本 調査는 金海平野외 農業用水로 使用하고 있는 洛東江支流의 水質을 主要 揚水場附近 6個地點(대저, 식만, 봉림, 녹산, 마찰, 장유)에서 1981年 5月, 7月 및 10月의 3回에 걸쳐 採水分析함으로서 水質保全對策과 이 地域의 農業에 參考資料를 提供코자 하였다. 時期別 各 地點의 水溫, 濁度, 蒸發殘留物, pH, BOD, COD, DO, 硬度, Cl^-, SO₄^(--), PO₄^(---), NH₄^(+), NO₃^(-), K^+, Na^+, 一般細菌, 大腸菌, 重金屬(Cd, Pb, Cr, Fe, Zn)을 分析한 結果를 要約하면 다음과 같다. 1) 時期別 모든 地點의 平均値는 pH 7.8, BOD 6.3 ppm, COD 6.5 ppm, DO 6.4 ppm, 硬度 231 ppm, Cl^- 582 ppm, SO₄^(--) 412 ppm, PO₄^(---) 2.32 ppm, NH₄^+ 3.8 ppm, Na^+ 478 ppm, 大腸細菌 2964 個/100㎖, Cd 0.0040 ppm, Pb 0.006 ppm이었다. 2) 地點別 汚染度가 가장 높은 곳은 식만 揚水場附近이었고 그 다음이 대저, 봉림, 녹산이었으며 비교적 汚染度가 덜한 곳은 마찰, 장유揚水場 附近이었다. 3) 汚染度가 가장 높은 식만揚水場 附近의 水質은 약간의 臭氣가 있을 뿐만 아니라 外觀上 약간의 黑色을 띄고 있었고, 分析平均値는 pH가 8.0, BOD 8.1 ppm, COD 8.2ppm, DO 5.3ppm으로 農業用水基準의 限界에 到達하고 있었다. 이곳이 汚染度가 높은 것은 金海市의 主要 工場廢水가 이곳으로 集中 排出되기 때문인 것으로 본다. 4) 時期別 各 成分의 差異는 뚜렷한 傾向이 없었으며 다만 DO가 10月이 5月 및 7月보다 높게 나타났고 NH₄^+는 10月이 5月 및 7月에 比해서 낮게 나타났을 뿐이다. 5) 各 地點이 NH₄^+含量이 높아 室素質肥料의 施肥에 이를 考慮해야 할 것이며, Cl^- 및 Na^+含量은 平水時에는 別問題가 없을 것이나 渴水期에는 灌漑에 注意를 해야 할 것으로 본다.

Water quality of downstream of the Nagdong river, using for agricultural irrigation of the Gimhae plain, were observed. Water temperature, turbidity, residue, pH, BOD, COD, DO, hardness, chloride, sulphate, phosphate, inorganic nitrogenous compounds, sodium, general bacteria, E. coli and heavy metals of the water were investigated at Daejeo, Sikman, Bongrim, Noksan, Machal and Jangyou pumping stations in the Gimhae plain in May, July and October, 1981. The results obtained were as follows; 1) Average value of analyzed components of the water at all sampling sites were 7.8 pH, 6.3 ppm BOD, 6.5 ppm COD, 6.4 ppm DO, 231 ppm hardness, 582 ppm Cl^-, 412 ppm SO₄^(--), 2.32 ppm PO₄^(---), 3.8 ppm NH₄^+, 478 ppm Na^+, 2964 No. /100 ㎖ total coliform, 0.0040 ppm Cd, 0.0066 ppm Pb, respectively. 2) The most heavily polluted site of all investigated ones was Sikman. It seemed to be caused by the vast quantity of wastewater discharged from industrial district in Gimhae city. The next polluted sites were Bongrim, Daejeo and Noksan, and comparatively less polluted sites were Machal and Jangyou, judging from both appearance and physicochemical observation. 3) At Sikman, the most heavily polluted site, average value of components were 8.0 pH, 8.1 ppm BOD, 8.2 ppm COD. These values were close to the limit point of agricultural water quality standard of 8.0 ppm BOD (COD). 4) Any apparent variation was not observed by the sampling season in most components except DO and NH₄^+. DO of October was higher than that of May or July but NH₄^+ was low. 5) NH₄^+ content was comparatively high in downstream of the Nagdong river of which water is used as the agricultural irrigation in the Gimhae plain. Therefore, fertilizer application on the farming land must make account of nitrogen content of the irrigation water 6) It was considered that chloride and sodium contents would not influence the crop cultivation in common season, but in dry season irrigation must be done carefully.