903R90010
                        CBP/TRS 51/90
                        November 1990
Chesapeake Bay Coordinated
       Split Sample Program
        Annual Report, 1989
                  P^^^
                  Chesapeake
                         Bay
                     Program
                         Printed on Recycled Paper

-------
     Chesapeake Bay Coordinated
          Split Sample Program
          Annual Report, 1989
                  by Peter Bergstrom
                 November 14,1990

              Computer Sciences Corporation
                Chesapeake Bay Program
              410 Severn Avenue, Suite 113
               Annapolis, Maryland 21403
                   (301) 267-0061
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program

-------
EXECUTIVE SUMMARY
     Hie Chesapeake Bay Program is a  Federal-State partnership with  a goal
of  restoring the Chesapeake  Bay.   Its ambient  water quality  monitoring
program uses 10  different analytical  laboratories.    The Chesapeake  Bay
Coordinated  Split Sample  Program (CSSP),  initiated  in 1988, assesses  the
comparability of  the water quality  results from these  laboratories.   This
report sunoarizes CSSP results for 1989, its first full year of operation.
     The  CSSP  has  two main  objectives:  estimating  measurement  system
variability,   and  identifying  parameters  with   low  inter-organization
agreement.  The variability estimates are most useful  to data  analysts and
modelers  who need  confidence  estimates  for  monitoring  data.     The
identification of parameters with  low agreement is  used as  part of  the
overall Quality Assurance  program.   Laboratory  and program personnel  use
this  information  to  investigate  possible  causes of  the differences,  and
take  action  to  increase  agreement  if  possible.    Later  CSSP  results
document any improvements in inter-organization agreement.

     Estimates of measurement system variability  based on split sample data
show that some parameters have more variable results than others.   In some
cases  these  patterns  were  consistent  when  different  laboratories  and
sampling stations were compared.

     Inter-organization  agreement was  high  for  18 of the  23  comparisons
made   in  two  components.    Agreement  was  low  enough  to   recommend
investigation  for five parameters:  Total  Phosphorus (TP), Total  Dissolved
Phosphorus  (TOP),  Particulate  Carbon (PC),  Particulate Nitrogen  (PN),  and
Dissolved Organic Carbon (DOC).   Recommendations for  further investigation
were made when there were three or more inter-organization differences that
were   larger  than  within-organization   precision,  and  there  were
statistically  significant  inter-organization differences at  the  P  < 0.01
level.

     In all five cases of low inter-organization  agreement,  only one of the
four  organizations compared had  divergent  results.   In each case,  this
organization had  a  different analytical method or instrument  type,  and in
two cases (PC and PN) there was also a  difference in filter  type,   in three
cases  (TP,  TOP, and DOC) method changes have been made  to  increase inter-
organization  agreement.  The  other two   cases   (PC  and  PN) are  being
investigated  by  the  organizations involved  to  find  ways  to   increase
agreement.

     The  results  from the first  year  of  operation show that the  CSSP is
successful at achieving its goals.  The communication and cooperation among
participants  that  occurred  was  essential  to  getting  the  split  sample
results  translated  into actions that have  increased  inter-organization
agreement.
                                  ii

-------
ACKNCWLEDGMENTS

     The members of  the Analytical  Methods and Quality Assurance Workgroup
of  the  Monitoring Subcommittee made  many helpful suggestions used in the
analysis.   Rich  Batiuk,  Tina  Fletcher,  Joe  Macknis,  Nina  Fisher,  Bruce
Neilson, Carl Zimmermann, Bruce Michael,  and Steve Sokolowski made helpful
comments on  earlier  drafts of  the  manuscript.  All of  the laboratory and
program personnel involved took the time to familiarize themselves with the
program, run the samples,  submit the data,  and  study the  results of the
analyses.  Their continuing support is what makes the program work.
                                  iii

-------

-------
TABLE OF CONTENTS


EXECUTIVE SUMMARY ...........................  ii

ACKNOWLEDGMENTS ............................ ill

TABLE OF CONTENTS ...........................  iv

LIST OF FIGURES ............................  vi

LIST OF TABLES  ............................ viii

I. INTRODUCTION ............................   1

II. MfftHOoS ..............................   4
     A. COMPONENTS AND PARTICIPATING LABORATORIES ...........   4
          1. Mainstem and Tidal Tributaries component .........   4
          2. Tidal Potomac component  .................   4
          3. Fall Line component  ...................   4
     B. SAMPLE COLLECTION AND SPLITTING METHODS ............   4
          1. Mainstem and Tidal Tributaries component .........   4
          2. Tidal Potomac component  .................   5
          3. Fall Line component  ...................   5
     C. DATA ENTRY AND REDUCTION  ...................   6
          1. Mainstem and Tidal Tributaries component .........   6
          2. Tidal Potomac component  .................   6
          3. Fall Line component  ...................   6
     D. DATA ANALYSIS AND GRAPHING  ..................   6
          1. Preliminary test of splitting randomness .........   6
          2. Precision estimates  ...................   7
          3. Assessing inter-organization agreement ..........   7

III. RESULTS  .............................   9
     A. WITHIN-ORGANIZATION PRECISION AND ACCURACY  ..........   9
          1. Mainstem and Tidal Tributaries component .........   9
          2. Tidal Potomac component  .................   9
          3. Fall Line component  ...................  15
     B. INTER-ORGANIZATION PRECISION  .................  15
          1. Mainstem and Tidal Tributaries component .........  15
          2. Tidal Potomac component  .................  15
          3. Fall Line component  ...................  15
     C. INTER-ORGANIZATION AGREEMENT  .................  22
          1. Mainstem and Tidal Tributaries component .........  22
          2. Tidal Potomac component  .................  22
          3. Fall Line component  ...................  22

IV. DISCUSSION  ............................  37
     A. WITHIN-ORGANIZATION PRECISION AND ACCURACY  ..........  37
     B. INTER-ORGANIZATION PRECISION  .................  37
     C. INTER-ORGANIZATION AGREEMENT  .................  37
          1. Mainstem component ....................  37

                                   iv

-------
          2. Potomac component  	  38
          3. Fall line component	38

V.  SUMMARY AND CONCLUSIONS	38

VI. REFERENCES	39

-------
LIST OF FIGURES

Figure 1.      Chesapeake  Bay  Coordinated  Split  Sample   Program
               Components	2

Figure 2.      Schematic of operational flow of analyses, Coordinated
               Split Sample Program	3

Figure 3.      Split sample data for Total Dissolved Phosphorus (TOP),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	23

Figure 4.      Split sample data for Total Phosphorus (TP),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	23

Figure 5.      Split sample data for Particulate Nitrogen (PN),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	24

Figure 6.      Split sample data for Particulate Carbon (PC),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	24

Figure 7.      Split sample data for Silica (SI),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	25

Figure 8.      Split sample data for Nitrite (N02),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	25

Figure 9.      Split sample data for Nitrite + Nitrate (N023),
               from samples collected at Station CBS.3 (Mainstem),
               showing cruise means with precision bars	26

Figure 10.     Split sample data for Ammonium (NH4),
               from samples collected at Station CBS.3 (Mainstem),
               showing cruise means with precision bars	26

Figure 11.     Split sample data for Particulate Phosphorus (PHOSP),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	27

Figure 12.     Split sample data for Orthophosphate (P04F),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	27

Figure 13.     Split sample data for Dissolved Organic Carbon (DOC),
               from samples collected at Station CBS.3 (Mainstem),
               showing cruise means with precision bars	28
                                  vi

-------
Figure 14.     Split sample data for Total Dissolved Nitrogen (TON),
               from samples collected at Station CB5.3 (Mainstern),
               showing cruise means with precision bars	28

Figure 15.     Split sample data for Total Nitrogen (TN),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	29

Figure 16.     Split sample data for Total Suspended Solids (TSS),
               from samples collected at Station CB5.3 (Mainstem),
               showing cruise means with precision bars	29

Figure 17.     Split sample data for Ammonium (NH4),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	31

Figure 18.     Split sample data for Nitrite (N02),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	31

Figure 19.     Split sample data for Nitrite + Nitrate (N023),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	.32

Figure 20.     Split sample data for Total Kjeldahl Nitrogen Whole  (TKNW),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	32

Figure 21.     Split sample data for Orthophosphate (P04),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	33

Figure 22.     Split sample data for Total Phosphorus (TP),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	33

Figure 23.     Split sample data for Total Organic Carbon (TOC),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	34

Figure 24.     Split sample data for Total Suspended Solids (TSS),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	34

Figure 25.     Split sample data for Silica (SI),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	35

Figure 26.     Split sample data for Biological Oxygen Demand 5 day (BOD5),
               from samples collected at Station PMS-10 (Potomac),
               showing cruise means with precision bars	35
                                  VII

-------
LIST OF TABLES

TABLE 1:  Method Detection Limits at Mainstem Component  Laboratories,
     1989-1990	10

TABLE 2:  Method Detection Limits  at Potomac Component  Laboratories,
     1989-1990	11

TABLE 3: Method Detection Limits at  Fall  Line Component  Laboratories,
     1989-1990	12

TABLE   4:   Wi thin-organization  and  inter-organization  precision
     estimates,  Mainstem Component	13

TABLE   5:   Wi thin-organization  and  inter-organization  precision
     estimates,  Potomac Component	14

TABLE 6: Wi thin-organization precision estimates,  Fall  Line Component.    16

TABLE 7: Percent Recovery Data,  Mainstem Component,  1989   	   17

TABLE 8: Percent Recovery Data,  Potomac Component, 1989-90	18

TABLE 9: Percent Recovery Data,  Fall  Line Component,  1989-90	19

TABLE 10:  Standard  Reference  Material  Results,  Mainstem Component,
     1989	20

TABLE 11:   Standard  Reference  Material  Results,  Potomac Component,
     1989-90	21

TABLE 12:   Mainstem  Component  (Station CB5.3)  Split  Sample Results
     using Cruise Means (1987 -  1989)	30

TABLE 13:  Potomac  Component (Station  PMS-10)  Split  Sample Results
     using Cruise Means (1989 -  1990)	36
                                 viii

-------
I. INTRODUCTION

     The Monitoring Subcommittee of  the  Chesapeake Bay  Program initiated
the Chesapeake  Bay Coordinated Split Sample  Program (CSSP) in  1988.   Its
goal is  to assess  the comparability  of water quality results from the 10
analytical  laboratories  that participate  in the Chesapeake Bay Monitoring
Program  (Chesapeake Bay  Program 1989).   This goal  is  being achieved by
estimating  measurement system variability  and identifying  any  parameters
that have low inter-organization agreement.

