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Spatial characteristics of groundwater chemistry in Unzen, Nagasaki, Japan

Nakagawa, Kei LU orcid ; Amano, Hiroki LU and Berndtsson, Ronny LU orcid (2021) In Water 13(4).
Abstract

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.... (More)

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.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Groundwater, Hierarchical cluster analysis, Nitrate pollution, Principal component analysis, Water chemistry
in
Water
volume
13
issue
4
article number
426
publisher
MDPI AG
external identifiers
  • scopus:85101272863
ISSN
2073-4441
DOI
10.3390/w13040426
language
English
LU publication?
yes
id
e000f157-1851-4688-b2f2-20cca76372e2
date added to LUP
2021-03-10 07:31:38
date last changed
2023-10-08 22:29:11
@article{e000f157-1851-4688-b2f2-20cca76372e2,
  abstract     = {{<p>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 (NO<sub>3</sub>-N) concentration at eight sampling sites (12%) exceeded Japanese drinking water standard for NO<sub>3</sub> + NO<sub>2</sub>-N (10 mg L<sup>-1</sup>). The highest nitrate concentration was 19.9 mg L<sup>-1</sup>. 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)-HCO<sub>3</sub> or (Ca+Mg)-(SO<sub>4</sub>+NO<sub>3</sub>) type. Groundwater with higher nitrate concentration is of (Ca+Mg)-(SO<sub>4</sub>+NO<sub>3</sub>) 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.</p>}},
  author       = {{Nakagawa, Kei and Amano, Hiroki and Berndtsson, Ronny}},
  issn         = {{2073-4441}},
  keywords     = {{Groundwater; Hierarchical cluster analysis; Nitrate pollution; Principal component analysis; Water chemistry}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{MDPI AG}},
  series       = {{Water}},
  title        = {{Spatial characteristics of groundwater chemistry in Unzen, Nagasaki, Japan}},
  url          = {{http://dx.doi.org/10.3390/w13040426}},
  doi          = {{10.3390/w13040426}},
  volume       = {{13}},
  year         = {{2021}},
}