A study on the physico-chemical speciation of heavy metals in waters of rivers, and lakes in the Changjiang River Valley, China
In the aquatic system, heavy metals always exist in a number of physico-chemical forms: particulate (Cp), soluble which consists of labile (MALI) and bound (inorganic MAb and organic MLb). The environmental behaviors of a metal are critically dependent on these forms. In this paper, the forms of heavy metals in waters from the Changjiang River source to mainstream and lakes were determined by ASV method. The main results are as follows: 1. The total contents (Ct) of Zn, Pb, Cu and Cd in the source were 4.0, 1.88, 1.28 and 0.07 (μg/L) respectively, while Ct (μg/L) in the mainstem were in the order of Zn (20.1) > Cu (14.9) > Pb (6.73) > Cd (0.15). Ct (μg/L) in Dianchi Lake were Zn (7.2) > Pb (0.72) > Cu (0.53) > Cd (0.05), and in Poyang Lake were Zn (12.5) > Pb (4.2) > Cu (3.4) > Cd (0.05), and in Poyang Lake were Zn (12.5) > Pb (4.2) > Cu (3.4) > Cd (0.05). However, most of them were presented as Cp. Their dissolved contents (Cs, μ/L) were lower. 2. The distribution of soluble forms was related to the type of metal and to environmental variables. In general, Zn and Cd have a tendency to be present in MALi, Pb in MAb and Cu in MLb.
Variability of dissolved trace metals in the mississippi river
Abstract The concentrations of eight dissolved trace metals were measured in the lower Mississippi River seven times at various flow stages during a two-year interval. Using trace metal sampling and analysis techniques demonstrated to be reliable, these metals are shown to occur at levels lower than frequently reported. There are systematic relations between the metals and discharge which can serve as predictors of metal variability. Anthropogenic contributions cannot be assessed accurately from these data but do not appear to cause the concentrations of most of these metals to be significantly higher than observed in less disturbed systems, with the possible exception of Ni and Cd.
The chemical mass balance of the amazon plume—II. Copper, nickel, and cadmium
Trace element samples spanning the salinity range were collected in the Amazon plume in June 1974 and 1976. In 1976, laboratory mixing experiments using unfiltered river water and seawater were undertaken. The studies show that copper and nickel are unreactive in the Amazon plume on a time scale of a few days: in both field and laboratory studies the elements are related linearly to salinity, so that neither adsorption and precipitation not desorption reactions significantly alter the net flux of these elements. The 1974 field data indicate there may be up to 25% removal of copper, probably biologically, although a conservative interpretation could be entertained if systematic deviations from the resulting copper-salinity plot are ignored. Cadmium behavior was not clearly defined. There is some indication of desorption, and the estuarine data can be used to set an upper limit on the net flux. The net effective contribution of the elements to the ocean from the Amazon is copper, 24 nmol kg−1; nickel, 4 to 5 nmol kg−1; and cadmium, <0.1 nmol kg−1.