10:45 AM - 11:00 AM
[AHW18-07] Approaches to Addressing Construction-excavated Rocks Producing Acidic Water and Investigating the Mechanisms of Acidic Water Occurrence
★Invited Papers
Keywords:acidic water, arsenic, cadmium, construction generated rock
Japan is an island arc formed in the convergent plate boundary located in the dynamic zone of the Circum-Pacific region, making it a region characterized by active volcanic activity and crustal movements. Consequently, metal mines, ore deposit areas, and volcanic zones are distributed throughout the country, with many of these geological formations containing sulfide minerals. These minerals may occur oxidation and decomposition through reactions with oxygen in water and/or air, or microbial activity, resulting in the generation of acidic water. In some cases, these acidic waters contain harmful elements, such as arsenic, lead, and cadmium, exceeding environmental standards, posing risks to human health. The presence of such harmful elements in acidic waters can lead to impacts on ecosystems, changes in landscapes due to the deposition of rust-like precipitates, and potentially severe environmental pollution.
Acidic water containing harmful elements is mainly generated from mining activities, including drainage, waste rocks, and tailings, and has long been a significant issue worldwide. However, in Japan, where geological formations like those mentioned above are distributed throughout the country, instances of environmental pollution in construction-excavated rocks are rare but exist. Furthermore, given that acidic water can be generated through the oxidation and decomposition of sulfide minerals contained in marine sediments, it is essential to implement appropriate measures to prevent environmental pollution in construction-generated soil, similar to those required in mining activities.
In recent years, efforts have been growing trend to consider construction-excavated rocks as a resource in public works projects, actively utilizing it primarily as construction materials such as embankment materials. Even for construction-excavated rocks that may cause environmental pollution, it is possible to utilize it as a resource by applying appropriate measures. Therefore, what becomes crucial is the necessity of appropriate countermeasures and their selection. Implementing excessive measures can lead to unnecessary expenses, while neglecting measures can lead to environmental pollution. Thus, it is essential to understand the lithological characteristics and mineral composition of the construction-excavated rocks in question, as well as the mechanisms of harmful element leaching and acidic water generation, in order to select appropriate measures.
In this presentation, I will introduce strategies regarding Construction-excavated rocks in Japan that produces acidic water containing harmful elements, covering from conventional evaluation methods to the selection of countermeasures. Additionally, I will report on case studies of harmful element leaching and the mechanisms of acidic water formation revealed through electron microscope observations.
Acidic water containing harmful elements is mainly generated from mining activities, including drainage, waste rocks, and tailings, and has long been a significant issue worldwide. However, in Japan, where geological formations like those mentioned above are distributed throughout the country, instances of environmental pollution in construction-excavated rocks are rare but exist. Furthermore, given that acidic water can be generated through the oxidation and decomposition of sulfide minerals contained in marine sediments, it is essential to implement appropriate measures to prevent environmental pollution in construction-generated soil, similar to those required in mining activities.
In recent years, efforts have been growing trend to consider construction-excavated rocks as a resource in public works projects, actively utilizing it primarily as construction materials such as embankment materials. Even for construction-excavated rocks that may cause environmental pollution, it is possible to utilize it as a resource by applying appropriate measures. Therefore, what becomes crucial is the necessity of appropriate countermeasures and their selection. Implementing excessive measures can lead to unnecessary expenses, while neglecting measures can lead to environmental pollution. Thus, it is essential to understand the lithological characteristics and mineral composition of the construction-excavated rocks in question, as well as the mechanisms of harmful element leaching and acidic water generation, in order to select appropriate measures.
In this presentation, I will introduce strategies regarding Construction-excavated rocks in Japan that produces acidic water containing harmful elements, covering from conventional evaluation methods to the selection of countermeasures. Additionally, I will report on case studies of harmful element leaching and the mechanisms of acidic water formation revealed through electron microscope observations.