Data/hora: 01/06/2024 18:19:08

Provedor de dados: | Gayana
País: | Chile
Título: | Oxygen depletion in the gulf of Mexico adjacent to the Mississippi river
Autores: | Rabalais,Nancy N.
Data: | 2006-10-01
Ano: | 2006
Palavras-chave: | Anoxia; Hypoxia; Eutrophication; Nutrients; Nitrogen.
Resumo: | The seasonal formation of a bottom-water layer severely depleted in dissolved oxygen has become a perennial occurrence on the Louisiana continental shelf adjacent to the Mississippi River system. Dramatic changes have occurred in this coastal ecosystem in the last half of the 20th century as the loads of dissolved inorganic nitrogen tripled. There are increases in primary production, shifts in phytoplankton community composition, changes in trophic interactions, and worsening severity of hypoxia. The river-influenced continental shelf is representative of similar ecosystems in which increased nutrient flux to the coastal ocean has resulted in eutrophication and subsequently hypoxia. The hypoxic conditions (dissolved oxygen less than 2 mg L-1) cover up to 22,000 km² of the seabed in mid-summer. Dissolved oxygen concentrations seldom decrease to anoxia, but are often below 1 mg L-1 and down to 0.5 mg L-1. The biogeochemical processes of oxic versus suboxic conditions in the water column and sediments of the Louisiana shelf are similar to other areas of oxygen deficiency. However, the suboxic conditions in the Gulf of Mexico are less persistent in time and space, and anoxia at the seabed is not common or long-lasting.
Tipo: | Journal article
Idioma: | Inglês
Identificador: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300015
Editor: | Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción
Formato: | text/html
Fonte: | Gayana (Concepción)  v.70 suppl.1 2006