Study on the Competitive Adsorption of Dimethoate with Multiple Pesticides and Heavy Metals Based on Fractional Factorial Design

Abstract

In order to reveal the composite contaminations characteristic of dimethoate adsorption onto the surficial sediments, the competitive adsorption of dimethoate in pesticide (dimethoate, metalaxyl, atrazine, malathion, and prometryn)/heavy metals (copper, zinc, lead, cadmium and nickel) system is investigated. A 210-5 fractional factorial design method at resolution IV and a multiple linear regression adsorption model are used to identify the main effects and interactions of above ten pollutions. The adsorption amount of dimethoate surficial sediments is set as the dependent variable, and the main effects and second-order interactions of ten pollutions are set as independent variables. Thus, a multiple linear regression model of dimethoate adsorption is screened and established. The results of model show that the main effects of Cd, malathion and prometryn performed a significant antagonistic effect (α=0.05) on the adsorption of dimethoate onto the sediment (competitive adsorption effects), and the order is: prometryn (-0.0925) > Cd (-0.0878) > malathion (-0.0827); while heavy metal Zn performed a significant synergy effect on the adsorption of dimethoate. The second-order interaction effects of Zn*prometryne, Pb*atrazine and Pb*atrazine has a significant antagonistic impact on the adsorption of dimethoate in sediments, which is in a sequence of Zn*prometryne (-0.0967) > Pb*atrazine (-0.0945) > Cd*atrazine (-0.0922). Moreover, according to the rate of contributions of main effects and second-order interaction effects in composite contaminations system, we can also estimate and definite the pollution levels of target pollutant.