Mercury isotope compositions in seawater and marine fish revealed the sources and processes of mercury in the food web within differing marine compartments

Mercury Isotope Composition in Open Water Corals of South China Sea: Implication for Atmospheric Mercury Deposition Pathways Into Tropical Oceans

“…Our calculation is further supported by the linear positive correlation between coral Δ 200 Hg and Δ 199 Hg (R 2 = 0.42, P < 0.001, n = 29, Figure S5 in Supporting Information S1). A similar relationship was observed in northern (Jiskra et al, 2021), PRE (Pearl River estuary), HNI (Hainan Island), XSI (Xisha Islands) (Yang et al, 2023), and Nansha Islands (this study). The atmospheric deposition sources are shown as horizontal bars in blue for Hg(0) and purple for reactive and rainfall Hg(II); the dashed line represents the mean and the shaded area the interquartile range (IQR).…”

“…A recent calculation (Yang et al, 2023) based on the Δ 200 Hg (0.10 ± 0.04‰, 1SD, n = 34) measured in pelagic fishes of the SCS showed that ∼74% marine Hg was derived from atmospheric Hg(II) deposition, which is much higher than our estimates. We suggest that shallow-water corals can provide a more reliable constraint on atmospheric sources to the ocean than the pelagic fishes.…”

“…The most striking feature of the Hg isotope compositions in our corals is that they are largely overlapped with values of surface particles (δ 202 Hg = −0.28 ± 0.47‰; Δ 199 Hg = −0.03 ± 0.19‰; Δ 200 Hg = 0.02 ± 0.08‰, 1SD, n = 14, equatorial/subtropical Pacific, northern Atlantic and Mediterranean Sea, Jiskra et al., 2021; Motta et al., 2019, 2022) and bulk seawaters of open oceans (δ 202 Hg = −0.27 ± 0.38‰; Δ 199 Hg = 0.08 ± 0.12‰; Δ 200 Hg = 0.02 ± 0.05‰, 1SD, n = 12, northern Atlantic and Mediterranean Sea, Jiskra et al., 2021) (Figure 3). Notably, the Δ 199 Hg and Δ 200 Hg values of our Nansha corals (0.03 ± 0.06‰ and 0.03 ± 0.03‰, 1SD, n = 29) are almost identical to those of filtered seawater from the nearby Xisha (0.04 ± 0.03‰ and −0.01 ± 0.05‰, 1SD, n = 3, Yang et al., 2023). The Hg isotope compositions recorded in corals are quite different from Chinese coastal seawaters (Bohai and Yellow Sea, depth 0–50 m: δ 202 Hg = −1.35 ± 0.64‰; Δ 199 Hg = 0.28 ± 0.14‰; Δ 200 Hg = 0.00 ± 0.04‰, 1SD, n = 8, Liu et al., 2021; Meng et al., 2020), which are typically characterized by much negative δ 202 Hg and positive Δ 199 Hg and Δ 200 Hg values.…”

“…Box plots showing Δ 199 Hg (a) and Δ 200 Hg (b) of seawater and biota (fish except for coral in Nansha Islands) in Med. Sea (Mediterranean Sea)(Jiskra et al, 2021), PRE (Pearl River estuary), HNI (Hainan Island), XSI (Xisha Islands)(Yang et al, 2023), and Nansha Islands (this study). The atmospheric deposition sources are shown as horizontal bars in blue for Hg(0) and purple for reactive and rainfall Hg(II); the dashed line represents the mean and the shaded area the interquartile range (IQR).…”

“… Plots of global annual total precipitation for 2000–2019 (mm, Grand Average Precipitation Climatology, NASA, 2020). The white triangles denote locations of published Hg isotope data of seawater, including the Mediterranean Sea (Jiskra et al., 2021), Atlantic Ocean (Jiskra et al., 2021), and SCS (including Pearl River estuary, Hainan Island, and Xisha Islands, Yang et al., 2023); the white diamond denotes the location of corals in this study (Nansha Islands). …”