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Sediment denitrification rates in the Pardiela brook, a temporary tributary of the Guadiana River

Ano
2005
Abstract

Climate change caused by global warming is expected to further alter the flow regimes of both regulated and unregulated rives Furthermore, the land use and the increase of areas affected by desertification in the Southern Europe will affect water dynamic in catchments containing dense network of temporary waters. The mechanisms by which hydrologic regimes influence ecosystem from and function is not well understood however, is consensus regarding the importance of both wet and dry periods in maintaining ecosystem integrity. Nutrient cycles in aquatic systems are dependent of three interrelated factors: the oxygen status of the environment, the mineralogy of the environment and microbial populations present. Sediment denitrification rates were determined as the flux of N2 from intact sediment cores collected at Degebe river affluent sediments (Pardiela) according to the technique developed by Seitzinger et al., (1980) and modified by Nowicki (1994). The lack of rain in the six months before the February essay, contributes to a small (i.e., 0.583 m) Pardiela water column depth which means a higher surface-to-volume ratio than in rainy weather and this could promote the uptake and removal processes of nitrogen in the sediments and at the same time, sediments did not revealed a deep oxic layer, which could also favours the downward flux of NO3- to the anoxic denitrification zone. The magnitude of NO3- flux into the sediments is more than sufficient for the denitrification rates obtained; however, denitrification represents only a small percentage of this influx. Our results suggested that a large percentage of the NO3- flux into the sediments was not denitrified as indicated by the N2/NO3- ratio but probably also reduced to NH4+ or assimilated and therefore conserved within the system.

Palavras Chave

Denitrification; Nitrogen cycle; Temporary rivers.

Tipo de Apresentação
Comunicação oral
Tipo de Revisão
Nacional
Âmbito Geográfico
Nacional
Situação
Publicado
Área de Trabalho
Referência

Lança, M.; Mira, F.; Bettencourt, A. (2005). Sediment denitrification rates in the Pardiela brook, a temporary tributary of the Guadiana River. Reunião Anual do IMAR ..Funchal, Portugal.