Water samples were collected during each of the 2012–2019 Cooperative Science and Monitoring Initiative (CSMI) cruises aboard the U.S. EPA R/V Lake Guardian as part of the Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) lower food web contaminant assessment. The CSMI rotates around each of the Great Lakes in a 5-year cycle providing top-to-bottom biological, chemical, and physical environmental assessments, including dissolved-phase surface water studies at two sample locations. Average polychlorinated biphenyl (∑PCB) concentrations across the Great Lakes was 268 pg/L with a station range of 72 pg/L (Keweenaw Point-Lake Superior) to 834 pg/L (Middle Bass Island-Lake Erie). The highest average Great Lakes concentration (pg/L-sample year) were measured in Lake Erie (645 pg/L-2014) and decreased in the order of Lake Huron (378 pg/L-2012) > Lake Erie (364 pg/L-2019) > Lake Ontario (300 pg/L-2013) > Lake Michigan (125 pg/L-2015) > Lake Huron (123 pg/L-2017) > Lake Superior (74 pg/L-2016). Lake Erie registered a 44 % reduction over the 2014–2019 period, attributed to sediment remediation in the late-1990's on the Detroit River, whereas Lake Huron exhibited a 67 % decrease over the 2012–2017 sample period. Our results indicate that dissolved-phase PCB water concentrations in Lake Ontario have significantly increased, rebounding from a low-point in the late-1990's likely due to the bioenergetic diversion of dissolved- and particulate-phase PCBs into the benthic food web by invasive zebra and quagga mussel colonization. Trend analyses uncovered breakpoints in the early 1990's documenting significantly slowing rates of PCB declines for both Lakes Superior and Michigan.

Polybrominated diphenyl ethers (PBDEs) were widely used as fire retardants and have been detected throughout the Great Lakes (GL) ecosystem. The concentration trends (after fish age normalization) of PBDEs in top predator fish (lake trout and walleye) of the GLs were determined from 1979 to 2016, which includes most of the period when PBDEs were manufactured and used in this region. The fish samples were collected by two national (U.S. and Canada) long-term monitoring and surveillance programs. Trends in total concentrations (age-normalized) of the five major PBDE congeners (BDE-47, 99, 100, 153, and 154) found in fish across all five lakes have varied over time. Significant increases were observed from 1990 to 2000 (16.3% per year). Rapidly decreasing concentrations (-19.5% per year) were found from 2000 to 2007. Since 2007, the decreasing trend has become smaller (less than -5.5% per year) and relatively unchanged from 2011 to 2015. BDE-47, the congener with the highest concentrations in lake trout, has decreased continuously (ranging from -6.7% to -16.2% per year) in all lakes except Lake Erie. This decrease can be associated with the voluntary and regulatory phase out of production and/or usage of PBDEs since 2000. However, it has been offset by recent (since 2007) increasing trends of the other four higher brominated BDE congeners, especially BDE-100 and 154. Production and usage of commercial penta- and octa- BDE mixtures containing primarily the five major PBDE congeners was discontinued in 2004 in the U.S.A. and 2008 in Canada. These results indicate increasing fish uptake and bioaccumulation of higher brominated BDE congeners may be related to the transformation of BDE-209 to lower brominated BDE compounds in the GL environment or food web. Considering the abundance of BDE-209 in existing products and sediment in GL region, the duration of the unchanging total PBDE concentration trend in GL fish could be longer than expected.

Concentration patterns and temporal trends of legacy persistent, bioaccumulative and toxic (PBT) contaminants were determined using the Great Lake Fish Monitoring and Surveillance Program (GLFMSP) top predator fish data from 1999 to 2014 and applying Kendall-Theil robust regression after cluster-based age normalization. For most Great Lakes sites, significant decreasing concentration trends ranging from -4.1% to -21.6% per year (with the only exception being mirex in Lake Erie walleye) were found for PBTs including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane (DDTs), dieldrin, endrin, chlordane, oxychlordane, nonachlor, mirex, and hexachlorobenzene (HCB) reflecting the successful historical and ongoing reduction of fugitive releases and remediation efforts in the U.S. and Canada including physical removal (dredging) coupled with sediment sequestration. Generally, lower concentrations and faster decreasing trends are observed in western/northern sampling sites compared to eastern/southern sites as the former sites are generally more remote from population centers and industrial activities. PCBs, which can be released from ongoing sources, have the highest concentration, the second slowest decreasing trend, and increasing mass fractions of the contaminants studied suggesting that they will continue to be the legacy contaminant of greatest concern into the future.

