Flite O P, Shannon R D, Schnabel R R, Parizek R R
Environmental Pollution Control Program, The Pennsylvania State University, University Park 16802, USA.
J Environ Qual. 2001 Jan-Feb;30(1):254-61. doi: 10.2134/jeq2001.301254x.
Riparian zones within the Appalachian Valley and Ridge physiographic province are often characterized by localized variability in soil moisture and organic carbon content, as well as variability in the distribution of soils formed from alluvial and colluvial processes. These sources of variability may significantly influence denitrification rates. This investigation studied the attenuation of nitrate (NO3- -N) as wastewater effluent flowed through the shallow ground water of a forested headwater riparian zone within the Appalachian Valley and Ridge physiographic province. Ground water flow and NO3- -N measurements indicated that NO3- -N discharged to the riparian zone preferentially flowed through the A and B horizons of depressional wetlands located in relic meander scars, with NO3- -N decreasing from > 12 to < 0.5 mg L(-1). Denitrification enzyme activity (DEA) attributable to riparian zone location, soil horizon, and NO3- -N amendments was also determined. Mean DEA in saturated soils attained values as high as 210 microg N kg(-1) h(-1), and was significantly higher than in unsaturated soils, regardless of horizon (p < 0.001). Denitrification enzyme activity in the shallow A horizon of wetland soils was significantly higher (p < 0.001) than in deeper soils. Significant stimulation of DEA (p = 0.027) by N03- -N amendments occurred only in the meander scar soils receiving low NO3- -N (<3.6 mg L(-1)) concentrations. Significant denitrification of high NO3- -N ground water can occur in riparian wetland soils, but DEA is dependent upon localized differences in the degree of soil saturation and organic carbon content.
阿巴拉契亚山谷和山脊地貌省内的河岸带通常具有土壤湿度和有机碳含量的局部变异性，以及由冲积和崩积过程形成的土壤分布变异性。这些变异性来源可能会显著影响反硝化速率。本研究调查了废水流出物流经阿巴拉契亚山谷和山脊地貌省内森林源头河岸带浅层地下水时硝酸盐（NO3--N）的衰减情况。地下水流和NO3--N测量表明，排放到河岸带的NO3--N优先流经位于残留河曲疤痕中的洼地湿地的A层和B层，NO3--N浓度从>12 mg L(-1)降至<0.5 mg L(-1)。还测定了河岸带位置、土壤层位和NO3--N添加量对反硝化酶活性（DEA）的影响。饱和土壤中的平均DEA高达210 μg N kg(-1) h(-1)，且无论土壤层位如何，均显著高于不饱和土壤（p<0.001）。湿地土壤浅层A层的反硝化酶活性显著高于深层土壤（p<0.001）。仅在接受低NO3--N（<3.6 mg L(-1)）浓度的河曲疤痕土壤中，NO3--N添加对DEA有显著刺激作用（p = 0.027）。河岸湿地土壤中高NO3--N地下水可发生显著反硝化作用，但DEA取决于土壤饱和度和有机碳含量的局部差异。
