Yimei Zhang

Planning of water resources management and pollution control for Heshui River watershed, China: A full credibility-constrained programming approach

A key issue facing integrated water resources management and water pollution control is to address the vague parametric information. A full credibility-based chance-constrained programming (FCCP) method is thus developed by introducing the new concept of credibility into the modeling framework. FCCP can deal with fuzzy parameters appearing concurrently in the objective and both sides of the constraints of the model, but also provide a credibility level indicating how much confidence one can believe the optimal modeling solutions. The method is applied to Heshui River watershed in the south-central China for demonstration. Results from the case study showed that groundwater would make up for the water shortage in terms of the shrinking surface water and rising water demand, and the optimized total pumpage of groundwater from both alluvial and karst aquifers would exceed 90% of its maximum allowable levels when credibility level is higher than or equal to 0.9. It is also indicated that an increase in credibility level would induce a reduction in cost for surface water acquisition, a rise in cost from groundwater withdrawal, and negligible variation in cost for water pollution control.

Graphene oxide coated quartz sand as a high performance adsorption material in the application of water treatment

In order to increase the water treatment performance, the quartz sand filter medium was improved by surface modification using a 3-aminopropyltriethoxy silane coupling agent (KH550), then GO was grafted to the surface of the sand though the chemical reaction between the functional groups. The interfacial interactions between the quartz sand surface and GO was studied. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses showed that the GO binds strongly to the quartz sand surface. Scanning electronic microscopy (SEM) observation showed that a thin GO layer was formed on the surface of the modified quartz sand. The modified sand was used as a sorbent for the removal of turbidity, organic matter, Cd(II) and Pb(II) ions from large volumes of aqueous solutions. The results indicate that the GO plays an important role in improving the water treatment performance of a quartz sand filter.

Characterization of monochlorobenzene contamination in soils using geostatistical interpolation and 3D visualization for agrochemical industrial sites in southeast China

Abstract Persistent organic pollutants (POPs) originating from agrochemical industries have become an urgent environmental problem worldwide. Ordinary kriging, as an optimal geostatistical interpolation technique, has been proved to be sufficiently robust for estimating values with finite sampled data in most of the cases. In this study, ordinary kriging interpolation integrate with 3D visualization methods is applied to characterize the monochlorobenzene contaminated soil for an agrochemical industrial site located in Jiangsu province. Based on 944 soil samples collected by Geoprobe 540MT and monitored by SGS environmental monitoring services, 3D visualization in terms of the spatial distribution of pollutants in potentially contaminated soil, the extent and severity of the pollution levels in different layers, high concentration levels and isolines of monochlorobenzene concentrations in this area are provided. From the obtained results, more information taking into account the spatial heterogeneity of soil area will be helpful for decision makers to develop and implement the soil remediation strategy in the future.

A semiparametric statistical approach for forecasting SO2 and NOx concentrations

This study develops a new semiparametric statistical approach for urban air quality forecasting. Compared to conventional approaches, the semiparametric approach allows the model users to benefit from the positive aspects and alleviate the negative ones of parametric and nonparametric approaches. Two advantages of the approach lie in (1) the interpretation of the data set being easily decoded and used by the model and (2) its capability in dependence on prior assumption. To illustrate the performance of the proposed approach, three semiparametric regression models (i.e., linear-, quadratic-, and interactive-based semiparametric regression) are applied to an air quality forecasting problem in the city of Xiamen, China, and satisfactory training and prediction performance are obtained. The three models are also compared to three parametric and two nonparametric regression models. The results indicate that the predictive accuracy of semiparametric regression models is higher than those obtained from the parametric and stepwise cluster analysis models. However, the proposed three semiparametric regression models could be much favored, since they can be achieved more easily and rapidly than the artificial neural network model.

A systemic ecological risk assessment based on spatial distribution and source apportionment in the abandoned lead acid battery plant zone, China

In China, potential heavy metal hazard around abandoned lead-acid battery plant (ALBP) area has been a great concern but without detailed report. The distribution and sources of heavy metals in soils and so by risk assessment associated with ALBP are conducted in this contribution, based on geographies and statistics. Pb and Zn are quantitively identified to be still emitted from ALBP soil, and Cd as well As are from agricultural activity. We investigate vertical metal distribution, and fortunately find that metals migrate within limit of 40 cm below topsoil, which is higher than groundwater table. The visualized stable depths are Zn 40 cm, Pb, As 20 cm, and Cd 40 cm. The mapped pollution load index (PLI) suggests a high pollution level exists in ALBP soil. The estimation of potential ecological risk index (PERI) indicates a light ecological risk in studied area, while As and Cd mainly from agricultural activity possess 54% of total Eri. Health risk index (THI) is 0.178 for children, indicating non-cancer risks may be ignored in observed area. Though calculated risk is temporarily affordable, soil remediation and reduction of agricultural chemical reagents are recommended for preventing potential cumulative risk from further bioconcentration of heavy metals.

