Toxics最新文献

Heavy metal-organic pollutants compound pollution at industrial legacy sites and have caused damage to the ecological environment and human health during recent decades. In view of the difficulty and high cost of post-contamination remediation, it is worth studying, and practically applying, cutoff walls to reduce the spread of pollution in advance. In this study, field-scale studies were carried out at e-waste dismantling legacy sites in Taizhou, Zhejiang Province of China, through the process of site investigation, numerical simulation, and cutoff wall practical application. Firstly, the concentrations and spatial distributions of Pb, Cd and polychlorinated biphenyls (PCBs) and poly brominated diphenyl ethers (PBDEs) were identified in both soil and groundwater. Then, potential dispersal routes of key combined contaminants (Pb and PCBs) at the soil-groundwater interface were systematically studied through numerical simulation applying Visual MODFLOW-MT3DMS. One site was chosen to predict the barrier effect of differently sized cutoff walls based on the migration path of compound pollutants. A protocol for a cutoff wall (50 m length × 2 m width × 3 m height) was finally verified and applied at the real contaminated site for the blocking of compound pollutant diffusion. Further, the groundwater quality of the contaminated site was monitored consecutively for six months to ensure the durability and stability of barrier measures. All pollutant indicators, including for Pb and PCB complex pollutants, were reduced to below the national Grade IV groundwater standard value, achieving environmental standards at these polluted sites and providing possibilities for land reuse. In summary, this field-scale test provided new ideas for designing cutoff walls to block the diffusion of complex pollutants; it also laid a basis for the practical application of cutoff walls in pollution prevention and control of complex contaminated sites and for soil-groundwater environmental protection at industrial heritage sites.

Cadmium (Cd) is a highly toxic substance in the aquatic ecosystem, which can represent a high risk to fish. Fish are exposed to heavy metals through waterborne and dietary pathways, some of which are absorbed by the body and can accumulate in specific tissues without being eliminated. The accumulation varies depending on several factors such as dose, exposure route, exposure time, metal types, and biological status of the fish, and environmental parameters such as DO, salinity, pH, and metal speciation. As Cd speciation occurs in the water, the amount accumulated in the fish can vary, and consuming Cd-accumulated fish can pose a risk to human health. Cd introduced into the body of fish can directly affect blood properties through the circulatory system. Cd introduced into the circulatory system of fish can reach all tissues through the blood flow, and the accumulation of specific tissues is different depending on the blood flow by the energy and oxygen demand of each tissue. Therefore, this review aimed to determine the toxic effects of Cd exposure in fish and identify indicators to assess the extent of Cd bioaccumulation toxicity in fish induced by Cd exposure.

Brazil is one of the largest consumers of herbicides in the world, and glyphosate-based herbicides (e.g., Roundup^®) are commonly applied in cropland. Among vertebrates, amphibians are especially susceptible to contamination due to their strong association with freshwater environments. However, our knowledge of how these herbicides affect amphibians is still scarce, mainly regarding the impacts of commercial formulations. In this study, we experimentally evaluated the effects of Roundup Original DI^®, a glyphosate-based herbicide, on tadpoles of Physalaemus cicada and Physalaemus erikae. Spawnings were collected in south and southern Bahia, transported to the laboratory, and kept until the tadpoles reached developmental stage 25. Tadpoles were acclimated for 24 h and subsequently exposed to increasing herbicide concentrations at acute and chronic levels to assess survival, lethal concentration (LC50 96 h), and morphological and ontogenetic responses. Contamination significantly decreased the survival of tadpoles of both species and affected the development of tadpoles of P. erikae. The estimated lethal concentration (LC50) after 96 h for Physalaemus cicada was 5.52 mg a.i./L, and Physalaemus erikae was 3.40 mg a.i./L. Also, at chronic concentrations, morphological changes were observed in the tadpoles of P. erikae, with the changes being mainly in the tadpoles' tail and body shapes. Therefore, Roundup Original DI^® is considered moderately toxic to both species. Our results extend the knowledge regarding the action of pesticides mainly for species of the genus Physalaemus, which is the best-known genus for glyphosate based-herbicide toxicity.

