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A number of remediation measures have been used in paddy fields to alleviate serious cadmium (Cd) contamination, which may pose a public health risk through the food chain. In this study, a field trial was conducted in paddy fields with slight–moderate Cd contamination to investigate the remediation effects of combined remediation measures (CRMs), including the use of Cd-safe rice (Oryza sativa L.) cultivars, water management modes (WMMs), lime application (LA), soil amendment application (SAA), and foliar silicon (Si) fertilizers. Two groups of field trials were designed including CRMs with selenium (Se) and without selenium (non-Se) application. The results show that soil measures (LA + SAA) can increase the soil pH by 0.99 and decrease the soil DTPA-extracted Cd content by 34.19% (p < 0.05). All measures used in the present study significantly decreased the Cd content in husked rice and yield, except for the WMMs; the CRMs achieved the best results, and Se application enhanced the effects of all measures. This study shows that CRMs significantly decreased the Cd content in husked rice by 58.10%; this value increased to 72.69% after Se application (p < 0.05). These results provide useful information for selecting remediation measures in paddy fields with slight–moderate Cd contamination. [ABSTRACT FROM AUTHOR]

Geochemical properties of rare earth elements (REEs) have the potential to represent the provenance and depositional history of surface sediment in aquatic environments. In this study, both surface and core sediment samples were collected from Dongting Lake to investigate the distribution characteristics and source of REEs by combining the methodologies of geostatistics, positive matrix factorization (PMF) model, discriminant function (DF), and provenance index (PI) based on REEs geochemical parameters. The results indicated that the total REEs content in sediment samples ranged from 129.12 to 284.02 μg g−1, with the average REEs content calculated to be 197.95 μg g−1. Light REEs (LREEs) comprised >90% of the total REEs, indicating that there was an enrichment of LREEs in the sediment samples. The REEs of the surface sediment showed strong spatial variation, with relatively high values located in Eastern Dongting Lake and relatively lower levels in Western Dongting Lake. Moreover, the vertical distributions of ∑REEs, ∑LREEs and ∑HREEs at most sampling sites behaved similarly with rapid increase until about 6–8 cm, followed by a downward trend with some irregularities. The strong association between most REEs confirmed that they often have a positive correlation and co-existence in sediment. The PMF model revealed that most of the REEs in the surface sediment were derived from natural sources with some anthropogenic inputs also serving as contributing sources. The DF and PI results indicated that the REEs distribution pattern in the surface sediment of Dongting Lake was similar to that of the Yangtze River, suggesting that Yangtze River had been more of an influence on sediment loads than the upstream tributaries. This study highlights the broader applicability of the REEs tracing method in sediment transport processes and can provide new knowledge regarding source apportionment analysis of sediment-related contaminants in aquatic environments. Unlabelled Image • Geochemical characteristics of REEs in sediment from Dongting Lake were studied. • Strong correlations were presented between most REEs in sediments. • Natural and anthropogenic sources of REEs were identified by PMF modeling. • DF and PI were used to discriminate the source areas of surface sediments. [ABSTRACT FROM AUTHOR]

Particulate pollution, especially PM2.5 (particles with an aerodynamic equivalent diameter of 2.5 μm or less), has received increased attention in China recently. In this study, PM2.5 samples were collected in August 2013 and April 2014 from different regions of Baotou, the largest rare earth elements (REEs) processing city in northern China. The concentrations and distribution patterns of REEs in PM2.5 were analyzed, and the inhalation exposure to REEs associated with PM2.5 was assessed. The results showed that the REEs levels were 56.9 and 15.3 ng m−3 in August 2013 and April 2014, respectively. These values are much higher than those in non-REEs mining areas. The distribution patterns of REEs exhibited LREE enrichment. The Eu and Ce anomalies displayed slightly positive and negative values, respectively, which were in accordance with the background soil and ore. The average daily intake amounts of REEs for population through inhalation exposure of PM2.5 in Baotou were in the range of 5.09 × 10−7 to 2.25 × 10−5 mg kg−1 day−1. [ABSTRACT FROM AUTHOR]

The lack of management in small-scale mining operations has the potential for negative repercussions, e.g., mine collapses, compared with well-regulated large-scale mines. Here, we used an in vitro model to investigate heavy metal soil pollution characteristics and their attendant health risks in an abandoned, small-scale lead (Pb) and zinc (Zn) mine located in southwestern China that had suffered from collapse. Our results showed the following: (1) Even the mine had been closed for many years, the soil was still heavily polluted by Pb, cadmium (Cd), and Zn, and there is a risk of secondary pollution. Pb, Zn, and Cd concentrations in the mining areas were all approximately 22-42 times higher than the background soil levels of Guangxi Province. (2) Cd had the largest bioaccessibility, and mining areas tend to have soils containing more bioaccessible metals (78 ± 14%, 27 ± 4%, and 38 ± 12% for Cd, Pb, and Zn in gastric phase and 40 ± 12%, 10 ± 5%, and 19 ± 8% in intestinal phase correspondingly). (3) Results of a stepwise, multiple regression analysis revealed that the total soil content of the three metals (Pb, Zn, and Cd), TOC (total organic carbon), soil composition, and Mn content were the main impact factors for the Pb, Cd, and Zn soil bioaccessibility in study area (R2 = 0.37~0.93). (4) A health risk assessment based on Pb, Cd, and Zn bioaccessibility indicated that the health risk for people in mine area is not high (HI is 1.07 at most and CR 2.40E−6 at most for children). [ABSTRACT FROM AUTHOR]

