Pollution simulation and remediation strategy of a zinc smelting site based on multi-source information

The study of the spatiotemporal evolution of landscape ecological hazard and human and natural influences is essential for conservative management and regional sustainable development. This study applied a landscape pattern analysis method and geodetector to multi-source data for 2000, 2010, and 2020 to analyze changes in and drivers of landscape ecological hazard in Laos. The results indicated that: (1) There were more prominent changes in landscape types in Laos. Forest area decreased, whereas the areas of other landscape types increased. There was an overall steady change in the landscape patterns of Laos. Besides for significant changes in the artificial surface landscape index, landscape indices remained stable; (2) The cumulative high and extreme ecological hazard areas increased by 1,947.81 km2, whereas the cumulative areas of low and minimal ecological hazard decreased by 8,461.8 km2. Areas of low and moderate ecological hazard accounted for > 85% of the total area. Areas of low ecological hazard were mainly in the northwest and southeast. The area of high ecological hazard was concentrated in the central and northeastern regions. The distributions of different landscape ecological hazards in Laos during the study period were similar, with general patterns of decreasing hazard from north to south; (3) A positive Moran’s I of landscape ecological hazard in Laos was obtained. While the agglomeration effect was pronounced, it decreased over time, resulting in a weakening in spatial autocorrelation. A significant positive autocorrelation was observed in the spatial distribution of landscape ecological hazard in the study area. Agglomerated areas of high and low ecological hazard were mainly concentrated in the northeast and southeast, respectively; (4) The spatiotemporal evolution of landscape ecological hazard in Laos over the last 20 years could be attributed to interactions between natural and anthropogenic influences. Natural influences were a significant driver of changes to landscape ecological hazard in Laos, with annual precipitation and average temperature being the most significant. Anthropogenic influences, including socioeconomic factors and regional accessibility, significantly impacted local ecological deterioration in Laos.

International audience

Integrated framework to assess soil potentially toxic element contamination through 3D pollution analysis in a typical mining city

Groundwater arsenic in Uruguay is an important environmental hazard, hence, predicting its distribution is important to inform stakeholders. Furthermore, occurrences in Uruguay are known to variably show dependence on depth and geology, arguably reflecting different processes controlling groundwater arsenic concentrations. Here, we present the distribution of groundwater arsenic in Uruguay modelled by a variety of machine learning, basic expert systems, and hybrid approaches. A pure random forest approach, using 26 potential predictor variables, gave rise to a groundwater arsenic distribution model with a very high degree of accuracy (AUC = 0.92), which is consistent with known high groundwater arsenic hazard areas. These areas are mainly in southwest Uruguay, including the Paysandú, Río Negro, Soriano, Colonia, Flores, San José, Florida, Montevideo, and Canelones departments, where the Mercedes, Cuaternario Oeste, Raigón, and Cretácico main aquifers occur. A hybrid approach separating the country into sedimentary and crystalline aquifer domains resulted in slight material improvement in a high arsenic hazard distribution. However, a further hybrid approach separately modelling shallow (<50 m) and deep aquifers (>50 m) resulted in the identification of more high hazard areas in Flores, Durazno, and the northwest corner of Florida departments in shallow aquifers than the pure model. Both hybrid models considering depth (AUC = 0.95) and geology (AUC = 0.97) produced improved accuracy. Hybrid machine learning models with expert selection of important environmental parameters may sometimes be a better choice than pure machine learning models, particularly where there are incomplete datasets, but perhaps, counterintuitively, this is not always the case.

Soil pollution by metal(loid)s caused by smelting activities is a severe problem posing a great threat to environmental and human health. In this study, the concentrations, sources and human health risks posed by six potentially toxic elements (Cr, Mn, Zn, Pb, Cd, and As) were determined in the soil of a typical alloy smelting site in South Central China. The results showed that the concentrations of metal(loid)s were in the descending order of Mn > Cr > Zn > Pb > As > Cd. Additionally, the selected elements were classified into different pollution degrees using geo-accumulation index and pollution load index. The entire study area had a high pollution level with relatively severe and extensive contamination by Cr, Cd, and Mn. The combined application of principal component analysis and positive matrix decomposition model revealed that the major sources of these elements include smelting activities (48.68%), waste residue stacking (22.95%), and natural sources (28.37%). According to the results of the human health risk assessment, the non-carcinogenic risk was insignificant as a whole; however, the carcinogenic risk had an unacceptable level. Among them, Cr was the main driver of carcinogenic risk, which needs special attention.

