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The spotted salamander ( Ambystoma maculatum ) shares a unique endosymbiotic relationship with the unicellular green alga, Oophila amblystomatis . Despite studies isolating and identifying O. amblystomatis in salamander eggs , the taxonomic identity of the alga remains a point of ongoing debate. In this study, the nuclear SSU rRNA gene was used to characterize two well-supported Oophila clades that include lineages identified from past studies in addition to new isolates from the current study. These two clades do not form a monophyletic group and, furthermore, O. amblystomatis appears to be paraphyletic with numerous other chlamydomonad algae. To gain further insight into the biogeographic variation of the host A. maculatum , the mitochondrial ND4 and control gene regions were examined and the phylogeography was observed to be similar to that noted in the literature. Additionally, the response of O. amblystomatis to atrazine and 2,4-dichlorophenoxyacetic acid following 96 h exposure and a 96 h recovery phase was characterized, as this is a plausible mechanism by which the development of the host salamander could be impaired by herbicides. At the 96 h growth rate, no-observed-effect concentrations were 64 μg/L and 30 mg/L for atrazine and 2,4-D, respectively. We observed full recovery of O. amblystomatis at these concentrations within 96 h. These data suggest that atrazine and 2,4-D do not pose a significant risk to the symbiotic algae, or, indirectly, to the host salamander. In conclusion, we recommend a revision of the current taxonomy of O. amblystomatis , and demonstrate the need for species identification and thorough phylogenetic reconstruction in toxicity testing to accurately inform risk assessment.

Antibiotic resistance (AR) is a growing health concern worldwide and the Arctic represents an understudied region in terms of AR. This study aimed to quantify AR genes (ARGs) from effluent released from a wastewater treatment plant (WWTP) in Iqaluit, Nunavut, Canada, thus creating a baseline reference for future evaluations. Water, sediment, and truncate softshell clam ( Mya truncata) tissue samples were compared from the wastewater, the receiving environment of Frobisher Bay, and nearby undisturbed freshwaters. The pharmaceuticals and personal care products (PPCPs) atenolol, carbamazepine, metoprolol, naproxen, sulfapyridine, and trimethoprim were found in the wastewater, but the PPCPs were undetectable in the receiving environment. However, the relative abundances of ARGs were significantly higher in wastewater than in the receiving environment or reference sites. Abundances did not significantly differ in Frobisher Bay compared to undisturbed reference sites. ARGs in clams near the WWTP had similar relative abundances as those from pristine areas. The lack of ARG detection is likely due to Frobisher Bay tides flushing inputs to levels below detection. These data suggest that the WWTP infrastructure does not influence the receiving environment based on the measured parameters; more importantly, further research must elucidate the impact and fate of AR and PPCPs in Arctic communities.

This paper presents a semiquantitative method to help ecotoxicologists evaluate the consistency of data within the available peer-reviewed literature. In this case study, we queried whether there is consistent evidence of direct toxicity in Anurans exposed to atrazine at concentrations ≤ 100 μg/L under laboratory conditions. Atrazine was selected because of the relatively large repository of Anuran toxicity data. To accomplish this, we interrogated available data found in recent quantitative weight-of-evidence risk assessments for atrazine with a series of yes or no questions developed a priori. The questions examined consistency of reported effects within and between studies, within and between species, and across a wide range of endpoints categories (e.g., survivorship, growth and development, reproduction). The analysis found no compelling evidence of a consistent direct effect in Anurans around growth and development, reproduction, or survivorship at concentrations of up to at least 100 μg/L atrazine in laboratory studies. Further work is needed to refine the approach, including accounting for the magnitude of the reported effects. However, we recommend that ecotoxicologists employ some method of formal consistency of effects assessment method routinely before performing toxicity tests, in the contextualizing of new data, and in reviews of contaminants.

