Soil total trace element content

ISO (2001) Soil Quality - Determination of total trace element content. Part 1 Digestion with hydrochloric and perchloric acids, International standard ISO 14869. 

Data from Ure AM, Bacon JR, Berrow ML, and Watt JJ (1979) The total trace element content of some Scottish soils by spark source mass spectrometry. Geoderma 22 1-23. 

In the rural situation, the total trace-element content of the soil may be virtually the same as that of the rocks from which the soil parent material was derived by weathering. The geochemical principles controlling the trace-element content of uncontaminated soils have been reviewed and reported by Mitchell [5, 80] who stated that it is possible to assess, with some degree of accuracy, the approximate total content of trace elements in a soil, when the nature of the parent material is known. 

Archer, F.C. and Hodgson, I.H. (1987) Total and extractable trace element contents of soils in England and Wales. Journal of Soil Science 38, 421-431. 

In areas which have been subjected to intensive glaciation, such as Scotland, the soils are often derived from mixtures of different types of rock and the nature of the parent material may vary, even within farm fields. In such circumstances, prediction of soil trace-element content may be very difficult. A further complication is that the total content of any trace element in the soil normally gives little indication of the availability of that element to plants, and Mitchell and co-workers have published several papers dealing with the factors affecting availability [6,84,85]. On the other hand, there are extensive regions in the world, for example, in central Australia, in the mid-west of the USA and in the steppes in the Soviet Union, where the soil is almost uniformly derived over wide areas from the same kind of parent material and where neither the total nor the available levels of trace elements vary very much. 

The rate of depletion of each element in relation to its total reserve in the soil will depend on the ratio of the level in crops to the total level in the soil and it is possible to calculate the maximum amount of dry matter of a given trace element content which can theoretically be removed from a soil of known composition. For example, an acre of topsoil, containing 1,000 tons of air-dry soil to plow depth with a total content of 10 ppm of any essential element can, in the limit, produce only 1,000 tons of crop dry matter of the same content. The ultimate theoretical production of crop dry matter is therefore limited by the total content of each essential trace element in the soil and is defined by the ratio of total soil content to crop content. 

Quevauviller Ph, Herzig R. and Muntau H (1996b) Certified reference material of lichen (CRM 482) for the quality control of trace element biomonitoring. Sci Total Environ 187 143-152 Quevauviller Ph, Lachica M., Barahona E, Rauret G, Ure A, Gomez A, and Muntau H (1997) The certification of the EDTA-extractable contents (mass fractions) of Cd, Cr, Ni, Pb, and Zn and of the DTPA-extractable contents (mass fractions) of Cd and Ni in calcareous soil by the extraction procedures given CRM 600. EUR Report 17555 Quevauviller Ph. Maier EA, and Griepink B, eds. (1995) Quality Assurance for Environmental Analysis. Elsevier. Amsterdam. 

Banin and his colleagues (Banin et al., 1997a) have studied the distribution of trace elements in 45 representative Israeli soils with 0.5-68% of CaC03 and 7.0-8.25 pH (Table 2.4). The total Cu concentration ranges from 3.21 mg/kg in a loessial soil to 62.05 mg/kg in a desert stony soil. In general, alluvial soils, colluvial-alluvial soils, and Terra-Rossa soils contain higher Cu than soils in Mediterranean brown and rendzina. The EDTA-extractable Cu content varies from 2-7.5 mg/kg in rendzinas, alluvial soils, and saline soils. 

Trace element speciation in soil solution is affected by total metal concentrations in soils. Free Cu2+ activity increases with total Cu content in soils from Quebec and New York (Sauve et al., 1997). Total free Cu activity in soils could be predicted from total Cu content and soil pH ... 

Soil solution to soil ratios also strongly affect distribution of some trace elements such as Zn speciation in arid and semi-arid soils. Fotovat et al. (1997) reported that the proportion of free hydrated Zn2+ to total Zn ranged from 20-65% at field capacity soil water content and decreased with increases in solution to soil ratios, while the proportion of Zn complexed with organic ligands increased dramatically in soils. However, solution to soil ratios do not strongly affect the distribution of Cu speciation in soil solution since Cu primarily occurs as organic complexes in these soil solutions. 

Banin A., Han F.X., Carina C. Total contents and solid-phase distribution of trace elements in 45 Israeli soils. Unpublished data. Hebrew University of Jerusalem, Rehonot, 76100. Israel. 1997a. 

We can see that the soluble and exchange forms of these metals are present in small amounts accounting merely for a few percent of the total metal content in soil. The content of organometal species is relatively high in the upper profile rich in humic species, whereas it drops sharply in the mineral horizons. Copper is extensively involved in the biogeochemical cycle in the Forest ecosystems and this is less profound for cobalt. It is noteworthy that a large part of metals (in particular, of copper) become bound to iron hydroxides. This is typical for various trace elements, including arsenic, zinc and other elements with variable valence. 

The second reason for acid-digestion is the determination of the total soil elemental content of, e.g. potassium, phosphorus or trace elements. This is seldom done for potassium in normal soil samples, mainly because the total K in soils is of no value as an index to the availability of K to plants, nor is it always of value in tracing the movement or accumulation of applied fertilizer K (Pratt, 1965). The unreactive soil phosphorus is obtained by subtracting the naturally leached reactive phosphorus from the total phosphorus, and a method for determining the latter by extraction with sulphuric acid and potassium persulphate is cited by Turner and FHaygarth (2000). They analysed... 

Species distribution studies have shown that trace element (e.g. metals) concentrations in soils and sediments vary with physical location (e.g. depth below bed surface) and with particle size. In these speciation studies the total element content of each fraction was determined using a suitable trace element procedure, for example, solid sample analysis by X-ray emission spectroscopy or neutron activation analysis, or alternatively by dissolution of sample and analysis by ICPOES, AAS or ASV. The type of sample fraction analysed can vary, and a few... 

Berrow, M.L. and Mitchell, R.L. (1980) Location of trace elements in soil profiles total and extractable contents of individual horizons. Trans. Roy. Soc. Edinburgh, 71, 103-121. 

The total content of the major elements in soil is of little practical significance since only a tiny, soluble fraction is available for absorption by plant roots (West, 1981 Tinker, 1986). To some extent this is less true for trace elements and micronutrients where for example, analyses of total copper or zinc can be used to assess the likelihood of plant deficiencies or toxicities. Nonetheless, for an element to be bioavailable it has to be relatively soluble. 

The significant part of trace elements in the soils of Steppe ecosystems are bound with highly dispersed mineral-organic particles, to a lesser degree, with only organic matter. We can see that the water soluble and exchangeable forms are less than 1 % of the total content. Specific forms of trace elements are bound with carbonate and gypsum in B and C horizons (Table 28). 

In general, the total contents of trace elements in solutions of uncontaminated mineral soils ranges from 1 to 100 pg L, while in contaminated soils these values can be much higher. In both types of soil, however, these are negligible portions of the total soil metals. The transfer factor - calculated as a ratio of metals in solution of contaminated soils to their content in solution of the control soils - usually decreases in the following order Cd > Ni > Zn > Cu > Pb > Cr (Kabata-Pendias and Pendias 2001). 

Biogeochemical availability is defined as the quantity-intensity factor calculated as a ratio of total content to the concentration of a trace element in soil solution. 

Inorganic components (including pollutants) in the soil may be present in different forms, which should be taken into account when analysing the soil. From this standpoint, particularly analyses are of interest, which provide data on those trace elements which are chemically available for the biosphere. The total content of trace elements in soils [1] is of less importance from the chemical standpoint. 

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