Here are some potential sources that could be used to add more information and references to this article. https://www.scopus.com/record/display.uri?eid=2-s2.0-85111045053&origin=resultslist&sort=plf- https://www.epa.gov/acidrain/what-acid-rain https://www.adirondackcouncil.org/page/acid-rain-86.html