The objectives of this study were to: (1) characterize the exposure of aquatic ecosystems in Southern Ontario, Canada to pesticides between 2002 and 2016 by constructing environmental exposure distributions (EEDs), including censored data; and (2) predict the probability of exceeding acute regulatory guidelines. Surface water samples were collected over a 15-year period by Environment and Climate Change Canada. The dataset contained 167 compounds, sampled across 114 sites, with a total of 2,213 samples. There were 67,920 total observations of which 55,058 were non-detects (81%), and 12,862 detects (19%). The most commonly detected compound was atrazine, with a maximum concentration of 18,600 ngL− 1 and ~ 4% chance of exceeding an acute guideline (1,000 ngL− 1) in rivers and streams. Using Southern Ontario as a case study, this study provides insight into the risk that pesticides pose to aquatic ecosystems and the utility of EEDs that include censored data for the purpose of risk assessment.

Fresh produce is an important component of maintaining cognitive and physical health, particularly for children. A mechanism to increase access to fresh produce is the construction of community gardens in urban centres. While reducing barriers to nutritious food, the soil of the community garden can contain contaminants (e.g. metals) depending on the location and how the garden was constructed. This study quantified, for the first time, seven metals (As, Cd, Cr, Cu, Pb, Mn, and Ni) in soil from 83 community gardens across the City of Winnipeg in Manitoba, Canada. Concentrations of metals in soil were used to create distributions for environmental exposure and estimated daily intake, which were then used to determine exceedances of soil quality guidelines and acceptable daily intakes, respectively. Raised garden beds and gardens further from roads had typically lower concentrations of metals in surface gardens and those nearer to roads. While some concentrations of metals exceeded CCME guidelines levels for the protection of environmental health, the vast majority represent a low risk. For human health, only As posed a quantifiable risk of exceeding the USEPA acceptable daily intake via the consumption of produce from gardens, though this was < 1.2% for the whole population and < 10.2% for children aged 1 to 2 years. Overall, this study is the first to show that the concentration of the metals in soil from gardens typically poses a low risk to environmental and human health. We recommend the use of raised gardens to further mitigate risk.

A comprehensive evaluation of public participation in rural domestic waste (RDW) source-separated collection in China was carried out within a social-dimension framework, specifically in terms of public perception, awareness, attitude, and willingness to pay for RDW management. The evaluation was based on a case study conducted in Guilin, Guangxi Zhuang Autonomous Region, China, which is a representative of most inland areas of the country with a GDP around the national average. It was found that unlike urban residents, rural residents maintained a high rate of recycling, but in a spontaneous manner; they paid more attention to issues closely related to their daily lives, but less attention to those at the general level; their awareness of RDW source-separated collection was low and different age groups showed significantly different preferences regarding the sources of knowledge acquirement. Among potential information sources, village committees played a very important role in knowledge dissemination; for the respondents’ pro-environmental attitudes, the influencing factor of “lack of legislation/policy” was considered to be significant; mandatory charges for waste collection and disposal had a high rate of acceptance among rural residents; and high monthly incomes had a positive correlation with both public pro-environmental attitudes and public willingness to pay for extra charges levied by RDW management. These observations imply that, for decision-makers in the short term, implementing mandatory RDW source-separated collection programs with enforced guidelines and economic compensation is more effective, while in the long run, promoting pro-environmental education to rural residents is more important.

The use of recycled glass as a substrate for constructed wetlands was assessed through two studies. The first study examined the dissipation of atenolol, carbamazepine, and sulfamethoxazole in mesocosm-modeled wetlands using glass or limestone gravel as substrates, with or without cattails ( Typha spp . ). Following pseudo-first-order kinetics, atenolol dissipated the fastest from the water surface of the mesocosms (t 1/2 ~1 day), followed by sulfamethoxazole (t 1/2 ~14 days), and carbamazepine (t 1/2 ~48 days), with no significant differences across treatments. Increased half-lives were observed at greater depth, likely due to light screening. A Monte Carlo sensitivity analysis diagnosed sunlight absorption rates and second-order hydroxyl-mediated indirect photolysis rates to be the main sources of uncertainty in our dissipation rate estimates, compared to our observed rates. The second study examined in situ pharmaceutical removal in tertiary pilot-scale subsurface filters made of crushed recycled glass or sand in a wastewater treatment facility in Manitoba, Canada. Glass and sand showed no significant differences for pharmaceutical removals; atenolol and metoprolol were removed below limits of detection, while carbamazepine and sulfamethoxazole persisted over a retention time of 24 h. Overall, recycled glass performed similarly to traditional substrates for wetland-based wastewater treatment.

