Chemical investigations on the hydrographical system of Cananéia lagoon

Abstract

Periodical observations were made in 1958 in the hydrographical system of Cananéia lagoon State of São Paulo. The present paper reports the general characteristics of the regional distribution of chemical constituents in the water of the lagoon as observed on the February 11, 1958. The outer sea water (34 ‰ salinity, 4.5 ml/l O2, pH 8.4, 0.1 µg-atoms-nitrate-N/l, 0.3 µg-atoms-phosphate-P/l and 4 µg-atoms-silicate-Si/l) flows into the lagoon at flood tide through the Barra de Cananéia. The major portion of the inflowing sea water moves westward through the Baía de Trapandé pushing the inner lagoon water toward the northern sheltered region, while a smaller portion enters along the eastern waterway called Mar de Cananéia, but is apparently blocked in its flow because of the narrow passage. In the sheltered inner region the rise of the water level apparently depends upon an accumulation on the water of the tributaries which is blocked by the outer tidal wave. The lowering of the water level of the open sea during the ebb sucks out the lagoon water, and a high velocity of the outflow through the narrow waterway of the Mar de Cananéia is then usually observed. In the inner region of the lagoon when the horizontal movement of the water due to the tides is weakened, a reduction state is likely to develop in the bottom layer on account of active decomposition by bacteria of the deposited organic materials. Accordingly, considerable lowering of the oxygen tension is observed in the water overlying the bottom. In the surface water at the same station the amount of dissolved oxygen is near saturation point. The decomposing activity of the bacteria is very important for the lagoon's metabolism. The return of nutrients into the water undoubtedly contributes efficiently to enrich the phytoplankton crop.

Plankton studies in a mangrove environment: V. salinity tolerances of some planktonic crustaceans

“…This species was found in greatest numbers in the inner parts of the lagoon where the average salinity is relatively low. KATO (1966).…”

“…AlI experiments were performed mainly with adult females of the species studied_ Experimental 1 -Water of salinity of 30%0 was considered as 100% sea-water. Previous results (TEIXEIRA et ai., 1965;KATO, 1966) demonstrated that sea-water of this salinity is more frequent in the entrance of the estuary than water of higher salinity. Therefore the extent to which this water was diluted was considered to be as the gradient that the zooplankton has to support in inshore waters.…”

Estudo dos metais traço (zinco, cádmio e chumbo) em duas regiões do complexo estuarino-lagunar de Cananéia-Iguape(SP) sob diferentes pressões antrópicas

“…Diversos estudos apresentam o complexo estuarino-lagunar de Cananéia-Iguape como eutrófico, rico em nutrientes (Kato, 1966;Tommasi, 1984;Miyao et al, 1986;Braga, 1995;Aguiar, 2005;Barrera-Alba, 2009).…”

“…4.3c). Em Cananéia, Kato (1966) observou valores de oxigênio dissolvido mais elevados do que os encontrados neste trabalho, entre 4,82 e 5,56 mL L -1 . Braga (1995) • Nutrientes (P e Si), Material em Suspensão e Matéria Orgânica em Suspensão…”

Avaliação da influência do canal do Valo Grande na composição molecular e isotópica da matéria orgânica depositada no Sistema Estuarino-Lagunar de Cananéia-Iguape-SP

“…As ondas de maré promovem a mistura das águas oceânicas e fluviais, ocasionando variações na distribuição da salinidade no sistema (Miyao, 1977). Kato (1966) apud Barcellos (2005) (Miranda et al, 1995;Bérgamo, 2000).…”