Biodegradation of simazine in olive fields.

Simazine (2-chloro-4, bis ethylamino-1,3,5-triazine) is a herbicide of the s-triazine group used mainly to control broad-leaved weeds in different crops. Several papers report about simazine and other s-triazine derivates as being actual polluting agents. In fact, simazine has been detected in groundwater and soil. Since this herbicide has been extensively used in Andalusia (south of Spain), we are analyzing the levels of simazine residues found in the soil of olive fields. We are also simazine could be detected isolating live micro organisms able to degrade this compound, and are characterizing the metabolic pathways leading to this degradation and the fate of this compound in nature. With all these data in mind, we will try to develop a strategy for the bioremediation of contaminated soils. We have taken samples of soil from many olive orchards of Andalusia that have been treated with simazine. These samples were located with the help of a handheld GPS. The presence of simazine of these samples was detected by HPLC. In most of the samples taken no, and those where it could be, contained very low levels of this herbicide (lower than 0.5 ppm). Soil samples are being characterized to determine their physicochemical characteristics [pH, organic matter, texture, etc), and we are attempting to correlate all these parameters with the presence or absence of simazine. From some of the soils, we have isolated a group of micro organisms that can grow using simazine as the sole carbon and nitrogen sources. We are analyzing how the addition of carbon or nitrogen can influence the rate of the simazine degradation.