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.

Using the diffusive gradients in thin films (DGT) technique and microelectrode technique, hypoxia and its effects on the release of phosphorus (P) from sediments were carefully investigated in Hongfeng Reservoir, a typical deep-water ecosystem where eutrophication and hypoxia is still an environmental challenge in Southwest China. The results suggested that hypoxia significantly promotes the release of P from sediments and the release of P under hypoxic condition mostly comes from the release of BD–P. Together with the in-situ and high resolution evidences from DGT and microelectrode, the release of P from sediments under hypoxic condition was assumed to be coupled processes which are associated with the combined cycles of “P-Fe-S”. Evidences from the present work implied that the internal P-loadings induced by hypoxia, especially after a reduction of external P-loading, should be paid more attention in eutrophic deep-water reservoirs, Southwest China.

Exposure to airborne fine particulate matter (PM2.5) is associated with cardiovascular diseases. However, a comprehensive understanding of the underlying mechanisms by which PM2.5 induces or aggravates these diseases is still insufficiently clear. The present study investigated whether PM2.5 alters the expression of the endothelin subtype B (ETB) and endothelin subtype A (ETA) receptors in the coronary artery and examined the underlying mechanisms. Rat coronary artery segments were cultured with PM2.5 in the presence or absence of MEK/ERK1/2, JNK, and p38 pathway inhibitors. Contractile reactivity was measured by myography. ETB and ETA receptor expression was evaluated using RT-PCR, western blot and immunohistochemistry. Compared with fresh arteries, the cultured coronary arteries showed a significantly enhanced contraction mediated by the ETB receptor and an unaltered contraction mediated by the ETA receptor. Culture with PM2.5 significantly enhanced the contraction and the mRNA and protein expression levels of the ETB and ETA receptors in the coronary arteries, suggesting that PM2.5 induces an upregulation of ETA and ETB receptors. In addition, the PM2.5-induced increases in ETB- and ETA-mediated vasoconstriction and receptor expressions could be notably decreased by MEK1/2 inhibitor, U0126 and Raf inhibitor, SB386023, suggesting that the upregulation of ETB and ETA receptors is related with MEK/ERK1/2 pathway. In conclusion, PM2.5 induces the ETB and ETA receptor upregulation in rat coronary arteries, and the MEK/ERK1/2 pathway may be involved in this process.

To better understand interaction mechanism of sediment organic matter with hydrophobic organic compounds, sorption of phenanthrene (Phen) and nonylphenol (NP) by bulk sediments and their fractions was investigated. Three surface sediments were selectively fractionated into different organic fractions, including the demineralized carbon (DM), lipid free carbon (LF), lipid (LP), and nonhydrolyzable carbon (NHC) fractions. The structure and microporosity of the isolated fractions were characterized by NMR and CO2 adsorption techniques, and used as sorbents for Phen and NP. The calculated micropore volumes (Vo) and specific surface area (SSA) values are positively related to the concentrations of aromatic C and char for the DM, LF and NHC fractions, suggesting that aromatic moieties and char component significantly contribute to the microporosity. The LF fractions exhibit greater sorption affinity than the DM fractions do, indicating that the presence of LP could block the accessibility of sorption sites for Phen and NP. Significant and positive correlations among log K′FOC values for Phen and NP and aromatic carbon and char contents, and Vo and SSA values suggest the aromatic moieties and microporosity dominate their sorption of HOCs by sediment organic matter (SOM). As the NHC fractions have much stronger sorption than other fractions do, they dominate the overall sorption by the bulk samples. This study indicated that the important roles of aromatic moieties, accessibility, and microporosity in the sorption of HOCs by SOM.

