Cadmium (Cd) pollution in alkaline soil in some areas of northern China has seriously threatened wheat production and human health. However, there are still few effective amendments for alkaline soil, and the mechanism of amendments with a good immobilization effect remains unclear. In this study, soil sterilization experiments were conducted to investigate the effects of soil microorganisms on the immobilization of a novel amendment—mercapto palygorskite (MPAL) in Cd-contaminated alkaline soils. The results showed that the mercapto on the MPAL surface was not affected by autoclaving. Compared with the control, the available Cd concentration in 0.025% MPAL treatments decreased by 18.80-29.23% after 1 d of aging and stabled after 10 d of aging. Importantly, the immobilization of MPAL on Cd in sterilized soil was significantly better than that in natural soil due to the changes in Cd fractions. Compared with MPAL-treated natural soil, exchangeable Cd fraction and carbonate-bound Cd fraction in MPAL-treated sterilized soil decreased by 20.79–27.09% and 20.05–26.45%, while Fe/Mn oxide-bound Cd fraction and organic matter-bound Cd fraction increased by 17.77–22.68% and 18.85–27.32%. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis found that the potential functions of the microbial community in normal and sterilized soil were different significantly. Soil sterilization increased the soil pH and decreased the arylsulfatase activity, but did not change the soil zeta potential and available sulfur. The changes in Cd fractions in MPAL-treated sterilized soil may be related to the reduction in the bacterial community and the changes in function microbial, but not to the soil properties. In addition, MPAL application had little effects on the bacterial community, soil pH value, zeta potential, available sulfur, and arylsulfatase. These results showed that the immobilization of MPAL on Cd in alkaline soil was stable and effective, and was not affected by soil sterilization and soil microorganism reduction.

A complex relationship exists between copper stress and the accumulation and release of domoic acid (DA) in toxin-producing Pseudo-nitzschia cells. To clarify the changes and role of DA in this process, we exposed the toxin-producing P. multiseries and the non-toxin-producing P. pungens to copper stress (5 and 9 μM) for 96 h. Results showed that P. multiseries grew better than P. pungens under the two aforementioned copper concentrations. DA content in the cells of P. multiseries increased with increased copper stress, and the dissolved DA in the medium under the 9 μM copper treatment increased. DA addition at a 9 μM copper concentration reduced the copper content in P. multiseries cells and cell walls, but did not change the free copper ion content in culture medium. Adding DA to the medium reduced the malondialdehyde (MDA) content in the cells of P. multiseries under copper stress, DA addition also reduced the activities of catalase (CAT) and superoxide dismutase (SOD) at 5 μM Cu, and the activity of peroxidase (POD) at 9 μM Cu. This suggests that DA may not alleviate copper stress by improving the antioxidant defense system of algal cells, nor can it be complexed with copper ions in the medium to alleviate copper stress. Furthermore, the reactive oxygen species (ROS) scavenger N-tert-butyl-α-phenylnitrone (BPN) was used to study the DA accumulated in cells. The BPN addition significantly reduced the accumulation of DA in the cells under copper stress, suggesting that DA content in cells was closely related to ROS. Moreover, further experiments demonstrated that DA addition can improve the growth of P. multiseries under hydrogen peroxide stress. Our results indicate that DA alleviates P. multiseries oxidative damage when expose to copper stress.

Environmental exposure to pollution generated by mining and burning coal is inevitable for people living nearby. Therefore, the aim of this study was to evaluate the influence of coal dust on health conditions and genomic instability of individuals who live near coal mines and thermoelectric power plants, and to relate the results to inorganic elements and inflammatory responses. Thus, we evaluated 284 individuals from four cities in the south of Brazil around a region with coal mines and a thermoelectric power plant (one city was considered a negative control). The results of the Comet assay and Micronucleus (MN) test did not show a genotoxic or mutagenic effect related to environmental exposure to coal, but the inflammatory cytokine tumor necrosis factor-α (TNF-α) was increased in all cities around the power plant when compared to the control conditions. Higher levels of MN were associated with body mass index and cardiovascular risk, and higher levels of Damage Index (DI), TNF-α and interleukin1β (IL-1β) with number of cigarettes/day. Principal component analysis (PCA) was used to integrate DNA damage and inflammatory results with inorganic elements. This study also demonstrated the relationship between zinc and MN, copper, and interleukin10 (IL-10), and among silicon and sulfur with DI and nucleoplasmic bridge. A relationship was also observed between the reduction of inorganic elements and both aging and quality of health. The use of different methodologies and the relationship between the results obtained in these studies, including different lifestyles, can increase the understanding of the interaction between this mineral and the health status of residents of regions affected by coal pollution.

