Characteristics of seasonal NO3--N discharge by groundwater in a coastal agricultural catchment

Mitsuyo Saito, Shin Ichi Onodera

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The seasonal variation in the nitrate-nitrogen (NO3--N) discharge by groundwater to the sea was evaluated from the monitoring data of hydraulic potential and NO3--N concentrations in the groundwater of a small coastal agricultural catchment. A large variation in the NO3--N concentration (<0.05 - 5.3 mg L-1) was found in the shallower groundwater of the coastal area. These results suggest that NO3--N attenuation via denitrification influences the seasonal variation in NO3--N concentrations. Furthermore, significant NO3--N attenuation was confirmed in relatively small Darcy flux (<1.8 x 10-6 cm/s). The estimated NO3--N flux varied (0.006 - 0.8 kg d-1) with changes in the NO3--N concentration. Annual groundwater discharge is estimated to be 1.7-fold higher than river discharge, while groundwater NO3--N flux accounts for approximately 70% of river flux owing to the attenuation of NO3--N in coastal areas.

Original languageEnglish
Pages (from-to)141-151
Number of pages11
JournalJapanese Journal of Limnology
Issue number2
Publication statusPublished - 2009
Externally publishedYes


  • Coastal agricultural catchment
  • Groundwater
  • NO-N discharge
  • Seasonal variation

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology
  • Water Science and Technology


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