Post-depositional loss of nitrate and chloride in Antarctic snow by photolysis and sublimation: a field investigation

New Estimation of the NOx Snow‐Source on the Antarctic Plateau

“…That said, note that this extrapolation to the continent is a first order estimate as it does not consider the differences on the ‐folding depth and the quantum yield variations with temperature and pH, especially at the coast; neither the latitude's differences modifying the ratios used in Equation . Indeed, Noro and Takenaka (2020) recently showed that at a coastal site called H128 (23'S, 34’E) that is located approximately 100 km away from the Japanese Syowa Station in East Antarctica, 50 of the nitrate on surface snow is lost by photolysis. Additionally, they suggest that a photic zone of 45 cm depth is observed at a low impurity coastal site such as H128, making the photic zone at the coast close to the one observed at the higher plateau.…”

“…That said, note that this extrapolation to the continent is a first order estimate as it does not consider the differences on the E e -folding depth and the quantum yield variations with temperature and pH, especially at the coast; neither the latitude's differences modifying the ratios used in Equation 11. Indeed, Noro and Takenaka (2020) depth is observed at a low impurity coastal site such as H128, making the photic zone at the coast close to the one observed at the higher plateau. Ideally, a 3-dimensional global chemical transport model of this snowpack source, supported by more FC experiments performed at strategic locations in Antarctica, to constrain the nitrate photolysis and the NO x E production, may be able to answer this question.…”

Sunlight-driven nitrate loss records Antarctic surface mass balance

“…Because 14 NO3is more readily photolyzed than 15 NO3, the δ 15 NNO3 of NO3remaining in the snow will increase from its initial depositional value of ≈ −20 to +20 ‰ to values as high as +400 ‰ [19][20][21][22][23][24][25][26] as the isotopically lighter photolytic NOx is ventilated and lost to the atmosphere. Although NO3can also be lost through HNO3 volatilization, we interpret δ 15 NNO3arc solely through photolysis as volatilization does not strongly fractionate NO3and is a very minor component of NO3loss outside of the warmest coastal zones 22,27,28 . Additionally, while the oxygen in NO3also undergoes isotopic fractionation through photolysis, its interpretation is complicated by isotopic interactions with snow and water vapor 22,23,29 and is not further discussed here.…”