11 resultados para Lisbon Bay
em Université de Lausanne, Switzerland
Resumo:
Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the (210)Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90s, which dismissed catchment erosion and pollution.
Resumo:
How to "bring the [European] Union closer to its citizens" is a vexed and vital problem of European integration. Article 11 TEU on participatory democracy, recently introduced by the Lisbon Treaty, is meant to be part of the solution. The EU Economic and Social Committee has gone so far as to define this provision "a milestone on the road to a people's Europe that is real and feasible". This appears to be an overly optimistic assessment - partly because art. 11 relies heavily on the involvement of civil society organisations, which political science literature suggests is conceptually and/or practically irrelevant to citizen involvement; partly because it largely formalizes participatory practices that have been in existence for years without cognizable effects on citizen participation; and partly because even its most innovative element - the European citizens' initiative (ECI) - does not bring significant changes to the Union's constitutional arrangements in terms of redistributing decision-making power. In addition to that, secondary legislation places significant hurdles on the submission of ECIs and might prevent or delay their becoming a standard democratic practice. This is not to say that art. 11 TEU has no potential at all. Its insertion in the Treaty might provide impetus to rethink and develop past participatory practices, such as horizontal civil dialogue. Moreover, the effects of "popular input" in the form of ECIs on EU institutional dynamics is as yet unknown - and perhaps not negligible, to judge from the keen interest that the European Parliament and other bodies have demonstrated in "appropriating" it as a political asset. Finally, art. 11 raises the stakes of the Union's democratic challenge and might pressure EU institutions to make full use of its potential. Or, if eventually proved inadequate, art. 11 might constitute a constitutional experiment on the way to meaningful forms of direct democracy at EU level.
Resumo:
The low 137Cs activity observed in marine sediments of tropical regions often precludes its use as chronostratigraphic marker. Here we present a study on the use of Pu and Am radioisotopes as alternative markers to constrain the 210Pb ages in a sediment core of the Havana Bay (Cuba). Mean activity ratios of 238Pu/239,240Pu, 241Am/239,240Pu and 241Pu/239,240Pu indicated that the nuclear weapon tests fallout is the main source of the anthropogenic radionuclides. While the inventory of 137Cs in the sediments is lower than the expected fallout inventory, 239,240Pu accumulates in the sediments with inventories higher than the expected fallout inventory. The high fluxes of 239,240Pu are nevertheless corroborated here through use of 210Pb, and confirm that focusing of solid particles is of great importance in the investigated site. 239,240Pu showed to be a useful time tracer in marine sites where the 137Cs signal is very low.