Chemosphere最新文献

Cyanobacterial blooms are prevalent globally and present a significant threat to water security. Titanium salt coagulants have garnered considerable attention due to their superior coagulation properties and the absence of metal residue risks. This paper explored the influencing factors in the coagulation process of titanium xerogel coagulant (TXC), the alterations in cell activity during floc storage, and the release of cyanobacterial organic matters, thereby determining the application scope of TXC for cyanobacterial water treatment. The findings indicated that at a TXC dosage of 8 mg Ti/L, the removal rate of Microcystis aeruginosa (M. aeruginosa) exceeded 86% across a pH range of 5-9. The coagulation performance with anions HCO₃^-, CO₃^2- and H₂PO₄^-/HPO₄^2- was unsatisfactory at concentrations of 10, 20, and 50 mg/L, with corresponding chlorophyll a (Chl-a) levels of 168, 129, and 196 μg/L, respectively. While the presence of Cl^-, NO₃^-, SO₄^2-, K⁺, NH₄⁺, Ca²⁺ and Mg²⁺ had little influence on the removal efficiency. At sodium alginate (SA) concentration of 6 mg/L, the Chl-a content was 116 μg/L, with humic acid (HA) not affecting M. aeruginosa removal but hindering turbidity reduction, leaving a residual turbidity of 11 NTU. Following TXC treatment, a floc storage study with cyanobacteria-laden surface water showed a decrease in microcystins (MCs) content. The low residual titanium concentration post-TXC coagulation (<0.06 mg/L) and MCs reduction contributed to reduced effluent toxicity, indicating TXC's versatile applicability for treating cyanobacterial-contaminated waters.

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Ciguatera poisoning (CP) is one of the most prevalent non-bacterial seafood-borne illnesses worldwide, caused by the consumption of fish contaminated with ciguatoxins (CTXs). Even though its prevention largely relies on avoidance of certain fishes and geographic regions, the development of rapid and user-friendly bioanalytical methods for effective CP management and surveillance is still necessary. In this work, four simplified strategies of a magnetic bead (MB)-based sandwich immunoassay were proposed for the rapid and highly sensitive detection of CTXs in fish. The one consisting of a single step was selected, which allowed the detection of CTXs in a fish extract in only 40 min at levels as low as 0.01 μg CTX1B equivalents/kg of fish, which is the safety guidance level proposed by the United States Food and Drug Administration (FDA). In this strategy, all components were incubated simultaneously with the sample, only requiring a subsequent washing and substrate incubation step before signal measurement, reducing the complexity and the time required for analysis in contrast with the classical sequential sandwich immunoassays. The ease of experimental handling, added to the short analysis time and appropriate sensitivity make this single-step immunoassay a promising tool for CP risk assessment and management.

The uneven distribution of lead (Pb) in rice and soil across the primary rice-growing regions of southern China has led to challenges in assessing rice quality and associated health risks. Therefore, it is crucial to develop a fast and precise method for forecasting the accumulation of Pb in soils and rice to evaluate the environmental risks of heavy metals. We utilized eight machine learning models to fit the training data and find the optimal model based on 1,396 pairs of soil-rice samples collected during field surveys in Guizhou Province. Among them, the random forest model achieved higher prediction accuracy (rice: R² = 0.486; soil: R² = 0.518) and was further optimized using a Bayesian optimizer to enhance its performance (rice: R² = 0.662; soil: R² = 0.718). The importance of characteristics showed that annual precipitation and soil effective state were the main factors affecting rice Pb accumulation; distance to the nearest mine and annual rainfall were the main factors affecting total soil Pb. The area with higher risk of Pb accumulation in soil was located in the western part of Bijie, while the area with higher risk of Pb accumulation in rice was located in the southern part of Tongren. There were some differences between the two. About 88% of the areas in Guizhou Province are classified as priority protected areas regarding safe planting zoning, with safe utilization areas accounting for about 10%. However, areas in the eastern part of Qiandongnan, the southeastern part of Tongren, and the western part of Bijie require strict control. Our study attach great importance to the prevention of high Pb accumulation in rice as well as in soils in major rice growing areas.

