Distribution and solid-phase speciation of toxic heavy metals of bed sediments of Bharali tributary of Brahmaputra River

Abstract

Heavy metal (Fe, Mn, Zn, Cu, Ni, Pb, and Cd) concentrations and their chemical speciations were investigated for the first time in bed sediments of Bharali River, a major tributary of the Brahmaputra River of the Eastern Himalayas. Levels of Fe, Mn, Pb, and Cd in the bed sediments were much below the average Indian rivers; however, Cu and Zn exhibit levels on the higher side. Enrichment factors (EF) of all metals was greater than 1 and a higher trend of EF was seen in the abandoned channel for most metals. Pb showed maximum EF of 32 at site near an urban center. The geoaccumulation indices indicate that Bharali river is moderately polluted. The metals speciations, done by a sequential extraction regime, show that Cd, Cu, and Pb exhibit considerable presence in the exchangeable and carbonate fraction, thereby showing higher mobility and bioavailability. On the other hand, Ni, Mn, and Fe exhibit greater presence in the residual fraction and Zn was dominant in the Fe-Mn oxide phase. Inter-species correlations at three sites did not show similar trends for metal pairs indicating potential variations in the contributing sources.

Heavy metals in road deposited sediments and road dusts of Colombo Capital, Sri Lanka

“…The commonly used methods are correlation analysis, enrichment factor (EF) and geoaccumulation index (I geo ) (Lu & Bai, 2010;Hoque et al, 2011;Singh, 2011). In order to establish inter-element relationships in collected samples, correlation coefficient analysis proves to be a useful tool (Kabadayi & Cesur, 2010).…”

“…In order to establish inter-element relationships in collected samples, correlation coefficient analysis proves to be a useful tool (Kabadayi & Cesur, 2010). The main factors behind enrichment of metals are change in land-use patterns and lithological effects besides anthropogenic pressure (Hoque et al, 2011).…”

“…I geo has been exploited to evaluate the degree of pollution by heavy metals in sediments (Hoque et al, 2011). I geo can be calculated by the following formula:…”

“…The factor 1.5 is used for possible variation in the background due to lithogenic effects (Hoque et al, 2011). The following classification is given for the index of geoaccumulation (Förstner et al, 1990) and inferences can be drawn accordingly: …”

“…The common environmental pollutants are aromatic compounds (Ray et Heavy metals are essential for vital processes in humans and many living organisms (Guney et al, 2010). However, they have a great ecological significance today due to their toxicity and accumulative behaviour (Hoque et al, 2011). These can accumulate in the body, affect the central nervous system, cause poisoning, and act as co-factors in many other illnesses (Tume et al, 2008).…”