Mass concentrations of chemical compounds in both PM2.5 (particle aerodynamic diameter, Dp < 2.5 μm) and PM2.5-10 (2.5 < Dp < 10 μm), and acidity of aerosol particles were measured at an urban site in western Japan using a continuous dichotomous Aerosol Chemical Speciation Analyzer (ACSA-12) throughout 2014. Mass concentrations of both PM2.5 and sulfate had distinct seasonal variabilities with maxima in spring and winter, mostly due to long-range transport with the prevailing westerly wind. Mass concentration of nitrate in PM2.5 (fNO3) showed an obvious warm-season-low and cold-season-high pattern as a result of both gas-aerosol phase equilibrium processes under high temperature conditions as well as transport. Nitrate in PM2.5-10 (cNO3) increased during long-range transport of dust, implying the great importance of heterogeneous processes at the surface of coarse mode particles. In this study, Δ[H+] (derived from the difference in pH of extract liquid with/without sampling) was used to indicate the acidity of particles. We found that acidity of particles in PM2.5 (fΔH) was mostly positive with a maximum in August because of the large fraction of nitrate and sulfate. Acidity of particles in PM2.5-10 (cΔH) was negative in winter and spring due to presence of alkaline matter from crustal sources. This study highlights the great importance of anthropogenic pollutants on the acidity of particles in the western Pacific Ocean and further impact on the marine environment and climate.

Mercury (Hg) is a potent neurotoxicant known to induce important adverse effects on fish, but a deeper understanding is lacking regarding how environmental exposure affects the brain morphology and neural plasticity of specific brain regions in wild specimens. In this work, it was evaluated the relative volume and cell density of the lateral pallium, hypothalamus, optic tectum and molecular layer of the cerebellum on wild Liza aurata captured in Hg-contaminated (LAR) and non-contaminated (SJ) sites of a coastal system (Ria de Aveiro, Portugal). Given the season-related variations in the environment that fish are naturally exposed, this assessment was performed in the winter and summer. Hg triggered a deficit in cell density of hypothalamus during the winter that could lead to hormonal dysfunctions, while in the summer Hg promoted larger volumes of the optic tectum and cerebellum, indicating the warm period as the most critical for the manifestation of putative changes in visual acuity and motor-dependent tasks. Moreover, in fish from the SJ site, the lateral pallium relative volume and the cell density of the hypothalamus and optic tectum were higher in the winter than in summer. Thus, season-related stimuli strongly influence the size and/or cell density of specific brain regions in the non-contaminated area, pointing out the ability of fish to adapt to environmental and physiological demands. Conversely, fish from the Hg-contaminated site showed a distinct seasonal profile of brain morphology, presenting a larger optic tectum in the summer, as well as a larger molecular layer of the cerebellum with higher cell density. Moreover, Hg exposure impaired the winter-summer variation of the lateral pallium relative size (as observed at SJ). Altogether, seasonal variations in fish neural morphology and physiology should be considered when performing ecotoxicological studies in order to better discriminate the Hg neurotoxicity.

PM₁ might be more hazardous than PM₂.₅ (particulate matter with an aerodynamic diameter ≤ 1 μm and ≤2.5 μm, respectively). However, studies on PM₁ concentrations and its health effects are limited due to a lack of PM₁ monitoring data.To estimate spatial and temporal variations of PM₁ concentrations in China during 2005–2014 using satellite remote sensing, meteorology, and land use information.Two types of Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 aerosol optical depth (AOD) data, Dark Target (DT) and Deep Blue (DB), were combined. Generalised additive model (GAM) was developed to link ground-monitored PM₁ data with AOD data and other spatial and temporal predictors (e.g., urban cover, forest cover and calendar month). A 10-fold cross-validation was performed to assess the predictive ability.The results of 10-fold cross-validation showed R² and Root Mean Squared Error (RMSE) for monthly prediction were 71% and 13.0 μg/m³, respectively. For seasonal prediction, the R² and RMSE were 77% and 11.4 μg/m³, respectively. The predicted annual mean concentration of PM₁ across China was 26.9 μg/m³. The PM₁ level was highest in winter while lowest in summer. Generally, the PM₁ levels in entire China did not substantially change during the past decade. Regarding local heavy polluted regions, PM₁ levels increased substantially in the South-Western Hebei and Beijing-Tianjin region.GAM with satellite-retrieved AOD, meteorology, and land use information has high predictive ability to estimate ground-level PM₁. Ambient PM₁ reached high levels in China during the past decade. The estimated results can be applied to evaluate the health effects of PM₁.

