Ammonium nitrogen deposition as a dominant source of nitrogen in a forested watershed experiencing acid rain in central Japan

Young Sik Ham, Hiromi Kobori, Joo Hyon Kang, Joon Ha Kim

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

To clarify nitrogen (N) sources, the overall N budget in a forested watershed in Kanagawa Prefecture, Central Japan was estimated by measuring dissolved inorganic N (DIN; NH4 + + NO3 - + NO2 -) from Nov 2004 through Oct 2005. The estimated N budget (-1.43 kg N ha-1 year-1) showed that the N output rate (stream water N) was higher than the N input rate (bulk deposition N) in the watershed. The annual NO2 - and NO3 - input rates were 0.02 and 1.99 kg N ha-1 year-1, respectively. NH4 + was the predominant source in this forested watershed, accounting for 71% (4.99 kg N ha -1 year-1) of DIN input rate. In addition, this study estimated rainfall pH, air temperature, and wind direction, which were considered as controlling factors related to the atmospheric deposition rate of NH4 +. This study showed that the rainfall NH4 + was inversely proportional to the initial pH of the rainfall, which was calculated by adding the amount of H+ consumed by the dissociation process of NH3(aq) to the measured rainfall pH. This result implies that acid rain can elevate the solubility of NH3(g) and the dissociation capacity of NH4 + throughout the process of precipitation. Also, this study provides strong evidence that the high NH4 + deposition rate is mainly derived from NH 3(g) emitted from livestock wastes under the NH3 transport condition of warm summer and favorable wind direction.

Original languageEnglish
Pages (from-to)337-344
Number of pages8
JournalWater, Air, and Soil Pollution
Volume212
Issue number1-4
DOIs
StatePublished - Oct 2010

Keywords

  • Acid rain
  • Atmospheric N deposition
  • Central Japan
  • Forested watershed
  • Livestock
  • N sources

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