丹江口水库水体氮的时空分布及入库通量

为解析丹江口水库水体氮的时空分布特征及主要污染来源,以丹江口库区及主要入库河流为研究对象,分析了水体氮的空间分布、季节及年际变化；利用回归分析,解析了氮污染驱动因素；并估算了入库河流氮通量及对库区氮污染负荷的贡献率. 结果表明:研究区水体ρ(TN)、ρ(NH₄+-N)分别在0.07~16.73和0.01~10.65 mg/L之间,年均值分别为2.34和0.71 mg/L,空间分布呈入库河流高于库区的趋势；季节特征表现为春季、冬季>秋季>夏季. 2005—2014年库区水体ρ(TN)整体呈先升后降的趋势,其中取水口陶岔断面ρ(TN)上升较快,2012年较2007年增加了1.5倍,2013年开始ρ(TN)有所下降,但仍然维持在较高水平. 近10年来库区水体ρ(NH₄+-N)始终维持在较低水平. 神定河、犟河、泗河、剑河等环库支流河口氮污染最严重,城镇化是造成流域水体氮污染的主要驱动力. 汉江TN入库量贡献最大,占63.0%,其中境外来水TN入库量占总量的59.2%,为达到丹江口水库生态环境保护要求的Ⅲ类水质(GB 3838—2002《地表水环境质量标准》)目标,汉江TN需削减量为16 715.0 t/a. 境内河流中,环库河流的TN入库量最大,其中泗河、老灌河、神定河、金钱河、犟河和天河等TN入库量较大,TN需削减量分别为 2 286.7、2 197.7、1 493.6、1 106.9、979.1和728.9 t/a. 

Spatial and Temporal Distribution and Flux of Nitrogen in Water of Danjiangkou Reservoir

To study the spatial-temporal distribution characteristics and major pollution sources of nitrogen in water of Danjiangkou reservoir, spatial distribution, seasonal and inter-annual variability of nitrogen in water were analyzed. The driving force of nitrogen pollution was studied by regression analysis. Flux and contribution rate of pollution load of inlet rivers for nitrogen were estimated. ρ(TN) and ρ(NH₄+-N) in the water ranged from 0.07 to 16.73 and 0.01 to 10.65 mg/L, with the mean value of 2.34 and 0.71 mg/L respectively. Concentrations of nitrogen decreased from inlet rivers to reservoir area. Characteristics of seasonal variability were:spring, winter>autumn>summer. ρ(TN) increased first and then decreased during 2005-2014. ρ(TN) in Taocha, the water intake of the mid-route of the south-to-north water transfer project, increased faster, and ρ(TN) in 2012 was 2.5 times of that in 2007. ρ(TN) in Taocha decreased in 2013 but still remained at a high level. ρ(NH₄+-N) in the water remained at a low level in the recent 10 years. Nitrogen pollution in Shending River, Jiang River, Si River and Jian River was most serious. Urbanization was the main driving force for nitrogen pollution in water of Danjiangkou basin. Han River contributed the most nitrogen to the reservoir, accounting for 63.0% of the total nitrogen load. Nitrogen load of cross-border of Han River took 59.2% of the total. TN load of Han River decreased 16,5.0 t/a to satisfy the classⅢwater quality aim requested by Danjiangkou Reservoir area ecological environment protection. In the territory, rivers around the reservoir contributed the most nitrogen load, and the load of Si River, Laoguan River, Shending River, Jinqian River, Jiang River and Tian River were relatively high; TN in their water needs to be reduced 2,6.7,2,197.7,1,493.6,1,106.9,9.1 and 728.9 t/a separately.