Using 15N, 17O, and 18O To Determine Nitrate Sources in the Yellow River, China

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• 作者：Ting Liu ; Fan Wang ; Greg Michalski ; Xinghui Xia ; Shaoda Liu
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：December 3, 2013
• 年：2013
• 卷：47
• 期：23
• 页码：13412-13421
• 全文大小：403K
• 年卷期：v.47,no.23(December 3, 2013)
• ISSN：1520-5851

文摘

Many previous studies have used 未¹⁵N and 未¹⁸O of nitrate (未¹⁵N_NO3 and 未¹⁸O_NO3) to determine the nitrate sources in rivers but were subject to substantial uncertainties and limitations, especially associated with evaluating the atmospheric contribution. The 螖¹⁷O of nitrate (螖¹⁷O_NO3) has been suggested as an unambiguous tracer of atmospheric NO₃^{鈥?/sup> and may serve as an additional nitrate source constraint. In the present study, triple nitrate isotopes (未15N_NO3, 螖17O_NO3, and 未18O_NO3) were used for the first time to assess the sources and sinks of nitrate in the Yellow River (YR) basin, which is the second longest river in China. Results showed that the 螖17O_NO3 of the water from the YR ranged from 0鈥?to 1.6鈥?during two normal-water seasons. This suggested that unprocessed atmospheric nitrate accounted for 0鈥?% of the total nitrate in the YR. The corrected 未15N_NO3 and 未18O_NO3 values with atmospheric imprints being removed indicated that the main terrestrial sources of nitrate were sewage/manure effluents in the upstream of the YR and manure/sewage effluents and ammonium/urea-containing fertilizer in the middle and lower reaches which made comparable contributions to the nitrate. In addition, there was a significant positive relationship between 未15N_NO3 and 未18O_NO3 values of river water (p < 0.01) which may signal the presence of denitrification. This study indicates that the triple nitrate isotope method is useful for assessing the nitrate sources in rivers, especially for the measurements of atmospheric nitrate contribution.}