The Great Lakes are a vital resource for drinking water and recreation and provide a major fishery for millions of people. As part of the Great Lakes Water Quality Agreement, the US and Canadian governments have been charged with the protection of this system. Persistent, bioaccumulative, and toxic (PBTs) contaminants were found to be affecting the lake water quality as early as the late 1960s, and various programs sponsored by the US and Canada have been created to monitor PBTs such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). These programs have refined measurement techniques to quantify trace level contaminants using a targeted analytical approach. However, new PBTs are being detected in the environment, and the traditional targeted methodology is inadequate for understanding the complex chemical mixture affecting Great Lakes wildlife. Fortunately, new analytical technologies are emerging that allow for comprehensive screening of PBTs beyond targeted methods. The current commentary presents an outline of a new framework for contemporary monitoring programs. The goal is to facilitate the compilation of legacy, emerging PBT, and archive PBT signatures by utilizing the basic practices of traditional targeted analysis. This example focuses on fish monitoring programs, and how they are ideally suited for legacy monitoring as well as data-driven discovery of new chemicals of concern.

The U.S. Environmental Protection Agency's Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) has traced the fate and transport of anthropogenic chemicals in the Great Lakes region for decades. Isolating and identifying halogenated species in fish is a major challenge due to the complexity of the biological matrix. A nontargeted screening methodology was developed and applied to lake trout using a 2-dimensional gas chromatograph coupled to a high resolution time-of-flight mass spectrometer (GC×GC-HR-ToF MS). Halogenated chemicals were identified using a combination of authentic standards and library spectral matching, with molecular formula estimations provided by exact mass spectral interpretation. In addition to the halogenated chemicals currently being targeted by the GLFMSP, more than 60 nontargeted halogenated species were identified. Most appear to be metabolites or breakdown products of larger halogenated organics. The most abundant compound class was halomethoxyphenols accounting for more than 60% of the total concentration of halogenated compounds in top predator fish from all five Great Lakes illustrating the need and utility of nontargeted halogenated screening of aquatic systems using this platform.

Our research reports polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (CP-PCBs) concentrations and age-corrected trends for lake trout and walleye in the Great Lakes over the 2004-2014 period. We determined that age-contaminant corrections are required to accurately report contaminant trends due to significant lake trout age structure changes. The age-trend model (ATM) described here uses a lake-specific age-contaminant regression to mitigate the effect of a fluctuating lake trout age structure to directly improve the log-linear regression model. ATM results indicate that half-life (t1/2) and percent decreases for PCDD/Fs, CP-PCBs, and toxic equivalence (TEQ) (average -56 to 70%) were fairly uniform and consistent across the Great Lakes over the 2004-2014 period. The vast majority of TEQ associated with all Great Lakes lake trout and walleye samples is due to the nonortho CP-PCBs (average = 79%) as compared with PCDD/Fs (average = 21%). On average, CP-PCB_126 individually accounted for over 95% of the total CP-PCB TEQ. A retrospective analysis (1977-2014) of 2378-TCDF and 2378-TCDD raw concentrations in Lake Ontario lake trout revealed decreases of 94% and 96%, respectively. Tissue residue guidelines for wildlife protection based on lake trout and walleye total TEQ were uniformly exceeded in all the Great Lakes.

The Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) has served to protect the Laurentian Great Lakes of North America for decades. Top predator fish from each lake are employed as bioindicators of chemical stressors within each lake. While a vast database has been created for legacy contaminants, such as polychlorinated biphenyls and organochlorine pesticides, a recent programmatic shift has transformed GLFMSP into a more proactive new chemical discovery/screening endeavour to capture the burden of more contemporary chemicals in the environment. The transition prompted the need for advanced instrumentation and the evaluation of mass spectrometric approaches beyond traditional electron capture detection and unit mass resolution mass spectrometers. Here the advances in detection methods are documented and the current direction of the program in creating a living database of anthropogenic chemicals affecting Great Lakes fish is highlighted.

Lake trout and walleye composites were collected between 2004 and 2009 as part of the Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) and analyzed for polybrominated diphenyl ethers (PBDEs). Yearly mean total PBDE concentrations (sum of congeners BDE-47, BDE-99, BDE-100, BDE-153, BDE-154) ranged from 44-192, 28-113, 50-107, 37-111, and 11-22 ng/g wet wt. for Lakes Michigan, Huron, Ontario, and Superior lake trout, and Lake Erie walleye, respectively. A 1980-2009 temporal record of PBDE concentrations in the Great Lakes' top predator fish (lake trout and walleye) was assembled by integrating previous GLFMSP data (1980-2003) with current results (2004-2009). Temporal profiles show obvious breakpoints between periods of PBDE accumulation and decline in trout for Lakes Huron, Michigan and Ontario with a significant (p < 0.0001 and r = 0.55, 0.72, and 0.51, respectively) decrease in concentration after 2000-2001. A similar transition was observed in Lake Superior for the nearshore site accompanied by a less significant decreasing trend (p = 0.016, r = 0.33), suggesting concentrations are declining very slowly or have leveled off. In contrast, Lake Erie walleye concentrations began leveling off in the late 1990s and no statistically significant trend (increasing or decreasing) has been observed in recent years. A decrease in the BDE-47/BDE-153 ratio was also recently observed, suggesting a transition to more highly brominated PBDEs is occurring in Great Lakes trout. This study provides region-wide evidence that PBDE concentrations are generally declining in Great Lakes trout, although there are clear exceptions to this trend. Results from this study reflect the positive impact of the 2004 PentaBDE ban on macro-scale aquatic freshwater ecosystems.

