Evaluation of sediment contamination with heavy metals: the importance of determining appropriate background content and suitable element for normalization

Abstract

In the present study, concentrations of heavy metals (Cd, Cu, Co, Mn, Cr, Ni, Pb, and Zn) were determined at 35 river sediments in Serbia. The anthropogenic heavy metals input and quantification of the metal enrichment degree in sediments were estimated by calculating geo-accumulation indices (I(geo)) and enrichment factors (EF). These pollution indices have been calculated using different background values (continental crust and local background values) and different element used for normalization (Al and Fe), followed by result comparison. The EF values calculated with continental crust as background (minor to extremely severe enrichment) were higher than when regional background values were used (minor to moderate enrichment). Significant influence of background values on the I(geo) values is observed. Values of geo-accumulation index (<2) revealed that studied river sediments are remaining unpolluted to moderately polluted with Co, Mn, Cr, and Ni. Significant pollution in the sediments was observed for Cd, Cu, Pb, and Zn elements. The results of this study confirm the relevance of precise and accurate determining of local background concentrations while assessing sediment pollution. The values of EFs for studied elements were more influenced by the choice of background values than selection of element used for normalization. Our recommendation would be to use the local and regional background content in quantification of metal contamination in sediments, since these values differ and are site and region dependent.

Caracterização estratigráfica dos depósitos sedimentares cenozoicos da Bacia do Ribeirão Sardinha, porção sul do Quadrilátero Ferrífero (MG), e estabelecimento de background geoquímico

“…De acordo com os critérios de avaliação da qualidade dos sedimentos utilizados e os valores de background calculados neste estudo, notou-se que as concentrações naturais dos elementos As, Cr, Ni, Fe e Mn podem ser consideradas elevadas. Valores altos de background também foram encontrados para os elementos Zn (66,6 mg/ kg) e Pb (57,8 mg/kg), de acordo com Sakan et al (2015), em um estudo realizado mais recentemente na Sérvia, na Bacia do Rio Danúbio, onde ocorrem depósitos de Pb, Zn e Cu. Garcia-Ordiales et al 2017também mostraram concentrações elevadas de background para o Zn (79,7 P: ponto de coleta; B: barranco em que a amostra foi retirada; T: terraço em que a amostra foi retirada.…”

Stream Sediment Geochemical Survey of Selected Element In Catchment Area Of Saguling Lake

“…The 12 points of sediment sampling locations around Saguling lake are presented in Table 2 and Figure 1. Where C Me is the concentration of metals in the sediment samples (mg/kg) [17]. This method compares the concentration of one type of heavy metal to the background heavy metal which is the concentration of the original heavy metals derived from the earth's crust.…”

Metal Pollution in Coastal Sediments

“…Although the choice of geochemical normalization element is critical when evaluating the enrichment level of metals based on EF, a more accurate assessment should be achieved by choosing the local background values from adjacent sites with less anthropogenic disturbance [83]. It should also be noted that the HQ based on the total sediment concentration is only a conservative evaluation of the potential ecological risk of metal accumulated in the sediment because only the bioavailable fraction of metals can pose potential risk to the ecosystem [84].…”

“…Therefore, the actual ecological risk could be different from what is indicated by the HQ in this study as total metal concentration applied for the HQ calculation includes both bioavailable metal concentration and non-bioavailable metal concentration [84]. To properly estimate the actual ecological risk of metals accumulated in sediment, it is more important to determine the concentration of bioavailable metal [83].…”