The influence of natural organic matter on the transport and bioavailability of arsenic and trace metals in groundwater in Lahore,Pakistan

Samples of drinking water from wells situated in lahore,pakistan have been analysed for dissolved organic carbon (doc),manganese,iron,copper and arsenic in a study on the role played by doc in facilitating the transport of these elements. filtered samples (64) were collected from five wells (depths 50-200 m) during the winter (31.12.09-21.02.10). during the period (2009-2010),the concentrations of doc (0.02-2.89 mg/l) in water from wells 1 and 4 correlate positively with that of arsenic. in well 4 there is also a positive correlation between doc and the manganese concentration. however,analysis of water extracted from well 5 shows a negative correlation between copper and doc. the concentrations of arsenic (10-36 μg/l),which are high relative to the limit recommended by who; result from a combination of iron reduction and interactions between doc and the arsenic-containing minerals that constitute part of the sediment. the results are consistent with doc contributing to the release and transport of arsenic and trace metals in ground water. it is suggested that doc may provide a means for evaluating the loadings of these elements in watercourses. © 2016,chemical society of pakistan. all rights reserved.