An Interhemispheric Difference in Atmospheric Gaseous Elemental Mercury Isotopes Reveals a New Insight in Oceanic Mercury Emissions
Description
This dataset contains the isotopic compositions of atmospheric gaseous elemental mercury in Terengganu, Malaysia. Methods 1. Sample Collection: Two sampling sites, one inside the Universiti Malaysia Terengganu (M1, 103.088°E, 5.408°N, 0 m) and another inside the Polytechnic of Kuala Terengganu (M2, 103.136°E, 5.330°N, 0 m) were chosen for GEM sampling. GEM samples were collected continuously using chlorine-impregnated activated carbon (CLC, 0.5 g) traps at a 10-day time resolution from December 2019 to January 2021. 2. Preconcentration and Determination of GEM: GEM collected on CLC traps was thermally desorbed into 5 mL of mixed acid trapping solution (40%, 2HNO3/1HCl, v/v) and Hg concentration in the trapping solution was then measured using a cold vapor atomic fluorescence spectroscopy (CVAFS). GEM concentration in each GEM sample was calculated by dividing total Hg mass (ng) detected in the trapping solution by the sampling air volume. 3. Hg Isotope Analysis: Isotope ratios of GEM were measured by MC-ICPMS (Nu II, Instruments, U.K.) at the State key Laboratory of Environmental Geochemistry, CAS (Guiyang, China). MDF signatures of GEM are reported using delta notation (δ) and calculated as follows: δxxxHgGEM = [ (xxxHg / 198Hg) GEM/ (xxxHg / 198Hg) NIST 3133 − 1] × 1000‰ (1) where δxxxHgGEM represents the MDF signatures of GEM in per mil (‰), and xxx refers to the mass number of Hg isotopes (199, 200, 201, 202, and 204). The MIF signatures of GEM are expressed using the capital delta notation (Δ) and calculated based on the Kinetic MDF law as follows: ΔxxxHgGEM = δxxxHgGEM − βxxx × δ202HgGEM (2) where ΔxxxHgGEM represents the MIF signatures of GEM in per mil (‰), and βxxx are 0.252, 0.5024, 0.752, and 1.493 for 199Hg, 200Hg, 201Hg, and 204Hg, respectively. In this study, when the 2sd values of GEM isotopic compositions were lower than the procedural RM 8610, 2sd values of the procedural RM 8610 were used to represent the 2sd of GEM isotopic compositions.