The environmental quality of an acid mine drainage polluted river (Odiel River) in the Iberian Pyrite Belt (SW Spain) was assessed by combining analyses of biomarkers (DNA strand breaks, LPO, EROD, GST, GR, GPx) in freshwater clams (Corbicula fluminea) exposed during 14 days and correlated with metal(loid) environmental concentrations.Results pointed that enzymatic systems are activated to combat oxidative stress in just 24 h. Along exposure, there were homeostatic regulations with the glutathione activity that influenced in lipid peroxidation oscillations, provoking significant DNA strand damage after 14 exposure days. EROD activity showed no changes throughout the exposure period.The Asian clam displayed balance biomarkers of exposure–antioxidant activity under non–stressfully environments; meanwhile, when was introduced into acid polymetallic environments, such as the acid mine drainage, its enzymatic activity was displaced towards biomarkers of effect and the corresponding antioxidant activity.

Biochar has potential for application for in situ metal-contaminated sediment remediation, mainly because of its cost-effectiveness. In this study, the effectiveness of Phyllostachys pubescens (PP) biochar for immobilization of cadmium (Cd) chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) by decreasing the bioavailable fraction was investigated using a series of laboratory sediment remediation microcosms. The results demonstrated that biochar could significantly reduce the bioavailable fraction of metals (except for Cr) by diffusive gradients in thin film (DGT) measurement in porewater. Additionally, amended sediment treated with 15% w/w biochar resulted in 79.71%, 73.20%, 54.86%, 49.75%, 31.16% and 0.99% reductions in the acid-soluble fraction for Cu, Pb, Ni, Zn, Cd, and Cr, respectively. Similarly, bioaccumulation of metals (except for Cr) by Limnodrilus hoffmeisteri was reduced by 18.45%–59.15% in biochar amended sediment. PP biochar at 15% could also reduce the inhibition or lethality rate by 37.5%, 18.1% and 36.3% for Chlorella vulgaris, Daphnia magna and luminescent bacteria Vibrio qinghaiensis, respectively. Overall, these results demonstrate the potential for biochar application for in situ sediment remediation.

Coal combustion is a major energy source in the US. The solid waste product of coal combustion, coal combustion residue (CCR), contains potentially toxic trace elements. Before 1980, the US primarily disposed of CCR in aquatic settling basins. Animals use these basins as habitat and can be exposed to CCR, potentially affecting their physiology. To investigate the effects of CCR on eastern mud turtles (Kinosternon subrubrum), we sampled 30 turtles exposed to CCRs and 17 unexposed turtles captured in 2015–2016 from the Savannah River Site (Aiken, SC, USA). For captured turtles, we (1) quantified accumulation of CCR in claw and blood samples, (2) used bacterial killing assays to assess influences of CCR on immune responses, (3) compared hemogregarine parasite loads, and (4) compared metabolic rates via flow-through respirometry between CCR-exposed and unexposed turtles when increased temperature was introduced as an added stressor. Turtles exposed to CCR accumulated CCR-associated trace elements, corroborating previous studies. Blood Se and Sr levels and claw As, Se, and Sr levels were significantly higher in turtles from contaminated sites. Average bacterial killing efficiency was not significantly different between groups. Neither prevalence nor average parasite load significantly differed between CCR-exposed and reference turtles, although parasite load increased with turtle size. Regardless of site, temperature had a significant impact on turtle metabolic rates; as temperature increased, turtle metabolic rates increased. The effect of temperature on turtle metabolic rates was less pronounced for CCR-exposed turtles, which resulted in CCR-exposed turtles having lower metabolic rates than reference turtles at 30 and 35 °C. Our results demonstrate that turtles accumulate CCR from their environment and that accumulation of CCR is associated with changes in turtle physiological functions when additional stressors are present.

