Microbial degradation of chemicals in the Tertiary Limestone Aquifer

CSIRO researchers have used groundwater sampling and DNA profiling to demonstrate that microbial communities found in South Australia’s Tertiary Limestone Aquifer (TLA) have the potential to partially detoxify and biodegrade chemicals used in gas exploration and development.

Conducted through CSIRO’s Gas Industry Social and Environmental Research Alliance (GISERA), the research responds to community concerns about onshore gas development in South Australia’s Limestone Coast region.

The TLA is the primary groundwater supply for the Limestone Coast region in the south east of South Australia. The aquifer is used for many purposes, including town water supplies, agricultural and viticulture activities, and industrial uses.

For this study, researchers collected groundwater samples from 21 sites across the region with a range of land-use types. The samples were used to establish baseline data for water chemistry and microbial communities. The data provides an important reference against which any future changes to the environmental health of the aquifer’s waters can be measured.

Twenty-six chemicals associated with onshore gas activities were individually added to aquifer water samples – at the same level of concentration they would be found in a well bore – and incubated for 120 days.

Researchers found that the sampled aquifer microbes were able to partially biodegrade alcohols, butoxyethanol, isopropanol, methanol and propylene glycol.

DNA profiling was then used to identify microbes within the TLA that have the potential to detoxify and biodegrade chemicals used in gas exploration and development. These data identified numerous microbial species that are likely bio-degraders of these chemicals.

Taken together, this suggests that many of the chemicals used by industry are subject to attack and degradation by microbes in the TLA, though the rates of degradation in the aquifer environment are slow and only partial degradation was observed after three months.

This study builds on previous GISERA projects in South Australia and the Northern Territory and results confirm that degradation of chemicals by microbial communities may offer an additional defence against accidental chemical contamination of the local environment.

Read more about this project, and find out about other GISERA projects in South Australia.