Airborne fluoride associated with total suspended particles (TSP) and respirable particulate (PM 10 ) in the rare earth mining and smelting areas were analyzed during August 2012 and March 2013. In March, average concentrations of fluoride bound to TSP in the mining and smelting areas were 0.598 ± 0.626 μg/m 3 and 3.615 ± 4.267 μg/m 3 , respectively, whereas that in August were 0.699 ± 0.801 μg/m 3 and 1.917 ± 2.233 μg/m 3 , respectively. TSP samples were classified into four categories by different sampling periods and locations using Kohonen's self-organizing map, which demonstrates that high airborne fluoride concentrations in March in the smelting area were probably attributed to industrial emissions from smelting activities and wind-blown dust from tailings pond, influenced by meteorologic parameters such as temperature, relative humidity, precipitation and wind speed. The mean daily amount of fluoride inhaled in the mining and smelting areas were estimated to be in the range of 2.77–57.61 μg/day and 3.39–64.32 μg/day, respectively. These results indicate the high potential exposure level of fluoride inhaled for local residents in the polymetallic mining and smelting areas. [ABSTRACT FROM AUTHOR]

A comprehensive analysis of content, pollution characteristics, health hazard, distribution, and source of some broadly concerned potentially toxic elements (PTEs, Pb, V, Mn, Cr, Ba, Zn, Ni, and Cu) in surface fine dust with particle size <63 μm (SFD63) from residence communities in Xi'an, a representative valley industrial city, was conducted in this research to analyze the quality of environment and influencing factors of valley industrial cities in China. The average contents of Ba (794.1 mg kg−1), Cu (61.3 mg kg−1), Pb (99.9 mg kg−1), Zn (408.1 mg kg−1), Cr (110.0 mg kg−1), and Ni (33.4 mg kg−1) in SFD63 of Xi'an residence communities surpassed their background contents of local soil. The high enrichment-value regions of PTEs were chiefly located in the regions with high traffic flow, high population density, and areas around industries. Zn and Pb had moderate enrichment, and the overall pollution level of PTEs was unpolluted-to-moderate and moderate pollution. Three source categories (including natural geogenic source, industrial anthropogenic source, and mixed anthropogenic source of transportation, residential activities, and construction) were identified as the predominant sources for the PTEs pollution in SFD63, with the contribution levels of 29.9%, 32.4%, and 37.7%, respectively. The assessment of health risks according to Monte Carlo simulation revealed that the 95% of the non-cancer risk of PTEs to residents (the elderly, working people, and children) was less than the threshold of 1, while the probability of cancer risk exceeding the acceptable threshold of 1E-6 was 93.76% for children, 68.61% for the elderly, and 67.54% for working people. Industrial source was determined as priority pollution source and Cr was determined as priority pollutant, which should be concerned. [Display omitted] • Source-specific probabilistic health risk assessment was conducted in this study. • Surface fine dust of residential area had elevated toxic elements. • Mixed source was the main anthropogenic source of toxic elements in the fine dusts. • Toxic elements in the fine dusts had a certain cancer risk to the residents. • Industrial source and Cr were the priority control factors for pollution control. [ABSTRACT FROM AUTHOR]

• Prioritizations of the 24 targets of the five LEEW related SDGs were set. • The interactions and performances of targets were assessed to prioritize them. • Key actions for promoting these SDGs were provided (e.g., regional collaboration). • The high trade-offs among water and energy dimensions require attention. The five Sustainable Development Goals (SDGs) related to livelihood, energy, ecosystem, and water (LEEW) are highly interlinked, and their progress is a strong stepping stone to achieve other SDGs. However, research about the effective actions for promoting them in the Asian Water Tower (AWT) region (16 countries) is limited. Here, we measured the interactions (synergies and trade-offs) among and the performances of 24 SDG targets related to LEEW based on calculating correlation coefficients, network analysis, and index-based and benchmarking analysis. By aggregating the results, we eventually prioritized the 24 targets to provide evidence-based support for identifying holistic and synergistic actions across scales. Targets 2.3 (agricultural productivity), 7.1 (modern energy services), 7.2 (renewable energy), 15.2 (sustainable forests), 15.5 (habitat and biodiversity conservation), 15.6 (sharing benefits from genetic resources), and 1.a and 15.a (resources mobilization) were top-prioritized. Mainstreaming them along with numerical target values into strategies across scales can be a useful starting action. Additionally, we highlighted several obstacles for these SDGs' progress (e.g., trade-offs among basin water and energy resource management in the future energy-oriented LEEW actions) and some keys to support their achievements (e.g., interdisciplinary research, sectoral transformation, and transnational and cross-basin collaboration). [ABSTRACT FROM AUTHOR]