Environmental Research最新文献

In this study, we conducted an analysis of the heavy metal concentrations, health risk assessment, fraction and source interpretation in surface and core sediments from main stream of the Pearl River and Pearl River Estuary (RRE) area. Results showed that the higher deposited heavy metal concentrations in sediments occur at the Pearl River. The concentrations of heavy metals in surface sediments from the studied locations are in a descending order: Zn > Cr > Cu > Ni > Pb > Cd. Regarding chemical fractions, Cd showed the highest proportion of acid soluble fraction (F1) among all studied heavy metals. The high mobility of Cd poses a significant threat to water bodies and the surrounding environment. The potential ecological risk index (RI) showed the Pearl River sediments exhibited significantly higher values than the estuary sediments. Cd was found to be the primary contributor to potential ecological risk, accounting for 74% of RI. The health risk assessment showed the total hazard index (HI) for child was exceeded 1 mainly driven by Zn, indicating that the child population was at risk of non-carcinogenic effects. Besides, unacceptable carcinogenic risk in both Pearl River and estuary area were observed for children. The positive matrix factorization (PMF) model was used to ascertain sources of six heavy metals and apportion their contributions in sediments. The results showed that the source contributions of natural, industrial, and mixed sources from coal combustion and traffic emissions accounted for 39.81%, 34.10%, 26.10%.

Photocatalytic property of nano Ag is weak and its enhancement is important to enlarge its application. Herein, a novel strategy of constructing silver g-C₃N₄ biochar composite (Ag-CN@BC) as photocatalyst is developed and its photocatalytic degradation of bisphenol A (BPA) coupled with peroxydisulfate (PDS) oxidation process is characterized. Characterization result showed that silver was evenly embedded into the g-C₃N₄ structure of the nitrogen atoms format, impeding agglomeration of Ag by distributing stably on biochar. In optimum condition, BPA of 10 mg/L could be degraded completely at pH of 9.0 with a 0.5 g/L photocatalyst, 2 mM PDS in Ag-CN@BC-2 (Ag/melamine molar ratio of 0.5)/PDS system (99.2%, k = 4.601 h⁻¹). Ag-CN@BC shows superior mineralization ratio in degrading BPA to CO₂ and H₂O via active radical way, including holes (h⁺), superoxide radicals (•O₂^⁻), sulfate radicals (SO₄•^⁻), and hydroxyl radicals (•OH). Proper amount of silver can be dispersed effectively by gC₃N₄, which is responsible for improving the visible-light absorbing capability and accelerate charge transfer during activation of PDS for BPA degradation, while biochar as carrier in the composite is supposed to enhance the photoelectric degradation of BPA by reducing the band gap and increasing the photocurrent of Ag-CN@BC catalyst. Ag-CN@BC exhibits excellent catalyst stability and photocatalytic activity for treatment of toxic organic contaminants in the environment.

Enzymatic hydrolysis has been considered as an eco-friendly pretreatment method for enhancing bioconversion process of food waste (FW). However, existing commercial enzymes and microbial monomer-based compound enzymes (MME) have the issues of uneven distribution of enzymatic activity and low matching degree with the components of FW, leading to low efficiency with enzymatic hydrolysis and removal of antibiotic resistance genes (ARGs). This study used FW as the substrate, under the co-culture system, produced a microbial consortium-based compound enzymes (MCE) with oriented and well-matching degree for FW hydrolysis and ARGs removal, of which the performance, metabolic pathways and microbial communities were also investigated in depth. Results showed that the best performance for ARGs was achieved by the MCE prepared by mixing 1:5 of Aspergillus oryzae and Aspergillus niger after 12 days fermentation. The highest soluble chemical oxygen demand (SCOD) concentration and ARGs removal could respectively reach 83.90 ± 1.67 g/L and 45.95% after MCE pretreatment. The analysis of metabolic pathways revealed that 1:5 MCE pretreatment strengthened the catalytic activity of carbohydrate-active enzymes, increased the abundances of genes involved in cellulose and starch degradation, polysaccharide synthesis, ATP binding cassette (ABC) transporters and global regulation, while decreased the abundances of genes involved in mating pair formation system, two-component regulatory systems and quorum sensing, thereby enhanced FW hydrolysis and restrained ARGs dissemination. Microbial community analysis further indicated that the 1:5 MCE pretreatment promoted growth, metabolism and richness of functional microbes, while inhibited the host microbes of ARGs. It is expected that this study can provide useful insights into understanding the fate of ARGs in food waste during MCE pretreatment process.

