Risk assessment of antimony-arsenic contaminated soil remediated using zero-valent iron at different pH values combined with freeze-thaw cycles.

Soil in mining wastelands is seriously polluted with heavy metals. Zero-valent iron (ZVI) is widely used for remediation of heavy metal-polluted soil because of its excellent adsorption properties; however, the remediation process is affected by complex environmental conditions, such as acid rain and freeze-thaw cycles. In this study, the effects of different pH values and freeze-thaw cycles on remediation of antimony (Sb)- and arsenic (As)-contaminated soil by ZVI were investigated in laboratory simulation experiments. The stability and potential human health risks associated with the remediated soil were evaluated. The results showed that ZVI has a significant stabilizing effect on Sb and As in both acidic and alkaline soils contaminated with dual levels of Sb and As, and the freeze-thaw process in different pH value solution systems further enhances the ability of ZVI to stabilize Sb and As, especially in acidic soils. However, it should be noted that apart from the pH=1.0 solution environment, ZVI's ability to stabilize As is attenuated under other circumstances, potentially leading to leaching of its unstable form and thereby increasing contamination risks. This indicates that the F1 (2% ZVI+pH=1 solution+freeze-thaw cycle) processing exhibits superior effectiveness. After F1 treatment, the bioavailability of Sb and As in both soils also significantly decreased during the gastric and intestinal stages (about 60.00%), the non-carcinogenic and carcinogenic risks of Sb and As in alkaline soils are eliminated for children and adults, with a decrease ranging from 60.00% to 70.00%, while in acidic soil, the non-carcinogenic and carcinogenic risks of As to adults and children is acceptable, but Sb still poses non-carcinogenic risks to children, despite reductions of about 65.00%. These findings demonstrate that soil pH is a crucial factor influencing the efficacy of ZVI in stabilizing Sb and As contaminants during freeze-thaw cycles. This provides a solid theoretical foundation for utilizing ZVI in the remediation of Sb- and As-contaminated soils, emphasizing the significance of considering both pH levels and freeze-thaw conditions to ensure effective and safe treatment.

Speciation analysis of arsenic in honey using HPLC-ICP-MS and health risk assessment of water-soluble arsenic.

It is well known that arsenic is one of the most toxic elements. However, measuring total arsenic content is not enough, as it occurs in various forms that vary in toxicity. Since honey can be used as a bioindicator of environmental pollution, in the present study the concentration of arsenic and its species (As(III), As(V), DMA, MMA and AsB) was determined in honey samples from mostly Poland and Ukraine using HPLC-ICP-MS hyphenated technique. The accuracy of proposed methods of sample preparation and analysis was validated by analyzing certified reference materials. Arsenic concentration in honey samples ranged from 0.12 to 13 µg kg-1, with mean value of 2.3 µg kg-1. Inorganic arsenic forms, which are more toxic, dominated in honey samples, with Polish honey having the biggest mean percentage of inorganic arsenic species, and Ukrainian honey having the lowest. Furthermore, health risks resulting from the consumption of arsenic via honey were assessed. All Target Hazard Quotient (THQ) values, for total water-soluble arsenic and for each form, were below 1, and all Carcinogenic Risk (CR) values were below 10-4, which indicates no potential health risks associated with consumption of arsenic via honey at average or recommended levels.

Assessment of some toxic elements (Co, Cr, Mn, Se, and As) in muscle, offal, hair, and blood of camels (Camelus dromedaries) and their risk assessment.

Background: Camel meat tainted with heavy metals or trace elements may pose a health risk to consumers. Heavy metal contamination poses a severe danger due to both their toxicity and bioaccumulation in the food chain. Aim: To estimate the residual levels of heavy metals (Co, Cr, Mn, Se, and As) in muscle, liver, kidney, hair, and serum of three camel breeds (Magaheem, Maghateer, and Wadha) collected from Al-Omran abattoir, Al-Ahsa, Saudi Arabia. Methods: A total of 225 tissue samples (muscles, liver, kidney, serum, and hair) were taken and analyzed using an Atomic Absorption Spectrophotometer. Health risk assessment was assessed using the guidelines set by the US Environmental Protection Agency. Results: Camel breed significantly (p < 0.05) influences Co, Cr, Mn, and Se accumulation and distribution in organs and muscle; however, arsenic accumulation was not significantly affected (p < 0.05) by camel breeds. The highest values of Co, Cr, Se, and Mn in all examined samples were detected in the liver samples of Maghateer and Magaheem breeds. Furthermore, significant strong positive correlation between serum and liver cobalt, chromium, manganese, and arsenic. The estimated daily intake owing to camel meat consumption was less than the tolerated daily intake. Conclusion: Heavy metals were distributed among different breeds of camel. Trace elements (Pb and Cd) in meat and offal were below the international maximum permissible limit. The correlation between samples reflects the role of hair as a good tool for the identification of heavy metal pollution.

