R&D News (continued) Mercury in Inland Waters
thiosulfate (for methylmercury). Detection limits of 0.1 ng/1 were
National Research Council scient
ists T. Kauri and A. Kudo,together with a colleague from Italy, deter mined the proportion of methylmercury to the amount of total mercury in river and lake water samples from the Ottawa Valley. The results published in Water Research showed that a relatively constant equilihrium between organic and inorganic mercury has been main tained over the last decade. A sim
ple method to determine both organic and inorganic mercury in natural waters was developed. This involved
initial
extraction
with
dithizone-chloroform followed by back extraction with aqueous solu tions of sodium nitrate (for inor
ganic mercury) and sodium
achieved.
Adsorption of Phosphate on River
Sediment Distribution in Rivers
Sediments
In a joint research study, Wilfrid Laurier University scientist M. Stone and National Water Research Institute's A. Mudroch collected sed
iment samples from two Lake Erie tributaries and separated them into ten particle size fractions. The con centrations of major elements, organic and inorganic carbon, mineralogical composition, and the
capacity for adsorption/desorption of inorganic phosphate were deter mined for each particle size fraction. The results presented in Environ-
EMPLOYMENT SOUGHT Chemical Engineer (AREO), cur rently employed, is seeking a
position in the Mississauga/Toronto area that provides a profes sional challenge, i have 10 years
experience In project manage ment/marketing in the environ
mental Technology Letters indi cated that the chemical composition and mineralogy were parameters controlling adsorption of phos phates on sediment particles.
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Natural Water Research Institute
scientists E.D. Ongley and E.G. Krishnappan and their Inland Waters Directorate colleague T.R. Yuzyk have examined the degree to which near-surface samples of silt and clay in rivers are representative of the vertical and cross section of
water columns. As reported in a paper accepted for publication in Water Research, surface samples of silt plus clay tend to underestimate the vertical mean concentration by less than 10%. The individual verti
cal distributions of clay and silt dis
play inconsistent and variable patterns of concentration with depth. A theoretical basis for the observations is provided together with a discussion of assumptions which render theory imprecise for
fine-grained cohesive sediment. For more Information, contact Dr. H.R. Elsenhauer, Canadian Associa tion on Water Pollution Research and
Control, Conservation and Protec tion, Environment Canada, Ottawa, ON K1A 0H3,(819) 994-5424.
Please reply to Box 10, Environmental Science & Engineering 10 Petch Or., Aurora, Ontario L4G 5N7
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Environmental Science & Engineering, December 1989