We investigated how sulfur (S) application prior to wheat cultivation under wheat-rice rotation influences the uptake of cadmium (Cd) in rice grown in low- and high-Cd soils. A pot experiment was conducted with four S levels (0, 30, 60, 120 mg S kg⁻¹) and two Cd rates (low and high, 0.35 and 10.35 mg Cd kg⁻¹) supplied to wheat. Part of the wheat straw was returned to the soil before planting rice, which was cultivated for 132 days. To explore the key mechanisms by which S application controlled Cd accumulation in brown rice, (1) soil pore water at the key growth stages was sampled, and dissolved Cd and S species concentrations were determined; (2) rice plant tissues (including iron plaque on the root surface) were sampled at maturity for Cd and S analysis. With increasing S level, Cd accumulation in brown rice peaked at 60 mg S kg⁻¹, irrespective of soil Cd levels. For high-Cd soils, concentrations of Cd in brown rice increased by 57%, 228%, and 100% at 30, 60, and 120 mg S kg⁻¹, respectively, compared with no S treatment. The increase in brown rice Cd by low S levels (0–60 mg kg⁻¹) could be attributed to (1) the S-induced increase in soil pore water sulfate increasing the Cd influx into rice roots and (2) the S-induced increase in leaf S promoting Cd translocation into brown rice. However, brown rice Cd decreased at 120 mg S kg⁻¹ due to (1) low Cd solubility at 120 mg S kg⁻¹ and (2) root and leaf S uptake, which inhibited Cd uptake. Sulfur application to wheat crop increased the risk of Cd accumulation in brown rice. Thus, applying S-containing fertilizers to Cd-contaminated paddy soils is not recommended.

Nitric oxide (NO) and hydrogen sulfide (H₂S) since their discovery have proven to be game changing molecules in alleviating abiotic stress. They individually play role in plant stress management while the pathways of stress regulation through their crosstalk remain elusive. The current study focuses on investigating the interplay of NO and H₂S signalling in the amelioration of arsenate As(V) toxicity in rice seedlings and managing its growth, photosynthesis, sucrose and proline metabolism. Results show that As(V) exposure declined fresh weight (biomass) due to induced cell death in root tips. Moreover, a diminished RuBisCO activity, decline in starch content with high proline dehydrogenase activity and increased total soluble sugars content was observed which further intensified in the presence of Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME, an inhibitor of nitric oxide synthase-like activity), and DL-propargylglycine (PAG, an inhibitor of cysteine desulfhydrase activity). These results correlate with lower endogenous level of NO and H₂S. Addition of L-NAME increased As(V) toxicity. Interestingly, addition of SNP reverses effect of L-NAME suggesting that endogenous NO has a role in mitigating As(V) toxicity. Similarly, exogenous H₂S also significantly alleviated As(V) stress, while PAG further stimulated As(V) toxicity. Furthermore, application of H₂S in the presence of L – NAME and NO in the presence of PAG could still mitigate As(V) toxicity, suggesting that endogenous NO and H₂S could independently mitigate As(V) stress.

Transition metals (TMs) (e.g. copper (Cu) and iron (Fe)) and certain organic compounds are known active constituents causing oxidative potential (OP) by inhaled ambient fine particulate matter (PM₂.₅) in lung fluid. Humic-like substances (HULIS), isolated from atmospheric PM₂.₅, are largely metal-free and contain mixtures of organics that are capable of complexing TMs. TMs and HULIS co-exist in the water-extractable part of PM₂.₅. In this work, we used a solid phase extraction procedure to isolate the water-soluble TMs in the hydrophilic fraction (HPI) and HULIS in the hydrophobic fraction (HPO) and carried out this isolation procedure to a set of 32 real-world PM₂.₅ samples collected in Beijing and Hong Kong, China. We quantified two OP endpoints, namely hydroxyl radical formation (denoted as OP•OH) and ascorbic acid depletion (denoted as OPAA), by the two fractions separately and combined, as well as by the bulk water-soluble aerosols. OP•OH and OPAA were well-correlated in both separate fractions and their combined mixtures or bulk water-soluble aerosols. OP by HPI far exceeded that by HPO. On a per unit PM₂.₅ mass basis, the Hong Kong samples on average had a higher OPAA and OP•OH than the Beijing samples due to more water-soluble Cu. For HPI, Cu was a dominant OP•OH and OPAA contributor (>80%), although water-soluble Fe was present at a concentration approximately one order of magnitude higher. Suppression effects on OP•OH were observed through comparing the OP of the bulk water-soluble aerosol with that of HPI. Our work reveals the importance of monitoring PM₂.₅ chemical compositions (especially water-soluble redox active metals). Furthermore, we demonstrate the need to consider metal-organic interactions when evaluating the aggregate OP by PM₂.₅ from individual components or apportioning OP by PM₂.₅ to specific chemical components.

