Book excerpt: Environmental and Ecological Chemistry is a component of Encyclopedia of Chemical Sciences, Engineering and Technology Resources in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty one Encyclopedias. The Theme on Environmental and Ecological Chemistry prsents the essential aspects such as: Fundamental Environmental Chemistry; Atmospheric Chemistry; Soil Chemistry; Aquatic Chemistry; Ecological Chemistry; Chemistry of Organic Pollutants Including Agrochemicals. These volumes are aimed at the following five major target audiences: University and College students Educators, Professional practitioners, Research personnel and Policy analysts, managers, and decision makers and NGOs.