6 research outputs found
Improvements in fish polychlorinated biphenyl and other contaminant levels in response to remedial actions in Hamilton Harbour, Ontario, Canada
<p>Hamilton Harbour, located in Ontario, Canada at the western end of Lake Ontario, is recognized as one of the most anthropogenically-impacted regions within the Great Lakes and is currently listed as an Area of Concern. One of the Beneficial Use Impairments for the harbour has been restrictions on fish consumption due to elevated contaminant levels. In this study, we examined past and recent fish contaminant data collected by the Ontario Ministry of the Environment and Climate Change in partnership with other agencies to evaluate temporal trends in fish contaminant concentrations. Measurements for both resident and migratory sport fish as well as juvenile/forage fish were considered, with analysis focused on polychlorinated biphenyls, the group of chemicals identified as the major contaminant of concern. Current contaminant levels were evaluated against fish consumption advisory benchmarks used by Ontario Ministry of the Environment and Climate Change, and compared with corresponding observations for other locations across the Great Lakes, including other Areas of Concern. The results show statistically significant improvements in fish contaminant levels within Hamilton Harbour, with recent fish mercury concentrations below the first advisory benchmarks for all species included in this study. Polychlorinated biphenyl concentrations declined by 59–82% from historical levels, although this decline was not statistically significant in Brown Trout, Common Carp, Freshwater Drum and White Sucker. Further, all species exhibit recent polychlorinated biphenyl concentrations above the first consumption advisory benchmark of 105 ng g<sup>−</sup><sup>1</sup>. Compared to other Great Lakes locations, including other areas of concern, Hamilton Harbour polychlorinated biphenyl concentrations remain amongst the highest. The results suggest that recovery of Hamilton Harbour is still on-going.</p
Fish Mercury Levels Appear to Be Increasing Lately: A Report from 40 Years of Monitoring in the Province of Ontario, Canada
Recent mercury levels and trends
reported for North America suggest
a mixed (positive/negative) outlook for the environmental mercury
problem. Using one of the largest consistent monitoring data sets
in the world, here we present long-term and recent mercury trends
in Walleye, Northern Pike, and Lake Trout from the Province of Ontario,
Canada, which contains about one-third of the world’s fresh
water and covers a wide geographical area (1.5 and 3 times larger
than France and Germany, respectively). Overall, the results indicate
that the fish mercury levels either declined (0.01–0.07 μg/g
decade) or remained stable between the 1970s and 2012. The rates of
mercury <i>decline</i> were substantially greater (mostly
0.05–0.31 μg/g decade) during the 1970s/80s possibly
in response to reductions in mercury emissions. However, Walleye and
Pike levels have generally <i>increased</i> (0.01–0.27
μg/g decade) in recent years (1995–2012), especially
for northern Ontario (effect sizes for differences between the two
periods ranged from 0.39 to 1.04). Proportions of Walleye and Pike
locations showing a flat or increasing trend increased from 26–44% to 59–73% between the 1970s/80s and 1995–2012. Mercury
emissions in North America have declined over the last few decades,
and as such it is logical to expect recovery in fish mercury levels;
however, other factors such as global emissions, climate change, invasive
species, and local geochemistry are likely affecting the response
time and magnitude
Projecting Fish Mercury Levels in the Province of Ontario, Canada and the Implications for Fish and Human Health
Fish mercury levels appear to be
increasing in Ontario, Canada,
which covers a wide geographical area and contains about 250 000
lakes including a share of the North American Great Lakes. Here we
project 2050 mercury levels in Ontario fish, using the recently measured
levels and rates of changes observed during the last 15 years, and
present potential implications for fish and human health. Percentage
of northern Ontario waterbodies where sublethal effects of mercury
on fish can occur may increase by 2050 from 60% to >98% for Walleye
(WE), 44% to 59–70% for Northern Pike (NP), and 70% to 76–92%
for Lake Trout (LT). Ontario waterbodies with <i>unrestricted</i> fish consumption advisories for the <i>general population</i> may deteriorate from 24–76% to <1–33% for WE, 40–95%
to 1–93% for NP, and 39–89% to 18–86% for LT.
