Hunt Patrick G, Matheny Terry A, Szögi Ariel A
USDA-ARS, Coastal Plain Soil, Water, and Plant Research Center, Florence, SC 29501, USA.
J Environ Qual. 2003 Mar-Apr;32(2):727-35.
Constructed wetland treatment of swine wastewater probably involves substantial denitrification. Our objective was to assess denitrification and denitrification enzyme activity (DEA) in such wetlands in relation to plant communities, N loading, carbon or nitrogen limitations, and water depth. Two wetland cells each 3.6 m wide and 33.5 m long were connected in series. One set of cells was planted with rushes and bulrushes, including soft rush (Juncus effusus L.), softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal, American bulrush [Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller], and woolgrass bulrush [Scirpus cyperinus (L.) Kunth]. Another set was planted with bur-reeds and cattails, including American bur-reed (Sparganium americanum Nutt.), broadleaf cattail (Typha latifolia L.), and narrowleaf cattail (Typha angustifolia L.). The sets will be referred to herein as bulrush and cattail wetlands, respectively. Denitrification and DEA were measured via the acetylene inhibition method in intact soil cores and disturbed soil samples that were taken during four years (1994-1997). Although DEA in the disturbed samples was greater than denitrification in the core samples, the measurements were highly correlated (r2 > or = 0.82). The DEA was greater in the bulrush wetlands than the cattail wetlands, 0.516 and 0.210 mg N kg(-1) soil h(-1), respectively; and it increased with the cumulative applied N. The DEA mean was equivalent to 9.55 kg N ha(-1) d(-1) in the bulrush wetlands. We hypothesized and confirmed that DEA was generally limited by nitrate rather than carbon. Moreover, we determined that one of the most influential factors in DEA was wetland water depth. In bulrush wetlands, the slope and r2 values of the control treatment were -0.013 mg N kg(-1) soil h(-1) mm(-1) depth and r2 = 0.89, respectively. Results of this investigation indicate that DEA can be very significant in constructed wetlands used to treat swine wastewater.
人工湿地处理猪废水可能涉及大量反硝化作用。我们的目标是评估此类湿地中反硝化作用及反硝化酶活性（DEA）与植物群落、氮负荷、碳或氮限制以及水深的关系。两个湿地单元，每个宽3.6米、长33.5米，串联连接。一组湿地单元种植了灯心草和芦苇，包括软质灯心草（Juncus effusus L.）、软茎芦苇[Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal]、美洲芦苇[Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller]和毛草芦苇[Scirpus cyperinus (L.) Kunth]。另一组种植了水烛和香蒲，包括美洲水烛（Sparganium americanum Nutt.）、阔叶香蒲（Typha latifolia L.）和窄叶香蒲（Typha angustifolia L.）。在此将这两组分别称为芦苇湿地和香蒲湿地。在1994年至1997年的四年间，通过乙炔抑制法在完整土壤芯样和扰动土壤样品中测量了反硝化作用和DEA。尽管扰动样品中的DEA大于芯样中的反硝化作用，但测量结果高度相关（r2≥0.82）。芦苇湿地中的DEA大于香蒲湿地，分别为0.516和0.210毫克氮每千克土壤每小时；并且它随累积施氮量增加。芦苇湿地中DEA的平均值相当于9.55千克氮每公顷每天。我们假设并证实DEA通常受硝酸盐而非碳的限制。此外，我们确定DEA中最有影响的因素之一是湿地水深。在芦苇湿地中，对照处理的斜率和r2值分别为-0.013毫克氮每千克土壤每小时每毫米深度和r2 = 0.89。本研究结果表明，DEA在用于处理猪废水的人工湿地中可能非常显著。
