Organochlorine contaminant concentrations in caddisfly adults (Trichoptera) collected from great lakes connecting channels

Pennsylvania-style light traps were used to capture adult Trichoptera from the St. Marys, St. Clair, Detroit and Niagara rivers, Canada. Adequate biomass was acquired in single, 2-h collections to permit triplicate gas chromatographic analyses of 1–4 g samples for 36 organochlorine contaminants. Contaminant levels varied unpredictably but relatively little among samples taken at monthly intervals over the summer. Samples collected simultaneously from the two sides of the Detroit R. reflected local sediment contaminant patterns, suggesting limited dispersal by adults. Genus-specific differences in contaminant concentrations within the Hydropsychidae and Leptoceridae probably reflect differences in larval habitats and manner of feeding. Contaminant concentrations and relative composition paralleled published reports of contaminants in sediments from collection locations. St. Marys R. caddisflies contained contaminant levels indistinguishable from samples collected at reference sites. St. Clair R. samples contained high levels of compounds associated with petrochemical industries located in the river's upstream reaches. High levels of polychlorinated biphenyls (PCBs) and most other contaminants in Detroit R. samples reflected industrial loadings near Detroit, Michigan. Niagara R. samples contained elevated concentrations of PCBs and pesticides. Cluster analysis grouped samples into five clusters each with unique contaminant composition. These also corresponded to geographic origin: St. Marys, St. Clair, Detroit and upper and lower Niagara rivers. The relative ease of collection and consistent results obtained render adult Trichoptera potentially valuable candidates for surveys of aquatic contamination over a broad range of geographical and ecological conditions.     

Computer simulation model for determining reclamation liability costs of the Ekati Diamond Mine™ in the Northwest Territories,Canada

Estimation of closure liabilities for financial reporting and security deposits in the mining industry is often based on past estimates or deterministic models. These methods are limited in their ability to account for the variability of contributing costing factors. In 2001, Komex International Ltd. developed a Monte Carlo simulation (MCS) model to provide a best estimate for the reclamation liabilities of the Ekati Diamond Mine™ (BHP Billiton Diamonds Inc.). The model was built upon Decisioneering's^® Crystal Ball risk analysis and forecasting software to simulate the various facets of the mine's closure plans and reclamation activities. Reclamation activities included decommissioning, demolition, site remediation, reclamation and post closure monitoring for seven mine pits and related infrastructures over four time periods. The model predicted the median, 10th and 90th percentile costs and other statistical measures. A sensitivity analysis was also conducted to identify the most significant cost contributors. This type of model offers many advantages for companies in determining probable costs of future environmental activities. Through the identification of cost contributors, work scenarios, computer code and modeling software, a MCS model can simulate a wide range of probable costs and scenarios. Probabilistic models are more effective at incorporating risk and uncertainty in liability estimates than deterministic estimation tools that rely heavily on global contingencies to account for risk.     

Using GRADE to respond to health questions with different levels of urgency

Increasing interest exists in applying the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to environmental health evidence. While ideally applied to evidence synthesized in systematic reviews and corresponding summary tables, such as evidence profiles, GRADE's correct application requires that “the evidence that was assessed and the methods that were used to identify and appraise that evidence should be clearly described.” In this article, we suggest that GRADE could be applied to evidence assembled from narrative reviews, modelled (indirect) evidence, or evidence assembled as part of a rapid response, if the underlying judgments about the certainty in this evidence are based on the relevant GRADE domains and provided transparently. Health questions that require assessing the certainty in a body of evidence to provide trustworthy answers may range from hours, to days or weeks, to a few months to scenarios that allow assessing evidence without short-term time pressures. Time frames of emergent, urgent or rapid evidence assessments will often require relying on existing summaries or rapidly compiling the available evidence and making assessments. Even without available full systematic reviews, expressing the certainty in the evidence can provide useful guidance for users of the evidence and those who evaluate certainty in effects. The ratings also help clarifying disagreement between organizations tackling similar questions about the evidence. Using the structured GRADE domains, narrative or other summaries of the evidence can be presented transparently.     

Removal of dinitrotoluenes from water via reduction with iron and peroxidase-catalyzed oxidative polymerization: a comparison between Arthromyces ramosus peroxidase and soybean peroxidase

A two-step process for the removal of dinitrotoluene from water is presented: zero-valent iron reduction is coupled with peroxidase-catalyzed polymerization of the resulting diaminotoluenes (DAT). The effect of pH was examined in the reduction step: at pH 6 the reaction occurred much more rapidly than at pH 8. In the second step, optimal pH and substrate ratio, minimal enzyme concentration and effect of polyethylene glycol (PEG) as an additive for greater than 95% conversion of DAT, over a 3h reaction period were determined using high performance liquid chromatography. Two enzymes were investigated and compared: Arthromyces ramosus peroxidase (ARP) and soybean peroxidase (SBP). The optimal pH values were 5.4 and 5.2 for ARP and SBP, respectively, but SBP was more resistant to mild acid whereas ARP was more stable in neutral solutions. SBP was found to have a greater hydrogen peroxide demand (optimal peroxide/DAT molar ratio for SBP: 2.0 and 3.0 for 2,4-diaminotoluene (2,4-DAT) and 2,6-diaminotoluene (2,6-DAT), respectively; for ARP: 1.5 and 2.75 for 2,4-DAT and 2,6-DAT, respectively) but required significantly less enzyme (0.01 and 0.1 U ml(-1) for 2,4-DAT and 2,6-DAT, respectively) to convert the DAT than ARP (0.4 and 1.5 U ml(-1) for 2,4-DAT and 2,6-DAT, respectively). PEG was shown to have no effect upon the degree of substrate conversion for either enzyme.     

