Environmental Chemistry and Ecotoxicology最新文献

The ecological and human health risks associated with heavy metal(loid)s (HMs) have attracted much attentions worldwide. In this study, 153 topsoil samples were collected across China in 2019, aiming to investigate the HMs pollution characteristics. The soil samples were collected from areas such as parks, schools, communities, and rural regions, which were far away from pollution sources of HMs. In order to study the temporal trend of pollution, related studies from 2000 to 2015 in China were also summarized. The findings indicated that Cd, Cu, Zn, and Pb were the major HMs with the mean concentrations of Cd, Cu, Zn, and Pb were 0.40, 36.5, 107, and 33.5 mg/kg, respectively. High background values and metal processing resulted in high total concentrations of Cd, As, Cr, and V especially in Southwest China (such as Guizhou and Yunnan provinces). The result of the Positive Matrix Factorization (PMF) model indicated the primary source of HMs was natural source (45.3%), followed by traffic source (20.6%), industrial source (17.3%), and agricultural source (16.8%). The health risk assessment of HMs indicated that non-carcinogenic risks were minimal, however, carcinogenic risks (95th) for As, Cr, and Cd should attract attentions. Compared with the measurements from 2000 to 2015, the pollution levels of HMs showed a decreasing trend in China in 2019, which indicated the effectives on HMs control along with the implementation of the control policy on soil in China.

Micropollutants such as steroid hormones contaminate water worldwide and cause significant damage. Wastewater treatment plants (WWTPs) partially remove them, and they have low biodegradability leading to their persistence in water bodies. They are endocrine disruptor compounds in aquatic organisms. Various environmental conditions contribute to their persistence in the environment like soil pH, organic matter, soil conditions, and temperature. The aquatic environment is most threatened even when present at very low concentrations. The environment is exposed to steroid hormones from agricultural run-offs, pharmaceutical and industrial waste, and veterinary medicine. Since most WWTPs partially remove contaminants, there is a need for new and improved technologies for higher and more efficient removal of steroid hormones.

This paper discusses the fate and toxicity of steroid hormones in the aquatic environment. It further elucidates the existing and emerging technologies in the treatment of steroid hormones in aquatic environments. Finally, the conclusion of this review along with the current limitations and future research perspectives of hormones present in the environment are elucidated.

The treatment of drinking water using Moringa oleifera (MO) Lam. seeds is gaining popularity as a sustainable alternative to synthetic chemicals. However, there is limited literature on the effect of particle size of the ground MO seeds on their coagulation characteristics, which is revealed in this study. To investigate the impact of the particle size, the sun-dried MO seeds were ground and sieved into five distinct sizes ranging from (i) <0.25 mm, (ii) 0.25–0.4 mm, (iii) 0.4–0.8 mm, (iv) 0.8–1.25 mm, and (v) 1.25–2.0 mm. The seed protein for the experiment was then prepared by stirring a 2% (w/v) solution of the five different seed powders in tap water. Six different protein doses between 100 and 350 mg/l were added to separate glass beakers featuring a synthetic solution of 80 nephelometric turbidity units (NTU) turbidity. The experimental results revealed that the MO seed particle sizes of 0.8–0.4 mm and 0.4–0.25 mm demonstrated superior coagulation characteristics compared to the other size categories tested. Specifically, a dose of 200–300 mg/l was found to be effective in reducing the turbidity to 5 NTU and eliminating $\sim$100% of E. coli after 3 h of settling. The surface characterisation showed a heterogenous surface and the presence of functional groups, which may have aided coagulation and caused the reduction in turbidity and microbial load. Statistical analysis revealed a P value <0.05, indicating that the results were highly consistent with no >5% variation. The study is also extended to explore the mechanism of coagulation of MO seeds, and the potential application of the research at a domestic scale is also discussed. Overall, the resulting water treated with MO met the WHO criteria.

Microbial biodegradation of oil pollutants and their derivatives has become the most environmental-friendly method in the developing world. The aim of this study was to evaluate crude oil biodegradation potential of lipase produced by indigenous bacteria from oil contaminated soil. Indigenous bacteria isolates were identified as species of Bacillus subtilis and Pseudomonas aeruginosa, the isolates were able to produce lipase as revealed in their zone of clearance on tween 80 agar plates and the presence of lipase produced by the two bacteria were further confirmed using spectrophotometric analyses. Lipase produced by B. subtilis showed maximal lipase activity at pH 8 and 40$°C$ while the enzyme produced by P. aeruginosa showed maximal lipase activity (U/mL) at pH 8 and 50$°C$ when subjected to various pH and temperature respectively. Lipase produced by B. subtilis recorded 8.11 ± 0.70$\%$ of crude oil degradation in mineral salt medium within 28 days, while that of P. aeruginosa recorded 15.6 ± 0.03$\%$ of crude oil biodegradation. The GC–MS analysis of the crude oil treatment showed complete mineralization of several compounds, and also showed peak reduction which indicates lipase efficiency in the degradation of hydrocarbons. As revealed by GC–MS analysis, out of the 8 hydrocarbons identified in an undegraded oil, 5 were completely degraded by the enzyme activities while 2 (toluene and methyl, cyclopentane) were identified with hydrocarbons treated with lipase. The enzymes produced by B. subtilis and P. aeruginosa can serve as useful product for bioremediation of crude oil contaminated soil.

