Atmospheric fluxes and marsh‐soil inventories of 7Be and 210Pb
Atmospheric fluxes and marsh‐soil inventories of 7Be and 210Pb
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DOI：
10.1029/jd090id06p10487
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发表时间：
1985-10
影响因子：
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通讯作者：
C. Olsen;I. Larsen;P. Lowry;N. Cutshall;J. F. Todd;G. Wong;W. Casey
中科院分区：
文献类型：
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作者：
C. Olsen;I. Larsen;P. Lowry;N. Cutshall;J. F. Todd;G. Wong;W. Casey
沿海站点(弗吉尼亚州诺福克)和内陆站点(田纳西州橡树岭)两年内7Be的大气通量通常支持1到2.0pCp/cm~2(1 pCI=0.037 Bq)的库存，库存最高通常出现在春季，最低出现在秋季。计算出支持这些清单所需的平均日通量范围为0.013至0.026 pci cm−2 d−1。尽管7Be和210Pb的生产源条件不同，但它们测量的每月总沉降量之间存在高度相关性，反映了冲刷对从大气中消除这两种放射性核素的重要性。土壤和植被覆盖的沼泽岩芯中的铍7的库存与根据大气沉积数据计算的库存相比是有利的。土壤和植被沼泽岩心中的铅210库存可以相对于从其到桶采样器的沉积通量计算的库存进行浓缩(20%-30%)。对这种浓缩的可能解释是，地面植被比水桶更有效地收集干燥的气溶胶(包含短暂的氡子体)，或者树叶是一种有效的捕集含有吸附的210Pb的颗粒的装置，这些颗粒可能会被风或水从未生长的表面侵蚀。沼泽岩芯中7Be和210Pb2种元素的垂直分布和储量受植被的存在和地下水位位置的影响。
The atmospheric flux of 7Be over a 2-year period at a coastal site (Norfolk, Virginia) and at an inland site (Oak Ridge, Tennessee) typically supports inventories ranging from 1.0 to 2.0 pCi/cm2 (1 pCi = 0.037 Bq), with the highest inventories generally occurring in the spring and the lowest occurring in the fall. The calculated average daily fluxes required to support these inventories range from 0.013 to 0.026 pCi cm−2 d−1. Despite the different production-source terms for 7Be and 210Pb, there is a high degree of correlation between their measured total monthly deposition reflecting the importance of washout in removing both radionuclides from the atmosphere. Beryllium 7 inventories in soil and vegetated marsh cores compare favorably with inventories calculated from the atmospheric deposition data. Lead 210 inventories in soil and vegetated marsh cores may be enriched (by 20–30%) in relation to inventories calculated from its depositional flux to bucket samplers. Possible explanations for this enrichment are that above-ground vegetation is more efficient at collecting dry aerosols (containing short-lived radon daughters) than buckets or that foliage is an effective trap for particles containing sorbed 210Pb which may be eroded from unvegetated surfaces by wind or water. The vertical distribution and inventory of both 7Be and 210Pb in marsh cores are affected by the presence of vegetation and the location of the groundwater table.