Gyoo Ho Lee

Effect of mining and geology on the chemistry of stream water and sediment in a small watershed

Chemical characteristics of the stream water and sediment in the small watershed with two distinctive mineralization zones (Cu and Pb−Zn), 7 abandoned mines and an active quarry were investigated to examine the effects of mining activity and regional geology on the chemistry. The stream water affected by the abandoned mines had Ca−SO4 type but the other had Ca−HCO3 type. The mine affected stream water and sediment showed relatively high concentrations of metals (Cu, Pb, Zn, Cd, Co, Ni, Mn, Al and Fe). The concentrations of Al, Mn, Fe and Cu of the stream water collected near an abandoned mine (Guryong) exceeded the EPA surface water quality standards (Al: 5.52 mg L−1, Mn: 1.58 mg L−1, Fe: 1.49 mg L−1, Cu: 0.63 mg L−1). The effect of mining activity on the stream water chemistry was attenuated in a relatively short distance from the source (<200 m) along the watercourse but the signature in the sediment showed a longer lasting effect (about 2 km) than that in the stream water: The residual and reducible forms were the dominant fractions of the heavy metals in the stream sediment. The particulate trnnsportation was the major cause of the dispersion of heavy metals in the watershed. There was a contrasting spatial distribution of background metal concentration in the stream sediment: a relatively higher concentration of Cu in the Cu mineralization zone and a relatively higher concentration of Pb, Zn and Mn in the Pb−Zn mineralization zone.

Soil characteristics and phosphorus accumulation in surface soil in relation to geological and land-use conditions

Abstract Effects of parent rocks and types of land use on soil physical and chemical properties and the phosphorus (P) accumulation in surface soil were examined in a small watershed. The soil developed from granite with a coarse texture, and felsic chemical and mineralogical compositions showed a coarser texture, lower contents of organic matter, water-soluble cations and anions and a lower cation exchange capacity (CEC) than soil developed from andesite. Farmland soils exhibited higher pH and electrical conductivity values, a lower ignition loss and CEC and a coarser texture compared with forest soils from the same parent rocks. The farmland soils contained greater amounts of total P, water-soluble reactive P, organic P and adsorbed inorganic P, and showed a higher degree of P saturation (DPS) than the forest soils in the following order: upland field > orchards > paddy fields > forest. The DPS of the farmland soils (28.2–93.1%) indicated that the soils showed a high potential to release P in the surface water and that careful management was required to reduce P release for the preservation of surface water quality.