Monitoring of heavy metal pollution and GIS derived land use changes in the major economic zone of Bangladesh

Abstract

Water pollution and land use changes are exceeding the limit in the most important economic zone, Dhaka Export Processing Zone (DEPZ) in Bangladesh and have become a great threat to the environment. To understand this threat, the dissolved metal concentration was measured from Turag and Bangshi River near DEPZ. The land use changes of DEPZ was measured and analyzed using Bangladesh Space Research and Remote Sensing Organization (SPARRSO) and Landsat TM images through Arc GIS 10.1, ERDAS Imagine 9.1. The dissolved Pb, Cd, Ni and Zn concentration were found to be higher in compare with those of water standards except Cu at every sampling point. Elevated concentration of Cd and its corresponding enrichment factor (EF%) indicated accumulation possibility of metals in the river bed sediments. The principal component analysis result also showed the dominance of Cd ions along with Ni ions in the river water. pH was found to be the controlling factor of every dissolved metal in the rivers sourced from DEPZ. Alongside, the study represents that the land use pattern has been changed remarkably. Large volume of water has been converted into unplanned settlement and urbanization. Land use changes may lead drastic changes in the land quality, such as decreases in biodiversity, instability of ecosystem, decreased soil quality, loss of nutrients, planned and unplanned urbanization, and bare land. Comprehensive synoptic researches are required to monitor the water pollution caused by DEPZ into these rivers and to determine the exact land uses for monitoring further changes.