Estimating the importance of natural and anthropogenic sources on N and P emission to estuaries along the Ceará State Coast NE Brazil.

The Northeastern semi-arid Brazilian region is experiencing rapid social and economic development based on improving water management and even in areas of low human occupation, anthropogenic emissions of N and P surpass natural emissions in at least one order of magnitude and these additional loads can alter the water quality of the receiving estuaries. This study estimates, using an emission factor approach, the annual emissions of N and P from natural processes and anthropogenic sources for estuaries along the Ceará State, NE Brazil. Emission factors from natural sources are one to two orders of magnitude lower than those for anthropogenic sources. Among the anthropogenic activities, the aquaculture is responsible for most N emission (0.52 t km(-2) year(-1)) followed by waste water and husbandry. For P, the largest average emission factors are from husbandry (0.30 t km(-2) year(-1)), waste water and agriculture.