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Sample records for soil ph influence

  1. Influence of pH on pesticide sorption by soil containing wheat residue-derived char

    International Nuclear Information System (INIS)

    Sheng Guangyao; Yang Yaning; Huang Minsheng; Yang Kai

    2005-01-01

    Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs ∼3.0 and ∼7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH ∼7.0 than at pH ∼3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH ∼7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH ∼3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH ∼3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides

  2. Influence of pH on pesticide sorption by soil containing wheat residue-derived char

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Guangyao [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States)]. E-mail: gsheng@uark.edu; Yang Yaning [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Huang Minsheng [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China); Yang Kai [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China)

    2005-04-01

    Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs {approx}3.0 and {approx}7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH {approx}7.0 than at pH {approx}3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH {approx}7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH {approx}3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH {approx}3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides.

  3. Evaluation of coal combustion byproducts as soil liming materials - their influence on soil pH and enzyme activities

    Energy Technology Data Exchange (ETDEWEB)

    McCarty, G W; Siddaramappa, R; Wright, R J; Codling, E E; Gao, G

    1994-03-01

    To evaluate coal combustion byproducts as liming materials and address issues related to soil quality, the authors compared the influence of different amounts of four combustion byproducts (fly ash and bed ash from a fluidized bed combustion furnace, lime-injected multistage burner residue, and spray dryer residue) and CaCO[sub 3] on soil pH and activities of urease, phosphatase, arylsulfatase, and dehydrogenase in an acidic soil. Studies comparing the influence of the combustion byproducts and CaCO[sub 3] on soil pH showed that on weight basis of application, substantial differences were observed in the ability of these materials to influence soil pH but that such differences decreased markedly after the data were transformed to a CaCO[sub 3] equivalent basis of application. Analysis of covariance for these transformed data indicated that whereas the liming abilities of fly ash and CaCO[sub 3] were not significantly different when compared on the CaCO[sub 3] equivalent basis, those of bed ash, multistage burner residue, and spray dryer residue were less than that of CaCO[sub 3]. Studies comparing the influence of the byproducts and CaCO[sub 3] on soil enzyme activities showed that the effect of these liming materials on the enzyme activities studied was largely due to their influence on soil pH. These studies showed that the combustion byproducts tested functioned as soil liming materials in a manner similar to that of CaCO[sub 3] and seemed to have little adverse effect on soil quality.

  4. Spatial patterns of soil pH and the factors that influence them in plantation forests of northern China

    Science.gov (United States)

    Hong, Songbai; Liu, Yongwen; Piao, Shilong

    2017-04-01

    Climate and anthropogenic activities such as afforestation and nitrogen deposition all impact soil pH. Understanding the spatial pattern of soil pH and the factors that influence it can provide basic information for generating appropriate strategies for soil resource management and protection, especially in light of increasing anthropogenic influences and climate change. In this study, we investigated the spatial and vertical pattern of soil pH and evaluated the influence of climate and nitrogen deposition using 1647 soil profiles 1 meter in depth from 549 plots in plantation forests of northern China. We found that soil pH decreased from the southwest to the northeast in the study region and had a similar spatial pattern before and after afforestation. Furthermore, our results show that climate and nitrogen deposition fundamentally influence the pattern of soil pH. Specifically, increasing precipitation significantly decreased soil pH (with a mean rate of 0.3 for every 100 mm rainfall, ppH (0.13 for every degree centigrade, ppH (ppH directly and indirectly through climate-plant-soil interactions. As the risks from both climate change and nitrogen deposition increase, there is an urgent need to further understanding of soil pH dynamics and to develop informed policies to protect soil resources.

  5. Influence of soil pH on the sorption of ionizable chemicals

    DEFF Research Database (Denmark)

    Franco, Antonio; Fu, Wenjing; Trapp, Stefan

    2009-01-01

    , the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of p......The soil-water distribution coefficient of ionizable chemicals (K-d) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K-d values normalized to organic carbon (K-OC) from the literature, a method was developed to estimate the K-OC of monovalent organic acids...

  6. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale

    DEFF Research Database (Denmark)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing

    2016-01-01

    Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples...... scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced...... scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity....

  7. The role of soil pH on soil carbonic anhydrase activity

    Science.gov (United States)

    Sauze, Joana; Jones, Sam P.; Wingate, Lisa; Wohl, Steven; Ogée, Jérôme

    2018-01-01

    Carbonic anhydrases (CAs) are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O) of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2-H2O isotopic exchange rate (kiso) in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content) affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content) played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation) that varied with soil texture. The reasons for this offset are still unknown.

  8. The role of soil pH on soil carbonic anhydrase activity

    Directory of Open Access Journals (Sweden)

    J. Sauze

    2018-01-01

    Full Text Available Carbonic anhydrases (CAs are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2–H2O isotopic exchange rate (kiso in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation that varied with soil texture. The reasons for this offset are still unknown.

  9. Influence of soil pH on the sorption of ionizable chemicals: modeling advances.

    Science.gov (United States)

    Franco, Antonio; Fu, Wenjing; Trapp, Stefan

    2009-03-01

    The soil-water distribution coefficient of ionizable chemicals (K(d)) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K(d) values normalized to organic carbon (K(OC)) from the literature, a method was developed to estimate the K(OC) of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pK(a)) and the octanol-water partition coefficient of the neutral molecule (log P(n)). Probably because of the lower pH near the organic colloid-water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals.

  10. Influence of soil-extractable aluminium and pH on the uptake of aluminium from soil into the soybean plant (Glycine max).

    Science.gov (United States)

    Dong, D; Thornton, I; Ramsey, M H

    1993-09-01

    The effects of soil pH and other soil properties on the uptake of AI by soybean plants have been investigated in a greenhouse experiment. Six soils were compared that were developed over six contrasting bedrock types ranging widely in their AI content and other chemical and physical characteristics, namely Oxford Clay, Chalk, Lower Lias Clay, Devonian Shale, Granite and Lower Greensand. Soil pH varied naturally between soil types and each soil was also amended to give two other pH levels using elemental sulphur and/or calcium carbonate. AI concentrations in various parts of the soybean plants were determined by ICP-AES after acid digestion. The AI solubility in the soils and hence its availability to the plants was estimated using a number of different reagents designed to extract different forms of AI.The AI concentration measured in the soybean leaves was found to be predicted most accurately by the 'available' AI extracted from soils by 0.02 M CaCl2. The relationship appears to the linear, with a correlation coefficient of 0.97 (p <0.01). The AI content of the leaves increases with decreasing soil pH. The relationship is non-linear with a marked increase in leaf AI for soils with pH <4.4. The amounts of 'plant-available' AI in the soils extracted with 0.02 M CaCl2 was much less than that extracted with 0.05 M EDTA, although both increased markedly with decreasing soil pH. The amount of AI measured in the soybean plants was directly related to both the 'available' forms of AI in the soils, and also to the pH of the soils. Soil pH was identified as a major factor that controls the uptake of Al from soil into the soybean plant.

  11. pH buffering capacity of acid soils from tropical and subtropical regions of China as influenced by incorporation of crop straw biochars

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ren-kou; Zhao, An-zhen; Yuan, Jin-hua; Jiang, Jun [Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture

    2012-04-15

    Purpose: The key factors influencing pH buffering capacity of acid soils from tropical and subtropical regions, and effects of soil evolution and incorporation of biochars on pH buffering capacity were investigated to develop suitable methods to increase pH buffering capacity of acid soils. Materials and methods: A total of 24 acid soils collected from southern China were used. The pH buffering capacity was determined using acid-base titration. The values of pH buffering capacity were obtained from the slope of titration curves of acid or alkali additions plotted against pH in the pH range 4.0-7.0. Two biochars were prepared from straws of peanut and canola using a low temperature pyrolysis method. After incubation of three acid soils, pH buffering capacity was then determined. Results and discussion: pH buffering capacity had a range of 9.1-32.1 mmol kg{sup -1} pH{sup -1} for 18 acid soils from tropical and subtropical regions of China. The pH buffering capacity was highly correlated (R{sup 2} = 0.707) with soil cation exchange capacity (CEC) measured with ammonium acetate method at pH 7.0 and decreased with soil evolution due to the decreased CEC. Incorporation of biochars at rates equivalent to 72 and 120 t ha{sup -1} increased soil pH buffering capacity due to the CEC contained in the biochars. Incorporation of peanut straw char which itself contained more CEC and alkalinity induced more increase in soil CEC, and thus greater increase in pH buffering capacity compared with canola straw char. At 5% of peanut straw char added, soil CEC increased by 80.2%, 51.3%, and 82.8% for Ultisol from Liuzhou, Oxisol from Chengmai and Ultisol from Kunlun, respectively, and by 19.8%, 19.6%, and 32.8% with 5% of canola straw char added, respectively; and correspondingly for these soils, the pH buffering capacity increased by 73.6%, 92.0%, and 123.2% with peanut straw char added; and by 31.3%, 25.6%, and 52.3% with canola straw char added, respectively. Protonation

  12. Effect of pH on the adsorption of carbendazim in Polish mineral soils

    International Nuclear Information System (INIS)

    Paszko, Tadeusz

    2012-01-01

    The study aimed to determine the influence of pH on the adsorption of carbendazim in soil profiles of three mineral agricultural soils: Hyperdystric Arenosol, Haplic Luvisol and Hypereutric Cambisol. In the examined pH range between 3 and 7 the adsorption of carbendazim was inversely correlated to the pH of the soil. The adsorption coefficients were in the range between 0.3 and 151.8 mL g −1 . Decreasing the pH in the soil suspensions from 7 to 3 increased the value of this coefficient by 3 to 70 times. A decrease in the amounts of organic matter down the soil profiles was not associated with weaker carbendazim adsorption. In the samples from all soil horizons, at pH values between 3 and 6, the predominant sorption process was carbendazim adsorption on clay minerals. The adsorption of carbendazim on organic matter prevailed over that on clays only at pH > 6 and only in the Ap horizon of the examined soils. The developed mathematical models yielded very good results when the adsorption of the protonated form of carbendazim was assumed to be the predominant adsorption process on clays together with the adsorption of neutral molecules on organic matter and clays. The results from both the model fitting and the experiments revealed the negative effect of Al oxides and hydroxides and Al cations on the adsorption of the protonated form of carbendazim on clay minerals. The developed models successfully described the pH-dependent adsorption processes of carbendazim for both data from particular soil horizons and those from all three examined soil profiles. -- Highlights: ► Adsorption of carbendazim in soils was inversely correlated to soil pH. ► At low pH carbendazim was adsorbed predominantly by clay minerals. ► Al 3+ influenced adsorption of the protonated form of carbendazim on clays. ► Created models predict pH-dependent sorption processes in the whole soil profiles.

  13. Water balance creates a threshold in soil pH at the global scale

    Science.gov (United States)

    Slessarev, E. W.; Lin, Y.; Bingham, N. L.; Johnson, J. E.; Dai, Y.; Schimel, J. P.; Chadwick, O. A.

    2016-12-01

    Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility—rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy. Here we evaluate the global relationship between water balance and soil pH by extracting a spatially random sample (n = 20,000) from an extensive compilation of 60,291 soil pH measurements. We show that there is an abrupt transition from alkaline to acid soil pH that occurs at the point where mean annual precipitation begins to exceed mean annual potential evapotranspiration. We evaluate deviations from this global pattern, showing that they may result from seasonality, climate history, erosion and mineralogy. These results demonstrate that climate creates a nonlinear pattern in soil solution chemistry at the global scale; they also reveal conditions under which soils maintain pH out of equilibrium with modern climate.

  14. pH dominates variation in tropical soil archaeal diversity and community structure.

    Science.gov (United States)

    Tripathi, Binu M; Kim, Mincheol; Lai-Hoe, Ang; Shukor, Nor A A; Rahim, Raha A; Go, Rusea; Adams, Jonathan M

    2013-11-01

    Little is known of the factors influencing soil archaeal community diversity and composition in the tropics. We sampled soils across a range of forest and nonforest environments in the equatorial tropics of Malaysia, covering a wide range of pH values. DNA was PCR-amplified for the V1-V3 region of the 16S rRNA gene, and 454-pyrosequenced. Soil pH was the best predictor of diversity and community composition of Archaea, being a stronger predictor than land use. Archaeal OTU richness was highest in the most acidic soils. Overall archaeal abundance in tropical soils (determined by qPCR) also decreased at higher pH. This contrasts with the opposite trend previously found in temperate soils. Thaumarcheota group 1.1b was more abundant in alkaline soils, whereas group 1.1c was only detected in acidic soils. These results parallel those found in previous studies in cooler climates, emphasizing niche conservatism among broad archaeal groups. Among the most abundant operational taxonomic units (OTUs), there was clear evidence of niche partitioning by pH. No individual OTU occurred across the entire range of pH values. Overall, the results of this study show that pH plays a major role in structuring tropical soil archaeal communities. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Solubility of lead and copper in biochar-amended small arms range soils: influence of soil organic carbon and pH.

    Science.gov (United States)

    Uchimiya, Minori; Bannon, Desmond I

    2013-08-14

    Biochar is often considered a strong heavy metal stabilizing agent. However, biochar in some cases had no effects on, or increased the soluble concentrations of, heavy metals in soil. The objective of this study was to determine the factors causing some biochars to stabilize and others to dissolve heavy metals in soil. Seven small arms range soils with known total organic carbon (TOC), cation exchange capacity, pH, and total Pb and Cu contents were first screened for soluble Pb and Cu concentrations. Over 2 weeks successive equilibrations using weak acid (pH 4.5 sulfuric acid) and acetate buffer (0.1 M at pH 4.9), Alaska soil containing disproportionately high (31.6%) TOC had nearly 100% residual (insoluble) Pb and Cu. This soil was then compared with sandy soils from Maryland containing significantly lower (0.5-2.0%) TOC in the presence of 10 wt % (i) plant biochar activated to increase the surface-bound carboxyl and phosphate ligands (PS450A), (ii) manure biochar enriched with soluble P (BL700), and (iii) unactivated plant biochars produced at 350 °C (CH350) and 700 °C (CH500) and by flash carbonization (corn). In weak acid, the pH was set by soil and biochar, and the biochars increasingly stabilized Pb with repeated extractions. In pH 4.9 acetate buffer, PS450A and BL700 stabilized Pb, and only PS450A stabilized Cu. Surface ligands of PS450A likely complexed and stabilized Pb and Cu even under acidic pH in the presence of competing acetate ligand. Oppositely, unactivated plant biochars (CH350, CH500, and corn) mobilized Pb and Cu in sandy soils; the putative mechanism is the formation of soluble complexes with biochar-borne dissolved organic carbon. In summary, unactivated plant biochars can inadvertently increase dissolved Pb and Cu concentrations of sandy, low TOC soils when used to stabilize other contaminants.

  16. Urea Fertilizer and pH Influence on Sorption Process of Flumetsulam and MCPA Acidic Herbicides in a Volcanic Soil.

    Science.gov (United States)

    Palma, Graciela; Jorquera, Milko; Demanet, Rolando; Elgueta, Sebastian; Briceño, Gabriela; de la Luz Mora, María

    2016-01-01

    The aim of this study was to evaluate the influence of urea fertilizer and pH on the sorption process of two acidic herbicides, flumetsulam (2',6'-difluoro-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonanilide) and MCPA (4-chloro--tolyloxyacetic acid), on an Andisol. Urea reduced the adsorption of MCPA but not that of flumetsulam. The Freundlich parameter of MCPA decreased from 8.5 to 5.1 mg L kg. This finding could be attributed to an increase in dissolved organic C due to an initial increase in soil pH for urea application. The higher acidic character of MCPA compared with that of flumetsulam produced a greater hydrolysis of urea, leading to a further pH increase. A marked effect of pH on the adsorption of both herbicides was observed. The organic C distribution coefficient () values for flumetsulam were in the range of 74 to 10 L kg, while those of MCPA were in the range of 208 to 45 L kg. In the kinetic studies, the pseudo-second-order model appeared to fit the data best ( > 0.994). The initial adsorption rates () ranged from 20.00 to 4.59 mg kg h for flumetsulam and from 125.00 to 25.60 mg kg hfor MCPA. Both herbicides were adsorbed rapidly during the first stage of the sorption process, and the rates of sorption were dependent on pH. The application of the Elovich and Weber-Morris models led us to conclude that mass transfer through the boundary layer and, to a lesser degree, intraparticle diffusion were influenced by the chemical character of the herbicide. These results suggest that urea application could increase leaching of acid herbicides in soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  17. Factors influencing the chemical extractability of 241Am from a contaminated soil

    International Nuclear Information System (INIS)

    Nishita, H.; Hamilton, M.

    1976-01-01

    Factors influencing the extractability of 241 Am from an artificially contaminated soil were investigated. This was done with an equilibrium batch technique using CH 3 COOH-NH 4 OH and HNO 3 -NaOH extracting systems. The influence of several soil components was determined indirectly by selectively removing them from the soil. The effect of water- and HCl-soluble salts and organic matter on 241 Am extractability was small. The most marked effect was due to the soil organic fraction that was not water- or HCl-soluble. This organic fraction was influential under both low and high pH conditions, but its influence was particularly marked under low pH conditions. The free iron-oxides had an appreciable effect under low pH conditions, but no observable effect in the high pH range. Though to a lesser extent, the free silica and alumina, amorphous alumino-silicate, and possibly residual organic matter also showed some influence. These results provide some implications on the conditions that influence the movement of 241 Am in soils and its availability to plants. A review of the literature on the behavior of Am in soils is included

  18. Laser-induced breakdown spectroscopy: Extending its application to soil pH measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Gomes Neto, José A. [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Milori, Débora M.B.P.; Ferreira, Ednaldo José [Embrapa Agricultural Instrumentation, Rua XV de Novembro 1452, CEP 13560-970, São Carlos, SP (Brazil); Anzano, Jesús Manuel [Laser Laboratory & Environment, Faculty of Sciences, University of Zaragoza, C/. Pedro Cerbuna 12, 50009, Zaragoza (Spain)

    2015-08-01

    Acid–base equilibria are involved in almost all the processes that occur in soil. The bioavailability of nutrients for plants, for instance, depends on the solubilization of mineral nutrients in the soil solution, which is a pH-dependent process. The determination of pH in soil solutions is usually carried out by potentiometry using a glass membrane electrode, after extracting some of the soil components with water or CaCl{sub 2} solution. The present work describes a simple method for determining the pH of soil, using laser-induced breakdown spectroscopy (LIBS). Sixty samples presenting different textural composition and pH (previously determined by potentiometry) were employed. The samples were divided into a calibration set with fifty samples and a validation set with ten samples. LIBS spectra were recorded for each pelleted sample using laser pulse energy of 115 mJ. The intensities of thirty-two emission lines for Al, Ca, H, and O were used to fit a partial least squares (PLS) model. The model was validated by prediction of the pH of the validation set samples, which showed good agreement with the reference values. The prediction mean absolute error was 0.3 pH units and the root mean square error of the prediction was 0.4. These results highlight the potential of LIBS for use in other applications beyond elemental composition determinations. For soil analysis, the proposed method offers the possibility of determining pH, in addition to nutrients and contaminants, using a single LIBS measurement. - Highlights: • Physical, chemical, and biological properties of soil are influenced by pH. • The pH of mineral soils is normally determined in slurries of water and soil sample by potentiometric measurements. • The association of LIBS elemental emissions with multivariate strategies of analysis has become LIBS a powerful technique. • LIBS was unprecedentedly applied for direct pH determination in different kinds of soil sample. • The clean and fast proposed

  19. Fate of cadmium at the soil-solution interface: a thermodynamic study as influenced by varying pH at South 24 Parganas, West Bengal, India.

    Science.gov (United States)

    Karak, Tanmoy; Paul, Ranjit Kumar; Das, Sampa; Das, Dilip K; Dutta, Amrit Kumar; Boruah, Romesh K

    2015-11-01

    A study on the sorption kinetics of Cd from soil solution to soils was conducted to assess the persistence of Cd in soil solution as it is related to the leaching, bioavailability, and potential toxicity of Cd. The kinetics of Cd sorption on two non-contaminated alkaline soils from Canning (22° 18' 48.02″ N and 88° 39' 29.0″ E) and Lakshmikantapur (22° 06' 16.61″ N and 88° 19' 08.66″ E) of South 24 Parganas, West Bengal, India, were studied using conventional batch experiment. The variable soil suspension parameters were pH (4.00, 6.00, 8.18, and 9.00), temperatures (308, 318, and 328 K) and Cd concentrations (5-100 mg L(-1)). The average rate coefficient (kavg) and half-life (t1/2) values indicate that the persistence of Cd in soil solution is influenced by both temperature and soil suspension pH. The concentration of Cd in soil solution decreases with increase of temperature; therefore, Cd sorption on the soil-solution interface is an endothermic one. Higher pH decreases the t 1/2 of Cd in soil solution, indicating that higher pH (alkaline) is not a serious concern in Cd toxicity than lower pH (acidic). Based on the energy of activation (Ea) values, Cd sorption in acidic pH (14.76±0.29 to 64.45±4.50 kJ mol(-1)) is a surface control phenomenon and in alkaline pH (9.33±0.09 to 44.60±2.01 kJ mol(-1)) is a diffusion control phenomenon The enthalpy of activation (ΔH∓) values were found to be between 7.28 and 61.73 kJ mol(-1). Additionally, higher positive energy of activation (ΔG∓) values (46.82±2.01 to 94.47±2.36 kJ mol(-1)) suggested that there is an energy barrier for product formation.

  20. Soil components that influence the chemical behavior of 239Pu

    International Nuclear Information System (INIS)

    Nishita, H.; Hamilton, M.

    1978-08-01

    Soil components that influence the extractability of 239 Pu from an artificially contaminated kaolinitic soil in relation to pH have been examined. This was done by using an equilibrium batch technique with CH 3 COOH--NH 4 OH and HNO 3 --NaOH extracting systems. Soil organic matter and free iron oxides had an appreciable effect depending on the pH and the extracting system. The free silica and alumina and amorphous alumino-silicates had lesser influence. With the untreated soil (control), the CH 3 COOH--NH 4 OH system generally extracted more 239 Pu than did the HNO 3 --NaOH system in the acidic pH range, whereas the latter system extracted markedly greater amounts of it in the alkaline pH range. With the soil from which the organic matter was removed, the CH 3 COOH--NH 4 OH system extracted appreciably greater amounts of 239 Pu than the HNO 3 --NaOH system in the acidic pH range, but there was only little, if any, difference between the two extracting systems in the alkaline pH range. The causes and the implications of these results are discussed

  1. Fluctuations in ammonia oxidizing communities across agricultural soils are driven by soil structure and pH

    Directory of Open Access Journals (Sweden)

    Michele C ePereira e Silva

    2012-03-01

    Full Text Available The milieu in soil in which microorganisms dwell is never constant. Conditions such as temperature, water availability, pH and nutrients frequently change, impacting the overall functioning of the soil system. To understand the effects of such factors on soil functioning, proxies (indicators of soil function are needed that, in a sensitive manner, reveal normal amplitude of variation. Thus, the so-called normal operating range (NOR of soil can be defined. In this study we determined different components of nitrification by analyzing, in eight agricultural soils, how the community structures and sizes of ammonia oxidizing bacteria and archaea (AOB and AOA, respectively, and their activity, fluctuate over spatial and temporal scales. The results indicated that soil pH and soil type are the main factors that influence the size and structure of the AOA and AOB, as well as their function. The nitrification rates varied between 0.11 ± 0.03 µgN.h-1.gdw-1 and 1.68 ± 0.11 µgN.h-1.gdw-1, being higher in soils with higher clay content (1.09 ± 0.12 µgN.h-1.gdw-1 and lower in soils with lower clay percentages (0.27 ± 0.04 µgN.h-1.gdw-1. Nitrifying activity was driven by soil pH, mostly related to its effect on AOA but not on AOB abundance. Regarding the influence of soil parameters, clay content was the main soil factor shaping the structure of both the AOA and AOB communities. Overall, the potential nitrifying activities were higher and more variable over time in the clayey than in the sandy soils. Whereas the structure of AOB fluctuated more (62.7 ± 2.10% the structure of AOA communities showed lower amplitude of variation (53.65 ± 3.37%. Similar trends were observed for the sizes of these communities. The present work represents a first step towards defining a NOR for soil nitrification. Moreover, the clear effect of soil texture established here suggests that the NOR should be defined in a soil-type-specific manner.

  2. Influence of soil pH on the toxicity of zinc oxide nanoparticles to the terrestrial isopod Porcellionides pruinosus.

    Science.gov (United States)

    Tourinho, Paula S; van Gestel, Cornelis A M; Lofts, Stephen; Soares, Amadeu M V M; Loureiro, Susana

    2013-12-01

    The effects of soil pH on the toxicity of ZnO nanoparticles (NPs) to the terrestrial isopod Porcellionides pruinosus were evaluated. Isopods were exposed to a natural soil amended with CaCO3 to reach 3 different pH(CaCl2) levels (4.5, 6.2, and 7.3) and to standard LUFA 2.2 soil (pH 5.5) spiked with ZnO NPs (30 nm), non-nano ZnO (200 nm), and ionic Zn as ZnCl₂. Toxicity was expressed based on total Zn concentration in soil, as well as total Zn and free Zn²⁺ ion concentrations in porewater. Compared with ZnO-spiked soils, the ZnCl₂-spiked soils had lower pH and higher porewater Ca²⁺ and Zn levels. Isopod survival did not differ between Zn forms and soils, but survival was higher for isopods exposed to ZnO NPs at pH 4.5. Median effect concentrations (EC50s) for biomass change showed similar trends for all Zn forms in all soils, with higher values at intermediate pH. Median lethal concentration (LC50) and EC50 values based on porewater Zn or free Zn ion concentrations were much lower for ZnO than for ionic zinc. Zn body concentrations increased in a dose-related manner, but no effect of soil pH was found. It is suggested not only that dissolved or free Zn in porewater contributed to uptake and toxicity, but also that oral uptake (i.e., ingestion of soil particles) could be an important additional route of exposure. © 2013 SETAC.

  3. Influence of Microsprinkler Irrigation Amount on Water, Soil, and pH Profiles in a Coastal Saline Soil

    Directory of Open Access Journals (Sweden)

    Linlin Chu

    2014-01-01

    Full Text Available Microsprinkler irrigation is a potential method to alleviate soil salinization. After conducting a homogeneous, highly saline, clayey, and coastal soil from the Bohai Gulf in northern China in a column experiment, the results show that the depth of the wetting front increased as the water amount applied increased, low-salinity and low-SAR enlarged after irrigation and water redistribution, and the soil pH increased with an increase in irrigation amount. We concluded that a water amount of 207 mm could be used to reclaim the coastal saline soil in northern China.

  4. Labile pools of Pb in vegetable-growing soils investigated by an isotope dilution method and its influence on soil pH.

    Science.gov (United States)

    Xie, Hong; Huang, Zhi-Yong; Cao, Ying-Lan; Cai, Chao; Zeng, Xiang-Cheng; Li, Jian

    2012-08-01

    Pollution of Pb in the surface of agricultural soils is of increasing concern due to its serious impact on the plant growth and the human health through the food chain. However, the mobility, activity and bioavailability of Pb rely mainly on its various chemical species in soils. In the present study, E and L values, the labile pools of isotopically exchangeable Pb, were estimated using the method of isotope dilution in three vegetable-growing soils. The experiments involved adding a stable enriched isotope ((206)Pb > 96%) to a soil suspension and to soils in which plants are subsequently grown, the labile pools of Pb were then estimated by measuring the isotopic composition of Pb in soil solutions and in the plant tissues, respectively. In addition, the correlation of E values and soil pH was investigated at the ranges of pH 4.5-7.0. The amount of labile Pb in soils was also estimated using different single chemical extractants and a modified BCR approach. The results showed that after spiking the enriched isotopes of (206)Pb (>96%) for 24 hours an equilibration of isotopic exchanges in soil suspensions was achieved, and the isotope ratios of (208)Pb/(206)Pb measured at that time was used for calculating the E(24 h) values. The labile pools of Pb by %E(24 h) values, ranging from 53.2% to 61.7% with an average 57%, were found to be significantly higher (p soil pH was found in the tested soil sample. The results indicate that the %E(24 h) value can more rapidly and easily predict the labile pools of Pb in soils compared with L values, but it might be readily overestimated because of the artificial soil acidity derived from the spiked isotopic tracer and the excess of spiked enriched isotopes. The results also suggest that the amounts of Pb extracted with EDTA and the Σ(BCR) values extracted with the modified BCR approach are helpful to detect the labile pools of Pb in soils. In addition, the negative correlation between soil pH and the labile pools of Pb in soils

  5. Relative influence of soil chemistry and topography on soil available micronutrients by structural equation modeling

    OpenAIRE

    Zhu, Hongfen; Zhao, Ying; Nan, Feng; Duan, Yonghong; Bi, Rutian

    2016-01-01

    Soil chemical and topographic properties are two important factors influencing available micronutrient distribution of soil in the horizontal dimension. The objective of this study was to explore the relative influence of soil chemistry (including soil pH, soil organic matter, total nitrogen, available phosphorus, and available potassium) and topography (including elevation, slope, aspect, and wetness index) on the availability of micronutrients (Fe, Mn, Cu, Zn, and B) using structural equati...

  6. Influence of indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils: a rhizobox study.

    Science.gov (United States)

    Kim, Kwon-Rae; Owens, Gary; Kwon, Soon-lk

    2010-01-01

    This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils (two alkaline soils and two acidic soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic soils and only a slight increase (soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.

  7. Data on soil PH of Barddhaman district, India

    Directory of Open Access Journals (Sweden)

    Sumanta Bid

    2017-06-01

    Full Text Available PH (Puissance de Hydrogen is an essential ingredient of soil that effects on fertility and productivity of dirt. Barddhaman district is a part of Lower Gangetic Plain fully covered by alluvial soil and popularly known as ‘rice bowl of West Bengal’ owing to its lofty production. This data article provides a block level data on soil PH that is essential for further investigation of the relationship among soil ph, plant growth, plant health and productivity. This data is valuable in the field of soil geography and soil science. Soil PH data is more relevant in the ground of plant biology, agricultural geography and agricultural science. It helps to explain the acidic and alkaline nature of alluvial soil. The data consist of 195 samples (n=195 taken from the entire district. Samples have been collected from March, 2014 to March, 2015 and experimented in the laboratory. Theoretically PH value is limited within 0–14. Experiment result exemplifies the highest value 8.5 found in Khandaghosh block whereas lowest value is 4.5 and the samples which result in lowest value are gathered from 4 different blocks like Manteswar, Burdwan - II, Barabani and Salanpur.

  8. Biochar contribution to soil pH buffer capacity

    Science.gov (United States)

    Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

    2014-05-01

    Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

  9. Plant species influence on soil C after afforestation of Mediterranean degraded soils

    Science.gov (United States)

    Dominguez, Maria T.; García-Vargas, Carlos; Madejón, Engracia; Marañón, Teodoro

    2015-04-01

    Increasing C sequestration in terrestrial ecosystems is one of the main current environmental challenges to mitigate climate change. Afforestation of degraded and contaminated lands is one of the key strategies to achieve an increase in C sequestration in ecosystems. Plant species differ in their mechanisms of C-fixation, C allocation into different plant organs, and interaction with soil microorganisms, all these factors influencing the dynamics of soil C following the afforestation of degraded soils. In this work we examine the influence of different woody plant species on soil C dynamics in degraded and afforested Mediterranean soils. The soils were former agricultural lands that were polluted by a mining accident and later afforested with different native plant species. We analysed the effect of four of these species (Olea europaea var. sylvestris Brot., Populus alba L., Pistacia lentiscus L. and Retama sphaerocarpa (L.) Boiss.) on different soil C fractions, soil nutrient availability, microbial activity (soil enzyme activities) and soil CO2 fluxes 15 years after the establishment of the plantations. Results suggest that the influence of the planted trees and shrubs is still limited, being more pronounced in the more acidic and nutrient-poor soils. Litter accumulation varied among species, with the highest C accumulated in the litter under the deciduous species (Populus alba L.). No differences were observed in the amount of total soil organic C among the studied species, or in the concentrations of phenols and sugars in the dissolved organic C (DOC), which might have indicated differences in the biodegradability of the DOC. Microbial biomass and activity was highly influenced by soil pH, and plant species had a significant influence on soil pH in the more acidic site. Soil CO2 fluxes were more influenced by the plant species than total soil C content. Our results suggest that changes in total soil C stocks after the afforestation of degraded Mediterranean

  10. Influence of pH of acid irrigation water on the transfer of elements into rice plant from soils

    International Nuclear Information System (INIS)

    Maeno, Tomokazu; Tanizaki, Yoshiyuki

    1996-01-01

    Rice plant samples were grown in 14 cultivative pots under six different pH conditions of acid irrigation water (pH: 6.5, 6.0, 4.5, 3.5, 3.0. 2.5) and ion exchange water (pH: 7.5), in order to study an influence of pH of irrigation water on the transfer of elements into rice plant from soils. The acid irrigation water was prepared by adding mixed solution of 1N H 2 SO 4 and 1N HNO 3 (1:1) to ion exchange water. The rice grain yielded was separated into three parts, i.e., polished rice, bran and chaff and they were powdered one by one. The contents of twenty five elements in the three parts of grain (14 samples each) were determined by a neutron activation analysis. It was clarified that the contents of Cu, Zn, Fe, Cr, Mg, Rb, Mo, Ni, and Cs in the polished rice increased with decreasing pH of the acid irrigation water. The contents of Se and Br, on the contrary, decreased. Significant changes of the contents were not observed for Na, Al, Sc, Mn, Cl, Ca, V and Co. The relationships between the contents of elements in the bran or chaff and pH of the acid irrigation water were not so clear as the case of polished rice. The enrichment factor of trace elements from soils was calculated for the polished rice, bran and chaff The high enrichment of Cl, Mo, Zn, Se and Cu was observed in the polished rice. Manganese and Cr were concentrated more in the bran than in the polished rice. (author)

  11. Copper availability and bioavailability are controlled by rhizosphere pH in rape grown in an acidic Cu-contaminated soil

    International Nuclear Information System (INIS)

    Chaignon, Valerie; Quesnoit, Marie; Hinsinger, Philippe

    2009-01-01

    We evaluated how root-induced changes in rhizosphere pH varied and interacted with Cu availability and bioavailability in an acidic soil. Rape was grown on a Cu-contaminated acidic soil, which had been limed at 10 rates. Soil Cu bioavailability was not influenced by liming. However, liming significantly decreased CaCl 2 -extracted Cu for pH between 3.7 and 5.1. Little effect was found for pH above 5.1. For soil pH 2 -Cu contents were smaller in rhizosphere than uncropped soil. Rhizosphere alkalisation occurred at pH 2 -Cu in the rhizosphere at low pH and the absence of pH dependency of Cu bioavailability to rape. In addition, apoplastic Cu in roots increased with increasing soil pH, most probably as a result of increased dissociation and affinity of cell wall compounds for Cu. - Root-induced increase in pH reduces Cu availability in the rhizosphere and Cu bioavailability to rape.

  12. Copper availability and bioavailability are controlled by rhizosphere pH in rape grown in an acidic Cu-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Chaignon, Valerie; Quesnoit, Marie [INRA, UMR 1222 Eco and Sols Ecologie fonctionnelle and Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Hinsinger, Philippe, E-mail: philippe.hinsinger@supagro.inra.f [INRA, UMR 1222 Eco and Sols Ecologie fonctionnelle and Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France)

    2009-12-15

    We evaluated how root-induced changes in rhizosphere pH varied and interacted with Cu availability and bioavailability in an acidic soil. Rape was grown on a Cu-contaminated acidic soil, which had been limed at 10 rates. Soil Cu bioavailability was not influenced by liming. However, liming significantly decreased CaCl{sub 2}-extracted Cu for pH between 3.7 and 5.1. Little effect was found for pH above 5.1. For soil pH < 4.4, CaCl{sub 2}-Cu contents were smaller in rhizosphere than uncropped soil. Rhizosphere alkalisation occurred at pH < 4.8, while acidification occurred at greater pH. This explained the changes of CaCl{sub 2}-Cu in the rhizosphere at low pH and the absence of pH dependency of Cu bioavailability to rape. In addition, apoplastic Cu in roots increased with increasing soil pH, most probably as a result of increased dissociation and affinity of cell wall compounds for Cu. - Root-induced increase in pH reduces Cu availability in the rhizosphere and Cu bioavailability to rape.

  13. A statistically based mapping of the influence of geology and land use on soil pH

    DEFF Research Database (Denmark)

    Balstrøm, Thomas; Breuning-Madsen, Henrik; Krüger, Johannes

    2013-01-01

    . The data have been analysed using statistical spatial analysis methods, and a model has been erected demonstrating areas of homogeneous low, high, or inhomogeneous pH values relative to deposits from different ice advances and regional variations in land use. The investigation shows that the major part......The purpose of this paper is to investigate the geographical distribution of pH values in Danish soils of different ages representing the main Saalian and Weichselian ice advances. The investigation is based on soil sampling from top- and subsoils in soil profiles located in a nationwide 7-km grid...... of Jutland is characterized by low pH values in the topsoils and subsoils compared to the islands east of the peninsula. This corresponds with the maximum extension of the Weichselian Young Baltic Ice Cap. A Hot Spot analysis carried out on regional and local scales shows that most of the Danish islands form...

  14. Zinc fractionation in contaminated soils by sequential and single extractions: influence of soil properties and zinc content.

    Science.gov (United States)

    Voegelin, Andreas; Tokpa, Gerome; Jacquat, Olivier; Barmettler, Kurt; Kretzschmar, Ruben

    2008-01-01

    We studied the fractionation of zinc (Zn) in 49 contaminated soils as influenced by Zn content and soil properties using a seven-step sequential extraction procedure (F1: NH4NO3; F2: NH4-acetate, pH 6; F3: NH3OHCl, pH 6; F4: NH4-EDTA, pH 4.6; F5: NH4-oxalate, pH 3; F6: NH4-oxalate/ascorbic acid, pH 3; F7: residual). The soils had developed from different geologic materials and covered a wide range in soil pH (4.0-7.3), organic C content (9.3-102 g kg(-1)), and clay content (38-451 g kg(-1)). Input of aqueous Zn with runoff water from electricity towers during 26 to 74 yr resulted in total soil Zn contents of 3.8 to 460 mmol kg(-1). In acidic soils (n = 24; pH soils (n = 25; pH > or =6.0), most Zn was extracted in the mobilizable fraction (F2) and the intermediate fractions (F4 and F5). The extractability of Zn increased with increasing Zn contamination of the soils. The sum of mobile (F1) and mobilizable (F2) Zn was independent of soil pH, the ratio of Zn in F1 over F1+F2 plotted against soil pH, exhibited the typical shape of a pH sorption edge and markedly increased from pH 6 to pH 5, reflecting the increasing lability of mobilizable Zn with decreasing soil pH. In conclusion, the extractability of Zn from soils contaminated with aqueous Zn after decades of aging under field conditions systematically varied with soil pH and Zn content. The same trends are expected to apply to aqueous Zn released from decomposing Zn-bearing contaminants, such as sewage sludge or smelter slag. The systematic trends in Zn fractionation with varying soil pH and Zn content indicate the paramount effect of these two factors on molecular scale Zn speciation. Further research is required to characterize the link between the fractionation and speciation of Zn and to determine how Zn loading and soil physicochemical properties affect Zn speciation in soils.

  15. Soil pH Mapping with an On-The-Go Sensor

    OpenAIRE

    Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

    2011-01-01

    Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH ManagerTM, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH ManagerTM under ...

  16. The influence of pH and organic matter content in paddy soil on heavy metal availability and their uptake by rice plants

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Fanrong; Ali Shafaqat; Zhang Haitao [Department of Agronomy, College of Agriculture and Biotechnology, Huajiachi Campus, Zhejiang University, Hangzhou 310029 (China); Ouyang Younan [China National Rice Research Institute, Fuyang 310041 (China); Qiu Boyin; Wu Feibo [Department of Agronomy, College of Agriculture and Biotechnology, Huajiachi Campus, Zhejiang University, Hangzhou 310029 (China); Zhang Guoping, E-mail: zhanggp@zju.edu.c [China National Rice Research Institute, Fuyang 310041 (China)

    2011-01-15

    The experiments were done to investigate the effect of soil pH and organic matter content on EDTA-extractable heavy metal contents in soils and heavy metal concentrations in rice straw and grains. EDTA-extractable Cr contents in soils and concentrations in rice tissues were negatively correlated with soil pH, but positively correlated with organic matter content. The combination of soil pH and organic matter content would produce the more precise regression models for estimation of EDTA-Cu, Pb and Zn contents in soils, demonstrating the distinct effect of the two factors on the availability of these heavy metals in soils. Soil pH greatly affected heavy metal concentrations in rice plants. Furthermore, inclusion of other soil properties in the stepwise regression analysis improved the regression models for predicting straw Fe and grain Zn concentrations, indicating that other soil properties should be taken into consideration for precise predicting of heavy metal concentrations in rice plants. - Soil pH and organic matter content significantly affect heavy metal availability and accumulation in rice plants.

  17. In situ measurements reveal extremely low pH in soil

    DEFF Research Database (Denmark)

    Nielsen, Knud Erik; Loibide, Amaia Irixar; Nielsen, Lars Peter

    2017-01-01

    We measured pH in situ in the top organic soil horizons in heathland and pine forest and found values between 2.6 and 3.2. This was 0.5e0.8 units lower than concurrent laboratory pH measurements of the same soil, which raises questions about the interpretation of pH measurements. We propose that ...... that the higher pH recorded by standard laboratory methods may be due to buffering ions from soil biota released from drying, grinding and rewetting of soil samples, whereas the in situ pH reflects the correct level of acidification....

  18. In vitro digestion and DGT techniques for estimating cadmium and lead bioavailability in contaminated soils: Influence of gastric juice pH

    International Nuclear Information System (INIS)

    Pelfrene, Aurelie; Waterlot, Christophe; Douay, Francis

    2011-01-01

    A sensitivity analysis was conducted on an in vitro gastrointestinal digestion test (i) to investigate the influence of a low variation of gastric juice pH on the bioaccessibility of Cd and Pb in smelter-contaminated soils (F B , using the unified bioaccessibility method UBM) and fractions of metals that may be transported across the intestinal epithelium (F A , using the diffusive gradient in thin film technique), and (ii) to provide a better understanding of the significance of pH in health risk assessment through ingestion of soil by children. The risk of metal exposure to children (hazard quotient, HQ) was determined for conditions that represent a worst-case scenario (i.e., ingestion rate of 200 mg day -1 ) using three separate calculations of metal daily intake: estimated daily intake (EDI), bioaccessible EDI (EDI-F B ), and oral bioavailable EDI (EDI-F A ). The increasing pH from 1.2 to 1.7 resulted in: (i) no significant variation in Cd-F B in the gastric phase but a decrease in the gastrointestinal phase; (ii) a decrease in soluble Pb in the gastric phase and a significant variation in Pb-F B in the gastrointestinal phase; (iii) a significant decrease in Cd-F A and no variation in Pb-F A ; (iv) no change in EDI-F B and EDI-F A HQs for Cd; (v) a significant decrease in EDI-F B HQs and no significant variation in EDI-F A HQ for Pb. In the analytical conditions, these results show that risk to children decreases when the bioavailability of Pb in soils is taken into account and that the studied pH values do not affect the EDI-F A HQs. The present results provide evidence that the inclusion of bioavailability analysis during health risk assessment could provide a more realistic estimate of Cd and Pb exposure, and opens a wide field of practical research on this topic (e.g., in contaminated site management). - Highlights: → Sensitivity analysis on an in vitro gastrointestinal digestion test. → Influence of gastric juice pH on metal bioaccessibility

  19. In vitro digestion and DGT techniques for estimating cadmium and lead bioavailability in contaminated soils: Influence of gastric juice pH

    Energy Technology Data Exchange (ETDEWEB)

    Pelfrene, Aurelie, E-mail: aurelie.pelfrene@isa-lille.fr [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geo-Environnement (LGCgE) Lille Nord de France (EA 4515), 48 boulevard Vauban, 59046 Lille cedex (France); Waterlot, Christophe; Douay, Francis [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geo-Environnement (LGCgE) Lille Nord de France (EA 4515), 48 boulevard Vauban, 59046 Lille cedex (France)

    2011-11-01

    A sensitivity analysis was conducted on an in vitro gastrointestinal digestion test (i) to investigate the influence of a low variation of gastric juice pH on the bioaccessibility of Cd and Pb in smelter-contaminated soils (F{sub B}, using the unified bioaccessibility method UBM) and fractions of metals that may be transported across the intestinal epithelium (F{sub A}, using the diffusive gradient in thin film technique), and (ii) to provide a better understanding of the significance of pH in health risk assessment through ingestion of soil by children. The risk of metal exposure to children (hazard quotient, HQ) was determined for conditions that represent a worst-case scenario (i.e., ingestion rate of 200 mg day{sup -1}) using three separate calculations of metal daily intake: estimated daily intake (EDI), bioaccessible EDI (EDI-F{sub B}), and oral bioavailable EDI (EDI-F{sub A}). The increasing pH from 1.2 to 1.7 resulted in: (i) no significant variation in Cd-F{sub B} in the gastric phase but a decrease in the gastrointestinal phase; (ii) a decrease in soluble Pb in the gastric phase and a significant variation in Pb-F{sub B} in the gastrointestinal phase; (iii) a significant decrease in Cd-F{sub A} and no variation in Pb-F{sub A}; (iv) no change in EDI-F{sub B} and EDI-F{sub A} HQs for Cd; (v) a significant decrease in EDI-F{sub B} HQs and no significant variation in EDI-F{sub A} HQ for Pb. In the analytical conditions, these results show that risk to children decreases when the bioavailability of Pb in soils is taken into account and that the studied pH values do not affect the EDI-F{sub A} HQs. The present results provide evidence that the inclusion of bioavailability analysis during health risk assessment could provide a more realistic estimate of Cd and Pb exposure, and opens a wide field of practical research on this topic (e.g., in contaminated site management). - Highlights: {yields} Sensitivity analysis on an in vitro gastrointestinal digestion test

  20. Leaching characteristics of toxic constituents from coal fly ash mixed soils under the influence of pH

    Energy Technology Data Exchange (ETDEWEB)

    Komonweeraket, Kanokwan [Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706 (United States); Cetin, Bora, E-mail: bora.cetin@sdsmt.edu [College of Engineering, University of Georgia, Athens, GA 30602 (United States); Benson, Craig H., E-mail: chbenson@wisc.edu [Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706 (United States); Aydilek, Ahmet H., E-mail: aydilek@umd.edu [Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742 (United States); Edil, Tuncer B., E-mail: edil@engr.wisc.edu [Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706 (United States)

    2015-04-15

    Highlights: • The impact of pH on the leaching of elements and metals from fly ash mixed soils. • Generally Ca, Cd, Mg, and Sr follows a cationic leaching pattern. • The leaching of As and Se shows an oxyanionic leaching pattern. • The leaching behavior of elements does not change based on material type. • Different fly ash types show different abilities in immobilizing trace elements. - Abstract: Leaching behaviors of Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Magnesium (Mg), Selenium (Se), and Strontium (Sr) from soil alone, coal fly ash alone, and soil-coal fly ash mixtures, were studied at a pH range of 2–14 via pH-dependent leaching tests. Seven different types of soils and coal fly ashes were tested. Results of this study indicated that Ca, Cd, Mg, and Sr showed cationic leaching pattern while As and Se generally follows an oxyanionic leaching pattern. On the other hand, leaching of Ba presented amphoteric-like leaching pattern but less pH-dependent. In spite of different types and composition of soil and coal fly ash investigated, the study reveals the similarity in leaching behavior as a function of pH for a given element from soil, coal fly ash, and soil-coal fly ash mixtures. The similarity is most likely due to similar controlling mechanisms (e.g., solubility, sorption, and solid-solution formation) and similar controlling factors (e.g., leachate pH and redox conditions). This offers the opportunity to transfer knowledge of coal fly ash that has been extensively characterized and studied to soil stabilized with coal fly ash. It is speculated that unburned carbon in off-specification coal fly ashes may provide sorption sites for Cd resulting in a reduction in concentration of these elements in leachate from soil-coal fly ash mixture. Class C fly ash provides sufficient CaO to initiate the pozzolanic reaction yielding hydrated cement products that oxyanions, including As and Se, can be incorporated into.

  1. Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

    International Nuclear Information System (INIS)

    Devau, Nicolas; Cadre, Edith Le; Hinsinger, Philippe; Jaillard, Benoit; Gerard, Frederic

    2009-01-01

    Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl 2 (P-CaCl 2 ) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH ∼ 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R 2 = 0.9, RMSE = 0.03 mg kg -1 ). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl 2 with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional contribution of soil organic matter.

  2. Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

    Energy Technology Data Exchange (ETDEWEB)

    Devau, Nicolas [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Cadre, Edith Le [Supagro, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Hinsinger, Philippe; Jaillard, Benoit [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Gerard, Frederic, E-mail: gerard@supagro.inra.fr [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France)

    2009-11-15

    Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl{sub 2} (P-CaCl{sub 2}) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH {approx} 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R{sup 2} = 0.9, RMSE = 0.03 mg kg{sup -1}). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl{sub 2} with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional

  3. Effect of soil organic matter content and pH on the toxicity of ZnO nanoparticles to Folsomia candida.

    Science.gov (United States)

    Waalewijn-Kool, Pauline L; Rupp, Svenja; Lofts, Stephen; Svendsen, Claus; van Gestel, Cornelis A M

    2014-10-01

    Organic matter (OM) and pH may influence nanoparticle fate and effects in soil. This study investigated the influence of soil organic matter content and pH on the toxicity of ZnO-NP and ZnCl2 to Folsomia candida in four natural soils, having between 2.37% and 14.7% OM and [Formula: see text] levels between 5.0 and 6.8. Porewater Zn concentrations were much lower in ZnO-NP than in ZnCl2 spiked soils, resulting in higher Freundlich sorption constants for ZnO-NP. For ZnCl2 the porewater Zn concentrations were significantly higher in less organic soils, while for ZnO-NP the highest soluble Zn level (23mgZn/l) was measured in the most organic soil, which had the lowest pH. Free Zn(2+) ion concentrations were higher for ZnCl2 than for ZnO-NP and were greatly dependent on pH (pHpw) and dissolved organic carbon content of the pore water. The 28-d EC50 values for the effect of ZnCl2 on the reproduction of F. candida increased with increasing OM content from 356 to 1592mgZn/kg d.w. For ZnO-NP no correlation between EC50 values and OM content was found and EC50 values ranged from 1695 in the most organic soil to 4446mgZn/kg d.w. in the higher pH soil. When based on porewater and free Zn(2+) concentrations, EC50 values were higher for ZnCl2 than for ZnO-NP, and consistently decreased with increasing pHpw. This study shows that ZnO-NP toxicity is dependent on soil properties, but is mainly driven by soil pH. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Seasonal Belowground Ecosystem and Eco-enzymatic Responses to Soil pH and Phosphorus Availability in Temperate Hardwood Forests

    Science.gov (United States)

    Smemo, K. A.; Deforest, J. L.; Petersen, S. L.; Burke, D.; Hewins, C.; Kluber, L. A.; Kyker, S. R.

    2013-12-01

    Atmospheric acid deposition can increase phosphorus (P) limitation in temperate hardwood forests by increasing N availability, and therefore P demand, and/or by decreasing pH and occluding inorganic P. However, only recently have studies demonstrated that P limitation can occur in temperate forests and very little is known about the temporal aspects of P dynamics in acidic forest soils and how seasonal shifts in nutrient availability and demand influence microbial investment in extracellular enzymes. The objectives of this study were to investigate how P availability and soil pH influence seasonal patterns of nutrient cycling and soil microbial activity in hardwood forests that experience chronic acid deposition. We experimentally manipulated soil pH, P, or both for three years and examined soil treatment responses in fall, winter, spring, early summer, and late summer. We found that site (glaciated versus unglaciated) and treatment had the most significant influence on nutrient pools and cycling. In general, nutrient pools were higher in glaciated soils than unglaciated for measured nutrients, including total C and N (2-3 times higher), extractable inorganic nitrogen, and readily available P. Treatment had no impact on total C and N pools in either region, but did affect other measured nutrients such as ammonium, which was greatest in the elevated pH treatment for both sites. As expected, readily available P pools were highest in the elevated P treatments (3 fold increase in both sites), but raising pH decreased available P pools in the glaciated site. Raising soil pH increased both net N mineralization rates and net P mineralization rates, regardless of site. Nitrification responses were complex, but we observed an overall significant nitrification increase under elevated pH, particularly in the growing season. Extracellular enzyme activity showed more seasonal patterns than site and treatment effects, exhibiting significant growing season activity reductions for

  5. Effect of acid rain pH on leaching behavior of cement stabilized lead-contaminated soil.

    Science.gov (United States)

    Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Liu, Zhao-Peng; Jin, Fei

    2014-04-30

    Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. SPATIAL AND TEMPORAL PATTERN OF SOIL pH AND Eh AND THEIR IMPACT ON SOLUTE IRON CONTENT IN A WETLAND (TRANSDANUBIA, HUNGARY

    Directory of Open Access Journals (Sweden)

    SZALAI ZOLTÁN

    2008-06-01

    Full Text Available Land mosaics have direct and indirect influence on chemical reaction and redox condition of soils. The present paper deals with the relationship between some environmental factors (such as soil andvegetation patterns, micro-relief, water regime, temperature and incident solar radiation and the pH, Eh of soils and solute iron in a headwater wetland in Transdanubia, Hungary. Measurements have been taken in four different patches and along their boundaries: sedge (Carex vulpina, Carex riparia, three patches and two species, horsetail (Equisetum arvense, common nettle (Urtica dioica. Thespatial pattern of the studied parameters are influenced by the water regime, micro-topography, climatic conditions and by direct and indirect effects of vegetation. The indirect effect can be the shading, which has influence on soil temperature and on the incident solar radiation (PAR. Root respiration and excretion of organic acids appear as direct effects.. There have been measured individual pH and Eh characteristic in the studied patches. Soil Eh, pH and solute iron have shown seasonal dynamics. Higher redox potentials (increasingly oxidative conditions and higher pH values were measured between late autumn and early spring. The increasing physiological activity of plants causes lower pH and Eh and it leads to higher spatial differences. Although temperature is an essential determining factor for Eh and pH, but our results suggest it rather has indirect effectsthrough plants on wetlands.

  7. Flooding-induced N2O emission bursts controlled by pH and nitrate in agricultural soils

    DEFF Research Database (Denmark)

    Hansen, Mette; Clough, Tim J.; Elberling, Bo

    2014-01-01

    emissions is poorly studied for agricultural systems. The overall N2O dynamics during flooding of an agricultural soil and the effect of pH and NO3− concentration has been investigated based on a combination of the use of microsensors, stable isotope techniques, KCl extractions and modelling. This study...... within the soil. The magnitude of the emissions are, not surprisingly, positively correlated with the soil NO3− concentration but also negatively correlated with liming (neutral pH). The redox potential of the soil is found to influence N2O accumulation as the production and consumption of N2O occurs...... in narrow redox windows where the redox range levels are negatively correlated with the pH. This study highlights the potential importance of N2O bursts associated with flooding and infers that annual N2O emission estimates for tilled agricultural soils that are temporarily flooded will be underestimated...

  8. INFLUENCES OF SOIL PROPERTIES ON CHROMIUM (III SORPTION

    Directory of Open Access Journals (Sweden)

    R. Salmasi, F. Salmasi

    2007-07-01

    Full Text Available Soil adsorbing properties reduce sorption ability of the metal, which in turn may influence decision for remediation at contaminated sites. The objective of this study is presentation of a model based on soil properties to estimate the sorption of Cr(III in chromium contaminated soils. Twenty uncontaminated soil samples, with properties similar to the contaminated soils were selected from around of city of Tabriz and treated with Cr as CrCl3. A multiple regression analysis with statgraph software was used to drive an expression that related Cr sorption to common soil properties. The results showed that four soil properties were important in determining the amount of Cr adsorbed by the soils including pH, cation exchange capacity, total inorganic carbon and clay content with nearly 80% variability in Cr sorption and a reasonable level of confidence by this model. The obtained model suggested that Cr(III sorption was enhanced by higher soil pH, more total inorganic carbon, more clay, and higher cation exchange capacity.

  9. Methods of pH determination in Calcareous soils of Oman: The effect of Electrolyte and soil solution ratio

    International Nuclear Information System (INIS)

    Al-Busaidi, A.; Cookson, P.

    2002-01-01

    Determination of pH assists in understanding many reactions that occur in soil. Soil pH values are highly sensitive to the procedure used for determination. In this study, pH was measured in different electrolytes [distilled water (pHw), 0.01MCaCl2 (pHCa), 1MKCl (pHk), and 0.01MBaCl2 (pHba)] with different soil: electrolyte ratios (i.e. 1:1, 1:2.5 and 1:5). The objective was to determine the effect of each electrolyte and dilution ratio on pH of saline and non-saline soils from Oman. It was found that ph values varied significantly between electrolytes and with different dilution ratios. Linear regression equations were generated between electrolytes, dilution ratios and were mostly significant. Soil pH values determined in different electrolytes were significantly interrelated. Water appeared as a highly suitable solvent for soil pH measurements because it is simple and values familiar to soil users. However, alkaline errors and electrode instabilities due to liquid junction and soluble salt effects, affected soil pH measurements, especially in water, and resulted in alkaline errors during pH measurements. Errors were minimized when pH was measured in electrolytes rather than in water. (author)

  10. Effect of pH value of applied solution on radioiodine sorption by soils

    International Nuclear Information System (INIS)

    Szabova, T.

    1976-01-01

    Sorption of radioiodine by soils was followed under static conditions at different pH values of the initial solution in five soil types. Sorption of radioiodine by soils is affected by the amount of the organic mass and by the pH of solutions. With the same pH, soils containing a higher amount of the organic mass absorb more radioiodine. The highest sorption percentage of 131 I - for all pH values was found in meadow chernozem soil and the lowest in the rendzina and in carboniferous meadow soils. The highest sorption of 131 I - for degraded chernozem, meadow chernozem soils and brown soil was recorded at pH 5 and for carboniferous meadow soil and rendzina at pH 7. (author)

  11. Extractability of plutonium-238 and curium-242 from a contaminated soil as a function of pH and certain soil components. CH3COOH-NH4OH system

    International Nuclear Information System (INIS)

    Nishita, H.

    1978-01-01

    Extractability of 238 Pu and 242 Cm from an artificially contaminated soil as a function of pH and certain soil components was examined with an equilibrium batch technique by the use of a CH 3 COOH--NH 4 OH extracting system. The influence of various soil components on 238 Pu and 242 Cm extractability was determined indirectly by selective removal of the components from the soil. The soil organic matter appeared to have a major influence on the extractability of these radionuclides. Though to a lesser extent, free iron oxides exerted an influence also. Before removal of soil organic matter, the extractability curves for these radionuclides were qualitatively similar in general form. The nature of this form is discussed. Within the contaminated, untreated soil, the 238 Pu and 242 Cm extractability ranged from 0.60 to 30.8% and 0.11 to 14.83% of dose, respectively, depending on the pH of the extracting solution. The liquid-to soild-phase ratio (K'/sub d/) values ranged from 3.5 x 10 -4 to 2.7 x 10 -2 for 238 Pu and 0.9 x 10 -4 to 1.4 x 10 -2 for 242 Cm. Very low extractability occurred in the pH range from approx. 8.6 to approx. 9.7 for 238 Pu and from 7.6 to approx. 9.7 for 242 Cm

  12. Variation in pH optima of hydrolytic enzyme activities in tropical rain forest soils.

    Science.gov (United States)

    Turner, Benjamin L

    2010-10-01

    Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly among enzymes and soils. Enzymes were grouped into three classes based on their pH optima: (i) enzymes with acidic pH optima that were consistent among soils (cellobiohydrolase, β-xylanase, and arylsulfatase), (ii) enzymes with acidic pH optima that varied systematically with soil pH, with the most acidic pH optima in the most acidic soils (α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminidase), and (iii) enzymes with an optimum pH in either the acid range or the alkaline range depending on soil pH (phosphomonoesterase and phosphodiesterase). The optimum pH values of phosphomonoesterase were consistent among soils, being 4 to 5 for acid phosphomonoesterase and 10 to 11 for alkaline phosphomonoesterase. In contrast, the optimum pH for phosphodiesterase activity varied systematically with soil pH, with the most acidic pH optima (3.0) in the most acidic soils and the most alkaline pH optima (pH 10) in near-neutral soils. Arylsulfatase activity had a very acidic optimum pH in all soils (pH ≤3.0) irrespective of soil pH. The differences in pH optima may be linked to the origins of the enzymes and/or the degree of stabilization on solid surfaces. The results have important implications for the interpretation of hydrolytic enzyme assays using fluorogenic substrates.

  13. Methodologically controlled variations in laboratory and field pH measurements in waterlogged soils

    DEFF Research Database (Denmark)

    Elberling, Bo; Matthiesen, Henning

    2007-01-01

    artefacts is critical. But the study includes agricultural and forest soils for comparison. At a waterlogged site, Laboratory results were compared with three different field methods: calomel pH probes inserted in the soil from pits, pH measurements of soil solution extracted from the soil, and pH profiles...... using a solid-state pH electrode pushed into the soil from the surface. Comparisons between in situ and laboratory methods revealed differences of more than 1 pH unit. The content of dissolved ions in soil solution and field observations of O2 and CO2 concentrations were used in the speciation model...... PHREEQE in order to predict gas exchange processes. Changes in pH in soil solution following equilibrium in the laboratory could be explained mainly by CO2 degassing. Only soil pH measured in situ using either calomel or solid-state probes inserted directly into the soil was not affected by gas exchange...

  14. Soil pH effects on the comparative toxicity of dissolved zinc, non-nano and nano ZnO to the earthworm Eisenia fetida.

