Why it matters
Coal seam gas extraction and coal mining may release chemicals into the environment. These chemicals could have an impact on aquatic and terrestrial organisms. Chemicals that affect water quality could also adversely impact on human health. To properly manage the risks, we need to be able to evaluate the toxicity of the chemicals.
Coal seam gas extraction and coal mining may also inadvertently mobilise naturally occurring underground chemicals and bring them to the surface in co-produced water or mine discharge water.
Researchers should consider how these issues contribute to the overall cumulative impacts of coal seam gas extraction and coal mining, at different scales (local to regional) and in different timeframes (tens to thousands of years).
Information on research projects based on the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development’s (IESC’s) 2013 research priorities for chemicals is on the Department of Agriculture, Water and the Environment website: Chemicals: water-related risks to environmental health
The IESC's 2017 revised research priorities for this theme are:
|Key research needs
|1. The fate, transformation and degradation of hydraulic fracturing fluids
|There is limited information about liquid and gas migration from production wells or target coal seams to aquifers (particularly at depth), and long-term liquid and gas migration from the fracture zone via pathways in subsurface rock formations. Developing and applying stable isotope methods to detect contamination in aquifers is one possible research strategy.
|2. The effects of fracturing fluids on the release behaviour of geogenic contaminants
|Hydraulic fracturing fluids have the potential to mobilise geogenic contaminants. Potential mobilisation is affected by elevated temperature, pressure, coal type and fracturing fluid composition. Improved understanding is needed of the transformation and fate of geogenics, including volatile geogenics and new products formed during fracturing, under different physico-chemical conditions.
|3. Composition and effects of flowback and produced water
|Knowledge on the composition and effects of flowback and produced water is required. In particular: development of analytical laboratory methods for detecting and quantifying their composition; characterisation of their physico-chemical, chemical and ecotoxicological properties; identification of factors that influence their composition (for example, formation type, fracturing fluids used, sub-surface processes, interaction with mobilised geogenics and residence time); and determination of their bioaccumulation and effects on aquatic ecosystems. The toxicity of mixtures and the interactive effects of chemical additives also need investigation.
|4. Waste water management
|A review of treatment options (for example, reverse osmosis) for waste water from coal seam gas and coal mining operations, considering: their effectiveness especially for total dissolved solids and endocrine-disrupting chemicals; effects of conductivity and total dissolved solids on freshwater aquatic biota (for example, stygofauna, turtles, frogs); the persistence and mobilisation in soil/sediments of naturally occurring radioactive material decay products; and effects-directed screening approaches to assess endocrine-disrupting and other effects of mixtures.
|5. Emerging issues
|In addition to the research priorities outlined above, there is a need to identify and investigate emerging issues, such as the impact of microbially enhanced coal seam gas production.