PROBLEMS OF WATER POLLUTION AFTER THE WATER GATE CONSTRUCTION AT THE MOUTH OF THE NAGARA RIVER

From last year, the water gate construction started at the mouth of Nagara River. There are two purposes for the construction of the gate; one is to control the flooding, another is to obtain a water resource. Regarding the former problem, the Water Resources Development Public Corporation, planned to deepen the river bottom in order to expand the area of the river section. But the deepening of the river bottom would lead the flow of much more seawater into the upper stream than at present. The authorities of the above corporation have emphasized the necessity of gate to eliminate the influence of seawater by possible rice field damage due to saline water which might penetrate through the bank. I will discuss the water pollution problems after the construction of gate at the mouth of river.Article信州大学理学部付属諏訪臨湖実験所報告 7: 121-128(1991)departmental bulletin pape

Physicochemical features of rivers and lakes in pantanal wetland

The Pantanal is one of the largest wetland in the world, and its located almost in the central part of South America. Preliminary studies on the chemical features of waters were carried out in July, 1983 in Rio Paraguai and its tributaries in southern Pantanal, and in January, 1986 for some lakes near Porto Jofre and a river in northern Pantanal. The former showed an extremely oligotrophic character and the latter a eutrophic character, while the nitrogen seemed to be the limiting nutrient rather than phosphorus in both waters. The oxygen deficiency in water seemed rather common throughout the area studied in spite of the difference in water temperature and the organic matter contents.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq