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1

Iron oxyhydroxide mineralization on microbial extracellular polysaccharides  

E-print Network

Iron oxyhydroxide mineralization on microbial extracellular polysaccharides Clara S. Chan a Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from

2

Iron oxyhydroxide mineralization on microbial extracellular polysaccharides  

SciTech Connect

Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron oxidation and create polymers that localize mineral precipitation. In order to classify the microbial polymers that influence FeOOH mineralogy, we studied the organic and mineral components of biominerals using scanning transmission X-ray microscopy (STXM), micro X-ray fluorescence ({mu}XRF) microscopy, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from a creek and abandoned mine; these samples are dominated by iron oxyhydroxide-coated structures with sheath, stalk, and filament morphologies. In addition, we characterized the mineralized products of an iron-oxidizing, stalk-forming bacterial culture isolated from the mine. In both natural and cultured samples, microbial polymers were found to be acidic polysaccharides with carboxyl functional groups, strongly spatially correlated with iron oxyhydroxide distribution patterns. Organic fibrils collect FeOOH and control its recrystallization, in some cases resulting in oriented crystals with high aspect ratios. The impact of polymers is particularly pronounced as the materials age. Synthesis experiments designed to mimic the biomineralization processes show that the polysaccharide carboxyl groups bind dissolved iron strongly but release it as mineralization proceeds. Our results suggest that carboxyl groups of acidic polysaccharides are produced by different microorganisms to create a wide range of iron oxyhydroxide biomineral structures. The intimate and potentially long-term association controls the crystal growth, phase, and reactivity of iron oxyhydroxide nanoparticles in natural systems.

Chan, Clara S.; Fakra, Sirine C.; Edwards, David C.; Emerson, David; Banfield, Jillian F.

2010-06-22

3

Iron oxyhydroxide mineralization by microbes in terrestrial environments  

NASA Astrophysics Data System (ADS)

Many microorganisms produce extracellular organic structures that become mineralized and thus preserved. As in higher organism mineralization (e.g. shells and bones), organics template mineral nucleation and control growth. However, polymer-mediated crystal growth is a more general phenomenon that can occur in extracellular, geochemically open systems. We have been studying microbial polymers mineralized by iron oxyhydroxides in a variety of natural environments, including a flooded mine in Wisconsin, creeks in Virginia and California, and cold springs in Oregon. Enrichment culturing showed that these environments are all populated by neutrophilic iron-oxidizers. We used scanning and transmission electron microscopy (SEM and TEM), Fourier transform infrared spectroscopy (FTIR), and synchrotron-based scanning transmission X-ray microscopy (STXM) to investigate the mineralogy and organic polymer functional groups. Microscopic observations revealed that these samples, while often dominated by the sheaths and stalks generally attributed to Leptothrix spp. and Gallionella, actually contain mineralized structures with a wide range of morphologies. The extent of mineralization is variable, with some environments characterized by heavy encrustations that likely formed via abiotic precipitation. We focused on the lightly mineralized polymers as this allows us to more closely examine the organic-mineral interactions. STXM work shows that the organics in the flooded mine and Virginia creek have common functional groups, including carboxyls. However, the exact ratio of functional groups may be more dependent on environmental factors than species. Our previous work showed that organic polymer fibrils template unusually long akaganeite (beta FeOOH) crystals in biofilm samples from the flooded mine. Subsequent work has shown that polymers in other environments, including polymers contained in organized structures, also template iron oxyhydroxide mineralization. Thus, microbial polymer templation of iron oxide minerals appears to be a general phenomenon. We also examined polymer mineralization in culture and abiotic synthesis experiments. We combined alginate, a well-characterized microbial polymer with carboxylic functional groups, and Fe(III) in various forms and reproduced some of the simple structures found in nature. We used STXM (with C, N, O, and Fe NEXAFS) and Fe EXAFS to follow the influence of polymers during mineral formation. NEXAFS data collected to date clearly show an evolution in interactions between polymer functional groups as iron is bound and mineralization proceeds. An understanding of polymer-mediated formation of unique minerals will allow us to better establish these minerals as biosignatures.

Chan, C. S.; Fakra, S.; Banfield, J. F.

2004-12-01

4

The role of iron oxyhydroxides in phosphorus chemistry of some East Texas forest soils  

E-print Network

in the forest floor were determined. Total P (PT) in the forest floor, and total and Mehlich-1 P and citratedithionite (CD) and acid ammonium-oxalate (AAO) extractable P, Al, Fe, and Mn within the mineral soil upper 100 cm were determined. Colorimetric...

Hass, Amir

2006-10-30

5

Influence of Pedogenic Iron-oxyhydroxides on the Ge/Si Weathering Tracer  

NASA Astrophysics Data System (ADS)

Germanium/silicon ratios are a promising tracer of the silica cycle in both marine and terrestrial environments. Prior work shows that Ge/Si ratios are fractionated by at least two distinct mechanisms in the weathering environment: sequestration of Ge by soil clay minerals and biological fractionation during plant phytolith formation. Ge may also be sequestered by pedogenic iron oxyhydroxides, resulting in a decoupling of the Ge and Si geochemical cycles. Ge/Si ratios in Hawaiian soils are high (3.5-25 ? mol/mol) relative to the ratio in the basaltic parent rock (2.5? mol/mol). We are examining Ge behavior in a well-characterized climate gradient on the Hawaiian island of Maui to elucidate the relationship between Fe geochemistry and Ge/Si ratios. The Maui precipitation gradient is made up of 7 sites on the flank of Haleakala Volcano ranging in mean annual precipitation from 875 mm rain/year to 5066 mm rain/year (Schurr et al., 2001). All sites are developed on ˜400 ka parent material and are highly weathered (>80% Si loss relative to immobile Nb). Sites experiencing less than 3338 mm rain/year display characteristics typical of oxic, highly weathered basaltic soils. In these soils, Fe weathered from parent material is not mobile and accumulates as secondary Fe(III) minerals (ferrihydrite). The wetter sites (>3338 mm/yr) show evidence of extensive Fe reduction, resulting in mobilization and loss. Ge/Si ratios in relatively dry sites (<3338 mm rain/year) are as high as 21 ? mol/mol, nearly 10 times higher than parent rock ratios. Fe-depleted horizons in the wettest sites have Ge/Si ratios as low as 3.5 ? mol/mol. Reductive loss of Fe-oxyhydroxides results in a dramatic drop in Ge/Si ratios, suggesting that Ge is in part accumulating in the Fe oxyhydroxide component of soil. However, nearly Fe-free soils maintain Ge/Si ratios elevated with respect to parent material, consistent with partitioning of Ge into secondary soil alumosilicates. Regardless, the influence of pedogenic Fe-oxyhydroxides must be taken into account when using the Ge/Si system as a weathering tracer.

Scribner, A. M.; Kurtz, A.; Chadwick, O.

2003-12-01

6

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

USGS Publications Warehouse

This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

Balistrieri, L.S.; Chao, T.T.

1990-01-01

7

Molecular Mechanisms of Iron Oxyhydroxide Biomineralization  

NASA Astrophysics Data System (ADS)

Neutrophilic iron-oxidizing microbes such as Gallionella and PV-1 (Emerson and Moyer, 1997) extrude polymers that become encrusted with iron oxides. Little is known about the identity of these polymers, their biological function and the roles they play in mineralization. To this end, we are investigating iron oxidizers in natural terrestrial iron-rich microbial mat communities, culturing and characterizing them in the laboratory and performing abiotic synthesis experiments based on the natural mineralization processes. Our sampling site is in a flooded former lead-zinc mine in Tennyson, WI, which is host to thick reddish-orange microbial mats. Scanning and transmission electron microscopy studies show that the mat is composed of iron oxide-covered stalks and sheaths (like those formed by Gallionella and Leptothrix spp.), as well as tangled masses of mineralized filaments. There is evidence of polymer influence on mineral phase and morphology in the form of extremely thin (few-unit cell wide), microns-long akaganeite (? -FeOOH) crystals at the center of these mineralized filaments. We are using synchrotron-based X-ray spectromicroscopy (PEEM-photoelectron emisson microscopy and STXM-scanning transmission X-ray microscopy), which has the ability to give chemical information on heterogenous samples at high spatial resolutions. Both PEEM and STXM show that these filaments contain polysaccharides, which are likely templating the akaganeite formation. Initial iron oxide synthesis experiments using model microbial polysaccharides support this hypothesis. Further synthesis and characterization by X-ray absorption and infrared spectroscopy methods is being performed in order to elucidate the molecular mechanisms of mineral nucleation and growth.

Chan, C. S.; Fakra, S.; de Stasio, G.; Banfield, J. F.

2003-12-01

8

Antagonistic effects of humic acid and iron oxyhydroxide grain-coating on biochar nanoparticle transport in saturated sand.  

PubMed

Biochar land application may result in multiple agronomic and environmental benefits (e.g., carbon sequestration, improving soil quality, and immobilizing environmental contaminants). However, our understanding of biochar particle transport is largely unknown in natural environments with significant heterogeneity in solid (e.g., patches of iron oxyhydroxide coating) and solution chemistry (e.g., the presence of natural organic matter), which represents a critical knowledge gap in assessing the environmental impact of biochar land application. Transport and retention kinetics of nanoparticles (NPs) from wheat straw biochars produced at two pyrolysis temperatures (i.e., 350 and 550 °C) were investigated in water-saturated sand columns at environmentally relevant concentrations of dissolved humic acid (HA, 0, 1, 5, and 10 mg L(-1)) and fractional surface coverage of iron oxyhydroxide coatings on sand grains (?, 0.16, 0.28, and 0.40). Transport of biochar NPs increased with increasing HA concentration, largely because of enhanced repulsive interaction energy between biochar NPs and sand grains. Conversely, transport of biochar NPs decreased significantly with increasing ? due to enhanced electrostatic attraction between negatively charged biochar NPs and positively charged iron oxyhydroxides. At a given ? of 0.28, biochar NPs were less retained with increasing HA concentration due to increased electrosteric repulsion between biochar NPs and sand grains. Experimental breakthrough curves and retention profiles were well described using a two-site kinetic retention model that accounted for Langmuirian blocking or random sequential adsorption at one site. Consistent with the blocking effect, the often observed flat retention profiles stemmed from decreased retention rate and/or maximum retention capacity at a higher HA concentration or smaller ?. The antagonistic effects of HA and iron oxyhydroxide grain-coating imparted on the mobility of biochar NPs suggest that biochar colloid transport potential will be dependent on competitive influences exerted by a number of environmental factors (e.g., natural organic matter and metal oxides). PMID:23614641

Wang, Dengjun; Zhang, Wei; Zhou, Dongmei

2013-05-21

9

Pressure-Induced Hydrogen Bond Symmetrization in Iron Oxyhydroxide  

NASA Astrophysics Data System (ADS)

Under high pressures the hydrogen bonds were predicted to transform from a highly asymmetric soft O-H⋯O to a symmetric rigid configuration in which the proton lies midway between the two oxygen atoms. Despite four decades of research on hydroxyl containing compounds, pressure induced hydrogen bond symmetrization remains elusive. Following single crystal x-ray diffraction, Mössbauer and Raman spectroscopy measurements supported by ab initio calculations, we report the H-bonds symmetrization in iron oxyhydroxide, FeOOH, resulting from the Fe3+ high-to-low spin crossover at above 45 GPa.

Xu, Weiming; Greenberg, Eran; Rozenberg, Gregory Kh.; Pasternak, Moshe P.; Bykova, Elena; Boffa-Ballaran, Tiziana; Dubrovinsky, Leonid; Prakapenka, Vitali; Hanfland, Michael; Vekilova, Olga Yu.; Simak, Sergei I.; Abrikosov, Igor A.

2013-10-01

10

Effect of Transport and Aging Processes on Metal Speciation in Iron Oxyhydroxide Aggregates, Tar Creek Superfund Site, Oklahoma  

NASA Astrophysics Data System (ADS)

Following the cessation of mining activity in the late 20th century, Tar Creek Superfund Site was left highly contaminated by Pb, Zn, and Cd. Tar Creek, which flows through the site and into the Neosho River, has been studied extensively because of its potential to transport metals from the mining site to downstream communities. Previous research identified aggregated iron oxyhydroxide material, which forms when mine seepage mixes with Tar Creek surface water, as a major transport vector of metals. Frequent flooding in Tar Creek deposits aggregates on downstream floodplains, where wetting and drying processes alter the speciation of iron and other metals. This study seeks to better quantify those changes and to determine how transport and aging affects the human and ecological health risk. Sequential extractions of aggregate samples collected from the creek demonstrate that Fe is present in both amorphous (10-35% of Fe extracted) and more crystalline (8-23% of Fe extracted) phases. Substantial portions of heavy metals sorb to amorphous iron oxyhydroxide phases (accounting for 10-30% of Pb and Zn extracted) but are not associated with more crystalline iron oxide phases (representing only 1% or less of the Pb and Zn extracted). Samples have a high organic matter content (18-25% mass loss on ignition), but only Fe was significantly extracted by the oxidizing step targeting organic matter (1-2% of Pb and Zn extracted, but 10-26% of Fe extracted). The majority of metals were extracted by the soluble or residual steps. If metals and organic matter inhibit transformation of amorphous iron oxyhydroxide material to nano and crystalline iron oxides, then a steady-state volume of amorphous iron oxyhydroxide material with a high total sorption capacity may exist within Tar Creek, enhancing the metal flux accommodated by this transport mechanism. Once transported downstream and deposited on floodplains, however, it is hypothesized that repeated changes in soil matrix composition and thermodynamic conditions could facilitate a transformation to more crystalline iron phases and increase metal bioavailability. While preliminary data from in-creek aggregates show no clear trend in mineralogical composition with downstream transport, only the furthest downstream samples have 2-line ferrihydrite in amounts detectable by XRD.

Estes, E. R.; Schaider, L. A.; Shine, J. P.; Brabander, D. J.

2010-12-01

11

Stable Cluster Formation in Aqueous Suspensions of Iron Oxyhydroxide Nanoparticles  

SciTech Connect

Metal oxide and oxyhydroxide nanoparticles are important components of natural aqueous systems and have application in photocatalysis. Uncoated (oxyhydr)oxide nanoparticles can form charge-stabilized colloids in water, but the precise regimes of dispersion and aggregation have been determined for very few nanomaterials. We studied the colloidal behavior of {approx}6 nm nanoparticles of iron oxyhydroxide (FeOOH), a common natural nanoscale colloid, and found that these nanoparticles formed stable suspended clusters under a range of aqueous conditions. Light and X-ray scattering methods show that suspended fractal nanoclusters are formed between pH 5 and 6.6 with well-defined maximum diameters that can be varied from 25 nm to approximately 1000 nm. The nanoclusters retain a very high surface area, and persist in suspension for at least 10 weeks in solution. The process is partially reversible because optically transparent suspensions are regained when nanoparticles that aggregated and settled at pH >7 are adjusted to pH 4 without stirring. However, completely redispersed nanoparticles are not obtained even after one month. Because nanocluster formation is controlled predominantly by surface charge, we anticipate that many metal oxide and other inorganic nanoparticles will exhibit equivalent cluster-forming behavior. Our results indicate that natural nanoparticles could form stable nanoclusters in groundwater that are likely to be highly mobile, with implications for the long-range transport of surface sorbed contaminants.

Gilbert, B.; Lu, G.; Kim, C.S.

2007-07-09

12

The nanosphere iron mineral(s) in Mars soil  

NASA Technical Reports Server (NTRS)

A series of surface-modified clays containing nanophase (np) iron/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these 'Mars-soil analogs' were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxyl mineral such as 'green rust', or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable meaghemite (gamma-Fe203) by mild heat treatment and then to nanophase hematite (aplha-Fe203) by extensive heat treatment. Their chemical reactivity offers a plausible mechanism for the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxide and silicate phase surfaces. The mode of formation of these (nanophase) iron oxides on Mars is still unknown.

Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

1993-01-01

13

The nanosphere iron mineral(s) in Mars soil  

NASA Astrophysics Data System (ADS)

A series of surface-modified clays containing nanophase (np) iron/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these 'Mars-soil analogs' were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxyl mineral such as 'green rust', or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable meaghemite (gamma-Fe203) by mild heat treatment and then to nanophase hematite (aplha-Fe203) by extensive heat treatment. Their chemical reactivity offers a plausible mechanism for the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxide and silicate phase surfaces. The mode of formation of these (nanophase) iron oxides on Mars is still unknown.

Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

1993-11-01

14

Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge  

E-print Network

Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge kgÃ?1 (German and von Damm, 2004). As vented hydrothermal fluids mix with cold, oxygenated deep in mid-ocean ridge (MOR) hydrothermal end-member fluids at concentrations ranging from 0.007 to 25 mmol

15

The immobilization of U(vi) on iron oxyhydroxides under various physicochemical conditions.  

PubMed

The immobilization of U(vi) at the solid-water interface is an important process affecting its transportation and migration in the environment, and is predominantly controlled by the sorption behavior of U(vi). In this study, U(vi) sorption on Fe(ii) and Fe(iii) oxyhydroxides prepared by a coprecipitation method was studied under a range of physicochemical conditions, including pH, ionic strength, presence of humic acid (HA) and temperature. The results showed that the sorption of U(vi) on iron oxyhydroxides is chemical, and that the principal rate limitation is due to intraparticle diffusion. The sorption of U(vi) on iron oxyhydroxides is strongly dependent on pH, but only weakly dependent on ionic strength through the entire pH range studied. Under acidic conditions, the presence of HA increases U(vi) sorption to a large degree, but an inhibiting effect on the sorption of U(vi) can be observed under alkaline conditions, due to the formation of soluble U(vi)-HA complexes. The sorption of U(vi) on iron oxyhydroxides is an endothermic process and favors high temperatures. The surface complexation model suggests three dominant monodentate inner-sphere complexes of [triple bond, length as m-dash]Fe(s)OUO2(+) (log?K = 1.65), [triple bond, length as m-dash]Fe(w)OUO2OH(0) (log?K = -8.00), and [triple bond, length as m-dash]Fe(w)OUO2(CO3)2(3-) (log?K = 17.50), contributing to U(vi) sorption on iron oxyhydroxides over the entire observed pH range. PMID:25043996

Ping, Li; Zhuoxin, Yin; Jianfeng, Lin; Qiang, Jin; Yaofang, Du; Qiaohui, Fan; Wangsuo, Wu

2014-10-01

16

To improve the performance of sediment microbial fuel cell through amending colloidal iron oxyhydroxide into freshwater sediments.  

PubMed

Effects of iron oxide amendment into freshwater sediments on performance of sediment microbial fuel cell (SMFC) were investigated. It was found that amending amorphous bulk ferric oxyhydroxide, and crystalline goethite and magnetite did not affect SMFC operation. However, amendment of the mixed solution including soluble ferric citrate and colloidal iron oxyhydroxide, stably improved SMFC performance with voltage outputs up to threefolds higher than those without amendment. The enhanced voltage production corresponded to lower anode potential, but was not related to organic matter removal in sediments. Further experiments demonstrated that colloidal iron oxyhydroxide instead of soluble ferric iron played an important role in voltage production through maintaining high-concentration ferrous iron in pore water of sediments as electron shuttle and for chemical oxidation on the anode. Thus, colloidal iron oxyhydroxide amendment was a promising strategy to improve power production from SMFC employed in sediments especially with low content of organic matters. PMID:24657753

Zhou, Yan-Li; Yang, Ying; Chen, Mo; Zhao, Zhi-Wei; Jiang, He-Long

2014-05-01

17

Surface complexation effects on phosphate adsorption to ferric iron oxyhydroxides along pH and salinity gradients in estuaries and coastal aquifers  

NASA Astrophysics Data System (ADS)

Non-conservative behavior of dissolved inorganic phosphate (DIP) in estuaries is generally ascribed to desorption from iron and aluminum (hydr)oxides with increasing salinity. Here, we assess this hypothesis by simulating the reversible adsorption of phosphate onto a model oxide (goethite) along physico-chemical gradients representative of surface and subsurface estuaries. The simulations are carried out using a surface complexation model (SCM), which represents the main aqueous speciation and adsorption reactions of DIP, plus the ionic strength-dependent coulombic interactions in solution and at the mineral-solution interface. According to the model calculations, variations in pH and salinity alone are unlikely to explain the often reported production of DIP in surface estuaries. In particular, increased aqueous complexation of phosphate by Mg 2+ and Ca 2+ ions with increasing salinity is offset by the formation of ternary Mg-phosphate surface complexes and the drop in electrical potential at the mineral-water interface. However, when taking into account the downstream decrease in the abundance of sorption sites, the model correctly simulates the observed release of DIP in the Scheldt estuary. The sharp increase in pH accompanying the admixing of seawater to fresh groundwater should also cause desorption of phosphate from iron oxyhydroxides during seawater intrusion in coastal aquifers. As for surface estuaries, the model calculations indicate that significant DIP release additionally requires a reduction in the phosphate sorption site density. In anoxic aquifers, this can result from the supply of seawater sulfate and the subsequent reductive dissolution of iron oxyhydroxides coupled to microbial sulfate reduction.

Spiteri, Claudette; Cappellen, Philippe Van; Regnier, Pierre

2008-07-01

18

Mineralogy and inorganic chemistry of naturally occurring biogenic iron oxyhydroxides: Spectroscopic evidence of thermal maturation  

NASA Astrophysics Data System (ADS)

Microbial mats were sampled at four sites at the Lo'ihi Seamount and examined for changes in mineralogy and inorganic chemistry via synchrotron-sourced X-ray Absorption Spectroscopy (XAS). These mats are rich in iron oxyhydroxides with morphologies similar to those produced by iron oxidizing microorganisms related to Zetaproteobacteria such as Mariprofundus ferroxydans, which have been shown to be present and active in all of these mat ecosystems. The same particle morphologies are observed consistently at all four sites, which range in temperature (4 - 40°C) and hydrothermal activity (dead to very active). Fe L-edge XAS reveals no significant differences in Fe speciation between the morphologies. Mineralogy, however, as reflected in O 1s XAS measurements, appears to be a function of thermal maturation with the hottest site harboring more crystalline particles. Morphology does not factor into the changes in mineralogy. These measurements are confirmed by Fe 1s XAS spectroscopy. The C 1s XAS spectroscopy is highly variable and may be related to overall maturation (age) or undetermined factors. Elucidating the effect of thermal maturation on biogenic iron oxhydroxide particles is essential to understanding the environmental influences on their preservation in the rock record.

Haddad, A.; Fakra, S.; Orcutt, B. N.; Toner, B.; Edwards, K. J.

2011-12-01

19

Novel iron oxyhydroxide lepidocrocite nanosheet as ultrahigh power density anode material for asymmetric supercapacitors.  

PubMed

A simple one-step electroplating route is proposed for the synthesis of novel iron oxyhydroxide lepidocrocite (?-FeOOH) nanosheet anodes with distinct layered channels, and the microstructural influence on the pseudocapacitive performance of the obtained ?-FeOOH nanosheets is investigated via in situ X-ray absorption spectroscopy (XAS) and electrochemical measurement. The in situ XAS results regarding charge storage mechanisms of electrodeposited ?-FeOOH nanosheets show that a Li(+) can reversibly insert/desert into/from the 2D channels between the [FeO6 ] octahedral subunits depending on the applied potential. This process charge compensates the Fe(2+) /Fe(3+) redox transition upon charging-discharging and thus contributes to an ideal pseudocapacitive behavior of the ?-FeOOH electrode. Electrochemical results indicate that the ?-FeOOH nanosheet shows the outstanding pseudocapacitive performance, which achieves the extraordinary power density of 9000 W kg(-1) with good rate performance. Most importantly, the asymmetric supercapacitors with excellent electrochemical performance are further realized by using 2D MnO2 and ?-FeOOH nanosheets as cathode and anode materials, respectively. The obtained device can be cycled reversibly at a maximum cell voltage of 1.85 V in a mild aqueous electrolyte, further delivering a maximum power density of 16 000 W kg(-1) at an energy density of 37.4 Wh kg(-1). PMID:24850774

Chen, Ying-Chu; Lin, Yan-Gu; Hsu, Yu-Kuei; Yen, Shi-Chern; Chen, Kuei-Hsien; Chen, Li-Chyong

2014-09-24

20

Remote Sensing of Soils, Minerals, and Geomorphology  

E-print Network

the soil taxonomy (Petersen, 19Remote Sensing of Soils, Minerals, and Geomorphology Remote Sensing of Soils,Remote Sensing of Soils, Minerals, and GeomorphologyMinerals, and Geomorphology · 26% of the Earth's surface is exposed

21

The Formation and Aggregation of Iron Oxyhydroxide Nanoparticles in the Aqueous Environment  

NASA Astrophysics Data System (ADS)

This dissertation consists of four studies, which seek explain how iron oxyhydroxide nanoparticles nucleate and develop new structures via aggregation, within the aqueous environment. The aim of the first study is to determine the structure of ferrihydrite nanoparticle aggregates in aqua. This is achieved using complimentary cryo-TEM and SAXS methodologies. Ferrihydrite nanoparticles are known to form complex aggregate structures. Interpretation of SAXS data is difficult due to suspension polydispersity. Cryo-ET is used to obtain three-dimensional images of the nanoparticle suspensions. A variety of aggregate structures are observed, with branched networks of linear chains of particles being prevalent in most suspensions. The tomographic structural models are processed to determine aggregate fractal dimensions, using an autocorrelation function based approach. These results are combined with SAXS data to obtain a more comprehensive understanding of the suspension complexity. The networks of linear chains are shown to possess low fractal dimensions, between 1.0 and 1.4; significantly lower than would be expected from traditional models for aggregation. This has important consequences for the aggregate's physical behavior, and allows very large aggregates to exist in stable colloidal suspension without flocculation. The second study addresses how the ferrihydrite aggregate structure responds to changes in the ionic strength of the suspension, and how low-dimensional aggregate structures may influence nanoparticle transport through subsurface environments. Introducing ferrihydrite particle aggregates into solutions of 2 mM to 50 mM NaNO3 is shown to induce aggregate collapse, with more salt leading to the formation of denser aggregate structures and eventual flocculation. Complementary experiments show that millimolar quantities of NaNO3 induce a fundamental change in nanoparticle transport through a saturated quartz sand column. In deionized water, where low fractal dimension aggregates are stable, nanoparticles deposit evenly throughout the column, which soon saturates with particles so that subsequent injections are transported freely. When conditions favor aggregate collapse, dense localized accumulations occur and more nanoparticles can be deposited within the column. These deposits may be mechanically unstable, leading to irregular transport behavior. In the third study, the relationship between aggregation and iron oxyhydroxide phase transformations is explored. Previous researchers have found that akaganeite (beta-FeOOH) nanoparticles transform to create hematite (?-Fe2 O3) nano-spindles in response to hydrothermal aging, but the mechanism of transformation is unknown. Some researchers have proposed a process based on the aggregation of hematite precursors, while others advocated for dissolution and re-precipitation mechanisms. In this study, the kinetics of the phase transformation from akaganeite to hematite is studied, and cryo-TEM is used to characterize the aggregate structures in the transforming suspension. The hematite spindles are shown to be nanoporous, while akaganeite nanoparticles display a tendency for oriented aggregation. Hematite spindles are frequently found in intimate contact with akaganeite nanoparticle aggregates during the process of phase transformation, suggesting a model for phase transformation in which the dehydration of akaganeite to form hematite is enhanced by aggregation. In the final study, the nucleation and growth of akaganeite nanoparticles from acidic (pH 1.5-3) FeCl3 solutions is tracked with in situ small angle x-ray scattering (SAXS). The hydrothermal precipitation process studied can generate highly monodisperse particles, whose size, shape, and nucleation rate can be tuned by varying solution saturation and temperature. Classical nucleation modeling is applied to determine new values for the interfacial energy of ferric oxyhydroxide clusters. The interfacial energy (interfacial tension) of the nucleus is shown to be pH dependent and ranges from 0.06 to 0.12 J/m2 within the

Legg, Benjamin Adam

22

Mineralization of Iron Oxyhydroxides in the Presence and in the Absence of Bacterial Cells  

NASA Astrophysics Data System (ADS)

Because of their small size, iron oxides have a large surface area per unit weight ratio and are believed to play an important role as an adsorbing phase in lake sediments for various molecules, including potentially dangerous ones like heavy metals. They have been observed to form in close association with bacterial cells, by oxidation of ferrous ions. It is thus important to determine whether the presence of the bacterial cells can affect the mineralogy and the mesoscopic structure of the Fe-oxides particles, as well as their reactivity towards heavy metals. We synthesized in the lab nanoparticles of Fe-oxides by oxidation of ferrous ions. This was done in the presence and in the absence of various bacterial strains (Escherichia coli, Bacillus subtilis, Pseudomonas Aeruginosa and Bacillus licheniformis) and of inorganic ligands (sulfate, phosphate, silicate). The Fe-oxides particles were then observed by TEM on thin sections and on whole mounts. The chemical composition was estimated by wet chemistry and by EDS. The mineralogy was determined by XRD, SAED and EXAFS. Surface area was investigated by BET. And adsorption of cadmium was also measured at various pH. We observed that the size and the morphology of the particles as well as their mesoscopic spatial organization can be affected by the presence of the cells, whereas the mineralogy is controlled by the chemistry of the solution. The adsorption isotherms of cadmium on the various Fe-oxides will be discussed at the light of these observations.

Châtellier, X.; West, M.; Rose, J.; Fortin, D.; Leppard, G. G.; Ferris, G.

2001-12-01

23

High-intensity ultrasonication as a way to prepare graphene/amorphous iron oxyhydroxide hybrid electrode with high capacity in lithium battery.  

PubMed

The preparation of graphene/iron oxyhydroxide hybrid electrode material with very homogeneous distribution and close contact of graphene and amorphous iron oxyhydroxide nanoparticles has been achieved by using high-intensity ultrasonication. Due to the negative charge of the graphene surface, iron ions are attracted toward the surface of dispersed graphene, according to the zeta potential measurements. The anchoring of the FeO(OH) particles to the graphene layers has been revealed by using mainly TEM, XPS and EPR. TEM observations show that the size of the iron oxide particles is about 4nm. The ultrasonication treatment is the key parameter to achieve small particle size in these graphene/iron oxyhydroxide hybrid materials. The electrochemical behavior of composite graphene/amorphous iron oxyhydroxide prepared by using high-intensity ultrasonication is outstanding in terms of gravimetric capacity and cycling stability, particularly when metallic foam is used as both the substrate and current collector. The XRD-amorphous character of iron oxyhydroxide in the hybrid electrode material and the small particle size contribute to achieve the improved electrochemical performance. PMID:25499466

González, José R; Menéndez, Rosa; Alcántara, Ricardo; Nacimiento, Francisco; Tirado, José L; Zhecheva, Ekaterina; Stoyanova, Radostina

2015-05-01

24

Aggregation of nanoscale iron oxyhydroxides and corresponding effects on metal uptake, retention, and speciation: II. Temperature and time  

NASA Astrophysics Data System (ADS)

The aggregation and growth of nanosized particles can greatly impact their capacity to sorb and retain dissolved metals, thus affecting metal fate and transport in contaminated systems. Aqueous suspensions of synthesized nanoscale iron oxyhydroxides were exposed to dissolved Zn(II) or Cu(II) and aged at room temperature (?20 °C), 50 °C, and 75 °C for timeframes ranging from 0 to 96 h before sorbed metal ions were desorbed by lowering the suspension pH. Atomic absorption spectroscopic analysis of supernatants both before and after the desorption step determined how temperature and time affect macroscopic metal uptake and retention capacities. Extended X-ray absorption fine structure (EXAFS) spectroscopy analysis described the local binding environment of the sorbed/retained metals on the solid phase. With increasing aging temperature and time, the initial ?5-nm oblong nanoparticles formed dense aggregates, lost reactive surface area, and retained progressively larger fractions of the initially-introduced Zn(II) and Cu(II) following the desorption step, with the copper species inhibiting the oriented aggregation of the nanoparticles into nanorods. Based on EXAFS analysis, the speciation of the sorbed metal species evolves with increasing time and temperature from surface-sorbed metal ions, which readily desorb and return to solution, to more strongly-bound, structurally-incorporated metal ions. These retained metals appear to associate intimately with the nanoparticle aggregates by substituting for iron in the nanoparticle lattice or by binding within nanoparticle aggregate pore spaces.

Stegemeier, J. P.; Reinsch, B. C.; Lentini, C. J.; Dale, J. G.; Kim, C. S.

2015-01-01

25

Chapter 6 Associations between Iron Oxyhydroxide Nanoparticle Growth and Metal Adsorption\\/Structural Incorporation  

Microsoft Academic Search

The interaction of metal ions and oxyanions with nanoscale mineral phases has not been extensively studied despite the increased recognition of their prevalence in natural systems as a significant component of geomedia. A combination of macroscopic uptake studies to investigate the adsorption behavior of As(V), Cu(II), Hg(II), and Zn(II) onto nanoparticulate goethite (?-FeOOH) as a function of aging time at

C. S. Kim; C. J. Lentini; G. A. Waychunas

2007-01-01

26

Development of a reactive force field for iron-oxyhydroxide systems.  

PubMed

We adopt a classical force field methodology, ReaxFF, which is able to reproduce chemical reactions, and train its parameters for the thermodynamics of iron oxides as well as energetics of a few iron redox reactions. Two parametrizations are developed, and their results are compared with quantum calculations or experimental measurements. In addition to training, two test cases are considered: the lattice parameters of a selected set of iron minerals, and the molecular dynamics simulation of a model for alpha-FeOOH (goethite)-water interaction. Reliability and limitations of the developed force fields in predicting structure and energetics are discussed. PMID:20455552

Aryanpour, Masoud; van Duin, Adri C T; Kubicki, James D

2010-06-01

27

Adsorption of antimony onto iron oxyhydroxides: adsorption behavior and surface structure.  

PubMed

Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl3, was oxidized into Sb(V) probably due to the involvement of O2 in the long duration of sample preservation. Only one Sb-Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0-1.9 attributed to bidentate mononuclear edge-sharing ((2)E) between Sb and HFO. PMID:24910911

Guo, Xuejun; Wu, Zhijun; He, Mengchang; Meng, Xiaoguang; Jin, Xin; Qiu, Nan; Zhang, Jing

2014-07-15

28

Neptunium and Plutonium Sorption to Snake River Plain, Idaho Soil  

SciTech Connect

The behavior of Np and Pu on soil collected from the subsurface disposal area at the Idaho National Engineering and Environmental Laboratory was investigated by performing short-duration, sorption experiments to measure sorption isotherms. Neptunium sorption can be described with a Freundlich isotherm; however, Pu sorption can only be described in this fashion as a conservative estimate of minimum sorption. Geochemical modeling predictions suggest that initial sorption of Np is controlled predominantly by surface complexation on clay minerals, while Pu is controlled by a competition between complexation with iron oxyhydroxides and the precipitation of hydrolysis products. Longer-term sorption is governed by the transformation of these species to oxide minerals. Solution ionic strength and carbonate alkalinity did not significantly affect Np or Pu soil sorption.

Mincher, Bruce Jay; Fox, Robert Vincent; Cooper, David Craig; Groenewold, Gary Steven

2003-07-01

29

Nitrogen mineralization in a tussock tundra soil  

SciTech Connect

The effects of substrate quality, temperature, and moisture on nitrogen mineralization from a tussock tundra soil were examined with laboratory soil incubations utilizing both air-dried samples and field-moist intact cores. The potentially mineralizable nitrogen (PMN) was highly correlated to both total soil nitrogen (positively) and the carbon/nitrogen ratio (negatively). All soil horizons exhibited a net nitrogen mineralization even at a high carbon/nitrogen ratio of 92. It was concluded that field-moist intact soil cores provide a more reliable estimate than the air-dried samples of both PMN and the mineralization rate under standard laboratory conditions. There was no significant effect of moisture tension (0.0 to 0.4 bars) on net nitrogen mineralization. The average Q/sub 10/ (temperature effect) for net nitrogen mineralization was 2.5. Based on this study and others, it was concluded that temperature through its effect on nitrogen mineralization plays an important role in controlling plant productivity in these naturally nitrogen-deficient tundra ecosystems.

Marion, G.M.; Miller, P.C.

1982-01-01

30

Electrokinetic properties of soil minerals and soils modified with polyelectrolytes  

NASA Astrophysics Data System (ADS)

The formation features of nanoadsorption polyelectrolyte (PE) layers with the formation of a mineral-organic matrix on the surface of clay minerals and soils (kaolinite, montmorillonite, quartz sand, gray forest soil, and chernozemic soil) have been elucidated by direct adsorption measurements. It has been found that the experimental values for the limit adsorption of polyacrylamide (PAM) and polyacrylic acid (PAA) on all the minerals are significantly higher than the calculated values for the formation of a monolayer. This indicates adsorption on the surface of not only separate macromolecules but also secondary PE structures as packets or fibrils determining the cluster-matrix structure of the modified surface. The study of the electro-surface properties (electrophoretic mobility, electrokinetic potential, pH, and electroconductivity) of mineral and soil particles adsorption-modified with PEs has confirmed the differences in the adsorption mechanisms (from physical sorption to chemisorption) with the formation of surface compounds depending on the different polar groups of PEs and the mineral type.

Kurochkina, G. N.; Pinskii, D. L.; Haynos, M.; Sokolowska, Z.; Tsesla, I.

2014-07-01

31

Aggregation of nanoscale iron oxyhydroxides and corresponding effects on metal uptake, retention, and speciation: I. Ionic-strength and pH  

NASA Astrophysics Data System (ADS)

The capacity of nanosized particles to adsorb and sequester dissolved metals can be significantly impacted by the mechanism and extent of aggregation the particles have undergone, which in turn can affect the long-term fate and transport of potentially toxic metals in natural aqueous systems. Suspensions of monodisperse nanoscale iron oxyhydroxides were synthesized and subjected to increased pH (pH 8.0, 10.0) or ionic strength (0.1, 1.0 M NaNO3) conditions to induce various states of aggregation prior to conducting macroscopic adsorption/desorption experiments with dissolved Cu(II) or Zn(II). The metal adsorption and retention capacities of the nanoparticle aggregates were compared to one another and to non-aggregated control nanoparticles, while the mode(s) of metal sorption to the nanoparticle surfaces were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. With increasing aggregation by both pH and ionic strength, the proportion of introduced zinc adsorbed to the iron oxyhydroxide nanoparticles progressively decreased from 45% on the monodispersed control particles to as low as 16% on the aggregates, while the proportion of introduced zinc retained upon desorption (obtained by lowering the suspension pH) increased from 7% on the control particles to as much as 17% on the aggregated particles. Copper exhibited a subtler trend of only slightly declining uptake (from 43% to 36%) and retention (from 35% to 30%) with increasing aggregation state. EXAFS analysis was consistent with the macroscopic results, showing relatively little change in Cu speciation between samples analyzed before and after the desorption step but significant increases in Zn-Fe interatomic distances and coordination numbers after desorption. This suggests the presence of both strongly- and weakly-bound zinc ions; the latter are likely affiliated with less stable, more distorted surface sorption sites and are thus more readily desorbed, resulting in the retention of zinc that is bound to more stable, less-distorted sorption sites. For both metals, inner-sphere bidentate sorption appears to dominate the sorption process to the nanoparticle aggregates, with potential structural incorporation into the aggregates themselves.

Dale, J. G.; Stegemeier, J. P.; Kim, C. S.

2015-01-01

32

Pentachlorophenol mineralization in an immobilized soil bioreactor  

SciTech Connect

The biological degradation of pentachlorophenol (PCP) was conducted in a new type of reactor-the immobilized soil bioreactor. In this bioreactor soil particles having natural microbial activity in degrading the target pollutant are entrapped into a solid membrane with a large pore size distribution. The resulting {open_quotes}immobilized soil{close_quotes} system can be easily supplied with dissolved mineral salts, oxygen and target pollutant and as a result an active microbial consortium will be quickly established. This consortium is later used for treatment of aqueous solutions of the pollutant, for instance, contaminated ground water. We have studied the process of PCP biodegradation in both batch and continuous regime. our results showed that the volumetric effectiveness of the process of PCP mineralization in the immobilized soil bioreactor is between 7 and 4000 times higher than results reported in the literature. It has been found that both chlorine and carbon atoms of PCP are at least 99% mineralized. 7 refs., 4 figs., 1 tab.

Karamanev, D.; Chavarie, C.; Samson, R. [Ecole Polytechnique, Montreal (Canada)

1996-12-31

33

Poliovirus Adsorption by 34 Minerals and Soils  

PubMed Central

The adsorption of radiolabeled infectious poliovirus type 2 by 34 well-defined soils and mineral substrates was analyzed in a synthetic freshwater medium containing 1 mM CaCl2 and 1.25 mM NaHCO3 at pH 7. In a model system, adsorption of poliovirus by Ottawa sand was rapid and reached equilibrium within 1 h at 4°C. Near saturation, the adsorption could be described by the Langmuir equation; the apparent surface saturation was 2.5 × 106 plaque-forming units of poliovirus per mg of Ottawa sand. At low surface coverage, adsorption was described by the Freundlich equation. The soils and minerals used ranged from acidic to basic and from high in organic content to organic free. The available negative surface charge on each substrate was measured by the adsorption of a cationic polyelectrolyte, polydiallyldimethylammonium chloride. Most of the substrates adsorbed more than 95% of the virus. In general, soils, in comparison with minerals, were weak adsorbents. Among the soils, muck and Genesee silt loam were the poorest adsorbents; among the minerals, montmorillonite, glauconite, and bituminous shale were the least effective. The most effective adsorbents were magnetite sand and hematite, which are predominantly oxides of iron. Correlation coefficients for substrate properties and virus adsorption revealed that the elemental composition of the adsorbents had little effect on poliovirus uptake. Substrate surface area and pH, by themselves, were not significantly correlated with poliovirus uptake. A strong negative correlation was found between poliovirus adsorption and both the contents of organic matter and the available negative surface charge on the substrates as determined by their capacities for adsorbing the cationic polyelectrolyte, polydiallyldimethylammonium chloride. PMID:6274259

Moore, Rebecca S.; Taylor, Dene H.; Sturman, Lawrence S.; Reddy, Michael M.; Fuhs, G. Wolfgang

1981-01-01

34

Biogeophysical factors inuencing soil respiration and mineral nitrogen content in an old eld soil  

E-print Network

Biogeophysical factors in¯uencing soil respiration and mineral nitrogen content in an old ®eld soil, soil respiration and mineral N concentrations in an old ®eld ®ve times during the course of a year. We, suggest that under our driest sampling conditions, soil respiration and mineral N content were controlled

Neher, Deborah A.

35

Humic acid facilitates the transport of ARS-labeled hydroxyapatite nanoparticles in iron oxyhydroxide-coated sand  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydroxyapatite nanoparticles (nHAP) have been widely used to remediate soil and wastewater contaminated with metals and radionuclides. However, our understanding of nHAP transport and fate is limited in natural environments that exhibit significant variability in solid and solution chemistry. The tr...

36

The nanophase iron mineral(s) in Mars soil  

NASA Technical Reports Server (NTRS)

A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism for, the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxides and silicate phase surfaces. The reflectance spectrum of the clay-iron preparations in the visible range is generally similar to the reflectance curves of bright regions on Mars. This strengthens the evidence for the predominance of nanophase iron oxides/oxyhydroxides in Mars soil. The mode of formation of these nanophase iron oxides on Mars is still unknown. It is puzzling that despite the long period of time since aqueous weathering took place on Mars, they have not developed from their transitory stage to well-crystallized end-members. The possibility is suggested that these phases represent a continuously on-going, extremely slow weathering process.

Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

1993-01-01

37

Adsorption of reovirus by minerals and soils.  

PubMed Central

Adsorption of [35S]methionine-labeled reovirus by 30 dry soils, minerals, and finely ground rocks suspended in synthetic freshwater at pH 7 was investigated to determine the conditions necessary for optimum virus removal during land application of wastewaters. All of the minerals and soils studied were excellent adsorbents of reovirus, with greater than 99% of the virus adsorbed after 1 h at 4 degrees C. Thereafter, virus remaining in suspension was significantly inactivated, and within 24 h a three to five log10 reduction in titer occurred. The presence of divalent cations, i.e., Ca2+ and Mg2+, in synthetic freshwater enhanced removal, whereas soluble organic matter decreased the amount of virus adsorbed in secondary effluent. The amount of virus adsorbed by these substrates was inversely correlated with the amount of organic matter, capacity to adsorb cationic polyelectrolyte, and electrophoretic mobility. Adsorption increased with increasing available surface area, as suspended infectivity was reduced further by the more finely divided substrates. However, the organic content of the soils reduced the level of infectious virus adsorbed below that expected from surface area measurements alone. The inverse correlation between virus adsorption and substrate capacity for cationic polyelectrolyte indicates that the adsorption of infectious reovirus particles is predominately a charged colloidal particle-charged surface interaction. Thus, adsorption of polyelectrolyte may be useful in predicting the fate of viruses during land application of sewage effluents and sludges. PMID:7149717

Moore, R S; Taylor, D H; Reddy, M M; Sturman, L S

1982-01-01

38

[Organic carbon and carbon mineralization characteristics in nature forestry soil].  

PubMed

Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction. PMID:24881403

Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

2014-03-01

39

Study of mineralogical speciation of arsenic in soils using X ray microfluorescence and scanning electronic microscopy.  

PubMed

In this paper we studied the As content in natural contaminated soils, classified as Dystric Leptosol, Chromic Luvisol, Eutric Cambisol and Mollic Leptosol. In soil samples, sieved (<2mm), total As was determined by XRF and chemical speciation by sequential extraction. As-bearing minerals were concentrated from fine sand fraction of soil (200-20 ?m) using heavy liquid. In this fraction, mineralogical speciation was studied by X-ray microfluorescence, XRD with Göbbel mirror and SEM-BEI-EDX. Total As contents ranging from 61.00 to 131.00 mg kg(-1). The results of the sequential extraction showed that As was, mainly, in the residual fraction (52.51-98.76 mg kg(-1)) and in the fraction bound to iron oxyhydroxides (0-36.5 mg kg(-1)). Mapping of As with X-ray microfluorescence show strongly relationship between Fe and As. Iron (III) oxyhydroxides (FeOHs) (lepidocrocite and goethite), scorodite, angelellite, schultenite and dussertite were identified by XRD analysis as most likely mineral phases. The contents of As, Fe, Pb and Ba obtained with EDX-microprobe, confirmed the results of XRD. The results of sequential extraction and X-ray microfluorescence indicate that As is strongly bound to the soils because the identified As-bearing mineral phases are very stable at the pH conditions of studied soils. Consequently, a low mobility of As can be assumed in these soils. PMID:21482293

Gómez-Parrales, Isidoro; Bellinfante, Nicolás; Tejada, Manuel

2011-05-15

40

Relationship between carbon and nitrogen mineralization in a subtropical soil  

NASA Astrophysics Data System (ADS)

In most soils, more than 90% nitrogen is bonded with carbon in organic forms. This indicates that carbon mineralization should be closely coupled with nitrogen mineralization, showing a positive correlation between carbon and nitrogen mineralization. To test this hypothesis above, we conducted an incubation using a subtropical soil for 10 days at 15 °C and 25 °C. 13C-labeled glucose and 15N-labeled ammonium or nitrate was used to separate CO2 and mineral N released from mineralization of soil organic matter and added glucose or inorganic nitrogen. Phospholipid fatty acid (PLFA) and four exoenzymes (i.e. ?-1,4- Glucosaminidase, chitinase, acid phosphatase, ?-1,4-N- acetyl glucosamine glycosidase) were also analyzed to detect change in microbial activities during the incubation. Our results showed that CO2 release decreased with increasing nitrogen mineralization rates. Temperature did not change this relationship between carbon and nitrogen mineralization. Although some changes in PLFA and the four exoenzymes were observed, these changes did not contribute to changes in carbon and nitrogen mineralization. These findings indicates that carbon and nitrogen mineralization in soil are more complicated than as previously expected. Future investigation should focus on why carbon and nitrogen mineralization are coupled in a negative correlation not in a positive correlation in many soils for a better understanding of carbon and nitrogen transformation during their mineralization.

Li, Qianru; Sun, Yue; Zhang, Xinyu; Xu, Xingliang; Kuzyakov, Yakov

2014-05-01

41

Hydrogeomorphology influences soil nitrogen and phosphorus mineralization in floodplain wetlands  

USGS Publications Warehouse

Conceptual models of river–floodplain systems and biogeochemical theory predict that floodplain soil nitrogen (N) and phosphorus (P) mineralization should increase with hydrologic connectivity to the river and thus increase with distance downstream (longitudinal dimension) and in lower geomorphic units within the floodplain (lateral dimension). We measured rates of in situ soil net ammonification, nitrification, N, and P mineralization using monthly incubations of modified resin cores for a year in the forested floodplain wetlands of Difficult Run, a fifth order urban Piedmont river in Virginia, USA. Mineralization rates were then related to potentially controlling ecosystem attributes associated with hydrologic connectivity, soil characteristics, and vegetative inputs. Ammonification and P mineralization were greatest in the wet backswamps, nitrification was greatest in the dry levees, and net N mineralization was greatest in the intermediately wet toe-slopes. Nitrification also was greater in the headwater sites than downstream sites, whereas ammonification was greater in downstream sites. Annual net N mineralization increased with spatial gradients of greater ammonium loading to the soil surface associated with flooding, soil organic and nutrient content, and herbaceous nutrient inputs. Annual net P mineralization was associated negatively with soil pH and coarser soil texture, and positively with ammonium and phosphate loading to the soil surface associated with flooding. Within an intensively sampled low elevation flowpath at one site, sediment deposition during individual incubations stimulated mineralization of N and P. However, the amount of N and P mineralized in soil was substantially less than the amount deposited with sedimentation. In summary, greater inputs of nutrients and water and storage of soil nutrients along gradients of river–floodplain hydrologic connectivity increased floodplain soil nutrient mineralization rates.

Noe, Gregory B.; Hupp, Cliff R.; Rybicki, Nancy B.

2013-01-01

42

Coexisting Bacterial Populations Responsible for Multiphasic Mineralization Kinetics in Soil  

PubMed Central

Experiments were conducted to study populations of indigenous microorganisms capable of mineralizing 2,4-dinitrophenol (DNP) in two soils. Previous kinetic analyses indicated the presence of two coexisting populations of DNP-mineralizing microorganisms in a forest soil (soil 1). Studies in which eucaryotic and procaryotic inhibitors were added to this soil indicated that both populations were bacterial. Most-probable-number counts with media containing different concentrations of DNP indicated that more bacteria could mineralize low concentrations of DNP than could metabolize high concentrations of it. Enrichments with varying concentrations of DNP and various combinations of inhibitors consistently resulted in the isolation of the same two species of bacteria from soil 1. This soil contained a large number and variety of fungi, but no fungi capable of mineralizing DNP were isolated. The two bacterial isolates were identified as a Janthinobacterium sp. and a Rhodococcus sp. The Janthinobacterium sp. had a low ?max and a low Km for DNP mineralization, whereas the Rhodococcus sp. had much higher values for both parameters. These differences between the two species of bacteria were similar to differences seen when soil was incubated with different concentrations of DNP. Values for ?max from soil incubations were similar to ?max values obtained in pure culture studies. In contrast, Ks and Km values showed greater variation between soil and pure culture studies. The results of this study help to confirm predictions that two physiologically distinct bacterial populations are responsible for the multiphasic mineralization kinetics observed in the soil studied. PMID:16348277

Schmidt, S. K.; Gier, M. J.

1990-01-01

43

Fractionation of Fe isotopes by soil microbes and organic acids  

USGS Publications Warehouse

Small natural variations in Fe isotopes have been attributed to biological cycling. However, without understanding the mechanism of fractionation, it is impossible to interpret such variations. Here we show that the ?56Fe of Fe dissolved from a silicate soil mineral by siderophore-producing bacteria is as much as 0.8% lighter than bulk Fe in the mineral. A smaller isotopic shift is observed for Fe released abiotically by two chelates, and the magnitude of the shift increases with affinity of the ligand for Fe, consistent with a kinetic isotope effect during hydrolysis of Fe at the mineral surface. Fe dissolved abiotically without chelates shows no isotopic shift. The ?56Fe of the exchange fraction on soil grains is also lighter by ~0.6%-1% than Fe from both hornblende and iron oxyhydroxides. The kinetic isotope effect is therefore preserved in open systems such as soils. when recorded in the rock record, Fe isotopic fractionation could document Fe transport by organic molecules or by microbes where such entities were present in the geologic past.

Brantley, Susan L.; Liermann, Laura; Bullen, Thomas D.

2001-01-01

44

nt adsorptionby soil minerals,in Elenletils in Soil-Plant -Aninal  

E-print Network

-matterreactions involving [. Giordano, and W. L. Lindsay Soil ScienceSociety of America t of Fertilizers, Commonweahh0cesse.s nt adsorptionby soil minerals,in Elenletils in Soil-Plant - Aninal rrk. USA. .. ( l96l). Molybdenumreactions ium and titanium, Soil Sci. Soc. i on the exhaustion of sewage e chemistry of lead in soil: solid

Short, Daniel

45

Radon sources emanation in granitic soil and saprolite  

SciTech Connect

Petrological and geochemical examinations of soil, saprolite, and quartz diorite protolith have been made at the Small Structures field site, Ben Lomond Mountain, California. Variations in Ra in soil and saprolite are mainly controlled by heterogeneities inherited from the parent quartz diorite. Fission-track radiography shows that U is concentrated in the primary accessory minerals, zircon and sphene. However, most importantly for Rn emanation, U is also concentrated in secondary sites: weathered sphene, biotite and plagioclase, grain coatings, and Fe-rich fracture linings which also contain a rare-earth phosphate mineral. This occurrence of U along permeable fracture zones suggests that soil-gas Rn from depth (> 2 m) is a significant contributor to Rn availability near the surface. Zones highest in emanation occur where fine pedogenic phases: gibbsite, amorphous silica, and iron oxyhydroxide are most abundant. Mass balance analyses of this soil-saprolite profile are in progress and preliminary indicate that a high-emanation zone corresponds to the upper portion of a zone of accumulation of U and Ba.

