Influence of export rain ratio changes on atmospheric CO2 and sedimentary calcite preservation
Influence of export rain ratio changes on atmospheric CO2 and sedimentary calcite preservation
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出口降雨比变化对大气CO2和沉积方解石保存的影响
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Y. Yamanaka
中科院分区：
文献类型：
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作者：
M. Chikamoto;Katsumi Matsumoto;Y. Yamanaka
利用扩散-平流海洋生物地球化学模型和一维沉积物地球化学模型，研究了大气PCO2和沉积物方解石含量对输出降水碳酸钙/有机碳比值变化的响应。我们的模型显示，降雨率每减少25%，大气中的二氧化碳就会减少59ppm。这是由于减弱的碳酸盐泵导致碱度重新分配，以及通过碳酸盐补偿和方解石埋藏减少而使整个海洋的碱度增加所致。沉积方解石含量和方解石保存效率的稳态响应对1.9 km饱和层的加深不敏感。这种不敏感是因为减少了减少方解石埋藏的沉积通量，抵消了增加方解石埋藏的饱和层加深的影响。但在前100年，方解石沉积减少对埋藏变化的影响更为突出，而在10000年后，饱和层位加深的影响更加突出。前10000年沉积物方解石含量的降低与饱和层1.9公里的下移有效地脱钩。我们的结果在一定程度上是由于在我们的控制运行中，呼吸作用CO2在沉积物方解石溶解过程中起着比底水化学更重要的作用，并支持方解石溶跃层深度和饱和水平移动的解耦，这最初是由Archer和Maier-Remer(1994)和Archer等人提出的。(2000年)。
The responses of atmospheric pCO2 and sediment calcite content to changes in the export rain ratio of calcium carbonate to organic carbon are examined using a diffusion-advection ocean biogeochemical model coupled to a one-dimensional sediment geochemistry model. Our model shows that a 25% reduction in rain ratio decreases atmospheric pCO2 by 59 ppm. This is caused by alkalinity redistribution by a weakened carbonate pump and an alkalinity increase in the whole ocean via carbonate compensation with decreasing calcite burial. The steady state responses of sedimentary calcite content and calcite preservation efficiency are rather insensitive to the deepening of the saturation horizon of 1.9 km. This insensitivity is a result of the reduced deposition flux that decreases calcite burial, counteracting the saturation horizon deepening that increases calcite burial. However, in the first 10,000 years the effect of reduced calcite deposition on the burial change is more prominent; while after 10,000 years, the effect of saturation horizon deepening is more dominant. The lowering of sediment calcite content for the first 10,000 years is effectively decoupled from the 1.9 km downward shift of the saturation horizon. Our results are in part a consequence of the more dominant role that respiration CO2 plays in sediment calcite dissolution over bottom water chemistry in our control run and support the decoupling of calcite lysocline depth and saturation horizon shifts, as suggested originally by Archer and Maier-Reimer (1994) and Archer et al. (2000).