Transformação ambiental de um estuário industrializado no século XIX: o registo sedimentar de Avilés (Asturias, N Espanha)

ABSTRACT: The Avilés estuary is one of the most important industrial ports in northern Spain, whose natural characteristics have been largely altered since the 1830s. Here, the environmental transformation of this estuary during the 19th century is explored using a multi-proxy approach including benthic foraminiferal content, sedimentology (grain-size), trace metals and short-lived radionuclides (210Pb and 137Cs) analysed from a 50-cm-long sediment core and a surface sample collected from the middle part of the estuary in the Pedro Menéndez Channel. The obtained results provide evidence that indicate an evolution from a naturally-driven environment with high a marine influence towards a more restricted setting under brackish conditions. The observed environmental change is interpreted as being mostly derived from physical modifications linked to the marsh reclamation and channelling starting in 1833 and intensified since 1860. This study provides a preindustrial environmental reference framework for future studies in coastal areas of the NW Atlantic Iberian margin.RESUMO: O estuário de Avilés é um dos portos industriais mais importantes do norte de Espanha, cujas características naturais foram bastante alteradas desde 1830. A transformação ambiental deste estuário durante o século XIX é estudada usando uma abordagem multi-proxy incluindo foraminíferos bentónicos, sedimentologia (dimensão do grão), metais traço e radionuclídeos de vida curta (210Pb e 137Cs) analisados a partir de sedimento de um testemunho de sondagem com 50 cm de comprimento e uma amostra recolhida à superfície na parte média do estuário do Canal de Pedro Menéndez. Os resultados obtidos fornecem evidências que indicam evolução de um ambiente com elevada influência marinha para um ambiente mais restrito em condições salobras. A alteração ambiental observada é interpretada como resultado de modificações físicas ligadas à recuperação e canalização de pântanos a partir de 1833, e intensificada desde 1860. Este estudo fornece um exemplo de referência ambiental pré-industrial para estudos futuros em áreas costeiras da margem NW Ibérica do Atlântico.info:eu-repo/semantics/publishedVersio

Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin

An analysis of geomorphic system`s response to change in human and natural drivers in some areas within the Rio de la Plata basin is presented The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers Study areas of different size, socio-economic and geomorphic conditions have been selected: the Rio de la Plata estuary and three sub-basins within its watershed Sediment cores were extracted and dated ((210)Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface Data on river discharge were also gathered Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the Sao Paulo metropolitan area Rates in the estuary are somewhere in between It appears that there is an intensification of denudation/sedimentation processes within the basin. Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes It appears that a marked increase in denudation, of a ""technological"" nature, is taking place in this basin and leading to an acceleration of sediment supply This is coherent with similar increases observed in other regions (C) 2010 Elsevier B V All rights reservedPlan Nacional de I+D+I, Ministerio de Educacion y Ciencia, Spain[CAMGEO]Plan Nacional de I+D+I, Ministerio de Educacion y Ciencia, Spain[CGL2006-11431]Universidad de Cantabria (Spain)Universidad Nacional de La Plata (Argentina)Universidade de Sao Paulo (USP, Sao Carlos, Brasil)MEC, Spai