The instantaneous transport of inorganic and organic material in a highly polluted tropical estuary

Abstract

The contribution of the estuarine channel of Recife harbour to the eutrophication of the Recife coastal area was evaluated by quantifying the instantaneous transport of salt, dissolved inorganic nutrients (PO 4 À , SiOH 4 , NO 3 À , NO 2 À and, NH 4 þ ), material in suspension, Chlorophyll-a, pico-nanoplankton and microplankton during the rainy (June 2007) and dry (November 2007) seasons. The results showed that all of the dissolved nitrogenated nutrients, the silicate and the material in suspension had higher concentrations during the rainy season, whereas the phosphate and Chlorophyll-a (both the total and the pico-nanoplankton and microplankton fractions) showed greater concentrations during the dry season. All of the materials considered were exported to the sea except for Chlorophyll-a (pico-nanoplankton and microplankton fractions) during the dry season, when these materials were imported into the area. The total liquid transport in the rainy season was three times higher than that found for the dry season. Silicate represented nearly 85% of the total exported material during the rainy period, whereas during the dry season, phosphate and silicate represented 79% of the total exported material. The stratification and circulation processes indicated a well mixed environment. The water-renewal rate was low, as demonstrated by the input of phytoplankton biomass during November. The area was characterised as eutrophic during the months investigated.

The circulation of the lower Capibaribe Estuary (Brazil) and its implications for the transport of scalars

“…The levels of environmental deterioration have increased during recent decades in response to population growth and local industrial development (PARANAGUÁ et al, 2005), which have compromised the water quality in the estuary. OTTMANN and OTTMANN (1959) presented the very first assessment of the water quality in the estuary, followed many years later by KOENING et al (1995) and, more recently, ANJOS et al (2012) andNORIEGA et al (2013). These authors noted the occurrence, in recent years, of a eutrophic state with high phytoplankton biomass, low transparency and low oxygen concentrations.…”

Influence of river discharge on phytoplankton structure and nutrient concentrations in four tropical semiarid estuaries

“…In tropical and subtropical areas, high fluvial discharge resulting from increased precipitation rates during rainy periods may be one of the major, if not the most important factor for controlling the structure and seasonal dynamics of estuarine phytoplankton assemblages (SASSI, 1991;EYRE, 2000;SAECK et al, 2013) due to its effect on turbidity, salinity, nutrient concentrations and water residence time (BASTOS et al, 2005;NORIEGA et al, 2013;SAECK et al, 2013). Generally, freshwater flow carries nutrients into estuaries and consequently increases their concentrations (EYRE, 2000;EYRE;FERGUSON, 2005).…”