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Groundwater geochemistry of a nitrate-contaminated agricultural site

Amano, Hiroki; Nakagawa, Kei and Berndtsson, Ronny LU (2016) In Environmental Earth Sciences 75(15).
Abstract

Groundwater samples were collected from several soil depths down to 50 m below soil surface to investigate vertical profiles of NO3 and hydrogeochemical characteristics of the experimental site. The experimental site is located in the Shimabara City, Nagasaki, Japan, where nitrate contamination in groundwater is severe due to intensive agricultural production. A transition zone regarding dissolved ions was found between specific depths caused by differences in the permeability of soil layers. Though NO3 concentration decreased significantly in the transition zone, the entire soil depth exceeded permissible levels (50 mg L−1) for drinking purposes. Comparing the temporal... (More)

Groundwater samples were collected from several soil depths down to 50 m below soil surface to investigate vertical profiles of NO3 and hydrogeochemical characteristics of the experimental site. The experimental site is located in the Shimabara City, Nagasaki, Japan, where nitrate contamination in groundwater is severe due to intensive agricultural production. A transition zone regarding dissolved ions was found between specific depths caused by differences in the permeability of soil layers. Though NO3 concentration decreased significantly in the transition zone, the entire soil depth exceeded permissible levels (50 mg L−1) for drinking purposes. Comparing the temporal NO3 fluctuation above the transition zone with that of the below, distinct fluctuations were observed depending on sampling campaign. High rainfall amounts typically lead to initial decrease in NO3 concentration for the shallow groundwater. After some time, however, increase in NO3 concentration occurred due to leaching of accumulated NO3 in the soil matrix. This indicated that temporal NO3 fluctuation is mainly controlled by natural impact and occurring crop system. Results of principal component analysis suggested that application of chemical fertilizers [(NH4)2SO4, NH4NO3, and KCl], dissolution of minerals (feldspar, calcite, and dolomite), and ion exchange are the predominant factors resulting in the observed vertical groundwater chemistry. The relative magnitude of these three principal component scores changed across the transition zone. Below the transition zone, groundwater geochemistry reflected application of NH4NO3 and KCl fertilizer and dissolution of albite and orthoclase.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Groundwater, Nitrate contamination, Nitrate fluctuation, Principal component analysis, Vertical profile
in
Environmental Earth Sciences
volume
75
issue
15
publisher
Springer
external identifiers
  • scopus:84981734344
  • wos:000381077100028
ISSN
1866-6280
DOI
10.1007/s12665-016-5968-8
language
English
LU publication?
yes
id
36f01550-448c-49d6-9eb2-40d930a9f031
date added to LUP
2016-12-14 10:15:57
date last changed
2017-09-18 11:31:16
@article{36f01550-448c-49d6-9eb2-40d930a9f031,
  abstract     = {<p>Groundwater samples were collected from several soil depths down to 50 m below soil surface to investigate vertical profiles of NO<sub>3</sub> <sup>−</sup> and hydrogeochemical characteristics of the experimental site. The experimental site is located in the Shimabara City, Nagasaki, Japan, where nitrate contamination in groundwater is severe due to intensive agricultural production. A transition zone regarding dissolved ions was found between specific depths caused by differences in the permeability of soil layers. Though NO<sub>3</sub> <sup>−</sup> concentration decreased significantly in the transition zone, the entire soil depth exceeded permissible levels (50 mg L<sup>−1</sup>) for drinking purposes. Comparing the temporal NO<sub>3</sub> <sup>−</sup> fluctuation above the transition zone with that of the below, distinct fluctuations were observed depending on sampling campaign. High rainfall amounts typically lead to initial decrease in NO<sub>3</sub> <sup>−</sup> concentration for the shallow groundwater. After some time, however, increase in NO<sub>3</sub> <sup>−</sup> concentration occurred due to leaching of accumulated NO<sub>3</sub> <sup>−</sup> in the soil matrix. This indicated that temporal NO<sub>3</sub> <sup>−</sup> fluctuation is mainly controlled by natural impact and occurring crop system. Results of principal component analysis suggested that application of chemical fertilizers [(NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, NH<sub>4</sub>NO<sub>3</sub>, and KCl], dissolution of minerals (feldspar, calcite, and dolomite), and ion exchange are the predominant factors resulting in the observed vertical groundwater chemistry. The relative magnitude of these three principal component scores changed across the transition zone. Below the transition zone, groundwater geochemistry reflected application of NH<sub>4</sub>NO<sub>3</sub> and KCl fertilizer and dissolution of albite and orthoclase.</p>},
  articleno    = {1145},
  author       = {Amano, Hiroki and Nakagawa, Kei and Berndtsson, Ronny},
  issn         = {1866-6280},
  keyword      = {Groundwater,Nitrate contamination,Nitrate fluctuation,Principal component analysis,Vertical profile},
  language     = {eng},
  month        = {08},
  number       = {15},
  publisher    = {Springer},
  series       = {Environmental Earth Sciences},
  title        = {Groundwater geochemistry of a nitrate-contaminated agricultural site},
  url          = {http://dx.doi.org/10.1007/s12665-016-5968-8},
  volume       = {75},
  year         = {2016},
}