     Estimates of  measurement system variability are useful to  data users
such  as   statisticians  and  modelers who  need  confidence   bounds  for
monitoring  data.    Although  split sample  results  do not  include sampling
variability,   they  are  the  best  estimate  available   of  total  system
variability for Chesapeake Bay water quality monitoring data.

     Identifying parameters  with low agreement enables  the organizations
involved  to investigate  any significant  differences  and take  actions to
raise  inter-organization agreement.    This might  involve  changing field
methods,  laboratory methods,  or both.    Because  results  of  field split
samples are affected by  both field and laboratory variability,  the terms
"inter-organization" and  "within-organization" are used rather  than "inter-
laboratory"  and "within-laboratory."   The organization  includes  all  the
elements  of  the  measurement system:  field  sampling,  sample  handling,
laboratory analysis, data handling, and the state  or municipal agency that
supervises the water quality monitoring program.

     The   CSSP  has  four   components,  each  including   three  to  five
laboratories  that  analyze  samples  from  similar  salinity  regimes  and
concentration  ranges  (Fig.  1).    Laboratories in  each  component  analyze
triplicate field split samples collected quarterly, following the specified
analysis flow  (Fig. 2).   Laboratory personnel send  the analytical results
to the EPA Chesapeake Bay Liaison Office (CBLO) in Annapolis for data entry
and analysis by Computer Sciences Corporation (CSC/CBLO)  staff.

     This  report   summarizes  the  results  of  three  of  the  four  CSSP
components  for 1989.    These components  are 1)  the Mainstem  and Tidal
Tributaries component, which analyzes estuarine samples  from  the mainstem
of the  Chesapeake  Bay; 2) the Tidal  Potomac component, which samples  the
tidal fresh portion of the  river;  and, 3)  the Fall  Line  component, which
samples the Susquehanna  River fall line  station.   The Virginia Mainstem
and Tidal  Tributaries  component,  which samples the tidal  fresh  portion of
the James River, did not operate between January 1989 and February 1990, so
it is not included  in this report.

     This  report  includes split  sample data  from September  1987  through
March 1990.  Early  1990 data were included  when  there were not enough data
through 1989 for statistical analysis.

-------
1
 4*
 O
U


 2
i
 Q.
C/3


I
13

'•3
 4)

 3

-------
       LARGE
       VESSEL

   (Aliquots split  in
   sequence: all Aliquot
   1 bottles, then 2, etc.)
                         Figure 2. Schematic of the Operational Flow of Analyses,
                                  Coordinated Split Sample Program
                Normal Laboratory
                  Quality Control
                    Procedures
Replicate Analyses
                **
                                               Triplicate Aliquots
                                            (sent to each laboratory)*
                                                   —-   —
                                 Analyze for
                              Routine Parameters
                           Analyze for
                       Routine Parameters
                                                               *(in-matrix estimate
                                                                 of field precision)
                                                                 Spike Sample
                                                                             ***
        Analyze for
     Routine Parameters
              Analyze for
           Routine Parameters
              ** (in-matrix estimate
                  of lab precision)
     Analyze for
  Percent Recovery

***(in-matrix estimate
      of accuracy)
               Deionized/distilled
                 water dilution
                                           EPA Standard
                                         Reference Material
                                                          Matrix water
                                                        dilution (if saline)
  Analyze for
SRM Parameter
                                                                           Analyze for
                                                                          SRM Parameter

-------
II. METHODS

A. COMPONENTS AND PARTICIPATING LABORATORIES

     1. Mainstem and Tidal Tributaries component

     This  component includes  the three  Chesapeake  Bay mainstem analysis
laboratories:  Chesapeake  Biological  Laboratory  (CBL)  in  Solomons,  MD,
Virginia Institute  of Marine  Science  (VIMS)  in Gloucester Point,  VA,  and
Old Dominion University (ODU)  in Norfolk.  It  also  includes  one tributary
laboratory, Maryland Department  of  Health and  Mental  Hygiene  (MDHMH)  in
Baltimore.   Starting  in June,  1990,  the  Virginia tributary  laboratory,
Division of Consolidated  Laboratory  Services  (DCLS)  in  Richmond, was added
to this component.   Split sample results from this component  were included
in two previous reports (Bergstrom 1989,  1990s).

     2. Tidal Potomac component

     This  component includes  three  analytical laboratories: MDHMH,  DCLS,
and the  EPA Central Regional  Laboratory (CRL)  in Annapolis.   Analyses at
CRL  are  conducted  by  District  of  Columbia  Department  of  Consumer  and
Regulatory  Affairs  (DCRA)  personnel  (referred to  as  CRL/DCRA).    Split
sample  results  from this component  were included in two  previous  reports
(Bergstrom 1989, 1990b).

     3. Fall Line component

     The Fall Line  component  includes  five analytical  laboratories: MDHMH,
DCLS,   the  United  States  Geological   Survey   (USGS)   in  Denver,  the
Pennsylvania Department of Environmental Resources  (PADER)  in  Harrisburg,
and the Occoquan Watershed Monitoring Laboratory (OWML)  in  Manassas,  VA.
DCLS does not currently participate in this component of the CSSP, but they
may do so in the  future.  Split sample results  from  this  component were
included in one previous CSSP  report (Bergstrom 1990c).

     All  of these  laboratories also  participate  in two-way split sample
programs  with USGS.    Data from these  programs  were  not  included here
because the goals and methods  of the USGS program are different from those
of the CSSP,  and many  of the  two-way split results have  been  analyzed by
others  (e.g., Kenney 1990) or  will be analyzed in  the future.

B. SAMPLE COLLECTION AND  SPLITTING METHODS

     1. Mainstem and Tidal Tributaries component

     A field crew  from the Maryland  Department of the  Environment (MDE)
collected quarterly water samples from the surface layer at Station CB5.3,
near Smith Point on  the  Maryland-Virginia line.  The  field  crew  followed
the splitting procedures  in the CSSP Implementation Guidelines  (CBP 1989).
The MDE field crew processed  and distributed samples  to  the two Maryland
laboratories  (CBL  and  MDHMH),  while  a  VIMS  field  crew processed  and
distributed samples to  the two Virginia  laboratories (VIMS and ODU).

-------
     Starting  in June  1989,  each  laboratory analyzed  a minimum  of four
samples  per cruise:  three aliquots  split  in the  field and  a laboratory
replicate  for  one of the aliquots.  One  exception  was CBL,  which received
four bottles  from the field crew.   Their "laboratory" replicate was split
from Aliquot  1 in the field until March  1990.   Some laboratories did more
than  one   laboratory  replicate:  ODU  analyzed  all  three  aliquots  in
triplicate—nine  samples per cruise.  Because CSC/CBLO staff received these
additional  replicate  data  after data entry was  almost complete, they were
only included  for Cruise 111.

     2. Tidal  Potomac component

     A  field  crew  from DCRA  collected quarterly  water samples  from the
surface  layer  at Station PMS-10, at Key Bridge  on  the Potomac River.  The
field  crew followed  the splitting  procedures  in  the  CSSP  Implementation
Guidelines  (CBP  1989)  starting in  May 1989.    The field crew  left whole
water  samples  in ice-filled coolers  at the designated dock.   Personnel
from each  laboratory  retrieved  the  coolers.   The field crew did not filter
any samples.   MDHMH  did laboratory filtration  for Total Suspended Solids
(TSS) only.   In the laboratory, DCLS  and CRL/DCRA  personnel also filtered
samples  for  Ammonium  (NH4),  Nitrite  (N02),  Nitrite  + Nitrate  (N023),
Orthophosphate (PO4F),  Total Dissolved Phosphorus (TOP), Dissolved Organic
Carbon  (DOC),  and  Silica  (SI).   CRL/DCRA and  DCLS both used pre-rinsed
Gelman cellulose  membrane filters with 0.45 micron pore size.  Samples were
received by the laboratories either  the same day they were collected or the
following  day.   The  March 1990  samples  were not  picked up  for  DCLS,  so
there are no DCLS results for that split sample.

     Starting  in May 1989,  each laboratory analyzed a  minimum  of  four
samples  per  cruise: three aliquots  (field replicates) split  in the field
and a laboratory  replicate for one of the aliquots.

     3. Fall Line component

     A field crew from  USGS-Towson  sampled the  Susquehanna River fall line
station and distributed samples  to  each laboratory  (except DCLS, which did
not participate).   The  field crew used USGS sampling procedures, including
flow-weighted  cross-sectionally integrated  samples.   Splitting was  done
with  a churn  splitter.   Field  filtration was  done with  a  0.45 micron
membrane  filter and  the nutrient  samples  shipped   to  USGS  and OWML were
preserved with mercuric chloride according  to USGS  standard protocol.  All
samples were  immediately placed  and kept on ice.   Samples for MDHMH and
PADER were delivered  to the laboratory the  day  of collection.   Samples for
USGS and OWML  were sent via priority mail  in  ice-filled coolers.   USGS
samples usually arrived in two days.  The samples sent to OWML arrived five
days later  with no ice  around  them, so their analytical  results  were not
reported.

