Welcome to Pink Lake; a bubble-gum stretch of water home to a mysterious process which
baffled scientists for decades and still draws tourists to the town of Esperance to this day.
Except it isn’t pink. So why did the colour change and could we do to make it pink once again?
950 km north we arrive at another Pink Lake, but this time one that's actually pink. To get
the full impression though we need to head high up, or even better take to the skies.
Known at Hutt Lagoon, we’re just a little west from Hutt River Province,
an unrecognised micronation which once went to war with Australia.
But we’re not here for esoteric WA history, we're here for the lagoon.
So what gives the lake its pink colour? I originally thought that it must be a trick
of the light or potentially that the floor itself was painted pink.
But, as you can see with a sample of the water, it truly is this weird colour.
I also thought that it might be a chemical spill which is validated by the presence of
an ominous-looking chemical production facility on the other side of the lake.
We’ll get to that facility later, but for now I’ve asked the UWA Chemistry department to help
me analyse two samples of water; one from Hutt Lagoon and the other from my local duck pond.
We found that the Hutt Lagoon sample has a 100
times greater salt concentration than the one from the bottom of my road.
Salt by itself can’t make things pink, but the things living inside the water can.
I’ve made some very big, very simple cells with a mix of water and food
dye encased in a cellulose membrane. I’ll be submerging them into a beaker of fresh water
and also a brine solution with a similar salt concentration to that of Hutt Lagoon.
After 24 hours our salt water cell has shriveled up
while the one in fresh water remains at full size.
Inside the cell we have a low salt concentration while outside there is a high concentration.
Nature hates this sort of imbalance and tries to correct itself. Since salt ions are unable
to pass into the cell through the membrane, water is instead pulled out. This is known as osmosis
where higher the difference in concentration the greater the osmotic pressure.
In salt concentrations like those of Hutt Lagoon this can literally rip cells apart.
As in the immortal words of Dr. Ian Malcolm “life, uh, finds a way” which holds true
for WA’s salty lakes. Duneala salina, a type of single-celled microalgae, replaces the water in
its cells with a chemical known as glycerol. Now, glycerol is quite similar to water in that it can
be used for the foundation of intracellular fluid. But, as you can see, it's a lot more viscous.
In theory it's non-toxic and tastes sweet, but given that I got this bottle from the
UWA chemistry department there's no way I’m going to be testing that out for myself.
After 24 hours both the brine and freshwater cells have no change.
Although there is still the same osmotic pressure as before, the glycerol molecules
are too large to pass through the membrane. Keeping our cells inflated and alive.
Another specialisation allowing dunaliella to thrive in its environment is beta-carotene.
It protects them from Australia’s harsh sunlight. Beta-carotene also gives carrots
their orange colour, but for dunaliella comes in a rather fetching shade of pink.
Since more salt means more osmotic pressure and a tougher environment for regular cells,
very salty lakes are populated almost exclusively by dunaliella.
Pink Lake is incredibly salty and these salt pans form a pure white circumference around
the edge. You can bend down to pick up a clump of the stuff meaning you would never need to
buy table salt again. Which is of course what an early group of entrepreneurs did.
From 1896 to 2007, the eastern portion of the lake was converted into eight solar ponds by the
WA Salt Supply company to extract this resource on an industrial scale. After 100 years of extraction
the salt content of the lake was halved. The salinity fell so far that dunaliella no longer had
its competitive advantage and was out-competed by other species filling this new niche.
These entrepreneurs missed the true opportunity offered by Pink Lake;
the algae itself. As promised, we’ve now arrived at the Hutt Lagoon chemical processing plant
and we’ve sent up a drone to survey the area.
This facility is owned by BASF, the world’s largest chemical producer.
One of these chemicals is beta-carotene; the pigment produced by dunaliella salina.
The ponds are kept at a salt concentration of as close to 24%
as possible, producing a maximum of 40 grams of dry mass per metre squared per day.
From here the algae are moved into a centrifuge where they are spun
to remove each of the constituents. Eventually the products are shipped around the world.
If you’ve purchased baby formula, soft drinks, custards, margarines, yogurts, dietary supplements
and pretty much anything that says natural colouring then there is a decent chance some of it
came from this facility. Some products, particularly those in the beauty sector,
can cost 3,000 dollars per kilogram. By extracting the salt
and by extension the dunaliella algae from Pink Lake, Esperance missed out on this opportunity.
That would normally be the end of the story, except the local town has sort of based their
identity on the Pink Lake. There’s a Pink Lake road, IGA, tourist park, and even a butchers. So,
short of dumping in a load of pink food dye, what could we do to make the water pink again?
Fortunately, there appears to be a correlation between increasing salt content
and the emergence of dunaliella, at least here in Esperance.
When the great southwest highway was built in the 1930s, Lake Warden became the new terminus
point of the local catchment system. All the salt which once flowed into Pink Lake was now
being collected in Lake Warden. In 2011 Lake Warden began to change colour. But instead of
turning pink it's become a more ochre because of the high level of nutrients in the water.
Under Esperance is an ancient pool of super salty water which
could be brought to the surface using pumps. The shire council have recently agreed to do a
200 thousand dollar trial project which, even if successful, will still need even more investment
to bring it to fruition. However, given the importance of tourism to the local economy,
perhaps it is only a matter of time before Pink Lake lives up to its name once again.
Esperance's Pink Lake is a tribute not only to nature's ability to thrive in extreme environments
but also reminds us that humans will always find a way to mess up those conditions. Through careful
conservation and some extreme engineering we’ll be able to revert this lake back to its pink past.
This has been James Dingley from the Atomic Frontier. Keep Looking Up.