Occurrence and distribution of selected heavy metals and boron in groundwater of the Gulf of Khambhat region, Gujarat, India.

The concentration of selected heavy metals, like As, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn as well as B, was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) in groundwater samples from various locations in the Gulf of Khambhat (GoK), an inlet of the Arabian Sea in the state of Gujarat, India, during post-monsoon, winter, and pre-monsoon seasons in a year. Most heavy elements are characterized by low mobility under slightly alkaline and reducing conditions; concentrations in confined aquifers are smaller than the maximum permissible values for drinking water. The temporal changes indicate that a majority of metals is entering the aquifer during monsoon. Principle component analysis of the heavy metal data suggests that Co, Cu, Cd, and Zn are interrelated with each other and derived significantly from anthropogenic route, while input of Pb and Cr may be due to atmospheric deposition in the study area. Both weathering of rocks and anthropogenic input were found to be main sources of elements in the groundwater. The heavy metal levels in groundwaters of the GoK region in comparison with some of the European and Asian sites were higher; however, these metal levels were found to be comparable with few urban sites in the world.