Isn’t that beautiful? A friend found it for me and my heart was very touched. Things in Australia are beyond horrific, I wish an import of beavers could help. Sigh.

Time for another installation of “Lets use physics to study what beavers could do naturally if we just stopped killing them all the time.” From our friends at Phys.org.

Toward a smarter way of recharging the aquifer

To replenish groundwater, many municipalities inject reclaimed water into depleted aquifers. The injected water has been purified by secondary wastewater treatment, and, in some cases, the water has been treated through tertiary processes and can be clean enough to drink directly.

The original water in the aquifer was chemically stable, in equilibrium with the surrounding rocks, and was slowly recharged by natural processes (water infiltration). However, when more groundwater is consumed than the natural processes can restore, engineered recharging with purified, reclaimed water is needed. Unfortunately, over time, the reclaimed water sometimes becomes contaminated.

Well gosh! Landowners are using so much water that they drain of the water table and have to inject it back. Like refilling your bank account, fair enough. But it’s so weird! When they put clean water in it comes out tainted with arsenic! What’s with that?

When we injected the water, it was good,” she said, “but when we withdrew it, it was bad, tainted with arsenic. What was wrong?”

It turned out that although the water being injected into the aquifer was usually clean enough to drink, it was bringing something new to the aquifer: oxygen.

“By injecting reclaimed water, we are triggering oxidative dissolution of sulfide minerals in the aquifer, which were stable at low oxygen levels,” she said. In particular, she looked at arsenopyrite (FeAsS), a mineral that dissolves into iron, sulfur and, crucially, arsenic.

Wait, that’s poison right? I mean if you drink arsenic you die don’t you? At least that’s what happened with those nice little old ladies serving tea to Cary Grant. What rotten luck! You need water so you use water. You will need water in the future so you replace it to save for a not-so-rainy day. And then when you take it out again it gets full of poison! That’s horrible! If only there were some some way to stop it from going all lethal.

Dissolved organic matter keeps water from turning into aresenic? You mean like sticks and leaves and bugs and fish and things that have been broken up in the water over time? Gosh if there were ONLY some tool that could get water back on the land. Recharge the aquifer naturally AND generate lots of DOM so that people won’t be drinking arsenic.