Understanding of xenobiotic metabolism is necessary for risk assessment as well as toxicological research. In the present study, nanoLC/LTQ-Orbitrap mass based non-targeted metabolomics method coupled with ultra-performance liquid chromatography (UPLC)/triple quadrupole mass based targeted metabolomics method was carried out to investigate the stereoselective metabolism of benalaxyl in mouse hepatic microsomes. As a result, 7 metabolites of benalaxyl were identified, including 5 previously reported and 2 newly identified metabolites in present work. Hydroxylation, oxidation and esterolysis were major biotransformation reactions of benalaxyl in mouse hepatic microsomes. For stereoselective metabolism study, (−)-R-benalaxyl degraded much faster than its antipode with the t1/2 of 81.24 and 190.38 min for (−)-R- and (+)-S-benalaxyl, respectively. More importantly, stereoselectivity was also observed in the formation of the identified metabolites. In conclusion, the combined use of the mass spectrometry based targeted and non-targeted metabolomics provided a new approach to investigate stereoselective metabolism and identify novel metabolites of chiral pesticides. This study highlights the stereoselective metabolic profile of benalaxyl enantiomers and provides reliable data for benalaxyl toxicological risk assessment in mammal.

Information on environmental distribution and human exposures of polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDDs/Fs) are little reported. In the present study, workshop dust, soil and sediment samples from Longtang and Shijiao, the intensive e-waste recycling sites within Qingyuan City, southern China, were collected and analyzed following the standard method. PBDD/F concentrations (sum of eight 2378-substituted PBDD/F congeners) in different environmental matrices were in the range of 122–4667 ng kg−1 dry wt (dw) for workshop dust, 19.6–3793 ng kg−1 dw for the top soils, and 527 ng kg−1 dw for the surface sediment, which were substantially higher than those of reference sites. The long-distance transport of PBDDs/Fs also impacted the adjacent areas. Contribution of the most two toxic congeners (2,3,7,8-TBDD and 1,2,3,7,8-PeBDD) to the total toxic equivalent quantity (TEQ) increased significantly from “source” (dust) to “sink” (sediment). Dismantling and open burning were the two procedures contributing relatively higher level PBDDs/Fs to the atmosphere, while acid leaching would contaminate soils and waters directly. The estimated daily intakes of eight PBDD/F congeners via soil/dust ingestion and dermal absorption for local residents were higher than those contributed by seventeen PCDD/F congeners in the same set of samples. Children and e-waste processing workers were the most affected groups by the low-tech recycling activities there.

The CO2 and CH4 fluxes at the water–air interface were measured in shrimp (Marsupenaeus japonicus) monoculture ponds (S) with feed supply and shrimp-sea cucumber (Apostichopus japonicus) polyculture ponds (SS) without feed supply. During farming seasons of the whole year, cumulated CO2–C fluxes were −5.69 g m−2 (S) and 11.23 g m−2 (SS), respectively. The cumulated CO2 emissions from S and SS did not differ significantly. The cumulated CH4–C emissions from S (0.57 g m−2) were significantly higher than those from SS (0.068 g m−2). S absorbed C from the atmosphere with a mean absorption rate of −5.12 g m−2, whereas SS emitted C to the atmosphere with a mean emission rate of 11.30 g m−2. Over 20-year horizon, the compressive global warming potentials (cGWPs) were 33.55 (S) and 47.71 (SS), respectively, indicating both feeding and no-feeding mariculture ponds could promote global warming.

Pesticide pollution from agricultural field run-off or spray drift has been documented to impact river ecosystems worldwide. However, there is limited data on short- and long-term effects of repeated pulses of pesticide mixtures on biotic assemblages in natural systems. We used reported pesticide application data as input to a hydrological fate and transport model (Soil and Water Assessment Tool) to simulate spatiotemporal dynamics of pesticides mixtures in streams on a daily time-step. We then applied regression models to explore the relationship between macroinvertebrate communities and pesticide dynamics in the Sacramento River watershed of California during 2002–2013. We found that both maximum and average pesticide toxic units were important in determining impacts on macroinvertebrates, and that the compositions of macroinvertebrates trended toward taxa having higher resilience and resistance to pesticide exposure, based on the Species at Risk pesticide (SPEARpesticides) index. Results indicate that risk-assessment efforts can be improved by considering both short- and long-term effects of pesticide mixtures on macroinvertebrate community composition.

Sediment cores and soil samples were taken from nine lakes and their catchments across England with varying degrees of direct human disturbance. Mercury (Hg) analysis demonstrated a range of impacts, many from local sources, resulting from differing historical and contemporary site usage and management. Lakes located in industrially important areas showed clear evidence for early Hg pollution with concentrations in sediments reaching 400–1600 ng g−1 prior to the mid-19th century. Control of inputs resulting from local management practices and a greater than 90% reduction in UK Hg emissions since 1970 were reflected by reduced Hg pollution in some lakes. However, having been a sink for Hg deposition for centuries, polluted catchment soils are now the major Hg source for most lakes and consequently recovery from reduced Hg deposition is being delayed.

