大河影响下的边缘海反风化作用

Reverse Weathering in River-dominated Marginal Seas

在河口与边缘海区域,大量陆源风化产物的输入和强烈的有机物再矿化作用加速了自生硅酸盐矿物和碳酸盐矿物的生成,这一过程与陆地风化作用相反,被称为反风化作用(Reverse weathering)。反风化作用所导致的自生矿物形成通常在短时间内完成,被认为是平衡大气二氧化碳含量,控制海洋中元素平衡的重要过程。反风化作用的研究方法主要分为直接观察法和化学检测法,前者主要用于自生矿物的结构和元素组成的分析,后者则用于自生铝硅酸盐矿物等定量的研究。反风化作用对海洋环境中碳、硅、常量离子(F^-,Li^+,Na^+,K^+,Ca^(2+)和Mg^(2+)等)和金属元素(Fe,Mn和Al等)等的循环具有重要影响,并促使它们在海洋沉积物中长久埋藏。富含金属氧化物的风化产物的输入,大量易降解有机物和生物硅的沉降,强烈的再矿化作用和次氧/厌氧的成岩条件使得河口与边缘海区域成为反风化作用发生的主要场所。

In estuarine regions and marginal seas, reverse weathering refers to the formation of authigenic aluminosilicate and carbonate minerals promoted by large inputs of terrestrial weathering products and intense remineralization of Sedimentary Organic Carbon （SOC）, which is opposite to land weathering process. Compared with the process in open ocean, the formation of authigenic aluminosilicate and carbonate minerals caused by reverse weather/ng in estuarine regions and marginal seas is rather rapid, playing an important role in the maintenance of ocean acidity and elements cycles. At present, there are two research methods regarding the reverse weathering process, i. e., direct observation and chemical detection. The first method is used to study the structure and chemical composi- tion of authigenic minerals and the second is mainly used to do quantified studies of authigenic minerals. The reverse weathering is very important to the cycles of Si, C, major ions （ F^-, Li^＋, Na^＋, K^＋, Ca^2＋ and Mg^2＋ ）, and alkali metal cations （ Fe, Mn and Al） in marine environments, which promotes the burial of these elements in marine sediments. Due to large inputs of weathering products rich in Fe, Mn and AI oxides, precipitation of labile OC and biogenic silica, intense remineralization process and suboxic/anoxic conditions, estuarine and marginal seas are suitable sites for reverse weathering studies. The reverse weathering studies in sub-tropical and temperate estuaries should be emphasized in the future.