It is estimated that approximately 0.4% of the total leachate produced in a landfill is destined for treatment plants, while the rest can reach the soil and groundwater. In this context, this study aimed to perform leachate toxicity evaluations through immune system cytotoxic assessments, genotoxic (comet assay) appraisals and antioxidant system (superoxide dismutase - SOD; catalase - CAT, glutathione-S-transferase - GST; reduced glutathione - GSH and metallothionein - MT) evaluations in Eisenia andrei earthworms exposed to a Brazilian leachate for 77 days. The leachate sample contained high organic matter (COD - 10,630 mg L⁻¹) and ammoniacal nitrogen (2398 mg L⁻¹), as well as several metals, including Ca, Cr, Fe, Mg, Ni and Zn. Leachate exposure resulted in SOD activity alterations and increased CAT activity and MT levels. Decreased GST activity and GSH levels were also observed. Antioxidant system alterations due to leachate exposure led to increased malondialdehyde levels as a result of lipid peroxidation after the 77 day-exposure. An inflammatory process was also observed in exposed earthworms, evidenced by increased amoebocyte density, and DNA damage was also noted. This study demonstrates for the first time that sublethal effect assessments in leachate-exposed earthworms comprise an important tool for solid waste management.

Developing low-cost and high-performance biosorbent for water purification continues drawing more and more attention. In this study, cellulose-chitosan composite hydrogels were fabricated via a co-dissolution and regeneration process using a molten salt hydrate (a 60 wt% aqueous solution of LiBr) as a solvent. The addition of chitosan not only introduced functionality for metal adsorption but also increased the specific surface area and improved the mechanical strength of the composite hydrogel, compared to pure cellulose hydrogel. Batch adsorption experiments indicated that the composite hydrogel with 37% cellulose and 63% chitosan exhibited an adsorption capacity of 94.3 mg/g (1.49 mmol/g) toward Cu²⁺ at 23 °C, pH 5, and initial metal concentration of 1500 mg/L, which was 10 times greater than the adsorption capacity of pure cellulose hydrogel. Competitive adsorption from a mixed metals solution revealed that the cellulose-chitosan composite hydrogel exhibited selective adsorption of the metals in the order of Cu²⁺ > Zn²⁺ > Co²⁺. This study successfully demonstrated an innovative method to fabricate biosorbents from abundant and renewable natural polymers (cellulose and chitosan) for removing metal ions from water.

As emerging pollutants, microplastics (MPs) have been found globally in various freshwater and marine matrices. This study recompiled 270 endpoints of 3765 individuals from 43 publications, reporting the onset of enhanced biological performance and reduced oxidative stress biomarkers induced by MPs in aquatic organisms at environmentally relevant concentrations (≤1 mg/L, median = 0.1 mg/L). The stimulatory responses of consumption, growth, reproduction and survival ranged from 131% to 144% of the control, with a combined response of 136%. The overall inhibitory response of 9 oxidative stress biomarkers was 71% of the control, and commonly below 75%. The random-effects meta-regression indicated that the extents of MPs-induced responses were independent of habitat, MP composition, morphology, particle size and exposure duration. The results implied that the exposure to MPs at low and high concentrations might induce opposite/non-monotonic responses in aquatic biota. Correspondingly, the hormetic dose response relationships were found at various endpoints, such as reproduction, genotoxicity, immunotoxicity, neurotoxicity and behavioral alteration. Hormesis offers a novel perspective for understanding the dose response mode of aquatic organisms exposed to low and high concentrations of MPs, highlighting the necessity to incorporate the hormetic dose response model into the ecological/environmental risk assessment of MPs.

In the present study, produced water sample collected from the Indian crude oil reservoir is used to enrich the bacterial communities. The impact of these enriched bacterial communities on the biodegradation of crude oil, biofilm formation, and biocorrosion process are elucidated. A crude oil degradation study is carried out with the minimal salt medium and 94% of crude oil was utilized by enriched bacterial communities. During the crude oil degradation many enzymes including alkane hydroxylase, alcohol dehydrogenase, and lipase are playing a key role in the biodegradation processes. The role of enriched bacterial biofilm on biocorrosion reactions are monitored by weight loss studies and electrochemical analysis. Weight loss study revealed that the biotic system has vigorous corrosion attacks compared to the abiotic system. Both AC-Impedance and Tafel analysis confirmed that the nature of the corrosion reaction take place in the biotic system. Very less charge transfer resistance and higher corrosion current are observed in the biotic system than in the abiotic system. Scanning electron microscope confirms that the dense biofilm formation favoured the pitting type of corrosion. X-ray diffraction analysis confirms that the metal oxides formed in the corrosion systems (biotic). From the metagenomic analysis of the V3–V4 region revealed that presence of diverse bacterial communities in the biofilm, and most of them are uncultured/unknown. Among the known genus, Bacillus, Halomonas, etc are dominant in the enriched bacterial biofilm sample. From this study, we conclude that the uncultured bacterial strains are found to be playing a key role in the pitting type of corrosion and they can utilize crude oil hydrocarbons, which make them succeeded in extreme oil reservoir environments.

