Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications
Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications
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DOI：
10.1002/2017jg004036
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发表时间：
2017-10-01
影响因子：
3.7
通讯作者：
Gao, Juan
中科院分区：
文献类型：
--
作者：
Lin, Xianbiao;Liu, Min;Gao, Juan
过去几十年来，沿海海洋生态系统中的全球活性氮（N）急剧增加，并造成了许多生态环境问题。沿海海洋沉积物在反硝化和厌氧氨氧化（厌氧氨氧化）以及一氧化二氮（N2O）释放造成的氮损失中发挥着关键作用。然而，沉积物中反硝化、厌氧氨氧化和 N2O 产生的程度和贡献仍不清楚，导致沿海海洋生态系统氮预算的确定存在不确定性。本文对东海 429 个地点的 6 次航行期间的表层沉积物中氮损失的潜在速率及其贡献和控制因素进行了调查。反硝化、厌氧氨氧化和 N2O 生产的潜在速率随空间和季节变化，但厌氧氨氧化对总 N-2 生产的贡献 (%anammox) 和 N2O:N-2 比率仅在空间上变化。有机碳和硝酸盐 (NO3-) 都是控制氮损失、N2O:N-2 比和厌氧氨氧化百分比的重要因素。我们的研究结果还表明，富营养化引起的海洋有机碳在刺激活性氮去除和增加暖季 N2O 产量方面发挥着重要作用。研究区反硝化、厌氧氨氧化和N2O产生造成的沉积物氮损失分别为2.2x10(6)tNyr(-1)、4.6x10(5)tNyr(-1)和8x10(3)tNyr(-1)。尽管沉积物去除了大量的活性氮，但在该地区受富含NO3的河流影响，它们是N2O的重要来源。
Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. Here potential rates of N losses, and their contributions and controlling factors, were investigated in surface sediments during six cruises from 429 sites of the East China Sea. The potential rates of denitrification, anammox, and N2O production varied both spatially and seasonally, but the contribution of anammmox to total N-2 production (%anammox) and N2O:N-2 ratio only varied spatially. Both organic carbon and nitrate (NO3-) were important factors controlling N losses, N2O:N-2 ratio, and %anammox. Our results also showed that marine organic carbon induced by eutrophication plays an important role in stimulating reactive N removal and increasing N2O production in warm seasons. The sediment N loss caused by denitrification, anammox, and N2O production in the study area were estimated at 2.2x10(6)tNyr(-1), 4.6x10(5)tNyr(-1), and 8x10(3)tNyr(-1), respectively. Although sediments remove large quantities of reactive N, they act as an important source of N2O in this region influenced by NO3--laden rivers.