북극 스발바드 롱이어비엔 융빙수의 지화학적 특성 연구: 빙하 융해 - 화학적 풍화 - 탄소순환의 되먹임 = Geochemical charactersitcs of meltwaters collected at Longyearbyen, Arctic Svalbard: Feedback linking glacial melting, chemical weathering and carbon cycle

다국어 초록 (Multilingual Abstract)

Glacial meltwater, once considered a passive component in the global carbon cycle, has recently been recognized as a potentially significant factor. This study investigates the feedback mechanisms of glacial meltwater on the carbon cycle through an analysis of major ions and magnesium isotopes in meltwater samples collected from Longyearbyen, Svalbard. The major ion composition revealed elevated concentrations of calcium, magnesium, bicarbonate, and sulfate, typical of glacial meltwater, along with high sodium concentration. Using chemical weathering pathways and mass balance calculations, the contribution of sulfuric acid-carbonate weathering (SACW) was determined to be 28.4±8.53% (1σ, n=11), sulfuric acid-silicate weathering (SASW) at 42.3±12.6% (1σ, n=11), carbonic acid-silicate weathering (CASW) at 11.1±13.7% (1σ, n=11), and carbonic acid-carbonate weathering (CACW) at 8.84±7.52% (1σ, n=11). These results indicate that the meltwater in the study area is primarily influenced by sulfide oxidation, incongruent silicate dissolution, and carbonate dissolution, a finding supported by variations in magnesium isotope composition. The chemical weathering rates (W) for each weathering pathway were calculated as follows: WSACW = 4.26±2.45 t/km2/yr (1σ, n=11), WSASW = 2.75±1.58 t/km2/yr (1σ, n=11), WCASW = 0.40±0.52 t/km2/yr (1σ, n=11), and WCACW = 1.03±0.96 t/km2/yr (1σ, n=11). The average CO2 consumption rate for the lowermost stream samples was 4.13×105 mol/km2/yr. However, on a geological timescale, the net carbon cycle due to chemical weathering in the entire study area was calculated to be -3.40×105 mol/km2/yr (-15.0 t CO2/km2/yr), indicating an annual release of 15 tons of carbon dioxide into the atmosphere. This study suggests that glacial melt exerts a positive feedback on the global carbon cycle and highlights the importance of considering sulfide mineral weathering, in addition to silicate mineral weathering, in future research on glacial weathering-carbon cycle feedback mechanisms.