It may be important to know where and when (which month) you collected the sample, especially how high the sampling site was.

Hello Sir,

We have collected samples through out the year from a very remote location near Gangotri Glacier. The winter samples have very low lead isotope signatures compared to the other month samples. I am trying to find if there is any atmospheric process linked with this change, other than contribution from different sources. 

Perhaps this is the result of changes in precipitation around the site, you changes in wind direction in different months, or wind speed patterns.  Some of that mean monthly data for 30 years can be found here.....

https://www.meteoblue.com/en/weather/forecast/modelclimate/gangotri-glacier_india_1271640

Hi, Arijeet,

I'd suggest that you make an analysis of the vertical convection in the area using reanalysis temperature data. Winter is a season when the air convection is weaker due to the cooling of the surface and probably the existence of the temperature inversion, which will not be beneficial to the upward transport of the lead pollutants from the surface sources of plains of the northern Indian sub-continent.

Guoyu Ren

Are you measuring also Pb210?

Dear Prof Holub,

I measured 204,206,207 and 208Pb for Himalayan dust samples.

Dear Prof Ren,

I will surely look into it. 

Thank you.

Arijeet

Pb210 can be measured using 45 keV peak by gamma spectroscopy. Because Pb210 comes most likely from Rn in air, via Bi210 and Po210, it can give you information on movements of air masses. There are many papers describing that. Also the group in Bhabha research center in Mumbay can easily measure these radioactive isotopes. Do you have a ICP/MS (induction coupled plasma mass spectrometer?