Biomonitoring in the mercury-contaminated Wabigoon–English–Winnipeg river (Canada) system: selecting the best available bioindicator

Several organisms used for biomonitoring in the mercury-contaminated Wabigoon–English River System, Ontario, Canada (sport fish, forage fish, crayfish and others) were examined for their utility as bioindicators. Causes for spatial and temporal variability in mercury concentrations in biota are reviewed. The significance of intertrophic and intratrophic biotic relationships is evaluated on both a site-specific and intersite basis. Larger mature fish are the most effective integrators as these organisms are the most buffered from site-specific and seasonal variations in mercury concentrations and bioavailability. Where there are no physical barriers preventing movement of biota between contaminated and uncontaminated parts of the watercourse, younger, smaller organisms can better - ical zones of contamination because of their restricted range. Because many organisms can provide information on mercury contamination, the choice of the most suitable indicator depends upon the purpose of the study, the pharmacokinetics of mercury uptake by the organisms in question, and the chemodynamics of methyl and inorganic mercury species in the field.     

Effects of airborne fluoride on soil and vegetation

The study was initiated by the sudden uncontrolled release of airborne fluorides in 2005 into the environment from aluminium smelter factory that caused damage of vegetation. Samples of corn leaves and corn male flower heads with visible symptoms of fluoride intoxication had been collected in autumn 2005. Increased contents of total fluoride, which exceeded the maximum allowable content of fluorine in feeding stuffs, including meadow grass, were detected. During continuation of the study some commercially available herbal teas and plants used for preparing herbal teas infusions, collected in the field in 2010, were investigated to investigate possible uptake of fluoride from the soil. Nettle (Urtica dioica) has been found to be a promising passive bioindicator for monitoring phytotoxic effects of fluoride in the soil on the vegetation. Good correlation between labile free fluoride in the soil and total fluoride in the nettle has been found, while total fluoride in the soil, soil pH and the dominant wind direction were also proven as important factors influencing the uptake of fluoride by the nettle.