Electronic Supplementary Information to “An interlaboratory-comparison for total
mercury and methylmercury in water at environmentally relevant concentrations”
Table S1. Rating system for laboratory performance (Niu & Tintle 2003). C-W distance = CookWeisberg distance.
Rating
t-value
C-W distance
5 (Very good)
0.00 ≤ t-value ≤ 2.00
C-W distance < 3.00
4 (Good)
2.01 ≤ t-value ≤ 4.00
C-W distance < 3.00
3 (Satisfactory)
t-value > 4.00
C-W distance < 3.00
2 (Questionable)
t-value > 4.00
3.00 ≤ C-W distance ≤ 10.00
1 (Poor)
t-value > 4.00
10.01 ≤ C-W distance
0 (Unacceptable)
With one or more outliers
With one or more outliers
Table S2. Study participants in 2011.
Laboratory Name
Acadia University
Alabama Power Company
ALS Environmental - Vancouver
ALS Laboratory Group-Envir. Division
ALS Technichem (m) Sdn Bhd
American Electric Power - Dolan Chem. Lab.
ARPA - FVG Dept. of Trieste - Italy
Basic Laboratory, Inc
Battelle Marine Science Lab
BRGM
Caltest Analytical Laboratory
Canada Centre for Inland Waters
Center for Environmental Systems Engr. (Syracuse)
Centre for Ecology and Hydrology
Centre for Environmental Contaminants Research
City of Portland WPCL
City of San Jose ESD
Dartmouth Trace Element Analysis Laboratory
Eagle Mountain Scientific
Flett Research Ltd.
Geochemical Lab of Pacific Geographical Institute, Russian Academy of
Sciences
Institute of Geology ASCR, v.v.i.
IVL Swedish Environmental Institute Ltd
Jozef Stefan Institute
Lab of Environmental Chemistry, University of Athens
Laboratoire des Mecanismes et Transferts en Geologie (LMTG)
LEEQ - Environment Canada
Country
Canada
USA
Canada
Canada
Malaysia
USA
Italy
USA
USA
France
USA
Canada
USA
United Kingdom
Australia
USA
USA
USA
USA
Canada
Russia
Czech Republic
Sweden
Slovenia
Greece
France
Canada
Laboratory Name
McCampbell Analytical, Inc.
Mercury One Ltd
Mercury-FFF Laboratory (University of Utah)
Microbac Laboratories, Inc. - Chicagoland Division
Moss Landing Marine Laboratories
NIVA
Oak Ridge National Laboratory, Environmental Sciences
Oceanography/Florida State University
Oregon Department of Environmental Quality
Quicksilver Scientific
Southern Analytical Laboratories, Inc
University of Connecticut-Civil/Environmental Engineering
University of Mississippi
University of Missouri
University of Ottawa Mercury Lab
University of San Francisco/Luengen Lab
University of Western Ontario/Branfireun Lab
USGS Menlo Park, California
USGS Middleton, Wisconsin
Wisconsin State Laboratory of Hygiene
Woods Hole Oceanographic Institution
WSU Ecological Engineering Mercury Lab
YS Institute of Environmental Technology Inc.
Country
USA
USA
USA
USA
USA
Norway
USA
USA
USA
USA
USA
USA
USA
USA
Canada
USA
Canada
USA
USA
USA
USA
USA
Korea
Table S3. Study participants in 2012.
Laboratory Name
AEP - Dolan Chemical Laboratory
Alabama Power Company
ALS Environmental (Vancouver)
ALS Environmental (Winnipeg)
ALS Technichem (M) Sdn. Bhd.
Regional Agency for Environmental Protection (ARPA) FVG
Basic Laboratory, Inc
Battelle Marine Sciences Laboratory
Biogeochemical Analytical Service Laboratory
Brooks Rand Labs ASD
Caltest Analytical Laboratory
Center for Environmental Systems Engr. - Syracuse University
Central Geological Laboratory
City of Portland WPCL
City of San Francsico Clean Water Labs
City of San Jose ESD
Clear Carbon Innovations
Dartmouth Trace Element Analysis Lab
Dr. Gustin Lab, University of Nevada, Reno
Country
USA
USA
Canada
Canada
Malaysia
Italy
USA
USA
Canada
USA
USA
USA
Mongolia
USA
USA
USA
USA
USA
USA
Laboratory Name
Environment Canada-Burlington
Finnish Forest Research Institute/University of Oulu
Flett Research Ltd.
