赣江上游河道氮污染分析评价

Analysis and evaluation on the nitrogen pollution in the upper reaches of Ganjiang River

为研究赣江上游-桃江流域水质污染分布状况,基于平水期在桃江流域采集的167个水样,通过现场和室内分析测定,并运用内梅罗综合污染指数和单因子污染指数评价法对流域的硝氮和氨氮污染状况进行评价。结果表明:①桃江干流和大部分支流pH值都在地表水环境质量标准限值范围内,但濂江17个采样点中,有4个采样点受小型电站和酿酒厂的影响,pH值低于地表水标准限值;②亚硝氮极易被氧化,是流域总体亚硝氮含量较低的原因,干流上游部分地区亚硝氮浓度稍高,渥江和濂江水质差,河水处于缺氧或厌氧状态,浓度较高;③流域总体硝氮超标率为31.7%,龙迳河和濂江受矿区及畜禽场的影响,硝氮变异系数大且超标严重,超标率分别为73.3%,70.6%;④流域内稀土矿区分布广、数量大,采矿、选矿过程中大量使用的硫酸铵、碳酸氢铵等化学药剂的使用,使氨氮污染最严重,且均超出地表Ⅲ类水氨氮限值,其中介于Ⅲ~Ⅳ类水占51.5%,Ⅳ~Ⅴ类水占8.4%,劣Ⅴ类水占40.1%。

To study the distribution of water pollution in the upper Ganjiang-Taojiang River basin,based on 167 water samples collected in the Taojiang River Basin(in normal water)period,it was determined by onsite and indoor analysis,and the comprehensive pollution index and single-factor pollution index evaluation method were used to assess the nitrate in the watershed.The ammonia and nitrogen pollution status was evaluated.The results showed that:①The pH value of the main stream of Taojiang River and most of its tributaries are within the limits of surface water environmental quality standards,but 4 of the 17 sampling points in Lianjiang River were affected by small power stations and wineries whose pH value was lower than the standard limit of surface water;②Nitrous nitrogen was easily oxidized,which was the reason for the lower nitrous nitrogen content in the basin.The concentration of nitrite nitrogen in some areas of the upper reaches of the main stream was slightly higher,the water quality of the Wojiang River and the Lianjiang River was poor,and the river water was in an anoxic or anaerobic state with higher concentration;③The overall over-standard rate of nitrate and nitrogen in the basin was 31.7%.Affected by mining areas and livestock and poultry farms,the coefficient of variation of nitrate and nitrogen in the Longjing River and Lianjiang River was large and exceeds the standard seriously which the exceed ratios were 73.3%and 70.6%respectively;④Rare earth mines in the basin were widely distributed and had a large number.The use of chemicals such as ammonium sulfate and ammonium bicarbonate,which were widely used in large quantities in the mining and beneficiation process,made the ammonia nitrogen pollution the most serious,and all of them exceeded the surface ammonia nitrogen limit of ClassⅢwater,among which GradeⅢ~IV water accounted for 51.5%,Grade IV~V water accounted for 8.4%,and water inferior to Grade V accounted for 40.1%.