Chemical Characteristics of Pore Water in Anoxic Sediment at Naha Port, Okinawa

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We investigated the chemical characteristics of estuarine environments comprising seawater, pore water and sediment at Naha Port, Okinawa. Alkalinity, sulfate and uranium in seawater column (-4 m) showed conservative behavior while nutrients and iron nonconservatively behaved. The average uranium content in the water column was found to be 3.34 μg/<I>l</I>Salinity, alkalinity, pH, phosphate and silicate in sediment pore water increased with sediment depth whereas Eh, sulfate, manganese, iron and nutrients in pore water decreased concurrently. Absence of nitrate below 10 cm of a sediment core and decrease in Eh value of the core indicate a gradual reduction towards sediment depth. Sulfate to salinity ratios in pore water decreased with the core depth. In pore water, uranium concentration was higher in the upper layer and it decreased with increasing core depth. No decrease in<SUP>210</SUP>Pb activities was found in core A with increasing sediment depth. Uranium content increased with core depth and indicates that uranium deposited in deeper sediment. Our observations suggest that port environments are likely to be altered due to urban development and waste water seepage from hinterland. Well-planned managements are necessary to maintain suitable environments of a port.
日本環境化学会の論文