We investigated the in vitro effects of pyriproxyfen on ionic balance in the testis of the zebrafish by measuring ⁴⁵Ca²⁺ influx. In vivo pyriproxyfen treatment was carried out to study oxidative stress, and conduct morphological analysis of the testis and liver. Whole testes were incubated in vitro with/without pyriproxyfen (10⁻¹², 10⁻⁹ or 10⁻⁶ M; 30 min) and ⁴⁵Ca²⁺ influx determined. To study pyriproxyfen’s mechanism of action, inhibitors/activators of ionic channels or pumps/exchangers, protein kinase inhibitors or a calcium chelator were added 15 min before the addition of ⁴⁵Ca²⁺ and pyriproxyfen. We evaluated the in vivo effects of 7 day exposure to waterborne pyriproxyfen (10⁻⁹ M) on reactive oxygen species (ROS) formation, lipid peroxidation, and reduced glutathione content (GSH), glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and γ-glutamyltransferase (GGT) activity. Morphological analyses of the testis and liver were carried out after in vivo exposure of D. rerio to pyriproxyfen. Pyriproxyfen increased ⁴⁵Ca²⁺ influx by opening the voltage-dependent T-type channels (T-type VDCC), inhibiting sarco/endoplasmic reticulum ⁴⁵Ca²⁺-ATPase (SERCA) and the NCX exchanger (forward mode) and by mobilizing calcium from stores. The involvement of potassium channels and protein kinase C (PKC) was also demonstrated in pyriproxyfen-induced intracellular calcium elevation. In vivo pyriproxyfen treatment of D. rerio increased lipid peroxidation, decreased GSH content and increased GST activity in testes, in addition to increasing the number and size of spermatogonia cysts and inducing hepatocyte basophilia and dilation of blood vessels in the liver. The toxicity of pyriproxyfen is mediated by calcium overload, increased lipid peroxidation, and a diminished antioxidant capacity in the testis, due to GSH depletion, and altered spermatogenesis. The development of high basophilia in the liver suggests that pyriproxyfen may have estrogenic activity, possibly acting as an endocrine-disruptor. These findings indicate that these alterations may contribute to pyriproxyfen toxicity and spermatogenesis disruption.

The spatial distributions, fluxes, and environmental effects of non-methane hydrocarbons (NMHCs) were investigated in the Yellow Sea (YS) and the East China Sea (ECS) in spring. The average concentrations of ethane, propane, i-/n-butane, ethylene, propylene and isoprene in the seawater were 18.1 ± 6.4, 15.4 ± 4.7, 6.8 ± 2.9, 6.4 ± 3.2, 67.1 ± 26.7, 20.5 ± 8.7 and 17.1 ± 11.1 pmol L⁻¹, respectively. The alkenes in the surface seawater were more abundant than their saturated homologs and NMHCs concentrations (with the exception of isoprene) decreased with carbon number. The spatial variations of isoprene were consistent with the distributions of chlorophyll a (Chl-a) and Chaetoceros, Skeletonema, Nitzschia mainly contributed to the production of isoprene, while the others’ distributions might be related to their photochemical production. Observations in atmospheric NMHCs indicated alkanes in the marine atmosphere decreased from inshore to offshore due to influence of the continental emissions, while alkenes were largely derived from the oceanic source. In addition, no apparent diurnal discrepancy of atmospheric NMHCs (except for isoprene) were found between daytime and night. As the main sink of NMHCs in seawater, the average sea-to-air fluxes of ethane, propane, i-/n-butane, ethylene and propylene were 31.70, 29.75, 18.49, 15.89, 239.6, 67.94 and 52.41 nmol m⁻² d⁻¹, respectively. The average annual emissions of isoprene accounted for 0.1–1.3% of the global ocean emissions, which indicated that the coastal and shelf areas might be significant sources of isoprene. Furthermore, this study represents the first effort to estimate the environmental effects caused by NMHCs over the YS and the ECS and the results demonstrated contributions of alkanes to ozone and secondary organic aerosol (SOA) formation were lower than those of the alkenes and the largest contributor was isoprene.

Two different methodologies were combined to evaluate the risks that antibiotics can pose in the environment; i) an effect-based methodology based on microbial growth inhibition and ii) an analytical method based on liquid-chromatography coupled to mass spectrometry (LC-MS). The first approach was adapted and validated for the screening of four antibiotic families, specifically macrolides/β-lactams, quinolones, sulfonamides and tetracyclines. The LC-MS method was applied for the identification and quantification of target antibiotics; then, the obtained results were combined with ecotoxicological data from literature to determine the environmental risk. The two methodologies were used for the analysis of antibiotics in water samples (wastewater, river water and seawater) and biofluids (fish plasma and mollusk hemolymph) in two monitoring campaigns undertaken in the Ebro Delta and Mar Menor Lagoon (both in the Mediterranean coast of Spain). Both approaches highlighted macrolides (azithromycin) and quinolones (ciprofloxacin and ofloxacin) as the main antibiotics in wastewater treatment plant (WWTP) effluents with potential risk for the environment. However, no risk for the aquatic life was identified in the river, lagoon and seawater as antibiotic levels were much lower than those in WWTP effluents. Fish from Ebro River were the organisms presenting the highest antibiotic concentration when compared with bivalves (mussels) from the Mediterranean Sea and gastropods (marine snails) from the Mar Menor Lagoon. The effect-based methodology successfully determined antibiotic risk in wastewater, but its applicability was less clear in environmental waters such as seawater, due to its high detection limits. Improving sample preconcentration could increase the method sensibility. Overall, combination of both methodologies provides comprehensive insights in antibiotic occurrence and risk associated in areas under study.

