**Acknowledgements**

I am grateful for the help and analytical skills of Dr. Stephan Hug, Eawag, Dübendorf, Switzerland, and I thank Thomas Ruettimann, Eawag, for analysis of the samples by ICP-MS. My gratitude for support and valuable discussions is expressed to Tommy Ngai and Candice Young-Rojanschi from CAWST, Calgary, Canada; Bipin Dangol and Hari Boudhatoki from ENPHO, Kathmandu, Nepal; Gyan Prakash Yadav, Parasi, and to Som Rai, my loyal expedition and trekking guide in Nepal and responsible for all logistics over many years.
