Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China.
Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China.
Mar Pollut Bull. 2020 Nov;160:111696. doi: 10.1016/j.marpolbul.2020.111696. Epub 2020 Sep 24.
Quality and source of soil organic carbon controlling DNRA in estuarine wetlands have not been well understood. We used a N isotopic tracer approach to investigate DNRA rates and determined the effects of organic carbon quality and source on magnitudes and distribution of DNRA along a freshwater-oligohaline gradient of Min River estuary, Southeast China. DNRA rates ranged from 0.45 to 2.92 nmol g h and were significantly higher in summer than in winter. DNRA was well predicted by dissolved organic carbon (DOC), organic carbon isotope (δC), total OC as the main predictor variables, which explained 63%, 6.0% and 7.0% of DNRA variances, respectively. Water content and temperature were crucial for DOC availability with important implications on DNRA. Soil δC increased from freshwater to oligohaline wetlands and showed a positive correlation with DNRA. We therefore conclude that high DOC availability enhances DNRA and can best predict spatial distribution in subtropical estuary.
土壤有机碳的质量和来源对河口湿地的反硝化氮还原作用（DNRA）的影响尚未得到很好的理解。本研究采用氮同位素示踪法，调查了中国东南地区闽江河口淡水-寡盐水体梯度上的 DNRA 速率，并确定了有机碳质量和来源对 DNRA 幅度和分布的影响。DNRA 速率范围为 0.45 至 2.92 nmol g h，夏季明显高于冬季。DNRA 与溶解有机碳（DOC）、有机碳同位素（δC）和总有机碳（TOC）呈显著正相关，可分别解释 63%、6.0%和 7.0%的 DNRA 方差，是主要的预测变量。含水量和温度对 DOC 的有效性至关重要，对 DNRA 有重要影响。土壤 δC 值从淡水向寡盐水湿地增加，并与 DNRA 呈正相关。因此，本研究认为高 DOC 可用性增强了 DNRA，并且可以很好地预测亚热带河口的空间分布。
