Exploring the Metals of Industrial Contaminated Soil and the Status of Heavy Metal Hyper-Accumulating Plant Species in Bangladesh

Abstract

Phytoremediation is a practical and cost-effective method for the remediation of heavy metal-polluted soils. The study aimed to explore phytoremediating plant species (no plant species from the food chain) available in the study area sites, evaluate their metal uptake capability, and illustrate the storage of metals within the parts of the hyperaccumulating species. A total of 14 phytoremediating species were identified as hyperaccumulators from the industry-contaminated sites in Gazipur, Narsingdi, Narayanganj, and Mymensingh, and out of them, 4 species (Mustard, Dhaincha, Bean, and Soybean) were selected for the field experiment, considering the farmers' interest and their availability.  Based on measured metal contents in soils, As, Fe, Cr, and Ni exceed the permitted level. There is a significant uptake of toxic metals from soils, as noticed based on primary analysis of soil samples (initial and final samples). In initial soil samples, As, Cd, Cu, Cr, Ni, Mn, Co, Fe, Pb, and Zn ranged 16.276-21.310, 0.42-2.167, 18.25-34.85, 76.73-156.75, 62.75-110.25, 282.5-470.00, 7.975-19.630, 18675-36860, 18.05-37.521, and 46.65-86.55 ppm, respectively. Based on maximum permissible limits, As, Fe, Cr, Ni contents in initial soils are higher, but the rest of the metals do not exceed the limits. Soil samples from Mymensingh and Narayanganj have greater metal concentrations than those from other places. Furthermore, several metals, particularly Pb and Ni, were detected in post-harvest soil in higher concentrations than initially, indicating persistent pollution in Gazipur. Therefore, using a hyperaccumulator to remediate soil ought to be regarded as a timely need method. Here, among the four species, planted Indian mustard (Brassica juncea) plants can be utilized to treat landfills in an economical and environmentally responsible manner.