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To clarify the mechanism controlling the migration of uranium and typical heavy metals at the sediment–water interface, four sampling cores were collected along the Mianyuan River near a phosphate mining region to investigate their distribution in pore water and sediment along vertical profiles. This study indicated that: (1) the average concentrations of U, Cd, Cu, Pb, Zn and Ni in the pore water were 2.17, 0.08, 6.28, 1.78, 80.56 and 5.18 µg l−1 , respectively, some of them being higher than the National Recommended Water Quality Criteria. (2) The enrichment of U, Cu, Pb, Zn and Ni in the sediment near the urban area clearly indicated that local industries were important pollution sources. (3) The average diffusive fluxes of U, Cd, Cu, Pb, Zn and Ni of the four profiles were 0.016, 0.007, 0.300, 0.022, 2.925 and −1.328 µg/(m2·d), indicating that most of the metals diffused from the sediment pore water to the overlying water. (4) The IWCTU (Interstitial Water Criteria Toxic Units) values of Pb in the pore water exceeded 1 in most river sections, indicating that the toxicity levels in the sediments presented a risk to aquatic organisms. [ABSTRACT FROM AUTHOR]

To explore geochemical factors affecting the chronological reconstruction of a historical arsenic pollution accident in Lake Qionghai at southwest of China, heavy metals and radionuclides (210Pbexand137Cs) in two sediment cores were sampled and analyzed. Our study revealed that (1) industrialization and urbanization of Xichang since the mid-20thCentury, aggravated soil erosion in the catchment and resulted in a significant and lasting increase in the sedimentation rate of Lake Qionghai; (2) sharp arsenic peaks in two sediment cores recorded an arsenic pollution accident in 2006 in which a large amount of arsenic was discharged into the lake from a chemical plant. Arsenic peaks in sediment cores A and B were dated to 1988 ± 3.5, 2006 ± 3.1, respectively. Only the arsenic peak time in core B: 2006 ± 3.1, agreed with the real pollution accident time of 2006. Linear correlation analysis suggested that arsenic sorption by Fe/Mn minerals and organic materials in sediment core A probably changed the depth distribution of the peak and affected the accuracy of chronological reconstruction. This case study suggested that sorption of heavy metals by Fe/Mn minerals and organic materials should be assessed before the chronological reconstruction of the metal pollution accident in the lake. [ABSTRACT FROM AUTHOR]

The Maoniuping rare earth elements deposit is the second largest rare earth elements deposit in China, and the third largest in the world. A sediment core was collected from the river floodplain downstream from the Maoniuping rare earth elements mining area (Sichuan Province, China) to reconstruct the cadmium contamination history and trace its contamination source. Based on lead-210 (210Pb) dating by gamma ray spectrometry and elements determination with inductively coupled plasma mass spectrometry of the sediment core, it was found that the cadmium accumulation rate of the flood plain increased from 0.16 to 2.22 µg cm−2yr−1over the past 100 years. Combining aspects of time, space, and element composition information, it is proved that the exploitation of Maoniuping rare earth elements deposit was the main reason for the increase. Moreover, to evaluate the mobility and availability of cadmium in the sediment core, the modified European Communities Bureau of Reference sequential extraction procedure in combination with inductively coupled plasma mass spectrometry was applied. Risk assessment code was used to further assess the environmental risk of cadmium in the sediment. It was found that the environmental risk from cadmium was high in the surface of the sediments. The results from gamma ray spectrometric and mass spectrometric methods may provide important information for the control and remedy of cadmium-related pollution areas. [ABSTRACT FROM PUBLISHER]