Real time chemical characterization of non-refractory submicron aerosols (NR-PM1) was carried out during post monsoon (September–October) via Aerosol Mass Spectrometer (AMS) at a polluted urban location of Kanpur, India. Organic aerosol (OA) was found to be the dominant species with 58% contribution to total NR-PM1 mass, followed by sulfate (16%). Overall, OA was highly oxidized (average O/C = 0.66) with the dominance of oxidized OAs (60% of total OA) as revealed by source apportionment. Oxidized nature of OA was also supported by very high OC/EC ratios (average = 8.2) obtained from simultaneous offline filter sampling. High and low OA loading periods have very dramatic effects on OA composition and oxidation. OA O/C ratios during lower OA loading periods were on average 30% higher than the same from high loading periods with significant changes in types and relative contribution from oxidized OAs (OOA). Comparison of OA sources and chemistry among post monsoon and other seasons revealed significant differences. Characteristics of primary OAs remain very similar, but features of OOAs showed substantial changes from one season to another. Winter had lowest OOA contribution to total OA but similar overall O/C ratios as other seasons. This reveals that processing of primary OAs, local atmospheric chemistry, and regional contributions can significantly alter OA characteristics from one season to another. This study provides interesting insights into the seasonal variations of OA sources and evolution in a very polluted and complex environment.

Birds are widely used to assess metal contamination in the environment and there are different approaches to determine the exposure level in individuals, some being destructive (collection of soft tissues) and some non-destructive (blood, feathers and excrement). The use of blood to detect internal concentrations of metals is an acknowledged method, but to what extent blood can predict the concentrations in soft tissues has been less well evaluated in wild terrestrial birds. The same is true for excrements. This study compares the non-destructive methods using blood and excrement with liver sampling, with respect to exposure and accumulation of the elements arsenic, cadmium, copper, lead and zinc in nestling pied flycatchers (Ficedula hypoleuca). Blood, liver and excrement reflected the environmental exposure of non-essential elements and were independent of nestling sex. There were asymptotic relationships between the concentration of arsenic, cadmium and lead in liver and blood, excrement and liver, and excrement and blood, but none for copper or zinc. Those relationships were generally stronger between liver and blood than between excrements and internal concentrations. Lead had the strongest associations for all matrixes. The conclusion is that blood is an appropriate tool to assess accumulation of arsenic, cadmium and especially lead, but that blood can underestimate the accumulation at highly contaminated sites. Excrement can also give an indication of metal accumulation, but may overestimate internal concentrations at high exposure, and individual variability makes direct comparisons between these matrices less appropriate.

Avoidance behaviour offers a highly relevant information as it reveals the ability to avoid (or not) possible toxic compounds in the field, hence it provides information on reasons for the presence/absence in the field. The earthworm Eisenia fetida was used to study avoidance behaviour to four silver forms (three nanomaterials (NMs) and one salt) over four time points (24, 48, 72 and 96 h), using OECD standard soil. Avoidance behaviour depended on both exposure material and concentration, but in general changed little with exposure duration. Avoidance was highest for the salt (AgNO₃) for all exposure durations and showed a continuous higher avoidance with time (based on EC₅₀ values). The AgNMs avoidance was in the order NM300K<AgNM-non coated = AgNM- PVP coated. It was not possible to identify one soil solution fraction that correlated with EC₅₀ across materials.

Given the lack of knowledge regarding climate change-chemical exposure interactions, it is vital to evaluate how these two drivers jointly impact aquatic species. Thus, for the first time, we aimed at investigating the combined effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on survival, growth, consumption rate and reproduction of the amphipod Gammarus locusta. For that, a full factorial design manipulating temperature [ambient temperature and warming (+4 °C)], pCO2 [normocapnia and hypercapnia (Δ pH 0.5 units)] and the progestin levonorgestrel (LNG: L1 – 10 ngLL−1 and L2 – 1000 ngLL−1, control – no progestin and solvent control – vehicle ethanol (0.01%)) was implemented for 21 days. G. locusta was strongly negatively affected by warming, experiencing higher mortality rates (50–80%) than in any other treatments. Instead, growth rates were significantly affected by interactions of LNG with temperature and pCO2. It was observed, in the short-term (7d) that under ambient temperature (18 °C) and hypercapnic conditions (pH 7.6), the LNG presence promoted the amphipod's growth, while in the medium-term (21d) this response was not observed. Relative consumption rates (RCRs), during the first week were higher than in the third week. Furthermore, in the first week, RCRs were negatively affected by higher temperature while in the third week, RCRs were negatively affected by acidification. Furthermore, it was observed a negative effect of higher temperature and acidification on G. locusta fecundity, contrarily to LNG. Concluding, the impact of increased temperature and pCO2 was clearly more adverse for the species than exposure to the synthetic progestin, however, some interactions between the progestin and the climate factors were observed. Thus, in a future scenario of global change, the presence of LNG (and other progestins alike) may modulate to a certain level the effects of climate drivers (and vice-versa) on the gammarids fitness and reproduction.

