Pollution Distribution of Potentially Toxic Elements in a Karstic River Affected by Manganese Mining in Changyang, Western Hubei, Central China.

This study investigated the distribution, pollution level and potential ecological risk of potentially toxic elements (PTEs) from manganese mining in a karstic Danshui River, in Changyang, Western Hubei, Central China. River water and sediments were collected for seven PTEs measurement (As, Cd, Cr, Cu, Mn, Pb and Zn), as well as pH and Eh of the river water were measured. Results showed that the major pollutant was Mn, the river water environment was mainly acidic and oxidizing (288 < Eh, pH < 6.3), and the pollution distribution of Mn in the study area was dominated by the combination of natural processes and anthropogenic activities. In the river water, according to the contamination factor (CF) and pollution load index (IPL) results, Mn was considered the main pollutant. There was low As and Pb pollution downstream as well as Cu pollution upstream. Upstream and downstream areas were the main polluted river sections of the river water samples collected. In river sediments, based on the results of the geo-accumulation index (Igeo) and potential ecological risk index (IPER), it was determined that there was only considerable Mn pollution. The IPER of the PTEs from the river sediments was at acceptable levels, only Mn upstream performed at a moderate ecological risk level. According to Pearson correlation and principal component analysis, Mn originated from manganese mining activities, Cd, Cr and Zn were of natural origin, and Cu may have come from both mining and natural origin, whereas Pb and As were mainly related to the daily activities. Consequently, elemental speciation, mining activities and the distribution of water conservancy facilities were the main impacts of PET pollution distribution in this river.

[Seasonal Distribution Characteristics and Health Risk Assessment of Heavy Metals in Surface Water of Qingjiang River].

In order to assess the health risks of heavy metals in surface water of Qingjiang River, surface water samples were taken at designed cross-sections of the river and analyzed for Cr, Cu, Zn, Pb, Cd, As, and Mn. Health risks from these heavy metals for adults and children in wet and dry seasons were compared by water environmental health risk assessment model of the USEPA. It found that the main excessive element is Mn, concentrating in the Danshui, Yantouxi, and Pingluoxi, the slightly excessive element is As, the concentration of Mn was above national standard, and it mainly distributed in Danshui, Yantouxi, and Pingluoxi, As was slightiy over the standard, and it concentrated in Wujiahe, The content of heavy metals during wet season were all higher than those during dry season. Cr, Cu, Zn, and Cd are mainly originated from the nature, Pb and As are separately mainly originated from traffic and agriculture, Mn originated from mining mainly in the downstream, while it has natural source from upper to middle. The health risks of heavy metals in surface water to adults and children in wet season are higher than those in dry season. The main health risk area was the midstream. As was the highest health risk element and children were the most preventive group. Specially, people in towns who drink the water from midstream should pay more attention.