-------
     The  Fall  Line  component generally  followed  CSSP  guidelines  (CBP
1989),  except each  laboratory received  less than  three aliquots  (field
replicates)  split  in  the field.    The  field  crew could  not  split  a
sufficiently  large  volume of water  accurately to provide three  aliquots.
Each laboratory  received two aliquots in  October 1989 and one aliquot in
March  1990.   Only  MDHMH  reported a laboratory  replicate for one  of the
aliquots.

C. DATA ENTRY AND REDUCTION

     1. Mainstem and Tidal Tributaries component

     Laboratory or program personnel submitted raw data on handwritten CSSP
Data  Submission  forms,  except  VIMS  personnel  submitted their  data  on
diskette  starting  in June, 1989.   CSC/CBLO staff transcribed and  entered
the handwritten data,  and data originators verified  the  printouts.   Field
and laboratory precision  and means over  the  three aliquots were  calculated
with SAS programs (SAS Institute 1985).

     2. Tidal Potomac component

     Laboratory or program personnel submitted raw data on handwritten CSSP
Data  Submission  forms.    CSC/CBLO  staff  transcribed  and  entered  the
handwritten  data.    Data  submitters verified  the printouts  through March
1990.  Field and laboratory precision and means for the three aliquots were
calculated with the SAS procedure MEANS (SAS Institute 1985).

     3. Fall Line component

     USGS-Towson  personnel submitted  the  Upper  Bay  data on  diskette for
October  1989 data and  in hard copy for March 1990 data.  CSC/CBLO staff
transcribed  and entered  the  handwritten  data,  transferred   the  diskette
data.  Data  submitters verified printouts of the data.  Field precision was
calculated with the SAS procedure MEANS (SAS Institute 1985).


D. DATA ANALYSIS AND GRAPHING

     1. Preliminary test  of splitting randomness

     Data were checked for the randomness  of the splitting procedures.  If
splitting was done correctly,  the  results for one of the aliquots should
not  be  consistently  higher   or  lower  than  the  results for  the  other
aliquots.  Since  the aliquots  are split sequentially, non-random splitting
would  probably result  in higher  results  for  solids and particulates in
Aliquot  3,  which  is drawn from  the lower  part of  the  splitting  vessel.
Splitting  randomness was checked with the Friedman  two-way  non-parametric
analysis of  variance, comparing the  results for the three aliquots for each
parameter  and sampling date.    None of  the parameters  had  statistically
significant  results  (P  >  0.03), showing that splitting was done randomly.

-------
     2. Precision estimates

     The  standard   deviation  (SD)  and  coefficient  of  variation  (CV,
standard  deviation/mean  x  100)   of  field  triplicate  results  estimated
within-organization  precision.    Since  the  field  replicates  are  usually
split  by  a  different organization  from  the  one doing  the  laboratory
analysis,   they  do  not  measure  only  "within-organization"  field  and
laboratory  precision,  but they  are considered  to  approximate it  for the
purposes  of  this  report.    The  CSSP  results also  include  laboratory
replicates, split in the laboratory just before analysis.   These were not
used to estimate within-organization precision because  they do not include
field  variability,   and  are  almost always  less variable  than  the  field
replicates.

     The means  of the  field  triplicate results were then used to calculate
the SD and CV of the results from different organizations for each sampling
date,  which  estimated inter-organization  precision.    For  the  Mainstem
component,  precision estimates  were calculated separately for  groups  of
four and three  laboratory means, including all the laboratories or only the
mainstem laboratories  (see above).

     The SD was positively correlated with the mean for several parameters,
and  usually the CV was not  affected  by  the  mean.   However,  the  CV was
sometimes affected  by  concentration as well.   It was positively correlated
with the mean in a  few cases,  and negatively correlated with the mean in a
few other  cases.   The negative correlation usually occurred  when the mean
concentrations  were  low.   Thus, neither precision  estimate should be used
in other analyses without  checking for concentration effects.  Because the
primary purpose of  the CSSP  is to assess inter-organization agreement,  a
detailed  analysis  of  precision  estimates  is  beyond  the  scope of  this
report.  The  author is currently analyzing fall line split sample data to
produce precision estimates  to  use in  calibrating  the Chesapeake Bay River
Input  computer  model.    Preliminary results of  this analysis  can  be sent
upon request.

     The Method Detection Limit  (MDL) was also used to estimate within-
organization precision, especially in  the graphs of the  data (see below).
At many  of the  laboratories,  the MDL  is  calculated from  three  times the
standard  deviation  of  seven  replicates  of  a low-level  sample,  so  it
estimates within-organization precision.

     3. Assessing inter-organization agreement

     Graphs of  the  split  sample results show which differences were larger
than the  within-organization precision.   Based on a discussion  with the
Analytical  Methods   and  Quality  Assurance Workgroup  (AMQAW)  on 4/24/90,
within-organization precision for  CSSP analyses is  estimated by the larger
of:  1) the Method Detection  Limit (MDL,  Tables 1-3); or,  2)  the standard
deviation  of  the  three aliquots  for  each  sample  which  estimates  field
precision.   Graphs  of  the  cruise  means for each  laboratory  show this
estimate as "precision bars."   Any laboratory  means with  non-overlapping

-------
precision bars  have differences that  are larger than  within-organization
precision.

     Statistical significance was assumed when the significance level (P)  <
0.01, rather than when P < Q.,05 as in the previous report (Bergstrom 1989).
Standard quality control procedures use the P - 0.01 level  as the "control"
or action level for precision and  accuracy charts (e.g., Montgomery 1985).

     A decision rule was developed to  identify which parameters had inter-
organization differences that were large and consistent enough to  warrant
investigation by  the  organizations involved.   The decision  is based  on
graphs  with  precision  bars  and  the   results  of   statistical   tests.
Investigation was recommended if:

     1)  three  or more sampling dates had  inter-organization  differences
     that were larger than within-organization precision; and,

     2) an  appropriate statistical test had a probability (P)  < 0.01 that
     the differences were due to chance alone, equivalent to  99% confidence
     that the observed difference was real.

The graphs show the magnitude of differences, while the  statistical  test is
more  sensitive  to  consistency of  the differences  over time.   Based  on
results  from  the Mainstem  component of  the  CSSP (see below),  parameters
identified by the combination of these two criteria usually  have different
field and/or laboratory methods at one of the laboratories  involved.

     A non-parametric statistical test was used to analyze  the split sample
data.   This test  assumes matched  (positively correlated)  samples,  since
this  is  inherent  in the split sample  design.  Comparisons  were done with
the   Friedman   two-way,  non-parametric,  repeated  measures  analysis  of
variance (ANOVA), which requires a minimum of 4 complete samples to  achieve
P -  0.01 (Siegel  1956).  The P < 0.01  standard  is  currently unattainable
for  most of the parameters  in the  Potomac  component  due  to  small sample
sizes.  The test was done with the Macintosh software package StatView 512+
(Brainpower, Inc. 1986) using exact P values from Siegel (1956) when sample
sizes were  small.   Below detection limit data were included  if they only
affected results from  one laboratory,  but no comparison was  made if two or
more  laboratories  had below  detection limit data,  because  this made the
rankings of the data ambiguous.

     The  analyses  for the  Mainstem component were  done  on  two groups of
laboratories,  because the  four  laboratories included  in  this component
differed  in  analytical methods.    The  three mainstem  laboratories  use
different  analytical  methods  than the  tributary laboratories.  Mainstem
laboratories measure  the dissolved and particulate  fractions  of nitrogen,
carbon,  and phosphorus and calculate  the  total  fractions, while tributary
laboratories measure  the total  and dissolved fractions and calculate the
particulate fractions  (D'Elia et al. 1987).   Data analyses and graphs were
done  for  all  four  laboratories and  also  for  the  three mainstem
laboratories,  because  of   this   difference   in  analytical methods.

-------
Participate  Carbon  (PC) comparisons  excluded  MDHMH results  because their
method only measures organic carbon.

     Split sample results  can also be analyzed by  comparing  the magnitude
of  inter-organization  CV  to  the  mean  within-organization  CV  of  the
different organizations.   This approach was used with Chesapeake Bay fall
line  split  sample  data by  Kenney  (1990),  adapted from  a  procedure  for
performance  testing given  by  Taylor (1987).    It  was  not  used  in  this
report for three reasons: Taylor's approach does not provide decision rules
for identifying parameters which  should  receive  further  investigation;   CV
comparisons could be biased by the dependence  of CV on mean concentration,
or by a  few high CV values; and,  this comparison method does not take  the
consistency  of  inter-organization  differences  into  account.    The
evaluation  of the  consistency of  inter-organization  differences  in  this
report is designed  to  facilitate actions by the  organizations involved to
increase inter-organization agreement.
III. RESULTS

A. WITHIN-ORGANIZATION PRECISION AND ACCURACY

     Two  estimates  of within-organization  precision  were used  in  this
analysis: the method detection limits (MDLs), listed in Tables 1-3; and the
precision of  field replicates, the  three  aliquots split in the  field and
analyzed  by the  same laboratory.  The  Methods  section describes how the
precision estimates were  calculated.   Percent  recovery data and results
from  Standard  Reference  Materials  (SRMs)  estimated  within-organization
accuracy.

     1. Mainstem and Tidal Tributaries component

     Table  4  gives  the  mean  SD and CV of  field replicates under  "Mean
within-organization  precision."    These precision estimates varied  among
parameters  in   data  from  the  same  organization,   as  well   as  among
organizations for  the same  parameter,  with CV  values  ranging from  1% to
45%.  In a  few  cases,  the  means  were inflated by a single high result, and
sample sizes varied slightly among organizations.

