Frequency distribution of naturally occurring arsenic leached from excavated rocks of Hokkaido Shinkansen tunnels between Shin-Hakodate-Hokuto and Oshamambe
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引用次数: 0
Abstract
Excavated rock produced during tunnel construction projects in volcanic areas and sedimentary rock of marine origin pose the potential hazard of introducing naturally occurring arsenic (As) into the surrounding soils and groundwater. Thus, appropriate management and/or countermeasures against As mobility is required by comprehending the leaching characteristics of the As in excavated and sedimentary rock. This study focused on the Neogene Miocene sedimentary rock of marine origin that is widely distributed between Shin-Hakodate-Hokuto and Oshamambe Stations along the Hokkaido Shinkansen in Hokkaido, Japan. The probability distribution of the leaching concentration of As from the rock excavated from the tunnels between the above stations was evaluated via batch leaching tests using crushed rock as a countermeasure against the rock containing naturally occurring toxic elements. A statistical evaluation of this probability distribution was conducted using a vast amount of test results. The results showed that the As leaching concentration followed a logarithmic normal distribution depending on the geological formation. The concentration was influenced by various factors, including the As content, key chemical composition in the rock, such as calcium (Ca), iron (Fe), and sulfur (S), as well as the pH and electrical conductivity (EC) in the leachate. In addition, the thickness of the overburden was found to impact the As leaching concentration. These results suggest that reasonable countermeasures against the risks of As leaching into the surrounding environment can be devised by considering the probability distribution of the As leaching concentration.
火山地区隧道建设工程中产生的挖掘岩和海洋沉积岩具有将天然砷(As)引入周围土壤和地下水的潜在危险。因此,需要通过了解挖掘岩和沉积岩中砷的沥滤特性来采取适当的管理和/或对策来防止砷的迁移。本研究的重点是广泛分布于日本北海道北杜新干线沿线的新函馆北杜站和押山部站之间的新近纪中新世海相沉积岩。通过批量浸出试验,评估了从上述车站之间的隧道中挖掘出的岩石中 As 浸出浓度的概率分布,该试验使用碎石作为含有天然有毒元素的岩石的对策。利用大量测试结果对这一概率分布进行了统计评估。结果表明,根据地质构造的不同,砷浸出浓度呈对数正态分布。浓度受多种因素影响,包括砷含量、岩石中的主要化学成分,如钙(Ca)、铁(Fe)和硫(S),以及沥滤液中的 pH 值和导电率(EC)。此外,研究还发现覆盖层的厚度也会影响砷的沥滤浓度。这些结果表明,通过考虑砷浸出浓度的概率分布,可以针对砷浸出到周围环境中的风险制定合理的对策。
期刊介绍:
Soils and Foundations is one of the leading journals in the field of soil mechanics and geotechnical engineering. It is the official journal of the Japanese Geotechnical Society (JGS)., The journal publishes a variety of original research paper, technical reports, technical notes, as well as the state-of-the-art reports upon invitation by the Editor, in the fields of soil and rock mechanics, geotechnical engineering, and environmental geotechnics. Since the publication of Volume 1, No.1 issue in June 1960, Soils and Foundations will celebrate the 60th anniversary in the year of 2020.
Soils and Foundations welcomes theoretical as well as practical work associated with the aforementioned field(s). Case studies that describe the original and interdisciplinary work applicable to geotechnical engineering are particularly encouraged. Discussions to each of the published articles are also welcomed in order to provide an avenue in which opinions of peers may be fed back or exchanged. In providing latest expertise on a specific topic, one issue out of six per year on average was allocated to include selected papers from the International Symposia which were held in Japan as well as overseas.