Tectonic Inclusions in Serpentinite Landscapes Contribute Plant Nutrient Calcium

Soil Science Society of America Journal - SSSAJ 01/2008; 72(3). DOI: 10.2136/sssaj2007.0159
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    ABSTRACT: California's diverse environmental gradients serve as natural experiments for examining controls on soil mineral distribution in landscapes. In this paper we use example soilscapes from throughout California to examine how lithology, climate, topography, and duration of pedogenesis interact to produce distinctive weathering environments and characteristic suites of soil minerals. Seven soil-geomorphic sequences were assembled from the literature to illustrate major soil mineralogical trends: 1) granitic terrain of the Peninsular Ranges, 2) granitic terrain of the central Sierra Nevada, 3) andesitic terrain of the northern Sierra Nevada, 4) fluvial terraces on the east side of the Great Valley, 5) marine terraces of the central coast, 6) ultramafic terrain of the Klamath Mountains, and 7) an alluvial fan in the Mojave Desert. Results of this analysis show that kaolin is present in virtually all pedons, irrespective of climate, parent material, age, or topographic position. Kaolin does not form in ultramafic soils due to insufficient aluminum. Many secondary clay minerals reflect the state's strong climatic influence, with palygorskite, smectite, and vermiculite in the dry, hot environments; hydroxy-interlayered minerals, gibbsite, and short range-ordered minerals in the cool, moist environments. In arid and semi-arid regions, the distribution of calcite, gypsum, and soluble salts is strongly related to patterns of eolian dust deposition and water infiltration and leaching.
    Geoderma. 01/2010;
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    ABSTRACT: The vertical distribution of 14 geochemical elements (Si, Al, Ti, K, Na, Ca, Mg, Fe, Mn, Cu, Cr, Ni, Pb, and Zn) in nine serpentine pedons for three ophiolite complexes was investigated. The pedons are located at Wu-Mau, Tong-An, and Shih-Tao mountains in the Coastal Range, eastern Taiwan. The objective of this study was to discriminate the parent material inheritance and pedogenic factors by comparison of the element concentrations based on principal component (PC) analysis. From the experimental results, the relative abundance of major elements was as follows: Si > Fe > Mg > Al, with lesser concentrations of Ti, K, Na, and Ca. In addition, Cr, Mn, and Ni contents in these soils were higher than in soils formed from other parent materials, with considerable variation between pedons on different landscapes, which reflected the ophiolite differences and degrees in chemical weathering of the associative serpentinitic rocks. The contents of pairs of Si-Fe, Si-Mn, Si-Pb, and Si-Zn showed significantly (P < 0.05) positive correlations. The close relations among contents of Fe, Mn, Cr, and Ni were observed herein. According to the eigenvalue in PC analysis, the elements most responsible for separation along the PC-1 axis were Si, Fe, Mn, Zn, Mg, and Ca, whereas Cr and Ni were the trace metals responsible for separation along the PC-2 axis. This result reflected the parent material differences in igneous rock composition and the degree of serpentinization between ophiolite complexes.
    Soil Science 04/2009; 174(5):283-291. · 1.05 Impact Factor
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    ABSTRACT: The regulated formation of inorganic minerals in living systems is called biomineralization. The mineralization processes of biogenic minerals are strictly regulated by a specific set of biomolecules, typically by proteins. Biologically formed calcium phosphates (hydroxyapatite (HA) in particular) are almost always nano-dimensional and nano-crystalline and are formed in vivo under mild conditions. The importance of understanding the molecular mechanisms underlying biological mineralization is underscored by the diseases associated with ectopic calcification or defects of skeletal mineralization. Proteins that mediate the mineralization process offer us a template for understanding how to potentially enhance the treatment of calcified tissue defects. However, the complexity and the number of proteins involved even in a rather simple biomineralization process can be daunting. The goal of this research was to identify short peptides through peptide-display libraries and demonstrate the utility of these peptides in better understanding the molecular mechanisms underlying biomineralization and as potential therapeutic agents in repairing calcified tissue defects. Using the phage-peptide display library, we have identified peptides that have affinity to HA and can regulate the formation of HA crystals. Utilizing the sequence knowledge obtained, we have identified putative functional domains within amelogenin; a naturally existing mineralization related protein, which, in turn, may provide a better understanding of the formation of dental enamel. These peptides also have the potential to be used to repair calcified tissue defects. To investigate this, we have developed and tested in vitro a hydrogel scaffold with pre-determined functionalities. We have also demonstrated the feasibility of obtaining significant re-mineralization of incipient dental root lesions ex vivo in a relatively short time using the mineralization-directing peptides. The approaches developed through this research may offer clinically acceptable novel procedures to treat calcified tissue defects because the developed peptide is safe to use and promotes the mineralization in a short period of time offered by none of the existing treatment options.