Dissolution and Etching Rate of Hornblende Under Ambient Conditions

宾夕法尼亚州立大学地球科学系的Susan L. Brantley博士和材料科学与工程系的Carol G. Pantano博士获得了环境地球化学和生物地球化学项目的这一奖项，以表彰他们对角闪石风化的研究。这项工作是由化学部和地球科学部共同支持的。在实验室条件下，将研究蚀坑的发展速度和角闪石的溶解速度，并与在土壤中观察到的角闪石蚀刻速度进行比较。还将研究细菌对角闪石溶解的影响，以便分离与矿物表面的直接和间接微生物相互作用。表面的变化将用x射线光电子能谱和二次离子质谱分析。不仅角闪石风化的速率将被确定，而且氧气、酸度、坑的形成和细菌反应的作用也将被确定。角闪石的溶解是花岗岩岩性土壤向自然水体中提供铁和镁的主要来源，并通过硅酸盐风化作用减少大气中二氧化碳的减少。来自地球化学、材料和微生物学的方法将用于综合了解角闪石风化的性质，并开发一个可用于实验室研究的模型。

This award in the Environmental Geochemistry and Biogeochemistry Program is made to Dr. Susan L. Brantley, Department of Geosciences, and Dr. Carol G. Pantano, Department of Materials Science and Engineering, both of Pennsylvania State University, for research on weathering of hornblende. The work is jointly supported by the Division of Chemistry and the Division of Earth Sciences. The rate of etch pit development and the rate of dissolution of hornblende under laboratory conditions will be studied and compared to hornblende etching rates observed in soils. The effects of bacteria on hornblende dissolution will also be investigated in order to isolate direct and indirect microbial interactions with the mineral surface. Changes in the surface will be analyzed using x-ray photoelectron spectroscopy and secondary ion mass spectrometry. Not only will the rate of hornblende weathering be determined, but the role of oxygen, acidity, pit formation, and bacterial reactions will be determined. Dissolution of hornblende is the principal source of iron and magnesium to natural waters from soils developed on granite lithologies and is a contributor to reduction of atmospheric carbon dioxide reduction through silicate weathering. Methods from geochemistry, materials and microbiology will be used to achieve an integrated understanding of the nature of hornblende weathering in the field and to develop a model that can be used in laboratory investigations.