Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China.
Sci Total Environ. 2020 Aug 25;732:138327. doi: 10.1016/j.scitotenv.2020.138327. Epub 2020 Apr 30.
Glomalin-related soil protein (GRSP) derived from arbuscular mycorrhizal fungi can be transported from land to sea and captured in mangrove wetlands, thereby contributing to soil C and N pools. However, the stable isotope signatures of GRSP and the key influencing factors that affect its isotope values in coastal wetlands remain unknown. In this study, the results showed that total-GRSP (T-GRSP) was a significant contributor of C and N content to mangrove soil. We first compared stable isotope (δC and δN) values and C/N ratios of GRSP with those of other blue carbon sources in a typical mangrove wetland. The isotope fingerprints of T-GRSP, mangrove soils, mangrove plants, and tidal waters were identified. Unlike those of the conventional sources, the δC and δN values of T-GRSP were -25.04‰ to -22.83‰ and 3.22‰ to 7.24‰, respectively, and the mean C/N ratio was 12.95 in the mangrove cover sites. These findings indicated that T-GRSP is a novel blue carbon source mainly originating from terrestrial ecosystems. Moreover, the δC and δN values of T-GRSP in mangrove wetlands were affected by vegetation interception and soil properties. Redundancy analysis results indicated that pH, moisture, depth, and salinity were key factors influencing the T-GRSP isotope fingerprints in mangrove wetlands. Additionally, the simultaneous changes in T-GRSP content, isotope values, and C/N ratios among mangrove cover sites, a mudflat, and tidal waters suggested that this protein is a sensitive tracer between land and sea. Overall, the isotope signatures of GRSP captured by mangroves were identified for the first time, which will have important implications for the estimation of the blue carbon budget and identification of the blue carbon sources in global coastal regions.
胶磷蛋白相关土壤蛋白（GRSP）来源于丛枝菌根真菌，可以从陆地运输到海洋，并在红树林湿地中被捕获，从而为土壤的碳和氮库做出贡献。然而，GRSP 的稳定同位素特征以及影响其同位素值的关键因素在沿海湿地中仍然未知。在这项研究中，结果表明总-GRSP（T-GRSP）是红树林土壤中碳和氮含量的重要贡献者。我们首先比较了典型红树林湿地中 GRSP 与其他蓝碳源的稳定同位素（δC 和 δN）值和 C/N 比值。鉴定了 T-GRSP、红树林土壤、红树林植物和潮汐水的同位素指纹。与常规来源不同，T-GRSP 的 δC 和 δN 值分别为-25.04‰至-22.83‰和 3.22‰至 7.24‰，而在红树林覆盖区的平均 C/N 比为 12.95。这些发现表明，T-GRSP 是一种主要源自陆地生态系统的新型蓝碳源。此外，红树林湿地中 T-GRSP 的 δC 和 δN 值受到植被截留和土壤性质的影响。冗余分析结果表明，pH 值、水分、深度和盐度是影响红树林湿地 T-GRSP 同位素指纹的关键因素。此外，红树林覆盖区、泥滩和潮汐水之间 T-GRSP 含量、同位素值和 C/N 比值的同时变化表明，这种蛋白质是陆地和海洋之间的敏感示踪剂。总的来说，首次确定了红树林捕获的 GRSP 的同位素特征，这对于估计全球沿海地区的蓝碳预算和确定蓝碳源具有重要意义。
