Abstract
Conditions of watershed and rivers are closely connected with coastal environments. Suspended sediment is important to water quality on the coast. In particular, at times of flooding a large quantity of suspended sediment is transported to the coast, and the majority of phosphorus is transported in particle form rather than dissolved form. But not all sediment phosphorus circulates to the coast, for example apatite phosphorus. For this reason, a quantitative analysis on the chemical form of phosphorus was conducted. Suspended sediment was sampled during flooding of the Ishikari, Shiribetsu and Mukawa rivers, and the phosphorus chemical combined forms of the samples were analyzed. The results show that more than 60% of the phosphorous in the suspended sediment is circulating phosphorous, and that the total phosphorous content is related to the suspended sediment diameter and is different for each river according to land use.