Wollenberg, H.; Flexser, S. [Lawrence Berkeley Lab., CA (United States); Brimhall, G.; Lewis, C. [California Univ., Berkeley, CA (United States). Dept. of Geology and Geophysics

1993-08-01

46

Effect of Mineral and Organic Soil Constituents on Microbial Mineralization of Organic Compounds in a Natural Soil  

PubMed Central

This research addressed the effect of mineral and organic soil constituents on the fate of organic compounds in soils. Specifically, it sought to determine how the associations between organic chemicals and different soil constituents affect their subsequent biodegradation in soil. Four 14C-labeled surfactants were aseptically adsorbed to montmorillonite, kaolinite, illite, sand, and humic acids. These complexes were mixed with a woodlot soil, and 14CO2 production was measured over time. The mineralization data were fitted to various production models by nonlinear regression, and a mixed (3/2)-order model was found to most accurately describe the mineralization patterns. Different mineralization patterns were observed as a function of the chemical and soil constituents. Surfactants that had been preadsorbed to sand or kaolinite usually showed similar mineralization kinetics to the control treatments, in which the surfactants were added to the soil as an aqueous solution. Surfactants that had been bound to illite or montmorillonite were typically degraded to lesser extents than the other forms, while surfactant-humic acid complexes were degraded more slowly than the other forms. The desorption coefficients (Kd) of the soil constituent-bound surfactants were negatively correlated with the initial rates of degradation (k1) and estimates of 14CO2 yield (Po) as well as actual total yields of 14CO2. However, there was no relationship between Kd and second-stage zero-order rates of mineralization (ko). Microbial community characteristics (biomass and activity) were not correlated with any of the mineralization kinetic parameters. Overall, this study showed that environmental form had a profound effect on the ultimate fate of biodegradable chemicals in soil. This form is defined by the physicochemical characteristics of the chemical, the composition and mineralogy of the soil, and the mode of entry of the chemical into the soil environment. PMID:16349465

Knaebel, David B.; Federle, Thomas W.; McAvoy, Drew C.; Vestal, J. Robie

1994-01-01

47

Relevance of mineral-organic associations in cryoturbated permafrost soils  

NASA Astrophysics Data System (ADS)

Enhanced microbial decomposition of deep buried organic matter (OM) increase the release of CO2and CH4from high latitude ecosystems, thus being an uncertain but potentially crucial positive feedback to global warming. The role of soil minerals as stabilization agents of OM against microbial attack gain in importance as soon abiotic soil conditions will change in permafrost soils. We investigated changes in storage and turnover of soil organic carbon (OC) and total nitrogen (TN) associated with minerals in 27 cryoturbated permafrost soils from the west to the east Siberian Arctic. Furthermore, we studied the mineral composition and the potential of OM to interact with soil minerals via different binding mechanisms. Mineral-associated organic matter (MOM) was separated from particulate plant debris by density fractionation in sodium polytungstate (density cut-off 1.6 g cm-3). Their apparent 14C ages were determined by accelerator mass spectrometry and potential mineralization rates were analyzed in a 180 days incubation experiments at 5 and 15° C. The mineral composition was analyzed by X-ray diffraction and selective extractions. Desorption experiments (stepwise extraction with KCl and NaH2PO4) using the permafrost soils as well as reference soils from temperate regions (three Stagnolsols from Germany) were performed to study OM sorbed to mineral surfaces or complexed with polyvalent metal ions. The proportion of OC associated with minerals (MOC) ranged from 5.1 to 14.9 kg m-2 (average: 11.0 kg m-2), corresponding to ~55% from the total soil OC storage (average: 20.2 ± 8.0 kg m-2) in the first meter of the Cryosols. In contrast to temperate soils, where maximum MOC concentrations are present in topsoils, cambic, or spodic horizons, cryoturbation in permafrost soils leads to high MOC concentrations within the whole solum. Cryoturbated OM-rich pockets in the subsoil store 18% (2.0 ± 1.3 kg m-2) of the MOC while another 34% (3.8 ± 3.5 kg m-2) was located in the uppermost permafrost. In topsoil horizons, mineralization rates showed a similar pattern for MOM and the bulk soil controls. In contrast, even higher MOM respiration rates then the bulk control were found in the cryoturbated OM-rich pockets and permafrost horizons. These findings deviate from temperate soil environments where MOM is considered to contribute to a 'stabilized pool' with mean residence times from hundreds to thousands of years. Statistical analysis indicated that mineral-organic interactions primarily occurred with poorly crystalline Fe and Al phases and Fe/Al-OM complexes. However, the minor desorption of organic polyelectrolytes by NaH2PO4 in permafrost soils indicated that significantly lower amounts of OC were bound by ligand exchange to Fe and Al minerals or the edges of clay minerals in permafrost soils compared to the temperate reference soils. Therefore, stabilization of OM by mineral surfaces or polyvalent metal ions appears to be of minor relevance in arctic environments compared to temperate soils.

Gentsch, Norman; Mikutta, Robert; Bárta, Ji?í; ?apek, Petr; Gittel, Antje; Richter, Andreas; Šantr??ková, Hanna; Schnecker, Jörg; Shibistova, Olga; Urich, Tim; Wild, Birgit; Guggenberger, Georg

2014-05-01

48

Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils  

SciTech Connect

A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group minerals react to form U(VI)- bearing aluminum phosphates. (author)

Jerden, James L. Jr. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 (United States)

2007-07-01

49

Soil nitrogen mineralization as affected by water and temperature interactions  

Microsoft Academic Search

The hypothesis that water and temperature interact to influence the rate of soil N mineralization was studied in laboratory incubation experiments with two contrasting soils. Small sample rings (10 mm tall, 50 mm diameter) were packed to uniform bulk density with 1–2 mm aggregates of Plano silt loam and Wacousta silty clay loam. Samples were brought to five different water

Eileen J. Kladivko; Dennis R. Keeney

1987-01-01

50

Ectomycorrhizal fungi in mineral soil * AND N. ROSENSTOCK  

E-print Network

Ectomycorrhizal fungi in mineral soil A. ROSLING 1, * AND N. ROSENSTOCK 2 1 Department of Forest and Management, UC Berkeley, 321 Koshland Hall, Berkeley Ca, 94720, USA ABSTRACT Ectomycorrhizal fungi communities in boreal forest soils but functional differences within this group of fungi remain largely

Bruns, Tom

51

Glyphosate behavior at soil and mineral-water interfaces.  

PubMed

Adsorption isotherms and surface coverage of glyphosate, N-phosphonomethylglycine (PMG), in aqueous suspensions of three Argentine soils with different mineralogical composition were measured as a function of PMG concentration and pH. Zeta potential curves for PMG/soils system were also determined. Montmorillonite and soil sample surface charges were negative and increased as the amount of adsorbed PMG increased, showing that the surface complexes are more negative than those formed during the surface protonation. PMG adsorption on soils were described using Langmuir isotherms and the affinity constants, and the maximum surface coverage was estimated at pH 4 and 7 using a two-term Langmuir isotherm, the mineralogical composition percentages, and maximum surface coverage and Langmuir constants for pure minerals. The influence of organic matter (OM) and iron content of soils on the PMG adsorption was evaluated. The surface coverage of PMG decreased when the OM and iron content decreased for minerals and soils. PMID:18280020

Pessagno, Romina C; Torres Sánchez, Rosa M; dos Santos Afonso, María

2008-05-01

52

Kinetics of methane oxidation in selected mineral soils  

NASA Astrophysics Data System (ADS)

The kinetic parameters of methane oxidation in three mineral soils were measured under laboratory conditions. Incubationswere preceded by a 24-day preincubationwith 10%vol. of methane. All soils showed potential to the consumption of added methane. None of the soils, however, consumed atmospheric CH4. Methane oxidation followed the Michaelis-Menten kinetics, with relatively low values of parameters for Eutric Cambisol, while high values for Haplic Podzol, and especially for Mollic Gleysol which showed the highest methanotrophic activity and much lower affinity to methane. The high values of parameters for methane oxidation are typical for organic soils and mineral soils from landfill cover. The possibility of the involvement of nitrifying microorganisms, which inhabit the ammonia-fertilized agricultural soils should be verified.

Walkiewicz, A.; Bulak, P.; Brzeziñska, M.; W?odarczyk, T.; Polakowski, C.

2012-10-01

53

Effects of acidity on mineralization: pH-dependence of organic matter mineralization in weakly acidic soils  

Microsoft Academic Search

The literature is ambiguous regarding the influence of acidity on mineralization of soil organic matter. Although mineralization is often regarded as being relatively insensitive to acidity, reports of agronomically-significant increases in N mineralization after liming of acid soils are common. We analyzed 61 soils (pH 5.1–7.9), representing all agro-ecological zones of Saskatchewan, Canada, to determine the pH-dependence of N mineralization.

Denis Curtin; C. A. Campbell; Abdul Jalil

1998-01-01

54

[Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region].  

PubMed

Typical paddy and upland soils were collected from a hilly subtropical red-soil region. 14C-labeled dissolved organic carbon (14C-DOC) was extracted from the paddy and upland soils incorporated with 14C-labeled straw after a 30-day (d) incubation period under simulated field conditions. A 100-d incubation experiment (25 degrees C) with the addition of 14C-DOC to paddy and upland soils was conducted to monitor the dynamics of 14C-DOC mineralization under different soil moisture conditions [45%, 60%, 75%, 90%, and 105% of the field water holding capacity (WHC)]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO2. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex composition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil moisture (45% -90% WHC). Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% (paddy soil) and 66.3%-72.4% (upland soil) of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction. PMID:24984493

Chen, Xiang-Bi; Wang, Ai-Hua; Hu, Le-Ning; Huang, Yuan; Li, Yang; He, Xun-Yang; Su, Yi-Rong

2014-03-01

55

Adsorption coefficients for TNT on soil and clay minerals  

NASA Astrophysics Data System (ADS)

To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.

Rivera, Rosángela; Pabón, Julissa; Pérez, Omarie; Muñoz, Miguel A.; Mina, Nairmen

2007-04-01

56

Pedogenic Magnetic Minerals in Soils: Some Tests of Current Models  

NASA Astrophysics Data System (ADS)

The magnetic enhancement of soils is increasingly used as a proxy for continental climate, since it is related to the formation of pedogenic iron minerals under warm, humid conditions. Ultrafine magnetite is believed to be the major responsible of the magnetic enhancement, however, very little is known on the detailed formation mechanism, ant its relation to the soil iron cycle. Furthermore, the 'textbook' case of the Chinese Loess Plateau is not well replicated around the World: Loessic soils from the Midwestern US are systematically less enhanced than their Chinese counterpart under similar climatic conditions, and many loessic soils in Argentina are not enhanced at all. In trying to find a rationale behind these differences, I will address three main questions that need to be answered in a bottom-up approach to the problem. The first question is whether susceptibility is indeed controlled by fine magnetite, excluding any significant role of other minerals such as ferrihydrite, goethite, and hematite. This is a rock magnetic problem addressing the interpretation of magnetic measurements: is susceptibility an adequate proxy for the concentration of magnetic minerals in soils? Answering this question allows us to think directly in terms of abundance specific magnetic minerals, which is fundamental for any subsequent interpretation. The second question is directed to understanding the role of magnetic minerals in the soil iron cycle and how they are formed. This brings us to a discussion of the transfer function linking magnetic enhancement with climate. Is indeed rainfall the only parameter controlling pedogenesis? Why is rainfall apparently related with the logarithm of susceptibility in enhanced soils? Can we test current pedogenetic models against this empirical transfer function? The third question points to the role of parent material and later dust inputs. Midwestern US and Argentinian loesses are different from Chinese loess. Is this a reason for the differences observed in the magnetic enhancement of the respective soils? Enough material is now available to test current models and hypotheses with respect to the first two questions.

Egli, R.

2008-12-01

57

The effect of soil horizon and mineral type on the distribution of siderophores in soil  

NASA Astrophysics Data System (ADS)

Iron is a key component of the chemical architecture of the biosphere. Due to the low bioavailability of iron in the environment, microorganisms have developed specific uptake strategies like production of siderophores. Siderophores are operationally defined as low-molecular-mass biogenic Fe(III)-binding compounds, that can increase the bioavailability of iron by promoting the dissolution of iron-bearing minerals. In the present study, we investigated the composition of dissolved and adsorbed siderophores of the hydroxamate family in the soil horizons of podzol and the effect of specific mineral types on siderophores. Three polished mineral specimens of 3 cm × 4 cm × 3 mm (apatite, biotite and oligioclase) were inserted in the soil horizons (O (organic), E (eluvial) and B (upper illuvial)). After two years, soil samples were collected from both the bulk soil of the whole profile and from the soil attached to the mineral surfaces. The concentration of ten different fungal tri-hydroxamates within ferrichromes, fusigen and coprogens families, and five bacterial hydroxamates within the ferrioxamine family were detected. All hydroxamate types were determined in both soil water (dissolved) and soil methanol (adsorbed) extracts along the whole soil profile by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS); hence, the study is the most extensive of its kind. We found that coprogens and fusigen were present in much higher concentrations in bulk soil than were ferrioxamines and ferrichromes. On the other hand, the presence of the polished mineral completely altered the distribution of siderophores. In addition, each mineral had a unique interaction with the dissolved and adsorbed hydroxamates in the different soil horizons. Thus siderophore composition in the soil environment is controlled by the chemical, physical and biological characteristics of each soil horizon and also by the available mineral types.

Ahmed, Engy; Holmström, Sara J. M.

2014-04-01

58

Characterizing regional soil mineral composition using spectroscopyand geostatistics  

USGS Publications Warehouse

This work aims at improving the mapping of major mineral variability at regional scale using scale-dependent spatial variability observed in remote sensing data. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and statistical methods were combined with laboratory-based mineral characterization of field samples to create maps of the distributions of clay, mica and carbonate minerals and their abundances. The Material Identification and Characterization Algorithm (MICA) was used to identify the spectrally-dominant minerals in field samples; these results were combined with ASTER data using multinomial logistic regression to map mineral distributions. X-ray diffraction (XRD)was used to quantify mineral composition in field samples. XRD results were combined with ASTER data using multiple linear regression to map mineral abundances. We testedwhether smoothing of the ASTER data to match the scale of variability of the target sample would improve model correlations. Smoothing was donewith Fixed Rank Kriging (FRK) to represent the mediumand long-range spatial variability in the ASTER data. Stronger correlations resulted using the smoothed data compared to results obtained with the original data. Highest model accuracies came from using both medium and long-range scaled ASTER data as input to the statistical models. High correlation coefficients were obtained for the abundances of calcite and mica (R2 = 0.71 and 0.70, respectively). Moderately-high correlation coefficients were found for smectite and kaolinite (R2 = 0.57 and 0.45, respectively). Maps of mineral distributions, obtained by relating ASTER data to MICA analysis of field samples, were found to characterize major soil mineral variability (overall accuracies for mica, smectite and kaolinite were 76%, 89% and 86% respectively). The results of this study suggest that the distributions of minerals and their abundances derived using FRK-smoothed ASTER data more closely match the spatial variability of soil and environmental properties at regional scale.

Mulder, V.L.; de Bruin, S.; Weyermann, J.; Kokaly, Raymond F.; Schaepman, M.E.

2013-01-01

59

A disconnect between O horizon and mineral soil carbon - Implications for soil C sequestration  

SciTech Connect

Changing inputs of carbon to soil is one means of potentially increasing carbon sequestration in soils for the purpose of mitigating projected increases in atmospheric CO{sub 2} concentrations. The effect of manipulations of aboveground carbon input on soil carbon storage was tested in a temperate, deciduous forest in east Tennessee, USA. A 4.5-year experiment included exclusion of aboveground litterfall and supplemental litter additions (three times ambient) in an upland and a valley that differed in soil nitrogen availability. The estimated decomposition rate of the carbon stock in the O horizon was greater in the valley than in the upland due to higher litter quality (i.e., lower C/N ratios). Short-term litter exclusion or addition had no effect on carbon stock in the mineral soil, measured to a depth of 30 cm, or the partitioning of carbon in the mineral soil between particulate- and mineral-associated organic matter. A two-compartment model was used to interpret results from the field experiments. Field data and a sensitivity analysis of the model were consistent with little carbon transfer between the O horizon and the mineral soil. Increasing aboveground carbon input does not appear to be an effective means of promoting carbon sequestration in forest soil at the location of the present study because a disconnect exists in carbon dynamics between O horizon and mineral soil. Factors that directly increase inputs to belowground soil carbon, via roots, or reduce decomposition rates of organic matter are more likely to benefit efforts to increase carbon sequestration in forests where carbon dynamics in the O horizon are uncoupled from the mineral soil.

Garten Jr, Charles T [ORNL

2009-01-01

60

Mineral Control of Soil Carbon Dynamics in Forest Soils: A Lithosequence Under Ponderosa Pine  

NASA Astrophysics Data System (ADS)

The role of soil organic carbon in regulating atmospheric CO2 concentration has spurred interest in both quantifying existing soil C stocks and modeling the behavior of soil C under climate change scenarios. Soil parent material exerts direct control over soil organic carbon content through its influence on soil pH and mineral composition. Soil acidity and mineral composition also influence soil microbial community composition and activity, thereby controlling soil respiration rates and microbial biomass size. We sampled a lithosequence of four parent materials (rhyolite, granite, basalt, limestone) under Pinus ponderosa to examine the effects of soil mineralogy and acidity on soil organic carbon content and soil microbial community. Three soil profiles were examined on each parent material and analyzed by X-ray diffraction, pH, selective dissolution, C and N content, and 13C signature. Soils from each of the four parent materials were incubated for 40 days, and microbial communities were compared on the basis of community composition (as determined through T-RFLP analysis), specific metabolic activity, biomass, ?13C of respired CO2, and cumulative amount of C mineralized over the course of the incubation. Soil C content varied significantly among soils of different parent material, and was strongly and positively associated with the abundance of Al-humus complexes r2 = 0.71; P < 0.0001, Fe-humus complexes r2 = 0.74; P = 0.0003, and crystalline Fe-oxide content r2 = 0.63; P = 0.0023. Microbial community composition varied significantly among soils and showed strong associations with soil pH 1:1 in KCl; r2 = 0.87; P < 0.0001, concentration of exchangeable Al r2 = 0.81; P < 0.0001, amorphous Fe oxide content r2 = 0.59; P < 0.004, and Al-humus content r2 = 0.35; P < 0.04. Mineralization rates, biomass and ?13C of respired CO2 differed among parent materials, and also varied with incubation time as substrate quality and N availability changed. The results demonstrate that within a specific ecosystem type, soil parent material exerts significant control over the lability and bioavailability of soil C and soil microbial community composition. We suggest that soil parent material and mineralogy are critical parameters for predicting soil C dynamics and recalcitrance of soil C stocks.

Heckman, K. A.; Welty-Bernard, A.; Rasmussen, C.; Schwartz, E.; Chorover, J.

2008-12-01

61

REGULAR ARTICLE Soil carbon and nitrogen mineralization following  

E-print Network

REGULAR ARTICLE Soil carbon and nitrogen mineralization following deposition of insect frass and greenfall were added to microcosms for each FACE treatment (control, +CO2, +O3, +CO2+O3). We measured. Elevated carbon dioxide (eCO2) and tropospheric ozone (eO3) significantly altered the carbon, nitrogen

62

Nitrogen Mineralization of Cover Crop Residues in Calcareous Gravelly Soil  

Microsoft Academic Search

Tropical legumes like sunn hemp (Crotolaria juncea L.) and aeschynomene (Aeschynomene evenia L.) have potential as alternative cover crops in tropical regions. The objective of this study was to evaluate the N mineralization rates of three cover crops [aeschynomene (AE), sorghum sudangrass (Sorghum sudanense L.), and sunn hemp (SH)] residues used to amend a calcareous gravelly soil in order to

R. B. Rao; Y. C. Li

2003-01-01

63

Soil type influences crop mineral composition in Malawi.  

PubMed

Food supply and composition data can be combined to estimate micronutrient intakes and deficiency risks among populations. These estimates can be improved by using local crop composition data that can capture environmental influences including soil type. This study aimed to provide spatially resolved crop composition data for Malawi, where information is currently limited. Six hundred and fifty-two plant samples, representing 97 edible food items, were sampled from >150 sites in Malawi between 2011 and 2013. Samples were analysed by ICP-MS for up to 58 elements, including the essential minerals calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), selenium (Se) and zinc (Zn). Maize grain Ca, Cu, Fe, Mg, Se and Zn concentrations were greater from plants grown on calcareous soils than those from the more widespread low-pH soils. Leafy vegetables from calcareous soils had elevated leaf Ca, Cu, Fe and Se concentrations, but lower Zn concentrations. Several foods were found to accumulate high levels of Se, including the leaves of Moringa, a crop not previously been reported in East African food composition data sets. New estimates of national dietary mineral supplies were obtained for non-calcareous and calcareous soils. High risks of Ca (100%), Se (100%) and Zn (57%) dietary deficiencies are likely on non-calcareous soils. Deficiency risks on calcareous soils are high for Ca (97%), but lower for Se (34%) and Zn (31%). Risks of Cu, Fe and Mg deficiencies appear to be low on the basis of dietary supply levels. PMID:25461061

Joy, Edward J M; Broadley, Martin R; Young, Scott D; Black, Colin R; Chilimba, Allan D C; Ander, E Louise; Barlow, Thomas S; Watts, Michael J

2015-02-01

64

NATURAL ATTENUATION OF COPPER IN SOILS AND SOIL MINERALS - I  

EPA Science Inventory

The bioavailability and toxicity of Cu in soils is controlled by a number of soil properties and processes. Some of these such as pH, adsorption/desorption and competition with beneficial cations have been extensively studied. However, the effects of natural attenuation (or aging...

65

NATURAL ATTENUATION OF COPPER IN SOILS AND SOIL MINERALS - II  

EPA Science Inventory

The bioabailability and toxicity of Cu in soils is controlled by a number of soil properties and processes. Some of these such as pH, adsorption/desorption and competition with beneficial cations have been extensively studied. However, the effects of natural attenuation (or aging...

66

Dielectric Constant Measurements on Lunar Soils and Terrestrial Minerals  

NASA Technical Reports Server (NTRS)

The return to the Moon has ignited the need to characterize the lunar regolith using in situ methods. An examination of the lunar regolith samples collected by the Apollo astronauts indicates that only a few minerals (silicates and oxides) need be considered for in situ resource utilization (ISRU). This simplifies the measurement requirements and allows a detailed analysis using simple methods. Characterizing the physical properties of the rocks and soils is difficult because of many complex parameters such as soil temperature, mineral type, grain size, porosity, and soil conductivity. In this presentation, we will show that the dielectric constant measurement can provide simple detection for oxides such as TiO2, FeO, and water. Their presence is manifest by an unusually large imaginary permittivity.

Anderson, R. C.; Buehler, M. G.; Seshardri, S.; Schaap, M. G.

2004-01-01

67

Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties  

NASA Astrophysics Data System (ADS)

Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1° First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at P<0.01). At this stage it is, however, not known if these relations between net evolution of NH4 and pH and Fe content are causal or indirect. 2° Second, the 25 samples collected from farmers' fields were physically fractionated into particulate OM and silt and clay associated OM. The silt and clay sized OM was further chemically fractionated by oxidation with 6%NaOCl to isolate an oxidation-resistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in turn equivalent to decreasing bio-availability. Although water has frequently been used to extract labile SOM, its use has mostly been limited to 100°C. 3° Third we developed sub critical water extraction (SCWE) at 100°C, 150°C and 200°C to isolate SOM fractions from the set of 25 paddy soil samples. In all cases, SCWE organic carbon (SCWE-OC) and N (SCWE-N) increased exponentially with the increase of temperature. SCWE preferentially extracted N over OC with increasing temperature. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. No correlations were found between the SCWE fractions and anaerobic N mineralization rate. In conclusion, SOM quantity and SOM quality, here represented by C and N distribution over physicochemical fractions, don't seem to dominantly determine anaerobic N mineralization in primarily young floodplain paddy soils. Other factors with exceeding control (pH and pyrophosphate extractable Fe) appear to exist. Possibly, the specific young genesis stage of most of the soils included (termed 'floodplain' soils) results in a limited availability of readily reducible Fe. Being an important alternative electron acceptor under submerged conditions, the availability of Fe, which is also controlled by pH, may be a bottleneck in the anaerobic N mineralization process. This needs to be further investigated by controlled incubation experiments with detailed follow-up of pH, redox potential, Fe in solution and mineral N.

Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan

2013-04-01

68

Interactions between Carbon and Nitrogen Mineralization and Soil Organic Matter Chemistry in Arctic Tundra Soils  

Microsoft Academic Search

We used long-term laboratory incubations and chemical fractionation to characterize the mineralization dynamics of organic\\u000a soils from tussock, shrub, and wet meadow tundra communities, to determine the relationship between soil organic matter (SOM)\\u000a decomposition and chemistry, and to quantify the relative proportions of carbon (C) and nitrogen (N) in tundra SOM that are\\u000a biologically available for decomposition. In all soils

Michael N. Weintraub; Joshua P. Schimel

2003-01-01

69

Mineralization of Nitrogen in Soils Amended with Dairy Manure as Affected by Wetting\\/Drying Cycles  

Microsoft Academic Search

Interest in manure management and its effects on nitrogen (N) mineralization has increased in recent years. The focus of this research was to investigate the N?mineralization rates of different soil types in Coastal Plain soils and compare them to a soil from Illinois. Soils with and without dairy composted manure addition were subjected to different wetting\\/drying cycles [constant moisture at

D. B. Watts; H. A. Torbert; S. A. Prior

2007-01-01

70

Activities of N-mineralization enzymes associated with soil aggregates in three different tillage systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil enzymes released by microorganisms play a significant role in N mineralization process that determines N availability for plant growth. Soil aggregates of different sizes provide diverse microhabitats for microorganisms and therefore influence soil enzyme activities. We hypothesize that enzyme ...

71

Stability of Soil Carbon Fractions - Aggregation Versus Mineral Association  

NASA Astrophysics Data System (ADS)

Models that seek to describe the dynamics of soil organic C typically distinguish between two or more C fractions according to differences of biochemical and microbial degradation. The rates are a consequence of recalcitrance, accessibility and interactions. Soil aggregation is an important mechanism controlling the accessibility of substrates by microbes and enzymes and thus the dynamics of minerals bound C are interacting with soil aggregate dynamics. In this study we focused on C fractions isolated by particle size fractionation. The main objective of our study was to differentiate between C stabilization of soil fractions due to accessibility/aggregation or to association with minerals. For a detailed understanding of these processes and the sources of respired soil CO2 we combined the measurement of heterotrophic respiration, CO2-13C analyses and radiocarbon dating of the respired CO2 in a long-term laboratory mineralization experiment. For the experiment we took soil material from the A horizon of an Albic Luvisol under Norway spruce forest (Picea abies) in southern Germany. The air dried bulk soil (< 2000 µm) was subjected to ultrasonication (1st step 60 J ml-1; 2nd step 440 J ml-1) and separated according to particle size in three fractions: > 63 µm to 2000 µm - sand, > 6.3 µm to 63 µm - silt and silt/clay fraction < 6.3 µm - clay. Solid-state 13C-CPMAS NMR spectroscopy was used to analyze the composition of bulk soil and fractions. The incubation of the three fractions and the bulk soil was done for 250 days in triplicate at 20 degree Celsius and 70% of maximal water holding capacity. A relative enrichment of alkyl C and an increase of the alkyl / O/N-alkyl C ratios in the order of sand < silt < clay were observed by 13C-NMR. On a long term the sand fraction and the bulk soil showed a sustained C bioavailability. For the silt and clay fraction similar respiration rates and a low C bioavailability were detected. The recombined fractions (by calculation) showed 35% higher amounts of respired CO2-C than the bulk soil. This difference accounts for the absence of restricted accessibility due to soil aggregation. Because of the high amounts of mineral bound C the main source of CO2-C (70%) in the recombined fraction is the clay fraction. Nevertheless the recalcitrance of mineral bound C is restricting the positive effects of aggregate disruption on the C turnover. The small fast decomposing C pool of the sand fraction is of minor importance to the total soil respiration balance. CO2-13C signatures showed higher values of the silt and clay fractions in contrast to the sand fraction, indicating a lower bioavailability of 13C-depleted carbon sources in the small fractions. The analyses of CO2-14C showed a shift to the utilization of older C sources with time.

Mueller, C. W.; Koegel-Knabner, I.

2007-12-01

72

Relationships between labile organic matter and nitrogen mineralization in Japanese agricultural soils with reference to land use and soil type  

Microsoft Academic Search

The relationship between the amount of organic matter determined using various extraction methods and the nitrogen mineralization potential (N0) in soil was examined with reference to land use (upland and paddy soils) and soil type (non-volcanic and volcanic soils). Surface soils were collected from agricultural lands all over Japan (n = 72). Seven methods of extracting labile organic matter were used: water

Shuji Sano; Junta Yanai; Takashi Kosaki

2006-01-01

73

Quantifying the effect of soil moisture on the aerobic microbial mineralization of selected pesticides in different soils.  

PubMed

A standardized quantitative approach was developed to reliably elucidate the effect of increasing soil moisture on pesticide mineralization. The mineralization of three aerobically degradable and chemically different 14C-labeled pesticides (isoproturon, benazolin-ethyl, and glyphosate) was studied under controlled conditions in the laboratory at an identical soil density of 1.3 g cm(-3). The agricultural soils used are characterized by (i) large variations in soil texture (sand content 4-88%) and organic matter content (0.97-2.70% org. C), (ii) fairly diverse soil-water retention curves, and (iii) differing pH values. We quantified the effect of soil moisture on mineralization of pesticides and found that (i) at soil water potential < or = -20 MPa minimal pesticide mineralization occurred; (ii) a linear correlation (P < 0.0001) exists between increasing soil moisture (within a soil water potential range of -20 and -0.015 MPa), and increased relative pesticide mineralization; (iii) optimum pesticide mineralization was obtained at a soil water potential of -0.015 MPa, and (iv) when soil moisture approximated water holding capacity, pesticide mineralization was considerably reduced. As both selected pesticides and soils varied to a large degree, we propose that the correlation observed in this study may be also valid in the case of aerobic degradation of other native and artificial organic compounds in soils. PMID:16749698

Schroll, Reiner; Becher, Hans Heinrich; Dörfler, Ulrike; Gayler, Sebastian; Grundmann, Sabine; Hartmann, Hans Peter; Ruoss, Jürgen

2006-05-15

74

Distinct temperature sensitivity of soil carbon decomposition in forest organic layer and mineral soil  

PubMed Central

The roles of substrate availability and quality in determining temperature sensitivity (Q10) of soil carbon (C) decomposition are still unclear, which limits our ability to predict how soil C storage and cycling would respond to climate change. Here we determined Q10 in surface organic layer and subsurface mineral soil along an elevation gradient in a temperate forest ecosystem. Q10 was calculated by comparing the times required to respire a given amount of soil C at 15 and 25°C in a 350-day incubation. Results indicated that Q10 of the organic layer was 0.22–0.71 (absolute difference) higher than Q10 of the mineral soil. Q10 in both the organic layer (2.5–3.4) and the mineral soil (2.1–2.8) increased with decreasing substrate quality during the incubation. This enhancement of Q10 over incubation time in both layers suggested that Q10 of more labile C was lower than that of more recalcitrant C, consistent with the Arrhenius kinetics. No clear trend of Q10 was found along the elevation gradient. Because the soil organic C pool of the organic layer in temperate forests is large, its higher temperature sensitivity highlights its importance in C cycling under global warming. PMID:25270905

Xu, Wenhua; Li, Wei; Jiang, Ping; Wang, Hui; Bai, Edith

2014-01-01

75

Distinct temperature sensitivity of soil carbon decomposition in forest organic layer and mineral soil.  

PubMed

The roles of substrate availability and quality in determining temperature sensitivity (Q10) of soil carbon (C) decomposition are still unclear, which limits our ability to predict how soil C storage and cycling would respond to climate change. Here we determined Q10 in surface organic layer and subsurface mineral soil along an elevation gradient in a temperate forest ecosystem. Q10 was calculated by comparing the times required to respire a given amount of soil C at 15 and 25°C in a 350-day incubation. Results indicated that Q10 of the organic layer was 0.22-0.71 (absolute difference) higher than Q10 of the mineral soil. Q10 in both the organic layer (2.5-3.4) and the mineral soil (2.1-2.8) increased with decreasing substrate quality during the incubation. This enhancement of Q10 over incubation time in both layers suggested that Q10 of more labile C was lower than that of more recalcitrant C, consistent with the Arrhenius kinetics. No clear trend of Q10 was found along the elevation gradient. Because the soil organic C pool of the organic layer in temperate forests is large, its higher temperature sensitivity highlights its importance in C cycling under global warming. PMID:25270905

Xu, Wenhua; Li, Wei; Jiang, Ping; Wang, Hui; Bai, Edith

2014-01-01

76

Mineral Dissolution and Precipitation due to Carbon Dioxide-Water-Rock Interactions: The Significance of Accessory Minerals in Carbonate Reservoirs (Invited)  

NASA Astrophysics Data System (ADS)

Accessory minerals in carbonate reservoirs, and in the caprocks that seal these reservoirs, can provide insight into multiphase fluid (CO2 + H2O)-rock interactions and the behavior of CO2 that resides in these water-rock systems. Our program integrates field data, hydrothermal experiments, and geochemical modeling to evaluate CO2-water-rock reactions and processes in a variety of carbonate reservoirs in the Rocky Mountain region of the US. These studies provide insights into a wide range of geologic environments, including natural CO2 reservoirs, geologic carbon sequestration, engineered geothermal systems, enhanced oil and gas recovery, and unconventional hydrocarbon resources. One suite of experiments evaluates the Madison Limestone on the Moxa Arch, Southwest Wyoming, a sulfur-rich natural CO2 reservoir. Mineral textures and geochemical features developed in the experiments suggest that carbonate minerals which constitute the natural reservoir will initially dissolve in response to emplacement of CO2. Euhedral, bladed anhydrite concomitantly precipitates in response to injected CO2. Analogous anhydrite is observed in drill core, suggesting that secondary anhydrite in the natural reservoir may be related to emplacement of CO2 into the Madison Limestone. Carbonate minerals ultimately re-precipitate, and anhydrite dissolves, as the rock buffers the acidity and reasserts geochemical control. Another suite of experiments emulates injection of CO2 for enhanced oil recovery in the Desert Creek Limestone (Paradox Formation), Paradox Basin, Southeast Utah. Euhedral iron oxyhydroxides (hematite) precipitate at pH 4.5 to 5 and low Eh (approximately -0.1 V) as a consequence of water-rock reaction. Injection of CO2 decreases pH to approximately 3.5 and increases Eh by approximately 0.1 V, yielding secondary mineralization of euhedral pyrite instead of iron oxyhydroxides. Carbonate minerals also dissolve and ultimately re-precipitate, as determined by experiments in the Madison Limestone, but pyrite will persist and iron oxyhydroxides will not recrystallize.

Kaszuba, J. P.; Marcon, V.; Chopping, C.

2013-12-01

77

Winter cover cropping influence on nitrogen mineralization, presidedress soil nitrate test, and corn yields  

Microsoft Academic Search

The mineralization and availability of cover crop N to the succeeding crop are critical components in the management of soil N to reduce N leaching. The effects of several leguminous and non-leguminous cover crops on soil N availability, N mineralization potential, and corn (Zea mays L.) yield were examined. The cover crops had variable effects on soil N availability and

S. Kuo; U. M. Sainju; E. Jellum

1996-01-01

78

Effects of mineral and biofertilizers on barley growth on compacted soil  

Microsoft Academic Search

Biofertilizers are an alternative to mineral fertilizers for increasing soil productivity and plant growth in sustainable agriculture. The objective of this study was to evaluate possible effects of three mineral fertilizers and four plant growth promoting rhizobacteria (PGPR) strains as biofertilizer on soil properties and seedling growth of barley (Hordeum vulgare) at three different soil bulk densities, and in three

Mustafa Y. Canbolat; Kenan Barik; Ramazan Çakmakçi; Fikrettin ?ahin

2006-01-01

79

Vertical profile measurements of soil air suggest immobilization of gaseous elemental mercury in mineral soil.  

PubMed

Evasion of gaseous elemental Hg (Hg(0)g) from soil surfaces is an important source of atmospheric Hg, but the volatility and solid-gas phase partitioning of Hg(0) within soils is poorly understood. We developed a novel system to continuously measure Hg(0)g concentrations in soil pores at multiple depths and locations, and present a total of 297 days of measurements spanning 14 months in two forests in the Sierra Nevada mountains, California, U.S. Temporal patterns showed consistent pore Hg(0)g concentrations below levels measured in the atmosphere (termed Hg(0)g immobilization), ranging from 66 to 94% below atmospheric concentrations throughout multiple seasons. The lowest pore Hg(0)g concentrations were observed in the deepest soil layers (40 cm), but significant immobilization was already present in the top 7 cm. In the absence of sinks or sources, pore Hg(0)g levels would be in equilibrium with atmospheric concentrations due to the porous nature of the soil matrix and gas diffusion. Therefore, we explain decreases in pore Hg(0)g in mineral soils below atmospheric concentrations--or below levels found in upper soils as observed in previous studies--with the presence of an Hg(0)g sink in mineral soils possibly related to Hg(0)g oxidation or other processes such as sorption or dissolution in soil water. Surface chamber measurements showing daytime Hg(0)g emissions and nighttime Hg(0)g deposition indicate that near-surface layers likely dominate net atmospheric Hg(0)g exchange resulting in typical diurnal cycles due to photochemcial reduction at the surface and possibly Hg(0)g evasion from litter layers. In contrast, mineral soils seem to be decoupled from this surface exchange, showing consistent Hg(0)g uptake and downward redistribution--although our calculations indicate these fluxes to be minor compared to other mass fluxes. A major implication is that once Hg is incorporated into mineral soils, it may be unlikely subjected to renewed Hg(0)g re-emission from undisturbed, background soils emphasizing the important role of soils in sequestering past and current Hg pollution loads. PMID:24428735

Obrist, Daniel; Pokharel, Ashok K; Moore, Christopher

2014-02-18

80

Mineral exploration and soil analysis using in situ neutron activation  

USGS Publications Warehouse

A feasibility study has been made to operate by remote control an unshielded portable positive-ion accelerator type neutron source to induce activities in the ground or rock by "in situ" neutron irradiation. Selective activation techniques make it possible to detect some thirty or more elements by irradiating the ground for periods of a few minutes with either 3-MeV or 14-MeV neutrons. The depth of penetration of neutrons, the effect of water content of the soil on neutron moderation, gamma ray attenuation in the soil and other problems are considered. The analysis shows that, when exploring for most elements of economic interest, the reaction 2H(d,n)3He yielding ??? 3-MeV neutrons is most practical to produce a relatively uniform flux of neutrons of less than 1 keV to a depth of 19???-20???. Irradiation with high energy neutrons (??? 14 MeV) can also be used and may be better suited for certain problems. However, due to higher background and lower sensitivity for the heavy minerals, it is not a recommended neutron source for general exploration use. Preliminary experiments have been made which indicate that neutron activation in situ is feasible for a mineral exploration or qualititative soil analysis. ?? 1976.

Senftle, F.E.; Hoyte, A.F.

1966-01-01

81

Changes in Soil Minerology Reduce Phosphorus Mobility During Anoxic Soil Conditions  

NASA Astrophysics Data System (ADS)

Phosphorus (P) transfer from the landscape to receiving waters is an important environmental concern because these diffuse losses may cause widespread water quality impairments which can accelerate freshwater eutrophication. Phosphorus (P) mobilization from soil to surface and subsurface flow paths is controlled by numerous factors, and thus it can vary greatly with time and landscape scale. To determine whether P mobilization during soil saturation in the landscape was caused or controlled by complexation, iron reduction or ligand exchange, experiments were carried out to better characterize the interrelationships of varying P sources with dissolved organic carbon (DOC) and soil anoxic conditions. The soil incubation experiments consisted of treatments with distilled water, 5 mM acetic acid (HAc), 0.05% humic acid (HA) and glucose (40 mM) at 26 o C under anaerobic conditions to isolate effects of the various P exchange processes. The experimental results suggest that during soil saturation, the loosely bound P, which is primarily associated with iron oxyhydroxides, was mobilized by both reduction and complexation processes. Good correlations were observed between ferrous iron (Fe+2) and DOC, and between total dissolved phosphorus (TDP) and DOC, facilitating P desorption to the soil water. The anaerobic soil conditions with different P sources also indicated that mineralization facilitated P mobility, mainly due to chelation (humics and metabolites) and as a result of the bio-reduction of iron when fresh litter and grass were present. The organic P sources which are rich in carbohydrate and cellulose and that undergo fermentation due to the action of lactate forming organisms also caused a release of P. The easily metabolizable DOC sources lead to intensive bio-reduction of soil with the release of Fe, however this did not necessarily appear to cause more TDP in the soil solution. The varying P additions in soils with water, HAc and glucose (40mm) before and after soil incubation showed higher P sorption than aerobic soil due to reduced iron (Fe+2) - P mineral formation. Some of the readily available P in the soil solution tended to co-precipitate quickly with Fe, Al, Ca, and Mn, but it also resulted in the formation of earthy masses of vivianite [Fe2+3(PO4)2 . 8 H20], thus almost completely immobilizing P. These findings suggest that where conditions in the landscape are saturated, but remain stagnant for extended time periods, P additions may not necessarily enhance leaching once hydrological transport resumes. The temporal nature of P mobilization processes combined with rapid (i.e., preferential flow) hydrological transport appears to have a more important role in controlling P transport through the landscape.

Giri, S. K.; Geohring, L. D.; Richards, B. K.; Walter, M.; Steenhuis, T. S.

2008-05-01

82

COMPARISON OF NUTRIENT SOURCES OF MINERAL SOIL NUTRITION IN FLORIDA SUGARCANE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Improving soil organic matter and soil fertility are important factors in the sustainability of sugarcane production on mineral soils. A trial was established in 2004 on a sandy Spodosol in Florida to compare the effect of organic and inorganic nutrient sources on soil fertility and sugarcane produ...

83

Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil  

SciTech Connect

Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2-ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [[sup 14]C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial mineralization activity was described well by first-order kinetics, whereas mineralization in long-term incubations was described better by fractional power kinetics. The mineralization activity was much lower in the late phase presumably due to a decline in the bioavailability of DEHP caused by diffusion-limited desorption. The initial DEHP mineralization rate in sludge-amended soil varied between 3.7 and 20.3 ng of DEHP (g dw)[sup [minus]1]d[sup [minus]1] depending on incubation conditions. Aerobic DEHP mineralization was 4--5 times faster than anaerobic mineralization, DEHP mineralization in sludge-amended soil was much more temperature sensitive than was DEHP mineralization in soil without sludge. Indigenous microorganisms in the sewage sludge appeared to dominate DEHP degradation in sludge-amended soil. It was estimated that > 41% of the DEHP in sludge-amended soil will have escaped mineralization after 1 year. In the absence of oxygen, > 68% of the DEHP will not be mineralized within 1 year. Collectively, the data suggest that a significant fraction of the DEHP in sludge-amended soils may escape mineralization under in situ conditions.

Madsen, P.L.; Thyme, J.B.; Henriksen, K.; Moeldrup, P.; Roslev, P. (Aalborg Univ. (Denmark). Environmental Engineering Lab.)

1999-08-01

84

Heavy metal adsorption by different minerals: application to the remediation of polluted soils  

Microsoft Academic Search

We studied the heavy-metal adsorption capacity of various minerals in order to evaluate their potential for the reduction of metal mobility and bioavailability and their possible application for the remediation of polluted soils in the Guadiamar valley. The study (batch tests) of zinc adsorption capacity of clays (sepiolites, palygorskites, and bentonite from different mineral deposits) and a soil unaffected by

A. Garc??a-Sánchez; A. Alastuey; X. Querol

1999-01-01

85

LONG-TERM URANIUM MIGRATION IN AGRICULTURAL FIELD SOILS FOLLOWING MINERAL P FERTILIZATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

To preserve soil fertility, organic and mineral fertilizers are often applied to agricultural fields. Mineral fertilizers such as phosphates and super phosphates contain a certain amount of long-lived alpha activity due to 238-U, 230-Th, amongst others. The fate of U in soil systems is quite complex...

86

Fibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina  

E-print Network

, palygorskite is the dominant clay mineral. Pedogenetic carbonate was qualified as low- Mg calcite, indicatingFibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina Patagonia identified fibrous-clay minerals in calcic and petrocalcic horizons developed on old fluvio

Ahmad, Sajjad

87

Effects of the duration of water saturation periods on organic carbon mineralization in a poorly-drained mineral soil  

NASA Astrophysics Data System (ADS)

In poorly-drained soils located in riparian areas, climate change is likely to affect the duration and frequency of water saturation periods and consequently rates of soil organic matter mineralization in these soils. Using laboratory incubations of an epistagnic Haplic Albeluvisol, the aim of this study was to quantify the effect the duration of water saturation periods on soil organic C (SOC) and N mineralization under saturated and non-saturated conditions. 120 undisturbed soils cores were incubated at 20°C during 64 days. Three treatments differing in the duration of the water saturation periods were considered. In the control treatment (T0), the soil water content was maintained at field capacity (71% WFPS) throughout the duration of the incubation. In treatment T1, the soil was saturated (100% WFPS) during 46 days, and desaturated and soil water content was maintained at field capacity until the end of incubation. In treatment T2, the soil was saturated (100% WFPS) during 19 days, and desaturated and soil water content was maintained at field capacity until the end of incubation. For each treatment, gas analyses (CO2) were performed at 10 dates on four replicates. SOC mineralization in T1 and T2 was low during the saturation phase (median value 2.7 and 1.5 mgC-CO2.kg-1.d-1 respectively) compared to that of the control treatment (median value 4.5 and 4.1 mgC-CO2.kg-1.d-1 respectively at 46th and 19th day) and that of the desaturated phase of T1 and T2 (median value 7.9 and 3.6 mgC-CO2.kg-1.d-1 respectively). In T1, CO2 concentration at the beginning of desaturation twice higher than that observed in the control treatment. The results also showed that whatever the duration of saturation periods SOC mineralization in T1 and T2 at desurated condition was similar to that of T0. However, the SOC mineralized on the whole 64 days of incubation was 45% less important for T1 and T2 than T0. This study showed that the duration of water saturation periods not affected organic carbon mineralization neither at saturated nor desaturated condition. In saturation condition carbon mineralization was provided by nitrate reduction respiration and desaturation beginning caused a flush of aerobic respiration. All these processes were not time depending but strongly linked to soil moisture and soil redox conditions.

Tete, Emmanuel; Viaud, Valérie; Walter, Christian

2013-04-01

88

Soil quality assessment for peat-mineral mix cover soil used in oil sands reclamation.  

PubMed

A soil quality (SQ) assessment and rating framework that is quantitative, iterative, and adaptable, with justifiable weighting for quality scores, is required for evaluating site-specific SQ at land reclamation sites. Such a framework needs to identify the minimum dataset that reflects the current knowledge regarding relationships between SQ indicators and relevant measures of ecosystem performance. Our objective was to develop nonlinear scoring functions for assessing the impact on SQ of peat-mineral mix (PMM) used as a cover soil at land reclamation sites. Soil functional indicators affected by PMM were extracted from existing databases and correlated with soil organic carbon (SOC). Based on defined objectives for SQ assessment, indicators with significant correlation ( < 0.05) to SOC were selected, normalized, and fitted to sigmoid functions using nonlinear regression procedure to establish SQ functions (SQFs) that can analyze changes in field capacity, permanent wilting point, soil nitrogen, and cation exchange capacity of PMM using SOC as input parameter. Application of the SQFs to an independent dataset produced ratings with mean differences similar to the treatment effects of mixing three levels of peat and mineral soil. These results show that derived ratings and weighing factors using SOC reflect the relationship between PMM treatment and other SQ indicators. Applying the developed SQFs to a long-term soil monitoring dataset shows that an increase or decrease in SOC from 10 to 20 g kg causes a significant change in SQ. This identifies the need for further nutrient and moisture management of PMM to support long-term SQ development in land reclamation. PMID:25603242

Ojekanmi, A A; Chang, S X

2014-09-01

89

Effects of Willows (Salix brachycarpa) on Populations of Salicylate-Mineralizing Microorganisms in Alpine Soils  

Microsoft Academic Search

We used the substrate-induced growth-response (SIGR) method to quantify salicylate-mineralizing microbes and total microbial biomass in soils from under willows (Salix brachycarpa) and in surrounding meadows dominated by the sedge Kobresia myosuroides. Willows had a strong effect on the biomass of salicylate-mineralizing microbes in both years of this study. There were always higher biomass levels of salicylate mineralizers in soils

S. K. Schmidt; D. A. Lipson; T. K. Raab

2000-01-01

90

Evolved gas detection of iron oxyhydroxides  

Microsoft Academic Search

A procedure is described for recording evolved gas detection (thermal desorption spectra) of various FeOOH samples up to 400°. Characteristic curves of ?-,?- and?-FeOOH are discussed, based on the crystallographic structure which governs the sites for physisorbed H2O as well as OH groups producing H2O by dehydration. Examinations are also made of the variations of the desorption spectra with the

T. Ishikawa; K. Inouye

1976-01-01

91

Indigenous and enhanced mineralization of pyrene, benzo[a]pyrene, and carbazole in soils.  

PubMed Central

We studied the mineralization of pyrene, carbazole, and benzo[a]pyrene in soils obtained from three abandoned coal gasification plants in southern Illinois. The soils had different histories of past exposure to hydrocarbon contamination and different amounts of total organic carbon, microbial biomass, and microbial activity. Mineralization was measured by using serum bottle radiorespirometry. The levels of indigenous mineralization of 14C-labeled compounds ranged from 10 to 48% for pyrene, from undetectable to 46% for carbazole, and from undetectable to 25% for benzo[a]pyrene following long-term (greater than 180-day) incubations. Pyrene and carbazole were degraded with short or no lag periods in all soils, but benzo[a]pyrene mineralization occurred after a 28-day lag period. Mineralization was not dependent on high levels of microbial biomass and activity in the soils. Bacterial cultures that were capable of degrading pyrene and carbazole were isolated by enrichment, grown in pure culture, and reintroduced into soils. Reintroduction of a pyrene-degrading bacterium enhanced mineralization to a level of 55% within 2 days, compared with a level of 1% for the indigenous population. The carbazole degrader enhanced mineralization to a level of 45% after 7 days in a soil that showed little indigenous carbazole mineralization. The pyrene and carbazole degraders which we isolated were identified as a Mycobacterium sp. and a Xanthamonas sp., respectively. Our results indicated that mineralization of aromatic hydrocarbons can be significantly enhanced by reintroducing isolated polycyclic aromatic hydrocarbon-degrading bacteria. PMID:1785924

Grosser, R J; Warshawsky, D; Vestal, J R

1991-01-01

92

Effects of mycorrhizal fungus isolates on mineral acquisition by Panicum virgatum in acidic soil  

Microsoft Academic Search

Plant ability to withstand acidic soil mineral deficiencies and toxicities can be enhanced by root-arbuscular mycorrhizal\\u000a fungus (AMF) symbioses. The AMF benefits to plants may be attributed to enhanced plant acquisition of mineral nutrients essential\\u000a to plant growth and restricted acquisition of toxic elements. Switchgrass (Panicum virgatum L.) was grown in pHCa (soil:10?mM CaCl2, 1?:?1) 4 and 5 soil (Typic

R. B. Clark; R. W. Zobel; S. K. Zeto

1999-01-01

93

High gradient magnetic separation of iron oxide minerals from soil clays  

E-print Network

HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis by DARRELL GENE SCHULZE Submitted to the Graduate College of Texas AIM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1977 Major Subject: Soil Science HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis DARRELL GENE SCHULZE Approved as to style and content by: (Chairman of C ittee) epartm t) j (Member) (Membe December 1977...

Schulze, Darrell Gene

2012-06-07

94

[Mineralization of soil organic carbon and its relationship with soil enzyme activities in apple orchard in Weibei].  

PubMed

A total of 36 kinds of soil samples were collected from apple orchards under three kinds of management model, including clear tillage model, intercropping white clover model and intercropping small crown flower model, the mineralization of soil organic carbon and four kinds of soil enzymes activities were determined, and the relationship between the two parameters was also analyzed. The results showed that the soil organic carbon mineralization of all the three treatments was almost the same. The daily SOC mineralization rate first increased and then decreased, and finally tended to be stable. After 31 days incubation experiment, the maximum accumulative amount of SOC mineralization occurred in white clover treatment with 590 mg x kg(-1), followed by small crown flower treatment with 541 mg x kg(-1), and the minimum value was 367 mg x kg(-1) in the control treatment, and the accumulative amount of SOC mineralization decreased with increasing soil depth. Discovered by the first-order kinetics, the fitting parameter Cp value ranged from 0.252 to 2.74 g x kg(-1) and k value ranged from 0.019 to 0.051 d(-1), and the two grass treatments both showed significant difference in Cp value from the control treatment, and the soil invertase and cellulose activities showed obvious relationship with soil organic carbon mineralization. PMID:25244868

Jia, Man-Li; Guo, Hong; Li, Hui-Ke

2014-07-01

95

Soil water effects on the use of heat units to predict crop residue carbon and nitrogen mineralization  

Microsoft Academic Search

Soil heat units (degree days) have previously been shown to predict net N mineralization from crop residues and papermil sludge. The present study was designed to identity the effects of soil water potential on predictions of mineralization with heat units and to compare field and laboratory results of white lupin (Lupinus albus L. cv. ‘Ultra’) N mineralization. Lupin-amended soil and

D. S. Doel; C. W. Honeycutt; W. A. Halteman

1990-01-01

96

Mineral Element Content of Timothy (Phleum pratense L.) in an Acid Sulphate Soil Area of Tupos Village, Northern Finland  

Microsoft Academic Search

The mineral element contents of timothy samples collected from 45 acid sulphate soil sites in Tupos village were compared with Finnish average values. The correlation between the contents of the mineral elements and different soil variables was also examined. Tupos soils are not calcium, magnesium, potassium, phosphorus and zinc deficient, but timothy samples were deficient in these mineral elements, possibly

Jukka Palko

1986-01-01

97

[Compositional characteristics and roles of soil mineral substances in depressions between hills in karst region].  

