Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

Last Child in the Woods: Saving Our Children From Nature-Deficit Disorder

Life on Earth is sustained by a small volume of soil surrounding roots, called the rhizosphere. The soil is where most of the biodiversity on Earth exists, and the rhizosphere probably represents the most dynamic habitat on Earth; and certainly is the most important zone in terms of defining the quality and quantity of the Human terrestrial food resource. Despite its central importance to all life, we know very little about rhizosphere functioning, and have an extraordinary ignorance about how best we can manipulate it to our advantage. A major issue in research on rhizosphere processes is the intimate connection between the biology, physics and chemistry of the system which exhibits astonishing spatial and temporal heterogeneities. This review considers the unique biophysical and biogeochemical properties of the rhizosphere and draws some connections between them. Particular emphasis is put on how underlying processes affect rhizosphere ecology, to generate highly heterogeneous microenvironments. Rhizosphere ecology is driven by a combination of the physical architecture of the soil matrix, coupled with the spatial and temporal distribution of rhizodeposits, protons, gases, and the role of roots as sinks for water and nutrients. Consequences for plant growth and whole-system ecology are considered. The first sections address the physical architecture and soil strength of the rhizosphere, drawing their relationship with key functions such as the movement and storage of elements and water as well as the ability of roots to explore the soil and the definition of diverse habitats for soil microorganisms. The distribution of water and its accessibility in the rhizosphere is considered in detail, with a special emphasis on spatial and temporal dynamics and heterogeneities. The physical architecture and water content play a key role in determining the biogeochemical ambience of the rhizosphere, via their effect on partial pressures of O2 and CO2, and thereby on redox potential and pH of the rhizosphere, respectively. We address the various mechanisms by which roots and associated microorganisms alter these major drivers of soil biogeochemistry. Finally, we consider the distribution of nutrients, their accessibility in the rhizosphere, and their functional relevance for plant and microbial ecology. Gradients of nutrients in the rhizosphere, and their spatial patterns or temporal dynamics are discussed in the light of current knowledge of rhizosphere biophysics and biogeochemistry. Priorities for future research are identified as well as new methodological developments which might help to advance a comprehensive understanding of the co-occurring processes in the rhizosphere.

Rhizosphere: biophysics, biogeochemistry and ecological relevance

'Blogging' - a contraction of the term 'web logging' - is perhaps best described as a form of micro-publishing. Easy to use, from any Internet connection point, blogging has become firmly established as a web based communications tool. The blogging phenomenon has evolved from its early origin as a medium for the publication of simple, online personal diaries, to the latest disruptive technology, the 'killer app' that has the capacity to engage people in collaborative activity, knowledge sharing, reflection and debate (Hiler, 2003). Many blogs have large and dedicated readerships, and blog clusters have formed linking fellow bloggers in accordance with their common interests. 
This paper explores the potential of blogs as learning spaces for students in the higher education sector. It refers to the nascent literature on the subject, explores methods for using blogs for educational purposes in university courses (eg. Harvard Law School), and records the experience of the Brisbane Graduate School of Business at Queensland University of Technology, with its 'MBA blog'. The paper concludes that blogging has the potential to be a transformational technology for teaching and learning.

Exploring the use of blogs as learning spaces in the higher education sector

Wild Crop Relatives: Genomic and Breeding Resources

Effective doctor-patient communication is a central clinical function in building a therapeutic doctor-patient relationship, which is the heart and art of medicine. This is important in the delivery of high-quality health care. Much patient dissatisfaction and many complaints are due to breakdown in the doctor-patient relationship. However, many doctors tend to overestimate their ability in communication. Over the years, much has been published in the literature on this important topic. We review the literature on doctor-patient communication.

Doctor-patient communication: a review.

Conflicting reports exist about the effect of N supply on the rate of leaf emergence. We examined effects of N deficiency on leaf and tiller emergence, tiller initiation and apical development in ‘Aroona’ and ‘Gamenya’ spring wheat (Triticum aestivum L.). Four levels of N (e.g., 50 μM N = N₅₀) were supplied by hourly irrigation with complete nutrient solution of plants growing in sand. The control plants in Exp. 1 (N₁₆₀₀) had 64 g kg⁻¹ N intheshoots at the two-leaf stag e, compared with 33 in N₅₀, 50 in N₃₀₀, and 58 in N₈₀₀. Compared with control plants, dry matter of N₅₀ plants was 10%, N₃₀₀ 50%, and N₈₀₀ 80%. Results in Exp. 2 were similar. The rate of leaf emergence was decreased in all N₅₀-treated and some N₂₀₀-treated plants, but not or N₃₀₀-treated plants. Tiller bud initiation was decreased in the treatment. The number of tiller buds was correlated with total number of leaves; if a leaf emerged, N deficiency did not affect tiller initiation. Nitrogen treatment did not alter the sequence of tiller emergence, but tiller emergence was delayed or did not occur in N₅₀, N₂₀₀, and N₃₀₀ plants. Nitrogen treatment had little effect on the rate of apical development. The double-ridge stage of development was delayed ≈2 d for both cultivars at the two lowest N treatments. Terminal spikelet production was also delayed by ≈2 d at these N treatments in Aroona, but not in Gamenya spring wheat. The rate of primordia initiation was decreased in N₅₀ and N₃₀₀ plants, resulting in fewer spikelet primordia. The level of N deficiency affected plant response to the stress.

