Trace Metals In Fresh Waters Research Articles

The coagulation, solubility and adsorption properties of Fe, Mn, Cu, Ni, Cd, Co and humic acids in a river water

River water (Water of Luce, Scotland) is used in laboratory experiments designed to investigate physical and chemical properties of Fe. Mn, Cu, Ni, Co, Cd and humic acids in riverine and estuarine systems. Using NaCl, MgCl 2 and CaCl 2 as coagulating agents, coagulation of dissolved (0.4 μm filtered) Fe, Cu, Ni, Cd and humic acids increases in a similar matter with increasing salt molarily: Ca 2+ is the most dominant coagulating agent. Removal by coagulation with Ca 2+ at seawater concentrations ranges from large (Fe-80%. HA-60%, Cu-40%) to small (Ni, Cd-15%) to essentially nothing (Cd, Mn-3%). Destabilization of colloids is the indicated mechanism. Solubility-pH measurements show that between a pH of 3 and 9, Fe, Cu, Ni, Mn, Co and Cd are being held in the dissolved phase by naturally occurring organic substances. Between pH of 2.2 and 1.2 a large proportion of dissolved Fe, Cu. Ni and Cd (72, 35,44 and 36% respectively) is precipitated along with the humic acids; in contrast, Mn and Co show little precipitation (3%). Adsorption-pH experiments, using unfiltered river water spiked with Cu, indicate that adsorption of Cu onto suspended particles is inhibited to a large extent by the formation of dissolved Cu-organic complexes. The experimental results demonstrate that solubilities and adsorption properties of certain trace metals in freshwaters can be opposite to those observed with artificial solutions or predicted with chemical models. Interaction with organic substances is a critical factor.

Chemical modeling of trace metals in fresh waters: Role of complexation and adsorption.

Chemical modeling of trace metals in fresh waters: Role of complexation and adsorption.

Chemical modeling of trace metals in fresh waters: role of complexation and adsorption

Research report:Chemical interactions of trace metals with ligands and surfaces and competition among metals of natural waters are examined by chemical modeling. The response of a body of oxic fresh water that contains four major cations, nine trace metals, eight inorganic ligands, and an adsorbent surface with the characteristics of silicon dioxides is investigated. The distribution of trace metals is assessed as a function of pH, type of additional adsorbing surfaces, surface area, and the presence of selected organic ligands. The speciation and distribution of metals depend on availability of organic ligands and surfaces. Specific conclusions are given for each metal. The modeling of the equilibrium distribution of trace metals is affected not only by the choice of metals, inorganic ligands, and surfaces, but also by the availability and choice of their respective stability constants. (13 graphs, 24 references, 4 tables)

Extraktion der metallionen Cr(III), Fe(III), Co(II), Ni(II), Cu(II) und Zn(II) mit geschmolzenem oxin und bestimmung der extrahierten metalle mit hilfe von röntgenfluoreszenz

The accuracy of the determination by X-ray fluorescence spectrometry of a number of metals in pressed tablets of oxine has been investigated. A procedure is described which has been used for the determination of trace metals in fresh water and in sugar, in which molten oxine is used as the extractant.