抄録
This paper regards the behaviour of iron and manganese in an aquatic environmnd from the viewpoint of thermodynamics. The important oxidation states of metals are bi —and tri—valency for iron,and tri—and quadri — valency for manganese in water. The metal concentration is determined by certain environmental conditions, such as solubility of metals, themodynamic states of pH,Eh and electron activity,other metal concentration in water,organic and inorganic chelate agents,organics,clay,carbonates,oxidizing agents and so on. The behaviour of iron and manganese in lakes depends on the seasonal cycle of water mass,which causes changes in the dissolved oxygen concentration in water. Iron and manganese precipitate under the oxidation state and dissolve under the reduction state from sediments. Heavy metals in sediments (Cd, Zn, Pb, Ni, Cu) were determined by atomic absorption spectrometry. Correlation analysis among the metal concentrations in sediments was done. High correlation coefficientss were obtained between two metals. Probability distributions of metal concentration in sediments were disscussed. Most metal concentrations showed logarithmic normal distribution. Different chemical species of metals in sediments were partitioned into selective chemical fractions.
