Chapter 1 The Biosphere Chapter 2 The Anthroposphere Introduction Air Pollution Water Pollution Soil Plants Chapter 3 Soils and Soil Processes Introduction Weathering Processes Pedogenic Processes Chapter 4 Soil Constituents Introduction Trace Elements Minerals Organic Matter Organisms in Soils Chapter 5 Trace Elements in Plants Introduction Absorption Translocation Availability Essentiality and Deficiency Toxicity and Tolerance Speciation Interaction Chapter 6 Elements of Group 1 (Previously Group Ia) Introduction Lithium Rubidium Cesium Chapter 7 Elements of Group 2 (Previously Group IIa) Beryllium Strontium Barium Radium Chapter 8 Elements of Group 3 (Previously Group IIIb) Scandium Yttrium Lanthanides Actinides Chapter 9 Elements of Group 4 (Previously Group IVb) Titanium Zirconium Hafnium Chapter 10 Elements of Group 5 (Previously Group Vb) Vanadium Niobium Tantalum Chapter 11 Elements of Group 6 (Previously Group VIb) Chromium Molybdenum Tungsten Chapter 12 Elements of Group 7 (Previously Group VIIb) Manganese Technetium Rhenium Chapter 13 Elements of Group 8 (Previously Part of Group VIII) Iron Ruthenium Osmium Chapter 14 Elements of Group 9 (Previously Part of Group VIII) Cobalt Rhodium Iridium Chapter 15 Elements of Group 10 (Previously Part of Group VIII) Nickel Palladium Platinum Chapter 16 Elements of Group 11 (Previously Group Ib) Copper Silver Gold Chapter 17 Trace Elements of Group 12 (Previously of Group IIb) Zinc Cadmium Mercury Chapter 18 Elements of Group 13 (Previously Group IIIa) Boron Aluminum Gallium Indium Thallium Chapter 19 Elements of Group I4 (Previously Group IVa) Silicon Germanium Tin Lead Chapter 20 Elements of Group 15 (Previously Group Va) Arsenic Antimony Bismuth Chapter 21 Elements of Group 16 (Previously Group VIa) Selenium Tellurium Polonium Chapter 22 Elements of Group 17 (Previously Group VIIa) Fluorine Chlorine Bromine Iodine

Trace elements in soils and plants

http://netedu.xauat.edu.cn/jpkc/netedu/jpkc2009/szylyybh/content/wlzy/1/Review%20of%20Arsenic%20in%20natural%20water%20-%20Smedly.pdf

A review of the source, behaviour and distribution of arsenic in natural waters

Summary
The water-stability of aggregates in many soils is shown to depend on organic materials. The organic binding agents have been classified into (a) transient, mainly polysaccharides, (b), temporary, roots and fungal hyphae, and (c) persistent, resistant aromatic components associated with polyvalent metal cations, and strongly sorbed polymers. The effectiveness of various binding agents at different stages in the structural organization of aggregates is described and forms the basis of a model which illustrates the architecture of an aggregate. Roots and hyphae stabilize macro-aggregates, defined as > 250 μm diameter; consequently, macroaggregation is controlled by soil management (i.e. crop rotations), as management influences the growth of plant roots, and the oxidation of organic carbon. The water-stability of micro-aggregates depends on the persistent organic binding agents and appears to be a characteristic of the soil, independent of management.

Organic matter and water-stable aggregates in soils

1. Plant Nutrients. 2. The Soil as a Plant Nutrient Medium. 3. Nutrient Uptake and Assimilation. 4. Plant Water Relationships. 5. Plant Growth and Crop Production. 6. Fertilizer Application. 7. Nitrogen. 8. Sulphur. 9. Phosphorus. 10. Potassium. 11. Calcium. 12. Magnesium. 13. Iron. 14. Manganese. 15. Zinc. 16. Copper. 17. Molybdenum. 18. Boron. 19. Further Elements of Importance. 20. Elements with More Toxic Effects. General Readings. References. Index.

/pdf/principles-of-plant-nutrition-2k4wl46ou6.pdf

Principles of plant nutrition

http://libir.tmu.edu.tw/bitstream/987654321/43034/1/4.pdf

Review of second-order models for adsorption systems.

Summary
The relationship between adsorption and pH, termed the adsorption envelope, varies with the pKa, of the conjugate acid of the anion, for several adsorbents in presence of an excess of specifically adsorbed anions. At pH values where the acid is fully dissociated, specific adsorption occurs only to the extent of the positive charge of the surface and little specific adsorption is found at pH values more alkaline than the zero point of charge (zpc).

With incompletely dissociated acids, anion adsorption can also take place at pH values more alkaline than the zpc providing the pH is somewhere near a pKa value of the acid, where the energy required to abstract a proton from the acid is at a minimum. The proton is required for the removal of a surface OH which provides a site for the anion.

Specific anion adsorption (i) from a fully dissociated acid can reduce the positive charge of the surface to zero and (ii) from a weak acid can make even a negative surface more negative. Thus specific adsorption shifts the zpc to more acid values.

The relationship between anion adsorption and OH release is not necessarily simple.

The ideas proposed for anion adsorption have implications for cation adsorption and incorporation in an oxide surface.

Anion adsorption by goethite and gibbsite

Summary

The specific adsorption of divalent Cd, Co, Cu, Pb, and Zn on goethite is measured as a function of pH. For each mole of heavy metal adsorbed approximately two moles of H+ ions are displaced from the interface. Using these results the heavy metal adsorption data are expressed as functions of the solution concentrations of both H+ and metal ions, and the interfacial reaction is described by the equation,



2SH+M2+= S2M+2H+.



The adsorption data are consistent with an electrochemical model of the simultaneous adsorption of H+ ions and divalent metal ions on to the oxide. The intrinsic affinities of the metal ions for the oxide surface increase in the order, Cd < Co < Zn < Pb < Cu. However, besides the affinity of the metal ion for the surface, the adsorption curves are considered to be influenced by surface charge, the adsorption density of the metal ions and their size.



The analysis of the data in terms of H+ and M2+ ion adsorption is considered to be complementary to the hydrolysis model for heavy metal adsorption.

THE SPECIFIC ADSORPTION OF DIVALENT Cd, Co, Cu, Pb, AND Zn ON GOETHITE

The specific adsorption of anions depends on the pK values of the anion acids The adsorbed anions confer a negative charge on the surface displacing the zero point of charge to lower pH values

Specific Adsorption of Anions

OVER the past decade much significance has been given to distribution of pore size characteristics in computing both saturated and unsaturated permeability of porous materials. Oil industry investigators1 and soil scientists have adopted this approach to permeability computation with considerable success.

Permeability of Porous Media

The competitive adsorption of phosphate + arsenate and phosphate + selenite on goethite and gibbsite has been measured. The oxide surface contains sites common to both anions on which competitive adsorption takes place and sites on which only one or the other anion is able to adsorb. The maximum amount of anions adsorbed from a mixture is approximately equal to the sum of the maximum adsorption for each anion in the absence of competition. The number of sites at which competition takes place is almost equal to the number of sites available to the anion with the lower adsorption in the absence of a competitor. Competition is described by a Langmuir-type exchange equation.

J. P. Quirk

Papers

Anion adsorption by goethite and gibbsite

THE SPECIFIC ADSORPTION OF DIVALENT Cd, Co, Cu, Pb, AND Zn ON GOETHITE

Specific Adsorption of Anions

Permeability of Porous Media

Competitive adsorption of negatively charged ligands on oxide surfaces