亚热带农业小流域水体氮素及其稳定同位素分布特征  

Distribution of nitrogen and its stable isotope from a small agricultural catchment in the subtropics

作　　者：赵强 秦晓波[2] 吕成文[1] 李玉娥[2] 吴红宝[1,2] 廖育林[3] 鲁艳红[3] ZHAO Qiang;QIN Xiaobo;LYU Chengwen;LI Yu-e;WU Hongbao;LIAO Yulin;LU Yanhong(College of Territorial Resources and Tourism, Anhui Normal University, Wuhu 241000, China;Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences / Key Laboratory of Agricultural Environment, Ministry of Agriculture, Beijing 100081, China;Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China)

机构地区：[1]安徽师范大学国土资源与旅游学院,芜湖241000 [2]中国农业科学院农业环境与可持续发展研究所/农业部农业环境重点实验室,北京100081 [3]湖南省土壤肥料研究所,长沙410125

出　　处：《中国生态农业学报》2018年第1期136-145,共10页Chinese Journal of Eco-Agriculture

基　　金：国家自然科学基金面上项目(41475129;41775157);国家发改委CDM基金赠款项目(2014081)资助~~

摘　　要：为控制流域氮素养分流失、改善流域水体环境,以亚热带典型农业小流域脱甲河为研究对象,对表层水体铵态氮(NH_4^+-N)、硝态氮(NO_3--N)浓度和水体硝态氮δ^(15)N(δ^(15)N-NO_3-)、沉积物有机质δ^(15)N(δ^(15)N-Org)浓度进行了连续试验观测,分析氮素浓度及其稳定同位素值的时空特征,探讨影响氮素分布的环境因子及水体NO_3-和沉积物有机质氮素的可能来源。结果表明:水体NO_3--N浓度明显高于NH_4^+-N,均值分别为1.62 mg·L^(-1)和0.90mg·L^(-1),并且分别在6月、8月及冬季较高;城镇区和农田区水体NH_4^+-N浓度与其他类型区差异显著(P<0.05),并且显著高于其他水体;NO_3--N浓度在城镇区、农田区及山间林地区较高,水库区较低。支流NH_4^+-N浓度高于干流,均表现为冬季>春季>夏季>秋季;干流、支流NO_3--N浓度分别表现为冬季>夏季>秋季>春季、秋季>冬季>夏季>春季。源头和出口处水体均表现为NO_3--N浓度高于NH_4^+-N,源头处氮素浓度低于出口处。水体δ^(15)N-NO_3-及底泥δ^(15)N-Org值分布范围分别为-19.87‰~8.11‰和-0.69‰~6.51‰,水体δ^(15)N-NO_3-最高值在Ⅲ级河段,最低值出现于Ⅳ级河段,各级河段间水体δ^(15)N-NO_3-11月差异较小,而1、2月差异明显;河流底泥δ^(15)N-Org最高值也位于Ⅲ级河段,而最低值则在Ⅰ级河段,Ⅲ、Ⅳ级河段δ^(15)N-Org值随时间变化趋势较为一致,Ⅰ、Ⅱ级河段δ^(15)N-Org最小值出现于1月。总之,脱甲河水体存在氮素污染现象且以外源输入为主,水体氮素来源主要为土壤有机质、人工合成肥料及陆源有机质,开展流域氮素分布及来源研究对认识流域尺度氮污染物的源解析具有一定科学意义。The Tuojia River basin,a typical agricultural catchment in the subtropics,was investigated in this study to clarify the spatial and temporal distribution characteristics of nitrogen and the related stable isotopes in water system of the catchment.The environmental factors influencing nitrogen distribution and the sources of nitrate nitrogen and sediment organic matter nitrogen were also determined.The concentrations of NH4+-N and NO3--N in surface water were analyzed in a continuous monitoring experiment.At the same time,the characteristics ofδ15N-NO3-in water and ofδ15N-Org in sediments were determined.Results showed that the concentration of NO3--N was significantly higher than that of NH4+-N in the river,with respective mean values of1.62mg.L-1and0.90mg.L-1.Higher values occurred in June,August and winter periods.NH4+-N concentrations in urban and farmland regions were significantly different(P<0.05)from other areas and obviously higher than that in other water bodies.The concentrations of NO3--N in urban,farmland and forest areas were higher than in other regions,with lower values in reservoir areas.The order of seasonal variations in NH4+-N concentration in mainstream and tributary flows was winter>spring>summer>autumn,while that of NO3--N concentration was winter>summer>autumn>spring in mainstream,and autumn>winter>summer>spring in tributary flows.The concentrations of NO3--N of mainstream and tributary flows were high but similar,and NH4+-N concentration in tributary flow was higher than that in mainstream flow.At source and estuary,NO3--N concentration was higher than NH4+-N concentration.Also,nitrogen concentration of at source was lower than that in estuaries.The distributions ofδ15N values(δ15N-NO3-)in the river andδ15N in sediment organic matters(δ15N-Org)were respectively-19.87‰to8.11‰and-0.69‰to6.51‰.While the highest value ofδ15N-NO3-was in the reachⅢ,the lowest was in the reachⅣ.The difference inδ15N-NO3-among different reaches was small in November,but was obvious in January a

关 键 词：脱甲河 亚热带 农业小流域 氮污染 氮同位素 氮素来源 

分 类 号：X522[环境科学与工程—环境工程]