     Percent  recovery data  (Table  7),  although  limited,  show that  most
values were near 100%.  Results from SRMs (Table 10) from VIMS and ODU also
had percent recovery values (SRM  results/expected x  100) near 100%.   All
but three were between 90 and 110%.

     2. Tidal Potomac component

     Table  5  gives  the  mean  SD and CV of  field replicates under  "Mean
within-organization precision."  All CV values were at or below 20%,  except
for TSS data from MDHMH.   Percent  recovery data  (Table  8) and results from
Standard Reference Materials (SRMs, Table 11) estimated within-organization
accuracy.   Percent  recovery data  are  limited since DCLS  did not  submit
them, but most values were close to 100%.  Results from SRMs from CRL/DCRA

-------
TABLE 1: Method Detection Limits at Mainstem Component Laboratories, 1989-
1990.

                              Method detection  limits (mg/1)
Parameter1
NH4
N02
N023
TDN
PN (PON)
P04F
TOP
PHOSP
TP
DOC
PC
TSS
SI
CBL'
0.003
0.0002
0.0002
0.002
0.0105
0.0006
0.001
0.0012
-
0.24
0.063
1.5
0.01
DCLS"
0.04
0.01
0.04
-
-
0.01
0.01
-
0.01
1.0
-
1
0.1
MDfflW
0.008
0.002
0.02
-
-
0.004
0.01
-
0.01
0.5
(0.8, 5/89-
3/90
-
1
0.1
ODU*
0.0056
0.001
0.0025
0.05
0.05
0.005
0.005
0.007
-
0.5
0.24
2
0.023
VIMS"
0.01
0.0015
0.0021
0.040
0.029
0.0005
0.005
0.003
-
1.0
0.104
5
0.007
     NR4 •  ammonium,  NO 2 - Nitrite,  NO23  - Nitrite + Nitrate,  TDN - Total
     Dissolved  Nitrogen,  PN •  Particulate Nitrogen, PO4F  -  0rthophosphate
     filtered,  TOP •  Total  Dissolved Phosphorus,  DOC  -  Dissolved Organic
     Carbon,  PC - Particulate  Carbon,  TSS -  Total Suspended  Solids,  SI -
     Silica  (as SI).
     Calculated from:  3 x standard deviation  of  7  replicates  of the lowest
     concentration sample  encountered.   Limits verified  by CBL and ODU.
     Calculated as  2* of  full  scale,  except  carbon limits  from Method MDL
     in 40  CFR  Ft  113  App.  B  (7-1-87  Ed.).
                                   10

-------
TABLE 2:  Method Detection Limits  at Potomac Component Laboratories,  1989-
1990.

                  Method detection limits  (mg/1)
Parameter
NH4
N02
N023
TKNW
P04
TOP
TP
DOC
TOC
TSS
SI
BODS
CRL/DCRA
0.04
0.01
0.04
0.2
0.007
0.01
0.01
1.0
1.0
4
0.2
1
DCLS
0.04
0.01
0.04
0.1
0.01
0.1
(0.01)1
0.1
(0.01)1
1.0
1.0
1
0.1
1
MDHMH
0.008
0.002
0.02
0.1
0.004
0.01
0.01
0.5 (0.8 from 5/89-3/90)
0.5 (0.8 from 5/89-3/90)
1
0.1
0.5
     Th«ir low-l«v«l phosphorus system achi«v«s 0.01 mg/1,
     but this syst«» -was not r»
-------
xftuus j: necncx
1990.
Parameter1
NH4
M02
N023
TKNW/TKNF
P04F
TOP
TP
DOC
i uececcion ionics ac ra-LJ. lone uanponenc ijaooracories, j.y«»-
Method detection limits (mg/1)
FADER
0.02
0.004
0.04
0.2
0.005
0.02
0.02
-
DCLS
0.04
0.01
0.04
0.1
0.01
0.1
0.1
1.0
MDHMH"
0.008
0.002
0.02
0.1
0.004
0.01
0.01
0.5
(0.8,
uses
0.01
0.001
0.10
0.20
0.001
0.001
0.01
5/89-
3/90
OWML
0.01
0.01
0.01
0.10
0.01
-
0.01
—
TOC
1.0
1.0       0.5        0.1
         (0.8, 5/89-
               3/90
TSS
SI
BODS
1 1
0.1
1
1
0.1
0.5
1
0.1
1
0.04
1
   NH4 - a»»oniu»,  NO 2  - Nitrite, NO23 - Nitrite  +  Nitrate,  TKNP • Total
   Kj«ld»hl  Nitrog.n  Filt«r«d,   TKRW  -  Total  Kj«ld«hl   Nitrogen  Whole,
   PO4F • Orthophosph*t•  filtered,  TDP -  Total Dissolved Phosphorus, TP  •
   Total Phosphorus,  TOC  -  Total Organic  Carbon,  TSS »  Total Suspended
   Solids, SI - Silica  (as  SI).
   Calculated as  2% of  full  scale,  except  carbon Units  froa Method  MOL
   in 40 CFR Pt 113 App.  B  (7-1-87  Ed.).
                                 12

-------













4J
d

d
o
3-
o
u
•
d
3
•
*>
2
a
•
d
o
••4
a
u
b
Oi

d
o
•H
JJ
M
.04
d
•

u
0
u
w
a
•o
q

q
0
•H

M
1
D<
Li
f
a
5
*
.
3
2
H
d
e
•r*
•H
U
U
a
d
o
Jj
4
M
I
U
b
d


2


IB


|

~*
•
b


B



o
m



.
,3

b
O
h,
B



o
OT


Z







a
o
•H
•H
U
b
a

d
o
•H
4J
M
•H
d

O1
u
I
*»4
5
'j

d
2
X









a
£,


B


o
in





§
o



£


B



a
OT







9
g



m


B


a
OT


K



S5



B



a
OT

b
U
b
Bi
0



*
fl
qp


Ol

o
o
0



f*
*
0
in

^

o
o





^

o

0
0
o
o

0
to
o
**
o
o
e



fi
0


^4
f^
O
e
o



4
0
»


o

o
o




i


to



.
fl
m


to
ft
o
o
e




I






i






"
i-

o
o
o
o

1

1



1



to
01


^
o
0
0
o




T
-


o
o
o
o




01
g


m



T
0



r-

0
o
e



ft

fi
ft

•i
r4
O
o






"»
m

in
0
o
e

«
fl
^

ft
O
O
o



01
0»


Ol

0
o
0




0


to
fl
0
o
o



fl
Ol
g


to



",
o





ml
o
0



^
•
o


M

o
o






Ol
in

0
in
o
e

**
e
in
**
m
•w
m
0
o



m
Ol


^i
^
^i
o
0




o
•H

O
m

o
o




s
H


to r. i



Ol Ot
in 0
Ol




O| ^
O O 1
o o



fl ft 1
• •
oi r>
01 ft

m 0
fl Ol
O O 1
e o




*

to r- I
o m

in
fl O
o o I
0 0
1
to to
Ol ft 1
0| fl
fl fl
Ol
Ol 01
O O 1
o o

1

01 01 |
fi in


o
fi m
fl to
O fl i
0 0




o » •"•



fl fl fl
o m o
o o o
e o o



h.
Z Z O
Bi H Bi


49



*
^4
in


Ol
m
o
o
o



O|
•
^
0
fl

ft
Ol
o
o






m
fi

Ol
o
0
0

"
fl
fl
fl
H
O
o
o


**
o
Ol


o

fl
o
o




*
~

in
f*
o
o
o




Bi


in



.
f»
ot


0

0
o
o



fl
•
^
to

fl
fl
o
o






-t
Ol

o
o
a
o

in
•w
01
r«
O
o
o


^
f
m


^
fi
01
o
o




fl



^
o
0
e



Bi
M
§
Bi


to



.
01
fl


^
0
o
0
o



ot

to
to

to
01
o
o






«
o

01
o
o
o

to
fl
„
fl
0
m
o
o
o


"*
r-
^J
01

^4
0
Ol
o
o




o
•H

0

o
0
o




Bi
H


V to fl to



• • • 1
0 0 to 1-
m ft » fi



r-
0 « 0 to
01 fl 0 O
fl O to O



o in
1 1
01 0
in i*i

Ol
oi r»
r- o
1 1 • •
to O




.

oi f m
o » •»

o m
to oi m
O ft O
0 01 0

» to fl to
oi fi H r-
oi r» » o
Ot 04
0m o
fl O 01 O
O O -9 O


^ 1 ^ 0
O Ol 0|
• 1 • •
01 Ol to
01


m fi
^ fi *v
O fl O
• 1 • •
0 fl O




to 0 o oi
fl fl


fi oi oi r-
01 in fi o
oi o r- o
o o o o




U I/I
a Bi H in


*> «
fi **4
•
•* d
U 0
•M «

• 0
0 •
U b


d
s!
u •**
. •
d M
0 -H
**4 O

4 O*
. 14
'.?
•o d
^2
« -*4
•o *
c

• t)
•
• "
4
Q ^
"* "3
O
*• «
23
^s
s:
fT fi
2 ••<
g-o
89 J
^ •
iS
ss
H
•O g
• b
•a o
-1  d

