Soil inorganic constituents

X-ray diffraction is the most commonly used technique to solve the atomic structure of crystalline materials, and it has provided one of the cornerstones of soil science research in determining the structure of soil inorganic constituents (Brindley and Brown... 

The weathering process which eventually reduces the rock of the parent material to the inorganic constituents of soil comprises both physical and chemical changes. Size reduction from rocks to the colloidal state depends not only upon the mechanical action of natural forces but also on chemical solubilisation of certain minerals, action of plant roots, and the effects of organic substances formed by biological activity. 

Table II summarizes analytical data for dissolved inorganic matter in a number of natural water sources (J3, 9, J 9, 20, 21). Because of the interaction of rainwater with soil and surface minerals, waters in lakes, rivers and shallow wells (<50m) are quite different and vary considerably from one location to another. Nevertheless, the table gives a useful picture of how the composition of natural water changes in the sequence rain ->- surface water deep bedrock water in a granitic environment. Changes with depth may be considerable as illustrated by the Stripa mine studies (22) and other recent surveys (23). Typical changes are an increase in pH and decrease in total carbonate (coupled), a decrease in 02 and Eh (coupled), and an increase in dissolved inorganic constituents. The total salt concentration can vary by a factor of 10-100 with depth in the same borehole as a consequence of the presence of strata with relict sea water. Pockets with such water seem to be common in Scandinavian granite at >100 m depth.

A majority of soil extractions of inorganic constituents are carried out to determine the metal content of a soil sample. In these cases, it is common to use add extracting solutions. Dilute hydrochloric and sulfuric acids are most commonly used. Nitric acid is an oxidizer, so undesired oxidation can occur during the extraction process using this reagent. Phosphate is a natural... 

Offers potential applications in the removal of inorganic constituents, such as heavy metals, that conventional soil washing technology lacks. 

The process is less suited to soils with undesirable high inorganic constituents, which result from the inherent mineralogy of the soils. 

In order to sieve samples that are to have their inorganic constituents determined, the soil is ground to pass through a nylon sieve meeting the requirements of BS 410i77. This avoids sample contamination associated with the use of metallic sieves. When sieving samples prior to the determination of organic constituents, a metal sieve may be used provided it does not react with the determinand of interest. 

Inderjit and Dakshini, K. M. M. 1999. Bioassays for allelopathy interactions of soil organic and inorganic constituents. In Inderjit, Dakshini, K. M. M., and Foy, C. L. (Eds.), Principles and Practices in Plant Ecology — Allelochemical Interactions. CRC Press, Boca Raton, FL, 35-42... 

Johnson J. S., Baker L. A., and Fox P. (1999) Geochemical transformations during artificial groundwater recharge soil-water interactions of inorganic constituents. Water Res. 33, 196-206. 

About 40% of the solid phase is inorganic and about 10% is organic, either dead or alive. The inorganic constituents of the soil are dominated by four elements O, Si, Al and Fe (Jackson, 1964). 

Recognition that Pb-contaminated house dust is a major source of Pb exposure for young children inspired research into other inorganic constituents of house dust, and by the early 2000s multi-element indoor data became available for many towns and cities in the U.K. and continental Europe, North America, Asia, Australia, and New Zealand. This research has revealed another widespread phenomenon concentrations of many key metals and metalloids, including Pb, Hg, As, Cd, Cu, Zn, and Sb, are commonly elevated in indoor dust compared to exterior dust and soil in ordinary urban environments (e.g., Thornton etal., 1985 Culbard etal., 1988 Fergusson and Kim, 1991 Kim and Fergusson, 1993 ... 

Arsenic. More than 300 arsenate and associated minerals have been identified (Escobar-Gonzalez and Monhemius 1988). Inevitably, some of the arsenic contained in these minerals enters any industrial circuit, and concentrations of As in soils and waters can become elevated due to mineral dissolution. The original National Priority List (USA) identified approximately 1000 sites in the United States (USA) that posed environmental health risks (Nriagu 1994 Allen et al. 1995) with arsenic cited as the second most common inorganic constituent after lead (Database 2001). The more common oxidation states of arsenic are III and V, and the predominant form is influenced by pH and redox potential. In aqueous solutions of neutral pH, arsenate is present... 

---