煤炭的非传统稳定同位素研究进展

A review of recent development of non-traditional stable isotope geochemistry in coal

煤炭在世界各国的能源结构中都占有极其重要的地位,被工业界誉为“黑色的金子”。中国能源结构也以煤为主,煤炭资源的利用对人们的生产生活有着举足轻重的作用,其存放、运输和燃烧过程中向环境中排放大量有害、有毒物质,影响人体健康。非传统稳定同位素作为一种新兴的示踪剂,可以为上述过程提供示踪,逐渐在煤炭研究中得到应用。本文拟对煤炭研究中成熟的非传统稳定同位素(Li、B、K、Mo和Hg)的应用进行综述,包括不同地区煤中同位素特征以及煤中非传统稳定同位素在环境示踪方面的潜力。最后对煤中非传统稳定同位素前处理消解存在的问题、不同赋存状态、其他非传统稳定同位素和激光原位研究进行展望。

Background, aim, and scope Coal is an extremely important global energy resource, and is regarded as the “black gold” by the industry. It is a particularly vital part of China’s energy strategy as it accounts for over half of its energy consumption. It is also pivotal for the country’s green energy transition and the carbon neutral plan. Due to the complex nature of coal compositions, a large quantity of harmful and toxins and pollutants will be released and emitted into the atmosphere, hydrosphere, and biosphere during its storage, transportation and combustion process, which will impact human health and cause significant environmental concerns. Recent development of the so-called non-traditional stable isotopes provide novel tracers for these processes, which have gradually become the frontiers in energy and environmental research. Materials and methods In this review, we look back at the recent progress and new applications of a number of non-traditional stable isotopes systems,such as Li, B, K, Mo and Hg in coal and their associated deposits. Results(1) The transportation and combustion process of coal can be faithfully traced by Li and B isotopes;(2) the variation of K isotope isotopic composition in coal is mainly affected by terrigenous clasts and coal-forming plants;(3) Mo isotope isotopic composition in coal is different from different regions of China;and(4) Hg isotope systematics provide an effective means to help understand the origin of coal and the fate of the gaseous Hg emissions during coal combustion.Discussion The complex nature of coal and its pretreatment present great challenges in applying the isotope systems in coal research. One such obstacle is the loss of volatile elements and the lack of appropriate sampling devices for collecting gaseous substances during sample preparation. The other is that there are white precipitates due to formation of silicate insoluble mineral. Sequential Chemical Extraction Technology and in-situ laser methods combined with emerging isotope systems are expected to generate new paradigm for coal related research and provide powerful tools for more in-depth exploration. Of the need for new reference materials,however is of paramount importance for developing the in-situ laser technique and non-traditional stable isotopes in coal. Conclusions Non-traditional stable isotopes are highly sensitive tracers for sourcing of some critical metal elements in coal. They can also help put constraints on the migration and transformation processes of coal during combustion. Recommendations and perspectives Further investigation can be strengthened in the following aspects:(1) development of experimental setups and prototypes to collect volatile elements during coal combustion;(2) improvement in in-situ measurement in coal.