Trace elements in major solid-pesticides used in the Gaza Strip B.H. Shomar * Institute of Environmental Geochemistry, University of Heidelberg, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany Received 2 January 2006; received in revised form 2 March 2006; accepted 3 March 2006 Available online 18 April 2006 Abstract This study describes the purity of pesticides used in Gaza in terms of trace elements. A semi-quantitative EMMA-XRF technique and quantitative ICP/OES was used to determine the concentrations of Al, As, Ba, Br, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, Rb, Sc, Se, Sr, Ti and Zn in 50 of the most commonly used solid pesticides collected from the five central shops in the Gaza Strip. The results revealed that the pesticides contain considerable amounts of trace elements and do not comply with the expected-theoretical structure of each species. Moreover, they do not reflect the actual constituents mentioned in the trade labels. Interviews with market owners and field sur- veys confirmed that the pesticides were not pure. In some cases they have been mixed in local markets with minor inorganic species with- out a scientific basis. They may also have been smuggled into Gaza with differing impurities. The results indicate that pesticides should be considered as a source of certain trace metals (particularly Cu, Mn and Zn) and other elements (Br, Sr and Ti), which may affect their mass balances in soil and groundwater as well as their plant uptake. Different scenarios and calculation models of the transport of trace elements in soil and groundwater of the Gaza Strip should include pesticides as an additional source. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Gaza Strip; Pesticides; Trace elements 1. Introduction Research on pesticides primarily focuses on the organic dimension, while the inorganic components receive rela- tively less attention. This could explain the shortage in the literature about the existence of trace elements in pesti- cides, as it is assumed that the chemical structure of pesti- cides is well known, labeled or documented. This is not the case, however, in many countries, particularly in develop- ing countries. Pesticides have greatly improved the agricul- tural production world-wide and have shown to be very effective in controlling vector-borne diseases. In Gaza their indiscriminate use and improper application are of concern because of the hazards and risks they pose to humans and the environment (Yassin et al., 2002). Pesticides display a variety of chemical characteristics (Stan, 1995); e.g. they can be bound by soil in different ways. Pesticides, including their trace element, constituents have been found in con- taminated groundwater and soil (El-Nahhal and Safi, 2004; Shomar et al., in press). Contamination due to leach- ing of pesticides is a common and growing problem in major agricultural regions (Flury, 1996). Pesticides that have trace metals in their chemical structure (fosetyl-alumi- num, propineb, mancozeb, maneb and copper oxychloride) have been detected in groundwater of many regions in the world (Kolpin et al., 2000a,b). A recent study categorized a wide range of pesticides as ‘‘leachers’’ or ‘‘non-leachers’’ for a specific Hawaiian hydrogeological setting (Li et al., 2001). In the United States, there is a considerable body of work demonstrating the occurrence of both parent com- pound pesticides and their metabolites in groundwater aquifers (Baker et al., 1993; Lawrence et al., 1993). Ten percent of 170 topsoil samples of the agricultural and non-agricultural areas of the Gaza Strip showed slight contamination, primarily by Zn, Cu, As and Pb, due to anthropogenic inputs. The mean concentrations of these elements were 180, 45, 13 and 190 mg kg À1 , respectively. The pollution of several investigated sites was found to 0045-6535/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2006.03.004 * Tel.: +49 6221 546 031; fax: +49 6221 545 228. E-mail address: bshomar@ugc.uni-heidelberg.de www.elsevier.com/locate/chemosphere Chemosphere 65 (2006) 898–905