『Environmental assessment of Dhaka City, Bangladesh』
Dr. Faruque Ahmed 島根大学汽水域研究センター 客員研究員
話題提供していただくのは、この4月から島根大学汽水域研究センターの客員研究員として来られた Faruque Ahmed 博士 です。皆様のご来聴をお待ちしております。
Environmental pollution has become a serious problem since the accelerated growth in world population during the 20th century, and Bangladesh is no exception. Over the last few decades, many geochemical studies have examined coastal and lake sediments and street dusts to disclose contamination by various trace metals. Recently, the urban environments of Dhaka City have been evaluated by determination of the geochemical compositions of core sediments from two lakes and street dusts from differing areas (industrial, commercial, and residential) of the city. Vertical profiles of metals (e.g. Pb, Zn) in cores from lakes show abundances gradually increase upward toward the sediment-water interface. The results also show significant concentrations of Pb, Zn, Cu, Ni, and Cr in the Dhaka dusts, and some variations related to the sample groups. The condition of the Dhaka environment was compared to that in Japan and other baseline sediments using Zn-Fe2O3 and Pb-Fe2O3 diagrams. Zn-Fe2O3 trends for the dusts show steep inclination compared to the baseline sediment and the Japanese urban sediment trends. Dhaka lake data show enrichment of Zn over the dusts, suggestive of Zn pollution from poorly-controlled industrial sources. In contrast, on the Pb-Fe2O3 diagram, Dhaka dusts have greater Pb contents than lake sediments, probably due to the higher traffic density in the commercial area compared to the residential area including the area around the lakes. The results overall suggest that higher levels of these metals in Dhaka environment can most likely be attributed to the anthropogenic sources like rapid development and vehicle emissions to the atmosphere.