Vanadium is a trace element widely distributed in the Earth’s crust. Naturally high levels of vanadium are recognized mainly in basic rocks and minerals, particularly in titaniferous magnetite. And the anthropogenic sources of vanadium include fossil fuel combustion and wastes including steel-industry slags. In the last few years, the authors have made investigations and assessments on the environmental geochemistry and ecological risk of vanadium in the Panzhihua mining and smelting area. In the study area, anthropogenic vanadium resulted from mining, extracting and smelting of V-Ti magnetite; vanadium pollution of topsoil and sediments occurs mainly in the mining and extracting area, smelting area, slag dumping area, tailing dam and coal mining area. In the soil, the chemical speciation of vanadium shows: insoluble residue > organically bound > Fe (amorphous) oxide-bound > Mn oxide-bound > soluble component. Vanadium pollution can cause potential harmful effects on ecological systems, and lead to animal poisoning and human disease. So vanadiam pollution should be monitored on a regular basis in the Panzhihua area. [ABSTRACT FROM AUTHOR]

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, water body and stream sediment. An environmental geochemical investigation was carried out in and around the Panzhihua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study are. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly contaminated. Geochemical maps of I[subgeo] of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elements come mainly from dusts resultant from mining activities and other three-waste-effluents. The are needs to be monitored regularly for trace metal, especially heavy metal enrichment. [ABSTRACT FROM AUTHOR]

Abstract: The Wenchuan earthquake with magnitude 8.0 hit Longmen Mountain on May 12, 2008. The coseismic deformation changed the slope in an instant and caused massive outbreaks of landslides and debris flows, which altered the river transport system. The seismic landslides, debris flows and subsequent heavy rainfall and flooding increased sediment discharge. Data on sediment discharge, rainfall, landslides, and debris flows were collected in this study for 1980–2010 to describe the effects of the Wenchuan earthquake and post-earthquake heavy rainfall on the increase in sediment discharge in the upper reaches of the Min River. The relationship between precipitation, sediment discharge, landslides, and debris flows before and after the Wenchuan earthquake in the upper reaches of the Min River was analyzed. The variation trends of sediment discharge in the river basin before and after the earthquake were calculated quantitatively. The research results can be summarized as follows: (1) Sediment discharge increased by approximately 30% due to coseismic uplift, coseismic landslides, and debris flows after the Wenchuan earthquake. (2) The sediment discharge caused by heavy rainfall after the earthquake was 1.75 times larger than before the earthquake. The percentage contribution of the sediment yield of debris flows induced by heavy rainfall after the earthquake to the increase in sediment discharge was 34.54%. (3) The heavy rainfall zone basically coincided with the earthquake fault zone and the seismic landslide zone. Therefore, there was a positive-feedback relationship between the increase of sediment discharge and heavy rainfall after the Wenchuan earthquake. (4) The loosening of surface materials and landslides driven by the Wenchuan earthquake resulted in an increase in sediment discharge into the river, bringing about a great disaster which will need to be addressed in the coming decades. [Copyright &y& Elsevier]

To clarify the impact of developing world-class REE and V-Ti magnetite mines on the distribution of potentially toxic elements (As, Cd, Co, Cu, Cr, Hg, Ni, Pb, Tl, U, and Zn) in adjacent aqueous sediments, thirty sediment samples from the Anning River and seventeen ore samples from the Panxi Rift of China were investigated. The results from this study suggest the following: (1) Mining activities have resulted in severe pollution of sediment by potentially toxic elements, especially Pb with an average concentration of 213.8 mg/kg, which is much higher than the probable effect concentration (PEC) and background values. (2) Different kinds of mines caused the enrichment of different elements in surface sediments. Heavy to extreme enrichment of Pb (EF = 45) and U (EF = 12) was observed in sediment near the Mianning REE mine, and severe enrichment of Pb (EF = 54), As (EF = 18), Cd (EF = 13) and U (EF = 8) was observed in sediment near the Lugu iron mine. (3) Concentrations of Pb and As in sediment that were extremely higher than the PEC indicate probable toxicity and support the need for further speciation analysis. (4) The joint application of distribution characteristics analysis (DCA) and robust regression (RR) was useful in identifying the source of potentially toxic elements in sediment near mining areas. Distribution characteristics analysis of risk elements can qualitatively suggest outliers, and robust regression can quantitatively identify whether a high concentration of a risk element can be classified as an outlier compared to a reference element. [ABSTRACT FROM AUTHOR]