High resolution studies of cosmogenic beryllium isotopes (10Be) at Law Dome

Energy from the Sun drives the Earth's climate system but this energy varies: there is an 11 year solar cycle and the Sun's intensity has varied over longer timescales. Reconstructing how the Sun's output has varied in past times is crucial to understanding the Earth's past climate which is key to predicting future climate change. Naturally-occurring radioactive isotopes such as 7Be and 10Be are produced in the Earth's atmosphere by cosmic rays, at a rate controlled by the activity of the Sun, and are layered in ice sheets, thus providing a means of reconstructing past solar output.3 x 3" PICO firn cores were drilled immediately in front of snow pit.The 3 pico cores were sampled at 14cm intervals and the sections combined resulting in 16 samples. Some length was lost during transit, especially in the top cores. It was assumed that the lost length was from the breaks in the core as the ends rubbed against each other during transport, and was evenly lost from each break, using the field notes to help. The bottom of each core was assumed to be the lengths as measured in the field.The samples were placed in a melting jar with carrier and left to melt overnight. ~10mL of the samples were retained for water isotope analysis. The samples were filtered and pumped onto cation columns.

太阳辐射驱动着地球气候系统，但该能量存在波动：既存在11年的太阳活动周期，太阳辐照度在更长时间尺度上也发生过变化。重建过去太阳输出的变化情况，对于理解地球古气候至关重要，而古气候研究是预测未来气候变化的核心环节。天然存在的放射性同位素（radioactive isotope）如铍-7与铍-10，由宇宙射线（cosmic rays）在地球大气中生成，其生成速率受太阳活动调控，且会在冰盖（ice sheets）中逐层沉积，因此为重建过去的太阳输出提供了可行途径。3根3英寸的PICO粒雪芯（firn core）在雪坑（snow pit）前方直接钻取。3根PICO粒雪芯以14厘米的间隔进行取样，并将各段合并后得到16个样品。运输过程中存在部分长度损失，尤以顶部冰芯为甚。结合野外记录推断，损失的长度来自运输过程中冰芯端部相互摩擦产生的断裂，且各断裂处的损失长度均匀分布。假定每根冰芯的底部长度以野外实测值为准。将样品置于搭载载体的融样罐中，静置过夜以待完全融化。留存约10 mL的样品用于水同位素分析（water isotope analysis）。随后对样品进行过滤，并将其泵入阳离子交换柱（cation columns）中。