The sulfentrazone dechlorination using bimetallic nanoparticles of Fe/Ni was studied. Different variables that could influence the sulfentrazone conversion were investigated, such as nitrogen atmosphere, pH and dosage of the nanoparticles and initial concentration of sulfentrazone. The best results were obtained using controlled pH (pH 4.0) and 1.0 g L⁻¹ of nanomaterials, resulting in 100 % conversion in only 30 min. Kinetic studies were also conducted, evaluating the influence of different nanoparticle dosages (1.0 to 4.0 g L⁻¹), system temperatures (20 to 35 °C) and nickel levels in the composition of the nanomaterials (0.025 to 0.10 gNi/gFe). The mechanism of sulfentrazone conversion has changed due a direct reduction on the catalytic activity sites and indirect reduction by atomic hydrogen. Both mechanisms have followed pseudo-first order models. The conversion rate improved when the dosage of the nanomaterials, system temperature and nickel content in the composition of the nanocomposites were increased. Finally, the conversion products were elucidated by mass spectrometry and toxicity assays were performed using Daphnia Similis. The results showed that the dechlorination product is less toxic than sulfentrazone.

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.

The spatial distributions and fates of selected legacy and emerging compounds were investigated and compared in surface sediments sampled along the Adriatic mud-wedge and in deep-sea regions from the southern Adriatic basin. Results indicated that the concentrations of legacy contaminants (PAHs, PCBs and DDTs) and emerging contaminants (tonalide, galaxolide, EHMC, octocrylene, BP3 and NP) ranged from 0.1 to 572 ng g−1 and from <LOD to 40.7 ng g−1, respectively. In general, higher concentrations and estimated burdens were detected in the northern Adriatic, highlighting the importance of the Po River as the major contributor for the inputs of legacy and emerging contaminants to sediments in the Adriatic Sea. Nevertheless, the prevalence of some UV filters and fragrances in the central and southern Adriatic indicates that the proximity to tourist areas and WWTPs discharges seems to affect the distribution of those compounds. The accumulation of contaminants in the deep-sea areas supports the inference that this region may act as an important repository for contaminants within the Adriatic Sea. Estimated annual contaminant accumulation reveals that both, legacy and emerging contaminants accumulate preferentially in the northern Adriatic (40–60% of the total annual contaminant accumulation), where the presence of legacy, and to a lesser extent emerging contaminants, are likely to pose an immediate or long-term hazard to resident biota.

In 2014, as an attempt to address the Zika health crisis by controlling the mosquito population, Brazil took the unprecedented action of applying a chemical larvicide, pyriproxyfen, to drinking water sources. The World Health Organization has established an acceptable daily intake of pyriproxyfen to be 100 μg per kg of body weight per day, but studies have demonstrated that at elevated doses (>5000 mg/kg), there are adverse effects in mice, rats and dogs. To better understand the potential developmental toxicity of pyriproxyfen, we utilized the embryonic zebrafish. Our results demonstrate that the concentration resulting in 50% of animals presenting adverse morphological effects (EC50), including craniofacial defects, was 5.2 μM for daily renewal exposure, and above this concentration, adverse behavioral effects were also observed in animals that followed a static exposure regimen. Thus, zebrafish data suggest that the developmental toxicity of pyriproxyfen may not be limited to insects.

We conducted a year-long WRF-Chem (Weather Research and Forecasting Chemical) model simulation of elemental carbon (EC) aerosol and compared the modeling results to the surface EC measurements in the Guanzhong (GZ) Basin of China. The main goals of this study were to quantify the individual contributions of different EC sources to EC pollution, and to find the major cause of the EC pollution in this region. The EC measurements were simultaneously conducted at 10 urban, rural, and background sites over the GZ Basin from May 2013 to April 2014, and provided a good base against which to evaluate model simulation. The model evaluation showed that the calculated annual mean EC concentration was 5.1 μgC m−3, which was consistent with the observed value of 5.3 μgC m−3. Moreover, the model result also reproduced the magnitude of measured EC in all seasons (regression slope = 0.98–1.03), as well as the spatial and temporal variations (r = 0.55–0.78). We conducted several sensitivity studies to quantify the individual contributions of EC sources to EC pollution. The sensitivity simulations showed that the local and outside sources contributed about 60% and 40% to the annual mean EC concentration, respectively, implying that local sources were the major EC pollution contributors in the GZ Basin. Among the local sources, residential sources contributed the most, followed by industry and transportation sources. A further analysis suggested that a 50% reduction of industry or transportation emissions only caused a 6% decrease in the annual mean EC concentration, while a 50% reduction of residential emissions reduced the winter surface EC concentration by up to 25%. In respect to the serious air pollution problems (including EC pollution) in the GZ Basin, our findings can provide an insightful view on local air pollution control strategies.

