Climate change and land use impacts on the environmental fates of organic contaminants in a tropical watershed

Organic contaminants, such as polybrominated diphenyl ethers, dioxins, furans, pesticides, and per- and polyfluoroalkyl substances, have the propensity to cause human and environmental harm, and many of these are currently ubiquitous in the environment. Evaluations of factors influencing the environmental fates and hazard potentials of these organics are accomplished using multimedia models. Climate conditions, land use, and chemical properties are among those factors. In this study, the multimedia model RioShed was used to evaluate the atmospheric long-range transport potential, (LRTPa) overall persistence (Pov), and ten-year compartmental concentrations of some known persistent organic pollutants, as well as some less persistent and more polar current use pesticides, in varying climate and land use scenarios, applied to a tropical watershed, in a developing country. Precipitation changes were more influential on hazard outcomes than temperature changes. However, for all evaluated climate changes, there were consequential increases in at least one hazard potential – LRTPa and/or Pov. For example, when precipitation increased, LRTPa and Pov generally decreased and increased, respectively – the opposite outcome occurred when precipitation decreased. However, when forest proportion in the landscape increased, the effects climate changes were either tempered or countered. These are important findings for the management and control of organic pollutants in tropical regions.