PubMed

Based on the investigation and analysis of seven soil mineral substance variables, nine vegetation factors, four topographical factors, and ten soil physicochemical factors in the 200 m x 40 m dynamic monitoring plots in farmland, forest plantation, secondary forest, and primary forest in the depressions between hills in karst region, and by using traditional statistical analysis, principal component analysis (PCA), and canonical correlation analysis (CCA), this paper studied the compositional characteristics and roles of soil mineral substances as well as the coupling relationships between the mineral substances and the vegetation, topography, and other soil properties. In the depressions, soil mineral substances were mainly composed of SiO2, Al2O3, K2O, and Fe2O3, whose contents were obviously lower than the mean background values of the soils in the world and in the zonal red soils at the same latitudes. The soil CaO and MgO contents were at medium level, while the soil MnO content was very low. The composition of soil mineral substances and their variation degrees varied with the ecosystems, and the soil development degree also varied. There was a positive correlation between vegetation origin and soil origin, suggesting the potential risk of rock desertification. Due to the high landscape heterogeneity of the four ecosystems, PCA didn't show good effect in lowering dimension. In all of the four ecosystems, soil mineral substances were the main affecting factors, and had very close relationships with vegetation, topography, and other soil properties. Especially for SiO2, CaO, and MnO, they mainly affected the vegetation species diversity and the soil organic matter, total nitrogen, and total potassium. This study indicated that soil mineral substances were the one of the factors limiting the soil fertility and vegetation growth in the depressions between hills in karst region. To effectively use the soil mineral resources and rationally apply mineral nutrients would have significances in the restoration and reconstruction of karst degraded ecosystems. PMID:22720612

Han, Mei-Rong; Song, Tong-Qing; Peng, Wan-Xia; Huang, Guo-Qin; Du, Hu; Lu, Shi-Yang; Shi, Wei-Wei

2012-03-01

98

Chemical and mineral composition of ectomycorrhizosphere soils of subalpine fir (Abies  

E-print Network

Chemical and mineral composition of ectomycorrhizosphere soils of subalpine fir (Abies lasiocarpa- zosphere soils of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in the Ae horizon of a Luvisol. Can. J'ectomycorhi- zosphère sous sapin subalpin (Abies lasiocarpa (Hook.) Nutt.) dans l'horizon Ae d'un luvisol. Can. J. Soil

Massicotte, Hugues

99

Nitrogen Mineralization in Aspen\\/Conifer Soils After a Natural Fire  

Microsoft Academic Search

We measured the effects of the 1996 Pole Creek fire, Fishlake National Forest, Utah, on available soil N and net N mineralization for three summers after the fire using an ion exchange membrane (IEM) soil core incubation method. Fire in mixed aspen\\/conifer increased the amount of available NH4, and a subsequent net increase in soil nitrification was observed. Release of

Michael C. Amacher; Dale L. Bartos; Tracy Christopherson; Amber D. Johnson; Debra E. Kutterer

100

Persistence of four pyrethroid insecticides in a mineral and an organic soil  

Microsoft Academic Search

Permethrin, cypermethrin, fenpropanate and fenvalerate (emulsifiable concentrates) were applied at 280 g AI\\/ha and incorporated into mineral and organic soil contained in small field plots. Radishes and carrots were grown to serve as indicators of insecticide uptake. Similar plots were treated with the same insecticides at 140 g AI\\/ha and the soil surface was left undisturbed following application. Soil cores

R. A. Chapman; C. R. Harris

1981-01-01

101

Effects of phosphoroamides on nitrification, denitrification, and mineralization of organic nitrogen in soil  

Microsoft Academic Search

Recent work has shown that several phosphorodiamides and phosphorotriamides are potent inhibitors of soil urease activity and have potential value for retarding hydrolysis of fertilizer urea in soil. The effects of nine of these compounds on nitrification, denitrification, and mineralization of organic nitrogen in soil were studied by determining the influence of different amounts of each compound on (1) the

J. M. Bremner; G. W. McCarty; J. C. Yeomans; H. S. Chai

1986-01-01

102

Nitrogen Mineralization in a Semiarid Silt Loam Soil in the Pacific Northwest  

Technology Transfer Automated Retrieval System (TEKTRAN)

The mineralization of nitrogen from soil organic matter or plant residues can provide a substantial amount of nitrogen for crop growth. Microbial activity in a soil may be adversely affected by either very high or low soil water content. A field study was conducted to determine the affect of three...

103

Exploitation of potassium by various crop species from primary minerals in soils rich in micas  

Microsoft Academic Search

We investigated the question of whether exchangeable K+ is a reliable factor for K+ availability to plants on representative arable soils (Aridisols) rich in K+-bearing minerals. Five soils with different textures were collected from different locations in Pakistan and used for pot experiments. The soils were separated into sand, silt, and clay fractions and quartz sand was added to each

K. Mengel; Rahmatullah

1994-01-01

104

Global distribution of minerals in arid soils as lower boundary condition in dust models  

NASA Astrophysics Data System (ADS)

Mineral dust eroded from arid soils affects the radiation budget of the Earth system, modifies ocean bioproductivity and influences human health. Dust aerosol is a complex mixture of minerals. Dust mineral composition has several potentially important impacts to environment and society. Iron and phosphorus embedded in mineral aerosol are essential for the primary marine productivity when dust deposits over the open ocean. Dust also acts as efficient agent for heterogeneous ice nucleation and this process is dependent on mineralogical structure of dust. Recent findings in medical geology indicate possible role of minerals to human health. In this study, a new 1-km global database was developed for several minerals (Illite, Kaolinite, Smectite, Calcite, Quartz, Feldspar, Hematite and Gypsum) embedded in clay and silt populations of arid soils. For the database generation, high-resolution data sets on soil textures, soil types and land cover was used. Tin addition to the selected minerals, phosphorus was also added whose geographical distribution was specified from compiled literature and data on soil types. The developed global database was used to specify sources of mineral fractions in the DREAM dust model and to simulate atmospheric paths of minerals and their potential impacts on marine biochemistry and tropospheric ice nucleation.

Nickovic, Slobodan

2010-05-01

105

Changes in mineral soil biogeochemical cycling and environmental conditions following tree harvest in the Northeast  

NASA Astrophysics Data System (ADS)

In the northeastern United States, reductions in carbon dioxide emissions have been attempted by using local wood as a renewable alternative to oil. Although woody biomass products are readily available, recent findings suggest that forest disturbance may cause release of carbon from the deeper mineral soil. Worldwide, deep soils sequester more than half of soil carbon, making it critical in the global carbon cycle; however, most studies on the effect of harvesting have focused on the organic soil horizon. Our research aimed to uncover changes in biogeochemistry and environmental conditions in deeper, mineral soil after clear cutting forests. We quantified post-harvest mineral soil carbon pools through a regional study. We utilized stands of different ages to measure the recovery of soil carbon over time since harvest. Stands included in this study were cut approximately 5, 12, 25, 50, or 120 ybp, in order to identify changes in soil carbon over time since harvest. We sampled harvested stands in six research or protected forests across New York, New Hampshire, Massachusetts, and Vermont. Soil samples were collected to a depth of 60 cm below the surface of the mineral soil using a gas-powered augur and 9.5 cm diameter drill bit. Soil samples were analyzed at Dartmouth College. In order to understand specific changes in mineral soil carbon dynamics following harvest, measurements of carbon fluxes, such as soil respiration and DOC transport were conducted at five different-aged stands at Bartlett Experimental Forest, NH. While parameters that may influence carbon storage—such as pH, clay content, tree cover and elevation— did not vary across the different-aged stands in each forest, carbon pools did vary over time. We found changes in carbon pools in at least three experimental forests across the northeast. At Bartlett Experimental Forest, we found a gradual decline in mineral soil carbon storage from between 85-87 Mg ha-1 in 120 year old and primary forest stands to a minimum of 53 Mg ha-1 in the 75 year old stand. In our carbon flux measurements, we observed higher DOC concentrations in lysimeter samples collected at 30 cm at 12 years after harvest. We have also documented consistently higher soil temperatures across summer months at 50 cm below the mineral soil in the recently clear-cut site at Bartlett Experimental Forest. These changes in biogeochemical and environmental conditions suggest that forest clearing does affect mineral soil, and our findings may help identify a mechanism to explain the observed carbon loss from soils in clear-cut forests.

Vario, C.; Friedland, A.

2012-12-01

106

X-ray digital imaging petrography of lunar mare soils: modal analyses of minerals and glasses  

NASA Technical Reports Server (NTRS)

It is essential that accurate modal (i.e., volume) percentages of the various mineral and glass phases in lunar soils be used for addressing and resolving the effects of space weathering upon reflectance spectra, as well as for their calibration such data are also required for evaluating the resource potential of lunar minerals for use at a lunar base. However, these data are largely lacking. Particle-counting information for lunar soils, originally obtained to study formational processes, does not provide these necessary data, including the percentages of minerals locked in multi-phase lithic fragments and fused-soil particles, such as agglutinates. We have developed a technique for modal analyses, sensu stricto, of lunar soils, using digital imaging of X-ray maps obtained with an energy-dispersive spectrometer mounted on an electron microprobe. A suite of nine soils (90 to 150 micrometers size fraction) from the Apollo 11, 12, 15, and 17 mare sites was used for this study. This is the first collection of such modal data on soils from all Apollo mare sites. The abundances of free-mineral fragments in the mare soils are greater for immature and submature soils than for mature soils, largely because of the formation of agglutinitic glass as maturity progresses. In considerations of resource utilization at a lunar base, the best lunar soils to use for mineral beneficiation (i.e., most free-mineral fragments) have maturities near the immature/submature boundary (Is/FeO approximately or = 30), not the mature soils with their complications due to extensive agglutination. The particle data obtained from the nine mare soils confirm the generalizations for lunar soils predicted by L.A. Taylor and D.S. McKay (1992, Lunar Planet Sci. Conf. 23rd, pp. 1411-1412 [Abstract]).

Taylor, L. A.; Patchen, A.; Taylor, D. H.; Chambers, J. G.; McKay, D. S.

1996-01-01

107

[Characteristics of soil organic carbon mineralization at different temperatures in paddy soils under long-term fertilization].  

PubMed

Dynamics of soil organic carbon mineralization affected by long-term fertilizations and temperature in relation to different soil carbon fractions were investigated in paddy soils. Soil samples were collected from the plough layer of 3 long-term national experimental sites in Xinhua, Ningxiang and Taojiang counties of Hunan Province. Mineralization of soil organic C was estimated by 33-day aerobic incubation at different temperatures of 10, 20 and 30 degrees C. The results showed that the rates of CO2 production were higher during the earlier phase (0-13 d) in all treatments, and then decreased according to a logarithm function. Higher incubation temperature strengthened C mineralization in the different treatments. The quantities of cumulative CO2 production in NPK with manure or straw treatments were greater than in inorganic fertilizers treatments. The Q10 values in the different soil treatments ranged from 1.01-1.53. There were significantly positive correlations between the Q10 values and soil total organic carbon (TOC), easy oxidation organic carbon (EOOC), humic acid carbon (C(HA)), fulvic acid carbon (CFA). The cumulative amount of mineralized C was significantly positively correlated with microbial biomass carbon (MBC) at 10 and 20 degrees C, but not significantly at 30 degrees C. Significant correlations were found between the cumulative amount of mineralized C and different soil carbon fractions and C(HA)/C(FA). The correlations of differ- ent soil carbon fractions with the ratio of cumulative mineralized C to TOC were negatively correlated at 10 degrees C, but not significantly at 20 and 30 degrees C. These results suggested that the application of NPK with manure or straw would be helpful to increase the sequestration of C in paddy soils and reduce its contribution of CO2 release in the atmosphere. PMID:25129934

Lin, Shan; Chen, Tao; Zhao, Jin-Song; Xiang, Rong-Biao; Hu, Rong-Gui; Zhang, Shui-Qing; Wang, Mi-Lan; Lu, Zhao-Qi

2014-05-01

108

A comparison of in situ methods for measuring net nitrogen mineralization rates of organic soil amendments.  

PubMed

In situ incubation methods may help provide site-specific estimates of N mineralization from land-applied wastes. However, there are concerns about the reliability of the data generated by the various methods due to containment artifacts. We amended a sandy soil with either poultry manure, biosolids, or yard-waste compost and incubated the mixtures using four in situ methods (buried bags, covered cylinders, standard resin traps, and "new" soil-resin traps) and a conventional laboratory technique in plastic bags. Each incubation device was destructively sampled at 45-d intervals for 180 d and net N mineralization was determined by measuring the amount of inorganic N that accumulated in the soil or soil plus resin traps. Containment effects were evaluated by comparing water content of the containerized soil to a field-reference soil column. In situ incubation methods provided reasonable estimates of short-term (< 45 d) N mineralization, but long-term (> 45 d) mineralization data were not accurate due to a variety of problems specific to each technique. Buried bags and covered cylinders did not retain mineralized N due to water movement into and out of the containers. Neither resin method captured all of the mineralized N that leached through the soil columns, but the new soil-resin trap method tracked field soil water content better than all other in situ methods evaluated. With further refinement and validation, the new soil-resin trap method may be a useful in situ incubation technique for measuring net N mineralization rates of organic soil amendments. PMID:15224949

Hanselman, Travis A; Graetz, Donald A; Obreza, Thomas A

2004-01-01

109

Effect of basic slag addition on soil properties, growth and leaf mineral composition of beans in a Cu-contaminated soil  

E-print Network

in contaminated soils. The BS effects on soil pH, soil conductivity, growth and chemical composition of beans were pH, soil conductivity, and plant growth compared to the untreated soil. At 1 % and 2 % BS addition1 Effect of basic slag addition on soil properties, growth and leaf mineral composition of beans

Paris-Sud XI, Université de

110

Effects of fungicides mancozeb and dinocap on carbon and nitrogen mineralization in soils.  

PubMed

In our study, effects of fungicides mancozeb and dinocap on C and N mineralization were measured in arable and grassland soil. The soils were treated with these fungicides at the application and 10 times lower doses and then incubated at 20 degrees C for 2 weeks. Carbon mineralization (basal and substrate-induced respiration) and nitrogen mineralization (potential ammonification and nitrification) were evaluated 1 and 14 days after the treatment. After 14 days, ammonification was decreased to 48% and 83% at dinocap application dose in arable and grassland soil, respectively. Application dose of mancozeb caused significant decrease of nitrification to 11.2% and 5.6% in arable and grassland soil, respectively. Basal respiration and substrate-induced growth were rather stimulated by fungicides, especially at lower application doses. To conclude, potential risk may exist to soil microorganisms and their activities in soils treated routinely by mancozeb or dinocap. PMID:18755509

Cernohlávková, Jitka; Jarkovský, Jirí; Hofman, Jakub

2009-01-01

111

Temperature Sensitivity of Soil Organic Carbon Mineralization along an Elevation Gradient in the Wuyi Mountains, China  

PubMed Central

Soil organic carbon (SOC) actively participates in the global carbon (C) cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC) mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0–10 cm) from evergreen broad-leaf forest (EBF), coniferous forest (CF), sub-alpine dwarf forest (SDF), and alpine meadow (AM) along an elevational gradient in the Wuyi Mountains, China. The soil samples were incubated at 5, 15, 25, and 35°C with constant soil moisture for 360 days. The temperature sensitivity of SOC mineralization (Q10) was calculated by comparing the time needed to mineralize the same amount of C at any two adjacent incubation temperatures. Results showed that the rates of SOC mineralization and the cumulative SOC mineralized during the entire incubation significantly increased with increasing incubation temperatures across the four sites. With the increasing extent of SOC being mineralized (increasing incubation time), the Q10 values increased. Moreover, we found that both the elevational gradient and incubation temperature intervals significantly impacted Q10 values. Q10 values of the labile and recalcitrant organic C linearly increased with elevation. For the 5–15, 15–25, and 25–35°C intervals, surprisingly, the overall Q10 values for the labile C did not decrease as the recalcitrant C did. Generally, our results suggest that subtropical forest soils may release more carbon than expected in a warmer climate. PMID:23342038

Xu, Xia; Ruan, Honghua; Wang, Jiashe

2013-01-01

112

Paenibacillus ferrarius sp. nov., isolated from iron mineral soil.  

PubMed

A Gram-reaction-positive, endospore-forming, aerobic bacterium, designated strain CY1(T), was isolated from iron mineral soil of Hunan Province, China. The isolate was rod-shaped and motile by means of peritrichous flagella. The major cellular fatty acids were anteiso-C15?:?0 and iso-C16?:?0 and the major quinone was menaquinone 7. The major polar lipids were phosphatidylglycerol and diphosphatidylglycerol phosphatidylethanolamine. The genomic DNA G+C content was 50.5 mol% and the major diagnostic diamino acid in cell-wall peptidoglycan was meso-diaminopimelic acid. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that strain CY1(T) is most closely related to Paenibacillus chondroitinus DSM 5051(T) (97.7?% 16S rRNA gene sequence similarity), Paenibacillus pocheonensis Gsoil 1138(T) (97.4?%) and Paenibacillus frigoriresistens YIM 016(T) (97.0?%). DNA-DNA hybridization dissociation values were lower than 49?% with the most closely related species. On the basis of phenotypic, chemotaxonomic and phylogenetic evidence, strain CY1(T) is affiliated to the genus Paenibacillus, but could be distinguished from the species of this genus. A novel species with the name Paenibacillus ferrarius sp. nov. is proposed. The type strain is CY1(T) (?=?KCTC 33419(T)?=?CCTCC AB 2013369(T)). PMID:25313091

Cao, Yajing; Chen, Fang; Li, Yanzhi; Wei, Sha; Wang, Gejiao

2015-01-01

113

Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil  

Microsoft Academic Search

Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2-ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [[sup 14]C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial

Peter Lindequist Madsen; Jesper Bandsholm Thyme; Kaj Henriksen; P. Moeldrup; Peter Roslev

1999-01-01

114

Stabilization of Soil Organic Matter: Association with Minerals or Chemical Recalcitrance?  

Microsoft Academic Search

Soil organic matter (OM) can be stabilized against decomposition by association with minerals, by its inherent recalcitrance\\u000a and by occlusion in aggregates. However, the relative contribution of these factors to OM stabilization is yet unknown. We\\u000a analyzed pool size and isotopic composition (14C, 13C) of mineral-protected and recalcitrant OM in 12 subsurface horizons from 10 acidic forest soils. The results

Robert Mikutta; Markus Kleber; Margaret S. Torn; Reinhold Jahn

2006-01-01

115

Nutrient Mineralization from Deoiled Neem Seed in a Savanna Soil from Nigeria  

Microsoft Academic Search

The mineralization of nutrients from deoiled neem seed (neem seed cake), the residue left after oil extraction, was examined in a typical savanna soil with a view to determining its potential for fertility improvement. The neem seed cake (NSC) application rates were 0, 2.5, and 5.0 g kg soil (0, 5, and 10 tons ha). The concentrations of ammonium?nitrogen (NH4?N) and nitrate (NO3)?N mineralized

John O. Agbenin; Stephen O. Ibitoye; Abel S. Agbaji

2008-01-01

116

Earthworm species composition affects the soil bacterial community and net nitrogen mineralization  

Microsoft Academic Search

Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for their ecological group classifications, and that earthworm species interactions would affect mineralization through competition and facilitation effects. A mesocosm experiment was conducted to investigate

Maria B. Postma-Blaauw; Jaap Bloem; Jack H. Faber; Jan Willem van Groenigen; Ron G. M. de Goede; Lijbert Brussaard

2006-01-01

117

Characteristics of nitrogen mineralization rates and controlling factors in forest soils in Japanese archipelago  

NASA Astrophysics Data System (ADS)

1. Introduction The nitrogen (N) dynamics in forest soils in the Japanese archipelago varies widely because it extends for 3000 km and the climatic zone ranges from cool-temperate to subtropical region. Therefore, it is necessary to understand the soil N transformation characteristics and its controlling factors across a wide area because the changes in N dynamics due to the climate change are expected to differ from region to region. In this study, we selected more than 30 sites from across the Japanese archipelago and measured net rates of soil N mineralization and nitrification. Also, we measured the physical, chemical and biological properties of soil to clarify the controlling factors. 2. Materials and methods We established an experimental plot (20 * 20 m) at each site, and at each plot, five soil sampling locations were established. At each sampling location, mineral soil samples were collected from 0-10, 10-30, 30-50 cm in depth. Net and gross N mineralization and nitrification rate, soil pH(H2O), water soluble cation (Ca2+, Mg2+, K+, Na+, NH4+, Al3+), anion (Cl-, NO3-, SO42-), and organic carbon (WSOC) were measured. From the net N mineralization and nitrification rate measured by laboratory incubation at three different temperatures (15, 20, 25 °C), Q10min, Q10nit (Q10 of N mineralization and nitrification) and average net rate at 20 °C (N20min and N20nit) were calculated. 3. Results and discussion In most of the sites, net N mineralization and nitrification rates were higher in the shallower soil layers. N20min and N20nit ranged 0.01-3.23 and 0.00-3.00 mgN/kg/d, respectively and Q10min and Q10nit ranged 1.09-24.16 and 1.38-20.10 respectively. There was a pattern that low rates soil (N20 < 0.5 mgN/kg/d) had high Q10 values. Soils which had high N mineralization rates had also high nitrification rates. Soils with high N mineralization and nitrification rate were mostly located in the northern region (Hokkaido Island and Tohoku region) in Japan. This suggests that soil type distribution in the archipelago and soil CN contents are related to the N mineralization and nitrification rates.

Urakawa, R.; Ohte, N.; Shibata, H.; Isobe, K.; Oda, T.; Watanabe, T.; Fukuzawa, K.; Ugawa, S.; Hishi, T.; Enoki, T.; Tateno, R.; Fukushima, K.; Nakanishi, A.; Saigusa, N.; Yamao, Y.; Oyanagi, N.; Hattori, D.; Nakata, M.; Kenta, T.; Toda, H.; Inagaki, Y.; Hirai, K.

2013-12-01

118

A simple method to determine mineralization of (14) C-labeled compounds in soil.  

PubMed

Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (14) C-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (14) C-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (14) C-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(14) C]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (14) C-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (14) C-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices. PMID:24677225

Myung, Kyung; Madary, Michael W; Satchivi, Norbert M

2014-06-01

119

Potential contributions of clay minerals and organic matter to pentachlorophenol retention in soils.  

PubMed

Sorption of pentachlorophenol (PCP) by pure minerals and humic acids were measured to obtain additional perspective on the potential contributions of both clay minerals and soil organic matter (SOM) to contaminants retention in soils. Four types of common soil minerals and two kinds of humic acids (HAs) were tested. The sorption affinity for PCP conformed to an order of HAs > K-montmorillonite > Ca-montmorillonite > goethite > kaolinite. Such a difference in sorption capacity could be attributed to the crucial control of HAs. Clay minerals also had their contribution, especially K-montmorillonite, which played an important, if not dominant, role in the controlling process of PCP sorption. By removing 80% (on average) of the organic carbon from the soils with H(2)O(2), the sorption decreased by an average of 50%. The sorption reversibility had been greatly favored as well. Considering the uncharged mineral fractions in soil before and after H(2)O(2)-treated, the main variation in sorption behavior of the soil might thus be related to the removed organic carbon and the reduced pH. This testified rightly the interactive effect of SOM and clay minerals on PCP sorption as a function of pH. PMID:16481030

He, Yan; Xu, Jianming; Wang, Haizhen; Zhang, Qichun; Muhammad, Akmal

2006-10-01

120

Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils  

NASA Astrophysics Data System (ADS)

Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils Meike Sauerwein1, Alexander Hanke2, Klaus Kaiser3, Karsten Kalbitz2 1) Dept. of Soil Ecology, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany, meike.sauerwein@gmail.com 2) Institute of ecosystem dynamics and biodiversity, University of Amsterdam, 1018 WV, Netherlands, a.hanke@uva.nl, k.kalbitz@uva.nl 3) Soil Sciences, Martin Luther University Halle, 06099 Halle, Germany, klaus.kaiser@landw.uni-halle.de Current knowledge on dissolved organic matter (DOM) in soils is based mainly on observations and experiments in aerobic environments. Adsorption to soil minerals is an important mechanism of DOM retention and stabilization against microbial decay under oxic conditions. Under anoxic conditions where hydrous iron oxides, the potential main adsorbents of DOM, possibly dissolve, the importance of adsorption seems questionable. Therefore, we studied the adsorption of DOM to selected soil minerals and to mineral soils under oxic and anoxic conditions. In detail, we tested the following hypotheses: 1. Minerals and soils adsorb less DOM under anoxic conditions than under oxic ones. 2. The reduced adsorption under anoxic conditions is result of the smaller adsorption to hydrous Fe oxides whereas adsorption to clay minerals and Al hydroxides is not sensitive to changes in redox conditions 3. DOM adsorption will increase with the number of redox cycles, thus time of soil formation, due to increasing contents of poorly crystalline Fe oxides. This will, however, cause a stronger sensitivity to redox changes as poor crystalline Fe oxides are more reactive. 4. Aromatic compounds, being preferentially adsorbed under oxic conditions, will be less strongly adsorbed under anoxic conditions. We chose paddy soils as models because their periodically and regular exposure to changing redox cycles, with anoxic conditions during the rice growing period and oxic conditions during harvest and growth of other crops. Soils of a unique chronosequence of paddy soils (50, 300, 700 and 2000 years) in China were studied in direct comparison to non-paddy soils of the same age. In additions, selected soil minerals (goethite, ferrihydrite, amorphous Al hydroxide, hydrobiotite, nontronite and ripodolite), differing in their response to changes in redox conditions, were studied in order to indentify those mineral constituents responsible for redox-induced changes in DOM adsorption to the test soils. The DOM for the adsorption was extracted from composted rice straw as a surrogate for DOM percolating in paddy soils. Batch adsorption experiments were carried out with DOM pre-incubated to give oxic and anoxic conditions and maintaining these redox conditions during the whole procedure. The redox potential resulting from anoxic pre-incubation was about 100 mV, thus in the range of Fe reduction. Besides of dissolved organic carbon (DOC), we determined changes in the composition of DOM by the specific UV absorbance. We also analyzed main cations, anions and redox-sensitive elements to give a comprehensive picture of the effects of changing redox conditions on the dynamics of organic C, N, P, S, Fe and Al. First results indicated indeed less adsorption of DOM to Fe oxides under anoxic than under oxic conditions, with a more pronounced effect for ferrihydrite than for goethite. Maximum adsorption of DOM was more than 50% larger under oxic than under anoxic conditions. The effect was less pronounced but still detectable for clay minerals such as hydrobiotite, nontronite, and ripodolite. The specific UV absorbance of DOM contact with minerals was 20-50% stronger under anoxic than under oxic conditions. These changes in DOM composition indicated that preferential adsorption of aromatic compounds might be limited to aerated soils. We conclude that adsorption, although less strong than under oxic conditions, is an important mechanism of DOM retention also under anoxic conditions. Decreasi

Sauerwein, Meike; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten

2010-05-01

121

NATIONALLY COORDINATED EVALUATION OF SOIL NITROGEN MINERALIZATION RATE USING A STANDARDIZED AEROBIC INCUBATION PROTOCOL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aerobic incubation methods have been widely used to assess soil nitrogen (N) mineralization, but standardized protocols are lacking. A silt loam soil (Catlin silt loam; fine-silty, mixed, superactive, mesic, Oxyaquic Arguidoll) was subjected to aerobic incubation at six USDA-ARS locations using a ...

122

Factors Affecting Mineral Nitrogen Transformations by Soil Heating: A Laboratory Simulated Fire Study.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two forest soils from the Sierra Nevada Mountains of California were brought into the laboratory and subjected to simulated burning in a muffle furnace at several durations, oven temperatures, and water contents. Soils were analyzed for NO3-, NH4+, mineral N, total N, total C, and C:N responses to t...

123

Soil mineral genesis and distribution in a saline lake landscape of the Pantanal Wetland, Brazil  

E-print Network

Soil mineral genesis and distribution in a saline lake landscape of the Pantanal Wetland, Brazil S Geografia, Universidade de São Paulo, São Paulo, Brazil b Soil & Water Sciences Program, Department São Paulo, Piracicaba, Brazil a b s t r a c ta r t i c l e i n f o Article history: Received 20 August

Ahmad, Sajjad

124

INFLUENCE OF CRY1AC TOXIN ON MINERALIZATION AND BIOAVAILABILITY OF GLYPHOSATE IN SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

The impact of transgenic plants containing Bacillus thuringiensis (Bt) toxin on soil processes has received recent attention. In these studies we examined the influence of the lepidopterean Bt Cry1Ac toxin on mineralization and bioavailability of the herbicide glyphosate in two different soils. The ...

125

Nitrogen Mineralization of Broiler Litter Applied to Southeastern Coastal Plain Soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

A field study was conducted to determine nitrogen (N) mineralization of broiler litter (BL) in two Coastal Plain soils of differing texture, sandy or clayey. The soils were a Tifton loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) and a Greenville sandy clay loam (clayey, kaoliniti...

126

A Simulation of the Interaction of Acid Rain with Soil Minerals  

ERIC Educational Resources Information Center

The atmospheric issue of acid rains is subjected to a five-part laboratory experiment by concentrating on the chemistry of the infiltration process of acid rainwater through soils. This procedure of quantitative scrutiny helps students realize the efficacy of soil minerals in the consumption of surplus acidity in rainwater.

Schilling, Amber L.; Hess, Kenneth R.; Leber, Phyllis A.; Yoder, Claude H.

2004-01-01

127

MINERALIZATION OF NITROGEN FROM BROILER LITTER AS AFFECTED BY SOIL TEXTURE IN THE SOUTHEASTERN COASTAL PLAIN  

Technology Transfer Automated Retrieval System (TEKTRAN)

A field study was conducted during 2004-2005 to determine nitrogen (N) mineralization of broiler litter (BL) in two Coastal Plain soils of differing texture, sandy or clayey. The soils were a Tifton loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) and a Greenville sandy clay loam (...

128

Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization.  

PubMed

This survey aimed to compare mercury concentrations in soils related to geology and mineralization types of mines. A total of 16,386 surface soils (0~15 cm in depth) were taken from agricultural lands near 343 abandoned mines (within 2 km from each mine) and analyzed for Hg by AAS with a hydride-generation device. To meaningfully compare mercury levels in soils with geology and mineralization types, three subclassification criteria were adapted: (1) five mineralization types, (2) four valuable ore mineral types, and (3) four parent rock types. The average concentration of Hg in all soils was 0.204 mg kg(-1) with a range of 0.002-24.07 mg kg(-1). Based on the mineralization types, average Hg concentrations (mg kg(-1)) in the soils decreased in the order of pegmatite (0.250) > hydrothermal vein (0.208) > hydrothermal replacement (0.166) > skarn (0.121) > sedimentary deposits (0.045). In terms of the valuable ore mineral types, the concentrations decreased in the order of Au-Ag-base metal mines ? base metal mines > Au-Ag mines > Sn-W-Mo-Fe-Mn mines. For parent rock types, similar concentrations were found in the soils derived from sedimentary rocks and metamorphic rocks followed by heterogeneous rocks with igneous and metamorphic processes. Furthermore, farmland soils contained relatively higher Hg levels than paddy soils. Therefore, it can be concluded that soils in Au, Ag, and base metal mines derived from a hydrothermal vein type of metamorphic rocks and pegmatite deposits contained relatively higher concentrations of mercury in the surface environment. PMID:21814815

Kim, Han Sik; Jung, Myung Chae

2012-01-01

129

Differential adsorption of occluded and nonoccluded insect-pathogenic viruses to soil-forming minerals.  

PubMed

Soil represents the principal environmental reservoir of many insect-pathogenic viruses. We compared the adsorption and infectivity of one occluded and two nonoccluded viruses, Helicoverpa armigera single nucleopolyhedrovirus (HaSNPV) (Baculoviridae), Cricket paralysis virus (CrPV) (Dicistroviridae), and Invertebrate iridescent virus 6 (IIV-6) (Iridoviridae), respectively, in mixtures with a selection of soil-forming minerals. The relative infective titers of HaSNPV and CrPV were unchanged or slightly reduced in the presence of different minerals compared to their titers in the absence of the mineral. In contrast, the infective titer of IIV-6 varied according to the mineral being tested. In adsorption studies, over 98% of HaSNPV occlusion bodies were adsorbed by all the minerals, and a particularly high affinity was observed with ferric oxide, attapulgite, and kaolinite. In contrast, the adsorption of CrPV and IIV-6 differed markedly with mineral type, with low affinity to bentonites and high affinity to ferric oxide and kaolinite. We conclude that interactions between soil-forming minerals and insect viruses appear to be most important in nucleopolyhedroviruses, followed by invertebrate iridescent viruses, and least important in CrPV, which may reflect the ecology of these pathogens. Moreover, soils with a high content of iron oxides or kaolinite would likely represent highly effective reservoirs for insect-pathogenic viruses. PMID:16820456

Christian, Peter D; Richards, Andrew R; Williams, Trevor

2006-07-01

130

Mineral characteristics of leaves of plants from different phylogeny grown in various soil types in the temperate region  

Microsoft Academic Search

The objective of this research was to analyze selected minerals in leavesof plants, belonging to 166 species growing in alluvial, low pH, brownforest and serpentine soils. Mineral characteristics of the soils involved werealso determined.For the macronutrients, in trees grown in alluvial soil, N, P, Ca, and Mgconcentrations of leaves were higher in recently evolved plants than inplants with a longer

M. Osaki; S. Yamada; T. Ishizawa; T. Watanabe; T. Shinano

2003-01-01

131

Mineral Contamination from Cemetery Soils: Case Study of Zandfontein Cemetery, South Africa  

PubMed Central

The burial of coffins may pose an environmental and health hazard since the metals that are used in coffin-making may corrode or degrade into harmful toxins. These may leach into the surrounding soils and groundwater. Very little research has been conducted world-wide on the mineral contamination potential of cemeteries, and virtually none in South Africa. The aim of the study is to determine whether burial practices affect the mineral content of soils in cemeteries. This was done by comparing the mineral concentrations of soils within the Zandfontein Cemetery in Tshwane (Gauteng, South Africa) to those off-site as well as those in zones with high burial loads with those zones with fewer burials. Twenty three soil samples were collected from various sites on- and off-site and analyzed for 31 minerals using ICP-AES. It was found that mineral concentrations of soils within the Zandfontein Cemetery were considerably higher than those off-site. Soil samples in multiple burials blocks also have elevated metal concentrations. These excess metals are probably of anthropogenic origin associated with burial practices and could pose an environmental and human health hazard. Strict monitoring of water quality in boreholes in the vicinity of the cemetery is recommended. PMID:22470306

Jonker, Cornelia; Olivier, Jana

2012-01-01

132

Lunar mineral feedstocks from rocks and soils: X-ray digital imaging in resource evaluation  

NASA Technical Reports Server (NTRS)

The rocks and soils of the Moon provide raw materials essential to the successful establishment of a lunar base. Efficient exploitation of these resources requires accurate characterization of mineral abundances, sizes/shapes, and association of 'ore' and 'gangue' phases, as well as the technology to generate high-yield/high-grade feedstocks. Only recently have x-ray mapping and digital imaging techniques been applied to lunar resource evaluation. The topics covered include inherent differences between lunar basalts and soils and quantitative comparison of rock-derived and soil-derived ilmenite concentrates. It is concluded that x-ray digital-imaging characterization of lunar raw materials provides a quantitative comparison that is unattainable by traditional petrographic techniques. These data are necessary for accurately determining mineral distributions of soil and crushed rock material. Application of these techniques will provide an important link to choosing the best raw material for mineral beneficiation.

Chambers, John G.; Patchen, Allan; Taylor, Lawrence A.; Higgins, Stefan J.; Mckay, David S.

1994-01-01

133

Clay Mineral Formation and Transformation in Rocks and Soils  

Microsoft Academic Search

Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most

D. D. Eberl; V. C. Farmer; R. M. Barrer

1984-01-01

134

Soil-specific response functions of organic matter mineralization to the availability of labile carbon.  

PubMed

Soil organic matter (SOM) mineralization processes are central to the functioning of soils in relation to feedbacks with atmospheric CO2 concentration, to sustainable nutrient supply, to structural stability and in supporting biodiversity. Recognition that labile C-inputs to soil (e.g. plant-derived) can significantly affect mineralization of SOM ('priming effects') complicates prediction of environmental and land-use change effects on SOM dynamics and soil C-balance. The aim of this study is to construct response functions for SOM priming to labile C (glucose) addition rates, for four contrasting soils. Six rates of glucose (3 atm% (13) C) addition (in the range 0-1 mg glucose g(-1) soil day(-1) ) were applied for 8 days. Soil CO2 efflux was partitioned into SOM- and glucose-derived components by isotopic mass balance, allowing quantification of SOM priming over time for each soil type. Priming effects resulting from pool substitution effects in the microbial biomass ('apparent priming') were accounted for by determining treatment effects on microbial biomass size and isotopic composition. In general, SOM priming increased with glucose addition rate, approaching maximum rates specific for each soil (up to 200%). Where glucose additions saturated microbial utilization capacity (>0.5 mg glucose g(-1) soil), priming was a soil-specific function of glucose mineralization rate. At low to intermediate glucose addition rates, the magnitude (and direction) of priming effects was more variable. These results are consistent with the view that SOM priming is supported by the availability of labile C, that priming is not a ubiquitous function of all components of microbial communities and that soils differ in the extent to which labile C stimulates priming. That priming effects can be represented as response functions to labile C addition rates may be a means of their explicit representation in soil C-models. However, these response functions are soil-specific and may be affected by several interacting factors at lower addition rates. PMID:23505211

Paterson, Eric; Sim, Allan

2013-05-01

135

Comparison of soil CO2 emission in poorly and well-drained mineral soil at a small agricultural hillside scale  

NASA Astrophysics Data System (ADS)

The increase of greenhouse gases (GHG) in the atmosphere and the climate change which results from it, will have major effects in the 21th century. In agricultural landscapes and others ecosystems, soil CO2 emissions are controlled by thermal and hydrological regimes, but their relative importance seems to be dependant of soil drainage conditions. The purpose of this study was to measure and model soil CO2 emissions at the scale of a hillslope presenting a gradient of soil drainage conditions. The studied hillslope is located in the Kervidy-Naizin headwater catchment (Brittany, France, 48°00'N 2°50W) and corresponds to an agricultural field cropped in a maize / winter wheat rotation. Soil CO2 emissions were measured once per week from February 2013 to March 2014, in two locations contrasting by soil drainage condition: (1) well-drained mineral (WDM) soil classified as Cambisol in upslope position, (2) poorly-drained mineral (PDM) soil classified as Haplic Albeluvisol and which undergoes continuous or periodic saturation and reduction conditions in downslope position. The measurement sites of 9m2 were equipped for continuous measurement of soil water content (TDR probes) and soil temperature. Soil CO2 emissions were measured with the infrared gas analyzer (IRGA) Li-8100A (Li-Cor, Lincoln, USA) until now. Results showed that PDM soils were waterlogged in winter and autumn inducing a low CO2 emission (average of 1.1±0.2µmol.m-2.s-1) which was two times lower than CO2 emissions in WDM soil. A shift of soil moisture to field capacity leading to an availability of oxygen in soil in the spring and summer induced an increase of soil CO2 emissions in PDM soil with a maximum of 5.03±0.5µmol.m-2.s-1 at the end of July. In WDM soil, CO2 emissions were high at the end of spring (average of 7µmol.m-2.s-1) and decreased of 65% at the end of summer because of the drought conditions. The modeling of temporal variability of soil CO2 emission by temperature and moisture empirical functions showed that the combined effect of soil temperature and soil moisture explained 77% (61% by T° and 39% by SWC) of soil CO2 emission variability in PDM soil, against 63% (53% by T° and 47% by SWC) in WDM soil. Others factors such as C input, and oxygen availability due to soil management may also controlled soil CO2 emission and mostly in WDM soil. The integration of these factors in model could help to well understand the difference in soil CO2 emission in Poorly-drained mineral soil compared with well-drained soil at agricultural hillside scale.

TETE, Emmanuel; Viaud, Valerie; Flechard, Chris; Walter, Christian

2014-05-01

136

Soil microbial activity and structure in mineralized terranes of the Western US  

NASA Astrophysics Data System (ADS)

Mineralized terranes (areas enriched in metal-bearing minerals) occur throughout the Western US, and are characterized by highly variable soil trace metal concentrations across small spatial scales. Assuming that non-lithologic (extrinsic) soil forming factors are relatively constant between mineralized and unmineralized zones, these mineralized areas allowed us to evaluate the effect of lithology on soil microbial activity. We established the following study sites: 1) sage-grassland on a Mo/Cu deposit (Battle Mountain, NV); 2) pine-chaparral on Ni/Cr bearing rocks (Chinese Camp, CA); and 3) two pine woodland sites on acid-sulfate altered rocks (Reno, NV; Bridgeport, CA). Microbial, physical and chemical measurements were performed on soils from undisturbed mineralized areas and adjacent unmineralized areas to determine baseline conditions for comparison to sites disturbed by mining. A host of abiotic soil parameters, along with bioavailable (diethylenetriaminepentaacetic acid (DTPA)-extractable) and total metals, were measured to examine their correlation with the following measures of microbial activity: enzyme assays (arylsulfatase, phosphatase, fluorescein diacetate hydrolysis), C/N mineralization potential, C substrate utilization (Biolog Ecoplate), and microbial biomass and community structure (phospholipid fatty acid analysis). Within the Battle Mountain study area, both microbial activity and structure were statistically similar between mineralized and unmineralized soils. Nutrient and metal concentrations were also similar; the only differences being higher Cu and lower P in the mineralized soils. Within the Chinese Camp study area, soil organic carbon and total nitrogen concentrations were similar between the serpentine (Ni/Cr bearing) and adjacent andesite soils, while differences were noted for other nutrients (S, P, Ca, Mg). For the serpentine soils, Co, Fe, Mn, and Ni showed the strongest correlations with microbial activity, where Cr, Mn showed the strongest correlations in the andesite soils. Measures of microbial activity were statistically similar, except for arylsulfatase and Biolog C substrate utilization, which were greater in the andesite soils. Biolog substrate utilization richness was greater for the andesite soils, which also showed greater fungal biomass compared to the serpentine soils. In the acid sulfate systems, most measures of microbial activity were reduced in the acid sulfate soils compared to the adjacent andesite soils. Lower pH and P, and greater Al concentrations in the acid sulfate soils are potential inhibitors of microbial activity, while greater concentrations of inorganic N suggest that N is not limiting in the acid sulfate soils. Biolog substrate utilization richness was much lower in the acid sulfate soils, which also exhibited a greater proportion of polymer and carbohydrate use compared to the andesite soils. Impacts on microbial activity and microbial community structure are depend on a combination of trace metal and nutrient concentrations within a given mineralization type. Improving our understanding of biotic/abiotic relationships in undisturbed systems should increase our understanding of these relationships in areas disturbed by mining.

Blecker, S. W.; Stillings, L. L.; Decrappeo, N.; Ippolito, J.

2009-12-01

137

Recovery of Minerals in Martian Soils Via Supercritical Fluid Extraction  

NASA Astrophysics Data System (ADS)

We are investigating the use of supercritical fluids to extract mineral and/or carbonaceous material from Martian surface soils and its igneous crust. Two candidate supercritical fluids are carbon dioxide and water. The Martian atmosphere is composed mostly of carbon dioxide (approx. 95.3%) and could therefore provide an in-situ source of carbon dioxide. Water, although present in the Martian atmosphere at only approx. 0.03%, is also a candidate supercritical solvent. Previous work done with supercritical fluids has focused primarily on their solvating properties with organic compounds. Interestingly, the first work reported by Hannay and Hogarth at a meeting of the Royal Society of London in 1879 observed that increasing or decreasing the pressure caused several inorganic salts e.g., cobalt chloride, potassium iodide, and potassium bromide, to dissolve or precipitate in supercritical ethanol. In high-pressure boilers, silica, present in most boiler feed waters, is dissolved in supercritical steam and transported as dissolved silica to the turbine blades. As the pressure is reduced the silica precipitates onto the turbine blades eventually requiring the shutdown of the generator. In supercritical water oxidation processes for waste treatment, dissolved salts present a similar problem. The solubility of silicon dioxide (SiO2) in supercritical water is shown. The solubility curve has a shape characteristic of supercritical systems. At a high pressure (greater than 1750 atmospheres) increasing the temperature results in an increase in solubility of silica, while at low pressures, less than 400 atm., the solubility decreases as temperature increases. There are only a few studies in the literature where supercritical fluids are used in extractive metallurgy. Bolt modified the Mond process in which supercritical carbon monoxide was used to produce nickel carbonyl (Ni(CO)4). Tolley and Tester studied the solubility of titanium tetrachloride (TiCl4) in supercritical CO2. They reported complete miscibility of TiCl4 with supercritical CO2 (infinite solubility). At 1500 psig, TiCl4 and CO2 form a single liquid phase below 50 C. Tolley et al. also reported on the solubility and thermodynamics of tin tetrachloride in supercritical CO2. Some of their data for TiC14 are shown. Three criteria have been suggested to predict which materials are suitable for supercritical extraction: 1) Hydrocarbons or lipophilic compounds of low molecular weight and polarity are easily extracted with supercritical CO2. 2) Compounds with polar groups are not easily extracted with supercritical CO2. 3) Separation of mixtures is facilitated if components differing mass, vapor pressure, or polarity.

Debelak, Kenneth A.; Roth, John A.

2001-03-01

138

Soil moisture influenced the interannual variation in temperature sensitivity of soil organic carbon mineralization in the Loess Plateau  

NASA Astrophysics Data System (ADS)

Temperature sensitivity of SOC mineralization (Q10) determines how strong the feedback from global warming may be on the atmospheric CO2 concentration, thus understanding the factors influencing the interannual variation in Q10 is important to accurately estimate the local soil carbon cycle. In situ SOC mineralization was measured using an automated CO2 flux system (Li-8100) in long-term bare fallow soil in the Loess Plateau (35° 12' N, 107° 40' E) in Changwu, Shaanxi, China form 2008 to 2013. The results showed that the annual cumulative SOC mineralization ranged from 226 to 298 g C m-2 y-1 (mean =253 g C m-2 y-1; CV =13%), annual Q10 ranged from 1.48 to 1.94 (mean =1.70; CV =10%), and annual soil moisture content ranged from 38.6 to 50.7% WFPS (mean =43.8% WFPS; CV =11%), which were mainly affected by the frequency and distribution of precipitation. Annual Q10 showed a negative quadratic correlation with soil moisture. In conclusion, understanding of the relationships between interannual variation in Q10 of SOC mineralization, soil moisture and precipitation is important to accurately estimate the local carbon cycle, especially under the changing climate.

Zhang, Y.; Guo, S.; Zhao, M.; Du, L.; Li, R.; Jiang, J.; Wang, R.; Li, N.

2015-01-01

139

Effects of flooding and warming on soil organic matter mineralization in Avicennia germinans mangrove forests and Juncus roemerianus salt marshes  

NASA Astrophysics Data System (ADS)

Under a changing climate, coastal wetlands experience sea level rise, warming, and vegetation change, all of which may influence organic matter mineralization. In coastal wetlands of subtropical west-central Florida (USA), we investigated how soil carbon (C) and nitrogen (N) mineralization respond to soil water, temperature, and ecosystem type (Avicennia germinans mangrove forest vs. Juncus roemerianus salt marsh). We evaluated how soil respiration and mineral N concentration varied along a soil moisture gradient, and whether these relationships differed between ecosystem types. Then, we manipulated soils in a 28-d laboratory incubation to evaluate how potentially mineralizable C and N respond to temperature (23 vs. 27 °C), soil hydroperiod (inundated 4 vs. 20 h/d), and soil source. Soil saturation and inundation suppressed short-term (minutes to weeks) C mineralization from near-surface soils. Soil CO2 efflux declined by 65% as soil moisture increased from 75% to 85%, and potentially mineralizable C was 18% lower with a 20-h hydroperiod than with a 4-h hydroperiod. Organic C quality appears to be greater in A. germinans than in J. roemerianus soils, as A. germinans soils had higher field CO2 efflux rates and greater mineralizable C:N (despite lower total C:N). Increasing incubation temperature from 23 to 27 °C elevated potentially mineralizable C by 40%, indicating that two symptoms of climate change (increased inundation from sea level rise, and warming) may have opposing effects on soil C mineralization. Temperature sensitivity of C mineralization was high for long-hydroperiod soils, however, suggesting that protection of soil organic matter (SOM) due to prolonged inundation will be undermined by warming. Potentially mineralizable N was greater in J. roemerianus soils, although in situ mineral N was not different between ecosystems, instead correlating positively with SOM. These results indicate that models forecasting soil elevation responses to climate change might include inundation effects on mineralization rates.

Lewis, David Bruce; Brown, Jewel A.; Jimenez, Kristine L.

2014-02-01

140

Correlation of the Abundance of Betaproteobacteria on Mineral Surfaces with Mineral Weathering in Forest Soils  

PubMed Central

Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia. PMID:22798365

Lepleux, C.; Turpault, M. P.; Oger, P.; Frey-Klett, P.

2012-01-01

141

Microbes residing in young organic rich Alaskan soils contain older carbon than those residing in old mineral high Arctic soils  

NASA Astrophysics Data System (ADS)

Arctic soils range from very organic rich to low carbon and mineral-dominated soils. At present, we do not yet fully understand if all carbon in the Arctic is equally vulnerable to mineralization in a warmer climate. Many studies have demonstrated that ancient carbon is respired when permafrost has thawed, yet our understanding of the active layer and permafrost carbon dynamics is still emerging. In an effort to remedy this disconnect between our knowledge of surface fluxes and below ground processes, we used radiocarbon to examine the microbial carbon dynamics in soil cores from organic rich soils near Barrow, Alaska and mineral soils from the Canadian high Arctic. Specifically, we compared the microbial community using lipid biomarkers, the inputs of carbon using n-alkanes and measured the 14C of both the bulk organic carbon and of the microbial lipids. In theory, the microbial lipids (phospholipid fatty acids, PLFA) represent the viable microbial community, as these lipids are hydrolyzed quickly after cell death. Variations in the PLFA distributions suggested that different microbial communities inhabit organic rich Alaskan soils and those of the Canadian high Arctic. When the PLFA concentrations were converted to cellular concentration, they were within the same order of magnitude (1 to 5 x 108 cells/g dry soil) with slightly higher cell concentrations in the organic rich Alaskan soils. When these cellular concentrations were normalized to the organic carbon content, the Canadian high Arctic soils contained a greater proportion of microbes. Although bulk organic carbon 14C of Alaskan soils indicated more recent carbon inputs into the soil than the Canadian high Arctic soils, the 14C of the PLFA revealed the opposite. For corresponding depth horizons, microbes in Alaskan soils were consuming carbon 1000 to 1500 years older than those in the Canadian high Arctic. Differences between the 14C content of bulk organic carbon and the microbial lipids were much smaller in Alaskan soil than that of the Canadian high Arctic soil, indicating that Alaskan microbes were interacting with the bulk organic carbon pool and Canadian high Arctic soil microbes were disconnected from the bulk organic carbon pool. Additionally, dissimilarities in the n-alkane distributions suggest vastly different carbon sources to these different soils. Collectively, these results suggest that (a) these Arctic soils contain a comparable abundance of microbes, (b) the organic carbon being accumulated in the Alaskan soil is likely from recent biomass, (c) mineral soil accumulation in the Canadian high Arctic is likely due to erosional inputs of ancient carbon and (d) the carbon stocks in Alaskan soils are more bioavailable to the microbes than those in mineral soils of the Canadian high Arctic. Incubation studies that incorporate gas fluxes and proteomics may tease apart if the observed differences in bioavailability are a function of temperature, substrate availability or some other variable.

Ziolkowski, L. A.; Slater, G. F.; Onstott, T. C.; Whyte, L.; Townsend-Small, A.

2013-12-01

142

High temperature and salinity enhance soil nitrogen mineralization in a tidal freshwater marsh.  

PubMed

Soil nitrogen (N) mineralization in wetlands is sensitive to various environmental factors. To compare the effects of salinity and temperature on N mineralization, wetland soils from a tidal freshwater marsh locating in the Yellow River Delta was incubated over a 48-d anaerobic incubation period under four salinity concentrations (0, 10, 20 and 35‰) and four temperature levels (10, 20, 30 and 40°C). The results suggested that accumulated ammonium nitrogen (NH4+-N) increased with increasing incubation time under all salinity concentrations. Higher temperatures and salinities significantly enhanced soil N mineralization except for a short-term (?10 days) inhibiting effect found under 35‰ salinity. The incubation time, temperature, salinity and their interactions exhibited significant effects on N mineralization (P<0.001) except the interactive effect of salinity and temperature (P>0.05), while temperature exhibited the greatest effect (P<0.001). Meanwhile, N mineralization processes were simulated using both an effective accumulated temperature model and a one-pool model. Both models fit well with the simulation of soil N mineralization process in the coastal freshwater wetlands under a range of 30 to 40°C (R2?=?0.88-0.99, P<0.01). Our results indicated that an enhanced NH4+-N release with increasing temperature and salinity deriving from the projected global warming could have profound effects on nutrient cycling in coastal wetland ecosystems. PMID:24733366

Gao, Haifeng; Bai, Junhong; He, Xinhua; Zhao, Qingqing; Lu, Qiongqiong; Wang, Junjing

2014-01-01

143

Carbon Mineralizability Determines Interactive Effects on Mineralization of Pyrogenic Organic Matter and Soil Organic Carbon  

SciTech Connect

Soil organic carbon (SOC) is a critical and active pool in the global C cycle, and the addition of pyrogenic organic matter (PyOM) has been shown to change SOC cycling, increasing or decreasing mineralization rates (often referred to as priming). We adjusted the amount of easily mineralizable C in the soil, through 1-day and 6-month pre-incubations, and in PyOM made from maple wood at 350°C, through extraction. We investigated the impact of these adjustments on C mineralization interactions, excluding pH and nutrient effects and minimizing physical effects. We found short-term increases (+20-30%) in SOC mineralization with PyOM additions in the soil pre-incubated for 6 months. Over the longer term, both the 6-month and 1-day pre-incubated soils experienced net ~10% decreases in SOC mineralization with PyOM additions. This was possibly due to stabilization of SOC on PyOM surfaces, suggested by nanoscale secondary ion mass spectrometry. Additionally, the duration of pre-incubation affected priming interactions, indicating that there may be no optimal pre-incubation time for SOC mineralization studies. We show conclusively that relative mineralizability of SOC in relation to PyOM-24 C is an important determinant of the effect of PyOM additions on SOC mineralization.

Whitman, Thea L.; Zhu, Zihua; Lehmann, Johannes C.

2014-10-31

144

High Temperature and Salinity Enhance Soil Nitrogen Mineralization in a Tidal Freshwater Marsh  

PubMed Central

Soil nitrogen (N) mineralization in wetlands is sensitive to various environmental factors. To compare the effects of salinity and temperature on N mineralization, wetland soils from a tidal freshwater marsh locating in the Yellow River Delta was incubated over a 48-d anaerobic incubation period under four salinity concentrations (0, 10, 20 and 35‰) and four temperature levels (10, 20, 30 and 40°C). The results suggested that accumulated ammonium nitrogen (NH4+-N) increased with increasing incubation time under all salinity concentrations. Higher temperatures and salinities significantly enhanced soil N mineralization except for a short-term (?10 days) inhibiting effect found under 35‰ salinity. The incubation time, temperature, salinity and their interactions exhibited significant effects on N mineralization (P<0.001) except the interactive effect of salinity and temperature (P>0.05), while temperature exhibited the greatest effect (P<0.001). Meanwhile, N mineralization processes were simulated using both an effective accumulated temperature model and a one-pool model. Both models fit well with the simulation of soil N mineralization process in the coastal freshwater wetlands under a range of 30 to 40°C (R2?=?0.88–0.99, P<0.01). Our results indicated that an enhanced NH4+-N release with increasing temperature and salinity deriving from the projected global warming could have profound effects on nutrient cycling in coastal wetland ecosystems. PMID:24733366

Gao, Haifeng; Bai, Junhong; He, Xinhua; Zhao, Qingqing; Lu, Qiongqiong; Wang, Junjing

2014-01-01

145

Forest type affects the coupled relationships of soil C and N mineralization in the temperate forests of northern China.  

