Does edge erosion alter coastal wetland soil properties? A multi-method biogeochemical study
Does edge erosion alter coastal wetland soil properties? A multi-method biogeochemical study
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DOI：
10.1016/j.catena.2019.104373
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发表时间：
2020-04
期刊：
影响因子：
6.2
通讯作者：
H. Steinmuller;M. P. Hayes;N. Hurst;Y. Sapkota;R. Cook;J. White;Z. Xue;Lisa G. Chambers
中科院分区：
文献类型：
--
作者：
H. Steinmuller;M. P. Hayes;N. Hurst;Y. Sapkota;R. Cook;J. White;Z. Xue;Lisa G. Chambers
路易斯安那州的沿海湿地由于海平面上升和海岸沉降的共同作用，边缘侵蚀率很高。本研究旨在（1）评估巴拉塔里亚湾沼泽边缘侵蚀速率的特定地点的空间和时间模式，（2）通过土壤地球化学和光谱表征，了解侵蚀土壤的物理和化学性质，（3）评估侵蚀，盐水入侵，通过比较不同侵蚀速率和离侵蚀边缘不同距离的地点，在三个不同的地点（西部，南部和北部），在三个距离内陆（1米，3米，5米），以1米的深度，重复土芯收集。侵蚀速率进行了测量，在每个网站，土壤被分成10厘米的间隔，共270个土壤和孔隙水样本。每个土壤样品进行土壤物理化学分析（容重，水分含量，有机质含量，总碳（C），氮（N），磷（P）），以及生态地球化学循环（CO2的生产，矿化的N和P，和可提取的养分浓度）的评估。孔隙水样品进行了分析，以阐明碳质量（芳香性，腐殖化作用，木质素比例和C源）的光谱和荧光指标。西部、北部和南部的侵蚀速率分别为3.36 ± 0.4、1.34 ± 0.2和0.58 ± 0.03 m yr−1。无论是侵蚀的幅度，也没有盐水入侵被发现是任何测量的光谱或地球化学参数的显着预测，虽然深度是一个显着的控制18所测量的20个参数。顶部30厘米的生物活性更强（如C，N和P的矿化程度更高所示），其特征在于低分子量的孔隙水DOM，芳香性较低。孔隙水DOM的腐殖化度和芳香度随深度和距离的增加而增加。在1米深的生物可利用的N和P的浓度至少5倍以上的表面浓度，代表一个池的营养物质，可以出口到沿海海洋与持续的侵蚀。这项研究是第一个耦合光谱和土壤地球化学测量的目的，评估土壤和孔隙水的物理化学湿地土壤，并说明了一个尚未考虑到潜在的出口不稳定的C，N和P到沿海海洋。
Coastal wetlands in Louisiana experience high rates of edge erosion due to combined eustatic sea level rise and coastal subsidence. This study sought to (1) evaluate site-specific spatial and temporal patterns in marsh edge erosion rates within Barataria Bay, LA, (2) develop an understanding of the physical and chemical properties of eroding soils through biogeochemical and spectroscopic characterization, and (3) evaluate interactions between erosion, saltwater incursion, and soil properties through a comparison of sites with different erosion rates and varying distances from the eroding edge. Replicate soil cores were collected at three distances inland (1 m, 3 m, 5 m) at three different sites (west, south, and north) to a depth of 1 m. Erosion rates were measured at each site, and soils were sectioned into 10 cm intervals for a total of 270 soil and porewater samples. Each soil sample was subjected to soil physicochemical analysis (bulk density, moisture content, organic matter content, and total carbon (C), nitrogen (N), and phosphorus (P)) as well as assessments of biogeochemical cycling (production of CO2, mineralization of N and P, and extractable nutrient concentrations). Porewater samples were analyzed to elucidate spectroscopic and fluorometric indicators of carbon quality (aromaticity, humification, lignin proportion, and C source). Erosion rates at the west, north, and south sites were 3.36 ± 0.4, 1.34 ± 0.2, and 0.58 ± 0.03 m yr−1, respectively. Neither erosional magnitude nor saltwater incursion was found to be significant predictors of any measured spectroscopic or biogeochemical parameters, though depth was a significant control on 18 of the measured 20 parameters. The top 30 cm were more biologically active (as indicated by greater mineralization of C, N and P) and were characterized by lower molecular weight porewater DOM with less aromaticity. Degree of humification and aromaticity of porewater DOM increased with both depth and distance inland. Concentrations of bioavailable N and P at 1 m depth were at least 5 times greater than surface concentrations, representing a pool of nutrients that could be exported into the coastal ocean with ongoing erosion. This study is the first to couple spectroscopic and biogeochemical measurements for the purpose of assessing soil and porewater physicochemistry within wetland soils and illustrates an as-yet unaccounted for potential for the export of labile C, N, and P into the coastal ocean.