4 H
*J
•3 *
4J ~
•H O
• 0
fl «
d
0 •
" 9
9 O

O fl
T3 ~*

0 0
i^ -H
• 4J
a «
•H
• >
4J
O «4
SB o
•
jj
*•
d
°

^
'
M
*


II

d
o
•H
n

u

b
Oi

d
o

•M
M
•H
q

CP
u
^
i,
4J
•H

•
•
|:
• «
• o>
w d
• ••«
•H Oi
"o, «

2-
• u

*<
• n
O A
2 •
3"
" n
fi
9 •
01 -U

u u

• "*
5 •*
^j
*"
s
d S

u n
• B
b 0

•
0
So

g
9 o
0 .H
TJ -H
• U
M •
• h
a Oi
d

2

S3
M


*
41*
O


N
9

B

fl

2

o
u

a
J3
4J

4J
3
O
J3
4J
S
..
JJ
0
Ol
§
—
8
b
(X
0
Oi
a
u
q
•H
^
•J
•1
ttl

3
"3
>

A
Oi
J3
S
JQ
•o

^J
e
•H

• O
U fl
• 01
a
U! 0
C 9

IB


*•<
13

-------
   o

   M
   •H
   U

 •  U
„  aj



S  §
i
   M
U  f4


u  I


•  U
O
o.
 -  a
«  -H
               m

               o>
      O
      Ul
         o
         o
                  •a  a
                  •4  O
                           Ol


                           O
   s
I  §


•I  O
H
•H  U
e  a

u  o

?  3
u
•  N
4J  -H

5  g

•o  Z


S  I
a  -H
O  JB
•H  41

«  -s
H

•«  S
      Q
      Ul
         O

         o
            m
            o
            o
            o
   A
   IN
   O


   O
r>  
g  g
                        04

                        H
                              U)
                              V)

                              H
                                      ! " o o

                                         •o -a
                                      I ^ • •

                                       <=>(•«
                         2 *» 5 2
                         s^^i
                         -* w • «
                         flsa-3
                                      • • o " o-

                                     315325
                                     o -S *» a 3
                                     6 W H -H Q,
                                     00  « •
                                     w u . •

                                     **  -o •* JS

                                     - • • S1 "
u  g  u
O-o^O

** § "3 «**

"2 *J ° •" S
^ * M *^ ^
3 -H 5 a Q.
5 > S ••* •
u • ' u •
                                      • •»-••* u
                                      5 S -8 ~ •-
                         ««:*-
                         tm
                         "*" 3 5 5 »
                    »':"§
                    O   " -H H
                    ^ BI  « a
                    • q 
-------
show good agreement with  the  expected  results,  and all but one result (the
last P04F result) were within the 95% confidence intervals for the SRMs.

     3. Fall Line component

     Field  precision  was estimated  from the  standard deviation  of field
duplicate  aliquots analyzed  for the  October  11,  1989  Upper Bay  sample
(Table  6).   Although  based on  results from a single sampling  date,  the
results are generally similar to those from the  Potomac  component  (Table
5).  Percent recovery data (Table 9) were only reported by FADER and MDHMH;
most values were close  to  100%.   No SEN  results were reported  for  this
component.
B. INTER-ORGANIZATION PRECISION

     The  tables of  inter-organization  precision give  both  the  standard
deviation  (SO)  and  coefficient of variation (CV) of  the mean results from
split samples  for  each sampling date.   The data user will  have to decide
which precision estimate  is best for their application  (see Methods for a
definition and discussion of each estimate).

     1. Mainstem and Tidal Tributaries component

     Table  4  lists  SD  and CV estimates  under "Mean  inter-organization
precision."    Although parameters  with  low inter-organization precision
tended to  have low inter-organization agreement, this correlation was not
found  in  all  cases.   Three  of  the  five  parameters  with statistically
significant  inter-organization differences (TP,  TOP,  and DOC;  see below)
had high  CV values (> 50%), while the  other two parameters in that group
(PC and  PN) had lower CV  values.  Three  parameters with  high agreement
(NH4, PHOSP, and TSS)  also had mean inter-organization  CV values  over 50%
when four organizations were included.

     2. Tidal Potomac component

     The  mean  inter-organization  precision estimates   for Potomac  data
(Table 5) varied from  CV values of 5% for NH4  to 41% for TSS, and TKNW had
the next highest CV value.  Due to small sample sizes, more data are needed
to determine  if there are  consistent  differences among  parameters in CV.
The parameter  that had  the lowest  inter-organization agreement  based on
graphing and ANOVA, N023 (see below), had one of the lowest CV values.

     3. Fall Line component

     No estimates were possible due to limited and missing data for 1989.
                                   15

-------






















•

a
*
a
i
o
u
B
3

— i
h.
^
»
2
2
•H
*
0

H
e
•H
U
b
ft
§
•H
*>
N
•H
a
8.
w

I
a
A
•H
*

^
g

































B
0
n
•H
U
b
a

o
*f4
4J
M
•H
S
tr
?**

B
4J
•H

S








b
^
!
2
































Ui
(9
S









U
3








a

Q
jjr






































w
B


a
n









a
U)





B




a
U)



































ot4ooiNO>r4or4«oo
ioo««oaoor-iflo
(S H m »< «
o P* »4  -•
'U o - •
1! " a S
H On
•H « -1
B • •
* M. O **
5>g «
b u o
o 3 -H
b B * "ft
• o a
•U -H a T>
B 4J 3
M'? " •
J -S -o rl
"3
^^15
> * «
"••3 *"
•2l S-
« 3 > -
"* Ml O *"*
^4 * 3
• - *
* 2 •
s • u

• a"° a
S at *>
7*4
1 .2 °
•o « o. o
3 " • 0
*u  _j >-* C
0 g *B .2
•• .5 « M
a " « -H
• X U
4J JJ X •
o o a b
z e v) Qi
16

-------
TABLE 7: Percent Recovery Data, Mainstem component,  1989.


Parameter   Laboratory   	Percent Recovery

TOP


TP
SI


N02


N023


NH4


PHOSP

DOC

P04F


TON


CBL
HDHMH
VIMS
MDHMH
CBL
MDHMH
VIMS
CBL
MDHMH
VIMS
CBL
MDHMH
VIMS
CBL
MDHMH
VIMS
CBL
VIMS
CBL
MDHMH
CBL
MDHMH
VIMS
CBL
VIMS
June 89
97
—
100
-
_
93
87
99
92
96
96
114
108
107
144
96
100
100
107
79
90
120
98
98
92
Sept 89
102
100
87
112
_
95
-
99
100
100
105
116
91
105
102
101
_
89
_
89
_
100
90
100
79
Dec 89
_
102
87
100
_
93
88
••
—
103
^^
—
95
^
94
101
_
—
_
122
^
72
100
w
85
Not*:  Percent  recovery  data  are  only  possible  for   directly  measured
paraaeters.   There  is  no way to  spike  parameters  don* in th* CHN  analyzer
(Particulate  Carbon, PC  and  Particulat* Nitrogen,  PN).  ODU did  not  report
any  p*rc*nt  r*cov*ry data,  and CBL  did not report  p*rc*nt  recovery  data
after Sept.  89.   TOP » Total Dissolved Phosphorus,  TP » Total  Phosphorus,
SI • Silica, NO2 - nitrite, N023 » nitrite + nitrate,  NH4 - ammonium,  PHOSP
•  Particulate   Phosphorus,  DOC  »   dissolved  Organic  Carbon,   P04F   »
0rthophosphat• filtered, TDN »  Total  Dissolved  Nitrogen.
                                   17

-------
TABLE 8: Percent Recovery Data, Potomac Component, 1989-90.
Parameter   Laboratory
                                Percent Recovery
                           5/1/89   6/12/89
                                    9/11/89   f/8/90
                                        3/5/90
NH4


N02


N023


TKNW


P04


TCP

TP


DOC

TOC


SI
CRL/DCRA
MDHMH

CRL/DCRA
MDHMH

CRL/DCRA
MDHMH

CRL/DCRA
MDHMH

CRL/DCRA
MDHMH

CRL/DCRA

CRL/DCRA
MDHMH

CRL/DCRA

CRL/DCRA
MDHMH

CRL/DCRA
MDHMH
140

110
 98

105
102

100
144
116

 82


103

136
107
108

108
100

 85
 95

117
 98

 96
106
115
104
 91
 99

111
 93
102

116
100

106
108

 67
100

 96
112

 95

 83
 76

 86

 92
 92

 75
102
110

102
100

 85
102

109
 98
136

100

100
100

108

115
 93


 95
 86
 76

 96
 95
 98
104

 98
 94

102
100

105

104
103

138
Not*:  Percent  recovery data are  not  possible  for TSS  analysis.   DCLS did
not report any percent recovery data.  TOP ~ Total Dissolved Phosphorus, TP
• Total  Phosphorus,  SI - Silica,  NO2 -  Nitrite,  NO23  - Nitrite + Nitrate,
TKNW  -  Total  Kjeldahl  Nitrogen  Whole,   NH4  •  Ammonium,  DOC  -  Dissolved
Organic  Carbon, TOC -  Total Organic Carbon, PO4 « Orthophosphate.
                                   18

-------
TABLE 9: Percent Recovery Data, Fall Line Component, 1989-90.
Parameter
NH4
N02
N023
TKNW
TKNF
PO4F
TOP
TP
DOC
TOC
SI
Laboratory
PADER
MDHHH
PADER
NDHMH
PADER
NDHMH
PADER
NDHMH
PADER
MDHNH
PADER
NDHMH
PADER
NDHMH
PADER
NDHMH
MDHMH
NDHMH
PADER
MDHNH
MDHNH
PADER
MDHMH
Percent Recovery
10/11/89 3/28/90
100
100
100
96
100
101
106
100
128
100
102
97.5
100
100
100
104 94
95
100
92 112
103
- -
Hot*: Percent  recovery  data are not possible  for  TSS  analysis.  DCLS, USOS
and OHML  did  not report any  percent  recovery data.   TDP  » Total Dissolved
Phosphorus,  TP  -  Total Phosphorus,  SI  « Silica,  NO2 -  Nitrite,  NO23  -
Nitrite  + Nitrate,  TKNW  -  Total  Kjeldahl  Nitrogen   Whole,  TKNF  - Total
Kjeldahl Nitrogen Filtered,  NH4  «  Ammonium,  DOC » Dissolved Organic  Carbon,
TOC • Total Organic Carbon,  P04  -  0rthophosphate .
                                   19