FSU Oceanography
Geosciences Environment Toulouse
IAEA EL
IFREMER Centre de Méditerranée
Institute of Geochemistry, Chinese Academy of Sciences
Institute of Geology AS CR, v.v.i.
IVL Swedish Environmental Research Institute Ltd
Jožef Stefan Institute
Laboratoire des essais environnementaux du Québec
Laboratory of High Res Spectroscopy, ASI, LU
Lakehead University Environmental Laboratory
LCABIE IPREM
McCampbell Analytical
Microbac Laboratories Inc. - Chicagoland Division
Minnesota Department of Health
National School of Public Health
NIVA
Oak Ridge National Laboratory
Pace Analytical Services, Virginia, MN
POD Laboratory
Rob Mason Lab, UConn Dept. of Marine Sciences
Rutgers University
South China Institute of Environmental Sciences
Sacramento Regional County Sanitation District EL
TestAmerica Laboratories, Inc.
University of Wisconsin Environmental Chem. & Tech.
University of Connecticut CEE
University of Missouri - Wall Lab
University of Ottawa Mercury Lab
University of San Francisco
University of Utah CMES ICP-MS Lab
University of Western Ontario, Analytical Services
USGS Menlo Park
USGS Middleton
Wisconsin State Lab of Hygeine
Woods Hole Oceanographic Institution
Wright State University
Country
Canada
Finland
Canada
USA
France
Monaco
France
China
Czech Republic
Sweden
Slovenia
Canada
Latvia
Canada
France
USA
USA
USA
Greece
Norway
USA
USA
USA
USA
USA
China
USA
USA
USA
USA
USA
Canada
USA
USA
Canada
USA
USA
USA
USA
USA
Table S4. Study participants in 2013.
Laboratory Name
ACZ Laboratories, Inc.
Alabama Power General Test Lab
Alpha Analytical Laboratories, Inc.
ALS Environmental (Vancouver)
ALS Environmental (Winnipeg)
American Assay Laboratories
American Electric Power - Dolan Chemical Laboratory
ARPA - FVG
Basic Laboratory, Inc.
Battelle Marine Sciences Lab
Biogeochem. Analytical Service Lab U of Alberta
Brooks Rand Labs
Caltest Analytical Laboratory
Central Geological Laboratory
City of Boise Water Quality Lab
City of Portland Water Pollution Control Lab
City of San Jose ESD
Clarkson University (Prof. Holsen's Lab)
Clean Water Services Water Quality Lab
CNR-Istituto Sull'Inquinamento Atmosferico
Dartmouth College - TEA Lab
Denver Metro Wastewater Reclamation District
Environment Canada Burlington (Kirk)
Environment Canada Burlington (Lawson)
Environment Canada Montreal - LEEQ
Finnish Forest Research Institute / University of Oulu
Flett Research Ltd.
Florida DEP
FSU Oceanography
Geosciences Environment Toulouse
Gustavus Adolphus College
Institute of Geochemistry, Chinese Academy of Sciences
Institute of Geology ASCR, v.v.i.
IVL Swedish Environmental Research Institute Ltd.
Jozef Stefan Institute
Lakehead University Environmental Laboratory
Marine Pollution Studies Lab (Moss Landing)
McCampbell Analytical
Microbac Laboratories, Inc. Chicagoland Division
Minnesota Department of Health
NIVA (Norwegian Institute For Water Research)
North Carolina DENR Laboratory
Oak Ridge National Laboratory
P.S. Analytical Ltd.
Country
USA
USA
USA
Canada
Canada
USA
USA
Italy
USA
USA
Canada
USA
USA
Mongolia
USA
USA
USA
USA
USA
Italy
USA
USA
Canada
Canada
Canada
Finland
Canada
USA
USA
France
USA
China
Czech Republic
Sweden
Slovenia
Canada
USA
USA
USA
USA
Norway
USA
USA
UK
Laboratory Name
Pace Analytical Laboratory
Pacific Geographical Institute, Russian Academy of Sciences
Rob Mason Lab - UConn
Seoul National University
Southeast Laboratory San Francisco PUC
SRCSD Environmental Laboratory
TestAmerica Laboratories, Inc.