Tributyltin (TBT) is a widely used organotin compound around the world and was frequently detected in surface waters, which would pose risk to aquatic organisms. However, the mechanisms of TBT-induced toxicity is not full clear. The present study investigated the effects of the tributyltin (TBT) on the blood parameters, immune responses and thyroid hormone system in zebrafish. Fish were exposed to sublethal concentrations of TBT (10 ng/L, 100 ng/L and 300 ng/L) for 6 weeks. The effects of long-term exposure to TBT on blood parameters (NH3, ammonia; GLU, glucose; TP, total proteins; CK, creatine kinase; ALT, alanine aminotransferase; AST, aspartate aminotransferase), immune responses (Lys, lysozyme; IgM, immunoglobulin M) and some indexes related thyroid hormone system (T3, 3,5,3′-triiodothyronine; T4, thyroxine) were measured in zebrafish, as well as the expression of genes related to immune responses and thyroid hormone system. Based on the results, the physiological-biochemical responses was significantly enhanced with an increase in TBT concentration, reflected by the abnormal blood indices, dysregulation of endocrine system and immunotoxicity in zebrafish under TBT stress. The present study greatly extends our understanding of adverse effects of TBT on aquatic organisms.

The current review reports the importance and significance of cattle solid waste in vermicomposting technology concerning biowaste pollution in the environment. Needy increasing population evokes livestock production resulting in the massive generation of livestock wastes, especially cattle dung. Improper disposal and handling of biowastes originating from agriculture, industries, forests, rural and urban areas lead to nutrient loss, environmental pollution and health risks. Among the organic waste disposal methods available, vermicomposting is regarded as an environmentally friendly technology for bioconversion of agricultural, industrial, rural and urban generated organic solid wastes which are serving as reservoirs of environmental pollution. In vermicomposting of organic wastes, cattle dung plays a central role in mineralization, nutrient recovery, earthworm and microbial activity leading to vermifertilizer production. Even though the vermicomposting studies use cattle dung invariably as an amendment material, its importance has not been reviewed to highlight its central role. Hence, the present review mainly emphasizes the key role played by cattle dung in vermicomposting. Vermiconversion of cattle dung alone and in combination with other biowaste materials of environmental concern, mechanisms involved and benefits of vermicompost in sustainable agriculture are the major objectives addressed in the present review. The analysis reveals that cattle dung is indispensable amendment material for vermicomposting technology to ensure agricultural and environmental sustainability by reducing pollution risks associated with biowastes on one hand, and nutrient-rich benign vermifertilizer production on the other hand.

Detailed, high resolution time-series observations were performed to investigate sources, diel cycling, natural attenuation, and loadings of dissolved trace metals/metalloids in a subtropical headwater stream draining intensive horticulture in Australia. A transect of ∼3 km away from the source (farms) showed >75% reduction in concentration and loads of most trace elements. Mercury and arsenic had elevated loads downstream relative to other elements. Hourly time-series sampling revealed elevated creek discharge at night, accompanied by elevated nickel, selenium, copper, and mercury loads. Inputs from groundwater or treated sewage used for irrigation within the catchment are likely sources. Groundwater bore and treated sewage samples were highly contaminated with either zinc, copper, or mercury. Comparisons of daily and hourly samples indicated common sampling strategies can underestimate horticultural contaminant loadings. Load estimates for mercury and copper derived from hourly samples were 1.6- to 7- fold greater than loads from daily sample data collected over 79 days with varying rainfall. These high contaminant concentrations and loads are of concern to food products receiving irrigation and protected waterbodies downstream.

There has been a significant increase in the microplastic (MP) polluting the ocean in recent time which is regarded as toxic for living organisms. In this study, Fluorescent red polyethylene microspheres (FRPE) were administered intramuscularly to Litopenaeus vannamei juveniles at the concentration of 0.1, 0.2, 0.5 and 1.0 μg (g shrimp)⁻¹, and the survival rate was recorded. Analysis of the hepatopancreas for antioxidant enzyme activity and gene expression were done after seven days. Further tissue morphology and accumulation of FRPE was analysed. The results showed that FRPE at 0.5 and 1.0 μg (g shrimp)⁻¹ reduce the survival rate of L. vannamei. FRPE at 0.5 and 1.0 μg (g shrimp)⁻¹ reduced superoxide dismutase (SOD) activity; FRPE at different concentrations reduced catalase (CAT) activity; FRPE at 0.2, 0.5 and 1.0 μg (g shrimp)⁻¹ increased the lipid peroxide thiobarbituric acid (TBARS) content. FRPE at 0.1, 0.2, and 0.5 μg (g shrimp)⁻¹ significantly affect the performance of SOD and CAT genes; FRPE at 0.2 and 0.5 μg (g shrimp)⁻¹ significantly improves GPx gene performance; FRPE at 1.0 μg (g shrimp)⁻¹ significantly reduced the expression of GPx genes. Analysis of tissue morphology shows that FRPE cause muscle, midgut gland, and hepatopancreas, and gill damage at different concentrations. In the results of accumulation of microplastic, FRPE accumulated in gill tissue at 0.2 and 0.5 μg (g shrimp)⁻¹; FRPE accumulated in gill, muscle and hepatopancreas tissue at 1.0 μg (g shrimp)⁻¹. Based on the above results, FRPE at 0.5 and 1.0 μg (g shrimp)⁻¹ can regulate the antioxidant enzymes of L. vannamei, increase lipid peroxide content, cause tissue damage by accumulating in the tissues. The rate of survival decreased in L. vannamei, and the impact of FRPE at 1.0 μg (g shrimp)⁻¹ was significant.