Integrated assessment of potentially toxic elements in soil of the Kangdian metallogenic province: A two-point machine learning approach.

The accumulation of potentially toxic elements in soil poses significant risks to ecosystems and human well-being due to their inherent toxicity, widespread presence, and persistence. The Kangdian metallogenic province, famous for its iron-copper deposits, faces soil pollution challenges due to various potentially toxic elements. This study explored a comprehensive approach that combinescombines the spatial prediction by the two-point machine learning method and ecological-health risk assessment to quantitatively assess the comprehensive potential ecological risk index (PERI), the total hazard index (THI) and the total carcinogenic risk (TCR). The proportions of copper (Cu), cadmium (Cd), manganese (Mn), lead (Pb), zinc (Zn), and arsenic (As) concentrations exceeding the risk screening values (RSVs) were 15.03%, 5.1%, 3.72%, 1.24%, 1.1%, and 0.13%, respectively, across the 725 collected samples. Spatial prediction revealed elevated levels of As, Cd, Cu, Pb, Zn, mercury (Hg), and Mn near the mining sites. Potentially toxic elements exert a slight impact on soil, some regions exhibit moderate to significant ecological risk, particularly in the southwest. Children face higher non-carcinogenic and carcinogenic health risks compared to adults. Mercury poses the highest ecological risk, while chromium (Cr) poses the greatest health hazard for all populations. Oral ingestion represents the highest non-oncogenic and oncogenic risks in all age groups. Adults faced acceptable non-carcinogenic risks. Children in the southwest region confront higher health risks, both non-carcinogenic and carcinogenic, from mining activities. Urgent measures are vital to mitigate Hg and Cr contamination while promoting handwashing practices is essential to minimize health risks.

Human health risks of heavy metal(loid)s mediated through crop ingestion in a coal mining area in Eastern China.

The heavy metal(loid)s (HMs) in soils can be accumulated by crops grown, which is accompanied by crop ingestion into the human body and then causes harm to human health. Hence, the health risks posed by HMs in three crops for different populations were assessed using Health risk assessment (HRA) model coupled with Monte Carlo simulation. Results revealed that Zn had the highest concentration among three crops; while Ni was the main polluting element in maize and soybean, and As in rice. Non-carcinogenic risk for all populations through rice ingestion was at an "unacceptable" level, and teenagers suffered higher risk than adults and children. All populations through ingestion of three crops might suffer Carcinogenic risk, with the similar order of Total carcinogenic risk (TCR): TCRAdults > TCRTeenagers > TCRChildren. As and Ni were identified as priority control HMs in this study area due to their high contribution rates to health risks. According to the HRA results, the human health risk was associated with crop varieties, HM species, and age groups. Our findings suggest that only limiting the Maximum allowable intake rate is not sufficient to prevent health risks caused by crop HMs, thus more risk precautions are needed.

Public health assessment of Kenyan ASGM communities using multi-element biomonitoring, dietary and environmental evaluation.

