Repository logo

Browsing by Author "Armando, Duarte"

Now showing 1 - 2 of 2
  • Mercury cycling between water column and upper sediments in a contaminated area (Largo do Laranjo, Aveiro, Portugal)
    Publication . Ramalhosa, Elsa; Río-Segade, Susana; Pereira, Eduarda; Vale, Carlos; Armando, Duarte
    The fate and reactivity of anthropogenic mercury in aquatic environment is of major concern owing to its toxicity to most organisms and man. In Ria de Aveiro, a chloralkali plant has been discharging mercury during decades into one of the remotest branches. Most of the discharged mercury settles down in Largo do Laranjo, an inner bay of 1.5 km'. Since 80's, several works have identified high mercury concentrations in sediments, suspended particulate matter and water [I, 2, 3]. The highest concentrations of mercury (max. 35 Og g") were found in sediments at 40 cm depth, corresponding to the period of maximum industrial production [2]. However, there is an escape of particulate mercury when surface sediments are resuspended and transported by the tide to the rest of the lagoon [4].
    2004Conference object Open access Show more
  • Simple methodology for methylmercury and inorganic mercury determinations by high-performance liquid chromatography-cold vapour atomic fluorescence spectrometry
    Publication . Ramalhosa, Elsa; Río-Segade, Susana; Pereira, Eduarda; Vale, Carlos; Armando, Duarte
    An analytical methodology was developed to separate and quantify methylmercury (MeHg) and inorganic mercury by high-performance liquid chromatography (HPLC)-cold vapour atomic fluorescence spectrometry (CV-AFS). The use of UV oxidation of the organic forms of mercury, the tin(II) chloride reduction in acidic medium of mercury and the introduction of a water vapour trap based on H2SO4/CaCl2 resulted in a low detection limit (DL) (10 +/- 2 pg, mean value +/- S.D.). The apparatus was operationally optimised through the modified simplex method leading to an increase of the signal by a factor of 2. The method performance has been tested by determining the MeHg concentration in a sediment certified reference material (CRM) and the results were statistically indistinguishable from the certificate value (alpha = 0.05) both for the mean value and S.D.
    2001Journal article Restricted access Show more