    Science.gov (United States)

    Heggelund, Laura R; Diez-Ortiz, Maria; Lofts, Stephen; Lahive, Elma; Jurkschat, Kerstin; Wojnarowicz, Jacek; Cedergreen, Nina; Spurgeon, David; Svendsen, Claus

    2014-08-01

    To determine how soil properties influence nanoparticle (NP) fate, bioavailability and toxicity, this study compared the toxicity of nano zinc oxide (ZnO NPs), non-nano ZnO and ionic ZnCl2 to the earthworm Eisenia fetida in a natural soil at three pH levels. NP characterisation indicated that reaction with the soil media greatly controls ZnO properties. Three main conclusions were drawn. First that Zn toxicity, especially for reproduction, was influenced by pH for all Zn forms. This can be linked to the influence of pH on Zn dissolution. Secondly, that ZnO fate, toxicity and bioaccumulation were similar (including relationships with pH) for both ZnO forms, indicating the absence of NP-specific effects. Finally, earthworm Zn concentrations were higher in worms exposed to ZnO compared to ZnCl2, despite the greater toxicity of the ionic form. This observation suggests the importance of considering the relationship between uptake and toxicity in nanotoxicology studies.

  15. Influence of long-term fertilization on soil physicochemical properties in a brown soil

    Science.gov (United States)

    Li, Dongdong; Luo, Peiyu; Han, Xiaori; Yang, Jinfeng

    2018-01-01

    This study aims to explore the influence on soil physicochemical properties under a 38-y long-term fertilization in a brown soil. Soil samples (0-20 cm)were taken from the six treatments of the long-term fertilization trial in October 2016:no fertilizer (CK), N1(mineral nitrogen fertilizer), N1P (mineral nitrogen and phosphate fertilizer), N1PK (mineral nitrogen, phosphate and potassic fertilizer), pig manure (M2), M2N1P (pig manure, mineral nitrogen and phosphate fertilizer).The results showed thatthe long-term application of chemical fertilizers reduced soil pH value, while the application of organic fertilizers increased pH value. Fertilization significantly increased the content of AHN, TN and SOM. Compared with the CK treatment and chemical fertilizer treatments, organic fertilizer treatments significantly increased the content of AP and TP. The content of AK and TK were no significant difference in different treatment.

  16. Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists.

    Science.gov (United States)

    Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun; Ezawa, Tatsuhiro

    2016-01-01

    Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0-7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils.

  17. Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists

    Science.gov (United States)

    Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun

    2016-01-01

    Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0–7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils. PMID

  18. Effect of pH and soil structure on transport of sulfonamide antibiotics in agricultural soils.

    Science.gov (United States)

    Park, Jong Yol; Huwe, Bernd

    2016-06-01

    We investigated the effect of solution pH and soil structure on transport of sulfonamide antibiotics (sulfamethoxazole, sulfadimethoxine and sulfamethazine) in combination with batch sorption tests and column experiments. Sorption isotherms properly conformed to Freundlich model, and sorption potential of the antibiotics is as follows; sulfadimethoxine > sulfamethoxazole > sulfamethazine. Decreasing pH values led to increased sorption potential of the antibiotics on soil material in pH range of 4.0-8.0. This likely resulted from abundance of neutral and positive-charged sulfonamides species at low pH, which electrostatically bind to sorption sites on soil surface. Due to destruction of macropore channels, lower hydraulic conductivities of mobile zone were estimated in the disturbed soil columns than in the undisturbed soil columns, and eventually led to lower mobility of the antibiotics in disturbed column. The results suggest that knowledge of soil structure and solution condition is required to predict fate and distribution of sulfonamide antibiotics in environmental matrix. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. The influence of soil type at Cs-137-spreading in soil depth

    International Nuclear Information System (INIS)

    Tyrpanova, Kh.; Jordanova, I.

    1995-01-01

    The distribution of Cs-137 in soil depth up to 15 cm was examined for four types of soil - leached black earth, calcareous black earth, brown forest soil and slightly leached humus-calcareous soil. The behaviour of Cs-137 before and after Chernobyl accident depending on soil type was determined using Cs-134. Accounting for halftime effect of Cs-134 it was possible to distinguish the penetration of the Chernobyl Cs-137 from that of the older one. The same degree of penetration has been achieved: for 30 years for the old Cs-137 and only for a year for the Chernobyl one probably due to its modification. The most expressed tendency to penetrate in depth has been observed at the calcareous black earth (from Kozloduy region, with highest pH value and basis content), the least - at the brown forest soil (from Smolyan region, lowest pH value and basis content). The mineral composition and organic matter content influence the penetration process. The humus matter absorbs Cs-137. Thus it is accessible to the plants, but its penetration is limited to 2.5 cm. 9 refs., 2 tabs. (author)

  20. Fertilization Shapes Bacterial Community Structure by Alteration of Soil pH

    Directory of Open Access Journals (Sweden)

    Yuting Zhang

    2017-07-01

    Full Text Available Application of chemical fertilizer or manure can affect soil microorganisms directly by supplying nutrients and indirectly by altering soil pH. However, it remains uncertain which effect mostly shapes microbial community structure. We determined soil bacterial diversity and community structure by 454 pyrosequencing the V1-V3 regions of 16S rRNA genes after 7-years (2007–2014 of applying chemical nitrogen, phosphorus and potassium (NPK fertilizers, composted manure or their combination to acidic (pH 5.8, near-neutral (pH 6.8 or alkaline (pH 8.4 Eutric Regosol soil in a maize-vegetable rotation in southwest China. In alkaline soil, nutrient sources did not affect bacterial Operational Taxonomic Unit (OTU richness or Shannon diversity index, despite higher available N, P, K, and soil organic carbon in fertilized than in unfertilized soil. In contrast, bacterial OTU richness and Shannon diversity index were significantly lower in acidic and near-neutral soils under NPK than under manure or their combination, which corresponded with changes in soil pH. Permutational multivariate analysis of variance showed that bacterial community structure was significantly affected across these three soils, but the PCoA ordination patterns indicated the effect was less distinct among nutrient sources in alkaline than in acidic and near-neural soils. Distance-based redundancy analysis showed that bacterial community structures were significantly altered by soil pH in acidic and near-neutral soils, but not by any soil chemical properties in alkaline soil. The relative abundance (% of most bacterial phyla was higher in near-neutral than in acidic or alkaline soils. The most dominant phyla were Proteobacteria (24.6%, Actinobacteria (19.7%, Chloroflexi (15.3% and Acidobacteria (12.6%; the medium dominant phyla were Bacterioidetes (5.3%, Planctomycetes (4.8%, Gemmatimonadetes (4.5%, Firmicutes (3.4%, Cyanobacteria (2.1%, Nitrospirae (1.8%, and candidate division TM7 (1

  1. Fertilization Shapes Bacterial Community Structure by Alteration of Soil pH.

    Science.gov (United States)

    Zhang, Yuting; Shen, Hong; He, Xinhua; Thomas, Ben W; Lupwayi, Newton Z; Hao, Xiying; Thomas, Matthew C; Shi, Xiaojun

    2017-01-01

    Application of chemical fertilizer or manure can affect soil microorganisms directly by supplying nutrients and indirectly by altering soil pH. However, it remains uncertain which effect mostly shapes microbial community structure. We determined soil bacterial diversity and community structure by 454 pyrosequencing the V1-V3 regions of 16S rRNA genes after 7-years (2007-2014) of applying chemical nitrogen, phosphorus and potassium (NPK) fertilizers, composted manure or their combination to acidic (pH 5.8), near-neutral (pH 6.8) or alkaline (pH 8.4) Eutric Regosol soil in a maize-vegetable rotation in southwest China. In alkaline soil, nutrient sources did not affect bacterial Operational Taxonomic Unit (OTU) richness or Shannon diversity index, despite higher available N, P, K, and soil organic carbon in fertilized than in unfertilized soil. In contrast, bacterial OTU richness and Shannon diversity index were significantly lower in acidic and near-neutral soils under NPK than under manure or their combination, which corresponded with changes in soil pH. Permutational multivariate analysis of variance showed that bacterial community structure was significantly affected across these three soils, but the PCoA ordination patterns indicated the effect was less distinct among nutrient sources in alkaline than in acidic and near-neural soils. Distance-based redundancy analysis showed that bacterial community structures were significantly altered by soil pH in acidic and near-neutral soils, but not by any soil chemical properties in alkaline soil. The relative abundance (%) of most bacterial phyla was higher in near-neutral than in acidic or alkaline soils. The most dominant phyla were Proteobacteria (24.6%), Actinobacteria (19.7%), Chloroflexi (15.3%) and Acidobacteria (12.6%); the medium dominant phyla were Bacterioidetes (5.3%), Planctomycetes (4.8%), Gemmatimonadetes (4.5%), Firmicutes (3.4%), Cyanobacteria (2.1%), Nitrospirae (1.8%), and candidate division TM7 (1

  2. Degradation of [14C]isofenphos in soil in the laboratory under different soil pH's, temperatures, and moistures

    International Nuclear Information System (INIS)

    Abou-Assaf, N.; Coats, J.R.

    1987-01-01

    The effects of three soil pH's, three soil temperatures, and three soil moistures on [ 14 C]isofenphos degradation were investigated. All three factors interacted strongly and significantly affected the persistence of isofenphos as well as the formation of the degradation products (p less than 1%). Isofenphos degradation was greatest at the higher temperatures 35 0 C greater than 25 0 C greater than 15 0 C (except under alkaline pH's), medium moisture 25% greater than 30% greater than 15%, and in both alkaline (pH = 8) and acidic soils (pH = 6) compared with neutral soil (pH = 7). Isofenphos oxon formation was greatest at higher temperatures 35 0 C compared with 25 0 C and 15 0 C, in acidic soil greater than neutral soil greater than alkaline soil, and under high moisture (30%) compared with the 15% and 22.5% moistures. The formation of soil-bound residues was greatest at higher temperatures 35 0 C greater than 25 0 C greater than 15 0 C, higher moisture 30% compared with 15% and 22.5%, and in alkaline soil compared with neutral and acidic soils

  3. [Spatiotemporal variation of soil pH in Guangdong Province of China in past 30 years].

    Science.gov (United States)

    Guo, Zhi-Xing; Wang, Jing; Chai, Min; Chen, Ze-Peng; Zhan, Zhen-Shou; Zheng, Wu-Ping; Wei, Xiu-Guo

    2011-02-01

    Based on the 1980s' soil inventory data and the 2002-2007 soil pH data of Guangdong Province, the spatiotemporal variation of soil pH in the Province in past 30 years was studied. In the study period, the spatial distribution pattern of soil pH in the Province had less change (mainly acidic), except that in Pearl River Delta and parts of Qingyuan and Shaoguan (weak alkaline). The overall variation of soil pH was represented as acidification, with the average pH value changed from 5.70 to 5.44. Among the soil types in the Province, alluvial soil had an increased pH, lateritic red soil, paddy soil, and red soil had a large decrement of pH value, and lime soil was most obvious in the decrease of pH value and its area percentage. The soil acidification was mainly induced by soil characteristics, some natural factors such as acid rain, and human factors such as unreasonable fertilization and urbanization. In addition, industrialization and mining increased the soil pH in some areas.

  4. Influence of the isomerism on the sorption of imazamethabenz-methyl by soil.

    Science.gov (United States)

    Pinna, Maria Vittoria; Pusino, Alba

    2013-04-01

    The sorption of meta and para isomers of the herbicide imazamethabenz-methyl, methyl 6-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-m- or p-toluate, by three soils and soil organic matter, was studied. Sorption isotherms conformed to the Freundlich equation. It was found that pH was the main factor influencing the adsorption in all of the systems. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, at low pH value, the soil rich in smectite clays, favoured the sorption of meta rather than para isomer. The higher affinity of clay surfaces for the meta isomer of the herbicide is due to the stabilization of the meta protonated form by resonance. At all pH values, the sorption on soil organic matter did not differ between two isomers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. pH is the primary determinant of the bacterial community structure in agricultural soils impacted by polycyclic aromatic hydrocarbon pollution

    Science.gov (United States)

    Wu, Yucheng; Zeng, Jun; Zhu, Qinghe; Zhang, Zhenfa; Lin, Xiangui

    2017-01-01

    Acidification and pollution are two major threats to agricultural ecosystems; however, microbial community responses to co-existed soil acidification and pollution remain less explored. In this study, arable soils of broad pH (4.26-8.43) and polycyclic aromatic hydrocarbon (PAH) gradients (0.18-20.68 mg kg-1) were collected from vegetable farmlands. Bacterial community characteristics including abundance, diversity and composition were revealed by quantitative PCR and high-throughput sequencing. The bacterial 16S rRNA gene copies significantly correlated with soil carbon and nitrogen contents, suggesting the control of nutrients accessibility on bacterial abundance. The bacterial diversity was strongly related to soil pH, with higher diversity in neutral samples and lower in acidic samples. Soil pH was also identified by an ordination analysis as important factor shaping bacterial community composition. The relative abundances of some dominant phyla varied along the pH gradient, and the enrichment of a few phylotypes suggested their adaptation to low pH condition. In contrast, at the current pollution level, PAH showed marginal effects on soil bacterial community. Overall, these findings suggest pH was the primary determinant of bacterial community in these arable soils, indicative of a more substantial influence of acidification than PAH pollution on bacteria driven ecological processes.

  6. Soil sealing degree as factor influencing urban soil contamination with polycyclic aromatic hydrocarbons (PAHs

    Directory of Open Access Journals (Sweden)

    Mendyk Łukasz

    2016-03-01

    Full Text Available The objective of the study was to determine role of soil sealing degree as the factor influencing soil contamination with polycyclic aromatic hydrocarbons (PAHs. The study area included four sampling sites located within the administrative boundaries of the Toruń city, Poland. Sampling procedure involved preparing soil pits representing three examples of soil sealing at each site: non-sealed soil as a control one (I and two degrees of soil sealing: semi-pervious surface (II and totally impervious surface (III. Together with basic properties defined with standard procedures (particle size distribution, pH, LOI, content of carbonates content of selected PAHs was determined by dichloromethane extraction using gas chromatography with mass spectrometric detection (GC-MS. Obtained results show that urban soils in the city of Toruń are contaminated with polycyclic aromatic hydrocarbons. Soil sealing degree has a strong influence on the soil contamination with polycyclic aromatic hydrocarbons. Totally sealed soils are better preserved from atmospheric pollution including PAHs. Combustion of grass/wood/coal was the main source of determined PAHs content in examined soils.

  7. Soil pH management without lime, a strategy to reduce greenhouse gas emissions from cultivated soils

    Science.gov (United States)

    Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter

    2015-04-01

    For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply lime, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than lime. Here we report a newly established field trail in Norway, in which we compare the effects of lime and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of lime on soil pH, and slower effects of the mafic rocks. The

  8. Sorption behavior of cesium on various soils under different pH levels

    International Nuclear Information System (INIS)

    Giannakopoulou, F.; Haidouti, C.; Chronopoulou, A.; Gasparatos, D.

    2007-01-01

    In the present study we investigated the sorption behavior of Cs in four different soils (sandyloam, loam, clayloam and clay) by using batch experiment. Cs sorption characteristics of the studied soils were examined at 4 mg L -1 Cs concentration, at various pH levels, at room temperature and with 0.01 M CaCl 2 as a background electrolyte. Among different soils the decrease of k d (distribution coefficient) of cesium, at all pH levels, followed the sequence sandyloam > loam > clayloam > clay, indicating that the particle size fractions and especially the clay content plays predominant role on sorption of Cs. The effect of pH on cesium sorption displays a similar pattern for all soils, depending on soil type. At acid pH levels less cesium was sorbed, due to a greater competition with other cations for available sorption sites. The maximum sorption of Cs was observed at pH 8, where the negative charge density on the surface of the absorbents was the highest. For all soils was observed significantly lower Cs sorption at pH 10

  9. Effect of the pH on the radiocesium adsorption in tropical soils

    International Nuclear Information System (INIS)

    Roque, Mario Lucio; Boaretto, Antonio E.; Moniz, Antonio C; Smolders, Erik E. T.

    2002-01-01

    The objective was to demonstrate that the pH dependent charges are specific change sites for radiocesium. Clay minerals occurrence in superficial samples of eight tropical soils was analyzed by X-Ray diffractometry. The variation of superficial charge of these soils were quantify by potentiometric titration in a range from 3 to 8 pH values. The results of radiocesium interception potential showed the presence of specific sites of adsorption of this radionuclide for all the soils. The variation of radiocesium adsorption for all soils was quantified in a pH defined range. The increase on the pH values caused increase on the radiocesium adsorption by the soils and a consequent decrease in the radiocesium activity in the equilibrium solution. The soil with predominance of the 2:1 clay minerals showed higher radiocesium adsorption than the soils with 1:1 clay minerals or iron and aluminum oxides. The increase on the negative charge in consequence of pH increase caused increase on radiocesium adsorption. The correction of soil acidity with lime by increasing the specific sites charge for radiocesium and decreasing the radionuclide activity in soil solution may cause decrease on the transference of radiocesium from soil to plant. (author)

  10. pH is the primary determinant of the bacterial community structure in agricultural soils impacted by polycyclic aromatic hydrocarbon pollution

    Science.gov (United States)

    Wu, Yucheng; Zeng, Jun; Zhu, Qinghe; Zhang, Zhenfa; Lin, Xiangui

    2017-01-01

    Acidification and pollution are two major threats to agricultural ecosystems; however, microbial community responses to co-existed soil acidification and pollution remain less explored. In this study, arable soils of broad pH (4.26–8.43) and polycyclic aromatic hydrocarbon (PAH) gradients (0.18–20.68 mg kg−1) were collected from vegetable farmlands. Bacterial community characteristics including abundance, diversity and composition were revealed by quantitative PCR and high-throughput sequencing. The bacterial 16S rRNA gene copies significantly correlated with soil carbon and nitrogen contents, suggesting the control of nutrients accessibility on bacterial abundance. The bacterial diversity was strongly related to soil pH, with higher diversity in neutral samples and lower in acidic samples. Soil pH was also identified by an ordination analysis as important factor shaping bacterial community composition. The relative abundances of some dominant phyla varied along the pH gradient, and the enrichment of a few phylotypes suggested their adaptation to low pH condition. In contrast, at the current pollution level, PAH showed marginal effects on soil bacterial community. Overall, these findings suggest pH was the primary determinant of bacterial community in these arable soils, indicative of a more substantial influence of acidification than PAH pollution on bacteria driven ecological processes. PMID:28051171

  11. Soil pH mapping with an on-the-go sensor.

    Science.gov (United States)

    Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

    2011-01-01

    Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH Manager™, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH Manager™ under farming conditions in Germany. Sensor readings were compared with data obtained by standard protocols of soil pH assessment. Experiments took place under different scenarios: (a) controlled tests in the lab, (b) semicontrolled test on transects in a stop-and-go mode, and (c) tests under practical conditions in the field with the sensor working in its typical on-the-go mode. Accuracy issues, problems, options, and potential benefits of the Veris pH Manager™ were addressed. The tests demonstrated a high degree of linearity between standard laboratory values and sensor readings. Under practical conditions in the field (scenario c), the measure of fit (r(2)) for the regression between the on-the-go measurements and the reference data was 0.71, 0.63, and 0.84, respectively. Field-specific calibration was necessary to reduce systematic errors. Accuracy of the on-the-go maps was considerably higher compared with the pH maps obtained by following the standard protocols, and the error in calculating lime requirements was reduced by about one half. However, the system showed some weaknesses due to blockage by residual straw and weed roots. If these problems were solved, the on-the-go sensor investigated here could be an efficient alternative to standard sampling protocols as a basis for liming in Germany.

  12. The effect of meat and bone meal (MBM on the nitrogen and phosphorus content and pH of soil

    Directory of Open Access Journals (Sweden)

    Anna Nogalska

    2017-12-01

    Full Text Available A field experiment was conducted in 2011 – 2013 in Poland. The objective of this study was to determine the effect of increasing doses of meat and bone meal (MBM on the mineral nitrogen (Nmin and available phosphorus (P content of soil and the soil pH. Changes in the content of NH4+-N, NO3--N and available P in soil were affected by MBM dose, experiment duration, weather conditions and crop species. Soil amended with MBM was more abundant in mineral N and available P. The lowest concentration of NO3--N and the highest concentration of NH4+-N were noted in the first year of the study, because the nitrification process requires a longer time. MBM had no influence on the accumulation of Nmin in soil, whereas the concentration of available P increased significantly throughout the experiment. The soil pH decreased with increasing MBM doses. After the application of the highest MBM doses soil pH classification was changed from neutral to slightly acidic.

  13. Effect of pH on saturated hydraulic conductivity and soil dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, D.L.; Roades, J.D.; Lavado, R.; Grieve, C.M.

    The adverse effects of exchangeable sodium on soil hydraulic conductivity (K) are well known, but at present only sodicity and total electrolyte concentration are used in evaluating irrigation water suitability. In arid areas, high sodicity is often associatd with high dissolved carbonate and thus high pH, but in humid areas high sodicity may be associated with low pH. To evaluate the effect of pH (as an independent variable) on K, solutions with the same SAR and electrolyte level were prepared at pH 6, 7, 8, and 9. Saturated K values were determined at constant flux in columns packed at a bulk density of 1.5 Mg m/sup -3/. At pH 9, saturated K values were lower than at pH 6 for a montmorillonitic and kaolinitic soil. For a vermiculitic soil with lower organic carbon and higher silt content, pH changes did not cause large K differences. Decreases in K were not reversible on application of waters with higher electrolyte levels. The results from the K experiments were generally consistent with optical transmission measurements of dispersion. Although anion adsorption was at or below detection limits and cation exchange capacity (CEC) was only slightly dependent on pH, differences in pH effects on K among soils are likely due to differences in quantities of variable-charge minerals and organic matter.

  14. Metal concentrations in aquatic macrophytes as influenced by soil and acidification

    Science.gov (United States)

    Sparling, D.W.; Lowe, T.P.

    1998-01-01

    Bioavailability of metals to aquatic plants is dependent on many factors including ambient metal concentration, pH of soil or water, concentration of ligands, competition with other metals for binding sites, and mode of exposure. Plants may be exposed to metals through water, air, or soil, depending on growth form. This paper examines the influence of soil type under two regimens of water acidification on metal uptake by four species of aquatic macrophytes: smartweed (Polygonum sagittatum), burreed (Sparganium americanum), pondweed (Potamogeton diversifolius), and bladderwort (Utricularia vulgaris) in constructed, experimentally acidified wetlands. Soil types consisted of a comparatively high-metal clay or a lower-metal sandy loam. Each pond was either acidified to pH ca. 4.85.3 or allowed to remain circumneutral. Metal concentrations tended to be higher in the submerged bladderwort and pondweed than in the emergent burreed and smartweed. Soils were important to plant metal concentrations in all species, but especially in the emergents. Acidification influenced plant concentrations of some metals and was especially important in the submerged pondweed. Bioaccumulation of metals occurred for Mn, B, Sr, Ba, and Zn, compared to soil concentrations.

  15. Soil microbial community structure and diversity are largely influenced by soil pH and nutrient quality in 78-year-old tree plantations

    Science.gov (United States)

    Zhou, Xiaoqi; Guo, Zhiying; Chen, Chengrong; Jia, Zhongjun

    2017-04-01

    Forest plantations have been recognised as a key strategy management tool for stocking carbon (C) in soils, thereby contributing to climate warming mitigation. However, long-term ecological consequences of anthropogenic forest plantations on the community structure and diversity of soil microorganisms and the underlying mechanisms in determining these patterns are poorly understood. In this study, we selected 78-year-old tree plantations that included three coniferous tree species (i.e. slash pine, hoop pine and kauri pine) and a eucalypt species in subtropical Australia. We investigated the patterns of community structure, and the diversity of soil bacteria and eukaryotes by using high-throughput sequencing of 16S rRNA and 18S rRNA genes. We also measured the potential methane oxidation capacity under different tree species. The results showed that slash pine and Eucalyptus significantly increased the dominant taxa of bacterial Acidobacteria and the dominant taxa of eukaryotic Ascomycota, and formed clusters of soil bacterial and eukaryotic communities, which were clearly different from the clusters under hoop pine and kauri pine. Soil pH and nutrient quality indicators such as C : nitrogen (N) and extractable organic C : extractable organic N were key factors in determining the patterns of soil bacterial and eukaryotic communities between the different tree species treatments. Slash pine and Eucalyptus had significantly lower soil bacterial and eukaryotic operational taxonomical unit numbers and lower diversity indices than kauri pine and hoop pine. A key factor limitation hypothesis was introduced, which gives a reasonable explanation for lower diversity indices under slash pine and Eucalyptus. In addition, slash pine and Eucalyptus had a higher soil methane oxidation capacity than the other tree species. These results suggest that significant changes in soil microbial communities may occur in response to chronic disturbance by tree plantations, and highlight

  16. Adsorption of tetracycline on soil and sediment: Effects of pH and the presence of Cu(II)

    International Nuclear Information System (INIS)

    Zhang Zheyun; Sun Ke; Gao Bo; Zhang Guixiang; Liu Xitao; Zhao Ye

    2011-01-01

    Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K OC ) and PMM saturated adsorption capacity (Q OC 0 ) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH < 5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH.

  17. Reduction of exchangeable calcium and magnesium in soil with increasing pH

    Directory of Open Access Journals (Sweden)

    Miyazawa Mário

    2001-01-01

    Full Text Available A laboratory study was conducted with soil samples and synthetic solutions to investigate possible mechanisms related with reduction in KCl exchangeable Ca and Mg with increasing pH. Increasing soil pH over 5.3 with CaCO3 added to the soil and with NaOH solution added to soil/KCl suspension increased adsorptions of Ca and Mg. The reduction of Mg was greater than Ca and was related to the concentration of soil exchangeable Al. The decreases of soluble Ca and Mg following addition of Al in synthetic solution were at pH > 7.5. The isomorphic coprecipitation reaction with Al compounds may be the most possible mechanism responsible for the decrease of exchangeable Ca and Mg with increasing pH. Possible chemical reactions are presented.

  18. Influence of humified organic matter on copper behavior in acid polluted soils

    International Nuclear Information System (INIS)

    Fernandez-Calvino, D.; Soler-Rovira, P.; Polo, A.; Arias-Estevez, M.; Plaza, C.

    2010-01-01

    The main purpose of this work was to identify the role of soil humic acids (HAs) in controlling the behavior of Cu(II) in vineyard soils by exploring the relationship between the chemical and binding properties of HA fractions and those of soil as a whole. The study was conducted on soils with a sandy loam texture, pH 4.3-5.0, a carbon content of 12.4-41.0 g kg -1 and Cu concentrations from 11 to 666 mg kg -1 . The metal complexing capacity of HA extracts obtained from the soils ranged from 0.69 to 1.02 mol kg -1 , and the stability constants for the metal ion-HA complexes formed, log K, from 5.07 to 5.36. Organic matter-quality related characteristics had little influence on Cu adsorption in acid soils, especially if compared with pH, the degree of Cu saturation and the amount of soil organic matter. - The effect of organic matter quality on Cu adsorption in acid soils was low compared with other soil characteristics such as pH or degree of Cu saturation.

  19. Effects of Soil Oxygen Conditions and Soil pH on Remediation of DDT-contaminated Soil by Laccase from White Rot Fungi

    Directory of Open Access Journals (Sweden)

    Yuechun Zhao

    2010-04-01

    Full Text Available High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5–4.5.

  20. Physiochemical Influence of Soil Minerals on the Organic Reduction of Soil Chromium

    International Nuclear Information System (INIS)

    Njoku, P.C.; Nweze, C.A.

    2009-01-01

    The physiochemical influence of soil minerals (Bentonite, Kaolinite, Diatomite,Rutile and Ferrihydrite) on the organic reduction ofchromium (VI) has been investigated with Oxalic acid as the organic reductant. The effect of pH and particle sizes of the soil minerals were also investigated. Results showed that with 0.1mol/dm3 concentration of Oxalic acid, the concentration of chromium(VI) remaining was 0.28, 0.34,0.38, 0.46 and 0.52mg/kgfor Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite respectively whereas at 0.5mol/dm3of oxalic acid, the concentration of chromium reduced to 0.20,0.26, 0.30, 0.38, and0.44mg/kg for Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite. Increasedconcentration of oxalic acid increased the reduction of chromium(VI) to chromium(III). At pH 5.0, the concentration of chromium(VI)left was 0.28, 0.34, 0.38,0.46 and 0.52mg/kg forBentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite while at pH 2.5, concentration was0.16, 0.22, 0.26, 0.34 and 0.43mg/kg respectively. At particle size of 47-42 microns, concentration of chromium(VI) was 0.28, 0.34,0.38, 0.46, 0.52mg/kg for the same order ofthe soil minerals. At micron sizes of33-29 and 28-25 ranges the concentration ofchromium(VI) left was 0.23, 0.29, 0.33,0.41 and 0.47mg/kg for both micron sizes and corresponding minerals as well. These results showed that above 33-29 micron sizes, the influence of particle size was negligible. (author)

  1. Influence of pretreatment on efficiency of bioremediation of hydrocarbon contaminated soils

    International Nuclear Information System (INIS)

    Elektorowicz, M.; Hadjinicolaou, J.; Yong, R.N.; St-Cyr, M.

    1992-01-01

    Biodegradation has been selected as a technique to treat a Montreal site which was contaminated by oil pipeline spills. A 2500 m 3 volume of soil was excavated and stored in piles. Three large closed cells were then constructed for use in on-site biodegradation of the soil. Before proceeding with the on-site biodegradation, a feasibility study was conducted in the laboratory using 20 kg of soil placed in mini-reactors for 188 d of biodegradation at ambient temperature. Before biodegradation began, the soil in certain of the mini-reactors was pretreated by comminuting gravel pieces larger than 0.5 cm in diameter and by mixing the soil with sawdust and nutrients. At predetermined intervals, the soils were analyzed at various locations in the mini-reactors for such parameters as oil and grease concentrations, organic matter content, Kjeldahl nitrogen, humidity, phosphorus, and metals. Emissions of volatile organic compounds and CO 2 were also measured. The mean decrease in oil and grease concentration was found to be 89%. No decrease was noted in those soils that had not been pretreated with sawdust and nutrients. An increase in soil pH was noted up to the 50th day of biodegradation, after which the pH decreased gradually. The feasibility study shows the influence of the addition of sawdust on one of the most important environmental parameters during the course of biodegradation: the pH value. Increase in pH can decrease or stop the activity of soil microorganisms. 11 refs., 6 figs

  2. Control of lead solubility in soil contaminated with lead shot: Effect of soil pH

    International Nuclear Information System (INIS)

    Rooney, Corinne P.; McLaren, Ronald G.; Condron, Leo M.

    2007-01-01

    An incubation experiment was carried out to assess the rate of oxidation of Pb shot and subsequent transfer of Pb to the soil under a range of soil pH conditions. Lead shot corrosion was rapid, so that soil solution and fine earth ( 3 (CO 3 ) 2 (OH) 2 ), developed in crusts surrounding individual Pb pellets. However, irrespective of pH, Pb 2+ activities in the soil solutions, modelled using WHAM 6, were much lower than would be the case if they were controlled by the solubility of the dominant Pb compounds present in the Pb shot crust material. In contrast, modelling of soil solid-solution phase distribution of Pb, again using WHAM 6, suggested that, at least during the 24 months of the study, soil solution Pb concentrations were more likely to be controlled by sorption of Pb by the soil solid phase. - Sorption processes control Pb 2+ ion activity in soils contaminated with Pb shot

  3. [Effects of soil pH on the competitive uptake of amino acids by maize and microorganisms].

    Science.gov (United States)

    Ma, Qing Xu; Wang, Jun; Cao, Xiao Chuang; Sun, Yan; Sun, Tao; Wu, Liang Huan

    2017-07-18

    Organic nitrogen can play an important role in plant growth, and soil pH changed greatly due to the over-use of chemical fertilizers, but the effects of soil pH on the competitive uptake of amino acids by plants and rhizosphere microorganisms are lack of detailed research. To study the effects of soil pH on the uptake of amino acids by maize and soil microorganisms, two soils from Hangzhou and Tieling were selected, and the soil pH was changed by the electrokinesis, then the 15 N-labeled glycine was injected to the centrifuge tube with a short-term uptake of 4 h. Soil pH had a significant effect on the shoot and root biomass, and the optimal pH for maize shoot growth was 6.48 for Hangzhou red soil, while it was 7.65 for Tieling brown soil. For Hangzhou soil, the 15 N abundance of maize shoots under pH=6.48 was significantly higher than under other treatments, and the uptake amount of 15 N-glycine was also much higher. However, the 15 N abundance of maize shoots and roots under pH=7.65 Tieling soil was significantly lower than it under pH=5.78, but the uptake amount of 15 N-glycine under pH=7.65 was much higher. The microbial biomass C was much higher in pH=6.48 Hangzhou soil, while it was much lower in pH=7.65 Tieling soil. According to the results of root uptake, root to shoot transportation, and the competition with microorganisms, we suggested that although facing the fierce competition with microorganisms, the maize grown in pH=6.48 Hangzhou soil increased the uptake of glycine by increasing its root uptake and root to shoot transportation. While in pH=7.65 Tieling soil, the activity of microorganisms was decreased, which decreased the competition with maize for glycine, and increased the uptake of glycine by maize.

  4. pH : a key control of the nature and distribution of dissolved organic matter and associated trace metals in soil

    Science.gov (United States)

    Pédrot, M.; Dia, A.; Davranche, M.

    2009-04-01

    Dissolved organic matter is ubiquitous at the Earth's surface and plays a prominent role in controlling metal speciation and mobility from soils to hydrosystems. Humic substances (HS) are usually considered to be the most reactive fraction of organic matter. Humic substances are relatively small and formed by chemically diverse organic molecules, bearing different functional groups that act as binding sites for cations and mineral surfaces. Among the different environmental physicochemical parameters controlling the metal speciation, pH is likely to be the most important one. Indeed, pH affect the dissociation of functional groups, and thus can influence the HS structure, their ability to complex metals, their solubility degree allowing the formation of aggregates at the mineral surface. In this context, soil/water interactions conducted through batch system experiments, were carried out with a wetland organic-rich soil to investigate the effect of pH on the release of dissolved organic carbon (DOC) and associated trace elements. The pH was regulated between 4 and 7.5 using an automatic pH stat titrator. Ultrafiltration experiments were performed to separate the dissolved organic pool following decreasing pore sizes (30 kDa, 5 kDa and 2 kDa with 1 Da = 1 g.mol-1). The pH increase induced a significant DOC release, especially in heavy organic molecules (size >5 kDa) with a high aromaticity (>30 %). These were probably humic acids (HA). This HA release influenced (i) directly the trace element concentrations in soil solution since HA were enriched in several trace elements such as Th, REE, Y, U, Cr and Cu; and (ii) indirectly by the breaking of clay-humic complexes releasing Fe- and Al-rich nanoparticles associated with V, Pb and Ti. By contrast, at acid pH, most HS were complexed onto mineral surfaces. They also sequestered iron nanoparticles. Therefore, at low pH, most part of DOC molecules had a size pH and ionic strength .The molecular size and shape of HS is

  5. Archaeal abundance across a pH gradient in an arable soil and its relationship to bacterial and fungal growth rates.

    Science.gov (United States)

    Bengtson, Per; Sterngren, Anna E; Rousk, Johannes

    2012-08-01

    Soil pH is one of the most influential factors for the composition of bacterial and fungal communities, but the influence of soil pH on the distribution and composition of soil archaeal communities has yet to be systematically addressed. The primary aim of this study was to determine how total archaeal abundance (quantitative PCR [qPCR]-based estimates of 16S rRNA gene copy numbers) is related to soil pH across a pH gradient (pH 4.0 to 8.3). Secondarily, we wanted to assess how archaeal abundance related to bacterial and fungal growth rates across the same pH gradient. We identified two distinct and opposite effects of pH on the archaeal abundance. In the lowest pH range (pH 4.0 to 4.7), the abundance of archaea did not seem to correspond to pH. Above this pH range, there was a sharp, almost 4-fold decrease in archaeal abundance, reaching a minimum at pH 5.1 to 5.2. The low abundance of archaeal 16S rRNA gene copy numbers at this pH range then sharply increased almost 150-fold with pH, resulting in an increase in the ratio between archaeal and bacterial copy numbers from a minimum of 0.002 to more than 0.07 at pH 8. The nonuniform archaeal response to pH could reflect variation in the archaeal community composition along the gradient, with some archaea adapted to acidic conditions and others to neutral to slightly alkaline conditions. This suggestion is reinforced by observations of contrasting outcomes of the (competitive) interactions between archaea, bacteria, and fungi toward the lower and higher ends of the examined pH gradient.

  6. Effect of soil pH on sorption of salinomycin in clay and sandy soils

    African Journals Online (AJOL)

    use

    The sorption of salinomycin to the sandy soil marginally increased as the pH decreased, while the sorption to the two .... plastic containers at room temperature for further analysis. ... The pH was adjusted eight times over 20 days to stabilize at.

  7. Earthworm bioturbation influences the phytoavailability of metals released by particles in cultivated soils

    International Nuclear Information System (INIS)

    Leveque, Thibaut; Capowiez, Yvan; Schreck, Eva; Xiong, Tiantian; Foucault, Yann

    2014-01-01

    The influence of earthworm activity on soil-to-plant metal transfer was studied by carrying out six weeks mesocosms experiments with or without lettuce and/or earthworms in soil with a gradient of metal concentrations due to particles fallouts. Soil characteristics, metal concentrations in lettuce and earthworms were measured and soil porosity in the mesocosms was determined. Earthworms increased the soil pH, macroporosity and soil organic matter content due to the burying of wheat straw provided as food. Earthworm activities increased the metals concentrations in lettuce leaves. Pb and Cd concentrations in lettuce leaves can increase up to 46% with earthworm activities … These results and the low correlation between estimated by CaCl 2 and EDTA and measured pollutant phytoavailability suggest that earthworm bioturbation was the main cause of the increase. Bioturbation could affect the proximity of pollutants to the roots and soil organic matter. - Highlights: • Earthworm bioturbation increases phytoavailability of Pb, Cd, Zn and Cu. • Earthworm activity influences soil structure and increases pH. • Plant metal uptake was not correlated with CaCl 2 , EDTA estimated phytoavailability. • Increased metal phytoavailability with bioturbation could increase human exposure. - Earthworm activities can increase metal phytoavailability and subsequent human exposure to metals in consumed vegetables

  8. Effects of sodium hypochlorite and high pH buffer solution in electrokinetic soil treatment on soil chromium removal and the functional diversity of soil microbial community

    International Nuclear Information System (INIS)

    Cang Long; Zhou Dongmei; Alshawabkeh, Akram N.; Chen Haifeng

    2007-01-01

    Effects of sodium hypochlorite (NaClO), applied as an oxidant in catholyte, and high pH buffer solution on soil Cr removal and the functional diversity of soil microbial community during enhanced electrokinetic treatments of a chromium (Cr) contaminated red soil are evaluated. Using pH control system to maintain high alkalinity of soil together with the use of NaClO increased the electrical conductivities of soil pore liquid and electroosmotic flux compared with the control (Exp-01). The pH control and NaClO improved the removal of Cr(VI) and total Cr from the soil. The highest removal percentages of soil Cr(VI) and total Cr were 96 and 72%, respectively, in Exp-04 when the pH value of the anolyte was controlled at 10 and NaClO was added in the catholyte. The alkaline soil environment and introduction of NaClO in the soil enhanced the desorption of Cr(VI) from the soil and promoted Cr(III) oxidation to mobile Cr(VI), respectively. However, the elevated pH and introduction of NaClO in the soil, which are necessary for improving the removal efficiency of soil Cr, resulted in a significantly adverse impact on the functional diversity of soil microbial community. It suggests that to assess the negative impact of extreme conditions for enhancing the extraction efficiencies of Cr on the soil properties and function is necessary

  9. Biogeochemical features technogenic pollution of soils under the influence chemical industry

    Directory of Open Access Journals (Sweden)

    Kuraeva I.V.

    2015-09-01

    Full Text Available The physico-chemical properties of soil (pH, organic matter content, cation exchange capacity. The regularities of the distribution of total and mobile forms of heavy metals in soil sediments in the territory of Shostka Sumy region under the influence of the chemical industry and in the background areas. Biogeochemical indicators obtained content of microscopic fungi and their species, the most characteristic of the study of soils, which can be used as an additional criterion for ecological and geochemical studies.

  10. Adsorption-Desorption of Hexaconazole in Soils with Respect to Soil Properties, Temperature, and pH

    Directory of Open Access Journals (Sweden)

    Maznah Zainol

    2016-06-01

    Full Text Available The effect of temperature and pH on adsorption-desorption of fungicide hexaconazole was studied in two Malaysian soil types; namely clay loam and sandy loam. The adsorption-desorption experiment was conducted using the batch equilibration technique and the residues of hexaconazole were analysed using the GC-ECD. The results showed that the adsorption-desorption isotherms of hexaconazole can be described with Freundlich equation. The Freundlich sorption coefficient (Kd values were positively correlated to the clay and organic matter content in the soils. Hexaconazole attained the equilibrium phase within 24 h in both soil types studied. The adsorption coefficient (Kd values obtained for clay loam soil and sandy loam soil were 2.54 mL/g and 2.27 mL/g, respectively, indicating that hexaconazole was weakly sorbed onto the soils due to the low organic content of the soils. Regarding thermodynamic parameters, the Gibb’s free energy change (ΔG analysis showed that hexaconazole adsorption onto soil was spontaneous and exothermic, plus it exhibited positive hysteresis. A strong correlation was observed between the adsorption of hexaconazole and pH of the soil solution. However, temperature was found to have no effect on the adsorption of hexaconazole onto the soils; for the range tested.

  11. Microbial community structure and soil pH correspond to methane production in Arctic Alaska soils.

    Science.gov (United States)

    Wagner, Robert; Zona, Donatella; Oechel, Walter; Lipson, David

    2017-08-01

    While there is no doubt that biogenic methane production in the Arctic is an important aspect of global methane emissions, the relative roles of microbial community characteristics and soil environmental conditions in controlling Arctic methane emissions remains uncertain. Here, relevant methane-cycling microbial groups were investigated at two remote Arctic sites with respect to soil potential methane production (PMP). Percent abundances of methanogens and iron-reducing bacteria correlated with increased PMP, while methanotrophs correlated with decreased PMP. Interestingly, α-diversity of the methanogens was positively correlated with PMP, while β-diversity was unrelated to PMP. The β-diversity of the entire microbial community, however, was related to PMP. Shannon diversity was a better correlate of PMP than Simpson diversity across analyses, while rarefied species richness was a weak correlate of PMP. These results demonstrate the following: first, soil pH and microbial community structure both probably control methane production in Arctic soils. Second, there may be high functional redundancy in the methanogens with regard to methane production. Third, iron-reducing bacteria co-occur with methanogens in Arctic soils, and iron-reduction-mediated effects on methanogenesis may be controlled by α- and β-diversity. And finally, species evenness and rare species abundances may be driving relationships between microbial groups, influencing Arctic methane production. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  12. Relation Between pH and Desorption of Cu, Cr, Zn, and Pb from Industrially Polluted Soils

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Hansen, Henrik K.; Jensen, Pernille Erland

    2009-01-01

    Desorption of Cu, Cr, Pb, and Zn from industrially polluted soils as a result of acidification is in focus. The eight soils of the investigation vary greatly in composition and heavy metal concentration/combination. Three soils had elevated concentrations of Cu, Pb, and Zn; regardless of pollution...... level, pollution origin, and soil type, the order for desorption as pH decreased was Zn > Cu > Pb. Turning to a single heavy metal in different soils, there was a huge difference in the pH at which the major desorption started. The variation was most significant for Pb where, e.g., less than 10......% was desorbed at pH 2.5 from one soil, whereas in another soil 60% Pb was desorbed at this pH. Sequential extraction was made and the soils in which a high percentage of Pb was found in the residual phase (adsorbed strongest) was also the soils where less Pb was desorbed at low pH in the desorption experiments...

  13. Fluctuations in ammonia oxidizing communities across agricultural soils are driven by soil structure and pH

    NARCIS (Netherlands)

    de Cassia Pereira e Silva, M.; Poly, F.; Guillaumaud, N.; van Elsas, J.D.; Falcao Salles, J.

    2012-01-01

    The milieu in soil in which microorganisms dwell is never constant. Conditions such as temperature, water availability, pH and nutrients frequently change, impacting the overall functioning of the soil system. To understand the effects of such factors on soil functioning, proxies (indicators) of

  14. Biochar alters microbial community and carbon sequestration potential across different soil pH.

    Science.gov (United States)

    Sheng, Yaqi; Zhu, Lizhong

    2018-05-01

    Biochar application to soil has been proposed for soil carbon sequestration and global warming mitigation. While recent studies have demonstrated that soil pH was a main factor affecting soil microbial community and stability of biochar, little information is available for the microbiome across different soil pH and the subsequently CO 2 emission. To investigate soil microbial response and CO 2 emission of biochar across different pH levels, comparative incubation studies on CO 2 emission, degradation of biochar, and microbial communities in a ferralsol (pH5.19) and a phaeozems (pH7.81) with 4 biochar addition rates (0.5%, 1.0%, 2.0%, 5.0%) were conducted. Biochar induced higher CO 2 emission in acidic ferralsol, largely due to the higher biochar degradation, while the more drastic negative priming effect (PE) of SOC resulted in decreased total CO 2 emission in alkaline phaeozems. The higher bacteria diversity, especially the enrichment of copiotrophic bacteria such as Bacteroidetes, Gemmatimonadetes, and decrease of oligotrophic bacteria such as Acidobacteria, were responsible for the increased CO 2 emission and initial positive PE of SOC in ferralsol, whereas biochar did not change the relative abundances of most bacteria at phylum level in phaeozems. The relative abundances of other bacterial taxa (i.e. Actinobacteria, Anaerolineae) known to degrade aromatic compounds were also elevated in both soils. Soil pH was considered to be the dominant factor to affect CO 2 emission by increasing the bioavailability of organic carbon and abundance of copiotrophic bacteria after biochar addition in ferralsol. However, the decreased bioavailability of SOC via adsorption of biochar resulted in higher abundance of oligotrophic bacteria in phaeozems, leading to the decrease in CO 2 emission. Copyright © 2017. Published by Elsevier B.V.

  15. pH controls over methanogenesis and iron reduction along soil depth profile in Arctic tundra

    Science.gov (United States)

    Zheng, J.; Gu, B.; Wullschleger, S. D.; Graham, D. E.

    2017-12-01

    Increasing soil temperature in the Arctic is expected to accelerate rates of soil organic matter decomposition. However, the magnitude of this impact is uncertain due to the many physical, chemical, and biological processes that control the decomposition pathways. Varying soil redox conditions present a key control over pathways of organic matter decomposition by diverting the flow of reductants among different electron accepting processes and further driving acid-base reactions that alter soil pH. In this study we investigated the pH controls over anaerobic carbon mineralization, methanogenesis, Fe(III) reduction and the interplay between these processes across a range of pH and redox conditions. pH manipulation experiments were conducted by incubating soils representing organic, mineral, cryoturbated transitional layers and permafrost. In the experiments we sought to understand (1) if methanogenesis or Fe(III) reduction had similar pH optima; (2) if this pH response also occurs at `upstream' fermentation process; and (3) if pH alters organo-mineral association or organic matter sorption and desorption and its availability for microbial degradation. Our preliminary results suggest that the common bell-shaped pH response curve provides a good fit for both Fe(III) reduction and methanogenesis, with optimum pH at 6.0-7.0. Exceptions to this were found in transitional layer where methanogenesis rates positively correlated with increasing pH, with maximum rates measured at pH 8.5. It is likely that the transitional layer harbors distinct groups of methanogens that prefer a high pH. Variations in the optimum pH of Fe(III) reduction and methanogenesis may play a significant role in regulating organic matter decomposition pathways and thus greenhouse gas production in thawing soils. These results support biogeochemical modeling efforts to accurately simulate organic matter decomposition under changing redox and pH conditions.

  16. Long-term changes in soil pH across major forest ecosystems in China

    Science.gov (United States)

    Yang, Yuanhe; Li, Pin; He, Honglin; Zhao, Xia; Datta, Arindam; Ma, Wenhong; Zhang, Ying; Liu, Xuejun; Han, Wenxuan; Wilson, Maxwell C.; Fang, Jingyun

    2015-02-01

    Atmospheric acidic deposition has been a major environmental problem since the industrial revolution. However, our understanding of the effect of acidic deposition on soil pH is inconclusive. Here we examined temporal variations in topsoil pH and their relationships with atmospheric sulfur and nitrogen deposition across China's forests from the 1980s to the 2000s. To accomplish this goal, we conducted artificial neural network simulations using historical soil inventory data from the 1980s and a data set synthesized from literature published after 2000. Our results indicated that significant decreases in soil pH occurred in broadleaved forests, while minor changes were observed in coniferous and mixed coniferous and broadleaved forests. The magnitude of soil pH change was negatively correlated with atmospheric sulfur and nitrogen deposition. This relationship highlights the need for stringent measures that reduce sulfur and nitrogen emissions so as to maintain ecosystem structure and function.

  17. Relationship among Phosphorus Circulation Activity, Bacterial Biomass, pH, and Mineral Concentration in Agricultural Soil

    Directory of Open Access Journals (Sweden)

    Dinesh Adhikari

    2017-12-01

    Full Text Available Improvement of phosphorus circulation in the soil is necessary to enhance phosphorus availability to plants. Phosphorus circulation activity is an index of soil’s ability to supply soluble phosphorus from organic phosphorus in the soil solution. To understand the relationship among phosphorus circulation activity; bacterial biomass; pH; and Fe, Al, and Ca concentrations (described as mineral concentration in this paper in agricultural soil, 232 soil samples from various agricultural fields were collected and analyzed. A weak relationship between phosphorus circulation activity and bacterial biomass was observed in all soil samples (R2 = 0.25, and this relationship became significantly stronger at near-neutral pH (6.0–7.3; R2 = 0.67. No relationship between phosphorus circulation activity and bacterial biomass was observed at acidic (pH < 6.0 or alkaline (pH > 7.3 pH. A negative correlation between Fe and Al concentrations and phosphorus circulation activity was observed at acidic pH (R2 = 0.72 and 0.73, respectively, as well as for Ca at alkaline pH (R2 = 0.64. Therefore, bacterial biomass, pH, and mineral concentration should be considered together for activation of phosphorus circulation activity in the soil. A relationship model was proposed based on the effects of bacterial biomass and mineral concentration on phosphorus circulation activity. The suitable conditions of bacterial biomass, pH, and mineral concentration for phosphorus circulation activity could be estimated from the relationship model.

  18. pH effects of the addition of three biochars to acidic Indonesian mineral soils

    DEFF Research Database (Denmark)

    Martinsen, V; Alling, V; Nurida, N L

    2015-01-01

    of increasing amounts (0–30%; weight:weight) of three types of field-produced BCs (from cacao (Theobroma cacao. L.) shell, oil palm (Elaeis guineensis. Jacq.) shell and rice (Oryza sativa. L.) husk) on soil pH and CEC. Soils were sampled from croplands at Java, Sumatra and Kalimantan, Indonesia. All BCs caused...... a significant increase in mean soil pH with a stronger response and a greater maximum increase for the cacao shell BC addition, due to a greater acid neutralizing capacity (ANC) and larger amounts of extractable base cations. At 1% BC addition, corresponding to about 30 tons ha−1, the estimated increase in soil...... pH from the initial mean pH of 4.7 was about 0.5 units for the cacao shell BC, whereas this was only 0.05 and 0.04 units for the oil palm shell and rice husk BC, respectively. Besides depending on BC type, the increase in soil pH upon the addition of each of the three BCs was mainly dependent...

  19. Soil pH is a Key Determinant of Soil Fungal Community Composition in the Ny-Ålesund Region, Svalbard (High Arctic)

    Science.gov (United States)

    Zhang, Tao; Wang, Neng-Fei; Liu, Hong-Yu; Zhang, Yu-Qin; Yu, Li-Yan

    2016-01-01

    This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic). A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS) region. The following eight soil properties were analyzed: pH, organic carbon (C), organic nitrogen (N), ammonium nitrogen (NH4+-N), silicate silicon (SiO42--Si), nitrite nitrogen (NO2--N), phosphate phosphorus (PO43--P), and nitrate nitrogen (NO3--N). A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs) were found. of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>eight soil samples) were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda) and analysis of similarities (ANOSIM) revealed that soil pH (p = 0.001) was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8–9, whereas Sordariales predominated in soils of pH 7–8 and Coniochaetales predominated in soils of pH 6–7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic. PMID:26955371

  20. Soil pH is a key determinant of soil fungal community composition in the Ny-Ålesund Region, Svalbard (High Arctic

    Directory of Open Access Journals (Sweden)

    Tao eZhang

    2016-02-01

    Full Text Available This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic. A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS region. The following eight soil properties were analyzed: pH, organic carbon (C, organic nitrogen (N, ammonium nitrogen (NH4+-N, silicate silicon (SiO42--Si, nitrite nitrogen (NO2--N, phosphate phosphorus (PO43--P and nitrate nitrogen (NO3--N. A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs were found. Of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>8 soil samples were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda and analysis of similarities (ANOSIM revealed that soil pH (p=0.001 was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8-9, whereas Sordariales predominated in soils of pH 7-8 and Coniochaetales predominated in soil samples of pH 6-7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic.

  1. Effect of organic matter and pH on the adsorption of metalaxyl and penconazole by soils

    Energy Technology Data Exchange (ETDEWEB)

    Gondar, Dora; López, Rocío [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Antelo, Juan [Departamento de Edafología y Química Agrícola, Facultad de Biología, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Fiol, Sarah, E-mail: sarah.fiol@usc.es [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Arce, Florencio [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2013-09-15

    Highlights: • The adsorption of non-ionic pesticides on soils is affected by pH. • At pH < 5, the C{sub s}{sup OC}/C{sub e} ratio increased as the pH of the medium decreased. • The effect of pH on adsorption is related to the ionization of carboxylic groups. • SOM charge had similar effect on C{sub s}{sup OC}/C{sub e} in the four soils under study. -- Abstract: Soil organic matter (SOM) is considered to be the primary adsorbent of non-ionic pesticides, and it is therefore thought to determine the concentration of such pesticides in the soil solution and how they are transported throughout the medium. It is generally assumed that the sorption capacity of different soils is the same per unit mass of SOM; however, the reactivity also depends on the SOM composition and the pH of the medium. We carried out experiments to study the effects of pH and ionic strength on the adsorption of the non-ionic fungicides metalaxyl and penconazole on four soils containing different amounts of organic carbon. The adsorption isotherms fitted a Freundlich equation. For pH > 5, partitioning of the fungicides between the solid phase and the soil solution did not vary with the pH, while at lower pH, the fraction adsorbed on the solid phase increased as the pH decreased. The response was related to the effect of pH on the ionization of the carboxylic groups of the SOM and therefore to the hydrophilic nature of the SOM. Analysis of the charge effect on the partitioning of both fungicides revealed a common response in all four soils. Adsorption appears to be related to the magnitude of the charge developed at the SOM due to ionization of the carboxylic acid groups.

  2. Soil pH effects on the interactions between dissolved zinc, non-nano- and nano-ZnO with soil bacterial communities

    DEFF Research Database (Denmark)

    Read, Daniel S.; Matzke, Marianne; Gweon, Hyun S.

    2016-01-01

    nanoparticles due to the practice of applying sewage sludge as a fertiliser or as an organic soil improver. However, understanding on the interactions between soil properties, nanoparticles and the organisms that live within soil is lacking, especially with regards to soil bacterial communities. We studied......Zinc oxide nanoparticles (ZnO NPs) are used in an array of products and processes, ranging from personal care products to antifouling paints, textiles, food additives, antibacterial agents and environmental remediation processes. Soils are an environment likely to be exposed to manmade...... the effects of nanoparticulate, non-nanoparticulate and ionic zinc (in the form of zinc chloride) on the composition of bacterial communities in soil with a modified pH range (from pH 4.5 to pH 7.2). We observed strong pH-dependent effects on the interaction between bacterial communities and all forms of zinc...

  3. Effect of pH on boron adsorption in some soils of Paraná, Brazil

    Directory of Open Access Journals (Sweden)

    Fábio Steiner

    2013-06-01

    Full Text Available Temporary B deficiency can be triggered by liming of acid soils because of increased B adsorption at higher soil pH. Plants respond directly to the activity of B in soil solution and only indirectly to B adsorbed on soil constituents. Because the range between deficient and toxic B concentration is relatively narrow, this poses difficulty in maintaining appropriate B levels in soil solution. Thus, knowledge of the chemical behavior of B in the soil is particularly important. The present study investigated the effect of soil pH on B adsorption in four soils of Paraná State, and to correlate these values with the physical and chemical properties of the soils. Surface samples were taken from a Rhodic Hapludox, Arenic Hapludalf, Arenic Hapludult, and one Typic Usthorthent. To evaluate the effect of pH on B adsorption, subsamples soil received the application of increasing rates of calcium carbonate. Boron adsorption was accomplished by shaking 2.0 g soil, for 24 h, with 20 mL of 0.01 mol L¹ NaCl solution containing different concentrations (0.0, 0.1, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0, and 4.0 mg B L-1. Sorption was fitted to non-linear form of the Langmuir adsorption isotherm. Boron adsorption increased as concentration increased. Boron adsorption was dependent on soil pH, increasing as a function of pH in the range between 4.6 and 7.4, although the bonding energy has decreased. Maximum adsorption capacity (MAC of B was observed in the Arenic Hapludalf (49.8 mg B kg-1 soil followed by Arenic Hapludult (22.5 mg kg-1, Rhodic Hapludox (17.4 mg kg-1, and Typic Usthorthent (7.0 mg kg-1. The organic matter content, clay content, and aluminum oxide content (Al2O3 were the soils properties that affecting the B adsorption on Paraná soils.

  4. Manganese toxicity in pasture legumes. II. Effects of pH and molybdenum levels in the substrate

    Energy Technology Data Exchange (ETDEWEB)

    Truong, N V; Andrew, C S; Wilson, G L

    1971-06-01

    The effects of pH and Mo levels in the growing media on Mn toxicity were investigated for white clover and five tropical pasture legume species. In solution culture, high Mo supply did not influence Mn toxicity. However, in two species, it caused Mo toxicity. High solution pH intensified Mn toxicity in white clover, probably by way of uptake. The effects of Ca and P on Mn toxicity reported in a previous paper, were not greatly influenced by solution pH. In the soil, Mo application greatly increased dry matter yield of white clover grown on soils high in exchangeable Mn. This effect was more easily attributed to an influence on N metabolism of the legume plant than on Mn toxicity. Measured soil pH was found to have little influence on the level of exchangeable Mn in the soil. However the larger pH changes in small soil pockets, resulting from non-uniform incorporation of chemicals in the soil, might have a more important effect on this fraction of soil Mn. 31 references, 7 tables.

  5. Soil solution Zn and pH dynamics in non-rhizosphere soil and in the rhizosphere of Thlaspi caerulescens grown in a Zn/Cd-contaminated soil.

    Science.gov (United States)

    Luo, Y M; Christie, P; Baker, A J

    2000-07-01

    Temporal changes in soil solution properties and metal speciation were studied in non-rhizosphere soil and in the rhizosphere of the hyperaccumulator Thlaspi caerulescens J. & C. Presl (population from Prayon, Belgium) grown in a Zn- and Cd-contaminated soil. This paper focuses on soil solution Zn and pH dynamics during phytoextraction. The concentration of Zn in both non-rhizosphere and rhizosphere soil solutions decreased from 23 mg/l at the beginning to 2 mg/l at the end of the experiment (84 days after transplanting of seedlings), mainly due to chemical sorption. There was no significant difference in overall Zn concentration between the planted and the unplanted soil solutions (P > 0.05). Soil solution pH decreased initially and then increased slightly in both planted and unplanted soil zones. From 60 to 84 days after transplanting, the pH of the rhizosphere soil solution was higher than that of non-rhizosphere soil solution (P<0.05). Zn uptake by the hyperaccumulator plants was 8.8 mg per pot (each containing 1 kg oven-dry soil) on average. The data indicate that the potential of T. caerulescens to remove Zn from contaminated soil may not be related to acidification of the rhizosphere.

  6. Spatial variability of soil pH based on GIS combined with geostatistics in Panzhihua tobacco area

    International Nuclear Information System (INIS)

    Du Wei; Wang Changquan; Li Bing; Li Qiquan; Du Qian; Hu Jianxin; Liu Chaoke

    2012-01-01

    GIS and geostatistics were utilized to study the spatial variability of soil pH in Panzhihua tobacco area. Results showed that pH values in this area ranged from 4.5 to 8.3, especially 5.5 to 6.5, and in few areas were lower than 5.0 or higher than 7.0 which can meet the need of high-quality tobacco production. The best fitting model of variogram was exponential model with the nugget/sill of soil pH in 13.61% indicating strong spatial correlation. The change process was 5.40 km and the coefficient of determination was 0.491. The spatial variability of soil pH was mainly caused by structural factors such as cane, topography and soil type. The soil pH in Panzhihua tobacco area also showed a increasing trend of northwest to southeast trend. The pH of some areas in Caochang, Gonghe and Yumen were lower, and in Dalongtan were slightly higher. (authors)

  7. [Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

    Science.gov (United States)

    Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

    2009-10-15

    To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

  8. Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

    Science.gov (United States)

    Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

    2015-06-16

    Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem.

  9. Chemigation with micronized sulfur rapidly reduces soil pH in northern highbush blueberry

    Science.gov (United States)

    Northern highbush blueberry is adapted to low soil pH in the range of 4.5–5.5. When pH is higher, soil is usually acidified by incorporating elemental sulfur (S) prior to planting. A study was conducted to determine the potential of applying micronized S by chemigation through the drip system to red...

  10. The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Rastas Amofah, Lea; Maurice, Christian; Kumpiene, Jurate [Luleaa Univ. of Technology, Luleaa (Sweden). Dept. of Civil, Environmental and Natural Resources; Bhattacharya, Prosun [Royal Institute of Technology (KTH), Stockholm (Sweden). Dept. of Land and Water Resources Engineering

    2011-12-15

    Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20 C, 30 C and 40 C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. For all extractants, mobilisation was most efficient at elevated temperature (40 C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed

  11. Soil solution dynamics of Cu and Zn in a Cu- and Zn-polluted soil as influenced by gamma-irradiation and Cu-Zn interaction.

