Affiliations: College of Environment and Resources, Jilin
University, Changchun 130023, China | Song-Liao River Basin Water Resources Protection
Bureau, Changchun 130021, China
Abstract: Surface coatings and surficial sediments ware obtained in four
natural waters in Xianghai Wetland in China to study the role of surface
coatings and surficial sediments in controlling the transporting and cycling of
heavy metals in aquatic environments. Pb and Cd adsorption to the surface
coatings and surficial sediments were measured under controlled laboratory
conditions (mineral salts solution with defined speciation, ionic strength 0.05
mol/L, 25°C and pH 6.0 for surface coatings; and 0.005 mol/L
CaCl_2 solution, 25°C and pH 6.0 for surficial
sediments). The Langmuir adsorption isotherm was applied to estimate
equilibrium coefficients of Pb and Cd adsorption to the surface coatings and
surficial sediments, and the component analyses of surface coatings and
surficial sediments were also carried out. Correlation analyses between the
maximum adsorption of Pb and Cd (Γ_{max}) and the
components in the surface coatings and surficial sediments suggested that there
was a statistically significant trend for Pb and Cd adsorption
(Γ_{max}) to the surface coatings to increase with
increasing in contents of Fe and Mn oxides in the surface coatings and
surficial sediments. And the metal adsorption abilities of surface coatings
were much stronger than those of surficial sediments, highlighting that in the
same water, i.e. at the same pH and initial metal concentrations, the metals
(such as lead and cadmium) in supernatant were feasible to be adsorbed by
surface coatings than surficial sediments. The more importance of surface
coatings than surficial sediments for adsorbing and cycling of heavy metals in
aquatic environments was evidenced.
