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Alternative TitleCharacteristics of Dissolved Nitrous Oxide (N2O) Concentrations and Impacting Factors in a Representative Agricultural Headwater Stream in the Upper Reach of Yangtze River
田琳琳1,2,3; 王正1,2,4; 胡磊1,2,4; 任光前2,5; 朱波1,2
Source Publication环境科学
Abstract随着农业非点源氮(N)污染的加剧,农田周边溪流成为重要的活性N汇和潜在的氧化亚氮(N2O)排放源.为查明长江上游农业源溪流中溶存N2O浓度的全年动态变化特征,于2014年12月~2015年10月开展紫色土丘陵区典型农田源头溪流N2O浓度的连续采样观测,采用水-气顶空平衡-气相色谱法测定顶空气体中N2O浓度,根据相关参数计算出本研究水体中的溶存N2O浓度,并同步测定溪流水体物理化学指标,分析水中溶存N2O浓度的主要影响因素.结果表明,长江上游紫色土丘陵区的典型农业源溪流的硝态氮(NO3--N)是最主要的活性N赋存形态(年均1.45 mg·L-1),溪流水体溶存N2O质量浓度(以N计)全年平均为0.57 μg·L-1(范围0.26~1.28 μg·L-1),冬、春、夏和秋季的均值分别为0.63、0.45、0.53和0.64 μg·L-1,但季节间显著差异.溪流水体溶存N2O浓度全年都处于过度饱和状态(饱和度年平均为203.9%,范围109.7%~546.5%),可见,农业源溪流全年均为潜在的N2O释放源.溪流溶存N2O浓度的变化主要由水体NO3--N浓度决定,N2O的主要产生机制为反硝化作用;溪流季节平均N2O饱和度在夏、秋季显著高于冬、春季,水中溶存N2O饱和度的变化主要受水温和NO3--N浓度的共同影响.研究还发现农业源溪流中溶存N2O浓度在4~10月(湿润季节)间波动明显,较强降雨可促使其水中NO3--N浓度在雨后短期内升高,进而促进水体反硝化作用,导致雨后溪流中溶存N2O浓度的增加.
Other AbstractHeadwater streams around agricultural farmlands can act as important sinks of active nitrogen (N) and potential sources of indirect nitrous oxide (N2O) emissions, as well as aggravating agricultural non-point source N pollution. In this study, the dynamic characteristics of the dissolved N2O concentration in an agricultural headwater stream in the hilly area of purple soil in the upper reach of the Yangtze River were observed during the period Dec. 2014-Oct. 2015 by measuring the headspace gaseous N2O concentration using headspace equilibration-gas chromatography, and the dissolved N2O concentration was calculated according to the related parameters. Simultaneously, the physical and chemical parameters of the stream water were also monitored to understand the factors that affect the dissolved N2O concentration. The results showed that the dissolved N2O concentration in the agricultural headwater stream ranged from 0.26 to 1.28 μg·L-1 with an annual mean value of 0.57 μg·L-1, with nitrate (NO3--N, with an annual mean concentration of 1.45 mg·L-1) as the predominant reactive N form. The seasonal mean concentrations of the dissolved N2O in winter, spring, summer, and autumn were 0.63, 0.45, 0.53, and 0.64 μg·L-1, respectively, without significant seasonal variations. The annual dynamics of the dissolved N2O concentration were primarily governed by the concentration of NO3--N in the stream water, with denitrification being the main process producing N2O. The saturation levels of the dissolved N2O in the stream water showed oversaturation, with an annual mean value of 203.9% (109.7%-546.5%), with a seasonal pattern in which the saturation levels in the summer and autumn were higher than those in the winter and spring, indicating that the agricultural headwater stream can release indirect N2O emissions throughout the year. The temporal variations in the saturation levels of the dissolved N2O were mainly controlled by the water temperature and the NO3--N concentration of the stream water. During April-October, the concentration of dissolved N2O in the stream fluctuated obviously as a result of heavy rainfall, which resulted in an increase of the concentration of NO3-N in the stream water in the short term after the rain, which promoted denitrification and then increased the dissolved N2O level correspondingly.
Keyword农业源溪流  溶存氧化亚氮  饱和度  硝态氮(NO3–-N)  反硝化  温度
Indexed ByEI ; CSCD
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Cited Times:1[CSCD]   [CSCD Record]
Document Type期刊论文
Corresponding Author朱波
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Corresponding Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
田琳琳,王正,胡磊,等. 长江上游典型农业源溪流溶存氧化亚氮(N2O)浓度特征及影响因素[J]. 环境科学,2019,40(4):1939-1949.
APA 田琳琳,王正,胡磊,任光前,&朱波.(2019).长江上游典型农业源溪流溶存氧化亚氮(N2O)浓度特征及影响因素.环境科学,40(4),1939-1949.
MLA 田琳琳,et al."长江上游典型农业源溪流溶存氧化亚氮(N2O)浓度特征及影响因素".环境科学 40.4(2019):1939-1949.
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