    Science.gov (United States)

    Luo, Y M; Yan, W D; Christie, P

    2001-01-01

    A pot experiment was conducted to study soil solution dynamics of Cu and Zn in a Cu/Zn-polluted soil as influenced by gamma-irradiation and Cu-Zn interaction. A slightly acid sandy loam was amended with Cu and Zn (as nitrates) either singly or in combination (100 mg Cu and 150 mg Zn kg(-1) soil) and was then gamma-irradiated (10 kGy). Unamended and unirradiated controls were included, and spring barley (Hordeum vulgare L. cv. Forrester) was grown for 50 days. Soil solution samples obtained using soil moisture samplers immediately before transplantation and every ten days thereafter were used directly for determination of Cu, Zn, pH and absorbance at 360 nm (A360). Cu and Zn concentrations in the solution of metal-polluted soil changed with time and were affected by gamma-irradiation and metal interaction. gamma-Irradiation raised soil solution Cu substantially but generally decreased soil solution Zn. These trends were consistent with increased dissolved organic matter (A360) and solution pH after gamma-irradiation. Combined addition of Cu and Zn usually gave higher soil solution concentrations of Cu or Zn compared with single addition of Cu or Zn in gamma-irradiated and non-irradiated soils, indicating an interaction between Cu and Zn. Cu would have been organically complexed and consequently maintained a relatively high concentration in the soil solution under higher pH conditions. Zn tends to occur mainly as free ion forms in the soil solution and is therefore sensitive to changes in pH. The extent to which gamma-irradiation and metal interaction affected solubility and bioavailability of Cu and Zn was a function of time during plant growth. Studies on soil solution metal dynamics provide very useful information for understanding metal mobility and bioavailability.

  12. Influence of ageing on zinc bioavailability in soils

    Energy Technology Data Exchange (ETDEWEB)

    Lock, K.; Janssen, C.R

    2003-12-01

    Currently, soil quality criteria or soil risk assessments of metals are based on laboratory toxicity tests which are carried out in soils freshly spiked with metal salts. With these data, species sensitivity distributions are fitted, from which hazardous concentrations and predicted no effect concentrations are derived. However, due to long-term processes, called ageing, soil metal availability decreases with time. Here we show that pH is the most important parameter determining the effect of ageing on zinc partitioning in soils, with the effect of ageing becoming more important with increasing pH. Furthermore, zinc bioavailability, expressed as the internal zinc concentrations in red clover (Trifolium pratense) is closely related to pore water zinc concentration. In addition, there is a clear dose-response relationship between the survival of the earthworm Eisenia fetida and the calcium chloride-extracted zinc fraction. These results indicate that zinc partitioning can be used to predict zinc bioavailability to terrestrial organisms. However, the use of spiked soils in toxicity assays can result in an over-estimation of the effects of zinc, especially at a high pH. - Zn ageing is affected by pH, while Zn partitioning can be used to predict its bioavailability.

  13. Influence of xenobiotics on the microbiological and agrochemical parameters of soddy-podzolic soil

    Science.gov (United States)

    Vakkerov-Kouzova, N. D.

    2010-08-01

    We studied the influence of various chemical compounds, i.e., azobenzene (an insecticide and acaricide), nitrification inhibitors (DCD, dicyandiamide and DMPP, and 3,4-dimetylpyrazolphosphate), and inhibitors of urease activity (HQ-hydroquinone), on the agrochemical and microbiological parameters of a soddy-podzolic soil. It is proved that these xenobiotics are able to influence the agrochemical parameters (the pH and the content of NO{3/-} and NH{4/+}, the microbial activity (the basal respiration, the microbial mass carbon, and the microbial quotient), and the number of bacteria of different physiological groups in soddypodzolic soil. The influence of the xenobiotics was preserved for some time, which testified to their persistence in the soil. Upon cultivating the soil microorganisms in different media, the growth of the heterotrophic bacteria was inhibited, the radial growth velocity was slowed down, and the sporogenesis of the micromycetes was retarded. The toxic effect of the xenobiotics was higher with their increasing concentrations.

  14. [Variation characteristics of farmland soil pH in the past 30 years of Enshi Autonomous Prefecture, Hubei, China].

    Science.gov (United States)

    Hu, Min; Xiang, Yong Sheng; Zhang, Zhi; Cong, Ri Huan; Huang, Fei Yue; Zhang, Jun Qiang; Shang, Li Li; Lu, Jian Wei

    2017-04-18

    In order to explore temporal-spatial variability of farmland soil pH at Enshi Antonomous Prefecture, Hubei, China, soil pH during the past three decades was analyzed, using the datasets of the Second National Soil Survey (1980-1983) and the Cultivated Land Quality Evaluation (2010-2013). The natural and human factors inducing the change of soil pH were evaluated to provide theoretical guidance for further soil acidification management. Results showed that acidic soil (i.e., pH<6.5) and neutral and alkaline soil (i.e., pH 6.5-8.5) were accounted for 98.4% and 1.6% in the farmland during the period of 2010-2013, respectively. The ratio increased 61.4% for the acidic soil but decreased 61.2% for the neutral and alkaline soil as compared with the period of 1980-1983. In addition, there was no alkaline soil (pH>8.5) in the region in 2010-2013. According to the dataset of the Second National Soil Survey (1980-1983), acidic soil was mainly distributed at Laifeng, Lichuan, Xuanen and Xianfeng counties, with the area ratio of 74.4%, 63.5%, 61.3% and 60.7%, respectively. For the period of 2010-2013, the ratio of acidic soil enhanced widely which was above 96% for each county. At Enshi Autonomous Prefecture, farmland soil showed an obvious acidification trend during the past three decades, with spatial variation of higher in the eastern part and lower in the western part of the region. Furthermore, soil pH decline occurred among different land use types in different areas. Overall, farmland soil pH declined 0.90 on average, with 1.14 decrease for upland and 0.87 for paddy soil, respectively. Clearly, upland soil acidification was severe than paddy soil. Factors related to soil acidification in the Enshi Autonomous Prefecture were mainly human factors such as unreasonable fertilizer combination, fertilizer ratio change, and more base cations taking away by high crop yield.

  15. Influence of soil solution cation composition on boron adsorption by soils

    Science.gov (United States)

    Boron (B) adsorption on five arid-zone soil samples from California was investigated as a function of solution pH (4-10) and cation composition (Na, Ca, or Mg). Boron adsorption increased with increasing solution pH, reached an adsorption maximum near pH 9, and decreased with further increases with...

  16. [Influence of organochlorine pesticides in wastewater on the soil along the channel].

    Science.gov (United States)

    Xu, Liang; Zhang, Cai-Xiang; Liu, Min; Liao, Xiao-Ping; Yao, Lin-Lin; Li, Jia-Le; Xiang, Qing-Qing

    2013-08-01

    Nine profile soil samples and two sewage water samples were collected from Xiaodian sewage irrigation area in Taiyuan city, concentrations of organochlorine pesticides (OCPs) were determined by the gas chromatography coupled with electron capture detector (GC-ECD) to analyze the influence of the leakage of sewage water. The result shows that OCPs in sewage water were mainly composed of HCHs. Concentrations of DDTs and other organochlorine pesticides were very low or out of the detection limit. Concentrations of sigmaOCPs and HCHs in eight profiles near irrigation channels to some extend decreased with the increasing of the linear distance off the channel, which shows influences of the leakage of sewage water on the soil nearby. Concentrations of HCHs clearly decreased with the increasing of soil depth in most profile soils. For the horizontal direction, concentrations of HCHs also decreased with the increasing of the linear distance off the channel. The correlation between HCHs and TOC was positive, but no correlation between pH and HCHs was found.

  17. Spatial variability of soil carbon, pH, available phosphorous and potassium in organic farm located in Mediterranean Croatia

    Science.gov (United States)

    Bogunović, Igor; Pereira, Paulo; Šeput, Miranda

    2016-04-01

    Soil organic carbon (SOC), pH, available phosphorus (P), and potassium (K) are some of the most important factors to soil fertility. These soil parameters are highly variable in space and time, with implications to crop production. The aim of this work is study the spatial variability of SOC, pH, P and K in an organic farm located in river Rasa valley (Croatia). A regular grid (100 x 100 m) was designed and 182 samples were collected on Silty Clay Loam soil. P, K and SOC showed moderate heterogeneity with coefficient of variation (CV) of 21.6%, 32.8% and 51.9%, respectively. Soil pH record low spatial variability with CV of 1.5%. Soil pH, P and SOC did not follow normal distribution. Only after a Box-Cox transformation, data respected the normality requirements. Directional exponential models were the best fitted and used to describe spatial autocorrelation. Soil pH, P and SOC showed strong spatial dependence with nugget to sill ratio with 13.78%, 0.00% and 20.29%, respectively. Only K recorded moderate spatial dependence. Semivariogram ranges indicate that future sampling interval could be 150 - 200 m in order to reduce sampling costs. Fourteen different interpolation models for mapping soil properties were tested. The method with lowest Root Mean Square Error was the most appropriated to map the variable. The results showed that radial basis function models (Spline with Tension and Completely Regularized Spline) for P and K were the best predictors, while Thin Plate Spline and inverse distance weighting models were the least accurate. The best interpolator for pH and SOC was the local polynomial with the power of 1, while the least accurate were Thin Plate Spline. According to soil nutrient maps investigated area record very rich supply with K while P supply was insufficient on largest part of area. Soil pH maps showed mostly neutral reaction while individual parts of alkaline soil indicate the possibility of penetration of seawater and salt accumulation in the

  18. Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

    Science.gov (United States)

    Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

  19. Variation in pH Optima of Hydrolytic Enzyme Activities in Tropical Rain Forest Soils

    OpenAIRE

    Turner, Benjamin L.

    2010-01-01

    Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly am...

  20. Influence of conventional biochar and ageing biochar application to arable soil on soil fertility and plant yield

    Science.gov (United States)

    Dvořáčková, Helena; Záhora, Jaroslav; Elbl, Jakub; Kynický, Jindřich; Hladký, Jan; Brtnický, Martin

    2017-04-01

    Biochar represents very controversial material which is product of pyrolysis. According to many studies biochar has positive effect on physical and chemical properties such as pH, conductivity, aggregates stability etc. Unfortunately biochar is product of combustion, so it can content toxic substance as are aromatic compound. These substances may have a negative effect on yield and microbial activities in soil. Our aim was eliminated concentration of toxic compound but preserved positive effect of biochar on soil properties. We was ageing/ activating of biochar in water environment and for soil inoculum we used native soil from landscape. Moreover two types of biochar was tested by pot experiment with seven variants, where conventional biochar from residual biomass and ageing biochar were applied in different doses: 10 t/ha, 20t/ha and 50 t/ha. Pots were placed in green house for 90 days and after the end of experiment the following parameters of soil fertility, health and quality were evaluated: content of soil organic matter, arbuscular mycorrhizal colonisation of Lactuca sativa L. roots, leaching of mineral nitrogen, changes in plant available nutrient content, EC and pH. Above all the total yield of indicator plant was observed. The significant (P plant yield and soil properties were found. The application of conventional biochar didn't have positive effect on plant yield in comparison with ageing biochar. The positive effect of ageing biochar addition on soil fertility was directly proportional to the dose which were applied - increasing in dose of ageing biochar resulted in increase of plant yield. Moreover the special experimental containers were used, where we was able to monitor the development of root in soil with and without addition of biochar (conventional or ageing). The positive influence of ageing biochar addition into soil on development of Lactuca sativa L. roots was observed.

  1. Long-term stabilization of crop residues and soil organic carbon affected by residue quality and initial soil pH.

    Science.gov (United States)

    Wang, Xiaojuan; Butterly, Clayton R; Baldock, Jeff A; Tang, Caixian

    2017-06-01

    Residues differing in quality and carbon (C) chemistry are presumed to contribute differently to soil pH change and long-term soil organic carbon (SOC) pools. This study examined the liming effect of different crop residues (canola, chickpea and wheat) down the soil profile (0-30cm) in two sandy soils differing in initial pH as well as the long-term stability of SOC at the amended layer (0-10cm) using mid-infrared (MIR) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. A field column experiment was conducted for 48months. Chickpea- and canola-residue amendments increased soil pH at 0-10cm in the Podzol by up to 0.47 and 0.36units, and in the Cambisol by 0.31 and 0.18units, respectively, at 48months when compared with the non-residue-amended control. The decomposition of crop residues was greatly retarded in the Podzol with lower initial soil pH during the first 9months. The MIR-predicted particulate organic C (POC) acted as the major C sink for residue-derived C in the Podzol. In contrast, depletion of POC and recovery of residue C in MIR-predicted humic organic C (HOC) were detected in the Cambisol within 3months. Residue types showed little impact on total SOC and its chemical composition in the Cambisol at 48months, in contrast to the Podzol. The final HOC and resistant organic C (ROC) pools in the Podzol amended with canola and chickpea residues were about 25% lower than the control. This apparent priming effect might be related to the greater liming effect of these two residues in the Podzol. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Migration characteristics of cobalt-60 through sandy soil in high pH solution

    International Nuclear Information System (INIS)

    Ohnuki, Toshihiko

    1992-01-01

    Migration characteristics of 60 Co through sandy soil in high pH solution has been investigated by both column and batch techniques. The association of 60 Co with the sandy soil and its components were studied by sequential extraction techniques. The concentration profile of 60 Co in the sandy soil column was composed of two exponential curves showing that 60 Co would consist of immobile and mobile fractions. The immobile 60 Co was retained by the sandy soil and was distributed near the top. Though the mobile 60 Co was little sorbed by soil and migrated through the soil column, maximum concentration of 60 Co in the effluents decreased slightly with increasing path length of the soil column. The sequential extraction of 60 Co from the sandy soil and from its components showed that 60 Co was sorbed by both manganese oxide and clay minerals. And manganese oxide is one of the responsible soil components for the observed decrease in the maximum concentration of 60 Co in the effluents. Although the content of manganese oxide in the sandy soil was 0.13%, manganese oxide is the important component to prevent from the migration of 60 Co in the high pH solution. (author)

  3. Using a toxicokinetics approach to explain the effect of soil pH on cadmium bioavailability to Folsomia candida

    International Nuclear Information System (INIS)

    Ardestani, Masoud M.; Gestel, Cornelis A.M. van

    2013-01-01

    The aim of this study was to improve our understanding of metal bioavailability in soil by linking the biotic ligand approach with toxicokinetics modelling. We determined cadmium bioaccumulation kinetics in Folsomia candida (Collembola) as a function of soil pH. Animals were exposed for 21 days to LUFA 2.2 soil at 5 or 20 μg Cd g −1 dry soil followed by 21 days elimination in clean soil. Internal cadmium concentrations were modelled using a first-order one-compartment model, relating uptake rate constants (k 1 ) to total soil, water or 0.01 M CaCl 2 extractable and porewater concentrations. Based on total soil concentrations, k 1 was independent of soil pH while it strongly increased with increasing pH based on porewater concentrations explaining the reduced competition of H + ions making cadmium more bioavailable in pore water at high pH. This shows that the principles of biotic ligand modelling are applicable to predict cadmium accumulation kinetics in soil-living invertebrates. -- Highlights: •Cadmium uptake and elimination in Folsomia candida were investigated. •Animals were exposed to LUFA 2.2 soil at different pH levels. •Langmuir isotherms were used to describe interaction of Ca and protons with Cd. •pH was the main factor affecting Cd toxicokinetics when pore water was considered. -- Integrating bioaccumulation kinetics with a BLM approach provides novel insights into the bioavailability of cadmium to springtails in soil

  4. Effect of soil pH on sorption of salinomycin in clay and sandy soils ...

    African Journals Online (AJOL)

    Desorption of salinomycin with methanol over a 72 h period was 70% with a phosphate buffer (pH 7). Since the phosphate buffer would mimic, to some extent, the quality of water flowing through field soils containing various salts, it was concluded that salinomycin could pose ...

  5. Distribution and function of carbamate hydrolase genes cehA and mcd in soils: the distinct role of soil pH.

    Science.gov (United States)

    Rousidou, Constantina; Karaiskos, Dionysis; Myti, Despoina; Karanasios, Evangelos; Karas, Panagiotis A; Tourna, Maria; Tzortzakakis, Emmanuel A; Karpouzas, Dimitrios G

    2017-01-01

    Synthetic carbamates constitute a significant pesticide group with oxamyl being a leading compound in the nematicide market. Oxamyl degradation in soil is mainly microbially mediated. However, the distribution and function of carbamate hydrolase genes (cehA, mcd, cahA) associated with the soil biodegradation of carbamates is not yet clear. We studied oxamyl degradation in 16 soils from a potato monoculture area in Greece where oxamyl is regularly used. Oxamyl showed low persistence (DT50 2.4-26.7 days). q-PCR detected the cehA and mcd genes in 10 and three soils, respectively. The abundance of the cehA gene was positively correlated with pH, while both cehA abundance and pH were negatively correlated with oxamyl DT50. Amongst the carbamates used in the study region, oxamyl stimulated the abundance and expression only of the cehA gene, while carbofuran stimulated the abundance and expression of both genes. The cehA gene was also detected in pristine soils upon repeated treatments with oxamyl and carbofuran and only in soils with pH ≥7.2, where the most rapid degradation of oxamyl was observed. These results have major implications regarding the maintenance of carbamate hydrolase genes in soils, have practical implications regarding the agricultural use of carbamates, and provide insights into the evolution of cehA. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Effects of some organic materials on bicarbonate extractable phosphate content of soils having different pH

    Directory of Open Access Journals (Sweden)

    Nutullah Özdemir

    2016-10-01

    Full Text Available This study was carried out to determine the effects of rice husk compost (RC, town waste compost (TW and tobacco waste (TB on bicarbonate extractable phosphate content (P in soils having different pH levels under greenhouse conditions. Soil samples used in this study were taken from surfaces (0-20 cm of agricultural fields around Samsun, Northern Anatolia. The experiment was conducted according to split plot design with four doses of organic matterials (0, 2.5, 5.0 and 7.5, %. After a month of mixing organic matterials into soils, lettuce were grown in the medias. According to the results, RC, TW and TB applications into acidic (Tepecik, neutral (Kampüs and alkaline (Çetinkaya soils increased extractable P content. It was observed that effectiveness of organic matterials changed depend on soil reaction, type and dose of organic matterials. All organic wastes were more effective on increment of bicarbonate extractable phosphate content in neutral soil pH when compared the other soil pH levels.

  7. Lead, zinc and pH concentrations of Enyigba soils in Abakaliki Local ...

    African Journals Online (AJOL)

    The concentrations of lead (Pb) and zinc (Zn) were quantitatively determined in surface and sub-surface soils in Enyigba, Ebonyi State, Nigerian's major lead mining area using atomic absorption spectrophotometer. pH status of the soils was similarly determined. The survey was conducted to establish a base line pollution ...

  8. Can we predict uranium bioavailability based on soil parameters? Part 1: Effect of soil parameters on soil solution uranium concentration

    International Nuclear Information System (INIS)

    Vandenhove, H.; Hees, M. van; Wouters, K.; Wannijn, J.

    2007-01-01

    Present study aims to quantify the influence of soil parameters on soil solution uranium concentration for 238 U spiked soils. Eighteen soils collected under pasture were selected such that they covered a wide range for those parameters hypothesised as being potentially important in determining U sorption. Maximum soil solution uranium concentrations were observed at alkaline pH, high inorganic carbon content and low cation exchange capacity, organic matter content, clay content, amorphous Fe and phosphate levels. Except for the significant correlation between the solid-liquid distribution coefficients (K d , L kg -1 ) and the organic matter content (R 2 = 0.70) and amorphous Fe content (R 2 = 0.63), there was no single soil parameter significantly explaining the soil solution uranium concentration (which varied 100-fold). Above pH = 6, log(K d ) was linearly related with pH [log(K d ) = - 1.18 pH + 10.8, R 2 = 0.65]. Multiple linear regression analysis did result in improved predictions of the soil solution uranium concentration but the model was complex. - Uranium solubility in soil can be predicted from organic matter or amorphous iron content and pH or with complex multilinear models considering several soil parameters

  9. [Aluminum dissolution and changes of pH in soil solution during sorption of copper by aggregates of paddy soil].

    Science.gov (United States)

    Xu, Hai-Bo; Zhao, Dao-Yuan; Qin, Chao; Li, Yu-Jiao; Dong, Chang-Xun

    2014-01-01

    Size fractions of soil aggregates in Lake Tai region were collected by the low-energy ultrasonic dispersion and the freeze-desiccation methods. The dissolution of aluminum and changes of pH in soil solution during sorption of Cu2+ and changes of the dissolution of aluminum at different pH in the solution of Cu2+ by aggregates were studied by the equilibrium sorption method. The results showed that in the process of Cu2+ sorption by aggregates, the aluminum was dissoluted and the pH decreased. The elution amount of aluminum and the decrease of pH changed with the sorption of Cu2+, both increasing with the increase of Cu2+ sorption. Under the same conditions, the dissolution of aluminum and the decrease of pH were in the order of coarse silt fraction > silt fraction > sand fraction > clay fraction, which was negatively correlated with the amount of iron oxide, aluminum and organic matter. It suggested that iron oxide, aluminum and organic matters had inhibitory and buffering effect on the aluminum dissolution and the decrease of pH during the sorption of Cu2+.

  10. Influence of a soil enzyme on iron-cyanide complex speciation and mineral adsorption.

    Science.gov (United States)

    Zimmerman, Andrew R; Kang, Dong-Hee; Ahn, Mi-Youn; Hyun, Seunghun; Banks, M Katherine

    2008-01-01

    Cyanide is commonly found as ferrocyanide [Fe(II)(CN)(6)](-4) and in the more mobile form, ferricyanide [Fe(III)(CN)(6)](-3) in contaminated soils and sediments. Although soil minerals may influence ferrocyanide speciation, and thus mobility, the possible influence of soil enzymes has not been examined. In a series of experiments conducted under a range of soil-like conditions, laccase, a phenoloxidase enzyme derived from the fungi Trametes versicolor, was found to exert a large influence on iron-cyanide speciation and mobility. In the presence of laccase, up to 93% of ferrocyanide (36-362ppm) was oxidized to ferricyanide within 4h. No significant effect of pH (3.6 and 6.2) or initial ferrocyanide concentration on the extent or rate of oxidation was found and ferrocyanide oxidation did not occur in the absence of laccase. Relative to iron-cyanide-mineral systems without laccase, ferrocyanide adsorption to aluminum hydroxide and montmorillonite decreased in the presence of laccase and was similar to or somewhat greater than that of ferricyanide without laccase. Laccase-catalyzed conversion of ferrocyanide to ferricyanide was extensive though up to 33% of the enzyme was mineral-bound. These results demonstrate that soil enzymes can play a major role in ferrocyanide speciation and mobility. Biotic soil components must be considered as highly effective oxidation catalysts that may alter the mobility of metals and metal complexes in soil. Immobilized enzymes should also be considered for use in soil metal remediation efforts.

  11. The effect of soil pH and the fungicide 'Captan' on 134Cs transfer factors for cucumber and radish plants

    International Nuclear Information System (INIS)

    Skarlou, V.; Massas, I.; Anoussis, J.; Haidouti, C.; Arapis, G.

    1999-01-01

    The effect of soil pH and the fungicide 'Captan' on 134 Cs transfer factors (TFs) was studied in a greenhouse pot experiment with cucumber and radish plants. A soil with a low pH (4.2) was selected and its pH value has increased to 5.7, 6.5 and 7.6 by the addition of different amounts of Ca(OH) 2 . Liming of the soil and the subsequent increase in pH values resulted in a reduction of 134 Cs TFs which was not always significant. TFs were the highest in the very acid soil (pH 4.2) and were practically the same above the pH 5.7 although they were the lowest in the calcareous soil. The ratio highest / lowest TF of each crop or plant part ranged between ∼ 2.0 for radish and 4.5 for cucumber plants and it was much lower than that previously reported and attributed to pH differences. Edible to other plant material TF ratio indicates that cucumber plant accumulates considerably more of the totally absorbed 134 CS in the edible part than radish crops. When biomass production was used for excluding dilution effects, 134 CS total activity (Bq/pot) was higher for both plants when grown in the intermediate soil pH (5.7 - 6.5), due to the higher yield at these pH values. The application of the fungicide 'Captan' gave no significant differences in 134 Cs TFs for both plant species and in all studied soil pH. Refs. 4 (author)

  12. Aging of nickel added to soils as predicted by soil pH and time.

    Science.gov (United States)

    Ma, Yibing; Lombi, Enzo; McLaughlin, Mike J; Oliver, Ian W; Nolan, Annette L; Oorts, Koen; Smolders, Erik

    2013-08-01

    Although aging processes are important in risk assessment for metals in soils, the aging of Ni added to soils has not been studied in detail. In this study, after addition of water soluble Ni to soils, the changes over time in isotopic exchangeability, total concentrations and free Ni(2+) activity in soil pore water, were investigated in 16 European soils incubated outdoors for 18 months. The results showed that after Ni addition, concentrations of Ni in soil pore water and isotopic exchangeability of Ni in soils initially decreased rapidly. This phase was followed by further decreases in the parameters measured but these occurred at slower rates. Increasing soil pH increased the rate and extent of aging reactions. Semi-mechanistic models, based on Ni precipitation/nucleation on soil surfaces and micropore diffusion, were developed and calibrated. The initial fast processes, which were attributed to precipitation/nucleation, occurred over a short time (e.g. 1h), afterwards the slow processes were most likely controlled by micropore diffusion processes. The models were validated by comparing predicted and measured Ni aging in three additional, widely differing soils aged outdoors for periods up to 15 months in different conditions. These models could be used to scale ecotoxicological data generated in short-term studies to longer aging times. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Sorption of Cu and Zn in low organic matter-soils as influenced by soil properties and by the degree of soil weathering.

    Science.gov (United States)

    Antoniadis, V; Golia, E E

    2015-11-01

    Copper and Zn sorption and desorption, among other factors, depend on soil pH, but in soils with different degree of weathering the role of other soil properties (e.g., oxides content and the level of their crystallinity) has not been thoroughly examined. We conducted batch sorption and desorption tests using 21 low-organic C soils that belonged to the soil orders of Entisols, newly developed soils, Inceptisols, and Alfisols, the most weathered soils. Zinc sorption was lower than that of Cu, and its desorption faster, confirming that it is a highly mobile metal. Alfisols had the weaker affinity for metals, due to the lower soil pH typical of this soil order, but also due to the low reactivity colloids they contained. Correlation analyses showed that Fe oxides in Alfisols increased metal release from soils, while they decreased metal desorption from Entisols. We conclude that in low organic matter-content soils, where the protective role of organic colloids is not to be expected, high soil pH alone is not sufficient to protect against metal contamination, but the degree of soil weathering is also important, due to the dominant role of other mineral phases (here, Fe oxides). Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Mobility and retention of micronutrients in soil : Part III. Investigation on the influence of various external factors, NPK-fertilizers and soil amending agents on the mobility and retention of manganese

    International Nuclear Information System (INIS)

    Das, S.K.; Santikari, A.K.; Banerji, K.C.

    1980-01-01

    Investigations on the mobility and retention of manganese through Sindri red sandy clay loam of pH 7.4 and Ranchi clay loam of pH 5.6 have been carried out using the radiotracer 54 Mn. The vertical distribution of manganese in these soils showed almost sharp fall upto a depth of 12 to 14 cm and thereafter it tended to attain the saturation. Variations have been marked in the degrees of manganese retention at the top surface layers of the concerned soils. Influence of various NPK fertilizers and soil amending agents, at various application levels, have been studied on the mobility, retention and leaching loss of manganese in the prementioned soils. Marked variations have been recorded and discussed. (author)

  15. [Influences of biochar and nitrogen fertilizer on soil nematode assemblage of upland red soil].

    Science.gov (United States)

    Lu, Yan-yan; Wang, Ming-wei; Chen, Xiao-vun; Liu, Man-qiang; Chen, Xiao-min; Cheng, Yan-hong; Huang, Qian-ru; Hu, Feng

    2016-01-01

    The use of biochar as soil remediation amendment has received more and more concerns, but little attention has been paid to its effect on soil fauna. Based on the field experiment in an upland red soil, we studied the influences of different application rates of biochar (0, 10, 20, 30, 40 t · hm⁻²) and nitrogen fertilizer (60, 90, 120 kg N · hm⁻²) on soil basic properties and nematode assemblages during drought and wet periods. Our results showed that the biochar amendment significantly affect soil moisture and pH regardless of drought or wet period. With the increasing of biochar application, soil pH significantly increased, while soil moisture increased first and then decreased. Soil microbial properties (microbial biomass C, microbial biomass N, microbial biomass C/N, basal respiration) were also significantly affected by the application of biochar and N fertilizer. Low doses of biochar could stimulate the microbial activity, while high doses depressed microbial activity. For example, averaged across different N application rates, biochar amendment at less than 30 t · hm⁻² could increase microbial activity in the drought and wet periods. Besides, the effects of biochar also depended on wet or drought period. When the biochar application rate higher than 30 t · hm⁻², the microbial biomass C was significantly higher in the drought period than the control, but no differences were observed in the wet period. On the contrary, microbial biomass N showed a reverse pattern. Dissolved organic matter and mineral N were affected by biochar and N fertilizer significantly in the drought period, however, in the wet period they were only affected by N fertilizer rather than biochar. There was significant interaction between biochar and N fertilizer on soil nematode abundance and nematode trophic composition independent of sampling period. Combined high doses of both biochar and N fertilization promoted soil nematode abundance. Moreover, the biochar amendment

  16. Changes in soil solution Zn and pH and uptake of Zn by arbuscular mycorrhizal red clover in Zn-contaminated soil.

    Science.gov (United States)

    Li, X; Christie, P

    2001-01-01

    Red clover plants inoculated with Glomus mosseae were grown in a sterile pasture soil containing 50 mg Zn kg(-1) in 'Plexiglas' (acrylic) containers with nylon net partitions (30 microm mesh) designed to separate the soil into a central root zone and two outer zones for hyphal growth with no root penetration. Two porous plastic soil moisture samplers were installed in each pot, one in the root compartment and the other in one of the hyphal compartments. The soil in the outer compartments was amended with one of the four application rates of Zn (as ZnSO4) ranging from 0 to 1000 mg kg(-1). Non-mycorrhizal controls were included, and there were five replicates of each treatment in a randomised block in a glasshouse. Uninoculated plants received supplementary P to avoid yield limitation due to low soil P status. Plants grew in the central compartment for nine weeks. Soil moisture samples were collected 4, 24 and 62 days after sowing to monitor changes in the Zn concentration and pH of the soil solution. At harvest, the mean mycorrhizal infection rate of inoculated plants ranged from 29% to 34% of total root length and was little affected by Zn application. Root and shoot yields were not affected by mycorrhizal infection. Plant Zn concentration and uptake were lower in mycorrhizal plants than non-mycorrhizal controls, and this effect was more pronounced with increasing Zn application rate to the soil. Soil solution Zn concentrations were lower and pH values were higher in mycorrhizal treatments than non-mycorrhizal controls and the mycorrhiza effect was more pronounced at higher Zn application rates. The protective effect of mycorrhiza against plant Zn uptake may have been associated with changes in Zn solubility mediated by changes in the soil solution pH, or by immobilisation of Zn in the extraradical mycelium.

  17. Can we predict uranium bioavailability based on soil parameters? Part 1: effect of soil parameters on soil solution uranium concentration.

    Science.gov (United States)

    Vandenhove, H; Van Hees, M; Wouters, K; Wannijn, J

    2007-01-01

    Present study aims to quantify the influence of soil parameters on soil solution uranium concentration for (238)U spiked soils. Eighteen soils collected under pasture were selected such that they covered a wide range for those parameters hypothesised as being potentially important in determining U sorption. Maximum soil solution uranium concentrations were observed at alkaline pH, high inorganic carbon content and low cation exchange capacity, organic matter content, clay content, amorphous Fe and phosphate levels. Except for the significant correlation between the solid-liquid distribution coefficients (K(d), L kg(-1)) and the organic matter content (R(2)=0.70) and amorphous Fe content (R(2)=0.63), there was no single soil parameter significantly explaining the soil solution uranium concentration (which varied 100-fold). Above pH=6, log(K(d)) was linearly related with pH [log(K(d))=-1.18 pH+10.8, R(2)=0.65]. Multiple linear regression analysis did result in improved predictions of the soil solution uranium concentration but the model was complex.

  18. Characterization of Growing Soil Bacterial Communities across a pH gradient Using H218O DNA-Stable Isotope Probing

    Science.gov (United States)

    Welty-Bernard, A. T.; Schwartz, E.

    2014-12-01

    Recent studies have established consistent relationships between pH and bacterial diversity and community structure in soils from site-specific to landscape scales. However, these studies rely on DNA or PLFA extraction techniques from bulk soils that encompass metabolically active and inactive, or dormant, communities, and loose DNA. Dormant cells may comprise up to 80% of total live cells. If dormant cells dominate a particular environment, it is possible that previous interpretations of the soil variables assumed to drive communities could be profoundly affected. We used H218O stable isotope probing and bar-coded illumina sequencing of 16S rRNA genes to monitor the response of actively growing communities to changes in soil pH in a soil microcosm over 14 days. This substrate-independent approach has several advantages over 13C or 15N-labelled molecules in that all growing bacteria should be able to make use of water, allowing characterization of whole communities. We hypothesized that Acidobacteria would increasingly dominate the growing community and that Actinobacteria and Bacteroidetes would decline, given previously established responses by these taxa to soil pH. Instead, we observed the reverse. Actinobacteria abundance increased three-fold from 26 to 76% of the overall community as soil pH fell from pH 5.6 to pH 4.6. Shifts in community structure and decreases in diversity with declining soil pH were essentially driven by two families, Streptomyceaca and Microbacteracea, which collectively increased from 2 to 40% of the entire community. In contrast, Acidobacteria as a whole declined although numbers of subdivision 1 remained stable across all soil pH levels. We suggest that the brief incubation period in this SIP study selected for growth of acid-tolerant Actinobacteria over Acidobacteria. Taxa within Actinomycetales have been readily cultured over short time frames, suggesting rapid growth patterns. Conversely, taxa within Acidobacteria have been

  19. Phosphorus sorption-desorption and effects of temperature, pH and salinity on phosphorus sorption in marsh soils from coastal wetlands with different flooding conditions.

    Science.gov (United States)

    Bai, Junhong; Ye, Xiaofei; Jia, Jia; Zhang, Guangliang; Zhao, Qingqing; Cui, Baoshan; Liu, Xinhui

    2017-12-01

    Wetland soils act as a sink or source of phosphorus (P) to the overlaying water due to phosphorus sorption-desorption processes. Litter information is available on sorption and desorption behaviors of phosphorus in coastal wetlands with different flooding conditions. Laboratory experiments were conducted to investigate phosphorus sorption-desorption processes, fractions of adsorbed phosphorus, and the effects of salinity, pH and temperature on phosphorus sorption on soils in tidal-flooding wetlands (TW), freshwater-flooding wetlands (FW) and seasonal-flooding wetlands (SW) in the Yellow River Delta. Our results showed that the freshly adsorbed phosphorus dominantly exists in Occluded-P and Fe/AlP and their percentages increased with increasing phosphorus adsorbed. Phosphorus sorption isotherms could be better described by the modified Langmuir model than by the modified Freundlich model. A binomial equation could be properly used to describe the effects of salinity, pH, and temperature on phosphorus sorption. Phosphorus sorption generally increased with increasing salinity, pH, and temperature at lower ranges, while decreased in excess of some threshold values. The maximum phosphorus sorption capacity (Q max ) was larger for FW soils (256 mg/kg) compared with TW (218 mg/kg) and SW soils (235 mg/kg) (p < 0.05). The percentage of phosphorus desorption (P des ) in the FW soils (7.5-63.5%) was much lower than those in TW (27.7-124.9%) and SW soils (19.2-108.5%). The initial soil organic matter, pH and the exchangeable Al, Fe and Cd contents were important factors influencing P sorption and desorption. The findings of this study indicate that freshwater restoration can contribute to controlling the eutrophication status of water bodies through increasing P sorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Influence of pH on the transport of nanoscale zinc oxide in saturated porous media

    Energy Technology Data Exchange (ETDEWEB)

    Kanel, Sushil R. [Pegasus Technical Services, Inc. (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [National Risk Management Research Laboratory, U.S. Environmental Protection Agency (United States)

    2011-09-15

    Widespread use of nanoscale zinc oxide (nZnO) in various fields causes subsurface environment contamination. Even though the transport of dissolved zinc ions in subsurface environments such as soils and sediments has been widely studied, the transport mechanism of nZnO in such environments is poorly understood. In addition, nZnO is often combined with stabilizers or dispersing agents to prevent its aggregation in products. The purpose of this study is to determine the influence of pH on the transport properties of pristine nZnO and carboxymethyl cellulose (CMC) stabilized nZnO (CMC-nZnO) suspensions in silica sand packed column under saturated flow conditions. Transport data were collected at different pHs (pHs: 3, 7, 9, and 11) under 1 mL/min flow rate conditions in a 1.1 cm diameter column. It is found that the transport trends of pristine nZnO and CMC-nZnO were different. For pristine nZnO, mobility of total Zn reached a minimum around its point of zero charge (pH 8.9). Whereas in the case of CMC-nZnO, the mobility of total Zn decreased as the pH of the solution pH increased from 3 to 11. ZnO and Zn ion mixture were separated using diafiltration membrane. It showed that most of the nZnO and CMC-nZnO exists as Zn ion at pH 3 before and after eluting from the sand packed column whereas at pH 11, they exist as particles. This study shows the strong influence of pH and stabilizing agents on nZnO transport. These factors should be considered during subsurface transport of nZnO.

  1. Influence of pH on the transport of nanoscale zinc oxide in saturated porous media

    International Nuclear Information System (INIS)

    Kanel, Sushil R.; Al-Abed, Souhail R.

    2011-01-01

    Widespread use of nanoscale zinc oxide (nZnO) in various fields causes subsurface environment contamination. Even though the transport of dissolved zinc ions in subsurface environments such as soils and sediments has been widely studied, the transport mechanism of nZnO in such environments is poorly understood. In addition, nZnO is often combined with stabilizers or dispersing agents to prevent its aggregation in products. The purpose of this study is to determine the influence of pH on the transport properties of pristine nZnO and carboxymethyl cellulose (CMC) stabilized nZnO (CMC–nZnO) suspensions in silica sand packed column under saturated flow conditions. Transport data were collected at different pHs (pHs: 3, 7, 9, and 11) under 1 mL/min flow rate conditions in a 1.1 cm diameter column. It is found that the transport trends of pristine nZnO and CMC–nZnO were different. For pristine nZnO, mobility of total Zn reached a minimum around its point of zero charge (pH 8.9). Whereas in the case of CMC–nZnO, the mobility of total Zn decreased as the pH of the solution pH increased from 3 to 11. ZnO and Zn ion mixture were separated using diafiltration membrane. It showed that most of the nZnO and CMC–nZnO exists as Zn ion at pH 3 before and after eluting from the sand packed column whereas at pH 11, they exist as particles. This study shows the strong influence of pH and stabilizing agents on nZnO transport. These factors should be considered during subsurface transport of nZnO.

  2. Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

    Science.gov (United States)

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.; Küsel, Kirsten

    2016-01-01

    The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.

  3. Influence of pH on the growth, laccase activity and RBBR decolorization by tropical basidiomycetes

    Directory of Open Access Journals (Sweden)

    Sérgio Luiz Moreira Neto

    2009-10-01

    Full Text Available The basidiomycete fungi Lentinus crinitus and Psilocybe castanella are being evaluated in a bioremediation process of soils contaminated with organochlorine industrial residues in the Baixada Santista, São Paulo. The aim of the present study was to determine the influence of pH on the fungal growth, in vitro decolorization of anthraquinonic dye Remazol Brilliant Blue R (RBBR and laccase activity. The pH of the culture medium influenced the growth of L. crinitus and P. castanella, which presented less growth at pH 5.9 and pH 2.7, respectively. The fungi were able to modify the pH of the culture medium, adjusting it to the optimum pH for growth which was close to 4.5. Decolorization of the RBBR was maximal at a pH of 2.5 to 3.5. Higher laccase activity was observed at pH 3.5 and pH 4.5 for L. crinitus and P. castanella, respectively. pH was found to be an important parameter for both the growth of these fungi and the enzymatic system involved in RBBR decolorization.Os fungos basidiomicetos Lentinus crinitus e Psilocybe castanella estão sendo avaliados em processo de biorremediação de solos contaminados com resíduos industriais organoclorados, na Baixada Santista, SP. O presente estudo avaliou a influência do pH no crescimento, na descoloração in vitro do corante Azul Brilhante de Remazol R (RBBR e na atividade de lacase durante cultivo destes fungos, de forma a subsidiar a otimização do processo. O pH do meio influenciou o crescimento de L. crinitus e de P. castanella, com menor biomassa em pH 5,9 e pH 2,7, respectivamente. Os fungos foram capazes de modificar o pH inicial do meio de cultura, de modo a ajustá-lo ao valor ótimo de crescimento, próximo a 4,5. Descoloração in vitro do RBBR foi máxima em pH 2,5 e 3,5. Maiores atividades de lacase foram obtidas em pH 3,5 e em pH 4,5 para L. crinitus e P. castanella, respectivamente. Evidenciou-se que o pH é um parâmetro importante para o crescimento destes fungos, atividade de lacase

  4. The role of rhizosphere pH in regulating the rhizosphere priming effect and implications for the availability of soil-derived nitrogen to plants.

    Science.gov (United States)

    Wang, Xiaojuan; Tang, Caixian

    2018-01-25

    A comprehensive understanding of the rhizosphere priming effect (RPE) on the decomposition of soil organic carbon (SOC) requires an integration of many factors. It is unclear how N form-induced change in soil pH affects the RPE and SOC sequestration. This study compared the change in the RPE under supply of NO3-N and NH4-N. The effect of the RPE on the mineralization of soil N and hence its availability to plant and microbes was also examined using a 15N-labelled N source. The supply of NH4-N decreased rhizosphere pH by 0.16-0.38 units, and resulted in a decreased or negative RPE. In contrast, NO3-N nutrition increased rhizosphere pH by 0.19-0.78 units, and led to a persistently positive RPE. The amounts of rhizosphere-primed C were positively correlated with rhizosphere pH. Rhizosphere pH affected the RPE mainly through influencing microbial biomass, activity and utilization of root exudates, and the availability of SOC to microbes. Furthermore, the amount of rhizosphere primed C correlated negatively with microbial biomass atom% 15N (R2 0.77-0.98, n = 12), suggesting that microbes in the rhizosphere acted as the immediate sink for N released from enhanced SOC decomposition via the RPE. N form was an important factor affecting the magnitude and direction of the RPE via its effect on rhizosphere pH. Rhizosphere pH needs to be considered in SOC and RPE modelling. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Horizontal distribution of phosphorus in soils of irrigation ditches ...

    African Journals Online (AJOL)

    Horizontal distribution of phosphorus in soils of irrigation ditches. ... correlations were found between soil P and stream water P on one hand, and between soil pH and stream water pH on the other, indicating that the irrigation water may indeed, have had little or no influence on the properties of the ditches' soils.

  6. Soil pH Errors Propagation from Measurements to Spatial Predictions - Cost Benefit Analysis and Risk Assessment Implications for Practitioners and Modelers

    Science.gov (United States)

    Owens, P. R.; Libohova, Z.; Seybold, C. A.; Wills, S. A.; Peaslee, S.; Beaudette, D.; Lindbo, D. L.

    2017-12-01

    The measurement errors and spatial prediction uncertainties of soil properties in the modeling community are usually assessed against measured values when available. However, of equal importance is the assessment of errors and uncertainty impacts on cost benefit analysis and risk assessments. Soil pH was selected as one of the most commonly measured soil properties used for liming recommendations. The objective of this study was to assess the error size from different sources and their implications with respect to management decisions. Error sources include measurement methods, laboratory sources, pedotransfer functions, database transections, spatial aggregations, etc. Several databases of measured and predicted soil pH were used for this study including the United States National Cooperative Soil Survey Characterization Database (NCSS-SCDB), the US Soil Survey Geographic (SSURGO) Database. The distribution of errors among different sources from measurement methods to spatial aggregation showed a wide range of values. The greatest RMSE of 0.79 pH units was from spatial aggregation (SSURGO vs Kriging), while the measurement methods had the lowest RMSE of 0.06 pH units. Assuming the order of data acquisition based on the transaction distance i.e. from measurement method to spatial aggregation the RMSE increased from 0.06 to 0.8 pH units suggesting an "error propagation". This has major implications for practitioners and modeling community. Most soil liming rate recommendations are based on 0.1 pH unit increments, while the desired soil pH level increments are based on 0.4 to 0.5 pH units. Thus, even when the measured and desired target soil pH are the same most guidelines recommend 1 ton ha-1 lime, which translates in 111 ha-1 that the farmer has to factor in the cost-benefit analysis. However, this analysis need to be based on uncertainty predictions (0.5-1.0 pH units) rather than measurement errors (0.1 pH units) which would translate in 555-1,111 investment that

  7. Utilization of maize cob biochar and rice husk charcoal as soil amendments for improving acid soil fertility and productivity

    Directory of Open Access Journals (Sweden)

    Nurhidayati

    2014-10-01

    Full Text Available The decline in soil fertility in agricultural land is a major problem that causes a decrease in the production of food crops. One of the causes of the decline in soil fertility is declining soil pH that caused the decline in the availability of nutrients in the soil. This study aimed to assess the influence of alternative liming materials derived from maize cob biochar and rice husk charcoal compared to conventional lime to improve soil pH, soil nutrient availability and maize production. The experiment used a factorial complete randomized design which consisting of two factors. The first factor is the type of soil amendment which consists of three levels (calcite lime, rice husk charcoal and cob maize biochar. The second factor is the application rates of the soil amendment consisted of three levels (3, 6 and 9 t/ha and one control treatment (without soil amendment. The results of this study showed that the application of various soil amendment increased soil pH, which the pH increase of the lime application was relatively more stable over time compared to biochar and husk charcoal. The average of the soil pH increased for each soil amendment by 23% (lime, 20% (rice husk charcoal and 23% (biochar as compared with control. The increase in soil pH can increase the availability of soil N, P and K. The greatest influence of soil pH on nutrient availability was shown by the relationship between soil pH and K nutrient availability with R2 = 0.712, while for the N by R2 = 0.462 and for the P by R2 = 0.245. The relationship between the availability of N and maize yield showed a linear equation. While the relationship between the availability of P and K with the maize yield showed a quadratic equation. The highest maize yield was found in the application of biochar and rice husk charcoal with a dose of 6-9 t/ha. The results of this study suggested that biochar and husk charcoal could be used as an alternative liming material in improving acid soil

  8. Dissolved organic carbon (DOC) concentrations in UK soils and the influence of soil, vegetation type and seasonality.

    Science.gov (United States)

    van den Berg, Leon J L; Shotbolt, Laura; Ashmore, Mike R

    2012-06-15

    Given the lack of studies which measured dissolved organic carbon (DOC) over long periods, especially in non-forest habitat, the aim of this study was to expand the existing datasets with data of mainly non-forest sites that were representative of the major soil and habitat types in the UK. A further aim was to predict DOC concentrations from a number of biotic and abiotic explanatory variables such as rainfall, temperature, vegetation type and soil type in a multivariate way. Pore water was sampled using Rhizon or Prenart samplers at two to three week intervals for 1 year. DOC, pH, organic carbon, carbon/nitrogen (C:N) ratios of soils and slope were measured and data on vegetation, soil type, temperature and precipitation were obtained. The majority of the variation in DOC concentrations between the UK sites could be explained by simple empirical models that included annual precipitation, and soil C:N ratio with precipitation being negatively related to DOC concentrations and C:N ratio being positively related to DOC concentrations. Our study adds significantly to the data reporting DOC concentrations in soils, especially in grasslands, heathlands and moorlands. Broad climatic and site factors have been identified as key factors influencing DOC concentrations. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Predicting molybdenum toxicity to higher plants: Influence of soil properties

    International Nuclear Information System (INIS)

    McGrath, S.P.; Mico, C.; Curdy, R.; Zhao, F.J.

    2010-01-01

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED 50 ) of Mo in different soils, explaining > 65% of the variance in ED 50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. - Amorphous iron oxides or organic carbon were found to be the best predictors of the toxicity threshold values of Mo to higher plants on different soils.

  10. Observation of pH Value in Electrokinetic Remediation using various electrolyte (MgSO4, KH2PO4 and Na(NO3)) for Barren Acidic Soil at Ayer Hitam, Johor, Malaysia

    Science.gov (United States)

    Norashira, J.; Zaidi, E.; Aziman, M.; Saiful Azhar, A. T.

    2016-07-01

    Barren acidic soil collected at Ayer Hitam, Johor Malaysia was recorded at pH value of 2.36 with relative humidity of 86%. This pH value is not suitable for the growth of any plants especially for the soil stabilization purposes. Gradation weathering within the range of 4 to 6 indicates an incomplete/partial weathering process. The soil grade in this range is known as a black shale mudstone. Beside, this also influences to a factor of the high surface water runoff at this particular soil species. As the acidic pH become a major problem for soil fertilizing hence an appropriate technique was implemented known as using ‘Electrokinetic Remediation’, EKR. This technique has a great potential in changing the soil pH value from acidic to less acidic and also kept maintain the pH at the saturated rate of electrochemical process. This research study presents the monitoring data of pH value due to the effect of various electrolyte consist of 0.5M of MgSO4, KH2PO4, and Na(NO3). Here, the distilled water (DW) was used as reference solution. The electric field was provided by dipping two pieces of identical rectangular aluminum foil as anode and cathode. The EKR was conducted under a constant voltage gradient of 50 V/m across the sample bulk at 0.14 m length measured between both electrodes. The data collection was conducted during the total period of 7 days surveillance. The variation of pH values at the remediation area between anode and cathode for various type of electrolyte indicates that there are a significant saturated value as it reaches 7 days of treatment. During the analysis, it is found that the highest pH value at the remediation area after 7 days treatment using Na(NO3), KH2PO4 and MgSO4 was 3.93, 3.33 and 3.39 respectively. Hence from the last stage of pH value observation, it can be conclude that the best electrolyte for barren soil treatment is Na(NO3) whereby it contribute to highest pH value and turn the soil to be less acidic.

  11. Electrokinetic remediation on cadmium (CD) spiked soils

    Energy Technology Data Exchange (ETDEWEB)

    Sah Jy-Gau [Dept. of Environmental Science and Engineering, National Pingtung Univ. of Science and Technology, Pingtung (Taiwan); Yu Lin, L. [Dept. of Civil and Environmental Engineering, Christian Bros. Univ. Memphis, TN (United States)

    2001-07-01

    The objective of this study is to examine several variables, such as soil pH, adsorption capacity, fraction of Cd in soils, and organic content for Cd removal in contaminated soil using electrokinetic technology. Two different experimental modules were constructed in the laboratory. In the small module, most Cd was able to move and concentrate at or near the cathode zone in acidic soil and neutral soil under 8 volts after 30 days of electrification. However, the Cd removal efficiency did not improve even when the alkaline soil was soaked in stronger acid solutions. The results indicated that the removal efficiencies were influenced not only by the pH of conducting solutions, but also the pH of the soils. The removal efficiencies of Cd were reduced when a portion of organic peat moss was added into the soils. The increases of organic content in the soils inhibit the removal efficiency in electrokinetic technology. In the larger scale module, the removal efficiency of Cd was lower than that in the smaller module during a short period of time. Nevertheless, the efficiency was improved in the larger module while 16 volts electric pressure and 180 days were applied to the module. The results also showed that the sequence of removal efficiency of the three soils in larger module followed the changes of soil pH. From this study, it concluded that electrokinetic technology has a highly potential to removal Cd in contaminated soils. Within these influence variable studies, the soil pH and organic content are the most important factor in electrokinetic technology. Keywords: Electrokinetic Technique, Heavy Metal, Cd, Soil Remediation. (orig.)

  12. Topsoil and subsoil properties influence phosphorus leaching from four agricultural soils.

    Science.gov (United States)

    Andersson, Helena; Bergström, Lars; Djodjic, Faruk; Ulén, Barbro; Kirchmann, Holger

    2013-01-01

    Eutrophication, a major problem in many fresh and brackish waters, is largely caused by nonpoint-source pollution by P from agricultural soils. This lysimeter study examined the influence of P content, physical properties, and sorption characteristics in topsoil and subsoil on P leaching measured during 21 mo in 1-m-long, undisturbed soil columns of two clay and two sandy soils. Total P losses during the period varied between 0.65 and 7.40 kg ha. Dissolved reactive P was the dominant form in leachate from the sandy soils and one clay soil, varying from 48 to 76%. Particulate P dominated in leachate from the other clay soil, where low pH (5.2) in the subsoil decreased aggregate stability and thereby probably increased the dispersion of clay particles. Phosphorus leaching was small from soils with high P sorption index (PSI) and low P saturation (35% of PSI) in the profile. High sorption capacity in the subsoil was more important for P leaching in sandy soils than in clay soils with macropore flow, where the effect of high sorption capacity was reduced due to less interaction between percolating water and the soil matrix. The results suggest that P leaching is greatly affected by subsoil properties and that topsoil studies, which dominate current research, are insufficient for assessing P leaching in many soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  13. Iron biofortification of wheat grains through integrated use of organic and chemical fertilizers in pH affected calcareous soil.

    Science.gov (United States)

    Ramzani, Pia Muhammad Adnan; Khalid, Muhammad; Naveed, Muhammad; Ahmad, Rashid; Shahid, Muhammad

    2016-07-01

    Incidence of iron (Fe) deficiency in human populations is an emerging global challenge. This study was conducted to evaluate the potential of iron sulphate combined with biochar and poultry manure for Fe biofortification of wheat grains in pH affected calcareous soil. In first two incubation studies, rates of sulfur (S) and Fe combined with various organic amendments for lowering pH and Fe availability in calcareous soil were optimized. In pot experiment, best rate of Fe along with biochar (BC) and poultry manure (PM) was evaluated for Fe biofortification of wheat in normal and S treated low pH calcareous soil. Fe applied with BC provided fair increase in root-shoot biomass and photosynthesis up to 79, 53 and 67%, respectively in S treated low pH soil than control. Grain Fe and ferritin concentration was increased up to 1.4 and 1.2 fold, respectively while phytate and polyphenol was decreased 35 and 44%, respectively than control in treatment where Fe was applied with BC and S. In conclusion, combined use of Fe and BC could be an effective approach to improve growth and grain Fe biofortification of wheat in pH affected calcareous soil. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  14. Predicting molybdenum toxicity to higher plants: Influence of soil properties

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, S.P., E-mail: steve.mcgrath@bbsrc.ac.u [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Mico, C. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Curdy, R. [Laboratory for Environmental Biotechnology (LBE), Swiss Federal Institute of Technology Lausanne (EPFL) Station 6 CH, 1015 Lausanne (Switzerland); Zhao, F.J. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom)

    2010-10-15

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED{sub 50}) of Mo in different soils, explaining > 65% of the variance in ED{sub 50} for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. - Amorphous iron oxides or organic carbon were found to be the best predictors of the toxicity threshold values of Mo to higher plants on different soils.

  15. The interaction of soil phototrophs and fungi with pH and their impact on soil CO2, CO18O and OCS exchange.

    Science.gov (United States)

    Sauze, Joana; Ogée, Jérôme; Maron, Pierre-Alain; Crouzet, Olivier; Nowak, Virginie; Wohl, Steven; Kaisermann, Aurore; Jones, Sam P; Wingate, Lisa

    2017-12-01

    The stable oxygen isotope composition of atmospheric CO 2 and the mixing ratio of carbonyl sulphide (OCS) are potential tracers of biospheric CO 2 fluxes at large scales. However, the use of these tracers hinges on our ability to understand and better predict the activity of the enzyme carbonic anhydrase (CA) in different soil microbial groups, including phototrophs. Because different classes of the CA family (α, β and γ) may have different affinities to CO 2 and OCS and their expression should also vary between different microbial groups, differences in the community structure could impact the 'community-integrated' CA activity differently for CO 2 and OCS. Four soils of different pH were incubated in the dark or with a diurnal cycle for forty days to vary the abundance of native phototrophs. Fluxes of CO 2 , CO 18 O and OCS were measured to estimate CA activity alongside the abundance of bacteria, fungi and phototrophs. The abundance of soil phototrophs increased most at higher soil pH. In the light, the strength of the soil CO 2 sink and the CA-driven CO 2 -H 2 O isotopic exchange rates correlated with phototrophs abundance. OCS uptake rates were attributed to fungi whose abundance was positively enhanced in alkaline soils but only in the presence of increased phototrophs. Our findings demonstrate that soil-atmosphere CO 2 , OCS and CO 18 O fluxes are strongly regulated by the microbial community structure in response to changes in soil pH and light availability and supports the idea that different members of the microbial community express different classes of CA, with different affinities to CO 2 and OCS.

  16. High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization.

    Directory of Open Access Journals (Sweden)

    Md Sainur Samad

    Full Text Available Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N2O and N2. It is known that N2O reduction to N2 is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N2O emissions in response to carbon (C mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand using a fully automated-high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N2O production index (IN2O and N2O/(N2O+N2 product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N2O+N2 μmol N/h/vial were significantly associated with C mineralization (CO2 μmol/h/vial measured both under oxic (r2 = 0.62, p = 0.0015 and anoxic (r2 = 0.89, p<0.0001 conditions.

  17. Reduction in soil N2O emissions by pH manipulation and enhanced nosZ gene transcription under different water regimes.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Yupeng; Khalid, Muhammad Salman; Peng, Qi-An; Xu, Xiangyu; Wu, Lei; Younas, Aneela; Bashir, Saqib; Mo, Yongliang; Lin, Shan; Zafar-Ul-Hye, Muhammad; Abid, Muhammad; Hu, Ronggui

    2018-04-01

    Several studies have been carried out to examine nitrous oxide (N 2 O) emissions from agricultural soils in the past. However, the emissions of N 2 O particularly during amelioration of acidic soils have been rarely studied. We carried out the present study using a rice-rapeseed rotation soil (pH 5.44) that was amended with dolomite (0, 1 and 2 g kg -1 soil) under 60% water filled pore space (WFPS) and flooding. N 2 O emissions and several soil properties (pH, NH 4 + N, NO 3 - -N, and nosZ gene transcripts) were measured throughout the study. The increase in soil pH with dolomite application triggered soil N transformation and transcripts of nosZ gene controlling N 2 O emissions under both water regimes (60% WFPS and flooding). The 60% WFPS produced higher soil N 2 O emissions than that of flooding, and dolomite largely reduced N 2 O emissions at higher pH under both water regimes through enhanced transcription of nosZ gene. The results suggest that ameliorating soil acidity with dolomite can substantially mitigate N 2 O emissions through promoting nosZ gene transcription. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Influence of pH on retention of camel chymosin in curd

    DEFF Research Database (Denmark)

    Børsting, Mette Winther; Qvist, Karsten B.; Ardö, Ylva Margareta

    2014-01-01

    Retained coagulant in cheese initiates casein breakdown and influences cheese structure and flavour formation. This study investigated the influence of milk pH on retention of camel chymosin in curd and compared it with bovine chymosin. Milk at five different pH levels was coagulated with same...... coagulation activity. The retention of camel chymosin in curd was rather constant at ∼20% between pH 6.65 and 6.00, while it increased almost linear from 2 to 21% for bovine chymosin. The lower pH dependence for retention of camel chymosin than of bovine chymosin may be explained by a lower negative charge...

  19. Novel Technique to improve the pH of Acidic Barren Soil using Electrokinetic-bioremediation with the application of Vetiver Grass

    Science.gov (United States)

    Azhar, A. T. S.; Nabila, A. T. A.; Nurshuhaila, M. S.; Zaidi, E.; Azim, M. A. M.; Zahin, A. M. F.

    2016-11-01

    Residual acidic slopes which are not covered by vegetation greatly increases the risk of soil erosion. In addition, low soil pH can bring numerous problems such as Al and Fe toxicity, land degradation issues and some problems related to vegetation. In this research, a series of electrokinetic bioremediation (EK-Bio) treatments using Bacillus sphaericus, Bacillus subtilis and Pseudomonas putida with a combination of Vetiver grass were performed in the laboratory. Investigations were conducted for 14 days and included the observation of changes in the soil pH and the mobilization of microorganism cells through an electrical gradient of 50 V/m under low pH. Based on the results obtained, this study has successfully proven that the pH of soil increases after going through electrokinetic bioremediation (EK-Bio). The treatment using Bacillus sphaericus increases the pH from 2.95 up to 4.80, followed by Bacillus subtilis with a value of 4.66. Based on the overall performance, Bacillus sphaericus show the highest number of bacterial cells in acidic soil with a value of 6.6 × 102 cfu/g, followed by Bacillus subtilis with a value of 5.7 × 102 cfu/g. In conclusion, Bacillus sphaericus and Bacillus subtilis show high survivability and is suitable to be used in the remediation of acidic soil.

