The Effect of Particle Composition and Concentration on the Partitioning Coefficient for Mercury in Three Ocean Basins

Abstract

The downward flux of sinking particles is a prominent Hg removal and redistribution process in the ocean; however, it is not well-constrained. Using data from three U.S. GEOTRACES cruises including the Pacific, Atlantic, and Arctic Oceans, we examined the mercury partitioning coefficient, Kd, in the water column. The data suggest that the Kd varies widely over three ocean basins. We also investigated the effect of particle concentration and composition on Kd by comparing the concentration of small-sized (1–51 μm) suspended particulate mass (SPM) as well as its compositional fractions in six different phases to the partitioning coefficient. We observed an inverse relationship between Kd and suspended particulate mass, as has been observed for other metals and known as the “particle concentration effect,” that explains much of the variation in Kd. Particulate organic matter (POM) and calcium carbonate (CaCO3) dominated the Hg partitioning in all three ocean basins while Fe and Mn could make a difference in some places where their concentrations are elevated, such as in hydrothermal plumes. Finally, our estimated Hg residence time has a strong negative correlation with average log bulk Kd, indicating that Kd has significant effect on Hg residence time.

Upwelling Enhances Hg Particle Scavenging in the California Current Ecosystem

“…This is in line with our previous nding that the open ocean generally exhibits higher K d values when compared to the coastal regions due to the so-called particle concentration effect. 30 Additionally, K d in the SSF is similar to that in the LSF (LSF log K d , upwelling: 6.61 ± 0.38) (t-test; P-value = 0.42 > 0.05). This similarity indicates that K d is a consistent value present in the SSF and LSF.…”

Distribution of Mercury in Soil, Water, and Vegetable Fern in a Former Gold Mining Area – Evidence from Nagan Raya Regency, Aceh Province, Indonesia

“…Nonetheless, in this present study, the presence of mercury was not detected in all sampling points (Table 4). The absence of mercury could be influenced by geographical factor, phase concentraiton [Cui et al, 2021], salinity [Bełdowska et al, 2015], and the mixing of river and sea waters [Saniewska et al, 2022]. There is a possibility that the mercury has been carried to the ocean, as suggested by a previous research [Saniewska et al, 2022].…”

Mercury Isotopes in Deep-Sea Epibenthic Biota Suggest Limited Hg Transfer from Photosynthetic to Chemosynthetic Food Webs

“…Meanwhile, the sinking particles and seafloor sediments could also release Hg during remineralization and diagenesis processes. 4,5,8,9 In addition, geogenic Hg could be discharged into the deep oceans via submarine hydrothermal vents mostly surrounding mid-ocean ridges, back-arc basins, and submarine volcanic arcs as well as possibly cold seeps located at continental slopes near the tectonic plate boundaries. 10−15 To date, submarine geogenic Hg is poorly constrained but is potentially important in volcanic-and hydrothermal-active areas.…”

“…In the open oceans, MMHg is thought to be mostly derived from in situ production within the upper marine (<1000 m) waters. , However, it is still uncertain if MMHg could be in situ produced in deep marine (>1000 m) waters and sediments. Deep oceans receive Hg from upper oceans via particle settling, , deep water formation, and occasionally carrion (e.g., whalefall) . Thus, anthropogenic Hg can be brought into deep oceans and finally buried into sediments.…”

“…Thus, anthropogenic Hg can be brought into deep oceans and finally buried into sediments. Meanwhile, the sinking particles and seafloor sediments could also release Hg during remineralization and diagenesis processes. ,,, In addition, geogenic Hg could be discharged into the deep oceans via submarine hydrothermal vents mostly surrounding mid-ocean ridges, back-arc basins, and submarine volcanic arcs as well as possibly cold seeps located at continental slopes near the tectonic plate boundaries. − …”