Analysis On Pollution Characteristics Of Tieling Watrshed

This article analyzes the pollution characteristics of 22 rivers(52 sampling sites) in Tieling watershed. The in situ investigation was carried out over the period of 2013.7-2014.7. The aim of the study is to understand the temperal and spetial distribution and sources of riverine pollutants. Issues measeured in water samples in the study include p H, total nitrogen, total phosphorus, ammonia, nitrate, phosphate(as P), BOD5, nitrogen and oxygen isotopes in nitrate. The main conclusions are as follows:(1) The concentrations of total nitrogen, nitrate nitrogen and ammonia presented a clear trend that dry season > normal water period > wet period. Nitrogen concentration in the western rivers is higher than tant in the eastern rivers. Nitrate is the major component of total nitrogen, acount for 75% of the TN. Ammonia nitrogen is the characteristic contaminant in rivers of Tieling watershed.The total dissolved phosphorus accounts for 76% of total phosphorus. Concentration of TP was significantly higher in normal water period than that in dry and wet seasons.(2) Concentration of CODMn ranges from 1.11 to 23.62 mg / L during the study period, with an annual mean value of 4.86mg/L. The annual mean concentration of CODMn was higher in normal water period than wet and dry season. Concentration of BOD5 ranged 2.17~40.80 mg / L with an annual mean value of 7.64mg/L. The higher concentration of BOD5 was observed in dry season.(3) Single-factorial and Comprehensive Evaluation methods were selected to assess the water quality of the 22 studied rivers. Results showed that two evaluation methods distinguished the same main pollutants in 48 of the total 52 sampling sites. The main pollutants in rivers were BOD5, ammonia nitrogen and TP.(4) Nitrogen and oxygen isotope in nitrate was measured to analyze the source of nitrogen in the studied rivers. δ15N and δ18Oaveraged +9.7‰ and +1.8‰ respectively. Riverine nitrogen was mainly derived from livestock excreta(11 rivers) and industrial waste water(8 rivers). However, nitrogen sources changed with time. For example, nitrate in Tiaozi, Nianpan Rivers mainly derived from fertilizer and soil nitrogen in the wet season, while mainly derived from industrial waste water in dry season.