Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change
Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change
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DOI：
10.5194/bg-10-371-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Regnier, P.
中科院分区：
文献类型：
--
作者：
Krumins, V.;Gehlen, M.;Regnier, P.
本文提出了一个一维反应输运模型来估算近岸海洋沉积物中溶解无机碳（DIC）和碱度（AT）的底栖通量。该模型结合了沉积物积累，分子扩散，生物扰动和生物灌溉的运输过程，而包括的反应是有机碳氧化的氧化还原途径，还原氮，铁和硫化合物的再氧化，孔隙水酸碱平衡，和溶解的颗粒无机碳（方解石，文石，镁方解石）。将海岸带划分为4个具有不同颗粒无机碳（PIC）和颗粒有机碳（POC）通量的环境单元：珊瑚礁、海岸和海湾、碳酸盐陆架和非碳酸盐陆架。模型结果分别分析了每个环境，然后按比例扩大到整个沿海海洋。基于全球沿海活性POC沉积通量为117 Tmol yr（-1），模型得出的当今全球沿海底栖DIC流出量估计值为126 Tmol yr（-1）。POC分解导致了7 Tmol yr（-1）（约0.1 Pg C yr（-1））的碳酸盐溶解。假设从沉积物中释放的含水硫化物完全再氧化，到水柱的有效净碱度通量为29 Teq。年（-1），主要来自PIC溶解（46%）和氨化作用（33%）。由于我们的POC沉积通量福尔斯在文献中给出的全球值的高范围内，报告的DIC和碱度通量应被视为上限估计。增加沿海海水DIC到2100年可能是预期的，由于人为CO2的吸收增加PIC溶解2.3 Tmol yr（-1）和碱度流出4.8 Teq。年（-1）。我们的反应传输建模方法不仅产生全球估计的底栖DIC，碱度和营养盐通量的海洋生产力和化学的可变情景下，但也提供了深入了解的基本过程。
We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr(-1), based on a global coastal reactive POC depositional flux of 117 Tmol yr(-1). The POC decomposition leads to a carbonate dissolution from shallow marine sediments of 7 Tmol yr(-1) (on the order of 0.1 Pg C yr(-1)). Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq. yr(-1), primarily from PIC dissolution (46 %) and ammonification (33 %). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO2 increases PIC dissolution by 2.3 Tmol yr(-1) and alkalinity efflux by 4.8 Teq. yr(-1). Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the underlying processes.