Sources and the distribution of heavy metals in the particle size of soil polluted by gold mining upstream of Miyun Reservoir,Beijing: implications for assessing the potential risks

Mining has been carried out upstream of Miyun Reservoir, Beijing, for several decades, and has caused metal emissions to the environment, threatening human health. We conducted a soil survey to assess metal contamination in this area and to determine distribution of heavy metals in the particle size. We attempted to determine the possible sources of the metals and the significance of metals in the fine particle fractions to soil risk assessments. Thirty-four soil samples were collected, and eight samples were partitioned into seven size fractions. Most of the metal concentrations in the soils were higher than the background levels in Beijing, and the metal concentrations and total organic matter (TOC) contents generally increased as the particle size decreased. Each metal except Hg significantly positively correlated with the TOC. The metals in the coarse-grained soils were mainly derived from parent materials, but the metals in the fine fractions were mostly anthropogenic. Statistical analyses showed that there were three metal sources: Cd, Cu, Hg, Pb, and Zn had anthropogenic sources; Co, Cr, Ni, and V had mixed anthropogenic and natural sources; and As and Be had natural sources. The trace metals were primarily in the clay and fine silt fractions, and they might pose health risks through the inhalation of resuspended soil particles (PM10 and PM2.5). The elevated accumulation factors, enrichment factors, and ecological risk indices for the metals in the fine fractions suggest that risk assessments should be based on the fine particle size.     

Functional soil organic matter fraction in response to short-term tillage management under the double-cropping rice paddy field in southern of China

Environmental Science and Pollution Research - Soil organic matter (SOM) and its fraction play an important role in maintaining and improving soil fertility of paddy field. However, there is still...     

Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine,caffeine and atenolol pharmaceuticals

Environmental Geochemistry and Health - Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health....     

RETRACTED ARTICLE: Adaptation strategies of farmers to drought in a changing climate in Dingcheng County,Hunan, southern China

Regional Environmental Change -     

Effects of pH,initial Pb2+ concentration,and polyculture on lead remediation by three duckweed species

Various geographical duckweed isolates have been developed for phytoremediation of lead. The Pb²⁺ removal efficiency of Lemna aequinoctialis, Landoltia punctata, and Spirodela polyrhiza was investigated in monoculture and polyculture at different levels of pH and initial Pb²⁺ concentrations. L. aequinoctialis was not sensitive to the tested pH but significantly affected by initial Pb²⁺ concentration, whereas synergistic effect of pH and initial Pb²⁺ concentration on removal efficiency of L. punctata and S. polyrhiza was found. Although the majority of polycultures showed median removal efficiency as compared to respective monocultures, some of the polycultures achieved higher Pb²⁺ removal efficiencies and can promote population to remove Pb²⁺. Besides, the three duckweed strains could be potential candidates for Pb²⁺ remediation as compared to previous reports. Conclusively, this study provides useful references for future large-scale duckweed phytoremediation.

     

Occurrence and profiles of polybrominated diphenyl ethers (PBDEs) in riverine sediments of Shanghai: a combinative study with human serum from the locals

Herein, we studied the occurrence and profiles of thirteen PBDE congeners in 30 river sediment samples from Shanghai, China. The concentrations of Σ₁₃PBDEs ranged from 110 to 13,071 pg g ^?1 dw, with an average value of 2,841 pg g ^?1 dw. BDE-209 was the predominant congener accounting for more than 65 % of total PBDEs, demonstrating that the major source of PBDEs in sediment samples was associated with the prevalent use of technical deca-BDE products. Moreover, low brominated BDEs in sediments also came from the degradation of higher brominated BDEs. In addition, taking into consideration of dietary exposure, PBDEs in serum samples collected from the locals were also detected with range of 419–26,744 pg g^?1 (average 5,561 pg g ^?1), which suggested a relatively low burden of PBDEs contamination to human body compared with the condition in other place. And in serum, low brominated compounds constituted the majority of total PBDE congeners.     

