Analysis of influence of enclosure aquaculture on water quality of Honghu Lake.

Influence of enclosure aquaculture on the water quality of Honghu Lake,Hubei Province was discussed. Change and trend process of water quality based on the measured data of the Lake from 1990 to 2006 were analyzed,and it was found that total nitrogen was out of limits markedly. Water quality was assessed through environmental contamination index method and compared in the enclosure positions with out of enclosure in different hydro-periods,as well as before the enclosure aquaculture with the after. Results showed that environmental contamination index in the enclosure positions was much larger than the outside in dry season. Enclosure aquaculture has polluted part of the Lake severely. Before the enclosure aquaculture,water quality conformed to Grade II in water classification,while after the enclosure,water quality in the Lake gradually deteriorated. There were some relationships between the area of enclosure aquaculture and degree of water quality deterioration. Content of total nitrogen changed obviously,which may increase sharply with increasing area of enclosure aquaculture.