Interference Adsorption of Cadmium with a Variety of Pollutants in Sediments Based on Fractional Factorial Design (Resolution V)

Abstract

The characteristics of composite cadmium contamination via adsorption onto the surficial sediments in a pesticide (dimethoate, metalaxyl, atrazine, malathion, and prometryn)/heavy metal (copper, zinc, lead, cadmium, and nickel) composite contamination system were examined. To do this, a confounding designassisted resolution V of 2 10-3 fractional factorial design method composed of a fixed effects model, a multiple linear regression model, and the best subset regression modeling methods was used to identify the main effects and second-order interaction effects of the aforementioned pollutants. Overall, 87.08% of the total contribution to cadmium adsorption derived from the main effect, and the main effects of copper, lead, zinc, and dimethoate had a significant antagonistic effect on cadmium adsorption on the sediments in the order of: copper (17.41%)>lead (13.09%)>zinc (10.06%)>dimethoate (5.03%), while the main effects of cadmium (41.49%) had a significant synergistic effect. Moreover, 12.92% of the total contribution to cadmium adsorption was attributed to second-order interaction effects (zinc*nickel and copper*zinc), with zinc*nickel (4.57%) having a significant antagonistic effect and copper*zinc (8.35%) having a significant synergistic effect on cadmium adsorption on the sediments. When compared with resolution IV of the 2 10-5 fractional factorial design method, the freedom of resolution V of the 2 10-3 fractional factorial design method increased from 21 to 45. This showed that resolution V of the 2 10-3 fractional factorial design method can significantly distinguish the aliases of the second-order interaction effects related to the objective pollutant cadmium. Also, the total contribution to cadmium adsorption of the second-order interaction effects decreased from 61.48% to 12.92%, indicating that resolution IV of the 2 10-5 fractional factorial design method overestimates the second-order interaction effect on cadmium adsorption on sediments.