Biogeochemistry of Nitrogen Across the Everglades Landscape
Biogeochemistry of Nitrogen Across the Everglades Landscape
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大沼泽地景观中氮的生物地球化学
DOI：
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发表时间：
2011
期刊：
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通讯作者：
J. Wozniak
中科院分区：
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作者：
P. Inglett;V. Rivera‐Monroy;J. Wozniak
与磷(P)相比，氮(N)在整个大沼泽地景观中几乎没有受到关注。尽管缺乏这种关注，氮在许多大沼泽地系统中扮演着重要的角色，包括作为佛罗里达州海湾和墨西哥湾的重要污染物，高度磷影响地区的限制性营养物质，以及微生物新陈代谢的重要底物。沼泽地中氮的储存和运输主要以有机形式为主，包括泥炭土壤和水体中溶解的有机氮。总体而言，北部地区的氮源最高；然而，在大多数系统中，大气沉积和围生植物组分的活跃的氮源固定是一个重要的氮源。对于大多数大沼泽地系统来说，湿地N循环中涉及的许多过程仍然没有测量到。特别是，缺乏氮气固定和反硝化的就地速率阻碍了系统级预算的建立，特别是对于南方红树林系统，那里的氮素出口到佛罗里达州海湾至关重要。也有可能出现几种新的N过程(如Anammox)，其对大沼泽地生态系统的氮循环和功能的重要性尚未确定。磷负荷通过促进有机氮矿化和由此产生的氨和DON通量来改变氮循环，并在提高磷浓度时通过增加氮素固定和氮素同化速率来改变氮循环。水文学的恢复有可能显著影响大沼泽地的氮素循环，不仅影响氮素的运输，而且通过改变土壤-水界面或季节性下降的地区(如泥炭草原)的有氧-厌氧转变。基于作者对N过程的理解，有必要进行更多的研究，以充分预测水文恢复的潜在影响，以及大沼泽地系统在南佛罗里达州景观中作为N的汇、源和转换的功能。
Compared to phosphorus (P), nitrogen (N) has received little attention across the Everglades landscape. Despite this lack of attention, N plays important roles in many Everglades systems, including being a significant pollutant in Florida Bay and the Gulf of Mexico, the limiting nutrient in highly P-impacted areas, and an important substrate for microbial metabolism. Storage and transport of N throughout the Everglades is dominated by organic forms, including peat soils and dissolved organic N in the water column. In general, N sources are highest in the northern areas; however, atmospheric deposition and active N2 fixation by the periphyton components are a significant N source throughout most systems. Many of the processes involved in the wetland N cycle remain unmeasured for most of the Everglades systems. In particular, the lack of in situ rates for N2 fixation and denitrification prevent the construction of system-level budgets, especially for the Southern mangrove systems where N export into Florida Bay is critical. There is also the potential for several novel N processes (e.g., Anammox) with an as yet undetermined importance for nitrogen cycling and function of the Everglades ecosystem. Phosphorus loading alters the N cycle by stimulating organic N mineralization with resulting flux of ammonium and DON, and at elevated P concentrations, by increasing rates of N2 fixation and N assimilation. Restoration of hydrology has a potential for significantly impacting N cycling in the Everglades both in terms of affecting N transport, but also by altering aerobic-anaerobic transitions at the soil-water interface or in areas with seasonal drawdowns (e.g., marl prairies). Based on the authors’ understanding of N processes, much more research is necessary to adequately predict potential impacts from hydrologic restoration, as well as the function of Everglades systems as sinks, sources, and transformers of N in the South Florida landscape.