Palygorskite (PAL) is a good heavy metal adsorbent due to its high surface area, low cost, and environmentally compatibility. But the natural PAL has limited its adsorption capacity and selectivity. In this study, a cost-effective and readily-generated absorbent, l-threonine-modified palygorskite (L-PAL), was used and its performance for Cu(II) removal in simulated aquaculture wastewater was evaluated. After preparation, L-PAL was characterized by using Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis. The impacts of pH, adsorbent dosage, contact time, and initial Cu(II) concentration on the adsorption capacity of L-PAL were examined. The Cu(II) adsorption capacity on L-PAL was enhanced almost 10 times than that of raw PAL. The adsorption isotherms of Cu(II) fit the Langmuir isotherms, and the adsorption kinetics was dominated by the pseudo-second-order model. The thermodynamic parameters at four temperatures were calculated, which indicated that the adsorption was spontaneous and endothermic. The adsorption mechanism involves complexation, chelation, electrostatic attraction, and micro-precipitation. Furthermore, L-PAL is shown to have a high regeneration capacity. These results indicate that L-PAL is a cheap and promising absorbent for Cu(II) removal and hold potential to be used for aquaculture wastewater treatment.

Exposure models are needed to evaluate the chronic health effects of ambient ultrafine particles (<0.1 μm) (UFPs). We developed a land use regression model for ambient UFPs in Toronto, Canada using mobile monitoring data collected during summer/winter 2010–2011. In total, 405 road segments were included in the analysis. The final model explained 67% of the spatial variation in mean UFPs and included terms for the logarithm of distances to highways, major roads, the central business district, Pearson airport, and bus routes as well as variables for the number of on-street trees, parks, open space, and the length of bus routes within a 100 m buffer. There was no systematic difference between measured and predicted values when the model was evaluated in an external dataset, although the R² value decreased (R² = 50%). This model will be used to evaluate the chronic health effects of UFPs using population-based cohorts in the Toronto area.

The treatment of municipal wastewater in the Arctic is challenging due to a variety of financial, operational, climatic and technical issues. To better understand the efficacy of current wastewater treatment in this region and the hazard posed to receiving waters, we assessed the occurrence of nutrients and contaminants (i.e., pharmaceuticals, antibiotic resistance genes) as they moved through a lagoon-based treatment system in Cambridge Bay, Nunavut, Canada. Wastewater treatment in this community is performed by the use of a lagoon-tundra wetland system that is discharged into the marine environment and is representative of current common practices throughout the region. In 2014, samples were collected before and during lagoon discharge from two locations in the main lagoon, one location downstream from the lagoon effluent and three locations offshore. Grab samples were collected to measure nutrients (e.g., total nitrogen and phosphorus) and the presence of antibiotic resistance gene-bearing microbes, and Polar Organic Chemical Integrative Samplers (POCIS) were deployed to collect passively organic contaminants in all locations. A total of six pharmaceuticals were detected from a screen of twenty-eight analytes during the study: atenolol, carbamazepine, clarithromycin, metoprolol, sulfamethoxazole and trimethoprim. The greatest concentrations of nutrients, antibiotic resistance genes (ARGs), and pharmaceuticals were found in sampling locations within the treatment lagoon. Offshore of the release point, we observed limited to no detection of pharmaceuticals and ARGs, but no change in total nitrogen and phosphorus from pre-release. We conclude that the current concentrations of monitored pharmaceuticals do not pose a significant hazard at this time to aquatic organisms in Cambridge Bay.

Exposure to metal pollution negatively affects animal physiology, including nutrient metabolism, but in the wild an effect can seldom be attributed to a single metal. Moreover, little is known about how the metabolism of vitamins, essential micronutrients for developing juveniles, is affected by toxic metals. Therefore we experimentally investigated the effects of lead (Pb), a widespread toxic metal, on four fat-soluble vitamins A (total and retinol), D3, E (total and α-tocopherol) and K and carotenoids (lutein, zeaxanthin and unidentified) in great tit (Parus major) nestlings. In addition to a control group where no Pb was provided, two Pb-dosed groups were compared to a metal exposed group in the vicinity of a Ni–Cu smelter. We examined whether Pb treatment affects vitamin homeostasis and how the response of Pb-treated birds relates to that of a population under industrial exposure of Pb and other metals. For this purpose, vitamin and carotenoid levels were quantified with UPLC-MS from plasma of 7 days-old nestlings. All metal exposed groups showed increased vitamin A and retinol levels. However, vitamin levels were not directly associated with fecal Pb levels, with the exception of retinol, which was positively correlated with fecal Pb. Alpha-tocopherol, lutein and zeaxanthin levels were positively associated with body mass and wing growth rate. To conclude, Pb exposure increased plasma vitamin A and retinol levels while the levels of other vitamins and carotenoids rather reflected secondary pollution effects via differences in habitat and diet quality at the smelter site. Our findings suggest Pb exposed nestlings may allocate the vitamins needed for growth and development to fight the physiological stress thus compromising their fitness.

To evaluate the influence of coal property and stove efficiency on the emissions of parent polycyclic aromatic hydrocarbons (pPAHs) and oxygenated PAHs (oPAHs) during the combustion, fifteen coal/stove combinations were tested in this study, including five coals of different geological maturities in briquette and chunk forms burned in two residential stoves. The emission factors (EFs) of pPAHs and oPAHs were in the range of 0.129–16.7 mg/kg and 0.059–0.882 mg/kg, respectively. The geological maturity of coal significantly affected the emissions of pPAHs and oPAHs with the lower maturity coals yielding the higher emissions. The chunk-to-briquette transformation of coal dramatically increased the emissions of pPAHs and oPAHs during the combustion of anthracite, whereas this transformation only elevated the emissions of high molecular weight PAHs for bituminous coals. The influence of stove type on the emissions of pPAHs and oPAHs was also geological-maturity-dependent. High efficiency stove significantly reduced the emissions of PAHs from those relatively high-maturity coals, but its influences on low-maturity coals were inconstant.