Formation conditions of ecological hazard of urbanized territories under the influence of atmospheric precipitations are analyzed in the paper. Self-consistent control scheme of ecological safety of precipitations is developed. It includes the stages of identification of hazards, formation of databases and making managerial decisions. The analysis of identification features of hazardous factors that cause ecologically hazardous precipitations is conducted. The features of atmospheric precipitations as the object of the ecological safety assessment are described. The choice of acidity index of precipitations in the city of Chernivtsi as an environmental hazard indicator is justified. The model scheme of interaction of natural and anthropogenic factors in the formation of ecologically hazardous sediments is developed. The influence of wind conditions on the environmental safety of precipitations is determined. In particular, it is shown that, in Chernivtsi north-west winds have the greatest influence on the formation of the ecological hazard of atmospheric precipitations. The contribution of stationary and mobile sources to the technogenic transformation of precipitations is analyzed. The role of transport networks and automotive pollution in the formation of roadside areas of high ecological hazard of precipitations is shown. It is found that, in Chernivtsi contribution of mobile sources to the overall picture of air pollution is consistently high and ranges from 91,6-92,3 %. Herewith, 60.4 % of the total emissions of sulfur oxides, 93 % of nitrogen oxides and 97.4 % of carbon oxide is formed due to mobile sources. This in turn leads to the formation of local areas of environmentally hazardous precipitations.

δ34S and δ18O of sulfates and Zn/Cd ratios reveal the cause of soil and groundwater contamination in metalliferous mining areas

Identification and prioritization of critical erosion areas based on onsite and offsite effects

Chapter 2 Contaminant chemistry in soils: Key concepts and bioavailability

Healthy soils are essential to food security and provide significant contributions to the Sustainable Development Goals (SDGs) by conserving biodiversity, improving water quality, and enhancing resilience against extreme weather. However, the introduction of contaminants from various sources into the soil environment has degraded the soil ecosystem and endangered human health. Soil contamination often cannot be visually detected; therefore, soil must be properly utilized, appropriately managed, comprehensively studied, and efficiently conserved. This chapter firstly introduces the types and sources of soil contamination, global soil contamination status, and soil remediation technologies. It then briefly describes the soil contamination in Japan by radioactive cesium (Cs) and the related decontamination practices implemented to address this problem. Furthermore, the results of our previous research on treating Cs contaminated soil using industrial waste materials are introduced. Finally, the efforts and challenges in managing and controlling soil contamination are presented to provide reference for soil remediation.KeywordsSoil contaminantsSoil remediationCesiumRecycling materialImmobilizationSDGs

Effect of potentially toxic elements on soil multifunctionality at a lead smelting site

Potentially toxic metals in the petroleum waste contaminated soils lead to human and ecological risks in Potwar and Kohat Plateau, Pakistan: Application of multistatistical approaches

Influence of microplastic contamination on the dissipation of endocrine disrupting chemicals in soil environment

With the rapid urbanization and industrial structure adjustment in China, many contaminated sites have been left for remediation. It is essential to develop and implement ecological risk assessment (ERA) before remediating contaminated sites at a large scale as well as sequential management. In this review, we discussed the key problems in ecological risk assessment of soils in contaminated sites focusing on scientific principles, frameworks, techniques, and approaches, including 1) the site-specific framework, 2) uncertainty of conceptual model, 3) toxic mechanisms of combined contamination in soil, 4) screening of assessment endpoints, and 5) development of assessing approaches and frameworks. Then, two perspectives were addressed: the toxicological mechanism of soil combined pollution including bioavailability of contaminants in soil and their joint effect is the scientific problem in ecological risk assessment of soil in contaminated site; and weight of evidence approach based on USEPA four-step approach and EU Tier approach is applicable for ecological risk assessment in field conditions. Future studies should focus on: 1) the coordination of ecological risk assessment (ERA) framework and risk management framework, 2) conceptual mo-del, 3) process-based reactive transport models for exposure evaluation, 4) ecotoxicological mechanism of combined contamination in site soil, and 5) high ecological level endpoints. The aim of this review was to provide theoretical base and framework for the establishment of local guideline of ecological risk assessment in China.

Earthquakes have occurred frequently in western China (Sichuan, Tibet, etc.) while the complex site conditions in western regions bring great uncertainty to the seismic performance of isolated high-speed railroad bridges (HSRBs). By studying the relationship between structure-dependent and structure-independent seismic intensity measures, soil site conditions are taken into account in the probabilistic seismic demand model (PSDM), which is applied to analyze the failure probability of the isolated HSRB under different site conditions. Based on the design parameters and test results of a typical isolated HSRB in western region, the analysis of the finite element model of the structure was performed. Probabilistic seismic demand models of the isolated HSRB were developed. The seismic fragility curves of the isolated HSRBs were obtained and the failure probabilities under different site conditions were compared and analyzed. The evaluation of the failure probability that the failure probability of the isolated HSRBs in the site area with seismic intensity of 9 is 35.84% and 78.19% under the soil site categories D and E, respectively. Therefore, the seismic spectrum characteristics of the soil site are an important factor affecting the seismic response of isolated HSRB structures. This study provides a more effective modified PSDM for seismic performance assessment of isolated HSRBs under the different site conditions.