Haining Huang

Huang, H.; Cai, L.; Luo, Y.; Wang, J.; Liu, Y.; Sun, X.; Lin, H., and Wang, W., 2018. Distribution and potential ecological risk assessment of heavy metals in surface sediments of Xiamen Bay. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 125–133. Coconut Creek (Florida), ISSN 0749-0208. The present work envisages the potential ecological risk assessment of heavy metals in surface sediments of Xiamen Bay. Based on the survey of the surface sediments in May 2012, the concentrations of heavy metals Cu, Pb, Zn, Cd, Cr, Hg and As in sediments were 1.2~57.2, 6.7~76.6, 13.3~150.0, 0.035~0.531, 1.48~92.7, 0.018~0.164, 1.9~10.9 mg.kg⁻¹, respectively. Significant positive correlations were observed amongst the concentrations of Cu, Zn, Hg and As and Total Organic Carbon (TOC). PCA analysis data showed the first three main factors shared 72.70% of the total variance. All stations in the studied area recorded Eⁱr < 40 for Cu, Pb, Zn, Cr and As, which were low risk, while Cd reported the highest ecological risk. The results of refractive index (RI) showed that 40.9% of stations in the Xiamen Bay were at a low risk, 45.5% of them were at a moderate risk, while 13.6% were at high ecological risk.

We investigated the dynamics of carbonate system which was greatly modulated by a river plume and coastal upwelling in July 2014 and July 2015 at the east coast of Hainan Island where a fringing reef distributes inshore. By using a three end‐member mixing model, we semiquantitatively estimated the removal of dissolved inorganic carbon (DIC) mediated by biological production in the river plume and upwelled water to be 13 ± 17 and 15 ± 16 μmol kg⁻¹, respectively. The enhanced organic production was mainly responsible for these DIC consumptions in both two regimes, however, nearly a half of DIC removal was attributed to biocalcification in the plume system while it was negligible in the upwelling system. Furthermore, the modeled results over reefs revealed that river plume and coastal upwelling were two major threats of acidification to coral communities at the east coast of Hainan Island during cruises. In comparison, the biological contribution to acidification was limited for balancing between organic production and biocalcification during July 2014 cruise, whereas the acidification was greatly intensified by organic degradation during July 2015 cruise. It was verified that naturally local acidification (physical and biological processes) played a major role in great pH decreases on a short‐term scale, leading to coastal waters more vulnerable to anthropogenic “ocean acidification” (uptake of atmospheric CO₂) by reducing buffering capacity of waters. Finally, effects of acidification associated with other local threats on a fringing reef were further depicted with a conceptual model.