太湖竺山湾缓冲带两种人工草林土壤反硝化作用比较  

Comparison of Soil Denitrification in Two Kinds of Planted Forests in the Buffer Zone of Zhushan Bay,Taihu Lake

作　　者：梁菊[1,2] 叶春[1] 李春华[1] 蔡绪贻[2] 

机构地区：[1]中国环境科学研究院,湖泊水污染治理与生态修复技术国家工程实验室,湖泊工程技术中心,北京100012 [2]中国地质大学(北京)水资源与环境学院,北京100083

出　　处：《环境科学研究》2017年第5期744-754,共11页Research of Environmental Sciences

基　　金：国家水体污染控制与治理科技重大专项(2012ZX07101-009)

摘　　要：在太湖竺山湾缓冲带选取两种人工草林(杨树灌木混合林和纯杨树林),对其林床地表径流、林下土壤水和林下地下水进行了为期1 a的观测,比较了土壤反硝化作用.结果表明:(1)两种人工草林林下土壤生化性质、w(有机碳)以及各形态氮质量分数在1 m深度内垂向剖面上的分布大致相同;(2)两种人工草林内地下水中的ρ(NO_3^--N)在1 a之内都没有明显升高趋势,显示反硝化作用在土壤水的入渗过程中有效削减了NO_3^--N,并阻止了其向地下水的迁移;(3)在垂直剖面上,两种人工草林土壤水中ρ(NO_3^--N)在40 cm深度处出现峰值,同深度处的ρ(DO)(低至0.08 mg/L)、E_h(氧化还原电位,0~18 mV)也较低,说明40 cm深度附近可能发生了耦合的硝化-反硝化作用;(4)在垂直剖面上,两种人工草林土壤中反硝化势和反硝化菌数均在40 cm深度附近出现峰值,虽然杨树灌木混合林土壤反硝化势[2.1 mg/(kg·h)]是纯杨树林[1.1 mg/(kg·h)]的2倍,但两种人工草林土壤中实际的反硝化速率受ρ(NO_3^--N)的限制,没有明显的差别.研究显示,两种人工草林土壤都在40 cm深度附近存在反硝化活跃带.Two planted forests with different compositions-the polar and shrub forest（PSF） and the polar forest（PF）-in Zhushan Bay in the buffering zone of the Taihu Lake were selected as the vegetation buffer strips for comparison of their soil denitrification ability.The contents of various forms of N species in their floor surface runoff,the soil water and groundwater below their floor were monitored for one year,and the soil denitrification potentials at different depths were also measured.The results showed that：（1） the soil physical chemistry and biological properties,the organic matter content,and the content of various species of nitrogen varied with depth less than one meter in the same pattern.（2） No significant increase trends were observed for nitrate（NO3---N） contents for the groundwater under both forests for one year.This indicated that the denitrification in their soils efficiently reduced the nitrate in their soil water,and prevented the nitrate from being transported into the groundwater.（3） The maximum value for the measured denitrification potentials were found around the depth of 40 cm in the vertical soil profiles for both planted forests,coinciding with lower values for DO concentration and Eh at the same depth,proving the existence of a coupled nitrification-denitrification layer.（4） In the vertical soil profiles for both planted forests,all the maximum values for the soil denitrification potentials and the numbers of denitrification bacteria in these two forests occurred around the depth of 40 cm,demonstrating the existence of an active denitrification layer around the depth of 40 cm,which was closely related to the root system of grass vegetation.（5） At the same depth,the soil denitrification potentials for PSF（2.1mg/（kg·h）） were twice those for PF（1.1 mg/（kg ·h））;however,there was no significant difference for the actual overall denitrification rates for the soils in both forests,which were limited by the concentration of nitrate in soil water.

关 键 词：植被缓冲带 人工草林 地下水 反硝化 

分 类 号：X171[环境科学与工程—环境科学]