The association between heavy metal exposure and diabetes is controversial and vitamin E (VE) may reduce diabetes risk. We aimed to examine the associations between blood heavy metals (BHMs) and diabetes risk and VE's role in the relationship. From the 2007-2018 NHANES, 10,721 participants aged ≥ 18 were included for multiple statistical analyses, which revealed that BHMs and dietary VE intake were negatively associated with diabetes and fasting plasma glucose (FPG). The diabetes prevalence in each quartile (Q) of heavy metal exposure increased with age, but within age Q4, it generally decreased with exposure quartiles. Moreover, BHMs were positively associated with all-cause and diabetes-related mortalities with aging, which induced an age breakpoint of 65 years for age-stratified analyses on the associations between BHMs and diabetes risk. In those aged > 65, BHMs were negatively correlated with diabetes risk and its biomarkers; however, in adults aged 18-65, the correlation was positive. At higher VE intake levels, blood lead was associated with a lower diabetes risk and all three BHMs demonstrated lower FPG levels than those at lower VE intake levels. In conclusion, consuming sufficient VE and avoiding heavy metal exposure are highly recommended to reduce diabetes risk.

Environmental pollutants significantly impact health and quality of life. High levels of harmful metals in drinking water, vegetables, and soil can accumulate in the body, leading to serious health issues. In Gilgit-Baltistan, Pakistan, the prevalence of cancer is notably high, and heavy metals are considered among the possible risk factors. In this study, the distribution of heavy metals, e.g., Cd, Mn, Cu, Cr, and Ni, in the drinking water, vegetables, and soil in the Gilgit and Skardu Districts was assessed. A geo-accumulation index was combined with a deterministic technique to examine potential carcinogenic and non-carcinogenic impacts on human health. Cr and Ni levels in drinking water exceeded the permissible limits from both districts. Drinking water had a HQ > 1 for Cd, Cr, Ni, and Mn, posing significant non-carcinogenic health effects. The lifetime cancer risk (LCR) by drinking water for Cd, Cr, and Ni in Gilgit (0.0087, 0.55, and 0.0048) and Skardu (0.071, 0.21, and 0.014) indicated a considerable cancer risk (>1 × 10^-4) for adults. The cancer risk for vegetable intake was observed within the safe limit, while LCR_ingetsion > LCR_dermal and LCR_inhalation for the soil samples in both regions. These findings highlight the need for regular monitoring, enhanced waste management, and advanced purification methods to reduce cancer risk, lower heavy metal contamination, and safeguard public health in the region.

This study assessed the effects of fenobucarb (F) (1%, 10%, and 20% of the LC₅₀-96h value) on the brain cholinesterase (AChE) activity, food intake (FI), feed conversion rate (FCR), and growth of silver barb (Barbonymus gonionotus, Bleeker, 1849). It also assessed the AChE inhibition levels that cause the abnormal swimming, behavior, and mortality of silver barb and how the feeding regime affects the recovery rate of the AChE activity. The results showed that the brain AChE inhibition increased with the F concentrations. It peaked after nine hours, at 73.6% and 79.7% for the two highest concentrations, and then the AChE activity started to recover. After 96 h, the inhibition level was still 11.8% in the fish exposed to the two lowest concentrations and 30.5% in the fish exposed to the highest concentrations. Even when placed in clean water, the inhibition level in the fish that were exposed to the highest concentrations and only fed every third day was 32% after 14 days. Although there were no differences in the feed intake at any time, the fish exposed to F had a higher FCR and a lower specific growth rate and weight compared to the control fish at the later stages of the experiment. Thus, although the use of F in rice farming in the Mekong Delta may not lead to direct fish kills, it impacts the growth and health of the fish, which could have negative implications for wild fish populations and the long-term production of healthy fish in the Mekong Delta.

The present study collected wastewater samples from fourteen (14) full-scale wastewater treatment plants (WWTPs) at different treatment stages, namely, primary, secondary, and tertiary, to understand the impact of WWTP processes on the bacterial community structure, their role, and their correlation with environmental variables (water quality parameters). The findings showed that the bacterial communities in the primary, secondary, and tertiary treatment stages are more or less similar. They are made up of 42 phyla, 84 classes, 154 orders, 212 families, and 268 genera. Proteobacteria, Bacteroidetes, Cloacimonetes, Firmicutes, Euryarchaeota, Verrucomicrobia, Cyanobacteria, Desulfomicrobium, Thauera, Zavarzinia, and Nitrospirae, among others, dominated the bacterial community structure in all treatment stages. The biochemical oxygen demand was 7-12 times, chemical oxygen demand (COD) was 6 times, and total suspended solids (TSS) was 3.5 times higher in the wastewater than what the Central Pollution Control Board (CPCB) in New Delhi, India, allows as standard discharge. The correlation analysis using the Pearson r matrix and canonical correspondence analysis (CCA) also confirmed the fact that these water quality parameters (especially BOD and COD) play a pivotal role in deciphering the community structure in WWTPs.