Leaf Emergence, Tiller Growth, and Apical Development of Nitrogen-Dificient Spring Wheat

Zinc (Zn) distribution and transport in plants is affected by the level of Zn supply and plant species. When plants have low to adequate Zn supply, Zn concentrations are usually higher in growing tissue than in mature tissue; this is true for roots, vegetative shoots and reproductive tissues. In plants tolerant of toxic levels of Zn, accumulation has been observed in the root cortex and in leaves. In these tissues, Zn accumulates in cell walls or is sequestered in vacuoles.

Distribution and Transport of Zinc in Plants

level appeared to play a secondary role, as a growth inhibitor. The concentrations of indole-3-acetic acid (IAA), cytokinins (CK) and abscisic acid (ABA) were measured in Key words: Apical dominance, cytokinin, auxin, abscisic buds of different regions (main stem and lateral acid, Lupinus angustifolius. branches) of Lupinus angustifolius L. (cv. Merrit) and at different stages in the development of branches. In lupin, branching patterns are the result of discrete Introduction regions of axillary branches (upper, middle and basal) which elongate at much different rates. Early in devel- A strongly growing main shoot apex represses the opment only the main shoot elongates, followed usu- growth of lateral buds by exerting ‘apical dominance’. ally by basal branch growth and then rapid upper Sachs and Thimann (1967) proposed that apical dominbranch growth. Branches in the middle of the main ance was hormonally controlled and that auxin played a stem grow only weakly or fail to develop. Levels of IAA dominant role. The model envisages auxin being transwere generally high in the apical buds of slowly grow- ported from its principal site of synthesis, the dominant ing branches and low in buds from strongly growing apical bud, towards the lateral buds where it inhibits branches, whereas CK levels showed the opposite growth either directly or indirectly. Support for this relationship. CK5IAA ratio showed a closer rela- model relies on the fact that exogenous auxin applicationship with the rate of growth of a particular branch tion, either re-establishes apical dominance when applied better than the levels of either CK or IAA alone. During to the stump of decapitated plants, or suppresses lateral early stages of growth ABA concentration did not growth when applied to lateral buds of intact plants follow the rate of branch growth. However, later in (Cline, 1991; Tamas, 1995). development, where growth did not closely match the In such a scenario, quiescent axillary buds are regarded ratio of CK5IAA, ABA level showed a strong negative as ‘replacement apices’; being called upon following loss relationship with growth. A significant decrease in ABA of the strongly growing shoot apex. While this scenario was associated with continued strong growth of the may apply to many plant species, the hypothesis has main stem apex following a decline in CK5IAA ratio. limitations, and cannot readily explain branching patOverall, the best relationship between the level of terns in plants with weak apical dominance, such as growth factors in apical buds and branching pattern Coleus blumei Benth. and Arabidopsis thaliana L., or in in lupin was the ratio of CK5IAA, implying that high those for which decapitation leads to outgrowth of buds which are furthest away from the apex (Cline, 1996).

Branch development in Lupinus angustifolius L. II. Relationship with endogenous ABA, IAA and cytokinins in axillary and main stem buds

We hypothesized that the resistance of Hawkeye (HA) soybean (Glycine max L.) to iron-deficiency induced chlorosis (IDC) is correlated to an ability to accumulate a large pool of extracellular-root iron which can be mobilized to shoots as the plants become iron deficient. Iron in the root apoplast was assayed after efflux from the roots of intact plants in nutrient solution treated with sodium dithionite added under anaerobic conditions. Young seedlings of HA soybean accumulated a significantly larger amount of extracellular iron in their roots than did either IDC-susceptible PI-54619 (PI) soybean or IDC-resistant IS-8001 (IS) sunflower (Helianthus annus L.). Concurrently, HA soybean had much higher concentrations of iron in their shoots than either PI soybean or IS sunflower. The concentration of iron in the root apoplast and in shoots of HA soybean decreased sharply within days after the first measurements of extracellular root iron were made, in both +Fe and −Fe treatments. The accumulation of short-term iron reserves in the root apoplast and translocation of iron in large quantities to the shoot may be important characteristics of IDC resistance in soybeans.

Nancy Longnecker

Papers

Doctor-patient communication: a review.

Leaf Emergence, Tiller Growth, and Apical Development of Nitrogen-Dificient Spring Wheat

Distribution and Transport of Zinc in Plants

Branch development in Lupinus angustifolius L. II. Relationship with endogenous ABA, IAA and cytokinins in axillary and main stem buds

Accumulation of Apoplastic Iron in Plant Roots: A Factor in the Resistance of Soybeans to Iron-Deficiency Induced Chlorosis?