Per

Polyfluoroalkyl substances (PFASs), typical persistent organic pollutants detected in various water environments, have attracted widespread attention due to their undesirable effects on ecology and human health. Constructed wetlands (CWs) have emerged as a promising, cost-effective, and nature-based solution for removing persistent organic pollutants. This review summarizes the removal performance of PFASs in CWs, underlying PFASs removal mechanisms, and influencing factors are also discussed comprehensively. Furthermore, the environmental risks of PFASs-enriched plants and substrates in CWs are analyzed. The results show that removal efficiencies of total PFASs in various CWs ranged from 21.3% to 98%. Plant uptake, substrate absorption and biotransformation are critical pathways in CWs for removing PFASs, which can be influenced by the physiochemical properties of PFASs, operation parameters, environmental factors, and other pollutants. Increasing dissolved oxygen supply and replacing traditional substrates in CWs, and combining CWs with other technologies could significantly improve PFASs removal. Further, CWs pose relatively lower ecological and environmental risks in removing PFASs, which indicates CWs could be an alternative solution for controlling PFASs in aquatic environments.

Knowledge about the characteristics of overburden and tailings from manganese (Mn) mining is essential for defining their levels of potentially toxic elements (PTEs) and appropriate environmental management. This study aimed to assess the total and bioavailable contents of PTEs in Mn mining areas in the Eastern Amazon, as well as the associated environmental risks. The samples were collected in areas of overburden and tailings deposition, in addition to forest soils in the Azul mine, Carajás Mineral Province, Brazil. These samples were characterized in terms of fertility, granulometry, and total and bioavailable PTE contents. The pH values of the forest soil were more acidic than those of the overburden and tailings, and the organic matter contents were considerably higher in the forest soil. All PTEs, especially Mn, Ba, Cu, Zn, and Pb, presented higher contents in the overburden and tailings. However, chemical fractionation revealed that PTEs were predominantly in the residual fraction, with percentage contents above 60% of the total content. These results suggest a low risk of environmental contamination. The findings of this study may support more efficient environmental rehabilitation in Mn mining areas in the Amazon.

Microplastics (MPs) are a global concern as an emerging pollutant, and the investigation on MPs in Antarctic aids in informing their global pollution assessments. Therefore, there are urgent scientific concerns regarding the environmental behavior, origins, influencing factors, and potential hazards of MPs in Antarctica. This study presents the characteristics of MPs from one ornithogenic sediment profile (coded CC) and two ornithogenic soil profiles (coded MR1 and MR2) from ice-free areas on Ross Island, Antarctica. We explored the potential sources of MPs and the main influencing factors for deposition based on their distribution with depth in the profiles. Through laser-infrared imaging spectroscopy (LDIR), a total of 30 polymer types were identified in all samples, with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) as the dominant types, accounting for more than 70% of the total. The abundance of MPs in the CC sediment profile ranged from 2.83 to 394.18 items/g, while in MR1 and MR2 soil profiles, the abundance ranged from 2.25 to 1690.11 and 8.24 to 168.27 items/g, respectively. The size of MPs was mainly concentrated in the range of 20–50 μm, and possible downward movement of certain polymer types was revealed. From the perspective of temporal variation, we suggest that MPs were heavily influenced by local human activities including scientific research, fishing, and tourism, balanced by protective regulations, while no solid evidence was obtained to support strong influence from biological transport through penguins. This research enhances our understanding on the environmental behavior of MPs in the terrestrial systems of remote polar regions.

Soil health is integral to sustainable agroecosystem management. Current monitoring and assessment practices primarily focus on soil physicochemical properties, yet the perspective of multitrophic biodiversity remains underexplored. Here we used environmental DNA (eDNA) technology to monitor multitrophic biodiversity in four typical agroecosystems, and analyzed the species composition and diversity changes in fungi, bacteria and metazoan, and combined with the traditional physicochemical variables to establish a soil health assessment framework centered on biodiversity data. First, eDNA technology detected rich multitrophic biodiversity in four agroecosystems, including 100 phyla, 273 classes, 611 orders, 1026 families, 1668 genera and 1146 species with annotated classification, and the relative sequence abundance of dominant taxa fluctuates tens of times across agroecosystems. Second, significant differences in soil physicochemical variables such as organic matter (OM), total nitrogen (TN) and available phosphorus (AP) were observed among different agroecosystems, nutrients were higher in cropland and rice paddies, while heavy metals were higher in fish ponds and lotus ponds. Third, biodiversity metrics, including α and β diversity, also showed significant changes across agroecosystems, the soil biota was generally more sensitive to nutrients (e.g., OM, TN or AP), while the fungal communities were mainly affected by heavy metals in October (e.g., Cu and Cr). Finally, we screened 48 sensitive organismal indicators and found significant positive consistency between the developed eDNA indices and the traditional soil quality index (SQI, reaching up to R² = 0.58). In general, this study demonstrated the potential of eDNA technology in soil health assessment and underscored the importance of a multitrophic perspective for efficient monitoring and managing agroecosystems.

