Coral Ba/Ca and Mn/Ca ratios as proxies of precipitation and terrestrial input at the eastern offshore area of Hainan Island

Chemical characterization of deep-sea corals from the continental slope of Santos Basin (southeastern Brazilian upper margin)

“…Also, in seawater, this ratio makes it possible to trace other elements such as Silica, influenced by coastal river sources, with the concentration of Ba increasing with depth (LaVigne et al, 2010;Anagnostou et al, 2011). The Ba/Ca ratio ranged between 0.009 and 0.027 mmol mol -1 , similar to the values obtained by studies carried out in different coral species in the Atlantic and Pacific Oceans, the Mediterranean Sea, and the South China Sea (Anagnostou et al, 2011;Hasegawa et al, 2012;Jiang et al, 2017). Our values correlated positively and significantly with depth (r= 0.54, p= 0.04).…”

“…The Mn/Ca ratio in deep-sea corals is dependent on oceanographic processes such as advection, vertical mixing, and upwelling, used as suspended sediment proxies associated with river discharge, land-use changes, and coastal development (Carriquiry and Villaescusa, 2010;Chen et al, 2010). The values obtained for Mn/Ca in the Trevizani et al present study surpass those found in studies conducted in the Pacific Ocean and the South China Sea, but these were carried out on the species Pavona gigantea, Pavona clivosa, Porites panamensis, and Porites lutea, which are reef-building species (Jiang et al, 2017).…”

“…The correlations between the elementary ratios and the environmental parameters depth, salinity, and temperature are shown in Table S1. In general, the Ba/Ca, Fe/Ca, and Mn/Ca ratios in corals are proxies for terrestrial fluxes (Jiang et al, 2017), and Pb/Ca is a tracer of anthropogenic input (Saha et al, 2016). These ratios correlated positively and significantly in the present study.…”

“…Corals absorb dissolved Ca and carbonate ions from seawater during the growth process, incorporating them into their skeletons. Metals such as Sr, Mg, Mn, and Ba can replace Ca within the aragonite structure (Hanna and Muir, 1990;Saha et al, 2016;Jiang et al, 2017). In addition, metals can be absorbed by trapping particulate matter in the pores of corals, through adsorption by the skeletal surface, and through the formation of complexes with organic matter (Livingston and Thompson, 1971;Saha et al, 2016;Jiang et al, 2017).…”

“…The Ba/Ca ratio in corals is related to the behavior of nutrients in seawater (Jiang et al, 2017). The main source of Ba in the seafloor sediments is Barite (BaSO 4 ), indicating the presence of methane fluxes (Joseph et al, 2013).…”