Influences of ozone (O3) on light-saturated rates of photosynthesis in crop leaves have been well documented. To increase our understanding of O3 effects on individual- or stand level productivity, a mechanistic understanding of factors determining canopy photosynthesis is necessary. We used a canopy model to scale photosynthesis from leaf to canopy, and analyzed the importance of canopy structural and leaf ecophysiological characteristics in determining canopy photosynthesis in soybean stands exposed to 9 concentrations of [O3] (37–116 ppb; 9-h mean). Light intensity and N content peaked in upper canopy layers, and sharply decreased through the lower canopy. Plant leaf area decreased with increasing [O3] allowing for greater light intensity to reach lower canopy levels. At the leaf level, light-saturated photosynthesis decreased and dark respiration increased with increasing [O3]. These data were used to calculate daily net canopy photosynthesis (Pc). Pc decreased with increasing [O3] with an average decrease of 10% for an increase in [O3] of 10 ppb, and which was similar to changes in above-ground dry mass production of the stands. Absolute daily net photosynthesis of lower layers was very low and thus the decrease in photosynthesis in the lower canopy caused by elevated [O3] had only minor significance for total canopy photosynthesis. Sensitivity analyses revealed that the decrease in Pc was associated with changes in leaf ecophysiology but not with decrease in leaf area. The soybean stands were very crowded, the leaves were highly mutually shaded, and sufficient light for positive carbon balance did not penetrate to lower canopy leaves, even under elevated [O3].

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.

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.

To assess pollution levels of major inorganic nitrogen species and their atmospheric deposition input to sensitive ecosystems in Sichuan Basin, southwest China, ambient concentrations of oxidized (NOy ∼ NO2, HNO3, NO3−) and reduced (NHx = NH3, NH4+) nitrogen species were collected at two urban sites during four one-month periods, each in a different season from July 2014 to April 2015. Estimated annual mean concentration of NOy was 20.3 and 13.5 μg N m−3 in Chengdu and Wanzhou, respectively, and NHx was 16.9 and 13.6 μg N m−3, respectively. Back trajectory cluster analysis indicated that high levels of NOy and NHx in Chengdu were mainly caused by local emissions while those in Wanzhou were caused by both the local emissions and long-range transport of pollutants. On annual basis, NO2 contributed the most to NOy, followed by NO3− and HNO3, accounting for 87.5%, 10.5% and 2.0%, respectively, of NOy in Chengdu, and 91.4%, 6.9% and 1.7%, respectively, in Wanzhou. NH3 was the predominant contributor to NHx, contributing 65.6% and 72.2% in Chengdu and Wanzhou, respectively. Dry deposition fluxes were estimated using the inferential method with measured ambient concentrations and modelled dry deposition velocities. The total inorganic nitrogen dry deposition flux was estimated to be 21.4 and 8.5 kg N ha−1 yr−1, with 44.3% and 41.4% from NOy in Chengdu and Wanzhou, respectively. NO2 and NH3 each contributed about 80% of NOy and NHx dry deposition, respectively. Wet deposition was only collected in Wanzhou, where the annual wet deposition of NO3− and NH4+ was 4.5 and 15.7 kg N ha−1 yr−1, respectively. The total wet plus dry deposition was 28.7 kg N ha−1 yr−1 in Wanzhou with 72.2% from reduced nitrogen. Therefore, controlling NH3 emissions from agricultural, traffic, waste containers and sewage system sources would be effective to reduce the total nitrogen deposition in the Sichuan Basin area.