The extensive usage of OTC and Cu2+ in livestock and poultry industry caused high residues in natural environment. Co-contamination of OTC and Cu2+ was a considerable environmental problem in surface waters. In this study, Cu2+ mediated direct photolysis of OTC was studied. Cu2+ chelating with OTC was found to greatly inhibit OTC photodegradation. To reveal the chelation mechanism of OTC-Cu complexes, multiple methods including UV–Vis absorption spectra, Infrared (IR) spectra, mass spectroscopy, and density functional theoretical (DFT) modeling were performed. Four OTC-Cu complexes were proposed. Cu2+ preferably bond to O11O12 site with the binding constants logK = 8.19 and 7.86 for CuHL+ and CuL±, respectively. The second chelating site was suggested to be O2O3 with the binding constants of logK = 4.41 and 4.62 for Cu2HL3+ and Cu2L2+, respectively. The suppressed quantum yield of OTC by Cu2+ chelation was accused for their intra-/inter-molecular electron transfer, by which the energy in activated states was distributed. The occurrence of electron transfer between BCD ring and A ring also from BCD ring to Cu was evidenced by the TD-DFT result only for the OTC-Cu complexes. Besides, the cyclic voltammetry measurement also suggested one OTC-Cu(II)/OTC-Cu(I) redox couple. These results suggested that the persistence of OTC in environmental surface waters will probably be underestimated for neglecting the chelating effect of Cu2+. The photolysis quantum yield of OTC-Cu complexes, as well as the specific molar absorption constants, the equilibrium binding constants of Cu2+ with OTC could contribute to more accurate kinetic models of OTC.

Trace organic contaminants such as pharmaceuticals, personal care products and industrial chemicals are frequently detected in the urban water cycle, including wastewater, surface water and groundwater, as well as drinking water. These also include human metabolites (HMs), which are formed in the human body and then excreted via urine or feces, as well as transformation products (TPs) formed in engineered treatment systems and the aquatic environment. In the current study, the occurrence of HMs as well as their TPs of the anticonvulsants carbamazepine (CBZ) and oxcarbazepine (OXC) were investigated using LC tandem MS in effluents of wastewater treatment plants (WWTPs), surface water and groundwater. Highest concentrations were observed in raw wastewater for 10,11-dihydro-10,11-dihydroxycarbamazepine (DiOHCBZ), 10,11-dihydro-10-hydroxy-cabamazepine (10OHCBZ) and CBZ with concentrations ranging up to 2.7 ± 0.4, 1.7 ± 0.2 and 1.07 ± 0.06 μg L−1, respectively. Predictions of different toxicity endpoints using a Distributed Structure-Searchable Toxicity (DSSTox) expert system query indicated that several HMs and TPs, in particular 9-carboxy-acridine (9-CA-ADIN) and acridone (ADON), may exhibit an increased genotoxicity compared to the parent compound CBZ. As 9-CA-ADIN was also detected in groundwater, a detailed investigation of the genotoxicity of 9-CA-ADIN is warranted. Investigations of an advanced wastewater treatment plant further revealed that the discharge of the investigated compounds into the aquatic environment could be substantially reduced by ozonation followed by granular activated carbon (GAC) filtration.

Seabirds are ideal model organisms to track mercury (Hg) through marine food webs as they are long-lived, broadly distributed, and are susceptible to biomagnification due to foraging at relatively high trophic levels. However, using these species as biomonitors requires a solid understanding of the degree of species, sexual and age-specific variation in foraging behaviors which act to mediate their dietary exposure to Hg. We combined stomach content analysis along with Hg and stable isotope analyses of blood, feathers and common prey items to help explain inter and intra-specific patterns of dietary Hg exposure across three sympatric Pygoscelis penguin species commonly used as biomonitors of Hg availability in the Antarctic marine ecosystem. We found that penguin tissue Hg concentrations differed across species, between adults and juveniles, but not between sexes. While all three penguins species diets were dominated by Antarctic krill (Euphausia superba) and to a lesser extent fish, stable isotope based proxies of relative trophic level and krill consumption could not by itself sufficiently explain the observed patterns of inter and intra-specific variation in Hg. However, integrating isotopic approaches with stomach content analysis allowed us to identify the relatively higher risk of Hg exposure for penguins foraging on mesopelagic prey relative to congeners targeting epipelagic or benthic prey species. When possible, future seabird biomonitoring studies should seek to combine isotopic approaches with other, independent measures of foraging behavior to better account for the confounding effects of inter and intra-specific variation on dietary Hg exposure.

