Effects of the Japanese Nitrate Directive Plan (NDP) to curb groundwater nitrate-nitrogen content in the Miyakonojo River Basin
Effects of the Japanese Nitrate Directive Plan (NDP) to curb groundwater nitrate-nitrogen content in the Miyakonojo River Basin
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DOI：
10.1016/j.jhydrol.2022.128563
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发表时间：
2022-10
影响因子：
6.4
通讯作者：
Zhiqiang Yu;K. Nakagawa;R. Berndtsson;T. Hiraoka;Yoshihiro Suzuki
中科院分区：
文献类型：
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作者：
Zhiqiang Yu;K. Nakagawa;R. Berndtsson;T. Hiraoka;Yoshihiro Suzuki
迫切需要评估不同的管理技术，以改善地下水质量。为了保持日本宫古之城河流域（MRB）地下水的良好质量，2004年实施了硝酸盐指令计划（NDP）。为了评估该计划的有效性，我们对26年（1996-2021年）来自多达584口地下水威尔斯井的地下水硝酸盐氮（NO3−-N）数据进行了多变量时间序列分析。结果表明，NO3−-N呈上升趋势（p≤ 0.05）的威尔斯井从1996年的5.8%增加到2009年的13.8%，此后随着时间的推移趋于平稳。NO3−-N呈下降趋势（p≤ 0.05）的地下水威尔斯井数量从1996年的18.7%增加到2021年的52.5%。这些地下威尔斯井主要分布在河流附近的城市和农业生产区。NO3--N含量的年变化率随时间的推移呈现出增加和减少的趋势（p≤ 0.05）。但最重要的是，从2004年到2021年，超过环境最大允许值的地下水威尔斯数量减少了60%以上。因此，有统计证据表明，NDP改善了区域流域尺度的NO3−-N地下水质量，并且氮水平正在逐渐降低。
There are urgent needs to evaluate different management techniques to improve groundwater quality. To maintain a good quality of groundwater in the Miyakonojo River Basin (MRB), Japan, the Nitrate Directive Plan (NDP) was implemented in 2004. To assess the efficiency of this plan, we performed multivariate times-series analyses on 26 years (1996–2021) of groundwater nitrate-nitrogen (NO3−-N) data from up to 584 groundwater wells. Results showed that wells with an increasing NO3−-N trend (p≤ 0.05) increased from 5.8% in 1996 to 13.8% in 2009 and thereafter leveled off with time. The number of groundwater wells with a decreasing NO3−-N trend (p≤ 0.05) increased from 18.7% in 1996 to 52.5% in 2021. These groundwater wells are primarily distributed in urban and agricultural production areas near rivers. However, the annual change rate of NO3−-N content displayed both increasing and decreasing NO3−-N trend (p≤ 0.05) over time. But most importantly, the number of groundwater wells exceeding the environmental maximum permissive value reduced by > 60% from 2004 to 2021. Thus, there is statistical evidence that NDP has improved the groundwater quality regarding NO3−-N at the regional basin scale and that nitrogen levels are gradually being reduced.