Influence of Copper on Transport and Dissipation of Lambda-Cyhalothrin and Cypermethrin in Soils

Repeated applications of bordeaux mixture (a blend of copper sulfate and calcium hydroxide) and pyrethroid insecticides (Pys) have led to elevated copper (Cu) and Pys concentrations in vineyard surface soils. To understand the potential influence of Cu on the fate of Pys in the soil environment, we selected two Pys, cypermethrin (CPM) and lambda-cyhalothrin (λ-CHT), and two typical Chinese vineyard soils, Haplic Acrisol and Luvic Phaeozem, as experimental samples. The dissipation experiment was conducted at room temperature in the dark, and the transport of both Pys through the soils was investigated using soil thin-layer chromatography. The results showed that the transport of Pys in both soils increased as the Cu2+ concentration increased from 0 to 100 mg L−1, and Pys were more transportable in Haplic Acrisol (HA) than in Luvic Phaeozem (LP) under the same experimental conditions. For CPM, only 100 mg L−1 of Cu2+ significantly (P < 0.05) increased Pys transport through both soils relative to water. Lambda-CHT was significantly (P < 0.05) transported through HA by all the Cu2+ concentrations compared to water, and all but the 1 mg L−1 of Cu2+ significantly (P < 0.05) increased the transport of λ-CHT through LP relative to water. However, the dissipation rates of CPM and λ-CHT decreased with the addition of Cu to soils. Our findings suggest that the risk of groundwater contamination by Pys increases in the soils with elevated Cu concentrations.