Selective sequential dissolution

The book focuses on the biogeochemistry of trace elements in arid and semiarid zone soils and includes an introductory chapter on the nature and properties of arid zone soils. It presents an updated overview and a comprehensive coverage of the major aspects of trace elements and heavy metals that are of most concern in the world s arid and semi-arid soils. These include the content and distribution of trace elements in arid soils, their solution chemistry, their solid-phase chemistry, selective sequential dissolution techniques for trace elements in arid soils, the bioavailability of trace elements, and the pollution and remediation of contaminated arid soils. A comprehensive and focused case study on transfer fluxes of trace elements in Israeli arid and semi-arid soils is presented. The book concludes with a discussion of a quantitative global perspective on anthropogenic interferences in the natural trace elements distributions. The elements discussed in this book include Cd, Cu, Cr, Ni, Pb, Zn, Hg, As, Se, Co, B, Mo and others. This book is an excellent reference for students and professionals in the environmental, ecological, agricultural and geological sciences. 

SELECTIVE SEQUENTIAL DISSOLUTION FOR TRACE ELEMENTS IN ARID ZONE SOILS... 

SELECTIVE SEQUENTIAL DISSOLUTION CHARACTERIZATION, ADVANTAGES, AND DISADVANTAGES... 

There are a number of selective sequential dissolution procedures which have been developed for specific elements, matrices, regional soils, and specific purposes (Table 4.1). Additionally, various extractants are used in different sequential procedures for the similar targeted solid-phase component. The review on the extractants of individual fractions of metals in soil was made by Shuman (1991). However, in most protocols the trace elements/heavy metals in their native and waste-amended soils are divided into the following physicochemical forms ... 

Table 4.1. Some selective sequential dissolution procedures employed to fractionate trace elements in soils... 

Figure 4.1. Removal of carbonate from Israeli arid soils as indicated by the X-ray diffractograms after extraction of the carbonate fraction by NaOAc-HOAc solutions at various pHs for 16 hours. C calcite d = 3.04 A, and D dolomite, d = 2.89 A. Number 1, 2, 3, 4, 5, and 6 indicate non-treated soil (No. 1), treatments (No. 2-6) with NaOAc-HOAc solutions at pH 7.0, 6.0, 5.5, 5.0 and 4.0, respectively (after Han and Banin, 1995. Reprinted from Commun Soil Sci Plant Anal, 26, Han and Banin A., Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, p 563, Copyright (1995), with permission from Taylor Francis US)...

Figure 4.2. Dissolution of Ca from Israeli arid soils by NaOAc-HOAc solutions at various pHs after the extraction of the exchangeable fraction (after Han and Banin, 1995. Reprinted from Commun Soil Sci Plant Anal, 26, Han and Banin A., Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, p 568, Copyright (1995), with permission from Taylor Francis US)...

The two representative selective sequential dissolution procedures (Bonn and Rehovot procedures) were employed to comparatively study the distribution of trace elements in Israeli arid soils (Table 4.4). The results of both experiments have been fully reported by Banin et al. (1995) and Han and Banin (1995). 

An optimal selective sequential dissolution procedure should satisfy the following requirements ... 

Table 4.4. Comparisons of two selective sequential dissolution procedures ... 

On the basis of this comparison study, at present, it is still difficult to adopt a universal selective sequential dissolution procedure, which may be used everywhere and be suitable for all soils with diversified physical, chemical and mineralogical properties. The application of the SSD procedure must consider individual soil characteristics, such as soil type and properties. The two typical SSD procedures were developed to address soils formed in two climates. The Rehovot procedure was developed to be suitable for the calcareous soils in arid and semi-arid zone soils, whereas the Bonn procedure was created to primarily handle the acid and neutral soils in humid zones. In general, the Bonn procedure appears to be unsuited for calcareous soils in arid and semi-arid zones. The Rehovot procedure has limitations in handling acid and neutral soils, especially forest soils with higher content of organic matter. 

There are very limited comparative studies on fractionations and distribution of trace elements in soils extracted by various selective sequential dissolution protocols. Sutherland and Tack (2003) compared fractionation of Cu, Pb and Zn in reference soils using three selective... 

Below is a review of the chemical extractants and their extraction order, in sequence, in the selective sequential dissolution procedures (Table 4.5). 

Subsamples were taken for selective sequential dissolution analyses (SSD, Table 6.4) after lhour, 1 day, 3 days, 6 days, 12 days, 18 days, 24 days, days, 30 days, 2 months, 5 months, 10 months and 1 year for the saturation... 

Table 6.4. Protocol for the selective sequential dissolution procedure...

Han F.X., Banin A. Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, Commun Soil Sci Plant Anal 1995 26 ... 

To determine the contents of REEs (La, Ce, Pr, Nd, Sm, Eu) associated with different chemical compartments of the soil, both bulk and rhizosphere soil were subjected to selective sequential dissolution according to the following procedure, modified from Berna et al. (2000) ... 

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