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乐安江是影响鄱阳湖水质的一条重要河流,近年来非点源污染迅速增加,水质呈下降趋势。运用GIS手段建立了研究区非点源污染的基本空间信息库,在野外水样监测和土地利用调查的基础上,分析了乐安江流域非点源氮的时空变化特征。氮的流失主要以可溶态形式,TN和DTN全年变化剧烈,在12月份普遍较高,4月份次之,9月份最低。在监测各月份乐安江流域TN浓度的范围为0.09~1.359 mg/L,水质属中营养水平。NO-3-N浓度平均值为DTN的65%,是DTN流失的主要形态,其时空分布与TN具有明显的相似性;在丰水期4月份,NH3-N的平均浓度为全年最低水平,平水期9月份NH3-N平均浓度为三氮之首;NO-2-N全年含量最低。各种形态的氮浓度在空间上从上游向下游基本呈增加趋势;西南部地区各种形态的氮浓度普遍高于东北部地区,说明上游水质普遍好于下游水质。
Le An River is an important river that affects the water quality of Poyang Lake. In recent years, the non-point source pollution has rapidly increased, and the water quality shows a downward trend. The basic spatial information database of non-point source pollution in the study area was established by means of GIS. Based on the field water monitoring and land use survey, the temporal and spatial variation characteristics of non-point source nitrogen in the Le’an River Basin were analyzed. Nitrogen loss mainly in soluble form, TN and DTN dramatic changes throughout the year, generally higher in December, followed in April, the lowest in September. The monitoring TN concentration in the Yue’an River Basin in each month ranged from 0.09 to 1.359 mg / L, and the water quality was in medium nutrient level. The average concentration of NO-3-N was 65% of DTN, which was the main form of DTN loss. The spatial-temporal distribution of NO-3-N was obviously similar to that of TN. In April, the average NH3-N concentration was the lowest in the whole year In September, the mean NH3-N concentration was the first of the three nitrogen compounds; the NO-2-N content was the lowest throughout the year. The nitrogen concentration in various forms increased basically from upstream to downstream in space. The nitrogen concentration of various forms in the southwestern region was generally higher than that in the northeast, indicating that the upstream water quality was generally better than the downstream water quality.