猿別川流域における硝酸性窒素及び亜硝酸性窒素の負荷

概要

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The surveys of water quality and water flow rate were made to estimate the loading of nitrate nitrogen (NO3-N) and nitrite nitrogen (NO2-N) in the Sarubetsu River basin. In four surveys over the wide range of the Sarubetsu River basin in 2001, the loading of NO3-N and NO2-N at the Yamuwakka Bridge, the lowest survey point in the main stream, was calculated to be 51.94±18.60g/s, equivalent to 1638 ton-N/y. The loading ratio of NO3-N and NO2-N at the middle courses of the main stream was 62-94% in the four surveys. Some tributaries, such as the Sarabetsu River and the Itarataraki River flowing into the main stream at the upper to middle courses, were found to contribute largely to the loading of NO3-N and NO2-N. Calculation on amount of nitrogen supplied to land in the Sarubetsu River basin gave the value of 2689 ton-N/y, based on several data such as land area, population, number of livestock and amount of fertilizer usage. Fertilizers and excreta of livestock were presumed to be the main sources of loading of NO3-N and NO2-N in the Sarubetsu River basin.
北海道立衛生研究所の論文
2004-11-30