Soil Contamination From Tannery Wastes with Emphasis on the Fate and Distribution of Tri- and Hexavalent Chromium

Abstract

Industrial wastes generated from tanneries located in the southwestern part of Dhaka, pose serious threat to the environment. Surface accumulation of trivalent chromium reaching as high as 28,000 mg/kg have been encountered at 1 km distance from the waste lagoon. In contrast, maximum concentration of hexavalent chromium is about 1 mg/ kg, and is very irregularly distributed all over the area. Although soil pH is alkaline in general, a sharp drop of pH down to 3.4 has been observed at some locations. Furthermore, high chloride (Cl) and lead (Pb) concentrations pose risk for city's groundwater quality, of which Pb is vulnerable for any chelateassisted phytoremediation as it can enhance its mobility. Scanning electron microscope study showed chromium within the structure of clay minerals, mainly illite-smectite, and also as chlorite-chromian. Presence of lepidocrocite indicates a rather reactive phase which can undergo reductive dissolution and release Cr in the environment.

Groundwater Quality

“…Tannery wastes in the southwestern part of Dhaka led to the accumulation of trivalent chromium as high as 28 g/kg (Shams et al, 2009) adapted for water quality classification, indicating that water chemistry was influenced by chemical fertilizers and organic matter in uplands (Chkirbene et al, 2009). Drained and undrained paddocks were compared to quantify the effects of intensive grazing on groundwater quality along two transects across the dairying area of Togari.…”

Assessment of Physicochemical and Biochemical Qualities of Tannery Effluents of Hazaribagh, Dhaka, and Comparison with Non-Tannery Water Samples

“…The groundwaters as well as the ecosystem of the Hazaribagh area are on the verge of huge pollution. A study was conducted on the soil profile of Hazaribagh tannery area down to a depth of 5 meters and the surface accumulation of total chromium reaching as high as 28000 mg/kg have been encountered at 1 km distance from the waste lagoon (Shams et al, 2009). The distribution of Cr (VI) has been irregular in the subsurface and a maximum of about 1 mg/kg have been measured at 3 m depth.…”

“…Although soil pH is alkaline in general, a sharp drop of pH has been observed at some locations both in surface and subsurface layers to as low as pH 3.4. Such an acidic environment can play a significant role in the fate and mobility of heavy metals in nature (Shams et al, 2009). Another study in the Southeast Asian region assessed the concentrations of total chromium in the soils and effluents of tanneries distributed in ten clusters of Sialkot District, Pakistan, and found (Cr) to be in range of 3.45-11.43 mg/kg, and 16.12-36.83 mg/L, respectively (Rafique et al, 2010).…”

“…The hexavalent chromium detected in alkaline environment in subsurface can enhance its mobility both vertically down to the aquifer and laterally towards the river Buriganga, hence again to the aquifer as the river and the aquifer are hydraulically connected (Shams et al, 2009). The effects of effluents from tanning industry and its toxicity on survival and histopathological changes of snakehead, Channa punctatus were studied.…”

Assessment of Environmental Impact for Tannery Industries in Bangladesh

“…Export earnings from the leather industries sector in 1995-1996 was USD $237.79 million, of which USD $211.70 million was from leather exports and USD $26.09 million was from export of finished leather products [1]. These industries process 220 metric tons of hide a day and some 40 to 50 liter of chemical liquids for each kilogram of hide [2]. However the industrial establishments' huge potential of for sustained economic development of the country has been constrained for they were not designed and operated in sustainable manner.…”