The honeybee has economic importance both for the commercial value of bee products and for its role in the pollination of agricultural crops. Despite the fact that the fungicides are widely used in agriculture, studies comparing the effects of this group of pesticides on bees are still scarce. There are many gaps preventing the understanding of bees’ responses to exposure to fungicides, including the influence of the age of the exposed workers. However, this study aimed to compare the effects of residual concentrations of pyraclostrobin on young and old bees of Africanized Apis mellifera. The parameters analyzed were the survival rates, as well as the histopathological and histochemical changes in midgut of orally exposed workers to different sublethal concentrations of this strobilurin fungicide: 0.125 ng a.i./μL (C1), 0.025 ng a.i./μL (C2) e 0.005 ng a.i./μL (C3). The results showed a significant decrease in the longevity only for old bees exposed to the three concentrations of pyraclostrobin. After the five-day exposure period, the fungicide induced sublethal effects in the midgut only from the old bees. These effects were the increase both in cytoplasmic vacuolization of digestive cells and morphological changes in the nests of regenerative cells, which reflected in the higher lesion index of organ for groups C1 and C2. Additionally, there was a reduction in total protein staining in the intestinal epithelium in C1 and C2. At the same exposure period, the midgut of young bees presented only a reduction in the staining of neutral polysaccharides in the group C1. Concluding, old workers are more sensitive to the fungicide than young workers. This study showed different responses according to worker age, which can affect the maintenance of colony health. Future studies should take into account the age of the workers to better understand the effects of fungicides on bees.

Microbial degradation is an important pathway for the attenuation of polybrominated diphenyl ethers (PBDEs) in natural soils. In this study, the compound-specific stable isotope analysis (CSIA) was applied to characterize microbial degradation of BDE-153, one of the prevailing and toxic PBDE congeners, in natural wetland soils. During the 45-day incubation, the residual percentages of BDE-153 decreased to 67.9% and 73.6% in non-sterilized soils spiked with 1.0 and 5.0 μg/g, respectively, which were both much lower than those in sterilized soils (96.0% and 97.2%). This result indicated that microbial degradation could accelerate BDE-153 elimination in wetland soils. Meanwhile, the significant carbon isotope fractionation was observed in non-sterilized soils, with δ¹³C of BDE-153 shifting from −29.4‰ to −26.7‰ for 1.0 μg/g and to −27.2‰ for 5.0 μg/g, respectively, whilst not in sterilized soils. This phenomenon indicated microbial degradation could induce stable carbon isotope fractionation of BDE-153. The carbon isotope enrichment factor (εc) for BDE-153 microbial degradation was first determined as −7.58‰, which could be used to assess the microbial degradation and bioavailability of BDE-153 in wetland soils. Based on δ¹³C and εc, the new methods were developed to dynamically and quantitatively estimate degradation degree and bioavailability of BDE-153 during degradation process, respectively, which could exclude interference of physical processes. This work revealed that CSIA was a promising method to investigate in situ microbial degradation of PBDEs in field studies.

The stability of mercury (Hg) contamination in soil environments can change over time. This has implications for agricultural sites under long-term management after in situ treatment involving soil amendments. In this study, rice husk biochar (RHB) and sulfur modified rice husk biochar (SRHB) were synthesized and applied (dosage = 5% dry wt.) to a Hg polluted agricultural soil collected from Guizhou province, Southern China (soil total Hg content = 28.3 mg/kg; C = 2%; and, S = 0.1%). The long-term stabilization effectiveness of the soil treatments was evaluated by a combined approach involving: (i) accelerated aging for 104 simulated years; (ii) soil extraction as a proxy for plant uptake; and, (iii) sequential extraction to identify Hg fractions. The SRHB amendment raised the soil’s total S content by approximately an order of magnitude (to 0.9%), which remained at a generally constant level throughout the simulation. The initial pH levels for the untreated and treated soils were alkaline and remained between 7.0 and 7.5 for the first 50 years of simulated aging, before decreasing as the simulation time increased further. The pH of the SRHB treated soils did not drop below that of untreated soils during the simulation. Soil extraction tests with 0.1 M HCl solution indicated that RHB and SRHB treatments could effectively immobilize the Hg in soil for at least 50 and 75 simulated years, respectively. At simulated year 50, the amount of Hg extracted from RHB and SRHB treated soils was <200 ng/L and <100 ng/L, respectively. Thus, showing SRHB to be a particularly promising remedial option. The soil Hg was mostly associated with the stable sequential extraction fractions (F3-5). By the end of the simulation, the F5 fraction for SRHB and RHB treated soils reduced by 44.6%, and 42.0%, respectively, whereas the F4 fraction increased by >400% in both cases. In summary, SRHB may provide long-lasting Hg stabilization at contaminated sites. Therefore, further research toward the development of this stabilization technology is warranted.