The University of Western Ontario, Analytical Services
Trent University Water Quality Centre
University of Utah Mercury/Microprobe/FFF Lab
Universidade Federal do Rio de Janeiro
University of Athens
University of Maine Sawyer Env. Chem. Research Lab
University of Ottawa Mercury Lab
University of South Carolina
USGS Menlo Park
USGS Middleton
UT2A
VHG Labs
Wisconsin State Laboratory of Hygiene
WISMA ALS
Wright State University
Country
USA
Russia
USA
Korea
USA
USA
USA
Canada
Canada
USA
Brazil
Greece
USA
Canada
USA
USA
USA
France
USA
USA
Malaysia
USA
Table S5. Study participants in 2014.
Laboratory Name
ACZ Laboratories Inc.
AEP Dolan Chemical Laboratory
Alpha Analytical Laboratories, Inc.
ALS Environmental (Vancouver)
ALS Environmental (Winnipeg)
ALS Technichem Sdn Bhd
American Assay Laboratories
Basic Laboratory, Inc.
Battelle Marine Sciences Lab
Brigham Young University Mercury Lab
Brooks Rand Labs
Caltest Analytical Laboratory
City of San Jose ESD Laboratory
Clean Water Services Water Quality Laboratory (Oregon)
CNR Institute of Atmospheric Pollution Research
CSIRO Land and Water
Dartmouth College Trace Element Analysis Lab
Desert Research Institute
Dr. Carol Ptacek Lab, University of Waterloo
Duke University/Hsu-Kim
Country
USA
USA
USA
Canada
Canada
Malaysia
USA
USA
USA
USA
USA
USA
USA
USA
Italy
Australia
USA
USA
Canada
USA
Laboratory Name
Environment Canada - Burlington
Environment Canada PYLET
Flett Research Ltd.
Geosciences Environment Toulouse
Gustavus Adolphus College
IAEA-Environment Laboratories
IFREMER/LBCM
Institut FA Forel, University of Geneva
Institute of Geology, ASCR, v.v.i.
Instituto de Quimica/UNICAMP
IVL Swedish Environmental Research Institute Ltd
Jozef Stefan Institute
Kentucky Environmental Services
Laboratory of Environmental Chemistry, Univ. of Athens
Lakehead University Environmental Laboratory
LEEQ - Environment Canada
Lumex Analytics GMBH
Marine Environmental Monitoring Centre of Guangxi Province
Metro Wastewater Reclamation District
Microbac Laboratories, Inc. - Chicagoland Division
NIVA (Norwegian Institute for Water Research)
North Carolina DENR Laboratory
Oak Ridge National Laboratory
Pace Analytical
Southeast Laboratory San Francisco PUC
SRC Environmental Analytical Laboratories
SRCSD-EL (Sacramento)
Texas Tech University/Dr. Danny Reible Lab
Trace Element Laboratory, University of Oulu
TU Braunschweig, Inst. für Geoökologie, Umweltgeochemie
UNIR/Laboratorio de Biogeoquimica Ambiental
University of Alberta, Biogeochemical Service Laboratory
University of Illinois
University of Ottawa Environ. Geochem. & Microbiol. Lab
University of South Carolina
University of Utah Geology & Geophysics
University of Western Ontario, Analytical Services
USGS Menlo Park
USGS Middleton
USGS Southeast Ecological Science Center
WE-Energies
Westminster College
Wisconsin State Lab of Hygiene
Woods Hole Oceanographic Institution
Country
Canada
Canada
Canada
France
USA
Monaco
France
Switzerland
Czech Republic
Brazil
Sweden
Slovenia
USA
Greece
Canada
Canada
Germany
China
USA
USA
Norway
USA
USA
USA
USA
Canada
USA
USA
Finland
Germany
Brazil
Canada
USA
Canada
USA
USA
Canada
USA
USA
USA
USA
USA
USA
USA
Figure S1. Histograms of reported total mercury concentrations for site UB in 2014. All
concentrations (left); non-outlier values (right).
Figure S2. Box plots of reported total mercury concentrations for site UB in 2014. All
concentrations (left); non-outlier values (right).
Figure S3. Normal quantile-quantile plots of reported total mercury data for site UB in 2014. All
concentrations (left); non-outlier values (right).
