Investigation on changes in water quality of Duobao reservoir in different seasons

In order to monitor and evaluate the water quality and explore the characteristics of water pollution of Duobao reservoir,water samples were collected during July 2011 to November 2012.And the pollution status was evaluated with the single and comprehensive index methods.Heavy metals and antibiotics concentration of Duobao reservoir water were also detected.The possible sources of the pollution were also discussed in detail.The single index evaluation results showed that the annual average values in the main part water of Duobao reservoir were over the standards of grand V for the surface water environment quality of China.The main pollution factors were total phosphorus,total nitrogen,ammonium nitrogen and BOD.And the organic pollutant comprehensive index method evaluation results indicated that the main part water of Duobao reservoir were ranked ordinary level in winter and ranked polluted seriously or moderately level in other seasons.The main sources of pollution may be the wastewater discharged from pig breeding farms in the upstream.The water in the discharge area of pig farm waste water was serious polluted and the water quality was over the standards of Grand V.The main pollution factors were the same as in the main water body.In the main water,the concentrations of Cu,Zn,As were very low even couldn't detect,only the Mn contents exceeded the standards for the surface water environment quality in the spring and autumn.Chloramphenicol and tetracycline were detected in the reservoir water,and its content of water in the vicinity of pig farms reached 5.35 and 18.56 μg/L,respectively.These results indicated that Duobao reservoir pollution mainly came from the pig farms discharging waste water in upstream.