Ecological integrity, encompassing physical, chemical, and biological aspects, is crucial for sustaining ecosystem service functions and stability. As the largest freshwater lake in China, the ecological integrity of Poyang Lake has attracted much attention due to the over-exploitation of its water resources in recent years. In this study, several biological and water quality surveys on water ecological conditions were carried out at 11 sampling points of Poyang Lake from 1998 to 2022, and the ecological health of Poyang Lake was evaluated by use of the O/E (Observation/Expectation) model and the chemical-biological index method according to the status of the water quality and the structure of the benthic fauna in the four seasons, respectively. The results showed that the benthic community structure is simple, and the biodiversity is low, which is mainly dominated by Insecta in Arthropoda and Oligochaeta in Oroidea, accounting for 84.3% and 42.4%, respectively; the results of the O/E index evaluated under the threshold of probability of capture ≥ 0.5 showed that the health grade of all sections was sub-healthy or average, which was consistent with the results of the chemical-biological composite index evaluation. The dual evaluation method of the O/E model and chemical-biological composite index adopted in this study integrates more than twenty years of long-time scale data; this method combined with long time scale data has not been studied before, and its advantage is that it can more objectively show the change in the ecological situation of Poyang Lake for many years. The results of the present study could provide a theoretical basis and technical support for the evaluation of lake water environment quality.

Active biomonitoring of mercury (Hg) using non-indigenous moss bags was performed for the first time within and around the former Hg mining area of Abbadia San Salvatore (Mt. Amiata, central Italy). The purpose was to discern the Hg spatial distribution, identify the most polluted areas, and evaluate the impacts of dry and wet deposition on mosses. The exposed moss bags consisted of a mixture of Sphagnum fuscum and Sphagnum tenellum from an external uncontaminated area. In each site, two different types of moss bags, one uncovered (to account for the wet + dry deposition) and one covered (to evaluate the dry deposition), were exposed. The behavior of arsenic (As) and antimony (Sb) in the mosses was investigated to assess the potential relationship with Hg. GEM (Gaseous Elemental Mercury) concentrations were also measured at the same sites where the mosses were exposed, although only as a reference in the initial stages of biomonitoring. The results revealed that the main Hg emissions sources were associated with the former mining area of Abbadia San Salvatore, in agreement with the measured GEM concentrations, while arsenic and antimony were related to soil enriched in As-Sb waste material. The three elements registered higher concentrations in uncovered mosses with respect to the covered ones, i.e., wet deposition was the key factor for their accumulation on the uncovered mosses, while dry deposition was especially important for the covered samples in the mining area. Hg was accumulated in the mosses via GEM adsorption, uptake of particulate Hg, and precipitation via raindrops/snowfall, with almost no loss and without post-deposition volatilization. The results testified that the chosen biomonitoring technique was an extremely useful tool for understanding Hg transport and fate in a contaminated area.

Soils in the Black Soil Zone of northeast China are experiencing pollution from polycyclic aromatic hydrocarbons (PAHs) as the region undergoes urbanization. In this study, 119 topsoil samples were collected from the black soil agricultural area in Jilin Province, China to investigate the characteristics and spatial distribution of 16 PAHs. The total concentration of ∑16 PAHs in the agricultural soils ranged from 2.546 to 33.993 mg/kg, with a mean value of 9.99 mg/kg. Positive matrix factorization (PMF) analysis indicated that vehicle exhaust and oil combustion were identified as the main contributors to traffic- and energy-related pollution. The inherited lifetime carcinogenicity risk (ILCR) was found to be relatively low, indicating a low potential risk in this region, with adults (1.34 × 10^-5) exhibiting a higher risk than adolescents (8.62 × 10^-6) and children (7.49 × 10^-6). The highest values for intake, skin contact, and inhalation routes were observed in the adult group, suggesting that adult residents in certain areas may be at increased health risk. This study enhances our understanding of the pathways through which PAHs enter agricultural soils in Jilin Province and provides insights that could aid in addressing PAH pollution in black soil, ultimately contributing to more sustainable agricultural practices in the region.