PubMed

Decomposition of soil organic matter (SOM) is sensitive to vegetation and climate change. Here, we investigated the influence of changes in forest types on the mineralization of soil carbon (C) and nitrogen (N), and their temperature sensitivity (Q10) and coupling relationships by using a laboratory soil incubation experiments. We sampled soils from four forest types, namely, a primary Quercus liaotungensis forest (QL), Larix principis-rupprechtii plantation (LP), Pinus tabulaeformis plantation (PT), and secondary shrub forest (SS) in temperate northern China. The results showed that soil C and N mineralization differed significantly among forest types. Soil C and N mineralization were closely coupled in all plots, and C:N ratios of mineralized SOM ranged from 2.54 to 4.12. Forest type significantly influenced the Q10 values of soil C and N mineralization. The activation energy (Ea) of soil C and N mineralization was negatively related to the SOM quality index in all forest types. The reverse relationships suggested that the carbon quality-temperature (CQT) hypothesis was simultaneously applicable to soil C and N mineralization. Our findings show that the coupled relationships of soil C and N mineralization can be affected by vegetation change. PMID:25322802

Quan, Quan; Wang, Changhui; He, Nianpeng; Zhang, Zhen; Wen, Xuefa; Su, Hongxin; Wang, Qing; Xue, Jingyue

2014-01-01

146

Forest type affects the coupled relationships of soil C and N mineralization in the temperate forests of northern China  

PubMed Central

Decomposition of soil organic matter (SOM) is sensitive to vegetation and climate change. Here, we investigated the influence of changes in forest types on the mineralization of soil carbon (C) and nitrogen (N), and their temperature sensitivity (Q10) and coupling relationships by using a laboratory soil incubation experiments. We sampled soils from four forest types, namely, a primary Quercus liaotungensis forest (QL), Larix principis-rupprechtii plantation (LP), Pinus tabulaeformis plantation (PT), and secondary shrub forest (SS) in temperate northern China. The results showed that soil C and N mineralization differed significantly among forest types. Soil C and N mineralization were closely coupled in all plots, and C:N ratios of mineralized SOM ranged from 2.54 to 4.12. Forest type significantly influenced the Q10 values of soil C and N mineralization. The activation energy (Ea) of soil C and N mineralization was negatively related to the SOM quality index in all forest types. The reverse relationships suggested that the carbon quality-temperature (CQT) hypothesis was simultaneously applicable to soil C and N mineralization. Our findings show that the coupled relationships of soil C and N mineralization can be affected by vegetation change. PMID:25322802

Quan, Quan; Wang, Changhui; He, Nianpeng; Zhang, Zhen; Wen, Xuefa; Su, Hongxin; Wang, Qing; Xue, Jingyue

2014-01-01

147

Organic matter protection as affected by the mineral soil matrix: allophanic vs. non-allophanic volcanic ash soils  

NASA Astrophysics Data System (ADS)

Volcanic ash soils (Andosols) contain the largest amounts of organic carbon of all mineral soil types. Chemical (complexes of organic matter with allophane, Al/Fe) and physical (aggregation) mechanisms are protecting the carbon from decomposition. While allophanic Andosols are dominated by short range order minerals such as allophane, imogolite and ferrihydrite, organic matter-Al/Fe complexes dominate non-allophanic Andosols. Consequently, chemical interactions between the mineral soil matrix and organic matter differ between these two soil types. This difference could potentially lead to different organic matter compositions. In this study, the organic matter of Ah horizons of an allophanic Andosol with a non-allophanic Andosol from Madeira Island is compared using analytical pyrolysis. Both volcanic soil types showed a relative decrease of lignin-derived pyrolysis products with depth, but this decrease was more pronounced in the allophanic Andosol. Polysaccharides were more abundant in the allophanic Ah horizon, particularly at lower depth, and this was also the case for the non-plant-derived N-containing polysaccharide chitin. Most likely, these biopolymers are adsorbed onto short range order minerals such as allophane and therefore were better protected in the allophanic Andosol. In addition, the higher chitin contents combined with the more pronounced lignin degradation suggests a higher fungal activity. Aliphatic pyrolysis products (n-alkenes/n-alkanes, fatty acids) were relatively more enriched in the non-allophanic Andosol. Lower microbial activity caused by the more acidic pH and higher levels of (toxic) aluminium are the most plausible reasons for the accumulation of these compounds in the non-allophanic Andosol. Although the allophanic and non-allophanic Andosol resembled each other in containing biopolymer groups of the same orders of magnitudes, in particular the contents of chitin and aliphatic compounds were distinctly affected by the differences in organic matter stabilizing properties and capacity of the mineral soil matrices.

Nierop, K. G. J.; Kaal, J.; Jansen, B.; Naafs, D. F. W.

2009-04-01

148

Iron Redox Cycling Drives Decomposition of Mineral-Associated C in Humid Tropical Forest Soils  

NASA Astrophysics Data System (ADS)

The stabilization of soil carbon (C) by reactive minerals and an inhibition of decomposition due to oxygen (O2) limitation (reducing conditions) have been proposed as drivers of the high soil C concentrations characteristic of humid tropical forests, which constitute a major terrestrial C reservoir. Here, we examined relationships between these factors and spatial patterns of C concentrations and C turnover (using radiocarbon modeling) in surface soils of the Luquillo Experimental Forest, Puerto Rico. We used concentrations of reduced iron (Fe(II)) as an index of reducing conditions given the importance of Fe reduction to anaerobic metabolism in these soils. Concentrations of Fe(II), reactive iron and aluminum (Al) minerals, interactions between Fe(II) and Al, and live fine root biomass explained most variation in C concentrations across the landscape (pseudo R2 = 0.84). Carbon increased with chelatable "poorly crystalline" Fe, in agreement with previous research, but C decreased with citrate/ascorbate extractable Fe, an index of Fe oxides susceptible to microbial reduction. We suggest that availability of Fe oxides to sustain anaerobic respiration partially offsets soil C accumulation in these ecosystems, despite the role of a subset of reactive Fe in promoting C stabilization. We estimated decomposition rates of mineral-associated C using 14C content of the heavy soil density fraction from a subset of samples. Turnover times averaged 108 years but decreased with Fe(II) concentrations. Thus, our data suggest that Fe redox cycling in soil microsites is associated with increased turnover of mineral-associated C in this fluctuating-oxygen environment, implying that the capacity of reactive metals to stabilize C may be partially contingent on O2 dynamics. Our results suggest a multifaceted role for reactive minerals in soil C cycling, emphasizing the importance of ecosystem-scale interactions among geochemical, physical, and biological factors.

Hall, S. J.; Mcnicol, G.; Silver, W. L.

2013-12-01

149

Fly ash addition affects microbial biomass and carbon mineralization in agricultural soils.  

PubMed

The microbial biomass carbon (MBC) and carbon mineralization of fly ash (FA) amended soil at (0 %, 1.25 %, 2.5 %, 5 %, 10 % and 20 % FA; v/v) was investigated under laboratory conditions for 120 days at 60 % soil water-holding capacity and 25 ± 1°C temperature. The results demonstrated that soil respiration and microbial activities were not suppressed up to 2.5 % FA amendment and these activities decreased significantly at 10 % and 20 % FA treatment with respect to control. Application of 10 % and 20 % FA treated soils showed a decreasing trend of soil MBC with time; and the decrease was significant throughout the period of incubation. The study concluded that application of FA up to 2.5 % can thus be safely used without affecting the soil biological activity and thereby improve nutrient cycling in agricultural soils. PMID:24362819

Nayak, A K; Kumar, Anjani; Raja, R; Rao, K S; Mohanty, Sangita; Shahid, Mohammad; Tripathy, Rahul; Panda, B B; Bhattacharyya, P

2014-02-01

150

Interactions of NaCl and Na 2SO 4 on soil organic C mineralization after addition of maize straws  

Microsoft Academic Search

NaCl and Na2SO4 often dominate salt compositions in saline soils. While either salt alone affects soil organic matter mineralization, their interactions on soil organic matter dynamics are unknown. This study aimed to investigate interactive effects of the two salts on organic C mineralization and microbial biomass C of the saline soils after addition of maize straws. Both NaCl and Na2SO4

Xiao-gang Li; Feng-min Li; Qi-fu Ma; Zhi-jun Cui

2006-01-01

151

Soil Genesis and Development, Lesson 1 - Rocks and Minerals  

Technology Transfer Automated Retrieval System (TEKTRAN)

All soil ultimately forms from rocks or their weathering products. Geologists classify rocks according to their origins. General rock types can weather to give soils with distinctive properties. The objectives of this lesson are: 1. To be able to classify rocks based on visual characteristics accord...

152

Dynamic role of “illite-like” clay minerals in temperate soils: facts and hypotheses  

Microsoft Academic Search

Analysis of new data and reinterpretation of published information for clay minerals found in temperate climate soil profiles\\u000a indicates that there is often a gradient of “illite-like” clay minerals with depth. We used the term “illite-like” because\\u000a these observations are based on X-Ray Diffractogram patterns and not on layer charge measurements which allow to define properly\\u000a illite. It appears that

P. Barré; B. Velde; L. Abbadie

2007-01-01

153

Changes in the Mineral Assemblage of Paddy Soils upon Redox Cycles  

NASA Astrophysics Data System (ADS)

Rice is one of the major cereal crops of global agriculture. World wide more than 10% of the arable land is used for rice production, mainly under temporarily waterlogged conditions. This leads to distinct redox cycles, governing the biogeochemistry of paddy soils. Yet, long-term effects of alternating redox conditions on the soil mineral matrix and properties are still not fully understood. The objective of the project is to elucidate the processes of mineral transformation as related to changing redox conditions and to time of rice cultivation. Long-term effects of rice cultivation on the mineral assemblage were studied along a chronosequence of paddy soils (100, 700 and 2000a paddy soils) developed in comparable parent material in the province of Zhejiang, China. Top soils were analysed for the mineral assemblage and physicochemical properties using x-ray diffraction and chemical analyses, respectively. All studied clay fractions showed a similar clay mineral assemblage (illite, chlorite, kaolinite, vermiculite, smectite). Differences among the paddy sites though could not be related to the time of cultivation. The CECpot of the clay fraction slightly increased from 100 to 2000 a paddy usage, which was partly attributed to a concurrent increase of Corg. With age the Feo/Fed-ratio in both the Alp and Ardp-horizon increased, with a maximum in the Ardp of the 2000 a paddy field. We conclude, that due to an increasing number of redox-cycles, long-term cultivation enhances the formation of microcrystalline Fe-hydroxides in the A-horizons of paddy soils. Chronological changes in the clay mineral assemblage could not be observed in this study.

Vogelsang, Vanessa; Fiedler, Sabine; Jahn, Reinhold

2010-05-01

154

In situ observations of soil minerals and organic matter in the early phases of prescribed fires  

NASA Astrophysics Data System (ADS)

We examined the chemical composition of aerosol samples collected during a prescribed fire at a Great Basin Desert site in the context of samples collected from controlled combustion of vegetation clippings from the same site and resuspension of soil samples obtained prior to and after the burn event. We observed a distinct difference in the composition of organic carbon resuspended soil dust after the burn, reflecting changes caused by the heating of the soil. The relative abundances of minerals and organic carbon fractions in aerosols collected during the first period of the burn were identical to those measured in soil dust. For aerosol samples collected for the remaining two periods of the burn event, the profiles of both minerals and organic carbon matched quite well those observed for vegetation combustion. Reconstruction of aerosol samples collected during the burn event showed that vegetation combustion dominated emissions but mineral soil dust may account for about 10% of PM10emissions (reconstructed) during the early stages of the fire. A large fraction of emissions during the first two hours was also unaccounted mainly because of the insufficient conversion of organic carbon to organic mass. The abundance of heavier non-volatile organics in soil dust suggested the presence of humic/fulvic acids that exhibit higher OM-to-OC ratios and thus, account for a proportion of the unaccounted emissions. These findings indicated that soil dust may be released into the air during a fire event, probably due to the enhanced turbulent mixing near the burn front.

Kavouras, Ilias G.; Nikolich, George; Etyemezian, Vic; Dubois, David W.; King, James; Shafer, David

2012-06-01

155

Mineral weathering in ectomycorrhizosphere of subalpine fir ( Abies lasiocarpa (Hook.) Nutt.) as revealed by soil solution composition  

Microsoft Academic Search

The soil solution is considered an important index of nutrient availability, because it mimics the field conditions when plant roots obtained their nutrition, and reflects the weatherability of a particular soil mineral. The composition of soil solution is sensitive to physical, biological and chemical changes to soil systems, including the presence of fungal hyphae and rhizomorphs from ectomycorrhizal colonization. The

J. M Arocena; K. R Glowa

2000-01-01

156

Microbial Composition in Decomposing Pine Litter Shifts in Response to Common Soil Secondary Minerals  

NASA Astrophysics Data System (ADS)

A range of environmental and biotic factors have been identified that drive microbial community structure in soils - carbon substrates, redox conditions, mineral nutrients, salinity, pH, and species interactions. However, soil mineralogy has been largely ignored as a candidate in spite of recent studies that indicate that minerals have a substantial impact on soil organic matter stores and subsequent fluxes from soils. Given that secondary minerals and organic colloids govern a soil's biogeochemical activity due to surface area and electromagnetic charge, we propose that secondary minerals are a strong determinant of the communities that are responsible for process rates. To test this, we created three microcosms to study communities during decomposition using pine forest litter mixed with two common secondary minerals in soils (goethite and gibbsite) and with quartz as a control. Changes in bacterial and fungal communities were tracked over the 154-day incubation by pyrosequencing fragments of the bacterial 16S and fungal 18S rRNA genes. Ordination using nonmetric multidimensional scaling showed that bacterial communities separated on the basis of minerals. Overall, a single generalist - identified as an Acidobacteriaceae isolate - dominated all treatments over the course of the experiment, representing roughly 25% of all communities. Fungal communities discriminated between the quartz control alone and mineral treatments as a whole. Again, several generalists dominated the community. Coniochaeta ligniaria dominated communities with abundances ranging from 29 to 40%. The general stability of generalist populations may explain the similarities between treatment respiration rates. Variation between molecular fingerprints, then, were largely a function of unique minor members with abundances ranging from 0.01 to 8%. Carbon availability did not surface as a possible mechanism responsible for shifts in fingerprints due to the relatively large mass of needles in the incubation. Other possible mechanisms include the presence of soluble Fe as an alternative energy source in the goethite treatment, the presence of toxic soluble Al in the gibbsite treatment, the loss of available phosphorus in the secondary mineral treatments due to sorption by secondary mineral surfaces, and variations in mineral surfaces as microhabitats. These findings suggest that Al and Fe oxides, such as goethite or gibbsite, are a factor in determining microbial community structure.

Welty-Bernard, A. T.; Heckman, K.; Vazquez, A.; Rasmussen, C.; Chorover, J.; Schwartz, E.

2011-12-01

157

Importance of soil and vineyard management in the determination of grapevine mineral composition.  

PubMed

The spatial variability of the mineral composition of grapevines in production vineyards along the east Adriatic coast was determined and compared between conventional and sustainable vineyard management. Cluster analysis shows a high level of spatial variability even within the individual locations. Factor analysis reveals three factors with strong loading for the macronutrients K and P and the micronutrient Mn, which explain 67% of the total variance in the mineral composition. Here, 26% to 34% of the variance of these three elements can be explained by abiotic and biotic soil parameters, with soil concentrations of K, Fe and Cu, organic matter content, and vesicular colonisation showing the strongest effects on the mineral composition of the grapevines. In addition, analysis of the mineral composition data shows significant differences between differently managed vineyards, with increased bioaccumulation of P and K in sustainable vineyards, while Zn bioaccumulation was increased in conventional vineyards. Our data confirm the importance of soil and vineyard management in the concept of terroir, and demonstrate the effects of sustainable management practices on the mineral nutrition of grapevines that result from modified nutrient availability related to changes in the abiotic and biotic characteristics of the soil. PMID:25461075

Likar, M; Vogel-Mikuš, K; Potisek, M; Han?evi?, K; Radi?, T; Ne?emer, M; Regvar, M

2015-02-01

158

Association of Growth Substrates and Bacterial Genera with Benzo[a]pyrene Mineralization in Contaminated Soil.  

PubMed

Benzo[a]pyrene (BaP) is a carcinogenic polycyclic aromatic hydrocarbon (PAH) that is not known to be a bacterial growth substrate. Organisms capable of cometabolizing BaP in complex field-contaminated systems have not previously been identified. We evaluated BaP mineralization by a bacterial community from a bioreactor treating PAH-contaminated soil during coincubation with or after pre-enrichment on various PAHs as growth substrates. Pyrosequence libraries of 16S rRNA genes were used to identify bacteria that were enriched on the added growth substrate as a means of associating specific organisms with BaP mineralization. Coincubating the bioreactor-treated soil with naphthalene, phenanthrene, or pyrene inhibited BaP mineralization, whereas pre-enriching the soil on the same three PAHs enhanced BaP mineralization. Combined, these results suggest that bacteria in the bioreactor community that are capable of growing on naphthalene, phenanthrene, and/or pyrene can metabolize BaP, with coincubation competitively inhibiting BaP metabolism. Anthracene, fluoranthene, and benz[a]anthracene had little effect on BaP mineralization compared to incubations without an added growth substrate under either coincubation or pre-enrichment conditions. Substantial increases in relative abundance after pre-enrichment with phenanthrene, naphthalene, or pyrene, but not the other PAHs, suggest that members of the genera Cupriavidus and Luteimonas may have been associated with BaP mineralization. PMID:25469077

Jones, Maiysha D; Rodgers-Vieira, Elyse A; Hu, Jing; Aitken, Michael D

2014-12-01

159

Limitations to carbon mineralization in litter and mineral soil of young and old ponderosa pine forests  

Microsoft Academic Search

Summer drought is a feature of the semi-arid region of central Oregon, USA, where vegetation naturally develops into ponderosa pine (Pinus ponderosa var. Laws) forest. Forest management consists of clearcut harvest and natural regeneration. Soil microbial activity is interconnected with forest processes because substrate quality and availability can be important driving variables. Stand development influences the soil water regime, and

F. m. Kelliher; D. j. Ross; B. e. Law; D. d. Baldocchi; N. j. Rodda

2004-01-01

160

Sorption and mineral-promoted transformation of synthetic hormone growth promoters in soil systems.  

PubMed

This work examines the fate of synthetic growth promoters (trenbolone acetate, melengestrol acetate, and zeranol) in sterilized soil systems, focusing on their sorption to organic matter and propensity for mineral-promoted reactions. In organic-rich soil matrices (e.g., Pahokee Peat), the extent and reversibility of sorption did not generally correlate with compound hydrophobicity (e.g., Kow values), suggesting that specific binding interactions (e.g., potentially hydrogen bonding through C17 hydroxyl groups for the trenbolone and melengestrol families) can also contribute to uptake. In soils with lower organic carbon contents (1-5.9% OC), evidence supports sorption occurring in parallel with surface reaction on inorganic mineral phases. Subsequent experiments with pure mineral phases representative of those naturally abundant in soil (e.g., iron, silica, and manganese oxides) suggest that growth promoters are prone to mineral-promoted oxidation, hydrolysis, and/or nucleophilic (e.g., H2O or OH(-)) addition reactions. Although reaction products remain unidentified, this study shows that synthetic growth promoters can undergo abiotic transformation in soil systems, a previously unidentified fate pathway with implications for their persistence and ecosystem effects in the subsurface. PMID:25426694

Qu, Shen; Kolodziej, Edward P; Cwiertny, David M

2014-12-24

161

Impact of clay mineral on air oxidation of PAH-contaminated soils.  

PubMed

This work investigated the impact of a clay mineral (bentonite) on the air oxidation of the solvent extractable organic matters (EOMs) and the PAHs from contaminated soils. EOMs were isolated from two coking plant soils and mixed with silica sand or bentonite. These samples, as well as raw soils and bentonite/soil mixtures, were oxidized in air at 60 and 100 °C for 160 days. Mineralization was followed by measuring the CO2 produced over the experiments. EOM, polycyclic aromatic compound (PAC), including PAH, contents were also determined. Oxidation led to a decrease in EOM contents and PAH concentrations, these diminutions were enhanced by the presence of bentonite. Transfer of carbon from EOM to insoluble organic matter pointed out a condensation phenomenon leading to a stabilization of the contamination. Higher mineralization rates, observed during the oxidation of the soil/bentonite mixtures, seem to indicate that this clay mineral had a positive influence on the transformation of PAC into CO2. PMID:24816462

Biache, Coralie; Kouadio, Olivier; Lorgeoux, Catherine; Faure, Pierre

2014-09-01

162

Organic matter mineralization in frozen boreal soils-environmental constraints on catabolic and anabolic microbial activity  

NASA Astrophysics Data System (ADS)

Heterotrophic microbial mineralization of soil organic matter (SOM) and associated production and emission of atmospheric trace gases proceed during the winter months in the frozen soils of high latitude ecosystems. However, in what ways this microbial activity is constrained by the environmental conditions prevailing in a frozen soil matrix is uncertain. This presentation will address how temperature, water availability and substrate availability combine to regulate rates of microbial activity at below freezing temperatures and the implications of this activity for SOM mineralization in the surface layers of boreal forest soils experiencing seasonal freezing. We show that the amount and availability of liquid water is an integral factor regulating rates of microbial activity in the frozen soil matrix and can also explain frequently observed deviations in the temperature responses of biogenic CO2 production in frozen soils, as compared to unfrozen soils. Using stable isotope labeling (13C) we also show that the partitioning of substrate carbon, in the form of monomeric sugar (glucose), for catabolic and anabolic metabolism remain constant in the temperature range of -4C to 9C. This confirms that microbial growth may proceed even when soils are frozen. In addition we present corresponding data for organisms metabolizing polymeric substrates (cellulose) requiring exoenzymatic activity prior to substrate uptake. We conclude that the metabolic response of soil microorganism to controlling factors may change substantially across the freezing point of soil water, and also the patterns of interaction among controlling factors are affected. Thus, it is evident that metabolic response functions derived from investigations of unfrozen soils cannot be superimposed on frozen soils. Nonetheless, the soil microbial population appear very adapted to seasonal freezing with respect to their metabolic performance.

Oquist, Mats G.; Sparrman, Tobias; Schleucher, Jürgen; Nilsson, Mats B.

2014-05-01

163

Organic Matter Development and Turnover depending on Mineral Composition in an Artificial Soil Incubation Experiment  

NASA Astrophysics Data System (ADS)

Recent research indicates that minerals play an important role in the formation and stabilization of soil organic matter (SOM). However, it is difficult to determine the effect of mineral composition on SOM development in natural soils where mineral composition is usually not well defined and initial conditions are generally unknown. Therefore, we performed an incubation experiment with so-called "artificial soils" composed of mixtures of clean and well-defined model materials where the development of organic matter could be followed from known initial conditions. The artificial soils were composed of 8 different mixtures of quartz, illite, montmorillonite, ferrihydrite, boehmite and charcoal, manure as carbon substrate and a microbial inoculum extracted from a natural arable soil. These mixtures were incubated in the dark and sampled 4 times over a total incubation time of 18 months. The organic matter (OM) turnover during incubation was followed by measuring CO2 respiration and C and N contents and distribution over particle size fractions with time. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and acid hydrolysis were used to determine the development of OM composition. The artificial soil mixtures developed quickly into complex, aggregated, soil-like materials. CO2 respiration was the same for all artificial soil compositions, indicating that microbial degradation was probably limited by nutrient or substrate availability. With increasing incubation time, nitrogen-rich, proteinaceous material, became enriched in the smallest particle size fraction, indicating the accumulation of microbial debris. There was some difference in the distribution of hydrolysable and non-hydrolysable N and organic carbon after 3 months of incubation depending on the type of clay mineral and charcoal presence. However, the artificial soils developed towards more similar systems with increasing incubation time. The artificial soil incubation experiment provided a useful system where the decay and turnover of the original manure substrate under the influence of microbial degradation could be studied. Because of the well-defined composition of the artificial soils this experiment gives us new insight into the dynamics of interactions between specific minerals, OM and charcoal during the decay and turnover of organic matter in a soil-like system.

Pronk, G. J.; Heister, K.; Kogel-Knabner, I.

2012-12-01

164

Microbial carbon mineralization in tropical lowland and montane forest soils of Peru  

PubMed Central

Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., “positive priming effects” that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils. PMID:25566230

Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P.; Nottingham, Andrew T.; Stott, Andrew W.; Bardgett, Richard D.; Salinas, Norma; Ccahuana, Adan J. Q.; Meir, Patrick

2014-01-01

165

Microbial carbon mineralization in tropical lowland and montane forest soils of Peru.  

PubMed

Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., "positive priming effects" that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding (13)C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils. PMID:25566230

Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P; Nottingham, Andrew T; Stott, Andrew W; Bardgett, Richard D; Salinas, Norma; Ccahuana, Adan J Q; Meir, Patrick

2014-01-01

166

Technogenic soils developed on mine spoils containing iron sulphides: Mineral transformations as an indicator of pedogenesis  

Microsoft Academic Search

Technogenic soils (Technosols) containing iron sulphides, developed on mine spoils located in three abandoned industrial sites in Poland (the “Siersza” hard coal mine in Trzebinia, “Staszic” pyrite mine in Rudki, and pyrite mines in Wie?ciszowice), were investigated in order to identify the most important mineral transformations occurring in the soils. The X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometry (SEM-EDS)

?ukasz Uzarowicz; Stefan Skiba

2011-01-01

167

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils and sediments in Loot Desert, central Iran  

E-print Network

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils Desert Stable isotope geochemistry is a unique technique to study the source of salts in soils and sediments. In the present research, sources of gypsum and other sulfur bearing minerals using stable isotope

Ahmad, Sajjad

168

Reversibility of soil forming clay mineral reactions induced by plant - clay interactions  

NASA Astrophysics Data System (ADS)

Recent data based upon observations of field experiments and laboratory experiments suggest that changes in phyllosilicate mineralogy, as seen by X-ray diffraction analysis, which is induced by plant action can be reversed in relatively short periods of time. Changes from diagenetic or metamorphic mineral structures (illite and chlorite) to those found in soils (mixed layered minerals in the smectite, hydroxy-interlayer mineral and illites) observed in Delaware Bay salt marsh sediments in periods of tens of years and observed under different biologic (mycorhize) actions in coniferous forests in the soil environment can be found to be reversed under other natural conditions. Reversal of this process (chloritisation of smectitic minerals in soils) has been observed in natural situations over a period of just 14 years under sequoia gigantia. Formation of smectite minerals from illite (potassic mica-like minerals) has been observed to occur under intensive agriculture conditions over periods of 80 years or so under intensive zea mais production. Laboratory experiments using rye grass show that this same process can be accomplished to a somewhat lesser extent after one growing season. However experiments using alfalfa for 30 year growing periods show that much of the illite content of a soil can be reconstituted or even increased. Observations on experiments using zea mais under various fertilizer and mycorhize treatments indicate that within a single growing season potassium can be extracted from the clay (illite layers) but at the end of the season the potassium can be restored to the clay structures and more replaced that extracted. Hence it is clear that the change in clay mineralogy normally considered to be irreversible, illite to smectite or chlorite to smectite observed in soils, is a reversible process where plant systems control the soil chemistry and the soil mineralogy. The changes in clay mineralogy concern mostly the chemical composition of the interlayer ion population of a 2:1 clay structure. However the differences in interlayer ion chemistry give us such mineral names as chloritic hydroxyinterlayered mineral (Mg, OH interlayer), illite (K interlayer), and smectite (essentially hydrated Ca interlayer ions). Extraction of these interlayer ions can be reversed by chemistry engendered by plant regimes.

Barré, P.; Velde, B.

2012-04-01

169

The influence of biological soil crusts on mineral uptake by associated vascular plants  

USGS Publications Warehouse

Soil surfaces dominated by cyanobacteria and cyanolichens (such as Collema sp.) are widespread in deserts of the world. The influence of these biological soil crusts on the uptake of bioessential elements is reported for the first time for six seed plants of the deserts of Utah. This sample almost doubles the number of species for which the influence of biological soil crusts on mineral uptake of associated vascular plants is known. These new case studies, and others previously published, demonstrate that cyanobacterial or cyanobacteria- Collema crusts significantly alter uptake by plants of many bioessential elements. In studies now available, these crusts always increase the N content of associated seed plants. Uptake of Cu, K, Mg, and Zn is usually (>70% of reported cases) increased in the presence of the biological soil crusts. Soil crusts are generally negatively associated with Fe and P levels in associated seed plant tissue, while plant tissue levels of Ca, Mn, and Na are positively as often as negatively associated with the presence of soil crusts. Increases in bioessential elements in vascular plant tissue from biologically-crusted areas are greatest for short-lived herbs that are rooted primarily within the surface soil, the horizon most influenced by crustal organisms. The mineral content of a deeply rooted shrub (Coleogyne ramosissima) was less influenced by co-occurrence of biological soil crusts.

Harper, K.T.; Belnap, Jayne

2001-01-01

170

Origin and Reactivity of the Martian Soil: A 2003 Micromission  

NASA Technical Reports Server (NTRS)

The role of water in the development of the martian surface remains a fundamental scientific question. Did Mars have one or more "warm and wet" climatic episodes where liquid water was stable at the surface? If so, the mineral phases present in the soils should be consistent with a history of aqueous weathering. More generally, the formation of hydrated mineral phases on Mars is a strong indicator of past habitable surface environments. The primary purpose of this investigation is to help resolve the question of whether such aqueous indicators are present on Mars by probing the upper meter for diagnostic mineral species. According to Burns [1993], the formation of the ferric oxides responsible for the visible color of Mars are the result of dissolution of Fe (+2) phases from basalts followed by aqueous oxidation and precipitation of Fe" mineral assemblages. These precipitates likely included iron oxyhydroxides such as goethite (a-FeOOH) and lepidocrocite (g-FeOOH), but convincing evidence for these phases at the surface is still absent. The stability of these minerals is enhanced beneath the surface, and thus we propose a subsurface search for hydroxylated iron species as a test for a large-scale chemical weathering process based on interactions with liquid water. It is also possible that the ferric minerals on Mars are not aqueous alteration products of the rocks. A chemical study of the Pathfinder landing site concluded that the soils are not directly derived from the surrounding rocks and are enhanced in Mg and Fe. The additional source of these elements might be from other regions of Mars and transported by winds, or alternatively, from exogenic sources. Gibson [1970] proposed that the spectral reflectivity of Mars is consistent with oxidized meteoritic material. Yen and Murray [1998] further extend Gibson's idea and show, in the laboratory, that metallic iron can be readily oxidized to maghemite and hematite under present-day martian surface conditions (in the absence of liquid water). A test for a meteoritic component of the soil can be conducted, as described below, by searching for the presence of Ni at the martian surface. The average abundance of nickel in an Fe-Ni meteorite is about 7% and, if present at measurable levels in the soil, would be indicative of an exogenic contribution. In addition, it may be possible to directly search for mineral phases common in meteorites. An understanding of the formation and evolution of the martian soil would not be complete without addressing the unusual reactivity discovered by the Viking Landers The presence of an inorganic oxidant, possibly one produced as a results of photochemical processes, is the most widely accepted explanation of the Viking results. Are these chemical species simply adsorbed on soil grains, or have they reacted with the metal oxide substrates and altered the mineral structures? Could a completely different (non-photochemical) process be responsible for the soil reactivity? The various ideas for the nature of this putative oxidant could be constrained by a measurement of the change in reactivity with depth. Different compositions will have different lifetimes and mobilities and thus will have different vertical profiles. Because the oxidizing compounds are believed to actively destroy organic molecules, determination of the reactivity gradient also has significant implications for the search for life on Mars. A DS2-based microprobe system can be instrumented for a 2003 micromission to investigate the origin and reactivity of the martian soil. These measurements would provide invaluable information regarding the climate history and exobiological potential of the planet. The NMR, X ray and chemiresistor measurement approach described embodies a highly synergistic and general set of soil interrogation methods for elements, compounds, and crystal structures and can also be applied to other geologic questions of interest. For example, if the capability for precise targeting of the probes is available, then in-situ investigations of suspec

Yen, Albert S.; Kim, S. Sam; Marshall, John; Murray, Bruce C.

1999-01-01

171

Clay mineral formation and transformation in rocks and soils  

USGS Publications Warehouse

Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.

Eberl, D.D.

1983-01-01

172

Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills, Antarctica  

Microsoft Academic Search

The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane\\/pristane and octadecane\\/phytane ratios; in concentrations

Elizabeth Kerry

1993-01-01

173

Influence of sewage sludge compost stability and maturity on carbon and nitrogen mineralization in soil  

Microsoft Academic Search

Incubation experiments with soil were made to study C and N mineralization in a sewage sludge–cotton waste mixture at different stages of the composting process performed by the Rutgers static pile system. Three composting samples were selected: initial mixture (I); the end of the active phase (E); and the mature compost (M). The CO2-C evolved (as % of added C)

M. P. Bernal; A. F. Navarro; M. A. Sánchez-Monedero; A. Roig; J. Cegarra

1998-01-01

174

Soil Property and Landscape Position Effects on Seasonal Nitrogen Mineralization of Composted Dairy Manure  

Technology Transfer Automated Retrieval System (TEKTRAN)

To develop better management practices that optimize the amount of N derived from manure, more information is needed regarding the mineralization and dynamics of N under normal field conditions. Thus, an in situ field study, using three different soil types located in close proximity, was conducted ...

175

Weathering Reactions in Soils on Peoria Loess Document Mineral Weathering Kinetics as a Function of Climate  

NASA Astrophysics Data System (ADS)

Through physical and chemical weathering, primary minerals are transformed to soil minerals in the Critical Zone. Using a published dataset, we investigated reaction fronts occurring in modern soils developed on Peoria Loess in the Mississippi River Valley over the last 10,000 to 13,000 years. After normalization to Zr, elemental concentrations document several different characteristic reaction fronts. Na, Ca, and Mg are depleted at the surface while Al, Fe, and Si show depletion at the surface and enrichment at depth. In contrast, the macronutrients P and K show reaction fronts that reveal the effect of biogenic uptake. Finally, the elemental profile for Mn is classified as an addition-only profile which reflects a relative increase in concentration from parent to surface. This Mn profile is attributed to contaminated dust input. Using the GENESIS v2 Global Climate Model, we performed climate simulations for three periods (modern, 6kyr BP and 10kyr BP) roughly spanning the time of soil development, and extracted model temperature, precipitation, and soil pore water flux for a north-south transect representing the Mississippi Valley. The extents of mineral reaction and reaction kinetic constants vary as functions of these climate variables along the transect. Reaction rate constants will be summarized as a function of these variables for minerals in the profiles.

Williams, J. Z.; Pollard, D.; Brantley, S. L.

2006-12-01

176

The Accumulation of Organic Carbon in Mineral Soils by Afforestation of Abandoned Farmland  

PubMed Central

The afforestation of abandoned farmland significantly influences soil organic carbon (OC). However, the dynamics between OC inputs after afforestation and the original OC are not well understood. To learn more about soil OC dynamics after afforestation of farmland, we measured the soil OC content in paired forest and farmland plots in Shaanxi Province, China. The forest plots had been established on farmland 18, 24, 48, 100, and 200 yr previously. The natural 13C abundance of soil organic matter was also analyzed to distinguish between crop- and forest-derived C in the afforested soils. We observed a nonlinear accumulation of total OC in the 0–80 cm depth of the mineral soil across time. Total soil OC accumulated more rapidly under forest stands aged 18 to 48 yr than under forest stands aged 100 or 200 yrs. The rate of OC accumulation was also greater in the 0–10 cm depth than in the 10–80 cm depth. Forest-derived OC in afforested soils also accumulated nonlinearly across time, with the greatest increase in the 0–20 cm depth. Forest-derived OC in afforest soils accounted for 52–86% of the total OC in the 0–10 cm depth, 36–61% of the total OC in the 10–20 cm depth, and 11–50% of the total OC in the 20–80 cm depth. Crop-derived OC concentrations in the 0–20 cm depth decreased slightly after afforestation, but there was no change in crop-derived OC concentrations in the 20–80 cm depth. The results of our study support the claim that afforestation of farmland can sequester atmospheric CO2 by increasing soil OC stocks. Changes in the OC stocks of mineral soils after afforestation appear to be influenced mainly by the input of forest-derived C rather than by the loss of original OC. PMID:22412854

Wei, Xiaorong; Qiu, Liping; Shao, Mingan; Zhang, Xingchang; Gale, William J.

2012-01-01

177

Degradation and Mineralization of Atrazine by a Soil Bacterial Isolate  

Microsoft Academic Search

An atrazine-degrading bacterial culture was isolated from an agricultural soil previously impacted by herbicide spills. The organism was capable of using atrazine under aerobic conditions as the sole source of C and N. Cyanuric acid could replace atrazine as the sole source of N, indicating that the organism was capable of ring cleavage. Ring cleavage was confirmed in 14CO2 evolution

MARK RADOSEVICH; SAMUEL J. TRAINA; YUE-LI HAO; ANDOLLI H. TUOVINEN

1995-01-01

178

Prions Adhere to Soil Minerals and Remain Infectious  

Microsoft Academic Search

An unidentified environmental reservoir of infectivity contributes to the natural transmission of prion diseases (transmissible spongiform encephalopathies [TSEs]) in sheep, deer, and elk. Prion infectivity may enter soil environments via shedding from diseased animals and decomposition of infected carcasses. Burial of TSE-infected cattle, sheep, and deer as a means of disposal has resulted in unintentional introduction of prions into subsurface

Christopher J Johnson; Kristen E Phillips; Peter T Schramm; Debbie McKenzie; Judd M Aiken; Joel A Pedersen

2006-01-01

179

PYROGENIC CARBON-CLAY MINERAL ASSOCIATIONS IN SOIL SMECTITES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bioorganic carbon is “sequestered” in soil as humic substances (HS). HS is believed to form strong complexes with clays by a number of bonding mechanisms, including ligand exchange, cation-bridging with metals, and H-bonding to siloxane sheets. However, the recent discovery of pyrogenic or black ca...

180

Sorption of a nonionic surfactant Tween 80 by minerals and soils.  

PubMed

Batch experiments were conducted to evaluate Tween 80 sorption by oxides, aluminosilicates, and soils. For oxides, the sorption by silica and alumina follow linear isotherms, and that by hematite follows a Langmuir isotherm. Considering isotherm type and surface coverage, Tween 80 may partition into the silica/alumina-water interface, whereas it may bind to hematite surface sites. Among aluminosilicates, montmorillonite shows the greatest sorption due to the absorption of Tween 80 into interlayers. For other aluminosilicates, it sorbs to surfaces, with the sorption increasing as plagioclasesoils reveal that fine-grained clay minerals, difficult to separate by dry-sieving, contribute significantly to Tween 80 sorption. The greater sorption by untreated soils than H2O2-treated soils indicates that soil organic matter is a vital sorbent. The sorption hysteresis, contributed to by clay minerals and soil organic matter, is characterized by the greater sorption during the desorption than the sorption stages. This suggests the potential difficulty in removing surfactants from soils. Also, sorption of surfactants can adversely affect surfactant-enhanced remediation by decreasing the aquifer permeability and the availability of surfactants for micellar solubilization. PMID:25463228

Kang, Soyoung; Jeong, Hoon Young

2015-03-01

181

Endogeic earthworms shape bacterial functional communities and affect organic matter mineralization in a tropical soil.  

PubMed

Priming effect (PE) is defined as a stimulation of the mineralization of soil organic matter (SOM) following a supply of fresh organic matter. This process can have important consequences on the fate of SOM and on the management of residues in agricultural soils, especially in tropical regions where soil fertility is essentially based on the management of organic matter. Earthworms are ecosystem engineers known to affect the dynamics of SOM. Endogeic earthworms ingest large amounts of soil and assimilate a part of organic matter it contains. During gut transit, microorganisms are transported to new substrates and their activity is stimulated by (i) the production of readily assimilable organic matter (mucus) and (ii) the possible presence of fresh organic residues in the ingested soil. The objective of our study was to see (i) whether earthworms impact the PE intensity when a fresh residue is added to a tropical soil and (ii) whether this impact is linked to a stimulation/inhibition of bacterial taxa, and which taxa are affected. A tropical soil from Madagascar was incubated in the laboratory, with a (13)C wheat straw residue, in the presence or absence of a peregrine endogeic tropical earthworm, Pontoscolex corethrurus. Emissions of (12)CO(2) and (13)CO(2) were followed during 16 days. The coupling between DNA-SIP (stable isotope probing) and pyrosequencing showed that stimulation of both the mineralization of wheat residues and the PE can be linked to the stimulation of several groups especially belonging to the Bacteroidetes phylum. PMID:21753801

Bernard, Laetitia; Chapuis-Lardy, Lydie; Razafimbelo, Tantely; Razafindrakoto, Malalatiana; Pablo, Anne-Laure; Legname, Elvire; Poulain, Julie; Brüls, Thomas; O'Donohue, Michael; Brauman, Alain; Chotte, Jean-Luc; Blanchart, Eric

2012-01-01

182

A general evaluation of the frequency distribution of clay and associated minerals in the alluvial soils of ceylon  

USGS Publications Warehouse

Clay mineral analyses were made of several alluvial clay materials from Ceylon. These studies show that the soil materials can be divided into 3 clay mineral provinces on the basis of the frequency distribution of clay and associated minerals. The provinces closely follow the climatic divisions. The characteristic feature of this classification is the progressive development of gibbsite from Dry to Wet Zone areas. Gibbsite has been used as a reliable indicator mineral. ?? 1971.

Herath, J.W.; Grimshaw, R.W.

1971-01-01

183

Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L. SPARKS2  

E-print Network

Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L,vermiculite. Ogwada, R.A., and D.L. Sparks. 1986. Kinetics of ion exchangeon clay minerals and soil: I. Evaluation displacement or flow techniques to investigate kinetics of ion exchange on soils and clay minerals (Sparks

Sparks, Donald L.

184

Factors driving carbon mineralization priming effect in a soil amended with different types of biochar  

NASA Astrophysics Data System (ADS)

The effect of biochar on soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on soil CO2 emissions and in different physicochemical properties. For this purpose, a sandy-loam soil was amended with the three biochars (BI, BII and BIII) at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving's from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2) greater than 0.97. Results shown a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related with different biochar properties such as ash content, volatile matter, fixed carbon, organic carbon oxidised with dichromate, soluble carbon and metal and phenolic substances content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

Cely, P.; Tarquis, A. M.; Paz-Ferreiro, J.; Méndez, A.; Gascó, G.

2014-03-01

185

Mineralization of 13C glucose in three fine textured soils from the western boreal forest  

NASA Astrophysics Data System (ADS)

Microbial composition is known, on similar soil types, to vary based on differing organic matter inputs, or stand composition. Dominating western upland boreal forests are fine textured soils with a canopy cover of aspen (Populus tremuloides Michx.), white spruce (Picea glauca (Moench) Voss or a mixture of the two. These soils then reflect different belowground biogeochemical processing of organic matter. Anthropogenic soils, formed from a combination of peat litter and fine textured mineral soil, are now also a part of the landscape in the western boreal. This study set out to determine if a simple labelled compound (13C glucose) was processed differently between soils from the two dominant stand types (aspen and spruce) and a soil from an anthropogenic (constructed) site. Results indicate that while all three soils rapidly incorporated, and respired, the labelled carbon each maintained a distinct microbial community structure (as evidenced by phospholipid fatty acid analysis) throughout the 300 hour experiment. Therefore soils with different microbial communities from varied organic matter inputs decompose organic carbon by different processes, even in the case of simple labile compounds.

Norris, C. E.; Quideau, S. A.; Macey, D. E.

2012-04-01

186

Effects of Biological Soil Crusts on Seedling Growth and Mineral Content of Four Semiarid Herbaceous Plant Species  

Microsoft Academic Search

A growing body of evidence indicates that biological soil crusts of arid and semiarid lands contribute significantly to ecosys- tem stability by means of soil stabilization, nitrogen fixation, and improved growth and establishment of vascular plant species. In this study, we examined growth and mineral content of Bromus tectorum, Elymus elymoides, Gaillardia pulchella, and Sphaeralcea munroana grown in soil amended

R. L. Pendleton; B. K. Pendleton; G. L. Howard; S. D. Warren

187

Analysis of hydrolysable neutral sugars in mineral soils: Improvement of alditol acetylation for gas chromatographic separation and measurement  

Microsoft Academic Search

To understand plant–microbe relationships, a simple method is required for identification of the nature of soil polysaccharides. Acid hydrolysis, reduction of sugar monomers to the corresponding alcohols and subsequent derivatisation with acetic anhydride prior to gas chromatography has often been used for identification and quantification of hydrolysable sugars in plant and soil samples. In mineral soil samples, precipitation of iron

Elisabeth Eder; Sandra Spielvogel; Angelika Kölbl; Gabriele Albert; Ingrid Kögel-Knabner

2010-01-01

188

17-? estradiol and testosterone mineralization and incorporation into organic matter in broiler litter-amended soils.  

PubMed

The presence of the hormones estradiol and testosterone in the environment is of concern because they adversely affect vertebrate sexual characteristics. Land spreading broiler litter introduces these hormones into the environment. We conducted two studies. The first study determined the mineralization of C-labeled estradiol and testosterone at three water potentials and three temperatures in four broiler litter-amended soils. With a few exceptions, the mineralization of each hormone either stayed the same or increased with increasing water content (both hormones) and increasing (estradiol) or decreasing (testosterone) temperature. Mineralization was dependent on soil type. The second study determined the incorporation of C-labeled estradiol and testosterone into (i) three soil organic matter (SOM) fractions (fulvic acid, humic acid, and humin) at two water potentials, two temperatures, and one sampling time, and (ii) at one water potential, one temperature, and seven sampling times. As time increased, higher temperature and water potential decreased percentages of C estradiol and testosterone in water- and acetone-soluble fractions and increased percentages in SOM fractions. However, the distribution of the two hormones in SOM fractions differed. For estradiol, higher temperature and water potential increased the percentage in all three SOM fractions. For testosterone, higher temperature and water potential increased the percentage of hormone in fulvic acid and humin. Although the mineralization studies suggest the potential for these hormones to still have environmental effects, the incorporation of the two hormones into SOM suggest that land spreading these hormones may actually be less of an environmental concern. PMID:23128749

Durant, Michelle B; Hartel, Peter G; Cabrera, Miguel L; Vencill, William K

2012-01-01

189

From bulk soil to intracrystalline investigation of plant-mineral interaction  

NASA Astrophysics Data System (ADS)

Understanding the controls and feedbacks regulating the flux of matter between bio-geochemical reservoirs in forest ecosystems receives a fast growing interest for the last decades. A complex question is to understand how minerals and vegetation interact in soils to sustain life and, to a broader scope, how forest ecosystems may respond to human activity (acid rain, harvesting,...) and climate perturbations (temperature, precipitation,...). Many mineralogical and biogeochemical approaches have longtime been developed, and occasionally coupled, in order to investigate the mechanisms by which chemical elements either are exchanged between soil particles and solutions, or are transferred to plants or to deeper soil layers and finally leave the system. But the characterization of particular processes like the contribution of minor reactive minerals to plant nutrition and global fluxes or the mechanisms by which biology can modify reaction rates and balance the bioavailability of nutrients in response to environmental perturbation sometimes fails because of the lack of suitable tracers. Recent analytical and conceptual advances have opened new perspectives for the use of light "non traditional" stable isotopes. Showing a wild range of concentrations and isotopic compositions between biogeochemical reservoirs in forest ecosystem, boron has physico-chemical properties particularly relevant to the investigation of water/rock interactions even when evolving biologically-mediated reactions. In this study, we focused on the distribution of boron isotopes from intracrystalline to bulk soil scales. An overview of the boron distribution and annual fluxes in the soil-plant system clearly indicates that the vegetation cycling largely controls the mobility of boron. We also observe that the mineral and biological B pools have drastically different isotopic signature that makes the transfer of B between them very easy to follow. In particular, the podzol soil we analyzed shows a clear contribution of vegetation-recycled B to neoformed mineral phases, whereas B in minerals from the brown acidic soil rather indicates predominant mineral dissolution with little or even no B supply from the soil solution. If B isotopes thus proved their sensitivity to the soil forming conditions, a simple isotopic budget also demonstrates that the isotopic signature shown by the vegetation cannot result from fractionation during boron absorption. Analyses of B isotopes within intracrystalline phyllosilicate minerals further identify the interfoliar layers as the major source of B during plant nutrition. Additionally, weathering experiments placing phyllosilicates in contact with various alteration agents (protons, organic acid or siderophore) point to the role of the latters as likely responsible for the boron liberation from the phyllosilicate interfoliar layers. This scenario gives the phyllosilicate interfoliar layers a central function in the plant nutrition in context studied here of soils developed on granitic bedrocks. It also implies a very dynamic system in which plants and minerals can exchange matter over very short periods of time.

Lemarchand, D.; Voinot, A.; Chabaux, F.; Turpault, M.

2011-12-01

190

Potential linkages between mineral magnetic measurements and urban roadside soil pollution (part 2).  

PubMed

Use of mineral magnetic concentration parameters (?LF, ?ARM and SIRM) as a potential pollution proxy for soil samples collected from Wolverhampton (UK) is explored. Comparison of soil-related analytical data by correlation analyses between each magnetic parameter and individual geochemical classes (i.e. Fe, Pb, Ni, Zn, Cd), are reported. ?LF, ?ARM and SIRM parameters reveal significant (p < 0.001 n = 60), strong (r = 0.632-0.797), associations with Fe, Cu, Zn and Pb. Inter-geochemical correlations suggest anthropogenic influences, which is supported by low ?FD% measurements that infer an influence of multi-domain mineralogy are indicative of anthropogenic combustion processes. Results indicate mineral magnetic measurements could potentially be used as a geochemical indicator for soils in certain environments and/or specific settings that are appropriate for monitoring techniques. The mineral magnetic technique offers a simple, reliable, rapid, sensitive, inexpensive and non-destructive approach that could be a valuable pollution proxy for soil contamination studies. PMID:24463607

Crosby, C J; Fullen, M A; Booth, C A

2014-03-01

191

Effects of glyphosate on soil microbial communities and its mineralization in a Mississippi soil  

Microsoft Academic Search

Transgenic glyphosate-resistant (GR) soybean (Glycine max (L.) Merr.) has enabled highly effective and economical weed control. The concomitant increased application of glyphosate could lead to shifts in the soil microbial community. The objective of these experiments was to evaluate the effects of glyphosate on soil microbial community structure, function and activity. Field assessments on soil microbial communities were conducted on

Mark A Weaver; L Jason Krutz; Robert M Zablotowicz; Krishna N Reddy

2007-01-01

192

Influence of soil properties on the toxicity of TiO? nanoparticles on carbon mineralization and bacterial abundance.  

PubMed

Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importance of soil characteristics is often neglected in ecological risk assessment. To evaluate the impact of TiO2 nanoparticles (NPs) on soil microbial communities (measured on bacterial abundance and carbon mineralization activity), 6 agricultural soils exhibiting contrasted textures and organic matter contents were exposed for 90 days to a low environmentally relevant concentration or to an accidental spiking of TiO2-NPs (1 and 500mgkg(-1) dry soil, respectively) in microcosms. In most soils, TiO2-NPs did not impact the activity and abundance of microbial communities, except in the silty-clay soil (high OM) where C-mineralization was significantly lowered, even with the low NPs concentration. Our results suggest that TiO2-NPs toxicity does not depend on soil texture but likely on pH and OM content. We characterized TiO2-NPs aggregation and zeta potential in soil solutions, in order to explain the difference of TiO2-NPs effects on soil C-mineralization. Zeta potential and aggregation of TiO2-NPs in the silty-clay (high OM) soil solution lead to a lower stability of TiO2-NP-aggregates than in the other soils. Further experiments would be necessary to evaluate the relationship between TiO2-NPs stability and toxicity in the soil. PMID:25464292

Simonin, Marie; Guyonnet, Julien P; Martins, Jean M F; Ginot, Morgane; Richaume, Agnès

2015-02-11

193

Linking Annual N2O Emission in Organic Soils to Mineral Nitrogen Input as Estimated by Heterotrophic Respiration and Soil C/N Ratio  

PubMed Central

Organic soils are an important source of N2O, but global estimates of these fluxes remain uncertain because measurements are sparse. We tested the hypothesis that N2O fluxes can be predicted from estimates of mineral nitrogen input, calculated from readily-available measurements of CO2 flux and soil C/N ratio. From studies of organic soils throughout the world, we compiled a data set of annual CO2 and N2O fluxes which were measured concurrently. The input of soil mineral nitrogen in these studies was estimated from applied fertilizer nitrogen and organic nitrogen mineralization. The latter was calculated by dividing the rate of soil heterotrophic respiration by soil C/N ratio. This index of mineral nitrogen input explained up to 69% of the overall variability of N2O fluxes, whereas CO2 flux or soil C/N ratio alone explained only 49% and 36% of the variability, respectively. Including water table level in the model, along with mineral nitrogen input, further improved the model with the explanatory proportion of variability in N2O flux increasing to 75%. Unlike grassland or cropland soils, forest soils were evidently nitrogen-limited, so water table level had no significant effect on N2O flux. Our proposed approach, which uses the product of soil-derived CO2 flux and the inverse of soil C/N ratio as a proxy for nitrogen mineralization, shows promise for estimating regional or global N2O fluxes from organic soils, although some further enhancements may be warranted. PMID:24798347

Mu, Zhijian; Huang, Aiying; Ni, Jiupai; Xie, Deti

2014-01-01

194

Exchangeable and secondary mineral reactive pools of aluminium in coastal lowland acid sulfate soils.  

PubMed

The use of coastal floodplain sulfidic sediments for agricultural activities has resulted in the environmental degradation of many areas worldwide. The generation of acidity and transport of aluminium (Al) and other metals to adjacent aquatic systems are the main causes of adverse effects. Here, a five-step sequential extraction procedure (SEP) was applied to 30 coastal lowland acid sulfate soils (CLASS) from north-eastern New South Wales, Australia. This enabled quantification of the proportion of aluminium present in 'water-soluble', 'exchangeable', 'organically-complexed', 'reducible iron(III) (oxyhydr)oxide/hydroxysulfate-incorporated' and 'amorphous Al mineral' fractions. The first three extractions represented an average of 5% of 'aqua regia' extractable Al and their cumulative concentrations were extremely high, reaching up to 4000 mg·kg(-1). Comparison of Al concentrations in the final two extractions indicated that 'amorphous Al minerals' are quantitatively a much more important sink for the removal of aqueous Al derived from the acidic weathering of these soils than reducible Fe(III) minerals. Correlations were observed between soil pH, dissolved and total organic carbon (DOC and TOC) and Al concentrations in organic carbon-rich CLASS soil horizons. These results suggest that complexation of Al by dissolved organic matter significantly increases soluble Al concentrations at pH values >5.0. As such, present land management practices would benefit with redefinition of an 'optimal' soil from pH ?5.5 to ~4.8 for the preservation of aquatic environments adjacent to organic-rich CLASS where Al is the sole or principle inorganic contaminant of concern. Furthermore, it was observed that currently-accepted standard procedures (i.e. 1 M KCl extraction) to measure exchangeable Al concentrations in these types of soils severely underestimate exchangeable Al and a more accurate representation may be obtained through the use of 0.2 M CuCl2. PMID:24727041

Yvanes-Giuliani, Yliane A M; Waite, T David; Collins, Richard N

2014-07-01

195

Mineral nutrition of campos rupestres plant species on contrasting nutrient-impoverished soil types.  