As part of the U.S. Great Lakes Fish Monitoring and Surveillance Program (GLFMSP), more than 300 lake trout (Salvelinus namaycush) and walleye (Stizostedion vitreum vitreum) collected from the Laurentian Great Lakes each year from 2004 to 2009, have been analyzed for total toxaphene and eight selected congeners. The analytical results show fish toxaphene concentrations are quite different among lakes. Between 2004 and 2009, Lake Superior lake trout had the highest concentration (119 to 482ng/g) and Lake Erie walleye had the lowest concentration (18 to 47ng/g). Combining these results with the historical total toxaphene data (1977–2003), temporal changes were examined for each lake. Because of different analytical methods used in the previous studies, the historical data were adjusted using a factor of 0.56 based on a previous inter-method comparison in our laboratory. Trend analysis using an exponential decay regression showed that toxaphene in Great Lakes fish exhibited a significant decrease in all of the lakes with t1/2 (confidence interval) of 0.9 (0.8–1.1) years for Lake Erie walleye, 3.8 (3.5–4.1) years for Lake Huron lake trout, 5.6 (5.1–6.1) years for Lake Michigan lake trout, 7.5 (6.7–8.4) years for Lake Ontario lake trout and 10.1 (8.2–13.2) years for Lake Superior lake trout. Parlars 26, 50 and 62 were the dominant toxaphene congeners accounting for 0.53% to 41.7% of the total toxaphene concentration. Concentrations of these congeners generally also decreased over time.

Temporal trend analysis of the latest Great Lake Fish Monitoring and Surveillance Program (GLFMSP) data showed statistically significant decreases in persistent bioaccumulative and toxic (PBT) contaminant (polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane and its metabolites (DDTs), dieldrin, cis-chlordane, oxychlordane, cis-nonachlor) concentrations in Lakes Huron, Ontario, and Michigan lake trout over the period of 1999 to 2009. In contrast, for most contaminants, no statistically significant concentration trends were found in top predator fish in Lakes Superior and Erie during the same period. For Lakes Huron, Ontario, and Michigan 5.0±2.6% average annual concentration decreases were found for PCBs, DDTs, dieldrin, and other organochlorine pesticides (OCs) decreased at a faster rate, ranging from 10±4.3% to 20±7.1% per year. For these three lakes, with the exception of PCBs, these current decreases are greater than were shown by an earlier trend analysis that estimated an annual contaminant decrease of about 2–5% for the period of 1980 to 2003. For Lakes Superior and Erie, the finding of no statistically significant trend is in agreement with previously reported results for these lakes.

Airborne particle and gas samples were collected approx every 12 days from April 2002 to June 2006 at the Sterling Nature Center located near the southeast corner of Lake Ontario. These samples were analyzed for polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDE). Clausius-Clapeyron (C-C) regression analyses of PCBs and DDE yielded moderate correlations (r(2) = 0.54, p < 0.001; r(2) = 0.74, p < 0.001, respectively) indicating that much of the variations in concentrations can be explained by temperature. Back trajectory analysis indicated that the most important factors driving unusually high PCB partial pressures relative to those predicted by the C-C regression were slow wind speeds and winds generally from the southwest. This combination, which occurred frequently in 2004, increased contact of the air with contaminated upwind surfaces with minimum dilution. Hybrid receptor modeling (Potential Source Contribution Function (PSCF)) results for the total PCBs identified the mid-western US region that contains the urban areas of southern Indiana (IN), southwestern Ohio (OH), and northern Kentucky (KY) having the highest PSCF values. In general urban areas like Chicago (IL), Detroit (MI), Cleveland (OH), St. Louis (MO), and Nashville (TN) also had significant possibilities. In contrast, the PSCF modeling for DDE identified northern Alabama as the area with the highest probability where DDT was applied to cotton fields. (C) 2010 Elsevier Ltd. All rights reserved.

Toxaphene is considered to be a problematic organochlorine pollutant because of its bioaccumulation potential and persistence in aquatic environments. In this study, whole lake trout and walleye composites were used to evaluate two analytical techniques for total toxaphene and selected congener analysis. The efficacy of using gas chromatography electron ionization tandem mass spectrometry (GC-EI/MS/MS) and electron capture negative ionization mass spectrometry (GC-ECNI-MS) were compared. Although the sensitivity using GC-ECNI-MS was approximately five times greater than GC-EI/MS/MS, the latter provided more consistent inter-Parlar relative response factors (RRF). When using technical calibration mixtures, these results suggest a more accurate total toxaphene measurement was obtained using the GC-EI/MS/MS method. Total toxaphene concentrations in lake trout composites from both methods were highly correlated (R(2) = 0.985) with the MS/MS concentrations approximately half of those determined by ECNI, suggesting systematic high bias in toxaphene concentrations when measured using GC-ECNI.