Trace metals in surface sediments of the Taiwan Strait: geochemical characteristics and environmental indication

Abstract

The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd>Pb>Ni>Zn>Cu>Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd>Pb>Ni>Cu>Zn>Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.

Impacts of Human Activities and Environmental Changes on Spatial-Seasonal Variations of Metals in Surface Sediments of Zhanjiang Bay, China

“…Table 2 also shows the metal values of other coastal areas in China. The average concentrations of the studied metals in this study were comparable to the values reported for the surface sediments of the Taiwan Strait (Gao et al, 2016), Xiamen bay (Lin et al, 2014), and Laizhou Bay (Zhuang and Gao, 2014) (Table 2). The metal concentrations in this study were apparently lower than the values reported for the Jinzhou Bay (Li et al, 2012), which is one of the most heavily polluted coastal region in China (Gao et al, 2014;Gao et al, 2016).…”

“…The former assessment methods of sediment metal contamination are based on the total concentrations of metals. In addition to the total concentrations, the geochemical composition of metals is equally important to determine their potential toxicity and threat to ecosystems (Sahuquillo et al, 2003;Gao et al, 2016). According to the study of Perin et al (1985), the acid soluble fraction (F1) of metal with no more than 1% of its total concentration is considered to have no risk to the environment; the percentage of metal in this fraction falling in the range of 1-10% indicates a low risk to the environment; its falling in the range of 10-30% indicates a medium risk to the environment; its falling in the range of 30-50% indicates a high risk to the environment; and the percentage higher than 50% indicates a very high risk to the environment.…”

The Geochemical and Environmental Characteristics of Trace Metals in Coastal Sediment Discharge off the Mailiao Industrial Zone of Central Western Taiwan

“…It is commonly found that the fractions of trace metals in marine sediment analyzed by the Tessier's sequential extraction method generally follow the order: residual (F5) > Fe-Mn oxides (F3) > organic (F4) > carbonate (F2) > exchangeable (F1), except Mn and Pb [27,39,42,[49][50][51][52][53]. However, the organic fraction of Cu frequently ranks as the second important fraction and contributes a significant portion of the total concentrations in some marine environments [27,28,41,49,54].…”