Mercury concentrations in wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada: relationship to age and parasitism

Total mercury (Hg) concentrations were measured in the fur, brain and liver of wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada. Total Hg concentrations in fur were strongly correlated with levels in the brain and liver. There was no difference in tissue concentrations between male and female mink; however, female otters had significantly higher fur, brain and liver Hg levels than males. Similarly, there was not a significant relationship between Hg concentration and age of mink, whereas in otters, Hg concentrations in all three tissues decreased significantly with age. In both species, only a very small percentage of the variability in Hg concentration was explained by age. After adjusting the data for site-to-site differences in Hg levels, Hg concentrations in the fur of mink infected by the parasite, Dioctophyma renale, were found to be significantly higher than Hg levels in uninfected mink.     

A synopsis of land use,land-use change and forestry (LULUCF) under the Kyoto Protocol and Marrakech Accords

The complexities inherent in land use, land-use change and forestry (LULUCF) activities have led to contentious and prolonged debates about the merits of their inclusion in the 2008–2012 first commitment period of the Kyoto Protocol. Yet the inclusion of these activities played a key role in agreement on the general framework of the Kyoto Protocol, and LULUCF will likely continue to play a substantial part in negotiations on national commitments post-2012. The Marrakech Accords dictate which LULUCF activities are to be included under the Kyoto Protocol and provide rules on how they are to be accounted in the first commitment period. However, these rules have limitations and drawbacks that may be avoided in the structure of future commitments beyond 2012. Through adherence to the objectives of the United Nations Framework Convention on Climate Change (UNFCCC), and the incorporation of several critical features, a future framework can more effectively address the mitigation challenges and opportunities of this sector.     

三峡库区回水区营养盐和叶绿素a的时空变化及其相互关系

为探讨三峡水库调度运行背景下,库区回水区营养盐和叶绿素a时空变化及其相互关系,于2013年5月~2014年5月在三峡库区北岸最大、也是库区水华频发的支流——澎溪河的回水区高阳平湖进行了定点和高频监测.结果表明水体热分层是高阳平湖水华发生的诱导因素.高阳平湖水体热分层发生于春季(3月初),消亡于夏末(9月中旬),冬季没有分层.2014年春季,随着水体分层的发生和发展,表层叶绿素a在69 d内从14.92μg·L-1骤增至183.73μg·L-1,并暴发水华,之后叶绿素a随着混合层深度增加而下降.水体没有分层时,表、中和底层营养盐浓度相近;水体分层之后,各层磷浓度有了明显差异,表层和底层总磷浓度相差(0.18±0.04)mg·L-1.高水位期(9月至次年4月),高阳平湖硝氮和溶解性磷高于低水位期(5~8月)的含量,分别占总氮、总磷浓度的71.4%~95.4%和42.7%~94.4%,是总氮和总磷的主要组成部分,干流倒灌输入的硝氮和溶解性磷是其主要来源.     

Triclosan in waste and surface waters from the upper Detroit River by liquid chromatography-electrospray-tandem quadrupole mass spectrometry

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is an antimicroibial disinfectant agent used in a wide array of consumer products. An analytical method based on solid-phase extraction (SPE) followed by reverse phase, liquid chromatography coupled with electrospray ionization (negative)-tandem quadrupole mass spectrometry (LC-ESI(-)-MS/MS; in the multiple reaction monitoring (MRM) mode) was developed, optimized and validated for the determination of triclosan in wastewater/sewage treatment plant (WSTP) effluent and surface waters from the upper Detroit River (Canada). The mean recoveries (+/-%RSD) of triclosan and the internal standard 2'-HO-tribromodiphenyl ether (2'-HO-BDE-28) spiked to surface water and WSTP effluent samples ranged similarly from 104+/-8% and 91+/-10%, respectively, and method limits of quantification were in the low ppb/high ppt range. However, ESI(-) enhancement was found for both analytes due to sample matrix effects, as indicated by % process efficiencies (a measure of ESI(-) enhancement/suppression), which were in the 111-128% range. We report the first known assessment of triclosan in the Detroit River watershed of the Great Lakes, which preliminarily examined the presence and UV-treatment effects on triclosan in effluent from the major WSTP serving the City of Windsor, Ontario, Canada, and fate in surface waters of the upper Detroit River. Triclosan in WSTP effluent decreased 22% after final UV treatment to a mean concentration of 63 ng/L. Concentrations were further reduced to 4 and 8 ng/L (a >90% reduction) in surface water samples from sites downstream on the Canadian shoreline of the Detroit River, which was due to dilution. Two hydroxylated tribrominated diphenyl ethers, which are structurally similar to triclosan, were also detected in WSTP effluent and surface water samples.