RISK INDICATORS FOR AGRICULTURAL USE IN OIL-CONTAMINATED SOILS

Oil activities have mainly affected the tropical zones of developing countries, and these effects have been difficult to measure due to the lack of in-situ monitoring indicators in agricultural areas. We determined the physical and chemical properties of soils sampled from four villages situated on the floodplain of the Tonala River in Tabasco, Mexico, and we analyzed the productive characteristics and total petroleum hydrocarbon (TPH) content in each site. The aim was to assess the potential risks affecting agricultural use in areas with or without oil wells. Three indicators were developed: the productive diversity index (PDIx), the productive rate risk index (PRx), and the efficient land use index (ELUIx) for farming systems (crop plants [p] and animal rearing [a]). Results indicate that the main limiting factors for farming are the flooding characteristics of Gleysols, high salinity, and contamination by hydrocarbons, and that these were related to higher values of PRa,p, which were recorded from zones with elevated density of oil facilities. High PDIa,p and ELUIa,p values were found in zones without oil facilities that had a greater production of crops and pastures and lower associated risk factors that are related to the presence of oil wells or soil contamination by TPH, but also to related secondary effects. These results allowed a comparison of potential risk assessment in areas with similar ecosystems, differentiating the diversity and the efficiency of productive land use related to polluted zones.