Spatiotemporal Characterization of Mercury Isotope Baselines and Anthropogenic Influences in Lake Sediment Cores

• Published in: Global Biogeochemical Cycles
• Main Authors: Lee, Ju Hyeon, Kwon, Sae Yun, Yin, Runsheng, Motta, Laura C., Kurz, Aaron Y., Nam, Seung‐il
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 2021
• Subjects: anthropogenic; Minamata Convention; Mercury isotope; sediment core; baseline; Geological Sciences; Science; Arctic
• Online Access: https://hdl.handle.net/2027.42/170254; https://doi.org/10.1029/2020GB006904

Increasing mercury isotope ratios from pre- industrial (1510- 1850) to present- day (1990- 2014) in lake sediment cores have been suggested to be a global phenomenon. To assess factors leading to spatiotemporal changes, we compiled mercury concentration (THg) and mercury isotope ratios in 22 lake sediment cores located at various regions of the world. We find that the positive δ202Hg shifts together with THg increases from pre- industrial to present- day are a widespread phenomenon. This is caused by increased contribution of mercury from local to regional anthropogenic mercury emission sources, which lead to higher sediment δ202Hg (- 1.07 ± 0.69- °, 1 SD) than pre- industrial sediments (- 1.55 ± 0.96- °, 1 SD). The positive Î 199Hg shifts were observed in 15 lake sediment cores, which have low pre- industrial Î 199Hg (- 0.20 ± 0.32- °) compared to the sediment cores with near- zero to positive pre- industrial Î 199Hg (0.08 ± 0.07- °). The magnitudes of δ202Hg (r2 = 0.09) and Î 199Hg (r2 = 0.20, both p > 0.05) changes from pre- industrial to present- day did not correlate with the magnitude of THg changes. Instead, the magnitudes of δ202Hg and Î 199Hg changes decreased with increasing pre- industrial δ202Hg and Î 199Hg values, suggesting that the baseline mercury isotope ratios play a more important role in determining the magnitude of mercury isotope changes compared to the degree of THg input. We suggest that the spatiotemporal assessments of δ202Hg in lake sediment cores can be used as an important proxy for monitoring changes in anthropogenic mercury sources for the Minamata Convention on Mercury.Key PointsPositive δ202Hg shifts together with mercury concentration in lake sediment cores from pre- industrial to present- day period are a widespread phenomenonMagnitudes of δ202Hg and Î 199Hg changes are determined by the pre- industrial or baseline values in the sediment cores rather than the degree of mercury inputSediment δ202Hg can be used as a proxy for monitoring changes in ...