  20. Sorption of samarium in soils: influence of soil properties and Sm concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Salaberria, Aitor; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    Due to the fact that barriers of Deep Geological Repositories (DGR) may lose efficiency before the radioisotopes present in the High Level Radioactive Waste (HLRW) completely decay, it is possible that, in the long-term, radioactive leachates may escape from the DGR and reach the soil and water compartments in the biosphere. Therefore, it is required to examine the interaction and mobility of radionuclides present in the HLRW, or their chemical analogues, to predict the impact of their eventual incorporation in the biosphere and to assess the derived risk. Although relevant data have been recently obtained for a few radionuclides in soils, there are still some important gaps for some radionuclides, such us for samarium (Sm). Sm is a lanthanide that, besides being considered as a natural analogue of actinides, may also be present in HLRW in the form of the radioactive isotope {sup 151}Sm. The main objective of this work was to obtain sorption data (K{sub d}) of {sup 151}Sm gathered from a set of soil samples physicochemical fully-characterized (pH, texture, cationic exchange capacity, soil solution cationic composition, organic matter, carbonate and metallic oxides content, etc.). Additionally, as an alternative for testing sorption capacity of radionuclides in soils is the use of the corresponding stable isotope or a chemical analogue, the influence of Sm concentration was also checked. To evaluate {sup 151}Sm sorption, batch assays were carried out for each soil sample, which consisted in a pre-equilibration step of 2 g of each soil with 50 ml of double deionised water, and a subsequent equilibration step with the same solution, but labelled with {sup 151}Sm. The activity of {sup 151}Sm in initial and final solutions was measured by liquid scintillation and K{sub d} ({sup 151}Sm) data were calculated. The reversibly sorbed fraction was estimated by the application of a single extraction test, with double deionised water, to soil residues coming from the previous

  1. Analysis Of Soil NPK Ph And Electrical Conductivity At Adham Area- Renk Upper Nile State

    Directory of Open Access Journals (Sweden)

    Abubaker Haroun Mohamed Adam

    2015-08-01

    Full Text Available ABSTRACT The objectives of this study were to investigate soil type potentiality and reaction in relation to the scattered remaining vegetation species and to quantify soil suitability for growing field crops. Adham area witnessed serious land degradation due to the rapid expansion of Rain-fed Mechanized Farming and overgrazing. Consequently the low crop yield enforced the local communities to shift to the alternative sources of income generating activities particularly those related to forest products like charcoal making firewood production logging and tree lobbing. By using Randomized Complete Block Design RCBD with emphasizes on Macro nutrients particularly the Nitrogen Phosphorous and potassium NPK in addition to soil pH and Electrical Conductivity EC. random soil samples each with three levels of depths 0 - 15 15 - 30 30 - 45 cm. were collected. All collected data were analyzed in the laboratory. The result of revealed several types of soils including the cracking and non -cracking clay sandy and red soils. The result of statistical analysis depicted variability in NPK pH and EC between the different locations and soil depths. Furthermore the result showed an association between some studied soil attributes and the spatial distribution of the vegetation species. Rational use through participatory approach is recommended for natural resources management conservation and sustainability. Moreover further study using space technology also recommended.

  2. Wood ash application increases pH but does not harm the soil mesofauna

    DEFF Research Database (Denmark)

    Qin, Jiayi; Hovmand, Mads Frederik; Ekelund, Flemming

    2017-01-01

    Application of bioash from biofuel combustion to soil supports nutrient recycling, but may have unwanted and detrimental ecotoxicological side-effects, as the ash is a complex mixture of compounds that could affect soil invertebrates directly or through changes in their food or habitat conditions...... is the likely cause of effects while high pH and heavy metals is of minor importance.......Application of bioash from biofuel combustion to soil supports nutrient recycling, but may have unwanted and detrimental ecotoxicological side-effects, as the ash is a complex mixture of compounds that could affect soil invertebrates directly or through changes in their food or habitat conditions....... To examine this, we performed laboratory toxicity studies of the effects of wood-ash added to an agricultural soil and the organic horizon of a coniferous plantation soil with the detrivore soil collembolans Folsomia candida and Onychiurus yodai, the gamasid predaceous mite Hypoaspis aculeifer...

  3. Influence of pH on extracellular matrix preservation during lung decellularization.

    Science.gov (United States)

    Tsuchiya, Tomoshi; Balestrini, Jenna L; Mendez, Julio; Calle, Elizabeth A; Zhao, Liping; Niklason, Laura E

    2014-12-01

    The creation of decellularized organs for use in regenerative medicine requires the preservation of the organ extracellular matrix (ECM) as a means to provide critical cues for differentiation and migration of cells that are seeded onto the organ scaffold. The purpose of this study was to assess the influence of varying pH levels on the preservation of key ECM components during the decellularization of rat lungs. Herein, we show that the pH of the 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS)-based decellularization solution influences ECM retention, cell removal, and also the potential for host response upon implantation of acellular lung tissue. The preservation of ECM components, including elastin, fibronectin, and laminin, were better retained in the lower pH conditions that were tested (pH ranges tested: 8, 10, 12); glycosaminoglycans were preserved to a higher extent in the lower pH groups as well. The DNA content following decellularization of the rat lung was inversely correlated with the pH of the decellularization solution. Despite detectible levels of cyotoskeletal proteins and significant residual DNA, tissues decellularized at pH 8 demonstrated the greatest tissue architecture maintenance and the least induction of host response of all acellular conditions. These results highlight the effect of pH on the results obtained by organ decellularization and suggest that altering the pH of the solutions used for decellularization may influence the ability of cells to properly differentiate and home to appropriate locations within the scaffold, based on the preservation of key ECM components and implantation results.

  4. A model to explain high values of pH in an alkali sodic soil Modelo para explicar valores elevados de pH em um solo sódico alcalino

    Directory of Open Access Journals (Sweden)

    José Guerrero-Alves

    2002-12-01

    Full Text Available For alkali sodic soils (pH>8.5, the "hydrolysis of exchangeable sodium" has been used as a possible explanation for the alkalinity production and rise in pH of these soils. As an alternative to this hypothesis, a model was developed to simulate and to explain that the alkalinity production and rise in pH is possible in a soil that accumulates alkaline sodium salts and CaCO3. Several simulations were performed by using different combinations of CO2 partial pressures (P, presence or absence of MgCO3, along with experimental values of exchangeable sodium percentage (ESP and ion concentrations in saturation extracts from an alkali sodic soil (named Pantanal. A hypothetical system with similar conditions to the Pantanal soil but with a Gapon selectivity coefficient (KG of 0.01475 (mmol L-1-1/2 was also considered. Good agreement was obtained between experimental and predicted values for pH and ion concentrations in the soil solution when the model (without MgCO3 was applied to the Pantanal soil. However, KG values calculated for the Pantanal soil were generally higher than 0.01475 (mmol L-1-1/2. Moreover, high pH values and elevated ionic strength were obtained when a KG of 0.01475 (mmol L-1-1/2 was used at high ESP (similar to those found in the Pantanal soil. KG values obtained for the Pantanal soil and the results obtained in the simulation of the hypothetical system are suggesting that a value higher than 0.01475 (mmol L-1-1/2 should be used to adequately simulate the behavior of the Pantanal soil at low ionic strength and high ESP values.Em solos alcalino sódicos (pH>8,5, a "hidrólise de sódio trocável" tem sido usada como uma possível explicação para a produção de álcali e elevação do pH nestes solos. Como uma alternativa a essa hipótese, um modelo foi desenvolvido para simular e explicar que a produção de álcali e elevação do pH é possível num solo que acumula sais alcalinos de sódio e CaCO3. Várias simulações foram

  5. Influence of soil properties and soil leaching on the toxicity of ionic silver to plants.

    Science.gov (United States)

    Langdon, Kate A; McLaughlin, Mike J; Kirby, Jason K; Merrington, Graham

    2015-11-01

    Silver (Ag) has been shown to exhibit antimicrobial properties; as a result, it is being used increasingly in a wide range of consumer products. With these uses, the likelihood that Ag may enter the environment has increased, predominately via land application of biosolids or irrigation with treated wastewater effluent. The aim of the present study was to investigate the toxicity of Ag to 2 plant species: barley (Hordeum vulgare L. CV Triumph) and tomato (Lycopersicum esculentum) in a range of soils under both leached and unleached conditions. The concentrations that resulted in a 50% reduction of plant growth (EC50) were found to vary up to 20-fold across the soils, indicating a large influence of soil type on Ag toxicity. Overall, barley root elongation was found to be the least sensitive to added Ag, with EC50 values ranging from 51 mg/kg to 1030 mg/kg, whereas the tomato plant height showed higher sensitivity with EC50 values ranging from 46 mg/kg to 486 mg/kg. The effect of leaching was more evident in the barley toxicity results, where higher concentrations of Ag were required to induce toxicity. Variations in soil organic carbon and pH were found to be primarily responsible for mitigating Ag toxicity; therefore, these properties may be used in future risk assessments for Ag to predict toxicity in a wide range of soil types. © 2015 SETAC.

  6. Effects of soil properties on the uptake of pharmaceuticals into earthworms

    International Nuclear Information System (INIS)

    Carter, Laura J.; Ryan, Jim J.; Boxall, Alistair B.A.

    2016-01-01

    Pharmaceuticals can enter the soil environment when animal slurries and sewage sludge are applied to land as a fertiliser or during irrigation with contaminated water. These pharmaceuticals may then be taken up by soil organisms possibly resulting in toxic effects and/or exposure of organisms higher up the food chain. This study investigated the influence of soil properties on the uptake and depuration of pharmaceuticals (carbamazepine, diclofenac, fluoxetine and orlistat) in the earthworm Eisenia fetida. The uptake and accumulation of pharmaceuticals into E. fetida changed depending on soil type. Orlistat exhibited the highest pore water based bioconcentration factors (BCFs) and displayed the largest differences between soil types with BCFs ranging between 30.5 and 115.9. For carbamazepine, diclofenac and fluoxetine BCFs ranged between 1.1 and 1.6, 7.0 and 69.6 and 14.1 and 20.4 respectively. Additional analysis demonstrated that in certain treatments the presence of these chemicals in the soil matrices changed the soil pH over time, with a statistically significant pH difference to control samples. The internal pH of E. fetida also changed as a result of incubation in pharmaceutically spiked soil, in comparison to the control earthworms. These results demonstrate that a combination of soil properties and pharmaceutical physico-chemical properties are important in terms of predicting pharmaceutical uptake in terrestrial systems and that pharmaceuticals can modify soil and internal earthworm chemistry which may hold wider implications for risk assessment. - Highlights: • Uptake of pharmaceuticals into earthworms is influenced by soil parameters. • Presence of pharmaceuticals in the terrestrial environment influences soil pH. • Uptake of pharmaceuticals by earthworms changes internal earthworm pH. - The uptake of pharmaceuticals into soil invertebrates is dependent on the complex interplay between pharmaceutical physico-chemical properties and soil

  7. The influence of surface incorporated lime and gypsiferous by-products on surface and subsurface soil acidity. I. Soil solution chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.L.; Hedley, M.J.; Bolan, N.S.; Horne, D.J. [New Zealand Forest Research Institute, Rotorua (New Zealand)

    1999-04-01

    Lime, fluidised bed boiler ash (FBA) and flue gas desulfurisation gypsum (FGDG) were incorporated in the top 50 mm of repacked columns of either an Allophanic (the Patua sand loam) or an Ultic (the Kaawa clay loam) soil, at rates containing calcium equivalent to 5000 kg/ha of CaCO{sub 3}. After leaching with water, the columns were sliced into sections for chemical analysis. In the columns of the variable-charged, allophanic Patua soil, topsoil-incorporated FBA ameliorated top and subsurface soil acidity through liming and the `self liming effect` induced by sulfate sorption, respectively. The soil solution pH of the top and subsurface layers of the Patua soil were raised to pH 6.40 and 5.35, respectively, by the FBA treatment. Consequently , phytotoxic labile monomeric aluminium (Al) concentration in the soil solution of the FBA treatment was reduced to {lt} 0.1 {mu}M Al. FGDG had a similar `self-liming effect` on subsurface of the Patua soil, but not the topsoil. Whereas FBA raised the pH of the Kaawa topsoil, no `self-liming effect` of subsurface soil by sulfate sorption was observed on the Kaawa subsurface soil, which is dominated by permanently charged clay minerals. Application of FBA and FGDG to both soils, however, caused significantly leaching of native soil Mg{sup 2+} and K{sup +}.

  8. Fungi, bacteria and soil pH: the oxalate-carbonate pathway as a model for metabolic interaction.

    Science.gov (United States)

    Martin, Gaëtan; Guggiari, Matteo; Bravo, Daniel; Zopfi, Jakob; Cailleau, Guillaume; Aragno, Michel; Job, Daniel; Verrecchia, Eric; Junier, Pilar

    2012-11-01

    The oxalate-carbonate pathway involves the oxidation of calcium oxalate to low-magnesium calcite and represents a potential long-term terrestrial sink for atmospheric CO(2). In this pathway, bacterial oxalate degradation is associated with a strong local alkalinization and subsequent carbonate precipitation. In order to test whether this process occurs in soil, the role of bacteria, fungi and calcium oxalate amendments was studied using microcosms. In a model system with sterile soil amended with laboratory cultures of oxalotrophic bacteria and fungi, the addition of calcium oxalate induced a distinct pH shift and led to the final precipitation of calcite. However, the simultaneous presence of bacteria and fungi was essential to drive this pH shift. Growth of both oxalotrophic bacteria and fungi was confirmed by qPCR on the frc (oxalotrophic bacteria) and 16S rRNA genes, and the quantification of ergosterol (active fungal biomass) respectively. The experiment was replicated in microcosms with non-sterilized soil. In this case, the bacterial and fungal contribution to oxalate degradation was evaluated by treatments with specific biocides (cycloheximide and bronopol). Results showed that the autochthonous microflora oxidized calcium oxalate and induced a significant soil alkalinization. Moreover, data confirmed the results from the model soil showing that bacteria are essentially responsible for the pH shift, but require the presence of fungi for their oxalotrophic activity. The combined results highlight that the interaction between bacteria and fungi is essential to drive metabolic processes in complex environments such as soil. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  9. Influence of plant roots upon the mobility of radionuclides in soil, with respect to location of contamination below the surface

    International Nuclear Information System (INIS)

    Harvey, N.W.; Shaw, G.; Bell, N.J.B.

    1997-01-01

    The movement of 85 Sr, 137 Cs, 54 Mn and 60 Co in the 50 cm soil profile was studied with and without the presence of plant roots (triticum aestivum) in order to investigate the influence of roots and depth contamination upon the migration of radionuclides. The water table was maintained manually at 3 cm from the bottom. The physicochemical characteristics (E h Fe -2 , NH 4 + , pH and moisture content) as well as the total and extractable radioactivity were investigated. In the discrete contamination, where the location of contamination varied within the soil profile (0-5, 25-30 or 45-50 cm from the top), the influence of location upon the movement of these radionuclides was also studied. It was found that the changes in the soil physicochemical characteristics influenced the mobility of the four radionuclides. The extractability of 54 Mn and 60 Co was significantly increased in the reducing region of the soil, whereas that of 85 Sr, 137 Cs was not. Plant roots excerted significant effects upon the soil characteristics, via, reducing the E h pH and moisture content of the soil; increasing the extractability of both 54 Mn and 60 Co from the depth of 35 cm downwards. Radionuclide migration occurred via physicochemical and biological transport. The biological transport via plant roots was of particular importance for 137 Cs. Location of contamination had a significant influence upon the mobility of radionuclides. The migration of radionuclides was in the sequence of contamination in middle > bottom > top. The degree of the influence varied with radionuclides concerned. In the top layer contamination, the rank of the migration from the contamination layers, on the other hand 54 Mn, 60 Co and 137 Cs were more mobile and the movement was: 85 Sr ∼ 54 Mn ∼ 60 Co > 137 Cs. In the middle and bottom contamination layers, on the other hand, 54 Mn and 60 Co and 137 Cs were more mobile and the movement was 85 Sr ∼ 54 Mn ∼ 60 Co ∼ 137 Cs. (author)

  10. Stair-Step Pattern of Soil Bacterial Diversity Mainly Driven by pH and Vegetation Types Along the Elevational Gradients of Gongga Mountain, China.

    Science.gov (United States)

    Li, Jiabao; Shen, Zehao; Li, Chaonan; Kou, Yongping; Wang, Yansu; Tu, Bo; Zhang, Shiheng; Li, Xiangzhen

    2018-01-01

    Ecological understandings of soil bacterial community succession and assembly mechanism along elevational gradients in mountains remain not well understood. Here, by employing the high-throughput sequencing technique, we systematically examined soil bacterial diversity patterns, the driving factors, and community assembly mechanisms along the elevational gradients of 1800-4100 m on Gongga Mountain in China. Soil bacterial diversity showed an extraordinary stair-step pattern along the elevational gradients. There was an abrupt decrease of bacterial diversity between 2600 and 2800 m, while no significant change at either lower (1800-2600 m) or higher (2800-4100 m) elevations, which coincided with the variation in soil pH. In addition, the community structure differed significantly between the lower and higher elevations, which could be primarily attributed to shifts in soil pH and vegetation types. Although there was no direct effect of MAP and MAT on bacterial community structure, our partial least squares path modeling analysis indicated that bacterial communities were indirectly influenced by climate via the effect on vegetation and the derived effect on soil properties. As for bacterial community assembly mechanisms, the null model analysis suggested that environmental filtering played an overwhelming role in the assembly of bacterial communities in this region. In addition, variation partition analysis indicated that, at lower elevations, environmental attributes explained much larger fraction of the β-deviation than spatial attributes, while spatial attributes increased their contributions at higher elevations. Our results highlight the importance of environmental filtering, as well as elevation-related spatial attributes in structuring soil bacterial communities in mountain ecosystems.

  11. Accounting for pH heterogeneity and variability in modelling human health risks from cadmium in contaminated land

    International Nuclear Information System (INIS)

    Gay, J. Rebecca; Korre, Anna

    2009-01-01

    The authors have previously published a methodology which combines quantitative probabilistic human health risk assessment and spatial statistical methods (geostatistics) to produce an assessment, incorporating uncertainty, of risks to human health from exposure to contaminated land. The model assumes a constant soil to plant concentration factor (CF veg ) when calculating intake of contaminants. This model is modified here to enhance its use in a situation where CF veg varies according to soil pH, as is the case for cadmium. The original methodology uses sequential indicator simulation (SIS) to map soil concentration estimates for one contaminant across a site. A real, age-stratified population is mapped across the contaminated area, and intake of soil contaminants by individuals is calculated probabilistically using an adaptation of the Contaminated Land Exposure Assessment (CLEA) model. The proposed improvement involves not only the geostatistical estimation of the contaminant concentration, but also that of soil pH, which in turn leads to a variable CF veg estimate which influences the human intake results. The results presented demonstrate that taking pH into account can influence the outcome of the risk assessment greatly. It is proposed that a similar adaptation could be used for other combinations of soil variables which influence CF veg .

  12. Soil pH Is the Primary Factor Correlating With Soil Microbiome in Karst Rocky Desertification Regions in the Wushan County, Chongqing, China

    Directory of Open Access Journals (Sweden)

    Daihua Qi

    2018-05-01

    Full Text Available Karst rocky desertification (KRD is a process of land degradation, which causes desert-like landscapes, deconstruction of endemic biomass, and declined soil quality. The relationship of KRD progression with above-ground communities (e.g. vegetation and animal is well-studied. Interaction of soil desertification with underground communities, such as soil microbiome, however, is vastly unknown. This study characterizes change in soil bacterial community in response to KRD progression. Soil bacterial communities were surveyed by deep sequencing of 16S amplicons. Eight soil properties, pH, soil organic matter (SOM, total and available nitrogen (TN and AN, total and available phosphorus (TP and AP, and total and available potassium (TK and AK, were measured to assess soil quality. We find that the overall soil quality decreases along with KRD progressive gradient. Soil bacterial community compositions are distinguishingly different in KRD stages. The richness and diversity in bacterial community do not significantly change with KRD progression although a slight increase in diversity was observed. A slight decrease in richness was seen in SKRD areas. Soil pH primarily correlates with bacterial community composition. We identified a core microbiome for KRD soils consisting of; Acidobacteria, Alpha-Proteobacteria, Planctomycetes, Beta-Proteobacteria, Actinobacteria, Firmicutes, Delta-Proteobacteria, Chloroflexi, Bacteroidetes, Nitrospirae, and Gemmatimonadetes in this study. Phylum Cyanobacteria is significantly abundant in non-degraded soils, suggesting that Cyanobacterial activities might be correlated to soil quality. Our results suggest that Proteobacteria are sensitive to changes in soil properties caused by the KRD progression. Alpha- and beta-Proteobacteria significantly predominated in SKRD compared to NKRD, suggesting that Proteobacteria, along with many others in the core microbiome (Acidobacteria, Actinobacteria, Firmicutes, and Nitrospirae

  13. The effect of the soil pH on 134Cs transfer factors for soybean and sunflower plants; 134Cs fate in the extracted seed-oil

    International Nuclear Information System (INIS)

    Massas, I.; Skarlou, C.; Anoussis, J.; Haidouti, C.; Arapis, G.

    1999-01-01

    The effect of soil pH on 134 Cs TFs as well as the fate of 134 Cs in the extracted oil was studied in a greenhouse experiment with soybean and sunflower plants. A soil with pH 4.2 was used as a basis and its pH value has increased to 5.7, 6.5 and 7.6 (by the addition of different amounts of Ca(OH) 2 ). The lowest TF value was observed in the calcareous soil (pH 7.6), while the highest in the lowest pH (4.2) for the vegetative part and in the pH 6.5 for the edible part for both studied plants. TFs were practically the same for soya plants grown on the three lowest soil pH and reduced significantly only at pH 7.6 for either pods or other plant material. However, the lowest/highest TF was ∼ 4 for pods and ∼ 6 for the other plant material. For the sunflower plants while TFs for other plant material reduced from lowest to highest soil pH by only a factor of 2, for the seeds TFs remained rather constant. The difference in TF between the two studied species in each soil pH was in some cases higher than the difference due to pH effect. When an oil fraction (∼ 20 %) was extracted from seeds of both plants, no 134 Cs was detected. Refs. 4 (author)

  14. Influence of Acacia trees on soil nutrient levels in arid lands

    Science.gov (United States)

    De Boever, Maarten; Gabriels, Donald; Ouessar, Mohamed; Cornelis, Wim

    2014-05-01

    The potential of scattered trees as keystone structures in restoring degraded environments is gaining importance. Scattered trees have strong influence on their abiotic environment, mainly causing changes in microclimate, water budget and soil properties. They often function as 'nursing trees', facilitating the recruitment of other plants. Acacia raddiana is such a keystone species which persists on the edge of the Sahara desert. The study was conducted in a forest-steppe ecosystem in central Tunisia where several reforestation campaigns with Acacia took place. To indentify the impact of those trees on soil nutrients, changes in nutrient levels under scattered trees of three age stages were examined for the upper soil layer (0-10 cm) at five microsites with increasing distance from the trunk. In addition, changes in soil nutrient levels with depth underneath and outside the canopy were determined for the 0-30 cm soil layer. Higher concentrations of organic matter (OM) were found along the gradient from underneath to outside the canopy for large trees compared to medium and small trees, especially at microsites close to the trunk. Levels of soluble K, electrical conductivity (EC), available P, OM, total C and N decreased whereas pH and levels of soluble Mg increased with increasing distance from tree. Levels of soluble Ca and Na remained unchanged along the gradient. At the microsite closest to the trunk a significant decrease in levels of soluble K, EC, OM, available P, total C and N, while a significant increase in pH was found with increasing depth. The concentration of other nutrients remained unchanged or declined not differently underneath compared to outside the canopy with increasing depth. Differences in nutrient levels were largely driven by greater inputs of organic matter under trees. Hence, Acacia trees can affect the productivity and reproduction of understory species with the latter in term an important source of organic matter. This positive feedback

  15. Effect of Soil pH Increase by Biochar on NO, N2O and N2 Production during Denitrification in Acid Soils.

    Directory of Open Access Journals (Sweden)

    Alfred Obia

    Full Text Available Biochar (BC application to soil suppresses emission of nitrous- (N2O and nitric oxide (NO, but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2 were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH.

  16. Effect of heavy metals on pH buffering capacity and solubility of Ca, Mg, K, and P in non-spiked and heavy metal-spiked soils.

    Science.gov (United States)

    Najafi, Sarvenaz; Jalali, Mohsen

    2016-06-01

    In many parts of the world, soil acidification and heavy metal contamination has become a serious concern due to the adverse effects on chemical properties of soil and crop yield. The aim of this study was to investigate the effect of pH (in the range of 1 to 3 units above and below the native pH of soils) on calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) solubility in non-spiked and heavy metal-spiked soil samples. Spiked samples were prepared by cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) as chloride salts and incubating soils for 40 days. The pH buffering capacity (pHBC) of each sample was determined by plotting the amount of H(+) or OH(-) added (mmol kg(-1)) versus the related pH value. The pHBC of soils ranged from 47.1 to 1302.5 mmol kg(-1) for non-spiked samples and from 45.0 to 1187.4 mmol kg(-1) for spiked soil samples. The pHBC values were higher in soil 2 (non-spiked and spiked) which had higher calcium carbonate content. The results indicated the presence of heavy metals in soils generally decreased the solution pH and pHBC values in spiked samples. In general, solubility of Ca, Mg, and K decreased with increasing equilibrium pH of non-spiked and spiked soil samples. In the case of P, increasing the pH to about 7, decreased the solubility in all soils but further increase of pH from 7, enhanced P solubility. The solubility trends and values for Ca, Mg, and K did not differed significantly in non-spiked and spiked samples. But in the case of P, a reduction in solubility was observed in heavy metal-spiked soils. The information obtained in this study can be useful to make better estimation of the effects of soil pollutants on anion and cation solubility from agricultural and environmental viewpoints.

  17. Is Tree Species Diversity or Species Identity the More Important Driver of Soil Carbon Stocks, C/N Ratio, and pH?

    DEFF Research Database (Denmark)

    Dawud, Seid Muhie; Raulund-Rasmussen, Karsten; Domisch, Timo

    2016-01-01

    We explored tree species diversity effects on soil C stock, C/N ratio, and pH as compared with effects of tree species identity. We sampled forest floors and mineral soil (0–40 cm) in a diversity gradient of 1–5 tree species composed of conifers and broadleaves in Białowieża Forest, Poland...... mechanism for higher root carbon input and in turn a deeper distribution of C in diverse forests. Diversity and identity affected soil pH in topsoil with positive and negative impacts, respectively. More diverse forests would lead to higher soil nutrient status as reflected by higher topsoil p......H, but there was a slight negative effect on N status as indicated by higher C/N ratios in the deeper layers. We conclude that tree species diversity increases soil C stocks and nutrient status to some extent, but tree species identity is a stronger driver of the studied soil properties, particularly in the topsoil....

  18. Growth and Cadmium Phytoextraction by Swiss Chard, Maize, Rice, Noccaea caerulescens, and Alyssum murale in Ph Adjusted Biosolids Amended Soils.

    Science.gov (United States)

    Broadhurst, C Leigh; Chaney, Rufus L; Davis, Allen P; Cox, Albert; Kumar, Kuldip; Reeves, Roger D; Green, Carrie E

    2015-01-01

    Past applications of biosolids to soils at some locations added higher Cd levels than presently permitted. Cadmium phytoextraction would alleviate current land use constraints. Unamended farm soil, and biosolids amended farm and mine soils were obtained from a Fulton Co., IL biosolids management facility. Soils contained 0.16, 22.8, 45.3 mg Cd kg(-1) and 43.1, 482, 812 mg Zn kg(-1) respectively with initial pH 6.0, 6.1, 6.4. In greenhouse studies, Swiss chard (Beta vulgaris var. cicla), a Cd-accumulator maize (inbred B37 Zea mays) and a southern France Cd-hyperaccumulator genotype of Noccaea caerulescens were tested for Cd accumulation and phytoextraction. Soil pH was adjusted from ∼5.5-7.0. Additionally 100 rice (Oryza sativa) genotypes and the Ni-hyperaccumulator Alyssum murale were screened for potential phytoextraction use. Chard suffered phytotoxicity at low pH and accumulated up to 90 mg Cd kg(-1) on the biosolids amended mine soil. The maize inbred accumulated up to 45 mg Cd kg(-1) with only mild phytotoxicity symptoms during early growth at pH>6.0. N. caerulescens did not exhibit phytotoxicity symptoms at any pH, and accumulated up to 235 mg Cd kg(-1) in 3 months. Reharvested N. caerulescens accumulated up to 900 mg Cd kg(-1) after 10 months. Neither Alyssum nor 90% of rice genotypes survived acceptably. Both N. caerulescens and B37 maize show promise for Cd phytoextraction in IL and require field evaluation; both plants could be utilized for nearly continuous Cd removal. Other maize inbreds may offer higher Cd phytoextraction at lower pH, and mono-cross hybrids higher shoot biomass yields. Further, maize grown only for biomass Cd maximum removal could be double-cropped.

  19. Influence of early pH decline on calpain activity in porcine muscle

    DEFF Research Database (Denmark)

    Pomponio, Luigi; Ertbjerg, Per; Karlsson, Anders H

    2010-01-01

    myofibril fragmentation at 24 h post-mortem was observed, which was no longer evident in the later phase of the tenderization process. In conclusion, the rate of early pH decline influenced l-calpain activity and the rate but not the extent of myofibrillar degradation, suggesting an early effect......This study investigated the influence of post-mortem pH decline on calpain activity and myofibrillar degradation.From 80 pigs, 30 Longissimus dorsi (LD) muscles were selected on the basis of pH values at 3 h post-mortem and classified into groups of 10 as fast, intermediate and slow pH decline...... measured. A faster decrease in pH resulted in reduced level of l-calpain activity and increased autolysis of the enzyme, and hence an earlier loss of activity due to activation of l-calpain in muscles with a fast pH decline. Paralleling the l-calpain activation in muscles with a fast pH decline a higher...

  20. Changes in the pH and other soil chemical parameters in soil surrounding wood ant (.i.Formica polyctena./i.) nests

    Czech Academy of Sciences Publication Activity Database

    Jílková, Veronika; Matějíček, L.; Frouz, J.

    2011-01-01

    Roč. 47, č. 1 (2011), s. 72-76 ISSN 1164-5563 Institutional research plan: CEZ:AV0Z60660521 Keywords : wood ants * soil pH * nutrients Subject RIV: EH - Ecology, Behaviour Impact factor: 1.578, year: 2011

  1. Soil pH and nutrient uptake in cauliflower (Brassica oleracea L. var. botrytis) and Broccoli (Brassica oleracea L. var. italica) in Northern Sweden. Multielement studies by means of plant and soil analyses

    Energy Technology Data Exchange (ETDEWEB)

    Magnusson, Margareta [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Agricultural Research for Northern Sweden

    2000-07-01

    To reveal nutrient element deficiencies or imbalances limiting vegetable production in northern Sweden, multielement soil and plant analyses were performed in cauliflower and broccoli during the period 1989 to 1996. The pH range of the soils was 4.4-8. 1. The results were evaluated with the multivariate statistical methods PCA (Principal Component Analysis) and PLS (Partial Least Squares Projection to Latent Structures). The major yield-limiting elements were Mg, B, Mn, Zn, Fe and Cu. This was a result of high soil pH and large content of Ca in the soil. The reason for B deficiency was also low B content in the soil. Applications of green mulch increased yield on soils with a pH below 6.0. It also increased the uptake and concentration in the plants of B, Ba, Cl, Cu, K, Mg, Mn, N, P, Se and Zn, and decreased the uptake and concentration of Al, Cs and Tl. The mineral fertilizer applied, NPK 11-5-18 micro, decreased soil pH. This has resulted in larger uptake and higher concentrations in the plants of Co and Mn, in comparison to where cattle manure was applied. This fertilizer strongly decreased uptake of Mo, as a result of both the acidifying effect and the large S content. Repeated applications of nitrate of lime in combination with the NPK 11-5-18 strongly increased the uptake of Cs by the plants. The results in this investigation, together with the literature reviews, strongly indicate that a relatively low soil pH (5.0-5.5) is favourable when organic fertilizers are used and that harmful effects of very low soil pH (<5.0), are ameliorated by organic materials but aggravated by mineral fertilizers. The main purpose of lime is to counteract the acidity and increased leaching created by mineral fertilizers. Because of the historical context in which the lime requirements were established, the dangers of acid soils appear to have been strongly overestimated.

  2. Wood Ash Induced pH Changes Strongly Affect Soil Bacterial Numbers and Community Composition

    DEFF Research Database (Denmark)

    Bang-Andreasen, Toke; Nielsen, Jeppe T.; Voriskova, Jana

    2017-01-01

    Recirculation of wood ash from energy production to forest soil improves the sustainability of this energy production form as recycled wood ash contains nutrients that otherwise would be lost at harvest. In addition, wood-ash is beneficial to many soils due to its inherent acid......-neutralizing capabilities. However, wood ash has several ecosystem-perturbing effects like increased soil pH and pore water electrical conductivity both known to strongly impact soil bacterial numbers and community composition. Studies investigating soil bacterial community responses to wood ash application remain sparse...... and the available results are ambiguous and remain at a general taxonomic level. Here we investigate the response of bacterial communities in a spruce forest soil to wood ash addition corresponding to 0, 5, 22, and 167 t wood ash ha(-1). We used culture-based enumerations of general bacteria, Pseudomonas...

  3. Standard test method for measuring pH of soil for use in corrosion testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1995-01-01

    1.1 This test method covers a procedure for determining the pH of a soil in corrosion testing. The principle use of the test is to supplement soil resistivity measurements and thereby identify conditions under which the corrosion of metals in soil may be accentuated (see G 57 - 78 (1984)). 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  4. Influence of pH on the localized corrosion of iron

    International Nuclear Information System (INIS)

    Webley, R.; Henry, R.

    1986-06-01

    The influence of pH on the pitting corrosion of iron in chloride and sulfate solutions was determined using two artificial pit apparatuses to obtain the pH near the surface of the pit bottom. A glass membrane electrode and an antimony electrode were used to measure pH in the two apparatuses. Using solutions of NaCl and Na 2 SO 4 at current densities of 0.5, 5.0, and 10 mA/cm 2 pH's in the range 5 to 6 were obtained with the first apparatus. The antimony probe did not measure pH accurately in solutions of 1 N NaCl and 1 N Na 2 SO 4 and had an error of approximately 2 pH units. A one-dimensional transport model was developed to predict pH variations around the pit mouth and inside the pit. The validity of this model was not verified due to the relative lack of precision with pH measurement techniques

  5. Influence of humic substances on enhanced remediation of soil polluted by a copper-nickel smelter

    Science.gov (United States)

    Tregubova, Polina; Turbaevskaya, Valeria; Korneecheva, Mariya; Kupriyanova, Yuliya; Koptsik, Galina

    2017-04-01

    The problem of technogenic contamination through the anthropogenic activity is quite urgent nowadays. Long-term air pollution with sulphur dioxide and heavy metals (HM) by injuring vegetation and inhibition of plant and soil microorganisms growth and activity causes appearance of the barren areas - highly damaged eroded ecosystems requiring remediation. There are a lot of remediation ways, but an appropriate restoration method, which does not expensive, does not demand special technical support and corresponds to the natural conditions of soil development is still open to question. We suggest application of exogenous humic substances as the possible environmentally friendly solution of HM toxicity problem and soil health restoration. Using of humates can result in the improvement of soil properties, localization of contamination by decreasing of HM mobility and bioavailability through binding them in relatively immobile complexes, and in stabilization of organic pool. But practice of scientific society as well as our previous investigations demonstrates ambiguous influence of exogenic humic substances on the behavior of HM depending on origin, doses, molecular weight of organic matter and state of microorganisms. In this research we have provided series of short-term (45 days) experiments dedicated to the evaluation of suitable doses of humates of different origin - coal and peat - inoculated by nitrogen fixers and mycorhizae-forming fungi in comparison with lime and NPK-fertilizer on the properties of contaminated soil and mobility of HM. The object of investigation was Al-Fe-humus abrazems from the vicinity of mining-and-metallurgical integrated work located in the Kola Peninsula, Russia. This soil is characterized by the absence of vegetation, complete loss of the organic horizon in result of the erosion processes, low pH (pH H2O 4.1-5.0), low exchangeable acidity (0.8-1.6 cmolc/kg), and depletion of organic mater (content of total carbon is 0.3-0.5%). The main

  6. Bacterial chitinolytic communities respond to chitin and pH alteration in soil

    DEFF Research Database (Denmark)

    Kielak, Anna; Cretoiu, Mariana; Semenov, Alexander

    2013-01-01

    by the addition of chitin at different prevailing soil pH values. Interestingly, a major role of Gram-negative bacteria versus a minor one of Actinobacteria in the immediate response to the added chitin (based on 16S rRNA gene abundance and chiA gene types) was indicated. The results of this study enhance our...

  7. Why is the influence of soil macrofauna on soil structure only considered by soil ecologists ?

    OpenAIRE

    Bottinelli, N.; Jouquet, Pascal; Capowiez, Y.; Podwojewski, Pascal; Grimaldi, Michel; Peng, X.

    2015-01-01

    These last twenty years have seen the development of an abundant literature on the influence of soil macrofauna on soil structure. Amongst these organisms, earthworms, termites and ants are considered to play a key role in regulating the physical, chemical and microbiological properties of soils. Due to these influential impacts, soil ecologists consider these soil macro-invertebrates as ‘soil engineers’ and their diversity and abundance are nowadays considered as relevant bioindi...

  8. Influence of Amang (Tin Tailing) on Geotechnical Properties of Clay Soil

    International Nuclear Information System (INIS)

    Zulfahmi, A.R.; Zuhairi, W.Y.W.; Raihan, M.T.; Sahibin, A.R.; Razi, I.W.M.; Tukimat, L.; Syakireen, Z.S.N.; Noorulakma, A.

    2012-01-01

    Amang or tin tailing is commonly found in the vicinity of disused mining area and responsible in downgrading the water quality, landscape and mechanical behaviour of soils. It was generated from extraction process of separating valuable metal from particular ore. This paper presents the geotechnical characteristics of amang-contaminated clay soil. The geotechnical properties of uncontaminated soils were studied in order to compare to that of amang contaminated soils. The base soil used in this study represents completely weathered horizon of meta sedimentary rock. Meanwhile, tin tailing sample was taken from the disused mine at Sungai Lembing, Pahang. The geotechnical characterisations of base soil and contaminated soils were determined based on consistency index, compaction behaviour, hydraulic conductivity and undrained shear strength (UU tests). Contaminated soil samples were prepared by adding 5, 10 and 20 % of tailing, based on dry weigh of the studied base soil. The results from the particle size distribution analysis showed that residual soil from meta sedimentary rock comprised 42.6 % clay, 32.2 % silt and 25.2 % sand whilst tailing was dominated by 98 % of sand fraction. XRD analysis indicated the presence of quartz, kaolinite and muscovite minerals in the studied soil. The specific gravity of soil used is 2.67 and the pH is 3.88. Tailing found to have higher specific gravity of 3.37. The consistency index of contaminated soils showed that liquid limit, wL and plastic limit, wP decreased with the increase in the percentage of tailing added to the soil samples. The value of maximum dry density, ρ dry max increased while optimum moisture content decreased due to the increase in tailing content in soil sample. The permeability of contaminated soil also increased with the increase in tailing contents ranged from 19.8 cm/ hr to 23.8 cm/ hr. The undrained shear strength, Cu, of contaminated soil decreased from 646 kPa (5 % of tailing) to 312 kPa (20 % of

  9. Low pH, aluminum, and phosphorus coordinately regulate malate exudation through GmALMT1 to improve soybean adaptation to acid soils.

    Science.gov (United States)

    Liang, Cuiyue; Piñeros, Miguel A; Tian, Jiang; Yao, Zhufang; Sun, Lili; Liu, Jiping; Shaff, Jon; Coluccio, Alison; Kochian, Leon V; Liao, Hong

    2013-03-01

    Low pH, aluminum (Al) toxicity, and low phosphorus (P) often coexist and are heterogeneously distributed in acid soils. To date, the underlying mechanisms of crop adaptation to these multiple factors on acid soils remain poorly understood. In this study, we found that P addition to acid soils could stimulate Al tolerance, especially for the P-efficient genotype HN89. Subsequent hydroponic studies demonstrated that solution pH, Al, and P levels coordinately altered soybean (Glycine max) root growth and malate exudation. Interestingly, HN89 released more malate under conditions mimicking acid soils (low pH, +P, and +Al), suggesting that root malate exudation might be critical for soybean adaptation to both Al toxicity and P deficiency on acid soils. GmALMT1, a soybean malate transporter gene, was cloned from the Al-treated root tips of HN89. Like root malate exudation, GmALMT1 expression was also pH dependent, being suppressed by low pH but enhanced by Al plus P addition in roots of HN89. Quantitative real-time PCR, transient expression of a GmALMT1-yellow fluorescent protein chimera in Arabidopsis protoplasts, and electrophysiological analysis of Xenopus laevis oocytes expressing GmALMT1 demonstrated that GmALMT1 encodes a root cell plasma membrane transporter that mediates malate efflux in an extracellular pH-dependent and Al-independent manner. Overexpression of GmALMT1 in transgenic Arabidopsis, as well as overexpression and knockdown of GmALMT1 in transgenic soybean hairy roots, indicated that GmALMT1-mediated root malate efflux does underlie soybean Al tolerance. Taken together, our results suggest that malate exudation is an important component of soybean adaptation to acid soils and is coordinately regulated by three factors, pH, Al, and P, through the regulation of GmALMT1 expression and GmALMT1 function.

  10. Characterization and nutrient release from silicate rocks and influence on chemical changes in soil

    Directory of Open Access Journals (Sweden)

    Douglas Ramos Guelfi Silva

    2012-06-01

    Full Text Available The expansion of Brazilian agriculture has led to a heavy dependence on imported fertilizers to ensure the supply of the growing food demand. This fact has contributed to a growing interest in alternative nutrient sources, such as ground silicate rocks. It is necessary, however, to know the potential of nutrient release and changes these materials can cause in soils. The purpose of this study was to characterize six silicate rocks and evaluate their effects on the chemical properties of treated soil, assessed by chemical extractants after greenhouse incubation. The experimental design consisted of completely randomized plots, in a 3 x 6 factorial scheme, with four replications. The factors were potassium levels (0-control: without silicate rock application; 200; 400; 600 kg ha-1 of K2O, supplied as six silicate rock types (breccia, biotite schist, ultramafic rock, phlogopite schist and two types of mining waste. The chemical, physical and mineralogical properties of the alternative rock fertilizers were characterized. Treatments were applied to a dystrophic Red-Yellow Oxisol (Ferralsol, which was incubated for 100 days, at 70 % (w/w moisture in 3.7 kg/pots. The soil was evaluated for pH; calcium and magnesium were extracted with KCl 1 mol L-1; potassium, phosphorus and sodium by Mehlich 1; nickel, copper and zinc with DTPA; and the saturation of the cation exchange capacity was calculated for aluminum, calcium, magnesium, potassium, and sodium, and overall base saturation. The alternative fertilizers affected soil chemical properties. Ultramafic rock and Chapada mining byproduct (CMB were the silicate rocks that most influenced soil pH, while the mining byproduct (MB led to high K levels. Zinc availability was highest in the treatments with mining byproduct and Cu in soil fertilized with Chapada and mining byproduct.

  11. Potential phosphorus eutrophication mitigation strategy: Biochar carbon composition, thermal stability and pH influence phosphorus sorption.

    Science.gov (United States)

    Ngatia, L W; Hsieh, Y P; Nemours, D; Fu, R; Taylor, R W

    2017-08-01

    Phosphorus (P) eutrophication is a major pollution problem globally, with unprecedented amount of P emanating from agricultural sources. But little is known about the optimization of soil-biochar P sorption capacity. The study objective was to determine how biochar feedstocks and pyrolysis conditions influences carbon (C) thermal stability, C composition and pH and in turn influence the phosphorus sorption optimization. Biochar was produced from switchgrass, kudzu and Chinese tallow at 200, 300, 400, 500, 550, 650,750 °C. Carbon thermal stability was determined by multi-element scanning thermal analysis (MESTA), C composition was determined using solid state 13 C NMR. Phosphorus sorption was determined using a mixture of 10% biochar and 90% sandy soil after incubation. Results indicate increased P sorption (P biochar pyrolysis temperature. However, optimum P sorption was feedstock specific with switchgrass indicating P desorption between 200 and 550 °C. Phosphorus sorption was in the order of kudzu > switchgrass > Chinese tallow. Total C, C thermal stability, aromatic C and alkalinity increased with elevated pyrolysis temperature. Biochar alkalinity favored P sorption. There was a positive relationship between high thermal stable C and P sorption for Kudzu (r = 0.62; P = 0.0346) and Chinese tallow (r = 0.73; P = 0.0138). In conclusion, biochar has potential for P eutrophication mitigation, however, optimum biochar pyrolysis temperature for P sorption is feedstock specific and in some cases might be out of 300-500 °C temperature range commonly used for agronomic application. High thermal stable C dominated by aromatic C and alkaline pH seem to favor P sorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Adsorción de cadmio, cromo y mercurio en suelos del Valle del Cauca a varios valores de pH Cadmium, chromium and mercury adsorption on Cauca Valley soils as a function of pH

    Directory of Open Access Journals (Sweden)

    García O. Álvaro

    1991-12-01

    Full Text Available Con el fin de observar el proceso de adsorción de Cd, Cr y Hg y determinar el efecto del pH sobre la adsorción de los metales indicados, se seleccionaron tres suelos de los órdenes predominantes en el Valle del Cauca que, por su ubicación, están siendo regados con aguas contaminadas o pueden llegar a serlo en un futuro. El pH de los suelos se ajustó con ácido acético al 1, 4 y 12% o con NaOH 0.01 N para obtener valores lo más próximo posible a 5.7, 6.5 Y 7.8. Se prepararon soluciones de equilibrio con cada metal (0.0, 0.28, 0.56, 1.12 Y 2.25 mg/L y se adicionaron a 0.25 g de suelo seco al aire y tamizado para pasar una malla de 2 mm. La extracción de los metales se realizó con HCI 001 N y se determinaron por espectrofotometría de absorción atómica. La diferencia entre la concentración inicial y la final se consideró como la cantidad adsorbida por el suelo y la diferencia entre la cantidad adsorbida y la cantidad extraída con H Cl 0.01 N se consideró como la cantidad retenida por el suelo. En general el Cd se adsorbe más a valores de pH neutro o alcalino en todos los suelos, debido a que su forma predominante es la divalente y tiende más a formar complejos solubles e insolubles con los aniones encontrados en el suelo por encima de pH 7.0. La adsorción de Cr y Hg es mayor a valores de pH ácido debido a que forman complejos con la materia orgánica del suelo y/o los óxidos e hidróxidos de Fe, Al y Mn cuyas reacciones se ven favorecidas a estos valores de pH. La menor extracción (mayor retención en todos los suelos se dio a valores de pH entre 6.4 y 6.6, indicando que en este pH los metales quedan fuertemente retenidos por el complejo de cambio y su disponibilidad hacia las plantas es mínima.Soils irrigated with heavy metals contamined water are common in Cauca Valley and there is not available information about of soil behavior and soil processes affected by Cd, Cr and Hg. Three soils of the main orders of Cauca Valley

  13. Path coefficient analysis of zinc dynamics in varying soil environment

    International Nuclear Information System (INIS)

    Rattan, R.K.; Phung, C.V.; Singhal, S.K.; Deb, D.L.; Singh, A.K.

    1994-01-01

    Influence of soil properties on labile zinc, as measured by diethylene-triamine pentaacetic acid (DTPA) and zinc-65, and self-diffusion coefficients of zinc was assessed on 22 surface soil samples varying widely in their characteristics following linear regression and path coefficient analysis techniques. DTPA extractable zinc could be predicted from organic carbon status and pH of the soil with a highly significant coefficient of determination (R 2 =0.84 ** ). Ninety seven per cent variation in isotopically exchangeable zinc was explained by pH, clay content and cation exchange capacity (CEC) of soil. The self-diffusion coefficients (DaZn and DpZn) and buffer power of zinc exhibited exponential relationship with soil properties, pH being the most dominant one. Soil properties like organic matter, clay content etc. exhibited indirect effects on zinc diffusion rates via pH only. (author). 13 refs., 6 tabs

  14. Pyrolysis temperature influences ameliorating effects of biochars on acidic soil.

    Science.gov (United States)

    Wan, Qing; Yuan, Jin-Hua; Xu, Ren-Kou; Li, Xing-Hui

    2014-02-01

    The biochars were prepared from straws of canola, corn, soybean, and peanut at different temperatures of 300, 500, and 700 °C by means of oxygen-limited pyrolysis.Amelioration effects of these biochars on an acidic Ultisol were investigated with incubation experiments, and application rate of biochars was 10 g/kg. The incorporation of these biochars induced the increase in soil pH, soil exchangeable base cations, base saturation, and cation exchange capacity and the decrease in soil exchangeable acidity and exchangeable Al. The ameliorating effects of biochars on acidic soil increased with increase in their pyrolysis temperature. The contribution of oxygen-containing functional groups on the biochars to their ameliorating effects on the acidic soil decreased with the rise in pyrolysis temperature, while the contribution from carbonates in the biochars changed oppositely. The incorporation of the biochars led to the decrease in soil reactive Al extracted by 0.5mol/L CuCl2, and the content of reactive Al was decreased with the increase in pyrolysis temperature of incorporated biochars. The biochars generated at 300 °C increased soil organically complexed Al due to ample quantity of oxygen-containing functional groups such as carboxylic and phenolic groups on the biochars, while the biochars generated at 500 and 700 °C accelerated the transformation of soil exchangeable Al to hydroxyl-Al polymers due to hydrolysis of Al at higher pH. Therefore, the crop straw-derived biochars can be used as amendments for acidic soils and the biochars generated at relatively high temperature have great ameliorating effects on the soils.

  15. Cadmium and Zn availability as affected by pH manipulation and its assessment by soil extraction, DGT and indicator plants

    International Nuclear Information System (INIS)

    Muhammad, Iqbal; Puschenreiter, Markus; Wenzel, Walter W.

    2012-01-01

    Manipulation of soil pH by soil additives and / or rhizosphere processes may enhance the efficiency of metal phytoextraction. Here we report on the effect of nitric acid additions to four polluted soils on Cd and Zn concentrations in soil solution (C soln ) and 0.005 M Ca(NO 3 ) 2 extracts, and related changes in the diffusive fluxes and resupply of the metals as assessed by diffusive gradients in thin films (DGT). The responses of these chemical indicators of bioavailability were compared to metal uptake in two indicator plant species, common dandelion (Taraxacum officinale F.H. Wigg) and narrow leaf plantain (Plantago lanceolata L.) grown for 75 days in a pot experiment. Lowering soil pH increased C soln , the 0.005 M Ca(NO 3 ) 2 -soluble fractions and the DGT-measured Cd and Zn concentrations (C DGT ) in the experimental soils. This was associated with enhanced uptake of Cd and Zn on soils acidified to pH 4.5 whereas plants did not survive at pH 3.5. Toxicity along with decreased kinetics of metal resupply (calculated by the 2D DIFS model) in the strong acidification treatment suggests that moderate acidification is more appropriate to enhance the phytoextraction process. Each of the chemical indicators of bioavailability predicted well (R 2 > 0.70) the Cd and Zn concentrations in plantain shoots but due to metal toxicity not for dandelion. Concentration factors, i.e. the ratio between metal concentrations in shoots and in soil solution (CF) indicate that Cd and Zn uptake in plantain was not limited by diffusion which may explain that DGT did not perform better than C soln . However, DGT is expected to predict plant uptake better in diffusion-limited conditions such as in the rhizosphere of metal-accumulating phytoextraction crops. - Highlights: ► The effect of soil acidification was assessed for four Zn and Cd polluted soils. ► For some soils moderate acidification could enhance the metal uptake efficiency. ► Chemical assessment of bioavailability using

  16. Cadmium and Zn availability as affected by pH manipulation and its assessment by soil extraction, DGT and indicator plants

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Iqbal; Puschenreiter, Markus, E-mail: markus.puschenreiter@boku.ac.at; Wenzel, Walter W.

    2012-02-01

    Manipulation of soil pH by soil additives and / or rhizosphere processes may enhance the efficiency of metal phytoextraction. Here we report on the effect of nitric acid additions to four polluted soils on Cd and Zn concentrations in soil solution (C{sub soln}) and 0.005 M Ca(NO{sub 3}){sub 2} extracts, and related changes in the diffusive fluxes and resupply of the metals as assessed by diffusive gradients in thin films (DGT). The responses of these chemical indicators of bioavailability were compared to metal uptake in two indicator plant species, common dandelion (Taraxacum officinale F.H. Wigg) and narrow leaf plantain (Plantago lanceolata L.) grown for 75 days in a pot experiment. Lowering soil pH increased C{sub soln}, the 0.005 M Ca(NO{sub 3}){sub 2}-soluble fractions and the DGT-measured Cd and Zn concentrations (C{sub DGT}) in the experimental soils. This was associated with enhanced uptake of Cd and Zn on soils acidified to pH 4.5 whereas plants did not survive at pH 3.5. Toxicity along with decreased kinetics of metal resupply (calculated by the 2D DIFS model) in the strong acidification treatment suggests that moderate acidification is more appropriate to enhance the phytoextraction process. Each of the chemical indicators of bioavailability predicted well (R{sup 2} > 0.70) the Cd and Zn concentrations in plantain shoots but due to metal toxicity not for dandelion. Concentration factors, i.e. the ratio between metal concentrations in shoots and in soil solution (CF) indicate that Cd and Zn uptake in plantain was not limited by diffusion which may explain that DGT did not perform better than C{sub soln}. However, DGT is expected to predict plant uptake better in diffusion-limited conditions such as in the rhizosphere of metal-accumulating phytoextraction crops. - Highlights: Black-Right-Pointing-Pointer The effect of soil acidification was assessed for four Zn and Cd polluted soils. Black-Right-Pointing-Pointer For some soils moderate acidification could

  17. Analysis of Factors Influencing Soil Salinity, Acidity, and Arsenic Concentration in a Polder in Southwest Bangladesh

    Science.gov (United States)

    Ayers, J. C.; Patton, B.; Fry, D. C.; Goodbred, S. L., Jr.

    2017-12-01

    Soil samples were collected on Polder 32 in the coastal zone of SW Bangladesh in wet (October) and dry (May) seasons from 2013-2017 and analyzed to characterize the problems of soil salinization and arsenic contamination and identify their causes. Soils are entisols formed from recently deposited, predominantly silt-sized sediments with low carbon concentrations typical of the local mangrove forests. Soluble (DI extract) arsenic concentrations were below the Government of Bangladesh limit of 50 ppb for drinking water. Soil acidity and extract arsenic concentrations exhibit spatial variation but no consistent trends. In October soil extract As is higher and S and pH are lower than in May. These observations suggest that wet season rainwater oxidizes pyrite, reducing soil S and releasing H+, causing pH to decrease. Released iron is oxidized to form Hydrous Ferric Oxyhydroxides (HFOs), which sorb As and increase extractable As in wet season soils. Changes in pH are small due to pH buffering by soil carbonates. Soil and rice paddy water salinities are consistently higher in May than October, reaching levels in May that reduce rice yields. Rice grown in paddies should be unaffected by salt concentrations in the wet season, while arsenic concentrations in soil may be high enough to cause unsafe As levels in produced rice.

  18. Influence of pH and temperature on alunite dissolution rates and products

    Science.gov (United States)

    Acero, Patricia; Hudson-Edwards, Karen

    2015-04-01

    Aluminium is one of the main elements in most mining-affected environments, where it may influence the mobility of other elements and play a key role on pH buffering. Moreover, high concentrations of Al can have severe effects on ecosystems and humans; Al intake, for example, has been implicated in neurological pathologies (e.g., Alzheimer's disease; Flaten, 2001). The behaviour of Al in mining-affected environments is commonly determined, at least partially, by the dissolution of Al sulphate minerals and particularly by the dissolution of alunite (KAl3(SO4)2(OH)6), which is one of the most important and ubiquitous Al sulphates in mining-affected environments (Nordstrom, 2011). The presence of alunite has been described in other acid sulphate environments, including some soils (Prietzel & Hirsch, 1998) and on the surface of Mars (Swayze et al., 2008). Despite the important role of alunite, its dissolution rates and products, and their controlling factors under conditions similar to those found in these environments, remain largely unknown. In this work, batch dissolution experiments have been carried out in order to shed light on the rates, products and controlling factors of alunite dissolution under different pH conditions (between 3 and 8) and temperatures (between 279 and 313K) similar to those encountered in natural systems. The obtained initial dissolution rates using synthetic alunite, based on the evolution of K concentrations, are between 10-9.7 and 10-10.9 mol-m-2-s-1, with the lowest rates obtained at around pH 4.8, and increases in the rates recorded with both increases and decreases in pH. Increases of temperature in the studied range also cause increases in the dissolution rates. The dissolution of alunite dissolution is incongruent, as has been reported for jarosite (isostructural with alunite) by Welch et al. (2008). Compared with the stoichiometric ratio in the bulk alunite (Al/K=3), K tends to be released to the solution preferentially over Al

  19. Influence of soil moisture content on surface albedo and soil thermal ...

    Indian Academy of Sciences (India)

    Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured ... and the influence of solar elevation angle and cloud cover are also investigated. .... ters are important factors in climate modelling and.

  20. Influence of land use on bacterial and archaeal diversity and community structures in three natural ecosystems and one agricultural soil.

    Science.gov (United States)

    Lynn, Tin Mar; Liu, Qiong; Hu, Yajun; Yuan, Hongzhao; Wu, Xiaohong; Khai, Aye Aye; Wu, Jinshui; Ge, Tida

    2017-07-01

    Studying shifts in microbial communities under different land use can help in determining the impact of land use on microbial diversity. In this study, we analyzed four different land-use types to determine their bacterial and archaeal diversity and abundance. Three natural ecosystems, that is, wetland (WL), grassland (GL), and forest (FR) soils, and one agricultural soil, that is, tea plantation (TP) soil, were investigated to determine how land use shapes bacterial and archaeal diversity. For this purpose, molecular analyses, such as quantitative polymerase chain reaction (Q-PCR), 16S rRNA gene sequencing, and terminal restriction fragment length polymorphism (T-RFLP), were used. Soil physicochemical properties were determined, and statistical analyses were performed to identify the key factors affecting microbial diversity in these soils. Phylogenetic affiliations determined using the Ribosomal Database Project (RDP) database and T-RFLP revealed that the soils had differing bacterial diversity. WL soil was rich in only Proteobacteria, whereas GR soil was rich in Proteobacteria, followed by Actinobacteria. FR soil had higher abundance of Chloroflexi species than these soils. TP soil was rich in Actinobacteria, followed by Chloroflexi, Acidobacteria, Proteobacteria, and Firmicutes. The archaeal diversity of GL and FR soils was similar in that most of their sequences were closely related to Nitrososphaerales (Thaumarchaeota phylum). In contrast, WL soil, followed by TP soil, had greater archaeal diversity than other soils. Eight different archaeal classes were found in WL soil, and Pacearchaeota class was the richest one. The abundance of bacterial and archaeal 16S rRNA gene copies in WL and GL soils was significantly higher than that in FR and TP soils. Redundancy analysis showed that bacterial diversity was influenced by abiotic factors, e.g., total organic carbon and pH, whereas total nitrogen, pH, and cation exchange capacity (CEC) significantly affected

  1. Titratable acidity of beverages influences salivary pH recovery.

    Science.gov (United States)

    Tenuta, Livia Maria Andaló; Fernández, Constanza Estefany; Brandão, Ana Carolina Siqueira; Cury, Jaime Aparecido

    2015-01-01

    A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

  2. Dynamic arsenic aging processes and their mechanisms in nine types of Chinese soils.

    Science.gov (United States)

    Wang, Yanan; Zeng, Xibai; Lu, Yahai; Bai, Lingyu; Su, Shiming; Wu, Cuixia

    2017-11-01

    Although specific soil properties controlling the arsenic (As) aging process have been studied extensively, few investigations have attempted to determine how soil types influence As bioavailability and fractionations in soils. Nine types of soil were selected from typical grain producing areas in China, and the bioavailability and fractionations of As during aging were measured. Results showed that available As in all soils rapidly decreased in the first 30 days and slowly declined thereafter. In spiked soils, As easily became less available and less toxic in low pH soils compared to high pH soils, demonstrating the importance of soil pH on As availability. Results from fitting kinetic equations revealed that the pseudo-second-order model described the As aging processes well in all soils (R 2  = 0.945-0.999, P soil clay content. The shortest time for approximate stabilization of As aging was 28 d in latosol soils (LS), while the longest approximate equilibrium time was 169 d in cinnamon soils (CS). Individual soil properties controlling the variation in different As fractionations further confirmed that the influences of soil types on As aging were the result of the combined effects of soil properties and a time-consuming redistribution process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Removal of Radium-226 from Radium-Contaminated Soil using Distilled Water and Humic Acid: Effect of pH

    International Nuclear Information System (INIS)

    Phillips, E.; Muhammad Samudi Yasir; Muhamat Omar

    2011-01-01

    Effect of washing solutions' pH removal of radium-226 from radium-contaminated soil using distilled water and humic acid extracted from Malaysian peat soil was studied by batch washing method. The study encompassed the extraction of humic acid and the washing of radium-contaminated soil using distilled water and humic acid solutions of 100 ppm, both with varying pHs in the range of 3 to 11. The radioactivity concentration of radium-226 was determined by gamma spectrometer.The removal of radium-226 was greater when humic acid solutions were used compared to distilled water at the pH range studied and both washing solutions showed greater removal of radium-226 when basic solutions were used. Nevertheless, comparable removal efficiencies were observed when neutral and highly basic humic acid solutions were used. (author)

  4. Titratable acidity of beverages influences salivary pH recovery

    Directory of Open Access Journals (Sweden)

    Livia Maria Andaló TENUTA

    2015-01-01

    Full Text Available A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively. Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

  5. CO2 leakage-induced vegetation decline is primarily driven by decreased soil O2.

    Science.gov (United States)

    Zhang, Xueyan; Ma, Xin; Zhao, Zhi; Wu, Yang; Li, Yue

    2016-04-15

    To assess the potential risks of carbon capture and storage (CCS), studies have focused on vegetation decline caused by leaking CO2. Excess soil CO2 caused by leakage can affect soil O2 concentrations and soil pH, but how these two factors affect plant development remains poorly understood. This hinders the selection of appropriate species to mitigate potential negative consequences of CCS. Through pot experiments, we simulated CO2 leakage to examine its effects on soil pH and soil O2 concentrations. We subsequently assessed how maize growth responded to these changes in soil pH and O2. Decreased soil O2 concentrations significantly reduced maize biomass, and explained 69% of the biomass variation under CO2 leakage conditions. In contrast, although leaked CO2 changed soil pH significantly (from 7.32 to 6.75), it remained within the optimum soil pH range for maize growth. This suggests that soil O2 concentration, not soil pH, influences plant growth in these conditions. Therefore, in case of potential CO2 leakage risks, hypoxia-tolerant species should be chosen to improve plant survival, growth, and yield. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Application of magnetic sorbent in the removal of cadmium from soils

    Directory of Open Access Journals (Sweden)

    Michal Lovás

    2006-12-01

    Full Text Available A contamination of soil by heavy metals is a common problem at many metalliferous mining sites. There are various treatment processes for the cleanup of soil contaminated with heavy metals. A method designed for the decontamination of soil polluted by Cd is described. The method utilizes a magnetic sorbent – sludges from the hydrometallurgic processing of nickel mineral, activated by milling. The influence of sorbent concentration, pH and microwave energy on the sorption capacity and content of Cd ions in a soil was studed. The effectiveness of Cd desorption from the soil was 75 %, the maximal sorption capacity of sorbent was 9,8 mg/g. The content of Cd in water is function of pH and the concentration of sorbent. The influence of microwave energy (90 W was negligible.

