Aquatic life, mainly fish, may face risks related with coal seam gas (CSG) mining, said Thursday Australian scientists exploring the relationship between groundwater and coastal life.
Ten years after the discovery of groundwater on the Australian mainland leaking into the ocean, the National Centre for Groundwater Research and Training is trying to understand what it means for coastal ecosystems.
The water flows into the ocean underground through old river channels that have since been buried, known as "wonky holes.”
These mysterious pits – named by fishermen whose nets they snagged, threatening to capsize their boats – were first found in a 60 km-wide strip fringing the Great Barrier Reef (GBR) coastline.
So far, researchers have identified some 200 holes, which resemble pockmarks on the seafloor along the GBR. Thought to be the remnants of fossilised rivers, they may also exist in other places round the 35,000 km Australian coast.
"If there's any contamination in the groundwater on the mainland and they intersect with one of these wonky holes, they're definitely going to take out the chemistry as well as the water," Professor Craig Simmons of the National Centre for Groundwater Research and Training (NCGRT) and Flinders University told Australian Associated Press.
"It's certainly not impossible that something like that could happen. I've not heard of it yet but there's certainly nutrients that are taken into the ocean so there is that possibility,” he added.
During coal seam gas extraction, water, sand and chemicals are injected into the ground at high pressures.
Simmons warns that, for years, people thought of water as draining from the land into the ocean mainly through surface rivers. “We didn’t realize how much groundwater also leaks from shore into the ocean floor itself – or the implications for the supply of fresh water on land,” he said in a statement.
According to the expert, his research colleagues were convinced coastal ecosystems in some areas were strongly dependent on freshwater seepage, but he said that more research needed to be conducted.