Eutrophication reduced the release of dissolved organic carbon from tropical seagrass roots through exudation and decomposition
Eutrophication reduced the release of dissolved organic carbon from tropical seagrass roots through exudation and decomposition
复制标题
富营养化减少了热带海草根部通过渗出和分解释放的溶解有机碳
DOI：
10.1016/j.marenvres.2022.105703
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发表时间：
2022-07-16
影响因子：
3.3
通讯作者：
Huang, Xiaoping
中科院分区：
文献类型：
--
作者：
Jiang, Zhijian;Li, Linglan;Huang, Xiaoping
海草床生态系统是地球上最有效的碳捕获和储存系统之一。海草根是叶根沉积物碳流动的关键环节，海草根通过渗出和分解释放的溶解有机碳（DOC）是海草床沉积物有机碳（SOC）的重要来源。不幸的是，人为引起的富营养化可能改变海草根部DOC的释放过程，从而影响沉积物的碳储存能力。然而，营养物富集对海草根部DOC释放的影响尚不清楚，阻碍了海草地下生态的发展。因此，我们选择热带优势海草种海草（Thalassia hemprichii）作为研究对象，比较不同硝酸盐处理下根系通过渗出和分解释放DOC的情况。我们发现控制10μl - 1摩尔20μ摩尔l - 1和40μ摩尔硝酸l - 1治疗,可溶性糖t . hemprichii根是71.37 + / - 3.43毫克g(1), 67.03 + / - 5.33毫克g(1), 49.14 + / - 3.48毫克g(1)和18.51 + / - 2.09毫克g(1),分别在相应的根DOC泌水率分别为7.00 + / - 0.97毫克g DW根(1)h(1), 5.11 + / - 0.42毫克g DW根(1)h(1), 4.08 + / - 0.23毫克g DW根(1)h(1)和3.78 + / - 0.74毫克g DW根(1)h(1),分别。根可溶性糖与DOC渗出率呈显著正相关。硝酸盐富集后，沉积物孔隙水DOC浓度和有机碳含量也显著降低（但不显著），两者均与DOC不渗出率呈显著正相关。同时，硝酸盐的富集也降低了海草根分解初期DOC的释放速率，降低了分解过程中DOC的释放通量。因此，营养物的富集可以减少海草根部的非结构性碳水化合物，降低mot渗出DOC的速率，从而降低SOC，降低海草mot分解释放DOC。为了增加海草床DOC的释放，提高海草床的固碳能力，应采取有效措施控制海岸营养物输入海草床。
Seagrass bed ecosystem is one of the most effective carbon capture and storage systems on earth. Seagrass roots are the key link of carbon flow between leaf-root-sediment, and the release of dissolved organic carbon (DOC) from seagrass roots through exudation and decomposition are vital sources to the sediment organic carbon (SOC) in the seagrass beds. Unfortunately, human-induced eutrophication may change the release process of DOC from seagrass roots, thereby affecting the sediment carbon storage capacity. However, little is known about the effect of nutrient enrichment on the release of DOC from seagrass roots, hindering the development of seagrass underground ecology. Therefore, we selected Thalassia hemprichii, the tropical dominant seagrass species, as the research object, and made a comparison of the release of DOC from roots through exudation and decomposition under different nitrate treatments. We found that under control, 10 mu mol L-1, 20 mu mol L-1 and 40 mu mol L-1 nitrate treatments, soluble sugar of T. hemprichii roots were 71.37 +/- 3.43 mg g(-1), 67.03 +/- 5.33 mg g(-1), 49.14 +/- 3.48 mg g(-1), and 18.51 +/- 2.09 mg g(-1), respectively, while the corresponding root DOC exudation rates were 7.00 +/- 0.97 mg g DW root(-1) h(-1), 5.11 +/- 0.42 mg g DW root(-1) h(-1), 4.08 +/- 0.23 mg g DW root(-1) h(-1), and 3.78 +/- 0.74 mg g DW root(-1) h(-1), respectively. There was a significant positive correlation between root soluble sugar and DOC exudation rate. DOC concentration of sediment porewater and SOC content also decreased under nitrate enrichment (though not significantly), which were both significantly positively correlated with the rate of mot exuded DOC. Meanwhile, nitrate enrichment also reduced the release rate of DOC from seagrass roots during initial decomposition, and the release flux of DOC from decomposition. Therefore, nutrient enrichment could decrease nonstructural carbohydrates of seagrass roots, reducing the rate of mot exuded DOC, thereby lowered SOC, as well as the DOC release from seagrass mot decomposition. In order to increase the release of DOC from seagrass mots and improve the carbon sequestration capacity of seagrass beds, effective measures should be taken to control the coastal nutrients input into seagrass beds.