한강하류의 환경학적 연구 I. 수질

Abstract

A two-year study programme has been launched in order to investigate environmental assessment on the biotic communities and physicochemical factors in the lower part of Han River. The purpose of this study is to clarify the water quality and to provide the basic physicochemical data for the goal mentioned above during the period from June 1995 to June 1996. Water temperature ranged from 1.6℃ in January 1996 to 26.1℃ in June 1996 and it showed a similarity to that of air. Difference in temperature (△t) between the intake and the discharge of Seoul fire Power Plants was 7.0℃ in January 1996 which was the highest in the investigated period, while △t was 1.9∼4.6℃ in summer with less degrees in difference. Seasonal mean variations of DO were 8.05 mg/L in January, 7,73 mg/L in October, 6.60 mg/L in July, 5.07 mg/L in May, 3.57 mg/L in June 1995 and 4,86 mg/L in June 1996. Monthly variations of average pH among 7 stations were almost constant values of 7.29∼7.51. Average concentrations of phenols were in the range of 0,002∼0.008 mg/L except a value of 0.016 mg/L In July 1995. The lowest value of BOD was 0.70 mg/L in October 1995, while relatively higher BOD values of 7.24∼8.34 mg/L were found in May and January 1996. In the average COD among 7 stations, the highest value of 8.19 mg/L was found in October, 1995 in contrast to BOD value, while COD values in the other months varied in the range of 2.09∼4.43 mg/L. Seasonal mean turbidity varied from 3.63 mg/L in January to 30.0 mg/L in the rainy season of July 1995. The lowest value of hardness was 35.5 mg/L in July and the highest was 82.6 mg/L in January. Monthly average concentrations of nutrients among 7 stations were as follows: 0.06∼0.117 mg/L of N-nitrite, 1.42∼2.42 mg/L of N-nitrate, 0.100∼0.376 mg/L of N-ammonia, 0.025∼0.20 mg/L of phosphorus and 0.87∼12.6mg/L of silicate were found. Concentrations of soluble nitrogen and phosphorus have been increased in comparing with the previous studies. Cadmium was not detected in any of the stations in October 1995 and June 1996. In the other months cadmium was found at low concentrations in the range of 0.0002∼0.0024 mg/L. Monthly average concentrations of zinc among 7 stations were low in the range of 0.0032∼0.1400 mg/L. Lead was hardly detected in any of the stations in May 1996. In the other months lead was found at relatively low concentrations in the range of 0.0022∼0.0361 mg/L.