PubMed

In Brazil, the campos rupestres occur over the Brazilian shield, and are characterized by acidic nutrient-impoverished soils, which are particularly low in phosphorus (P). Despite recognition of the campos rupestres as a global biodiversity hotspot, little is known about the diversity of P-acquisition strategies and other aspects of plant mineral nutrition in this region. To explore nutrient-acquisition strategies and assess aspects of plant P nutrition, we measured leaf P and nitrogen (N) concentrations, characterized root morphology and determined the percentage arbuscular mycorrhizal (AM) colonization of 50 dominant species in six communities, representing a gradient of soil P availability. Leaf manganese (Mn) concentration was measured as a proxy for carboxylate-releasing strategies. Communities on the most P-impoverished soils had the highest proportion of nonmycorrhizal (NM) species, the lowest percentage of mycorrhizal colonization, and the greatest diversity of root specializations. The large spectrum of leaf P concentration and variation in root morphologies show high functional diversity for nutritional strategies. Higher leaf Mn concentrations were observed in NM compared with AM species, indicating that carboxylate-releasing P-mobilizing strategies are likely to be present in NM species. The soils of the campos rupestres are similar to the most P-impoverished soils in the world. The prevalence of NM strategies indicates a strong global functional convergence in plant mineral nutrition strategies among severely P-impoverished ecosystems. PMID:25425486

Oliveira, Rafael S; Galvão, Hugo C; de Campos, Mariana C R; Eller, Cleiton B; Pearse, Stuart J; Lambers, Hans

2015-02-01

196

Pathogenic prion protein is degraded by a manganese oxide mineral found in soils  

USGS Publications Warehouse

Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.

Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, J.M.; Pedersen, J.A.

2009-01-01

197

The extent of carbon mineralization in boreal soils controls compositional changes  

NASA Astrophysics Data System (ADS)

Almost twenty percent of global carbon stocks in vegetation and soil are found in boreal soils, making them the largest terrestrial carbon storehouse in the world. Yet, despite their importance in the global carbon budget, very little is known about the exact nature and decomposition pathways of organic matter in these soils. The overall objective of this study was to examine the effects of vegetation and disturbance (fire and harvest) on: 1) soil organic matter composition, and 2) decomposition-induced changes in composition from a range of representative boreal forest and peatland ecosystems. Forest floor and peat samples (0-10 cm) were obtained from 17 sites along an east-west transect from New Brunswick to British Columbia, Canada. Carbon mineralization rates were measured during a 1-year laboratory incubation at 10 °C. Carbon chemistry in pre- and post-incubation samples was characterized by solid-state ramped-cross-polarization (RAMP-CP) 13C nuclear magnetic resonance (NMR). The percentage of carbon mineralized during incubation ranged from 1 to 24%, and corresponded to significant increases in aromatic, phenolic, and carbonyl carbons. As expected, significant differences in carbon composition pre-incubation were found among vegetation types regardless of disturbance and sampling location. May be more interestingly, comparable differences among samples persisted post-incubation. In addition, decomposition-induced changes in carbon chemistry significantly differed among vegetation types. Samples from Jack pine and Douglas fir stands, which experienced the highest carbon mineralization, also showed the greatest increase in aromatic, phenolic, and carbonyl carbons. Overall, changes in carbon chemistry were significantly correlated to the percentage of carbon mineralized; i.e., the extent of decomposition that the samples underwent.

Mercier Quideau, S.; Oh, S.; Paré, D.

2013-12-01

198

Catalyser21 TM , a mineral water derived from leaf soil, inhibits tumor cell invasion and angiogenesis  

Microsoft Academic Search

Catalyser-21TM is a mineral water derived from natural leaf soil containing various organic and inorganic substances. Previous reports suggested\\u000a a possibility that Catalyser-21TM has antioxidative potential and could inhibit angiogenesis and cancer cell invasiveness. Angiogenesis is a prerequisite for\\u000a cancer cells to spread to surrounding tissues. Vascular endothelial growth factor (VEGF) is a major angiogenic factor in the\\u000a formation of

Jun Ye; Yuping Li; Takeki Hamasaki; Noboru Nakamichi; Takeshi Kawahara; Kazuhiro Osada; Kiichiro Teruya; Yuko Kato; Kazuko Toh; Masumi Abe; Yoshinori Katakura; Katsumi Noguchi; Sanetaka Shirahata

2007-01-01

199

Role of organic fractions on C decomposition and N mineralization of animal wastes in soil  

Microsoft Academic Search

The relative contributions of water-soluble, water-non-soluble, Van Soest-soluble, and neutral detergent fiber (NDF) fractions\\u000a of pig slurry (PS), cattle slurry (CS), cattle farmyard manure (FYM), and composted cattle farmyard manure (CFYM) to the overall\\u000a C and N mineralization of the raw wastes were studied by incubating treated soil for 107 days at 15°C under non-limiting N\\u000a conditions. The C or N

Thierry Morvan; Bernard Nicolardot

2009-01-01

200

Reductive capacity of iron-bearing soil minerals for U(VI)  

NASA Astrophysics Data System (ADS)

Oxidation-reduction processes play a major role in the mobility, transport, and fate of uranium (U) in the geological system. Under reducing conditions, U mobility is much slower than in oxidizing conditions. Previous studies have reported that iron oxides, hydroxides, and oxyhydroxides are associated with U retention in the subsurface environment. Therefore, measuring reductive capacity of iron-bearing soil minerals is important for assessing the U mobility in geological systems where U can be easily disposed. In this study, magnetite (Fe3O4), greenrust (GR-SO4), nZVI, mackinawite (FeS), and pyrite (FeS2) were used to estimate and compare their reductive capacity for U(VI). nZVI showed the fastest U(VI) removal kinetic and highest reduction capacity among the iron-bearing soil minerals tested. We found that the iron-bearing soil mineral with higher content of reactive Fe(II) on its surface is more favorable for U(VI) sorption and reduction. This is because the U(VI) reduction capacity is attributed to surface Fe-O complexes and amount of surface Fe(II) reducing sorbed U(VI). The experimental results show that surface Fe(II) in iron-bearing soil minerals is an important factor that significantly stabilize and immobilize U(VI) in the geological system. This can be used as basic knowledge for the prediction of U fate in the natural environment and for the development of remediation technology to treat uranium-contaminated sites.

Sihn, Y.; Lee, W.

2011-12-01

201

Automated SEM-EDS (QEMSCAN®) Mineral Analysis in Forensic Soil Investigations: Testing Instrumental Reproducibility  

Microsoft Academic Search

The complex mix of organic and inorganic components present in urban and rural soils and sediments potentially enable them\\u000a to provide highly distinctive trace evidence in both criminal and environmental forensic investigations. Organic components\\u000a might include macroscopic or microscopic plants and animals, pollen, spores, marker molecules, etc. Inorganic components comprise\\u000a naturally derived minerals, mineralloids and man-made materials which may also

Duncan Pirrie; Matthew R. Power; Gavyn K. Rollinson; Patricia E. J. Wiltshire; Julia Newberry; Holly E. Campbell

202

Effect of potassium salts and distillery effluent on carbon mineralization in soil.  

PubMed

Distillery effluent, a rich source of potassium, is used for irrigation at many places in the world. A laboratory experiment was conducted to study the influence of potassium salts present in post-methanation distillery effluent (PME) along with two other salts, KCl and K2SO4, on mineralization of carbon in soil. PME oxidized with H2O2, raw PME, KCl and K2SO4 solutions containing K equivalent to 10%, 20%, 40% and 100% of K present in PME were added to the soil separately, maintaining four replications for each treatment and control. Addition of salts up to a certain concentration stimulated C mineralization but a decline was noticed at higher concentrations. All the levels of salts caused higher CO2 evolution than the control suggesting that the presence of K salts enhanced the microbial activity resulting in increased CO2 evolution. The influence of K2SO4 was significantly higher than KCl in stimulating C mineralization in soil. Oxidized effluent had a higher stimulating effect than inorganic salts, showing the influence of other salts accompanying K in the PME. Raw PME, which contained excess organic C, increased CO2 evolution even at the highest salt level (100% PME) signifying the effect of added C on alleviating the salt stress on microbial activity. PMID:12094803

Chandra, Suresh; Joshi, H C; Pathak, H; Jain, M C; Kalra, N

2002-07-01

203

The Role of Elevated PCO2 on Selenate and Selenite Sorption to and Desorption from Calcareous Soils and Carbonate Minerals  

NASA Astrophysics Data System (ADS)

Selenium is a minor component of highly weatherable rock formations in the Uintah Basin Utah from which soils are formed. Activities such as soil/gas extraction and irrigated agriculture may be accelerating the mobilization of Se in the soils, which eventually reach the Pariette Wetlands. Since the wetlands are a stopping point for migratory water fowl, the elevated levels of Se detected in the sediments and waters are of concern. Understanding soil mechanisms related to selenium transport through soils is critical to managing the contamination. In microbially active agricultural soils concentrations of CO2 in the soil air may be 10 to 100 times higher than at the soil surface. CO2 dissolved in the soil solution forms numerous carbonate species that may enhance or compete with selenate and selenite sorption/desorption from soil. Thus we investigated the partitioning of Se between the immobile solid phase and mobile solution phase in six calcareous soils and three carbonate minerals by the batch sorption method at ambient and elevated PCO2. We hypothesized that in these highly buffered soils competition from carbonate species would result in decreased Se sorption. Results indicate that at elevated PCO2 selenate and selenite sorption increased in all soils and minerals tested relative to sorption at ambient levels. Minimal desorption occurred with a dilute electrolyte solution, but could be induced in the presence of phosphate. This finding suggests that actively respiring soils mitigate Se transport to ground or surface waters.

Jacobson, A. R.; Wen, L.

2013-12-01

204

Mineralization of carbon during moist incubation of soil JF79 treated with organic heat-transfer and storage fluids  

Microsoft Academic Search

Biodegradability of four heat transfer\\/storage fluids (ethylene glycol, Therminol 66, Caloria HT43, and Dow Corning Fluid No. 200) were examined. The degradation was monitored by periodically measuring the mineralization of carbon in moist fluid-contaminated soils incubated at 28° and 37°C for 8 weeks. Ethylene glycol mineralized relatively readily. The other three fluids did not show measurable amount of carbon mineralization

H. Nishita; R. M. Haug

1981-01-01

205

The study of the soil clay minerals within the framework of the integrated research headed by N.I. Bazilevich  

NASA Astrophysics Data System (ADS)

The main areas of the integrated biogeochemical studies performed under the supervision of N.I. Bazilevich dealing with the investigation of soil minerals were considered. The development of the clay profiles in soils under the effect of chernozem formation, solodization, salinization, solonetzization, and gleyzation, the spatial differentiation of which favored the development of the pronounced complexity of the soil cover in the forest-steppe zone of the Baraba Lowland, was described. It was shown that irrigation with sodic water induces the evolution of chernozems to solodized soils due to the dispersion and destruction of the clay minerals. The behavior of the minerals in the sodic solonetz-solonchaks of Armenia during their reclamation with sulfuric acid and iron (II) sulfate was explained. The effect of the root exudates from black saxaul ( Haloxylon aphyllum) on the transformation of the layered silicates in the rooting zone of sandy desert soils was noted.

Chizhikova, N. P.

2010-11-01

206

Immediate effects of prescribed burning on mineral soil nitrogen in ponderosa pine of New Mexico  

SciTech Connect

Three 0.1-ha ponderosa pine (Pinus ponderosa Dougl. ex Laws) sites were burned in the fall of 1981. The burn was mainly a ground fire. Burn intensity was 980, 1760, and 2280 kJ s/sup -1/ m/sup -1/ on sites 1, 2, and 3, respectively. We analyzed the mineral soils on each of these sites for total N, NO/sub 2//sup -/ + NO/sub 3//sup -/-N and NH/sub 4//sup +/-N prior to prescribed burning, 1 d postburn, and 30 d postburn. On the most intense burn, NH/sub 4//sup +/-N levels increased threefold from preburn (10 ppm) to 1 d postburn (32 ppm), but declined somewhat 30 d following the burn (24 ppm). Concentrations of NO/sub 2//sup -/ + NO/sub 3//sup -/-N on site 3 rose from 1 ppm preburn and 1 d postburn to 5 ppm 30 d postburn. There were no significant differences in soil total N after burning. Immediate postburn inorganic N values for ponderosa pine mineral soils have not been previously reported in the literature. It is important to investigate burned soils immediately after burning to better understand sequential processes involved in postfire inorganic N dynamics.

Kovacic, D.A.; Swift, D.M.; Ellis, J.E.; Hakonson, T.E.

1986-01-01

207

Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills, Antarctica  

SciTech Connect

The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane/pristane and octadecane/phytane ratios; in concentrations of major hydrocarbon components and in microbial numbers and activity. Significantly lower hydrocarbon concentration were recorded after one year in soils treated with fertilizer solutions, but only in the surface 3 cm. These soils also showed lowered heptadecane/pristane and octadecane/phytane ratios and had the highest levels of microbial activity relative to other plots. Soils treated with gum xanthan or covered with plastic had the highest residual hydrocarbon levels. Both treatments inhibited evaporative loss of hydrocarbon, and there were indications that gum xanthan was utilized by the microbiota as an alternative carbon source to distillate. Higher temperatures were recorded under the plastic but no stimulation of biodegradation was detected. Estimated numbers of metabolically active bacteria were in the range 10[sup 7] to 10[sup 8] g[sup [minus]1] dry weight of soil, with an estimated biomass of 0.03 to 0.26 mg g[sup [minus]1] soil. Estimated numbers of amoebae were in the range 10[sup 6] 10[sup 7] g[sup [minus]1] soil (biomass of 2 to 4 mg g[sup [minus]1]). The highest populations were recorded in fertilized, contaminated soils, the only soils where petroleum degradation was demonstrated. 23 refs., 1 fig., 4 tabs.

Kerry, E. (Univ. of Tasmania (Australia))

1993-01-01

208

Effects of organic matter removal and soil compaction on fifth-year mineral soil carbon and nitrogen contents for sites across the United States and Canada  

Microsoft Academic Search

This study describes the main treatment effects of organic matter removal and compaction and a split-plot effect of competition control on mineral soil carbon (C) and nitrogen (N) pools. Treatment effects on soil C and N pools are discussed for 19 sites across five locations (British Columbia, Northern Rocky Mountains, Pacific Southwest, and Atlantic and Gulf coasts) that are part

Felipe G. Sanchez; Allan E. Tiarks; J. Marty Kranabetter; Deborah S. Page-Dumroese; Robert F. Powers; Paul T. Sanborn; William K. Chapman

2006-01-01

209

Beryllium geochemistry in soils: Evaluation of 10Be/9Be ratios in authigenic minerals as a basis for age models  

USGS Publications Warehouse

Soils contain a diverse and complex set of chemicals and minerals. Being an 'open system', both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric 10Be in soils, its relatively long half-life (1.5 Ma), and the fact that 10Be gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of 10Be with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636-639.]. We find that the 10Be/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10Be concentrations. Also, the highest 10Be/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model 10Be/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the 10Be/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10-15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport of 10Be and clays, and in-situ dissolution of clay minerals at depths, altering the 10Be/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their 10Be inventories and 10Be/9Be ratios have been significantly disturbed possibly by mixing with transported soils. ?? 1997 Elsevier Science B.V.

Barg, E.; Lal, D.; Pavich, M.J.; Caffee, M.W.; Southon, J.R.

1997-01-01

210

Zinc Fertilization Plus Liming to Reduce Cadmium Uptake by Romaine Lettuce on Cd-Mineralized Lockwood Soil  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lockwood shaly loam (Pachic Argixerolls) and similar Cd mineralized soils derived from marine shale in California contain higher Cd levels and higher Cd:Zn ratios than uncontaminated US soils, and produce leafy vegetables with considerably higher Cd than is normal for US lettuce. Previous work by B...

211

Amino acid, peptide and protein mineralization dynamics in a taiga forest soil David L. Jones a,*, Knut Kielland b  

E-print Network

Amino acid, peptide and protein mineralization dynamics in a taiga forest soil David L. Jones a was of high MW of which >75% remained unidentified. Free amino acids constituted less than 5% of the total DON the concentration of free amino acids. Incubations of low MW DON with soil indicated a rapid processing of amino

Wagner, Diane

212

ACCUMULATION AND CROP UPTAKE OF SOIL MINERAL NITROGEN AS INFLUEMCED BY TILLAGE, COVER CROPS, AND NITROGEN FERTILIZATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil and crop management practices may influence soil mineral N, crop N uptake, and N leaching. We evaluated the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)]...

213

Carbon mineralization in the soils under different cover crops and residue management in an intensive protected vegetable cultivation  

Microsoft Academic Search

Continuous cropping under plastic greenhouses, a common practice in intensive Chinese vegetable production systems, has led to the decline of soil productivity and crop yields. A 4-year greenhouse experiment on cucumber double-cropping systems was conducted in Changping country, Beijing, China, to investigate the effects of summer cover crops and residue management on soil microbial biomass carbon (MBC), C mineralization and

Yongqiang Tian; Juan Liu; Xuhui Wang; Lihong Gao

2011-01-01

214

Andic soils : mineralogical effect onto organic matter dynamics, organic matter effect onto mineral dynamics, or both?  

NASA Astrophysics Data System (ADS)

From a strictly mineralogical point of view, weathering of volcanic glass produces secondary phases that are short range ordered alumino-silicates (SRO-AlSi). These are imogolite tubes (2 to 3 nm of diameter) and allophane supposedly spheres (3.5 to 5 nm). Their local structure is composed of a curved gibbsite Al layer and Si tetrahedra in the vacancies (Q0). Proto-imogolites have the same local structure but are roof-shape nanoparticles likely representing the precursors of imogolite and allophanes (Levard et al. 2010). These structures and sizes give to the SRO-AlSi large specific surfaces and high reactivities. In some natural sites, imogolites and allophanes are formed in large quantities. Aging of these phases may lead to the formation of more stable minerals (halloysite, kaolinite and gibbsite) (Torn et al 1997). In natural environments, when the weathering of volcanic glass is associated with the establishment of vegetation, the soils formed are generally andosols. These soils are particularly rich in organic matter (OM), which is explained by the high ability of SRO-AlSi mineral phases to form bonds with organic compounds. In a first order "bulk" approach, it is considered that these bonds strongly stabilize the organic compounds as their mean age can reach more than 10 kyrs in some studied sites (Basile-Doelsch et al. 2005; Torn et al. 1997). However, the structure of the mineral phases present in andosols deserves more attention. Traditionally, the presence in the SRO-AlSi andosols was shown by selective dissolution approaches by oxalate and pyrophosphate. Using spectroscopic methods, mineralogical analysis of SRO-AlSi in andosols samples showed that these mineral phases were neither imogolites nor allophanes as originally supposed, but only less organized structures remained in a state of proto-imogolites (Basile-Doelsch al. 2005 ; Levard et al., 2012). The presence of OM would have an inhibitory effect on the formation of secondary mineral phases, by blocking the crystal growth of SRO-AlSi. Conversely, the effect of minerals on the dynamics of organic compounds also deserves to be studied in greater detail. If the "bulk" approaches showed that proto-imogolites involve long-term stabilized OM, other approaches such as densimetric fractionation and C3/C4 chronosequences (Basile-Doelsch et al. 2007; De Junet et al. 2013) led us to consider a new model involving two types of organo-mineral interactions: (1) OM stabilized by strong bonds to proto-imogolite, leading to a slow OM turnover and (2) OM retained within the porosity of the 3D structure formed by the proto-imogolite (similar to a gel structure), leading to a faster OM turnover. Understanding the mechanisms of organo-mineral interactions in andosols will open new research directions for understanding the mechanisms of stabilization of OM in any type of soil (Bonnard et al. 2012). Basile-Doelsch et al., Geoderma, 137, 477-489, 2007. Basile-Doelsch et al., European Journal of Soil Science, 56, 689-703, 2005. Bonnard et al., European Journal of Soil Science, 63, 5, 625-636, 2012. de Junet, et al., Journal of Analytical and Applied Pyrolysis, 99, 92-10, 2013, Levard et al, Geoderma, 183-184, 100-108, 2012. Levard et al. Chemistry Of Materials, 22, 2466-2473, 2010 Torn et al. Nature, London, 389, 170-173, 1997.

Basile-Doelsch, Isabelle; Amundson, Ronald; Balesdent, Jérome; Borschneck, Daniel; Bottero, Jean-Yves; Colin, Fabrice; de Junet, Alexis; Doelsch, Emmanuel; Legros, Samuel; Levard, Clément; Masion, Armand; Meunier, Jean-Dominique; Rose, Jérôme

2014-05-01

215

Mineral cycling in soil and litter arthropod food chains. Progress report, November 1, 1979-October 31, 1980  

SciTech Connect

Recent progress and current status are reported for research concerned with mineral element dynamics in soil arthropod food chains. Research is performed within the larger context of terrestrial decomposition systems, in which soil arthropods may act as regulators of nutrient dynamics during decomposition. Research is measuring rates of nutrient accumulation and excretion by using radioactive tracer techniques with radioactive analogs of nutrients. Experimental measurement of radioactive tracer excretion and nutrient element pools are reported for soil microarthropods, using new methods of counting and microprobe elemental analysis. Research on arthropod-fungal relations is utilizing high-efficiency extraction followed by dissection of 13 x 13 cm soil blocks. A two-component excretion model is reported for Cobalt-60 in earthworms (Eisenia foetida), demonstrating that no assimilation of cobalt occurs from the mineral soil fraction but is entirely from organic matter. Collection of data sets on soil arthropod communities and abundances is completed.

Crossley, Jr, D A

1980-08-01

216

Stimulating effect of earthworm excreta on the mineralization of nitrogen compounds in soil  

NASA Astrophysics Data System (ADS)

The effect of excreta of earthworm species Aporrectodea caliginosa and Eisenia fetida on the mineralization of nitrogen compounds in soils has been studied. A single application of excreta obtained from three earthworms in one day increased the formation of nitrate nitrogen compounds in the soil by 10 50%. The application of ammonium nitrogen (in the form of NH4Cl) in amounts equivalent to the ammonium nitrogen content in the daily excreta of three earthworms had the same effect on the mineralization of nitrogen compounds. The effect of earthworm excreta, as well as the effect of ammonium nitrogen, on the nitrification process was an order of magnitude higher than their contribution to the formation of nitrates due to the oxidation of the introduced ammonium. Hence, ammonium—an important component of the earthworm excreta—can exert a stimulating effect on nitrification processes in the soil and produce long-term cumulative effects that are much more significant than the direct effect of this nitrogen compound.

Bityutskii, N. P.; Solov'eva, A. N.; Lukina, E. I.; Oleinik, A. S.; Zavgorodnyaya, Yu. A.; Demin, V. V.; Byzov, B. A.

2007-04-01

217

Carbon and nitrogen mineralization in a vineyard soil amended with grape marc vermicompost.  

PubMed

Vineyard soils in many areas suffer from low organic matter contents, which can be the cause of negative effects such as increasing the risk of erosion, so the use of organic amendments must be considered a good agricultural practice. Even more, if grape marc is recycled as a soil amendment in the vineyards, benefits from a good waste management strategy are also obtained. In the present study, a grape marc from the wine region of Valdeorras (north-west Spain) was used for the production of vermicompost, and this added to a vineyard soil of the same area in a laboratory study. Mixtures of soil and grape marc vermicompost (2 and 4%, dry weight) were incubated for ten weeks at 25°C and the mineralization of C and N studied. The respiration data were fitted to a first-order kinetic model. The rates of grape marc vermicompost which should be added to the vineyard soil in order to maintain the initial levels of organic matter were estimated from the laboratory data, and found to be 1.7?t?ha(-1)?year(-1) of bulk vermicompost (if the present mean temperature is considered) and 2.1?t?ha(-1)?year(-1) of bulk vermicompost (if a 2°C increment in temperature is considered), amounts which could be obtained recycling the grape marc produced in the exploitation. PMID:20837558

Paradelo, Remigio; Moldes, Ana Belén; Barral, María Teresa

2011-11-01

218

Effect of electrolytes and soil mineral surfaces on N2O hydrate formation kinetics  

NASA Astrophysics Data System (ADS)

Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by IPCC (Intergovernmental Panel on Climate Change) and its global warming potential (GWP) is 310 times higher than that of carbon dioxide (CO2). Gas hydrates are unique crystalline compounds that trap suitable guest gas molecules (size between 0.35 and 0.9 nm) stably inside the hydrogen-bonded water cages via van der Waals interaction under high pressure and low temperature conditions. N2O has similar properties (e.g. van der Waals diameter, molar mass, density, etc.) with CO2 except for polarity and it was revealed that both N2O and CO2 can be formed as hydrate s-I in natural environment. In this study, we have identified the effect of electrolytes (NaCl, KCl, CaCl2, MgCl2) and solid surfaces (illite, nontronite, sphalerite, kaolinite, montmorillonite) on the N2O hydrate formation kinetics. The hydrate formation experiments were conducted by injecting N2O gas into the soil mineral suspensions with and without electrolytes in a 50mL pressurized vessel. The formation of N2O hydrate in aqueous electrolyte solutions was slower than that in deionized water. Ion charge and size were significant factors affecting N2O hydrate formation kinetic in electrolytes solutions. The addition of soil mineral suspensions accelerated the formation of N2O hydrate in the electrolyte solutions. Surface area and ionic strength of soil minerals highly influenced on formation kinetic of N2O hydrate. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. The results obtained from this research could be indirectly applied to the fate of N2O sequestered into geological formations as well as its storage as a form of N2O hydrate.

Kyung, D.; Ha, S.; Lee, W.

2013-12-01

219

The impact of climate change on the soil/moisture regime of Scottish mineral soils.  

PubMed

The likely impact of climate change on the moisture regime of Scottish soils and consequently on agriculture and land use has been addressed using a novel Geographic Information Systems (GIS) approach. Current estimates of changes in summer precipitation by the year 2030 are 0% with an associated uncertainty of +/- 11%. This study considers the worst case scenario of a decrease in rainfall by 11% which will lead to some low rainfall areas experiencing an increased drought risk, particularly on lighter soils. Wet areas with heavy soils could benefit from an increase in the accessibility period for machinery. As the major agricultural land in Scotland is located on the relatively dry east coast where localised problems due to drought are not uncommon even under the present climate, the detrimental effects of a decrease in rainfall for the whole of Scotland are therefore likely to outweigh the benefits. Approximately 8% of Scotland has been identified in this study as soil/climate combinations which will be susceptible to drought should summer rainfall decrease by 11% and summer temperature increase by 1.4 degrees C. PMID:15091767

MacDonald, A M; Matthews, K B; Paterson, E; Aspinall, R J

1994-01-01

220

Measurement of net nitrogen and phosphorus mineralization in wetland soils using a modification of the resin-core technique  

USGS Publications Warehouse

A modification of the resin-core method was developed and tested for measuring in situ soil N and P net mineralization rates in wetland soils where temporal variation in bidirectional vertical water movement and saturation can complicate measurement. The modified design includes three mixed-bed ion-exchange resin bags located above and three resin bags located below soil incubating inside a core tube. The two inner resin bags adjacent to the soil capture NH4+, NO3-, and soluble reactive phosphorus (SRP) transported out of the soil during incubation; the two outer resin bags remove inorganic nutrients transported into the modified resin core; and the two middle resin bags serve as quality-control checks on the function of the inner and outer resin bags. Modified resin cores were incubated monthly for a year along the hydrogeomorphic gradient through a floodplain wetland. Only small amounts of NH4+, NO3-, and SRP were found in the two middle resin bags, indicating that the modified resin-core design was effective. Soil moisture and pH inside the modified resin cores typically tracked changes in the surrounding soil abiotic environment. In contrast, use of the closed polyethylene bag method provided substantially different net P and N mineralization rates than modified resin cores and did not track changes in soil moisture or pH. Net ammonification, nitrifi cation, N mineralization, and P mineralization rates measured using modified resin cores varied through space and time associated with hydrologic, geomorphic, and climatic gradients in the floodplain wetland. The modified resin-core technique successfully characterized spatiotemporal variation of net mineralization fluxes in situ and is a viable technique for assessing soil nutrient availability and developing ecosystem budgets.

Noe, Gregory B.

2011-01-01

221

Field-scale variation in microbial activity and soil properties in relation to mineralization and sorption of pesticides in a sandy soil.  

PubMed

Pesticides applied to agricultural soils are subject to environmental concerns because leaching to groundwater reservoirs and aquatic habitats may occur. Knowledge of field variation of pesticide-related parameters is required to evaluate the vulnerability of pesticide leaching. The mineralization and sorption of the pesticides glyphosate and metribuzin and the pesticide degradation product triazinamin in a field were measured and compared with the field-scale variation of geochemical and microbiological parameters. We focused on the soil parameters clay and organic carbon (C) content and on soil respiratory and enzymatic processes and microbial biomass. These parameters were measured in soil samples taken at two depths (Ap and Bs horizon) in 51 sampling points from a 4-ha agricultural fine sandy soil field. The results indicated that the spatial variation of the soil parameters, and in particular the content of organic C, had a major influence on the variability of the microbial parameters and on sorption and pesticide mineralization in the soil. For glyphosate, with a co-metabolic pathway for degradation, the mineralization was increased in soils with high microbial activity. The spatial variability, expressed as the CV, was about five times higher in the Bs horizon than in the Ap horizon, and the local-scale variation within 100 m(2) areas were two to three times lower than the field-scale variation within the entire field of about 4 ha. PMID:18689732

Vinther, F P; Brinch, U C; Elsgaard, L; Fredslund, L; Iversen, B V; Torp, S; Jacobsen, C S

2008-01-01

222

Mineralization of nitrogen compounds in soils of south-taiga ecosystems  

NASA Astrophysics Data System (ADS)

The productivity of the nitrogen mineralization in the A0 (0-2 cm), A1 (2-3 cm), and A2 (3-13 cm) horizons of a soddy-podzolic soil was measured in a wood-sorrel-whortleberry birch forest (7Birch3Asp, 80 years, the second stand quality class, tree canopy density 0.7, Yaroslavl oblast) using the sample incubation method; the measurements were performed from May till October in eight replicates for each horizon. In 2007, 5.85 ± 0.73 g N/m2 were mineralized in the soil. In the litter, 2.01 ± 0.23 g N/m2 were mineralized, whereas 0.35 ± 0.03 and 3.49 ± 0.72 g N/m2 were mineralized in the A1 and A2 horizons, respectively. In 2008, 3.34 ± 0.25 g N/m2 were mineralized in the A0 and A1 horizons, of which 2.44 ± 0.23 g N/m2 were in the former. Ammonification prevailed in all the horizons. The contribution of nitrification was assessed as 1.6 and 0.3% of the process’s productivity in 2007 and 2008, respectively. The Corg and Norg pools decreased in the litter by 407 g C/m2 and 13.7g N/m2 (or 33%) from May to October. Of this carbon amount, 67% is spent for humification and the organic mass preservation and 33% was transformed to carbonic acid. The nitrogen expenses for the synthesis of humus acids are equal to 70 and 30%; it is spent equally for the mineralization of the element and its immobilization by microorganisms. In the A0 and A1 horizons, the seasonal trends of the ammonification correlated with the carbon dioxide emission from these horizons in the year of 2008 with r = 0.75 atp = 0.09 and r = 0.82 atp = 0.04 for both horizons, respectively.

Razgulin, S. M.

2010-06-01

223

Effects of temperature on microbial C metabolism in peat and mineral soil  

NASA Astrophysics Data System (ADS)

Microbial metabolism, the main mechanism responsible for soil CO2 emissions, plays an important role in the global C cycle. Increased temperature generally stimulates decomposition and respiration, indicative of increased microbial C metabolism and possibly greater energy demand by microbes for growth and maintenance. Changes in microbial metabolism with temperature may manifest differently in microbial communities from soils with different C availability because it is generally expected that when more organic C is present, carbon use efficiency (CUE) will be lower and more CO2 will be released per unit C assimilated by microbes than when less C substrate is available. In this study we examined the effect of temperature on C processing in peat and mineral soil from the Marcel Experimental Forest in Minnesota. Samples were incubated for 7 days at 5, 10, 15, and 20°C. We used position-specific 13C-labeled tracers to model C flux through the central C metabolic network (i.e. glycolysis, pentose phosphate pathway, and the citric acid cycle) and to asses the CUE of microbial communities. We also measured total CO2 production and microbial biomass, and we calculated the metabolic quotient (qCO2), which is the rate of CO2, respired per unit of microbial biomass. We found that temperature and soil type did not affect CUE and patterns of C flow through the central C metabolic network. Increased temperature stimulated respiration and decreased qCO2 in peat more than the mineral soil. These results suggest temperature affects rate of C cycling, but does not alter the relative demand for energy production and biosynthesis per unit substrate-C. This implies, in contrast to expectations that at higher temperatures more substrate will be used to offset greater demand for maintenance energy, warmer temperatures will not alter the balance of growth and maintenance energy by soil microbes. Moreover, substrate availability did not result in ';wasteful' C use, but increased C cycling rates. These findings may simplify the modeling of soil respiration with climatic warming.

Hagerty, S.; Dijkstra, P.; Miller, E.; Schwartz, E.; KOCH, G. W.; Hungate, B. A.

2013-12-01

224

Nitrogen mineralization and microbial activity in oil sands reclaimed boreal forest soils.  

PubMed

Organic materials including a peat-mineral mix (PM), a forest floor-mineral mix (L/S), and a combination of the two (L/PM) were used to cap mineral soil materials at surface mine reclamation sites in the Athabasca oil sands region of northeastern Alberta, Canada. The objective of this study was to test whether LFH provided an advantage over peat by stimulating microbial activity and providing more available nitrogen for plant growth. Net nitrification, ammonification, and N mineralization rates were estimated from field incubations using buried bags. In situ gross nitrification and ammonification rates were determined using the 15N isotope pool dilution technique, and microbial biomass C (MBC) and N (MBN) were measured by the chloroform fumigation-extraction method. All reclaimed sites had lower MBC and MBN, and lower net ammonification and net mineralization rates than a natural forest site (NLFH) used as a control, but the reclamation treatment using LFH material by itself had higher gross and net nitrification rates. A positive correlation between in situ moisture content, dissolved organic N, MBC, and MBN was observed, which led us to conduct a moisture manipulation experiment in the laboratory. With the exception of the MBN for the L/S treatment, none of the reclamation treatments ever reached the levels of the natural site during this experiment. However, materials from reclamation treatments that incorporated LFH showed higher respiration rates, MBC, and MBN than the PM treatment, indicating that the addition of LFH as an organic amendment may stimulate microbial activity as compared to the use of peat alone. PMID:17766826

McMillan, R; Quideau, S A; MacKenzie, M D; Biryukova, O

2007-01-01

225

Sol-Gel Precursors for Ceramics from Minerals Simulating Soils from the Moon and Mars  

NASA Technical Reports Server (NTRS)

Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report some preliminary results on the production of sol-gel precursors for ceramic products using mineral resources available in Martian or Lunar soil. The presence of SiO2, TiO2, and A12O3 in both Martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and Lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from Lunar and Martian simulant soils. Clear sol-gel precursors have been obtained by dissolution of silica from Lunar simulant soil in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy were used to characterize the elemental composition and structure of the precursor molecules. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors. In the second set of experiments, we used the same starting materials to synthesize silicate esters in acidified alcohol mixtures. Preliminary results indicate the presence of silicon alkoxides in the product of distillation.

Sibille, Laurent; Gavira-Gallardo, Jose-Antonio; Hourlier-Bahloul, Djamila

2003-01-01

226

Mineral magnetic measurements as a particle size proxy for urban roadside soil pollution (part 1).  

PubMed

The use of mineral magnetic concentration parameters (?LF, ?ARM and SIRM) as a potential particle size proxy for soil samples collected from Wolverhampton (UK) is explored as an alternative means of normalizing particle size effects. Comparison of soil-related analytical data by correlation analyses between each magnetic parameter and individual particle size classes (i.e. sand, silt and clay), more discrete intervals within classes (e.g. fine sand or medium silt) and cumulative size fractions (e.g. clay + fine silt) are reported. ?LF, ?ARM and SIRM parameters reveal significant (p < 0.05; p < 0.001 n = 60), moderate negative (rs = -0.3 to -0.557) associations with clay, silt and sand content. Contrary to earlier research findings which found positive relationships, this indicates that magnetic measurements cannot always provide a predictable particle size proxy and it is only certain environments and/or specific settings that are appropriate for granulometric normalization by this technique. However, if future researchers working in other soil settings can identify a formal predictable relationship, the technique is known to offer a simple, reliable, rapid, sensitive, inexpensive and non-destructive approach that could be a valuable proxy for normalizing particle size effects in soil contamination studies. PMID:24365865

Crosby, C J; Booth, C A; Fullen, M A

2014-03-01

227

Impact of Surface Roughness and Soil Texture on Mineral Dust Emission Fluxes Modeling  

NASA Technical Reports Server (NTRS)

Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

Menut, Laurent; Perez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, Stephane

2013-01-01

228

A kinetic approach to evaluate salinity effects on carbon mineralization in a plant residue-amended soil*  

PubMed Central

The interaction of salinity stress and plant residue quality on C mineralization kinetics in soil is not well understood. A laboratory experiment was conducted to study the effects of salinity stress on C mineralization kinetics in a soil amended with alfalfa, wheat and corn residues. A factorial combination of two salinity levels (0.97 and 18.2 dS/m) and four levels of plant residues (control, alfalfa, wheat and corn) with three replications was performed. A first order kinetic model was used to describe the C mineralization and to calculate the potentially mineralizable C. The CO2-C evolved under non-saline condition, ranged from 814.6 to 4842.4 mg CO2-C/kg in control and alfalfa residue-amended soils, respectively. Salinization reduced the rates of CO2 evolution by 18.7%, 6.2% and 5.2% in alfalfa, wheat and corn residue-amended soils, respectively. Potentially mineralizable C (C 0) was reduced significantly in salinized alfalfa residue-treated soils whereas, no significant difference was observed for control treatments as well as wheat and corn residue-treated soils. We concluded that the response pattern of C mineralization to salinity stress depended on the plant residue quality and duration of incubation. PMID:16972320

Nourbakhsh, Farshid; Sheikh-Hosseini, Ahmad R.

2006-01-01

229

Stabilisation of soil organic matter by interactions with minerals as revealed by mineral dissolution and oxidative degradation  

Microsoft Academic Search

Soil organic matter is known to contain a stable fraction with an old radiocarbon age. Size and stabilisation processes leading to the formation of this old soil carbon pool are still unclear. Our study aims to differentiate old organic matter from young and labile carbon compounds in two acid forest soils (dystric cambisol, haplic podzol). To identify such fractions soil

Karin Eusterhues; Cornelia Rumpel; Markus Kleber; Ingrid Kögel-Knabner

2003-01-01

230

Patterns of spatial distribution of mineral components of the complex of gray forest soils Vladimir opolye  

NASA Astrophysics Data System (ADS)

The aim of the work is the analysis of spatial distribution of soil fundamental characteristics - fine fractions content (less than 1, 1-5, 5-10 and more than 10 mkm) and their mineralogical composition. The experiments were carried out on the experimental field in Suzdal region in a trench (22 m length and 2 m depth) laid in upland, well-drained conditions. Soil samples from 5 different soil profiles were collected. Fractions were obtained by Gorbunov method. Mineralogical analysis were carried out by universal X-ray diffractometer (Carl Zeiss Jena, Germany). The dominant fraction is a coarse silt fraction, the sand fraction content is negligible. The soil is characterized by medium-textured loam composition from the above and a sandy loam composition in the bottom. Textural differentiation occured due to the distribution of clay fraction. The content of this fraction in plough horizons varies depending on addition of part of other horizons during plowing. The plogh-layer of the residual-carbonate agrogrey soil is characterized by higher (20-23 %) amount of fraction less than 1 mkm, in comparison with plough horizon above the second humus horizon (SHH ), where the amount of silt is 15-16 %. The main components of the fraction derived from the rock are complex mixed- lattice formations dominated by mica - smectite with a high proportion of smectite packages, mica - smectites with low content of smectite packages were in subordinate quantity. The next component is hydromica - a mixture of dioctahedral and trioctahedral varieties. Smectite phase and hydromica add up to 85-90 % of the silt component. The amount of kaolinite and chlorite usually range in 7-13 %. Kaolinite is generally imperfect, chlorite is magnesia-ferric. The presence of fine quartz and feldspars (less amount) is revealed. During the soil formation the redistribution of the above minerals whose behavior is caused by the type of soil is occurring. Agrogrey heavy-textured soils are characterized by textural differentiation of the profile. The main carrier of this differentiation is the silt fraction, mainly its component - the swelling phase. Smectite phase dominates in silt fraction and it is eluvially distributed within the soil profile. Silty fraction of loess loam contains 72 % of the smectite phase. Behavior of minerals constituting the sum of kaolinite and chlorite content indicates its relatively uniform distribution. A slight increase in their content is noted in the eluvial part of the profile, mainly due to increasing in the proportion of kaolinite. The amount of hydromica reduces down the profile from 44.2 % to 19.8% in loess loam (soil-forming rock). The ratio of dioctahedral structures of hydromica to trioctahedral changes within the soil profile: trioctahedral varieties are more abundant in the upper part of the profile.

Karpova, Dina; Chizhikova, Natalya; Starokozhko, Natalya; Hadyushina, Viktorya; Korotaeva, Valentina

2014-05-01

231

Extraction Pattern of Arsenic Species with Mineral Composition in Contaminated Soils in Korea  

NASA Astrophysics Data System (ADS)

Specific determination of various arsenic species is gaining increasing attention because the toxicity of arsenic differs with chemical forms such as organic (MMA, DMA) or inorganic (arsenite, arsenate). Knowledge of extraction method for arsenic speciation in contaminated soils then notified and tested by many researchers. However, the analytical technique for separation of different arsenic species has been always challenging in different environmental samples. A achieving correct analytical results and resolving the lowest detection limit is also desirable. Extraction method for arsenic speciation have been studied by many researchers with the use of a variety of extractants such as H3PO4, HCl, Na2CO3, EDTA 'in soils and sediments including plenty of clay. We, in this study, reported a benign extraction method and presented the pattern of arsenic in contaminated soils of different mineral compositions. Soil samples were collected from tailings of 2 places (Kyungbuk, Jeonnam); both were from abandoned metal mines in Korea. Samples were air dried at room temperature and separated by mechanical sieving to three fractions (2mm_200 ?m, 200_64?m, <64?m). Prepared samples were examined for total arsenic analysis used by KBSI method and modified Garcia-Manyes method for arsenic speciation. We extracted arsenic species from the soils by using a mixture of 1M phosphoric acid and 0.1% ascorbic acid. 0.2g of sample was placed in microwave digestion vessels along with 10ml extraction solution and treated for 15min at 60w microwave power. After the microwave stage, the contents were transferred to 30ml sample bottles and diluted to 16ml with deionized water, then centrifuged for 15min at 2500rpm. Total arsenic concentration of sample was analyzed by using ICP-AES (ICP-OES, Ultima2C, Jobin Yvon) and the arsenic species were analyzed by hyphenated system, SPE-HG-ICP-AES. To identify the mineral phases in bulk soil samples, we used XRD (Phillips X'Pert MPD) under 40kV/30mA condition. XRD data was collected between 5 and 70° 2theta values using CuK? target.

Park, M.; Shin, M.; Yoon, H.; Kim, Y.; Kim, K.; Ko, I.

2006-12-01

232

Mineral cycling in soil and litter arthropod food chains. Annual progress report, February 1, 1983-January 31, 1984  

SciTech Connect

This annual report describes progress in research on the influence of soil fauna on the general process of terrestrial decomposition. The major goal is to investigate the regulation of decomposition by soil arthropods. Methods have included radioactive tracer measurements of food chain dynamics, rates of nutrient or mineral element flow during decomposition, and simulation modeling. This year's report describes significant progress in defining the influence of soil arthropods in stimulating microbial immobilization of nutrients. Preliminary efforts to define the importance of the soil-litter macroarthropods are also reported.

Crossley, D.A. Jr.

1983-09-30

233

Application of calcium carbonate slows down organic amendments mineralization in reclaimed soils  

NASA Astrophysics Data System (ADS)

A field experiment was set up in Cartagena-La Unión Mining District, SE Spain, aimed at evaluating the short-term effects of pig slurry (PS) amendment alone and together with marble waste (MW) on organic matter mineralization, microbial activity and stabilization of heavy metals in two tailing ponds. These structures pose environmental risk owing to high metals contents, low organic matter and nutrients, and null vegetation. Carbon mineralization, exchangeable metals and microbiological properties were monitored during 67 days. The application of amendments led to a rapid decrease of exchangeable metals concentrations, except for Cu, with decreases up to 98%, 75% and 97% for Cd, Pb and Zn, respectively. The combined addition of MW+PS was the treatment with greater reduction in metals concentrations. The addition of PS caused a significant increase in respiration rates, although in MW+PS plots respiration was lower than in PS plots. The mineralised C from the pig slurry was low, approximately 25-30% and 4-12% for PS and MW+PS treatments, respectively. Soluble carbon (Csol), microbial biomass carbon (MBC) and ?-galactosidase and ?-glucosidase activities increased after the application of the organic amendment. However, after 3 days these parameters started a decreasing trend reaching similar values than control from approximately day 25 for Csol and MBC. The PS treatment promoted highest values in enzyme activities, which remained high upon time. Arylesterase activity increased in the MW+PS treatment. Thus, the remediation techniques used improved soil microbiological status and reduced metal availability. The combined application of PS+MW reduced the degradability of the organic compounds. Keywords: organic wastes, mine soils stabilization, carbon mineralization, microbial activity.

Zornoza, Raúl; Faz, Ángel; Acosta, José A.; Martínez-Martínez, Silvia; Ángeles Muñoz, M.

2014-05-01

234

Soil solid materials affect the kinetics of extracellular enzymatic reactions  

NASA Astrophysics Data System (ADS)

INTRODUCTION Soil solid materials affect the degradation processes of many organic compounds by decreasing the bioavailability of substrates and by interacting with degraders. The magnitude of this effect in the environment is shown by the fact that xenobiotics which are readily metabolized in aquatic environments can have long residence times in soil. Extracellular enzymatic hydrolysis of cellobiose (enzyme: beta-glucosidase from Aspergillus niger) was chosen as model degradation process since it is easier to control and more reproducible than a whole cell processes. Furthermore extracellular enzymes play an important role in the environment since they are responsible for the first steps in the degradation of organic macromolecules; beta-glucosidase is key enzyme in the degradation of cellulose and therefore it is fundamental in the carbon cycle and for soil in general. The aims of the project are: 1) quantification of solid material effect on degradation, 2) separation of the effects of minerals on enzyme (adsorption ?change in activity) and substrate (adsorption ?change in bioavailability). Our hypothesis is that a rate reduction in the enzymatic reaction in the presence of a solid phase results from the sum of decreased bioavailability of the substrate and decreased activity of enzyme molecules. The relative contribution of the two terms to the overall effect can vary widely depending on the chemical nature of the substrate, the properties of the enzyme and on the surface properties of the solid materials. Furthermore we hypothesize that by immobilizing the enzyme in an appropriate carrier the adsorption of enzymes to soil materials can be eliminated and that therefore immobilization can increase the overall reaction rate (activity loss caused by immobilization < activity loss caused by adsorption to soil minerals). MATERIALS AND METHODS Enzymatic kinetic experiments are carried out in homogeneous liquid systems and in heterogeneous systems where solid materials (bentonite, kaolinite, goethite, activated charcoal) are suspended in a mixed liquid (standard experimental conditions: 66 mM phosphate buffer, pH 5, 25°C, 20 mg solid/ml buffer). The enzyme in an immobilized form (covalent bonding to oxirane groups on the surfaces of macroporous Eupergit® C particles) is used to exclude a direct effect of soil solid materials on the enzyme without excluding their effect on the availability of the substrate.The progress of the reactions is determined by measuring the accumulation of the product (i.e. glucose) in the systems at different times (after destroying enzymatic activity by boiling the samples) with a coupled enzymatic assay and an automatic microplate spectrophotometer. A regression analysis on the data points is performed to calculate the initial reaction rates, which is the parameter that allows to compare the different systems. RESULTS AND DISCUSSION The results show that, under the standard experimental conditions, cellobiose is not adsorbed by the clay minerals bentonite and kaolinite and by the iron oxyhydroxide goethite. In the case of activated charcoal a rapid adsorption phase in the first 20' is followed by a much slower process; after 4h 30' approximately 98% of cellobiose was adsorbed. The results from the adsorption experiments of beta-glucosidase to bentonite, kaolinite, goethite and activated charcoal show that, under the standard experimental conditions, the adsorption process is rapid in all cases (more than 80% of the adsorption takes place in the first 20 minutes). After 1h 20min the following fractions of enzyme were adsorbed: 30 % to bentonite, 60% to kaolinite, 67% to goethite, 100% to activated charcoal. The effect of kaolinite on the reaction rate was quantified: under the standard experimental conditions the initial reaction rate in presence of the mineral was 22% less then in the control. The fraction of enzyme molecules which are adsorbed to kaolinite (60%) loses 37% of its activity. CONCLUSIONS The results from the adsorption experiments lead to the conclusion that, among the sol

Lammirato, C.; Miltner, A.; Kästner, M.

2009-04-01

235

Modeling of Phenoxy Acid Herbicide Mineralization and Growth of Microbial Degraders in 15 Soils Monitored by Quantitative Real-Time PCR of the Functional tfdA Gene  

PubMed Central

Mineralization potentials, rates, and kinetics of the three phenoxy acid (PA) herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), were investigated and compared in 15 soils collected from five continents. The mineralization patterns were fitted by zero/linear or exponential growth forms of the three-half-order models and by logarithmic (log), first-order, or zero-order kinetic models. Prior and subsequent to the mineralization event, tfdA genes were quantified using real-time PCR to estimate the genetic potential for degrading PA in the soils. In 25 of the 45 mineralization scenarios, ?60% mineralization was observed within 118 days. Elevated concentrations of tfdA in the range 1 × 105 to 5 × 107 gene copies g?1 of soil were observed in soils where mineralization could be described by using growth-linked kinetic models. A clear trend was observed that the mineralization rates of the three PAs occurred in the order 2,4-D > MCPA > MCPP, and a correlation was observed between rapid mineralization and soils exposed to PA previously. Finally, for 2,4-D mineralization, all seven mineralization patterns which were best fitted by the exponential model yielded a higher tfdA gene potential after mineralization had occurred than the three mineralization patterns best fitted by the Lin model. PMID:22635998

Bælum, Jacob; Prestat, Emmanuel; David, Maude M.; Strobel, Bjarne W.

2012-01-01

236

Does temperature of charcoal creation affect subsequent mineralization of soil carbon and nitrogen?  

NASA Astrophysics Data System (ADS)

Forest fire is the most common form of natural disturbance of boreal forest ecosystems and has primordial influence on successional processes. This may be due in part to the pre-disturbance vegetation development stage and species composition, but these successional pathways could also vary with differences in fire behavior and consequently in fire intensity, defined as the energy released during various phases of a fire. Fire intensity may also affect soil C and N cycling by affecting the quality of the charcoal that is produced. For example, the porosity of coal tends to increase with increasing temperature at which it is produced Higher porosity would logically increase the surface area to which dissolved soil molecules, such as tannins and other phenolics, may be adsorbed. We report on a microcosm study in which mineral and organic soils were jointly incubated for eight weeks with a full factorial array of treatments that included the addition of Kalmia tannins, protein, and wood charcoal produced at five different temperatures. A fourth experimental factor comprised the physical arrangement of the material (stratified vs. mixed), designed to simulate the effect of soil scarification after fire and salvage harvest. We examined the effects of these treatments on soil C and N mineralisation and soil microbial biomass. The furnace temperature at which the charcoal was produced had a significant effect on its physico-chemical properties; increasing furnace temperatures corresponded to a significant increase in % C (P<0.001), and a significant decrease in %O (P<0.001) and %H (P<0.001). Temperature also had significant impacts on microporosity (surface area and volume). Temperature of production had no effect (P=0.1355) on soil microbial biomass. We observed a linear decreasing trend (P<0.001) in qCO2 with increasing temperature of production, which was mainly reflected in a decline in basal respiration. Finally, we found a significant interaction (P=0.010) between temperature of charcoal production x soil mixing in controlling post incubation NH4+ concentrations. We discuss the results in relation to potential implications for changing fire regime and C and N cycles.

Pelletier-Bergeron, S.; Bradley, R.; Munson, A. D.

2012-04-01

237

Soil factors controlling mineral N uptake by Picea engelmannii seedlings: the importance of gross NH4+ production rates.  

PubMed

* Hydroponic studies suggest that plant nitrogen (N) demand determines the rate of mineral N uptake; however, field observations show N limitation to be widespread. Field experiments are needed to understand soil factors controlling mineral N uptake. * We planted Picea engelmannii seedlings that had initially been grown from sterilized seeds, on a recently clearcut site. We applied a hybrid isotope dilution/pulse labelling technique to compare the gross production rate, concomitantly to the plant uptake rate, of soil mineral N. We also measured mineral N concentrations, microbial N, and percent ectomycorrhizal root tips. * Gross NH4+ production rate was the most important determinant of plant uptake rate. Exploratory path analysis suggested that plant uptake was also determined by microbial N, which was, in turn, determined by soil mineral N concentrations. Percent ectomycorrhizal root tips was negatively related to gross NO3- production rate and microbial N concentrations. * We conclude that nutrient flux density is important in controlling plant uptake. Mycorrhizal colonization may alter N dynamics in the rhizosphere without affecting mineral N uptake by seedlings. PMID:15720690

Grenon, F; Bradley, R L; Jones, M D; Shipley, B; Peat, H

2005-03-01

238

Mineral soil carbon and nitrogen still low three decades following clearcut harvesting in a typical Acadian Forest stand  

NASA Astrophysics Data System (ADS)

Given the important role forest soil organic matter (SOM) plays in global greenhouse gas regulation, forest productivity, and functioning of forest ecosystems, it is imperative to understand the effect of intensive forest management practices on forest SOM stores. This study compared SOM in two typical Acadian Forest stands that were both heavily logged in 1900. One of the two stands was clearcut harvested again in 1974, allowing comparison between a 35-year-old clearcut stand and a 110 year-old reference stand. We found lower mineral soil carbon (C) and nitrogen (N) storage (27% and 26%, respectively), and lower C and N concentrations in the top 50 cm of soil of the 35-year-old stand compared with the 110-year-old stand. Isotopic compositions of C and N characterized for each site through the soil profile, showed patterns consistent with other profile studies, but did not identify significant differences between sites within specific soil strata. This study demonstrates a clear trend of soil C and N losses following clearcut harvesting in this temperate forest system by sampling to a depth of at least 50 cm and using a reference site that had been left undisturbed for at least 110 years. The study design emphasized within stand spatial representation and analysis of the mineral soil component of the soil profile, factors that have helped to elucidate forest soil C and N dynamics in the decades following this intensive forest management practice.