Polycyclic aromatic hydrocarbons (PAHs) in urban soils are of increasing concern because of their potential toxicity and persistence. However, there is limited information about PAHs in Tianjin coastal new region, although it is an important economic and industrial center in Northern China. Here we determined the concentrations of PAHs in 210 surface soil samples collected from this region according to administrative divisions covering Han’gu district, Tanggu district, and Dagang district, to evaluate their contamination and potential cancer risks. The concentrations of 16 PAHs ranged from 58.2 to 9160 ng g⁻¹, and the highest concentration was found in Han’gu district. According to the incremental lifetime cancer risk (ILCR) model, the soils from Han’gu district and Dagang district posed a moderate carcinogenic risk to residents, and dermal contact was the main exposure pathway. Besides, ILCRs for children through ingestion were comparable to those for adults but apparently higher than adolescents, while ILCRs of dermal contact for adults were higher than children and adolescents. Comparisons between the layout of industrial zones and the distributions of PAHs as well as ILCRs indicate that PAHs accumulating in soils and then incurring risk areas is partly controlled by the economic and industrial structure.

The hazardous effects of herbicides are well known; however, their effects on the reproductive system remain unclear. In this study, we demonstrated the anti-proliferative effects of dinitramine (DN) on immature murine testicular cell lines (Leydig and Sertoli cells) mediated via endoplasmic reticulum (ER) stress-induced calcium dysregulation in the cytosol and mitochondria. The results demonstrated that the viability and proliferation of DN-treated TM3 and TM4 cells decreased significantly, even in the spheroid state. DN induced the apoptosis of TM3 and TM4 cells and decreased the expression of genes related to cell cycle progression. Treatment with DN increased the cytosolic and intramitochondrial levels of calcium by activating ER stress signals. DN activated the Erk/P38/Jnk Mapk pathway and inactivated the Pi3k/Akt pathway in murine testicular cells. Co-treatment with 2-aminoethoxydiphenyl borate (2-APB) mitigated DN-induced calcium upregulation in both testicular cell lines. Although 2-APB did not antagonize the anti-proliferative effect of DN in TM3 cells, treatment with 2-APB and 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid restored the proliferation of DN-treated TM4 cells.

Potentially toxic Cylindrospermopsis raciborskii blooms are of emerging concerns, as its scale is spreading from tropical regions to high latitudes, increasing the risk of aquatic biota being exposed to cylindrospermopsin (CYN). So far, CYN-producing C. raciborskii strains have only been reported in tropical waters which are commonly phosphorus (P)-deficient, where they can dominate phytoplankton communities. However, the influence of CYN on phytoplankton communities under different P status remains unclear. In this study, we first analyzed the summer observations of 120 tropical reservoirs in Guangdong Province. The proportion of potential CYN-producers was significantly higher in P-deficient and CYN-present reservoirs than that in P-sufficient or CYN-absent ones. This suggested that in P-deficient condition, the potential CYN producers might gain more advantages by the help of CYN. Then, in laboratory experiments we found that upon P deprivation, CYN did not inhibit the cell growth of other algal cells, but significantly stimulates them to secret more alkaline phosphatase (ALP) than in P-sufficient condition. Through transcriptomics, we further revealed that under such P-deficient condition, CYN remarkably induced intracellular nitrogen allocation and protein export system by activating the PIK3/Akt-cGMP/PKG signaling pathways in Scenedesmus bijugatus, thus enhancing its ALP secretion. Our study implies that CYN-induced ALP secretion is facilitated upon P deficiency, thus supporting the dominance of its producers C. raciborskii.

Biochar has the potential to remediate heavy metals in agricultural soil and mitigate nitrous oxide (N₂O) emissions; however, the effects of biochar on heavy metal remediation, the soil microbial community and N₂O emissions are not completely understood. In this study, we conducted a pot experiment in which Glycine max L. (soybean) was cultivated in two cadmium (Cd)-contaminated soils (low, 3.14 mg kg⁻¹; high, 10.80 mg kg⁻¹) to investigate the effects of biochar on the bioremediation of Cd, N₂O emissions and the rhizosphere microbial community structure. The bioaccumulation of Cd in the plant shoots and roots increased with all biochar addition rates (0%, 1%, 5% and 10%); unexpectedly, the translocation capacity of Cd to the edible parts of the plant significantly decreased to 0.58 mg kg⁻¹, which was close to the edible threshold (0.4 mg kg⁻¹). The abundance and activities of functional marker genes of microbial nitrification (amoA) and denitrification (nirK, nirS and nosZ) were quantified with quantitative PCR, and we found that biochar addition reduced the precursor production of rhizoshpere N₂O by inhibiting the transcription of the nirK gene. In addition, the nitrogenase activity during anthesis (S) was significantly (P < 0.05) increased with 1% (v/v) biochar addition. Noticeably, biochar addition only changed the microbial community structure in the very first stage before eventually stabilize. This study highlighted that biochar has the potential ability to maintain the quality of agricultural crops, remediate Cd-contaminated soils and may help reduce N₂O emissions without disturbing the microbial community.