-------
TABLE 10: Standard Reference Material Results, Mainstem Component, 1989.
Para-    Date    Laboratory     Distilled matrix       Estuarine matrix
meter	Results  % Recovery    Results   % Recovery
TOP
N023
NH4
PHOSP

DOC

PO4F



TON
 6/89
 9/89
12/89
12/89

 6/89
 9/89
12/89
12/89

 6/89
 9/89
12/89
12/89

12/89

12/89

 6/89
 9/89
12/89

 6/89
 9/89
12/89
12/89
VIMS
VIMS
VIMS
ODU

VIMS
VIMS
VIMS
ODU

VIMS
VIMS
VIMS
ODU

ODU

ODU

VIMS
VIMS
VIMS

VIMS
VIMS
VIMS
ODU
0.072
0.074
0.074
0.213
0.206
0.203
0.0397

0.164
0.183
0.181
0.041

0.37

4.07

0.050
0.047
0.051

0.253
0.217
0.323
0.343
 96.0
 98.7
 98.7
106.5
103.0
                                           101
                                            99
   .5
   .3
 82.0
                                            91,
                                            90,
102.5

 94.9

 93.3

100.0
 94.0
102.0

101.2
 86.6
129.2
107.2
0.080
0.074
0.073
0.208

0.205
0.189
0.189
0.196
0.201
0.218
0,
0,
050
048
0.053

0.266
0.287
0.231
          106.7
           98.7
           97.3
           95.9

          102.5
           94.5
           94.5
           98.0
          100.5
          109.0
100.0
 96.0
106.0

106.2
114.8
 92.2
Not*: CBL  and  HDHMH  have not reported any  SRM  results.   Results •r• given
for  diluted  samples,  diluted either  with  disti11ed/deionized or estuarine
water.   Confidence  intervals  are  not  given  due  to  the  dilution.   ODU
results for PHOSP are for a  PO4P standard diluted with IN HC1.  TOP - Total
Dissolved  Phosphorus,  NO23  »  Nitrite + Nitrate,  NH4 - a»»oniu»,  PHOSP •
Particulate  Phosphorus,   DOC  »   Dissolved  Organic  Carbon,   PO4P  »
Orthophosphate filtered, TDK • Total  Dissolved Nitrogen.
                                   20

-------
TABLE 11: Standard Reference Material Results, Potomac
                                                     nt, 1989-90.
Para-
 meter
Date
Laboratory
    Results (mg/1)
                      Expected
                               Distilled
                              95% CI1
NH4
N023
TKNW
PO4F
TOP
TP
TOC
6/89
9/89
1/90
3/90

5/89
6/89
9/89
1/90
3/90

9/89
1/90
3/90

5/89
6/89
9/89
3/90

1/90
3/90

6/89
9/89

5/89
6/89
9/89
1/90
3/90
  CKL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA

  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
  CRL/DCRA
1.90
1.90
1.90
1.90

1.43
1.43
1.43
1.43
1.43
5.
4.
00
78
                                  4.78
  .35
  .35
  .35
  .35
1.00
1.03
  ,50
  .50
6.1
6.1
6.1
6.1
6.1
               1.88
               1.80
               1.84
               1.93

               1.32
               1.32
               1.38
               1.35
               1.29
5.
5,
4,
70
05
90
               0.327
               0.331
               0.326
               0.401

               1.00
               0.924
                .53
                .60
               9.2
               7.3
               7.1
               7.5
               6.9
1.68
1.68
1.68
1.68
1.28
1.28
1.28
1.28
1.28
- 2.12
- 2.12
- 2.12
- 2.12
- 1.56
- 1.56
- 1.56
- 1.56
- 1.56
3.88 - 6.02
3.70 - 5.77
3.70 - 5.77
          0.
          0,
          0.
          0.
          33
          33
          33
          33
          0.89
          0.89
       0.37
       0.37
       0.37
       0.37

     - 1.21
     - 1.21
           ,30
           ,30

           ,50
           ,50
           ,50
           ,50
                 76
                 76
               9.32
               9.32
               9.32
               9.32
                                                             3.50 - 9.32
   Provided  by  EPA Environmental Monitoring  and  Support  Laboratory  (EMSL)
     Cincinnat i.
Not*: DCLS  and  MDHMH  have not  reported  any SRM  results.   NH4  » ammonium,
N023  "  nitrite  +  Nitrate,  TKNW » Total  Kjeldahl Nitrogen Whole,   PO4P -
0rthophosphat•  filtered,  TOP  »  Total   Dissolved Phosphorus,  TP  -  Total
Phosphorus, TOC » Total Organic Carbon.
                                   21

-------
C. INTER-ORGANIZATION AGREEMENT

     1. Mainstem and Tidal Tributaries component

     Cruise means with precision bars for each parameter are  shown in Figs.
3-16.   Five  parameters out of 14 analyzed  had three or more cruises  with
non-overlapping  error  bars:   Total  Dissolved  Phosphorus   (TDP),   Total
Phosphorus (TP),  Particulate Nitrogen  (PN),  Particulate Carbon  (PC),  and
Dissolved Organic Carbon (DOC).

     Friedman ANOVA  performed  on cruise means  assessed inter-organization
agreement  and determined  which parameters  had statistically  significant
inter-organization differences.   The  Friedman ANOVA  results  (Table  12)
showed  that   the  same  five parameters  (TDP/  TP,  PN,  PC,  and  DOC)  had
statistically significant  inter-organization  differences (P  < 0.01).   The
first  two parameters  had  significantly higher  results from MDHMH,  while
the two participate  parameters had  significantly higher results  from CBL.
DOC results  were significantly  lower  at MDHMH, due to a series  of  below
detection  limit values starting  in  June 1989  (Fig. 13)  after they started
using a new DOC instrument.

     2. Tidal Potomac component

     Cruise  means with precision bars  for  each parameter plotted against
time  show inter-organization  agreement (Figures 17-26).   Two  parameters
out of  10  graphed, N023  and TP,  had three or more sampling dates with non-
overlapping  precision  bars.  N023  samples  (Fig. 19) were from unfiltered
samples at MDHMH and  filtered samples  at the other two laboratories.   TP
results  had  non-overlapping precision  bars  between   MDHMH  and  CRL/DCRA
results  on  three dates  (Fig.  22).    The  other  parameters  had  inter-
organization  differences  that   tended  to  be  smaller  than within-
organization precision.  Two parameters  are not shown  due  to missing data:
TDP and DOC.

     The  Friedman ANOVA results  (Table  13) showed that none of  the  nine
parameters  analyzed  had  statistically   significant  inter-organization
differences  at  the P  <  0.01 level,  although this significance  level was
only  possible when N  -  4.  N023 results were the closest  to  statistical
significance  (P  - 0.042).   Below detection limit values at  DCLS prevented
the analysis of  TP  results,  and missing data ruled out analysis of  BOD5
results.

     3. Fall Line component

     No analyses were possible due to limited and missing data for 1989.
                                   22

-------
FIGURE 3.   Split sample data for Total Dissolved Phosphorus (TDP), from samples collected
            at Station CBS.3 (Mainstem), showing cruise means with precision bars.
        0.10
   ^i   0.08 •
   E
    •%
   M

   J    0.06
—Q—  TDP_CBL
—•—  TDP~MDH
—O—  TDP_ODU
	A—  TDP~VIM
   "3    0.04 '
            66   70   74    78   82   86   90    94   98   102  106   110
                                  CRUISE and DATE
FIGURE 4.  Split sample data for Total Phosphorus (TP), from samples collected at Station
            CB5.3 (Mainstem), showing cruise means with precision bars.
                                                 TP_CBL
                                                 TP'MDH
                                                 TP_ODU
                                         —Ar—   TP VIM
                                                       98   102   106   110
                                                           s
                                  CRUISE and DATE

                                         23

-------
FIGURE 5. Split sample data for Paniculate Nitrogen (PN), from samples collected at Station
           CB5.3 (Mainstem), showing cruise means with precision bars.
         OJO
         0.25
    £   0.20
    e

    |   0.15  '
    Z

    •i   o.io  •

         0.05
         0.00
               PN_CBL
               PN'MDH
               PN_ODU
               PN'VIM
                (No precision shown for MDHMH)
             66    70   74    78   82   86    90   94    98   102   106   110
               i                 £         p   s   1         *     i     §
               v)                 S         OQS         2     to     a
                                   CRUISE and DATE
 FIGURE 6.  Split sample data for Particulate Carbon (PQ, from samples collected at Station
           CB5.3 (Mainstem), showing cruise means with precision bars.
     .
     4^
     «
     eu
           1.4
1.1 •
1.0 •
0.9 '
0.8 '
0.7
0.6
0.5 1
0.4
0 J •
0.2 •
0.1 •
0.0
   66
                           PC_CBL
                           PC~ODU
                           PC VIM
                    70    74   78    82   86   90    94   98   102   106  110
                                    CRUISE and DATE
                                          24

-------
FIGURE 7. Split sample data for Silica (SI), from samples collected at Station CB5.3 (Main-
           stem), showing cruise means with precision bars.
  CA
  CA
                                                  SI_CBL
                                                  SI~MDH
                                                  SI_ODU
                                                  SI'VIM
                                                       Note: Cruises 81 and 94 had
                                                       below detection limit values.
                                 CRUISE and DATE

