Different silicon forms sinalize an input of urbanized river and indicate the presence of phytoplankton with silicon structures in the tropical coastal area of Recife (PE-Brazil)

Autor(es)

Cordeiro Cid Bastos, Ana Teresa ; Braga, Elisabete de Santis

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Journal of Oceanography; v. 66, n. 1, p. 11-pg., 2018-01-01.

Resumo

The urbanized areas mark its presence m the hydrological systems with some biogeochemical signs including silicon inputs.Natural influence of leaching and erosion is done by silicate contribution and sometimes, the agriculturally soil contains microphytoliths and contributes with biogenic silica.Once in the hydrological system, the silicon can integrate the biogeochemical cycles showing a balance or not between inorganic and biological forms that reveals a tendency of processes that occur m each sector of the estuarine-marine interface. This study arms to evaluate the impact of a heavily polluted/urbanized nver, whose input can be evidenced by the contnbution of different forms of silicon that can evidence the tenestnal contnbution, erosion process, the presence of phytoplankton species with siliceous structures, mainly associated to diatoms and also, to study the river plume spreading on the coastal area by undertaking silicon profiles in the region adjacent to the river mouth. The coastal region of Recife is under influence of fluvial inputs from Capibanbe and Beberibe rivers venfied by observed low salinity (min. 33.93). The distnbution of silicon forms showed sectonal vanation, and the maximum values were dissimilar Dissolved silicate reached 14.40 mu mol L-1,lithogenic silicon (LSi) maximum of 25.76 mu mol L (-1) and biogenic silica (BSi) reaching 7.39 mu mol L (-1) near the river mouth toward the sea, evidencing the river influence coming from the west, achieving the port barrier at the end and propagating in the sea toward northeast. Due to higher nutrient availability in the stations nearest to the coast, primary production was encouraged with evidencing by high values of chlorophyll-a associated to silicate (r=0.71) and to BSi (r=0.44). In the stations more distant to the coast, the forms of silicon showed very low concentrations and BSi/ Chlorophyll-a showed negative correlation associated with chlorophyll-a concentrations evidencing the participation of non-silicon actors in the primary production in medium depth in oligotrophic tropical waters. (AU)

• Processo FAPESP: 11/50582-0 - Estudo do equilíbrio do ciclo do carbono na região costeira e de seu potencial transporte oceânico: com ênfase ao litoral de Pernambuco (Carecos)
• Beneficiário: Elisabete de Santis Braga da Graça Saraiva
• Modalidade de apoio: Auxílio à Pesquisa - Temático