  7. Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

    Directory of Open Access Journals (Sweden)

    Davi Lopes do Carmo

    2016-01-01

    Full Text Available ABSTRACT Soil solution samplers may have the same working principle, but they differ in relation to chemical and physical characteristics, cost and handling, and these aspects exert influence on the chemical composition of the soil solution obtained. This study was carried out to evaluate, over time, the chemical composition of solutions extracted by Suolo Acqua, with the hydrophilic membrane (HM as a standard, using soils with contrasting characteristics, and to determine the relationship between electrical conductivity (EC and concentration of ions and pH of soil solution samples. This study was carried out under laboratory conditions, using three soils samples with different clay and organic matter (OM contents. Soil solution contents of F−, Cl−, NO−3, Br−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+, were analyzed, as well as inorganic, organic, and total C contents, pH, and EC, in four successive sampling times. Soil solution chemical composition extracted by the Suolo Acqua sampler is similar to that collected by the HM, but the Suolo Acqua extracted more Na+ and soluble organic C than the HM solution. Solution EC, cation and anion concentrations, and soluble C levels are higher in the soil with greater clay and OM contents (Latossolo and Cambissolo in this case. Soil solution composition varied over time, with considerable changes in pH, EC, and nutrient concentrations, especially associated with soil OM. Thus, single and isolated sampling of the soil solution must be avoided, otherwise composition of the soil solution may not be correctly evaluated. Soil solution EC was regulated by pH, as well as the sum of cation and anion concentrations, and the C contents determined in the soil liquid phase.

  8. The influence of wildfire severity on soil char composition and nitrogen dynamics

    Science.gov (United States)

    Rhoades, Charles; Fegel, Timothy; Chow, Alex; Tsai, Kuo-Pei; Norman, John, III; Kelly, Eugene

    2017-04-01

    both indicate that C contained or leached from severely-burned char layers has higher aromaticity and thus chemical stability compared to C in unburned soils. Mineral soil (0-5 cm depth) beneath char layers in high severity portions of the Hayman Fire had significantly more soil N and C and lower pH. Potential net mineralization - an index of the supply of plant-available nitrogen - differed between the severely-burned areas and both unburned and moderately-burn areas. Negative net mineralization in unburned and moderately burned soils indicates immobilization or retention of inorganic N by soil microbes. In contrast, soils burned at high severity produced inorganic N sources available to plants, leaching and gas losses. Water soluble nitrate comprised a larger proportion of inorganic N leached from the char layer of high severity burns. Mineral soil in those areas had both higher water soluble nitrate and total inorganic N in leachate. Char layers that have persisted for fifteen years influence soil N turnover within the Hayman Fire affected area and may contribute to elevated N losses in streams burned at high severity. The chemical stability of soil char layers perpetuates their importance for C sequestration and N dynamics in burned landscapes.

  9. Urbanization in China drives soil acidification of Pinus massoniana forests

    Science.gov (United States)

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-09-01

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10 cm (for ammonium N (-N), P greatly contributed to a significant soil acidification occurred in the urbanized environment.

  10. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

    Science.gov (United States)

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-01-01

    Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

  11. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils.

    Science.gov (United States)

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-06-01

    Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline-alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation.

  12. Assessment of possible solid-phase phosphate sorbents to mitigate eutrophication: Influence of pH and anoxia.

    Science.gov (United States)

    Mucci, Maíra; Maliaka, Valentini; Noyma, Natalia Pessoa; Marinho, Marcelo Manzi; Lürling, Miquel

    2018-04-01

    Managing eutrophication remains a challenge to water managers. Currently, the manipulation of biogeochemical processes (i.e., geo-engineering) by using phosphorus-adsorptive techniques has been recognized as an appropriate tool to manage the problem. The first step in finding potential mitigating materials is conducting a sequence of upscaling studies that commence with controlled laboratory experiments. Here, the abilities of 10 possible solid-phase-sorbents (SPS) to adsorb P were examined. Four materials adsorbed P, and two of these materials were modified, i.e., a lanthanum-modified-bentonite (LMB) and an aluminum-modified-zeolite (AMZ), and had the highest adsorption capacities of 11.4 and 8.9mgPg -1 , respectively. Two natural materials, a red soil (RS) and a bauxite (BAU), were less efficient with adsorption capacities of 2.9 and 3.4mgPg -1 , respectively. Elemental composition was not related to P adsorption. Since SPS might be affected by pH and redox status, we also tested these materials at pH values of 6, 7, 8 and 9 and under anoxic condition. All tested materials experienced decreased adsorption capacities under anoxic condition, with maximum adsorptions of 5.3mgPg -1 for LMB, 5.9mgPg -1 for AMZ, 0.2mgPg -1 for RS and 0.2mgPg -1 for BAU. All materials were able to adsorb P across the range of pH values that were tested. The maximum adsorption capacities of LMB and RS were highest at pH6, AMZ was higher at a pH of 9 and BAU at a pH of 8. Thus, pH influenced P adsorption differently. Given the effects of pH and anoxia, other abiotic variables should also be considered. Considering the criteria that classify a useful SPS (i.e., effective, easy to produce, cheap and safe), only the two modified materials that were tested seem to be suitable for upscaling to enclosure studies with anoxic sediments. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Adsorption of arsenate on soils. Part 2: Modeling the relationship between adsorption capacity and soil physiochemical properties using 16 Chinese soils

    International Nuclear Information System (INIS)

    Jiang Wei; Zhang, Shuzhen; Shan Xiaoquan; Feng Muhua; Zhu Yongguan; McLaren, Ron G.

    2005-01-01

    An attempt has been made to elucidate the effects of soil properties on arsenate adsorption by modeling the relationships between adsorption capacity and the properties of 16 Chinese soils. The model produced was validated against three Australian and three American soils. The results showed that nearly 93.8% of the variability in arsenate adsorption on the low-energy surface could be described by citrate-dithionite extractable Fe (Fe CD ), clay content, organic matter content (OM) and dissolved organic carbon (DOC); nearly 87.6% of the variability in arsenate adsorption on the high-energy surface could be described by Fe CD , DOC and total arsenic in soils. Fe CD exhibited the most important positive influence on arsenate adsorption. Oxalate extractable Al (Al OX ), citrate-dithionite extractable Al (Al CD ), extractable P and soil pH appeared relatively unimportant for adsorption of arsenate by soils. - Citrate-dithionite extractable Fe has the most important positive influence on arsenate adsorption on soils

  14. The effect of pH on the toxicity of zinc oxide nanoparticles to Folsomia candida in amended field soil.

    Science.gov (United States)

    Waalewijn-Kool, Pauline L; Ortiz, Maria Diez; Lofts, Stephen; van Gestel, Cornelis A M

    2013-10-01

    The effect of soil pH on the toxicity of 30 nm ZnO to Folsomia candida was assessed in Dorset field soils with pHCaCl2 adjusted to 4.31, 5.71, and 6.39. To unravel the contribution of particle size and dissolved Zn, 200 nm ZnO and ZnCl2 were tested. Zinc sorption increased with increasing pH, and Freundlich kf values ranged from 98.9 (L/kg)(1/n) to 333 (L/kg)(1/n) for 30 nm ZnO and from 64.3 (L/kg)(1/n) to 187 (L/kg)(1/n) for ZnCl2. No effect of particle size was found on sorption, and little difference was found in toxicity between 30 nm and 200 nm ZnO. The effect on reproduction decreased with increasing pH for all Zn forms, with 28-d median effective concentrations (EC50s) of 553 mg Zn/kg, 1481 mg Zn/kg, and 3233 mg Zn/kg for 30 nm ZnO and 331 mg Zn/kg, 732 mg Zn/kg, and 1174 mg Zn/kg for ZnCl2 at pH 4.31, 5.71, and 6.39, respectively. The EC50s based on porewater Zn concentrations increased with increasing pH for 30 nm ZnO from 4.77 mg Zn/L to 18.5 mg Zn/L, while for ZnCl2 no consistent pH-related trend in EC50s was found (21.0-63.3 mg Zn/L). Porewater calcium levels were 10 times higher in ZnCl2 -spiked soils than in ZnO-spiked soils. The authors' results suggest that the decreased toxicity of ZnCl2 compared with 30 nm ZnO based on porewater concentrations was because of a protective effect of calcium and not a particle effect. © 2013 SETAC.

  15. The gamma dose assessment and pH correlation for various soil types at Batu Pahat and Kluang districts, Johor, Malaysia

    Science.gov (United States)

    Johar, Saffuwan Mohamed; Embong, Zaidi; Tajudin, Saiful Azhar Ahmad

    2016-01-01

    An assessment of absorbed dose and radiation hazard index as well as its relationship with soil pH was performed in this study. The area was chosen due to its variety of soil types from the Alluvial and the Sedentary group. The radioactivity concentration levels and the soil acidity were measured using the Canberra GC3518 high pure germanium with a relative efficiency of 35% at 1.3 MeV and the Takemura Soil pH and Moisture Tester (DM15), respectively. Overall results show the Holyrood-Lunas soil of Alluvial group recorded the highest external terrestrial gamma radiation dose rate (TGRD) of 286.4±37.9 nGy h-1 and radioactivity concentrations of 78.1±8.9 Bq kg-1 (226Ra), 410.5±55.4 Bq kg-1 (232Th) and 56.4±8.8 Bq kg-1 (40K), respectively, while the Peat soil of Alluvial group recorded the lowest TGRD of 4.4±2.7 nGy h-1 and radioactivity concentrations of 4.8±1.7 Bq kg-1 (226Ra), 3.1±1.1 Bq kg-1 (232Th) and 6.1±2.0 Bq kg-1 (40K), respectively. The estimated mean outdoor annual effective dose, the mean radium equivalent activity (Req) and the mean external (Hext) and internal hazard index (Hint) associated with the alluvial and sedentary soil group were evaluated at 0.15 and 0.20 mSv, 280 and 364 Bq kg-1, Hext = 0.78 and 1.01, and Hint = 0.93 and 1.26, respectively. Correlation analysis between 238U, 232Th and 40K with soil pH level for alluvial group was r = +0.68, +0.48 and 0, respectively, while for sedentary soil, the Pearson's, r = -0.30, -0.90 and +0.14, respectively.

  16. The influence of pH on the adsorption of lead by Na-clinoptilolite ...

    African Journals Online (AJOL)

    The influence of pH on the adsorption of lead by Na-clinoptilolite: Kinetic and equilibrium studies. ... At high pH of the contact solution, the adsorption process occurs by ion exchange and at low pH; i.e., it is physical. The variation of the Gibbs free energy demonstrates that adsorption occurs spontaneously. The process was ...

  17. The influence of rice husk and tobacco waste biochars on soil quality

    Directory of Open Access Journals (Sweden)

    Amir Hamzah

    2017-10-01

    Full Text Available Heavy metal pollution in agricultural land threatens soil and food quality. Soil pollution could be remediate using biochar, but the effectiveness of biochar on soil quality improvement is determined by types of feedstock and pyrolysis temperature. This study was aimed to explore the effect of different types of biochar on soil properties.  Biochar from rice husk and tobacco waste was applied to soil contaminated with lead and mercury. This study was conducted at Sumber Brantas, Malang East Java, and used a completely randomized design with three replicates. Heavy metals content was measured using AAS. The results of measurements were analyzed using analysis of variance at 5% and 1% significance levels. The initial analysis of the soil properties at the research site showed that the soil nutrient status was low, i.e. N (0.2 %, K (0.50 cmol+/kg, and CEC (5.9 me/100g respectively, but soil pH was neutral (6.8. The research site also has crossed the threshold of heavy metal content for Hg (0.5 ppm, Pb (25.22 ppm, Cd (1.96 ppm, and As (0.78 ppm. Biochar added had a positive influence on soil characteristics improvement. It could increase the content of organic C, i.e. 35.12% and 31.81% and CEC (cation exchange capacity, i.e.30.56 me/100g and 28.13 me/100 g for rice husk biochar and tobacco waste biochar, respectively.  However, N, P, and K contents were low i.e. N ( 0.33 and 0.30 %; P2O5 (148.79 and 152 ppm; K (1.58 and 2.11 mg/100g for rice husk biochar and tobacco waste biochar, respectively.

  18. Soil pH in fruit trees in relation to specific replant disorder of apple. I. Introduction and review of literature

    NARCIS (Netherlands)

    Jonkers, H.; Hoestra, H.

    1978-01-01

    A low pH of the soil prevents the specific apple replant disorder (SARD). Not much is known about the effect of a low pH on the growth of fruit trees. Most authors accept a pH of between 5.5 and 6.5 as optimum for apples but this assumption is not based on experimental research. It is feasible that

  19. Low pH, Aluminum, and Phosphorus Coordinately Regulate Malate Exudation through GmALMT1 to Improve Soybean Adaptation to Acid Soils1[W][OA

    Science.gov (United States)

    Liang, Cuiyue; Piñeros, Miguel A.; Tian, Jiang; Yao, Zhufang; Sun, Lili; Liu, Jiping; Shaff, Jon; Coluccio, Alison; Kochian, Leon V.; Liao, Hong

    2013-01-01

    Low pH, aluminum (Al) toxicity, and low phosphorus (P) often coexist and are heterogeneously distributed in acid soils. To date, the underlying mechanisms of crop adaptation to these multiple factors on acid soils remain poorly understood. In this study, we found that P addition to acid soils could stimulate Al tolerance, especially for the P-efficient genotype HN89. Subsequent hydroponic studies demonstrated that solution pH, Al, and P levels coordinately altered soybean (Glycine max) root growth and malate exudation. Interestingly, HN89 released more malate under conditions mimicking acid soils (low pH, +P, and +Al), suggesting that root malate exudation might be critical for soybean adaptation to both Al toxicity and P deficiency on acid soils. GmALMT1, a soybean malate transporter gene, was cloned from the Al-treated root tips of HN89. Like root malate exudation, GmALMT1 expression was also pH dependent, being suppressed by low pH but enhanced by Al plus P addition in roots of HN89. Quantitative real-time PCR, transient expression of a GmALMT1-yellow fluorescent protein chimera in Arabidopsis protoplasts, and electrophysiological analysis of Xenopus laevis oocytes expressing GmALMT1 demonstrated that GmALMT1 encodes a root cell plasma membrane transporter that mediates malate efflux in an extracellular pH-dependent and Al-independent manner. Overexpression of GmALMT1 in transgenic Arabidopsis, as well as overexpression and knockdown of GmALMT1 in transgenic soybean hairy roots, indicated that GmALMT1-mediated root malate efflux does underlie soybean Al tolerance. Taken together, our results suggest that malate exudation is an important component of soybean adaptation to acid soils and is coordinately regulated by three factors, pH, Al, and P, through the regulation of GmALMT1 expression and GmALMT1 function. PMID:23341359

  20. Dynamics of pH, Ferrum and Mangan, and Phosphorus on Newly Opened Paddy Soil having High Soil Organic Matter on Rice Growth

    Directory of Open Access Journals (Sweden)

    Sukristyonubowo

    2012-01-01

    Full Text Available Research had been carried out at the Research and Soil Testing Laboratory and Greenhouse of Soil ResearchInstitute, Bogor using newly opened paddy soil from Pesisir Selatan districts, West Sumatra (one year old. Totaltreatments tested were 12 which were combination of farmer rate, NPK recommendation (½×; ¾×; 1½×, strawcompost (½×; ¾×; 1½×, and dolomite. The trial was conducted using a completely randomized design with threereplications. This research had been prepared in two units, one unit for observing plant response to nutrientmanagement and another unit for incubation trial with the same treatment placed in the greenhouse. Rice cultivarused was IR-42 in accordance to the preferred varieties of local farmers. The sampling method for measuring thesolubility of Fe2+ and Mn2+, as well as the availability of PO43- was by centrifuge 50 g mud samples from theincubation pots then separated clear extract using filter paper. The observation results on dynamics of pH, Fe2+,Mn2+ and PO4-3 mainly occured in 1 to 14 days after submerging (incubation. After 14 days soil reaction had reachedthermodynamic sequence of oxidation-reduction processes, the PO43- more available and pH of the soil reached thepeak. The optimum dose of NPK fertilizer obtained 0.875 NPK or equal to 175 kg of urea, 87.5 kg of SP-36 and 87.5 kgKCl ha-1. The highest number of hills achieved from straw compost treatment 1½ organic matter (OM or 3 tons withan increase of 20%. Application of ameliorant dolomite increased the number of tillers about 2-3%, but insignificantlydifferent with no dolomite treatment.

  1. Experimental Investigation of Phenanthrene Pollutant Removal Efficiency for Contaminated Sandy Soil by Enhanced Soil Washing

    Directory of Open Access Journals (Sweden)

    Saif salah Alquzweeni

    2016-12-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs are environmental concerns that must be removed to acceptable level. This research assesses two agents (Na2EDTA and SDS to remediate contaminated sandy soil, spiked with 500mg/kg phenanthrene. Five sets of experiments (batch are applied to investigate the optimal of five influencing factors on soil remediation: Na2EDTA-SDS concentration, liquid/Solid ratio, stirring speed, pH value of flushing solution and mixing time. The results of batch experiments showed that SDS has high phenanthrene removal efficiency (90%, while Na2EDTA shows no phenanthrene removal. pH has no effect on phenanthrene removal. To study the influence of flow rates on the removal efficiency of contaminants, two column tests with hydraulic gradient of 0.2 and 1.2 conducted by SDS solution. The results illustrate that high phenanthrene removal from soil obtained by 1.2 hydraulic gradient condition. The SDS flushing solution removed approximately 69% and 81% of phenanthrene from soil under low and high hydraulic gradients, respectively. It was concluded that phenanthrene removal depend on surfactant micelles formation. Overall, the study showed that soil flushing removal efficiency for contaminants depends on the flushing agents selectivity and affinity to the contaminants and the condition of hydraulic gradient.

  2. Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

    Science.gov (United States)

    Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

    2014-05-01

    The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

  3. Effect of elevated Al and pH on the growth and root morphology of Al-tolerant and Al-sensitive wheat seedlings in an acid soil

    Directory of Open Access Journals (Sweden)

    Md. Toufiq Iqbal

    2014-03-01

    Full Text Available Aluminium ion (Al3+ toxicity and hydrogen ion (H+ activity are the major constraints for plant growth in acid soil. This study was undertaken to determine the effect of pH and Al on the growth response and changes in root morphology of Al-tolerant (ET8 and Al-sensitive (ES8 wheat seedlings. Different levels of AlCl3 and CaCO3 were added to the soils to manipulate soil pH and extractable Al. The results showed that the bulk soil pH remained constant at pH 4.1 with further applications of AlCl3, and that the seedlings died at the 200 mg AlCl3/kg treatments. The ET8 seedlings responded better than the ES8 seedlings in both low and high Al and pH. The ET8 seedlings had higher root surface areas and root tip numbers than the ES8 seedlings in the Al treatment. In contrast, the ES8 had higher root diameters than the ET8 seedlings due to the elevated Al supply. Apoplast Al increased with the increase of soil available extractable Al, and declined with the decrease of soil extractable Al. The ET8 seedlings accumulated more Al in their apoplast than the ES8 seedlings. This study concluded that accumulation of Al in the apoplast is also involved in Al tolerance mechanism with the addition of organic acid exudation.

  4. Influence of long-term land use (arable and forest) and soil mineralogy on organic carbon stocks as well as composition and stability of soil organic matter

    Science.gov (United States)

    Kaiser, M.; Ellerbrock, R. H.; Wulf, M.; Dultz, S.; Hierath, C.; Sommer, M.

    2009-04-01

    The function of soils to sequester organic carbon (OC) and their related potential to mitigate the greenhouse effect is strongly affected by land use and soil mineralogy. This study is aimed to clarify long-term impacts of arable and forest land use as well as soil mineralogy on topsoil soil organic carbon (SOC) stocks as well as soil organic matter (SOM) composition and stability. Topsoil samples were taken from deciduous forest and adjacent arable sites (within Germany) that are continuously used for more than 100 years. The soils are different in genesis (Albic and Haplic Luvisol (AL, HL), Colluvic and Haplic Regosol (CR, HR), Haplic and Vertic Cambisol (HC, VC), Haplic Stagnosol (HSt)). First, particulate and water soluble organic matter were separated from the topsoil samples (Ap and Ah horizons). From the remaining solid extraction residues the Na-pyrophosphate soluble organic matter fractions (OM(PY)) were extracted, analysed for its OC content (OC(PY)) and characterized by FTIR spectroscopy and 14C analyses. The SOC stocks calculated for 0-40 cm depth are in general larger for the forest as compared to the adjacent arable soils (except VC). The largest difference between forest and arable topsoils was detected for the HR site (5.9 kg m-2) and seemed to be caused by a two times larger stock of exchangeable Ca of the forest topsoil. For the arable topsoils multiple regression analyses indicate a strong influence of clay, oxalate soluble Al and pyrophosphate soluble Mg on the content of OC(PY) weighted with its C=O content. Such relation is not found for the forest topsoils. Further, a positive relation between Δ14C values of OM(PY) and the following independent variables: (i) specific mineral surface area, (ii) relative C=O group content in OM(PY) and (iii) soil pH is found for the arable topsoils (pH 6.7 - 7.5) suggesting an increase in OM(PY) stability with increasing interactions between OM(PY) and soil mineral surfaces via cation bridging. A similar

  5. Influence of fuelwood trees on sodic soils

    International Nuclear Information System (INIS)

    Garg, V.K.; Jain, R.K.

    1992-01-01

    The persistent acute fuelwood shortage problem in India has necessitated having tree plantations on waste lands to obtain renewable energy. Fuelwood production screening trials initiated in 1981 at the Biomass Research Centre in Banthra, India identified babul, Acacia nilotica (L.) Wild. ex Delile, and mesquite, Prosopis juliflora (Swartz) DC., to be the most promising and suitable leguminous trees in terms of biomass production on sodic sites. A study was carried out to assess soil enrichment due to the growth of these fuelwood trees planted a decade past on sordic soil that had had no other amendments. Results showed preferential nutrient accumulation and greater reduction in soil pH (from 9.5 to 7.9) and exchangeable sodium (from 30 to 8%) at the P. juliflora plantation compared with at the A. nilotica plantation. There was also a reduction in surface soil (0-15 cm) bulk density, but an enhancement in porosity and water holding capacity, making soil more friable. The P. juliflora plantation produced markedly more leaf litter than the A. nilotica plantation. Both the species had fibrous lateral root systems on the surface in the sodic soil. However, the penetration and spread of roots were almost 2-fold greater in P. juliflora than in A. nilotica. Thus, the potential magnitude of changes in soil properties was related to the distribution of roots and amount of litter falling on the soil surface. Prosopis juliflora appeared to be better than A. nilotica under adverse sodic soil conditions in establishing an enlarged plant-litter nutrient cycle relationship. This study also provides an assessment of soil amelioration by leguminous trees under short-rotation forestry practices. 16 refs., 7 figs., 4 tabs

  6. Influence of fuelwood trees on sodic soils

    Energy Technology Data Exchange (ETDEWEB)

    Garg, V.K.; Jain, R.K. (National Botanical Research Inst., Lucknow (India))

    1992-01-01

    The persistent acute fuelwood shortage problem in India has necessitated having tree plantations on waste lands to obtain renewable energy. Fuelwood production screening trials initiated in 1981 at the Biomass Research Centre in Banthra, India identified babul, Acacia nilotica (L.) Wild. ex Delile, and mesquite, Prosopis juliflora (Swartz) DC., to be the most promising and suitable leguminous trees in terms of biomass production on sodic sites. A study was carried out to assess soil enrichment due to the growth of these fuelwood trees planted a decade past on sordic soil that had had no other amendments. Results showed preferential nutrient accumulation and greater reduction in soil pH (from 9.5 to 7.9) and exchangeable sodium (from 30 to 8%) at the P. juliflora plantation compared with at the A. nilotica plantation. There was also a reduction in surface soil (0-15 cm) bulk density, but an enhancement in porosity and water holding capacity, making soil more friable. The P. juliflora plantation produced markedly more leaf litter than the A. nilotica plantation. Both the species had fibrous lateral root systems on the surface in the sodic soil. However, the penetration and spread of roots were almost 2-fold greater in P. juliflora than in A. nilotica. Thus, the potential magnitude of changes in soil properties was related to the distribution of roots and amount of litter falling on the soil surface. Prosopis juliflora appeared to be better than A. nilotica under adverse sodic soil conditions in establishing an enlarged plant-litter nutrient cycle relationship. This study also provides an assessment of soil amelioration by leguminous trees under short-rotation forestry practices. 16 refs., 7 figs., 4 tabs.

  7. Filamentous soil fungi comunities on Kiphakiphani agroesosistems, Choquenaira-Viacha Municipaly

    Directory of Open Access Journals (Sweden)

    Pacasa-Quisbert Fernando

    2017-08-01

    Full Text Available Soil fungi play important roles in ecosystems and these populations are closely related to soil type, climatic characteristics, other microorganisms and plant communities. People’s activities, mainly agriculture alter their habitat and therefore affect fungi diversity and functions on soil. The effects of soil use type (TUS, native vegetation type (TVN and crop type (TC on colony forming units (CFU, number of spe-cies and physical, chemical and biological parameters was assessments in the present work in Plurination-al State of Bolivian´s highland agroecosystem. In addition, the diversity and number of filamentous fungi were related to physical and chemical soil parameters (pH, texture, organic matter, The fungi were de-scribed macro- and microscopically and were taxonomically identified. The TUS, TVN and TC influenced differently on the pH, soil texture and soil organic matter (SOM. The TUS and TC significantly affected the CFU´s and number of species. CFU´s were high in crop potato and number of species in Trifolium sp., 44 species were isolated, predominating genera of Penicillium and Alternaria. The rela-tionships between SOM were non-significant and weak (r2 = 32.1, p> 0.05, pH, significant and strong positive relation (r2 = 47.7, p 0.05. The results suggest that the soil use type affect in soil properties, plant diversity and community fungi. Additionally, it is necessary to investigate other parameters that influence the microbial community in the agroecosystem.

  8. Modelling the soil nitrogen denitrification

    International Nuclear Information System (INIS)

    Budoi, G.H.; Danuso, F.; Giovanardi, R.; Gavriluta, A.; Alexandrescu, A.; Bireescu, L.

    1999-01-01

    The paper presents the differential equations used to compute the daily amounts of N denitrified and to compute the amount of N denitrified in a given period of time. It shows also the equations which compute the correction factors of the maximum denitrification rate as a function of soil temperature (F td ), moisture (F md ) and pH (F pHd ), original equations used by NICROS - nitrogen crop simulation model to describe the influence of these abiotic factors. The temperature factor, F td . The optimum temperature for denitrification is between 25-37 o C. The process is slow at temperatures below 10 o C, there is an increased inhibition below 5 o C and stop completely at 0 o C. The maximum temperature for denitrification is practically that which limits the soil microbiological activity, generally 75 o C. The following relations are used to compute the F td factor: F td 1/(1 + e -0,3347 tmed+ 4,99 ) if t med ≤ 37; F td = 1 - (t med - 37)/38 if 75 > t med > 37; F td = 0 if t med ≥ 75, where t med is the average daily soil temperature. The moisture factor, F md . The denitrification has maximum intensity at soil water saturation, U sat , and stop below 80 % from U sat . F md = 0 if soil moisture U s ≤ 0,8*U sat , and F md = (U s - 0,8*U sat )/(U sat - 0,8*U sat ) if U s > 0,8*U sat . The pH factor, F pHd . Denitrification takes place at pH between 4-9 and is maximum at pH between 7-8. The relations used to compute the F pHd factor are: F pHd = 1/(1 + e -3,1923 pH + 18,87 ) if pH ≤ 8; F pHd = (9 - pH) when pH is between 8-9, and F pHd = 0 if pH > 9. Refs. 6 (author)

  9. Influence of bacteria on Pb and Zn speciation, mobility and bioavailability in soil: A laboratory study

    International Nuclear Information System (INIS)

    Wu, S.C.; Luo, Y.M.; Cheung, K.C.; Wong, M.H.

    2006-01-01

    A soil column experiment was carried out to investigate the effects of inoculation of bacteria on metal bioavailability, mobility and potential leachability through single chemical extraction, consequential extraction and in situ soil solution extraction technologies. Results showed that bacteria inoculated, including Azotobacter chroococcum, Bacillus megaterium and Bacillus mucilaginosus, may pose both positive and negative impacts on bioavailability and mobility of heavy metals in soil, depending on the chemical nature of the metals. The activities of bacteria led to an increase of water dissolved organic carbon (DOC) concentration and a decrease of pH value, which enhanced metal mobility and bioavailability (e.g. an increase of water-soluble and HOAc-soluble Zn). On the other hand, bacteria could immobilize metals (e.g. a great reduction of water-soluble Pb) due to the adsorption by bacterial cell walls and possible sedimentation reactions with phosphate or other anions produced through bacterial metabolism. - Influence of bacterial activities on heavy metal is two-edged

  10. A preliminary evaluation of some soil and plant parameters that influence root uptake of arsenic, cadmium, cooper, and zinc

    International Nuclear Information System (INIS)

    Hattemer-Frey, H.A.; Krieger, G.R.; Lau, V.

    1994-01-01

    In the absence of site-specific data, the concentration of metals in plants is typically estimated by multiplying the total concentration of metal in soil by a metal-specific soil-to-root bioconcentration factor (BCF). However, this approach does not account for various soil properties, such as pH, organic matter content, and cation exchange capacity, that are known to influence root uptake of some metals. For risk assessment purposes, a simple, predictive method for estimating root uptake of metals that is based on site-specific soil and crop data is needed so that the importance of the produce ingestion pathway and subsequent influence on human exposure can be quantitatively assessed. An easy-to-use method is necessary since collecting site-specific data on the concentration of metals in home-grown produce is often time-consuming and costly. Ideally, it should be possible to develop a statistically-reliable relationship between plant and soil metals levels that includes appropriate weighing factors for various soil properties. Multiple linear regression analyses were used to develop simple, predictive models for estimating the concentration of metals in plants via root uptake using site-specific soil data. This paper presents preliminary predictive equations for estimating root uptake of arsenic, cadmium, copper, and zinc in fruiting, root, and all vegetables combined (i.e., fruiting and root crop data were combined). Results show that by using data on additional soil parameters (other than relying solely on the concentration of metals in soil), the concentration of metals in fruiting and root vegetables can be more confidently predicted

  11. Influence of sulphur and multi-component fertilizer application on the content of Cu, Zn and Mn in different types of soil under maize

    Directory of Open Access Journals (Sweden)

    Barbara MURAWSKA

    2017-09-01

    Full Text Available The aim of the study was to determine the influence of the soil type and differential sulphur rates used with or without Basfoliar 36 Extra on the soil pH as well as the amount of available forms of copper, zinc and manganese based on the micro plots field experiment. Moreover, the relationship between the studied microelements was examined. The experiment was performed in two-factor design; the first-order factor was the soil type (Typic Hapludolls, Typic Hapludalfs, Typic Haplorthods, Typic Endoaquolls, while the second-order factor - fertilization with sulphur and compound fertilizer - Basfoliar 36 Extra. The plant tested was Rota cultivar maize. The use of sulphur and sulphur combined with Basfoliar 36 Extra changed the classification of the soils in terms of their pH. In the soils under study, as a result of the 10-years application of sulphur and/or foliar fertiliser with NPK fertilization as well as growing maize in monoculture showing a high uptake of macro- and micro-nutrients, there was reported a clear decrease in the content of zinc, copper and manganese, as compared with the initial content. With that in mind, one shall assume that growing maize in a 10-year monoculture is connected with an intensive use of soils, which can result in a clear deficit of the elements studied in soil.

  12. Influence of environmental variables on the structure and composition of soil bacterial communities in natural and constructed wetlands.

    Science.gov (United States)

    Arroyo, Paula; Sáenz de Miera, Luis E; Ansola, Gemma

    2015-02-15

    Bacteria are key players in wetland ecosystems, however many essential aspects regarding the ecology of wetland bacterial communities remain unknown. The present study characterizes soil bacterial communities from natural and constructed wetlands through the pyrosequencing of 16S rDNA genes in order to evaluate the influence of wetland variables on bacterial community composition and structure. The results show that the composition of soil bacterial communities was significantly associated with the wetland type (natural or constructed wetland), the type of environment (lagoon, Typha or Salix) and three continuous parameters (SOM, COD and TKN). However, no clear associations were observed with soil pH. Bacterial diversity values were significantly lower in the constructed wetland with the highest inlet nutrient concentrations. The abundances of particular metabolic groups were also related to wetland characteristics. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Glyphosate behavior at soil and mineral-water interfaces

    International Nuclear Information System (INIS)

    Pessagno, Romina C.; Torres Sanchez, Rosa M.; Santos Afonso, Maria dos

    2008-01-01

    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. - Adsorption isotherms, surface coverage and zeta potential curves of glyphosate in aqueous suspensions of montmorillonite and three Argentine soils were measured as a function of PMG concentration and pH

  14. Glyphosate behavior at soil and mineral-water interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pessagno, Romina C. [INQUIMAE and Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellon II, (C1428EHA) Buenos Aires (Argentina)], E-mail: rpessagno@qi.fcen.uba.ar; Torres Sanchez, Rosa M. [CETMIC, CC 49, (B1896ZCA) M.B. Gonnet, Buenos Aires Province (Argentina)], E-mail: rosats@cetmic.unlp.edu.ar; Santos Afonso, Maria dos [INQUIMAE and Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellon II, (C1428EHA) Buenos Aires (Argentina)], E-mail: dosantos@qi.fcen.uba.ar

    2008-05-15

    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. - Adsorption isotherms, surface coverage and zeta potential curves of glyphosate in aqueous suspensions of montmorillonite and three Argentine soils were measured as a function of PMG concentration and pH.

  15. Copper concentration of vineyard soils as a function of pH variation and addition of poultry litter

    Directory of Open Access Journals (Sweden)

    Gilmar Ribeiro Nachtigall

    2007-11-01

    Full Text Available Copper (Cu concentration was evaluated as a function of pH variation and addition of poultry litter to a Dystrophic Lithic Udorthent and a Humic Dystrudept from the state of Rio Grande do Sul, Brazil, cultivated with vines treated with successive applications of Cu-based product. Samples were collected from the surface layer (0 to 10 cm. Soluble Cu concentration was determined using DTPA and Mehlich III as extractants, and exchangeable Cu was determined in CaCl2. The availability of Cu was mainly affected by the soil pH. CaCl2 extractant had the best correlation with Cu concentration in contaminated soils, according to treatments applied. The addition of poultry litter did not reduce Cu availability in these soils. Total soil Cu content varied between 1,300 and 1,400 mg kg-1 in both soils. Copper available fractions, extracted by DTPA, CaCl2 and Mehlich III, averaged 35, 0.2 and 63%, respectively, of the total Cu present in the soil.Avaliaram-se os teores de Cu em função da variação do pH e da adição de cama-de-frango de dois solos com elevados teores deste elemento. Foram coletadas amostras da camada superficial (0 a 10 cm de um typical dystrophic Lithic Udorthent - LU (Neossolo Litólico distrófico típico e de um Humic Dystrudept - HD (Cambissolo Húmico alumínico típico da região da Serra do RS, cultivados com parreirais que receberam aplicações sucessivas de produtos à base de Cu. Foram determinados os teores de Cu solúvel em DTPA e pelo método Mehlich III, além do Cu trocável em CaCl2. A disponibilidade de Cu foi afetada principalmente pelo pH do solo. O extrator CaCl2 foi o que melhor se correlacionou com os teores de Cu em solos contaminados em função dos tratamentos aplicados. A adição de cama-de-frango não diminuiu a disponibilidade de Cu destes solos. Os teores de Cu total variaram entre 1.300 e 1.400 mg kg-1 nos dois solos. Considerando os teores totais de Cu nos solos, as frações "disponíveis", extra

  16. Metals in European roadside soils and soil solution – A review

    International Nuclear Information System (INIS)

    Werkenthin, Moritz; Kluge, Björn; Wessolek, Gerd

    2014-01-01

    This review provides a summary of studies analysing metal concentrations in soils and soil solution at European roadsides. The data collected during 27 studies covering a total of 64 sites across a number of European countries were summarised. Highest median values of Cr, Cu, Ni, Pb, and Zn were determined in the top soil layer at the first 5 m beside the road. Generally, the influence of traffic on soil contamination decreased with increasing soil depth and distance to the road. The concentration patterns of metals in soil solution were independent from concentrations in the soil matrix. At 10-m distance, elevated soil metal concentrations, low pH, and low percolation rates led to high solute concentrations. Directly beside the road, high percolation rates lead to high annual loadings although solute concentrations are comparatively low. These loadings might be problematic, especially in regions with acidic sandy soils and a high groundwater table. - Highlights: • Summary of studies analysing metals in soils and soil solution at European roadsides. • Metal concentrations in topsoil 5 m beside the road are influenced strongly by traffic. • Solute concentrations of metals are mostly independent from soil concentrations. • High percolation rates lead to high annual loadings directly beside the road. - Summarised data showed typical distance related metal patterns of European roadside soils; solute concentrations are mostly independent from soil matrix concentrations

  17. [Influence of the earthworm Lumbricus terrestris on soil solution complexation capacity].

    Science.gov (United States)

    el Gharmali, A; Rada, A; el Meray, M; Nejmeddine, A

    2001-04-01

    Four soil samples highly contaminated with metals of urban and mine origin (SE1, SE2, SM1, SM2) and having different physico-chemical proprieties were selected to study copper complexation capacity (LT) of soil solution. The effect of Lumbricus terrestris on copper complexation capacity of soil solution was investigated on SE1 and SE2. The complexation capacity was estimated by amperometric titration of soil solution by copper. Free hydrated cation and labile complexes of copper were determined by DPASV. The results show that the copper complexation capacity variation depends on the physico-chemical characteristics of soils, particularly pH. Thus, the values of copper complexation capacity are 0; 0.6 x 10(-7); 1.8 x 10(-7) and 5.5 x 10(-7) mol l-1 respectively for SM2; SM1; SE1 and SE2 which are pH 5; 5.4; 6.5 and 7.4. Based on these results, the bioavailability levels of heavy metals show the following pool ranking: SM2 > SM1 > SE1 > SE2. The copper complexation capacity of soil solution increases with the soil disturbance by Lumbricus terrestris. This is more obvious when the time of disturbance by lumbrics is longer. Indeed, average values determined for 1 month and 3 months are 3.8 x 10(-7) and 7.8 x 10(-7) mol l-1 for SE1; 7.7 x 10(-7) and 15.2 x 10(-7) mol l-1 for SE2 respectively. It seems that the action of earthworm on soil can contribute to the decrease of bioavailability of heavy metals, particularly copper.

  18. Metals in European roadside soils and soil solution--a review.

    Science.gov (United States)

    Werkenthin, Moritz; Kluge, Björn; Wessolek, Gerd

    2014-06-01

    This review provides a summary of studies analysing metal concentrations in soils and soil solution at European roadsides. The data collected during 27 studies covering a total of 64 sites across a number of European countries were summarised. Highest median values of Cr, Cu, Ni, Pb, and Zn were determined in the top soil layer at the first 5 m beside the road. Generally, the influence of traffic on soil contamination decreased with increasing soil depth and distance to the road. The concentration patterns of metals in soil solution were independent from concentrations in the soil matrix. At 10-m distance, elevated soil metal concentrations, low pH, and low percolation rates led to high solute concentrations. Directly beside the road, high percolation rates lead to high annual loadings although solute concentrations are comparatively low. These loadings might be problematic, especially in regions with acidic sandy soils and a high groundwater table. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Sorption of perfluoroalkyl substances (PFASs) to an organic soil horizon - Effect of cation composition and pH.

    Science.gov (United States)

    Campos Pereira, Hugo; Ullberg, Malin; Kleja, Dan Berggren; Gustafsson, Jon Petter; Ahrens, Lutz

    2018-09-01

    Accurate prediction of the sorption of perfluoroalkyl substances (PFASs) in soils is essential for environmental risk assessment. We investigated the effect of solution pH and calculated soil organic matter (SOM) net charge on the sorption of 14 PFASs onto an organic soil as a function of pH and added concentrations of Al 3+ , Ca 2+ and Na + . Often, the organic C-normalized partitioning coefficients (K OC ) showed a negative relationship to both pH (Δlog K OC /ΔpH = -0.32 ± 0.11 log units) and the SOM bulk net negative charge (Δlog K OC  = -1.41 ± 0.40 per log unit mol c g -1 ). Moreover, perfluorosulfonic acids (PFSAs) sorbed more strongly than perfluorocarboxylic acids (PFCAs) and the PFAS sorption increased with increasing perfluorocarbon chain length with 0.60 and 0.83 log K OC units per CF 2 moiety for C 3 -C 10 PFCAs and C 4 , C 6 , and C 8 PFSAs, respectively. The effects of cation treatment and SOM bulk net charge were evident for many PFASs with low to moderate sorption (C 5 -C 8 PFCAs and C 6 PFSA). However for the most strongly sorbing and most long-chained PFASs (C 9 -C 11 and C 13 PFCAs, C 8 PFSA and perfluorooctane sulfonamide (FOSA)), smaller effects of cations were seen, and instead sorption was more strongly related to the pH value. This suggests that the most long-chained PFASs, similar to other hydrophobic organic compounds, are preferentially sorbed to the highly condensed domains of the humin fraction, while shorter-chained PFASs are bound to a larger extent to humic and fulvic acid, where cation effects are significant. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. A review of metal (Pb and Zn) sensitive and pH tolerant bioassay organisms for risk screening of metal-contaminated acidic soils

    International Nuclear Information System (INIS)

    Chapman, E.Emily V.; Dave, Göran; Murimboh, John D.

    2013-01-01

    To improve risk estimates at the screening stage of Ecological Risk Assessment (ERA), short duration bioassays tailored to undisturbed soil cores from the contaminated site could be useful. However, existing standardized bioassays use disturbed soil samples and often pH sensitive organisms. This is a problem as naturally acidic soils are widespread. Changing soil properties to suit the test organism may change metal bioavailability, leading to erroneous risk estimates. For bioassays in undisturbed soil cores to be effective, species able to withstand natural soil properties must be identified. This review presents a critical examination of bioassay species' tolerance of acidic soils and sensitivity to metal contaminants such as Pb and Zn. Promising organisms include; Dendrobaena octaedra, Folsomia candida, Caenorhabditis elegans, Oppia nitens, Brassica rapa, Trifolium pratense, Allium cepa, Quercus rubra and Acer rubrum. The MetSTICK test and the Bait lamina test were also identified as suitable microorganism tests. -- Highlights: •Risk screening of metal contaminated soils should consider metal bioavailability. •Metal bioavailability is dependent on soil properties such as pH. •Many standardized bioassay organisms are sensitive to acidic soils. •This review identifies acid tolerant and metal sensitive bioassays and species. •The identified tests can improve risk screening of acidic metal contaminated soil. -- This review identifies bioassay species able to withstand naturally acidic soils while being sensitive to metal contaminants

  1. Analysis of Seasonal Soil Organic Carbon Content at Bukit Jeriau Forest, Fraser Hill, Pahang

    International Nuclear Information System (INIS)

    Ahmad Adnan Mohamed; Ahmad Adnan Mohamed; Sahibin Abd Rahim; David Allan Aitman; Mohd Khairul Amri Kamarudin; Mohd Khairul Amri Kamarudin

    2016-01-01

    Soil carbon is the carbon held within the soil, primarily in association with its organic content. The total soil organic carbon study was determined in a plot at Bukit Jeriau forest in Bukit Fraser, Pahang, Malaysia. The aim of this study is to determine the changing of soil organic carbon between wet season and dry season. Soil organic carbon was fined out using titrimetric determination. The soil organic carbon content in wet season is 223.24 t/ ha while dry season is 217.90 t/ ha. The soil pH range in wet season is between 4.32 to 4.45 and in dry season in 3.95 to 4.08 which is considered acidic. Correlation analysis showed that soil organic carbon value is influenced by pH value and climate. Correlation analysis between clay and soil organic carbon with depth showed positively significant differences and clay are very much influenced soil organic carbon content. Correlation analysis between electrical conductivity and soil organic carbon content showed negative significantly difference on wet season and positively significant different in dry season. (author)

  2. Metal(loid)s behaviour in soils amended with nano zero-valent iron as a function of pH and time.

    Science.gov (United States)

    Vítková, Martina; Rákosová, Simona; Michálková, Zuzana; Komárek, Michael

    2017-01-15

    Nano zero-valent iron (nZVI) is currently investigated as a stabilising amendment for contaminated soils. The effect of pH (4-8) and time (48 and 192 h) on the behaviour of nZVI-treated Pb-Zn and As-contaminated soil samples was assessed. Additionally, soil leachates were subsequently used to study the direct interaction between soil solution components and nZVI particles in terms of mineralogical changes and contaminant retention. A typical U-shaped leaching trend as a function of pH was observed for Cd, Pb and Zn, while As was released predominantly under alkaline conditions. Oxidising conditions prevailed, so pH was the key controlling parameter rather than redox conditions. Generally, longer contact time resulted in increased soluble concentrations of metal(loid)s. However, the stabilisation effect of nZVI was only observed after the direct soil leachate-nZVI interactions, showing enhanced redox and sorption processes for the studied metals. A significant decrease of dissolved As concentrations was observed for both experimental soils, but with different efficiencies depending on neutralisation capacity, organic matter content or solid fractionation of As related to the origin of the soils. Scorodite (FeAsO 4 ·2H 2 O) was predicted as a potential solubility-controlling mineral phase for As. Sorption of metal(loid)s onto secondary Fe- and Al-(oxyhydr)oxides (predicted to precipitate at pH > 5) represents an important scavenger mechanism. Moreover, transmission electron microscopy confirmed the retention of Zn and Pb under near-neutral and alkaline conditions by newly formed Fe oxides or aluminosilicates. This study shows that the efficiency of nZVI application strongly depends not only on soil pH-Eh conditions and contaminant type, but also on the presence of organic matter and other compounds such as Al/Fe/Mn oxyhydroxides and clay minerals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Ptaquiloside in Pteridium aquilinum subsp. aquilinum and corresponding soils from the South of Italy: influence of physical and chemical features of soils on its occurrence.

    Science.gov (United States)

    Zaccone, Claudio; Cavoski, Ivana; Costi, Roberta; Sarais, Giorgia; Caboni, Pierluigi; Traversa, Andreina; Miano, Teodoro M

    2014-10-15

    The bracken fern Pteridium aquilinum (L.) Kuhn, one of the most common plant species on Earth, produces a wide range of secondary metabolites including the norsesquiterpene glucoside ptaquiloside (PTA). Several studies are present in literature about eco-toxicological aspects related to PTA, whereas results about the effect of growth conditions and soil properties on the production and mobility of PTA are sometimes conflicting and further investigations are needed. The aim of the present work is to investigate the occurrence and possible fate of PTA in soils showing different physical and chemical features, and collected in several areas of the South of Italy. The PTA content was determined in both soil and fern samples by GC-MS; both the extraction protocol and recovery were previously tested through incubation studies. Soils samples were also characterized from the physical and chemical points of view in order to correlate the possible influence of soil parameters on PTA production and occurrence. PTA concentration in P. aquilinum fern seemed to be significantly affected by the availability of nutrients (mainly P) and soil pH. At the same time, PTA concentration in soil samples was always undetectable, independent of the PTA concentration in the corresponding Pteridium samples and pedo-climatic conditions. This seems to suggest the degradation of the PTA by indigenous soil microbial community, whereas incubation studies underlined a certain affinity of PTA for both organic colloids and clay/silt particles. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

    Directory of Open Access Journals (Sweden)

    Sung-Wook Yun

    2015-01-01

    Full Text Available Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

  5. Effects of artificial soil surface management on changes of ...

    African Journals Online (AJOL)

    Studies of size distribution, stability of the aggregates, and other soil properties are very important due to their influence on tilth, water infiltration, and nutrient dynamics and more importantly on accelerated erosion but are affected by soil surface management. Both chemical e.g. pH, organic carbon, (OC), exchangeable ...

  6. Influence of acid rain and organic matter on the adsorption of trace elements on soil

    International Nuclear Information System (INIS)

    Wang, H.; Ambe, S.; Takematsu, N.; Ambe, F.

    1998-01-01

    Acid rain has become one of the most serious environmental problems. Soil loses its buffering capacity by long exposure to acid rain, and the soil pH value decreases significantly. The acidification of the soil disturbs the adsorption equilibrium of many elements in the soil-water system. Soil is a very complex heterogeneous system, primarily consisting of clay minerals, hydrous oxides and polymeric organic substances, which possess their own characteristic element-adsorbing properties. On the other hand, the intrinsic properties of elements are reflected in their adsorption process as a matter of course. Therefore, both the effects of the pH of acid rain and that of the components of the soil on the adsorption of different elements should be studied when the adsorption process in acid soils is to be clarified. Although leaching of major cations in soil, such as Ca 2+ , Mg 2+ and Al 3+ , by acid rain, has been extensively studied, relatively little attention has been focused on trace elements which can also seriously affect the ecological system. We studied the acid rain effects on element adsorption by kaolin, forest soil, black soil, and also these soils with Fe- and Mn-oxides or organic matter selectively removed by using the radioactive multitracer technique. (author)

  7. Influence of the Dentinal Wall on the pH of Sodium Hypochlorite during Root Canal Irrigation

    NARCIS (Netherlands)

    Macedo, Ricardo Gomes; Herrero, Noemi Pascual; Wesselink, Paul; Versluis, Michel; van der Sluis, Luc

    Introduction: The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels.

  8. Forest management type influences diversity and community composition of soil fungi across temperate forest ecosystems

    Directory of Open Access Journals (Sweden)

    Kezia eGoldmann

    2015-11-01

    Full Text Available Fungal communities have been shown to be highly sensitive towards shifts in plant diversity and species composition in forest ecosystems. However, little is known about the impact of forest management on fungal diversity and community composition of geographically separated sites. This study examined the effects of four different forest management types on soil fungal communities. These forest management types include age class forests of young managed beech (Fagus sylvatica L., with beech stands age of approximately 30 years, age class beech stands with an age of approximately 70 years, unmanaged beech stands, and coniferous stands dominated by either pine (Pinus sylvestris L. or spruce (Picea abies Karst. which are located in three study sites across Germany. Soil were sampled from 48 study plots and we employed fungal ITS rDNA pyrotag sequencing to assess the soil fungal diversity and community structure.We found that forest management type significantly affects the Shannon diversity of soil fungi and a significant interaction effect of study site and forest management on the fungal OTU richness. Consequently distinct fungal communities were detected in the three study sites and within the four forest management types, which were mainly related to the main tree species. Further analysis of the contribution of soil properties revealed that C/N ratio being the most important factor in all the three study sites whereas soil pH was significantly related to the fungal community in two study sites. Functional assignment of the fungal communities indicated that 38% of the observed communities were Ectomycorrhizal fungi (ECM and their distribution is significantly influenced by the forest management. Soil pH and C/N ratio were found to be the main drivers of the ECM fungal community composition. Additional fungal community similarity analysis revealed the presence of study site and management type specific ECM genera.This study extends our knowledge

  9. Forest Management Type Influences Diversity and Community Composition of Soil Fungi across Temperate Forest Ecosystems.

    Science.gov (United States)

    Goldmann, Kezia; Schöning, Ingo; Buscot, François; Wubet, Tesfaye

    2015-01-01

    Fungal communities have been shown to be highly sensitive toward shifts in plant diversity and species composition in forest ecosystems. However, little is known about the impact of forest management on fungal diversity and community composition of geographically separated sites. This study examined the effects of four different forest management types on soil fungal communities. These forest management types include age class forests of young managed beech (Fagus sylvatica L.), with beech stands age of approximately 30 years, age class beech stands with an age of approximately 70 years, unmanaged beech stands, and coniferous stands dominated by either pine (Pinus sylvestris L.) or spruce (Picea abies Karst.) which are located in three study sites across Germany. Soil were sampled from 48 study plots and we employed fungal ITS rDNA pyrotag sequencing to assess the soil fungal diversity and community structure. We found that forest management type significantly affects the Shannon diversity of soil fungi and a significant interaction effect of study site and forest management on the fungal operational taxonomic units richness. Consequently distinct fungal communities were detected in the three study sites and within the four forest management types, which were mainly related to the main tree species. Further analysis of the contribution of soil properties revealed that C/N ratio being the most important factor in all the three study sites whereas soil pH was significantly related to the fungal community in two study sites. Functional assignment of the fungal communities indicated that 38% of the observed communities were Ectomycorrhizal fungi (ECM) and their distribution is significantly influenced by the forest management. Soil pH and C/N ratio were found to be the main drivers of the ECM fungal community composition. Additional fungal community similarity analysis revealed the presence of study site and management type specific ECM genera. This study extends our

  10. Fator capacidade de fósforo em solos de pernambuco mineralogicamente diferentes e influência do pH na capacidade máxima de adsorção Phosphate capacity factor in mineralogically different soils in Pernambuco and the influence of pH on the maximum capacity of adsorption

    Directory of Open Access Journals (Sweden)

    Fábio Broggi

    2011-02-01

    Full Text Available O Fator Capacidade de Fósforo (FCP é definido pela razão de equilíbrio entre o fator quantidade de P (Q e o fator intensidade (I e representa uma medida da capacidade do solo em manter um determinado nível de P em solução. As características e o teor dos constituintes minerais da fração argila são responsáveis por uma maior ou menor FCP, interferindo nas relações solo-planta. Por outro lado, o pH do solo tem, em alguns casos, mostrado-se com efeito na adsorção e, em outros, com pequena e não consistente alteração na Capacidade Máxima de Adsorção de P (CMAP. Objetivou-se, neste trabalho, determinar o FCP de solos mineralogicamente diferentes em Pernambuco; correlacionar características físicas e químicas dos solos com o FCP; e avaliar o efeito do pH na CMAP. Amostras subsuperficiais de quatro solos, mineralogicamente diferentes, foram caracterizadas química e fisicamente e determinado o FCP. Essas amostras foram corrigidas com CaCO3 e MgCO3 na proporção 4:1 e incubadas por 30 dias, com exceção do Vertissolo. Determinou-se a CMAP antes e após a correção dos solos. O experimento consistiu de um fatorial 4 x 2 (quatro solos com e sem correção, distribuídos em blocos ao acaso, com três repetições. As características dos solos que melhor refletiram o FCP foram o P remanescente (P-rem e a CMAP. Independentemente dos constituintes mineralógicos da fração argila, solos com elevados teores de alumínio apresentaram aumento da CMAP com a correção. A energia de adsorção (EA nos solos corrigidos foi, em média, significativamente menor, independentemente do solo.Phosphate Maximum Capacity (FCP is defined by the ratio of equilibrium between the amount of factor P (Q and factor intensity (I and represents a measure of the soil ability to maintain a certain level of P in solution. The characteristics and content of the constituents of clay minerals are responsible for a greater or lesser FCP, interfering in soil

  11. The geochemistry during management of lake acidification caused by the rewetting of sulfuric (pH < 4) acid sulfate soils

    International Nuclear Information System (INIS)

    Mosley, Luke M.; Shand, Paul; Self, Peter; Fitzpatrick, Rob

    2014-01-01

    Highlights: • The dynamic geochemistry of a lake acidification event and its management was assessed. • Sulfate complexes dominated the aqueous metal speciation at low pH. • Iron oxydroxysulfate minerals (schwertmannite, jarosite) were identified. • Aerial additions of limestone to the acidic water slowly returned the pH to near neutral. • Coating of the limestone with gypsum and metal precipitates limited its neutralisation efficiency. - Abstract: Understanding the geochemistry and kinetics of acidification events arising from acid sulfate soils is important to enable effective management and risk assessment. Large-scale exposure and oxidation of acid sulfate soils occurred during a drought in the Lower Lakes (Murray–Darling Basin) of South Australia. We examined the geochemical changes that occurred in one region (Boggy Lake) that experienced surface water acidification and was subsequently neutralised via aerial limestone (CaCO 3 ) dosing and dilution via natural lake refill. Very low pH (< 3) and high concentrations (≈10–1000 mg/L Fe, Al, Mn) of dissolved metals were initially found in surface water. The water chemistry exhibited pH-dependent enhancement of constituents typically associated with acid sulfate soils (SO 4 , Al and Fe). Geochemical speciation calculations indicated that most (60–80%) of the acidity was present as dissolved metal-sulfate complexes at low pH. X-ray diffraction (XRD) analyses showed that the orange-brown precipitates present after an initial limestone dosing were secondary oxyhydroxysulfate minerals (schwertmannite, jarosite). Further limestone dosing resulted in neutralisation of the pH, reduction in dissolved metal concentrations, dissolution of jarosite and schwertmannite precipitates, and formation of other metal oxyhydroxide phases. The results were consistent with a pE-pH diagram constructed for metal-sulfur geochemistry. Assessment of the measured and simulated (using PHREEQC) pH and Ca/Cl ratio during

  12. INFLUENCE OF USUAL AND DUAL WHEELS ON SOIL PENETRATION RESISTANCE: THE GIS-APPROACH

    Directory of Open Access Journals (Sweden)

    Zhukov A. V.

    2015-12-01

    Full Text Available GIS-APPROACH application has allowed establishing that usual wheels of machine-tractor units carry out considerable influence on soil which exceeds visible borders of a track of wheels on the dimensions. This influence shows in augmentation of soil penetration resistance at 100-155 % in comparison with the control on depth of 0-10 cm and on 20-30 % on depth of 45-50 %. It is impossible to exclude that influence of wheels proceeds more deeply, than tests have been conducted. Critical for cultivated plants value of soil penetration resistance in 3 MPa under the influence of usual wheels of agricultural machinery comes nearer practically to a surface. Character of profile changes of hardness in various regions influences of wheels allows assuming the long season of a relaxation of soil for achievement of background values of soil penetration resistance. The further researches are necessary for an establishment of concrete indicators of dynamics. Negative influence of an overstocking does not confine only deterioration of conditions of growth of assemblages of rootlets of plants. Infringement of processes of moving of moisture in the soil, the accelerated evaporation and the slowed down processes of a filtration and an infiltration, destruction of modular frame, activization of erosive processes is possible. The understanding of these processes will give the chance volume understanding of real influence of running systems of machine-tractor devices on bedrock. Region intensive influence of dual wheels is circumscribed by the top soil layers (0-15 cm. The major feature of influence of dual wheels is absence of an overstocking above critical levels. It is impossible to exclude possible positive influence of moderate inspissations of soil under the influence of dual wheels for growth of agricultural crops and moisture conservation in soil. The cumulative negative effect on soil crossed vehicles traces is probable. The long season of a relaxation of

  13. The gamma dose assessment and pH correlation for various soil types at Batu Pahat and Kluang districts, Johor, Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Johar, Saffuwan Mohamed, E-mail: saffuwan@uthm.edu.my [Department of Science, Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia (Malaysia); Embong, Zaidi [Department of Science, Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia (Malaysia); Research Center for Soft Soil (RECESS), Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia (Malaysia); Tajudin, Saiful Azhar Ahmad [Research Center for Soft Soil (RECESS), Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia (Malaysia)

    2016-01-22

    An assessment of absorbed dose and radiation hazard index as well as its relationship with soil pH was performed in this study. The area was chosen due to its variety of soil types from the Alluvial and the Sedentary group. The radioactivity concentration levels and the soil acidity were measured using the Canberra GC3518 high pure germanium with a relative efficiency of 35% at 1.3 MeV and the Takemura Soil pH and Moisture Tester (DM15), respectively. Overall results show the Holyrood-Lunas soil of Alluvial group recorded the highest external terrestrial gamma radiation dose rate (TGRD) of 286.4±37.9 nGy h{sup −1} and radioactivity concentrations of 78.1±8.9 Bq kg{sup −1} ({sup 226}Ra), 410.5±55.4 Bq kg{sup −1} ({sup 232}Th) and 56.4±8.8 Bq kg{sup −1} ({sup 40}K), respectively, while the Peat soil of Alluvial group recorded the lowest TGRD of 4.4±2.7 nGy h{sup −1} and radioactivity concentrations of 4.8±1.7 Bq kg{sup −1} ({sup 226}Ra), 3.1±1.1 Bq kg{sup −1} ({sup 232}Th) and 6.1±2.0 Bq kg{sup −1} ({sup 40}K), respectively. The estimated mean outdoor annual effective dose, the mean radium equivalent activity (R{sub eq}) and the mean external (H{sub ext}) and internal hazard index (H{sub int}) associated with the alluvial and sedentary soil group were evaluated at 0.15 and 0.20 mSv, 280 and 364 Bq kg{sup −1}, H{sub ext} = 0.78 and 1.01, and H{sub int} = 0.93 and 1.26, respectively. Correlation analysis between 238U, {sup 232}Th and {sup 40}K with soil pH level for alluvial group was r = +0.68, +0.48 and 0, respectively, while for sedentary soil, the Pearson’s, r = −0.30, −0.90 and +0.14, respectively.

