Abstract:

To investigate the effect of coexistent heavy metals on atrazine adsorption onto sediments (surface coatings) before and after the selective extraction treatments in the atrazine-Cd/Cu coexistence systems, a chemical extraction technique was employed to separate non-residual components (Fe/Mn oxides and organic materials) in sediments (surface coatings). The results indicated that the greatest contribution to atrazine adsorption on a molar basis is from Fe oxides and next is from organic materials in the coexistence system, while Mn oxides restrain atrazine adsorption. It was also found that coexistent Cd promoted atrazine adsorption onto original sediments (surface coatings) and each non-residual component, and the promotion was significant at 0.2 mg/L of Cd, with the adsorption contribution of atrazine onto Fe/ Mn oxides and organics enhanced by 3.20%-32.31% for sediments and 1.61%-17.10% for surface coatings, but this simulative effect was generally weakened with increasing concentration of cadmium. Meanwhile, coexistent Cu could restrain atrazine adsorption onto original sediments (surface coatings) and Fe oxides, organic materials, and atrazine adsorption was inhibited most distinctly at 75.0 mg/L of Cu，at this time, the adsorption contribution of atrazine onto Fe oxides and organics reduced by 29.21%, 22.36% for sediments and 9.46%, 77.27% for surface coatings, but coexistent Cu could also reduced the inhibition of artazine adsorption onto Mn oxides by 28.98% (sediments) and 17.46% (surface coatings), respectively.

Key words: sediments, surface coatings, non-residual components, selective extraction technique, atrazine, Cd/Cu, adsorption