Depletion risks of essential trace metals in a transboundary drain and its surrounding soil using GIS techniques.

Hudiara drain, a big sewage water body originating from India, is an important tributary of river Ravi in Pakistan. In present study, role of the drain in build-up/depletion of metal micronutrients Cu, Fe, Mn and Zn in surrounding agricultural lands has been investigated. Soil samples, up to a vertical distance of 1200 m on both sides of the drain and drain water samples were collected and analysed for metal micronutrients. Soil analysis results were interpolated by using the best optimized interpolator to generate continuous variation of the selected metals. Further patterns have been identified using proximity stat with consecutive neighbouring zones of 100 m extent. Cu and Mn concentrations were higher in some drain water samples, whereas Fe and Zn were found below guidelines in all collected water samples. In adjacent agricultural land the metals did not show uniform dispersal pattern along the drain length. However, vertical pattern of distribution indicated that drain water was controlling Cu and Zn concentrations, positively, whereas it was causing a dilution effect on Fe and Mn build-up in the surrounding agricultural lands. [ABSTRACT FROM AUTHOR]