Iron: Extraterrestrial or Anthropogenic ?

I’ve begun a new project to isolate magnetotactic bacteria (using organelles called magnetosomes these bacteria orientate themselves along magnetic field lines)  from natural water courses. The process involves a magnetic dredging and panning step, followed by an enrichment using a capillary racetrack. I chose our waterbutt (collects rain from our roof) in the first instance and was astonished by the amout of magnetic iron that I collected from its sediment. Every day around 200 tons of extraterrestrial matter enters the Earth’s atmosphere, and most of this is in the form of micrometeorites. Most

of these are made from iron,  and they  are thus magnetic,  so it’s tempting to speculate that the magnetic material in the water butt comprises these which have hit our roof and then been concentrated in our water butt by rain. It’s more likely though, that this material, given its quantity, is anthropogenic iron, that is part of the tens of thousands of tons of iron particles and dust that daily enter the Earth’s atmosphere, from engines of all kinds, fly ash from coal fired power stations etc. Makes you wonder what all of this iron is doing to the environment.

The magnetic iron particles, concentrated by a disc magnet

The magnetic iron particles, concentrated by a disc magnet

The iron particles reacting to a bar magnet.

The iron particles reacting to a bar magnet.

The magnetic iron particles, concentrated by a disc magnet

The magnetic iron particles, concentrated by a disc magnet

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