Drilling, processing and first results for Mount Johns ice core in West Antarctica Ice Sheet

ABSTRACT: An ice core, 92.26 m in length, was collected near the ice divide of the West Antarctica ice sheet during the 2008/2009 austral summer. This paper described the fieldwork at the Mount Johns site (79º55'S; 94º23'W) and presented the first results of the upper 45.00 m record covering approximately 125 years (1883 - 2008), dated by annual layer counting and volcanic reference horizons. Trace element concentrations in 2,137 samples were determined using inductively coupled plasma mass spectrometry. The concentrations obtained for Al, Ba, Ca, Fe, K, Mg, Mn, Na, Sr and Ti are controlled by climate variations, the transport distance, and the natural sources of these aerosols. Natural dust contributions, mainly derived from the arid areas of Patagonia and Australia, are important sources for aluminum, barium, iron, manganese and titanium. Marine aerosols from sea ice and transported by air masses are important sources of sodium and magnesium. Calcium, potassium and strontium showed considerable inputs of both continental dust and marine aerosols.

摘要：本研究于2008/2009年南半球夏季在西南极冰盖冰盖分水岭附近采集了一根总长92.26米的冰芯。本文详述了约翰斯山测点（南纬79°55′，西经94°23′）的野外工作情况，并公布了上部45.00米冰芯记录的首批研究结果：该记录覆盖约125年（1883年至2008年），通过年层计数法与火山参考层位完成定年。本研究采用电感耦合等离子体质谱法（Inductively Coupled Plasma Mass Spectrometry）对2137个样品的微量元素浓度进行了测定。铝（Al）、钡（Ba）、钙（Ca）、铁（Fe）、钾（K）、镁（Mg）、锰（Mn）、钠（Na）、锶（Sr）与钛（Ti）的浓度，受气候变化、气溶胶传输距离以及这些气溶胶的天然源区共同调控。天然粉尘主要源自巴塔哥尼亚与澳大利亚的干旱区域，是铝、钡、铁、锰及钛的重要来源。源自海冰并经气团传输的海洋气溶胶，是钠与镁的重要来源。钙、钾与锶则同时受到大陆粉尘与海洋气溶胶的显著输入影响。