Household air pollution is the dominant contributor to population air pollutant exposure, but it is often of less concern compared with ambient air pollution. One of the major knowledge gaps in this field are detailed quantitative source contributions of indoor pollutants, especially for gaseous compounds. In this study, temporally, spatially, and vertically resolved monitoring for typical indoor gases including CO₂, CO, formaldehyde, methane, and the total volatile organic compounds (VOCs) was conducted to address pollution dynamics and major sources in an urban apartment. The indoor concentrations were significantly higher than the simultaneously measured outdoor concentrations. A new statistic approach was proposed to quantitatively estimate contributions of different sources. It was estimated that outdoor CO₂ contributed largely to the indoor CO₂, while main indoor sources were human metabolism and cooking. Outdoor infiltration and cooking contributed almost equally to the indoor CO. The contribution of outdoor infiltration to methane was much higher than that to formaldehyde. Cooking contributed to 24%, 19%, and 25% of indoor formaldehyde, methane, and VOCs, whereas the other unresolved indoor sources contributed 61%, 19%, and 35% of these pollutants, respectively. Vertical measurements showed that the uplifting of hot air masses led to relatively high concentrations of the pollutants in the upper layer of the kitchen and in the other rooms to a lesser extent.

The solid waste of ductile iron industry, which contains at least 88.0% magnesium oxide, is one of the toxic materials, leading to land contamination. On the other hand, the removal of reactive dyes from wastewaters is difficult required effective adsorbent like nano-porous MgO. The novelty of present investigation is based on nano-porous magnesium oxide production by precipitation from the solid waste to treat the wastewaters contaminated by reactive dye which is abundantly used in the textile industry. In order to improve the adsorptive properties of extracted MgO powder, the combinations of surfactants, containing cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polyoxyethylene octyl phenyl ether (TX100) were applied based on the mixture design algorithm in the precipitation. The effects of processing factors such as surfactant composition, powder calcination temperature, surfactant dose and pH were evaluated on the removal efficiency. The results revolved that the combination of SDS and TX100, 1:1, plays an effective role in the production of particles with the appropriate average pore size, 16 nm. The adsorbent prepared in the optimum condition indicated a significant affinity for the removal of reactive dye which shows relatively pH-independent efficiency in the range of 3–9. The applied producer for fabrication of adsorbent eventually overcomes the pH-dependent problem for the toxic dye uptake, leading to produce the adsorbent with maximal adsorption capacity of 1000 mg g−1.

Diclofop-methyl (DM) is one of the most widely used herbicides in agriculture production and has been frequently detected in both freshwater and environments, even agricultural products. However, the potential toxic effects of DM on organisms and the underlying mechanisms are still poorly understood. In this study, we utilized zebrafish to evaluate the toxicity of DM during the cardiovascular developmental process. Exposure of zebrafish embryos to 0.75, 1.0 and 1.25 mg/L DM induced cardiac defects, such as pericardial edema, slow heart rate and long SV-BA distance but the vascular development in zebrafish larvae was not influenced by DM treatment. The expression of cardiac-related genes were disordered and DM exposure initiated disordering cardiogenesis from the period of precardiac mesoderm formation. Moreover, the apoptosis and proliferation of cardiomyocytes were not influenced but the levels of oxidative stress were upregulated by DM exposure. Fullerenes and astaxanthin was able to rescue cardiac defects caused by DM via downregulating oxidative stress. Wnt signaling was downregulated after DM treatment and activation of Wnt signaling could rescue cardiac defects. Therefore, our results suggest that DM has the potential to induce cardiac developmental toxicity through upregulation of Wnt-Mediated (reactive oxygen species) ROS generation in zebrafish larvae.

While considerable efforts have been made to address the relationship between urbanization and environmental issues, few of them focus on household emissions. Thus, this work aimed at evaluating the effect of urbanization on household wastewater emissions, and made a distinction between the efficient- and the inefficient-emissions. We compiled a China’s provincial dataset over the period 2005–2017, and estimates indicated that a 1% rise in the urbanization was correlated with a 0.581 increase of efficient emissions, while inefficient emissions decreased by 7.606. As of 2017, the sample period end year, the inefficient emissions accounted for 10.5% of the total emissions of China as a whole, which was relatively large and could not be overlooked. Meanwhile, a back-of-the-envelope estimate revealed that urbanization had a negative impact on China’s total emissions, with a marginal effect ranging from −0.226 to −1.354 over the sample period. The above findings, however, did not imply that urbanization would spontaneously reduce the inefficient- and total-emissions. Thus, the government in the process of urbanization should strengthen environmental education, municipal facilities, and others.

