First sulfur isotope measurements in central Greenland ice cores along the preindustrial and industrial periods

Abstract

[1] Sulfur isotopes of sulfate have been measured in a discontinuous set of polar ice core samples from Summit, central Greenland, covering the preindustrial (from the fourteenth to the eighteenth century) and industrial (from 1872 to 1969 A.D.) periods. Results have been used to estimate the different source contributions to the deposited sulfate and their evolution along the last centuries. They indicate that the preindustrial background sulfate budget is slightly dominated on a year-round average by marine biogenic emissions, amounting to close to half of the non-sea-salt sulfate (49%). The second contribution is provided by continental sources of secondary sulfate, including background volcanism and, to a lesser extent, continental biota (44% of the non-sea-salt sulfate). Sulfur emitted by relatively weak eruptions is found to be largely depleted in 34 S compared to bulk volcanic S, suggesting an efficient washout of the heavier isotope during the tropospheric transport. The impact of human-driven emissions on the sulfate deposited in central Greenland ice is visible in isotope data as early as 1870 A.D. The isotopic signature of anthropogenic sulfur deposited during the twentieth century is found to be constant (d 34 S % + 3.0 ± 1.5%), regardless of the changes of dominant source regions and emission processes. This signature is slightly but measurably lighter than the one reported for Arctic haze pollution events.

Sulfur isotope variability of oceanic DMSP generation and its contributions to marine biogenic sulfur emissions

“…3), taking into account fractionations associated with degradation of DMSP to DMS. Marine biogenic sulfate δ 34 S NSS-SO4 values have been estimated to range from +14 to +22‰ (19), with measurements of Pacific aerosols being +15.6 ± 3.1‰ (21), North Atlantic coastal aerosols being +22‰ (22), and Greenland ice cores being +18.6 ± 0.9‰ (23). These are similar to the DMS sulfur isotope compositions predicted on the basis of DMSP measurements.…”

“…The proportion of NSS-SO 4 2− and MSA derived from DMS and DMSP has previously been explored using sulfur isotopes (19)(20)(21). The sulfur isotope compositions of these atmospheric oxidation products have been estimated from measurements of aerosol sulfate (19,21,22), measurements of MSA (20), and measurements of the sum of sulfate and MSA in ice cores (23). These constraints have been used, in turn, by other studies to constrain the fraction of NSS-SO 4 2− in atmospheric aerosols.…”

Biogenic, anthropogenic and sea salt sulfate size-segregated aerosols in the Arctic summer

“…Sulfur isotope apportionment in the Arctic assumes a δ 34 S value of +21 ‰ ± 0.1 (Rees et al, 1978), +18.6 ‰ ± 0.9 (Sanusi et al, 2006;Patris et al, 2002) and +3 ‰ ± 3 (Li and Barrie, 1993;Nriagu and Coker, 1978;Norman et al, 1999) for sea salt, biogenic and anthropogenic δ 34 S values, respectively. These values were used to find sea salt, biogenic and anthropogenic fractions in this study.…”

Atmospheric Composition and Biogeochemical Cycles over the Last Million Years

“…On the other hand, measurements of methanesulfonic acid (MSA), a compound produced exclusively by DMS oxidation, should be a means to distinguish biogenic sulfates from volcanic and anthropogenic sulfates. Recent studies on sulfur isotopes ( 34 S/ 32 S) have been successfully carried out on sulfate in ice, shedding significant light on their three origins (Patris et al, 2002). The lack of information on organic aerosols in ice concerns primarily the secondary fractions that outweigh the primary fractions in the present atmosphere.…”