INVESTIGADORES
ONDARZA Paola Mariana
artículos
Título:
SEDIMENT AND POLLUTANT DISTRIBUTION ALONG THE NEGRO RIVER: PATAGONIA, ARGENTINA.
Autor/es:
ISLA F.I.,; MIGLIORANZA K.S.B.; ONDARZA P.M.; SHIMABUKURO V.M.,; MENONE M.L.,; ESPINOSA M; QUIROZ LONDOÑO O; FERRANTE A; AIZPÚN J.E.; MORENO V.J.
Revista:
The International Journal of River Basin Management
Editorial:
Taylor & Francis
Referencias:
Lugar: London, England; Año: 2010 p. 111 - 114
ISSN:
1571-5124
Resumen:
The Negro River extends from the Andes to the Atlantic Ocean supplying water to several cities and to the most important fruit-bearing productive region of Patagonia. Floodplains from the upper valley are artificially irrigated with water delivered from the main channel. Pesticides are increasingly used without a strict government control. Dams constructed at the tributary rivers retained sediment and therefore the clean water delivered used to erode some levees during high discharge events. Bedload-transport fraction (sand dunes) increases at the Upper Valley and is fixed at the levees of the Lower Valley by riparian vegetation. This riparian vegetation is dominated by Salix humboldtiana while Spartina sp is abundant at the estuarine marsh area. Organochlorine compounds (OCCs) were measured by GC-ECD including DDT, DDE, DDD,endosulfans (a-, b-, and sulphate), Hexachlorocyclohexanes (HCH) and chlordanes. OCCs were preferentially accumulated at the Upper Valley in relation to the agricultural activities developed. The dominance of DDE and the parental endosulfan can be explained by their past and current use, respectively. PCBs (different congener groups)showed low levels as consequence of chronic pollution related to the mud fraction. The high concentration in pollutants at the Upper Valley is significantly reduced to the Middle and Lower Valleys. At the estuary very low OCCs levels were measured probably due to the dilution induced by mesotidal dynamics. The sedimentation rate of the lower flooplain is of 1 mm/yr. The bottom of the main channel is dominated by 2D sand dunes. At the inlet, a sandy gravel bank is composed of megaripples 0.5 m high. The estuary stratifies with variations of salinity (up to 10 practical salinity units), and temperature (2 °C) in depth. Tidal currents guarantee the stability of the inlet, and particularly the asymmetric flood-tidal delta. Wwave action induces a net longshore sand transport towards the north.