Nitrogen pollution and spatial distribution pattern of Wuliangsuhai Lake
Nitrogen pollution and spatial distribution pattern of Wuliangsuhai Lake
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作者：
He-Long Jiang
五粮素海是中国草原地区具有代表性的内陆淡水湖之一。近年来，湖泊不断萎缩，富营养化现象严重。本文系统地解释了地表水和沉积物岩心中总氮（TN）、铵态氮（NH~+_(4)-N）、硝态氮（NO~-_(3)-N）和有机氮（orgn）的空间分布规律。结果表明：地表水TN平均含量为1.78mg/L，主要无机氮污染物为NH~+_(4)-N，占水体无机氮的69%以上；表面沉积物的氮空间分布模式表明,氮含量湖的西部高于东部和氮的主要物种是Org-N超过95%的TN.Furthermore基于沉积物质量评价指南制定的生态毒性作用的环境和能源部门的安大略省,加拿大,1992年,TN表面沉积物的内容具有一定的生态毒性作用更多严重的;富营养化过程分三个阶段进行，表明富营养化过程加速始于20世纪90年代。五粮素海表层水和底泥岩心TN含量、形态分布和空间分布格局表明其污染具有外源和内源污染的特征。外源污染主要是农田排水和工业废水，分别占总氮负荷的50%和35%，通过主排水渠、第8和第9排水渠排入湖泊。在一定条件下，内源负荷可将氮释放到地表水中，使其成为主要污染源。除了外源污染和内源污染外，强烈的蒸发加速了五粮素海的富营养化过程，也是造成表层和现代沉积物氮积累的关键因素。
Wuliangsuhai Lake is one of the representative inland freshwater lakes in grassland area in China.Recently,the lake is shrinking and eutrophication has become serious.This paper interpreted the spatial distribution patterns of total nitrogen(TN),ammonium nitrogen(NH~+_(4)-N),nitrate nitrogen(NO~-_(3)-N) and organic nitrogen(Org-N) in surface water and sediment cores systematically.The results revealed that the average content of TN was 1.78mg/L and the main inorganic nitrogen pollutant was NH~+_(4)-N which accounted for more than 69% of the inorganic nitrogen in surface water;spatial distribution pattern of nitrogen in surface sediment indicated that the nitrogen content in the west of the lake was higher than in the east and the main species of nitrogen was Org-N which was more than 95% of TN.Furthermore based on the Sediment Quality Estimation Guide which was enacted in terms of ecological toxic effects by Department of Environment and Energy of Ontario Province,Canada,1992,the content of TN in surface sediment has certain ecological toxic effects which are more serious;the content of nitrogen decreased with depth and the eutrophication process existed in three periods which revealed that the acceleration of the eutrophication process dated back to the 1990s.The content,speciation distribution and spatial distribution pattern of TN in Wuliangsuhai Lake′s surface water and sediment cores indicated that its pollution was characterized by exogenous and endogenous pollution.The exogenous pollution was mainly the drainage water from farmland and industrial wastewater,which accounted for 50% and 35% of the TN load respectively,pouring into the lake through the main drainage canals,the eighth and the ninth drainage canal.And under certain conditions,the endogenous load could release nitrogen into surface water and make it the main pollution source.Besides the exogenous and the endogenous pollution,the intense evaporation,which accelerated the eutrophication process of Wuliangsuhai Lake,was also a key factor which caused nitrogen accumulation in the surface and modern sediments.