2,4,6-Tribromophenol is the most widely produced brominated phenol. In the present review, we summarize studies dealing with this substance from an environmental point of view. We cover concentrations in the abiotic and biotic environment including humans, toxicokinetics as well as toxicodynamics, and show gaps of the current knowledge about this chemical.2,4,6-Tribomophenol occurs as an intermediate during the synthesis of brominated flame retardants and it similarly represents a degradation product of these substances. Moreover, it is used as a pesticide but also occurs as a natural product of some aquatic organisms. Due to its many sources, 2,4,6-tribromophenol is ubiquitously found in the environment. Nevertheless, not much is known about its toxicokinetics and toxicodynamics. It is also unclear which role the structural isomer 2,4,5-tribromophenol and several degradation products such as 2,4-dibromophenol play in the environment. Due to new flame retardants that enter the market and can degrade to 2,4,6-tribromophenol, this compound will remain relevant in future years – not only in aquatic matrices, but also in house dust and foodstuff, which are an important exposure route for humans.

The top-selling strobilurin, azoxystrobin (AZ), is a broad-spectrum fungicide that protects against many kinds of pathogenic fungi by preventing their ATP production. The extensive use of AZ can have negative consequences on non-target species and its effects and toxic mechanisms on algae are still poorly understood. In this work, Chlorella pyrenoidosa that had been grown in BG-11 medium was exposed to AZ (0.5–10 mg L⁻¹) for 10 d. The physiological and molecular responses of the algae to AZ treatment, including photosynthetic efficiency, lipid peroxidation level, antioxidant enzyme activities, as well as transcriptome-based analysis of gene expression, were examined to investigate the potential toxic mechanism. Results shows that the photosynthetic pigment (per cell) increased slightly after AZ treatments, indicating that the photosystem of C. pyrenoidosa may have been strengthened. Glutathione and ascorbate contents were increased, and antioxidant enzyme activities were induced to relieve oxidative damage (e.g., from lipid peroxidation) in algae after AZ treatment. Transcriptome-based analysis of gene expression combined with physiological verification suggested that the 5 mg L⁻¹ AZ treatment did not inhibit ATP generation in C. pyrenoidosa, but did significantly alter amino acid metabolism, especially in aspartate- and glutamine-related reactions. Moreover, perturbation of ascorbate synthesis, fat acid metabolism, and RNA translation was also observed, suggesting that AZ inhibits algal cell growth through multiple pathways. The identification of AZ-responsive genes in the eukaryotic alga C. pyrenoidosa provides new insight into AZ stress responses in a non-target organism.

Indo-Pacific humpback dolphin (Sousa chinensis) are chronically exposed to organic pollutants since they inhabit shallow coastal waters that are often impacted by anthropogenic activities. The aim of this review was to evaluate existing knowledge on the occurrence of organic pollutants in Indo-Pacific humpback dolphins, identify knowledge gaps, and offer recommendations for future research directions. We discussed the trends in the bioaccumulation of organic pollutants in Indo-Pacific humpback dolphins focusing on sources, physicochemical properties, and usage patterns. Furthermore, we examined factors that influence bioaccumulation such as gender, age, dietary intake and tissue-specific distribution. Studies on bioaccumulation in Indo-Pacific humpback dolphin remain scarce, despite high concentrations above 13,000 ng/g lw we previously detected for PFOS, ∑PBDE and chlorinated paraffins. The maximum concentration of organochlorines detected was 157,000 ng/g wt. Furthermore, variations in bioaccumulation were shown to be caused by factors such as usage patterns and physicochemical properties of the pollutant. However, restrictions in sampling inhibit investigations on exposure pathway and toxicity of organic pollutants in Indo-Pacific humpback dolphin. We proposed the use of biopsy sampling, predictive bioaccumulation and toxicity modeling, and monitoring other emerging contaminants such as microplastics and pharmaceuticals for future health risk assessment on this critically endangered marine mammal species.