Mejillones Bay is a coastal ecosystem situated in an oxygen-deficient upwelling area impacted by mining activities in the coastal desert region of northern Chile, where conspicuous microbial life develops in the sediments. Herein, heavy metal (loid)s (HMs) such as Cu, Pb, As, Zn, Al, Fe, Cd, Mo, Ni and V as well as benthic microbial communities were studied using spectrometry and iTag-16 S rRNA sequencing. Samples were taken from two contrasting sedimentary localities in the Bay named Punta Rieles (PR) and Punta Chacaya (PC) within 10–50 m water-depth gradient. PR sediments were organic matter rich (21.1% of TOM at 50 m) and overlaid with low-oxygen waters (<0.06 ml O2/L bottom layer) compared with PC. In general, HMs like Al, Ni, Cd, As and Pb tended to increase in concentration with depth in PR, while the opposite pattern was observed in PC. In addition, PR presented a higher number of unique families (72) compared to PC (35). Among the top ten microbial families, Desulfobulbaceae (4.6% vs. 3.2%), Flavobacteriaceae (2.8% vs. 2.3%) and Anaerolineaceae (3.3% vs. 2.3%) dominated in PR, meanwhile Actinomarinales_Unclassified (8.1% vs. 4.2%) and Sandaracinaceae (4.4% vs. 2.0%) were more abundant in PC. Multivariate analyses confirmed that water depth-related variation was a good proxy for oxygen conditions and metal concentrations, explaining the structure of benthic microbial assemblages. Cd, Ni, As and Pb showed uniformly positive associations with communities that represented the keystone taxa in the co-occurrence network, including Anaerolineaceae, Thiotrichaceae, Desulfobulbaceae, Desulfarculaceae and Bacteroidales_unclassified communities. Collectively, these findings provide new insights for establishing the ecological interconnections of benthic microorganisms in response to metal contamination in a coastal upwelling environment.

Because most relevant studies have used small sample sizes, to date, representative atmospheric monitoring of persistent organic pollutants (POPs) on a regional scale has been very limited, which makes it difficult to precisely identify “hotspots” and possible pollution sources. In this study, an ultrahigh resolution monitoring technique was used to measure the atmospheric spatial variations in POP concentrations on a regional scale, throughout Campania, Italy. The occurrence of specific POPs—including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and phthalate esters (PAEs)—were investigated using polyurethane foam-based passive air samplers (PUF-PAS), which were deployed at 129 sites across the Campania Territory between April and July 2016. The results show that the highest POP levels occurred in the Naples metropolitan area (NMA), although there were other problematic spots throughout the Territory. More specifically, hotspot areas in the NMA that depict serious POP pollution were found in the Bagnoli brownfield site, Sarno River Basin, and parts of the northeastern NMA sector. The atmospheric POP contamination in Campania is jointly controlled by the contributions of local emissions and long-range atmospheric transport. Diffusion model was employed to identify the potential sources of various POPs. The simulation showed that all the POP sources are located in the NMA and are closely related to industrial sites. This study demonstrates the advantage of using large sample sizes to identify POP source locations and achieve geospatial visualization of POP concentration and risk assessment levels.

Groundwater in several parts of the world, particularly in developing countries, has been contaminated with Arsenic (As). In search of low-cost As removal methods, the biological oxidation of As(III) and Fe(II) followed by co-precipitation requires detailed investigation for the practical implementation of this technology. The present study investigated the biological oxidation of As(III) and Fe(II) through a combination of laboratory experiments and reactive transport modeling. Batch experiments were conducted to evaluate the As(III) oxidation by Fe-oxidizing bacteria, mainly Leptothrix spp. A fixed-bed down-flow biological column containing inexpensive and readily available coconut husk support media was used to evaluate the combined removal of As(III) and Fe(II) from synthetic groundwater. Oxidation and co-precipitation processes effectively reduced the concentration of As(III) from 500 μg/L to < 10 μg/L with a hydraulic retention time of 120 min. A one-dimensional reactive transport model was developed based on the microbially mediated biochemical reactions of As(III) and Fe(II). The model successfully reproduced the observed As(III) and Fe(II) removal trends in the column experiments. The modeling results showed that the top 20 cm aerobic layer of the column played a primary role in the microbial oxidation of Fe(II) and As(III). The model calibration identified the hydraulic residence time as the most significant process parameter for the removal of Fe and As in the column. The developed model can effectively predict As concentrations in the effluent and provide design guidelines for the biological treatment of As. The model would also be useful for understanding the biogeochemical behavior of Fe and As under aerobic conditions.