| مستخلص: |
ABSTRACT Peixoto, H.J.C.; Baia, L.P.; Pereira, D.R.; Rollnic, M., and Monteiro, S.M., 2018. Sedimentological Sectorization Model in an Amazonian Estuary. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 91–95. Coconut Creek (Florida), ISSN 0749-0208. The aim of this study is to check whether a macro tide-dominated Amazonian estuary might be separated in sectors according to recent sediment distribution, considering local hydrodynamics. The case study was conducted in the river Mojuim estuary (−0.72° and −48.00°), situated between the Pará River mouth and the Atlantic Ocean, northeastern Pará, Brazil. A total of 117 superficial sediment samples were collected using a Van Veen dredge in the lower estuary (16 km). Stations are equidistant and encompass margins and estuarine channel. We performed a sieving granulometric analysis and a calcination analysis of total organic matter and total calcium carbonate content (360° and 1000° C, respectively). Were used a multivariate statistical treatment to separate the estuary in sectors, with clustering analysis and principal component analysis (PCA). Recent sediment distribution of the river Mojuim estuary is characterized by fine, platykurtic, and poorly selected sediments (0.63–125 mm) with low organic matter content (5.8% ±0.30) and carbonate (2.4% ±0.04). The river Mojuim estuary is divided in three sedimentation subenvironments: 1) marine domain, located in the estuary mouth, with predominance of moderately selected sandy sediment, where reworking and sedimentary distribution are influenced by tidal currents; 2) river estuarine domain, with predominance of poorly selected muddy sediment, where sedimentation is influenced by river discharge; and 3) a transitional sector with sediments typical of both environments. The Mojuim estuary might be divided in sectors according to recent sedimentary distribution, However, it differs from classic model as it has: 1) a mixed mouth, where the East channel has marine characteristics (93%) and the West channel has transitional (20.7%) and freshwater characteristics; 2) widespread distribution of CaCO3 throughout the estuary, with higher contents in the freshwater zone. Supplementary hydrochemical analyses are required to understand the processes that define these differences in the sedimentological sectorization of Amazon estuaries. [ABSTRACT FROM AUTHOR] |
Full Text Finder