企鹅粪土层中石英砂表面的化学溶蚀形貌及实验模拟

利用电镜扫描的方法分析了南极阿德雷岛Y2湖企鹅粪土沉积层中石英砂微形貌的特征,发现在企鹅粪含量高的沉积层中石英砂表面具有明显的碗状溶蚀坑等化学溶蚀特征,这一溶蚀特征在Y2湖企鹅粪含量低的沉积层和研究区的其他未受企鹅粪影响的沉积环境中均未明显出现。为了揭示这一特殊化学溶蚀现象的作用机制,根据Y2湖企鹅粪土沉积层自然沉积环境,通过条件实验确定在实验室内使用酸性较高的氟溶液(1mol.L-1HF溶液)对石英砂进行溶蚀实验,通过对比分析发现,实验室模拟条件下可以得到与企鹅粪土沉积层中石英砂相近的表面微形貌特征,这表明它们是在相似的过程中形成的。企鹅粪土沉积层酸性高氟环境中可能存在的HF酸化学溶蚀作用是形成企鹅粪土层中石英砂表面特有溶蚀坑的主要原因。在南极特殊的自然条件下碗状溶蚀坑与企鹅粪之间存在一定的因果关系,从而使石英砂的表面微形貌分析成为南极企鹅生态研究的一种新的辅助手段。

CHEMICAL RESOLUTION MICROTEXTURES ON QUARTZ GRAINS IN LAKE SEDIMENTS INFLUENCED BY PENGUIN DROPPINGS AND EXPERIMENTAL SIMULATION

Microtextures analysis of quartz grains from the Y2 lake sediment of Antarctic Ardley Island was performed by Scanning Electron Microscopy(SEM)in order to investigate the forming mechanism of erosion bowled-pit on quartz grains in sediments influenced by penguin droppings.While this special characteristic didn't occure in the Y2 lake sediments without the influence of penguin droppings and other sedimentary environment.Because of penguin droppings' influences,there is a quite high fluorine ion content in the Y2 sediments.To understand the forming mechanism of the special characteristic,we used 1 mol·L-1 HF acid as dissolving solution to erode numerous quartz grains with fresh surfaces,and then compared it with natural features on quartz grains in the sediments.As a result,the micro-textures on the quartz grains by modeling in the laboratory are very similar to those found in the Y2 lake sediments influenced by penguin droppings,indicating that acidity and fluoride-bearing environment is likely the reason of forming the bowled-pit on quartz surface.Therefore,the close association between erosion bowl-pits and penguin droppings under the special natural conditions of Antarctica may provide valuable insight into the investigating on the Antarctic penguin ecology by the other new method of micro-textures analysis of quartz grains.