Spatio-temporal variations in physico-chemical parameters and potentially harmful elements (PHEs) of Uchalli Wetlands Complex (Ramsar site), Pakistan.

Abstract

Uchalli Wetlands Complex (UWC) is located in District Khushab, Pakistan, which comprised of three lakes named Khabeki, Uchalli, and Jahlar. The UWC Pakistan is one of the Ramsar sites of international importance. However, the information regarding water quality parameters and concentration of potentially harmful elements (PHEs) is relatively short. Present study focused on spatio-temporal variations in the physico-chemical parameters and PHE (Cd, Pb, Ni, Cu, Zn, Cr, As, Mn) concentrations in water and fish samples using inductively coupled plasma. Sampling was done in summer (August 2016) and winter (January 2017) seasons. The overall concentrations of PHEs in water were in the following order: Mn > Zn > Cu > Cr > Ni > Cd > Pb > As for Khabeki; As >Ni > Cr > Mn > Zn > Cu > Cd > Pb for Uchalli; and Mn > Zn > Ni > Cu > As > Cr > Cd > Pb for Jahlar Lake. PHE concentration in fish followed the order Ni > Cd > Mn > Pb > Cu > Zn > Cr > As. PHEs analysis showed that Mn; Ni and As; and Ni and Mn in summer were above the Pakistan Environmental Quality Standards (PEQS) and World Health Organization (WHO) standards in Khabeki, Uchalli, and Jahlar Lakes respectively while in winter, Mn; Cd, Ni, and As; and Ni and Mn were higher than standard values in Khabeki, Uchalli, and Jahlar Lakes respectively. In fish samples, only Cd (0.0942) was higher in summer as compared to winter (0.0512) while other seven PHEs observed were higher in winter. Conclusively, the metal pollution index showed that water quality of UWC is not very fit for human consumption directly. The bioconcentration factor results indicated potential to accumulate PHEs, i.e., Cd (29.4375 and 9.4814), Pb (16.66 and 4.375), and Ni (4.9875 and 6.206), in fish during both sampling campaigns. Target hazard quotient (THQ), target carcinogenic risk (TR), hazard index (HI), estimated daily intake (EDI), and international safe standard limits of PHEs for fish species indicated that fish from UWC is safe for human consumption. Variations in physic-chemical parameters and PHE concentration were observed spatially and temporally that could be caused by precipitation amount or natural geochemistry of the lakes' crust. The water quality was not suitable for direct human consumption. Fish was only found in Khabeki Lake that had potential to accumulate Cd, Pb, and Ni more as compared to other studied PHEs.