Temperature change affected groundwater quality in a confined marine aquifer during long-term heating and cooling
Temperature change affected groundwater quality in a confined marine aquifer during long-term heating and cooling
复制标题
长期加热和冷却过程中温度变化影响海洋承压含水层的地下水质量
DOI：
10.1016/j.watres.2016.01.043
复制
发表时间：
2016
期刊：
影响因子：
12.8
通讯作者：
Toshiko Komatsu
中科院分区：
文献类型：
--
作者：
Takeshi Saito;Shoichiro Hamamoto;Takashi Ueki;Satoshi Ohkubo;Per Moldrup;Ken Kawamoto;Toshiko Komatsu
全球变暖和城市化以及地下基础设施（如地铁、购物中心、污水处理系统和地源热泵系统）的发展可能会导致相对较浅的地下水库的温度迅速上升（地下热污染）。然而，地下温度的变化对地下水水质的潜在影响，由于改变了物理，化学和微生物的过程很少受到关注。因此，我们调查了34个地下水水质参数的变化，在13个月的强化加热期间，随后的14个月的自然或强化冷却在封闭的海洋含水层在约17米深的琦玉大学校园，日本。安装了一个全尺寸的地源热泵试验设施，包括一个50米深的U型管，用于循环载热流体和四个监测威尔斯井在1，2，5和10米的U型管，地下水水质监测每1-2周。该地区地下水位的快速变化，特别是在夏季，阻碍了使用单井时间序列对温度影响的准确分析。相反，双井分析（DWA）的应用，比较地下温度和地下水化学浓度的变化之间的热扰动井和未受影响的参考井。使用1米远的井（温度升高至7 °C）和10米远的井（非温度影响），8个组分的DWA呈近似线性关系（B、Si、Li、溶解有机碳（DOC）、Mg 2+、NH 4+、Na+和K+），表明温度变化为7 °C时，浓度变化在4%和31%之间。
Global warming and urbanization together with development of subsurface infrastructures (e.g. subways, shopping complexes, sewage systems, and Ground Source Heat Pump (GSHP) systems) will likely cause a rapid increase in the temperature of relatively shallow groundwater reservoirs (subsurface thermal pollution). However, potential effects of a subsurface temperature change on groundwater quality due to changed physical, chemical, and microbial processes have received little attention. We therefore investigated changes in 34 groundwater quality parameters during a 13-month enhanced-heating period, followed by 14 months of natural or enhanced cooling in a confined marine aquifer at around 17 m depth on the Saitama University campus, Japan. A full-scale GSHP test facility consisting of a 50 m deep U-tube for circulating the heat-carrying fluid and four monitoring wells at 1, 2, 5, and 10 m from the U-tube were installed, and groundwater quality was monitored every 1–2 weeks. Rapid changes in the groundwater level in the area, especially during the summer, prevented accurate analyses of temperature effects using a single-well time series. Instead, Dual-Well Analysis (DWA) was applied, comparing variations in subsurface temperature and groundwater chemical concentrations between the thermally-disturbed well and a non-affected reference well. Using the 1 m distant well (temperature increase up to 7 °C) and the 10 m distant well (non-temperature-affected), the DWA showed an approximately linear relationships for eight components (B, Si, Li, dissolved organic carbon (DOC), Mg2+, NH4+, Na+, and K+) during the combined 27 months of heating and cooling, suggesting changes in concentration between 4% and 31% for a temperature change of 7 °C.