Transformations of snow chemistry in the boreal forest: Accumulation and volatilization
Transformations of snow chemistry in the boreal forest: Accumulation and volatilization
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北方森林雪化学的变化：积累和挥发
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
M. Tranter
中科院分区：
文献类型：
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作者：
J. Pomeroy;T. Davies;H. G. Jones;P. Marsh;N. Peters;M. Tranter
本文研究了寒冬期间加拿大西部北方森林北部和南部地区北方森林积雪中具有重要生态意义的无机化学物质（主要是no3 -N）积累和损失的过程和动态，并利用西北地区Inuvik和加拿大萨斯喀彻温省Waskesiu的野外观测资料，将北方森林积雪的化学转化和物理过程联系起来。研究了雪水当量、no3 -、so42 -等主要离子的配置和越冬转化。除了大气气溶胶浓度较高的地区外，在这两个地点都没有发现化学物质在拦截雪中干沉积增加的证据。在Inuvik，拦截的雪中so42 -和Cl -的浓度比远离树木的地表雪高5到6倍。Inuvik的so4 -S和Cl的负荷在离单个树干最近的0.5 m范围内相应地增加了3倍。没有快速升华的冠层拦截影响的雪的测量没有提供从拦截雪中离子挥发的证据。在截获的积雪升华率显著的地方，冠层下积雪中的离子负荷表明，每升华一个雪团，no3 -的挥发效率约为62%。将这一测量结果外推到在其他南方北方环境中观测到的升华损失表明，在拦截的雪升华过程中，19-25%的no3 -雪输入可能会损失。在高降雪量、高氮负荷的南方北方森林（魁北克），升华过程中的N损失量可能很大，其中估计可能的季节性no3 -挥发为0.42 kg no3 -N ha -1。讨论了北方森林氮通量对气候和林冠变化的敏感性，以及冬季氮损失对北方森林氮收支的影响。
This paper examines the processes and dynamics of ecologically-important inorganic chemical (primarily NO 3 -N) accumulation and loss in boreal forest snow during the cold winter period at a northern and southern location in the boreal forest of western Canada, Field observations from Inuvik, Northwest Territories and Waskesiu, Saskatchewan, Canada were used to link chemical transformations and physical processes in boreal forest snow. Data on the disposition and overwinter transformation of snow water equivalent, NO 3 - , SO 4 2- and other major ions were examined. No evidence of enhanced dry deposition of chemical species to intercepted snow was found at either site except where high atmospheric aerosol concentrations prevailed. At Inuvik, concentrations of SO 4 2- and Cl - were five to six times higher in intercepted snow than in surface snow away from the trees. SO 4 -S and Cl loads at Inuvik were correspondingly enhanced three-fold within the nearest 0.5 m to individual tree stems. Measurements of snow affected by canopy interception without rapid sublimation provided no evidence of ion volatilization from intercepted snow. Where intercepted snow sublimation rates were significant, ion loads in sub-canopy snow suggested that NO 3 - volatized with an efficiency of about 62% per snow mass sublimated. Extrapolating this measurement from Waskesiu to sublimation losses observed in other southern boreal environments suggests that 19-25% of snow inputs of NO 3 - can be lost during intercepted snow sublimation. The amount of N lost during sublimation may be large in high-snowfall, high N load southern boreal forests (Quebec) where 0.42 kg NO 3 -N ha -1 is estimated as a possible seasonal NO 3 - volatilization. The sensitivity of the N fluxes to climate and forest canopy variation and implications of the winter N losses for N budgets in the boreal forest are discussed.