these oily looking patches appear on my pond from time to time but I have no idea where they are coming from other than the sky, is this possible as I do live under the flight path of Manchester airport?
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A light oily film can be caused by decomposing pond plants, it can be removed by floating a paper towel on the pond surface; however look for a rotting plant as the source. This is just one but likely possible cause.
Chris Brooks - www.dragonfly-images.co.uk
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Geology can also cause these effects, clays, shales, coal. Not from aircraft ;-)
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....birds bathing can disturb bottom and they also release oils into the water - not to this extent though.
If you touch the oily film and it break up into tiny flakes/plates I have been told that this indiicates a plant wax breakdown product and if it just moves around like oil its probably oil! (but i cannot remember who told me and when)
Firstly, I'd ask if your pond is lined? If it is, the answer cannot be connected to geology. It won't be aircraft, either. Secondly, have you had a really good hunt around in the pond to ensure that no-one has dumped some oily refuse in it? If the answer to that is yes, you've looked, then the solution is probably simply the breakdown of detritus.
Your photo shows a large amount of leaf litter in your pond. Every living thing is composed of cells & every cell has a lipid (fat) membrane that encases it. So, if a pond is full of organic matter, there will be a lot of fatty substances in it.
Do you clean debris out of your pond periodically? You need to do this.
One final point: is your pond (in summer, at least) full of living things? If so, it is very unlikely to be external pollution.
Lat/Lng: 53.7335, -2.1385
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