Dome Fuji, Antarctica 1993 Shallow Core 1 cm Electrical Conductivity Measurements (ECM)

The climatic record from the 2503m Dome Fuji (Antarctica) ice core was analyzed using ECM (electrical conductivity measurements). The ECM current respond to acid. Dome Fuji ice was measured to be highly acidic, with background values of 2-7 micro M, and had 4500 major peaks with acidities of up to 90 micro M. Method is as follows. After equilibrating for 1 day at the cold-room temperature at Dome F, all core sections, which were 93mm in diameter and about 1.7m long, were cut parallel to their central axes into 60% and 40% portions by volume. The cut surfaces of the 60% portions were further finished with a microtome knife to make fresh, smooth surfaces. Immediately after a surface was cut and finished, two ECM electrodes were dragged along the surface with a 1250V d.c. potential difference. The entire ice core from depths of 112.65 to 2503.07m was covered by the measurements. Although the signal was sampled every 2mm, we plot only 10mm running averages of the data to remove noise. The ECM electrodes were manually dragged along the ice. The electrodes were aligned perpendicular to the core axis and 15mm apart. The effective resolution of the electrodes approximately equaled the distance between the electrodes (15mm); based on a physical principle that the electrical field decreases inversely proportional to the distance from a given location to each electrode. Within this distance, about 65% of the lines of electrical force cross. Measurement temperature is described in Fujita et al.(2002). All of the measured data were converted to values equivalent to -25C. For details, please see Fujita et al.(2002).本研究针对南极富士穹顶（Dome Fuji）2503米冰芯所获取的气候记录，采用导电率测量法（electrical conductivity measurements，ECM）开展分析。ECM电流对酸性物质具有响应。经测量，富士穹顶冰芯呈强酸性，背景值为2~7微摩尔（micro M），共存在4500个主要酸度峰值，最高酸度可达90微摩尔（micro M）。具体实验方法如下：将冰芯段置于富士穹顶冷库温度下平衡1天后，对所有直径93毫米、长约1.7米的冰芯样品，沿其中心轴平行切割为体积占比60%和40%的两部分。对占比60%的部分的切割面，进一步使用切片机刀具进行修整，以获得新鲜平整的表面。在冰面切割修整完成后，立即使用两个ECM电极沿冰面拖动，施加1250伏特的直流电势差。本次测量覆盖了深度112.65米至2503.07米的全部冰芯段。尽管信号采样间隔为2毫米，但为去除噪声，我们仅对数据进行10毫米滑动平均后进行展示。ECM电极通过手动方式沿冰面拖动，电极与冰芯轴垂直对齐，且间距为15毫米。根据电场强度与到电极的距离成反比的物理原理，电极的有效分辨率近似等于电极间距（15毫米）；在此间距范围内，约65%的电力线会发生交叉。测量温度的详细信息参见Fujita等人（2002）的研究。所有测量数据均被转换为等效于-25℃下的数值。更多细节请参见Fujita等人（2002）的研究。