Enrichments of Zinc, Lead, and Copper in Recent ... - ACS Publications


waters into the sediments. The aim of ... mud-black ooze transition in core LWIN 1 is a primary de- .... water sediments is probably similar throughou...
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stack-collected fly ash samples ( 2 , 4 ) .Also, Ondov et al. (13) have reported on elemental size distribution of impactor samples from the same power plant. The mass median aerodynamic diameters (MMAD) of these elements, with the exception of Cr, ranged from 4.4 to 6.3 pm, while the MMAD of matrix elements ranged from 9.1 to 10.0 pm. I t is possible, however, that the observed concentration enhancement in fine particles is associated with a bimodal distribution. Ondov e t al. (14) have reported bimodal size distributions for Cr, Sb, As, U, Se, and Ba with a broad minimum between 0.5 and 2 pm. The submicron mode (accumulation mode) probably is the result of coagulation of primary particles or the condensation of reaction products as described by Whitby (15). Whitby (15) has demonstrated that the accumulation mode of urban aerosols has an average geometric mean diameter by volume of 0.34 pm, in agreement with the findings of this study. Similarly, Kanapilly et al. (16) have produced, by varying the rate of vaporization, submicron aerosols of YzO3 with mass median diameters ranging from 0.1 to 0.3 pm. These data provide insight into the solubility and concentration size dependence of fly ash components. The solubility behavior and fine particle contribution to the elemental concentrations of filtrates may be classified into four basic categories: solubility with and without insoluble fine particle contribution, fine particle contribution without detectable solubility, and no detectable elemental concentration in the filtrates. The results of this study indicate that (a) the elements Mo, Ca, Se, Ba, Na, Co, Sb, As, Zn, W, and Cr are relatively soluble a t physiological p H and therefore may be soluble upon deposition in lung fluid; (b) a relatively large proportion of the mass of Sb, As, Zn, w, Cr, and U is associated with particles of go% of the total concentration) associated with the labile fraction a t all depths, whereas Fe is associated mainly with the resistate fraction (range = 47-77%, mean = 60% of the total concentration). Chlorite is probably the main Fe source. The elevated Fe and Mn levels in the oxidized, surface sediments may in part reflect the well-known recycling of the metals associated with redox changes. The brown mud underlying the black ooze also appears to have been laid down under oxidizing conditions (17),but in contrast this sediment was not subjected to reducing conditions on burial. The variable concentrations of the elements in the brown mud probably reflect changes in deposition rate of the various components rather than any diagenetic process. Zn, P b , and Cu exhibit similar profiles to that of S being enriched in the black ooze compared to the underlying brown mud. Intermediate concentrations exist in the surface oxidized layer. A t depth the concentrations fall to near constant values of 160 ppm of Zn, 56 ppm of P b , and 24 ppm of Cu, which are taken as baseline concentrations. The leaching experiments show that the concentrations associated with the resistate fraction are more or less constant a t all depths with mean values of 37 ppm of Zn, 12 ppm of Pb, and 13 ppm of Cu. Thus, even where the metals are a t their baseline levels, the labile fraction constitutes as much as 80%of the Zn and P b and 50% of the Cu. The enrichment of P b above its baseline concentration occurs (in both cores) within the brown mud deposit rather than a t the transition with the black ooze. Forstner (18) gives average background concentrations for pelitic lacustrine sediments of 123 ppm of Zn, 46 ppm of Cu, and 31 ppm of P b and ranges which include the Windermere baseline values for all three metals. In contrast, the maxima in the black ooze are Volume 13, Number 6, June 1979

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Table II. Fluxes of Heavy Metals into Windermere Together with Comparable Data from Other Localities locality

Windermere

Lake Eried California coast e a

This study.

sedimentary,a precultural present-day, natural present-day, anthropogenic maximum anthropogenic atmospheric, total deposition for 1971 sedimentary, natural anthropogenic sedimentary,natural for 1970 anthropogenic for 1970

Hg fluxescalculated from t h e data

rate, p g m n - 2 . y r - l Pb cu

Zn

type

1.9 7.5 16.9 47.9 12.0 6.5 -52.6 10.9-113.1 2.8-9.7 1.9-2.2

0.7 2.6 9.9 25.1

5.5 1.6-16.4 5.4-44.3 0.23-1.0 0.9-2.1

0.3 1.2 1.8 2.8 3.2 1.9-16.3 2.6-13.0 1.0-2.6 1.1-1.4

Hg

0.001 0.005 0.049 0.049