Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, People's Republic of China.
Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, People's Republic of China
Biol Lett. 2018 Nov 14;14(11):20180483. doi: 10.1098/rsbl.2018.0483.
Soil inorganic carbon (IC) is neglected in most blue carbon studies despite the globally significant role of the calcium carbonate cycle in ocean C balance and climate change. We sampled soils to 1 m depth from seven mangrove reserves in Hainan Island, China. Only 45 out of 509 samples were rich in IC (greater than 10 mg cm). Most of the IC-rich samples were found at the outer part of Qinglan Bay, which is adjacent to the largest coral reef zone of Hainan Island. Soil IC concentration ranged from 0 to 66 g kg (or 0-67 mg cm), accounting for 0-92% of total C. IC concentration increased with soil depth where it was abundant. Soil pH was low (2.36-6.59) in IC-depleted soils, but increased to 5.67-7.99 in IC-rich soils. Soil total C stock and IC stock in mangroves of Hainan amounted to 0.76×10 and 0.12×10 Mg, respectively, with IC accounting for 16% of total C. Our study finds that carbonate concentrations can be high in mangrove soils but their spatial distribution indicates they are largely allochthonous in origin. Evidence of carbonate dissolution in mangroves suggests mangroves may increase total alkalinity to buffer acidification in seawater.
土壤无机碳（IC）在大多数蓝碳研究中被忽视，尽管碳酸钙循环在海洋碳平衡和气候变化中具有全球重要作用。我们从中国海南岛的七个红树林保护区采集了 1 米深的土壤样本。在 509 个样本中，只有 45 个富含 IC（大于 10mg/cm）。大多数富含 IC 的样本都位于青澜湾的外部，该湾毗邻海南岛最大的珊瑚礁区。土壤 IC 浓度范围从 0 到 66g/kg（或 0-67mg/cm），占总 C 的 0-92%。IC 浓度随土壤深度的增加而增加，在富含 IC 的土壤中更为丰富。在 IC 贫化土壤中，土壤 pH 值较低（2.36-6.59），但在富含 IC 的土壤中增加到 5.67-7.99。海南岛红树林的土壤总 C 储量和 IC 储量分别达到 0.76×10 和 0.12×10 Mg，IC 占总 C 的 16%。我们的研究发现，红树林土壤中的碳酸盐浓度可能很高，但它们的空间分布表明它们主要来自异地。红树林中碳酸盐溶解的证据表明，红树林可能会增加总碱度，以缓冲海水酸化。
