Modelling Spatial Distribution of Heavy Metals and their Fluxes in Riverine System of Azad Jammu and Kashmir, Pakistan

Abstract

Himalaya region is considered as hotspot for climatic change, ecology and hydrological studies. The cold climatic regime, altitude, remoteness, scarce population and minimum traffic movement has gained very less attention for conducting studies specifically on heavy metal contamination. The present appraisal has investigated heavy metal concentration for AJK riverine system located in Lesser Himalaya Region (LHR) of Pakistan. Statistical modelling techniques were used to evaluate concentration levels, spatial distributio, source identification and contribution factors for metal enrichment. The development of heavy metal mass inventory and annual depositional fluxes calculation were done for sediments of riverine system of this region for the very first time. Thirty two sites from three sampling stations were located for sampling of soil, sediments and water. Pb, Cd, Zn, Cu, Ni, Mn, Cr and Fe concentrations were analyzed in all matrices. Moreover, the burial flux calculations for Black Carbon (BC) and Total Organic Carbon (TOC) levels were made in sediments of all sites. Descriptive stats, multivariate data ordination analysis and HYSPLIT model were employed for delineation of metal profile, spatial distribution and source apportionment. Ecological risk assessment was done using mathematical equations of Enrichment Factor (EF), Geo-accumulation index (I-geo) and Metal pollution index (MPI). Results indicated some natural sources, anthropogenic interference and transboundary movements (LRAT) are playing their role for metal enrichment and flux in the region. The average concentration of Pb and Cd in soils and sediments were found higher than the pre-industiral/crustal values. Their elevated mean concentrations can be attributed to well preserve ore forming topographic feature of limestone as well. The concentrations found in river water of LHR were in compliance with the maximum allowable limit (MAL) in drinking water as per prescribed by NSDWQ Pakistan. BC burial flux showed the human interference especially biomass burning, vehicular emissions and hydropower projects can also be significant for intensifying heavy metals in the region. Since severity of contamination in the entire area is very low but if the current pace of development and human intrusion will remain constant in future then picture will be entirely opposite for LHR. Therefore, the attention of local and regional research institutions is required to investigate the seasonal and temporal trends of heavy metals in LHR and to formulate policies and strategies to cater heavy metal problems if they are seriously posing threats to the regional ecology