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研究论文

Nitrogen mineralization and denitrification in bamboo riparian systems in Southeastern China

基金项目：国家自然科学基金项目(No.40671116, 41175130);福建省自然科学基金重点项目(No.D0720002);教育部新世纪优秀人才支持计划;福建省高校新世纪优秀人才支持计划

摘要：采用原位培养法和乙炔抑制-静态土柱培养法,对南方丘陵地区竹林河岸系统的矿化、反硝化作用进行了研究.结果表明,研究区土壤氮矿化速率为-0.28~0.30 mg·kg^-1·d^-1(以N计,下同),且与土壤含水量存在显著正相关(p<0.05).在系统中,与入口区与中部区的土壤氮矿化作用平均强度相比,毗邻河道的河岸区更为强烈.土壤氨化速率为-0.43~0.35 mg·kg^-1·d^-1,硝化速率为-0.32~0.61 mg·kg^-1·d^-1.其中,硝化作用产生的硝态氮占原地土壤硝态氮的24%~80%,平均为56%.反硝化作用强度为0.03~3.88 mg·m^-2·d^-1,降雨期间土壤的反硝化水平显著高于无降雨期间,平均强度表现为:河岸出口>河岸入口>河岸中部,并呈现出较大的时空差异.硝化和反硝化过程存在较强的耦合作用.较河岸区入口处和中部区而言,毗邻河道的河岸区的生物地球化学过程更为活跃.

Abstract：In situ nitrogen mineralization and denitrification rates in top soils are measured using soil core incubation methods and acetylene inhibition technique within a bamboo riparian system in Southeastern China. The results show that the net nitrogen mineralization rate ranges from -0.28 to 0.30 mg·kg^-1·d^-1, and has an obvious positive correlation with soil moisture (p<0.05). The peak nitrogen mineralization rate occurs in the zones adjacent to the river. The soil ammonification and nitrification rates vary from -0.43 to 0.35 mg·kg^-1·d^-1 and from -0.32 to 0.61 mg·kg^-1·d^-1, respectively. Continuous incubations indicate that nitrification in surface soils could contribute as much as 24% to 80% of nitrate nitrogen content, accounting for 56% (in average) of the final nitrate nitrogen content of the soil. Denitrification rate ranges from 0.03 to 3.88 mg·m^-2·d^-1, with high spatial and temporal variation. In addition, the peak denitrification rate happens in riverfront zones. As a result, stronger biogeochemistry processes are observed in the riparian zone adjacent to the river than those in the middle or cultivated field front, and nitrification and denitrification processes within the zone are closely coupled.

Key words：bamboo riparian systems net mineralization ammonification nitrification denitrification