The Kakamega gold belt's natural geological enrichment and artisanal and small-scale gold mining (ASGM) have resulted in food and environmental pollution, human exposure, and subsequent risks to health. This study aimed to characterise exposure pathways and risks among ASGM communities. Human hair, nails, urine, water, and staple food crops were collected and analysed from 144 ASGM miners and 25 people from the ASGM associated communities. Exposure to PHEs was predominantly via drinking water from mine shafts, springs and shallow-wells (for As>Pb>Cr>Al), with up to 366 µg L-1 arsenic measured in shaft waters consumed by miners. Additional exposure was via consumption of locally grown crops (for As>Ni>Pb>Cr>Cd>Hg>Al) besides inhalation of Hg vapour and dust, and direct dermal contact with Hg. Urinary elemental concentrations for both ASGM workers and wider ASGM communities were in nearly all cases above bioequivalents and reference upper thresholds for As, Cr, Hg, Ni, Pb and Sb, with median concentrations of 12.3, 0.4, 1.6, 5.1, 0.7 and 0.15 µg L-1, respectively. Urinary As concentrations showed a strong positive correlation (0.958) with As in drinking water. This study highlighted the importance of a multidisciplinary approach in integrating environmental, dietary, and public health investigations to better characterise the hazards and risks associated with ASGM and better understand the trade-offs associated with ASGM activities relating to public health and environmental sustainability. Further research is crucial, and study results have been shared with Public Health and Environmental authorities to inform mitigation efforts.

Distribution, ecological, and health risk assessment of trace elements in the surface seawater along the littoral of Tangier Bay (Southwestern Mediterranean Sea).

In the current study, an environmental assessment of surface seawater in Tangier Bay was conducted by analyzing physicochemical parameters and trace elements, such as As, Cr, Zn, Cd, Pb, and Cu. The results showed mean concentrations (µg/l) of 22.50 for As, 0.46 for Cr, 8.57 for Zn, 15.41 for Cd, 0.23 for Pb, and 1.83 for Cu. While most trace elements met the guidelines, elevated levels of Cd raised concerns about long-term exposure. Pollution indices, including the contamination factor, degree of contamination, and water quality index, indicate the impact of human activities, dividing sites into arsenic-cadmium contamination, wastewater influence, and low pollution levels. Statistical methods, such as ANOVA, revealed no significant differences in trace element levels across the bay. PCA and HCA revealed that Cr, Cu, and Zn originated from common anthropogenic sources, whereas Pb and Cd originated from distinct sources. As indicates that natural geological processes influence its origin.

Health risk assessment of heavy metal toxicity in the aquatic environment of the Persian Gulf.

This study aims to explore the potential health risks linked to four heavy metals/metalloids (Pb, Cd, As, Hg) present in four commercially important fish species (Scombromorus commerson, Pseudorhombus elevatus, Thunnus tonggol and Otolithes ruber) in the Persian Gulf. Metals in fish muscle tissue were analyzed via ICP-MS. The analysis revealed that Scombromorus commerson (except for Pb) and Thunnus tonggol (except for As) exhibited the highest and lowest contamination levels, respectively. The Hazard Index findings highlighted arsenic and mercury as the most hazardous elements. However, the Target Hazard Quotient values for each metal and fish species remained within safe thresholds. The highest and lowest Total Carcinogenic Risk was concerning Pseudorhombus elevates (As: 7.41-E05), and Thunnus thonggol (Pb: 3.21-E07), respectively. TCR analysis suggests that the cancer risk of studied metals was below the negligible level (TCR < 10-6) or within the acceptable level (10-6 < TCR < 10-4), potentially not posing carcinogenic risks through extended consumption.

Air quality, metal(loid) sources identification and environmental assessment using (bio)monitoring in the former mining district of Salsigne (Orbiel valley, France).

The former mining district of Salsigne is situated in the Orbiel valley. Until the 20th century, it was the first gold mine in Europe and the first arsenic mine in the world. Rehabilitation has been performed during the 20 years that followed closure of the mines and factories, which led to the accumulation of storage of several million tons of waste in this valley. Nevertheless, a detailed description of the air quality of this area is still missing. The goal of the present study is to evaluate atmospheric contamination in the valley and identify the potential sources of this contamination. Active monitors (particulate matter samplers) and passive bioindicators (Tillandsia usneoides) were placed in strategic sites including remote areas. Over the year 2022, we assessed the air quality using microscopic and spectroscopic techniques, as well as environmental risk indicators to report the level of contamination. Results indicate that the overall air quality in the valley is good with PM10 levels in accordance with EU standards. Elemental concentrations in the exposed plants were lower than reported in the literature. Among the different sites studied, Nartau and La Combe du Saut, corresponding to waste storage and former mining industry sites, were the most affected. Chronic exposure over 1 year was highlighted for Fe, Ni, Cu, Pb, Sb and As. Pollution Load Index and Enrichment Factors, which provided valuable information to assess the environmental condition of the valley's air, suggested that dust and resuspension of anthropogenic materials were the principle sources for most of the elements. Finally, this study also highlights that using T. usneoides could be a convenient approach for biomonitoring of metal (loid)-rich particles in the atmosphere within a former mining area, for at least one year. These results in turn allow to better understand the effects of chronic exposure on the ecosystem.

