Assessing the hydrogeochemical impact and distribution of acid sulphate soils, Heart Morass, West Gippsland, Victoria

摘要: The hydrogeochemical processes associated with the precipitation and oxidation of pyrite during development acid sulphate soils was investigated in coastal floodplain environment Heart Morass, Victoria, Australia. During drought conditions 2009, low-lying areas (0–2 m elevation) were most affected by soils, a median soil pH (pHF) 3.56 to approximately 50 cm depth. Soils below ∼100 cm depth these contain have reduced inorganic S concentrations up 0.85 wt%. Higher (2–6 m) do not 4.74 depth, an average neutralising capacity 3.87 kg H2SO4/t, no appreciable unoxidised pyrite. In Co, Ni, Zn, Mn Fe increased from <2.0, 4.0, 10, 20 2000 mg/kg, respectively, at 56 cm 20, 45, 152 15,000 mg/kg 221 cm higher elevation, Zn 6, 11, 21 12,500 mg/kg 44 cm 19, 47 19,400 mg/kg 239 cm These data indicate acidic leaching metals upper profile both more elevated areas. lowest Al, Fe, Ni surface water or pit 2.43, 0.06, 2.90, 2.89 0.09 mg/L, respectively. are 1–2 orders magnitude than any potential sources around morass can be accounted for evapotranspiration, indicating into groundwater. Excess SO42- central area characterised molar Cl:SO4 ratios <5 δ34S values <10‰. combined define zones depletion reduction (Cl:SO4 ∼ 24, δ34S = 22.7‰) contemporary SO4 enriched oxidised pyritic (Cl:SO4 = 9.9, δ34S = 26.2‰). Average decreased 129 g/kg 15.2 g/kg after flooding 2011, suggesting dissolution mineral salts accumulated profile. Cr Cu 9,522, 18.4, 17.0 14.4 mg/kg 12,800, 22.4, 22.6 22.4 mg/kg flooding, that metal is result changing redox chemistry flooding. This highlights need continuous measurement sampling flood events order better constrain processes.