Assessment of impact of environmental pollution on groundwater and surface water qualities in a heavily industrialized district of Kocaeli (Dilovası), Turkey

The impact of uncontrolled industrialization and urbanization on surface water and groundwater qualities was assessed in a heavily industrialized district of Kocaeli (Turkey) considering source, types and levels of contaminants. A sampling campaign was conducted on both water bodies in dry (September) and wet (May) sampling periods. Water samples were taken from 6 surface water stations and 24 wells distributed from upstream to downstream along Dil stream to determine the degree of deterioration in water quality from background conditions. Results showed that Dil stream was heavily polluted with regard to many parameters including Al, Fe, Mn, Pb, DO, COD, NH₄, NO₂ and PO₄. While sewage discharges, leachates from closed wild landfill and quarries create sources of contamination for Dil stream at upstream, primarily metal industries (mainly iron and steel manufacturing) at downstream contribute markedly to the metal contamination. Contribution of highly polluted Dil stream to the groundwater contamination is also significant in the alluvium aquifer at both upstream and downstream of Dil stream. Microbial pollution indicating fecal contamination and high nutrient levels exist in the groundwater. In addition, relatively high AOX concentrations over background levels were detected in wells at the downstream part of Dil stream where industrial activities were densely distributed. Deep wells located near the Gulf of İzmit were also affected by seawater intrusion. Results suggest that Dil stream contaminated by industrial discharges, sewages, and leachates from old wild landfill negatively influences the groundwater quality in the alluvial aquifer.