Arsenic (As) is a toxic metalloid and its widespread contamination in agricultural soils along with soil salinization has become a serious concern for human health and food security. In the present study, the effect of cotton shell biochar (CSBC) in decreasing As-induced phytotoxicity and human health risks in quinoa (Chenopodium quinoa Willd.) grown on As-spiked saline and non-saline soils was evaluated. Quinoa plants were grown on As contaminated (0, 15 and 30 mg kg⁻¹) saline and non-saline soils amended with 0, 1 and 2% CSBC. Results showed that plant growth, grain yield, stomatal conductance and chlorophyll contents of quinoa showed more decline on As contaminated saline soil than non-saline soil. The application of 2% CSBC particularly enhanced plant growth, leaf relative water contents, stomatal conductance, pigment contents and limited the uptake of As and Na as compared to soil without CSBC. Salinity in combination with As trigged the production of H₂O₂ and caused lipid peroxidation of cell membranes. Biochar ameliorated the oxidative stress by increasing the activities of antioxidant enzymes (SOD, POD, CAT). Carcinogenic and non-carcinogenic human health risks were greatly decreased in the presence of biochar. Application of 2% CSBC showed promising results in reducing human health risks and As toxicity in quinoa grown on As contaminated non-saline and saline soils. Further research is needed to evaluate the role of biochar in minimizing As accumulation in other crops on normal as well as salt affected soils under field conditions.

As the ubiquitous active components in aquatic environments, low molecular weight organic acids (LMWOAs) have a large influence on the environmental behaviors of contaminants. This research was focused on the effect of different LMWOAs including 11 aliphatic acids and 7 aromatic acids on the photodegradation kinetics of tetracycline (TC), and the development of quantitative structure-activity relationship (QSAR) model. Results showed that TC photodegradation in the presence of LMWOAs fitted pseudo-first-order photolysis kinetics, and the observed photolysis rate constant (kobs) varied from 0.077 to 0.331 h⁻¹. The QSAR model was developed by partial-least-squares (PLS) with using a sequential approach with 25 theoretical molecular descriptors. Four descriptors including ELUMO-EHOMO, ELUMO, CCR and Qmax were found to mechanistically and statistically affect kobs.The high cross validated regression coefficient (Qcum2, 0.898) and high correlation coefficient (R², 0.908) indicated significantly goodness-of-fit and high robustness of the model. The predicted and observed values with high agreement in the defined applicability domain featured accuracy and feasibility of model. This work provided a robust predictive method for estimating the TC photodegradation in the presence of different structures of LMWOAs.

We assessed the contribution of transboundary air pollutants (TAPs) transported from China to Tokyo using the Pb₍₀.₅<Dₚ < ₁₎/Cu₍₂.₅<Dₚ < ₁₀₎ index. We conducted intensive observations over four seasons during 2014–2015 and analyzed ionic components and thirteen elements in size-segregated aerosols collected at the top of a 30-m-high tower in a hilly forested area of the Field Museum Tamakyuryo (FM Tama), in a western suburb of Tokyo. In order to evaluate if the Pb₍₀.₅<Dₚ < ₁₎/Cu₍₂.₅<Dₚ < ₁₀₎ ratio can be applied in Tokyo as the megacity, the annual average concentration of Pb at Cape Hedo, Kumamoto city, on the west side of Japan, was higher than that of Pb at Tokyo, on the east side; this result indicates that TAPs affect western Japan more than eastern Japan. We inferred the main source of Cu to be braking abrasion from cars at local scale on the basis of its enrichment factor and size distribution. From the Pb₍₀.₅<Dₚ < ₁₎/Cu₍₂.₅<Dₚ < ₁₀₎ ratio and sulfate concentration, we inferred that the highest contribution of TAPs to the total mass concentration in Tokyo occurred in spring, when TAPs accounted for 55%, 72%, and 53% of the total mass concentration in the 0.1 < Dp < 0.5, 0.5 < Dp < 1, and 1 < Dp < 2.5 fractions, respectively. These results can contribute to assessment of TAPs in Tokyo.