FIGURE 8.  Split sample data for Nitrite (NO2), from samples collected at Station CB5.3
            (Mainstem), showing cruise means with precision bars.
       0.025
       0.020
        NO2_CBL
        NO2~MDH
	At—  NOZ'VIM
       0.000
            66    70   74    78   82    86   90    94   98   102   106  110



                                   CRUISE and DATE

                                           25

-------
FIGURE 9. Split sample data for Nitrite + Nitrate (NO23), from samples collected at Station
           CB5.3 (Mainstem), showing cruise means with precision bars.
   -S
   2
                  -O—   NO23_CBL
                  -•—   N023~MDH
                  -O—   NO23_ODU
                 	A—   NO23~VIM
0.20

0.18

0.16

0.14  •

0.12  '

0.10

0.08

0.06

0.04

0.02

0.00
                                  CRUISE and DATE
 FIGURE 10. Split sample data for Ammonium (NH4), from samples collected at Station CB5.3
             (Mainstem), showing cruise means with precision bars.
    •%,
   |
   <
                                                NH4_CBL
                                                NH4~MDH
                                                NH4_ODU
                                                NH4~VIM
                            78   82   86    90   94    98   102   106  110
                                   CRUISE and DATE
                                         26

-------
FIGURE 11. Split sample data for Paniculate Phosphorus (PHOSP), from samples collected at
           Station CB5.3 (Mainstem), showing cruise means with precision bars.
                         PHOSPCBL
                         PHOSPMDH
                         PHOSPODU
                 —£r—  PHOSPVIM
                                 CRUISE and DATE
FIGURE 12. Split sample data for Orthophosphate (PO4F), from samples collected at Station
            CB5.3 (Mainstem), showing cruise means with precision bars.
       0.050
    eo
    Q.
   i
    a.
    o
                                                             P04F_CBL
                                                             P04F~MDH
                                                             PO4F"viM
                                                     Note: All cruises had below
                                                     detection limit values.
                                 CRUISE and DATE
                                         27

-------
FIGURE 13. Split sample data for Dissolved Organic Carbon (DOC), from samples collected at
            Station CB5.3 (Mainstem), showing cruise means with precision bars.
          5.0
    e
    5
    g
    i
    o
    1
    i
    .2
    Q
      4.5 •

      4.0 •

      3.5 •

      3.0 '

      2£ •

      2.0 '

      1.5

      1.0 1

      0.5

      0.0
                           DOC_CBL
                           DOC~MDH
                           DOC~ODU
Only one cruise (94) had data
for a 3 -way comparison.
             66    70   74    78    82   86    90    94
               &                  8         3  S   8
                                                      98   102  106   110

                                        O   Q   Jg         2      «o     Q
                                 CRUISE and DATE
 FIGURE 14. Split sample data for Total Dissolved Nitrogen (TON), from samples collected at
             Station CB5.3 (Mainstem), showing cruise means with precision bars.
         0.60

         0.55

         0.50 -j
I   0-45
         0.40 •
     M
    i
    2
    •5    OJ5  '
    Q
    3
     OJO •

     OJ15 '
         0.20
                      TDN_CBL
                      TDN~MDH
                      TDN'ODU
                      TON VIM
                                      No precision shown for MDHMH, too wide
             66    70   74    78   82    86   90    94    98    102   106   110
               r~                   23        2op2i         o\o2!
                                     CRUISE and DATE

                                           28

-------
FIGURE 15. Split sample data for Total Nitrogen (TN), from samples collected at Station
            CB5.3 (Mainstem), showing cruise means with precision bars.

          i .2 ^
          1.1
          1.0
          0.9 1
          0.8
          0.7 '
          0.6 •
          0.5
          0.4 H
          0.3
          0.2 1
          0.1
          0.0
                                       TN_CBL
                                       TN'MDH
                                       TN_ODU
                                       TN~VIM
             66   70    74   78    82    86    90   94    98   102   106   110


                                  CRUISE and DATE
FIGURE 16. Split sample data for Total Suspended Solids (TSS), from samples collected at
            Station CB5.3 (Mainstem), showing cruise means with precision bars.
          26
    T3
    1
    i
   3
24
22 1
20
18 1
16
14 •
12 •
10 •
 8-
 6
 4'
 2-
 0
                           TSS_CBL
                           TSS_MDH
                           TSS_ODU
                           TSS~VIM
             66    70   74    78    82   86
90
                                    I
                                        94
98   102   106   110
                                                            Os
                                                            2
                                   CRUISE and DATE
                                         29

-------
TABLE  12:   Mainstem  Component (Station CB5.3)  Split Sample  Results using
Cruise Means  (1987 -  1989).
Parameter   N
Laboratory Means (mg/1)
P values1

NH4
N02
N023
TEN
PN
TN
P04F
TOP
PHOSP
TP
DOC
PC
TSS
SI

8
62
32
6
6
7
83
8
5
6
4
6
3
6
CBL
0.0181
0.00756
0.110
0.398
0.152
A
0.525
0.0036
0.0071
A
0.0138
0.0227
A
2.81
0.840
A
5.1
0.297
MDHMH
0.0370
0.0089
0.102
0.421
0.114
0.633
0.0091
0.048
B
0.0320
0.0722
B
1.15<
A
_5
10.6
0.442
ODU
0.0176
-
0.102
0.388
0.112
0.479
-
0.015
B
0.0181
0.0322
3.63
B
0.686
17.5
0.382
VIMS
0.0203
0.00828
0.102
0.439
0.105
B
0.523
0.00071
0.0084
A
0.0124
0.0218
0.588
B
15.6
0.404
4 way / 3 way
0.051/0.285
- /0.184
0.608/0.36
0.532/0.43
0.0074/0.0055
0.28 /0.085
- /MDL3
0.0011/0.079

0.47 /0.17
0.0055/0.142

- /0.0046
- /0.0017
0.148/0.194
0.016/0.052
     Underlined  P  values  w*r«>  statistically significant ( P_ < 0.01, Friedman
     2-way  ANOVA"  on  cruise   Means,  using  exact  probabilities   for  3-way
     comparisons.   Laboratory Beans  with  different letters  below then had
     statistically  significant  pairwise  differences   (expe r iment wi s e  P_   <
     0.01),  otherwise  they did not differ.  When  there were data from  four
     labs,  3-way comparisons  omitted  MDHMH data.
     Only using  data from cruises  that  had values above detection limits.
     Too many  values were below  the MDL to make a comparison.
     MDHMH  data  were mostly below  detection due to a faulty instrument.
     MDHMH  data  were excluded  because they included only organic carbon.
                                   30

-------
FIGURE 17.  Split sample data for Ammonium (NH4), from samples collected at
             Station PMS-10 (Potomac), showing cruise means with precision bars.
    I
     E
     I
0.20

0.18 -

0.16 -

0.14 -

0.12 -

0.10 -

0.08 '
0.06 -

0.04 -

0.02 -

0.00
                          NH4_CRL
                          NH4_DCL
                          NH4~MDH
                        £
                                   i
                                   Gd
                                                                 I
FIGURE 18.   Split sample data for Nitrite (NO2), from samples collected at Station
              PMS-10 (Potomac), showing cruise means with precision bars.
         0.040
                                                                  N02_CRL
                                                                  NO2_DCL
                                                                  NO2 MDH
        0.000
                        I
                                   u
                                   en
                                             |
                                                                 y?
                                          31

-------
FIGURE 19. Split sample data for Nitrite + Nitrate (NO23), from samples collected at Station
            PMS-10 (Potomac), showing cruise means with precision bars. MDHMH samples
            were unfiltered, other samples were filtered (see text).
2.0

1.8

1.6

1.4

L2

1.0

0.8

0.6
    i:    0.4 -
    Z
          0.2 H

     2
           0.0
                                                         NO23_CRL
                                                         NO23_DCL
                                                         NO23 MDH
                                  i
                                             CA
                                                       I
 FIGURE 20. Split sample data for Total Kjeldahl Nitrogen Whole (TKNW), from samples
             collected at Station PMS-10 (Potomac), showing cruise means with precision
^ ^



b
     I
     2
     ^5
     s?
 1.0

 o^

 0.8

 0.7

 0.6

 OJ

 0.4

 0.3

 OJ

 0.1

 0.0
                          TKNW_CRL
                          TKNW.DCL
                          TKNW'MDBI
                                   1
                                   g
                                                             I
                                           32

-------
FIGURE 21. Split sample data for Orthophosphate (PCM), from samples collected at Station
            PMS-10 (Potomac), showing cruise means with precision bars.
                                                            PO4F_CRL
                                                      -•—  PO4F_DCL
                                                            PO4W MDH
 FIGURE 22.  Split sample data for Total Phosphorus (TP), from samples collected at Station
             PMS-10 (Potomac), showing cruise means with precision bars.
                                                                TP_CRL
                                                                TP_DCL
                                                                TP MDH
                                          33

-------
FIGURE 23. Split sample data for Total Organic Carbon (TOG), from samples collected at
            Station PMS-10 (Potomac), showing cruise means with precision bars.
    U
     i
     «
     u
     w
     2
     &
73
7.0
6.5
6.0
53
5.0
4.5
4.0
3.5
3.0

2.0 '

1.0
0.5
0.0
                                                                 TOC_CRL
                                                                 TOcfDCL
                                                                 TOC MDH
                        |
                                  Cd
                                  CA

 FIGURE 24. Split sample data for Total Suspended Solids (TSS), from samples collected at
             Station PMS-10 (Potomac), showing cruise means with precision bars.
    JO
    "o
     I
    CO
    s
                          TSS_CRL
                          TSS_DCL
                          TSS'MDH
                                            3A

-------
FIGURE 25. Split sample data for Silica (SI), from samples collected at Station PMS-10

            (Potomac), showing cruise means with precision bars.
    CM
     en
     at
     a
    C/3
          4.0




          3.5 •




          3.0 •
        SI_CRL

—•—  SI_DCL

        SI'MDH
FIGURE 26. Split sample data for Biological Oxygen Demand 5 day (BODS), from samples

            collected at Station PMS-10 (Potomac), showing cruise means with precision bars.