The transfer of antibiotic resistance genes (ARGs) in the environment is a threat to both human and animal health. However, the contribution of bacteriophages to the dissemination of resistance genes via transduction is rarely explored. In this study, we screened pig feces from three commercial farms in China for 32 clinically relevant ARG types to assess the presence of the ARG population in bacteria and bacteriophage and further to estimate the contribution of bacteriophages to the dissemination of antibiotic resistance. We found that bacteriophage DNA contained 35.5% of the target ARG types and sul1, blaTEM and ermB were found in 100% of the phage DNA samples. The most abundant genes in the bacterial population were ermB and fexA whereas ermB was the most abundant in bacteriophage. In contrast, floR was the least abundant ARG in both populations. Also, the ratio index of the abundance of ARGs in bacteriophage and bacteria was firstly used in this study as an estimator of bacteriophage ability to transmit ARGs. The ratio for qnrA was the greatest (about 10−1) and differed from the most abundant bacteriophage ARG ermB. In addition, fexA had the lowest ratio value (about 10−6) and not floR. These results illustrate that ARGs abundance and detection rates used alone probably be not suitable for comprehensively judging the contribution of bacteriophage to the dissemination of antibiotic resistance. A more suitable model is the application of three indices; occurrence rate, absolute abundance in bacteriophage and the ratio value as warning and monitoring tools for environmental ARG assessments in bacteriophages.

Microplastics and mercury are environmental pollutants of great concern. The main goal of the present study was to investigate the effects of these pollutants, both individually and in binary mixtures, on the swimming performance of juvenile European seabass, Dicentrarchus labrax. Microplastics alone, mercury alone and all the mixtures caused significant reduction of the swimming velocity and resistance time of fish. Moreover, changes in behavioural responses including lethargic and erratic swimming behaviour were observed. These results highlight that fish behavioural responses can be used as sensitive endpoint to establish the effects of contamination by microplastics and also emphasizes the need to assess the combined effects of microplastics and other environmental contaminants, with special attention to the effects on behavioural responses in fish and other aquatic species.

Recent studies have indicated that urban streets can be hotspots for emissions of methane (CH4) from leaky natural gas lines, particularly in cities with older natural gas distribution systems. The objective of the current study was to determine whether leaking sewer pipes could also be a source of street-level CH4 as well as nitrous oxide (N2O) in Cincinnati, Ohio, a city with a relatively new gas pipeline network. To do this, we measured the carbon (δ13C) and hydrogen (δ2H) stable isotopic composition of CH4 to distinguish between biogenic CH4 from sewer gas and thermogenic CH4 from leaking natural gas pipelines and measured CH4 and N2O flux rates and concentrations at sites from a previous study of street-level CH4 enhancements (77 out of 104 sites) as well as additional sites found through surveying sewer grates and utility manholes (27 out of 104 sites). The average isotopic signatures for δ13C-CH4 and δ2H-CH4 were −48.5‰ ± 6.0‰ and −302‰ ± 142‰. The measured flux rates ranged from 0.0 to 282.5 mg CH4 day−1 and 0.0–14.1 mg N2O day−1 (n = 43). The average CH4 and N2O concentrations measured in our study were 4.0 ± 7.6 ppm and 392 ± 158 ppb, respectively (n = 104). 72% of sites where fluxes were measured were a source of biogenic CH4. Overall, 47% of the sampled sites had biogenic CH4, while only 13% of our sites had solely thermogenic CH4. The other sites were either a source of both biogenic and thermogenic CH4 (13%), and a relatively large portion of sites had an unresolved source (29%). Overall, this survey of emissions across a large urban area indicates that production and emission of biogenic CH4 and N2O is considerable, although CH4 fluxes are lower than those reported for cities with leaky natural gas distribution systems.