Provenance (geology) to determine the origin of sediments. This is often used in conjunction with the study of exhumation histories, interpretation of drainage networks and their evolution, and forward-modelling of paleo-earth systems. In combination, these help to characterise the "source to sink" journey of clastic sediments from hinterland to sedimentary basin. Provenance (from the French provenir, "to come from"), is the place of origin or earliest known history of something. In geology (specifically, in sedimentary petrology), the term provenance deals with the question where sediments originate from. The purpose of sedimentary provenance studies is to reconstruct and to interpret the history of
Issues relating to biofuels ecosystems including rainforest in South America. In forest ecosystems, these effects themselves will undermine the climate benefits of alternative fuels, in addition to representing a major threat to global biodiversity. Although biofuels are generally considered to improve net carbon output, biodiesel and other fuels do produce local air pollution, including nitrogen oxides, the principal cause of smog. Issues relating to biofuels There are various social, economic, environmental and technical issues with biofuel production and use, which have been discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, poverty