Patrícia Catarina Sanches de Carvalho

Potential risk assessment in stream sediments, soils and waters after remediation in an abandoned W>Sn mine (NE Portugal)

The mining complex of Murçós belongs to the Terras de Cavaleiros Geopark, located in Trás-os-Montes region, northeast Portugal. A stockwork of NW-SE-trending W>Sn quartz veins intruded Silurian metamorphic rocks and a Variscan biotite granite. The mineralized veins contain mainly quartz, cassiterite, wolframite, scheelite, arsenopyrite, pyrite, sphalerite, chalcopyrite, galena, rare pyrrhotite, stannite, native bismuth and also later bismuthinite, matildite, joseite, roosveltite, anglesite, scorodite, zavaritskite and covellite. The exploitation produced 335t of a concentrate with 70% of W and 150t of another concentrate with 70% of Sn between 1948 and 1976. The exploitation took place mainly in four open pit mines as well as underground. Three lakes were left in the area. Remediation processes of confination and control of tailings and rejected materials and phytoremediation with macrophytes from three lakes were carried out between 2005 and 2007. Stream sediments, soils and water samples were collected in 2008 and 2009, after the remediation process. Most stream sediments showed deficiency or minimum enrichment for metals. The sequential enrichment factor in stream sediments W>Bi>As>U>Cd>Sn=Ag>Cu>Sb>Pb>Be>Zn is mainly associated with the W>Sn mineralizations. Stream sediments receiving drainage of a mine dump were found to be significantly to extremely enriched with W, while stream sediments and soils were found to be contaminated with As. Two soil samples collected around mine dumps and an open pit lake were also found to be contaminated with U. The waters from the Murçós W>Sn mine area were acidic to neutral. After the remediation, the surface waters were contaminated with F(-), Al, As, Mn and Ni and must not be used for human consumption, while open pit lake waters must also not be used for agriculture because of contamination with F(-), Al, Mn and Ni. In most waters, the As occurred as As (III), which is toxic and is easily mobilized in the drainage system. The remediation promoted a decrease in metals and As concentrations of soils and waters, however the applied processes were not enough to rehabilitate the area.

Metal and metalloid leaching from tailings into streamwater and sediments in the old Ag–Pb–Zn Terramonte mine, northern Portugal

Tailings deposited over the Castanheira, a stream which flows through the old Ag–Pb–Zn Terramonte mine area, showed a great potential environmental risk due to sulphide weathering, facilitated by the tailings–water interaction. The high concentrations of Al, Fe, Pb and Zn in the tailings are associated with the exchangeable, reducible and sulphide fractions and suggest sphalerite and pyrite occurrences. Oxidation of pyrite is responsible for the low pH values (3.38–4.89) of the tailings. The water from the Castanheira stream is not suitable for human consumption due to high concentrations of SO42−, Mn, Al, Cd, Ni, and Pb. The lowest concentrations of metals and metalloids were detected in downstream stretches of the Castanheira. However, As, Fe and Zn in deeper sediments tend to increase downstream. Significant concentrations of trivalent forms of arsenic were detected in water samples. In downstream stretches of the Castanheira, some free ions (Fe2+, Mn2+ and Zn2+) also predominate and the water is saturated with ferrihydrite, goethite, hematite, lepidocrosite and magnetite.

Eficácia da promoção da saúde oral no controlo do biofilme bucal

Objective: To assess the efficacy of oral health instructions, particularly in the control of dental plaque, as well as assess the effectiveness of the reinforcement of the same instructions. Methods: A quasi-experimental study was conducted at the University Clinic of the Portuguese Catholic University (UCP) in Viseu-Portugal from January to June 2012. Three different assessments were performed with 30 participants using the O’Leary Plaque Index and a questionnaire on oral health behavior, with a one-month interval between each assessment. In the first assessment, all participants received the same instructions of oral hygiene and the O’Leary Plaque Index registration and the application of the questionnaire were performed; in the second assessment, a new registration of the O’Leary Index was made, but only the experimental group (n=16) received the reinforcement of oral health instructions, and in the third assessment, a new registration of the O’Leary Plaque Index was made for all the individuals (n=30). Results: Both control and experimental groups showed a decrease in the O’Leary Plaque Index, but the latter showed a more significant decrease in the last assessment: 38.19% (n=16) vs. 69.57% (n=14), p <0.05. Regarding the frequency of toothbrushing, in the experimental group, 68.8% (n=11) brushed the teeth at least twice a day, while in the control group only 57.1% (n=8) performed the same frequency of toothbrushing. In this case, statistically significant differences were found between the two groups (p<0.05). Conclusion: Oral health promotion through oral hygiene instruction was effective in improving oral health behaviors, and, consequentely, the control of dental biofilm. doi:10.5020/18061230.2014.p117