Tools to predict environmental fate processes during remediation of persistent organic pollutants (POPs) in soil are desperately needed since they can elucidate the overall behavior of the chemical and help to improve the remediation process. A dynamic multimedia fate model (SoilPlusVeg) was further developed and improved to account for rhizoremediation processes. The resulting model was used to predict Polychlorinated Biphenyl (PCB) fate in a highly contaminated agricultural field (1089 ng/g d.w.) treated with tall fescue (Festuca arundinacea), a promising plant species for the remediation of contaminated soils. The model simulations allowed to calculate the rhizoremediation time (about 90 years), given the available rhizoremediation half-lives and the levels and fingerprints of the PCB congeners, to reach the legal threshold, to show the relevance of the loss processes from soil (in order of importance: degradation, infiltration, volatilization, etc.) and their dependence on meteorological and environmental dynamics (temperature, rainfall, DOC concentrations). The simulations showed that the effective persistence of PCBs in soil is deeply influenced by the seasonal variability. The model also allowed to evaluate the role of DOC as a possible enhancer of PCB degradation as a microorganism “spoon feeder” of PCBs in the soil solution. Additionally, we preliminary predicted how the contribution of PCB metabolites could modify the PCB fingerprint and their final total concentrations. This shows that the SoilPlusVeg model could be used in selecting the best choices for a sustainable rhizoremediation of a POP contaminated site.

Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or mixed-culture studies using targeted qPCR. In this study, four different levels of TCS were continuously fed to triplicate lab-scale anaerobic digesters to assess the effect of TCS levels on the antibiotic resistance gene profiles (resistome). Blasting metagenomic reads against antibiotic/metal resistance gene database (BacMet) revealed that ARG diversity and abundance changed along the TCS concentration gradient. While loss of bacterial diversity and digester function were observed in the digester treated with the highest TCS concentration, FabV, which is a known TCS resistance gene, increased in this extremely high TCS environment. The abundance of several other known ARG or metal resistance genes (MRGs), including corA and arsB, also increased as the concentrations of TCS increased. Analysis of other functional genes using SEED database revealed the increase of potentially key genes for resistance including different types of transporters and transposons. These results indicate that antimicrobials can alter the abundance of multiple resistance genes in anaerobic digesters even when function (i.e. methane production) is maintained. This study also suggests that enriched ARGs could be released into environments with biosolids land application.

Ecological quality objectives (EcoQOs), as tools for implementing ecosystem approach, have long been acknowledged to protect the marine ecosystems and fisheries in regional seas through joint efforts by surrounding countries over the past decade. The present review analyzed the best available meta-data relating to the five ecosystem elements that were recently proposed by the Northwest Pacific Action Plan to evaluate the current status of coastal ecosystem health in marine environment of the Yellow Sea. We suggested the six tentative EcoQOs among five ecological quality elements including: 1) biological and habitat diversity; 2) invasive species; 3) eutrophication; 4) pollutants; and 5) marine litters. Environmental status was assessed, depending on the EcoQOs targets, by comparison to the world average values, existing environmental standards, or reported values of other regional seas. Results of analysis revealed that among the six tentative EcoQOs, two target objectives to marine biodiversity and concentrations of nutrients (viz., DIN and DIP) were met towards good environmental status. Whilst, three EcoQOs relating to hypoxia and red-tide, pollutants (persistent toxic substances and metals), and marine litters (including microplastics) did not meet and one relating to invasive species could not be judged due to insufficient data sets. The biggest weak point for developing suitable EcoQOs and assessing status of ecosystem health could be insufficient meta-data sets available and/or discrepancy in methodological details cross the data-sets or between the two targeted countries. Thus, the cooperation of neighboring countries, viz., Korea and China for the Yellow Sea, is necessary for the ecosystem based management of our regional sea in the future. Overall, this first time review for the assessment of target tentative EcoQOs in the Yellow Sea region encompassing coasts of Korea and China would provide a better understanding of the current status of environmental pollution and ecosystem health.

Sea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1–10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27–38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans.