Mascarenhas, A.C.C.; Gomes, G.S.; Lima, A.P.Y.; Silva, H.K.N.; Santana, L.S.; Rosário, R.P., and Rollnic, M., 2016. Seasonal variations of the Amazon River plume with focus on the eastern sector. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 532–536. Coconut Creek (Florida), ISSN 0749-0208.
The Amazon Continental Shelf (ACS) is a highly dynamic environment as a result of physical processes (tidal, current and wind) and the large river discharge from Amazon and Pará Rivers. This research aims to determine seasonal variations of the plume of the Amazon River in the eastern sector, near the Pará River mouth. Five oceanographic campaigns were conducted on the ACS: April and October 2013; May, July and October 2014. The sampling line followed the shape of the Cabo Maguari (Marajo Island) to 260 km in the shelf break. Nine vertical profiles of conductivity, temperature and pressure and turbidity were collected. It reaches a perpendicular distance up to 200 km from the coast during period of maximum rivers discharge (April and May). During low river discharge (October 2013 and 2014), the plume was restricted to 30 km and presented relative high levels of salinity (20 PSU). The Coastal Water, characterized by high temperatures and low salinity was limited to about - 15 m deep. The Tropical Surface Water, which is considered a high value of salinity and water temperature, was identified in the last sample point to 260 km from the coast in 2014. This water body characteristics is commonly found in the North Brazil Current, then it can be concluded that water mass invades the Amazon continental shelf. Even in low discharge conditions, adjacent ocean water do not invade the the Amazon River mouth, only the Pará River estuary. Because of that, these estuaries present different physical and biological processes.