纳米银的体内毒性及毒作用机制研究进展

很多研究表明纳米银对机体的消化系统、呼吸系统、生殖系统等多个系统均会产生毒作用，且其毒作用受到多种因素的影响。目前关于纳米银的毒作用机制尚未明确，研究发现纳米银的毒作用机制可能与银离子释放，活性氧自由基产生，氧化应激的发生，炎症反应等有关，最新研究指出纳米银的毒性作用还可能与内质网应激和自噬有关，本文将就纳米银的体内毒性及毒作用机制进行综述。     

基于支持向量机的白云湖水质评价

利用支持向量机模型良好的推广和泛化能力,以及在处理分类问题及小样本问题方面的优势,构建了湖泊水质评价模型,并运用此模型对白云湖的水质评价进行了研究。于2011年对广州市白云湖进水口A和出水口E以及湖区内B、C、D共5点分别进行了3次水质监测(1月份、4月份和8月份)。分析结果表明,A、B、C、D、E 5点1月份的水质除B点为Ⅳ类水外其余4点均为Ⅴ类水,4月份除A点为Ⅴ类水外其余4点均为Ⅳ类水,8月份除A为Ⅳ类水外其余4点均为Ⅱ类水,白云湖在经过开始的不稳定状态后,正在逐渐实现其净化水质的设计作用。相对于常规的评价方法,所得结果更为科学、合理。     

A fingerprint analysis method for characterization of dissolved organic matter in secondary effluents of municipal wastewater treatment plant

Dissolved organic matter (DOM) in wastewater and reclaimed water is related to water quality, safety, and treatability. In this study, DOM was characterized through a fingerprint analysis method for DOM characterization using resin fractionation followed by size exclusion chromatography (SEC). Resin fractionation was used in the first step to divide the DOM in water samples into six resin fractions, namely, hydrophobic acids (HOA), hydrophobic bases (HOB), hydrophobic neutrals (HON), hydrophilic acids (HIA), hydrophilic bases (HIB), and hydrophilic neutrals (HIN). SEC analysis was then performed to separate each resin fraction into several (n) subfractions with different molecular weights (MW). Thus, the total DOM in the water sample was fractionated into 6n subfractions. After quantification of each subfraction by dissolved organic carbon (DOC), a fingerprint graph was constructed to express the distribution of DOM in the subfractions. The fingerprint analysis method was applied to a secondary effluent sample during ozonation. Ozonation (dose of 10 mg L^?1) removed the DOC only by 8 % and reduced UV₂₅₄ of the sample by 36 %. Fingerprint graphs also revealed that the resin fractions changed quite limitedly but transformation of subfractions occurred notably.     

A new approach for crop identification with wavelet variance and JM distance

This paper develops a new crop mapping method through combined utilization of both time and frequency information based on wavelet variance and Jeffries–Matusita (JM) distance (CIWJ for short). A two-dimensional wavelet spectrum was obtained from datasets of daily continuous vegetation indices through a continuous wavelet transform using the Mexican hat and the Morlet mother wavelets. The time-average wavelet variance (TAWV) and the scale-average wavelet variance (SAWV) were then calculated based on the wavelet spectrum of the Mexican hat and the Morlet wavelet, respectively. The class separability based on the JM distance was evaluated to discriminate the proper period or scale range applied. Finally, a procedure for criteria quantification was developed using the TAWV and SAWV as the major metrics, and the similarity between unclassified pixels and established land use/cover types was calculated. The proposed CIWJ method was applied to the middle Hexi Corridor in northwest China using 250-m 8-day composite moderate-resolution imaging spectroradiometer (MODIS) enhanced vegetation index (EVI) time series datasets in 2012. The CIWJ method was shown to be efficient in crop field mapping, with an overall accuracy of 83.6 % and kappa coefficient of 0.7009, assessed with 30 m Chinese Environmental Disaster Reduction Satellite (HJ-1)-derived data. Compared with methods utilizing information on either frequency or time, the CIWJ method demonstrates tremendous potential for efficient crop mapping and for further applications. This method could be applied to either coarse or high spatial resolution images for agricultural crop identification, as well as other more general or specific land use classifications.