Microplastics are widespread pollutants in the environment, with characteristics such as small particle size, strong adsorption, and difficult degradation, and have gradually become a global pollution problem, potentially endangering host health via various mechanisms. Currently, numerous research has verified biological toxic effects of microplastics in a variety of organisms and human organs and tissues, while the understanding of interaction between microplastics and bone metabolism is still limited. Based on assessing the relevance between microplastics and bone metabolism, strengthening the monitoring and control of microplastic pollution, and clarifying the mechanisms of microplastics on the bone metabolism, is critical for prevention and treatment of bone metabolic diseases. Herein, this review summarizes the classification of microplastics, source and distribution of microplastics, pathways of microplastics invading host, impacts and mechanisms of microplastics modulating the bone metabolism, and potential recommendations for preventing bone metabolic diseases caused by microplastic invasion, thus providing a novel perspective for the in-depth exploration of microplastics on bone metabolism and pivotal references for the future related researches and health policy formulation.

Environmental toxins threaten human health and ecosystem integrity, necessitating advanced detection, degradation, and removal methodologies. In recent years, the scientific community has increasingly focused on MXenes, a novel class of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, due to their exceptional potential in toxin management. This comprehensive review thoroughly examines MXenes, including synthesis methods, structural and chemical properties, and functionalization strategies. Unique to this review is the integrated discussion of MXenes in the context of environmental toxin management, encompassing detection, degradation, and removal within a single study. The enhancement of sensor technologies using MXenes for rapid and precise toxin detection is thoroughly analyzed. It focuses on MXene-mediated degradation pathways, especially photocatalytic and electrocatalytic mechanisms, considering their redox potential and light-harvesting capabilities. Additionally, the adsorption dynamics of MXene-based adsorbents are scrutinized, covering adsorption capacity, kinetics, and regeneration/recyclability. The review offers a comparative evaluation of MXenes with other 2D materials, positioning MXenes within the broader context of toxin management solutions. This article stands out for its novel and comprehensive approach, being the first to concurrently address the detection, degradation, and removal of environmental toxins using MXenes. The review concludes by underscoring the vast potential of MXenes in addressing environmental toxins. It emphasizes the urgent need for continued research to optimize their performance, scale up production, and enable practical implementation. This detailed reference aims to serve researchers and practitioners in environmental management, guiding future innovations and applications of MXenes in toxin control.

Nutrient washout remains a key drawback of nutrient supplementation during bioremediation interventions in aquatic systems. This study assessed the adsorption and controlled release properties of biochar‑iron oxide nanoparticle (IONPs) beads laden with bacteria and nutrients for treatment of petroleum spills in freshwater ecosystems in a bid to counter the challenge of nutrient washout. The IONPs synthesised from phytoextracts were decorated on biochar made from cow bones at 500 °C. The composite produced was embedded in an alginate matrix with degradative bacteria and inorganic nutrients via physical crosslinking. Swelling indices revealed better release properties for the monoammonium phosphate nutrients with the beads that had the biochar‑iron oxide nanocomposite incorporated (BCNP). The 15-min swelling indices (SI₁₅) for the beads ranged from 0.13 to 2.00. Batch adsorption experiments revealed that adsorption was physical in nature and higher at lower adsorbate concentrations with significant differences (p ≤ 0.05) between the three groups of adsorbents. The BCNP bead showed the greatest sorption levels (71.69%) compared to the plain biochar beads (57.83%) and the biochar powder (46.12%). Based on the adsorption parameters obtained, it was concluded that the adsorption data were more suited to the Freundlich isotherm model and the pseudo-second order kinetic model. The study developed a slow-release nanocomposite that could counter the challenge of nutrient washout associated with bioremediation in aquatic ecosystems.