Harbours, as strategic places in tourism and transportation, are exposed to many sources of contamination. Assessing the quality of harbours sediment by guidelines and regulations does not reflect the actual level of contamination and the risk posed to aquatic ecosystems. Selection of an appropriate management technique for contaminated sediments in those strategic locations is crucial for the aquatic environment. The purpose of this study is to show that insufficient information, provided by sediment quality guidelines (SQGs) to identify the actual contaminants, could lead to a destructive or potentially ineffective decision for risk reduction in contaminated harbours. A comprehensive evaluation on physicochemical characteristics of sediment and water samples of a shallow harbour in St. Lawrence River was performed. Results of trace metal fractionation and risk assessment indicated that Cd and Pb were the contaminants that could pose a threat to aquatic ecosystem, although the SQG outcomes implied that Cu and Zn may cause an adverse effect on the benthic organisms. The results of multivariate statistical analysis demonstrated that the locations in the vicinity of the maintenance area contained the most contaminated sediment samples and require appropriate management. Antifouling paint particles and probably the runoff entering the harbour were the main sources of pollution. Among the diverse range of management strategies, the resuspension technique is suggested as a viable alternative in this specific case for shallow locations with contaminated sediments. A suitable management strategy could reduce the cost of remediation process by identifying the actual contaminated spots and also reduce the risk of remobilization of trace metals.

Cyanobacterial blooms threaten human health as well as the population of other living organisms in the aquatic environment, particularly due to the production of natural toxic components, the cyanotoxin. So far, the most studied cyanotoxins are microcystins (MCs). In this study, the hepatic alterations at histological, proteome and transcriptome levels were evaluated in female and male medaka fish chronically exposed to 1 and 5 μg L−1 microcystin-LR (MC-LR) and to the extract of MC-producing Microcystis aeruginosa PCC 7820 (5 μg L−1 of equivalent MC-LR) by balneation for 28 days, aiming at enhancing our understanding of the potential reproductive toxicity of cyanotoxins in aquatic vertebrate models. Indeed, both MC and Microcystis extract adversely affect reproductive parameters including fecundity and egg hatchability. The liver of toxin treated female fish present glycogen storage loss and cellular damages. The quantitative proteomics analysis revealed that the quantities of 225 hepatic proteins are dysregulated. In particular, a notable decrease in protein quantities of vitellogenin and choriogenin was observed, which could explain the decrease in reproductive output. Liver transcriptome analysis through Illumina RNA-seq reveals that over 100–400 genes are differentially expressed under 5 μg L−1 MC-LR and Microcystis extract treatments, respectively. Ingenuity pathway analysis of the omic data attests that various metabolic pathways, such as energy production, protein biosynthesis and lipid metabolism, are disturbed by both MC-LR and the Microcystis extract, which could provoke the observed reproductive impairment. The transcriptomics analysis also constitutes the first report of the impairment of circadian rhythm-related gene induced by MCs. This study contributes to a better understanding of the potential consequences of chronic exposure of fish to environmental concentrations of cyanotoxins, suggesting that Microcystis extract could impact a wider range of biological pathways, compared with pure MC-LR, and even 1 μg L−1 MC-LR potentially induces a health risk for aquatic organisms.

Fullerenes (e.g. C60, C70, etc.) present in soil may undergo changes in its retention with aging. In this study, the partitioning behavior of (14C)-C60 aged up to 12 weeks was investigated in biosolids-amended soil. Spiked samples were subjected to sequential partitioning using water, methanol, and toluene followed by total combustion of solids; the distribution of 14C across solvents and matrices were used to provide insights on C60 behavior. In most samples, 14C only partitioned in toluene with the remaining (non-extractable) activity detected in the solid phase. In all biosolids-amended soil samples, an increase in non-extractable 14C were observed for those exposed to light (vs dark) with the greatest difference observed in biosolids + sand samples. Possible processes that contribute to the observed 14C distribution, i.e. retention and potential transformation of C60, were discussed. Over-all, results suggest that environmental exposure to C60 and potentially transformed C60 species, as a result of their release from soils, is likely to be low.