For surface ( river ) water pollution good on line literature available.

Akmal: Part of the difficulty finding literature on the topic you want to study has to do with performing the search using correct terms in, for example, google scholar. Because the term "pollution" is defined in specific or different ways in different disciplines, you should instead search using the term "contamination." And, because the term "contamination" can apply to a wide range of natural substances, you need to qualify that. So, for example, in google scholar you could search for:

contamination "naturally occurring" "heavy metal."

Tidal water pollution can not be ruled out for river water pollution. Anthropogenic pollution is difficult to separate from natural cause of river water pollution and can not be ruled out. Published work and on line literature are available

thank you for replies. I do have problem searching for it. maybe i didn't apply the correct browser technique. every time i googled the anthropogenic would come out.

thank you for your suggestion i will try again