This theme focuses on probing the biogeochemical cycles of pollutants in the environment by quantifying anthropogenic element fluxes from mining, human apportionment of net primary productivity, construction activities, and fossil fuel and biomass burning, and comparing with natural fluxes from primary productivity, total sediment denudation on land, eolian dust, sea-salt spray, soil erosion and volcanic emissions to model how chemicals flow on Earth's surface. Another focus is on developing new methods that can degrade toxic inorganic contaminants, in particular Cr+6 present in water and soil at heavily contaminated sites. The goal is to build on a nanoparticle-mediated degradation approach that is based primarily on the successful application of nano-scale ZVI (NZVI) particles to reduce the more toxic form to a benevalent form. Recent work involves monitoring changes in carbon isotopic composition of Black Carbon (BC) in Particulate Matter collected on quartz filters from regional sites in India. Our goal is to identify and quantify BC sources with the help of stable carbon isotope fingerprinting and develop independent proxies.