Trace Element Contamination of Groundwater Around Kirana Hills, District Chiniot, Punjab, Pakistan

Abstract

Thirteen groundwater samples and one river water samples were collected from wells and water sources in
Chenab Nagar (Rabwah) area, district Chiniot, Punjab in July 2017, in order to analyze trace elements composition of
water. The water samples were directly analyzed using an inductively coupled plasma mass spectrometry (ICP-MS).
Judging from the Maximum Contaminant Level (MCL), Secondary Maximum Contaminant Level (SMCL) and
Maximum Contaminant Level Goal (MCLG) as defined by USEPA and WHO Guidelines for Drinking-water Quality,
the concentration of 5 elements, As, Mn, Cl, Br and S, in groundwater samples exceeded the standards. In particular,
the concentration of As (max. 25.1 μg/l) and Mn (max. 443 μg/l) showed high level, which may cause negative effect if
the contaminated water is continuously consumed. High concentrations of As (max. 161 mg/kg) and Mn (max. 355
mg/kg) were also detected in the Precambrian meta-volcano sedimentary rock samples collected from the Kirana hills,
according to the aqua regia digestion ICP-ES/MS analysis. Arsenopyrite (FeAsS) and cryptomelane (K(Mn4+,
Mn2+)8O16) were identified in the rock samples using X-ray diffraction (XRD) and petrographic observation and those
minerals are considered to be the main sources of As and Mn contamination. The groundwater contamination by As
and Mn is caused by a water rock interaction in the subsurface zone, where basement rocks of Kirana hills and their
debris are exposed with groundwater. High salinity of groundwater is inherent in the area, but shallower parts of the
contamination by Cl, Br, and S is probably accelerated by anthropogenic origins such as septic tank and wastewater.