Essential and non-essential element concentrations in human milk samples and the assessment of infants' exposure.

As the data concerning element concentrations in human milk (HM) samples and their intake by infants are lacking in Poland, the present study aimed to explore this issue. The material consisted of HM samples obtained from 30 exclusively breastfeeding mothers during 4-6 weeks postpartum. Additionally, to identify the factors that may potentially affect HM composition, information regarding maternal data (anthropometry, body composition, and diet) was also collected. Maternal diet was assessed with two methods-a food frequency questionnaire and 3-day dietary records. In total, 18 essential and non-essential elements were determined. For the elements analysis, we used inductively coupled plasma quadrupole mass spectrometry. Most of the elements (n = 11, 61%) were detected in all HM samples. In all HM samples tin concentration was higher (5.67 ± 2.39 µg/L) than the usual range reported by the World Health Organization (~ 1.0 µg/L). HM cadmium content was positively associated with maternal salty snacks intake (r = 0.502, p = 0.005), arsenic with whole-grain products intake (r = 0.37, p = 0.043), and mercury concentration with fruits and seeds/nuts consumption (r = 0.424, p = 0.042 and r = 0.378, p = 0.039, respectively). Higher HM lead concentration was predicted by maternal age (95% CI [0.94-0.97]), intake of fish (95% CI [1.01-1.03]), and vegetables (95% CI [1.02-1.06]). The highest infants' intake was observed for copper (35.24 ± 12.48) and the lowest for arsenic (0.076 ± 0.102). Infants' exposure to lead was associated with maternal frequency consumption of canned fish (p = 0.0045). There is a need to perform further research on this topic to maximize the benefits of breastfeeding by minimizing maternal and infant exposure to potentially toxic elements.

Essential and Toxic Elements in Infant Cereal in Brazil: Exposure Risk Assessment.

Infant cereals, one of the first solid foods introduced to infants, have been reported to pose risks to human health because they contain toxic elements and an excess of essential elements. The objective of this study was to assess the cancer and non-cancer risk of exposure to essential and toxic elements in infant cereal in Brazil. In our analyses, we included data from 18 samples of infant cereals made from different raw materials and estimated the incremental lifetime cancer risks and non-cancer hazard quotients (HQs) for their consumption. Rice cereal is particularly concerning because it is immensely popular and usually contains high levels of inorganic arsenic. In addition to arsenic, we assessed aluminum, boron, barium, cadmium, chromium, copper, lead, manganese, nickel, selenium, silver, strontium, and zinc. The cancer risk was highest for rice cereal, which was also found to have an HQ > 1 for most of the tested elements. Inorganic As was the element associated with the highest cancer risk in infant cereal. All of the infant cereals included in this research contained at least one element with an HQ > 1. The essential and non-essential elements that presented HQ > 1 more frequently were zinc and cadmium, respectively. The cancer and non-cancer risks could potentially be decreased by reducing the amount of toxic and essential elements (when in excess), and public policies could have a positive influence on risk management in this complex scenario.

Survey of arsenic content in edible seaweeds and their health risk assessment.

Since humans are especially sensitive to arsenic exposure, predominantly through diet, a strict control of the most widely consumed seaweeds is mandatory. Total arsenic contents and arsenic species in twenty-five different seaweeds from five different origins were studied. Seaweeds selected, included Phaeophyta (brown seaweed), Chlorophyta (green seaweed) and Rhodophyta (red seaweed) genera. The highest arsenic content appears in the Phaeophyta seaweed in the range from 11 to 162 mg kg-1 dried weight. Arsenosugars were found to be the predominant species of arsenic in most seaweeds, being up to 99.7% of total arsenic in some samples. The arsenic dietary intakes for seaweeds studied were assessed and the Target Hazard Quotients (THQ) and the Target Cancer Risk (TCR) were calculated, taking into account inorganic arsenic contents (iAs). iAs species in seaweeds showed low risk of arsenic intake except for Hizikia fusiforme samples.

