Firn Accumulation Processes in Taylor Dome, Vostok and Siple Dome Ice Using Cosmogenic 14 C and 10Be as Tracers

9909484Lal该奖项是对三年资助的支持，目的是利用宇宙源原位碳14(14C)和宇宙源铍10(10Be)作为放射性示踪剂，建立南极洲几个地点沉积的上层冰中积雪和物理过程的历史。这项拟议的研究源于最近对GISP2全新世宇宙成因现场14C和几个南极冰样的研究，这些样品中的14C浓度与理论预期值相比存在显著差异。GISP2样品的14C含量与预期大致相当，但南极样品的14C含量不足30%-50%或更多。这些结果表明，在缓慢积累的冰样中(如在南极洲发生的)，植入14C的宇宙线不知何故部分丢失，但在高积累区的样本中得到定量保存。这些结果表明，宇宙成因的14C沉积后，由于重结晶、升华/蒸发和再沉积等过程，其浓度在FIRN中降低。为了量化这些过程，还将测量冰样中的大气宇宙成因10Be。由于10Be和14C对固化过程有不同的响应，因此同时研究它们有助于阐明这些过程的性质和重要性。泰勒穹顶、沃斯托克和西普穹顶的样品都将被研究。

9909484LalThis award is for support for three years of funding to develop a history of snow accumulation and physical processes occurring in the upper layers of ice deposited at several sites in Antarctica, using cosmogenic in-situ Carbon-14 (14C) and cosmogenic Beryllium-10 (10Be) as radiotracers. The proposed research emerges from recent studies of cosmogenic in-situ 14C in GISP2 Holocene and several Antarctic ice samples, which revealed marked differences in the 14C concentrations in the samples, compared to the theoretically expected values. The GISP2 samples have about the expected amount of 14C but the Antarctic samples are deficient by 30-50% or more. These results suggest that in slowly accumulating ice samples (such as occur in Antarctica), the cosmic ray implanted 14C is somehow partially lost, but quantitatively preserved in samples from areas of high accumulation. These results suggest that after deposition of the cosmogenic 14C, its concentration is decreased in firn due to processes such as recrystallization, sublimation/evaporation and redeposition. In order to quantify these processes, the atmospheric cosmogenic 10Be in ice samples will also be measured. Since 10Be and 14C have different responses to the firnification processes, their simultaneous study can help to elucidate the nature and importance of these processes. Samples from Taylor Dome, Vostok and Siple Dome will all be studied.