Figure S4. Density functions of residuals (residual = individual measurement - laboratory mean)
of total mercury data for site UB in 2014. All values (left); non-outlier values (right).
Figure S5. Residual (residual = individual measurement - laboratory mean) vs. fitted value plots
of reported total mercury concentrations for site UB in 2014. All values (left); non-outlier values
(right).
Site HP
8
Total Mercury (ng/L)
7
6
5
4
BRL
USGS
3
2/17/11
2/22/11
2/27/11
3/4/11
3/9/11
3/14/11
3/9/11
3/14/11
3/9/11
3/14/11
Date Analyzed
Site SP
Total Mercury (ng/L)
9
8
7
6
5
4
BRL
3
USGS
2
2/17/11
2/22/11
2/27/11
3/4/11
Date Analyzed
Site EN
Total Mercury (ng/L)
2.2
2
1.8
1.6
1.4
1.2
1
2/17/11
BRL
USGS
2/22/11
2/27/11
3/4/11
Date Analyzed
Figure S6. 2011 holding-time data for total mercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they do not extend beyond the edge of
the graph symbol. BRL = Brooks Rand Labs; USGS = U.S. Geological Survey.
Methylmercury (ng/L)
Site HP
0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
2/10/11
BRL
USGS
2/12/11
2/14/11
2/16/11
2/18/11
2/20/11
2/22/11
2/24/11
2/20/11
2/22/11
2/24/11
2/20/11
2/22/11
2/24/11
Date Analyzed
Methylmercury (ng/L)
Site SP
0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
2/10/11
BRL
USGS
2/12/11
2/14/11
2/16/11
2/18/11
Date Analyzed
Site EN
Methylmercury (ng/L)
0.1
0.08
0.06
0.04
0.02
BRL
USGS
0
2/10/11
2/12/11
2/14/11
2/16/11
2/18/11
Date Analyzed
Figure S7. 2011 holding-time data for methylmercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they do not extend beyond the edge of
the graph symbol. BRL = Brooks Rand Labs; USGS = U.S. Geological Survey.
Total Mercury (ng/L)
6.9
6.7
6.5
6.3
6.1
5.9
5.7
5.5
5.3
5.1
2/1/12
Site HP
BRL
JSI
USGS
2/6/12
2/11/12
2/16/12
2/21/12
2/26/12
3/2/12
3/7/12
3/12/12
Total Mercury (ng/L)
Date Analyzed
6.9
6.7
6.5
6.3
6.1
5.9
5.7
5.5
5.3
5.1
2/1/12
Site SP
BRL
JSI
USGS
2/6/12
2/11/12
2/16/12
2/21/12
2/26/12
3/2/12
3/7/12
3/12/12
Date Analyzed
2.6
Site EN
Total Mercury (ng/L)
2.4
2.2
2
1.8
1.6
BRL
JSI
USGS
1.4
1.2
1
2/1/12
2/6/12
2/11/12
2/16/12
2/21/12
2/26/12
3/2/12
3/7/12
3/12/12
Date Analyzed
Figure S8. 2012 holding-time data for total mercury. Error bars are ± 1 standard deviation of
replicate measurements. Note that the graph scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey.
Methylmercury (ng/L)
0.18
Site HP
0.16
0.14
0.12
0.1
0.08
0.06
0.04
1/27/12
BRL
JSI
USGS
2/1/12
2/6/12
2/11/12
2/16/12
2/21/12
2/26/12
3/2/12
3/7/12
2/21/12
2/26/12
3/2/12
3/7/12
2/21/12
2/26/12
3/2/12
3/7/12
Date Analyzed
Methylmercury (ng/L)
0.18
Site SP
0.16
0.14
0.12
0.1
0.08
0.06
0.04
1/27/12
BRL
JSI
USGS
2/1/12
2/6/12
2/11/12
2/16/12
Date Analyzed
Methylmercury (ng/L)
0.08
Site EN
0.07
0.06
0.05
0.04
0.03
0.02
0.01
1/27/12
BRL
JSI
USGS
2/1/12
2/6/12
2/11/12
2/16/12
Date Analyzed
Figure S9. 2012 holding-time data for methylmercury. Error bars are ± 1 standard deviation of
replicate measurements. Note that the graph scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey.
