Heavy Metals in Marine Surface Sediments of Daya Bay, Southern China: Spatial Distribution, Sources Apportionment, and Ecological Risk Assessment

Abstract

Daya Bay, especially in the northwestern region, which is a nature reserve with larval economic fish and shrimp populations, is no longer an unpolluted marine environment due to the recent increases in anthropogenic activities. This study collected seasonal surface sediment samples from 20 sites in northwestern Daya Bay to evaluate pollution and ecological risks and to identify possible sources and transport pathways of heavy metals (Cd, Pb, Cr, Cu, Zn, Hg, As). The results showed that all the heavy metal concentrations were below the established primary standard criteria, except for concentrations of Cr in spring, as well as Cu and Zn in autumn at several sampling stations, which had excess rates of 35, 4.76, and 4.76%, respectively. The geoaccumulation index (Igeo) values of heavy metals indicated that all sites had unpolluted to moderate pollution levels. In comparison to the samples collected in autumn, those in spring experienced a higher degree of pollution, particularly Cr and As. The ecological risk indices of heavy metals in sediments ranged from 225.86 to 734.20 in spring and from 196.69 to 567.52 in autumn, suggesting that most sites had a moderate ecological risk or a considerable ecological risk, and very few a had high ecological risk. Moreover, ArcGIS10.2 software was used to visualize their spatial distribution, and the results were similar in both spring and autumn. The results of the Pearson correlation analysis and principal component analysis showed that Cu, Hg, and Pb might be affected by anthropogenic activities, and As might be derived from natural sources such as atmospheric inputs. A cluster analysis showed that heavy metals were mainly affected by the negative impacts of human beings on the environment.

Spatial distribution of trace elements and potential contamination sources for surface sediments of the North-Western Black Sea, Romania

“…Numerous studies in the related literature reported that clay, silt, and organic matter particles are important carriers of TEs in sediments (Rubio et al, 2000;Vaalgamaa and Korhola, 2004;Selvam et al, 2012;Özkan, 2012;Dou et al, 2013;Hu et al, 2013;Xu et al, 2016;Zhao et al, 2017;Perina et al, 2018;Remeikaite-Nikienėet al, 2018;Sun et al, 2020; Values of Pearson correlation coefficient (r) highlighted in bold are different from 0 with a significance level a = 0.05. Wang et al, 2021;Zhou et al, 2022). On the one hand, the finer sediment fractions (clay and silt) have a higher specific surface area than the coarser fraction (sand), giving them more binding sites for the adsorption of TEs and organic matter (Rubio et al, 2000;Xu et al, 2016;Zhou et al, 2022).…”

“…Accumulation of TEs in marine sediments depends on various factors, e.g., water depth, water physicochemical properties (pH, salinity, temperature, dissolved oxygen and organic matter content), sediment composition and texture, intensity/direction of winds, waves, and currents, fluvial, atmospheric, and other natural or anthropogenic inputs (Oros, 2019;Constantinescu et al, 2023). Multivariate analysis, especially PCA, is widely used to identify the main factors affecting the concentration of TEs in sediments and possible pollution sources/transport pathways (Martins et al, 2012;Kahal et al, 2018;Remeikaite-Nikienėet al, 2018;El-Sorogy et al, 2020;Perumal et al, 2021;Vilhena et al, 2021;Wang et al, 2021;Kubra et al, 2022;Zhou et al, 2022).…”

Contamination characteristics, coexistence relationships and health risk assessment of dioxins and metals in topsoil around municipal solid waste incinerator in Hainan, China

“…Actually, existing studies have also found a positive correlation between exposure to these toxic pollutants and development of abnormal endocrine, elevated cancer rates, immunity disorders, and increased risk of diabetes (Wang B. et al, 2019;Hashem et al, 2021). This is because of their enrichment, nonbiodegradability, high-persistency half-life of decades, as well as their inherent toxicity, biogeochemical recycling, and ecological risks (Vassura et al, 2011;Wang et al, 2021). Therefore, it is important to monitor these harmful compounds in the soil around MSW incinerator and estimate their health effects on nearby people.…”