Australian National University research finds Tasmanian lakes among the world’s worst for metal contamination
ICONIC lakes within the Wilderness World Heritage Area have been so badly affected by West Coast mining that their metal contamination readings are among the worst in the world.
Australian National University researchers have studied airborne contamination for the first time in Tasmania and found metal contaminants had travelled up to 130km from historical mining sites in Queenstown and Rosebery.
The study found six lakes, including Dove Lake at Cradle Mountain, had dangerous levels of lead, copper, arsenic and cadmium, with some readings exceeding the highest allowable levels in Australian and New Zealand sediment guidelines. Academics urged more research into the effect on fish, algae and bacteria in those areas, with lead researcher Larissa Schneider saying there could be cause for health concerns.
“As we know, concentrations of contaminants increase as they travel up the food chain so this has implications for anyone who consumes fish from these areas,” the ANU academic said. “We tested a number of metals and metalloids including selenium, where a study in the US proved that lower concentrations than the ones found in Tasmania had affected the ability of fish to reproduce.”
The worst affected lakes were, in order, Owen Tarn, Basin Lake, Perched Lake, Dove Lake, Lake Dobson and Lake Cygnus, with four of those within the Tasmanian Wilderness World Heritage Area. Lakes closer to mine sites had the highest levels of contamination. It was comparable to highly polluted rivers in Pakistan, Iran and China, Dr Schneider said.
Wilderness Society state campaign manager Vica Bayley labelled the study, published in Science of the Total Environment, a “devastating scientific revelation”.
“That Tasmanian icons like Dove Lake and Lake Dobson are global record holders in mining-related toxicity is an indictment on our laws and highlights the challenge of truly protecting conservation reserves from external factors like pollution,” Mr Bayley said. “If World Heritage-listed lakes are polluted at alarming levels, what’s the impact on farmland, drinking water catchments and human health?”
Dr Schneider said the study raised serious questions about who was responsible for the environmental impacts. Testing found the largest contamination occurred when open-cut mining kicked off in 1930.
Tasmania was among the first to legislate an Environmental Protection Act in 1973 but the Labor government, led by Eric Reece, then exempted mining companies from those rules. But the sites were likely able to be remediated, Dr Schneider said.
“If [the Federal Government were to] develop a program that current industry should fund studies to assess what happened in former mines … I think that would be very, very important,” she said.
Tasmanian Minerals and Energy Council chief executive Wayne Bould said his body would look closely at the new research.
“We have a keen interest in remediating any problems that may be the result of any legacy issues over time,” he said.
The State Government and Environment Protection Authority were asked for comment.
Will post the journal article when it is available.
Airborne dust originating at the mine with the dust being washed out of the atmosphere in rain events - just like the crap that gets deposited on your car after rain. Other earlier studies (1980's?) on the western lakes found other gradients of minerals and nutrients such as salt - basically they decrease with distance from source and are related to prevailing wind direction.
If those numbers weren't 'bad' (?) we'll have to see what comes of the later testing. I'd like to see numbers from plateau soil, lakes and small tarns (or, more importantly what those numbers have meant.. for creatures other than us) (Surely there's not ongoing contamination?).
You do need to be careful as none/some/much/all of this "contamination" could arise naturally. Tassie, particularly the West Coast has a complex geology with many mineral rich rocks and especially ultra-mafic sequences which are high in many of the identified minerals. Do some reading on acid mine drainage and keep in mind that this can occur naturally but at a much lower volumes and concentrations than in an exploited (mined) environment.
Owen Tarn would have to be least surprising but it has an even smaller catchment
I'd assume they could only have measured historic contaminants through lake sediments to conclude 'airborne' contamination (ie. above what was naturally there)?
Mark F wrote:You do need to be careful as none/some/much/all of this "contamination" could arise naturally. Tassie, particularly the West Coast has a complex geology with many mineral rich rocks and especially ultra-mafic sequences which are high in many of the identified minerals. Do some reading on acid mine drainage and keep in mind that this can occur naturally but at a much lower volumes and concentrations than in an exploited (mined) environment.
Yes, the paper reports high levels of Aluminium, Iron and Lead in Lake Dove in 1880, before any mining occurred. It must be in a good area to do some mining.
& Table 4 seems to indicate the amount of 'deposit' we've managed to add? What pollution doesn't make it to these catchments (or is still on it's way to the lakes and tarns) could equally contaminate others, especially to their west?
There may be members on this forum who could interpret results and suggest implications. Testing like this does open up reasonable questions.
Does sediment indicate the amount of metals in free water, do unacceptable sediment results mean unacceptable water quality? Does this vary widely with changes in the factors she mentions, eg. seasonally, with temperature changes, after rain?
How about interpreted water quality results from along the track, in that area, Crater lake and all the little tarns on the plateau? (And how about telling us what is in the tank water that would prompt filter warnings?)
I'd be guessing that the average walker would have nothing to worry about, hoping no concern for those drinking this water much more regularly. But just guessing/hoping.
For the health of these environs the results recommend further studies on the effect on biota, the forms of deposits and what (if anything) can be done, in these WWHA lakes.
Different metals will mobilised at different chemistries - pH, oxidation, temperature etc. The reported levels wouldn't have a long term effect on people drinking occasionally from these sources as the conditions are reasonably stable. Probably best not to routinely drink suspended sediments though.
I've seen drinking water catchments on the mainland with higher levels of metals than those reported by the article discussed in this thread.