Residues and Organic Contaminants in Agricultural Soils in Intensive Agricultural Areas of Spain: A Three Years Survey

Abstract

AbstractA three‐year study of the levels of pesticide residues and organic contaminants in agricultural soils has been carried out in an important intensive agricultural area in Spain. Although traditional farming practices are being replaced by integrated pest management programs (IPMs), extensive phytosanitary application and inadequate farm practices (e.g. burning of vegetable and plastic material) have been carried out during decades, and occurrence of residues and persistent pollutants was expected. The monitoring program was divided into three samplings (one per year), evaluating pesticides, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls. In the first sampling, 38 agricultural soil samples were evaluated; multivariate analysis was used to select the most representative samples and continue the monitoring study. Then, the second and third samplings were performed to study the evolution of the concentration (including transformation products) of the compounds. Applying univariate and multivariate analysis, it was observed that PAHs (except anthracene and benzo[k]fluoranthene) were the most significant compounds, as well as some degradation products of banned pesticides (endosulfan ether, o,p′‐dichlorodiphenyldichloroethane and p,p′‐dichlorodiphenyldichloroethylene). Finally, a reduction of the concentration of contaminants was observed along the three years sampling period, indicating that the improved practices used in the area, such as IPMs, are having the desired effect regarding the reduction of contaminants in soil.