Evaluation of groundwater and soil pollution in a landfill area using electrical resistivity imaging survey

Landfills are sources of groundwater and soil pollution due to the producti on of leachate and its migration through refuse. This study was conducted i n order to determine the extent of groundwater and soil pollution within an d around the landfill of Seri Petaling located in the State of Selangor, Ma laysia. The condition of nearby surface water was also determined. An elect rical resistivity imaging survey was used to investigate the leachate produ ction within the landfill. Groundwater geochemistry was carried out and che mical analysis of water samples was conducted upstream and downstream of th e landfill, Surface water was also analyzed in order to determine its quali ty. Soil chemical analysis was performed on soil samples taken from different l ocations within and around the landfill in the vadose zone (unsaturated zon e) and below the water table (in the soil saturated zone). The resistivity image along line L-L, indicated the presence of large zones of decomposed w aste bodies saturated with highly conducting leachate. Analysis of trace el ements indicated their presence in very low concentrations and did not refl ect any sign of heavy metal pollution of ground and surface water or of soi l. Major ions represented by Na, K, and Cl were found in anomalous concentrati ons in the groundwater of the downstream bore hole, where they are 99.1%, 9 9.2%, and 99.4%, respectively, higher compared to the upstream bore hole. E lectrical conductivity (EC) was also found in anomalous concentration downs tream. Ca and Mg ions represent the water hardness (which is comparatively high downstream). There is a general trend of pollution towards the downstr eam area. Sulfates (SO4) and nitrates (NO3) are found in the area in low co ncentrations, even below the WHO standards for drinking water, but are sign ificantly higher in the surface water compared to the groundwater. Phosphat e (PO4) and nitrite (NO2), although present in low levels, are significantl y higher at the downstream. There is no significant difference in the amoun t of fluoride (F) in the different locations. In the soil vadose zone, heav y metals were found to be in their typical normal ranges and within the bac kground concentrations. Soil exchangeable bases were significantly higher i n the soil saturated zone compared to the vadose zone, and no significant d ifference was obtained in the levels of inorganic pollutants. With the exce ption of Cd, the concentration ranges of all trace elements (Cu, Zn, Cr, Pb , and Ni) of Seri Petaling landfill soils were below the upper limits of ba seline concentrations published from different sources.