Kellman, L. M.; Prest, D.; Lavigne, M.; Gabriel, C.

2013-12-01

239

Long Term Effect of Land Reclamation from Lake on Chemical Composition of Soil Organic Matter and Its Mineralization  

PubMed Central

Since the late 1950s, land reclamation from lakes has been a common human disturbance to ecosystems in China. It has greatly diminished the lake area, and altered natural ecological succession. However, little is known about its impact on the carbon (C) cycle. We conducted an experiment to examine the variations of chemical properties of dissolved organic matter (DOM) and C mineralization under four land uses, i.e. coniferous forest (CF), evergreen broadleaf forest (EBF), bamboo forest (BF) and cropland (CL) in a reclaimed land area from Taihu Lake. Soils and lake sediments (LS) were incubated for 360 days in the laboratory and the CO2 evolution from each soil during the incubation was fit to a double exponential model. The DOM was analyzed at the beginning and end of the incubation using UV and fluorescence spectroscopy to understand the relationships between DOM chemistry and C mineralization. The C mineralization in our study was influenced by the land use with different vegetation and management. The greatest cumulative CO2-C emission was observed in BF soil at 0–10 cm depth. The active C pool in EBF at 10–25 cm had longer (62 days) mean residence time (MRT). LS showed the highest cumulative CO2-C and shortest MRT comparing with the terrestrial soils. The carbohydrates in DOM were positively correlated with CO2-C evolution and negatively correlated to phenols in the forest soils. Cropland was consistently an outlier in relationships between DOM chemistry and CO2-evolution, highlighting the unique effects that this land use on soil C cycling, which may be attributed the tillage practices. Our results suggest that C mineralization is closely related to the chemical composition of DOM and sensitive to its variation. Conversion of an aquatic ecosystem into a terrestrial ecosystem may alter the chemical structure of DOM, and then influences soil C mineralization. PMID:24905998

He, Dongmei; Ruan, Honghua

2014-01-01

240

Enhanced Mineralization of [U-14C]2,4-Dichlorophenoxyacetic Acid in Soil from the Rhizosphere of Trifolium pratense  

PubMed Central

Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/?-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 ?g g?1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g?1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of ?-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway. PMID:15294813

Shaw, Liz J.; Burns, Richard G.

2004-01-01

241

Mineralization of carbon during moist incubation of soil JF79 treated with organic heat-transfer and storage fluids  

SciTech Connect

Biodegradability of four heat transfer/storage fluids (ethylene glycol, Therminol 66, Caloria HT43, and Dow Corning Fluid No. 200) were examined. The degradation was monitored by periodically measuring the mineralization of carbon in moist fluid-contaminated soils incubated at 28/sup 0/ and 37/sup 0/C for 8 weeks. Ethylene glycol mineralized relatively readily. The other three fluids did not show measurable amount of carbon mineralization during the experimental period. This implies potential long term environmental effects of mismanaged or accidental releases of these fluids into natural environment.

Nishita, H.; Haug, R.M.

1981-01-01

242

Carbon mineralization of flooded boreal soil and vegetation under different temperature and oxygen conditions  

NASA Astrophysics Data System (ADS)

Flooding of terrestrial ecosystems significantly alters carbon (C) mineralization rates, which results in increasing emissions of carbon dioxide (CO2) and methane (CH4). To better understand the changes after water impoundment, C mineralization under flooded conditions needs to be investigated. This study investigates CO2 and CH4 fluxes from flooded boreal soil and vegetation, compares them to the fluxes of non- flooded treatment, and examines how environmental factors affect the fluxes. We conducted short-term in vitro experiments using boreal forest soil (FH layer), peat soil (0 to 5 and 5 to 15 cm) layer, and black spruce needles and small twigs, and shrub, sedge, lichen, and moss tissues. Flooded samples were incubated in 1- L Mason jars without light, under three temperatures (5, 12, and 24degC) and 0 and 50 percent of ambient oxygen (O2) concentration, and non-flooded ones were incubated in 1-L plastic containers under same light and temperature conditions to those of flooded samples and ambient oxygen concentration. We collected gas samples after flushing with nitrogen gas and air, and the fluxes of CO2 and CH4 were determined by gas chromatography. The average CO2 and CH4 fluxes in all materials were 200 and 0.8 microgram C/g organic matter/day, with smaller CO2 fluxes and larger CH4 fluxes than the fluxes of non-flooding (CO2 and CH4: 370 and 0.2 microgram C/g organic matter/day). Among the flooded samples, forest and peatland ground vegetation showed much high CO2 fluxes, and peat soils released more CH4 than other materials. Higher temperatures increased emissions of both CO2 and CH4, and the lower O2 concentration increased CH4 emissions. These results suggest the flooded vegetation and peat soil largely contribute to the total C emission in the flooded ecosystem and that spatial and temporal variability in CO2 and CH4 emissions can be related to substrate type, temperature and O2 concentration.

Kim, Y.; Ullah, S.; Roulet, N.; Moore, T.

2009-05-01

243

Linking soil element-mass-transfer to microscale mineral weathering in the Santa Catalina Critical Zone Observatory  

NASA Astrophysics Data System (ADS)

Soil chemical denudation and mineral transformation contributes significantly to landscape evolution and to our understanding of water and carbon cycling across ecosystems. The main objective of this research was to couple the chemical composition of bulk soils to the elemental changes associated with microscale mineral transformations to better understand climatic controls on soil development in semi-arid and sub-humid environments. Soil profiles to the depth of refusal and representative parent rock samples were collected from granitic terrain across the Santa Catalina Mountain Critical Zone observatory (SCM-CZO) environmental gradient that spans desert scrub to mixed conifer forest ecosystems. Bulk elemental chemistry, including major, minor, and trace elemental constituents, was determined by x-ray fluorescence (XRF) for all samples and microscale weathering patterns were quantified using electron microprobe analyses. From these data, elemental mass-transfer percentages were calculated and normalized to the parent rock materials using Na and Zr as the mobile and immobile inputs, respectively. Chemical depletions of Na, a proxy for plagioclase feldspar weathering, was observed in both the desert scrub and mixed conifer ecosystems. Na chemical loss was most consistent with depth and across soil pedons (n = 4) in the mixed conifer system where sodium depletion averaged 46% (± 5%) relative to the parent material, providing evidence for loss of plagioclase to chemical weathering. Electron microprobe analyses of surface and subsurface soils at the mixed conifer site revealed a significant decrease in sodium weight percent from the unaltered regions of the grains (Na of ~7-8%) to fully transformed areas of the grains (Na of ~0.2-0.3%) located in joint fractures and at grain edges. In contrast, soils from the desert scrub site exhibited highly variable Na loss in the bulk soils with Na depletion ranging from 23 to 50%. Electron microprobe analyses of desert scrub soils indicated incomplete mineral transformation where sodium weight percents spanned ~7% in un-altered grain centers to ~4% in grain fractures and edges. Backscattered electron (BSE) images support these patterns where more completely transformed minerals were observed in the mixed conifer soils compared to incomplete transformations in soils at the desert scrub site. These results document an important link between bulk soil element loss and microscale weathering processes with increased chemical denudation and mineral transformation in wetter, higher elevation mixed conifer ecosystems.

Lybrand, R. A.; Rasmussen, C.

2012-12-01

244

Applications of PIXE to mineral characterization  

NASA Astrophysics Data System (ADS)

This article illustrates the application of the proton-induced X-ray emission (PIXE) technique to detailed documentation of mineral assemblages, with emphasis on base-metal ores. Some of the investigations aided by the PIXE laboratory at Guelph since 1993 include determinations of the distribution of minor and trace elements in magmatic Ni-Cu ores, volcanogenic massive sulphide Cu-Pb-Zn-(Ag-Au) ores and lode Au-(Ag) deposits. Minor elements of importance include possible by-products or co-products of metal refining, as well as deleterious impurities in mill-feed, e.g. Cd, In, Sn, As, Se, Te, Tl and Hg. Weathering products of primary sulphide mineralization, including tropical laterites and other oxidized assemblages, have been analysed successfully and can contain a wide range of minor elements which reflect the bedrock style of mineralization. The iron oxyhydroxide goethite, ?-FeO(OH), contains trace levels of many elements, and in some cases 1 wt.% or more of base metals and arsenic, elements which are invisible in reflected-light microscopy. Other metals such as Ag are of sporadic occurrence in oxidized ores: they may be found as discrete mineral species, not incorporated into the dominant oxyhydroxides. A summary of findings from three base-metal deposits in Canada, the Philippines and Portugal serves to illustrate the manner in which PIXE data benefit our knowledge of metal distributions in metallic ores. PIXE can contribute to several facets of mineral-deposit research, such as: (1) the development of ore textures, and specifically the distribution of elements within zoned crystals, or between multiple generations of a particular mineral; (2) the location of precious metals, Ag being in general the simplest case; and (3) pinpointing elements that may have implications for ore genesis, environmental quality or metal refining, such as Cr, As and Se.

Wilson, Graham C.; Rucklidge, John C.; Campbell, John L.; Nejedly, Zdenek; Teesdale, William J.

2002-04-01

245

Effect of four experimental insecticides on enzyme activities and levels of adenosine triphosphate in mineral and organic soils  

Microsoft Academic Search

A laboratory study was conducted to determine the effect of four experimental insecticides, DOWCO429X, DPX43898, tefluthrin and trimethacarb, on enzyme activities and levels of adenosine 5'?triphosphate (ATP) in mineral and organic soils. DOWCO429X decreased urease activity in organic soil after 7 days while a stimulatory effect was observed with most treatments after 14 days. No inhibition on acetylene (C2H2) reduction

C. M. Tu

1990-01-01

246

Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A. OGWADA ANDD. L. SPARKS2  

E-print Network

Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A, diffusion, reaction kinetics, K-ion selective electrode, energies of activation. Ogwada, R.A., and D.L. Sparks. 1986. Kinetics of ion exchange on clay minerals and soil: II. Elucidation of rate-limiting steps

Sparks, Donald L.

247

Near infrared spectroscopy as a potential tool to monitor the mineralization of exogenous organic matter within the soil  

NASA Astrophysics Data System (ADS)

Many studies have shown that near infrared spectroscopy (NIRS) is an effective method to characterize various soil properties and endogenous or exogenous organic matter. However, the ability of NIRS to monitor the dynamics of organic matter incorporated into the soil has not yet been tested. This method has a great potential as it can be faster, cheaper and more accessible than conventional techniques dealing with this topic. The aim of this study was to evaluate the potential of the visible near infrared (Vis-NIR: 400-2500nm) to monitor the mineralization of organic matter added to the soil by quantifying, over time, its degradation products. This study focused on 2 types of soils, one from France (Neoluvisol developed on silt wind) and the other from Tunisia (Vertic Xerofluvents). Both soils received two types of organic input, poultry manure (C/N = 17.8) and composted pig manure on straw (C/N = 20.6). Moreover, a sample from each soil type, with no organic input, was kept as a reference. The samples were wetted up to field capacity and were incubated at 25°C during 58 days. Analytical data characterizing the mineralization of organic matter, as mineral carbon (C-CO2) and mineral nitrogen (N-NH4 and N-NO3) were collected following periodic measurements. The soil samples spectra were recorded at the same time using an ASD Fieldspec Pro (350-2500 nm). Principal components analysis (PCA) was performed with the analytical data and spectra to find correlations between the mineralization dynamics and changes of spectra, in relation to the exogenous organic matter degradation. Partial least squares (PLS) algorithm was used to calibrate models linking different mineralization parameters to spectral response. Owing to the low number of available samples (28 samples), the models were adjusted using leave one out cross-validation. Direct observation of the spectra as shown that the level of spectral reflectance of soil samples has evolved over time, which means that the state of degradation of organic matter affects soil reflectance in the Vis-NIR. PCA performed with the analytical data discriminates the time according to the 1st axis that explains 50.1% of the observed variance. PCA performed with the reflectance spectra did not show any significant correlation with the time parameter in the 1st factorial plane. However, the 2nd axis of this factorial plane differentiates between soil types. The models calibrated by the mean of PLS to predict direct analytical data (C-CO2, N-NH4 and N-NH3) were quite precise for the cumulative carbon and the mineral nitrogen produced after mineralization of the exogenous organic matter. The performance of these models were R²=0.68-0.78, RMSE=64.92mg C/kg-109.91mg N/kg and ME=3.47mg C/kg-13.94mg N/kg, respectively. Moreover, we have calibrated models to predict the organic carbon (R² = 0.89, RMSE = 352.57 mg C / kg and ME = -50.16mg C / kg) and organic nitrogen (R² = 0.79, RMSE = 9.46% and ME = 0.69%) remaining in the soil samples. The predictions of these indirect variables related to mineralization process were satisfactory. These first results are promising towards the development of a non-intrusive, cheaper and flexible tool to monitor the mineralization of exogenous organic matter within the soil.

Fouad, Youssef; Walter, Christian; Morvan, Thierry; Zaouchi, Yousr; Sanaa, Mustapha

2010-05-01

248

Microbial weathering of apatite and wollastonite in a forest soil: Evidence from minerals buried in a root-free zone  

NASA Astrophysics Data System (ADS)

Mineral weathering is an important process in biogeochemical cycling because it releases nutrients from less labile pools (e.g., rocks) to the food chain. A field experiment was undertaken to determine the degree to which microbes - both fungi and bacteria - are responsible for weathering of Ca-bearing minerals. The experiment was performed at the Hubbard Brook Experimental Forest (HBEF) in the northeastern USA, where acid deposition has leached plant-available calcium from soils for decades. Trees obtain soil nutrients through root uptake as well as through mycorrhizal fungi with which they are symbiotically associated. These fungi extend their hyphae from the tree roots into the soil and exude organic acids that may enhance mineral dissolution. The two most common types of symbiotic fungal-tree associations are ectomycorrhizae, which are associated with spruce (Picea), fir (Abies), and beech (Fagus); and arbuscular mycorrhizae which are commonly associated with angiosperms, such as maples (Acer). To examine the role of fungi and bacteria in weathering of Ca- and/or P-bearing minerals, mesh bags containing sand-sized grains of quartz (as a control), quartz plus 1% wollastonite (CaSiO3), or quartz plus 1% apatite (Ca5(PO4)3F) were buried ~15 cm deep in mineral soil beneath American beech, sugar maple, and mixed spruce and balsam fir stands at the HBEF. Half of the bags were constructed of 50-?m mesh to exclude roots but allow fungal hyphae and bacteria to enter the bags; the remaining bags had 1-?m mesh to exclude fungi and roots but allow bacteria to enter. The bags were retrieved ~ 1, 2 or 4 years after burial. Microbial community composition and biomass in the mesh bags and surrounding soil were characterized and quantified using phospholipid fatty acid (PLFA) analysis. Fungal biomass in the soil and control bags did not differ significantly among stand types. In contrast, the degree of fungal colonization in apatite- and wollastonite-amended bags varied significantly, suggesting that microbial response was due to tree species, type of mycorrhizal fungi, nutrient status of the soils, and mineral composition of the mesh bags. Mineral surfaces were examined using scanning electron microscopy (SEM) to investigate the degree of mineral dissolution as a function of stand type, microbial composition, and time.

Nezat, C. A.

2011-12-01

249

Genetically biodiverse potato cultivars grown on a suitable agricultural soil under compost amendment or mineral fertilization: yield, quality, genetic and epigenetic variations, soil properties.  

PubMed

The use of compost for soil amendment is a promising agricultural practice environmentally and economically viable. In the framework of a wide research project designed to evaluate the effects of soil amendment with municipal solid waste compost in comparison with traditional mineral fertilization practices, 54 different cultivars (Cvs) of potatoes were AFLP (amplified fragment length polymorphism) molecularly fingerprinted. The seven most genetically biodiverse potato Cvs were used to establish an experimental field in southern Italy. The field area was divided into two portions fertilized with compost (20 Mg ha(-1)) or with ammonium sulphate (200 kg ha(-1)). No significant differences in productivity, organoleptic characteristics and element concentrations were observed between the potato tubers obtained with both kinds of soil fertilization, while the tubers grown on compost amended soil showed, on average, higher K concentrations with respect to those grown on mineral fertilised soil. cDNA-AFLP (complementary DNA-AFLP) and MSAP (methylation sensitive amplified polymorphism) analyses were carried out on both leaves and tubers of one selected Cv to estimate if any transcriptome alterations or epigenetic modifications were induced by the two kinds of fertilization, however no variations were detected. Chemical and biological soil qualities (i.e., microbial respiration, FDA hydrolysis, alkaline and acid phosphatase) were assessed on soil samples at the start of the experiment and at the end of potato crop cycle. No significant differences in soil pH and limited ones, in the available fraction of some trace elements, were observed; while conductivity was much higher for the compost amended portion of the experimental field. Microbial respiration, FDA hydrolysis and acid phosphatase activities were significantly increased by compost amendment, in comparison with mineral fertilization. Finally, a sensory panel of potato Cvs detected no significant differences among qualitative descriptors and among potatoes coming from the two differently fertilized soils. PMID:25016108

Cicatelli, Angela; Baldantoni, Daniela; Iovieno, Paola; Carotenuto, Maurizio; Alfani, Anna; De Feis, Italia; Castiglione, Stefano

2014-09-15

250

Carbon dioxide emissions from semi-arid soils amended with biochar alone or combined with mineral and organic fertilizers.  

PubMed

Semi-arid soils cover a significant area of Earth's land surface and typically contain large amounts of inorganic C. Determining the effects of biochar additions on CO2 emissions from semi-arid soils is therefore essential for evaluating the potential of biochar as a climate change mitigation strategy. Here, we measured the CO2 that evolved from semi-arid calcareous soils amended with biochar at rates of 0 and 20tha(-1) in a full factorial combination with three different fertilizers (mineral fertilizer, municipal solid waste compost, and sewage sludge) applied at four rates (equivalent to 0, 75, 150, and 225kg potentially available Nha(-1)) during 182 days of aerobic incubation. A double exponential model, which describes cumulative CO2 emissions from two active soil C compartments with different turnover rates (one relatively stable and the other more labile), was found to fit very well all the experimental datasets. In general, the organic fertilizers increased the size and decomposition rate of the stable and labile soil C pools. In contrast, biochar addition had no effects on any of the double exponential model parameters and did not interact with the effects ascribed to the type and rate of fertilizer. After 182 days of incubation, soil organic and microbial biomass C contents tended to increase with increasing the application rates of organic fertilizer, especially of compost, whereas increasing the rate of mineral fertilizer tended to suppress microbial biomass. Biochar was found to increase both organic and inorganic C contents in soil and not to interact with the effects of type and rate of fertilizer on C fractions. As a whole, our results suggest that the use of biochar as enhancer of semi-arid soils, either alone or combined with mineral and organic fertilizers, is unlikely to increase abiotic and biotic soil CO2 emissions. PMID:24632059

Fernández, José M; Nieto, M Aurora; López-de-Sá, Esther G; Gascó, Gabriel; Méndez, Ana; Plaza, César

2014-06-01

251

Metagenomes from thawing low-soil-organic-carbon mineral cryosols and permafrost of the canadian high arctic.  

PubMed

Microbial release of greenhouse gases from thawing permafrost is a global concern. Seventy-six metagenomes were generated from low-soil-organic-carbon mineral cryosols from Axel Heiberg Island, Nunavut, Canada, during a controlled thawing experiment. Permafrost thawing resulted in an increase in anaerobic fermenters and sulfate-reducing bacteria but not methanogens. PMID:25414511

Chauhan, Archana; Layton, Alice C; Vishnivetskaya, Tatiana A; Williams, Daniel; Pfiffner, Susan M; Rekepalli, Bhanu; Stackhouse, Brandon; Lau, Maggie C Y; Phelps, Tommy J; Mykytczuk, Nadia; Ronholm, Jennifer; Whyte, Lyle; Onstott, Tullis C; Sayler, Gary S

2014-01-01

252

Metagenomes from Thawing Low-Soil-Organic-Carbon Mineral Cryosols and Permafrost of the Canadian High Arctic  

PubMed Central

Microbial release of greenhouse gases from thawing permafrost is a global concern. Seventy-six metagenomes were generated from low-soil-organic-carbon mineral cryosols from Axel Heiberg Island, Nunavut, Canada, during a controlled thawing experiment. Permafrost thawing resulted in an increase in anaerobic fermenters and sulfate-reducing bacteria but not methanogens. PMID:25414511

Chauhan, Archana; Layton, Alice C.; Vishnivetskaya, Tatiana A.; Williams, Daniel; Pfiffner, Susan M.; Rekepalli, Bhanu; Stackhouse, Brandon; Lau, Maggie C. Y.; Phelps, Tommy J.; Mykytczuk, Nadia; Ronholm, Jennifer; Whyte, Lyle; Onstott, Tullis C.

2014-01-01

253

Microbiological quality of organic vegetables produced in soil treated with different types of manure and mineral fertilizer  

Microsoft Academic Search

An attempt was made to evaluate microbiological quality of horticultural crops grown organically. Three species of vegetables were used, lettuce (Lactuva sativa), radish (Raphanus sativus) and spinach (Tetragonia expansa), grown organically, in fertile soil. Six different treatments were applied: mineral fertilizer, chicken, cow, and pig manure, chicken litter and cow manure, in association with a liquid foliar biofertilizer. These crops

Débora Cabral Machado; Carla Marques Maia; Isabel Dias Carvalho; Natan Fontoura da Silva; Maria Cláudia Dantas Porfírio Borge André; Álvaro Bisol Serafini

2006-01-01

254

Post-fire spatial patterns of soil nitrogen mineralization and microbial abundance.  

PubMed

Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R²<0.29). Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21(st) Century. PMID:23226324

Smithwick, Erica A H; Naithani, Kusum J; Balser, Teri C; Romme, William H; Turner, Monica G

2012-01-01

255

Post-Fire Spatial Patterns of Soil Nitrogen Mineralization and Microbial Abundance  

PubMed Central

Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R2<0.29). Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21st Century. PMID:23226324

Smithwick, Erica A. H.; Naithani, Kusum J.; Balser, Teri C.; Romme, William H.; Turner, Monica G.

2012-01-01

256

Impact of soil primary size fractions on sorption and desorption of atrazine on organo-mineral fractions.  

PubMed

In the current study, a mechanical dispersion method was employed to separate clay (<2 ?m), silt (2-20 ?m), and sand (20-50 ?m) fraction in six bulk soils. Batch equilibrium method was used to conduct atrazine sorption and desorption experiments on soil organo-mineral fractions with bulk soils and their contrasting size fractions separately. The potential contribution of total organic carbon (TOC) for atrazine retention in different fractions was further investigated. It was found that clay fraction had the highest adsorption but the least desorption capacities for atrazine, while sand fraction had the lowest adsorption but the highest desorption capacities for atrazine. The adsorption percentage of atrazine, as compared with adsorption by the corresponding bulk soils, ranged from 53.6 to 80.5 %, 35.7 to 56.4 %, and 0.2 to 4.5 % on the clay, silt, and sand fractions, respectively. TOC was one of the key factors affecting atrazine retention in soils, with the exact contribution dependent on varying degree of coating with mineral component in different soil size fractions. The current study may be useful to predict the bioavailability of atrazine in different soil size fractions. PMID:25300187

Huang, Yufen; Liu, Zhongzhen; He, Yan; Li, Yanliang

2014-10-11

257

The effects of fulvic acids extracted from soils on the mineralization of pyrene by an isolated Mycobacterium sp.  

SciTech Connect

The degradation of many hazardous compounds in soils can be affected by soil chemical constituents as well as the populations of degrading organisms present. Fulvic acids were extracted from various soils and used to determine their effects on pyrene mineralization by an isolated pyrene-degrading Mycobacterium sp. Mineralization was measured using serum bottle radiorespirometry. Samples were prepared using sterile sand with different concentrations of fulvic acids made into a slurry using sterile deionized distilled water which included added Mycobacterium cells. Mineralization was measured over a 16-day period. Results show that the addition of fulvic acids from nonimpacted soil, at all concentrations, produced significantly higher levels of mineralization compared to the impacted fulvic acids. Adjusting the pH to 7.0 had no effect on the extent of mineralization of pyrene. Because the addition of fulvic acids to the slurries decreases the pH, survival studies were conducted at unadjusted pH and at pH adjusted to 7, and with varying concentrations of added fulvic acids. Activity of the Mycobacterium cells was measured as {sup 14}C-acetate incorporation into lipids and biomass was measured as lipid phosphate concentration. In general, biomass measurements decreased with increasing levels of fulvic acid added. Activity measurements showed that only the 1% fulvic acid addition in the nonimpacted samples and the 1 and 5% additions in the impacted samples displayed measurable activity. The decreasing mineralization of pyrene with increasing levels of fulvic acid addition appears to be due to toxicity to the microbes and possible sorption of the compound making it less bioavailable.

Grosser, R.J.; Warshawsky, D.; Kinkle, B.K. [Univ. of Cincinnati, OH (United States)

1994-12-31

258

Mineralization of organic matter with warming in boreal forest soils is influenced by nitrogen dynamics  

NASA Astrophysics Data System (ADS)

Temperature is an important factor in regulating soil organic matter (SOM) decomposition, but the drivers of microbial substrate choice with changing temperature regimes remain poorly elucidated. For example, nitrogen (N) dynamics play a key role in dictating activity levels of different microbial groupings, which in turn may influence who in a microbial community is better able to take advantage of more favorable energetics in a warmer soil profile. These issues are particularly important for large SOM reservoirs, such as those in the boreal biome. To address these issues, we collected soils in organic horizons from two forested sites along the Newfoundland-Labrador Boreal Ecosystem Latitude Transect (NL-BELT) in eastern Canada. Sites differ in latitude and mean annual temperature, but are similar in forest cover and soil type. We incubated humified Oe+Oa materials and replaced Oi with low or high C:N coniferous litter possessing a distinct ?13C signature for 120 days at 15°C and 20°C. During the incubation, we assessed respiratory CO2 losses and its origin via ?13C of CO2, microbial biomass, and the activity of multiple exo-enzymes associated with the mineralization of slow-turnover and more labile substrates. As predicted by enzyme kinetics, warming positively influenced respiratory loss and the proportion of CO2 derived from more humified SOM, particularly in late stages of the incubation. We observed no interaction effect of warming and Oi C:N on respired CO2 or microbial biomass C or N in soil from either site. Oi C:N influenced respiratory loss from higher latitude soils, with lower C:N Oi input dampening respiration rates early in the incubation, and promoting it at later stages. Late in the incubation, when the positive effect of warming on CO2 release from more humified SOM was most pronounced, the warming-induced increase in phenol oxidase activity was further enhanced when Oi material had a relatively low C:N by factors of 1.87 and 17 for lower vs. higher latitude soils, respectively. Overall, these results indicate that the C:N of inputs to the O horizon such as the Oi sub-horizon can exert a quantifiable influence on CO2 efflux rates in some boreal soils. That we observed a general effect of Oi C:N on the activity of an enzyme linked to decay of relatively slow-turnover SOM suggests that Oi C:N can serve as a driver of microbial substrate choices, such that the relatively greater influence of warming on humified SOM decay is magnified by increased organic N availability. These results highlight the potentially positive feedbacks to warming that may result in boreal soil systems, as well as the important role that N plays in dictating microbial responses to climate warming.

Li, J.; Ziegler, S. E.; Lane, C. S.; Billings, S. A.

2011-12-01

259

Mineral cycling in soil and litter arthropod food chains. Progress report, November 1, 1980-October 31, 1981  

SciTech Connect

Progress and current status are reported for research projects concerned with mineral element and nutrient dynamics in soil arthropod food chains. Research is performed within the larger context of terrestrial decomposition, in which soil arthropods may act as regulators of nutrient dynamics during decomposition. Research is measuring rates of nutrient accumulation and excretion by using radioactive tracer analogs of nutrients. This year, emphasis has been placed on field work in which soil arthropod population size and nutrients inputs were varied experimentally. The presence of microarthropods in field microcosms increased the mineralization of N and P in each case, but rates were not correlated with arthropod densities. Experiments recently started are using both arthropod and microfloral inhibitors, in open systems on the forest floor, with the objective of quantifying arthropod enhancement of microbial immobilization of nutrients.

Crossley, D.A. Jr.

1980-06-15

260

Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media  

USGS Publications Warehouse

The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons, are included here in the AGDB and will be added to the NGDB. The AGDB data provided here are the most accurate and complete to date, and should be useful for a wide variety of geochemical studies. The AGDB data provided in the linked database may be updated or changed periodically. The data on the DVD and in the data downloads provided with this report are current as of date of publication.

Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

2011-01-01

261

How biological crusts are stabilizing the soil surface? The devolpment of organo-mineral interactions in the initial phase  

NASA Astrophysics Data System (ADS)

First colonizers of new land surfaces are cryptogames which often form biological soil crusts (BSC) covering the first millimetre of the top soil in many ecosystems from polar to desert ecosystems. These BSC are assemblages of cyanobacteria, green algae, mosses, liverworts, fungi and/or lichens. The development of soil surface crusts plays a major role for the further vegetation pattern through changes to the physico-chemical conditions and influencing various ecosystem processes. We studied the development of BSC on quaternary substrate of an initial artificial water catchment in Lusatia, Germany. Due to lack of organic matter in the geological substrate, photoautotrophic organisms like green algae and cyanobacteria dominated the initial phases of ecosystem development and, hence, of organo-mineral ineractions. We combined SEM/EDX and FTIR microscopy to study the contact zone of extracellular polymeric substances (EPS) of green algae and cyanobacteria with quartz, spars and mica on a >40 µm scale in undisturbed biological soil crusts, which had a maximum thickness of approx. 2 mm. SEM/EDX microscopy was used to determine the spatial distribution of S, Ca, Fe, Al, Si and K in the profiles, organic compounds were identified using FTIR microscopy. Exudates of crust organisms served as cementing material between sand particles. The crust could be subdivided into two horizontal layers. The upper layer, which had a thickness of approx. 200 µm, is characterized by accumulation of Al and K, but absence of Fe in microbial derived organic matter, indicating capture of weathering products of feldspars and mica by microbial exudates. The pore space between mineral particles was entirely filled with organic matter here. The underlying layer can be characterized by empty pores and organo-mineral bridges between the sand particles. Contrarily to the upper layer of the crust, Fe, Al and Si were associated with organic matter here but K was absent. Highest similarity of the FTIR spectra of EPS was observed with carbohydrates, using cellulose, dextran and humic acid Na salt as controls. Obviously, humification does not play a key role during this initial phase of soil formation. It was hypothesized that biological soil crusts facilitate the weathering of mineral substrate by (I) circumventing loss of fine particles with erosion, (II) by chemical treatment of minerals and (III) by catching small mineral-particles by glutinous EPS on the soil surface from the surrounding area.

Fischer, T.; Veste, M.; Wiehe, W.; Lange, P.

2009-04-01

262

Increased physical protection of soil carbon in the mineral soil of a poplar plantation after five years of free atmospheric CO2 enrichment (FACE)  

NASA Astrophysics Data System (ADS)

Free air CO2 enrichment (FACE) experiments in aggrading forests and plantations have demonstrated significant increases in net primary production (NPP) and C storage in forest vegetation. The extra C uptake may also be stored in forest floor litter and in forest soil. After five years of FACE treatment at the EuroFACE short rotation poplar plantation, the increase of total soil C% was larger under elevated than under ambient CO2. However, the fate of this additional C allocated belowground remains unclear. The stability of soil organic matter is controlled by the chemical structure of the organic matter and the existence of protection offered by the soil matrix and minerals. Fresh litter entering the soil enhances microbial activity which induces the binding of organic matter and soil particles into macro-aggregates. As the enclosed organic matter is decomposed, microbial and decomposition products become associated with mineral particles. This association results in the formation of micro-aggregates (within macro-aggregates) in which organic matter is stabilized and protected. FACE and N-fertilization treatment did not affect the micro- and macro-aggregate weight, C or N fractions obtained by wet sieving. However, Populus euramericana increased the micro- and small macro-aggregates weight and C fractions. The obtained macro-aggregates were broken up in order to isolate recently formed micro-aggregates within macro-aggregates (iM-micro-aggregates). FACE increased the iM-micro-aggregate weight and C fractions. This study reveals that: 1) Species has an effect on the formation of macro-aggregates. The choice of species in a plantation or the effect of global change on species diversity, may therefore affect the stabilization and protection of soil C in aggregates. And 2) Increased atmospheric CO2 concentration increases the stabilization and protection of soil C in micro-aggregates formed within macro-aggregates. This mechanism increases the C sink of forest soils under increasing atmospheric CO2 concentration.

Hoosbeek, M. R.; Vos, J. M.; Scarascia-Mugnozza, G. E.

2006-07-01

263

Anatomical characteristics of individual roots within the fine-root architecture of Chamaecyparis obtusa (Sieb. & Zucc.) in organic and mineral soil layers  

Microsoft Academic Search

Nutrient availability and temporal variation of physical stress are usually higher in organic soil layers than in mineral soils. Individual roots within the fine-root system adjust anatomical, morphological, and turnover characteristics to soil conditions, for example nutrient availability and physical stresses. We investigated anatomical traits, including cork formation and passage and protoxylem cell numbers, in cross-sections of individual fine roots

Takuo Hishi; Ryunosuke Tateno; Hiroshi Takeda

2006-01-01

264

Recent (<4 year old) Leaf Litter is Not a Major Source of Microbial Carbon in a Temperate Forest Mineral Soil  

SciTech Connect

Microbial communities in soil A horizons derive their carbon from several potential sources: organic carbon (C) transported down from overlying litter and organic horizons, root-derived C, or soil organic matter. We took advantage of a multi-year experiment that manipulated the {sup 14}C isotope signature of surface leaf litter inputs in a temperate forest at the Oak Ridge Reservation, Tennessee, USA, to quantify the contribution of recent leaf litter C to microbial respiration and biomarkers in the underlying mineral soil. We observed no measurable difference (< {approx}40{per_thousand} given our current analytical methods) in the radiocarbon signatures of microbial phospholipid fatty acids (PLFA) isolated from the top 10 cm of mineral soil in plots that experienced 3 years of litterfall that differed in each year by {approx}750{per_thousand} between high-{sup 14}C and low-{sup 14}C treatments. Assuming any difference in {sup 14}C between the high- and low-{sup 14}C plots would reflect C derived from these manipulated litter additions, we estimate that <6% of the microbial C after 4 years was derived from the added 1-4-year-old surface litter. Large contributions of C from litter < 1 year (or >4 years) old (which fell after (or prior to) the manipulation and therefore did not differ between plots) are not supported because the {sup 14}C signatures of the PLFA compounds (averaging 200-220{per_thousand}) is much higher that of the 2004-5 leaf litter (115{per_thousand}) or pre-2000 litter. A mesocosm experiment further demonstrated that C leached from {sup 14}C-enriched surface litter or the O horizon was not a detectable C source in underlying mineral soil microbes during the first eight months after litter addition. Instead a decline in the {sup 14}C of PLFA over the mesocosm experiment likely reflected the loss of a pre-existing substrate not associated with added leaf litter. Measured PLFA {Delta}{sup 14}C signatures were higher than those measured in bulk mineral soil organic matter in our experiments, but fell within the range of {sup 14}C values measured in mineral soil roots. Together, our experiments suggest that root-derived C is the major (>60%) source of C for microbes in these temperate deciduous forest soils.

Kramer, Christiane [University of California, Irvine; Trumbore, Susan E. [University of California, Irvine; Froberg, Mats J. [Sveriges Lantbruksuniversitet; Cisneros dozal, Luz Maria [Los Alamos National Laboratory (LANL); Zhang, Dachun [University of California, Irvine; Xu, Xiamei [University of California, Irvine; Santos, Guaciara [University of California, Irvine; Hanson, Paul J [ORNL

2010-01-01

265

Integrating microbial physiology and physiochemical principles in soils with the MIcrobial-MIneral Carbon Stabilization (MIMICS) model  

NASA Astrophysics Data System (ADS)

Previous modeling efforts document divergent responses of microbial explicit soil biogeochemistry models when compared to traditional models that implicitly simulate microbial activity, particularly following environmental perturbations. However, microbial models are needed that capture current soil biogeochemical theories emphasizing the relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model. In MIMICS, the turnover of litter and SOM pools are governed by temperature sensitive Michaelis-Menten kinetics and the activity of two physiologically distinct microbial functional types. The production of microbial residues through microbial turnover provides inputs to SOM pools that are considered physically or chemically protected. Soil clay content determines the physical protection of SOM in different soil environments. MIMICS adequately simulates the mean rate of leaf litter decomposition observed at a temperate and boreal forest sites, and captures observed effects of litter quality on decomposition rates. Initial results from MIMICS suggest that soil C storage can be maximized in sandy soils with low-quality litter inputs, whereas high-quality litter inputs may maximize SOM accumulation in finely textured soils that physically stabilize microbial products. Assumptions in MIMICS about the degree to which microbial functional types differ in the production, turnover, and stabilization of microbial residues provides a~mechanism by which microbial communities may influence SOM dynamics in mineral soils. Although further analyses are needed to validate model results, MIMICS allows us to begin exploring theoretical interactions between substrate quality, microbial community abundance, and the formation of stable SOM.

Wieder, W. R.; Grandy, A. S.; Kallenbach, C. M.; Bonan, G. B.

2014-01-01

266

Quantification of the effects of various soil fumigation treatments on nitrogen mineralization and nitrification in laboratory incubation and field studies.  

PubMed

Better quantification of nitrogen mineralization and nitrification after fumigation would indicate if any adjustment is needed in fertilizer application. The effects of chloropicrin (Pic), 1,3-dichloropropene (1,3-D), dimethyl disulfide (DMDS) and metham sodium (MS) fumigation on soil nitrogen dynamics were evaluated in lab incubation and field studies. Although some differences were observed in NH(4)(+)-N and NO(3)(-)-N concentrations in lab incubation and field experiments, both studies led to the same conclusions: (1) Soil fumigation was shown to increase soil mineral nitrogen only during the first 2 weeks after fumigation (WAF). In particular, Pic significantly increased soil mineral nitrogen in both studies at 1 WAF. However, for all fumigant treatments the observed effect was temporary; the soil mineral content of treated samples recovered to the general level observed in the untreated control. (2) All the fumigation treatments depressed nitrification temporarily, although the treatments exhibited significant differences in the duration of nitrification inhibition. In both studies, for a limited period of time, Pic showed a stronger inhibitory effect on nitrification compared to other fumigant treatments. An S-shaped function was fitted to the concentrations of NO(3)(-)-N in lab incubation samples. The times of maximum nitrification (t(max)) in DMDS and MS treatments were 0.97 week and 1.03 week, which is similar to the untreated control (t(max)=1.02 week). While Pic has the longest effect on nitrifying bacteria, nitrification appears to restart at a later time (t(max)=14.37 week). PMID:23062947

Yan, Dongdong; Wang, Qiuxia; Mao, Liangang; Li, Wei; Xie, Hongwei; Guo, Meixia; Cao, Aocheng

2013-01-01

267

Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil.  

PubMed

Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3. JR7B3 was able to metabolize 2,4,5-T as the sole source of carbon and energy, and demonstrated the ability to affect metabolism of 2,4-D to a lesser degree. Strain JR7B3 was able to mineralize 2,4,5-T in pure culture and utilized 2,4,5-T in the presence of 0.01% yeast extract. Subsequent characterization of the 2,4-D degrading culture showed that one bacterium, Burkholderia species strain JRB1, was able to utilize 2,4-D as a sole carbon and energy source in pure culture. Polymerase chain reaction (PCR) experiments utilizing known genetic sequences from other 2,4-D and 2,4,5-T degrading bacteria demonstrated that these organisms contain gene sequences similar to tfdA, B, C, E, and R (Strain JRB1) and the tftA, C, and E genes (Strain JR7B3). Expression analysis confirmed that tftA, C, and E and tfdA, B, and C were transcribed during 2,4,5-T and 2,4-D dependent growth, respectively. The results indicate a strong selective pressure for 2,4,5-T utilizing strains under field condition. PMID:15865343

Rice, J F; Menn, F M; Hay, A G; Sanseverino, J; Sayler, G S

2005-12-01

268

Computer simulation of the distribution of aluminum speciation in soil solutions in equilibrium with the mineral phase imogolite.  

PubMed

The speciation of aluminum (Al) is a critical issue when evaluating the environmental and biological significance of elevated Al concentrations in soil solutions caused by acidic precipitation. Numerous studies have revealed that, with increased concentrations of silica acid in soil, the activity of Al species in soil solutions is greatly modified by SiO(4)(2-). However, thus far there has been little thorough theoretical modeling of this subject. This paper reports a computer simulation of the distribution of Al speciation in soil solutions in equilibrium with the mineral phase imogolite based on a chemical equilibrium calculation. The unique characteristic associated with imogolite reported by previous researchers can be explained theoretically by the proposed model. The dissolved silica has a remarkable influence on Al speciation: increasing concentrations of silica acid may effectively inhibit the formation of polymeric alumino-hydroxo species, and, furthermore, detoxify Al toxicity to plants. PMID:11709218

Bi, S; An, S; Tang, W; Xue, R; Wen, L; Liu, F

2001-11-01

269

Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals  

NASA Astrophysics Data System (ADS)

In isotope-enabled hydrology, soil and vadose zone sediments have been generally considered to be isotopically inert with respect to the water they host. This is inconsistent with knowledge that clay particles possessing an electronegative surface charge and resulting cation exchange capacity (CEC) interact with a wide range of solutes which, in the absence of clays, have been shown to exhibit ?18O isotope effects that vary in relation to the ionic strength of the solutions. To investigate the isotope effects caused by high CEC clays in mineral-water systems, we created a series of monominerallic-water mixtures at gravimetric water contents ranging from 5% to 32%, consisting of pure deionized water of known isotopic composition with homoionic (Mg, Ca, Na, K) montmorillonite. Similar mixtures were also created with quartz to determine the isotope effect of non-, or very minimally-, charged mineral surfaces. The ?18O value of the water in these monominerallic soil analogs was then measured by isotope ratio mass spectrometry (IRMS) after direct headspace CO2 equilibration. Mg- and Ca-exchanged homoionic montmorillonite depleted measured ?18O values up to 1.55‰ relative to pure water at 5% water content, declining to 0.49‰ depletion at 30% water content. K-montmorillonite enriched measured ?18O values up to 0.86‰ at 5% water content, declining to 0.11‰ enrichment at 30% water. Na-montmorillonite produces no measureable isotope effect. The isotope effects observed in these experiments may be present in natural, high-clay soils and sediments. These findings have relevance to the interpretation of results of direct CO2-water equilibration approaches to the measurement of the ?18O value of soil water. The adsorbed cation isotope effect may bear consideration in studies of pedogenic carbonate, plant-soil water use and soil-atmosphere interaction. Finally, the observed isotope effects may prove useful as molecular scale probes of the nature of mineral-water interactions.

Oerter, Erik; Finstad, Kari; Schaefer, Justin; Goldsmith, Gregory R.; Dawson, Todd; Amundson, Ronald

2014-07-01

270

Clay minerals in chernozem-like soils of mesodepressions in the northern forest-steppe of European Russia  

NASA Astrophysics Data System (ADS)

In the northern forest-steppe of European Russia, under the conditions of surface waterlogging (freshwater) and a stagnant-percolative regime, gleyic podzolic chernozem-like soils with thick light-colored eluvial horizons are formed. These horizons are close or similar to the podzolic horizons of bog-podzolic soils in many properties of their solid phase. They are bleached in color and characterized by the removal of Ca, Mg, Fe, Al, and Mn and the relative accumulation of quartz SiO2. These soils differ from leached chernozems in their acid reaction and very low CEC, the presence of Fe-Mn concretions and coatings, and the significant decrease in the clay content in the A2 horizon as compared to the parent rock. The soils studied differ significantly from loamy podzolic and bog-podzolic soils by the composition of the clay minerals in the A2 horizons: (1) no essential loss of smectite minerals from this horizon was found as compared to the rest of the solum, (2) pedogenic chlorites (HIV and HIS) are absent, and (3) the distinct accumulation of illites is observed as compared to the subsoil and parent material, probably, due to the process of illitization.

Sokolova, T. A.; Zaidel'Man, F. R.; Ginzburg, T. M.

2010-01-01

271

Microbe-driven turnover offsets mineral-mediated storage of soil carbon under elevated CO2  

NASA Astrophysics Data System (ADS)

The sensitivity of soil organic carbon (SOC) to changing environmental conditions represents a critical uncertainty in coupled carbon cycle-climate models. Much of this uncertainty arises from our limited understanding of the extent to which root-microbe interactions induce SOC losses (through accelerated decomposition or `priming') or indirectly promote SOC gains (via `protection' through interactions with mineral particles). We developed a new SOC model to examine priming and protection responses to rising atmospheric CO2. The model captured disparate SOC responses at two temperate free-air CO2 enrichment (FACE) experiments. We show that stabilization of `new' carbon in protected SOC pools may equal or exceed microbial priming of `old' SOC in ecosystems with readily decomposable litter and high clay content (for example, Oak Ridge). In contrast, carbon losses induced through priming dominate the net SOC response in ecosystems with more resistant litters and lower clay content (for example, Duke). The SOC model was fully integrated into a global terrestrial carbon cycle model to run global simulations of elevated CO2 effects. Although protected carbon provides an important constraint on priming effects, priming nonetheless reduced SOC storage in the majority of terrestrial areas, partially counterbalancing SOC gains from enhanced ecosystem productivity.

Sulman, Benjamin N.; Phillips, Richard P.; Oishi, A. Christopher; Shevliakova, Elena; Pacala, Stephen W.

2014-12-01

272

Mineral cycling in soil and litter arthropod food chains. Three-year progress report, February 1, 1984-January 31, 1987  

SciTech Connect

This report summarizes progress in a three-year research project on the influence of soil arthropods (mites, collembolans, insects, millipedes and others) upon decomposition rates and nutrient dynamics in decaying vegetable matter. Research has concentrated on two aspects of elemental dynamics in decomposing organic matter: Effects of arthropods on rates of decomposition and nutrient loss (mineralization of carbon and other elements), and arthropod stimulation of microbial immobilization of nutrient elements during decomposition.

Crossley, D.A. Jr.

1986-08-29

273

Enhanced Mineralization of [U-14C]2,4-Dichlorophenoxyacetic Acid in Soil from the Rhizosphere of Trifolium pratense  

Microsoft Academic Search

Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on com- pounds produced by rhizodeposition. We monitored the mineralization of (U-14C)2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history

Liz J. Shaw; Richard G. Burns

2004-01-01

274

Mineralization and conversion of pentachlorophenol (PCP) in soil inoculated with the white-rot fungus Trametes versicolor  

Microsoft Academic Search

The fate of pentachlorophenol (PCP) in autoclaved soil supplemented with straw and inoculated with the white-rot fungus Trametes versicolor was investigated. Inoculated flasks were incubated for 0 to 42d and control flasks for 0 to 28d. Mineralization and volatilization of PCP and its transformation products were measured using 14C-labelled PCP for radiorespirometry and extraction analysis, and non-labelled PCP to monitor

Marja Tuomela; Merja Lyytikäinen; Pekka Oivanen; Annele Hatakka

1998-01-01

275

Comparison of Mineralization and Distribution of Soil Sulfur Fractions in the Rhizosphere of Oilseed Rape and Rice  

Microsoft Academic Search

The effect of plant growth on the mineralization and distribution of soil sulfur (S) fractions (soluble adsorbed ester-bonded S, carbon-bonded S and residual S) in the rhizosphere of oilseed rape and rice was studied in a greenhouse experiment using a rhizobag technique. Significant differences of sulfur fractions between the rhizosphere and the non-rhizosphere were determined in dependence on crop type.

Zhengyi Hu; Silvia Haneklaus; Shiping Wang; Chengkai Xu; Zhihong Cao; Ewald Schnug

2003-01-01

276

Integrating microbial physiology and physio-chemical principles in soils with the MIcrobial-MIneral Carbon Stabilization (MIMICS) model  

NASA Astrophysics Data System (ADS)

A growing body of literature documents the pressing need to develop soil biogeochemistry models that more accurately reflect contemporary understanding of soil processes and better capture soil carbon (C) responses to environmental perturbations. Models that explicitly represent microbial activity offer inroads to improve representations of soil biogeochemical processes, but have yet to consider relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations, we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, and evaluate it by comparing site-level soil C projections with observations from a long-term litter decomposition study and soil warming experiment. In MIMICS, the turnover of litter and SOM pools is governed by temperature-sensitive Michaelis-Menten kinetics and the activity of two physiologically distinct microbial functional types. The production of microbial residues through microbial turnover provides inputs to SOM pools that are considered physically or chemically protected. Soil clay content determines the physical protection of SOM in different soil environments. MIMICS adequately simulates the mean rate of leaf litter decomposition observed at temperate and boreal forest sites, and captures observed effects of litter quality on decomposition rates. Moreover, MIMICS better captures the response of SOM pools to experimental warming, with rapid SOM losses but declining temperature sensitivity to long-term warming, compared with a more conventional model structure. MIMICS incorporates current microbial theory to explore the mechanisms by which litter C is converted to stable SOM, and to improve predictions of soil C responses to environmental change.

Wieder, W. R.; Grandy, A. S.; Kallenbach, C. M.; Bonan, G. B.

2014-07-01

277

Crop rotations with annual and perennial forages under no-till soil management: soil attributes, soybean mineral nutrition, and yield  

Technology Transfer Automated Retrieval System (TEKTRAN)

Extensive use of sustainable crop and soil management systems would result in profitable farms producing greater yields while maintaining or enhancing natural resources. Development of sustainable agricultural systems depends on understanding complex relationships between soil management, crop mana...

278

Carbon Sequestration and Nitrogen Mineralization in Soil Cooperated with Organic Composts and Bio-char During Corn (Zea mays) Cultivation  

NASA Astrophysics Data System (ADS)

Objectives of this study were to estimate the carbon sequestration and to evaluate nitrogen mineralization and nitrification in soils cooperated with organic composts and bio-char during corn cultivation. For the experiment, the soil used in this study was clay loam types, and application rates of chemical fertilizer and bio-char were recommended amount after soil test and 2 % to soil weight, respectively. The soil samples were periodically taken at every 15 day intervals during the experimental periods. The treatments were consisted of non-application, cow manure compost, pig manure compost, swine digestate from aerobic digestion system, their bio-char cooperation. For the experimental results, residual amount of inorganic carbon was ranged from 51 to 208kg 10a-1 in soil only cooperated with different organic composts. However it was estimated to be highest at 208kg 10a-1 in the application plot of pig manure compost. In addition to bio-char application, it was ranged from 187.8 to 286kg 10a-1, but was greatest accumulated at 160.3kg 10a-1 in the application plot of cow manure compost. For nitrogen mineralization and nitrification rates, it was shown that there were generally low in the soil cooperated with bio-char compared to the only application plots of different organic composts except for 71 days after sowing. Also, they were observed to be highest in the application plot of swine digestate from aerobic digestion system. For the loss of total inorganic carbon (TIC) by run-off water, it was ranged from 0.18 to 0.36 kg 10a-1 in the different treatment plots. Also, with application of bio-char, total nitrogen was estimated to be reduced at 0.42(15.1%) and 0.38(11.8%) kg 10a-1 in application plots of the pig manure compost and aerobic digestate, respectively.

Shin, Joung-Du; Lee, Sun-Ill; Park, Wu-Gyun; Choi, Yong-Su; Hong, Seong-Gil; Park, Sang-Won

2014-05-01

279

Development and application of a soil organic matter based soil quality index in mineralized terrane of the Western US  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil’s ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, we set out to develop and apply an index using the relation between so...

280

Effects of multi-walled carbon nanotubes on mineralization and mobility of nonylphenol and sodium dodecyl sulfate in agricultural soils  

NASA Astrophysics Data System (ADS)

Nanotechnology is one of the major scientific research fields in this decade. One of the most wide-spread nanomaterials are carbon based nanoparticles (CNPs) which are increasingly be used in industry. Several studies shows that CNPs are interacting with other chemical compounds and organic pollutants in the environment. It is assumed that the interactions between CNPs and organic pollutants are affected by solution and aggregate behavior. Based on the knowledge of the behavior of CNPs and organic pollutants in aquatic systems the interactions of CNPs and organic pollutants in agricultural soils have to be studied. As organic pollutants two environmental substances, nonylphenol (NP) and sodium dodecyl sulfate (SDS) were selected as model substances. They occur frequently in aqueous systems and also show different solubility behavior. As CNP representatives, two different multi-walled carbon nanotubes (MWNT) were selected. They differed either in length or outer diameter. Conclusions therefrom are to be closed the influence of length and diameter of the sorption capacity of different organic pollutants. In addition, two agricultural soils (sandy and silty soil) and one forest soil (sandy soil) were chosen. Mineralization and sorption experiments were conducted to provide information about the degradation of organic pollutants in presence of multi-walled carbon nanotubes in soils. To analyze the CNPs mineralization potential, peroxidase activity was measured. Further extraction experiments were conducted to detect the extractable part of organic pollutants. The results show that the surface area of the MWNT has a significant impact on the sorption behav-ior of NP and SDS in soils. The sorption of NP and SDS is much higher than without MWNT. However, the properties of the organic pollutants (different water solubility and hydrophobicity) are equally important and should be noted. The degradation of both pollutants is influenced by MWNT. Due to the strong sorption of NP and SDS on the MWNT, the degradation of these pollutants in soils, is slower than without MWNT. The peroxidase activity did not contribute to NP and SDS degradation. But the peroxidase activity in agricultural soils is higher than in forest soils. The extractable fraction of NP and SDS is very low and amounts to a maximum of 2 %. Due to the lower degradation of NP and SDS in the presence of MWNT a longer retention of the substances in the soils and potential toxic effects for humans and animals, as a result of plant uptake may be taken into account.