Heterogeneous Fenton degradation of bisphenol A using Fe3O4@β-CD/rGO composite: Synergistic effect, principle and way of degradation

In this study, a multi-component catalyst, β-cyclodextrin (β-CD) and reduced graphene oxide (rGO) co-modified Fe3O4, was fabricated via one-pot solvothermal method and used as a synergistic catalyzer for Bisphenol A (BPA) removal. The study found that catalytic reactions of BPA followed the pseudo-first-order kinetics model, and the correlation rate constants (kobs) were calculated. Compared with Fe3O4@β-CD (0.02173 min-1), Fe3O4/rGO (0.09735 min-1) and Fe3O4 (0.01666 min-1), the composite (0.15733 min-1) exhibited stronger catalytic ability to remove BPA from aqueous solution under the same conditions, which were attributed to the synergistic enhancement effect among the components. The introduction of rGO in the composites was beneficial to the generation of •OH, and the role of β-CD might enhance the utilization of •OH. A possible three-element catalytic schematic diagram was described. The effects of pH, dosage of the catalyst, initial H2O2 and NH2OH concentrations on the removal efficiency were further investigated. The removal of BPA and TOC retained 78.2 ± 2.4% and 52.9 ± 2.5% after five cycles, indicating its excellent stability and reusability. Furthermore, a probable reaction pathway of BPA removal was suggested by analyzing the intermediate products. All results indicated that the composite had high and stable catalytic performance, which made it have potential application on the industrial treatment of wastewater.

Methodology of spatial risk assessment for arsenic species associated with sampling and analysis results optimization

The conventional risk assessment methods may be defective for more effective health risk assessment due to ignoring heavy metal species and the accuracy and integrity of sampling and analysis results. Using the accurate and integral data to quantify the human health effects of metal species can provide great support for more effective health risk assessment. This study presents a new methodology to optimize sampling and analysis results for implementing the spatial human health risk of heavy metal species in contaminated sites. The method integrated Entropy method and Inverse Distance to a Power (IDW) for obtaining the effective risk, and mapping the visual risk distribution of metal species. The results of its application with ingesting arsenic via oral route on adults showed that carcinogenic and non-carcinogenic risks of As were influenced by its species. The risk of HAsO4-2, H3AsO3, H2AsO4-, H2AsO3- and AsS(OH)HS- exceeded threshold that was significantly harmful to human health in study area. This method broadened the scope of human health risk assessment and provided a basis for government policy-making and site remediation.

High efficiency and rapid degradation of bisphenol A by the synergy between adsorption and oxidization on the MnO2@nano hollow carbon sphere

In this research, a novel efficiency MnO2@Nano hollow carbon sphere (MnO2@NHCS) nanocomposite was prepared by one-pot hydrothermal reaction with KMnO4 solution. The adsorption and oxidization performance of MnO2@NHCS were assessed by degradation of bisphenol A (BPA) at different conditions. The effect of dosage of MnO2@NHCS, pH, initial concentration of BPA, temperature and humic acid were investigated systematically. Moreover, the characterizations of MnO2@NHCS were measured by a series of techniques, such as XRD, FESEM, HRTEM, TGA and XPS. Notably, hollow structure of nano carbon sphere was still retained with uniform MnO2 nanosheets covered. The results show that the removal rate of BPA was 95.3% within 10 min and BPA can be almost decomposed in 30 min under the optimal conditions. Additionally, the MnO2@NHCS remained stable and had a high regeneration efficiency (more than 85%) after 3 cycles (360 min). The reaction intermediates/products of oxidation of BPA were analyzed and the possible degradation pathways of BPA were proposed. These research results demonstrate that the MnO2@NHCS is a fleet and efficient material for BPA degradation in aqueous environment.

Establishing a method to assess comprehensive effect of gradient variation human health risk to metal speciation in groundwater

A method was proposed to evaluate comprehensive effects of pHs and total metal concentration (TMC) variation for metal speciation human health risk in groundwater. The method used for the health assessment considered comprehensive and mutative effects caused by oral ingestion of groundwater based on human health risk assessment model and MINTEQ simulation. The results demonstrated that the dissolution rate of Ni2+ was affected by pH and Ni total concentration (total-Ni). With the increase of pH, the Ni2+ dissolved rate was smaller in the higher total-Ni at same pH. Ni2+ was dominant components contributed to health risk in groundwater. With the increase of pH in various total-Ni, HINi keep constant at first, and then decreased gradually. The HINi values of Ni speciation above acceptable level only in high total-Ni with alkaline conditions. The obtained results to verify that metals speciation were determined in health risk, and variation factors (pH and metal total concentration) played important role in risk estimation. These results provide basic information of heavy metal pollution control as well as remediation management.

Establishing a health risk assessment for metal speciation in soil—A case study in an industrial area in China

An improved method was proposed which integrates the distribution of metal speciation simulated by chemical equilibrium model, different exposure models and average daily intake dose modified by analytic hierarchy process for human health risk assessment of metal species (MS). With the rapid development of economic and urbanization, the metals pollution had become more serious in industrial areas. Adverse effects of soil contaminants on human health in typical industrial area should be assessed to evaluate the risks of soils in these areas. The method was applied to study nickel (Ni) species health risks in soil of industrial areas. The pH possessed significant impact to determine distribution/existence and solubility of Ni species, followed by DOC. The non-carcinogenic risk (HQ) of Ni species were less than 1 in each sampling points, except Ni2+. In addition, the carcinogenic risk (CR) of different Ni species were less than 10-6, except for FANi and Ni2+.