ABSTRACT
The ability of freshwater aquatic vascular plants to accumulate heavy metals was examined in some detail during a five year study. Differences in uptake rate were found to depend on the species of plant, the seasonal growth rate changes and the metal ion being absorbed. Lead and mercury were concentrated to a greater extent than the lighter nickel and copper. Laboratory experiments were designed to establish uptake rate constants which were used to calculate water concentrations of mercury from the analyses of plant samples from the river. 'Background' levels of mercury in aquatic plants of 35-50 ng g(-1) dry weight corresponded to a water concentration near 15 ng L(-1) of total mercury of which 25-30% was methylmercury. Higher concentrations of mercury in the plants indicated a proportional increase in the mercury level in the water.
ABSTRACT
Comparative rates of absorption of copper, lead, cadmium, nickel, tin, and inorganic and methylmercury ions from water by Elodea densa were measured. Methylmercury, at relatively low tissue concentrations, was the only ion that quenched the laser-induced fluorescence.
Subject(s)
Metals/metabolism , Plants/metabolism , Absorption , Lasers , Methylmercury Compounds/metabolism , Spectrometry, Fluorescence , Water Pollutants, ChemicalABSTRACT
Rats were dosed once per os with either plant-incorporated or solution-radioactive methylmercury (MeHg). While whole-body retention did not change, the incorporation into some organs was approx. 2.5 X higher when administered Hg was in the plant-incorporated rather than in solution form. The only noticeable change in demethylation occurred in the cerebrum where MeHg:Hg ratios were 79:10 (plant-incorporated MeHg) and 65:24 (solution-MeHg). Between 5 to 7% of the total mercury was excreted in faeces and urine either in the inorganic (faeces) or organic (urine) forms. Mercury levels in mitochondrial and soluble fractions of cerebrum were noticeably lower with plant-MeHg than with solution-MeHg.
Subject(s)
Methylmercury Compounds/pharmacology , Plants/metabolism , Animals , Dealkylation , Feces/analysis , Female , Mercury/metabolism , Protein Binding , Rats , Rats, Inbred Strains , Tissue DistributionABSTRACT
Long-term bone calcium metabolism was measured using a whole body counter apparatus and the radioisotopes calcium-47 and strontium-85. Strontium was given with calcium in a single intravenous injection in order to estimate long-term retention of calcium. Calcium-47, with a short radio-active half-life, was measured directly for 20 days, and then indirectly from strontium retention for periods up to 200 days.The standard parameters of calcium transport were measured and, as well, a new parameter, calcium accretion to the fixed bone pool. These studies were carried out on 13 subjects, six of whom were selected "normals" and seven were patients with osteoporosis. Calcium accretion to the fixed bone pool, the new index of bone formation, varied from 100 to 210 mg. of calcium daily in normal subjects and from 70 to 340 mg./day in patients with osteoporosis. These values are one-third of those for the accretion to the total bone pool, the previously reported bone formation rate.
