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Studies of Soils, Soil Water and Stream Water at a Small Catchment near Guiyang, China
1998
Larssen, Thorjørn | Jiling, Xiong | Vogt, Rolf D. | Seip, Hans Martin | Bohan, Liao | Dianwu, Zhao
Acid deposition is considered to be a major environmental problem in China, but information about effects on soils and waters is scarce. To contribute to increased knowledge about the problem a small catchment (about 7 ha) in the outskirts of Guiyang, the provincial capital of Guizhou in south-western China, was instrumented for collection of precipitation, throughfall, soil water and stream water. In addition soil samples have been collected and analyzed for key properties. Median pH in the precipitation is 4.40 (quartiles: 4.19 and 4.77) and the median sulfate concentration 228 µeq/L (quartiles: 147 and 334 µeq/L). The dry deposition of both SO₂ and alkaline dust is considerable. The sum of wet deposition of sulfate and dry deposition of SO₂ has been estimated to about 8.5 gSm⁻²yr⁻¹. The total S-deposition may be somewhat higher due to dry deposition of sulfate and occult deposition. In soil water, SO₄ ²⁻ is the major anion, generally ranging from 300 to 2500 µeq/L in the different plots. Calcium is an important cation, but there is also a considerable contribution of aluminum from the soil. In some of the plots the concentrations of inorganic monomeric aluminum (Ali) are typically between 200 and 400 µm. Potential harmful levels of aluminum and/or high Ali/(Ca²⁺ + Mg²⁺) molar ratios occur in the catchment, but damages to vegetation have not yet been reported. In most cases exchangeable aluminum accounts for between 75 and 95% of the total effective cation exchange capacity (CECE) in the mineral soils. The aluminum chemistry cannot easily be explained by conventional models as the Gaines-Thomas ion-exchange equation or equilibrium with an Al(OH)₃ mineral phase. The stream water is generally less acidic and has considerably lower concentrations of aluminum than the soil water, even though quite acid events have been observed (pH < 4.4). The median pH values are 4.9 and 5.0 in the two first order streams and 6.3 in the dam at the lower boarder of the catchment.
Show more [+] Less [-]Occurrence of persistent organic contaminants and related substances in Hong Kong marine areas: an overview
1998
Connell, D.W. | Wu, R.S.S. | Richardson, B.J. | Leung, K. | Lam, P.S.K. | Connell, P.A. (Centre for Environmental Science and Technology, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China))
Changes in pH, CEC and exchangeable acidity of some forest soils in southern China during the last 32-35 years
1998
Dai, Z.H. (Chinese Academy of Sciences, Beijing (China). Research Center for Eco-Environmental Sciences) | Liu, Y.X. | Wang, X.J. | Zhao, D.W.