Applications of engineered biochar in remediation of heavy metal(loid)s pollution from wastewater: Current perspectives toward sustainable development goals.

Environmental pollution of heavy metal(loid)s (HMs) caused adverse impacts, has become one of the emerging concerns and challenges worldwide. Metal(loid)s can pose significant threats to living organisms even when present in trace levels within environmental matrices. Extended exposure to these substances can lead to adverse health consequences in humans. Removing HM-contaminated water and moving toward sustainable development goals (SDGs) is critical. In this mission, biochar has recently gained attention in the environmental sector as a green and alternative material for wastewater removal. This work provides a comprehensive analysis of the remediation of typical HMs by biochars, associated with an understanding of remediation mechanisms, and gives practical solutions for ecologically sustainable. Applying engineered biochar in various fields, especially with nanoscale biochar-aided wastewater treatment approaches, can eliminate hazardous metal(loid) contaminants, highlighting an environmentally friendly and low-cost method. Surface modification of engineered biochar with nanomaterials is a potential strategy that positively influences its sorption capacity to remove contaminants. The research findings highlighted the biochars' ability to adsorb HM ions based on increased specific surface area (SSA), heightened porosity, and forming inner-sphere complexes with oxygen-rich groups. Utilizing biochar modification emerged as a viable approach for addressing lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), and chromium (Cr) pollution in aqueous environments. Most biochars investigated demonstrated a removal efficiency >90 % (Cd, As, Hg) and can reach an impressive 99 % (Pb and Cr). Furthermore, biochar and advanced engineered applications are also considered alternative solutions based on the circular economy.

Immobilisation remediation of arsenic-contaminated soils with promising CaAl-layered double hydroxide and bioavailability, bioaccessibility, and speciation-based health risk assessment.

Arsenic (As)-contaminated soil poses great health risk to human mostly through inadvertent oral exposure. We investigated CaAl-layered double hydroxide (CaAl-LDH), a promising immobilising agent, for the remediation of As-contaminated Chinese soils. The effects on specific soil properties and As fractionation were analyzed, and changes in the health risk of soil As were accurately assessed by means of advanced in vivo mice model and in vitro PBET-SHIME model. Results showed that the application of CaAl-LDH significantly increased soil pH and concentration of Fe and Al oxides, and effectively converted active As fractions into the most stable residual fraction, guaranteeing long-term remediation stability. Based on in vivo test, As relative bioavailability was significantly reduced by 37.75%. Based on in vitro test, As bioaccessibility in small intestinal and colon phases was significantly reduced by 25.65% and 28.57%, respectively. Furthermore, As metabolism (reduction and methylation) by the gut microbiota inhabiting colon was clearly observed. After immobilisation with CaAl-LDH, the concentration of bioaccessible As(Ⅴ) in the colon fluid was significantly reduced by 61.91%, and organic As (least toxic MMA(V) and DMA(V)) became the main species, which further reduced the health risk of soil As. In summary, CaAl-LDH proved to be a feasible option for immobilisation remediation of As-contaminated soils, and considerable progress was made in relevant health risk assessment.

Air, land, and water pollutants and public health expenditures: Empirical data from selected EU countries in the transport sector.

The increase in economic activity, particularly in transport, leads to a significant increase in emissions of pollutants, such as ammonia, arsenic and cadmium, at the European Union (EU) level. This can seriously impact human health and, consequently, public health spending. Based on data from 15 European Union countries from 1992 to 2020, a panel co-integration approach is used to study these pollutants' short- and long-term co-movements and per capita health expenditure. The results show a long-term relationship between ammonia, arsenic and cadmium emissions and per capita health spending, as they are panel-cointegrated. Ammonia and cadmium emissions exert a statistically significant positive effect on health expenditure in the short run, and arsenic emissions have a statistically significant positive impact in the long run. The forecast assessment of reductions in health spending resulting from policies to reduce emissions of air, land and water pollutants, such as ammonia, arsenic and cadmium, from the transport sector supports investments in its policies that reduce pressure on health spending. The reduction in annual healthcare expenditure is greater when these reductions are made sooner and more severely. Indeed, varying the reduction in emissions for each pollutant by 10% and 100%, respectively, from the first year for all countries over a 3-year period results in an average annual reduction in health spending of 2.05% and 51.02%, respectively. However, if we wait until the third year, the annual reduction is only 0.77% and 17.63% respectively.

