Trace metal pollution risk assessment in urban mangrove patches: Potential linkage with the spectral characteristics of chromophoric dissolved organic matter

Metal Pollution and Bioaccumulation in the Nhue-Day River Basin, Vietnam: Potential Ecological and Human Health Risks

“…When emRI was compared between seasons, it was observed that metals in the spring have a higher ecotoxicological risk in rivers but not in ponds (p < 0.03; Figure 4C; Table 4). The emRIs in this study were approximately ten times higher than those found in the Tamsui River in northern Taiwan, with less than 2.3 at all studied sites [32]. Cd was the most significant contributor to the river sediment's potential ecological risk, which may adversely affect the surrounding riverine ecosystems, including aquaculture ponds.…”

“…The modified Nemerow Pollution Index (mPI) [30,31] and the expanded, modified potential ecological risk index (emRI) [32] were used to assess sediment quality and potential ecological risks, considering the variation in toxicity of each metal and the effects of the element mixture in sediment, particularly considering the complex sediment behavior.…”

“…However, the composition of metals in sediment varies by ecosystem, depending on environmental conditions and pollution sources. Therefore, emRI is more appropriate for estimating the potential ecological risk of a given ecosystem with its specific pollution pattern [32]; Er denotes a nominal potential ecological risk factor; Tr denotes a dimensionless toxic factor for a specific element: Cd = 30, Pb = Cu = 5, and Zn = 1. Because data for the background level of metals in this river basin and region are unavailable, the upper continental crust values [35] were used as the background in this study (Cd = 0.098, Cu = 25, Pb = 20, Zn = 71 µg/g dw).…”

“…However, only using the emRI index does not allow us to categorize the risk level of a given ecosystem, which is a significant limitation, so the calculated result(s) need to be compared with the thresholds to determine the current risk level of the tested ecosystem. As those thresholds are not yet available for use with emRI, we combined the findings from Hakanson [33] and Hong et al [32] to calculate them as given in Table 3, which clearly shows that the emRI ranges correspond to the ecological risk levels of the ecosystem, and provide a more accurate method. These new ecological risk thresholds for emRI were calculated as the relative values of the potential ecological risk index per toxic unit of the target toxic substance mixture, rather than as a sum of the potential ecological risk factors for all tested contaminants as was calculated for RI [33].…”

“…In ponds, no seasonal variation was observed (p > 0.05). Similarly, Hong et al [32] proposed the emRI index to improve the method for determining the potential ecological risk, which can be applied to any condition (contaminant combinations and available testing methods). However, only using the emRI index does not allow us to categorize the risk level of a given ecosystem, which is a significant limitation, so the calculated result(s) need to be compared with the thresholds to determine the current risk level of the tested ecosystem.…”