Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan
Nitrate pollution in groundwater is a severe problem in Shimabara Peninsula, Nagasaki Prefecture, Japan. Previous studies have investigated water quality characteristics in the northern part of the peninsula and shown serious effects of nitrate pollution in the groundwater. The present study aimed t...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-12-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/14/24/4106 |
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| author | Kei Nakagawa Hiroki Amano Zhi-Qiang Yu Ronny Berndtsson |
| author_facet | Kei Nakagawa Hiroki Amano Zhi-Qiang Yu Ronny Berndtsson |
| author_sort | Kei Nakagawa |
| collection | DOAJ |
| description | Nitrate pollution in groundwater is a severe problem in Shimabara Peninsula, Nagasaki Prefecture, Japan. Previous studies have investigated water quality characteristics in the northern part of the peninsula and shown serious effects of nitrate pollution in the groundwater. The present study aimed to investigate the groundwater quality in the southern areas of the peninsula for improved understanding of the water quality status for the entire peninsula. Groundwater samples were collected at 56 locations in Minami-Shimabara City from 28 July to 4 August 2021. The spatial distribution of water quality constituents was assessed by Piper-trilinear and Stiff diagrams for major ion concentrations. One agricultural area in the western parts exceeded Japanese recommended standards for water. According to the Piper-trilinear diagram, 44 sampling sites (78.6%) were classified as alkaline earth carbonate type, nine sites (16.1%) as alkaline earth non-carbonate type, and three sites (5.3%) as alkaline carbonate type. Stiff diagrams displayed Ca-HCO<sub>3</sub> water type for most of the sites. Na-HCO<sub>3</sub> and Mg-HCO<sub>3</sub> types were found in coastal areas. Principal component analyses showed that the first component corresponded to dissolved constituents in groundwater and denitrification, the second effects of ion exchange and low nitrate pollution, and the third effects of severe nitrate pollution. Hierarchical cluster analysis was used to classify the groundwater into five groups. The first group included sites with relatively high nitrate concentration. The second group had relatively low ion concentration, distributed from center to eastern parts. The third group included intermediate ion concentration, distributed at lower altitudes along the coastal line. The fourth and fifth groups had a higher ion concentration, especially characterized by high sodium and bicarbonate concentration. |
| first_indexed | 2024-03-09T15:43:30Z |
| format | Article |
| id | doaj.art-1e4a4aff0c604bd28790e4151793509f |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-09T15:43:30Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-1e4a4aff0c604bd28790e4151793509f2023-11-24T18:42:59ZengMDPI AGWater2073-44412022-12-011424410610.3390/w14244106Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, JapanKei Nakagawa0Hiroki Amano1Zhi-Qiang Yu2Ronny Berndtsson3Institute of Integrated Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanUndergraduate School of Humanities and Science, Tokai University, 9-1-1 Toroku, Higashi-ku, Kumamoto 862-8652, JapanGraduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDivision of Water Resources Engineering & Centre for Advanced Middle Eastern Studies, Lund University, P.O. Box 118, SE-221 00 Lund, SwedenNitrate pollution in groundwater is a severe problem in Shimabara Peninsula, Nagasaki Prefecture, Japan. Previous studies have investigated water quality characteristics in the northern part of the peninsula and shown serious effects of nitrate pollution in the groundwater. The present study aimed to investigate the groundwater quality in the southern areas of the peninsula for improved understanding of the water quality status for the entire peninsula. Groundwater samples were collected at 56 locations in Minami-Shimabara City from 28 July to 4 August 2021. The spatial distribution of water quality constituents was assessed by Piper-trilinear and Stiff diagrams for major ion concentrations. One agricultural area in the western parts exceeded Japanese recommended standards for water. According to the Piper-trilinear diagram, 44 sampling sites (78.6%) were classified as alkaline earth carbonate type, nine sites (16.1%) as alkaline earth non-carbonate type, and three sites (5.3%) as alkaline carbonate type. Stiff diagrams displayed Ca-HCO<sub>3</sub> water type for most of the sites. Na-HCO<sub>3</sub> and Mg-HCO<sub>3</sub> types were found in coastal areas. Principal component analyses showed that the first component corresponded to dissolved constituents in groundwater and denitrification, the second effects of ion exchange and low nitrate pollution, and the third effects of severe nitrate pollution. Hierarchical cluster analysis was used to classify the groundwater into five groups. The first group included sites with relatively high nitrate concentration. The second group had relatively low ion concentration, distributed from center to eastern parts. The third group included intermediate ion concentration, distributed at lower altitudes along the coastal line. The fourth and fifth groups had a higher ion concentration, especially characterized by high sodium and bicarbonate concentration.https://www.mdpi.com/2073-4441/14/24/4106groundwaterprincipal component analysishierarchical cluster analysis |
| spellingShingle | Kei Nakagawa Hiroki Amano Zhi-Qiang Yu Ronny Berndtsson Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan Water groundwater principal component analysis hierarchical cluster analysis |
| title | Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan |
| title_full | Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan |
| title_fullStr | Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan |
| title_full_unstemmed | Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan |
| title_short | Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan |
| title_sort | groundwater quality and potential pollution in the southern shimabara peninsula japan |
| topic | groundwater principal component analysis hierarchical cluster analysis |
| url | https://www.mdpi.com/2073-4441/14/24/4106 |
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