Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Italy
Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Italy
复制标题
意大利特拉帕尼浅层超盐日光盐场中碳酸盐系统参数沿盐度梯度的生物和物理修改
DOI：
10.1016/j.gca.2017.04.013
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发表时间：
2017
影响因子：
5
通讯作者：
and N. Ohkouchi
中科院分区：
文献类型：
--
作者：
Isaji Y.;H. Kawahata;J. Kuroda;T. Yoshimura;N. O. Ogawa;A. Suzuki;T. Shibuya;F. J. Jimenez-Espejo;S. Lugli;A. Santulli;V. Manzi;M. Roveri;and N. Ohkouchi
我们调查的变化，在微生物活动的影响下，蒸发海水的化学特性进行的盐水和蒸发岩沉积物的地球化学分析收集太阳盐沼在意大利。微生物活动对碳酸盐体系参数有显著影响。溶解无机碳（DIC）在海水蒸发至碳酸钙沉淀的过程中基本上从盐水中去除，其碳同位素组成（δ 13 CDIC）随之降低至-10.6 ‰。尽管DIC的去除是由于碳酸钙沉淀、光合作用和蒸发引起的CO2（aq）脱气，但在碳酸钙沉淀的池塘中，δ 13 CDIC的存在可能是由于光合作用强烈吸收CO2（aq）导致大气CO2溶解和/或硫酸盐还原导致有机物矿化。相反，在石盐沉淀的盐度范围内，δ 13 CDIC增加到7.2‰，这可以归因于在微生物活动减少的条件下CO2（aq）的脱气作用的支配。微生物活动的逐渐减少也反映在光合色素的化合物特异性δ 13 C中;与DIC同化相关的同位素分馏随着蒸发的进行而线性增加，表明微生物垫和石膏结壳内的DIC限制条件，因为来自上覆盐水的DIC扩散受到限制和/或在较高盐度下初级生产受到抑制。
We investigated changes in the chemical characteristics of evaporating seawater under the influence of microbial activity by conducting geochemical analyses of the brines and evaporite sediments collected from solar salterns in Trapani, Italy. The microbial activity had a substantial effect on the carbonate system parameters. Dissolved inorganic carbon (DIC) was substantially removed from the brine during the course of evaporation from the seawater to the point where calcium carbonate precipitates, with an accompanying decrease in its carbon isotopic composition (δ13CDIC) to as low as −10.6‰. Although the removal of DIC was due to calcium carbonate precipitation, photosynthesis, and the degassing of CO2(aq) induced by evaporation, the presence of13C-depleted δ13CDICin ponds where calcium carbonate precipitates can be attributed to the dissolution of atmospheric CO2because of intensive CO2(aq) uptake by photosynthesis, and/or mineralization of organic matter by sulfate reduction. In contrast, δ13CDICincreased up to 7.2‰ in the salinity range where halite precipitates, which can be ascribed to the domination of the effect of degassing of CO2(aq) under conditions with reduced microbial activity. A gradual decrease in microbial activity was also reflected in compound-specific δ13C of photosynthetic pigments; isotopic fractionation associated with DIC assimilation increased linearly as the evaporation proceeded, indicating DIC-limited conditions within the microbial mats and gypsum crusts because of restricted DIC diffusion from the overlying brine and/or suppression of primary production at higher salinity.