  14. Modeling the influence of organic acids on soil weathering

    Science.gov (United States)

    Lawrence, Corey R.; Harden, Jennifer W.; Maher, Kate

    2014-01-01

    Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

  15. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Brus, D.J.; Guo, H.Y.; Chu, C.L.; Chiang, C.M.; Koopmans, G.F.

    2011-01-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal

  16. Cadmium availability in rice paddy fields from a mining area: The effects of soil properties highlighting iron fractions and pH value.

    Science.gov (United States)

    Yu, Huan-Yun; Liu, Chuanping; Zhu, Jishu; Li, Fangbai; Deng, Dong-Mei; Wang, Qi; Liu, Chengshuai

    2016-02-01

    Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Co-contaminants and factors affecting the sorption behaviour of two sulfonamides in pasture soils

    International Nuclear Information System (INIS)

    Srinivasan, Prakash; Sarmah, Ajit K.; Manley-Harris, Merilyn

    2013-01-01

    We investigated the effect of soil pH, organic carbon, ionic strength and steroid hormones on the sorption of sulfamethoxazole (SMO) and sulfachloropyridazine (SCP) in three pastoral soils of New Zealand. A model linking sorbate speciation with species-specific sorption coefficients describing the pH dependence of the apparent sorption coefficients was used to derive the fraction of each species of SMO. All soils displayed a decrease in sorption when pH was increased, with SMO exhibiting the highest sorption at pH 2. The cationic form of SMO appeared to sorb more close to pH ≥ pK a1 and, when pH ≥ pK a2 (6.5, 7.5 and 8.5) the anionic species seems to dominate, however, its sorption affinity to all soils was low. SMO sorption was affected by ionic strengths and organic carbon content, while the presence of hormones showed only a subtle decrease in SCP sorption in a selected model pasture soil. -- Highlights: •The effect of OC content on sulfamethoxazole sorption is nullified by the pH effect. •Steroid hormone has a subtle influence on the sulfachloropyridazine sorption in pastoral soil. •Increased hormone concentrations decrease sulfachloropyridazine sorption in soils. -- Sorption affinity of SMO and SCP are strongly governed by multitude of factors, and variations in these factors can be significant when manure and fertilisers are added to soil

  18. Yield and cold storage of Trichoderma conidia is influenced by substrate pH and storage temperature.

    Science.gov (United States)

    Steyaert, Johanna M; Chomic, Anastasia; Nieto-Jacobo, Maria; Mendoza-Mendoza, Artemio; Hay, Amanda J; Braithwaite, Mark; Stewart, Alison

    2017-05-01

    In this study we examined the influence of the ambient pH during morphogenesis on conidial yield of Trichoderma sp. "atroviride B" LU132 and T. hamatum LU593 and storage at low temperatures. The ambient pH of the growth media had a dramatic influence on the level of Trichoderma conidiation and this was dependent on the strain and growth media. On malt-extract agar, LU593 yield decreased with increasing pH (3-6), whereas yield increased with increasing pH for LU132. During solid substrate production the reverse was true for LU132 whereby yield decreased with increasing pH. The germination potential of the conidia decreased significantly over time in cold storage and the rate of decline was a factor of the strain, pH during morphogenesis, growth media, and storage temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Soil Response to Global Change: Soil Process Domains and Pedogenic Thresholds (Invited)

    Science.gov (United States)

    Chadwick, O.; Kramer, M. G.; Chorover, J.

    2013-12-01

    The capacity of soil to withstand perturbations, whether driven by climate, land use change, or spread of invasive species, depends on its chemical composition and physical state. The dynamic interplay between stable, well buffered soil process domains and thresholds in soil state and function is a strong determinant of soil response to forcing from global change. In terrestrial ecosystems, edaphic responses are often mediated by availability of water and its flux into and through soils. Water influences soil processes in several ways: it supports biological production, hence proton-donor, electron-donor and complexing-ligand production; it determines the advective removal of dissolution products, and it can promote anoxia that leads microorganisms to utilize alternative electron acceptors. As a consequence climate patterns strongly influence global distribution of soil, although within region variability is governed by other factors such as landscape age, parent material and human land use. By contrast, soil properties can vary greatly among climate regions, variation which is guided by the functioning of a suite of chemical processes that tend to maintain chemical status quo. This soil 'buffering' involves acid-base reactions as minerals weather and oxidation-reduction reactions that are driven by microbial respiration. At the planetary scale, soil pH provides a reasonable indicator of process domains and varies from about 3.5 to10, globally, although most soils lie between about 4.5 and 8.5. Those that are above 7.5 are strongly buffered by the carbonate system, those that are characterized by neutral pH (7.5-6) are buffered by release of non-hydrolyzing cations from primary minerals and colloid surfaces, and those that are buffered by hydrolytic aluminum on colloidal surfaces. Alkali and alkaline (with the exception of limestone parent material) soils are usually associated with arid and semiarid conditions, neutral pH soils with young soils in both dry and wet

  20. Decreased Soil Nitrification Rate with Addition of Biochar to Acid Soils

    Institute of Scientific and Technical Information of China (English)

    Shiyu LI; Xiangshu DONG; Dandan LIU; Li LIU; Feifei HE

    2017-01-01

    This study was conducted to investigate the effects of mixed biochar on the nitrification rate in acidic soils. A 15N tracer experiment with (15NH4)2SO4 was conducted to determine the nitrification rates of 4 acidic agricultural soils with pH 4.03-6.02in Yunnan Province, Southern China. The accumulation of 15N-NO3 - and nitrification rates decreased with the addition of biochar at the end of incubation, suggesting that biochar could be a nitrification inhibitor in acidic fertilized soil. Nitrification rates in soil with pH 4.03 were evidently lower than those in soil with pH 4.81 -6.02 with or without biochar. Decreased nitrification rates were detected in the acidic soils with biochar. Soil pH controlled nitrification more than biochar in certain strongly acidic soils.

  1. Effect of manure, clay, charcoal, zeolite, and calcium oxide on some properties of soil contaminated with cobalt

    Directory of Open Access Journals (Sweden)

    Kosiorek Milena

    2017-09-01

    Full Text Available The study has been undertaken in order to determine the influence of different substances (manure, clay, charcoal, zeolite and calcium oxide on soil pH, hydrolytic acidity, total exchangeable bases, cation exchange capacity, the base saturation of soil contaminated with cobalt (0, 20, 40, 80, 160, 320 mg·kg−1 of soil. The analysed properties of soil proved to be dependent on the cobalt contamination and the kind of substances. In the series without substances soil contamination with the highest doses of cobalt raised the soil’s hydrolytic acidity but depressed its pH, total exchangeable bases and base saturation. Among the substances applied to soil in order to neutralize the effect of contamination with cobalt, calcium oxide had the strongest influence on the soil’s properties. In the series with calcium oxide application the hydrolytic acidity was decreased and other soil properties were increased. Manure addition to soil had positive but weaker effect on analysed soil properties.

  2. Influence of organic components on plutonium and americium speciation in soils and soil solutions

    International Nuclear Information System (INIS)

    Sokolik, G.A.; Ovsyannikova, S.V.; Kimlenko, I.M.

    2003-01-01

    Group composition of humic substances of organic and mineral soils sampled in the 30-km zone of the Chernobyl accident was analyzed for studying influence of organic components on migration properties of plutonium and americium in soils and soil solutions by the method of gel-chromatography and chemical fractionation. It was ascertained that humus of organic soils binds plutonium and americium stronger than humus of mineral soils. Elevated mobility of americium compared to plutonium one stems from lower ability of the latter to from hard to solve organic and organomineral complexes, as well as from its ability to form anionic complexes in soil solutions [ru

  3. Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures

    Science.gov (United States)

    Liu, Shurong; Berns, Anne E.; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

    2017-02-01

    Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH2OH) to nitrous oxide (N2O) is a possible mechanism of N2O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO2) and organic matter (OM) content of soil as well as soil pH are important control variables of N2O formation in the soil. But until now, their combined effect on abiotic N2O formation from NH2OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO2 and OM, respectively, and quantified the interactive effects of the three variables on the NH2OH-to-N2O conversion ratio (RNH2OH-to-N2O). Furthermore, the effect of OM quality on RNH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO2 and OM on RNH2OH-to-N2O. In general, increasing MnO2 and decreasing pH increased RNH2OH-to-N2O, while increasing OM content was associated with a decrease in RNH2OH-to-N2O. Organic matter quality also affected RNH2OH-to-N2O. However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

  4. Sorption of thiabendazole in sub-tropical Brazilian soils.

    Science.gov (United States)

    de Oliveira Neto, Odilon França; Arenas, Alejandro Yopasa; Fostier, Anne Hélène

    2017-07-01

    Thiabendazole (TBZ) is an ionizable anthelmintic agent that belongs to the class of benzimidazoles. It is widely used in veterinary medicine and as a fungicide in agriculture. Sorption and desorption are important processes influencing transport, transformation, and bioavailability of xenobiotic compounds in soils; data related to sorption capacity are therefore needed for environmental risk assessments. The aim of this work was to assess the sorption potential of TBZ in four Brazilians soils (sandy, sandy-clay, and clay soils), using batch equilibrium experiments at three pH ranges (2.3-3.0, 3.8-4.2, and 5.5-5.7). The Freundlich sorption coefficient (K F ) ranged from 9.0 to 58 μg 1-1/n  (mL) 1/n  g -1 , with higher values generally observed at the lower pH ranges (2.3-3.0 and 3.8-4.2) and for clay soils. The highest organic carbon-normalized sorption coefficients (K OC ) obtained at pH 3.8-5.7 (around the natural pH range of 4.1-5.0) for both clay soils and sandy-clay soil were 3255 and 2015 mL g -1 , respectively. The highest correlations K F vs SOM (r = 0.70) and K F vs clay content (r = 0.91) were observed at pH 3.8-4.2. Our results suggest that TBZ sorption/desorption is strongly pH dependent and that its mobility could be higher in the studied soils than previously reported in soils from temperate regions.

  5. INFLUENCE OF NPK AND LIME APLICATION ON ERVA-MATE GROWTH, ROOT-ROT SEVERITY AND SOIL FUNGI POPULATION1

    Directory of Open Access Journals (Sweden)

    Igor Poletto

    2011-09-01

    Full Text Available The present work evaluated the influence of the application of NPK and liming doses in the soil, on the growth of Erva-mate, the severity of rot-root and the fungi population of the soil. To do so, an experiment was installed at the green house, in the Forest Nursery of UFSM, using an experimental design completely randomized factorial 4x3x4 (Factor F: Fusarium spp. inoculation; Factor C: soil limestone; Factor A: NPK doses , totaling 48 treatments. The seedlings were cultivated in vases containing 2 kg of soil, classified as ‘Red-Yellow Argisoil’ (clay soil. At the end of the experiment was measured the stem diameter, height of the aerial part, leaves number, aerial dry biomass, root dry biomass and total dry biomass of the seedlings. Also, the soil was collected, from each treatment, for the chemical analysis and the counting of the fungi population. It was observed that the association among application of NPK and liming in the soil hampered the development of Erva-mate seedlings. The analysis of some variables suggests that the limestone absence provided greater resistance of seedlings to the attack of Fusarium spp. or the severity of Fusarium spp. was reduced in lower pH. The fungi population of the soil presented varied behavior depending on the applied treatments.

  6. Detection of tritium sorption on four soil materials

    International Nuclear Information System (INIS)

    Teng Yanguo; Zuo Rui; Wang Jinsheng; Hu Qinhong; Sun Zongjian; Zeng Ni

    2011-01-01

    In order to measure groundwater age and design nuclear waste disposal sites, it is important to understand the sorption behavior of tritium on soils. In this study, batch tests were carried out using four soils from China: silty clays from An County and Jiangyou County in Sichuan Province, both of which could be considered candidate sites for Very Low Level Waste disposal; silty sand from Beijing; and loess from Yuci County in Shanxi Province, a typical Chinese loess region. The experimental results indicated that in these soil media, the distribution coefficient of tritium is slightly influenced by adsorption time, water/solid ratio, initial tritium specific activity, pH, and the content of humic and fulvic acids. The average distribution coefficient from all of these influencing factors was about 0.1-0.2 mL/g for the four types of soil samples. This relatively modest sorption of tritium in soils needs to be considered in fate and transport studies of tritium in the environment. - Research highlights: → In this study, batch sorption tests validate the adsorption of tritium on all of the four tested soil samples collected in China, and the distribution coefficient is found to be non-zero and less than 0.4 mL/g. The experimental results indicated that in these soil media, the distribution coefficient of tritium is slightly influenced by adsorption time, water/solid ratio, initial tritium specific activity, pH, and the content of humic and fulvic acids. This relatively modest sorption of tritium in soils needs to be considered in fate and transport studies of tritium in the environment.

  7. The relationship between plant species richness and soil pH vanishes with increasing aridity across Eurasian dry grasslands

    Czech Academy of Sciences Publication Activity Database

    Palpurina, S.; Wagner, V.; von Wehrden, H.; Hájek, M.; Horsák, M.; Brinkert, A.; Hölzel, N.; Wesche, K.; Kamp, J.; Hájková, Petra; Danihelka, Jiří; Lustyk, P.; Merunková, K.; Preislerová, Z.; Kočí, M.; Kubešová, S.; Cherosov, M. M.; Ermakov, N.; German, D.; Gogoleva, P. A.; Lashchinsky, N.; Martynenko, V. B.; Chytrý, M.

    2017-01-01

    Roč. 26, č. 4 (2017), s. 425-434 ISSN 1466-822X Institutional support: RVO:67985939 Keywords : diversity-environment relationship * dry grassland * precipitation * soil pH Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 6.045, year: 2016

  8. Dynamical soil-structure interactions: influence of soil behaviour nonlinearities

    International Nuclear Information System (INIS)

    Gandomzadeh, Ali

    2011-01-01

    the soil and the response of the soil-structure system. Through these parametric studies we show that depending on the soil properties, frequency content of the soil response could change significantly due to the soil nonlinearity. The peaks of the transfer function between free field and outcropping responses shift to lower frequencies and amplification happens at this frequency range. Amplification reduction for the high frequencies and even de-amplification may happen for high level input motions. These changes influence the structural response. We show that depending on the combination of the fundamental frequency of the structure and the the natural frequency of the soil, the effect of soil-structure interaction could be significant or negligible. However, the effect of structure weight and rocking of the superstructure could change the results. Finally, the basin of Nice is used as an example of wave propagation on a heterogeneous nonlinear media and dynamic soil-structure interaction. The basin response is strongly dependent on the combination of soil nonlinearity, topographic effects and impedance contrast between soil layers. For the selected structures and soil profiles of this work, the performed numerical simulations show that the shift of the fundamental frequency is not a good index to discriminate linear from nonlinear soil behavior. (author)

  9. Strontium sorption on Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1984-12-01

    A laboratory study of strontium-85 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that strontium sorption is most strongly a function of pH. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence strontium sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect. Ferrous ion, added to groundwater to simulate the conditions of water at the bottom of waste trenches, did not account for low strontium sorption observed with some trench waters

  10. Investigation of features in radon soil dynamics and search for influencing factors

    Science.gov (United States)

    Yakovlev, Grigorii; Cherepnev, Maxim; Nagorskiy, Petr; Yakovleva, Valentina

    2018-03-01

    The features in radon soil dynamics at two depths were investigated and the main influencing factors were revealed. The monitoring of radon volumetric activity in soil air was performed at experimental site of Tomsk Observatory of Radioactivity and Ionizing Radiation with using radon radiometers and scintillation detectors of alpha-radiation with 10 min sampling frequency. The detectors were installed into boreholes of 0.5 and 1 m depths. The analysis of the soil radon monitoring data has allowed revealing some dependencies at daily and annual scales and main influencing factors. In periods with clearly defined daily radon variations in the soil were revealed the next: 1) amplitude of the daily variations of the soil radon volumetric activity damps with the depth, that is related with the influence of convective fluxes in the soil; 2) temporal shift between times of occurrence of radon volumetric activity maximum (or minimum) values at 0.5 m and 1 m depths can reach 3 hours. In seasonal dynamics of the soil radon the following dependences were found: 1) maximal values are observed in winter, but minimal - in summer; 2) spring periods of snow melting are accompanied by anomaly increasing of radon volumetric activity in the soil up to about 3 times. The main influencing factors are atmospheric precipitations, temperature gradient in the soil and the state of upper soil layer.

  11. Chemical stability of insulin. 3. Influence of excipients, formulation, and pH.

    Science.gov (United States)

    Brange, J; Langkjaer, L

    1992-01-01

    The influence of auxiliary substances and pH on the chemical transformations of insulin in pharmaceutical formulation, including various hydrolytic and intermolecular cross-linking reactions, was studied. Bacteriostatic agents had a profound stabilizing effect--phenol > m-cresol > methylparaben--on deamidation as well as on insulin intermolecular cross-linking reactions. Of the isotonicity substances, NaCl generally had a stabilizing effect whereas glycerol and glucose led to increased chemical deterioration. Phenol and sodium chloride exerted their stabilizing effect through independent mechanisms. Zinc ions, in concentrations that promote association of insulin into hexamers, increase the stability, whereas higher zinc content had no further influence. Protamine gave rise to additional formation of covalent protamine-insulin products which increased with increasing protamine concentration. The impact of excipients on the chemical processes seems to be dictated mainly via an influence on the three-dimensional insulin structure. The effect of the physical state of the insulin on the chemical stability was also complex, suggesting an intricate dependence of intermolecular proximity of involved functional groups. At pH values below five and above eight, insulin degrades relatively fast. At acid pH, deamidation at residue A21 and covalent insulin dimerization dominates, whereas disulfide reactions leading to covalent polymerization and formation of A- and B-chains prevailed in alkaline medium. Structure-reactivity relationship is proposed to be a main determinant for the chemical transformation of insulin.

  12. Functional significance of tree species diversity and species identity on soil organic carbon, C/N ratio and pH in major European forest types

    DEFF Research Database (Denmark)

    Dawud, Seid Muhie

    Forests provide different ecosystem functions and services including soil carbon sequestration and nutrient supply to maintain growth and productivity. This PhD thesis explored tree species diversity and tree species identity (conifer proportion of basal area) effects on soil C stock and nutrient...... 8 and 12 years old common garden stands established in two contrasting bioclimatic regions. In all the studied contexts, tree species identity (confers versus broadleaves) was stronger than diversity in consistently driving variability of the examined soil properties and root characteristics......, particularly in topsoil layers. Diversity did not affect fine root characteristics of the young forests and effects on soil properties were different under the investigated contexts. Across the different European sites, diversity had no effect on C/N ratio and pH but under comparable environmental conditions...

  13. Remediation of multiple heavy metal-contaminated soil through the combination of soil washing and in situ immobilization.

    Science.gov (United States)

    Zhai, Xiuqing; Li, Zhongwu; Huang, Bin; Luo, Ninglin; Huang, Mei; Zhang, Qiu; Zeng, Guangming

    2018-09-01

    The remediation of heavy metal-contaminated soils is a great challenge for global environmental sciences and engineering. To control the ecological risks of heavy metal-contaminated soil more effectively, the present study focused on the combination of soil washing (with FeCl 3 ) and in situ immobilization (with lime, biochar, and black carbon). The results showed that the removal rate of Cd, Pb, Zn, and Cu was 62.9%, 52.1%, 30.0%, and 16.7%, respectively, when washed with FeCl 3 . After the combined remediation (immobilization with 1% (w/w) lime), the contaminated soils showed 36.5%, 73.6%, 70.9%, and 53.4% reductions in the bioavailability of Cd, Cu, Pb, and Zn (extracted with 0.11M acetic acid), respectively, than those of the soils washed with FeCl 3 only. However, the immobilization with 1% (w/w) biochar or 1% (w/w) carbon black after washing exhibited low effects on stabilizing the metals. The differences in effects between the immobilization with lime, biochar, and carbon black indicated that the soil pH had a significant influence on the lability of heavy metals during the combined remediation process. The activity of the soil enzymes (urease, sucrase, and catalase) showed that the addition of all the materials, including lime, biochar, and carbon black, exhibited positive effects on microbial remediation after soil washing. Furthermore, lime was the most effective material, indicating that low soil pH and high acid-soluble metal concentrations might restrain the activity of soil enzymes. Soil pH and nutrition were the major considerations for microbial remediation during the combined remediation. These findings suggest that the combination of soil washing and in situ immobilization is an effective method to amend the soils contaminated with multiple heavy metals. Copyright © 2018 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2013-04-01

    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 Presistant 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

  15. Arsenic adsorption of lateritic soil, limestone powder, lime and fly ash on arsenic-contaminated soil

    Directory of Open Access Journals (Sweden)

    Wuthiphun, L.

    2007-05-01

    Full Text Available Arsenic adsorption efficiency of soil covering materials (lateritic soil, limestone powder, lime and fly ash on arsenic-contaminated soil obtained from Ronpiboon District, Nakhon Sri Thammarat Province tosolve arsenic air pollution problem was investigated using batch experiments. The four types of the aforementioned soil covering materials were examined to determine their arsenic adsorption efficiency, equilibriumtime as well as adsorption isotherms.The results revealed that among soil covering materials mixed with arsenic-contaminated soil at 10% w/w, the efficiency of arsenic adsorption of fly ash, lateritic soil, lime and limestone powder were 84, 60,38 and 1% respectively. The equilibrium time for lateritic soil at pH 4 was achieved within 4 hrs, whereas pH 7 and 12, the equilibrium time was 6 hrs. For fly ash, 2 hrs were required to reach the equilibrium at pH 12, while the equilibrium time was attained within 6 hrs at pH 4 and 7. Furthermore, lateritic soil possessedhigh arsenic adsorption efficiency at pH 7 and 4 and best fit with the Langmuir isotherm. The fly ash showing high arsenic adsorption efficiency at pH 12 and 7 fit the Freundlich isotherm at pH 12 and Langmuirisotherm at pH 7.This indicated that lateritic soil was suitable for arsenic adsorption at low pH, whilst at high pH,arsenic was well adsorbed by fly ash. The Freundlich and Langmuir isotherm could be used to determine quantities of soil covering materials for arsenic adsorption to prevent arsenic air pollution from arseniccontaminated soils.

  16. INFLUENCE OF ILLEGAL WASTE DUMPING SITES OF NORTH-WEST PART OF BARLINEK COMMUNITY ON HEAVY METALS CONTENT IN SOILS

    Directory of Open Access Journals (Sweden)

    Kamil Szydłowski

    2017-02-01

    Full Text Available The in-depth analysis of the soil samples study included 6 from 17 catalogued illegal waste dumps localized in the Barlinek Commune (Gmina Barlinek area. The samples were taken from the middle part of each waste dump and at 5 meter distance toward north and south directions. In the collected material the pH values and concentration of lead, zinc, cadmium, cobalt, manganese, nickel, chromium, iron, copper and mercury were determined. The results of laboratory analysis were compared with current standards (Regulation of the Minister of Environment from 9th September 2002 on soil quality standards and quality standards of soil - Journal of Laws 2002 No 165, item 1359 and with the soils classification by the content of trace elements, according to Kabata-Pendias et al. The reason of diversified content of heavy metals in the collected soils samples from different waste dumps is various morphological composition of deposited waste. Nonetheless, waste landfilled on illegal dumps were not significantly influencing the levels of soil contamination with heavy metals. The concentration of Hg, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, Fe qualifies those soils to geochemical natural levels of heavy metals content. Nevertheless, cadmium was the element, which concentration were most often (21 times exceeded.

  17. Interactions of calcium sulfite with soils and plants

    International Nuclear Information System (INIS)

    Ritchey, K.D.; Kinraide, T.B.; Wendell, R.R.

    1995-01-01

    CaSO 3 is a by-product formed by several of the processes used for scrubbing SO 2 from flue gas produced by coal-burning power generators. Using CaSO 3 to improve the calcium status of acid soils would be a beneficial alternative to disposal in landfills. CaSO 3 has biocidal properties and is used as disinfectant and food and drink preservative. It is important to evaluate under what conditions application to soils would not harm plant growth. Laboratory experiments confirmed that two transformations of CaSO 3 occurred in soil systems: (1) decomposition to produce SO 2 gas, and (2) oxidation to calcium suflate. Conversion to SO 2 occurred in solution and soil at low pH, and acid soils treated with CaSO 3 were initially toxic to seedling root growth. The degree of toxicity was time-dependent, with reduction in toxicity occurring as CaSO 3 oxidized to calcium sulfate. Soil reaction also influenced toxicity, and at soil pH levels above 6, little seeding toxicity was evident

  18. Adsorption and desorption of 14C-chlorsulfuron in soils

    International Nuclear Information System (INIS)

    Chen Zuyi; Cheng Wei; Mi Chunyun

    1995-01-01

    The adsorption and desorption of the 4 concentrations of 14 C-chlorsulfuron in 10 soils were studied. As a result the soils had weak adsorptions of chlorsulfuron and the adsorptions varied with different type of soils tested. Adsorption rate of paddy soil (infant red earth) from Hunan and latosol red earth from Hainan was 3%∼4%; Yellow-brown earth from Nanjing and red earth from Jiangxi was 6%∼9%; black soil from Jilin, paddy soil (infant red earth) from Jiangxi and red earth from Anhui was 10%∼14%; Albic bleached soil from Jilin and yellow fluvo-aquatic soil from Jiangsu was 19%∼23%. pH value had an influence on the adsorption and organic matter had not obvious influence on the adsorption. Chlorsulfuron absorbed in soil could be desorbed through water. The relation between the adsorption and desorption was negative. The weak adsorption in soil shows that chlorsulfuron is active movable and diffusible and likely to pollute the ecological environment

  19. Soil-structure interaction Vol.3. Influence of ground water

    Energy Technology Data Exchange (ETDEWEB)

    Costantino, C J

    1986-04-01

    This study has been performed for the Nuclear Regulatory Commission (NRC) by the Structural Analysis Division of Brookhaven National Laboratory (BNL). The study was conducted during the fiscal year 1965 on the program entitled 'Benchmarking of Structural Engineering Problems' sponsored by NRC. The program considered three separate but complementary problems, each associated with the soil-structure interaction (551) phase of the seismic response analysis of nuclear plant facilities. The reports, all entitled Soil-Structure Interaction, are presented in three separate volumes, namely: Vol. 1 Influence of Layering by AJ Philippacopoulos, Vol. 2 Influence of Lift-Off by C.A. Miller, Vol. 3 Influence of Ground Water by C.J. Costantino. The two problems presented in Volumes 2 and 3 were conducted at the City University of New York (CUNY) under subcontract to BNL. This report, Volume 3 of the report, presents a summary of the first year's effort on the subject of the influence of foundation ground water on the SSI phenomenon. A finite element computer program was developed for the two-phased formulation of the combined soil-water problem. This formulation is based on the Biot dynamic equations of motion for both the solid and fluid phases of a typical soil. Frequency dependent interaction coefficients were generated for the two-dimensional plane problem of a rigid surface footing moving against a saturated linear soil. The results indicate that interaction coefficients are significantly modified as compared to the comparable values for a dry soil, particularly for the rocking mode of response. Calculations were made to study the impact of the modified interaction coefficients on the response of a typical nuclear reactor building. The amplification factors for a stick model placed atop a dry and saturated soil were computed. It was found that pore water caused the rocking response to decrease and translational response to increase over the frequency range of interest, as

  20. Study on the influence factors about the soil radon measurement

    International Nuclear Information System (INIS)

    Wu Zixiang; Liu Yanbin; Jia Yuxin; Mai Weiji; Liu Xiaolian; Yang Yuhua

    2006-01-01

    Objective: To explore relevant factors about the soil radon measurement and provide gist of formulating correct measure method by studying the way of the soil radon measurement. Methods: Deflation-ionization room standard is adopted. Results: The concentration of soil radon becomes higher with the sample's volume added, it also augmented with the measure depth increased in certain degree; The concentration of soil radon changes little when sample's depth is above 60 cm; The time of deflation has no obvious influence on the concentration of soil radon, but microwave show serious effect on it; The results will be lowered when the desiccant is humidified, raining has the same affection on it; Plant has some impact on it. Conclusion: The measured results will be affected by microwave, oscillate and plant. Sample's volume and depth, soil's humidity can influence it too. The result's veracity can be guaranteed by choosing appropriate sample and measure condition. (authors)

  1. Effect of N, P and K humates on dry matter of Zea mays and soil pH ...

    African Journals Online (AJOL)

    Ammonia volatilization from surface-applied urea reduces urea-N use efficiency in crop production and it also pollutes the environment; it is an economic loss. A greenhouse study was conducted to confirm the effect of similar fertilizer formulations (N, P and K humates) on soil pH, exchangeable ammonium, available nitrate ...

  2. Influence of physical and chemical properties of different soil types on optimal soil moisture for tillage

    Directory of Open Access Journals (Sweden)

    Vladimir Zebec

    2017-01-01

    Full Text Available Soil plasticity is the area of soil consistency, i.e. it represents a change in soil condition due to different soil moisture influenced by external forces activity. Consistency determines soil resistance in tillage, therefore, the aim of the research was to determine the optimum soil moisture condition for tillage and the influence of the chemical and physical properties of the arable land horizons on the soil plasticity on three different types of soil (fluvisol, luvisol and humic glaysol. Statistically significant differences were found between all examined soil types, such as the content of clay particles, the density of packaging and the actual and substitution acidity, the cation exchange capacity and the content of calcium. There were also statistically significant differences between the examined types of soil for the plasticity limit, liquid limit and the plasticity index. The average established value of plasticity limit as an important element for determining the optimal moment of soil tillage was 18.9% mass on fluvisol, 24.0% mass on luvisol and 28.6% mass on humic glaysol. Very significant positive direction correlation with plasticity limits was shown by organic matter, clay, fine silt, magnesium, sodium and calcium, while very significant negative direction correlation was shown by hydrolytic acidity, coarse sand, fine sand and coarse silt. Created regression models can estimate the optimal soil moisture condition for soil cultivation based on the basic soil properties. The model precision is significantly increased by introducing a greater number of agrochemical and agrophysical soil properties, and the additional precision of the model can be increased by soil type data.

  3. Fractionation and solubility of cadmium in paddy soils amended with porous hydrated calcium silicate.

    Science.gov (United States)

    Zhao, Xiu-Lan; Masaihiko, Saigusa

    2007-01-01

    Previous studies have shown that porous hydrated calcium silicate (PS) is very effective in decreasing cadmium (Cd) content in brown rice. However, it is unclear whether the PS influences cadmium transformation in soil. The present study examined the effect of PS on pH, cadmium transformation and cadmium solubility in Andosol and Alluvial soil, and also compared its effects with CaCO3, acidic porous hydrated calcium silicate (APS) and silica gel. Soil cadmium was operationally fractionationed into exchangeable (Exch), bound to carbonates (Carb), bound to iron and manganese oxides (FeMnO(x)), bound to organic matters (OM) and residual (Res) fraction. Application of PS and CaCO3 at hig rates enhanced soil pH, while APS and silica gel did not obviously change soil pH. PS and CaCO3 also increased the FeMnO(x)-Cd in Andosol and Carb-Cd in Alluvial soil, thus reducing the Exch-Cd in the tested soils. However, PS was less effective than CaCO3 at the same application rate. Cadmium fractions in the two soils were not changed by the treatments of APS and silica gel. There were no obvious differences in the solubility of cadmium in soils treated with PS, APS, silica gel and CaCO3 except Andosol treated 2.0% CaCO3 at the same pH of soil-CaCl2 suspensions. These findings suggested that the decrease of cadmium availability in soil was mainly attributed to the increase of soil pH caused by PS.

  4. Assessment of fly ash-aided phytostabilisation of highly contaminated soils after an 8-year field trial

    Energy Technology Data Exchange (ETDEWEB)

    Lopareva-Pohu, Alena [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geoEnvironnement Lille Nord de France EA 4515, 48 boulevard Vauban, 59046 Lille Cedex (France); Universite du Littoral-Cote d' Opale, Unite de Chimie Environnementale et Interactions sur le Vivant (UCEIV), EA4492, Maison de la Recherche en Environnement Industriel de Dunkerque 2, Avenue Maurice Schumann, 59140 Dunkerque (France); Pourrut, Bertrand; Waterlot, Christophe [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geoEnvironnement Lille Nord de France EA 4515, 48 boulevard Vauban, 59046 Lille Cedex (France); Garcon, Guillaume [Universite Lille Nord de France, Lille (France); Universite du Littoral-Cote d' Opale, Unite de Chimie Environnementale et Interactions sur le Vivant (UCEIV), EA4492, Maison de la Recherche en Environnement Industriel de Dunkerque 2, Avenue Maurice Schumann, 59140 Dunkerque (France); Bidar, Geraldine; Pruvot, Christelle [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geoEnvironnement Lille Nord de France EA 4515, 48 boulevard Vauban, 59046 Lille Cedex (France); Shirali, Pirouz [Universite Lille Nord de France, Lille (France); Universite du Littoral-Cote d' Opale, Unite de Chimie Environnementale et Interactions sur le Vivant (UCEIV), EA4492, Maison de la Recherche en Environnement Industriel de Dunkerque 2, Avenue Maurice Schumann, 59140 Dunkerque (France); Douay, Francis, E-mail: f.douay@isa-lille.fr [Universite Lille Nord de France, Lille (France); Groupe ISA, Equipe Sols et Environnement, Laboratoire Genie Civil et geoEnvironnement Lille Nord de France EA 4515, 48 boulevard Vauban, 59046 Lille Cedex (France)

    2011-01-01

    Sustainable management of large surface areas contaminated with trace elements is a real challenge, since currently applied remediation techniques are too expensive for these areas. Aided phytostabilisation appears to be a cost efficient technique to reduce metal mobility in contaminated soils and contaminated particle spread. In this context, this study aimed at evaluating the long-term efficiency of aided phytostabilisation on former agricultural soils highly contaminated with trace elements. The influence of afforestation and fly ash amendments to reduce metal mobility was investigated. Before being planted with a tree mix, the study site was divided into three plots: a reference plot with no amendment, the second amended with silico-aluminous fly ash and the third with sulfo-calcic fly ash. After eight years, some soil physico-chemical parameters, including cadmium (Cd), lead (Pb) and zinc (Zn) extractability were modified. In particular, pH decreased on the whole site while organic carbon content increased. The alteration of these parameters influencing trace element mobility is explained by afforestation. Over time, concentrations of CaCl{sub 2}-extractable metals increased and were correlated with the soil pH decrease. In the amended soils, extractable Cd, Pb and Zn concentrations were lower than in the reference soil. The results indicated that the two fly ashes buffered natural soil acidification due to vegetation development and limited trace element mobility and thus could limit their bioavailability. For long-term phytostabilisation, special attention should be focused on the soil pH, metal mobility and phytoavailability analysis. - Research Highlights: {yields} Afforestation leads to soil pH decrease and organic carbon content increase. {yields} Fly ashes buffered natural soil acidification. {yields} Fly ashes limited metal mobility.

  5. Assessment of fly ash-aided phytostabilisation of highly contaminated soils after an 8-year field trial

    International Nuclear Information System (INIS)

    Lopareva-Pohu, Alena; Pourrut, Bertrand; Waterlot, Christophe; Garcon, Guillaume; Bidar, Geraldine; Pruvot, Christelle; Shirali, Pirouz; Douay, Francis

    2011-01-01

    Sustainable management of large surface areas contaminated with trace elements is a real challenge, since currently applied remediation techniques are too expensive for these areas. Aided phytostabilisation appears to be a cost efficient technique to reduce metal mobility in contaminated soils and contaminated particle spread. In this context, this study aimed at evaluating the long-term efficiency of aided phytostabilisation on former agricultural soils highly contaminated with trace elements. The influence of afforestation and fly ash amendments to reduce metal mobility was investigated. Before being planted with a tree mix, the study site was divided into three plots: a reference plot with no amendment, the second amended with silico-aluminous fly ash and the third with sulfo-calcic fly ash. After eight years, some soil physico-chemical parameters, including cadmium (Cd), lead (Pb) and zinc (Zn) extractability were modified. In particular, pH decreased on the whole site while organic carbon content increased. The alteration of these parameters influencing trace element mobility is explained by afforestation. Over time, concentrations of CaCl 2 -extractable metals increased and were correlated with the soil pH decrease. In the amended soils, extractable Cd, Pb and Zn concentrations were lower than in the reference soil. The results indicated that the two fly ashes buffered natural soil acidification due to vegetation development and limited trace element mobility and thus could limit their bioavailability. For long-term phytostabilisation, special attention should be focused on the soil pH, metal mobility and phytoavailability analysis. - Research Highlights: → Afforestation leads to soil pH decrease and organic carbon content increase. → Fly ashes buffered natural soil acidification. → Fly ashes limited metal mobility.

  6. The pH Game.

    Science.gov (United States)

    Chemecology, 1996

    1996-01-01

    Describes a game that can be used to teach students about the acidity of liquids and substances around their school and enable them to understand what pH levels tell us about the environment. Students collect samples and measure the pH of water, soil, plants, and other natural material. (DDR)

  7. Vertebrate herbivores influence soil nematodes by modifying plant communities

    NARCIS (Netherlands)

    Veen, G. F. (Ciska); Olff, Han; Duyts, Henk; van der Putten, Wim H.

    Abiotic soil properties, plant community composition, and herbivory all have been reported as important factors influencing the composition of soil communities. However, most studies thus far have considered these factors in isolation, whereas they strongly interact in the field. Here, we study how

  8. Cobalt sorption onto Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1985-06-01

    A laboratory study of cobalt-60 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that cobalt sorption is most strongly a function of pH. Over a pH range of 2 to 9, the distribution coefficient ranged from 2 to more than 10,000 mL/g. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence cobalt sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect on cobalt sorption. Ferrous ion, added to groundwater to simulate the condition of water at the bottom of the waste trenches, accounts for part of the decrease in cobalt sorption observed with trench waters. 17 refs., 3 figs., 4 tabs

  9. Sorption and Transport of Pharmaceutical chemicals in Organic- and Mineral-rich Soils

    Science.gov (United States)

    Vulava, V. M.; Schwindaman, J.; Murphey, V.; Kuzma, S.; Cory, W.

    2011-12-01

    OC, again indicating that these PhACs preferentially partition into the soil OM. Such a correlation was absent for cetirizine. Breakthrough curves of PhACs measured in homogeneous packed soil columns indicated that PhAC transport was affected by chemical nonequilibrium processes depending on the soil and PhAC chemistry. The shape of the breakthrough curves indicated that there were two distinct sorption sites - OM and clay minerals - which influence nonequilibrium transport of these compounds. The retardation factor estimated using the distribution coefficient, Kd, measured from the sorption experiments was very similar to the measured value. While the sorption and transport data do not provide mechanistic information regarding the nature of PhAC interaction with chemical reactive components within geological materials, they do provide important information regarding potential fate of such compounds in the environment. The results also show the role that soil OM and mineral surfaces play in sequestering or transporting these chemicals. These insights have implications to the quality of the water resources in our communities.

  10. Furfural and its biochar improve the general properties of a saline soil

    Science.gov (United States)

    Wu, Y.; Xu, G.; Shao, H. B.

    2014-07-01

    Organic materials (e.g., furfural residue) are generally believed to improve the physical and chemical properties of saline soils with low fertility. Recently, biochar has been received more attention as a possible measure to improve the carbon balance and improve soil quality in some degraded soils. However, little is known about their different amelioration of a sandy saline soil. In this study, 56 d incubation experiment was conducted to evaluate the influence of furfural and its biochar on the properties of saline soil. The results showed that both furfural and biochar greatly reduced pH, increased soil organic carbon (SOC) content and cation exchange capacity (CEC), and enhanced the available phosphorus (P) in the soil. Furfural is more efficient than biochar in reducing pH: 5% furfural lowered the soil pH by 0.5-0.8 (soil pH: 8.3-8.6), while 5% biochar decreased by 0.25-0.4 due to the loss of acidity in pyrolysis process. With respect to available P, furfural addition at a rate of 5% increased available P content by 4-6 times in comparison to 2-5 times with biochar application. In reducing soil exchangeable sodium percentage (ESP), biochar is slightly superior to furfural because soil ESP reduced by 51% and 43% with 5% furfural and 5% biochar at the end of incubation. In addition, no significant differences were observed between furfural and biochar about their capacity to retain N, P in leaching solution and to increase CEC in soil. These facts may be caused by the relatively short incubation time. In general, furfural and biochar exhibited a different effect depending on the property: furfural was more effective in decreasing pH and increasing available P, whereas biochar played a more important role in increasing SOC and reducing ESP of saline soil.

  11. Controls on accumulation and soil solution partitioning of heavy metals across upland sites in United Kingdom (UK).

    Science.gov (United States)

    Zia, Afia; van den Berg, Leon; Ahmad, Muhammad Nauman; Riaz, Muhammad; Zia, Dania; Ashmore, Mike

    2018-05-31

    A significant body of knowledge suggests that soil solution pH and dissolved organic carbon (DOC) strongly influence metal concentrations and speciation in porewater, however, these effects vary between different metals. This study investigated the factors influencing soil and soil solution concentrations of copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) under field conditions in upland soils from UK having a wide range of pH, DOC and organic matter contents. The study primarily focussed on predicting soil and soil solution metal concentrations from the data on total soil metal concentrations (HNO 3 extracts) and soil and soil solution properties (pH, DOC and organic matter content). We tested the multiple regression models proposed by Tipping et al. (2003) to predict heavy metal concentrations in soil solutions and the results indicated a better fit (higher R 2 values) in both studies for Pb compared to the Zn and Cu concentrations. Both studies observed consistent negative relationships of metals with pH and loss on ignition (LOI) suggesting an increase in soil solution metal concentrations with increasing acidity. The positive relationship between Pb concentrations in porewater and HNO 3 extracts was similar for both studies, however, similar relationships were not found for the Zn and Cu concentrations because of the negative coefficients for these metals in our study. The results of this study conclude that the predictive equations of Tipping et al. (2003) may not be applicable to the field sites where the range of DOC and metal concentrations is much lower than their study. Our study also suggests that the extent to which metals are partitioned into soil solution is lower in soils with a higher organic matter contents due to binding of these metals to soil organic matter. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Effects of pH-Induced Changes in Soil Physical Characteristics on the Development of Soil Water Erosion

    Directory of Open Access Journals (Sweden)

    Shinji Matsumoto

    2018-04-01

    Full Text Available Soil water erosion is frequently reported as serious problem in soils in Southeast Asia with tropical climates, and the variations in pH affect the development of the erosion. This study investigated the effects of changes in pH on soil water erosion based on changes in the physical properties of the simulated soils with pH adjusted from 2.0 to 10.0 through artificial rainfall tests. The zeta potential was entirely shifted to positive direction at each pH condition due to Al, Ca, and Mg. In the pH range of 6.0 to 2.0, the aggregation of soil particles resulting from the release of Al3+ from clay minerals and/or molecular attraction between soil particles caused the plastic index (IP of the soil to decrease. The decrease in IP led to the development of soil water erosion at the pH range. When the pH exceeded 6.0, the repulsive force generated by the negative charges on soil particles decreased IP, resulting in accelerated erosion by water. The results suggest that changes in pH causes physical properties of the soil to change through changes of the zeta potential in the clayey soil rich in Al, Ca, and Mg, leading to the development of soil water erosion.

  13. Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.

    Science.gov (United States)

    Zampella, Mariavittoria; Adamo, Paola

    2010-01-01

    A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability.

  14. Chemodynamics of chromium reduction in soils: Implications to bioavailability

    Energy Technology Data Exchange (ETDEWEB)

    Choppala, Girish [Centre for Environmental Risk Assessment and Remediation, Building-X, University of South Australia, Mawson Lakes, South Australia 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, PO Box 486, Salisbury, South Australia 5106 (Australia); Bolan, Nanthi, E-mail: Nanthi.Bolan@unisa.edu.au [Centre for Environmental Risk Assessment and Remediation, Building-X, University of South Australia, Mawson Lakes, South Australia 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, PO Box 486, Salisbury, South Australia 5106 (Australia); Seshadri, Balaji [Centre for Environmental Risk Assessment and Remediation, Building-X, University of South Australia, Mawson Lakes, South Australia 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, PO Box 486, Salisbury, South Australia 5106 (Australia)

    2013-10-15

    Highlights: • Examined the effects of sorption, pH and C sources on Cr(VI) reduction and toxicity. • The rate of Cr(VI) reduction decreased with an increase in Cr(VI) adsorption and pH. • The proton dynamics in Cr(VI) reduction was assessed in relation to remediation. • A novel black carbon showed the highest reduction rate of Cr(VI) in soils. • Black carbon decreased the bioavailability and phytotoxicity of Cr(VI) in soils. -- Abstract: Chromium toxicity in soils can be mitigated by reduction of Cr(VI) to Cr(III) which is influenced by the presence of free Cr(VI) species in soil solution, and the supply of protons and electrons. In this study, the effects of Cr(VI) adsorption (i.e. availability of free Cr(VI) species in soil solution), soil pH (i.e. supply of protons) and three electron donor carbon sources [black carbon (BC), chicken manure biochar (CMB) and cow manure (CM)] on the reduction of Cr(VI) to Cr(III) in soils were investigated. The results indicated that the rate of Cr(VI) reduction decreased with an increase in Cr(VI) adsorption and soil pH, which is attributed to decreased supply of free Cr(VI) ions and protons, respectively. Among the three different amendments tested, BC showed the highest rate of Cr(VI) reduction followed by CM and CMB. Furthermore, addition of BC, CM and CMB decreased the bioavailability of Cr(VI) in contaminated soils. The high efficiency of BC on Cr(VI) reduction was due to the electron donor's functional groups such as phenolic, hydroxyl, carbonyl and amides. The study demonstrated that free form of Cr(VI) ions in soil solution and carbon amendments enriched with acidic functional groups favored the reduction of Cr(VI), thereby mitigating its bioavailability and toxicity in contaminated soils.

  15. Novel chelating agents for iron, manganese, zinc, and copper mixed fertilisation in high pH soil-less cultures.

    Science.gov (United States)

    López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

    2016-03-15

    Studies about simultaneous fertilisation with several micronutrients have increased in recent years, as Fe, Mn and Zn deficiencies may appear in the same culture conditions. In fertigation, the replacement of sulfates by synthetic chelates is essential in areas with high pH irrigation water and substrates. Ethylenediamine-N-(2-hydroxyphenylacetic acid)-N'-(4-hydroxyphenylacetic acid) (o,p-EDDHA) and ethylenediamine disuccinic acid (EDDS) are novel chelating agents whose efficacy in simultaneous fertilisation of Zn, Mn and Cu is unknown. This work evaluates the effectiveness of both ligands compared to traditional ligands (EDTA, HEEDTA and DTPA) applied as micronutrient chelate mixtures to soybean and navy bean plants grown in soil-less cultures at high pH by analysing the SPAD and micronutrient nutritional status, including the Composition Nutritional Diagnosis (CND) analysis tool. The application of micronutrients using o,p-EDDHA was more effective in providing Mn and Zn than traditional ligands or sulfates. The application using EDDS increased the Zn nutrition. The results are well correlated with the chemical stability of the formulations. The combined application of Mn and Zn as o,p-EDDHA chelates can represent a more effective source than traditional chelates in micronutrient fertiliser mixtures in soil-less cultures at a high pH. © 2015 Society of Chemical Industry.

  16. Effect of quick lime on physicochemical properties of clay soil

    Directory of Open Access Journals (Sweden)

    Bessaim Mohammed Mustapha

    2018-01-01

    Full Text Available Clay soils are known for their water sensitivity, which causes irreparable damage to any structure built on this type of soil. In order to avoid such problem, it is necessary to use various improvement and stabilization methods such as treatment with lime. This process has been used successfully in the field for decades. The addition of lime generates various physicochemical reactions within the soil such as cation exchange and pozzolanic reactions which are largely responsible for the improvement of the soil in question. This paper presents a study concerning the variation of physicochemical properties of clayey soil with the addition of quicklime at different percentages. Experiments were performed on two clayey soils (CL type in order to investigate the influence of quicklime on Atterberg limits and pH. These tests were carried out in an attempt to study and follow the development and progression of various reactions occurred within the soil with various lime percentages. The results show that the addition of quicklime causes a significant improvement in soil properties by reducing plasticity and thereby improves the soil workability. It can also be found that the addition of lime increase pH of soil, which allow activating pozzolanic reactions who tend to stabilize the soil in question by formation of cementitious compounds. Finally, the pH can be considered as a relevant parameter who allows a better understanding of the reactions that occur in the soil matrix.

  17. Soil Characteristics Driving Arbuscular Mycorrhizal Fungal Communities in Semiarid Mediterranean Soils.

    Science.gov (United States)

    Alguacil, Maria Del Mar; Torres, Maria Pilar; Montesinos-Navarro, Alicia; Roldán, Antonio

    2016-06-01

    We investigated communities of arbuscular mycorrhizal fungi (AMF) in the roots and the rhizosphere soil of Brachypodium retusum in six different natural soils under field conditions. We explored phylogenetic patterns of AMF composition using indicator species analyses to find AMF associated with a given habitat (root versus rhizosphere) or soil type. We tested whether the AMF characteristics of different habitats or contrasting soils were more closely related than expected by chance. Then we used principal-component analysis and multivariate analysis of variance to test for the relative contribution of each factor in explaining the variation in fungal community composition. Finally, we used redundancy analysis to identify the soil properties that significantly explained the differences in AMF communities across soil types. The results pointed out a tendency of AMF communities in roots to be closely related and different from those in the rhizosphere soil. The indicator species analyses revealed AMF associated with rhizosphere soil and the root habitat. Soil type also determined the distribution of AMF communities in soils, and this effect could not be attributed to a single soil characteristic, as at least three soil properties related to microbial activity, i.e., pH and levels of two micronutrients (Mn and Zn), played significant roles in triggering AMF populations. Communities of arbuscular mycorrhizal fungi (AMF) are main components of soil biota that can determine the productivity of ecosystems. These fungal assemblages vary across host plants and ecosystems, but the main ecological processes that shape the structures of these communities are still largely unknown. A field study in six different soil types from semiarid areas revealed that AMF communities are significantly influenced by habitat (soil versus roots) and soil type. In addition, three soil properties related to microbiological activity (i.e., pH and manganese and zinc levels) were the main factors

  18. Soil Characteristics Driving Arbuscular Mycorrhizal Fungal Communities in Semiarid Mediterranean Soils

    Science.gov (United States)

    Torres, Maria Pilar; Montesinos-Navarro, Alicia; Roldán, Antonio

    2016-01-01

    ABSTRACT We investigated communities of arbuscular mycorrhizal fungi (AMF) in the roots and the rhizosphere soil of Brachypodium retusum in six different natural soils under field conditions. We explored phylogenetic patterns of AMF composition using indicator species analyses to find AMF associated with a given habitat (root versus rhizosphere) or soil type. We tested whether the AMF characteristics of different habitats or contrasting soils were more closely related than expected by chance. Then we used principal-component analysis and multivariate analysis of variance to test for the relative contribution of each factor in explaining the variation in fungal community composition. Finally, we used redundancy analysis to identify the soil properties that significantly explained the differences in AMF communities across soil types. The results pointed out a tendency of AMF communities in roots to be closely related and different from those in the rhizosphere soil. The indicator species analyses revealed AMF associated with rhizosphere soil and the root habitat. Soil type also determined the distribution of AMF communities in soils, and this effect could not be attributed to a single soil characteristic, as at least three soil properties related to microbial activity, i.e., pH and levels of two micronutrients (Mn and Zn), played significant roles in triggering AMF populations. IMPORTANCE Communities of arbuscular mycorrhizal fungi (AMF) are main components of soil biota that can determine the productivity of ecosystems. These fungal assemblages vary across host plants and ecosystems, but the main ecological processes that shape the structures of these communities are still largely unknown. A field study in six different soil types from semiarid areas revealed that AMF communities are significantly influenced by habitat (soil versus roots) and soil type. In addition, three soil properties related to microbiological activity (i.e., pH and manganese and zinc levels

  19. Individual whey protein components influence lipid oxidation dependent on pH

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jacobsen, Charlotte

    In emulsions, lipid oxidation is expected to be initiated at the oil-water interface. The properties of the emulsifier used and the composition at the interface is therefore expected to be of great importance for the resulting oxidation. Previous studies have shown that individual whey protein...... by affecting the preferential adsorption of whey protein components at the interface. The aim of the study was to compare lipid oxidation in 10% fish oil-in-water emulsions prepared with 1% whey protein having either a high concentration of α-lactalbumin, a high concentration of β-lactoglobulin or equal...... amounts of the two. Emulsions were prepared at pH4 and pH7. Emulsions were characterized by their droplet sizes, viscosities, and contents of proteins in the water phase. Lipid oxidation was assessed by PV and secondary volatile oxidation products. Results showed that pH greatly influenced the oxidative...

  20. Predicting Soluble Nickel in Soils Using Soil Properties and Total Nickel.

    Science.gov (United States)

    Zhang, Xiaoqing; Li, Jumei; Wei, Dongpu; Li, Bo; Ma, Yibing

    2015-01-01

    Soil soluble nickel (Ni) concentration is very important for determining soil Ni toxicity. In the present study, the relationships between soil properties, total and soluble Ni concentrations in soils were developed in a wide range of soils with different properties and climate characteristics. The multiple regressions showed that soil pH and total soil Ni concentrations were the most significant parameters in predicting soluble Ni concentrations with the adjusted determination coefficients (Radj2) values of 0.75 and 0.68 for soils spiked with soluble Ni salt and the spiked soils leached with artificial rainwater to mimic field conditions, respectively. However, when the soils were divided into three categories (pH 8), they obtained better predictions with Radj2 values of 0.78-0.90 and 0.79-0.94 for leached and unleached soils, respectively. Meanwhile, the other soil properties, such as amorphous Fe and Al oxides and clay, were also found to be important for determining soluble Ni concentrations, indicating that they were also presented as active adsorbent surfaces. Additionally, the whole soil speciation including bulk soil properties and total soils Ni concentrations were analyzed by mechanistic speciation models WHAM VI and Visual MINTEQ3.0. It was found that WHAM VI provided the best predictions for the soils with pH 8. The Visual MINTEQ3.0 could provide better estimation for pH 8. These results indicated the possibility and applicability of these models to predict soil soluble Ni concentration by soil properties.

  1. Terrestrial soil pH and MAAT records based on the MBT/CBT in the southern South China Sea: implications for the atmospheric CO2 evolution in Southeast Asia

    Science.gov (United States)

    Dong, L.; Li, L.; Li, Q.; Zhang, C.

    2013-12-01

    Liang Dong1, Li Li1, Qianyu Li1,2, Chuanlun L. Zhang1,3 1State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 2School of Earth and Environment Sciences, University of Adelaide, SA 5005, Australia 3Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA The methylation index of branched tetraethers (MBT) and/or the cyclization ratio of branched tetraethers (CBT) are derived from the branched glycerol dialkyl Glycerol tetraethers (GDGTs) of bacterial origin and are widely used to reconstruct the terrestrial soil pH and mean annual air temperature (MAAT); however, these proxies are less frequently used in the oceanic settings. Here we provide the first high resolution records of soil pH and MAAT since the last glacial maximum based on the sedimentary core of MD05-2896 in the southern South China Sea. The MAAT record exhibited typical glacial and interglacial cycles and was consistent with the winter insolation variation. The pH values were lower (6.4-7) in the glacial time and higher (7-8.4) in the interglacial time. Changes in soil pH allowed the evaluation of changes in soil CO2 based on the atmosphere-soil CO2 balance. The results imply that the lower winter MAAT variation with a lower winter atmospheric CO2 concentration might have resulted in a higher pH in the interglacial period. Our records provide a new insight into the evolution of atmospheric CO2 between glacial and interglacial cycles in East Asia. Key words: South China Sea, MBT/CBT, b-GDGTs, MAAT, pH

  2. Shear bond strength of one-step self-etch adhesives: pH influence

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2015-01-01

    Background: The aim of this study was to compare the shear bond strength of four one-step self-etch adhesives with different pH values to enamel and dentin. Materials and Methods: In this in vitro study, 200 bovine permanent mandibular incisors were used. Four one-step self-etch adhesives with different pH values were tested both on enamel and on dentin: Adper™ Easy Bond Self-Etch Adhesive (pH = 0.8-1), Futurabond NR (pH=2), G-aenial Bond (pH = 1.5), Clearfil S3 Bond (pH = 2.7). After adhesive systems application, a nanohybrid composite resin was inserted into the bonded surface. The specimens were placed in a universal testing machine. The shear bond strength was performed at a cross-head speed of 1 mm/min until the sample rupture. The shear bond strength values (MPa) of the different groups were compared with analysis of variance after that Kolmogorov and Smirnov tests were applied to assess normality of distributions. P enamel shear bond strength, the highest shear bond strength values were reported with Futurabond NR (P adhesive systems showed lower shear bond strength values with significant differences between them (P 0.05). Conclusion: The pH values of adhesive systems did not influence significantly their shear bond strength to enamel or dentin. PMID:26005459

  3. Contrasting elevational diversity patterns for soil bacteria between two ecosystems divided by the treeline.

    Science.gov (United States)

    Li, Guixiang; Xu, Guorui; Shen, Congcong; Tang, Yong; Zhang, Yuxin; Ma, Keming

    2016-11-01

    Above- and below-ground organisms are closely linked, but how elevational distribution pattern of soil microbes shifting across the treeline still remains unknown. Sampling of 140 plots with transect, we herein investigated soil bacterial distribution pattern from a temperate forest up to a subalpine meadow along an elevational gradient using Illumina sequencing. Our results revealed distinct elevational patterns of bacterial diversity above and below the treeline in responding to changes in soil conditions: a hollow elevational pattern in the forest (correlated with soil temperature, pH, and C:N ratio) and a significantly decreasing pattern in the meadow (correlated with soil pH, and available phosphorus). The bacterial community structure was also distinct between the forest and meadow, relating to soil pH in the forest and soil temperature in the meadow. Soil bacteria did not follow the distribution pattern of herb diversity, but bacterial community structure could be predicted by herb community composition. These results suggest that plant communities have an important influence on soil characteristics, and thus change the elevational distribution of soil bacteria. Our findings are useful for future assessments of climate change impacts on microbial community.

  4. Toxin production in food as influenced by pH, thermal treatment and ...

    African Journals Online (AJOL)

    Toxin production in food as influenced by pH, thermal treatment and chemical ... carrot, spinach, pepper, tomato, onion and cooked food samples (rice, yam, beans, ... on the growth rate and toxin elaboration of E. coli, K. aerogenes, C. freundii, ...

  5. Developing and using artificial soils to analyze soil microbial processes

    Science.gov (United States)

    Gao, X.; Cheng, H. Y.; Boynton, L.; Masiello, C. A.; Silberg, J. J.

    2017-12-01

    Microbial diversity and function in soils are governed by soil characteristics such as mineral composition, particles size and aggregations, soil organic matter (SOM), and availability of nutrients and H2O. The spatial and temporal heterogeneity of soils creates a range of niches (hotspots) differing in the availability of O2, H2O, and nutrients, which shapes microbial activities at scales ranging from nanometer to landscape. Synthetic biologists often examine microbial response trigged by their environment conditions in nutrient-rich aqueous media using single strain microbes. While these studies provided useful insight in the role of soil microbes in important soil biogeochemical processes (e.g., C cycling, N cycling, etc.), the results obtained from the over-simplified model systems are often not applicable natural soil systems. On the contrary, soil microbiologists examine microbial processes in natural soils using longer incubation time. However, due to its physical, chemical and biological complexity of natural soils, it is often difficult to examine soil characteristics independently and understand how each characteristic influences soil microbial activities and their corresponding soil functioning. Therefore, it is necessary to bridge the gap and develop a model matrix to exclude unpredictable influences from the environment while still reliably mimicking real environmental conditions. The objective of this study is to design a range of ecologically-relevant artificial soils with varying texture (particle size distribution), structure, mineralogy, SOM content, and nutrient heterogeneity. We thoroughly characterize the artificial soils for pH, active surface area and surface morphology, cation exchange capacity (CEC), and water retention curve. We demonstrate the effectiveness of the artificial soils as useful matrix for microbial processes, such as microbial growth and horizontal gene transfer (HGT), using the gas-reporting biosensors recently developed in

  6. Migration of heavy metals in soil as influenced by compost amendments

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Mark, E-mail: m.farrell@bangor.ac.u [School of the Environment and Natural Resources, Bangor University, Gwynedd LL57 2UW (United Kingdom); Perkins, William T. [Institute of Geography and Earth Sciences, Aberystwyth University, Ceredigion SY23 3DB (United Kingdom); Hobbs, Phil J. [North Wyke Research, Okehampton, Devon EX20 2SB (United Kingdom); Griffith, Gareth W. [Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion SY23 3DA (United Kingdom); Jones, Davey L. [School of the Environment and Natural Resources, Bangor University, Gwynedd LL57 2UW (United Kingdom)

    2010-01-15

    Soils contaminated with heavy metals can pose a major risk to freshwaters and food chains. In this study, the success of organic and inorganic intervention strategies to alleviate toxicity in a highly acidic soil heavily contaminated with As, Cu, Pb, and Zn was evaluated over 112 d in a mesocosm trial. Amelioration of metal toxicity was assessed by measuring changes in soil solution chemistry, metal leaching, plant growth, and foliar metal accumulation. Either green waste- or MSW-derived composts increased plant yield and rooting depth, reduced plant metal uptake, and raised the pH and nutrient status of the soil. We conclude that composts are well suited for promoting the re-vegetation of contaminated sites; however, care must be taken to ensure that very short-term leaching pulses of heavy metals induced by compost amendment are not of sufficient magnitude to cause contamination of the wider environment. - Composts increase rooting depth and vegetation growth over inorganic amendment in an acidic, contaminated soil.

  7. Migration of heavy metals in soil as influenced by compost amendments

    International Nuclear Information System (INIS)

    Farrell, Mark; Perkins, William T.; Hobbs, Phil J.; Griffith, Gareth W.; Jones, Davey L.

