So (180m/s x 3m) *10microgram=5400microgram/second.
5400microgram * 10*60= 3.24grams in 10 minutes.
At a higher concentration (still low) of 100 micrograms per cubic meter of air it would be 32.4g per engine per transit through the layer.
This is assuming 10 minutes transit, I believe the cloud is now down to FL10 and below isn't it?
Right. I made an algebraic error. 32 g is it.
You can easily adapt to different times and conditions.