Assessment of the stabilization effect of ferrous sulfate for arsenic-contaminated soils based on chemical extraction methods and in vitro methods: Methodological differences and linkages.

Stabilization of arsenic-contaminated soils with ferrous sulfate has been reported in many studies, but there are few stabilization effects assessments simultaneously combined chemical extraction methods and in vitro methods, and further explored the corresponding alternative relationships. In this study, ferrous sulfate was added at FeAs molar ratio of 0, 5, 10 and 20 to stabilize As in 10 As spiked soils. Stabilization effects were assessed by 6 chemical extraction methods (toxicity characteristic leaching procedures (TCLP), HCl, diethylenetriamine pentaacetic acid (DTPA), CaCl2, CH3COONH4, (NH4)2SO4), and 4 in vitro methods (physiologically based extraction test (PBET), in vitro gastrointestinal method (IVG), Solubility Bioaccessibility Research Consortium (SBRC) method, and the Unified Bioaccessibility Research Group of Europe method (UBM)). The results showed that the HCl method provides the most conservative assessment results in non-calcareous soils, and in alkaline calcareous soils, (NH4)2SO4 method provides a more conservative assessment. In vitro methods provided significantly higher As concentrations than chemical extraction methods. The components of the simulated digestion solution as well as the parameters may have contributed to this result. The small intestinal phase of PBET and SBRC method produced the highest and lowest ranges of As concentrations, and in the range of 127-462 mg/kg and 68-222 mg/kg when the FeAs molar ratio was 5. So the small intestinal phase of PBET method may provide the most conservative assessment results, while the same phase of SBRC may underestimate the human health risks of As in stabilized soil by 51 %(at a FeAs molar ratio of 5). Spearman correlation analysis indicated that the small intestinal phase of PBET method correlated best with HCl method (correlation coefficient: 0.71). This study provides ideas for the assessment of stabilization efforts to ensure that stabilization meets ecological needs while also being less harmful to humans.

Characterization and childhood exposure assessment of toxic heavy metals in household dust under true living conditions from 10 China cities.

Health hazards caused by metal exposure in household dust are concerning environmental health problems. Exposure to toxic metals in household dust imposes unclear but solid health risks, especially for children. In this multicenter cross-sectional study, a total of 250 household dust samples were collected from ten stratified cities in China (Panjin, Shijiazhuang, Qingdao, Lanzhou, Luoyang, Ningbo, Xi'an, Wuxi, Mianyang, Shenzhen) between April 2018 and March 2019. Questionnaire was conducted to gather information on individuals' living environment and health status in real-life situations. Multivariate logistic regression and principal component analysis were conducted to identify risk factors and determine the sources of metals in household dust. The median concentration of five metals in household dust from 10 cities ranged from 0.03 to 73.18 µg/g. Among the five heavy metals, only chromium in household dust of Mianyang was observed significantly both higher in the cold season and from the downwind households. Mercury, cadmium, and chromium were higher in the third-tier cities, with levels of 0.08, 0.30 and 97.28 µg/g, respectively. There were two sources with a contribution rate of 38.3 % and 25.8 %, respectively. Potential risk factors for increased metal concentration include long residence time, close to the motorway, decoration within five years, and purchase of new furniture within one year. Under both moderate and high exposure scenarios, chromium showed the highest level of exposure with 6.77 × 10-4 and 2.28 × 10-3 mg·kg-1·d-1, and arsenic imposed the highest lifetime carcinogenic risk at 1.67 × 10-4 and 3.17 × 10-4, respectively. The finding highlighted the priority to minimize childhood exposure of arsenic from household dust.

Iron-lanthanum supported on graphite sheets for As(III) removal from aqueous solution: kinetics, thermodynamic and ecotoxicity assessment.

