入冬水生高等植物的衰亡对河流水质的影响

上海市郊河流水体中有很高的氮、磷和有机负菏，由于受水生高等植物生灭的影响，初春河流中的氮、磷和有机负菏明显高于上一年的初冬，河流中的水生高等植物能大量地吸收水体中的氮、磷，抑制藻类生长，净化水质；但其植株残体在水中的腐解，又会重新释出营养元素，造成对水体的二次污染。在冬季，随着水生高等植物的大量死亡这种污染更加明显，应加强对水生高等植物的利用，尝试建立既能净化水质，又有创造经济效益的生态工程模式，使市郊受污水体得到资源化利用。

Effect of Aquatic Higher Plants Withering through Winter onWater Quality of Creeks

High loads of nitrogen, phosphorus and organic matters have been found in the water of creeks, outskirts of Shanghai. Because of the death of aquatic higher plants during the cold winter, nitrogen, phosphorus and organic loads in the creeks at the beginning of the spring were higher than that before last winter. Aquatic higher plants in the creeks could take up a large amount of nitrogen and phosphorus in the rivers, inhibit algae growth and purify water. However, owing to the decay of the plants in water, the nutrients once taken up by them would be released, resulting in the second pollution of the water. In winter, with most of aquatic higher plants withering, such pollution was even more serious. The aquatic higher plants naturally growing in waters should be used and managed properly. The bio-engineering projects, which can not only purify the water, but also gain economic profits, were discussed and suggested. By such way, the polluted water in the outskirts of Shanghai would be utilized as resources.