Element enrichment

Since the majority of the elements in surface dust arise from deposited aerosol and added soil it is not surprising to find strong linear relationships between the concentrations of the elements in an atmospheric dust and street or house dust. This is illustrated by the two examples given in Fig. 8 for remote house dust vs urban atmospheric dust and street dust vs rural atmospheric dust. As discussed above crustal/soil material is a major component of atmospheric dust and the soil based elements in the atmospheric dust are Al, Ca, Fe, Mg, Mn, Ni, K, Si and Ti. The elements As, Br, Cd, Cl, Co, Cu, Pb, Rb, Se, V, and Zn are, on the other hand, enriched in atmospheric dust. The same elemental distribution applies to surface dust, but in this case their concentrations (compared on a mass basis) are reduced presumably due to dilution with soil. However, the elements enriched in the atmosphere remain enriched in the surface dusts. 

Elements enriched into Kuroko and midoceanic ridge ores (Shikazono, 1988)... 

Elements enriched into Ktrroko Elements enriched into MORB... 

Shikazono, N. (1988) Difference in elements enriched into Kuroko and ridge hydrothermal ore deposits. Ocean Science, 20, 217-222 (in Japanese). 

Figure 2.3. Elemental enrichment factors in baterial and fungi, plotted on a log scale against the ionic potential of the elements (after Banin and Navrot, 1975. Reprinted from Science, 189, Banin A. and Navrot J., Origin of Life Clues from relations between chemical compositions of living organisms and natural environments, pp 550-551, Copyright (1975), with permission from AAAS)...

Elemental enrichment factors in soils, plotted on a log scale against the ionic potential of the elements. 

It is important to note that we have tried to avoid carbon-rich stars, because they have a rich molecular line spectrum, mostly CN, CH and C2, obliterating many interesting atomic lines of rare elements. This is why we had in our sample a star, CS 31082-001, in which we were able to measure the 385.97 nm line of U II, whereas in the similar r-process element enriched star CS 22892-052, but carbon rich, a CN line obliterates the U II line. 

Although not part of soil, lichens, by virtue of their solubilising action on rocks, contribute to the elemental enrichment of soil. Several studies have identified lichen acids as complexing agents for the iron and aluminium of rocks (95, 96). An examination of the various structures indicates that the basic structure responsible for the chelation is the carboxylic acid group with an orthophenolic group. Grodzinskii (97) has found lichens to be intense accumulators of elements in the uranium-radium, actinouranium and thorium orders. 

It is apparent from our pXRF analyses that at the scale of the analytical window, there are regular, reproducible, variations in element enrichments between sulfide accumulations (nodules, concretions, crusts) and shale matrix. Some of the largest base metal and associated element contents measured in the field (e.g. Zn = 1.4 wt% Cu = 600 ppm Mn = 1 wt% Cd = 90 ppm Hg = 50 ppm) are in apparently (to the naked eye) sulfide-free shale. The majority of such enrichments appear to be due to the incorporation of disseminated, very fine-grained, Fe-rich sphalerite. In many instances this is not evident even when using a hand lens, and care must be taken not to overlook these cryptic enrichments. 

Key indicators of alteration and proximity to ore are increased K2O (particularly in the shale component) near complete loss of Na20 increased FeO (particularly in the siltstone-sandstone component) and increased CO2 in shale. These changes reflect the development of iron carbonate (siderite and ankerite) by carbonate introduction and some alteration of existing calcic carbonate in siltstone-sandstone samples. Destruction of albite, absence of chlorite and increased abundance of muscovite due to potassic alteration, are the other major mineral alteration effects in the altered host rocks. Trace elements enriched in the primary dispersion zone are Zn, Pb, Ag, Sb, As, Rb, and TI. Antimony provides the most consistent and extensive trace element dispersion halo around the deposit and is also preserved in most of... 

To estimate the contribution of wind-blown dust of crustal origin to the fine aerosol concentration, elemental enrichment factors were calculated using the method of Macias et al. (20). The enrichment factor, EF., for an element i was calculated as follows ... 

Aerosol Elemental Enrichment Factors, 1979, China Lake... 

Studies of fresh ash produced by coal combustion have shown that many trace elements (As, B, Bi, Cd, Cr, Cu, Ge, Hg, Mo, Pb, Ni, Se, Sr, Tl, V, W, Zn) are enriched in the fly ash compared to the bottom ash (Hansen Fisher 1980 Eary et al. 1990 Mukhopadhyay et al. 1996 Karayigit et al. 2001). For example, Mukhopadhyay et al. (1996) reported 10-20 times enrichment of most trace elements in the fly ash compared to the feed coal and association of As with crystalline Fe-0 and Fe-S phases in the bottom ash from a power plant in Nova Scotia fed by eastern Canadian coal. Elements enriched in fly ash are typically those more easily volatilized. Because fly ash particles also have smaller sizes and therefore greater reactivity than bottom ash, the probability of metal leaching is correspondingly greater. Ainsworth Rai (1987) and Rai et al. (1988) found that most of the Cu, Mo, Se, Sr, and V in fly ash was readily soluble. 

Trace element measurements in lunar basalts also indicate that the Moon is depleted in highly volatile elements (Taylor et al., 2006a). Estimates of some of the Moon s volatile element concentrations are compared with the Earth in Figure 13.11 a. The absence of water in lunar basalts suggests that the mantle is dry. The Moon may also be enriched in refractory elements (Fig. 13.11b). Volatile element depletion and refractory element enrichment are expected consequences of the giant impact origin and subsequent high-temperature accretion of the Moon. 

The most obvious pattern among all the data concerned the difference between prehistoric and modem samples. A number of elements show either systematic increases or decreases in ppm concentrations between the modem and prehistoric shells. For example, Figure 7 plots Na and Ba as ratios Of % Ca. Relative to prehistoric samples, modem ones are systematically enriched in Na and depleted in Ba. Other elements that show such systematic changes include Ti, V, Mn, As, and Cd, where prehistoric samples tend to be enriched in these elements. Enrichment of some elements in prehistoric samples is likely the product of leaching of other elements over time (such as Na), thereby increasing the relative proportion of the former. 

Eckel WP, Langley WD. 1988. A background-based ranking technique for assessment of elemental enrichment in soils at hazardous waste sites. In Superfund 88 Proceedings of the 9th National Conference. Washington, DC The Hazardous Materials Control Research Institute. 

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