High salinity leads to accumulation of soil organic carbon in mangrove soil.
High salinity leads to accumulation of soil organic carbon in mangrove soil.
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DOI：
10.1016/j.chemosphere.2017.02.074
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发表时间：
2017-06
期刊：
影响因子：
8.8
通讯作者：
Morimaru Kida;M. Tomotsune;Yasuo Iimura;K. Kinjo;T. Ohtsuka;N. Fujitake
中科院分区：
文献类型：
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作者：
Morimaru Kida;M. Tomotsune;Yasuo Iimura;K. Kinjo;T. Ohtsuka;N. Fujitake
虽然红树林是最著名的土壤有机碳汇之一，但其积累机制尚不清楚。高净初级生产量（NPP）、典型的重底生物量分配和低土壤呼吸（SR）被认为是土壤有机碳积累的主要原因。然而，一种新兴的范式假设，由于地下水中溶解无机碳（DIC）的泄漏，SR被严重低估。本文提出了一种简单而独特的红树林土壤有机碳积累机制。分别利用超纯水和人工海水对红树林土壤进行了水可萃取性有机物（WEOM）的连续提取。只有在超纯水的情况下，腐殖质（HS）浓度才会急剧增加，同时盐度也会下降。提取的WEOM为胶体，加入人工海水后其再沉淀率≤70%。这些结果强烈表明，由于高盐度，HS在红树林土壤中有选择性地絮凝和维持。由于海盐是任何红树林的特征，高盐度可能是红树林土壤有机碳积累的机制之一。
Although mangrove forests are one of the most well-known soil organic carbon (SOC) sinks, the mechanism underlying SOC accumulation is relatively unknown. High net primary production (NPP) along with the typical bottom-heavy biomass allocation and low soil respiration (SR) have been considered to be responsible for SOC accumulation. However, an emerging paradigm postulates that SR is severely underestimated because of the leakage of dissolved inorganic carbon (DIC) in groundwater. Here we propose a simple yet unique mechanism for SOC accumulation in mangrove soils. We conducted sequential extraction of water extractable organic matter (WEOM) from mangrove soils using ultrapure water and artificial seawater, respectively. A sharp increase in humic substances (HS) concentration was observed only in the case of ultrapure water, along with a decline in salinity. Extracted WEOM was colloidal, and ≤70% of it re-precipitated by the addition of artificial seawater. These results strongly suggest that HS is selectively flocculated and maintained in the mangrove soils because of high salinity. Because sea salts are a characteristic of any mangrove forest, high salinity may be one of mechanisms underlying SOC accumulation in mangrove soils.