Occurrence of Pesticides in Groundwater and Topsoil of the Gaza Strip

Agricultural activities in the Gaza Strip have been associated with excessive and uncontrolled use of dozens of pesticides. Accordingly, groundwater and soil are potentially contaminated causing severe threat to the crowded population. The present study describes a 3-year program to monitor types and levels of contamination by 52 pesticides in 94 groundwater wells in Gaza. Two analytical techniques (GC/MS and HPLC/MS) were applied to achieve this objective. Water from 63 wells showed no detectable levels of pesticides or levels that were much lower than the allowable limit (0.5 μg/L) of the German and the European Commission (EC) standards for groundwater. Municipal groundwater wells located in residential areas showed better quality than private wells in agricultural regions. Atrazine, atrazine-desisopropyl, propazine, simazine were detected in 18, 15, 8 and 5 wells with average concentrations of 3.5, 1.2, 1.5 and 2.3 μg/L, respectively. A linear correlation was found between the chloride concentrations in groundwater and atrazine for the same private wells. Generally speaking, shallow aquifers in sandy substances in areas of low annual precipitation in the southern areas of Gaza showed detectable concentrations of pesticides. Pesticides were more abundant in clay soils of the northern area. A linear regression analysis showed a correlation coefficient of r = 0.87 between the strawberry greenhouses and the occurrence of propazine, sebutylazine, terbutylazine, 4,4′-DDT, 4,4′-DDE, and 4,4′-DDD in soil. The averages of propazine, sebutylazine and terbutylazine were 19, 13 and 39 μg/kg, respectively. Two soil samples from greenhouses showed maximum contents of 4,4′-DDE and 4,4′-DDT up to 1150 and 823 μg/kg, respectively. Groundwater needs to be assessed for pesticide contamination on a routine basis to protect the health of Gaza's residents. Where levels of pesticides are found to exceed levels that protect health, alternative water resources need to be found for drinking and possibly other household uses.