Seasonal variations of trace elements and heavy metal concentrations in Phuleli Canal Water (Sindh), Pakistan

Phuleli Canal (Sindh), Pakistan is one of the irrigation canals of the Kotri Barage which provides water for irrigation as well as for drinking purpose. Quality of the canal deteriorates while passing through Hyderabad city, 2nd largest city of Sindh, Pakistan because highly toxic effluent from plastic factories, illegal cattle pens, slaughterhouses and municipal sewage water are directly discharged into the Phuleli Canal without any treatment. That polluted water has put lives of millions of people at risk living at downstream in district Tando Muhammad Khan. Human health problems due to waterborne diseases are commonly reported in newspapers in Phuleli Canal Command area. Present study was thus conducted to investigate the effect of disposal of untreated domestic and industrial sewage water and waste into Phuleli canal on the quality of canal water. The study was conducted during the year 208-209 to observe seasonal variation of trace and heavy metals at different location (reduced distance, RD = 100 ft.) along the length of Phuleli Canal. Water samples were collected during four seasons (summer, autumn, spring and winter) with three replications each from seven locations (RD-0, RD-30, RD-50, RD-70, RD-90, RD-10 and RD-130). The samples collected were analyzed for their trace elements and heavy metal concentrations including zinc, manganese copper, iron, cadmium, chromium, lead and arsenic. The water analysis results were then compared with international organizations i.e. FAO and WHO standards of water for irrigation and human consumption respectively. Fe, Cd and Cr concentrations in water were higher than WHO permissible limits, and Cu and Mn were greater than FAO permissible limit at downstream of the canal. Comparatively heavy metals viz. Cd, Cr, Pb and As were higher towards downstream reaches as compared to upstream reaches during winter. As the season changed the values of these parameters showed decreasing trend (autumn greater than spring greater than summer).