Similarly, Ontario waterbodies with <i>do not eat</i> advisories
for the <i>sensitive population</i> may increase from 32–84% to 73–100% for WE, 9–72% to 12–100% for
NP, and 19–71% to 24–89% for LT. Risk to health of Ontario
fish and humans consuming these fish may increase substantially over
the next few decades if the increasing mercury trend continues and
updated advisories based on continued monitoring are not issued/followed
Assessing fish consumption Beneficial Use Impairment at Great Lakes Areas of Concern: Toronto case study
<p>Beneficial use of fish consumption was designated impaired in the 1980s in many Areas of Concern across the North American Great Lakes. Remedial Action Plans have guided the restoration of beneficial use impairments with the goal of delisting the Areas of Concern. Here we present generic re-designation criteria and a three-tier Assessment Framework to assess the status of the fish consumption beneficial use impairments using the Toronto and Region Area of Concern as a case study. Tier 1 assessment identified that consumption advisories for many resident fish on the Toronto waterfront are non-restrictive (8+ meals month<sup>−1</sup>). Advisory assessments in Tier 1 found that most migratory fish species, Carp and White Sucker are still restrictive in some cases preventing a ‘not impaired’ re-designation. Tier 2 Comparison with Reference Sites found that the advisories for most local fish are either non-restrictive or similar to reference locations in Lake Ontario, but some advisories due to elevated levels of polychlorinated biphenyl are still more restrictive for the Toronto waterfront and do not favour a ‘not impaired’ re-designation. An evaluation of multiple lines of evidence in Tier 3 including fish contaminant trend analyses, time to reach target fish levels, sediment concentrations and fish consumption patterns resulted in outcomes ranging from <i>neutral</i> (not conclusive) to <i>not impaired</i>. As a precautionary approach, the impaired status of the beneficial use impairment should be maintained to ensure continued polychlorinated biphenyl declines in fish. It is recommended that the Remedial Action Plan team update the fish consumption survey, investigate where additional feasible actions can be taken including examining potential polychlorinated biphenyl sources on the Humber and Don Rivers, and collect new data to undertake a future assessment.</p
Evaluation and Interconversion of Various Indicator PCB Schemes for ∑PCB and Dioxin-Like PCB Toxic Equivalent Levels in Fish
Polychlorinated
biphenyls (PCBs) remain chemicals of concern more
than three decades after the ban on their production. Technical mixture-based
total PCB measurements are unreliable due to weathering and degradation,
while detailed full congener specific measurements can be time-consuming
and costly for large studies. Measurements using a subset of indicator
PCBs (iPCBs) have been considered appropriate; however, inclusion
of different PCB congeners in various iPCB schemes makes it challenging
to readily compare data. Here, using an extensive data set, we examine
the performance of existing iPCB3 (PCB 138, 153, and 180), iPCB6 (iPCB3
plus 28, 52, and 101) and iPCB7 (iPCB6 plus 118) schemes, and new
iPCB schemes in estimating total of PCB congeners (∑PCB) and
dioxin-like PCB toxic equivalent (dlPCB-TEQ) concentrations in sport
fish fillets and the whole body of juvenile fish. The coefficients
of determination (<i>R</i><sup>2</sup>) for regressions
conducted using logarithmically transformed data suggest that inclusion
of an increased number of PCBs in an iPCB improves relationship with
∑PCB but not dlPCB-TEQs. Overall, novel iPCB3 (PCB 95, 118,
and 153), iPCB4 (iPCB3 plus 138) and iPCB5 (iPCB4 plus 110) presented
in this study and existing iPCB6 and iPCB7 are the most optimal indicators,
while the current iPCB3 should be avoided. Measurement of ∑PCB
based on a more detailed analysis (50+ congeners) is also overall
a good approach for assessing PCB contamination and to track PCB origin
in fish. Relationships among the existing and new iPCB schemes have
been presented to facilitate their interconversion. The iPCB6 equiv
levels for the 6.5 and 10 pg/g benchmarks of dlPCB-TEQ<sub>05</sub> are about 50 and 120 ng/g ww, respectively, which are lower than
the corresponding iPCB6 limits of 125 and 300 ng/g ww set by the European
Union
Development and Application of a Low-Volume Flow System for Solution-State <i>in Vivo</i> NMR
<i>In vivo</i> nuclear magnetic resonance (NMR) spectroscopy
is a particularly powerful technique, since it allows samples to be
analyzed in their natural, unaltered state, criteria paramount for
living organisms. In this study, a novel continuous low-volume flow
system, suitable for <i>in vivo</i> NMR metabolomics studies,
is demonstrated. The system allows improved locking, shimming, and
water suppression, as well as allowing the use of trace amounts of
expensive toxic contaminants or low volumes of precious natural environmental
samples as stressors. The use of a double pump design with a sump
slurry pump return allows algal food suspensions to be continually
supplied without the need for filters, eliminating the possibility
of clogging and leaks. Using the flow system, the living organism
can be kept alive without stress indefinitely. To evaluate the feasibility
and applicability of the flow system, changes in the metabolite profile
of <sup>13</sup>C enriched <i>Daphnia magna</i> over a 24-h
period are compared when feeding laboratory food vs exposing them
to a natural algal bloom sample. Clear metabolic changes are observed
over a range of metabolites including carbohydrates, lipids, amino
acids, and a nucleotide demonstrating <i>in vivo</i> NMR
as a powerful tool to monitor environmental stress. The particular
bloom used here was low in microcystins, and the metabolic stress
impacts are consistent with the bloom being a poor food source forcing
the <i>Daphnia</i> to utilize their own energy reserves