Microplastics (MPs) are abundant in marine environments, drawing global attention from scientists and rendering it significant to review the research progress and predict future trends of this field. To achieve that, we collected 1898 publications on marine MPs from Web of Science and performed a bibliometric analysis by CiteSpace and VOSviewer. Additionally, we utilized an unrestricted retrieval of literature from ScienceDirect to supplement our major findings. Trends in publication numbers show the growth in study from the initial stage (2012 and before), when microplastic (MP) occurrence, abundance, and distribution were primarily investigated. Throughout the ascent stage (between 2013–2016), when diverse sampling and analytical methods were applied to capture and identify MPs from the ocean, baseline data have been gleaned on physiochemical properties of MPs. The research focus then shifted to the bioaccumulation and ecotoxicological effects of MPs on marine biota, further highlighting their potential deleterious impacts on human health via dietary exposure, and this period was defined as the exploration stage (2017 and onwards). Nevertheless, key challenges including the lack of standard procedures for MP sampling, technical limitations in MP detecting and identification, and controversy about the underlying effects on the marine ecosystems and humans have also been arisen in the last decade. The present study elucidates how we gradually recognize MP pollution in marine environments and what challenges we face, suggesting future avenues for MP research.

Air quality has been significantly improved in China in recent years; however, our knowledge of the long-term changes in health risks from exposure to air pollutants remain less understood. Here we investigated the temporal variations and spatial distributions of six criteria pollutants (SO₂, NO₂, O₃, CO, PM₂.₅ and PM₁₀) in Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD) during 2015–2019. SO₂ showed 36−60% reductions in three regions, comparatively, NO₂ decreased by 3–17% in BTH and YRD and had a 5% increase in PRD. PM₂.₅ and PM₁₀ showed the largest reductions in BTH (30−33%) and the lowest in PRD (7−13%), while O₃ increased by 9% during 2015–2019 particularly in BTH and YRD. Assuming that only air pollutants above given thresholds exert excess risk (ERₜₒₜₐₗ) of mortality, we found that the different variations of pollutants have caused ERₜₒₜₐₗ in BTH decreasing significantly from 4.8% in 2015 to 2.0% in 2019, while from 1.9% to 1.0% in YRD, and a small change in PRD. These results indicate substantially decreased health risks of mortality from exposure to air pollutants as a response to improved air quality. Overall, PM₂.₅ dominated ERₜₒₜₐₗ accounting for 42−53% in BTH and 58−64% in YRD with steadily increased contributions, yet ERₜₒₜₐₗ presented strong seasonal dependence on air pollutants with largely increased contribution of O₃ in summer. The ERₜₒₜₐₗ caused by SO₂ was decreased substantially and became negligible except in winter in BTH, while NO₂ only played a role in winter. We also found that ERPM₂.₅ was compositional dependent with organics being the major contributor at low ERPM₂.₅ while nitrate was more important at high ERPM₂.₅. Our results highlight that evaluation of public health risks of air pollution needs to consider chemical differences of PM in different regions in addition to dominant air pollutants in different seasons.

Hybrid artificial intelligence (AI) models are developed for sediment lead (Pb) prediction in two Bays (i.e., Bramble (BB) and Deception (DB)) stations, Australia. A feature selection (FS) algorithm called extreme gradient boosting (XGBoost) is proposed to abstract the correlated input parameters for the Pb prediction and validated against principal component of analysis (PCA), recursive feature elimination (RFE), and the genetic algorithm (GA). XGBoost model is applied using a grid search strategy (Grid-XGBoost) for predicting Pb and validated against the commonly used AI models, artificial neural network (ANN) and support vector machine (SVM). The input parameter selection approaches redimensioned the 21 parameters into 9–5 parameters without losing their learned information over the models’ training phase. At the BB station, the mean absolute percentage error (MAPE) values (0.06, 0.32, 0.34, and 0.33) were achieved for the XGBoost–SVM, XGBoost–ANN, XGBoost–Grid-XGBoost, and Grid-XGBoost models, respectively. At the DB station, the lowest MAPE values, 0.25 and 0.24, were attained for the XGBoost–Grid-XGBoost and Grid-XGBoost models, respectively. Overall, the proposed hybrid AI models provided a reliable and robust computer aid technology for sediment Pb prediction that contribute to the best knowledge of environmental pollution monitoring and assessment.