The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Profile photo of Ronny Berndtsson

Ronny Berndtsson

Professor, Dep Director, MECW Dep Scientific Coordinator

Profile photo of Ronny Berndtsson

Spatial characteristics of groundwater chemistry in Unzen, Nagasaki, Japan

Author

  • Kei Nakagawa
  • Hiroki Amano
  • Ronny Berndtsson

Summary, in English

Nitrate pollution in groundwater is a serious problem in Shimabara Peninsula, Nagasaki, Japan. A better understanding of the hydrogeochemical evolution of groundwater in vulnerable aquifers is important for health and environment. In this study, groundwater samples were collected at 12 residential and 57 municipal water supply wells and springs in July and August 2018. Nitrate (NO3-N) concentration at eight sampling sites (12%) exceeded Japanese drinking water standard for NO3 + NO2-N (10 mg L-1). The highest nitrate concentration was 19.9 mg L-1. Polluted groundwater is distributed in northeastern, northwestern, and southwestern areas, where land is used for intensive agriculture. Correlation analysis suggests that nitrate sources are agricultural fertilizers and livestock waste. Dominant groundwater chemistry is (Ca+Mg)-HCO3 or (Ca+Mg)-(SO4+NO3) type. Groundwater with higher nitrate concentration is of (Ca+Mg)-(SO4+NO3) type, indicating nitrate pollution affecting water chemistry. Principal component analysis extracted two important factors controlling water chemistry. The first principal component explained dissolved ions through water-rock interaction and agricultural activities. The second principal component explained cation exchange and dominant agricultural effects from fertilizers. Hierarchical cluster analysis classified groundwater into four groups. One of these is related to the dissolution of major ions. The other three represent nitrate pollution.

Department/s

  • Centre for Advanced Middle Eastern Studies (CMES)
  • MECW: The Middle East in the Contemporary World
  • Division of Water Resources Engineering
  • LTH Profile Area: Water

Publishing year

2021

Language

English

Publication/Series

Water

Volume

13

Issue

4

Document type

Journal article

Publisher

MDPI AG

Topic

  • Oceanography, Hydrology and Water Resources

Keywords

  • Groundwater
  • Hierarchical cluster analysis
  • Nitrate pollution
  • Principal component analysis
  • Water chemistry

Status

Published

ISBN/ISSN/Other

  • ISSN: 2073-4441