摘要
如何利用湖泊/海洋沉积物地球化学代用指标有效地指示环境很大程度取决于元素的来源及其在沉积物中赋存形态的确定.对位于半干旱区的内蒙古岱海14个沉积物样品的连续提取实验及18个元素在水可溶态、可交换态、碳酸盐结合态、铁锰氧化物结合态、有机物结合态及残留态等六种赋存相态中含量变化进行了测试和研究,结合沉积物的矿物组成,结果表明在岱海流域内只经历了较弱的化学风化过程,除了Ca和Sr外,其他元素主要赋存于残留态中,只发生了很小程度的活化溶解.受元素亲合性和湖水物理化学状态的制约,出溶的Sr与Ca的赋存相态基本一致,而出溶的Pb、Be、Co、Cu、K、Mn、Fe等元素则与自生碳酸盐、有机质表现出一定的亲合性.元素在不同赋存相态中分布为地球化学环境代用指标的提取和解释提供了机理性的实验依据.
Environmental interpretation of geochemical proxies of lake/ocean sediments largely depends on an understanding of where elements are from and of how elements bound to various fractions in the sediments. Fourteen samples from Lake Daihai, Inner Mongolia , located in semiarid zone, were carried out a sequential extraction experiment and analyzed eighteen elements concentration by ICP-AES or AAS in each chemical fractions defined as follows: soluble, exchangeable, bound to carbonate, bound to Fe-Mn-ox-ides, bound to organic matter and residual. Our results indicate that weak chemical weathering was proceeded under climate conditions in the Lake Daihai watershed, resulting that most of the elements determined are in residual due to little activation during weathering, except Ca and Sr, by combining with detrital minerals of predominantly plagioclase. Meanwhile, controlled by element affinity and lake water physicochemical conditions, leached both Sr and Ca are in the same fractions with good correlation, whereas other activated elements including Pb, Be, Co, Cu, K, Mn, Fe etc are predominantly associated with the fractions of bound to carbonate and/or organic matter. Consequently, element distribution in various chemical fractions provides a useful experimental evidence for selection and interpretation of some geochemical proxies.
出处
《湖泊科学》
EI
CAS
CSCD
北大核心
2005年第1期47-53,共7页
Journal of Lake Sciences
基金
国家自然科学基金(40373004)
中国科学院院南京地理与湖泊研究所所长特别支持项目(CXNIGLAS-A01-2)联合资助