    2010-01-01

    Soils contaminated with heavy metals can pose a major risk to freshwaters and food chains. In this study, the success of organic and inorganic intervention strategies to alleviate toxicity in a highly acidic soil heavily contaminated with As, Cu, Pb, and Zn was evaluated over 112 d in a mesocosm trial. Amelioration of metal toxicity was assessed by measuring changes in soil solution chemistry, metal leaching, plant growth, and foliar metal accumulation. Either green waste- or MSW-derived composts increased plant yield and rooting depth, reduced plant metal uptake, and raised the pH and nutrient status of the soil. We conclude that composts are well suited for promoting the re-vegetation of contaminated sites; however, care must be taken to ensure that very short-term leaching pulses of heavy metals induced by compost amendment are not of sufficient magnitude to cause contamination of the wider environment. - Composts increase rooting depth and vegetation growth over inorganic amendment in an acidic, contaminated soil.

  8. Differences in sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid on artificial soils as a function of soil pre-aging.

    Science.gov (United States)

    Waldner, Georg; Friesl-Hanl, Wolfgang; Haberhauer, Georg; Gerzabek, Martin H

    The sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) to three different artificial soil mixtures was investigated. Artificial soils serve as model systems for improving understanding of sorption phenomena. The soils consisted of quartz, ferrihydrite, illite, montmorillonite, and charcoal. In a previous study, several selected mixtures had been inoculated with organic matter, and microbial aging (incubation) had been performed for different periods of time (3, 12, and 18 months) before conducting the sorption experiments. The effect of this pre-incubation time on the sorption behavior was determined. Interaction of MCPA with soil surfaces was monitored by aqueous phase sorption experiments, using high-performance liquid chromatography/ultraviolet and in selected cases Fourier-transformed infrared spectroscopy. The sorption behavior showed large differences between differently aged soils; Freundlich and linear sorption model fits (with sorption constants K f , 1/ n exponents, and K d values, respectively) were given for pH = 3 and the unbuffered pH of ∼7. The largest extent of sorption from diluted solutions was found on the surfaces with a pre-incubation time of 3 months. Sorption increased at acidic pH values. Regarding the influence of aging of artificial soils, the following conclusions were drawn: young artificial soils exhibit stronger sorption at lower concentrations, with a larger K f value than aged soils. A correlation with organic carbon content was not confirmed. Thus, the sorption characteristics of the soils are more influenced by the aging of the organic carbon than by the organic carbon content itself.

  9. Soil geochemical parameters influencing the spatial distribution of anthrax in Northwest Minnesota, USA

    International Nuclear Information System (INIS)

    Nath, Samuel; Dere, Ashlee

    2016-01-01

    Bacillus anthracis is the pathogenic bacterium that causes anthrax, which dwells in soils as highly resilient endospores. B. anthracis spore viability in soil is dependent upon environmental conditions, but the soil properties necessary for spore survival are unclear. In this study we used a range of soil geochemical and physical parameters to predict the spatial distribution of B. anthracis in northwest Minnesota, where 64 cases of anthrax in livestock were reported from 2000 to 2013. Two modeling approaches at different spatial scales were used to identify the soil conditions most correlated to known anthrax cases using both statewide and locally collected soil data. Ecological niche models were constructed using the Maximum Entropy (Maxent) approach and included 11 soil parameters as environmental inputs and recorded anthrax cases as known presences. One ecological niche model used soil data and anthrax presences for the entire state while a second model used locally sampled soil data (n = 125) and a subset of anthrax presences, providing a test of spatial scale. In addition, simple logistic regression models using the localized soil data served as an independent measure of variable importance. Maxent model results indicate that at a statewide level, soil calcium and magnesium concentrations, soil pH, and sand content are the most important properties for predicting soil suitability for B. anthracis while at the local level, clay and sand content along with phosphorous and strontium concentrations are most important. These results also show that the spatial scale of analysis is important when considering soil parameters most important for B. anthracis spores. For example, at a broad scale, B. anthracis spores may require Ca-rich soils and an alkaline pH, but may also concentrate in microenvironments with high Sr concentrations. The study is also one of the first ecological niche models that demonstrates the major importance of soil texture for defining

  10. Influence of management history and landscape variables on soil organic carbon and soil redistribution

    Science.gov (United States)

    Venteris, E.R.; McCarty, G.W.; Ritchie, J.C.; Gish, T.

    2004-01-01

    Controlled studies to investigate the interaction between crop growth, soil properties, hydrology, and management practices are common in agronomy. These sites (much as with real world farmland) often have complex management histories and topographic variability that must be considered. In 1993 an interdisiplinary study was started for a 20-ha site in Beltsville, MD. Soil cores (271) were collected in 1999 in a 30-m grid (with 5-m nesting) and analyzed as part of the site characterization. Soil organic carbon (SOC) and 137Cesium (137Cs) were measured. Analysis of aerial photography from 1992 and of farm management records revealed that part of the site had been maintained as a swine pasture and the other portion as cropped land. Soil properties, particularly soil redistribution and SOC, show large differences in mean values between the two areas. Mass C is 0.8 kg m -2 greater in the pasture area than in the cropped portion. The pasture area is primarily a deposition site, whereas the crop area is dominated by erosion. Management influence is suggested, but topographic variability confounds interpretation. Soil organic carbon is spatially structured, with a regionalized variable of 120 m. 137Cs activity lacks spatial structure, suggesting disturbance of the profile by animal activity and past structures such as swine shelters and roads. Neither SOC nor 137Cs were strongly correlated to terrain parameters, crop yields, or a seasonal soil moisture index predicted from crop yields. SOC and 137Cs were weakly correlated (r2 ???0.2, F-test P-value 0.001), suggesting that soil transport controls, in part, SOC distribution. The study illustrates the importance of past site history when interpreting the landscape distribution of soil properties, especially those strongly influenced by human activity. Confounding variables, complex soil hydrology, and incomplete documentation of land use history make definitive interpretations of the processes behind the spatial distributions

  11. Prolonged acid rain facilitates soil organic carbon accumulation in a mature forest in Southern China.

    Science.gov (United States)

    Wu, Jianping; Liang, Guohua; Hui, Dafeng; Deng, Qi; Xiong, Xin; Qiu, Qingyan; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

    2016-02-15

    With the continuing increase in anthropogenic activities, acid rain remains a serious environmental threat, especially in the fast developing areas such as southern China. To detect how prolonged deposition of acid rain would influence soil organic carbon accumulation in mature subtropical forests, we conducted a field experiment with simulated acid rain (SAR) treatments in a monsoon evergreen broadleaf forest at Dinghushan National Nature Reserve in southern China. Four levels of SAR treatments were set by irrigating plants with water of different pH values: CK (the control, local lake water, pH ≈ 4.5), T1 (water pH=4.0), T2 (water pH=3.5), and T3 (water pH=3.0). Results showed reduced pH measurements in the topsoil exposed to simulated acid rains due to soil acidification. Soil respiration, soil microbial biomass and litter decomposition rates were significantly decreased by the SAR treatments. As a result, T3 treatment significantly increased the total organic carbon by 24.5% in the topsoil compared to the control. Furthermore, surface soil became more stable as more recalcitrant organic matter was generated under the SAR treatments. Our results suggest that prolonged acid rain exposure may have the potential to facilitate soil organic carbon accumulation in the subtropical forest in southern China. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. pH control for enhanced reductive bioremediation of chlorinated solvent source zones

    International Nuclear Information System (INIS)

    Robinson, Clare; Barry, D.A.; McCarty, Perry L.; Gerhard, Jason I.; Kouznetsova, Irina

    2009-01-01

    Enhanced reductive dehalogenation is an attractive treatment technology for in situ remediation of chlorinated solvent DNAPL source areas. Reductive dehalogenation is an acid-forming process with hydrochloric acid and also organic acids from fermentation of the electron donors typically building up in the source zone during remediation. This can lead to groundwater acidification thereby inhibiting the activity of dehalogenating microorganisms. Where the soils' natural buffering capacity is likely to be exceeded, the addition of an external source of alkalinity is needed to ensure sustained dehalogenation. To assist in the design of bioremediation systems, an abiotic geochemical model was developed to provide insight into the processes influencing the groundwater acidity as dehalogenation proceeds, and to predict the amount of bicarbonate required to maintain the pH at a suitable level for dehalogenating bacteria (i.e., > 6.5). The model accounts for the amount of chlorinated solvent degraded, site water chemistry, electron donor, alternative terminal electron-accepting processes, gas release and soil mineralogy. While calcite and iron oxides were shown to be the key minerals influencing the soil's buffering capacity, for the extensive dehalogenation likely to occur in a DNAPL source zone, significant bicarbonate addition may be necessary even in soils that are naturally well buffered. Results indicated that the bicarbonate requirement strongly depends on the electron donor used and availability of competing electron acceptors (e.g., sulfate, iron (III)). Based on understanding gained from this model, a simplified model was developed for calculating a preliminary design estimate of the bicarbonate addition required to control the pH for user-specified operating conditions.

  13. Study of the trace metal ion influence on the turnover of soil organic matter in cultivated contaminated soils

    International Nuclear Information System (INIS)

    Dumat, C.; Quenea, K.; Bermond, A.; Toinen, S.; Benedetti, M.F.

    2006-01-01

    The role of metals in the behaviour of soil organic matter (SOM) is not well documented. Therefore, we investigated the influence of metals (Pb, Zn, Cu and Cd) on the dynamic of SOM in contaminated soils where maize (C 4 plant) replaced C 3 cultures. Three pseudogley brown leached soil profiles under maize with a decreasing gradient in metals concentrations were sampled. On size fractions, stable carbon isotopic ratio (δ 13 C), metals, organic carbon and nitrogen concentrations were measured in function of depth. The determined sequence for the amount of C 4 organic matter in the bulk fractions: M 3 (0.9) > M 2 (0.4) > M 1 (0.3) is in agreement with a significant influence of metals on the SOM turnover. New C 4 SOM, mainly present in the labile coarser fractions and less contaminated by metals than the stabilised C 3 SOM of the clay fraction, is more easily degraded by microorganisms. - Measure of δ 13 C and total metal concentrations in size fractions of contaminated soils suggests an influence of metals on the soil organic matter dynamic

  14. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    International Nuclear Information System (INIS)

    Roemkens, P.F.A.M.; Brus, D.J.; Guo, H.Y.; Chu, C.L.; Chiang, C.M.; Koopmans, G.F.

    2011-01-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal content, pH, and CEC or soil Cd and Zn extracted by 0.01 M CaCl 2 as explanatory variables. The models were validated against a set of 2300 data points not used in the calibration. These models were then used inversely to derive soil quality standards for Japonica and Indica rice cultivars based on the food quality standards for rice. To account for model uncertainty, strict soil quality standards were derived considering a maximum probability that rice exceeds the food quality standard equal to 10 or 5%. Model derived soil standards based on Aqua Regia ranged from less than 0.3 mg kg -1 for Indica at pH 4.5 to more than 6 mg kg -1 for Japonica-type cultivars in clay soils at pH 7. Based on the CaCl 2 extract, standards ranged from 0.03 mg kg -1 Cd for Indica cultivars to 0.1 mg kg -1 Cd for Japonica cultivars. For both Japonica and Indica-type cultivars, the soil quality standards must be reduced by a factor of 2 to 3 to obtain the strict standards. The strong impact of pH and CEC on soil quality standards implies that it is essential to correct for soil type when deriving national or local standards. Validation on the remaining 2300 samples indicated that both types of models were able to accurately predict (> 92%) whether rice grown on a specific soil will meet the food quality standard used in Taiwan. - Research highlights: → Cadmium uptake by Japonica and Indica rice varieties depends on soil pH and CEC. → Food safety based soil standards range from 0.3 (Indica) to 6 mg kg -1 (Japonica). → Model uncertainty leads to strict soil standards of less than 0.1 mg kg -1 for Indica. → Soil pH and CEC should be considered to obtain meaningful standards for agriculture.

  15. Topographic variability influences the carbon sequestration potential of arable soils

    DEFF Research Database (Denmark)

    Chirinda, Ngoni; Elsgaard, Lars; Thomsen, Ingrid Kaag

    2012-01-01

    There is presently limited knowledge on the influence of field spatial variability on the carbon (C) sink-source relationships in arable landscapes. This is accompanied by the fact that our understanding of soil profile C dynamics is also limited. This study aimed at investigating how spatial...... results indicated that variability across arable landscapes makes footslope soils both a larger sink of buried soil C and a bigger potential CO2 source than upslope soils....

  16. The Influence of Pb and Zn Contaminated soil on the Germination ...

    African Journals Online (AJOL)

    Journal of Applied Sciences and Environmental Management ... The bambara nut seedlings were irrigated with various concentrations of Pb and Zn ... as well as the organic matter, pH and moisture content of the soil were also evaluated. ... down to humans through the food chain if animals eat such plants during grazing.

  17. Availability of potassium in biomass combustion ashes and gasification biochars after application to soils with variable pH and clay content

    DEFF Research Database (Denmark)

    Li, Xiaoxi; Rubæk, Gitte Holton; Sørensen, Peter

    2017-01-01

    .8–7.8) and clay contents (3–17%). Exchangeable K in the product-soil mixture was determined, and the K recovery rate from the applied products varied from 31 to 86%. The relative recovery compared to applied KCl was used to indicate K availability and was 50–86% across all soils, but lower for two sewage sludge....... The objective of this study was to evaluate the potassium (K) availability in various types of biomass ashes and gasification biochars (GBs) derived from straw, wood, sewage sludge and poultry manure when mixed with soil. A 16-week incubation study was conducted with three contrasting soils of variable pH (5...

  18. Evaluation of carbaryl sorption in alluvial soil

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2013-12-01

    Full Text Available This study investigated the adsorption potential of carbaryl onto alluvial soil. Parameters that influence the adsorption process such as pH, adsorbent dose, initial carbaryl concentration, stirring rate, particle size, contact time and temperature were studied in a batch process. The carbaryl adsorption capacity was at maximum at pH 6 for an initial concentration of 20 ppm. Adsorption equilibirium time was observed in 180 min. Equilibrium adsorption data was best fitted with Freundlich isotherm and pseudo-first order kinetic model, respectively. The adsorbent was characterized by X-ray diffraction spectrum, Fourier transform infrared spectroscopy and scanning electron microscopy. The experiment performed indicated that the adsorption capacity of carbaryl was significantly correlated with particle size, organic matter and pH of the soil. Therefore, the possibility for carbaryl to contaminate underground water may be greater in the presence of low organic matter content.

  19. Net carbon allocation in soybean seedlings as influenced by soil water stress at two soil temperatures

    International Nuclear Information System (INIS)

    McCoy, E.L.; Boersma, L.; Ekasingh, M.

    1990-01-01

    The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14 C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0.25 and -0.50 MPa; and soil temperatures of 25 and 10C. Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and partitioning of carbon to the sink tissues increased with moderate water stress at 25C soil temperature. Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis

  20. Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated rice soils

    International Nuclear Information System (INIS)

    Kuo, S.; Lai, M.S.; Lin, C.W.

    2006-01-01

    Soil washing is considered a useful technique for remediating metal-contaminated soils. This study examined the release edges of Cd, Zn, Ni, Cr, Cu or Pb in two contaminated rice soils from central Taiwan. The concentrations exceeding the trigger levels established by the regulatory agency of Taiwan were Cu, Zn, Ni and Cr for the Ho-Mei soil and Pb for the Nan-Tou soil. Successive extractions with HCl ranging from 0 to 0.2 M showed increased release of the heavy metals with declining pH, and the threshold pH value below which a sharp increase in the releases of the heavy metals was highest for Cd, Zn, and Ni (pH 4.6 to 4.9), intermediate for Pb and Cu (3.1 to 3.8) and lowest for Fe (2.1), Al (2.2) and Cr (1.7) for the soils. The low response slope of Ni and Cr particularly for the rice soils make soil washing with the acid up to the highest concentration used ineffective to reduce their concentrations to below trigger levels. Although soil washing with 0.1 M HCl was moderately effective in reducing Cu, Pb, Zn and Cd, which brought pH of the soils to 1.1 ± 0.1 (S.D.), the concurrent release of large quantities of Fe and Al make this remediation technique undesirable for the rice soils containing high clay. Successive washings with 0.01 M HCl could be considered an alternative as the dissolution of Fe and Al was minimal, and between 46 to 64% of Cd, Zn, and Cu for the Ho-Mei soil and 45% of Pb in the Na-Tou soil were extracted after four successive extractions with this dilute acid solution. The efficacy of Cd extraction improved if CaCl 2 was added to the acid solution. The correlation analysis revealed that Cr extracted was highly correlated (P < 0.001) with Fe extracted, whereas the Cu, Ni, Zn, Cd or Pb extracted was better correlated (P < 0.001) with Al than with Fe extracted. It is possible that the past seasonal soil flooding and drainage in the soils for rice production was conducive to incorporating Cr within the structure of Fe oxide, thereby making them

  1. Transfer of Ni, Cr, Zn, Cu and 99mTc to plant biomass of Raphanus sativus L. Role of 125I-fulvic acid and the influence of different treatments on urban soil in Havana

    International Nuclear Information System (INIS)

    Santana Romero, Jorge Luis; Diaz Velazquez, Alberto; Garcia Cespedes, Damaris; Lima Cazorla, Lazaro; Saborit Sanchez, Israel; Olivares Rieumont, Susana; Rivas, Edgar; Manduca, Michel

    2011-01-01

    The importance of studying the transfer of heavy metals from soil to plant biomass is a current scientific topic. The global economic changes have caused accelerated environmental degradation processes in urban soils, in which important amount of agricultural production is obtained. The application of 'ecological' techniques on these soils, including the use of vermicompost, is be-coming more and more extensive and common. The question is: Is always safe and pertinent to apply vermicompost to urban soils?. Hence the importance of studying the heavy metal mobility and bioavailability to plant biomass in these conditions. In the present work, using different analytical techniques, a sample of Havana urban soil is characterized by determination of ph, electrical conductivity, organic material content and the total and EDTA extractable Ni, Cr, Zn and Cu levels. Fulvic acid was extracted from vermicompost and chemically characterized as well as its ability to chelate metals. The conditional stability constant, K of the fulvic acid-copper complex at different ph values was determined (log K cond = 7.39) using size-exclusion chromatography method. The Ni, Cr, Zn and Cu transfer study was conducted using biomass of Raphanus sativus L. The result shows significative statistical agreement with proposed experimental design 2 4-1 and allowed us to recognize the significant positive influence of factors such as the addition of Cu as possible pollutant in soil, ph, addition of fulvic acid and the time of addition of fulvic acid (vermicompost) at different physiological stages of plant development in increasing the bioavailability of Cu into plant biomass studied. The application of radiochemical methods with the use of fulvic acid labeled with 99mTc and 125I respectively allowed to ratify the influence of the factors studied on the transfer of heavy metals into biomass in terms of urban soil. It was possible to determine that the fulvic acid acts as a heavy metals transporter in

  2. Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils

    International Nuclear Information System (INIS)

    Rhind, S.M.; Kyle, C.E.; Kerr, C.; Osprey, M.; Zhang, Z.L.; Duff, E.I.; Lilly, A.; Nolan, A.; Hudson, G.; Towers, W.; Bell, J.; Coull, M.; McKenzie, C.

    2013-01-01

    Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0–5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. -- Highlights: •Concentrations of selected organic pollutants in Scottish soils were determined. •Concentrations were highly variable. •There were few effects of soil or vegetation type, soil carbon, pH or altitude. •Distance from cities was not an important determinant of concentrations. •Atmospheric deposition and soil organic carbon content may affect concentrations. -- Soil concentrations of anthropogenic persistent organic pollutants are not clearly related to soil type or pH, vegetation, altitude, or distance from pollutant sources

  3. The influence of bioturbation on the vertical distribution of soil organic matter in volcanic ash soils: a case study in northern Ecuador

    NARCIS (Netherlands)

    Tonneijck, F.H.; Jongmans, A.G.

    2008-01-01

    Soil faunal bioturbation ('bioturbation') is often cited as a major process influencing the vertical distribution of soil organic matter (SOM). The influence of bioturbation on vertical SOM transport is complex because it is the result of interaction between different groups of soil faunal species

  4. Ph influence on acidogenic dissimilation of glucose in an anaerobic digestor

    Energy Technology Data Exchange (ETDEWEB)

    Zoetemeyer, R J; van den Heuvel, J C; Cohen, A

    1982-01-01

    The paper describes a study of the influence of the pH value on acidogenesis, with reference to maximum specific growth rate and product distribution at various dilution rates, in order to optimize product distribution with respect to the more sensitive methanogenic stage. Glucose was used as the carbon-limiting substrate as its acidogenesis is rate limiting. 18 refs.

  5. Soil properties influence kinetics of soil acid phosphatase in response to arsenic toxicity.

    Science.gov (United States)

    Wang, Ziquan; Tan, Xiangping; Lu, Guannan; Liu, Yanju; Naidu, Ravi; He, Wenxiang

    2018-01-01

    Soil phosphatase, which plays an important role in phosphorus cycling, is strongly inhibited by Arsenic (As). However, the inhibition mechanism in kinetics is not adequately investigated. In this study, we investigated the kinetic characteristics of soil acid phosphatase (ACP) in 14 soils with varied properties, and also explored how kinetic properties of soil ACP changed with different spiked As concentrations. The results showed that the Michaelis constant (K m ) and maximum reaction velocity (V max ) values of soil ACP ranged from 1.18 to 3.77mM and 0.025-0.133mMh -1 in uncontaminated soils. The kinetic parameters of soil ACP in different soils changed differently with As contamination. The K m remained unchanged and V max decreased with increase of As concentration in most acid and neutral soils, indicating a noncompetitive inhibition mechanism. However, in alkaline soils, the K m increased linearly and V max decreased with increase of As concentration, indicating a mixed inhibition mechanism that include competitive and noncompetitive. The competitive inhibition constant (K ic ) and noncompetitive inhibition constant (K iu ) varied among soils and ranged from 0.38 to 3.65mM and 0.84-7.43mM respectively. The inhibitory effect of As on soil ACP was mostly affected by soil organic matter and cation exchange capacity. Those factors influenced the combination of As with enzyme, which resulted in a difference of As toxicity to soil ACP. Catalytic efficiency (V max /K m ) of soil ACP was a sensitive kinetic parameter to assess the ecological risks of soil As contamination. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Long-Term Coffee Monoculture Alters Soil Chemical Properties and Microbial Communities.

    Science.gov (United States)

    Zhao, Qingyun; Xiong, Wu; Xing, Yizhang; Sun, Yan; Lin, Xingjun; Dong, Yunping

    2018-04-17

    Long-term monoculture severely inhibits coffee plant growth, decreases its yield and results in serious economic losses in China. Here, we selected four replanted coffee fields with 4, 18, 26 and 57 years of monoculture history in Hainan China to investigate the influence of continuous cropping on soil chemical properties and microbial communities. Results showed long-term monoculture decreased soil pH and organic matter content and increased soil EC. Soil bacterial and fungal richness decreased with continuous coffee cropping. Principal coordinate analysis suggested monoculture time was a major determinant of bacterial and fungal community structures. Relative abundances of bacterial Proteobacteria, Bacteroidetes and Nitrospira and fungal Ascomycota phyla decreased over time. At genus level, potentially beneficial microbes such as Nitrospira and Trichoderma, significantly declined over time and showed positive relationships with coffee plant growth in pots. In conclusion, continuous coffee cropping decreased soil pH, organic matter content, potentially beneficial microbes and increased soil EC, which might lead to the poor growth of coffee plants in pots and decline of coffee yields in fields. Thus, developing sustainable agriculture to improve soil pH, organic matter content, microbial activity and reduce the salt stress under continuous cropping system is important for coffee production in China.

  7. Influence of the soil-atmosphere exchange on the hydric profile induced in soil-structure system

    Directory of Open Access Journals (Sweden)

    A. Al Qadad

    2012-06-01

    Full Text Available Soil-atmosphere exchange leads to a moisture change in the soil. This can cause major damage to engineering structures due to the soil expansion and shrinkage. The soil-atmosphere exchange is related to several parameters, in particular the soil characteristics and climate conditions. The presence of an engineering structure causes a variation of the hydraulic profile in the soil, which can lead to heterogeneous soil movement and consequently to structural damage. This paper presents a coupled numerical model based on the consideration of both water flow in unsaturated soils and soil-atmosphere exchange. After the validation of the model, the paper presents its use for the analysis of the influence of the presence of structures on moisture change induced under climatic conditions recorded in a semi-arid region. Analysis shows that the presence of the structure leads to important change in the moisture distribution, in particular in the vicinity of the structure.

  8. Effect of pH on sludge composting

    International Nuclear Information System (INIS)

    Hashimoto, Shoji; Watanabe, Hiromasa; Nishimura, Koichi; Kawakami, Waichiro

    1984-01-01

    The effect of pH on composting of irradiated sewage sludge was discussed. Inorganic materials, such as activated alumina, Kanuma-soil, and Akadama-soil, were used as bulking agents. Na 2 CO 3 was used as a pH adjuster. The fermentations were done isothermally at the optimum temperature, 50 0 C. The rate of CO 2 evolution increased initially with time, and then, decreased. The peak value of CO 2 evolution and the time to attain the peak varied by the addition of Na 2 CO 3 . When Kanuma-soil was used as the bulking agent, for example, the peak value became larger as the amount of Na 2 CO 3 was increased to 1.0 % and became smaller over this value. From pH measurements, it was found that the optimum pH for fermentation was ranged from 6 to 8 when activated alumina was used. When other bulking agents were used, the maximum value of CO 2 evolution rate was obtained at pH 7 to 8.5. The peak value and the peak time also varied by the addition of NH 3 in the aeration gas. (author)

  9. Meia-vida do ametryn em argissolo vermelho-amarelo e latossolo vermelho-amarelo, com diferentes valores de pH Determination of half-life of ametryn on red-yellow latosol and red-yellow ultisol with different pH values

    Directory of Open Access Journals (Sweden)

    S.R.B. Andrade

    2010-06-01

    .9, collected in degraded pastures without herbicide application. Ametryn was applied on these soil samples at a dose of 5.0 ha L-1. Twelve hours after application, the first soil samples were extracted from the pots to determine the concentration at zero time, and every five days new samples were removed from the other pots (two per time to determine ametryn concentration over time. Ametryn extraction from the soil matrix was performed by Solid Liquid Extraction with Partition at Low Temperature (SLE-PLT and quantified by liquid chromatography. A biological test for indirect determination of herbicide persistence was also carried out. Results indicated that ametryn half-life (t½ on the soils evaluated was 26, 19, 12 and 11 days in LVA soil pH 4.4; pH 4.9; pH 5.8 and PVA pH 5.9, respectively. Both methods (chromatography or bioassay used to evaluate ametryn persistence in soils showed that degradation of this herbicide is strongly influenced by soil pH and organic matter content.

  10. Influence of the Amino Acid Sequence on Protein-Mineral Interactions in Soil

    Science.gov (United States)

    Chacon, S. S.; Reardon, P. N.; Purvine, S.; Lipton, M. S.; Washton, N.; Kleber, M.

    2017-12-01

    The intimate associations between protein and mineral surfaces have profound impacts on nutrient cycling in soil. Proteins are an important source of organic C and N, and a subset of proteins, extracellular enzymes (EE), can catalyze the depolymerization of soil organic matter (SOM). Our goal was to determine how variation in the amino acid sequence could influence a protein's susceptibility to become chemically altered by mineral surfaces to infer the fate of adsorbed EE function in soil. We hypothesized that (1) addition of charged amino acids would enhance the adsorption onto oppositely charged mineral surfaces (2) addition of aromatic amino acids would increase adsorption onto zero charged surfaces (3) Increase adsorption of modified proteins would enhance their susceptibility to alterations by redox active minerals. To test these hypotheses, we generated three engineered proxies of a model protein Gb1 (IEP 4.0, 6.2 kDA) by inserting either negatively charged, positively charged or aromatic amino acids in the second loop. These modified proteins were allowed to interact with functionally different mineral surfaces (goethite, montmorillonite, kaolinite and birnessite) at pH 5 and 7. We used LC-MS/MS and solution-state Heteronuclear Single Quantum Coherence Spectroscopy NMR to observe modifications on engineered proteins as a consequence to mineral interactions. Preliminary results indicate that addition of any amino acids to a protein increase its susceptibility to fragmentation and oxidation by redox active mineral surfaces, and alter adsorption to the other mineral surfaces. This suggest that not all mineral surfaces in soil may act as sorbents for EEs and chemical modification of their structure should also be considered as an explanation for decrease in EE activity. Fragmentation of proteins by minerals can bypass the need to produce proteases, but microbial acquisition of other nutrients that require enzymes such as cellulases, ligninases or phosphatases

  11. Macroscopic and molecular approaches of enrofloxacin retention in soils in presence of Cu(II).

    Science.gov (United States)

    Graouer-Bacart, Mareen; Sayen, Stéphanie; Guillon, Emmanuel

    2013-10-15

    The co-adsorption of copper and the fluoroquinolone antibiotic enrofloxacin (ENR) at the water-soil interface was studied by means of batch adsorption experiments, and extended X-ray absorption fine structure (EXAFS) spectroscopy. The system was investigated over a pH range between 6 and 10, at different contact times, ionic strengths, and ENR concentrations. Adsorption coefficient - Kd - was determined at relevant environmental concentrations and the value obtained in water at a ionic strength imposed by the soil and at soil natural pH was equal to 0.66Lg(-1). ENR adsorption onto the soil showed strong pH dependence illustrating the influence of the electrostatic interactions in the sorption processes. The simultaneous co-adsorption of ENR and Cu(II) on the soil was also investigated. The presence of Cu(II) strongly influenced the retention of the antibiotic, leading to an increase up to 35% of adsorbed ENR amount. The combined quantitative and spectroscopic results showed that Cu(II) and ENR directly interacted at the water-soil interface to form ternary surface complexes. Cu K-edge EXAFS data indicated a molecular structure where the carboxylate and carbonyl groups of ENR coordinate to Cu(II) to form a 6-membered chelate ring and where Cu(II) bridges between ENR and the soil surface sites. Cu(II) bonds bidentately to the surface in an inner-sphere mode. Thus, the spectroscopic data allowed us to propose the formation of ternary surface complexes with the molecular architecture soil-Cu(II)-ENR. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. The Effect of Limestone and Stabilized Nitrogen Fertilizers Application on Soil pH Value and on the Forage Production of Permanent Grassland

    Directory of Open Access Journals (Sweden)

    Pavel Ryant

    2016-01-01

    Full Text Available The changes of soil pH and dry forage yield of permanent grassland after application of dolomitic limestone and stabilized nitrogen fertilizers are described in this paper. The small‑plot experiment was located on semi‑natural grassland at Bohemian‑Moravian Highlands, near village Kameničky (Czech Republic, with poor and acidic soil. The experiment was divided into two blocks, within one of whose dolomitic limestone was applied in autumn 2013. In each block, 4 experimental treatments were applied: 1. control (untreated, 2. Urea, 3. Urea with inhibitor of urease, 4. Urea with inhibitor of nitrification. After liming, the pH/CaCl2 soil values increased in both the first as well as the second year after application. Fertilizing by urea, namely urea with inhibitors, did not significantly influence the pH/CaCl2 values. Dry forage productions in both years were comparable. In comparison to the untreated variants, significant increase in dry forage yield was achieved after application of urea and urea with urease inhibitors. The impact of stabilized fertilizers on the yield was not proven. In case of the limed variants, yield drop by 1.12 t/ha (average of both years was observed; the yield decrease may be connected with disturbance of production potential of the stable community of plant species that had been adapted to acidic locations.

  13. BIOREMEDIATION - TECHNOLOGY FOR DECONTAMINATION OF SOILS POLLUTED WITH PETROLEUM HYDROCARBONS

    Directory of Open Access Journals (Sweden)

    Irina-Ramona PECINGINĂ

    2013-05-01

    Full Text Available The pollution of soil with petroleum hydrocarbons prevents unfolding processes ofwater infiltration in soil, its circulation and the exchanges of the gaseous substances with theatmosphere. The biodegradation speed of the pollutants by the microorganisms is influenced ofsome factors: nutrients, soil type, humidity, temperature, pH, the type and the metabolism of themicroorganisms. The spill of the crude oil in the soil results in numerical growth of bacteriapopulations, with a concomitant reduction in their diversity, respectively with the predominantspecies that degrade hydrocarbons to simpler compounds, determining their gradualdisappearance.

  14. LIME REQUIREMENT DETERMINATION AND LIMING IMPACT ON SOIL NUTRIENT STATUS

    Directory of Open Access Journals (Sweden)

    Krunoslav Karalić

    2010-06-01

    Full Text Available The aim of conducted research was to determine the influence of liming, mineral and organic fertilization on soil chemical properties and nutrient availability in the soil, yield height and mineral composition of alfalfa. Results were used to create regression models for prediction of liming impact on soil chemical properties. Liming and fertilization experiment was sat up in 20 L volume plastic pots with two types of acid soils with different texture from two sites. Ten liming and fertilization treatments were applied in four repetitions. Lime treatments increased soil pH values and decreased hydrolytic acidity. Mineral and organic fertilization affected additional soil acidification. Application of lime intensified mineralization and humus decomposition, while organic fertilization raised humus content. The results showed significant increase of AL-P2O5 and K2O availability. The treatments increased soil Ca concentrations, but at the same time decreased exchangeable Mg concentrations. Soil pH increase resulted in lower Fe, Mn, Zn and Cu availability. Soil CEC was increased by applied treatments. Lime rates increased number and height of alfalfa plants, as well as yield of leaf, stalk increased concentrations of N, P, K and Ca in alfalfa leaf and stalk, but decreased leaf Mg and Fe, Mn, Zn and Cu concentrations. Regression computer models predicted with adequate accuracy P, Fe, Mn, Zn and Cu availability and final pH value as a result of liming and fertilization impact.

  15. Influence of Height Waterlogging on Soil Physical Properties of Potential and Actual Acid Sulphate Soils

    Directory of Open Access Journals (Sweden)

    Arifin Fahmi

    2014-06-01

    Full Text Available Water management is main factor that determines the successful of rice cultivation in acid sulphate soil. Soil waterlogging determines the direction and rate of chemical, geochemical and biological reaction in the soil, indirectly these reactions may influence to the changes of soil psycal properties during soil waterlogging process. The experiment was aimed to study the changes of two type of acid sulphate soils physical properties during rice straw decomposition processes. The research was conducted in the greenhouse consisting of the three treatment factors using the completely randomized design with three replications. The first factor was soil type: potential acid sulphate soil (PASS and actual acid sulphate soil (AASS. The second factor was height of water waterlogging: 0.5-1.0 cm (muddy water–level condition and 4.0 cm from above the soil surface (waterlogged. The third factor was organic matter type: rice straw (RS, purun tikus (Eleocharis dulcis (PT and mixed of RS and PT (MX. Soil physical properties such as aggregate stability, total soil porosity, soil permeability, soil particle density and bulk density were observed at the end of experiment (vegetative maximum stage. The results showed that acid sulphate soil type had large effect on soil physicl properties, soil waterlogging decreased aggregate stability, soil particle density and bulk density both of soil type.

  16. Determination of critical pH and Al concentration of acidic Ultisols for wheat and canola crops

    Science.gov (United States)

    Abdulaha-Al Baquy, M.; Li, Jiu-Yu; Xu, Chen-Yang; Mehmood, Khalid; Xu, Ren-Kou

    2017-02-01

    Soil acidity has become a principal constraint in dry land crop production systems of acidic Ultisols in tropical and subtropical regions of southern China, where winter wheat and canola are cultivated as important rotational crops. There is little information on the determination of critical soil pH as well as aluminium (Al) concentration for wheat and canola crops. The objective of this study is to determine the critical soil pH and exchangeable aluminium concentration (AlKCl) for wheat and canola production. Two pot cultures with two Ultisols from Hunan and Anhui (SE China) were conducted for wheat and canola crops in a controlled growth chamber. Aluminium sulfate (Al2(SO4)3) and hydrated lime (Ca(OH)2) were used to obtain the target soil pH levels from 3.7 (Hunan) and 3.97 (Anhui) to 6.5. Plant height, shoot dry weight, root dry weight, and chlorophyll content (SPAD value) of wheat and canola were adversely affected by soil acidity in both locations. The critical soil pH and AlKCl of the Ultisol from Hunan for wheat were 5.29 and 0.56 cmol kg-1, respectively. At Anhui, the threshold soil pH and AlKCl for wheat were 4.66 and 1.72 cmol kg-1, respectively. On the other hand, the critical soil pH for canola was 5.65 and 4.87 for the Ultisols from Hunan and Anhui, respectively. The critical soil exchangeable Al for canola cannot be determined from the experiment of this study. The results suggested that the critical soil pH and AlKCl varied between different locations for the same variety of crop, due to the different soil types and their other soil chemical properties. The critical soil pH for canola was higher than that for wheat for both Ultisols, and thus canola was more sensitive to soil acidity. Therefore, we recommend that liming should be undertaken to increase soil pH if it falls below these critical soil pH levels for wheat and canola production.

  17. Influence of perennial colonies of piscivorous birds on soil nutrient contents in a temperate humid climate

    DEFF Research Database (Denmark)

    Breuning-Madsen, Henrik; Ehlers-Koch, Camilla; Gregersen, Jens

    2010-01-01

    conductivity and content of carbon, nitrogen, phosphorus, calcium and potassium in a reference area and in two cormorant sub-colonies. In general, the soils exposed to cormorant guano had lower pH and higher contents of plant available phosphorus, calcium and potassium compared to the control reference soil...

  18. Estimativa da acidez potencial pelo método do pH SMP em solos com elevado teor de matéria orgânica Estimation of potencial acidity by the pH SMP method in soils with higher organic matter content in Brazil

    Directory of Open Access Journals (Sweden)

    Marcos Gervasio Pereira

    2006-01-01

    Full Text Available Apesar do potencial para uso agrícola e das características edáficas peculiares, poucos são os métodos desenvolvidos para a recomendação de adubação e calagem para os solos com elevado teor de matéria orgânica. O objetivo deste estudo foi definir um modelo matemático que estime a acidez potencial (H+Al a partir do pH SMP medido em água e em solução de CaCl2 0,01 mol L-1 em solos com elevado teor de matéria orgânica. Foram utilizadas 41 amostras de horizontes superficiais de solos com elevado teor de matéria orgânica de vários Estados do Brasil. Os resultados demonstraram que a acidez potencial pode ser estimada por meio da regressão da solução-tampão SMP (r =0,85**. Também foi observada correlação significativa (r = 0,65** entre o pH em CaCl2 0,01 mol L-1 e o pH SMP.In spite of agricultural potential for use and the peculiar edaphic characteristics, there are few methods developed for manuring and liming recommendation for soils with high organic matter contents. The objective of this study was to determine a mathematical model that estimates the potencial acidity with pH SMP measured in water and in solution of CaCl2 0.01 mol L-1 in soil with high organic matter content. Forty one surface soil samples of Histosols and other soils whith higher organic matter content of different states of Brazil were utilized. The results showed that potential acidity can be estimated by pH SMP buffer suspension regression ( R=0.85** and that in pH determined in CaCl2 0.01 mol L-1 was significantly correlated (R= 0.65** to pH determined in SMP.

  19. Coagulation-flocculation process applied to wastewaters generated in hydrocarbon-contaminated soil washing: Interactions among coagulant and flocculant concentrations and pH value.

    Science.gov (United States)

    Torres, Luis G; Belloc, Claudia; Vaca, Mabel; Iturbe, Rosario; Bandala, Erick R

    2009-11-01

    Wastewater produced in the contaminated soil washing was treated by means of coagulation-flocculation (CF) process. The wastewater contained petroleum hydrocarbons, a surfactant, i.e., sodium dodecyl sulfate (SDS) as well as salts, brownish organic matter and other constituents that were lixiviated from the soil during the washing process. The main goal of this work was to develop a process for treating the wastewaters generated when washing hydrocarbon-contaminated soils in such a way that it could be recycled to the washing process, and also be disposed at the end of the process properly. A second objective was to study the relationship among the coagulant and flocculant doses and the pH at which the CF process is developed, for systems where methylene blue active substances (MBAS) as well as oil and greases were present. The results for the selection of the right coagulant and flocculant type and dose, the optimum pH value for the CF process and the interactions among the three parameters are detailed along this work. The best coagulant and flocculant were FeCl(3) and Tecnifloc 998 at doses of 4,000 and 1 mg/L, correspondingly at pH of 5. These conditions gave color, turbidity, chemical oxygen demand (COD) and conductivity removals of 99.8, 99.6, 97.1 and 35%, respectively. It was concluded that it is feasible to treat the wastewaters generated in the contaminated soil washing process through CF process, and therefore, wastewaters could be recycled to the washing process or disposed to drainage.

  20. Influence of relief and vegetation on soil properties in a disturbed chernozem soil landscape

    Science.gov (United States)

    Raab, Thomas; Hirsch, Florian; Vasserman, Oleksandr; Raab, Alexandra; Naeth, Anne

    2017-04-01

    results of basic physical and chemical soil parameters (bulk density, water content, pH, C-stock, N-stock).

  1. Long-term tobacco plantation induces soil acidification and soil base cation loss.

    Science.gov (United States)

    Zhang, Yuting; He, Xinhua; Liang, Hong; Zhao, Jian; Zhang, Yueqiang; Xu, Chen; Shi, Xiaojun

    2016-03-01

    Changes in soil exchangeable cations relative to soil acidification are less studied particularly under long-term cash crop plantation. This study investigated soil acidification in an Ali-Periudic Argosols after 10-year (2002-2012) long-term continuous tobacco plantation. Soils were respectively sampled at 1933 and 2143 sites in 2002 and 2012 (also 647 tobacco plants), from seven tobacco plantation counties in the Chongqing Municipal City, southwest China. After 10-year continuous tobacco plantation, a substantial acidification was evidenced by an average decrease of 0.20 soil pH unit with a substantial increase of soil sites toward the acidic status, especially those pH ranging from 4.5 to 5.5, whereas 1.93 kmol H(+) production ha(-1) year(-1) was mostly derived from nitrogen (N) fertilizer input and plant N uptake output. After 1 decade, an average decrease of 27.6 % total exchangeable base cations or of 0.20 pH unit occurred in all seven tobacco plantation counties. Meanwhile, for one unit pH decrease, 40.3 and 28.3 mmol base cations kg(-1) soil were consumed in 2002 and 2012, respectively. Furthermore, the aboveground tobacco biomass harvest removed 339.23 kg base cations ha(-1) year(-1) from soil, which was 7.57 times higher than the anions removal, leading to a 12.52 kmol H(+) production ha(-1) year(-1) as the main reason inducing soil acidification. Overall, our results showed that long-term tobacco plantation not only stimulated soil acidification but also decreased soil acid-buffering capacity, resulting in negative effects on sustainable soil uses. On the other hand, our results addressed the importance of a continuous monitoring of soil pH changes in tobacco plantation sites, which would enhance our understanding of soil fertility of health in this region.

  2. White poplar (Populus alba L. - Litter impact on chemical and biochemical parameters related to nitrogen cycle in contaminated soils

    Directory of Open Access Journals (Sweden)

    Paula Madejon

    2014-04-01

    Full Text Available Aim of study: The aim of this study was to determine the effect of litter from Populus alba on chemical and biochemical properties related to the N cycle in soils with different pH values and trace element contents. We hypothesized that this litter would influence several parameters related to the N cycle and consequently to soil health.Area of study: we collected two reforested contaminated soils of different pH values (AZ pH 7.23 and DO pH = 2.66 and a non-contaminated soil (RHU pH 7.19.Materials and methods: Soil samples were placed in 2,000 cm3 microcosms and were incubated for 40 weeks in controlled conditions. Each soil was mixed with its corresponding litter, and soils without litter were also tested for comparison. Ammonium (NH4+-N and nitrate (NO3–-N content, potential nitrification rate (PNR, microbial biomass nitrogen (MBN, protease activity, and several chemical properties such as pH, available trace element concentrations (extracted with 0.01 M CaCl2 were determined at different times of incubation.Main results: Values of available trace elements did not vary during the incubation and were always higher in acid soil. In neutral soils litter presence increased values of Kjeldahl-N, NO3–-N content, potential nitrification rate (PNR, microbial biomass nitrogen (MBN and protease activity. Presence of trace elements in neutral soils did not alter the parameters studied. However, acidic pH and high content of available trace elements strongly affected NH4+-N andNO3–-N, microbial biomass N and protease activity.Research highlights: Our results showed the negative effect of the acidity and trace element availability in parameters related with the N-cycle.Key words: microbial biomass N; protease activity; soil pH; N mineralization; nitrification; phytoremediation.

  3. In-situ Monitoring of Plant-microbe Communication to Understand the Influence of Soil Properties on Symbiotic Biological Nitrogen Fixation

    Science.gov (United States)

    Webster, T.; Del Valle, I.; Cheng, H. Y.; Silberg, J. J.; Masiello, C. A.; Lehmann, J.

    2016-12-01

    Plant-microbe signaling is important for many symbiotic and pathogenic interactions. While this signaling often occurs in soils, very little research has evaluated the role that the soil mineral and organic matter matrix plays in plant-microbe communication. One hurdle to these studies is the lack of simple tools for evaluating how soil mineral phases and organic matter influence the availability of plant-produced flavonoids that initiate the symbiosis between nitrogen-fixing bacteria and legumes. Because of their range of hydrophobic and electrostatic properties, flavonoids represent an informative class of signaling molecules. In this presentation, we will describe studies examining the bioavailable concentrations of flavonoids in soils using traditional techniques, such as high-pressure liquid chromatography and fluorescent microbial biosensors. Additionally, we will describe our progress developing a Rhizobium leguminosarum reporter that can be deployed into soils to report on flavonoid levels. This new microbial reporter is designed so that Rhizobium only generates a volatile gas signal when it encounters a defined concentration of flavonoids. By monitoring the output of this biosensor using gas chromatography-mass spectrometry during real time during soil incubations, we are working to establish the impact of soil organic matter, pH, and mineral phases on the reception of these signaling molecules. We expect that the findings from these studies will be useful for recommending soil management strategies that can enhance the communication between legumes and nitrogen fixing bacteria. This research highlights the importance of studying the role of soil as a mediator of plant-microbe communication.

  4. Influence of surface chemistry of carbon materials on their interactions with inorganic nitrogen contaminants in soil and water.

    Science.gov (United States)

    Sumaraj; Padhye, Lokesh P

    2017-10-01

    Inorganic nitrogen contaminants (INC) (NH 4 + , NO 3 - , NO 2 - , NH 3 , NO, NO 2 , and N 2 O) pose a growing risk to the environment, and their remediation methods are highly sought after. Application of carbon materials (CM), such as biochar and activated carbon, to remediate INC from agricultural fields and wastewater treatment plants has gained a significant interest since past few years. Understanding the role of surface chemistry of CM in adsorption of various INC is highly critical to increase adsorption efficiency as well as to assess the long term impact of using these highly recalcitrant CM for remediation of INC. Critical reviews of adsorption studies related to INC have revealed that carbon surface chemistry (surface functional groups, pH, Eh, elemental composition, and mineral content) has significant influence on adsorption of INC. Compared to basic functional groups, oxygen containing surface functional groups have been found to be more influential for adsorption of INC. However, basic sites on carbon materials still play an important role in chemisorption of anionic INC. Apart from surface functional groups, pH, Eh and pH zpc of CM and elemental and mineral composition of its surface are important properties capable of altering INC interactions with CM. This review summarizes our current understanding of INC interactions with CM's surface through the known chemisorption mechanisms: electrostatic interaction, hydrogen bonding, electron donor-acceptor mechanism, hydrophobic and hydrophilic interaction, chemisorption aided by minerals, and interactions influenced by pH and elemental composition. Change in surface chemistry of CM in soil during aging is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Measurement of soil lead bioavailability and influence of soil types and properties: A review.

    Science.gov (United States)

    Yan, Kaihong; Dong, Zhaomin; Wijayawardena, M A Ayanka; Liu, Yanju; Naidu, Ravi; Semple, Kirk

    2017-10-01

    Lead (Pb) is a widespread heavy metal which is harmful to human health, especially to young children. To provide a human health risk assessment that is more relevant to real conditions, Pb bioavailability in soils is increasingly employed in the assessment procedure. Both in vivo and in vitro measurements for lead bioavailability are available. In vivo models are time- consuming and expensive, while in vitro models are rapid, economic, reproducible, and reliable while involving more uncertainties. Uncertainties in various measurements create difficulties in accurately predicting Pb bioavailability, resulting in the unnecessary remediation of sites. In this critical review, we utilised available data from in vivo and in vitro studies to identify the key parameters influencing the in vitro measurements, and presented uncertainties existing in Pb bioavailability measurements. Soil type, properties and metal content are reported to influence lead bioavailability; however, the differences in methods for assessing bioavailability and the differences in Pb source limit one's ability to conduct statistical analyses on influences of soil factors on Pb bioavailability. The information provided in the review is fundamentally useful for the measurement of bioavailability and risk assessment practices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Evaluation of conservation-oriented management on grayish brown soil

    Directory of Open Access Journals (Sweden)

    Consuelo E. Hernández Rodríguez

    2015-03-01

    Full Text Available Conservation and improvement actions were taken to ensure the soil preservation in agricultural areas affected by erosion on a grayish brown soil of Sarduy farm in Cumanayagua, Cuba. The technology that was used included strip-till, crop rotation, live and/or dead barriers, channel terraces, contour farming and the addition of organic matter and biofertilizers. The implementation of the soil conservation-oriented management had an influence on the yield increase of 10.6% - 20.2%, on the decrease of the erosive processes with a retention of soils to 13.33 t.ha -1, on maintaining the soil pH and on the increment of the assimilable P2O5 contents and soil organic matter.

  7. Vertical structure and pH as factors for chitinolytic and pectinolytic microbial community of soils and terrestrial ecosystems of different climatic zones

    Science.gov (United States)

    Lukacheva, Evgeniya; Natalia, Manucharova

    2016-04-01

    Chitin is a naturally occurring fibre-forming polymer that plays a protective role in many lower animals similar to that of cellulose in plants. Also it's a compound of cell walls of fungi. Chemically it is a long-chain unbranched polysaccharide made of N-acetylglucosamine residues; it is the second most abundant organic compound in nature, after cellulose. Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. Roots of the plants and root crops contain pectin. Chitin and pectin are widely distributed throughout the natural world. Structural and functional features of the complex microbial degradation of biopolymers one of the most important direction in microbial ecology. But there is no a lot of data concerns degradation in vertical structure of terrestrial ecosystems and detailed studies concerning certain abiotic features as pH. Microbial complexes of natural areas were analyzed only as humus horizons (A1) of the soil profile. Only small part of microbial community could be studied with this approach. It is known that ecosystems have their own structure. It is possible to allocate some vertical tiers: phylloplane, litter (soil covering), soil. We investigated chitinolytic and pectinolytic microbial communities dedicated to different layers of the ecosystems. Also it was described depending on pH dominated in certain ecosystem with certain conditions. Quantity of eukaryote and procaryote organisms increased in the test samples with chitin and pectin. Increasing of eukaryote in samples with pectin was more then in samples with chitin. Also should be noted the significant increasing of actinomycet's quantity in the samples with chitin in comparison with samples with pectin. The variety and abundance of bacteria in the litter samples increased an order of magnitude as compared to other probes. Further prokaryote community was investigated by method FISH (fluorescence in situ hybridization). FISH is a cytogenetic

  8. Influence of lake water pH and alkalinity on the distribution of coreand intact polar branched glycerol dialkyl glycerol tetraethers (GDGTs) in lakes

    NARCIS (Netherlands)

    Schoon, P.L.; de Kluijver, A.; Middelburg, J.J.; Downing, J.A.; Sinninghe Damsté, J.S.; Schouten, S.

    2013-01-01

    Branched glycerol dialkyl glycerol tetraethers (GDGTs) are bacterial membrane lipids, ubiquitously present in soils and peat bogs, as well as in rivers, lakes and lake sediments. Their distribution in soil is controlled mainly by pH and mean annual air temperature, but the controls on their

  9. Land cover changes affect soil chemical attributes in the Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Murilo Rezende Machado

    2017-05-01

    Full Text Available Forest plantations may minimize the effects of deforestation in the Amazon. However, there are differences among species in terms of their influences on soil recovery. The effects of monospecific plantations of Acacia mangium, Dipteryx odorata, Jacaranda copaia, Parkia decussata,and Swietenia macrophylla, and areas of pasture and native forest on the chemical soil attributes of the Brazilian Amazon were evaluated. One bulked soil sample was collected per plot (0.00-0.05, 0.05-0.10, and 0.10-0.30 m; three plots of 128 m2 in each area. No significant differences in most of the soil attributes were observed among the forest plantations. However, soil K+ and P were higher in the Swietenia macrophylla plantations, while higher values of Ca2+, sum of bases, and pH occurred in Jacaranda copaia plantations. In the native forest, the pH, and P content were lower, whereas the soil organic matter (SOM content, soil organic carbon (SOC content, cation exchange capacity (CEC, N content, H+Al content, and Al3+ content were higher than in the plantations. The lowest values of SOM, SOC, CEC, K+, Mg2+, N, H+Al, and Al3+ occurred in the pasture. None of the forest species led to the return of the original soil chemical attributes of the native forest. However, S. macrophylla and J. copaia plantations presented the highest positive edaphic influences.

  10. Exploring intentions of physician-scientist trainees: factors influencing MD and MD/PhD interest in research careers.

    Science.gov (United States)

    Kwan, Jennifer M; Daye, Dania; Schmidt, Mary Lou; Conlon, Claudia Morrissey; Kim, Hajwa; Gaonkar, Bilwaj; Payne, Aimee S; Riddle, Megan; Madera, Sharline; Adami, Alexander J; Winter, Kate Quinn

    2017-07-11

    Prior studies have described the career paths of physician-scientist candidates after graduation, but the factors that influence career choices at the candidate stage remain unclear. Additionally, previous work has focused on MD/PhDs, despite many physician-scientists being MDs. This study sought to identify career sector intentions, important factors in career selection, and experienced and predicted obstacles to career success that influence the career choices of MD candidates, MD candidates with research-intense career intentions (MD-RI), and MD/PhD candidates. A 70-question survey was administered to students at 5 academic medical centers with Medical Scientist Training Programs (MSTPs) and Clinical and Translational Science Awards (CTSA) from the NIH. Data were analyzed using bivariate or multivariate analyses. More MD/PhD and MD-RI candidates anticipated or had experienced obstacles related to balancing academic and family responsibilities and to balancing clinical, research, and education responsibilities, whereas more MD candidates indicated experienced and predicted obstacles related to loan repayment. MD/PhD candidates expressed higher interest in basic and translational research compared to MD-RI candidates, who indicated more interest in clinical research. Overall, MD-RI candidates displayed a profile distinct from both MD/PhD and MD candidates. MD/PhD and MD-RI candidates experience obstacles that influence their intentions to pursue academic medical careers from the earliest training stage, obstacles which differ from those of their MD peers. The differences between the aspirations of and challenges facing MD, MD-RI and MD/PhD candidates present opportunities for training programs to target curricula and support services to ensure the career development of successful physician-scientists.

  11. pH control for enhanced reductive bioremediation of chlorinated solvent source zones

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Clare, E-mail: clare.robinson@epfl.ch [Laboratoire de technologie ecologique, Institut d' ingenierie de l' environnement, Station No. 2, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Now at: Department of Civil and Environmental Engineering, University of Western Ontario, London, Canada N6A 5B9 (Canada); Barry, D.A., E-mail: andrew.barry@epfl.ch [Laboratoire de technologie ecologique, Institut d' ingenierie de l' environnement, Station No. 2, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); McCarty, Perry L., E-mail: pmccarty@stanford.edu [Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020 (United States); Gerhard, Jason I., E-mail: j.gerhard@ed.ac.uk [Now at: Department of Civil and Environmental Engineering, University of Western Ontario, London, Canada N6A 5B9 (Canada); Institute for Infrastructure and Environment, University of Edinburgh, Edinburgh, EH9 3JL (United Kingdom); Kouznetsova, Irina, E-mail: irina.kouznetsova@ed.ac.uk [Institute for Infrastructure and Environment, University of Edinburgh, Edinburgh, EH9 3JL (United Kingdom)

    2009-08-01

    Enhanced reductive dehalogenation is an attractive treatment technology for in situ remediation of chlorinated solvent DNAPL source areas. Reductive dehalogenation is an acid-forming process with hydrochloric acid and also organic acids from fermentation of the electron donors typically building up in the source zone during remediation. This can lead to groundwater acidification thereby inhibiting the activity of dehalogenating microorganisms. Where the soils' natural buffering capacity is likely to be exceeded, the addition of an external source of alkalinity is needed to ensure sustained dehalogenation. To assist in the design of bioremediation systems, an abiotic geochemical model was developed to provide insight into the processes influencing the groundwater acidity as dehalogenation proceeds, and to predict the amount of bicarbonate required to maintain the pH at a suitable level for dehalogenating bacteria (i.e., > 6.5). The model accounts for the amount of chlorinated solvent degraded, site water chemistry, electron donor, alternative terminal electron-accepting processes, gas release and soil mineralogy. While calcite and iron oxides were shown to be the key minerals influencing the soil's buffering capacity, for the extensive dehalogenation likely to occur in a DNAPL source zone, significant bicarbonate addition may be necessary even in soils that are naturally well buffered. Results indicated that the bicarbonate requirement strongly depends on the electron donor used and availability of competing electron acceptors (e.g., sulfate, iron (III)). Based on understanding gained from this model, a simplified model was developed for calculating a preliminary design estimate of the bicarbonate addition required to control the pH for user-specified operating conditions.

  12. 3.4. Durability of soil-cement mixtures influenced by hostile environment

    International Nuclear Information System (INIS)

    Saidov, D.Kh.

    2011-01-01

    It is determined that soil-cement mixture is one of most perspective materials, that can substitute concrete. Experiments on revelation of magnesium sulphate influence on soil-cement mixtures were carried out. Data on granulometric composition and physical parameters of loess soils is presented in this article. Portland cement M 400 was used as binder. According to the results it is concluded that stability of soil-cement mixtures from loess soils in solutions of magnesium sulphate depends on concentration of solution.

  13. Influence of lokpa cattle market wastes on agricultural soil quality ...

    African Journals Online (AJOL)

    Influence of lokpa cattle market wastes on agricultural soil quality. ... African Journal of Environmental Science and Technology ... Soil samples were collected from the Central, 3 and 6 m Northwards, Southwards, Eastwards and Westwards of Lokpa cattle market, Umuneochi Local Government Area of Abia State, Nigeria at ...

  14. The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

    Energy Technology Data Exchange (ETDEWEB)

    Muhlbachova, G. [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Sagova-Mareckova, M., E-mail: sagova@vurv.cz [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Omelka, M. [Charles University, Faculty of Mathematics and Physics, Dept. of Probability and Mathematical Statistics, Prague 8, Karlin (Czech Republic); Szakova, J.; Tlustos, P. [Czech University of Life Sciences, Department of Agroenvironmental Chemistry and Plant Nutrition, Prague 6, Suchdol (Czech Republic)

    2015-01-01

    The effects of lead, zinc, cadmium, arsenic and copper deposits on soil microbial parameters were investigated at a site exposed to contamination for over 200 years. Soil samples were collected in triplicates at 121 sites differing in contamination and soil organic carbon (SOC). Microbial biomass, respiration, dehydrogenase activity and metabolic quotient were determined and correlated with total and extractable metal concentrations in soil. The goal was to analyze complex interactions between toxic metals and microbial parameters by assessing the effect of soil organic carbon in the relationships. The effect of SOC was significant in all interactions and changed the correlations between microbial parameters and metal fractions from negative to positive. In some cases, the effect of SOC was combined with that of clay and soil pH. In the final analysis, dehydrogenase activity was negatively correlated to total metal concentrations and acetic acid extractable metals, respiration and metabolic quotient were to ammonium nitrate extractable metals. Dehydrogenase activity was the most sensitive microbial parameter correlating most frequently with contamination. Total and extractable zinc was most often correlated with microbial parameters. The large data set enabled robust explanation of discrepancies in organic matter functioning occurring frequently in analyzing of contaminated soil processes. - Highlights: • Soil organic carbon affected all interactions between metals and microorganisms. • Soil organic carbon adjustment changed correlations from positive to negative. • Ammonium nitrate extractable metals were the most influencing fraction. • Dehydrogenase activity was the most affected soil parameter. • Zinc was the most toxic metal among studied metals.

  15. The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

    International Nuclear Information System (INIS)

    Muhlbachova, G.; Sagova-Mareckova, M.; Omelka, M.; Szakova, J.; Tlustos, P.

    2015-01-01

    The effects of lead, zinc, cadmium, arsenic and copper deposits on soil microbial parameters were investigated at a site exposed to contamination for over 200 years. Soil samples were collected in triplicates at 121 sites differing in contamination and soil organic carbon (SOC). Microbial biomass, respiration, dehydrogenase activity and metabolic quotient were determined and correlated with total and extractable metal concentrations in soil. The goal was to analyze complex interactions between toxic metals and microbial parameters by assessing the effect of soil organic carbon in the relationships. The effect of SOC was significant in all interactions and changed the correlations between microbial parameters and metal fractions from negative to positive. In some cases, the effect of SOC was combined with that of clay and soil pH. In the final analysis, dehydrogenase activity was negatively correlated to total metal concentrations and acetic acid extractable metals, respiration and metabolic quotient were to ammonium nitrate extractable metals. Dehydrogenase activity was the most sensitive microbial parameter correlating most frequently with contamination. Total and extractable zinc was most often correlated with microbial parameters. The large data set enabled robust explanation of discrepancies in organic matter functioning occurring frequently in analyzing of contaminated soil processes. - Highlights: • Soil organic carbon affected all interactions between metals and microorganisms. • Soil organic carbon adjustment changed correlations from positive to negative. • Ammonium nitrate extractable metals were the most influencing fraction. • Dehydrogenase activity was the most affected soil parameter. • Zinc was the most toxic metal among studied metals

  16. Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO2 emission.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Lei; Peng, Qi-An; van Zwieten, Lukas; Chhajro, Muhammad Afzal; Wu, Yupeng; Lin, Shan; Ahmed, Muhammad Mahmood; Khalid, Muhammad Salman; Abid, Muhammad; Hu, Ronggui

    2017-04-01

    Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO 2 emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO 2 emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g -1 soil, herein referred to as CK, L, and H, respectively. The soil pH (H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO 2 emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO 2 emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg -1 in the RR soil and 244 and 481 mg kg -1 in the RF soil by H treatments. The NH 4 - -N and NO 3 - -N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO 2 release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.

