Implementation of long-term assessment of human health risk for metal contaminated groundwater: A coupled chemical mass balance and hydrodynamics model.

Assessing human health risk using spatiotemporal migration and geochemical evolution concurrently in an area where the groundwater is contaminated with heavy metals can provide more instructive information to protect specific potential negative impacts on human health. In this research, we established a model of long-term assessment of human health risk for metal contaminated groundwater by coupling two models: the geochemical (based on the law of chemical mass balance) model and the hydrodynamics module. The hydrodynamics module is used to initially identify the total temporal concentration of various elements, and the chemical mass balance module is used to gain the concentration and ionic activity of various toxic elements according to the range of environmental pH. Effective concentrations calculated using activity weight (based on speciation and ionic activity) were introduced into the formula for risk analysis. The results of the study show that, with the exploitation and recharge of groundwater, the non-carcinogenic and carcinogenic health risks cannot be reduced to acceptable levels until 18 and 22 years, respectively. The calculated risk values of using the coupling model are lower than that of statistics or single hydrokinetics. The sensitivity analysis results show that this model is reliable. The recharge, pH and the permeability coefficient are defined as the most sensitive factors.

Exploring human health risk assessment based on the screening of primary targeted metal and chemical balance simulation of ionic speciation in an industrial area, China.

A comprehensive human health risk assessment methodology based on major hazard element screening and morphological evolution simulation is proposed. The primary targeted metal (PTM) screened by classical health risk assessment was introduced into chemical balance simulation to obtain speciation distribution and corresponding risk. According to the results of risk assessment of morphological evolution of primary targeted metal (PTM), a potential methodology for the remediation is proposed, which could reduce the risk level efficiently and quickly by changing the pH of soil environment with additional acid and alkali substances. A case study was performed in a dye factory in Suzhou city, Jiangsu Province, China. The results of classical health risk assessment showed that the regional health risk index for children exceeded tolerance value of 1, in which Cr accounted for high risk level of 61%. Chemical balance simulation results showed that CrO42- and CaCrO4 had the highest risk index, and the change of pH value would affect the proportion of CrO42- and CaCrO4 in Cr6+ ionic speciation, which may indirectly change the risk level. It is recommended to adjust the pH of the soil environment to quickly reduce regional human health risk. This study will provide a theoretical basis for public health protection and site restoration management.

Three-dimensional heterogeneous Electro-Fenton system with a novel catalytic particle electrode for Bisphenol A removal.

Herein, a novel three-dimensional (3D) heterogeneous Electro-Fenton (EF) system with improved gas diffusion electrode (GDE) as cathode and magnetic nitrogen doped/reduced graphene oxide (Fe3O4/N-rGO) as catalytic particle electrodes (CPEs) was built for Bisphenol A (BPA) removal. The Fe3O4/N-rGO served as both particle electrodes and heterogeneous catalyst. The study concluded that BPA could be effectively removed via this hybrid system. The synergistic effect between the 3D electrode and EF system was discussed by comparing the performance of different functional particle electrodes. The 3D electrode system exhibited a larger specific surface area electrode, which improved the mass transfer of pollutants to electrode, and also accelerated the regeneration of FeⅡ due to faster electron transfer, thereby enhancing the efficiency of EF catalysis. The EF process promotes the regeneration rate of particle electrodes and thus accelerates the 3D electrode reaction course. The parameters affecting degradation behavior of BPA were optimized. As a result, optimal removal rate of BPA and TOC was 93% and 60.5%, respectively within 90 min. The CPEs showed high catalytic performance (86.5% for BPA and 50.3% for TOC) and low catalyst loss (less than 9.5%) after 5 cycles, indicating its excellent stability and reusability. The possible mechanism of 3D heterogeneous EF was investigated by comparing the catalytic activity and •OH production capacity of homogeneous EF and Fenton-like. Built on the analysis of intermediates, a possible decomposition pathway of BPA was proposed.

Implementing chemical mass balance model and vulnerability the theories to realize the comprehensive evaluation in an abandoned battery plant.

In China groundwater contamination has become a serious problem. The assessment and remediation of contaminated sites are greatly important. Moreover, only few studies deal with the influence of metal speciation on human health risk assessment. This paper proposed a comprehensive assessment methodology combined human health risk assessment and groundwater vulnerability assessment for contaminated area, exploring a more reasonable model for the Cd morphology simulation, and utilizing accurate method to calculate the average daily dose by the weight analysis. PHREEQC and Visual MINTEQ were applied and compared to the morphology simulation, the modified of average daily dose and non-modified of average daily dose was investigated, carcinogenic and non-carcinogenic risks were calculated subsequently. The groundwater vulnerability was assessed by the DRASTIC model, the DRASTIC index as the indicator of groundwater vulnerability. The morphology simulation results showed 20 and 13 metal species which were simulated by PHREEQC and Visual MINTEQ, respectively. Cd2+ and CdCl+ were the primary species of Cd in groundwater. The modified average daily dose showed less than the average daily dose in results. The carcinogenic risks showed the species of Cd2+ and CdCl+ were simulated by PHREEQC which were harmful to human health. The DRASTIC index was ranged from 109 to 134 in the studied area, which showed that the area was susceptible to pollution. This method provided a more effective risk assessment model and supplied a fundamental advice for government policy-making and site remediation.