1. Department of Geological Sciences, Achievers University, Owo, Nigeria
2. Department of Environmental Health Sciences, College of Medicine, University of Ibadan, Ibadan, Nigeria
3. Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, China
4. School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China
5. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China