            CRL/DCRA data from 05MAR90 were added to the figure.
     O
     B

     i
      I
     O
     ^»

     "o
                          BOD5.DCL

                          BOD5~MDH
                        I
                 I
ac
a.
u
03
                                          35

-------
TABLE  13:  Potomac  Component (Station  PMS-10) Split  Sample Results using
Cruise Means (1989 - 1990).
Parameter1
N
Laboratory Means (mg/1)
P value2

NH4
N02
N023
TKNW
P04
TP .
TOC
TSS
SI

3
4
4
3
3
3
4
3
3
CRL/DCRA
0.097
0.015
1.255
0.676
0.027
0.065
4.48
12.3
1.66
DCLS
0.098
0.013
1.395
0.478
0.039
0.10
3.62
8.8
1.66
MDHMH
0.092
0.012
1.525
0.544
0.038
0.082
3.12
11.1
1.57

0.36
0.93
0.042
0.36
0.19
MDL3
0.65
0.53
0.53
     Total Dissolved  Phosphorus  (TOP), Dissolved Organic  Carbon  (DOC), and
     Biological  Oxygen Demand  5  day  (BODS)  could  not  be analyzed  due to
     • is•ing data .

     No P_  values  were statistically  significant  ( P_ < 0.01,  Friedman 2-way
     ANOVA on cruise  means uning exact probabilities).

     Too many values  were bellow the  HDL to  Make  a comparison.
                                   36

-------
IV. DISCUSSION

     All of  these results are preliminary,  due to small  sample  sizes and
start-up problems inherent in any new sampling program.   The  results are
not  necessarily  or  exclusively  a  reflection  of laboratory  performance.
They may suggest  that CSSP design features, specific  parameters,  or field
or  laboratory methods  should receive  extra attention  in  future quality
assurance work.

     Readers should also keep in mind that all the components include state
laboratories  that analyze a large number  of samples per  day  comprising a
wide range  of sample concentrations—from estuarine samples to wastewater
treatment plant  samples.   The number  of samples they analyze  reduces the
time available for researching advanced techniques and equipment.   Some of
the  laboratories  have  also had  difficulty obtaining and paying  for the
Standard Reference Material samples that are included in some CSSP results.

A. WITHIN-ORGANIZATION PRECISION AND ACCURACY

     The estimates of within-organization  precision  and  accuracy generally
show  similar  results  from the  different  organizations  involved.    One
exception is  the  two parameters calculated by  subtraction in  the Mainstem
component,  PN and PHOSP  results from  MDHMH (Table 4).   These were more
variable than the PN and PHOSP  results calculated  directly by  the other
three organizations.   The same pattern was noted by D'Elia et al. (1987)
and used as an argument for using the  direct methods.  One parameter, TON,
was  calculated  by addition  in the MDHMH  data  and  directly by  the other
organizations.  It had.similar precision among the four organizations.

B. INTER-ORGANIZATION PRECISION

     The estimates of inter-organization precision are  designed  to assess
the  measurement  system variability  in each  component after  sampling has
occurred.  They should be used with caution for that purpose, since both SD
and CV values can be affected by concentration.  They should not be used to
assess  inter-organization agreement.    Unless  there are  consistent inter-
organization differences  over  several  sampling dates, larger  SD  and/or CV
values may not indicate any problem with inter-organization agreement.  For
example,  some tests may be more  sensitive  to variations in  splitting
procedures than others; this variability may not be  under the laboratory's
control.  The SD  and CV results will be more useful when sample sizes are
larger.

C. INTER-ORGANIZATION AGREEMENT

     1. Mainstem component

     In  the Mainstem component,  five   parameters  (of  14  compared)  showed
statistically significant inter-organization differences  that  were larger
than wi thin-organization precision.   All involve a method difference at the
laboratory that had  divergent  results.  MDHMH uses a  different method for
TP and TOP from the three mainstem laboratories.  The MDHMH method does not

                                  37

-------
appear sufficiently sensitive to measure  the  low TP and TOP concentrations
at  Station  CB5.3.    Recent  digestion  method  changes  should  increase
sensitivity  to  low TP and  TOP concentrations.   CBL uses a different CHN
analyzer  (used  for  PC and PN) and a  different  filter  (25  mm  diameter
Whatman  GF/F)  than  ODU or  VIMS.    ODU  and  VIMS  both  use identical GIN
analyzers  and  13  mm diameter Gelman  AE filters.   Experiments are  being
planned  to study the possible  effects of these different  instruments and
filters  on PC and PN results.   The problem with DOC analyses  at MDHMH was
caused by  a new DOC  instrument that did not work  with  estuarine  samples.
It has  now been  remedied  by using  their old DOC  instrument, which  works
better with estuarine samples.

     2.  Potomac component

     In  the Potomac component, none of the nine parameters analyzed met the
criteria  for recommending  further  investigation.  Two  of  the parameters,
N023  and  TP,  had  inter-organization differences  that  were  larger  than
within-organization precision  on  three or  more sampling dates.   However,
none of  them had statistically significant differences.   Unfiltered samples
at MDHMH  may  have accounted  for  the  N023  differences,  since MDHMH had
higher  results  than  the   other  two  laboratories.   MDHMH  will  receive
filtered samples  starting  in late  1990.   The DCLS  results  for TP  were all
below their  detection limit because their low-level phosphorus  system was
not requested for these samples.

     3.  Fall line component

     No  analyses  were done due to the limited data  for  1989.   The sample
distribution problems were solved in 1990, and each laboratory should  start
receiving  triplicate aliquots once a cone splitter  is obtained.
V.  SUMMARY AND CONCLUSIONS

     Estimates of within-organization and inter-organization precision were
presented  which  may  be  useful  in  statistical  analyses  and  computer
modeling of Chesapeake  Bay water quality.   In three cases, parameters that
showed  low inter-organization  precision also  had  low inter-organization
agreement, but  the two were not  always  correlated.   Other parameters such
as  TKNW and  TSS  usually had  fairly low inter-organization  precision but
generally  high  inter-organization agreement.    Estimates  of  within-
organization  accuracy,  including percent  recovery  results and  Standard
Reference materials  (SRMs), showed high accuracy.

     Assessments  of  inter-organization agreement  found high agreement for
18  of the  23  comparisons made in two components.  Agreement was low enough
to  recommend  investigation for  five  parameters  (TP, TOP, PC, PN, and DOC).
In  all  five cases,  the organization  with divergent results had a different
analytical method or instrument  type, and  in two  cases  (PC and PN) there
was also a difference in filter  type.   In  three cases (TP, TOP, and DOC),
method  changes have  been made to  increase inter-organization agreement, and


                                   38

-------
the other two cases are being investigated by the organizations involved to
find ways to increase agreement.
VI. REFERENCES

Bergstrom, P.   1989.   Split sample  water quality results from laboratories
     participating  in  the Chesapeake  Bay Program: 1985-1989.   Chesapeake
     Bay Program, Coordinated Split Sample Program, Report Series: No. 1.

Bergstrom, P.   1990a.   Coordinated Split  Sample Program  Interim Report,
     Wainstem Component,  1989.   Chesapeake Bay  Program,  Coordinated Split
     Sample Program, Report Series:  No. 2.

Bergstrom, P.   1990b.   Coordinated Split  Sample Program  Interim Report,
     Potomac Component,  1989.    Chesapeake  Bay Program,  Coordinated Split
     Sample Program, Report Series:  No. 3.

Bergstrom, P.   1990c.   Coordinated Split  Sample Program  Interim Report,
     Fall Line  Component, 1989.   Chesapeake Bay Program, Coordinated Split
     Sample Program, Report Series:  No. 4.

Brainpower, Inc.  1986.  Statview 512+.  Brainpower, Inc., Calabasas, CA.

Chesapeake  Bay  Program.    1989.    Coordinated  Split  Sample  Program
     Implementation Guidelines,  Revision 1.   EPA Chesapeake  Bay Program,
     Annapolis, MD.

D'Elia, C., R.  Magnien,  C.  Zimmermann, P. Vaas, N. Kaumeyer,  C.  Keefe,  D.
     Shaw, and  K.  Wood.   1987.  Nitrogen and  phosphorus determinations in
     estuarine  waters: A comparison  of methods  used  in  Chesapeake  Bay
     Monitoring.  Report to EPA Chesapeake Bay Program, Annapolis, MD.

Kenney, S.   1990.  Maryland Department  of the  Environment Chesapeake  Bay
     Water Quality Monitoring  Program River  Input Monitoring  Component,
     Inter-  and   Intra-laboratory  Comparisons.    MDE  Water  Management
     Administration, Chesapeake Bay and Special Projects Program,  Watershed
     Restoration Projects Division Administrative Report, Baltimore, MD.

Montgomery, D.  C.   1985.   Introduction to  statistical quality control.
     Wiley & Sons, NY.

SAS  Institute,  Inc.   1985.    Statistical  Analysis  System (SAS)  Usersfs
     Guide: Basics, Version 5 edition.   SAS Institute, Gary, NC.

Siegel, S.  1956.   Non-parametric statistics  for  the  behavioral  sciences.
     McGraw-Hill Book Co., NY.

Taylor, J. K.   1987.  Quality assurance of chemical  measurements.   Lewis
     Publishers, Chelsea, MI.
                                  39

-------
ui o  O
-o  52.  n>

 3  
-------