Orthogonal experimental methods were applied to study effects of the joint action of eutrophication(nitrogen and phosphorus) and heavy metals(cadmium, lead and copper, zinc,chromium, arsenic etc.) pollution on growth and accumulation of the elements in Lemna minor L. and the desorption of elements in sediment by the cultivating test. And it is tried to find the principle of the combined pollution of eutrophication and heavy metals. The results showed that accumulation of the heavy metals in the plant mainly depended on the concentration in the water, and also depended on the nutrient level and co-existing elements of the water. High level of the nutrients could increase the primary production and partly low the toxicity of the heavy metals. The desorption of heavy metals in sediment obviously varied with the nutrient level in the water and with effctive order of Cd>As>Pb>Zn>Cr>Cu. There were certain correlations among the elements.
The current situation of water resources utilization: the contradiction between supply and demand of water resources is aggravating, water pollution is being serious and water crisis stands out. For the sustainable utilization of water resources, a series of countermeasures should be put forward, such as, to increase utilization radio of water resources; to build underground reservoir; to enforce legislation to protect water resources; to heighten the water protection consciousness of public.
