中文摘要：

于2009年7月（丰水期）、2010年7月（丰水期）和2009年12月（枯水期）在东江干流及其主要支流的水体进行了3次系统水样采集,通过实验测定分析了水体中各形态氮的时空分布特征,结果表明：①东江干支流的氮素污染状况较为严重,TN平均浓度在（1.45～1.93）mg/L之间,整个干支流中IV-V类水体达42%;②不同季节期间水体中氮含量存在一定变化,表现为丰水期TN、DIN、NH4-N和NO3-N浓度均小于枯水期;③按水体中氮含量划分水质等级,可将东江干流分为5个区段：东江源头低值区河段、枫树坝水库上游高值区河段、新丰江水库上游中值区河段、惠州地区上游中值区河段、惠州地区下游高值区河段,干流河段氮浓度空间变化表现为＂低值-升高-下降-维持-再升高＂趋势;④枫树坝水库上游高值区河段的氮来源主要来自干流沿途的农业面源污染,而惠州地区下游高值区河段的氮来源主要来自生活和工业直排点源污染,其中又以秋香江、西枝江、淡水河、石马河、沙河等支流的输入为主体。

英文摘要：

To examine the temporal-spatial distribution of nitrogen in the Dongjiang River basin, we sampled river water regularly and repeatedly in 47 sampling points dispersed in the mainstream and major tributaries of three times （July2009 and 2010 for flood season, and December of 2009 for dry season）. We found that the average concentration of total nitrogen （TN） in the river water were （ 1.45～1.93 ） mg/L, and up to 42% of the water samples from the mainstream and tributaries were polluted grades IV to V according to the national water quality standards. The average nitrogen concentration in the forms of TN, DIN, NH4-N and NO3-N changed seasonally, being lower in flood season than that in dry season. According to the average nitrogen concentration in river water, the mainstream of Dongjiang River could be divided into five different reach sectors： the low value sector upstream of river source; the high value sector upstream of Fengshuba Reservoir; the medium value sector upstream of Xinfengjiang Reservoir; the medium value sector upstream of Huizhou City area; and the high value sector downstream from Huizhou City area. The pollution sources of nitrogen for the two most heavily-polluted sectors were different. Upstream of Fengshuba Reservoir, the sources were primarily non-point pollution origins from agriculture,whereas downstream from Huizhou City area the sources came mainly from point pollutants from industrial wastewater and domestic sewage, particularly from tributaries of the Qiuxiangjiang River, Xizhijiang River, Danshuihe River, Shimahe River and Shahe River.