Study On Water Quality Assessment And Variation Of Space-Time In Nansi Lake

In recent years, along with China’s rapid socio-economic development and continuing population growth, large quantities of untreated industrial wastewater and domestic sewage have been discharged directly into rivers, lakes and seas which leads to increasingly serious water pollution and decreased water quality. The increasing pollution of the water environment has been seriously constraining China’s socio-economic development, endangering the ecological environment and affecting the people’s lives and health.The Nansi Lake is the fresh water lake with abundant water and biology resources.It has multiple functions including flood control, irrigation, aquaculture and tourism. The water environmental protection question of Nansi Lake is paid attention all the time.Taking pH,NH3-N,COD and TN as main objective, the water quality was measured and evaluated from2006to2010, and the water quality variation was analyzed. The following achievements were obtained:1.In the75times measurement of the Nansi Lake water quality,74times were inferior to the III level of water quality standard, accounting for98.66%of the total; the times inferior to the V level of water quality standard reached13, accounting for44%of the total. The times of Nemero index between1.0--2.0, which was in lightly polluted water quality level, reached58, accounting for77.33%of the total. The times of Nemero index higher than2.0, which was in polluted water quality level, reached7, accounting for9.33%of the total. The indices exceeding the standard mostly were COD and TN.2. There were15times measurement of Qianbaikou sampling cross section, all of them were inferior to the III level of water quality standard,5times were inferior to the V level of water quality standard, accounting for33.33%of the total. The times of Nemero index between1.0--2.0, which was in lightly polluted water quality level, were12, accounting for 80%of the total15. The times of Nemero index higher than2.0, which was in polluted water quality level, were1, accounting for6.67%of the total15. There were15times measurement of Erjiba sampling cross section, all of them were inferior to the III level of water quality standard,2times were inferior to the V level of water quality standard, accounting for13.34%of the total. The times of Nemero index between1.0--2.0, which was in lightly polluted water quality level, were13, accounting for86.67%of the total15. There were15times measurement of Nanyang sampling cross section, all of them were inferior to the III level of water quality standard,3times were inferior to the V level of water quality standard, accounting for20%of the total. The times of Nemero index between1.0--2.0, which was in lightly polluted water quality level, were12, accounting for80%of the total15. The times of Nemero index higher than2.0, which was in polluted water quality level, were3, accounting for20%of the total15.There were15times measurement of Dajuan sampling cross section all of them were inferior to the III level of water quality standard,3times were inferior to the V level of water quality standard, accounting for20%of the total. The times of Nemero index between1.0--2.0, which was in lightly polluted water quality level, were13, accounting for86.67%of the total15. The times of Nemero index higher than2.0, which was in polluted water quality level, were2, accounting for13.33%of the total15. The times inferior to the III level of water quality standard of Daodong, up to14; one time was inferior to the V level of water quality standard, accounting for6.67%of15times measurement. There were8times in lightly polluted water quality level and one time polluted water quality level, accounting for53.33%and6.67%of the total15separately.3. The overall trend of the degree polluted of the five sections is downward from2006to2010. Five sections were all in lightly polluted water quality level or in polluted water quality level in2006. The degree polluted of five sections has been greatly improved,which was in lightly polluted water quality level or in cleaning water quality level.