Soil, element speciation

In addition to soil solution, speciation of trace elements in water of the Nahr-Ibrahim river valley of Lebanon was studied with the AQUACHEM model. The results indicate that a high percentage of Pb and Zn is present as carbonate species, but in low percentages in free hydrated ion species. Cadmium exhibits as a high percentage of a free hydrated Cd2+. 

FACTORS AFFECTING TRACE ELEMENT SPECIATION IN SOIL SOLUTION... 

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 ... 

Carbonates, organic matter, Fe and Mn oxides, and clay minerals play important roles in controlling overall reactivity of trace elements in soils and sediments. This chapter addresses the interaction of trace elements with carbonates, organic matter, Fe and Mn oxides and clay minerals. Analytical techniques for trace element speciation in solid-phase and their distribution among various solid-phase components in arid and semi-arid soils are reviewed. Solubilities of trace elements in solid phases and their mineralogical characteristics in arid and semi-arid soils also are discussed. 

Rodushkin IV, Moiseenko TI, Kudryavtseva LP. 1995b. Changes in trace element speciation in Kola Morth surface waters during snow melt. Water Air Soil Pollut 85 731-736. 

Table 2.4 Element speciation by analysis of different physical fractions of a soil or sediment using a sensitive analytical technique such as AAS or neutron activation analysis...

In this chapter, we shall introduce soil speciation concepts by consideration of inorganic trace elements in dissolved and adsorbed forms, with reference to both their molecular speciation and their operationally defined soil component speciation. We shall then consider the implications of chemical speciation in soils for agriculture and soil pollution. 

In common with other solid materials the determination of element speciation in soils presents a number of difficulties. Firstly, direct determination of speciation in the solid material, without prior separation of the species from the solid matrix, is generally limited to major component elements since few of the direct techniques available are sensitive enough for trace element studies. Resort to separation or extraction of element species presents the usual problem of maintaining the speciation unchanged during the extraction or separation procedure. Despite these difficulties, speciation studies related to nutrient element availability to crops have been a major topic in soil science for more than half a century, uncategorised, however, as speciation until the relatively recent adoption of this terminology. 

This chapter considers methods of trace element speciation, and their application to soils, that involve selective chemical extraction techniques. It will be concerned firstly with extraction by single selective reagents and secondly with the development and application of sequential extraction procedures for soils and related materials. Sequential extraction procedures for sediments are discussed in depth in Chapter 11. Speciation in the soil solution and modelling aspects of its interaction with soil solid phases are comprehensively covered in Chapter 9 and will not be considered here. 

Cordos, E.A., Frentiu, T., Rusu, A.-M. and Vatca, G. (1995) Elemental speciation of lead, zinc and copper in sedimented dust and soil using a capacitively coupled plasma atomic emission spectrometer as detector. Analyst, 120, 725-731. 

In this context, speciation science seeks to characterise the various forms in which PTMs occur in soil or, at least, the main metal pools present in soil. Understanding speciation is important for assessing the potential of soil to supply micronutrients for plant growth or to contain toxic quantities of PTMs, and for determining amelioration procedures for soils at risk of causing the PTMs contamination of waterways. The residence time of an element in a soil depends on the mobility of its predominant forms. Speciation science is relevant to scientists with many different backgrounds and should be taken into consideration by legislators in the field of environmental protection. 

Adamo, P., Zampella, M., Gianfreda, L., Renella, G., Rutighano, F. A., and Terribile, F. (2006). Impact of river overflowing on trace element contamination of volcanic soils in south Italy Part I. Trace element speciation in relation to soil properties. Environ. Pollut. 144(1), 308—316. 

Burt, R., Wilson, M. A., Keck, T. J., Dougherty, B. D., Strom, D. E., and Lindahl, J. A. (2003). Trace element speciation in selected smelter-contaminated soils in Anaconda and Deer Lodge Valley, Montana, USA. Adv. Environ. Res. 8, 51—67. 

Many chemical models have been developed over the years for problems solving chemical speciation. A comprehensive survey of many of the models and detailed analysis of computer modeling in relation to trace element speciation has been by made by Waite (1989), with particular reference to MINEQL, and by Lumsdon and Evans (2002), with particular reference to MITEQA2. Soil solution has significant amounts of DOM, which is poorly quantified and understood. The trace element speciation information obtained using computer modeling with data on complexation constants of metal—DOM complexes has to be substantiated with data on free metal ion species obtained from sophisticated physical techniques. 

Amacher, M.C., R.W. Brown, R.W. Sidle, and J. Kotuby-Amacher. 1995. Effect of mine waste on element speciation in headwater streams, p. 275-309. In H.E. Allen et al. (ed.) Metal speciation and contamination of soil. Lewis Publ., Boca Raton, FL. 

Trace element speciation analysis is a base for the description of forms and compounds in which they occur in soils. Other definitions are also used to define properties of trace elements in soils. In fact, the general term availability has been recently defined as geoavailability, geochemical availability, biogeochemical availability and bioavailability (Wolt 1994, Smith and Huyck 1999) ... 

See alsa Distillation. Elemental Speciation Waters, Sediments, and Soils. Fuels Gaseous. Gas Chromatography Petrochemical Applications. Infrared Spectroscopy Near-Infrared Industrial Applications. Nuclear Magnetic Resonance Spectroscopy Overview. Sulfur. Supercritical Fluid Chromatography Applications. X-Ray Fluorescence and Emission Wavelength Dispersive X-Ray Fluorescence Energy Dispersive X-Ray Fluorescence. 

Adamo P, McHardy WJ, and Edwards AC (1998) SEM observations in the back-scattered mode of the soil-root zone of Brassica napus (cv. Rafal) plants grown at a range of soil pH values. Geoderma 85(4) 357-370. Batley GE (1989) Trace Element Speciation Analytical Methods and Problems. Boca Raton, FL CRC Press. Chappell A and Warren A (2003) Spatial scales of Cs-137-derived soil flux by wind in a 25 km arable area of eastern England. Catena 52(3—4) 209-234. 

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