Lillotte, Julia; Marschner, Bernd; Stumpe, Britta

2014-05-01

281

Magnetic minerals: Understanding the processes of formation in soils and clays and identifying their presence in the rock record  

NASA Astrophysics Data System (ADS)

Magnetic minerals can form authigenically in soils and sediments, but the processes involved can be complex and are often a matter of debate. For example, anomalous concentrations in magnetic minerals have been described in soils and their origin has been ascribed to a range of processes including inorganic and biological precipitation. Also, the presence of secondary magnetic minerals in sedimentary rocks has been described and their origin has been related to a variety of geologic processes such as orogenic fluid migration, presence of hydrocarbons, and clay diagenesis. Developing a better understanding for the conditions by which magnetic minerals form in soils and sediments is important because of the information they can provide to decipher the geologic past on Earth and potentially on other planets. This work presents results of biological formation of magnetite under a variety of laboratory conditions in a hydrocarbon-contaminated soil profile. Magnetite was formed only in biological samples but not in the abiotic: counterparts suggesting biological processes may be more important in the formation of magnetic minerals in soils than previously thought. A study on naturally occurring clays heated to temperatures equivalent to low burial conditions (62 and 98°C) resulted in increases in the bulk magnetic susceptibility (chib) in some smectites but not in any of the other tested clays. Furthermore, a closer look was taken at heated smectites and the authigenic magnetic grains that were formed in the process were rock magnetically characterized. The findings suggest that clay diagenetic processes occurring at low temperatures can lead to the formation of magnetite capable of carrying remanence and thus, provide a viable mechanism for the acquisition of secondary magnetizations in sedimentary rocks. Lastly, a rock magnetic comparison of two Paleozoic loessite-paleosol couplets is presented to investigate whether the enhanced chi b trends in the paleosols as compared to the loessite can be confirmed in ancient deposits. The results for one couplet are similar to those from the Chinese Loess Plateau, which have an enrichment of ferrimagnetic material in the paleosol. The second couplet, however, reveals that the variations in the chib can be more complex and shows the importance of combining rock magnetic with sedimentologic evidence in order to identify the origin and preservation of chib patterns in geologic deposits.

Cogoini, Monika

282

Mineral content of grasses and grasslands of the Himalayan region: 1. Trace element distribution in soil profiles and their concentrations in surface soils  

SciTech Connect

Researchers analyzed soil samples, collected from naturally occurring grasslands of the Himalayan region, to investigate trace element distribution in soil profiles and their concentrations in surface soils, as well as to examine frequency and geographical distribution of low and high levels of trace elements. Both chemical and radiochemical analytical techniques were employed to determine the trace elements. This study was part of a research project on the evaluation of mineral content of natural grasslands and grasses and the relationship between the mineral contents in grasses and grasslands. Little or no variation in the content of total Zn, Mn, Cu, Cd, Ni, Pb, Co, and I from surface to subsurface horizons in the soil profiles was observed. However, the concentrations of extractable Zn, Mn, Cu, and B in the surface horizons were higher than in the subsurface horizons. The variations among the profiles were primarily related to the geological material from which the soils derived. Means and ranges of trace elements are given for particular locations and for the whole sample area. Concentrations of most of the trace elements varied greatly among sites at the same location and among locations. There were highly significant correlations between the contents of trace elements, especially total Zn and Mn, and extractable Zn, Fe, Ni, Co, B, and I, and the soil chemical properties, elevation, rainfall, and temperature. Rainfall and temperature showed negative correlations for almost all the trace elements. A number of the trace elements were interrelated in their geochemical origin. On the basis of the critical levels suggested for trace element deficiencies, proportions of the samples that may be considered deficient were about 28% for Zn, 50% for Mn, 20-30% for Cu, 4% for Fe, 56-87% for B, 77% for Mo, and 5-10% for Co.

Singh, B.R.; Mishra, V.K.; Tripathi, B.R.

1987-03-01

283

Thermally induced changes in metal solubility of contaminated soils is linked to mineral recrystallization and organic matter transformations.  

PubMed

Soils are biogeochemical systems under continual modification by biological and chemical processes. Trace element solid-solution partitioning is thus influenced by long-term changes to these solid phases. We study Pb, Cd, Zn, and Cu solution speciation and solid-phase dynamics in two soils of volcanic origin (Te Akatea and Egmont, high in noncrystalline aluminosilicates), an oxisol from Brazil (Oxisol, high in oxides of Al and Fe), and several sludge-treated soils (labeled NYS soils, high in organic materials). Total soluble (by ICP) and labile (by ASV) concentrations of Pb, Cd, Zn, and Cu were determined after incubation of the soils for about 1.5 yr at room (23 degrees C) and elevated (70 degrees C) temperatures. Changes occurring to the solid phases were monitored by FTIR and extraction with oxalate and pyrophosphate. It is shown that induced hydrolysis or decomposition of organic materials in soils results in increases in both labile and total soluble concentrations of Pb, Cd, Cu, and Zn in solution. Labile and total soluble concentrations of Cu and Zn increase concomitantly with dissolved organic carbon (DOC); the nonlabile soluble fraction also increases with increasing DOC. Similarly, the concentration of Cd and Pb in solution increases with increasing DOC; however, most soluble Cd and Pb is asv-labile. Only in the Egmont soil (mineralogy dominated by proto-imogolite allophane) was reduced Pb solubility observed after prolonged equilibration and heating. Lead solubility increased after partial crystallization of amorphous minerals in the Te Akatea and the Oxisol. Thus, for most of the metal-soil systems studied, prolonged thermal treatment at 70 degrees C increased total soluble and asv-labile metals, suggesting that aging effects on metals in contaminated soils could release metals to labile forms in some cases. PMID:11351534

Martínez, C E; Jacobson, A; McBride, M B

2001-03-01

284

Influence of soil C stocks and interannual climatic variability on the CO2 and CH4 exchange of maize cultivated on mineral and organic soils in NE Germany  

NASA Astrophysics Data System (ADS)

Due to its glacially influenced genesis and land use history, the soils of the Great Plain Region of NE-Germany show large differences in groundwater levels and soil carbon (C) stocks over short distances. Although generally featuring a rather dry climate, trace gas exchange at individual sites may be influenced by i) interannual climatic variability, particularly with respect to precipitation; as well as by ii) variability of soil C stocks. However, it is still unclear how these factors affect fluxes of CO2 and CH4, and if there is any positive or negative feedback on the C source or sink function of different soil types. We present measured and modeled CO2 and CH4 fluxes of minerally fertilized grain maize for three sites located near Paulinenaue, within the so-called Rhin-Havelluch, a shallow and drained paludification mire complex in NE Germany. The sites are characterized by a distinct gradient of 0-1 m soil organic C stocks: i) Arenosol (AR: mineral soil/distant groundwater; 8 000 g C m-2), ii) Gleysol (GL: organic soil/groundwater-dependent; 35 000 g C m-2), and iii) Histosol (HS: organic soil/near groundwater; 45 000 g C m-2). CO2 flux measurements of ecosystem respiration (Reco), net ecosystem exchange (NEE) and gross primary production (GPP; calculated as difference between NEE and Reco) were conducted every four weeks using a flow-through non-steady-state closed chamber system. Measurement gaps of Reco and NEE were filled by using temperature or radiation-based models, respectively. CH4 fluxes were measured bi-weekly using a static closed chamber system with interval sampling, with gap filling via linear interpolation. Cumulated fluxes of CO2-C (Reco, GPP, NEE) and CH4-C were calculated for a period of four consecutive years (2007-2010). The intensity of CO2-C fluxes increased with growing soil organic C stocks (AR < GL < HS). Mean annual values of the years 2008-2010 for Reco ranged between 1 500 g C m-2 and 2 000 g C m-2; annual GPP fluxes ranged from -1 400 g C m-2 to -2 300 g C m-2. NEE balances varied from C source on the mineral AR site (65 g C m-2) to C sink for organic sites (nearly -350 g C m-2). Annual CH4 exchange rates were generally very low < 0.3 g C m-2 and negligible compared to annual CO2 exchange. However, the exceptionally wet summer of 2007 (May to July) resulted in drastically increased CH4 emissions from the groundwater-influenced organic soils, particularly at the HS site where CH4 emissions were nearly 100 times higher emissions than in the following years (28 g C m-2). The excess moisture levels in 2007 also appeared to influence ecosystem CO2 exchange - likely through effects on maize growth - resulting in strongly increased Reco and GPP rates at the mineral AR site and drastically decreased Reco and GPP rates at the flooded HS site. The intensity of gaseous C fluxes seems to strongly depend on interactions between soil C stocks and interannual climatic variability. More detailed conclusions about the nature of these interactions require continuation of these measurements, i.e. long-term investigation.

Pohl, Madlen; Hagemann, Ulrike; Hoffmann, Mathias; Giebels, Michael; Albiac-Borraz, Elisa; Sommer, Michael; Augustin, Jürgen

2014-05-01

285

Reconstruction of the long-term fire history of an old-growth deciduous forest in Southern Québec, Canada, from charred wood in mineral soils  

Microsoft Academic Search

Charcoal particles are widespread in terrestrial and lake environments of the northern temperate and boreal biomes where they are used to reconstruct past fire events and regimes. In this study, we used botanically identified and radiocarbon-dated charcoal macrofossils in mineral soils as a paleoecological tool to reconstruct past fire activity at the stand scale. Charcoal macrofossils buried in podzolic soils

Brigitte Talon; Serge Payette; Louise Filion; Ann Delwaide

2005-01-01

286

EFFECT OF THE QUANTITY AND DURATION OF APPLICATION OF SIMULATED ACID PRECIPITATION ON NITROGEN MINERALIZATION AND NITRIFICATION IN A FOREST SOIL  

EPA Science Inventory

A study was conducted of the influence of the rate of application of simulated acid rain on N mineralization and nitrification in a forest soil. The rates were varied by applying different quantities of simulated rain for varying periods of time. The soil was exposed in the labor...

287

Treatment of petroleum-contaminated soils using iron mineral catalyzed hydrogen peroxide  

Microsoft Academic Search

Naturally-occurring iron minerals, goethite and magnetite, were used to catalyze hydrogen peroxide and initiate Fenton-like reaction of silica sand contaminated with diesel and\\/or kerosene in batch system. Optimum reaction conditions were investigated by varying H2O2 concentrations (0, 1, 7, 15, and 35wt%) and iron mineral contents (0, 1, 5 and 10wt%). Contaminant degradation in silica sand-iron mineral-H2O2 system was identified

Sung-Ho Kong; Richard J. Watts; Jin-Ho Choi

1998-01-01

288

The effects of organic matter-mineral interactions and organic matter chemistry on diuron sorption across a diverse range of soils.  

PubMed

Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, KOC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron KOC - organic matter-mineral interactions and organic matter chemistry - for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased KOC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between KOC for the whole soils and KOC for the HF-treated soils, indicating that the importance of organic matter-mineral interactions varied greatly amongst these soils. There was as much variation in KOC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to KOC variability. Organic matter chemistry, determined by solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, was correlated with KOC for the HF-treated soils. In particular, KOC increased with the aromatic C content (R=0.64, p=1×10(-6)), and decreased with O-alkyl C (R=-0.32, p=0.03) and alkyl C (R=-0.41, p=0.004) content. PMID:24972176

Smernik, Ronald J; Kookana, Rai S

2015-01-01

289

Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation, sorption, mineralization and leaching in different soil horizons.  

PubMed

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1mug/l in all tested profiles while metribuzine always exceeded the 0.1mug/l threshold value. PMID:18639963

Jacobsen, Carsten S; van der Keur, Peter; Iversen, Bo V; Rosenberg, Per; Barlebo, Heidi C; Torp, Søren; Vosgerau, Henrik; Juhler, René K; Ernstsen, Vibeke; Rasmussen, Jim; Brinch, Ulla Catrine; Jacobsen, Ole Hørbye

2008-12-01

290

A Method for the Determination of the Cation Exchange Capacity of Clay Minerals and Soils  

Microsoft Academic Search

For many purposes it is desirable to have a method for the determination of the cation exchange capacity of clay minerals based on principles as free from ambiguity as pos- sible. Most of the many methods previously proposed have the drawback of entailing a great deal of work if one is to make sure that the mineral is completely saturated

Galen Frysinger; HENRY C. THOMAS

1954-01-01

291

Microbial biomass and mineral N transformations in soil planted with barley, ryegrass, pea or turnip  

Microsoft Academic Search

Plants of barley (Hordeum vulgare), ryegrass (Lolium perenne), pea (Pisum sativum) or turnip (Brassica campestris rapifera) were grown in pots of unfertilised soil for 10 weeks together with unplanted control pots. A wide range of soil microbiological parameters was measured on bulk soil samples 2, 4, 7 and 10 weeks after seedlings were transplanted. There was no effect of planting

Ron Wheatley; Karl Ritz; Bryan Griffiths

1990-01-01

292

INFLUENCE OF SOIL MINERAL COLLOIDS ON METABOLIC PROCESSES, GROWTH, ADHESION, AND ECOLOGY OF MICROBES AND VIRUSES  

EPA Science Inventory

Soil is an extremely complex habitat for microbes because of the heterogeneity of soil particulates, the constantly changing water and gas regimes, the discontinuity between microhabitats, the intermittent supply of nutrients, etc. The complexity of soil is reflected in the heter...

293

Mineral ecophysiological evidence for microbial activity in banded iron formation  

SciTech Connect

The phosphorus composition of banded-iron formations (BIFs) has been used as a proxy for Precambrian seawater composition and the paleoeredox state of Earth's surface environment. However, it is unclear whether the phosphorus in BIFs originally entered the sediment as a sorbed component of the iron oxyhydroxide particles, or whether it was incorporated into the biomass of marine phytoplankton. We conducted high-resolution mineral analyses and report here the first detection of an Fe(III) acetate salt, as well as nanocrystals of apatite in association with magnetite, in the 2.48 Ga Dales Gorge Member of the Brockman Iron Formation (a BIF), Hamersley, Western Australia. The clusters of apatite are similar in size and morphology to biogenic apatite crystals resulting from biomass decay in Phanerozoic marine sediments, while the formation of an Fe(III) acetate salt and magnetite not only implies the original presence of biomass in the BIF sediments, but also that organic carbon likely served as an electron donor during bacterial Fe(III) reduction. This study is important because it suggests that phytoplankton may have played a key role in the transfer of phosphorus (and other trace elements) from the photic zone to the seafloor.

Li, Dr. Yi-Liang [University of Tennessee, Knoxville (UTK); Konhauser, Dr, Kurt [University of Alberta; Cole, David R [ORNL; Phelps, Tommy Joe [ORNL

2011-01-01

294

Effects of land use and mineral characteristics on the organic carbon content, and the amount and composition of Na-pyrophosphate soluble organic matter in subsurface soils  

NASA Astrophysics Data System (ADS)

Land use and mineral characteristics affect the balance of organic carbon in surface as well as in subsurface soils and related feedbacks on soil functions like their potential to mitigate the greenhouse effect. Actually, there are less information about the effects of land use as well as soil properties on the amount and composition of organic matter (OM) for subsurface soils as compared to surface soils. Here we aimed to analyze the long-term impact of arable and forest land use and soil mineral characteristics on subsurface soil organic carbon (SOC) contents, as well as on amount and composition of OM sequentially separated by Na-pyrophosphate solution (OM(PY)) from subsurface soil samples. Seven soils different in mineral characteristics were selected within Germany. Soil samples were taken from subsurface horizons of forest and adjacent arable sites continuously used >100 years. The OM(PY) fractions were analysed on their OC content (OCPY) and characterized by FTIR spectroscopy. A distinct influence of the long-term land use on the SOC contents could not be detected because only for four out of seven sites the forest subsurface soils showed larger SOC contents than the adjacent agricultural soils. A generally site independent enhanced OC sequestration in subsurface soils due to differences in land use cannot be expected in the long-term. Multiple regression analyses indicated for the arable subsurface soils significant positive relationships between the SOC contents and combined effects of the i) exchangeable Ca (Caex) and oxalate soluble Fe (Feox), and ii) the Caex and Alox contents. For the arable subsurface soils the increase of OCPY* (OCPY multiplied by the relative C=O content of OM(PY)) by increasing contents of Caex indicated that OM(PY) mainly interacts with Ca2+ cations. For the forest subsurface soils (pH <5), the OCPY contents were found to be related to the contents of Na-pyrophosphate soluble Fe and Al. The long-term arable and forest land use seems to result in different OM(PY)-mineral interactions in subsurfac soils. Based on this we hypothesize that a long-term land use change from arable to forest may lead to a shift from mainly OM(PY)-Ca2+ to mainly OM(PY)-Fe3+ and -Al3+ interactions if the pH of subsurface soils significantly decrease (i.e. <5).

Ellerbrock, R.; Kaiser, M.; Walter, K.; Sommer, M.

2010-12-01

295

Characterization of mineral phases of agricultural soil samples of Colombian coffee using Mössbauer spectroscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

Soil chemical analysis, X-ray diffraction (XRD) and Mössbauer spectrometry (MS) of 57Fe were used to characterize mineral phases of samples taken from the productive layer (horizon A) of agricultural coffee soil from Tolima (Colombia). Chemical analysis shows the chemical and textural parameters of samples from two different regions of Tolima, i.e., Ibagué and Santa Isabel. By XRD phases like illite (I), andesine (A) and quartz (Q) in both samples were identified. The quantity of these phases is different for the two samples. The MS spectra taken at room temperature were adjusted by using five doublets, three of them associated to Fe + 3 type sites and the other two to Fe + 2 type sites. According to their isomer shift and quadrupole splitting the presence of phases like illite (detected by DRX), nontronite and biotite (not detected by XRD) can be postulated.

Rodríguez, Humberto Bustos; Lozano, Dagoberto Oyola; Martínez, Yebrayl Antonio Rojas; Pinilla, Marlene Rivera; Alcázar, German Antonio Pérez

2012-03-01

296

Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide  

NASA Astrophysics Data System (ADS)

Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide E. Dubrovskaya1, O. Turkovskaya1, A. Tiunov2, N. Pozdnyakova1, A. Muratova1 1 - Institute of Biochemistry and Physiology of Plants and Microorganisms, RAS, Saratov, 2 - A.N. Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russian Federation Hydrocarbon mineralization in soil undergoing phytoremediation was investigated in a laboratory experiment by estimating the variation in the 13?/12? ratio in the respired ??2. Hexadecane (HD) was used as a model hydrocarbon pollutant. The polluted soil was planted with winter rye (Secale cereale) inoculated with Azospirillum brasilense strain SR80, which combines the abilities to promote plant growth and to degrade oil hydrocarbon. Each vegetated treatment was accompanied with a corresponding nonvegetated one, and uncontaminated treatments were used as controls. Emission of carbon dioxide, its isotopic composition, and the residual concentration of HD in the soil were examined after two and four weeks. At the beginning of the experiment, the CO2-emission level was higher in the uncontaminated than in the contaminated soil. After two weeks, the quantity of emitted carbon dioxide decreased by about three times and did not change significantly in all uncontaminated treatments. The presence of HD in the soil initially increased CO2 emission, but later the respiration was reduced. During the first two weeks, nonvegetated soil had the highest CO2-emission level. Subsequently, the maximum increase in respiration was recorded in the vegetated contaminated treatments. The isotope composition of plant material determines the isotope composition of soil. The soil used in our experiment had an isotopic signature typical of soils formed by C3 plants (?13C,-22.4‰). Generally, there was no significant fractionation of the carbon isotopes of the substrates metabolized by the soil microbiota. The plants and microorganisms used had the isotopic signatures similar to that of the soil, whereas the ?13C of HD was -47.9‰. The HD mineralization level was assessed by determining the difference between the isotopic compositions of soil CO2 immediately after pollution and during remediation. In the unvegetated soil, about 13% of initially added HD was mineralized, the phytoremediation increased the total decomposition of the contaminant to 19%, and an additional plant inoculation with strain SR80 raised it to 33%. The GC analysis of soil demonstrated that contaminant loss in the plant treatments and in the inoculated plant treatment was 71 and 72%, respectively, whereas in the nonvegetated treatments, it was 64 and 66%, respectively. Thus, the elimination of the contaminant resulted from its total mineralization (CO2 emission) and partial chemical transformation.

Dubrovskaya, Ekaterina; Turkovskaya, Olga

2010-05-01

297

Minerals Masquerading As Enzymes: Abiotic Oxidation Of Soil Organic Matter In An Iron-Rich Humid Tropical Forest Soil  

NASA Astrophysics Data System (ADS)

Oxidative reactions play an important role in decomposing soil organic matter fractions that resist hydrolytic degradation, and fundamentally affect the cycling of recalcitrant soil carbon across ecosystems. Microbial extracellular oxidative enzymes (e.g. lignin peroxidases and laccases) have been assumed to provide a dominant role in catalyzing soil organic matter oxidation, while other potential oxidative mechanisms remain poorly explored. Here, we show that abiotic reactions mediated by the oxidation of ferrous iron (Fe(II)) could explain high potential oxidation rates in humid tropical forest soils, which often contain high concentrations of Fe(II) and experience rapid redox fluctuations between anaerobic and aerobic conditions. These abiotic reactions could provide an additional mechanism to explain high rates of decomposition in these ecosystems, despite frequent oxygen deficits. We sampled humid tropical forest soils in Puerto Rico, USA from various topographic positions, ranging from well-drained ridges to riparian valleys that experience broad fluctuations in redox potential. We measured oxidative activity by adding the model humic compound L-DOPA to soil slurries, followed by colorimetric measurements of the supernatant solution over time. Dilute hydrogen peroxide was added to a subset of slurries to measure peroxidative activity. We found that oxidative and peroxidative activity correlated positively with soil Fe(II) concentrations, counter to prevailing theory that low redox potential should suppress oxidative enzymes. Boiling or autoclaving sub-samples of soil slurries to denature any enzymes present typically increased peroxidative activity and did not eliminate oxidative activity, further suggesting the importance of an abiotic mechanism. We found substantial differences in the oxidation products of the L-DOPA substrate generated by our soil slurries in comparison with oxidation products generated by a purified enzyme (mushroom tyrosinase). Tyrosinase generated a red compound (dopachrome) that is the target analyte of the traditional L-DOPA oxidative enzyme assay, whereas our soil slurries generated purple melanin-like compounds that were likely generated by more extensive oxidation. To investigate the importance of Fe(II) for L-DOPA oxidation, we added realistic concentrations of Fe(II) (equivalent to 10 - 500 ?g Fe g-1 soil) to an L-DOPA buffer solution under oxic conditions, and found rates of L-DOPA oxidation comparable to those from soil slurries. Molecular oxygen and Fe(II) are known to generate strong oxidants via Fenton reactions. We decreased L-DOPA oxidation rates in soil slurries by adding catalase and superoxide-dismutase enzymes to scavenge reactive oxygen species, suggesting that a free-radical mechanism contributed to L-DOPA oxidation. We obtained similar results using another humic model compound, tetramethylbenzidine (TMB). Although abiotic oxidative reactions involving iron have been employed to degrade anthropogenic organic contaminants, this study is among the first to demonstrate their potential importance for oxidizing organic matter in natural ecosystems. In soils rich in Fe(II), abiotic reactions could complement, or even obviate, the role of microbial oxidative enzymes in degrading recalcitrant organic compounds.

Hall, S. J.; Silver, W. L.

2010-12-01

298

Influence of mineral characteristics and long-term arable and forest land use on stocks, composition, and stability of soil organic matter  

NASA Astrophysics Data System (ADS)

A land use change from arable to forest is discussed as an option to sequester carbon and mitigate climate change but land use specific mechanisms responsible for soil organic matter stabilization are still poorly understood. In this study we aimed to analyze the impact of soil mineral characteristics on organic carbon (OC) stocks and on the composition as well as on the stability of mineral associated organic matter (OM) of arable and forest topsoils. We selected seven soil types of different mineral characteristics. Topsoil samples of each soil type were taken from a deciduous forest and an adjacent arable site, which have been continuously used for more than 100 years. The sequentially extracted Na-pyrophosphate soluble OM fractions (OM(PY)), representing mineral associated OM, were analyzed on their OC and 14C content and characterized by infrared spectroscopy. We found land use effects on the soil OC stocks and OC amounts separated by OM(PY) (OCPY) (forest > arable) as well as on the stability of OM(PY) (arable > forest). For the forest and arable topsoils, a linear relationship was found between the stocks of OC and exchangeable Ca. Only for the near neutral arable topsoils, correlation analyses indicate increasing OCPY contents with an increase in oxalate soluble Fe and Al, exchangable Ca, and Na-pyrophosphate soluble Mg and Fe contents. The stability of OM(PY) of the arable topsoils seems to increase with the specific surface area of the mineral phase and the content of exchangeable Ca. For the acidic forest topsoils, the stability of OM(PY) seems to increase with increasing pH, the C=O group content of OM(PY) and, the Na-pyrophosphate soluble Mg contents. The results indicate cation bridging of OM to mineral surfaces in near neutral arable soils and OM-crosslinking in acidic forest soil as important mechanisms for the stabilization of OM(PY).

Kaiser, Michael; Ellerbrock, Ruth H.; Wulf, Monika; Dultz, Stefan; Hierath, Christina; Michael, Sommer

2013-04-01

299

Mineral acquisition by mycorrhizal maize grown on acid and alkaline soil  

Microsoft Academic Search

Arbuscular mycorrhizal (AM) fungi can enhance plant acquisition of mineral nutrients and function over relatively broad pH ranges. We have determined the effect of the AM fungi Glomus etunicatum WV579A (Ge), G. diaphanum WV579B (Gd), and G. intraradices WV894 (Gi) on the acquisition of minerals by maize (Zea mays L.) grown on acid (pH 4.2 and 4.6) and alkaline (pH

R. B. Clark; S. K. Zeto

1996-01-01

300

Occurrence and distribution of polycyclic aromatic hydrocarbons in organo-mineral particles of alluvial sandy soil profiles at a petroleum-contaminated site.  

PubMed

The occurrence and the distribution of 16 USEPA priority pollutants polycyclic aromatic hydrocarbons (PAHs) were investigated in two alluvial sandy soil profiles and in their four sizes of organo-mineral particles (<2 ?m clay, 2-20 ?m silt, 20-200 ?m fine sand, and >200 ?m coarse sand) beside a typical oil sludge storage site in eastern China. PAHs were mainly enriched in the surface soil (0-20 cm) and the concentrations declined in deeper soils, from 3.68 to 0.128 ?g/g in profile 1 and 10.8 to 0.143 ?g/g in profile 2 (dry wt.). The PAHs in the upper soil layers of this study site mainly came from combustion pollution, whereas in the lower soil layers petroleum contamination became the major source of PAHs. The content of different sized organo-mineral particles of this alluvial sandy soil decreased in the following order: fine sand>coarse sand>silt>clay. X-ray diffraction (XRD) results showed that all the different sized soil fractions of this study site were dominated by quartz, calcite and feldspar. The particle surface became smoother with size increasing as shown by scanning electron microscope (SEM) images. PAH concentrations varied largely in different sized soil fractions. The highest PAH concentration was associated with clay and decreased in the order: clay>silt>coarse sand>fine sand. Soil organic matter (SOM) content, mineral composition and particle surface characteristics were suggested as three main factors affecting the distribution of PAHs in different sized organo-mineral particles. This study will help to understand the distribution and transport characteristics of PAHs in soil profiles at petroleum-contaminated sites. PMID:22766427

Lu, Zhe; Zeng, Fangang; Xue, Nandong; Li, Fasheng

2012-09-01

301

Usefulness of NIR spectroscopy for the estimation of the mineral composition and texture of soils and heavy metal uptake  

NASA Astrophysics Data System (ADS)

The accumulation of heavy metals in soils from different sources (atmospheric deposition, agricultural practices, urban-industrial activities, etc.) is of a great environmental concern. In this sense, there is a consensus in the literature that the total heavy metals in soil are not a suitable tool for risk assessment regarding heavy metal mobility and bioavailability. Several approaches have been proposed to estimate this bioavailability but controversy exists to define an universal method. The bioavailability is influenced, apart from other properties like pH, organic matter, etc., by the mineral fraction and texture of a soil. However, the determination of these parameters, especially the mineral composition, is laborious, expensive, and time consuming. Thus, the objectives of this work are the estimation of the texture and mineral components of contrasting soils and the heavy metal uptake (Cu, Zn, Pb, Ni, Cr, Cd) by barley after sewage sludge application using NIR spectroscopy. A set of 70 contrasting soils from different parts of Spain were used for the analysis of the texture and mineral composition. The mineralogical characterization of soil samples was carried out by X-ray diffraction (XRD) using whole soil random powder, oriented clay on ceramic plates, and clay random powder. Chung method was used for semi-quantitative interpretation of X-ray diffraction patterns of soils, obtaining the percentage of Calcite (Ca), Quartz (Q), Albite (Ab), Potassium Feldspar (FK), phyllosilicates (PS). For the prediction of heavy metal uptake, the 70 soils were divided in two separate sets of 36 (experiment 1) and 34 (experiment 2) soils. The methodology for both experiments, separated in time, was the same. The soils were amended with the same dose of sewage sludge (15.71 g dry weight kg-1) and placed in pots. In these pots, a bioassay with barley, under greenhouse conditions, was carried out. Eight weeks after sowing, the plants were harvested. Roots were dried in an oven at 65°C for 2 days, and total heavy metals were determined. The soil samples (air-dried and ground to pass through 2-mm sieve) were placed in glass Petri-dishes, and scanned on reflectance mode from 12000 to 3800 cm-1. For these measurements, a Fourier-Transform near infrared (FT-NIR) spectrophotometer (MPA, Bruker Optik GmbH, Germany) was used. Partial least squares (PLS) regressions were performed to relate the spectral information with the studied parameters. For the mineral parameters and texture, and according to the RPD value, the following models were obtained: excellent for Ca (R2=90.33; RPD=3.24) and Ab (R2=86.03; RPD=2.70), very good (where quantitative predictions are possible) for silt (R2=77.61; RPD=2.13), sand (R2=75.46; RPD=2.03), Q (R2=75.72; RPD=2.04) and FK (R2=78.97; RPD=2.20), and fair models which may be used for assessment and correlation for clay (R2=68.19; RPD=1.78) and PS (R2=67.63; RPD=1.77). For the case of the estimation of the heavy metal uptake, and using the results obtained in the experiment 1, very good models were obtained for Pb (R2=80.75; RPD=2.31), fair, where only high and low values are distinguishable, Ni (R2=50.13; RPD=1.43) and Cd (R2=57.65; RPD=1.56), and poor for Cu (R2=21.94; RPD=1.15), Zn (R2=1.03; RPD=1.02) and Cr (R2=46.01; RPD=1.38). The models developed with the results obtained in the experiment 2 were classified as follows: excellent for Zn (R2=87.62; RPD=2.89) and Ni (R2=85.67; RPD=2.68), very good for Pb (R2=75.08; RPD=2.04) and Cd (R2=77.37; RPD=2.13), good for Cu (R2=72.54; RPD=1.94), and fair for Cr (R2=54.9; RPD=1.51). Although satisfactory results were found for Cu and Zn in the experiment 2 (surprisingly, after the bad results of the experiment 1), they seemed not to be useful, since they were influenced by just one high value, very different to the rest. However, this was not the case of the rest of studied metals, which seemed to have similar patterns in both experiments, with logical differences due to the different ranges, soils, etc. The results indicate that NIR spectroscopy can be a very usef

Soriano-Disla, J. M.; Gómez, I.; Jordán, M. M.; Guerrero, C.; Navarro-Pedreño, J.; Meseguer, S.; Sanfeliu, T.

2009-04-01

302

The influence of water table position on soil microbial processes and carbon mineralization in a mid-latitude spruce peatland  

NASA Astrophysics Data System (ADS)

High latitude forest and peatland soils represent a major global carbon store sensitive to the impacts of global climate change. While increased temperatures may impact rates of microbial enzyme activity and greenhouse gas release from peat soils, the interaction between increased temperatures and changing precipitation patterns is projected to simultaneously reduce soil moisture and water table (WT) height in high latitude peatlands. WT reduction increases oxygen diffusion within the peat profile and potentially impacts (1) microbial activity and enzyme production, and (2) the rate of carbon mineralization and greenhouse gas emission. We performed an experiment investigating the influence temperature and available oxygen on rates of microbial enzyme activity and carbon mineralization across a 0-40 cm depth-to-water-table gradient in Caribou Bog, Orono, ME. We incubated peat samples acrotelm and catotelm peat samples at four temperatures and three oxygen concentrations for 28 days in order to investigate the temperature and oxygen sensitivity of extracellular enzyme activity and carbon gas emission. We assayed rates of four hydrolytic and two oxidative exoenzymes that depolymerize carbon (C), nitrogen (N), or phosphorus (P) and compared enzymatic activity to rates of carbon mineralization and CO2 production in incubated samples. Microbial biomass increased significantly with water table depth and incubation temperature, but did not vary significantly with sampling depth or [O2]. In contrast, hydrolytic and oxidative enzyme activity consistently decreased with sampling depth, but did not typically vary significantly with site water table position. The chitinase, N-acetyl-glucosaminidase, however, demonstrated significantly higher activity at low water table sites than high water table sites, potentially due to high fungal abundances at low water table height. Enzyme activity increased with temperature, although increases were not significant above 21°C and weakly increased with [O2]. CO2 mineralization increased with depth to water table, sampling depth, oxygen concentration, and incubation temperature, with microbial CO2 production most sensitive to increased temperature at the highest water table sites. Although total microbial biomass did not differ significantly between samples taken above and below the water table, CO2 production was significantly higher in the acrotolm and associated with higher rates of oxidative and hydrolytic enzyme activity. These distinct functional responses despite identical total biomass suggest microbial community-level differences driving distinct patterns in enzyme expression and C release. As peatland water tables fall, shifts in the proportion of catotelm-associated microbial communities to acrotelm-associated microbial communities could drive C losses and contribute to a reduction in the long-term peatland carbon store.

Gill, A. L.; Finzi, A.

2013-12-01

303

Interactions between mineral phases in the preservation of soil organic matter  

Microsoft Academic Search

Given appropriate management, soils may serve as a sink for carbon, and thereby play a potentially important role in helping countries meet CO2 emission reductions as agreed to under the Kyoto Protocol. To fully judge the capacity of soils to store carbon, however, gaps regarding the mechanisms of organic carbon (OC) stabilization need to be filled. A number of studies

C. L. S. Wiseman; W. Püttmann

2006-01-01

304

EFFECTS OF BACTERIAL LIGNIN PEROXIDASE ON ORGANIC CARBON MINERALIZATION IN SOIL, USING RECOMBINANT STREPTOMYCES STRAINS  

EPA Science Inventory

Purified lignin peroxidase was added to sterile and nonsterile silt loam soil to study the effects of bacterial lignin peroxidase ALip-P3 of Streptomyces viridosporus T7A on the rate of organic carbon turnover in soil. ignin peroxidase ALip-P3 appears to affect the short-term tur...

305

DETERMINATION OF KINETICS OF PHOSPHORUS MINERALIZATION IN SOILS UNDER OXIDIZING CONDITIONS  

EPA Science Inventory

In search of a better approach to predict phosphorus movement in soils from applied wastewaters, reactions of added orthophosphates were studied in 9 different soils with widely varying physical and chemical properties. Information obtained on the nature and rate of P reaction wi...

306

Assessing indices for predicting potential N mineralization in pedogenically distinct soils under different tillage management systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

A reliable laboratory index of nitrogen availability would be useful for making N recommendations but no single approach has received broad acceptance across a wide range of soils. We compared several indices over a range of soil conditions to test the possibility of determining the best combination...

307

EFFECT OF SIMULATED ACID RAIN ON NITRIFICATION AND NITROGEN MINERALIZATION IN FOREST SOILS  

EPA Science Inventory

To determine the possible microbiological changes in soil resulting from acid rain, columns containing samples of forest soils were leached with either a continuous application of 100cm of simulated acid rain (pH3.2-4.1) at 5 cm/hour or an intermittent 1.5-hour application of 1.2...

308

COMPARISON OF NITROGEN MINERALIZATION FOLLOWING US AND BRAZILIAN COVER CROPS FOR A SOUTHERN PIEDMONT SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Winter cover crops are essential in conservation tillage systems to protect soils from erosion and for improving soil productivity. Black oat (Avena strigosa Schreb) and oilseed radish (Raphanus sativus L.) could be useful cover crops in the Southeastern USA but successful adoption requires underst...

309

Estimating soil carbon, nitrogen, and phosphorus mineralization from short-term CO2 respiration  

Technology Transfer Automated Retrieval System (TEKTRAN)

The measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. A new method to...

310

Extraordinary soils give insight into the role of non-crystalline minerals in soil carbon response to climate and land use changes (Invited)  

NASA Astrophysics Data System (ADS)

Volcanic ash-derived soils often have enormous capacity to store carbon (C) due to complex, amorphous mineralogy. On the Island of Hawaii, a series of acrudoxic Hydrudands present along the windward slopes of Mauna Kea underlie a mosaic of vegetation ranging from undisturbed native forest to grass-dominated pasture and managed Eucalyptus plantations. These soils demonstrate a particularly strong ability to store C, even under scenarios of climate and land use change. We tested the effect of mean annual temperature (MAT) on ecosystem C storage along a 5 °C gradient and found that although fluxes of C belowground increased with MAT, total C storage, radiocarbon-based mean residence time, distribution of C among pools, and temperature sensitivity of decomposition did not change with MAT. Instead of MAT controlling these factors belowground, we identified that organo-Al complexes that were abundant in many of the soils across the gradient were the dominant factor positively associated with exceptional C storage. Further, in a sorption study from the same gradient, these same complexes also were identified as the primary driver of dissolved organic matter retention and of preferential sorption of aromatic compounds. Adjacent to the undisturbed sites, we paired a series of pasture and Eucalyptus plantation plots to determine whether conversion between these land-uses impacted C storage. We found that 10 years of plantation on previous pasture increased total soil C storage by 14.8%. Significant increases in total C occurred in the 18-72 cm depth section, consistent with the tree rooting depth. Further, within this depth increment the C fraction dominated by organo-mineral association significantly increased with plantation. These results collectively suggest the capacity for these extraordinary soils to retain carbon lies within the complex non-crystalline mineralogy and likely will be retained under future scenarios of climate and land use change.

Crow, S. E.; Lazaro, M.; Reeves, M. I.; Litton, C. M.; Giardina, C. P.; Wells, J. M.

2013-12-01

311

The influence of iron and sulfur mineral fractions on carbon tetrachloride transformation in model anaerobic soils and sediments.  

PubMed

The objective of this research was to identify the dissolved species or solid phase mineral fraction(s) best correlated with rates of carbon tetrachloride (CT) reductive transformation in systems modeling sulfate-reducing and iron oxide-rich soils and sediments. We used sulfide (S(-II))-treated goethite as our model system, but also studied Fe(II) and S(-II)-treated goethite, Fe(II)-treated goethite, pure FeS, and Fe(II)-treated FeS in order to isolate and evaluate the influence of different mineral fractions on reaction rates. Initial rates of CT transformation were measured for different pH values and concentrations of added Fe(II), as well as different aging times and conditions. The following dissolved species and iron and sulfur mineral fractions were quantified and compared with CT transformation rates: aqueous Fe(2+) and S(-II), surface associated Fe(II) (including weakly and strongly bound Fe(II)), FeS(s), and Cr(II) reducible solid phase S. Over the pH range of 6-10, CT transformation rates were correlated with surface associated Fe(II), while at pH 8, rates were correlated with weakly bound Fe(II). Aging of S(-II)-treated goethite led to oxidation of surface sulfur and a change in the concentration of weakly bound Fe(II), but did not change the relationship between initial rates and weakly bound Fe(II). The results of this research suggest that surface associated Fe(II) and weakly bound Fe(II) could serve as indicators of the potential for abiotic CT dechlorination in natural soils under sulfate-reducing conditions. PMID:17537483

Shao, Hongbo; Butler, Elizabeth C

2007-08-01

312

Role of soil mineral components in the stabilization of organic matter in Umbric Ferralsols of South Brazil  

NASA Astrophysics Data System (ADS)

Climatic conditions of subtropical and tropical regions support fast carbon (C) mineralization, and thus an accelerated degradation of soil organic matter (SOM) if compared to temperate region (Sánchez & Logan, 1992). However, even in those regions, there are still soil horizons that show notable C accumulation. Examples for the latter are umbric horizons in typical tropical soils, such as Ferralsols. The occurrence of this soils with thick umbric epipedons (× 100 cm thickness) in areas of South Brazil is a paradox, that still needs a better understanding (Marques et al., 2011), in particular since the processes that are responsible for the thickness and darkness of the umbric horizons are of special interest with respect to the role of soils as carbon sink. One major contributor to SOM stabilization represents the soil mineral phase. Therefore the main goal of this work its to study the impact of this factor on the SOM sequestration in Umbric Ferralsols from Atibaia, Campinas (São Paulo State) and Chapecó (Santa Catarina State) developed under different environmental conditions. With this objective the mineral fractions have been isolated by selective extraction of iron and aluminium oxides with different extracting solutions (sodium pyrophosphate, ammonium oxalate and dithionite-citrate-bicarbonate solution) and related to SOM quality and quantity. The latter was studied by the use of solid-state cross polarisation (CPMAS) 13C NMR spectroscopy after demineralization with hydrofluoric acid (Gonçalves et al., 2003). Quantification of the NMR spectra was performed by integration of the respective chemical shift regions under consideration of the contribution of spinning side bands. For our study the following regions were distinguished (Knicker & Lüdemann, 1995): alkyl C (0-45 ppm), N-alkyl C (45-60ppm), O-alkyl C (60-110 ppm), aryl C (110-160 ppm), carbonyl C (160-245 ppm). Preliminary results show that, the minimum vertical variation of total Fe into the profile is classical in Ferralsols and the behavior of Al points to the high presence of gibbsite in the clay fractions of the deeper horizon of the Campinas soils. The (AlP+FeP)/C ratios, obtained after extraction of the Al and Fe forms with a sodium pyrophosphate solution, were above 0.03 throughout the studied profile. According to Nierop et al. (2002) this points towards the existence of organic-metallic compounds. Most tentatively, they precipitated due to saturation of adsorption site. The solid-state 13C NMR spectra of the Chapecó samples showed that the preserved organic C is dominated by a alkyl C in lipids and amino acids (45 - 0 ppm). Other major intensities are observed between 110 and 45 ppm, in the region of O/N-alkyl C (carbohydrates, amino acids) and carboxyl C (220 to 160 ppm). The missing of a clear signal in the region between 160 and 110 ppm (signal derives from aromatic or olefinic C) indicates that in this soil lignin has minor contributions to its aromatic C content.

Velasco-Molina, Marta; Berns, Anne E.; Macias, Felipe; Knicker, Heike

2013-04-01

313

Biochemical resistance of pyrogenic organic matter in fire-affected mineral soils of Southern Europe  

NASA Astrophysics Data System (ADS)

Incorporated into the soil, naturally formed pyrogenic organic matter (PyOM) is considered as highly recalcitrant, but direct estimation of PyOM decomposition rates are scarce. With this aim in mind, we subjected organic matter (OM) of fire-affected and unaffected soils to biochemical degradation under laboratory conditions and monitored CO2 production over a period of seven months. The soils derived from fire affected and unaffected areas of the Sierra de Aznalcóllar and the Doñana National Park, Southern Spain. Virtual fractionation of the solid-state 13C nuclear magnetic resonance (NMR) spectra of the fire affected soils into fire-unaffected soil organic matter (SOM) and PyOM yielded charcoal C contributions of 30 to 50% to the total organic C (Corg) of the sample derived from the Aznalcóllar region. Fitting the respiration data with a double exponential decay model revealed a fast carbon flush during the first three weeks of the experiment. Solid-state 13C NMR spectroscopy evidenced the contribution of aromatic moieties of the PyOM to this initial carbon release and to the biosynthesis of new microbial biomass. The input of PyOM resulted in an increase of the mean residence time (MRT) of the slow OM pool of the soil by a factor of 3 to 4 to approximately 40 years which rises doubts rises doubts about the presumed big influence of PyOM as an additional C-sink in soils. On the other hand, although being small the difference in turnover rates is evident and has some major implication with respect to long-term alteration of the chemical composition of OM in fire-affected soils. Based on the obtained results and the analysis of PyOM in other soil systems, a conceptual model is presented which can explain the different behavior of PyOM under different soil conditions.

Knicker, H.; González Vila, F. J.; Clemente Salas, L.

2012-04-01

314

SOIL LIMING AND MINERAL FERTILIZATION FOR ROOT NODULATION AND GROWTH OF FABA BEANS IN AN ACID SOIL IN TUNISIA  

Microsoft Academic Search

Faba beans (Vicia faba L) are grown in northern Tunisia where annual rainfall approaches 1200 mm and where the soil acidity is the most limiting factor for plant growth. Aluminum (Al) and manganese (Mn) toxicities provide a hostile environment to root growth. To alleviate such a problem, farmers use selected acid-tolerant species. However, crop yields remain far below their optimal

Sarra Ouertatani; Kamel Regaya; John Ryan; Azaiez Gharbi

2011-01-01

315

Compound-specific Sorption of Dissolved Organic Carbon on Soil Minerals  

NASA Astrophysics Data System (ADS)

Organic carbon (OC) in soil is the largest terrestrial C sink and securely storing this pool appears to be a promising strategy to combat climate change. Sorption of dissolved organic carbon (DOC) is considered to be a major process of OC preservation in deeper soils. However the soil and solution parameters and environmental factors controlling the DOC sorption rates and mechanisms are still poorly studied. We tested the influence of different physical and chemical properties of subsurface soils on the DOC sorption capacity of a wide range of temperate soils. Soil samples from B horizons were selected from various sites within the eastern United States (225 samples from 73 soil series). The maximum sorption of DOC was determined by applying different concentrations of solutions of characterized humic acid (0-100 mg/L) to the soils in batch experiments at a solid-to-solution ratio of 1:60 for 48 h and fitting to the Langmuir equation. Multiple regression analysis revealed that clay and Fe-oxide content accounted for 55 % of variation in maximum DOC sorption capacity in Ultisols and, clay content and pH were the major drivers for DOC sorption capacity of Alfisols. The maximum DOC sorption capacity of Mollisols was mainly controlled by clay and total OC content. Results also provide indirect indication that Mollisols preferentially sorb certain OC functional groups from the bulk humic acid solution. Consequently, we hypothesize that chemical nature of OC compounds impart a major control on C cycling and preservation in soils. This hypothesis was tested by studying the specific sorption and desorption of a variety of organic compounds (e.g., carbohydrates, organic acids, amino acids, phenols, and lignin) on Mollisols, Ultisols and Alfisols through batch technique. Preliminary results showed that different soil orders exhibit compound-specific sorption of DOC. The underpinning mechanisms of such sorption specificity at solution and solid phases of soils have currently been explored. This study will provide novel insights on the role of soil OC chemistry as a control for long-term preservation of C in deeper soils.

Jagadamma, S.; Heal, K.; Mayes, M. A.; Phillips, J.; Jardine, P.

2010-12-01

316

Assessment of natural radioactivity and function of minerals in soils of Yelagiri hills, Tamilnadu, India by Gamma Ray spectroscopic and Fourier Transform Infrared (FTIR) techniques with statistical approach  

NASA Astrophysics Data System (ADS)

Gamma Ray and Fourier Transform Infrared (FTIR) spectroscopic techniques were used to evaluate the natural radioactivity due to natural radionuclides and mineralogical characterization in soils of Yelagiri hills, Tamilnadu, India. Various radiological parameters were calculated to assess the radiation hazards associated with the soil. The distribution pattern of activity due to natural radionuclides is explained by Kriging method of mapping. Using FTIR spectroscopic technique the minerals such as quartz, microcline feldspar, orthoclase feldspar, kaolinite, montmorillonite, illite, and organic carbon were identified and characterized. The extinction coefficient values were calculated to know the relative distribution of major minerals such as quartz, microcline feldspar, orthoclase feldspar and kaolinite. The calculated values indicate that the amount of quartz is higher than orthoclase feldspar, microcline feldspar and much higher than kaolinite. Crystallinity index was calculated to know the crystalline nature of quartz. The result indicates that the presence of disordered crystalline quartz in soils. The relation between minerals and radioactivity was assessed by multivariate statistical analysis (Pearson's correlation and cluster analysis). The statistical analysis confirms that the clay mineral kaolinite and non-clay mineral quartz is the major factor than other major minerals to induce the important radioactivity variables and concentrations of uranium and thorium.

Chandrasekaran, A.; Ravisankar, R.; Rajalakshmi, A.; Eswaran, P.; Vijayagopal, P.; Venkatraman, B.

2015-02-01

317

Incorporating microbial ecology concepts into global soil mineralization models to improve predictions of carbon and nitrogen fluxes  

NASA Astrophysics Data System (ADS)

models of soil carbon (C) and nitrogen (N) fluxes become increasingly needed to describe climate change impacts, yet they typically have limited ability to reflect microbial activities that may affect global-scale soil dynamics. Benefiting from recent advances in microbial knowledge, we evaluated critical assumptions on microbial processes to be applied in global models. We conducted a sensitivity analysis of soil respiration rates (Cmin) and N mineralization rates (Nmin) for different model structures and parameters regarding microbial processes and validated them with laboratory incubation data of diverse soils. Predicted Cmin was sensitive to microbial biomass, and the model fit to observed Cmin improved when using site-specific microbial biomass. Cmin was less affected by the approach of microbial substrate consumption (i.e., linear, multiplicative, or Michaelis-Menten kinetics). The sensitivity of Cmin to increasing soil N fertility was idiosyncratic and depended on the assumed mechanism of microbial C:N stoichiometry effects: a C overflow mechanism upon N limitation (with decreased microbial growth efficiency) led to the best model fit. Altogether, inclusion of microbial processes reduced prediction errors by 26% (for Cmin) and 7% (for Nmin) in our validation data set. Our study identified two important aspects to incorporate into global models: site-specific microbial biomass and microbial C:N stoichiometry effects. The former requires better understandings of spatial patterns of microbial biomass and its drivers, while the latter urges for further conceptual progress on C-N interactions. With such advancements, we envision improved predictions of global C and N fluxes for a current and projected climate.

Fujita, Yuki; Witte, Jan-Philip M.; Bodegom, Peter M.

2014-03-01

318

Influence of long-term mineral fertilization on metal contents and properties of soil samples taken from different locations in Hesse, Germany  

NASA Astrophysics Data System (ADS)

Essential and non-essential metals occur in soils as a result of weathering, industrial processes, fertilization, and atmospheric deposition. Badly adapted cultivation of agricultural soils (declining pH value, application of unsuitable fertilizers) can enhance the mobility of metals and thereby increase their concentrations in agricultural products. As the enrichment of metals in soils occurs over long time periods, monitoring of the long-term impact of fertilization is necessary to assess metal accumulation in agricultural soils. The main objective of this study was to test the effects of different mineral fertilizer variations on soil properties (pH, Corg, and cation exchange capacity (CEC)) and pseudo-total and mobile metal contents of soils after 14 years of fertilizer application and to determine residual effects of the fertilization 8 years after cessation of fertilizer treatment. Soil samples were taken from a field experiment which was carried out at four different locations (210, 260, 360, and 620 m above sea level) in Hesse, Germany. During the study, a significant decrease in soil pH and an evident increase in soil carbon content and cation exchange capacity with fertilization were determined. The CEC of the soils was closely related to their organic C contents. Moreover, pseudo- and mobile metal (Cd, Cu, Mn, Pb, Zn) contents in the soils increased due to application of 14 years of mineral fertilizer treatments (N, P, NP, and NPK) when compared to control plots. Eight years after termination of the fertilization in the soil samples taken from soil profiles of the fertilized plots (NPK) for monitoring the residual effects of the fertilizer application, a decrease of 82.6, 54.2, 48.5, 74.4, and 56.9% in pseudo-total Cd, Cu, Mn, Pb, and Zn contents, respectively, was determined.

Czarnecki, S.; Düring, R.-A.

2015-01-01

319

Thermal Analyzer for Planetary Soil (TAPS): an in Situ Instrument for Mineral and Volatile-element Measurements  

NASA Technical Reports Server (NTRS)

Thermal Analyzer for Planetary Soil (TAPS) offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with an integrated sampling mechanism. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K. During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through ground based data analysis, multicomponent DSC data are deconvolved and correlated with the water release profile to quantitatively determine the types and relative proportions of volatile-bearing minerals such as clays and other hydrates, carbonates, and nitrates. The rapid-response humidity sensors also achieve quantitative analysis of total water. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume less than 1000 cm(sup 3), occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NO(x), and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas.

Gooding, J. L.; Ming, D. W.; Gruener, J. E.; Gibbons, F. L.; Allton, J. H.

1993-01-01

320

Identifying soils with potential of expanding sulfate mineral formation using electromagnetic induction  

E-print Network

quantifying sulfate in soils that may be potentially used in highway construction using electromagnetic induction. The objectives are to: 1) document electrical conductivity (EC) variability within selected sites that contain sulfate-bearing materials, and 2...

Fox, Miranda Lynn

2004-11-15

321

Mineral-Induced Formation of Free Radicals: A Plausible Mechanism for Anoxic Oxidation in Martian Soils  

NASA Astrophysics Data System (ADS)

We investigated the kinetic of free radical generation by aqueous pyrite slurries under anoxic conditions as a possible explanation for the oxidative reactivity of martian soils today and in the past.

Gil-Lozano, C.; Losa-Adams, E.; Davila, A. F.; Fairen, A. G.; Gago-Duport, L.

2014-07-01

322

EFFECT OF SIMULATED ACID PRECIPITATION ON NITROGEN MINERALIZATION AND NITRIFICATION IN FOREST SOILS  

EPA Science Inventory

After exposure of samples of three forest soils(pH 3.4 and 3.9) from the Adirondacks region of New York to 60, 230, or 400 cm of simulated rain of pH 3.5 or 5.6 in 4, 14 or 24 weeks, respectively, the soil samples were seperated into the 0 to 2 and 2 to 5 cm organic layers and fu...

323

Biodegradation of methyl tert -butyl ether by newly identified soil microorganisms in a simple mineral solution  

Microsoft Academic Search

Methyl tert-butyl ether (MTBE) is a widely used fuel ether, which has become a soil and water contaminant. In this study, 12 microbial\\u000a strains were isolated from gasoline-contaminated soils and selected because of their capacity to grow in MTBE. The strains\\u000a were identified by 16S\\/ITS rDNA gene sequencing and screened for their ability to consume MTBE aerobically in a simple

Maria José Barberà; Estíbaliz Mateo; Rasa MonkaityteMagda; Magda Constantí

2011-01-01

324

Pristine Soils Mineralize 3-Chlorobenzoate and 2,4-Dichlorophenoxyacetate via Different Microbial Populations  

Microsoft Academic Search

Biodegradation of two chlorinated aromatic compounds was found to be a common capability of the microorganisms found in the soils of undisturbed, pristine ecosystems. We used 2,4-dichlorophenoxyacetate (2,4-D) and 3-chlorobenzoate (3CBA) as enrichment substrates to compare populations of degrading bacteria from six different regions making up two ecosystems. We collected soil samples from four Mediterranean (California, central Chile, the Cape

ROBERTA R. FULTHORPE; ALBERT N. RHODES; ANDJAMES M. TIEDJE

1996-01-01

325

Nitrogen mineralization and availability of mixed leguminous and non-leguminous cover crop residues in soil  

Microsoft Academic Search

Whereas non-leguminous cover crops such as cereal rye (Secale cereale) or annual ryegrass (Lolium multiflorium) are capable of reducing nitrogen (N) leaching during wet seasons, leguminous cover crops such as hairy vetch (Vicia villosa) improve soil N fertility for succeeding crops. With mixtures of grasses and legumes as cover crop, the goal of reducing\\u000a N leaching while increasing soil N

S. Kuo; U. M. Sainju

1998-01-01

326

Nitrogen mineralization in riparian soils along a river continuum within a multi-landuse basin  

EPA Science Inventory

Nitrogen dynamics in riparian systems are often addressed within one landuse type and are rarely studied on watershed scales involving multiple land uses. This study tested for both temporal trends and watershed-wide spatial patterns in N mineralization and identified site fact...

