RESUMO.O estuário do rio Pará representa um sistema complexo e peculiar, com processos físicos de micro e mesoescala gerados por forçantes de diferentes fontes (por exemplo, as marés astronômicas e a descarga fluvial). No presente estudo, as principais componentes semidiurna (M2) e de água-rasa (M4) são analisadas para quantificar graus de distorção e identificar assimetrias no estuário do rio Pará. Dois medidores de maré foram fundeados. Um na margem direita (ponto #RG) e outro na margem esquerda (#LF), durante 6 meses (Setembro de 2014 à Março de 2015). Além disso, foram utilizadas cartas harmônicas da Fundação de Estudos do Mar (FEMAR). Variações laterais foram identificadas entre #RG e #LF de acordo com as cartas cotidais de amplitude e fase, com defasagem de aproximadamente 10 minutos e variação de 2 cm na amplitude. Verificamos que a onda de maré entra pelo sistema pela margem direita (#RG). Os resultados indicaram graus de distorção maiores que 10% e assimetria positiva da onda de maré, sendo que a atenuação da maré no estuário pode ser maior que 400 km estuário acima ao longo da bacia de drenagem. ABSTRACT. The Pará River estuary is a complex and special system in amazon continental shelf, with micro and mesoscale physical processes generated by forces of different sources (e.g., astronomical tides and river discharge). In this study, the main semidiurnal (M2) and the overtide (M4) components were analyzed by quantifying distortions degrees and identifying tidal asymmetries in the Pará River estuary. Two submersible tidal gauges were moored to measure the water level. One on the right margin (point #RG) and another on the left margin (#LF) recorded measurements 6 months (from September 2014 to March 2015). Furthermore, we used harmonic charts from Marine Studies Foundation (FEMAR, Fundação de Estudos do Mar). Lateral variations were also identified between #RG and #LF points from the amplitude and phase cotidal charts, with about 10 minutes delay and variation of 2 cm in tidal amplitude. We verified that the tidal wave enters in system by the right margin (#RF). The results show distortion degrees higher than 10% and positive asymmetry of the tidal wave in the Pará River, and the tidal attenuation in the estuary may be greater than 400 km upstream along the drainage basin.

The Suape coastal zone has suffered since the 1980s the effects of anthropogenic action due to the construction of the industrial complex of Suape. This work aimed to evaluate the environmental conditions and possible eutrophication processes of the area. Six campaigns were carried out, three in the dry season (November 2015, January and April 2016) and three in the rainy season (July 2015, July and August 2016). Water samples were collected at the surface during low tide and high tide, in neap tides. Salinity ranged from 19.75 to 37.20, the dissolved oxygen rate ranged from 61.75 to 125.90% and chlorophyll-a from 0.02 to 3.48 mg m−3. Water transparency, temperature, nitrate and silicate presented significant seasonal variation, the concentrations of nutrients being higher in the rainy season and the others in the dry season. Water transparency, salinity, dissolved oxygen saturation and chl-a <20 µm showed significant differences for tide, being higher at high tide, and at low tide for chl-a of <20 µm. The low content of dissolved inorganic nutrient salts and chl-a were indicative of an area still free of eutrophication. Anthropogenic changes in the environment have led to greater marine interference and consequently to a reduction of the productive capacity of the system.