In the context of global warming, the accelerated evaporation of seawater will lead to a continuous expansion of saline-alkali land area. As an important economic freshwater crustacean, investigation on the mechanism of damage to Eriocheir sinensis (E. sinensis) under saline-alkali environment will provide a valuable precedent for understanding the detrimental effect of climate change on crustaceans. In this study, histopathological analysis and integrative omics analysis were employed to explore the injury mechanism on the cerebral nervous system of E. sinensis exposure to saline-alkali stress. Our findings revealed that under this stress E. sinensis exhibited behavioral disorders and damage to cerebral neurosecretory cells and key organelles. Additionally, several pathways related to detoxification metabolism, neurotransmitter synthesis, and antioxidant defense were significantly down-regulated. Collectively, these results show, for the first time, that saline-alkali stress can induce neurodegenerative disease-like symptoms in E. sinensis, and provide critical information for understanding the harmful effects of saline-alkali environments.

The significance of intermittent streams in nutrient loss within forest ecosystems is becoming increasingly critical due to changes in precipitation patterns associated with global climate change. However, few studies have focused on nutrient export from intermittent streams. We conducted continuous sediment collection from intermittent streams from March 2022 to February 2023 to investigate the export pattern and mechanism of sediment-associated nitrogen (N) from intermittent streams of different forest types (composed forest of Castanopsis carlesii (Cas. carlesii) and Cunninghamia lanceolata (C. lanceolata) forests, compared to Cas. carlesii forests). We measured the N concentrations and calculated the export amounts of four common forms of N associated with sediments: total N (TN), dissolved N (DN), nitrate, and ammonia. Our results showed that (1) the annual average exports of TN, DN, nitrate, and ammonia associated with sediments from intermittent streams from both forest types were 273, 1.62, 0.26, and 0.84 kg ha⁻¹, respectively; (2) N export was significantly higher in composite forests of Cas. carlesii and C. lanceolata, compared to Cas. carlesii forests; (3) stream sediment export amount positively affected N export both in composite forests and Cas. carlesii forests; and (4) N export was also controlled by rainfall amount and stream characteristics. Our study quantified sediment-associated N export from intermittent streams among different subtropical forest types, which will enhance our understanding of N dynamics associated with stream hydrological processes in subtropical forests.

Parabens are common contaminants in river and lake environments. However, few studies have been conducted to determine the effects of parabens on bacteria, phytoplankton, and zooplankton communities in aquatic environments. In this study, the effect of methylparaben (MP) on the diversity and community structure of the aquatic plankton microbiome was investigated by incubating a microcosm with MP at 0.1, 1, 10, and 100 μg/L for 7 days. The results of the Simpson index showed that MP treatment altered the α-diversity of free-living bacteria (FL), phytoplankton, and zooplankton but had no significant effect on the α-diversity of particle-attached bacteria (PA). Further, the relative abundances of the sensitive bacteria Chitinophaga and Vibrionimonas declined after MP addition. Moreover, the relative abundances of Desmodesmus sp. HSJ717 and Scenedesmus armatus, of the phylum Chlorophyta, were significantly lower in the MP treatment group than in the control group. In addition, the relative abundance of Stoeckeria sp. SSMS0806, of the Dinophyta phylum, was higher than that in the control group. MP addition also increased the relative abundance of Arthropoda but decreased the relative abundance of Rotifera and Ciliophora. The β-diversity analysis showed that FL and phytoplankton communities were clustered separately after treatment with different MP concentrations. MP addition changed community assembly mechanisms in the microcosm, including increasing the stochastic processes for FL and the deterministic processes for PA and phytoplankton. Structural equation modeling analysis showed a significant negative relationship between bacteria richness and phytoplankton richness, and a significant positive relationship between phytoplankton (richness and community composition) and zooplankton. Overall, this study emphasizes that MP, at environmental concentrations, can change the diversity and structure of plankton microbial communities, which might have a negative effect on ecological systems.