Total Mercury (ng/L)
Total Mercury (ng/L)
12.5
12
11.5
11
10.5
10
9.5
9
8.5
8
7.5
2/12/13
3.5
3.3
3.1
2.9
2.7
2.5
2.3
2.1
1.9
1.7
1.5
2/12/13
Site NS
BRL
JSI
USGS
2/22/13
3/4/13
3/14/13
Date Analyzed
3/24/13
4/3/13
Site UB
BRL
JSI
USGS
2/22/13
3/4/13
3/14/13
Date Analyzed
3/24/13
4/3/13
60
Site MP
Total Mercury (ng/L)
55
50
45
40
35
BRL
JSI
USGS
30
25
2/12/13
2/22/13
3/4/13
3/14/13
Date Analyzed
3/24/13
4/3/13
Figure S10. 2013 holding-time data for total mercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they are smaller than the chart symbol
to which they pertain. Note that the vertical scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey.
Methylmercury (ng/L)
5
Site NS
4.5
4
3.5
3
BRL
JSI
USGS
2.5
2
2/11/2013
2/16/2013
2/21/2013
Methylmercury (ng/L)
0.3
3/8/2013
3/13/2013
Site UB
0.25
0.2
0.15
BRL
JSI
USGS
0.1
0.05
2/11/2013
2/16/2013
2/21/2013
2/26/2013
3/3/2013
Date Analyzed
3/8/2013
3/13/2013
Site MP
4.25
Methylmercury (ng/L)
2/26/2013
3/3/2013
Date Analyzed
3.75
3.25
2.75
2.25
BRL
JSI
USGS
1.75
1.25
2/11/2013
2/16/2013
2/21/2013
2/26/2013
3/3/2013
Date Analyzed
3/8/2013
3/13/2013
Figure S11. 2013 holding-time data for methylmercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they are smaller than the chart symbol
to which they pertain. Note that the vertical scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey.
Total Mercury (ng/L)
100
95
90
85
80
75
70
65
60
55
50
2/10/14
Site WH
BRL
JSI
USGS
2/15/14
2/20/14
2/25/14
Date Analyzed
3/2/14
3/7/14
2.45
Site UB
Total Mercury (ng/L)
2.35
2.25
2.15
2.05
1.95
1.85
BRL
JSI
USGS
1.75
1.65
Total Mercury (ng/L)
1.55
2/10/14
10
9.5
9
8.5
8
7.5
7
6.5
6
5.5
5
2/10/14
2/15/14
2/20/14
2/25/14
Date Analyzed
3/2/14
3/7/14
Site SP
BRL
JSI
USGS
2/15/14
2/20/14
2/25/14
Date Analyzed
3/2/14
3/7/14
Figure S12. 2014 holding-time data for total mercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they are smaller than the chart symbol
to which they pertain. Note that the vertical scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey.
Methylmercury (ng/L)
0.05
0.04
Site WH
BRL
JSI
USGS*
0.03
0.02
0.01
0
2/10/2014
2/15/2014
2/20/2014
0.19
3/2/2014
3/7/2014
Site UB
0.18
Methylmercury (ng/L)
2/25/2014
Date Analyzed
3/12/2014
BRL
JSI
USGS
0.17
0.16
0.15
0.14
0.13
0.12
0.11
0.1
2/10/2014
2/15/2014
2/20/2014
Methylmercury (ng/L)
0.16
2/25/2014
Date Analyzed
3/2/2014
3/7/2014
Site SP
0.15
3/12/2014
BRL
JSI
USGS
0.14
0.13
0.12
0.11
0.1
0.09
0.08
2/10/2014
2/15/2014
2/20/2014
2/25/2014
Date Analyzed
3/2/2014
3/7/2014
3/12/2014
Figure S13. 2014 holding-time data for methylmercury. Error bars are ± 1 standard deviation of
replicate measurements. Where error bars are not visible, they are smaller than the chart symbol
to which they pertain. Note that the vertical scales are not identical. BRL = Brooks Rand Labs;
JSI = “Jožef Stefan” Institute; USGS = U.S. Geological Survey. *In the Site WH graph, the
USGS concentrations were below the detection limit (0.04 ng/L). The plotted value is half of the
detection limit (0.02 ng/L) and the error bars span the range from 0 to the detection limit.