This study is an attempt to assess the influence of the oil storage depot discharges on proximate water sources in Ibadan, southwest Nigeria. Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were examined in a total of 15 water samples (10 groundwater +4 surface water samples) utilizing gas chromatography–mass spectrometry, after extraction of the waters with dichloromethane and clean-up of the extracts. Results revealed that values of overall PAHs in groundwater (GW) and surface water (SW) varied from 0.01 to 3.45 mg/L (mean = 0.42 mg/L) and 0.01 to 0.09 mg/L (mean = 0.05 mg/L), correspondingly. The highest value of ∑15 PAHs (3.45 mg/L) was observed at 24 m to the discharge point. The ring wise distribution pattern of the PAHs in collected water samples follows the order: 2–3 rings >5–6 rings >4 – ring PAHs and low molecular weight (LMW) PAHs accounted for 90.73% relative to HMW (9.27%) in groundwater samples. The diagnostic ratios suggested that the PAHs pollution in water were likely from incomplete combustion of fossil fuels, vehicle emissions and released petroleum effluents from nearby depot. The concentration of carcinogenic PAHs in GW and SW ranged from $1\times {10}^{-2}$to $9\times {10}^{-2}$ mg/L and $1\times {10}^{-2}$to $7\times {10}^{-2}$ mg/L, correspondingly, which highlights possible human health risks. The values of hazard index (HI) for the studied samples via the oral ingestion and dermal exposure pathways are less than unity, suggesting no adverse non-carcinogenic health effects. The calculated incremental lifetime cancer risk (ILCR) for adults and children are in the 10⁻²–10⁻³ range, implying noteworthy possible carcinogenic health effects to human beings, with children being the most susceptible. Correspondingly, dibenzo [a, h] anthracence (DahA) and Benzo [a] pyrene (BaP) were established to be of greater carcinogenic threats in the waters taken from the study location. The study advocates complete discontinuance of discharge release into the neighboring environment.

The multifunctional properties of biochar make it a promising adsorbent of heavy metals for environmental bioremediation. Pyrolytic temperature is a key factor that impacts the properties, performance, and mechanisms of agro-wastes-derived biochar because of the physiochemical transformation of its structural composition. It has been deliberated that increased pyrolysis temperatures strongly enhance specific surface area, pH, and high microporosity as well as carbon and ash content with low cation exchange capacity and volatiles content. The reason for different properties from different pyrolysis is related to the variations in the lignin-cellulose structures as well as moistures in different agro-waste biomasses. Biochar has been considered a low-cost material that has shown its convenient applicability in rural areas of developing countries where environmental contamination of heavy metals is emerging. A wide range of pyrolytic temperatures has shown distinctive properties and characteristics of biochar from different biomass and their capacities to remove heavy metals. Higher pyrolysis temperatures can exhibit higher specific surface areas, enhanced functional groups, and stability than modified biochar. Different pyrolysis temperatures exhibited diverse adsorption capacities on biomass such as rice husk and corncob, as efficiency increases with temperatures on selective heavy metals such as hexavalent chromium [Cr(VI)], cadmium [Cd(II)] and zinc [Zn(II)]. This review aimed to understand the physiochemical and structural properties, and the transformation of pristine biochar that can enhance the environmental bioremediation of heavy metals. The deliberations on the mechanisms of diverse biomasses obtained from different pyrolysis for decision-making processes as well as production costs were reviewed. The authors propose future investigations on heavy metal immobilization to unlock the full potential of biochar in environmental bioremediation.

The escalating production and ubiquitous presence of plastics and their degradation products, such as microplastics and nanoplastics, pose a significant environmental threat. Microplastics enter the soil through various pathways, including agricultural practices, plastic degradation, and wastewater disposal. Herein, we discussed the harmful effects of microplastics on the physicochemical properties of soil, plant growth, terrestrial fauna, and microbial activity, potentially affecting the stability and nutrient cycle of the soil ecosystem. This review delves into recent advances in potential microplastic bioremediation approaches, such as phytoremediation strategies utilized by plants and their associated microbes to accumulate, immobilize, and even degrade microplastics. Rhizosphere microorganisms play a crucial role in the degradation of microplastics, potentially utilizing them as a carbon source. Soil animals like earthworms, snails, and mealworms can also contribute significantly to bioremediation by ingesting and degrading microplastics through their gut microbiota. Various soil microorganisms, including bacteria and fungi, can degrade different microplastics with the help of enzymes such as laccase, esterase, peroxidase, oxidoreductase, and hydrolases and depolymerise the larger polymer chains into smaller units that ultimately mineralize them into CO_2, H₂O, and CH₄. Genetic engineering and synthetic biology are also used to create strains with enhanced microplastic degrading and mineralization capabilities. It holds promise for efficient bioremediation but requires further research for real-world application and scalable implementation. Overall, this review comprehensively highlights the potential of bioremediation approaches and future recommendations for tackling microplastic pollution. Further research and development are crucial for enhancing biodegradation efficiency and scaling up this strategy for environmental protection.