不同滨岸带土壤反硝化潜力及影响因子

Soil denitrification potential and its influence factors in different riparian zones

以太湖西部3个中小流域为研究区,于2017年7月15日—20日,采集各流域内3种典型滨岸带表层(0—20 cm)土壤,测定土壤理化性质和反硝化潜力,探讨不同流域滨岸带土壤反硝化潜力的差异和变化规律,并确定土壤反硝化潜力的主要影响因子.研究结果表明,各流域土壤反硝化潜力存在明显差异,天目湖流域、合溪流域和苕溪流域土壤反硝化潜力分别为0.294±0.226 (μg N (N2O)·(g·h)-1)、0.542±0.327 (μg N (N2O)·(g·h)-1)和0.821±0.494 (μg N (N2O)·(g·h)-1),总体表现为城镇化程度越高,土壤反硝化潜力越大.在相同流域内,林地滨岸带土壤反硝化潜力最大,其次为草地滨岸带和荒地滨岸带.相关分析结果表明,土壤反硝化潜力与土壤含水率、硝态氮含量、有机质含量和微生物碳含量都显著正相关(n=54,P<0.01).结合回归分析,表明土壤含水率、硝态氮含量和微生物量碳含量是苕溪流域滨岸带土壤反硝化潜力的主要影响因子;土壤有机质含量和硝态氮含量分别是合溪和天目湖流域滨岸带土壤反硝化潜力的主要影响因子.综上,滨岸带土壤反硝化潜力与人类活动强弱有密切联系,其主要影响因子在不同城镇化背景下的流域间也各不相同.

Three medium and small watersheds located in the western part of Taihu River were selected as the research areas,where 3 typical riparian zone surface(0—20 cm)soils were collected between July 15 to 20,2017 respectively.The soil physicochemical properties and denitrification potentials were mearsured,the differences and variation patterns of soil denitrification potentials in different riparian zones were discussed,and the main factors influencing soil denitrification potentials were determined.The results showed that there were significant differences in soil denitrification potential in each watershed,and the soil denitrification potential was 0.294±0.226(μg N(N2O)·(g·h)-1),0.542±0.327(μg N(N2O)·(g·h)-1)and 0.821±0.494(μg N(N2O)·(g·h)-1)in the Tianmuhu watershed,the Hexi watershed and the Tiaoxi watershed,respectively.Overall,it was shown that the higher the degree of urbanization,the greater the soil denitrification potential.In the same watershed,the soil denitrification potential of woodland was the highest,followed by the grassland and the bareland.The correlation analysis suggested that the soil denitrification potential was positively correlated with physical and chemical properties of soil(n=54,P<0.01),including soil moisture content,nitrate nitrogen concentration,organic matter content and microbial carbon contents.Meanwhile,combined with regression analysis,it was found that soil moisture,nitrate-nitrogen concentration,and microbial biomass carbon concentration were the dominant factors influencing the riparian soil denitrification potential in the Tiaoxi watershed.The soil denitrification potentials of the Hexi watershed and the Tianmuhu watershed were primarily related to soil organic matter and nitrate-nitrogen concentration,respectively.In conclusion,the potential of soil denitrification in the riparian zone was closely related to intensity of human activities,and the main influencing factors were also different among the three watersheds.