Methyl 2-{[1-(5-fluoropentyl)-1H-indazole-3-carbonyl]amino}-3,3-dimethylbutanoate (5F-ADB), which is classified as an illicit drug in China and most European countries, is susceptible to abuse. The abuse of 5F-ADB must avoid entering the water environment. However, the aquatic toxic effects of 5F-ADB remain unclear. In this study, Daphnia magna (D. magna) was used to investigate the potential toxicity of 5F-ADB at concentrations of 0, 0.01, 1, and 100 μg/L. The results showed that 5F-ADB caused significant developmental, reproductive, and neurodevelopmental toxicity in D. magna. Compared with the control group, exposure to 5F-ADB significantly reduced daphnia body length, weight, heartbeat, total number of offspring, while increased daphnia respiratory rate, and swimming behavior. Superoxide dismutase (SOD) activity increased significantly, while catalase (CAT) activity decreased, indicating that the exposed daphnia suffered obvious oxidative damage. 5F-ADB also triggered the inhibition of the serotonergic and noradrenergic systems, which ultimately stimulated the swimming behavior of D. magna. This study demonstrates that 5F-ADB has a significant toxic effect on the vital activity of D. magna upon entering aquatic environments, and that synthetic cannabinoid analogs such as 5F-ADB may pose potential ecological risks to organisms in aquatic ecosystems.

The environmental safety and health impacts of nanosilver have attracted much attention due to their continuous detection in water. Although the effects of nanosilver on aquatic organisms have been reported, the ecotoxicity and underlying mechanism of nanosilver in aquatic organisms are not fully understood. Fish gills are the primary target organs of pollutant exposure in aquatic environments, and is important to clarify the impact of nanosilver on aquatic organisms by systematically and comprehensively revealing the effect of nanosilver on fish gills. Here, we review the ecotoxicity and potential mechanisms of nanosilver on fish gills. Studies have shown the most commonly used and toxic nanosilver for studying the effects of nanosilver on fish gills is 5-30 nm. Nanosilver mainly affects various physiological functions of fish gills, such as respiration, ion, and osmotic pressure regulation, by disrupting the structure and components of tissues or cells (e.g., cell membranes and mitochondria), as well as interfering with tissue lipid, amino acid, and carbohydrate metabolism. The main mechanisms of toxicity induced by nanosilver in fish gills are gill membrane damage, oxidative stress, and silver ion release. This review provides a scientific basis for the detrimental effects of nanosilver on aquatic ecological environment health and the protection of fish resources.

Triclosan (TCS) is an antimicrobial agent commonly used in personal care products. The assessment of TCS exposure in humans frequently relies on analyzing urinary TCS levels. Consequently, it is crucial to have a comprehensive understanding of the variability of TCS levels in urine. However, studies of temporal variations in urinary TCS levels at different time intervals among youth are lacking. This study collected urine samples from 109 participants over a period of one year to assess the temporal variability of TCS over different time intervals. The detection rate of TCS in urine was 75%. The intraclass correlation coefficient (ICC) indicated good reproducibility of TCS in spot urine among youth at a day, a week, and a month (ICC = 0.541-0.857), but the poor reproducibility within one year (ICC = 0.209). The number of spot urine samples needed to provide dependable exposure estimates (ICC > 0.8) at different time periods over the course of a year ranges from 1 to 16 tubes (m = 1-16). The sensitivity and specificity of TCS as a predictor of the mean annual top 33% concentration of TCS ranged from 0.667 to 1.000 and from 0.519 to 1.000, respectively. In addition, Spearman correlation analysis revealed that TCS levels were significantly associated with the use of various personal care products (antibacterial ointment, mouthwash or body deodorant, hand sanitizer) (p < 0.05). In light of these findings, it is recommended that urine samples be collected in 1 to 16 tubes at least 3 months apart to accurately assess the level of exposure at the appropriate time of the year, facilitating the prospective assessment of TCS exposure in different epidemiological studies.

