An environmental interface is defined as a surface between two abiotic or biotic systems, in relative motion and exchanging mass, heat and momentum through biophysical and/or chemical processes. These processes fluctuate temporally and spatially. The book first treats exchange processes occurring at the interfaces between atmosphere and the surface of the sea, and atmosphere and land surface. These exchanges include the effect of vegetation, transport of dust and dispersion of passive substances within the atmosphere. Processes at the environmental interfaces of freshwater, such as gas-transfer at free-surfaces of rivers, advective diffusion of air bubbles in turbulent water flows and boundary-layers phenomena in vegetated open channels are also described. Finally, the book deals with the phenomena that affect transport of material to and from the surface of an organism, including molecular and turbulent diffusion. The relevant issues related to mass transfer to and from benthic plants and animals are further considered in detail. The book will be of interest to graduate students and researchers in environmental sciences, civil engineering and environmental engineering, (geo)physics and applied mathematics.