###### Abstract  
Surface water pollution (as a result of pesticides) is a major problem, due to the negative impact on human health and ecosystems. The excessive use and persistence of surface water pollution in the environment may present a notable risk. In this article, DDT and its metabolite DDE hereafter, DDT-DDE), and a commonly used pesticide (herbicide) glyphosate, were analyzed in agricultural drainage waters; afterward, a spatial analysis was applied to identify potential areas of high pesticide occurrence in an agricultural Mediterranean coastal floodplain. The spatial distribution of banned (Directive 79/117/EEC), yet highly persistent pesticides in the environment, such as DDT (and metabolites), was compared with the (currently and mostly used) glyphosate. A sequence of various point patterns, spatial analysis methods, and non-parametric statistics, were computed to elucidate the pesticide pollution hotspots. As a reference value, almost 70% of the water samples were above the World Health Organization (WHO) guideline for DDT (and metabolites) for drinking water (1 \(\mu\)g/L), with a maximum of 6.53 \(\mu\)g/L. Our spatial analysis approach revealed a significantly high concentration of DDT-DDE clusters close to wetlands in natural parks, where mosquitos are abundant, and pesticides persist and flow to the surface waters from soil and groundwater pools. Conversely, glyphosate concentrations were below WHO guidelines; their spatial patterns were related more toward current agricultural uses in the southern sector of the study area. Keywords: irrigation systems; DDT; glyphosate; salinity; spatial autocorrelation +
Footnote †: journal: Medical  
restricted. DDT is banned in most of the countries that signed the Stockholm Convention on Persistent Organic Pollutants (POP). The signatory countries (e.g., Spain was incorporated into the convention in 2001; entry enforced in 2004) should adopt measures to restrict its production and use [11]. However, past restrictions on the use of certain pesticides do not mean that they are no longer present in the environment. It is well known that DDT is still present in ocean and inland waters, soils, sediments, and living organisms in countries whose commercialization was prohibited decades ago, such as those belonging to the European Union (EU) [9; 10; 12]. If this pesticide is apparently no longer being used in many areas, the fact that it continues to appear (even at low concentrations) implies that there is a huge storage in the soils and sediments [13; 14; 15; 16] that, little-by-little, is emerging into surface and groundwater, and entering into the trophic chains. Glyphosate is another widely employed herbicide that is generating great concern (due to its possible effects on health and ecosystems). Glyphosate is a broad-spectrum herbicide, in which worldwide usage (agricultural and non-agricultural) rose more than 12-fold from 1995 to 2014 [17]. Although glyphosate was identified as \"probably carcinogenic to humans\" [18], its commercialization and use is generalized worldwide. However, research indicates that our current dependence (of its massive application) implies that, without glyphosate, fundamental changes in farming practices should be adopted, with huge economic costs, at least in the short-term [19]. One underdeveloped aspect is the analysis of the regional spatial distribution of pesticides, between measurements carried out in different locations and environmental compartments, and the possible existence of storage hotspots in soils and sediments. The use of pesticides did not have to follow a homogeneous spatial pattern because of their preferential uses of combatting or mitigating different types of pests. The possible existence of areas with higher levels of pesticide contaminations should be of concern, and should involve an appropriate spatial analysis, in order to promote better monitoring and management strategies for the territory [20].