Groundwater nitrogen response to regional land-use management in South Japan
Groundwater nitrogen response to regional land-use management in South Japan
复制标题
地下水氮对日本南部区域土地利用管理的响应
DOI：
10.1007/s12665-021-09936-5
复制
发表时间：
2021
影响因子：
2.8
通讯作者：
Y
中科院分区：
文献类型：
--
作者：
Yu;Z-Q;Nakagawa;K;Berndtsson,R;Hiraoka;T;Suzuki;Y
为了更好地了解不同土地利用类型的区域地下水管理对地下水中氮含量的影响，我们调查了日本南部的宫古野町流域，该流域自2004年以来一直在实施硝酸盐指令。为此，我们使用了2000至2017年间420口井的氮素浓度，并结合8种不同的土地利用分类。结果表明，森林补给区的平均氮素浓度最低，约为2.9 mg/L，城市地区的平均氮素浓度约为4.4 mg/L，农业用地如水田的平均氮素浓度约为5.1 mg/L，地下水排泄区和居民区的平均地下水氮素浓度分别为8.2和7.1 mg/L。农业用地集约利用和城市污水排放是这些地区地下水氮污染的主要原因。在2009年至2017年期间，约有70%的井地下水氮浓度呈下降趋势(p<； 0.05，p≥ 0.05)。从2000-2008年(增加)到2009-2017年(减少)，约有20%的井出现了趋势逆转。总体而言，硝酸盐指导计划似乎对缓解地下水氮问题产生了积极影响。但仍有30%的水井未出现下降趋势，部分水井超过最大允许饮用水标准。因此，管理层需要继续改善地下水含氮量方面的条件。
For a better understanding of the effects of regional groundwater management for different land-use types on nitrogen content in groundwater, we investigated the Miyakonojo River Basin in south of Japan where the Nitrate Directive Plan has been in practice since 2004. For this purpose, we used nitrogen concentrations from 420 wells between 2000 and 2017 together with 8 different land-use categorizations. The data were analyzed using self-organizing maps (SOM) and results showed that forest recharge areas have lowest mean nitrogen concentrations of about 2.9 mg/L. Urban areas displayed a mean nitrogen concentration of about 4.4 mg/L. Agricultural land such as paddy fields had a mean nitrogen concentration of about 5.1 mg/L. Groundwater discharge and residential areas had mean groundwater nitrogen concentrations of 8.2 and 7.1 mg/L, respectively. Intensive agricultural land-use and wastewater discharge from urban areas caused the main groundwater nitrogen contamination in these areas. About 70% of the wells had a decreasing trend of groundwater nitrogen concentration (p< 0.05,p≥ 0.05) during the period 2009–2017. About 20% of the wells displayed a trend reversal from 2000–2008 (increasing) to 2009–2017 (decreasing). In general, the Nitrate Directive Plan appears to have had positive effects for mitigating groundwater nitrogen problems. However, 30% of the wells still do not display a decreasing trend and some wells exceed maximum permissive level for drinking water. Thus, management needs to continue to improve groundwater conditions regarding nitrogen content.