Zhao Xue-Min, Yao Ling-Ai, Ma Qian-Li, Zhou Guang-Jie, Wang Li, Fang Qiao-Li, Xu Zhen-Cheng
South China Institute of Environmental Science, Ministry of Environmental Protection, Guangzhou 510655, China.
South China Institute of Environmental Science, Ministry of Environmental Protection, Guangzhou 510655, China.
Chemosphere. 2018 Mar;194:107-116. doi: 10.1016/j.chemosphere.2017.11.127. Epub 2017 Nov 24.
In early January 2012, the Longjiang River was subjected to a serious cadmium (Cd) pollution accident, which led to negatively environmental and social impacts. A series of measures of emergency treatment were subsequently taken to reduce water Cd level. However, little information was available about the change of Cd level in environmental matrices and long-term effect of this pollution accident to aquatic ecosystem. Thus, this study investigated the distribution of Cd in water and sediment of this river for two years since pollution accident, as well as assessed its ecological risk to aquatic ecosystem of Longjiang River. The results showed that it was efficient for taking emergency treatment measures to decrease water Cd concentration to below the threshold value of national drinking water quality standard of China. There was high risk (HQ > 1) to aquatic ecosystem in some of reaches between February and July 2012, but low or no risk (HQ < 1) between December 2012 to December 2013. Cd concentration in sediment in polluted reaches increased after pollution accident and emergency treatments in 2012, but decreased in 2013. During flood period, the sediment containing high concentration of Cd in Longjiang River was migrated to downstream Liujiang River. Cd content in sediment was reduced to background level after two years of the pollution accident occurrence. The study provides basic information about Cd levels in different media after pollution accident, which is helpful in evaluating the effectiveness of emergency treatments and the variation of ecological risk, as well as in conducting water management and conservation.
2012年1月初，龙江河遭受了一起严重的镉污染事故，造成了负面的环境和社会影响。随后采取了一系列应急处理措施以降低水体镉含量。然而，关于环境基质中镉含量的变化以及此次污染事故对水生生态系统的长期影响，可获取的信息很少。因此，本研究调查了污染事故发生后两年内该河流的水和沉积物中镉的分布情况，并评估了其对龙江河水生生态系统的生态风险。结果表明，采取应急处理措施能有效将水体镉浓度降至中国国家饮用水水质标准阈值以下。2012年2月至7月期间，部分河段对水生生态系统存在高风险（危害商数HQ>1），但在2012年12月至2013年12月期间风险较低或无风险（HQ<1）。污染事故发生及2012年进行应急处理后，污染河段沉积物中的镉浓度有所增加，但在2013年有所下降。汛期时，龙江河含高浓度镉的沉积物向下游柳江迁移。污染事故发生两年后，沉积物中的镉含量降至背景水平。该研究提供了污染事故后不同介质中镉含量的基础信息，有助于评估应急处理的效果和生态风险的变化，以及进行水资源管理和保护。
