在大量详实资料和调查基础上,论述了呼伦湖富营养化状况,找出了该湖富营养化的影响因素,以及其较强自净功能的成因。呼伦湖地处内陆区高纬度、半干旱气候地区,属牧业污染型,氮入湖量主要来源于点源污染(河流的输入),磷入湖量面源(主要是降尘)大于点源。经多年观测发现,氮和磷的变化并不明显,反映出湖体有较强的自净功能,这是和湖体特殊的地理位置分不开的:①该湖系构造湖与河流沟通的吞吐湖,面积大,水较深,使得湖体自净功能显著;②地处高纬度、半干旱地区,气温低,对湖体浮游生物有一定的抑制作用;③湖体构造特殊,露出30余个泉点,有大量地下水的补给。呼伦湖是一个较大的水体与其周围湿地构成的淡水湖泊生态系统,在维持生物多样性和丰富的生物资源方面发挥巨大作用,且有明显的调蓄洪水的功能,在区域环境保护中具有特殊的地位。

Based on a vast amount of full and accurate data and investigations,this paper dis cussed the eutrophication state of Hulun Lake and found out key factors influencing eutrophica-tion and causes of relative strong self-purification function of the lake.Hulun Lake is the fifth largest lake in the semi-arid continental climate region of high latitude in China.It belongs to animal husbandry pollution.The nitrogen input to Hulun Lake mainly comes from polluted point sources(the rivers),while phosphorus input from area source is more than that from point sources.Through many years observatuion s,it is found out that the changes in nitrogen and phosphorus content s are not obvious,indicating the existence of a strong self-purification function of Hulun Lake.The self-purification function of Hulun Lake is related to its special geographical position.First,Hulun Lake is an alternately inflow-outflow lake linking tectonic lake and rivers with vast area and deep water.All of these con tributed to the self-purification function of the lake.Second,the activity of planktons in the lake is restrained by the higher latitude,semi-arid climate and low temperature.Third,the structure of the lake is special with over30mouths of springs and sufficient replenishment of underground water to the lake.Hulun Lake is a freshwater lake ecosystem consisting of a relative large water body and its surrounding wetlands.It not only places an important role in keeping biodiversity and enriching biological resources,but also functions obviously in adjusting and impounding flood s.Consider-ing its ecological and social benefits,Hulun Lake is indispensable to the development of commu-nity and industry,agriculture and animal husbandry.All of these showed that Hulun Lake bears an important position in the regional environmental conservation.