Sulfates in soils

Those who use recreational shooting ranges may be exposed to lead and soluble lead compounds, such as carbonates and sulfates, in soil. Surface... 

Bettany, J.R. and Helstead, E.H. (1972) An automated procedure for the nephelometric determination of sulfate in soil extracts. Canadian Journal of Soil Science 52, 127-129. 

A turbidimetric method has been described for the determination of water-soluble and acid-soluble sulfate in hydrochloric acid extracts of soils [62]. Spectrophotometry has also been employed to carry out the determination of total water-soluble sulfate in soil [63,64],... 

In an indirect method for determining sulfate in soil extracts, Little et al. [68] precipitate sulfate as the lead salt in 40% ethanol medium. Unconsumed sol-... 

Molecular emission cavity analysis has been used to determine soluble sulfate in soil [69]. 

The Bradfield and Cooke [45] procedure (Sect. 6.12) determines sulfate in soils. Miscellaneous... 

Little or no fractionation accompanies the uptake of sulfate in soils by plants during ASR (60.611. Chukhrov et al. ( Q) showed that in cases where atmospheric sulfate is not subject to bacterial reduction in the soil, the value of the plant sulfur was identical to rainfall sulfur. In soils subject to dissimilatory sulfate reduction, the 6 S value of plant sulfur differed from that of local rainfall. Additionally, Chukhrov et al. (60) found that plants from oceanic islands had a sulfur content with higher values than those from continental areas, which they attribute to the relative influence of marine sulfate to these areas. 

Over the last three decades, two general approaches have been proposed in the literature for describing the interactions of sulfate in soils. The first approach is that of a chemical nature where thermodynamic interrelationships with speciation of cations and anions present in soil solution and the interaction with the soil surface are the major mechanisms. These models may be referred to as chemical models. Examples of such models include that of Cosby et al. (1986), Reuss and Johnson (1986), De Vries et al. (1994), among others. A common feature of these models is that both ion exchange and aluminum hydrolysis reactions are similar. Their capability of quantifying these processes varies according to whether the interactions are... 

Barrow, N.J. (1975) Reactions of fertilizer sulfate in soils. In K.D. McLachlan (ed.), Sulfur in Australasian Agriculture, pp. 50—57. Sydney Univ. Press, Australia. 

Figure 2.2. Routine assay of (a) sulfate in soil extracts by spectrophotometry [355] and (b) of potassium in soil extracts by flame photometry [43] as performed by the Analytical Laboratory of the Centro de Energia Nuclear na Agricultura, Piracicaba, Sao Paulo, Brazil. Note that the large series of routine assays, all performed in duplicate, are bracketed by serial calibration of standards injected in triplicate.

The UK s Department of Transport s specification states that the upper limiting value for the total sulfate level in the soil may be equivalent to 1 % by weight (expressed as SO3) [26.6]. It proposes an upper limit for sulfate in groundwater adjacent to lime and/or cement treated areas of 1.9 g/1. A test method for sulfate in soil is given in BS 1047 [26.14]. 

Methanogens require neutral pH conditions to function optimally. Methane prodnction occnrs only after a sequential reduction of other inorganic electron acceptors (e.g., Fe +, Mn +, SO ) it is produced at redox levels below which sulfate in soil is rednced. Methane prodnction is inversely related to sulfate concentration in wetland soils and sediments. High snlfate levels snch as those found in seawater can inhibit methane formation (DeLaune et al., 1983). 

The main problem is the external problem, mainly due to the corrosive nature of the soil. Across the pipeline route, the soil can be soft mud, hard mud, rocks, sand, sand with minerals, moisture, and other environments such as marshy lands, brackish water, seawater, and so forth. Ordinary steel with several compositions, shown in Table 8.1, shows severe corrosion, general corrosion, pitting, and so forth. One kind of serious corrosion problem that takes place is microbiological corrosion, which occurs due to presence of sulfate-reducing bacteria (SRB). They convert sulfate in soil to sulfide, which attacks steel, causing severe pits. Thus, external corrosion is taken care of by a combination of a good coating and cathodic protection. Let us now deal with internal and external corrosion in more detail. 

A portable apparatus has been developed for the determination of chloride in water (0.001%) by precipitation with silver labeled with "Ag. A rapid and routine method for the determination of sulfate in soils is based on its precipitation with barium salt labeled with... 

Sulfate in soil on Mars, A barium sulfate precipitation titration described at the opening of this chapter is shown in the figure. The initial concentration of Cl" before adding BaCl2 was 0.000 19 M in 25 mL of aqueous extract of Martian soil. At the end point, when there is a sudden rise in Ba, [cr] = 0.009 6 M. 

Figures 6.3 and 6.4 show preindustrial and present-day circulation of S in earth s surface environment. Sulfur supply to the atmosphere by industrial activities (e.g., burning of fossil fuels, smelting) is 113 x lO g year that is about eight times of flux by volcanism (14 x lO g year" ) (Kimura 1989). Riverine sulfur flux to ocean is 208 x lO g year. A half of this flux is considered to be of anthropogenic source (Holland 1978). Sulfur in environment (atmosphere, river water) is the element that is significantly affected by human activity, the greatest among elements. According to previous estimates most of sulfur in acid rain transfer to river water. However, acid rain containing sulfur reacts with soil and evaporite, leading to the formation of sulfate minerals and fixation of sulfur in soil. If we take into accotmt the amount of sulfur fixation as sulfates in soil, previously obtained...

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