Whereas non-extractable residue (NER) formation is recognized as an important process affecting the ecological risk of organic contaminants in soils, it is commonly neglected in regional-scale multi-media models assessing chemical environmental fate and risk. We used a combined field and modeling study to elucidate the relative importance of NER formation to the reduction in available organic contaminants compared with fate processes commonly considered in risk assessment models (volatilization, leaching, and biodegradation). Specifically, four polycyclic aromatic hydrocarbons (PAHs), i.e., phenanthrene (Phe), pyrene (Pyr), benzo[a]pyrene (BaP), and benzo[ghi]perylene (BghiP), were spiked and measured in a one-year field pot experiment at four sites with diverse environmental conditions on the eastern Tibetan Plateau. The rate of NER formation was derived as the difference between the overall rate of decline in total-extractable PAH concentrations, obtained by fitting a biphasic first-order model to the measured concentrations, and the sum of the calculated rates of volatilization, leaching, and biodegradation. Our work shows that the total-extractable PAH concentration undergoes a rapid decline and a slow decline, with shorter overall half-lives (especially for BaP and BghiP) than those observed in earlier studies. Generally, NER formation was assessed to be the dominant contributor (64 ± 33%) to the overall decline of PAHs, followed by biodegradation (35 ± 32%); volatilization and leaching were the smallest contributors. In particular, heavier PAHs (i.e. BaP and BghiP) tend to have shorter half-lives in the rapid and the overall decline phase, indicating that the erroneous estimation of environmental fate and risks might be more pronounced for organic contaminants with a large molecular size. The trend of overall decline rates of PAHs displayed a combined effect of NER formation and biodegradation. This work indicates the need to consider NER formation as a process in multi-media models of chemical fate and risk.

In this study, the distribution profiles, emission characteristics, and health risks associated with 43 volatile and semi-volatile organic compounds, including 15 phenols, 18 polycyclic aromatic hydrocarbons (PAHs), 6 BTEX, and 4 other compounds, were determined in the wastewater treatment plant (WWTP) of a coking factory (plant C) and the succeeding final WWTP (central WWTP). Total phenols with a concentration of 361,000 μg L⁻¹ were the predominant compounds in the influent wastewater of plant C, whereas PAHs were the major compounds in the final effluents of both coking WWTPs (84.4 μg L⁻¹ and 30.7 μg L⁻¹, respectively). The biological treatment process in plant C removed the majority of volatile organic pollutants (94.1%–99.9%). A mass balance analysis for plant C showed that biodegradation was the main removal pathway for all the target compounds (56.6%–99.9%) except BTEX, chlorinated phenols, and high molecular weight (MW) PAHs. Chlorinated phenols and high MW PAHs were mainly removed via sorption to activated sludge (51.8%–73.2% and 60.2%–75.9%, respectively). Air stripping and volatilization were the dominant mechanisms for removing the BTEX compounds (59.8%–73.8%). The total emission rates of the detected volatile pollutants from plant C and the central WWTP were 1,640 g d⁻¹ and 784 g d⁻¹, respectively. Benzene from the equalization basins of plant C and the central WWTP corresponded to the highest inhalation carcinogenic risks (1.4 × 10⁻³ and 3.2 × 10⁻⁴, respectively), which exceeded the acceptable level for human health (1 × 10⁻⁶) recommended by the United States Environmental Protection Agency. The results showed that BaP exhibited the highest inhalation non-cancer risk, with a hazard index ratio of 70 and 30 for plant C and the central WWTP, respectively. Moreover, the excess sludge generated during wastewater treatment should also be carefully handled because it adsorbed abundant PAHs and chlorinated phenols at coking plant C (58,000 μg g⁻¹ and 3,500 μg g⁻¹) and the central WWTP (622 μg g⁻¹ and 54 μg g⁻¹).

PM₂.₅ exposure is an emerging environmental concern and severe health insult closely related to psychological conditions such as anxiety and depression in adolescence. Adolescence is a critical period for neural system development characterized by continuous brain maturation, especially in the prefrontal cortex. The etiology of these adolescent conditions may derive from fetal origin, probably attributed to the adverse effects induced by intrauterine environmental exposure. Anxiety- and depression-like behavior can be induced by gestational exposure to PM₂.₅ in mice offspring which act as a useful model system. Recent studies show that B-vitamin may alleviate PM₂.₅-induced hippocampal neuroinflammation- and function-related spatial memory impairment in adolescent mice offspring. However, cortical damage and related neurobehavioral defects induced by gestational PM₂.₅ exposure, as well as the potential reversibility by interventions in mice offspring require to be elucidated. Here, we aimed to investigate whether B-vitamin would protect mice offspring from the adverse effects derived from gestational exposure to urban PM₂.₅ on cortical areas to which anxiety and depression are closely related. Pregnant mice were divided into three groups: control group (treated with PBS alone), model group (treated with both PM₂.₅ and PBS), and intervention group (treated with both PM₂.₅ and B-vitamin), respectively. The mice offspring were then applied to comprehensive neurobehavioral, ultrastructural, biochemical, and molecular biological analyses. Interestingly, we observed that gestational PM₂.₅ exposure led to neurobehavioral defects including anxiety- and depression-like behavior. In addition, neuroinflammation, oxidative damage, increased apoptosis, and caspase-1-mediated inflammasome activation in the prefrontal cortex were observed. Notably, both behavioral and molecular changes could be significantly alleviated by B-vitamin treatment. In summary, our results suggest that the anxiety- and depression-like behavior induced by gestational PM₂.₅ exposure in mice offspring can be ameliorated by B-vitamin supplementation, probably through the suppression of apoptosis, oxidative damage, neuroinflammation, and caspase-1-mediated inflammasome activation.