Effects of soil loading on the phosphorus cycle in estuarine and coastal marine environments
1995
Tanaka, K. (Nansei National Fisheries Research Inst., Ono, Hiroshima (Japan))
It is well known that phosphorus is an important component in the eutrophication of coastal marine environments and the major source of phosphorus are from the input of rivers and from the release from coastal sea sediments. However, little is known about the nature of phosphorus in riverine suspended matter and in the sediments and their behavior in estuarine and coastal marine environments. The release of phosphorus from sediments under anaerobic conditions in eutrophic coastal waters has been investigated experimentally in order to explain the origin of the eluted phosphate. The results indicate that the origin is inorganic phosphorus rather than organic phosphorus. Terrestrial soil substances contain a large amount of inorganic phosphorus together with organic phosphorus. Therefore, the origin of inorganic phosphorus in sediments and its loading process can not be clearly understood without further information on riverine suspended matter. In this study, phosphorus in riverine suspended matter was investigated for its chemical nature and its behavior in coastal marine environments. Phosphorus in the suspended matter and in coasts marine sediments was divided into four forms: CDB-P (citrate-dithionite-bicarbonate extractable phosphorus), NaOH-P(1N-NaOH extractable phosphorus), HC1-P(1N-HCl extractable phosphorus), and organic phosphorus (Org-P), following the fractionation scheme of Williams et al. (1976a). Adsorbed phosphate (Ads-P) which desorbs rapidly in sea water was also measured by the seawater extraction technique
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