Graphene-based material is widely used to remove arsenic from water due to its layered structure with high surface area. Here, we have successfully synthesized Fe-La bimetallic modified graphite sheet materials to more efficiently remove As(III) from aqueous solution. The results showed that Fe-La-graphite sheets (FL-graphite sheets) have a larger specific surface area (194.28 m2·g-1) than graphite sheets (2.80 m2·g-1). The adsorption capacity of FL-graphite sheets for As(III) was 51.69 mg·g-1, which was higher than that of graphite sheets (21.91 mg·g-1), La-graphite sheets (26.06 mg·g-1), and Fe-graphite sheets (40.26 mg·g-1). The FL-graphite sheets conformed to the Freundlich and Dubinin-Radushkevich isotherm, and the maximum adsorption capacity was 53.62 mg·g-1. The removal process obeys intra-particle diffusion and pore diffusion for As(III). The results of batch adsorption experiments and characterization analyses demonstrated that oxidation, ligand exchange, and inner sphere complexation mechanisms involved in the adsorption of FL-graphite sheets to As(III) in comparison with graphite sheets. In addition, electrostatic attraction mechanism was found vital in the adsorption. Ecotoxicity assessment revealed that FL-graphite sheets have little influence on rice germination and growth, but reduced the toxicity of As(III) to rice. Therefore, the FL-graphite sheets have good practical application value in purifying As(III) polluted water with litter ecotoxicity.

[Health Risk Assessment for an Arsenic-contaminated Site Based on Monte Carlo Simulation and Parameters Optimization].

Risk assessment is a critical part of risk management for contaminated sites. However， in the specific management practice of As-contaminated sites， it is difficult to obtain realistic health risks for contaminated sites based on the total amount of pollutants and determined values of the model， thus preventing the control requirements of later remediation to be met. An increasing number of studies have recently been conducting risk assessments by considering bioavailability， modification parameters， and combined probabilistic models. To improve the accuracy of risk assessment results， taking a large As-contaminated site as a case， 432 sampling sites were set up and collected at different depths to analyze the level and distribution characteristics of As pollution， and probabilistic risk assessment was conducted with the modification of model parameters through literature research and Monte Carlo simulation. Then， the impact of traditional methods and probabilistic methods on health risk assessment was explored in comparison. The results indicated that ω（As） in the top soil of the study area ranged from 2.70-97.0 mg·kg-1， with a spatial variation coefficient of 0.61 and weaker spatial continuity. The carcinogenic risk and hazard index obtained by the traditional risk assessment method were 2.12E-4 and 8.36， respectively， which obviously overestimated the actual risk level and were not conductive to the refined management of As-contaminated sites. Combined with modification of model parameters and probabilistic risk assessment， the non-carcinogenic risk for adults and children was found to be at an acceptable level， and the carcinogenic risk was reduced by nearly an order of magnitude compared to that in the conventional method. Considering the relative biological effectiveness （RBA） of As， the 95% quantile of the total carcinogenic risk was 1.24E-5， a reduction of up to 36.41% compared to the uncorrected corresponding risk value of 1.95E-5. The carcinogenic risk of soil As for adults and children in the study area exceeded acceptable risk levels 1E-6， with oral ingestion of soil being the primary route of exposure. In addition， the results of the sensitivity analysis of the parameters showed that As concentration， daily oral ingestion rate of soils， and exposure duration of children had relatively larger effects for health risks. This work will provide a methodological and theoretical basis for achieving accurate risk assessment of As-contaminated sites and provide concepts for refined risk management.

Contamination and health risk assessment of heavy metals in soil surrounding an electroplating factory in JiaXing, China.

A total of 30 samples from the downwind direction of a certain electroplating company in Jiaxing were collected in layers to analyze their heavy metal content. The soil risk assessment was conducted from the perspective of ecological and human health risks using the ground accumulation index method and human health risk assessment method. The results showed that in all samples, cadmium and arsenic far exceeded the soil background values, with an average exceeding multiple of 14.31 and 64.42, respectively, and a exceeding rate of 100%. After evaluation by the ground accumulation index, among these six heavy metals, arsenic and cadmium belong to extremely serious pollution levels. The human health risk assessment of electroplating plants found that in the exposure risk assessment, the ingestion value was much greater than the harm caused by breathing and skin, and the maximum exposure damage value of arsenic to children and adults was 4.17 × 10-3, among the carcinogenic risks, the risk brought by consumption is much greater than the respiratory and skin carcinogenic risk index, with the highest value score of 3.37 for cadmium, arsenic, and zinc carcinogenic risks 3.37 × 10-6, 2.42 × 10-3, 1.10 × 10-4.