For many years, the presence of heavy metals in water and sediments as well as their impacts on both terrestrial and aquatic organisms has been attributed to anthropogenic inputs. In this book, Dr. G.M. Ogendi presents results showing that elevated heavy metals levels may be associated with natural weathering processes and thereby impacting negatively on aquatic and terrestrial organisms. He describes the black shale system with its enriched metal composition, its weathering and impacts on the adjacent aquatic ecosystems. The levels of heavy metals in water, sediments and rock samples were...