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Speciation of Ca in terrestrial water and its role in element cycle in forested ecosystem

陆地水中钙的形态及其在森林生态系统元素循环中的作用

基本信息

批准号：
20540477
负责人：
KOSHIKAWA Masami
金额：
$ 3.49万
依托单位：
National Institute for Environmental Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2012
项目状态：
已结题

项目摘要

In our previous study, we found that acidic deposition in Japan has already resulted in elevated concentrations of NO3- + SO42- in stream waters, and a high level of Ca (instead of Al) is serving as a major counterion for NO3- + SO42-. However, an additional loading of acidic deposition may result in shortage of Ca (essential element for plants) and mobilization of Al (toxic element for plants and fishes). We also found that reactive Al increased in proportion to the DOC/Ca ratio in Japanese stream waters, which imply the higher ratio of (organic ligand concentration)/(competitive cation concentration) in solution enhancing formation of soluble organic aluminum complexes. In this study, we tried to determine concentrations of soluble organic calcium complexes in stream waters in order to evaluate the influence of calcium complex on behavior of aluminum. We determined calcium ion concentration (CaI) using calcium ion selective electrode, reactive calcium concentration (CaR) using ion chromatography, and organic calcium complex concentration as a difference between CaR and CaI. However, we unexpectedly found the tendency of calcium ion selective electrode to overestimate CaI under dilute sample such as stream waters. It was found that more selective method is necessary to determine soluble organic calcium complexes in stream waters

在我们之前的研究中，我们发现日本的酸沉积已经导致沃茨水中NO3- + SO 42-的浓度升高，并且高水平的Ca（而不是Al）作为NO3- + SO 42-的主要反离子。然而，额外的酸沉降负荷可能会导致钙（植物必需元素）和铝（植物和鱼类的有毒元素）的动员不足。我们还发现，在日本流沃茨中，活性铝的增加与DOC/Ca比成比例，这意味着溶液中较高的（有机配体浓度）/（竞争性阳离子浓度）比增强可溶性有机铝络合物的形成。本研究尝试测定溪流沃茨中可溶性有机钙络合物的浓度，以评估钙络合物对铝行为的影响。我们确定钙离子浓度（CaI），使用钙离子选择性电极，活性钙浓度（CaR），使用离子色谱法，和有机钙络合物浓度作为CaR和CaI之间的差异。然而，我们意外地发现，钙离子选择电极的倾向，高估钙离子在稀样品，如流沃茨。结果表明，在测定沃茨中可溶性有机钙络合物时，需要选择性更强的方法