327

Impact of Organic Amendments with and Without Mineral Fertilizers on Soil Microbial Respiration  

NASA Astrophysics Data System (ADS)

A field experiment was conducted to study the effects of Sewage Sludge (SS), Municipal Waste Compost (MWC) and Vermicompost (VC) with and without chemical fertilizer (Urea, 50 kg ha-1 + Potassium sulfate, 100 kg ha-1 + Triple super phosphate, 127.5 kg ha-1) on Soil Microbial Respiration (SMR) and Total Organic Carbon (TOC) in a soil cropped to soybean. Experiment was arranged in a complete block design with three replications. Organic amendments were added to soil at rate of 0 (control treatment), 20 and 40 Mg ha-1. Furthermore each level of organic fertilizers with ½ normal of chemical fertilizer was also enriched. Soil samples were taken after one year of fertilization. Results illustrated that application of organic amendments increased TOC and SMR and soybean yield compared to control and chemical fertilizer treatments. Sewage sludge amended soils showed higher SMR, TOC and soybean yield than that of other organic amendment treatments. An increasing trend was observed in all studied parameters, as rates of application increased. All parameters were greater in treatments receiving a combination of chemical fertilizers and organic amendments (enriched treatments) compared to soils receiving organic amendments alone. Results obtained by discriminate analysis indicated that rates of application were more effective to create discriminating among treatments. This study showed that TOC was significantly correlated with SMR. Significant correlation was also observed between SMR and soybean yield.

Gilani, S. S.; Bahmanyar, M. A.

328

Urea-nitrogen transformation and compost-nitrogen mineralization in three different soils as affected by the interaction between both nitrogen inputs  

Microsoft Academic Search

Interactive effects of a combined application of urea and compost on the fates of urea-N and net mineralization of compost-N in three soils with different contents of organic-C and inorganic-N were examined through an aerobic 6-week incubation study. Soils were each subjected to four treatments of urea and compost applied at rates of 0 and 0 mg N kg -1 (control),

Kyung-Hwa Han; Woo-Jung Choi; Gwang-Hyun Han; Seok-In Yun; Sun-Ho Yoo; Hee-Myong Ro

2004-01-01

329

Alternate partial root-zone irrigation induced dry\\/wet cycles of soils stimulate N mineralization and improve N nutrition in tomatoes  

Microsoft Academic Search

Given the same amount of irrigation volume, applying alternate partial root-zone irrigation (PRI) has improved crop N nutrition\\u000a as compared to deficit irrigation (DI), yet the mechanisms underlying this effect remain unknown. Therefore, the objective\\u000a of this study was to investigate whether PRI induced soil dry\\/wet cycles facilitate soil organic N mineralization hereby contributing\\u000a to the improvement of N nutrition

Yaosheng Wang; Fulai Liu; Andreas de Neergaard; Lars S. Jensen; Jesper Luxhøi; Christian R. Jensen

2010-01-01

330

Repeated wet-dry cycles do not accelerate the mineralization of organic C involved in the macro-aggregation of a sandy loam soil  

Microsoft Academic Search

Repeated mild wet-dry cycles were imposed on a sandy loam to accelerate the mineralization of organic C involved in stabilising macro-aggregates. Soil maintained continually moist (control soil) was compared to that subjected to a series of 6 wet-dry cycles. Two patterns of rewetting and drying were investigated: (1) incubated dry at 25°C for six days between each wet-dry cycle (dry-incubated),

B. P. Degens; G. P. Sparling

1995-01-01

331

Integrating plant-microbe interactions to understand soil C stabilization with the MIcrobial-MIneral Carbon Stabilization model (MIMICS)  

NASA Astrophysics Data System (ADS)

If soil organic matter is predominantly microbial biomass, plant inputs that build biomass should also increase SOM. This seems obvious, but the implications fundamentally change how we think about the relationships between plants, microbes and SOM. Plant residues that build microbial biomass are typically characterized by low C/N ratios and high lignin contents. However, plants with high lignin contents and high C/N ratios are believed to increase SOM, an entrenched idea that still strongly motivates agricultural soil management practices. Here we use a combination of meta-analysis with a new microbial-explicit soil biogeochemistry model to explore the relationships between plant litter chemistry, microbial communities, and SOM stabilization in different soil types. We use the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, newly built upon the Community Land Model (CLM) platform, to enhance our understanding of biology in earth system processes. The turnover of litter and SOM in MIMICS are governed by the activity of r- and k-selected microbial groups and temperature sensitive Michaelis-Menten kinetics. Plant and microbial residues are stabilized short-term by chemical recalcitrance or long-term by physical protection. Fast-turnover litter inputs increase SOM by >10% depending on temperature in clay soils, and it's only in sandy soils devoid of physical protection mechanisms that recalcitrant inputs build SOM. These results challenge centuries of lay knowledge as well as conventional ideas of SOM formation, but are they realistic? To test this, we conducted a meta-analysis of the relationships between the chemistry of plant liter inputs and SOM concentrations. We find globally that the highest SOM concentrations are associated with plant inputs containing low C/N ratios. These results are confirmed by individual tracer studies pointing to greater stabilization of low C/N ratio inputs, particularly in clay soils. Our model and meta-analysis results suggest that current ideas about plant-microbe-SOM relationships are unraveling. If so, our reconsideration of the mechanisms stabilizing SOM will also challenge long-held views about how to optimize plant community management to increase SOM.

Grandy, Stuart; Wieder, Will; Kallenbach, Cynthia; Tiemann, Lisa

2014-05-01

332

Biogeochemistry of mineral-organic associations across a long-term mineralogical soil gradient (0.3-4100 kyr), Hawaiian Islands  

NASA Astrophysics Data System (ADS)

Organic matter (OM) in mineral-organic associations (MOAs) represents a large fraction of carbon in terrestrial ecosystems which is considered stable against biodegradation. To assess the role of MOAs in carbon cycling, there is a need to better understand (i) the time-dependent biogeochemical evolution of MOAs in soil, (ii) the effect of the mineral composition on the physico-chemical properties of attached OM, and (iii) the resulting consequences for the stabilization of OM. We studied the development of MOAs across a mineralogical soil gradient (0.3-4100 kyr) at the Hawaiian Islands that derived from basaltic tephra under comparable climatic and hydrological regimes. Mineral-organic associations were characterized using biomarker analyses of OM with chemolytic methods (lignin phenols, non-cellulosic carbohydrates) and wet chemical extractions, surface area/porosity measurements (N 2 at 77 K and CO 2 at 273 K), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results show that in the initial weathering stage (0.3 kyr), MOAs are mainly composed of primary, low-surface area minerals (olivine, pyroxene, feldspar) with small amounts of attached OM and lignin phenols but a large contribution of microbial-derived carbohydrates. As high-surface area, poorly crystalline (PC) minerals increase in abundance during the second weathering stage (20-400 kyr), the content of mineral-associated OM increased sharply, up to 290 mg C/g MOA, with lignin phenols being favored over carbohydrates in the association with minerals. In the third and final weathering stage (1400-4100 kyr), metastable PC phases transformed into well crystalline secondary Fe and Al (hydr)oxides and kaolin minerals that were associated with less OM overall, and depleted in both lignin and carbohydrate as a fraction of total OM. XPS, the N 2 pore volume data and OM-mineral volumetric ratios suggest that, in contrast to the endmember sites where OM accumulated at the surfaces of larger mineral grains, topsoil MOAs of the 20-400-kyr sites are composed of a homogeneous admixture of small-sized PC minerals and OM, which originated from both adsorption and precipitation processes. The chemical composition of OM in surface-horizon MOAs, however, was largely controlled by the uniform source vegetation irrespective of the substrate age whereas in subsoil horizons, aromatic and carboxylic C correlated positively with oxalate-extractable Al and Si and CuCl 2-extractable Al concentrations representing PC aluminosilicates and Al-organic complexes ( r2 > 0.85). Additionally, XPS depth profiles suggest a zonal structure of sorbed OM with aromatic carbons being enriched in the proximity of mineral surfaces and amide carbons (peptides/proteins) being located in outer regions of MOAs. Albeit the mineralogical and compositional changes of OM, the rigidity of mineral-associated OM as analyzed by DSC changed little over time. A significantly reduced side chain mobility of sorbed OM was, however, observed in subsoil MOAs, which likely arose from stronger mineral-organic bindings. In conclusion, our study shows that the properties of soil MOAs change substantially over time with different mineral assemblages favoring the association of different types of OM, which is further accentuated by a vertical gradient of OM composition on mineral surfaces. Factors supporting the stabilization of sorbed OM were (i) the surface area and reactivity of minerals (primary or secondary crystalline minerals versus PC secondary minerals), (ii) the association of OM with micropores of PC minerals (via 'sterically' enhanced adsorption), (iii) the effective embedding of OM in 'well mixed' arrays with PC minerals and monomeric/polymeric metal species, (iv) the inherent stability of acidic aromatic OM components, and (iv) an impaired segmental mobility of sorbed OM, which might increase its stability against desorption and microbial utilization.

Mikutta, Robert; Schaumann, Gabriele E.; Gildemeister, Daniela; Bonneville, Steeve; Kramer, Marc G.; Chorover, Jon; Chadwick, Oliver A.; Guggenberger, Georg

2009-04-01

333

A regional approach for mineral soil weathering estimation and critical load assessment in boreal Saskatchewan, Canada.  

PubMed

In boreal regions of the province of Saskatchewan, Canada, there is concern over emerging acid precursor emission sources associated with the oil sands industry. Base cation weathering rates (BC(w)) and steady-state critical loads of sulfur (CL(S)) were identified for upland forest soil plots (n=107) in 45 ecodistricts according to a new method for approximation of BC(w) in the region. This method was developed by regression of simple soil and site properties with BC(w) calculated through application of a soil chemical model (PROFILE). PROFILE was parameterized using detailed physicochemical data for a subset (n=35) of the sites. Sand content, soil moisture and latitude emerged as important predictive variables in this empirical regression approximation. Base cation weathering varied widely (0.1-8000 mmol(c) m(-3) yr(-1)) across the study sites, consistent with their contrasting soil properties. Several sites had lower rates than observed in other acid-sensitive regions of Canada owing to quartz dominated mineralogy and coarse-textured soils with very low surface area. Weathering was variable within ecodistricts, although rates were consistently low among ecodistricts located in the northwest of the province. Overall, half of the forest plots demonstrated CL(S) less than 45 mmol(c) m(-2) yr(-1). Historically, the acidification risk in this region has been considered low and monitoring has been limited. Given the very low CL(S) in many northern ecodistricts and the potential for increased acid deposition as oil sands activities expand, soil acidification in these regions warrants further study. PMID:22940479

Whitfield, Colin J; Watmough, Shaun A

2012-10-15

334

Influence of mineral characteristics on soil organic matter stocks, composition and stability of topsoils under long-term arable and forest land use  

NASA Astrophysics Data System (ADS)

A land use change from arable to forest is discussed as an option to sequester carbon and mitigate climate change but land use specific mechanisms responsible for soil organic matter stabilization are still poorly understood. In this study we aimed to analyze the impact of soil mineral characteristics (clay content and composition, iron and aluminium oxide content and crystallinity, specific surface area, content of exchangeable cations) on organic carbon (OC) stocks (kg m-2) and on the composition as well as on the stability of mineral associated organic matter (OM) of arable and forest topsoils. We selected seven soil types of different mineral characteristics for this study. Topsoil samples of each soil type were taken from a deciduous forest and an adjacent arable site. The arable and forest sites have been used continuously for more than 100 years. The Na-pyrophosphate soluble OM fractions (OM(PY)), representing mineral associated OM, were sequentially extracted, analyzed on their OC and 14C content, and characterised by FTIR spectroscopy. We found land use effects on the soil OC stocks and OC amounts separated by OM(PY) (OCPY) (forest > arable) as well as on the stability of OM(PY) (arable > forest). For the forest and arable topsoils, respectively, a linear relationship was found between the stocks of OC and exchangeable Ca. Only for the arable topsoils (pH 6.7-7.5), correlation analyses indicate increasing OCPY contents with an increase in oxalate soluble Fe and Al, exchangable Ca, and Na-pyrophosphate soluble Mg and Fe contents. The stability of OM(PY) of the arable topsoils seems to increase with the specific surface area of soil minerals <2 ?m and the content of exchangeable Ca. For the acidic forest topsoils (pH <5) showing a ratio between soil organic carbon content and specific surface area of >1 g m-2, the stability of OM(PY) seems to increase with increasing pH, the C=O group content of OM(PY) and, the Na-pyrophosphate soluble Mg contents. We hypothesize cation bridging of OM to mineral surfaces in near neutral arable soils and OM-crosslinking in acidic forest soil as important mechanisms for OM(PY) stabilization.

Kaiser, M.; Ellerbrock, R. H.; Wulf, M.; Dultz, S.; Hierath, C.; Sommer, M.

2011-12-01

335

Mercury in soil gas and air--A potential tool in mineral exploration  

USGS Publications Warehouse

The mercury content in soil gas and in the atmosphere was measured in several mining districts to test the possibility that the mercury content in the atmosphere is higher over ore deposits than over barren ground. At Cortez, Nev., the distribution of anorhalous amounts of mercury in the air collected at ground level (soil gas) correlates well with the distribution of gold-bearing rocks that are covered by as much as 100 feet of gravel. The mercury content in the atmosphere collected at an altitude of 200 feet by an aircraft was 20 times background over a mercury posit and 10 times background over two porphyry copper deposits. Measurement of mercury in soil gas and air may prove to be a valuable exploration tool.

McCarthy, Joseph Howard; Vaughn, W.W.; Learned, R.E.; Meuschke, J.L.

1969-01-01

336

Coupling Sorption to Soil Weathering during Reactive Transport: Impacts of Mineral Transformation and Sorbate Aging on Contaminant Speciation and Mobility  

SciTech Connect

The Hanford subsurface has become contaminated with highly alkaline, radioactive waste generated as a result of weapons production. The radioactive brine was stored in underground storage tanks, a number of which developed leaks and contaminated the surrounding subsurface. The high pH and ionic strength of these wastes has been predicted to accelerate the degree of soil weathering to produce new mineral phases--cancrinite and sodalite among the most abundant. Previous work has demonstrated that Cs and Sr, which along with I represent the most radioactive components in the waste, are sequestered by these neo-formed solids. The present work is aimed at assessing the stability of these neo-formed solids, with special emphasis on the degree of Cs, Sr and I release under ambient (neutral pH, low ionic strength) conditions expected to return to the Hanford area after the caustic radioactive brine waste is removed.

Carl I. Steefel; Aaron Thompson; Jon Chorover

2006-06-01

337

The influence on climate forcing of mineral aerosols from disturbed soils  

Microsoft Academic Search

AEROSOLS influence the global radiation budget1, and so changes in the atmospheric aerosol load due to either natural causes or human activity will contribute to climate change2. A large fraction of the mass of tropospheric aerosol is wind-blown mineral dust, and its contribution to radiative forcing can be locally significant3,22. Model calculations indicate that 50 +\\/- 20% of the total

Ina Tegen; Andrew A. Lacis; Inez Fung

1996-01-01

338

Residence Time Effects on P Sorption/Desorption on Ferrihydrite Understanding mechanisms of P retention/release on soil mineral surfaces is  

E-print Network

Residence Time Effects on P Sorption/Desorption on Ferrihydrite Y. Arai Understanding mechanisms of P retention/release on soil mineral surfaces is fundamental in assessing the P biogeochemistry that are high ammonium oxalate extractable P, due to long-term manure amendments. Since there is a high

Sparks, Donald L.

339

In-Vitro Determination of Arsenic Bioavailability in Contaminated Soil and Mineral Beneficiation Waste from Ron Phibun, Southern Thailand: A Basis for Improved Human Risk Assessment  

Microsoft Academic Search

The post-ingestion bioavailability of arsenic (As) in alluvial soil and mineral beneficiation waste from Ron Phibun, Nakhon Si Thammarat Province, Thailand has been investigated using a physiologically-based extraction test (PBET). The method utilises synthetic leaching fluids closely analogous to those of the human stomach and small intestine, upon which the leaching duration and ambient temperature of the experimental procedure are

T. M. Williams; B. G. Rawlins; B. Smith; M. Breward

1998-01-01

340

In-situ mineralization of actinides for groundwater cleanup: Laboratory demonstration with soil from the Fernald Environmental Management Project  

SciTech Connect

An attractive approach to decreasing the probability of actinide migration in the subsurface is to transform the ions into less mobile forms by remote treatment. The process described herein relies on a polyfunctional organophosphorus complexant to sequester the mobile metal ions by complexation/cation exchange in the near term. The cation exchanger is designed to subsequently decompose, transforming the actinides into insoluble phosphate mineral forms as the medium of stable long-term isolation. This material can be generated in situ in the subsurface thus eliminating the need for excavation to immobilize the actinide ions. Previous investigations have identified a suitable organophosphorus reagent and profiled its decomposition kinetics, verified the formation of phosphate mineral phases upon decomposition of the reagent, determined solubility limits for appropriate metal phosphates under groundwater conditions, and examined the cation exchange behavior of the calcium salt of the organophosphorus reagent. In this report, the focus is on a laboratory-scale demonstration of the concept using a soil sample from the Fernald Environmental Management Plant.

Nash, K.L.; Jensen, M.P.; Schmidt, M.A. [Argonne National Lab., IL (United States). Chemistry Div.

1997-11-01

341

Nutrient-enhanced survival of and phenanthrene mineralization by alginate-encapsulated and free Pseudomonas sp. UG14Lr cells in creosote-contaminated soil slurries.  

PubMed

The effects of nutrient amendment and alginate encapsulation on survival of and phenanthrene mineralization by the bioluminescent Pseudomonas sp. UG14Lr in creosote-contaminated soil slurries were examined. UG14Lr was inoculated into creosote-contaminated soil slurries either as a free cell suspension or encapsulated in alginate beads prepared with montmorillonite clay and skim milk. Additional treatments were free-cell-inoculated slurries amended with sterile alginate beads, free-cell-inoculated and uninoculated slurries amended with skim milk only, and uninoculated, unamended slurries. Mineralization was determined by measuring 14CO2 released from radiolabelled phenanthrene. Survival was measured by selective plating and bioluminescence. Inclusion of skim milk was found to enhance both survival of and phenanthrene mineralization by free and encapsulated UG14Lr cells. PMID:7576562

Weir, S C; Dupuis, S P; Providenti, M A; Lee, H; Trevors, J T

1995-10-01

342

Nature of organo-mineral particles across density fractions in a volcanic-ash soil: air-drying and sonication effect  

NASA Astrophysics Data System (ADS)

Interactions of plant- and microbially-derived organic matter with mineral phases exert significant controls on the stabilization of organic matter (OM) as well as other biogeochemical processes in soil. Density fractionation techniques have been successful in distinguishing soil organo-mineral particles of different degrees of microbial alteration, turnover rate of C, mineral associations. A major methodological difference among the density fractionation studies is the choice of sample pre-treatment. Presence or absence of sonication to disrupt and disperse soil particles and aggregates is a particularly important choice which could significantly alter the nature and distribution of organo-mineral particle and thus the resultant elemental concentration in each density fraction. Soil moisture condition (air-dry vs. field-moist) may also have strong impact especially for soils rich in Fe oxides/hydroxides and/or poorly-crystalline minerals that are prone for (possibly irreversible) aggregation. We thus tested these two effects on the concentration and distribution of C, N, and extractable phases of Fe and Al (by pyrophosphate and acid oxalate) across six density fractions (from <1.6 to >2.5 g/cm^3) using a surface-horizon of volcanic-ash soil which contained large amounts of poorly-crystalline minerals and organo-metal complexes. Compared to field-moist sample, air-drying had little effects on the elemental concentration or distribution across the fractions. In contrast, sonication on air-dried sample at each density cutoff during fractionation process caused significant changes. In addition to well-known increase in low-density material due to the liberation of plant detritus upon aggregate disruption, we found clear increase in C, N, and metals in 2.0-2.3 g/cm^3 fraction, which was largely compensated by the reduction in 1.8-2.0 g/cm^3 and, to a less extent, 2.3-2.5 g/cm^3 particles. Overall, sonication led to the redistribution of C and N by 15-20% and that of poorly-crystalline phases of Al and Fe by similar degrees. These results suggest that, for the volcanic soil studied here, the use of field-moist or air-dried samples without sonication step likely provide better information on the organo-mineral associations occurring in the field.

Wagai, R.; Kajiura, M.; Shirato, Y.; Uchida, M.

2011-12-01

343

Analysis of soil washing effectiveness to remediate a brownfield polluted with pyrite ashes.  

PubMed

Soil in a brownfield contaminated by pyrite ashes showed remarkably high concentrations of several toxic elements (Hg, Pb, Zn, Cu, Cd, and As). Initially, we assessed various physical, chemical and mineralogical properties of this soil. The data obtained, and particularly multivariate statistics of geochemical results, were useful to establish the predominant role of the soil organic matter fraction (6%) and iron oxyhydroxides in the binding of heavy metals and arsenic. In addition, we studied the viability of soil washing techniques to reduce the volume of contaminated soil. Therefore, to concentrate most of the contaminants in a smaller volume of soil, the grain-size fraction below 125 microm was treated by hydrocycloning techniques. The operational parameters were optimized by means of a factorial design, and the results were evaluated by attributive analysis. This novel approach is practical for the global simultaneous evaluation of washing effectiveness for several contaminants. A concentration factor higher than 2.2 was achieved in a separated fraction that contained less than 20% of the initial weight. These good yields were obtained for all the contaminants and with only one cycle of hydrocycloning. Hence full-scale soil washing is a plausible remediation technique for the study site. PMID:20447764

Sierra, C; Gallego, J R; Afif, E; Menéndez-Aguado, J M; González-Coto, F

2010-08-15

344

Forest Application of Granulated Wood Ash on Mineral Soils in Sweden  

Microsoft Academic Search

Most of the wood ash produced in Sweden today is disposed of in landfills. Ash application to forests is an alternative use. Possible environmental risks of ash fertilization in forests are heavy metal contamination, N- leaching, formation of greenhouse gases, and damage to soil vegetation, roots, and mycorrhiza. These risks are mainly associated with application of \\

STAFFAN JACOBSON

345

MECHANISM OF MOLYBDENUM ADSORPTION ON SOIL MINERALS EVALUATED USING VIBRATIONAL SPECTROSCOPY AND SURFACE COMPLEXATION MODELING.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Molybdenum adsorption on amorphous aluminum and iron oxides and soils was investigated as a function of solution pH and ionic strength. Vibrational spectroscopies (Raman and FTIR) were used to determine mode of bonding of adsorbed molybdate ions. The ability of the constant capacitance, diffuse la...

346

Phosphorus Dynamics in Amended Soils During the Growing Season: II. Ligand Exchange and Mineralization  

Technology Transfer Automated Retrieval System (TEKTRAN)

A field study was conducted near Bushland, TX to evaluate changes in phosphorus (P) pools in soils amended with cattle manure and monoammonium phosphate (MAP) throughout a single growing season. Unfertilized checks were included for P extractability comparisons. Grain sorghum (Sorghum bicolor (L.)...

347

Carbon mineralization from organic wastes at different composting stages during their incubation with soil  

Microsoft Academic Search

The decomposition of seven different organic waste mixtures prepared with sewage sludges, animal manures, city refuse and industrial and plant residues, was studied during their aerobic incubation with soil. The waste mixtures were composted by the Rutgers static pile system, and four samples of each mixture were collected at various composting stages: the initial mixture, and samples taken during the

M. P. Bernal; M. A. Sánchez-Monedero; C. Paredes; A. Roig

1998-01-01

348

LUMBRICID MACROFAUNA ALTER ATRAZINE MINERALIZATION AND SORPTION IN A SILT LOAM SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Atrazine is a widely used herbicide and is often a contaminant in terrestrial and freshwater ecosystems. It is uncertain, however, how the activity of soil macrofauna affects atrazine fate and transport. Therefore, we investigated whether earthworms enhance atrazine biodegradation by stimulating her...

349

Accounting for change of support in spatial accuracy assessment of modelled soil mineral phosphorous concentration  

Microsoft Academic Search

Agricultural activities in the Netherlands cause high nitrogen and phosphorous fluxes from soil to ground- and surface water. A model chain (STONE) has been developed to study and predict the magnitude of the resulting ground- and surface water pollution under different environmental conditions. STONE has three main components, namely: 1) the fertiliser distribution model CLEAN; 2) the atmospheric transport and

Ulrich Leopold; Gerard B. M. Heuvelink; Aaldrik Tiktak; Peter A. Finke; Oscar Schoumans

2006-01-01

350

Altered Snow Density and Chemistry Change Soil Nitrogen Mineralization and Plant Growth  

Microsoft Academic Search

Snow properties such as snow density will likely change in a warmer climate. Changes in depth and extent of snow cover have been shown to affect soil nutrient dynamics and plant growth; however, effects of a changed snow density have so far not been explicitly tested. We altered snow properties (especially depth and density according to those found on ski

Christian Rixen; Michele Freppaz; Veronika Stoeckli; Christine Huovinen; Kai Huovinen; Sonja Wipf

2008-01-01

351

Growth and mineral nutrition of the native trees Pollalesta discolor and the N-fixing Inga densiflora in relation to the soil properties of a degraded volcanic soil of the Ecuadorian Amazon  

Microsoft Academic Search

Land reclamation in the humid tropics, using native tree plantations, requires a better knowledge of plant-soil interactions,\\u000a and of patterns of growth of several poorly known species. We examined the establishment and mineral nutrition of two early-successional\\u000a native tree species, Inga densiflora (N-fixing) and Pollalesta discolor, in relation to properties of a degraded Hydrandept\\u000a volcanic soil in Ecuadorian Amazon. Initial

Robert Davidson; Daniel Gagnon; Yves Mauffette

1999-01-01

352

[Variation of soil nitrogen during in situ mineralization process under different grasslands in the mountainous area of southern Ningxia, Northwest China].  

PubMed

Variations in organic nitrogen, microbial biomass nitrogen, soluble organic nitrogen, NH4(+) -N, NO3(-) -N, NO2(-) -N and N mineralization were investigated under three different grasslands in the mountainous area of southern Ningxia, Northwest China (natural grassland, artificial turf and abandoned land) using the close-top tube incubation method. Microbial biomass nitrogen, soluble organic nitrogen, NH4(+)-N, NO3(-)-N, NO2(-)-N and N mineralization exhibited significant seasonal variations. The nitrogen levels remained essentially unchanged from April to June, significantly decreased in July-August, rebounded after August, and were lowest in August. The organic nitrogen content remained unchanged in the whole training process. The soil mineralization rates, nitrification and ammonification rate were lowest in June-August. The ratios of each N fraction to total N responded differently to seasonal changes. The ratios of organic N, NO2(-) -N to total N did not change, in contrast, the ratios of nitrate N, microbial biomass nitrogen and soluble organic nitrogen, to total soil N decreased from April to August, and increased from August to December. The soil organic matter, pH, and bulk density were closely related to soil N. There was a significant positive correlation among the six N fractions. The soil nitrogen content of the different grassland types followed the order of natural grassland > abandoned land > artificial turf. PMID:25158519

Jiang, Yue-Li; Zhao, Tong; Yan, Hao; Huang, Yi-Mei

2014-06-01

353

Sorption and mineralization of S-metolachlor and its ionic metabolites in soils and vadose zone solids: consequences on groundwater quality in an alluvial aquifer (Ain Plain, France).  

PubMed

This study characterizes the transfer of S-metolachlor (SMOC) and its metabolites, metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA) to the alluvial aquifer. Sorption and mineralization of SMOC and its two ionic metabolites were characterized for cultivated soils and solids from the vadose (unsaturated) zone in the Ain Plain (France). Under sterile soil conditions, the absence of mineralization confirms the importance of biotic processes in SMOC degradation. There is some adsorption and mineralization of the parent molecule and its metabolites in the unsaturated zone, though less than in soils. For soils, the MESA adsorption constant is statistically higher than that of MOXA and the sorption constants of the two metabolites are significantly lower than that of SMOC. After 246 days, for soils, maximums of 26% of the SMOC, 30% of the MESA and 38% of the MOXA were mineralized. This partly explains the presence of these metabolites in the groundwater at concentrations generally higher than those of the parent molecule for MESA, although there is no statistical difference in the mineralization of the 3 molecules. The laboratory results make it possible to explain the field observations made during 27 months of groundwater quality monitoring (monthly sampling frequency). The evolution of both metabolite concentrations in the groundwater is directly related to recharge dynamics; there is a positive correlation between concentrations and the groundwater level. The observed lag of several months between the signals of the parent molecule and those of the metabolites is probably due to greater sorption of the parent molecule than of its metabolites and/or to degradation kinetics. PMID:24055953

Baran, Nicole; Gourcy, Laurence

2013-11-01

354

Identification of Mn-oxide minerals in some soils from Devon, UK, and their varying capacity to adsorb Co and Cu.  

PubMed

A number of Mn-oxide minerals in soils from a farm in North Devon have been tentatively identified using a combination of advanced analytical techniques: scanning electron microscopy (SEM), scanning electron microprobe (SEMP), X-ray diffraction (XRD) and bulk chemical analysis by wet digestion followed by inductively-coupled plasma spectrometry (ICP). The minerals lithiophorite and hollandite are thought to occur throughout the study area although there is considerable geographical variation in the proportions of minerals present. Bimessite, vernadite, romanechite, todorokite and cryptomelane may also be present, although in smaller amounts.The use of SEMP, together with a simple sorption experiment, has allowed a study of the extent of uptake of Co and Cu by different Mn-oxide minerals. Lithiophorite appears to take up Co and Cu more effectively than hollandite within a pH range of 4-6. PMID:24198105

Lidiard, H M; Rae, J E; Parker, A

1993-09-01

355

Effect of heavy metals on soil mineral surfaces and bioretention pond performance  

NASA Astrophysics Data System (ADS)

Haibo Zhang and Mira S. Olson Department of Civil, Architectural, and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 As urban stormwater runoff flows across impervious surfaces, it collects and accumulates pollutants that are detrimental to the quality of local receiving water bodies. Heavy metal pollution, such as copper, lead and zinc, has been a concern in urban stormwater runoff. In addition, the presence of bacteria in stormwater has been frequently reported. The co-existence of both heavy metals and bacteria in stormwater and their complex interactions determine their transport and removal through bioretention pond. Stormwater runoff was sampled from a bioretention pond in Philadelphia, PA. The concentration of copper, lead and zinc were measured as 0.086ppm, 0.083ppm and 0.365ppm, respectively. Batch experiments were conducted with solutions of pure copper, lead and zinc, and with a synthetic stormwater solution amended with copper, lead and zinc. The solution was buffered to pH 7, within the range of the observed stormwater pH. In pure heavy metal solutions, the sorption of copper, lead and zinc onto soil are 96%, 99% and 85%, respectively. In synthetic stormwater containing nutrients and all three metals, the sorption of lead is 97%, while copper and zinc decrease to 29% and 71%, respectively. Mineralogy of a soil sample taken from the bioretention pond was analyzed using a scanning electron microscope (SEM) and compared before and after sorption experiments. Sorption and complexation of heavy metals is likely to change the mineralogy of soil particle surfaces, which will affect the attachment of bacteria and therefore its transport through soil. This study will benefit long-term predictions of the performance of bioretention ponds for urban stormwater runoff treatment. Keyword: Heavy metal pollution, sorption, surface complexation, urban stormwater runoff, bioretention pond

Zhang, H.; Olson, M. S.

2009-12-01

356

Effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper in synthesized Fe(III) minerals and Fe-rich soils.  

PubMed

The effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper were investigated in a high concentration of sulfate with synthesized Fe(III) minerals and red earth soils rich in amorphous Fe (hydr)oxides. Batch microcosm experiments showed that red earth soil inoculated with subsurface sediments had a faster Fe(III) bioreduction rate than pure amorphous Fe(III) minerals and resulted in quicker immobilization of Cu in the aqueous fraction. Coinciding with the decrease of aqueous Cu, SO4(2-) in the inoculated red earth soil decreased acutely after incubation. The shift in the microbial community composite in the inoculated soil was analyzed through denaturing gradient gel electrophoresis. Results revealed the potential cooperative effect of microbial Fe(III) reduction and sulfate reduction on copper immobilization. After exposure to air for 144 h, more than 50% of the immobilized Cu was remobilized from the anaerobic matrices; aqueous sulfate increased significantly. Sequential extraction analysis demonstrated that the organic matter/sulfide-bound Cu increased by 52% after anaerobic incubation relative to the abiotic treatment but decreased by 32% after oxidation, indicating the generation and oxidation of Cu-sulfide coprecipitates in the inoculated red earth soil. These findings suggest that the immobilization of copper could be enhanced by mediating microbial Fe(III) reduction with sulfate reduction under anaerobic conditions. The findings have an important implication for bioremediation in Cucontaminated and Fe-rich soils, especially in acid-mine-drainage-affected sites. PMID:24448165

Hu, Chaohua; Zhang, Youchi; Zhang, Lei; Luo, Wensui

2014-04-01

357

Impact of two different types of grassland-to-cropland-conversion on dynamics of soil organic matter mineralization and N2O emission  

NASA Astrophysics Data System (ADS)

Conversion of grassland to arable land often causes a decrease of soil organic matter stocks and it increases nitrate leaching and the emission of the greenhouse gases CO2 and N2O. Conversion methods which minimize the mechanical impact on the surface soil may reduce mineralization rates and greenhouse gas emissions. We determined the effect of two different types of grassland to maize conversion (a) plowing of the sward followed by seeding of maize and (b) chemical killing of the sward by glyphosate followed by direct seed of maize) on the mineralization of grassland derived organic matter, the release of nitrate and the emission of N2O. The field experiment was carried out at the research station Kleve which is located in North Rhine-Westphalia, Germany. A four times replicated plot experiment with the following treatments was set up in April 2010: (i) mechanical conversion of grassland to maize (ii) chemical conversion grassland to maize and (iii) continuous grassland as reference. Nitrogen fertilization was 137 kg N ha-1 for maize and 250 kg N ha-1 for grassland. Soil respiration and emission of N2O were measured weekly for one year using manual closed chambers and gas chromatography. Emission of CO2 from mineralization of grassland-derived organic matter was determined from the ?13C signature of soil respiration. Soil respiration was mainly fueled by mineralization of grassland-derived organic carbon. There was no effect of the type of grassland conversion on total mineralization of organic matter originating from grassland. Both grassland to maize conversion treatments exhibited very high soil nitrate concentrations one year after grassland conversion (about 250 kg NO3-N in 0 - 90 cm). Total N2O emission decreased in the order chemical conversion of grassland (25.5) > mechanical conversion of grassland (20.1) > permanent grassland (10.8). Emissions were highest after harvest of maize when soil moisture increased. The results show that both types of grassland-to-maize conversion resulted in a large surplus of soil nitrate which promotes nitrate leaching to the groundwater and indirect N2O emissions. In addition, it caused high direct N2O emissions. We found no evidence that grassland conversion without mechanical plowing is an option to reduce groundwater contamination and greenhouse gas emission to the atmosphere.

Roth, G.; Flessa, H.; Helfrich, M.; Well, R.

2012-04-01

358

Plant growth promotion by inoculation with selected bacterial strains versus mineral soil supplements.  

PubMed

In the process of remediation of mine sites, the establishment of a vegetation cover is one of the most important tasks. This study tests two different approaches to manipulate soil properties in order to facilitate plant growth. Mine waste from Ingurtosu, Sardinia, Italy rich in silt, clay, and heavy metals like Cd, Cu, and Zn was used in a series of greenhouse experiments. Bacteria with putative beneficial properties for plant growth were isolated from this substrate, propagated and consortia of ten strains were used to inoculate the substrate. Alternatively, sand and volcanic clay were added. On these treated and untreated soils, seeds of Helianthus annuus, of the native Euphorbia pithyusa, and of the grasses Agrostis capillaris, Deschampsia flexuosa and Festuca rubra were germinated, and the growth of the seedlings was monitored. The added bacteria established well under all experimental conditions and reduced the extractability of most metals. In association with H. annuus, E. pithyusa and D. flexuosa bacteria improved microbial activity and functional diversity of the original soil. Their effect on plant growth, however, was ambiguous and usually negative. The addition of sand and volcanic clay, on the other hand, had a positive effect on all plant species except E. pithyusa. Especially the grasses experienced a significant benefit. The effects of a double treatment with both bacteria and sand and volcanic clay were rather negative. It is concluded that the addition of mechanical support has great potential to boost revegetation of mining sites though it is comparatively expensive. The possibilities offered by the inoculation of bacteria, on the other hand, appear rather limited. PMID:23990253

Wernitznig, S; Adlassnig, W; Sprocati, A R; Turnau, K; Neagoe, A; Alisi, C; Sassmann, S; Nicoara, A; Pinto, V; Cremisini, C; Lichtscheidl, I

2014-06-01

359

The isotopic composition of neon emitted in solar flares and trapped in lunar soil minerals  

NASA Astrophysics Data System (ADS)

Closed system etching of lunar soil samples and stepwise mass spectrometric analysis of the He, Ne, and Ar released was developed. This noble gas release technique prevents isotopic and elemental fractionation occurring in stepwise heating. Measurements on one pyroxene and two plagioclase separates reveal the presence of trapped noble gases emitted during solar flares (SEP Ne) besides the solar wind, confirming earlier indications for such a component. Solar wind Ne and SEP Ne are isotopically different. The best estimate for the composition of SEP Ne is: Ne20/Ne22 = 11.1 +or- 0.2; Ne21/Ne22 less than or = 0.029. The Ne20/Ne22 ratio is within error limits equal to Ne-C found in meteorites but agrees at best marginally with the respective value measured by satellite borne instruments. The SEP Ne in lunar soils is not identical with planetary Ne. Only weak evidence that SEP Ar may be isotopically different from solar wind Ar is found.

Wieler, R.; Baur, H.; Signer, P.

360

Impact of the addition of different plant residues on carbon-nitrogen content and nitrogen mineralization-immobilization turnover in a soil incubated under laboratory conditions  

NASA Astrophysics Data System (ADS)

Application of plant residues as soil amendment may represent a valuable recycling strategy that affects on carbon (C) and nitrogen (N) cycling, soil properties improvement and plant growth promotion. The amount and rate of nutrient release from plant residues depend on their quality characteristics and biochemical composition. A laboratory incubation experiment was conducted for 120 days under controlled conditions (25 °C and 58% water filled pore space (WFPS)) to quantify initial biochemical composition and N mineralization of leguminous and non-leguminous plant residues i.e. the roots, shoots and leaves of Glycine max, Trifolium repens, Zea mays, Poplus euramericana, Rubinia pseudoacacia and Elagnus umbellate incorporated into the soil at the rate of 200 mg residue N kg-1 soil. The diverse plant residues showed wide variation in total N, carbon, lignin, polyphenols and C/N ratio with higher polyphenol content in the leaves and higher lignin content in the roots. The shoot of G. max and the shoot and root of T. repens displayed continuous mineralization by releasing a maximum of 109.8, 74.8 and 72.5 mg N kg-1 and representing a 55, 37 and 36% of added N being released from these resources. The roots of G. max and Z. mays and the shoot of Z. mays showed continuous negative values throughout the incubation showing net immobilization. After an initial immobilization, leaves of P. euramericana, R. pseudoacacia and E. umbellate exhibited net mineralization by releasing a maximum of 31.8, 63.1 and 65.1 mg N kg-1, respectively and representing a 16, 32 and 33% of added N being released. Nitrogen mineralization from all the treatments was positively correlated with the initial residue N contents (r = 0.89; p ? 0.01), and negatively correlated with lignin content (r = -0.84; p ? 0.01), C/N ratio (r = -0.69; p ? 0.05), lignin/N ratio (r = -0.68; p ? 0.05), polyphenol/N ratio (r = -0.73; p ? 0.05) and ligin + polyphenol/N ratio (r = -0.70; p ? 0.05) indicating a significant role of residue chemical composition and quality in regulating N transformations and cycling in soil. The present study indicates that incorporation of plant residues strongly modify the mineralization-immobilization turnover (MIT) of soil that can be taken into account to develop synchronization between net N mineralization and crop demand in order to maximize N delivery and minimize N losses.

Abbasi, M. K.; Tahir, M. M.; Sabir, N.; Khurshid, M.

2014-10-01

361

Effects of Mineral Phosphorous Fertilization and cd Loading on cd Translocation from Soil to Corn (Zea mays L.)  

NASA Astrophysics Data System (ADS)

During the last fifty years phenomenal progress has been made in several areas of ecology of different toxic elements in soils. Concerns regarding heavy metals contamination in the environment affecting all ecosystem componets, including "soil-plant-animal-human" chain (SPAHC), have been identified with increasing efforts on limiting their bioavailability. Many sites have been identified as hazardous (H) waste (W) sites (S)(HWS) because of the presence of elevated concentrations of these elements. In 2000, the main cadmium actual transfer index ("ATI" by Márton 2004) maximum and minimum values in the case of maize 4-6 foliaged phenophase ranged between +22.0- -89.2%. compared with control soils. The grain "ATI" maximum and minimum values changed between +14.4- -89.2% as opposed to unterated plants. The highest yields reached around 10 t* ha-1. These study shows maize has ability to a different degree to cadmium bioaccumulation from soil to corn and by these way for "FOOD CHAIN". Key words: Phosphorous, Fertilization, Cadmium, Translocation, Corn Introduction Nowadays, sustainable (S) precision (P) agricultural (A) production (P)(SPAP) has become the major issue following global changes in all the world over. It is well known that it has strongly established on soils. The functioning and their ability to supply nutrients, store water, release gases, modify pollutants, decrease physical degradation and produce crops is profundly influenced by their fertiliy. During the last fifty years phenomenal progress has been made in several areas of ecology of different toxic elements in soils (ATSDR 1997, 1999; ANZECC 1992; CWP 1995; COC 2004; DEFRA 2002; EDF 1998; HSC 2005; IARC 1993; ). Concerns regarding heavy metals contamination in the environment affecting all ecosystem componets, including "soil-plant-animal-human" chain (SPAHC), have been identified with increasing efforts on limiting their bioavailability (Magher 1991; NEPC 1998; NDH 1986; NTP 1991). Many sites have been identified as hazardous (H) waste (W) sites (S)(HWS) because of the presence of elevated concentrations of these elements. They will remain a threat to the environment until they are removed or immobilized. We can test and improve these situation by using different plant species, as corn (Zea mays L.) x macro nutrients as phosphorous experimental methods. Maize has a very great biomass (B) production (P) potential (P)(BPP) and important role in soil fertility by the design of plant rotation to field plant production, the animal foraging as a fodder-crop with a high carbohydrate (70%) and protein (10%) content (70%) and via pytoremediation possibilities. Cd is considered to be a nonessential element for maize, it is effectively absorbed by both the root and leaf system. By these ways a great proportion of the cadmium is to be accumulated in root tissues, even when Cd enters the plant via foliar system from the polluted air and precipitation. The most chief geobiochemical property of cadmium ions is their strong affinity for sulfhydryl groups of several compounds (OSHA 1992; Richardson 1992; RAIS 1991; Sittig 1991; TAP 1999; WA 1996; WHO 1992, 2001). Furthermore Cd shows an affinity for other side chains of protein and for phosphate groups too. The Cd content of maize is of the highest concern as a Cd reservoir and as the patway of cadmium to soil-plant-animal-man chain (FOOD CHAIN). Thus, tolerance and adaptation of corn to higher Cd levels, although important from the environmental poin of view, create a helth risc. Material and Method The phosphorus (P2O5) mineral fertilization and cadmium loading effects were studied in a long-term field experiment set up at Experimental Station of the Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences on a calcareous chernozem soil at Nagyhörcsök in 1977. The soil had the following agrogeochemical characteristics: pH (KCl) 7.3, humus 3.0%, ammonlactate (AL) soluble-P2O5 60-80 mg*kg-1, AL-K2O 180-200 mg*kg-1 in the plowed

László, Márton, ,, Dr.

2010-05-01

362

Metal Reduction and Mineral formation by a Psychrotolerant Fe(III)-Reducing Bacterium Isolated from an Iron-Rich Waters near a Hydrothermal Vent  

NASA Astrophysics Data System (ADS)

Although dissimilatory metal reduction and mineral formation under mesophilic and thermophilic conditions are extensively examined, they are poorly understood under low temperature. The objective of this study was to examine metal reduction and mineral formation using a psychrotolerant iron-reducing bacterium (Shewanella alga, PV-4) isolated from iron-rich waters associated with the Naha vents off the Hawaiian coast. The psychrotolerant iron-reducing bacterium was able to use lactate, formate, and hydrogen as an electron donor while reducing Fe(III)-citrate, Fe(III)-EDTA, Co(III)-EDTA, Cr(VI), Mn(IV), and iron oxyhydroxide (FeOOH) at temperatures between 0 and 37°C. The psychrotolerant bacterium exhibited diverse mineral precipitation capabilities including the formation of magnetite (Fe3O4), siderite (FeCO3), and rhodochrosite (MnCO3). Transmission electron microscopic data showed that PV-4 formed mainly superparamagnetic magnetite at temperatures ranging from 0 to 14°C and formed mainly single-domain magnetite at temperatures ranging from 18 to 37°C. This study indicats that iron-reducing bacteria may contribute to the biogeochemical cycling of metals and carbon at low temperatures and may contribute to the natural remnant magnetism of marine sediments.

Roh, Y.; Vali, H.; Stapleton, R. D.; Fields, M. M.; Phelps, T. J.; Zhou, J.

2002-12-01

363

Magnetic Properties of Ubiquitous yet Underrated Antiferromagnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrihydrite, lepidocrocite and goethite are antiferromagnetic, weakly "ferromagnetic" iron oxyhydroxides that are commonly found in diverse environments, including ground waters and streams, sediments, soils, or acid mine drainage. One of them, ferrihydrite, constitutes the mineral core of ferritin, a vital iron storage protein. Iron oxyhydroxides take part in multiple biological and abiological processes, and can evolve, under changing environmental or geological conditions, to more magnetic phases such as hematite, maghemite, or magnetite. Therefore, they represent key minerals with regard to paleoclimate, paleoenvironmental, and paleomagnetic studies. We will present low temperature magnetic properties acquired on fully characterized synthetic iron oxyhydroxides. The complex nature of the magnetism of these minerals is revealed by comparing magnetic data with other types of characterizations such as high-resolution transmission electron microscopy or synchrotron X-ray magnetic circular dichroism (XMCD), or when the early-stages of solid-state alteration (under oxidizing or reducing atmosphere) are studied. In particular, we will present resent results about the structure of 6-line ferrihydrite, about the possible presence of ferri-magnetic nano-clusters in lepidocrocite, and about uncompensated magnetic moments in goethite nanoparticles.

Guyodo, Y. J.; Till, J. L.; Lagroix, F.; Bonville, P.; Penn, R.; Sainctavit, P.; Ona-Nguema, G.; Morin, G.

2013-05-01

364

Physicochemical Properties Of Starch From Sago (Metroxylon Sagu) Palm Grown In Mineral Soil At Different Growth Stages  

NASA Astrophysics Data System (ADS)

A study was carried out to determine the physico-chemical properties of sago starch from sago palm grown in mineral soil at different growth stages. Four stages of sago palm, namely, Plawei (P), Bubul (B), Angau Muda (AM) and Angau Tua (AT) were studied. Sago starch granules were observed by using scanning electron microscopy (SEM) while the x-ray diffraction patterns were examined to study the starch crystallinity. The highest starch content was found at Plawei stage (94.2%) and Angau Muda stage (97.9%), respectively. The amylose content varied between 29.4 to 31.2% for each growth stages. The highest swelling power was found at the earliest growth stages (P) late growth stages (AT) which are 13.3 g/g and 13.2 g/g, respectively. Granule size distributions were similar as the palm grows to the later growth stages, where highest mean diameter of sago starches granules was found at AM. Variation of starch, amylose and proximate content was observed for starches derived from sago palm different growth stages were insignificant.

Uthumporn, U.; Wahidah, N.; Karim, A. A.

2014-08-01

365

Arthrobacter nanjingensis sp. nov., a mineral weathering bacterium isolated from forest soil.  

PubMed

A Gram-positive-staining, non-motile, rod- or coccoid-shaped actinobacterium, designated strain A33(T), was isolated from a forest soil sample from Nanjing, Jiangsu Province, China. The strain grew optimally at 30 ºC, pH 7.0 and with 3% NaCl (w/v). Phylogenetic analysis of the strain based on 16S rRNA gene sequences showed it was most closely related to Arthrobacter woluwensis (98.4%), Arthrobacter humicola (97.5%), Arthrobacter globiformis (97.4%), Athrobacter oryzae (97.3%) and Arthrobacter cupressi (97.0%). The major cellular fatty acids were anteiso-C15:0, anteiso-C17:0 and iso-C15:0 and MK-9(H2) was the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and three glycolipids. Cell-wall analysis revealed peptidoglycan type A3?, based on L-Lys-L-Ala, and cell-wall sugars were galactose and mannose. The genomic G+C content of strain A33(T) was 66.8 mol%. The low DNA-DNA relatedness values between strain A33(T) and recognized species of the genus Arthrobacter and many phenotypic properties supported the classification of strain A33(T) as a representative of a novel species of the genus Arthrobacter, for which the name Arthrobacter nanjingensis sp. nov. is proposed. The type strain is A33(T) (=CCTCC AB 2014069(T) =DSM 28237(T)). PMID:25358511

Huang, Zhi; Bao, Yuan Yuan; Yuan, Tong Tong; Wang, Guo Xiang; He, Lin Yan; Sheng, Xia Fang

2014-10-30

366

A Novel Approach to Investigate Soil Organic Matter Development Using Isotopes and Thermal Analysis: C Sourcing from Various Plant Materials and Mineral Influence on Stability  

NASA Astrophysics Data System (ADS)

Biomolecular input quality and mineral constituents are important factors that regulate turnover and stabilization of natural organic matter. The complexity and variability of natural soil systems might shadow basic mechanisms occurring between organic and mineral components. Utilizing an in vitro model decomposition system allows for control over inputs and turnover time. We created a model soil system with composted plant litter that was enriched with 13-C in order to investigate C use during the formation of stabilized SOM. The litter was subjected to microbially-mediated, aerobic decomposition before pure clays were added and allowed to incubate further. Isotopically labeled organic inputs allowed us to focus on C derived from known plant sources as a qualitative assessment of SOM formation. Thermogravimetry-Differential Scanning Calorimetry (TG-DSC) has been used successfully to quantify thermochemical properties of SOM reactivity/stability in three regions of exothermic activity corresponding generally to carbohydrates and lipids (Exo 1; 150-350 C), aromatic and condensed polymers (Exo 2; 400-460 C) and refractory/mineral associated C (Exo 3; 500-550 C). Thermal separation of the organics allows for in-line evolved gas analysis via Isotope Ratio Mass Spectrometry (IRMS) to measure 13-C isotopic values of those thermally separated organic compound classes. This coupled analysis is ideal in that it is fast, reproducible, and requires no sample pretreatment other than drying/grinding and it provides stability, mass loss, and isotopic data from a single sample. DSC results show the development of a higher temperature, energetically recalcitrant C pool over the course of decomposition in mineral-free litters and its absence in clay-litter mixtures, implicating the influence of mineral surfaces on soil organic matter energetic stability. Preliminary IRMS results indicate that mineral presence influences C sourcing from particular plant materials in some SOM compound classes. For example, in mineral-free treatments containing 13-C enriched woody material, gas evolution from Exo 3 that was enriched in 13-C and was therefore derived from the woody material. However, the presence of montmorillonite clay minerals resulted in gas evolution that was depleted in 13-C and was therefore derived from the non-woody plant inputs present (grass and leaves). This shows a change in mechanism: either the microbial sourcing of C from woody material to produce Exo 3 compounds changed in the presence of the mineral or mineral interaction with the organics altered the thermal reactivity of those wood-derived compounds, causing them to thermally separate differently. We are also exploring the effect of bridging metal interaction with minerals and plant litter as SOM develops. We are able to show that this analytical method is useful for probing mineral influence on SOM stability and differentiation in litter C utilization during decomposition in a single sample. TG-DSC-IRMS analysis can be used for any soil-organic matter investigation, with isotopically enriched or natural abundance materials: applications range from measuring terrestrial C sequestration efforts and organic waste management efficacy to sustainable agricultural practices.

Bower, J.; Horwath, W. R.

2012-12-01

367

Effects of summer catch crop, residue management, soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems  

Microsoft Academic Search

Nitrogen nutrient management is crucially important in shallow-rooted vegetable production systems characterized by high input\\u000a and high environmental risk. To investigate the effects of summer catch crop (sweet corn, common bean, garland chrysanthemum\\u000a and edible amaranth), residue management, and soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization\\u000a in intensive production systems, we determined the rates of net

Yongqiang Tian; Jun Liu; Xueyan Zhang; Lihong Gao

2010-01-01

368

Characterization of the Mineral Phosphate-Solubilizing Activity of Pantoea aglomerans MMB051 Isolated from an Iron-Rich Soil in Southeastern Venezuela (Bolívar State)  

Microsoft Academic Search

The mineral phosphate-solubilizing (MPS) activity of a Pantoea agglomerans strain, namely MMB051, isolated from an iron-rich, acidic soil near Ciudad Piar (Bolívar State, Venezuela), was characterized\\u000a on a chemically defined medium (NBRIP). Various insoluble inorganic phosphates, including tri-calcium phosphate [Ca3(PO4)2], iron phosphate (FePO4), aluminum phosphate (AlPO4), and Rock Phosphate (RP) were tested as sole sources of P for bacterial growth.

Miguel Sulbarán; Elizabeth Pérez; María M. Ball; Alí Bahsas; Luis Andrés Yarzábal

2009-01-01

369

Effects of the geophagous earthworm Metaphire guillelmi on sorption, mineralization, and bound-residue formation of 4-nonylphenol in an agricultural soil.  

PubMed

Effects of earthworms on fate of nonylphenol (NP) are obscure. Using (14)C-4-NP111 as a representative, we studied the fate of