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

作者：Liu, Ting; Wang, Fan; Michalski, Greg; Xia, Xinghui^*; Liu, Shaoda

来源：Environmental Science & Technology, 2013, 47(23): 13412-13421.

DOI：10.1021/es403357m

• OXYGEN ISOTOPIC COMPOSITION
• ATMOSPHERIC NITRATE
• SUSPENDED-SEDIMENT
• COUPLED NITROGEN
• WATER
• GROUNDWATER
• BASIN
• DEPOSITION
• DELTA-O-17
• POLLUTION

Many previous studies have used delta N-15 and delta O-18 of nitrate (delta N-15(NO3) and delta O-18(NO3)) to determine the nitrate sources in rivers but were subject to substantial uncertainties and limitations, especially associated with evaluating the atmospheric contribution. The Delta O-17 of nitrate (Delta O-17(NO3)) has been suggested as an unambiguous tracer of atmospheric NO3- and may serve as an additional nitrate source constraint. In the present study, triple nitrate isotopes (delta N-15(NO3), Delta O-17(NO3), and delta O-18(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 Delta O-17(NO3) of the water from the YR ranged from 0 parts per thousand to 1.6 parts per thousand during two normal-water seasons. This suggested that unprocessed atmospheric nitrate accounted for 0-7% of the total nitrate in the YR. The corrected delta N-15(NO3) and delta O-18(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 delta N-15(NO3) and delta O-18(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.

• 出版日期2013-12-3
• 单位北京师范大学