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No.75 (2003/3) >

Title :Impacts of acidic red soil on pH and aluminum under the soil-seawater interacting environment
Authors :Kombo, Mohamed M.
Vuai, Said Ali
Tokuyama, Akira
Authors alternative :渡久山, 章
Issue Date :Mar-2003
Abstract :The study was conducted to investigate the impacts of acidic red soil, on chemical composition of seawater. Two samples of red soil from Gushikawa recreation center (GRC) and Okinawa royal golf club (ORGC) were used for the experiments. Different weights (1, 3, 5, 10, 15, 20, 30, and 40 g) of bulk soil, ground bulk soil, coarse sand and silt+clay fractions were shook with 100mL of filtered seawater to obtain seawater extracts. The pH, EC and concentrations of Na^+, K^+, Ca^<2+>, Mg^<2+>, Al^<3+>, dissolved SiO_2, SO_4^<2->, Cl^- and HCO_3^- were determined in the seawater extracts. Results showed a considerable decrease in pH, which was inversely related to released Al. The pH ranged from 8.13 (seawater) to 3.85 and 4.06, while Al ranged from $\sim$0.00 mgL^<-1> (seawater) to 53.94 and 52.51 mgL^<-1> in 40 g/100mL for GRC and ORGC silt+clay fractions, respectively. The decreases of the ions especially K^+ and SO_4^<2-> was a common feature where K^+ decreased by 22.60 and 32.90% while SO_4^<2-> decreased by 16.90 and 14.70% in silt+clay fractions for GRC and ORGC samples, respectively. The dissolved SiO_2 increased from 0.42 mgL^<-1> (seawater) to 34.23 and 32.43 mgL^<-1> in 40 g of coarse sand for GRC and ORGC samples, respectively. The HCO_3^- decreased from 139 mgL^<-1> in the seawater to 1.58 mgL^<-1> in 10 g/100mL of silt+clay, and was not detected from 15 g/100mL. The increase in Al concentrations that was concomitant with decrease in the major cations suggested the adsorption and/or ion exchange reactions while the lowering of pH was likely due to the dissociation of H^+ from the soil mineral edges, exchange and hydrolysis of Al.
Type Local :紀要論文
ISSN :0286-9640
Publisher :琉球大学理学部
URI :http://hdl.handle.net/20.500.12000/5385
Citation :琉球大学理学部紀要 = Bulletin of the College of Science. University of the Ryukyus no.75 p.75 -87
Appears in Collections:No.75 (2003/3)

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