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Mono Lake and arsenic – toxic?

December 2nd, 2010 by Bartshé, Eastern Sierra Policy Director
ISS image of Mono Lake, where arsenic and abundant life both exist. Image Science and Analysis Laboratory, NASA-Johnson Space Center.

ISS image of Mono Lake, where arsenic and abundant life both exist. Image Science and Analysis Laboratory, NASA-Johnson Space Center.

Mono Lake is usually in the spotlight for photographers, birders, and those seeking solutions to balanced water needs in California. You don’t see many geochemists, astrobiologists, or NASA/Jet Propulsion Laboratory staff plying Mono’s shoreline. However, they certainly have been around over the years, and it seems that Mono Lake is getting a little more attention due to it harboring an arsenic-eating microbe. The greater implication for our understanding of life here and elsewhere is exciting … but don’t conclude that Mono Lake is a toxic, arsenic-saturated lake!

There is arsenic in Mono Lake, but it’s in trace amounts overall, and it is found in greater concentration in specific areas of the lake. Arsenic is toxic to cellular function, but Mono Lake is also home to one of the most productive aquatic ecosystems on earth. In the summer trillions of brine shrimp and endless clouds of alkali flies feed on microscopic algae. The flies and shrimp in turn feed millions of resident and migratory birds. Collectively, the amount of biomass in Mono Lake, produced in the upper water column, is staggering. Mono Lake water has an unusual chemical brew of sodium, carbonates, sulfates, borates, and even trace amounts of arsenic. Yet, it is astonishingly productive. Sure, you won’t find fish, and most aquatic life on earth can’t survive in Mono’s waters, but if you think it’s toxic, spending an hour at the shoreline during summer will tell you a strikingly different story.

2 Responses to “Mono Lake and arsenic – toxic?”

  1. avatar Greg, Information Specialist Says:

    Click here to see a water quality analysis of Mono Lake’s mineral content, adjusted for the volume of the lake at its lowest, most concentrated level in 1982. At that time the arsenic level was 17 parts per million (0.01 parts per million is the EPA drinking water standard–although you can’t drink Mono Lake water!).

  2. avatar David Carle Says:

    If I’m reading the information correctly, the bacteria have the capability of utilizing arsenic as a substitute for phosphorus, but that substitution happened in the lab under highly concentrated arsenic conditions and (here’s where I don’t think the stories are clear) not under the conditions found in Mono Lake itself. How the bacteria evolved that capability is a great question. What it means for our understanding of the building blocks of life is another great topic. But the relationship to “natural” conditions in the lake is getting confused, I think.