Speciation and ecological risk of heavy metals and metalloid in the sediments of Zhalong Wetland in China

Abstract

A total of 271 sediments samples from the Zhalong Wetland were analyzed for concentration and distribution of Hg, Cd, As, Cu, Pb, Zn, Cr, and Zn; their speciation according to the modified European Community Bureau of Reference sequential extraction procedures and their ecological risk based on Lars Hakanson's potential ecological risk assessment and risk assessment code were made. The results can be summarized as the followings: (1) Concentrations of all metals measured were above soil background values of Songnen Plain, and their spatial distributions were distinctly different. The concentrations of metals (except Pb) were high in the east, followed by the north, and were relatively low in the core zone and south. The concentration of Pb was high in the north, south, and west, compared with low concentration in the core zone and east. (2) The dominant proportion of Pb, Zn, and Cr was in the residual fraction, suggesting that they were environmental stable. The concentrations of Cu and As in the reducible fraction, the concentration of Cd in the acidsoluble fraction, and the concentration of Hg in the oxidizable fraction were relatively high, indicating they had greater environmental effects. (3) The evaluation of the ecological risk showed that Cd, Hg, and As had relatively high ecological risk index, especially the ecological risk of Cd should be paid attention to. In general, the ecological risk of the heavy metals and metalloid by zone was experimental zone [ buffering zone [ ecological tourism zone [ core zone.

Experimental Study of Mobility and Kinetic Characterization of Trace Elements in Contaminated Sediments from a River Basin in Northern Peru

“…Hakanson's potential ecological risk index (Hakanson 1980;Ye et al 2013) was used. The potential ecological risk index methodology is based on the assumption that the sensitivity of the aquatic system depends on its productivity.…”

“…T i r is the biological toxicity factor of different trace elements (the factors of Cd, As, Ni, Cu, Pb, and Zn were 30, 10, 5, 5, 5, and 1, respectively) (Wang et al 2011;Zhang et al 2012); E i r is the potential ecological risk factor of single metal and RI is the potential ecological risk index of all metals and metalloids present in the sample (Ye et al 2013). …”

“…According to Ye et al (2013), the potential ecological risk of sediments posed by heavy metals can be classified into the following categories: low risk (E i r < 40, RI < 135), moderate risk: (40  E i r < 80, 135  RI < 265), considerable risk (80  E i r < 160), high risk (160  E i r < 320, 265  RI < 525), and very high risk (E i r > 320, RI > 525).…”

Distribuição geoquímica e biodisponibilidade de metais traço em sedimentos no Rio Bento Gomes, Poconé - MT, Brasil

“…Dentre todos os principais impactos que ameaçam os ecossistemas, os metais e metalóides desempenham um papel muito importante devido à sua não degradabilidade, bioconcentração e biomagnificação (Zhang et al 2012;Townsend et al 2013;Ye et al 2015).…”

“…A especiação de metais potencialmente tóxicos fornece informações importantes para avaliar a toxicidade e o risco ecológico aos humanos e animais (Ye et al 2015). Assim, os metais podem se apresentar nas diferentes formas químicas: solúvel, trocável, ligados à matéria orgânica, ligados aos óxidos/hidróxidos de ferro, alumínio e manganês, carbonatos, fosfatos, sulfatos (ou outros minerais secundários), ou ligados aos silicatos (Devesa-Rey et al 2010).…”