Links
http://www.usgs.gov/newsroom/article.asp?ID=3813&from=rss#.U38lL5RdWuc
http://www.sciencedirect.com/science/article/pii/S0048969706006978
http://www.crdt.org.kh/2013/09/mekong-river-pollution/
http://fmanha.com.br/blogs/esdras/2011/06/25/peixe-panga-do-rio-mais-poluido-do-vietnam-para-a-mesa-dos-campistas/