Polychlorinated dibenzo-p-dioxins (PCDDs) are persistent organic pollutants that pose considerable threats to ecological and human health owing to their high toxicity potential. Understanding the mechanisms for underlying the base-catalyzed hydrolysis of PCDDs in aquatic environments is essential for assessing their environmental behaviour and ecological risks. Herein, we combined quantitative structure-activity relationship (QSAR) models with density functional theory calculations to analyse the base-catalyzed hydrolysis mechanisms of PCDDs. Among the four developed QSAR models, the single-parameter QSAR model based on the lowest unoccupied molecular orbital energy (E_LUMO) demonstrated the best performance, achieving a coefficient of determination of 0.89 and a root mean square error of 0.49, indicating superior overall performance. Results indicate that the second-order rate constants for base-catalyzed hydrolysis (k_OH) of PCDDs are primarily influenced by E_LUMO, molecular polarizability (α), molecular volume (V_m), degree of chlorination (N_Cl), and chlorine position. Specifically, increases in the α and V_m values of PCDDs lead to higher logk_OH values, while an increase in the E_LUMO value results in a lower logk_OH value. This study elucidates the relationship between the molecular structure and the rate of base-catalyzed hydrolysis of PCDDs for the first time, providing valuable insight into their environmental fate. Furthermore, this research offers a novel theoretical perspective on the base-catalyzed hydrolysis of PCDDs, which will aid in regulatory assessments and risk management.

Chlorpyrifos (CLP) and deltamethrin (DTM) are among the most widely utilized organophosphate and pyrethroid insecticides globally. Their simultaneous presence in aquatic environments poses significant threats to fish health and challenges the sustainability of aquaculture practices. Despite their prevalence, the combined toxic effects of CLP and DTM on hook snout carp (Opsariichthys bidens Günther) remain insufficiently understood. In this study, O. bidens were exposed to waterborne treatments of CLP, DTM, or their combination for 30 days, and the biochemical and molecular responses of the liver tissue were systematically assessed. Acute toxicity tests revealed that the combined exposure to CLP and DTM resulted in synergistic toxicity. Significant alterations in the activities of key enzymes, including superoxide dismutase (SOD), catalase (CAT), caspase-3 (CASP-3), and caspase-9 (CASP-9), relative to the control group, demonstrated that co-exposure induced oxidative stress in O. bidens. Additionally, the elevated transcriptional levels of immune-related genes such as cxcl-c1c, il-8, and il-1 suggested a pronounced inflammatory response triggered by the pesticide mixture. Conversely, the significantly reduced expression of p53 and esr indicated that combined exposure disrupted apoptotic regulation and endocrine system function in the fish. In summary, these findings demonstrated that co-exposure to CLP and DTM induced liver damage in O. bidens by impairing antioxidant enzyme activity, disrupting apoptosis regulation, and altering the transcriptional profiles of genes involved in immune and endocrine pathways. These results provided new insights into the physiological and molecular mechanisms of pesticide-induced hepatotoxicity in fish and offered valuable information for evaluating the ecological risks associated with pesticide mixtures in aquatic environments.

N-doped hierarchical porous carbon (N-HPC) is made from waste lignin by a one-pot method, and its mechanisms of Cr (VI) removal was investigated. The specific surface area (S_BET) of N-HPC-Fe3 was 1749.8 m²/g, the experimentally determined equilibrium adsorption capacity (q_e) for Cr (VI) was 386.5 mg/g, and the calculated maximum adsorption capacity (q_m) was 627.1 mg/g, which showed excellent adsorption performance. The adsorption process is consistent with the Langmuir model and the pseudo-second-order model. The removal process of Cr (VI) was proposed: the high specific surface area and positively charged surface of N-HPC enhanced the pore filling and electrostatic adsorption effects; and the high content of nitrogen-oxygen functional groups acted as electron donors and adsorption active sites, which reduced Cr (VI) to Cr (III) and complexed it to the N-HPC surface. The contribution of different mechanisms was quantified and 85.1% reduction was the main removal mechanism. The removal efficiency of N-HPC reached 76.5% after 7 cycles and was minimally affected by coexisting ions, showing excellent reusability, stability and selectivity. This study emphasizes the potential of using cost-effective and sustainable biomass waste carbon for Cr (VI) removal, providing a theoretical and practical basis for environmental remediation.