The influence of relative isolation on the ecological recovery of freshwater outdoor mesocosm communities after an acute toxic stress was assessed in a 14-month-long study. A single concentration of deltamethrin was applied to 8 out of 16 outdoor 9-m3 mesocosms to create a rapid decrease of the abundance of arthropods. To discriminate between external and internal recovery mechanisms, four treated and four untreated (control) mesocosms were covered with 1-mm mesh screen lids. The dynamics of planktonic communities were monitored in the four types of ponds. The abundance of many phytoplankton taxa increased after deltamethrin addition, but the magnitude of most increases was relatively small, probably due to low nutrient availability and the survival of rotifers. The greatest impact on zooplankton was seen in Daphniidae and, to a lesser extent, calanoid copepods. Recovery (defined as when statistical analysis failed to detect a difference in the abundance between the deltamethrin-treated ponds and corresponding control ponds for two consecutive sampling dates) of Daphniidae was observed in the water column 105 and 77 d after deltamethrin addition in open and covered mesocosms, respectively, and 42 d for both open and covered ponds at the surface of the sediments. Rotifers did not proliferate, probably because of the survival of predators (e.g., cyclopoid copepods). These results confirm that the recovery of planktonic communities after exposure to a strong temporary chemical stress mostly depends upon internal mechanisms (except for larvae of the insect Chaoborus sp.) and that recovery dynamics are controlled by biotic factors, such as the presence of dormant forms and selective survival of predators.

Doc number: 54 Abstract Background: The discharge of complex mixtures of nutrients, organic micropollutants, and antibiotic resistance genes from treated municipal wastewater into freshwater systems are global concerns for human health and aquatic organisms. Antibiotic resistance genes (ARGs) are genes that have the ability to impart resistance to antibiotics and reduce the efficacy of antibiotics in the systems in which they are found. In the rural community of Grand Marais, Manitoba, Canada, wastewater is treated passively in a sewage lagoon prior to passage through a treatment wetland and subsequent release into surface waters. Using this facility as a model system for the Canadian Prairies, the two aims of this study were to assess: (a) the presence of nutrients, micropollutants (i.e., pesticides, pharmaceuticals), and ARGs in lagoon outputs, and (b) their potential removal by the treatment wetland prior to release to surface waters in 2012. Results: As expected, concentrations of nitrogen and phosphorus species were greatest in the lagoon and declined with movement through the wetland treatment system. Pharmaceutical and agricultural chemicals were detected at concentrations in the ng/L range. Concentrations of these compounds spiked downstream of the lagoon following discharge and attenuation was observed as the effluent migrated through the wetland system. Hazard quotients calculated for micropollutants of interest indicated minimal toxicological risk to aquatic biota, and results suggest that the wetland attenuated atrazine and carbamazepine significantly. There was no significant targeted removal of ARGs in the wetland and our data suggest that the bacterial population in this system may have genes imparting antibiotic resistance. Conclusions: The results of this study indicate that while the treatment wetland may effectively attenuate excess nutrients and remove some micropollutants and bacteria, it does not specifically target ARGs for removal. Additional studies would be beneficial to determine whether upgrades to extend retention time or alter plant community structure within the wetland would optimize removal of micropollutants and ARGs to fully characterize the utility of these systems on the Canadian Prairies.