Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Poligono Río San Pedro s/n, 11510, Puerto Real, Cádiz, Spain.
Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Poligono Río San Pedro s/n, 11510, Puerto Real, Cádiz, Spain.
Sci Total Environ. 2020 Jul 1;724:138205. doi: 10.1016/j.scitotenv.2020.138205. Epub 2020 Mar 24.
This study examines long-term burial rates of organic carbon (OC), organic nitrogen (ON), and total sulphur (TS) in a tidal-dominated coastal wetland with a high spatial heterogeneity and habitat diversity, and long history of human impacts, Cádiz Bay (SW Spain). Using replicate sediment cores, we quantified fluxes of these elements over a transect, extending from the lower saltmarsh (Spartina maritima, 0.3 m mean sea level, MSL) to the lower intertidal region (Zostera noltei, ~ - 0.7 m MSL). Potential organic matter (OM) sources to the sediment were examined using an extensive dataset on carbon and nitrogen stable isotopes, and C:N molar ratios of primary producers in the region. OC burial rates decreased from the sites below MSL (80 gC·m·y) to the lower saltmarsh (50 gC·m·y), whereas ON burial rates showed an opposite pattern (3 gN·m·y and ~4 gN·m·y observed below and above MSL, respectively). TS burial rates (0.5-46 gS·m·y) did not show any trend along the sea-land gradient. Hence, (tidal) elevation appeared to be an important determinant of sediment biogeochemical properties, and predictor of OM burial rates. The Bayesian mixing model suggested a well-mixed combination of subtidal and terrestrial/high-marsh OM sources to the surface sediments, with no clear indication of an increased contribution from the particular vegetation species inhabiting the sediments. The indication that there is substantial transport, remineralization and cycling of OM between habitats, suggests diversity may play an important role in maintaining this function, reinforcing the idea that a holistic, catchment-scale view is appropriate for understanding and preserving the long-term burial of OM in coastal wetlands.
本研究考察了具有高度空间异质性和生境多样性、且长期受人类活动影响的潮汐主导型滨海湿地中有机碳（OC）、有机氮（ON）和总硫（TS）的长期埋藏速率，该湿地为卡迪斯湾（西班牙西南部）。使用重复的沉积物岩芯，我们在一个从低盐沼（米草，约 0.3 m 平均海平面，MSL）延伸到低潮间带区域（海蓬子，约-0.7 m MSL）的横截面上量化了这些元素的通量。使用该地区碳和氮稳定同位素以及初级生产者的 C:N 摩尔比的广泛数据集，研究了这些元素向沉积物的潜在有机物质（OM）来源。OC 埋藏速率从低于 MSL 的地点（80 gC·m·y）下降到低盐沼（50 gC·m·y），而 ON 埋藏速率则呈现相反的模式（分别在 MSL 以下和以上观察到3 gN·m·y 和4 gN·m·y）。TS 埋藏速率（0.5-46 gS·m·y）没有沿着海陆梯度表现出任何趋势。因此，（潮汐）高程似乎是沉积物生物地球化学性质的重要决定因素，也是 OM 埋藏速率的预测因子。贝叶斯混合模型表明，表层沉积物中存在来自亚潮带和陆地/高沼生境的 OM 的良好混合，没有明显迹象表明栖息在沉积物中的特定植被物种的贡献增加。有迹象表明，OM 在生境之间有大量的运输、再矿化和循环，这表明多样性可能在维持这种功能方面发挥重要作用，强化了整体、集水区尺度的观点对于理解和保护滨海湿地中 OM 的长期埋藏是合适的。
