El rol del fitoplancton en los procesos biogeoquímicos en estuarios

In book: Proceso Químicos en Estuarios, Publisher: Editorial de la Universidad Tecnológica Nacional.-edUTecNe, Editors: Marcovecchio, J. & Freije, R. H, pp.172-196
291 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Contamination by butyltin (BTs) and organochlorine compounds (OCs) in green mussels collected along the coastal areas of Thailand, Philippines and India during the period of 1994–1997 was examined. The BT residues in green mussel were widely detected, suggesting a widespread contamination along the coastal waters of Asian developing countries. Relatively high concentrations of BTs in green mussel were found in high boating activity and coastal aquaculture areas, implying the usage of TBT as a biocide in antifouling paints used on boat hulls and marine aquaculture facilities. The composition of BT derivatives in mussel was in the order of TBT>DBT>MBT, suggesting also the presence of significant butyltin source in Asian coast. BT residues pattern in green mussels from Thailand revealed higher levels in aquaculture than in boating activity sites. This result may indicate that the developing countries showing high economic growth rate (like Thailand) tend to increase the usage of TBT for aquaculture activities. BT contamination levels in Asian developing countries were lower than those in developed nations. However, considering the fact that the unregulated usage of organotins in Asian developing countries and the increasing demand for antifouling paints in Asia–Pacific regions, BTs contamination in aquatic environment may be serious in future. Concentrations of OCs detected in green mussels were lower than BTs. Considerable residues of p,p′-DDT found in mussel indicated the current usage of DDTs in Asian regions. HCHs and DDTs contamination in India is apparently higher than in other Asian developing countries. The present study clearly indicates that the aquatic environment in Asia–Pacific regions is still being contaminated by some OCs. To our knowledge, this is a first report on the detection of butyltin compounds in green mussels (Perna viridis) from Thailand, Philippines and India.
    Ocean & Coastal Management 01/2000; 43(8-43):819-839. DOI:10.1016/S0964-5691(00)00060-0 · 1.75 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Large herbivores can affect the carbon cycle in boreal forests by changing productivity and plant species composition, which in turn could ultimately alter litter production, nutrient cycling, and the partitioning between aboveground and belowground allocation of carbon. Here we experimentally tested how moose (Alces alces) at different simulated population densities affected belowground respiration rates (estimated as CO2 flux) in young boreal forest stands situated along a site productivity gradient. At high simulated population density, moose browsing considerably depressed belowground respiration rates (24-56% below that of no-moose controls) except during June, where the difference only was 10%. Moose browsing depressed belowground respiration the most on low-productivity sites. Soil moisture and temperature did not affect respiration rates. Impact of moose on belowground respiration was closely linked to litter production and followed Michaelis-Menten dynamics. The main mechanism by which moose decrease belowground respiration rates is likely their effect on photosynthetic biomass (especially decreased productivity of deciduous trees) and total litter production. An increased productivity of deciduous trees along the site productivity gradient causes an unequal effect of moose along the same gradient. The rapid growth of deciduous trees may offer higher resilience against negative effects of moose browsing on litter production and photosynthate allocation to roots.
    Ecology 10/2009; 90(10):2724-33. DOI:10.1890/08-1662.1 · 4.66 Impact Factor
Show more