Objective To evaluate the quality of water environment in the South Lake Park by using fuzzy mathematics comprehensive evaluation method, cumulate water quality data, and provide scientific basis for making a feasible water protection plan and administration measures.
Methods Thirteen sampling points were selected from three major lakes, including Xixing Pool, Yanglong Lake and Qingtianjing in Tangshan South Lake Park. Water samples were collected from shallow water (0.5 m under water surface) of thirteen sampling points continuously for three days in each month during April, May and June in 2014. Main pollutants were measured, and then the fuzzy mathematics comprehensive index was calculated to evaluate the water quality of three major lakes and whole South Lake.
Results The rate exceeded the national standard limit of total phosphorus, total nitrogen, ammonia and nitrite nitrogen was 88.89%, 77.78%, 33.33% and 22.22%, respectively. The concentrations of cyanide, volatile phenol, sulfide, fluoride and heavy metals were lower than the national standard limits. The qualified rate of these three lakes was 55.56%. The frequencies of water quality reaching to class Ⅱand Ⅲ were 11.11%, reaching to class Ⅳ and Ⅴ were 33.33% and 44.44%, and never reaching to class Ⅰ.
Conclusions The main pollutants that affected the overall water environmental quality were total phosphorus, total nitrogen and ammonia. The water quality of Xixing Pool and Yanglong Lake was in class Ⅳ, and Qingtianjing was in class Ⅴ. The overall water quality of South Lake Park was in class Ⅴ. The water quality of Yanglong Lake was the best, followed by Xixing Pool and Qingtianjing.
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