赣南离子型稀土矿区周边河流氨氮浓度时空分布特征

Temporal and spatial distribution of ammonia nitrogen concentration in river around ion-absorbed rare earth areas in Southern Jiangxi

为探究赣南离子型稀土尾矿对周边不同流域水环境产生的影响,以定南县岭北镇月子河流域和龙头流域为研究对象,基于3个水文期的连续监测数据,分析特征污染物氨氮的时空分布差异,利用主成分分析解析其主要污染物及来源。结果表明:研究区域水体丰、枯、平水期pH平均值分别为5.47、4.73、5.38,水质酸化明显;氨氮平均值分别为6.28、6.02、6.07 mg/L,均在《地表水环境质量标准》(GB 3838—2002)Ⅴ类标准限值3倍以上;研究区岭北矿区东南部氨氮浓度最高,中东部最低,距离稀土矿区越远,水中氨氮浓度越低;3个水文期水体主要环境影响因子均为氨氮。即使经过地表水和地下水稀释作用,离子型稀土矿区所在流域水体中氨氮仍长期稳定保持在高位水平,建议水体氨氮污染控制应优先考虑矿区土壤吸附态氨氮污染拦截。

In order to study the influence of ion-absorbed rare earth tailings on the water environment in the surrounding basins of Southern Jiangxi,this paper took the Yuezi River basin and Longtou River basin in Lingbei Town of Dingnan County(Jiangxi,China)as the research object,to study the spatial and temporal distribution differences of the characteristic pollutant ammonia nitrogen based on continuous monitoring data of three hydrological periods.The principal component analysis method was used to analyze the main pollutants and their sources.The results displayed that the water quality was obvious acidification,the average pH in high water period,low water period and normal water period was 5.47,4.73,5.38,respectively,and the average ammonia nitrogen was 6.28,6.02 and 6.07 mg/L,which were more than 3 times of classⅤlimit value in“Environmental quality standards for surface water”(GB 3838-2002).In the spatial distribution,the concentration of ammonia nitrogen was highest in the southeast area and lowest in the east-central area,the content of ammonia nitrogen in water-bodies decreased with the increase of distance to rare earth mining area.The main environmental influencing factor was ammonia nitrogen in all three hydrological periods.Regardless of surface water and groundwater dilution,the concentrations of ammonia nitrogen in water body maintained at high level,so the control of ammonia nitrogen pollution should be returned to the interception of adsorbed ammonia nitrogen on soil.