Investigation and evaluation of water quality of Changsha Baili Aquatic Zone and its pollution control measures.

Field survey and laboratory analysis were carried out to study the water quality value changes and pollution distribution of the main culturing waters of Changsha Baili Aquatic Zone,and it used single factor index combining with the Nemero index to evaluate the quality of its water environment.The results showed that in summer(wet season),the exceeding standard factors are Chemical Oxygen Demand(CODcr),Biochemical Oxygen Demand(BOD5),Total Nitrogen(TN) and Total Phosphorus(TP) in water quality of main culturing waters in Changsha Baili Aquatic Zone.Those factors exceeded 3.4,6.5,3.5 and 1.9 times than type Ⅲ's limit of National surface water environmental quality standard(GB3838-2002).Nemero index of the water quality is 3.14,belonging to heavy pollution level Ⅳ;in winter(dry season),water quality has some changes.Those are DO dropping,ammonia nitrogen content increasing,but the main exceeding standard factors are still CODcr,BOD5,TN and TP.Nemero index of the water quality is 1.81 in level Ⅱ,which is a relatively light pollution.Different water sources,the types of geographical landforms and cultures are closely related to the culture water environment quality.The measures to prevent and control culture water pollution are reducing endogenous pollution and eliminating external pollution sources,in addition,taking other measures to improve self-purification capacity of waters,and eutrophicated waters can be discharged into farmland for consuming.Those are in order to ensure the efficiently using of water resources and the sustainable development of aquaculture.