Partitioning the relative contributions of organic matter and mineral sediment to accretion rates in carbonate platform mangrove soils
Partitioning the relative contributions of organic matter and mineral sediment to accretion rates in carbonate platform mangrove soils
复制标题
DOI：
10.1016/j.margeo.2017.07.002
复制
发表时间：
2017-08-01
期刊：
影响因子：
2.9
通讯作者：
Sanders, Christian J.
中科院分区：
文献类型：
--
作者：
Breithaupt, Joshua L.;Smoak, Joseph M.;Sanders, Christian J.
未来几十年，全球海平面上升速度（SLR）预计将超过过去几千年热带、亚热带和温带地区红树林湿地扩张所观察到的速度。栖息在各种地貌环境中的不同红树林生态类型对 SLR 加速的反应存在很大的不确定性，包括它们永久淹没的阈值。本研究在美国佛罗里达州西南部和墨西哥尤卡坦半岛的 23 个红树林地点考察了土壤有机质和无机质（SOM 和 SIM）对 Pb-210 沉积率的相对贡献。这些地点位于碳酸盐台地顶部，SIM（通常是海洋泥灰岩）的可用性存在很大差异。为了解释这种变异性，研究地点根据使用烧失量估算的 SOM 含量 (%) 按 SIM 存在情况进行分类：有机地点 (SOM > 70%)、中间地点 (SOM = 40-70%) 和矿物地点 (SOM < 40%)。在过去的一个世纪中，三个土壤类别中的 SOM 积累率基本相同 (p < 0.05)；然而，中间位点和矿物位点的 SIM 积累率分别比有机位点高约 5 倍和 20 倍。尽管总质量积累率存在显着差异，但土壤类别之间的积累率没有统计差异（p < 0.05）。我们的分析表明，SOM 积累速率是沉积速率的最佳预测因子，而 SIM 积累速率主要预测土壤干容重。这些发现表明，SOM 和 SIM 不会对土壤体积产生附加贡献。这与北美沿海湿地的广泛调查结果相反，表明碳酸盐台地红树林土壤具有缺乏定期、大量陆源 SIM 供应的独特特征。总体而言，佛罗里达州地点和加勒比海尤卡坦半岛地点的吸积率在过去 100 年和 50 年的时间跨度中与 SLR 的区域速率保持同步，而墨西哥塞莱斯顿泻湖（位于墨西哥湾）的地点则表现出增生赤字。到 2060 年，区域 SLR 速率的估计范围为 4.6 至 12.2 mm yr-1。根据上个世纪观察到的吸积率，其中一些站点可能能够与较低的 SLR 估计保持同步，但没有证据表明这些站点中的任何一个可以与更高的速率相匹配。
In coming decades, the global rate of sea-level rise (SLR) is projected to accelerate beyond rates observed over the past several millennia when mangrove wetlands have expanded in tropical, sub-tropical and temperate regions. There is substantial uncertainty about how distinct mangrove ecotypes inhabiting a wide range of geomorphic settings will respond to SLR acceleration, including the thresholds at which they will submerge permanently. In this study, the relative contributions of soil organic and inorganic matter (SOM and SIM) to Pb-210-derived accretion rates were examined at 23 mangrove sites in southwest Florida, USA and the Yucatan Peninsula in Mexico. These sites are situated atop carbonate platforms where there is wide variation in the availability of SIM (generally marine marl). To account for this variability, research sites were classified by SIM presence based on the SOM content (%) estimated using loss-on-ignition: organic sites (SOM > 70%), intermediate sites (SOM = 40-70%) and mineral sites (SOM < 40%).SOM accumulation rates were largely the same in the three soil classes during the past century (p < 0.05); however, SIM accumulation rates in the intermediate and mineral sites were approximately 5 and 20 times greater, respectively, than rates in the organic sites. Despite this substantial difference in total mass accumulation rates, accretion rates were not statistically different between soil classes (p < 0.05). Our analysis revealed that the rate of SOM accumulation is the best predictor of accretion rates, while the rate of SIM accumulation primarily predicts soil dry bulk density. These findings indicate that SOM and SIM do not contribute additively to soil volume. This is contrary to findings from North American coastal wetlands broadly, suggesting a unique characteristic of carbonate platform mangrove soils that lack a regular, substantive supply of terrigenous SIM.Overall, accretion rates in the FL sites and a Yucatan site on the Caribbean Sea are maintaining pace with regional rates of SLR over the past 100-year and 50-year timespans, whereas the sites in Celestun Lagoon, MX (located on the Gulf of Mexico) exhibit an accretion deficit. Estimates of regional SLR rates range from 4.6 to 12.2 mm yr-1 by the year 2060. Based on accretion rates observed in the past century, some of these sites may be able to keep pace with the lower SLR estimate, but there is no evidence that any of these sites can match the higher rate.