Heaven S, Ilyushchenko M A, Kamberov I M, Politikov M I, Tanton T W, Ullrich S M, Yanin E P
Department of Civil and Environmental Engineering, University of Southampton, UK.
Sci Total Environ. 2000 Oct 9;260(1-3):45-55. doi: 10.1016/s0048-9697(00)00566-0.
A unique and serious case of mercury pollution has occurred in the River Nura and its floodplain in Central Kazakhstan, where mercury-rich wastewater from an acetaldehyde plant was discharged largely without treatment for several decades. In the river, the mercury became associated with millions of tonnes of power station fly ash, forming a new type of deposit known as 'technogenic silt'. During spring floods these highly contaminated silts are transported downstream and are dispersed over the floodplain, leading to widespread contamination of the land. A detailed survey of the floodplain was carried out to investigate the extent of pollution and to assess the need for remediation. Total mercury concentrations in the topsoils of the floodplain ranged from near background levels to over 100 mg/kg. Mercury concentrations in river bank deposits were found to range from a mean of 73.3 mg/kg Hg in the most contaminated section of the river to a mean of 13.4 mg/kg Hg at a distance of 70 km downstream. Concentrations were lower than corresponding concentrations in the riverbed within the first 25 km from the source of the pollution, but thereafter they were significantly higher. The results show that over the past 30-40 years a large proportion of the contaminated sediments from the river was deposited on the 70 km of banks and in the floodplain below the pollution source. Topsoils of the floodplain and silt deposits located on or close to the river banks contain an estimated 53 t and 65 t of mercury respectively, with an additional 62 t in a small natural swamp which was formerly used as a waste disposal area. The contamination is serious but relatively localized, with > 70% of the total amount of mercury in topsoils and > 90% of mercury in river bank deposits located within 25 km from the source.
哈萨克斯坦中部的努拉河及其河漫滩发生了一起独特而严重的汞污染事件。几十年来，一家乙醛厂未经处理的富含汞的废水大量排放到这里。在河中，汞与数百万吨电站粉煤灰结合，形成了一种新型沉积物，称为“技术成因淤泥”。在春季洪水期间，这些高度污染的淤泥被冲向下游，并散布在河漫滩上，导致土地受到广泛污染。对河漫滩进行了详细调查，以研究污染程度并评估修复的必要性。河漫滩表层土壤中的总汞浓度从接近背景水平到超过100毫克/千克不等。河岸沉积物中的汞浓度范围为：河流最受污染区域平均为73.3毫克/千克汞，下游70公里处平均为13.4毫克/千克汞。在距污染源25公里以内，浓度低于河床中的相应浓度，但此后则显著更高。结果表明，在过去30至40年中，河流中大部分受污染的沉积物沉积在污染源下游70公里的河岸和河漫滩上。河漫滩的表层土壤和位于河岸或靠近河岸的淤泥沉积物分别估计含有53吨和65吨汞，在一个以前用作废物处理区的小型天然沼泽中还额外含有62吨汞。污染严重但相对局部化，表层土壤中汞总量的70%以上以及河岸沉积物中汞的90%以上位于距污染源25公里范围内。