  17. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    Energy Technology Data Exchange (ETDEWEB)

    Roemkens, P.F.A.M., E-mail: paul.romkens@wur.nl [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Brus, D.J. [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Guo, H.Y.; Chu, C.L.; Chiang, C.M. [Taiwan Agricultural Research Institute (TARI), Wufong, Taiwan (China); Koopmans, G.F. [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Department of Soil Quality, Wageningen University, WageningenUR. P.O. Box 47, 6700AA, Wageningen (Netherlands)

    2011-08-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal content, pH, and CEC or soil Cd and Zn extracted by 0.01 M CaCl{sub 2} as explanatory variables. The models were validated against a set of 2300 data points not used in the calibration. These models were then used inversely to derive soil quality standards for Japonica and Indica rice cultivars based on the food quality standards for rice. To account for model uncertainty, strict soil quality standards were derived considering a maximum probability that rice exceeds the food quality standard equal to 10 or 5%. Model derived soil standards based on Aqua Regia ranged from less than 0.3 mg kg{sup -1} for Indica at pH 4.5 to more than 6 mg kg{sup -1} for Japonica-type cultivars in clay soils at pH 7. Based on the CaCl{sub 2} extract, standards ranged from 0.03 mg kg{sup -1} Cd for Indica cultivars to 0.1 mg kg{sup -1} Cd for Japonica cultivars. For both Japonica and Indica-type cultivars, the soil quality standards must be reduced by a factor of 2 to 3 to obtain the strict standards. The strong impact of pH and CEC on soil quality standards implies that it is essential to correct for soil type when deriving national or local standards. Validation on the remaining 2300 samples indicated that both types of models were able to accurately predict (> 92%) whether rice grown on a specific soil will meet the food quality standard used in Taiwan. - Research highlights: {yields} Cadmium uptake by Japonica and Indica rice varieties depends on soil pH and CEC. {yields} Food safety based soil standards range from 0.3 (Indica) to 6 mg kg{sup -1} (Japonica). {yields} Model uncertainty leads to strict soil standards of less than 0.1 mg kg{sup -1} for Indica. {yields} Soil pH and CEC should be

  18. Soil Respiration under Different Land Uses in Eastern China

    Science.gov (United States)

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  19. Temperature and pH influence adsorption of cellobiohydrolase onto lignin by changing the protein properties.

    Science.gov (United States)

    Lu, Xianqin; Wang, Can; Li, Xuezhi; Zhao, Jian

    2017-12-01

    Non-productive adsorption of cellulase onto lignin restricted the movement of cellulase and also hindered the cellulase recycling in bioconversion of lignocellulose. In this study, effect of temperature and pH on adsorption and desorption of cellobiohydrolase (CBH) on lignin and its possible mechanism were discussed. It found that pH value and temperature influenced the adsorption and desorption behaviors of CBH on lignin. Different thermodynamic models suggested that the action between lignin and CBH was physical action. More CBH was adsorbed onto lignin, but lower initial adsorption velocity was detected at 50°C comparing with 4°C. Elevating pH value could improve desorption of cellulase from lignin. The changes of hydrophobicity and electric potential on protein surface may partially explain the impact of environmental conditions on the adsorption and desorption behaviors of CBH on lignin, and comparing to electrical interaction, the hydrophobicity may be the dominating factor influencing the behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. A review of sample preparation and its influence on pH determination in concrete samples

    International Nuclear Information System (INIS)

    Manso, S.; Aguado, A.

    2017-01-01

    If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field.

  1. Influence of facing vertical stiffness on reinforced soil wall design

    OpenAIRE

    Puig Damians, Ivan; Bathurst, Richard; Josa Garcia-Tornel, Alejandro; Lloret Morancho, Antonio

    2013-01-01

    Current design practices for reinforced soil walls typically ignore the influence of facing type and foundation compressibility on the magnitude and distribution of reinforcement loads in steel reinforced soil walls under operational conditions. In this paper, the effect of the facing vertical stiffness (due to elastomeric bearing pads placed in the horizontal joints between panels) on load capacity of steel reinforced soil walls is examined in a systematic manner using a numerical modelli...

  2. Effects of changing pH, incubation time, and As(V) competition, on F- retention on soils, natural adsorbents, by-products, and waste materials

    Science.gov (United States)

    Quintáns-Fondo, Ana; Santás-Miguel, Vanesa; Nóvoa-Muñoz, Juan C.; Arias-Estévez, Manuel; Fernández-Sanjurjo, María J.; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino

    2018-03-01

    The purpose of this work was to elucidate the repercussion of changing pH, incubation time and As(V) competition on fluoride (F-) sorption on forest and vineyard soil samples, pyritic and granitic materials, as well as on the by-products pine sawdust, oak wood ash, mussel shell ash, fine and coarse mussel shell, and slate processing waste fines. To reach this end, the methodological approach was based on batch-type experiments. The results indicate that, for most materials, F- sorption was very high at the start, but was clearly diminished when the pH value increased. However, oak wood ash and shell ash showed high F- sorption even at alkaline pH, and pine sawdust showed low F- sorption for any pH value. Specifically, F- sorption was close to 100% for both ashes at pH time on F- sorption, it was very low for both soils, pyritic material, granitic material and both kinds of ashes, as all of them showed very rapid F- sorption from the start, with differences being lesser than 10% between sorption at 30 min and 1 month of incubation. However, sawdust and slate fines sorbed 20% of added F- in 30 minutes, remaining constant up to twelve hours, and doubling after 30 days. And finally, mussel shell sorbed 20% at 30 minutes, increasing to close to 60% when incubation time was 30 days. This means that some of the materials showed a first sorption phase characterized by rapid F- sorption, and a slower sorption in a second phase. As regards the effect of the presence of As(V) on F- sorption, it was almost negligible, indicating the absence of competition for sorption sites. In view of that all, these results could aid to appropriately manage soils and by-products when focusing on F- removal, in circumstances where pH value changes, contact time vary from hours to days, and potential competition between F- and As(V) could take place.

  3. Aluminium, extractable from soil samples by the acid ammonium acetate soil-testing method

    Directory of Open Access Journals (Sweden)

    Osmo Mäkitie

    1968-05-01

    Full Text Available The extractant, 0.5 M acetic acid –0.5 M ammonium acetate at pH 4.65, which is used in soil-testing, extracts relatively high amounts of aluminium from acid soils. The mean values of acetate-extractable aluminium at pH 4.65, 1.75 meq Al/100 g of soil, and of exchangeable aluminium (M KCI extraction, 0.41 meq Al were obtained from a material of 30 samples of acid soils (Table 2. Several other acetic acid ammonium acetate extractants, from M acetic acid to M ammonium acetate solution were also used for studying the extractability of soil aluminium. The soil-testing extractant can be used for the estimation of the soluble amounts of aluminium in acid soils, however, further studies are needed for a better interpretation of the ammonium acetate extractable (at pH 4.65 aluminium in our soils.

  4. Uncertainties associated with lacking data for predictions of solid-solution partitioning of metals in soil

    International Nuclear Information System (INIS)

    Le, T.T. Yen; Hendriks, A. Jan

    2014-01-01

    Soil properties, i.e., pH and contents of soil organic matter (SOM), dissolved organic carbon (DOC), clay, oxides, and reactive metals, are required inputs to both mechanistic and empirical modeling in assessing metal solid-solution partitioning. Several of these properties are rarely measured in site-specific risk assessment. We compared the uncertainties induced by lacking data on these soil properties in estimating metal soil solution concentrations. The predictions by the Orchestra framework were more sensitive to lacking soil property data than the predictions by the transfer functions. The deviations between soil solution concentrations of Cd, Ni, Zn, Ba, and Co estimated with measured SOM and those estimated with generic SOM by the Orchestra framework were about 10 times larger than the deviations in the predictions by the transfer functions. High uncertainties were induced by lacking data in assessing solid-solution partitioning of oxy-anions like As, Mo, Sb, Se, and V. Deviations associated with lacking data in predicting soil solution concentrations of these metals by the Orchestra framework reached three-to-six orders of magnitude. The solid-solution partitioning of metal cations was strongly influenced by pH and contents of organic matter, oxides, and reactive metals. Deviations of more than two orders of magnitude were frequently observed between the estimates of soil solution concentrations with the generic values of these properties and the estimates based on the measured data. Reliable information on these properties is preferred to be included in the assessment by either the Orchestra framework or transfer functions. - Highlights: • Estimates of metal solid-solution partitioning sensitive to soil property data. • Uncertainty mainly due to lacking reactive metal contents, pH, and organic matter. • Soil solution concentrations of oxy-anions highly influenced by oxide contents. • Clay contents had least effects on solid-solution partitioning

  5. Uncertainties associated with lacking data for predictions of solid-solution partitioning of metals in soil

    Energy Technology Data Exchange (ETDEWEB)

    Le, T.T. Yen, E-mail: YenLe@science.ru.nl; Hendriks, A. Jan

    2014-08-15

    Soil properties, i.e., pH and contents of soil organic matter (SOM), dissolved organic carbon (DOC), clay, oxides, and reactive metals, are required inputs to both mechanistic and empirical modeling in assessing metal solid-solution partitioning. Several of these properties are rarely measured in site-specific risk assessment. We compared the uncertainties induced by lacking data on these soil properties in estimating metal soil solution concentrations. The predictions by the Orchestra framework were more sensitive to lacking soil property data than the predictions by the transfer functions. The deviations between soil solution concentrations of Cd, Ni, Zn, Ba, and Co estimated with measured SOM and those estimated with generic SOM by the Orchestra framework were about 10 times larger than the deviations in the predictions by the transfer functions. High uncertainties were induced by lacking data in assessing solid-solution partitioning of oxy-anions like As, Mo, Sb, Se, and V. Deviations associated with lacking data in predicting soil solution concentrations of these metals by the Orchestra framework reached three-to-six orders of magnitude. The solid-solution partitioning of metal cations was strongly influenced by pH and contents of organic matter, oxides, and reactive metals. Deviations of more than two orders of magnitude were frequently observed between the estimates of soil solution concentrations with the generic values of these properties and the estimates based on the measured data. Reliable information on these properties is preferred to be included in the assessment by either the Orchestra framework or transfer functions. - Highlights: • Estimates of metal solid-solution partitioning sensitive to soil property data. • Uncertainty mainly due to lacking reactive metal contents, pH, and organic matter. • Soil solution concentrations of oxy-anions highly influenced by oxide contents. • Clay contents had least effects on solid-solution partitioning

  6. Geographic distance and pH drive bacterial distribution in alkaline lake sediments across Tibetan Plateau

    Science.gov (United States)

    Xiong, Jinbo; Liu, Yongqin; Lin, Xiangui; Zhang, Huayong; Zeng, Jun; Hou, Juzhi; Yang, Yongping; Yao, Tandong; Knight, Rob; Chu, Haiyan

    2012-01-01

    Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4–1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r = 0.443, P = 0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments. PMID:22676420

  7. Assessing Soil Organic C Stability at the Continental Scale: An Analysis of Soil C and Radiocarbon Profiles Across the NEON Sites

    Science.gov (United States)

    Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; McKnight, D. M.; Strahm, B. D.; Sanclements, M.

    2017-12-01

    Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of physicochemical parameters on soil C stocks and turnover, and their relative importance in comparison to climatic variables. Soils were cored at NEON sites, sampled by genetic horizon, and density separated into light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon abundance was correlated with pH, with variance also grouping by dominate vegetation type. Soil order was also identified as an important proxy variable for C and radiocarbon abundance. Preliminary results suggest that

  8. Factors of influencing dissolved organic carbon stabilization in two cambic forest soils with contrasting soil-forming processes

    Science.gov (United States)

    Kawasaki, M.; Ohte, N.; Asano, Y.; Uchida, T.; Kabeya, N.; Kim, S.

    2004-05-01

    Stabilization of Dissolved Organic Carbon (DOC) in forest soil is a major process of soil organic carbon formation. However, the factors influencing DOC stabilization are poorly understood. To clarify the factors that affect the stabilization of DOC in forest soil mantle, we measured DOC concentrations and soil properties which were DOC adsorption efficiency at two adjacent cambic forest soils with contrasting forest management histories in Tanakami Mountains, central Japan. Matsuzawa was devastated about 1,200 years ago by excessive timber use and remained denuded for a long period. Hillside restoration and reforestation work have been carried out over the last 100 years and soil loss has been reduced. Fudoji is covered with undisturbed forest (mixed stands of cypress and oaks) with developed forest soils (more than 2,600 years old). There was no apparent seasonal variation in DOC concentration in the soil solution in either catchment. In addition, there were no significant relationships between the DOC concentration, soil temperature, and new water ratio. These results indicate that temporal variation in biological activity and rainfall-runoff process have little effect on temporal variation in DOC. The vertical variation in the DOC adsorption efficiency and DOC concentration differed between Matsuzawa and Fudoji, and the highest DOC removal rate occurred at the lowest DOC adsorption efficiency in the 0 to 10-cm soil layer at Fudoji. These results suggest that DOC removal rate is independent of DOC adsorption efficiency. Below 60 cm soil depth, DOC fluxes were constant and dissolved organic Al concentrations were little or zero in either catchment. These results suggest that abiotic precipitation of DOC is a major mechanism for stabilization of DOC. Therefore, DOC content which is able to form metal complexes may be the most important factor of influencing DOC stabilization in cambic forest soil.

  9. Interrelationships of Land Use/Cover Change and Topography with Soil Acidity and Salinity as Indicators of Land Degradation

    Directory of Open Access Journals (Sweden)

    Ramita Manandhar

    2014-03-01

    Full Text Available As soil is the basis of all terrestrial ecosystems, degraded soil means lower fertility, reduced biodiversity and reduced human welfare. Therefore the focus of this paper is on elucidating the influence of land use and land cover (LULC change on two important soil quality indicators that are fundamental to effective measures for ameliorating soil degradation; namely soil acidity and soil salinity in the Lower Hunter Valley of New South Wales, Australia. First, Analysis of Variance was used to elucidate the effects of LULC categories on soil acidity and salinity. The results indicate that soils under Vineyard have significantly higher pH. In contrast there is no significant effect of LULC or its change on soil salinity. To further elucidate the complex interactions of these soil quality indicators with landscape attributes over 20 years and other terrain attributes, multivariate ordination techniques (correspondence analysis and canonical correspondence analysis were used. The results show that elevation exerted a more dominant influence on pH than the LULC types and their dynamics. In comparison, salinity of the soil appears to be higher in subsoil layers under woodland than under other LULC categories. The environmental implications of these interactions, as evidenced by this study, provide some insights for future land use planning in the region.

  10. Influence of land improvement on soil oxidation. Inverkan av grundfoerbaettring paa markens syrehalt

    Energy Technology Data Exchange (ETDEWEB)

    Kowalik, P.J.

    1985-01-01

    The paper presents the theoretical analysis of influence of the land reclamation on soil oxidation. Examination was carried out on dependencies existing among soil moisture content, respiratory activity of the soil, absolute soil porosity, gas-filled soil porosity, coeffficient of oxygen diffusion in soil air and soil liquid, oxygen concentration in soil air and in soil water, oxygen diffusion flux, oxygen diffusion rate and the depth of zone of aeration in soil profile. Some remarks about the influence of soil oxidation on root growth and morphology of soil profile were presented too. Results of own empirical investigations and similar data from literature verify theoretical ideas pointed out in the paper. The methods and results of own measurements of ODR (oxygen diffusion rate) has been presented in detail. The research explains the relationship between soil moisture content and soil oxidation. As a result of the analysis there have been proposed such methods of land improvement that the water and oxygen demands of plant roots and microorganisms would be satisfying. The paper proposes a new method of account of the so-called anaerobic soil moisture content. This moisture should be the highest for irrigation practice and more or less lowest for drainage of soil water. Soil moisture a little lower than anarobic soil water content is enough for warranting the sufficient soil aeration during drainage and irrigation activity. With 82 refs.

  11. To Identify the Important Soil Properties Affecting Dinoseb Adsorption with Statistical Analysis

    Directory of Open Access Journals (Sweden)

    Yiqing Guan

    2013-01-01

    Full Text Available Investigating the influences of soil characteristic factors on dinoseb adsorption parameter with different statistical methods would be valuable to explicitly figure out the extent of these influences. The correlation coefficients and the direct, indirect effects of soil characteristic factors on dinoseb adsorption parameter were analyzed through bivariate correlation analysis, and path analysis. With stepwise regression analysis the factors which had little influence on the adsorption parameter were excluded. Results indicate that pH and CEC had moderate relationship and lower direct effect on dinoseb adsorption parameter due to the multicollinearity with other soil factors, and organic carbon and clay contents were found to be the most significant soil factors which affect the dinoseb adsorption process. A regression is thereby set up to explore the relationship between the dinoseb adsorption parameter and the two soil factors: the soil organic carbon and clay contents. A 92% of the variation of dinoseb sorption coefficient could be attributed to the variation of the soil organic carbon and clay contents.

  12. Study of solution speciation, soil retention and soil-plant transfer of zirconium

    International Nuclear Information System (INIS)

    Ferrand, E.

    2005-12-01

    Within the framework of the risks prevention policy of Andra, the radioactive zirconium introduction ( 93 Zr and 95 Zr) into the environment could be carried out starting from the nuclear waste whose storage is envisaged in deep geological layers. Thus, the goal of this study was to evaluate the parameters and phenomena influencing speciation (various chemical forms) and the soil-plant transfer of zirconium. Experiments of adsorption/desorption of zirconium with different ligands likely to be present in soils (goethite and humic acid) and with two soils, with contrasted characteristics, close to the underground research laboratory of Andra (Meuse) were carried out. These results of adsorption were then confronted with those obtained by the MUSIC and NICA-DONNAN models carried out using the computer code ECOSAT. Zr presents a strong affinity for the two types of soils and the soils constituents. Specific interactions of internal sphere type with the goethite were highlighted using the model. Soil-solution partition coefficients, or K d , values increase with pH and contact time. Various types of edible plants, pea (Pisum sativum L.) and tomato (Lycopersicon esculentum L cv. St Pierre) were cultivated in hydroponic conditions and in soils spiked with various sources of Zirconium. The maximum zirconium contents are mainly measured in the roots of the plants. The soil-plant transfer factors measured during these experiments show a weak bioavailability of zirconium. An influence of speciation on Zr bioavailability is however highlighted. Some chemical forms, such as oxychloride or acetate, are more easily mobilized than others by the plant. (author)

  13. Enzyme Sorption onto Soil and Biocarbon Amendments Alters Catalytic Capacity and Depends on the Specific Protein and pH

    Science.gov (United States)

    Foster, E.; Fogle, E. J.; Cotrufo, M. F.

    2017-12-01

    Enzymes catalyze biogeochemical reactions in soils and play a key role in nutrient cycling in agricultural systems. Often, to increase soil nutrients, agricultural managers add organic amendments and have recently experimented with charcoal-like biocarbon products. These amendments can enhance soil water and nutrient holding capacity through increasing porosity. However, the large surface area of the biocarbon has the potential to sorb nutrients and other organic molecules. Does the biocarbon decrease nutrient cycling through sorption of enzymes? In a laboratory setting, we compared the interaction of two purified enzymes β-glucosidase and acid phosphatase with a sandy clay loam and two biocarbons. We quantified the sorbed enzymes at three different pHs using a Bradford protein assay and then measured the activity of the sorbed enzyme via high-throughput fluorometric analysis. Both sorption and activity depended upon the solid phase, pH, and specific enzyme. Overall the high surface area biocarbon impacted the catalytic capacity of the enzymes more than the loam soil, which may have implications for soil nutrient management with these organic amendments.

  14. Headcut erosive regimes influenced by groundwater on disturbed agricultural soils.

    Science.gov (United States)

    Rockwell, D L

    2011-02-01

    A series of simulated rainfall experiments, testing several soils and slope gradients in a 10 m x 0.8m laboratory flume, displayed close correlations between initial development of a water table at a 10 cm depth and highly erosive headcut formation. On some soils and gradients, highly erosive headcuts formed consistently and predictably within minutes or seconds of initial water table rise. However, headcuts alone were not good indicators of increased erosion. In most experiments some headcuts formed early, often when surface hydraulic parameter values reached established rill initiation thresholds, but resulted in little or no erosion increase. Later, at initial water table rise, other headcuts formed coincident with major erosion increase, often with surface hydraulic values then less than rill initiation thresholds. On the four soils tested, highly erosive headcuts never formed without groundwater development, except on steep 9 ° slopes. Common visual indicators such as headcut morphology and headcut advance rates were not effective means of determining either erosion or the existence of groundwater. Only local monitoring of subsurface moisture conditions with micro-standpipes and TDR aided in determining headcut processes and erosive regimes. Groundwater-influenced headcut formation was likely caused by increased soil pore-water pressures and decreased soil shear strengths in surface rainflow, not by sapping or seepage from the soil matrix. Highly erosive headcuts can thus form under common agricultural conditions where reductions in permeability, such as plow pans, exist near the surface--without the need for saturated soils. Headcut erosive regimes were also significantly influenced by soil type and slope gradient, with the greatest effects of groundwater on moderate slopes and fairly permeable soils. Copyright © 2010. Published by Elsevier Ltd.

  15. Influence of agricultural management on chemical quality of a clay soil of semi-arid Morocco

    Science.gov (United States)

    Ibno Namr, Khalid; Mrabet, Rachid

    2004-06-01

    Morocco's semi-arid lands are characterized by unique challenges. The most important obstacles to the development of durable agriculture are (1) limited and unpredictable supply of soil moisture and (2) low soil quality. Intensive use of soil throughout history has led to depletion in soil quality, leading in return to reduced yields because of the consequent reduced organic matter. Recognizing the need to recover soil quality and production decline, INRA scientists began, in the early 1980s, research on the effects of crop rotations, tillage and residue management on the productivity and quality of cropped soils. The present study concerns the short-term effect of rotation, tillage and residue management on selected quality indices of a calcixeroll (organic matter, nitrogen, particulate organic carbon (Cpom), particulate organic nitrogen (Npom) and pH). Hence, three rotations (wheat-wheat, WW; fallow-wheat, FW; and fallow-wheat-barley, FWB), two tillage systems (conventional offset disking, CT and no-tillage, NT), and three levels of residue in the NT system (NT 0 = no-residue cover, NT 50 = half surface residue cover, NT 100 = full surface residue cover) were selected. Three surface horizons were sampled (0-2.5, 2.5-7 and 7-20 cm). The study results showed an improvement of measured soil chemical properties under NT compared to CT, at the surface layer. No-tillage system helped sequestration of carbon and nitrogen, build-up of particulate organic carbon and nitrogen and sensible reduction of pH only at the surface layer. Continuous wheat permitted a slight improvement of soil quality, mainly at the 0-2.5 cm depth. Effects of rotation, tillage and residue level were reduced with depth of measurements.

  16. Influence of soil and hydrocarbon properties on the solvent extraction of high-concentration weathered petroleum from contaminated soils.

    Science.gov (United States)

    Sui, Hong; Hua, Zhengtao; Li, Xingang; Li, Hong; Wu, Guozhong

    2014-05-01

    Petroleum ether was used to extract petroleum hydrocarbons from soils collected from six oil fields with different history of exploratory and contamination. It was capable of fast removing 76-94 % of the total petroleum hydrocarbons including 25 alkanes (C11-C35) and 16 US EPA priority polycyclic aromatic hydrocarbons from soils at room temperature. The partial least squares analysis indicated that the solvent extraction efficiencies were positively correlated with soil organic matter, cation exchange capacity, moisture, pH, and sand content of soils, while negative effects were observed in the properties reflecting the molecular size (e.g., molecular weight and number of carbon atoms) and hydrophobicity (e.g., water solubility, octanol-water partition coefficient, soil organic carbon partition coefficient) of hydrocarbons. The high concentration of weathered crude oil at the order of 10(5) mg kg(-1) in this study was demonstrated adverse for solvent extraction by providing an obvious nonaqueous phase liquid phase for hydrocarbon sinking and increasing the sequestration of soluble hydrocarbons in the insoluble oil fractions during weathering. A full picture of the mass distribution and transport mechanism of petroleum contaminants in soils will ultimately require a variety of studies to gain insights into the dynamic interactions between environmental indicator hydrocarbons and their host oil matrix.

  17. Uptake and elimination kinetics of metals in soil invertebrates: a review.

    Science.gov (United States)

    Ardestani, Masoud M; van Straalen, Nico M; van Gestel, Cornelis A M

    2014-10-01

    Uptake and elimination kinetics of metals in soil invertebrates are a function of both soil and organism properties. This study critically reviewed metal toxicokinetics in soil invertebrates and its potential use for assessing bioavailability. Uptake and elimination rate constants of different metals are summarized. Invertebrates have different strategies for essential and non-essential metals. As a consequence, different types of models must be applied to describe metal uptake and elimination kinetics. We discuss model parameters for each metal separately and show how they are influenced by exposure concentrations and by physiological properties of the organisms. Soil pH, cation exchange capacity, clay and organic matter content significantly affect uptake rates of non-essential metals in soil invertebrates. For essential metals, kinetics is hardly influenced by soil properties, but rather prone to physiological regulation mechanisms of the organisms. Our analysis illustrates that toxicokinetics can be a valuable measurement to assess bioavailability of soil-bound metals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Influence of soil type, cultivar and Verticillium dahliae on the structure of the root and rhizosphere soil fungal microbiome of strawberry.

    Science.gov (United States)

    Nallanchakravarthula, Srivathsa; Mahmood, Shahid; Alström, Sadhna; Finlay, Roger D

    2014-01-01

    Sustainable management of crop productivity and health necessitates improved understanding of the ways in which rhizosphere microbial populations interact with each other, with plant roots and their abiotic environment. In this study we examined the effects of different soils and cultivars, and the presence of a soil-borne fungal pathogen, Verticillium dahliae, on the fungal microbiome of the rhizosphere soil and roots of strawberry plants, using high-throughput pyrosequencing. Fungal communities of the roots of two cultivars, Honeoye and Florence, were statistically distinct from those in the rhizosphere soil of the same plants, with little overlap. Roots of plants growing in two contrasting field soils had high relative abundance of Leptodontidium sp. C2 BESC 319 g whereas rhizosphere soil was characterised by high relative abundance of Trichosporon dulcitum or Cryptococcus terreus, depending upon the soil type. Differences between different cultivars were not as clear. Inoculation with the pathogen V. dahliae had a significant influence on community structure, generally decreasing the number of rhizosphere soil- and root-inhabiting fungi. Leptodontidium sp. C2 BESC 319 g was the dominant fungus responding positively to inoculation with V. dahliae. The results suggest that 1) plant roots select microorganisms from the wider rhizosphere pool, 2) that both rhizosphere soil and root inhabiting fungal communities are influenced by V. dahliae and 3) that soil type has a stronger influence on both of these communities than cultivar.

  19. Hypoxia induced expression of endogenous markers in vitro is highly influenced by pH

    International Nuclear Information System (INIS)

    Sorensen, Brita Singers; Alsner, Jan; Overgaard, Jens; Horsman, Michael R.

    2007-01-01

    Background: Genes such as carbonic anhydrase IX (Ca9), glucose transporter 1 (Glut1), lactate dehydrogenase A (LDH-A), osteopontin (OPN) and lysyl oxidase (LOX) have been suggested as hypoxic markers, but inconsistent results suggest that factors other than oxygen influence their expression. The current study is a detailed investigation using a range of pH values from 6.3 to 7.5 in two human cell lines to establish the pH dependency of hypoxia induced gene expression. Methods: Human tumour cell lines (uterine cervix squamous cell carcinoma (SiHa) and pharyngeal squamous cell carcinoma [FaDu DD ]) were used. Hypoxia was induced by gassing cells in airtight chambers with various oxygen concentrations (21%, 1%, 0.1%, 0.01% and 0%) for up to 24 h. The media were titrated to a range of pH values (7.5, 7.0, 6.7, 6.5 and 6.3). Gene expression was determined by real-time PCR. Results: In both SiHa and FaDu DD cells Ca9 and LOX reached the highest level of expression at 1% oxygen. In FaDu DD cells, a pH of 6.5 had a medium suppression effect on the hypoxia induced expression of Ca9. pH 6.3 resulted in severe suppression of expression for Ca9 and LOX in both SiHa and FaDu DD . Glut1 and LDH-A had a similar expression pattern to each other, with a maximum expression at 0.01% oxygen, in both cell lines. For these genes pH 6.5 and 6.3 changed the expression pattern in SiHa cells. OPN was up regulated at low oxygen in SiHa cells, but was not induced by hypoxia in FaDu DD cells. Conclusion: As tumour hypoxia occurs in a deprived microenvironment, other environmental factors, for example low pH, might interact with the effect of low oxygen concentration on gene expression. This study shows that pH in two cell lines has a profound influence on the oxygen dependent induction of certain endogenous hypoxic markers

  20. Impact of a low intensity controlled-fire in some chemical soil properties.

    Science.gov (United States)

    Martínez-Murillo, Juan F.; Hueso-González, Paloma; Aranda-Gómez, Francisco; Damián Ruiz-Sinoga, José

    2014-05-01

    Some changes in chemical soil properties can be observed after fires of low intensities. pH and electric conductivity tend to increase, while C/N ratio decrease. In the case of organic matter, the content can increase due to the massive incorporation of necromass including, especially, plants and roots. The aim of this study is to assess the impact of low intensity and controlled fire in some soil properties in field conditions. El Pinarillo experimental area is located in South of Spain. Two set of closed plots were installed (24 m2: 12 m length x 2 m width). One of them was remained as control with the original vegetation cover (Mediterranean matorral: Rosmarinus officinalis, Cistus clusii, Lavandula stoechas, Chamaeropos humilis, Thymus baetica), and the other one was burnt in a controlled-fire in 2011. Weather conditions and water content of vegetation influenced in the intensity of fire (low). After the controlled-fire, soil surface sample (0-5 cm) were taken in both set of plots (B, burnt soil samples; C, control soil samples). Some soil chemical properties were analysed: organic matter content (OM), C/N ratio, pH and electrical conductivity (EC). Some changes were observed in B corroborating a controlled-fire of low intensity. pH remained equal after fire (B: pH=7.7±0.11; C: pH=7.7±0.04). An increment was obtained in the case of EC (B: EC=0.45 mScm-1±0.08 mScm-1; C: EC=0.35 mScm-1±0.07 mScm-1) and OM (B: OM=8.7%±3.8%; C: pH=7.3%±1.5%). Finally, C/N ratio decreased after fire respect to the control and initial conditions (B: C/N=39.0±14.6; C: C/N =46.5±10.2).

  1. Influence of temperature and hydraulic conductivity of soil on electrokinetic decontamination

    International Nuclear Information System (INIS)

    Kim, Gye-Nam; Kim, Seung-Soo; Jeong, Jung-Whan; Choi, Jong-Won

    2016-01-01

    The electrokinetic process holds great promise for the decontamination of contaminated soil because it has a high removal efficiency and is time-effective for low permeability. Electrokinetic decontamination can be used to treat soil contaminated with inorganic species and radionuclides. The main mechanisms of a contaminant's movement in an electrical field involved in electrokinetic technology are the electro-migration of the ionic species and electro-osmosis. Electro-migration probably contributes significantly to the removal of contaminants, especially at high concentrations of ionic contaminants and/or a high hydraulic permeability of soil. The cathode reaction should be depolarized to avoid the generation of hydroxides and their transport in soil. The selected liquid, also known as a purging reagent, should induce favorable pH conditions in soil, and/or interact with the incorporated heavy metals so that these heavy metals are removed from the soil. The removal efficiencies of uranium from contaminated soil in manufactured laboratory electrokinetic decontamination equipment were proportional to the elapsed time. The removal efficiencies of uranium for 2 days were 77-87%. In addition, the removal efficiencies according to the elapsed time after 2 days were reduced. When 75, 80, and 85℃ electrolyte temperatures in the cathode chamber were applied, the time required for the removal efficiency of uranium to reach 92% was 6, 5 and 4 days

  2. Influence of temperature and hydraulic conductivity of soil on electrokinetic decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gye-Nam; Kim, Seung-Soo; Jeong, Jung-Whan; Choi, Jong-Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The electrokinetic process holds great promise for the decontamination of contaminated soil because it has a high removal efficiency and is time-effective for low permeability. Electrokinetic decontamination can be used to treat soil contaminated with inorganic species and radionuclides. The main mechanisms of a contaminant's movement in an electrical field involved in electrokinetic technology are the electro-migration of the ionic species and electro-osmosis. Electro-migration probably contributes significantly to the removal of contaminants, especially at high concentrations of ionic contaminants and/or a high hydraulic permeability of soil. The cathode reaction should be depolarized to avoid the generation of hydroxides and their transport in soil. The selected liquid, also known as a purging reagent, should induce favorable pH conditions in soil, and/or interact with the incorporated heavy metals so that these heavy metals are removed from the soil. The removal efficiencies of uranium from contaminated soil in manufactured laboratory electrokinetic decontamination equipment were proportional to the elapsed time. The removal efficiencies of uranium for 2 days were 77-87%. In addition, the removal efficiencies according to the elapsed time after 2 days were reduced. When 75, 80, and 85℃ electrolyte temperatures in the cathode chamber were applied, the time required for the removal efficiency of uranium to reach 92% was 6, 5 and 4 days.

  3. Biosolids and heavy metals in soils

    Directory of Open Access Journals (Sweden)

    Silveira Maria Lucia Azevedo

    2003-01-01

    Full Text Available The application of sewage sludge or biosolids on soils has been widespread in agricultural areas. However, depending on their characteristics, they may cause increase in heavy metal concentration of treated soils. In general, domestic biosolids have lower heavy metal contents than industrial ones. Origin and treatment method of biosolids may markedly influence their characteristics. The legislation that controls the levels of heavy metal contents in biosolids and the maximum concentrations in soils is still controversial. In the long-term, heavy metal behavior after the and of biosolid application is still unknown. In soils, heavy metals may be adsorbed via specific or non-specific adsorption reactions. Iron oxides and organic matter are the most important soil constituents retaining heavy metals. The pH, CEC and the presence of competing ions also affect heavy metal adsorption and speciation in soils. In solution, heavy metals can be present either as free-ions or complexed with organic and inorganic ligands. Generally, free-ions are more relevant in environmental pollution studies since they are readily bioavailable. Some computer models can estimate heavy metal activity in solution and their ionic speciation. Thermodynamic data (thermodynamic stability constant, total metal and ligand concentrations are used by the GEOCHEM-PC program. This program allows studying heavy metal behavior in solution and the effect of changes in the conditions, such as pH and ionic strength and the application of organic and inorganic ligands caused by soil fertilization.

  4. Influence of lake water pH and alkalinity on the distribution of core and intact polar branched glycerol dialkyl glycerol tetraethers (GDGTs) in lakes

    NARCIS (Netherlands)

    Schoon, P.L.; de Kluijver, A.; Middelburg, J.J.; Downing, J.A.; Sinninghe Damsté, J.S.; Schouten, S.

    2013-01-01

    Branched glycerol dialkyl glycerol tetraethers (GDGTs) are bacterial membrane lipids, ubiquitously present in soils and peat bogs, as well as in rivers, lakes and lake sediments. Their distribution in soil is controlled mainly by pH and mean annual air temperature, but the controls on their

  5. Application of ground bone and sheep manure on soils from two contaminated sites and influence on oat growth, uranium and radium uptake and translocation

    Science.gov (United States)

    Abreu, M. M.; Pacheco, A.; Santos, E.; Magalhães, M. C. F.

    2012-04-01

    Past radium and uranium exploitation and processing in Urgeiriça mine and radium processing in Barracão (centre-north of Portugal) led to soils and waters contamination. Most of the soils, located in rural areas, are cultivated for vegetables, fruit trees, and/or pasturage, and the waters used for soils irrigation. The objective of this work was to evaluate the capacity of organic amendments and hydroxiapatite to reduce the soil available fraction of Utotal and 226Ra in soils of two areas after four months of incubation. Influence on oat growth, uranium and radium uptake and translocation was also studied. Pot experiments, under controlled conditions, were undertaken during four months of incubation at 70% of the soil water-holding capacity. Urgeiriça (Urg) and Barracão (Brc) soils containing large concentrations of Utotal (635 and 189 mg/kg, respectively), and 226Ra (2310 and 1770 Bq/kg, respectively) were used. The available fraction of these elements, extracted with ammonium acetate, corresponds to: 90 and 20% of total concentration of uranium and radium, respectively, for Urgeiriça soil, and 19 and 43% of total concentration of uranium and radium, respectively, for Barracão soil. Fine ground bone (FB), sheep manure (OM), and vermicompost (V) single or mixtures were used as amendments. Control (soil) and treatments were made in triplicate: (T1) soil+96 g FB/kg of soil; (T2) soil+168 g OM/kg of soil; (T3) soil+168 g OM/kg of soil+96 g FB/kg of soil; (T4) soil+168 g V/kg of soil. After incubation, soil subsamples were analysed for pH, electric conductivity (EC), and available fractions of Utotal and 226Ra. The remaining soils were used for oat (Avena sativa L.) cultivation. Soils had pH 5.15 (Urg) and 6.04 (Brc), and EC 57.3 µS/cm (Urg) and 36.3 µS/cm (Brc). After incubation soil pH increased to a maximum of 6.82 (Urg) and 7.10 (Brc) in amended samples, and EC showed a large increase (15-19 times) when compared to the control. A decrease of the available

  6. Evaluation of different soil parameters and wild boar (Sus scrofa [L.] grassland damage

    Directory of Open Access Journals (Sweden)

    Žiga Laznik

    2014-10-01

    Full Text Available Presented in this paper are the correlations between different soil parameters [presence of grubs, earthworms, pH, content of P2O5, K2O and organic matter (OM in soil] and wild boar (Sus scrofa [L.] damage to grasslands. The soil samples and damage assessments were performed at six locations in the Kočevje region, which is a densely wooded part of South East Slovenia. A significant positive correlation was discovered between the extent of damage due to wild boar rooting in grasslands and the number of grubs (r=0.73, the weight of grubs (r=0.69 and the content of P2O5 (r=0.87 in the soil. The quantity and weight of grubs in soil were significantly influenced by soil pH, the content of CaCl2 (r=0.71/0.72, P2O5 (r=0.90/0.91, and OM (r=0.74/0.77; while the quantity and weight of earthworms in soil were influenced by the content of K2O (r=0.81/-0.84. A moderate yet insignificant correlation (r=0.48/0.56 was discovered between the number and weight of earthworms in soil and the extent of grassland damage. Grubs represent a more important source of protein for wild boars than earthworms; consequently, reducing the quantity of grubs in soil could minimise the extent of damage caused by boars.

  7. Influence of the sunflower rhizosphere on the biodegradation of PAHs in soil

    OpenAIRE

    Tejeda Agredano, M. C.; Gallego, Sara; Vila, Joaquim; Ortega Calvo, J. J.; Cantos, Manuel

    2013-01-01

    Reduced bioavailability to soil microorganisms is probably the most limiting factor in the bioremediation of polycyclic aromatic hydrocarbons PAH-polluted soils. We used sunflowers planted in pots containing soil to determine the influence of the rhizosphere on the ability of soil microbiota to reduce PAH levels. The concentration of total PAHs decreased by 93% in 90 days when the contaminated soil was cultivated with sunflowers, representing an improvement of 16% compared to contaminated soi...

  8. A review of sample preparation and its influence on pH determination in concrete samples

    Directory of Open Access Journals (Sweden)

    S. Manso

    2017-01-01

    Full Text Available If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field.

  9. Effect of Litter Fall on Soil Nutrient Content and pH, and its Consequences in View of Climate Change (Síkf

    OpenAIRE

    TÓTH, János Attila; NAGY, Péter Tamás; KRAKOMPERGER, Zsolt; VERES, Zsuzsa; KOTROCZÓ, Zsolt; KINCSES, Sándorné; FEKETE, István; PAPP, Mária; LAJTHA, Kate

    2011-01-01

    In the DIRT (Detritus Input and Removal Treatment) field experiments established at theSíkfkút Site (North Hungary) in October 2000, an experiment was initiated to study the long-termeffects of litter quality and quantity on pH and nutrient content (organic carbon, N forms, PO43–, K+,Mg2+, Ca2+) of soil in a Quercetum petraeae-cerris forest. An eight-year litter manipulationdemonstrated a close connection between the changes in pH and Mg2+ and Ca2+ concentration. Thedecline of litter producti...

  10. Influence of oxidation state on the pH dependence of hydrous iridium oxide films

    International Nuclear Information System (INIS)

    Steegstra, Patrick; Ahlberg, Elisabet

    2012-01-01

    Many electrochemical reactions taking place in aqueous solution consume or produce protons. The pH in the diffusion layer can therefore be significantly altered during the reaction and there is a need for in situ pH measurements tracing this near surface pH. In the present paper the rotating ring disc technique was used to measure near surface pH changes during oxygen reduction, utilising hydrous iridium oxide as the pH sensing probe. Before such experiments a good understanding of the pH sensing properties of these films is required and the impact of the oxidation state of the film on the pH sensing properties was investigated as well as the influence of solution redox species. The pH sensitivity (depicted by dE/dpH) was found to depend on the average oxidation state of the film in a manner resembling the cyclic voltammetry response. In all cases the pH response is “supernernstian” with more than one proton per electron. The origin of this behaviour is discussed in the context of acid-base properties of the film and the existence of both hydrous and anhydrous oxide phases. The pH response depends also on the redox properties of the solution but can be optimised for various purposes by conditioning the film at different potentials. This was clearly illustrated by adding hydrogen peroxide, an intermediate in the oxygen reduction reaction, to the solution. It was shown that hydrous iridium oxide can be used as a reliable in situ pH sensor provided that care is taken to optimise the oxidation state of the film.

  11. Study on the adsorption-desorption characteristics of 14C-pirimicarb in soils

    International Nuclear Information System (INIS)

    Guo Jiangfeng; Sun Jinhe; Li Xingming

    1995-01-01

    14 C-pirimicarb was used to study its adsorption-desorption behavior in 8 kinds of soils. The results indicated that there were significant differences in its adsorption with different kinds of soil. The lowest adsorption percentage was only 13.16% and the highest one was 87.75%. The amount of adsorption in the same kind of soil increased with the concentration of pesticide, but concentration had little influence on the adsorption within the certain range of concentrations. Multiple linear regression equation was developed for prediction of adsorption and determination of the relative importance of the soil parameters. It was significant that the key factors, soil pH and clay content were negatively and positively correlated with the adsorption respectively. The adsorption equilibrium of pirimicarb in soils could be well described by both the Freundlich isotherm and the Langmuir isotherm. The adsorbed 14 C-pirimicarb could disrobe from soil and its desorption was also influenced by soil properties described by multiple linear regression equation

  12. Integrated Nanozero Valent Iron and Biosurfactant-Aided Remediation of PCB-Contaminated Soil

    Directory of Open Access Journals (Sweden)

    He Zhang

    2016-01-01

    Full Text Available Polychlorobiphenyls (PCBs have been identified as environmental hazards for years. Due to historical issues, a considerable amount of PCBs was released deep underground in Canada. In this research, a nanoscale zero valent iron- (nZVI- aided dechlorination followed by biosurfactant enhanced soil washing method was developed to remove PCBs from soil. During nZVI-aided dechlorination, the effects of nZVI dosage, initial pH level, and temperature were evaluated, respectively. Five levels of nZVI dosage and two levels of initial pH were experimented to evaluate the PCB dechlorination rate. Additionally, the temperature changes could positively influence the dechlorination process. In soil washing, the presence of nanoiron particles played a key role in PCB removal. The crude biosurfactant was produced using a bacterial stain isolated from the Atlantic Ocean and was applied for soil washing. The study has led to a promising technology for PCB-contaminated soil remediation.

  13. White popular (Populus alba L.) - Litter impact on chemical and biochemical parameters related to nitrogen cycle in contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Ciadamidaro, L.; Madejon, P.; Cabrera, F.; Madejon, E.

    2014-06-01

    Aim of study: The aim of this study was to determine the effect of litter from Populus alba on chemical and biochemical properties related to the N cycle in soils with different pH values and trace element contents. We hypothesized that this litter would influence several parameters related to the N cycle and consequently to soil health. Area of study: we collected two reforested contaminated soils of different pH values (AZ pH 7.23 and DO pH 2.66) and a non-contaminated soil (RHU pH 7.19). Materials and methods: Soil samples were placed in 2,000 cm{sup 3} microcosms and were incubated for 40 weeks in controlled conditions. Each soil was mixed with its corresponding litter, and soils without litter were also tested for comparison. Ammonium (NH{sub 4}{sup 4}+-N) and nitrate (NO{sub 3}{sup -} -N) content, potential nitrification rate (PNR), microbial biomass nitrogen (MBN), protease activity, and several chemical properties such as pH, available trace element concentrations (extracted with 0.01 M CaCl{sub 2}) were determined at different times of incubation. Main results: Values of available trace elements did not vary during the incubation and were always higher in acid soil. In neutral soils litter presence increased values of Kjeldahl-N, NO{sub 3} –-N content, potential nitrification rate (PNR), microbial biomass nitrogen (MBN) and protease activity. Presence of trace elements in neutral soils did not alter the parameters studied. However, acidic pH and high content of available trace elements strongly affected NH{sub 4}{sup +}-N and NO{sub 3}{sup -} -N, microbial biomass N and protease activity. Research highlights: Our results showed the negative effect of the acidity and trace element availability in parameters related with the N-cycle. (Author)

  14. Labile soil phosphorus as influenced by methods of applying radioactive phosphorus

    International Nuclear Information System (INIS)

    Selvaratnam, V.V.; Andersen, A.J.; Thomsen, J.D.; Gissel-Nielsen, G.

    1980-03-01

    The influence of different methods of applying radioactive phosphorus on the E- and L-values was studied in four foil types using barley, buckwheat, and rye grass for the L-value determination. The four soils differed greatly in their E- and L-values. The experiment was carried out both with and without carrier-P. The presence of carrier-P had no influence on the E-values, while carrier-P in some cases gave a lower L-value. Both E- and L-values dependent on the method of application. When the 32 P was applied on a small soil or sand sample and dried before mixing with the total amount of soil, the E-values were higher than at direct application most likely because of a stronger fixation to the soil/sand particles. This was not the case for the L-values that are based on a much longer equilibrium time. On the contrary, the direct application of the 32 p-solution to the whole amount of soil gave higher L-values of a non-homogeneous distribution of the 32 p in the soil. (author)

  15. Bacterial community profile of contaminated soils in a typical antimony mining site.

    Science.gov (United States)

    Wang, Ningning; Zhang, Suhuan; He, Mengchang

    2018-01-01

    The soils around the world's largest antimony mine have been contaminated by high concentrations of Sb and As, which might influence microbial diversity in the surrounding soils. The ecological effects of bioavailable Sb and As on the composition and diversity of microbial community in soils remain unknown. In this study, the relative abundance, taxonomic diversity and composition of bacterial community in soils from a typical Sb mine area, and the relationship between the bacterial community and bioavailable concentrations as well as environmental factors have been investigated comprehensively using high-throughput sequencing (HTS) and diffusive gradients in thin films (DGT). The results indicated that Proteobacteria, Acidobacteria, Chloroflexi, Bacteroidetes, Actinobacteria, Gemmatimonadetes, and Cyanobacteria were the dominant bacterial populations at phylum level in all soil samples, accounting for more than 80% of the bacteria sequenced. The abundance and diversity of bacterial community vary along a metal contamination gradient. Redundancy discriminate analysis (RDA) revealed that 74.74% of bacterial community variation in the contaminated soils was explained by six environmental factors (pH, Sb DGT , As DGT , potential ecological risk index (RI), TC, TN), among which pH, Sb DGT , and As DGT were dominant factors influencing the composition and diversity of bacteria. This study contributes to our understanding of microbial diversity in a local ecosystem and introduces the option of studying bioavailable Sb and As using DGT.

  16. Processes regulating nitric oxide emissions from soils

    DEFF Research Database (Denmark)

    Pilegaard, Kim

    2013-01-01

    , the net result is complex and dependent on several factors such as nitrogen availability, organic matter content, oxygen status, soil moisture, pH and temperature. This paper reviews recent knowledge on processes forming NO in soils and the factors controlling its emission to the atmosphere. Schemes......Nitric oxide (NO) is a reactive gas that plays an important role in atmospheric chemistry by influencing the production and destruction of ozone and thereby the oxidizing capacity of the atmosphere. NO also contributes by its oxidation products to the formation of acid rain. The major sources...

  17. Variations in soil microbial community structure induced by the conversion from paddy fields to upland fields

    Science.gov (United States)

    Dai, X.

    2015-12-01

    Land-use conversion is an important factor influencing the carbon and nitrogen gas exchange between land and atmosphere, and soil microorganisms is main driver of soil carbon and nitrogen gas production. Understanding the effect of land-use conversion on soil microbial communities and its influencing factor is important for greenhouse gas emission reduction and soil organic carbon and nitrogen sequestration and stability. The influence of land use conversion on soil process was undergoing a dynamic change, but little research has been done to understand the effect on soil microbial communities during the initial years after land conversion. In the study, the influences of land-use conversion from double rice cropping (RR) to maize-maize (MM) and soybean-peanut (SP) double cropping systems on soil physical and chemical properties, and microbial community structure was studied after two years of the conversion in southern China. The results showed that land use conversion significantly changed soil properties, microbial communities and biomass. Soil pH significantly decreased by 0.50 and 0.52 after conversion to MM and SP, respectively. Soil TN and NH4-N also significantly decreased by 9%-15% and 60% after conversion to upland fields, respectively. The total PLFAs, bacterial, gram-positive bacterial (G+), gram-negative bacterial (G-) and actinomycetic PLFAs decreased significantly. The ng g-1 soil concentration of monounsaturated chain PLFAs 16:1ω7c and 18:1ω9t were significantly higher at paddy fields than at upland fields. No significant differences in soil properties, microbial communities and biomass were found between conversed MM and SP. Our results indicated that land use conversion, not crop type conversed had a significant effects on soil properties and microbial communities at the initial of land conversion. And soil pH was the key factor regulating the variations in soil microbial community structure after land use conversion from paddy to upland fields.

  18. Effect of structure and hydrophobicity of soil on the accessibility of diuron

    Science.gov (United States)

    Chaplain, V.; Défossez, P.; Brault, A.; Breuil, S.; Tessier, D.

    2009-04-01

    Effect of structure and hydropbicity of soil on the accessibility of diuron V. Chaplain1, P. Desfossez2, A. Brault1, S. Breuil1 and D. Tessier1. 1 UR INRA PESSAC, RD 10, Versailles F-78026 2 UMR INRA/URCA FARE, 2 Esplanade Roland Garros, BP 224 F-51686 Reims cedex 2 Corresponding author: chaplain@versailles.inra.fr Retention process plays a major role in the fate and impact of organic contaminants in soils. We studied the global talk of accessibility by measuring the influence of soil hydrophobic properties and soil structure on the retention of diuron. We selected seven plots with pH 3.4 to 8.2 of the long-term experiment of 42 plots in Versailles. Textural properties and composition were similar. The organic content was low. Sorption isotherms were obtained on soil slurries and kinetic measurements of diuron sorption were performed on undisturbed soil samples built up using sieved air-dried soil. The results showed that the Freundlich coefficient kf deduced from isotherm curves decreased as pH increased. For a given density, (i) the Koc coefficient, kf/TOC, was linearly related to the contact angle measured on the clay fraction over a wide range of pH (ii) kinetics slightly increased when pH decreased. On the contrary, when a compact structure was involved, a low initial adsorption rate and low adsorption equilibrium were observed. In this case, the structure in micro-aggregates due to the dispersion of fine particles induced by repeated treatment of soil with NaNO3, was assumed to limit the accessibility of adsorption sites.

  19. Assessing the influence of compost and biochar amendments on the mobility and toxicity of metals and arsenic in a naturally contaminated mine soil.

    Science.gov (United States)

    Beesley, Luke; Inneh, Onyeka S; Norton, Gareth J; Moreno-Jimenez, Eduardo; Pardo, Tania; Clemente, Rafael; Dawson, Julian J C

    2014-03-01

    Amending contaminated soils with organic wastes can influence trace element mobility and toxicity. Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved organic carbon primarily controlled metal mobility after compost amendment. Individually, both amendments induced considerable solubilisation of arsenic to pore water (>2500 μg l(-1)) related to pH and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous reductions in extractable metals and increases in soluble nutrients (P). Thus the measure-monitor-model approach taken determined that combining the amendments was most effective at mitigating attendant toxicity risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Influence of mammal fossorial activity on the soil fermentative activity in conditions of metallurgical production

    Directory of Open Access Journals (Sweden)

    S. M. Kirienko

    2010-09-01

    Full Text Available Effect of mammal fossorial activity as an ecological factor of the soil genesis intensification is studied. Enzymatic activity of soil as its ability to demonstrate a catalytic effect for various compounds transformation is examined. Variability of soil urease activity in technogenic conditions with the participation of animals is shown. The positive influence of animals’ activity on the catalitic ability of the investigated soils was determined. The statistically significant characteristics which have an influence on the urease activity in soil are found out.

  1. The impact of acid soil volume of reclaimed minespoils on plant growth in minilysimeters

    International Nuclear Information System (INIS)

    Shahandeh, H.; Hossner, L.R.; Birkhead, J.A.

    1996-01-01

    Limited data are available to assess the influence of randomly distributed acid soil, produced from acid forming materials (AFM), on growth and productivity of crops. This study evaluated the effect of amount and volume of acid soil on the growth of an acid tolerant plant (Coastal bermudga grass, Cynodon dactylon, L.) and an acid intolerant plant (Yuchi arrowleaf clover, Trifolium vesiculosum, Savi) in greenhouse lysimeters. Acid soil (pH=2.5) volumes up to 20% for Yuchi arrowleaf clover and up to 40% for Coastal bermuda grass did not significantly decrease dry matter yield. Concentrations of Al and Mn in plant tissue of clover and bermudagrass were below the toxicity level. In the presence of randomly distributed acid soil, plant roots continued to elongate in non-acid soil, by evading localized areas of low soil pH. These results suggest that the federally mandated zero tolerance for AFM in the top 1.2 m of reclaimed lands may not be reasonable. 18 refs., 7 figs., 2 tabs

  2. Carbon stabilization and microbial growth in acidic mine soils after addition of different amendments for soil reclamation

    Science.gov (United States)

    Zornoza, Raúl; Acosta, Jose; Ángeles Muñoz, María; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2016-04-01

    The extreme soil conditions in metalliferous mine soils have a negative influence on soil biological activity and therefore on soil carbon estabilization. Therefore, amendments are used to increase organic carbon content and activate microbial communities. In order to elucidate some of the factors controlling soil organic carbon stabilization in reclaimed acidic mine soils and its interrelationship with microbial growth and community structure, we performed an incubation experiment with four amendments: pig slurry (PS), pig manure (PM) and biochar (BC), applied with and without marble waste (MW; CaCO3). Results showed that PM and BC (alone or together with MW) contributed to an important increment in recalcitrant organic C, C/N ratio and aggregate stability. Bacterial and fungal growths were highly dependent on pH and labile organic C. PS supported the highest microbial growth; applied alone it stimulated fungal growth, and applied with MW it stimulated bacterial growth. BC promoted the lowest microbial growth, especially for fungi, with no significant increase in fungal biomass. MW+BC increased bacterial growth up to values similar to PM and MW+PM, suggesting that part of the biochar was degraded, at least in short-term mainly by bacteria rather than fungi. PM, MW+PS and MW+PM supported the highest microbial biomass and a similar community structure, related with the presence of high organic C and high pH, with immobilization of metals and increased soil quality. BC contributed to improved soil structure, increased recalcitrant organic C, and decreased metal mobility, with low stimulation of microbial growth.

  3. Tree species effect on the redistribution of soil metals

    International Nuclear Information System (INIS)

    Mertens, Jan; Van Nevel, Lotte; De Schrijver, An; Piesschaert, Frederic; Oosterbaan, Anne; Tack, Filip M.G.; Verheyen, Kris

    2007-01-01

    Phytostabilization of metals using trees is often promoted although the influence of different tree species on the mobilization of metals is not yet clear. Soil and biomass were sampled 33 years after planting four tree species (Quercus robur, Fraxinus excelsior, Acer pseudoplatanus, Populus 'Robusta') in a plot experiment on dredged sediment. Poplar took up high amounts of Cd and Zn and this was associated with increased Cd and Zn concentrations in the upper soil layer. The other species contained normal concentrations of Cd, Cu, Cr, Pb and Zn in their tissues. Oak acidified the soil more than the other species and caused a decrease in the concentration of metals in the upper soil layer. The pH under poplar was lower than expected and associated with high carbon concentrations in the top soil. This might be assigned to retardation of the litter decomposition due to elevated Cd and Zn concentrations in the litter. - Trees (33-year-old) growing on polluted dredged sediment have influenced the metal concentration in the upper soil layer and there was a significant tree species effect

  4. Evaluation of potential effects of soil available phosphorus on soil arsenic availability and paddy rice inorganic arsenic content.

    Science.gov (United States)

    Jiang, Wei; Hou, Qingye; Yang, Zhongfang; Zhong, Cong; Zheng, Guodong; Yang, Zhiqiang; Li, Jie

    2014-05-01

    The transfer of arsenic from paddy field to rice is a major exposure route of the highly toxic element to humans. The aim of our study is to explore the effects of soil available phosphorus on As uptake by rice, and identify the effects of soil properties on arsenic transfer from soil to rice under actual field conditions. 56 pairs of topsoil and rice samples were collected. The relevant parameters in soil and the inorganic arsenic in rice grains were analyzed, and then all the results were treated by statistical methods. Results show that the main factors influencing the uptake by rice grain include soil pH and available phosphorus. The eventual impact of phosphorus is identified as the suppression of As uptake by rice grains. The competition for transporters from soil to roots between arsenic and phosphorus in rhizosphere soil has been a dominant feature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Removal efficiency of methylene blue using activated carbon from waste banana stem: Study on pH influence

    Science.gov (United States)

    Misran, E.; Bani, O.; Situmeang, E. M.; Purba, A. S.

    2018-02-01

    The effort to remove methylene blue in artificial solution had been conducted using adsorption process. The abundant banana stem waste was utilized as activated carbon precursor. This study aimed to analyse the influence of solution pH to removal efficiency of methylene blue using activated carbon from banana stem as adsorbent. Activated carbon from banana stem was obtained by chemical activation using H3PO4 solution. Proximate analysis result showed that the activated carbon has 47.22% of fixed carbon. This value exhibited that banana stem was a potential adsorbent precursor. Methylene blue solutions were prepared at initial concentration of 50 ppm. The influence of solution pH was investigated with the use of 0.2 g adsorbent for 100 mL dye solution. The adsorption was conducted using shaker with at a constant rate of 100 rpm at room temperature for 90 minutes. The results showed that solution pH influenced the adsorption. The activated carbon from banana stem demonstrated satisfying performance since removal efficiencies of methylene blue were higher than 99%.

  6. [Effects of soil properties on the stabilization process of cadmium in Cd alone and Cd-Pb contaminated soils].

    Science.gov (United States)

    Wu, Man; Xu, Ming-Gang; Zhang, Wen-Ju; Wu, Hai-Wen

    2012-07-01

    In order to clarify the effects of soil properties on the stabilization process of the cadmium (Cd) added, 11 different soils were collected and incubated under a moisture content of 65%-70% at 25 degrees C. The changes of available Cd contents with incubation time (in 360 days) in Cd and Cd-Pb contaminated treatments were determined. The stabilization process was simulated using dynamic equations. The results showed that after 1.0 mg x kg(-1) Cd or 500 mg x kg(-1) Pb + 1.0 mg x kg(-1) Cd were added into the soil, the available Cd content decreased rapidly during the first 15 days, and then the decreasing rate slowed down, with an equilibrium content reached after 60 days' incubation. In Cd-Pb contaminated soils, the presence of Pb increased the content of available Cd. The stabilization process of Cd could be well described by the second-order equation and the first order exponential decay; meanwhile, dynamic parameters including equilibrium content and stabilization velocity were used to characterize the stabilization process of Cd. These two key dynamic parameters were significantly affected by soil properties. Correlation analysis and stepwise regression suggested that high pH and high cation exchange capacity (CEC) significantly retarded the availability of Cd. High pH had the paramount effect on the equilibrium content. The stabilization velocity of Cd was influenced by the soil texture. It took shorter time for Cd to get stabilized in sandy soil than in the clay.

  7. Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

    Science.gov (United States)

    Hansen, Gunda; Johansen, Claus Lindvald; Marten, Gunvor; Wilmes, Jacqueline; Jespersen, Lene; Arneborg, Nils

    2016-07-01

    In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.5, 6.5, and 7.5) on the growth, viability, cell size, acidification activity in milk, and intracellular pH (pHi) of Lactococcus lactis subsp. lactis DGCC1212 during pH-controlled batch fermentations. A universal parameter (e.g., linked to pHi) for the description or prediction of viability, specific acidification activity, or growth behavior at a given pHex was not identified. We found viability as determined by flow cytometry to remain high during all growth phases and irrespectively of the pH set point. Furthermore, regardless of the pHex, the acidification activity per cell decreased over time which seemed to be linked to cell shrinkage. Flow cytometric pHi determination demonstrated an increase of the averaged pHi level for higher pH set points, while the pH gradient (pHi-pHex) and the extent of pHi heterogeneity decreased. Cells maintained positive pH gradients at a low pHex of 5.5 and even during substrate limitation at the more widely used pHex 6.5. Moreover, the strain proved able to grow despite small negative or even absent pH gradients at a high pHex of 7.5. The larger pHi heterogeneity at pHex 5.5 and 6.5 was associated with more stressful conditions resulting, e.g., from higher concentrations of non-dissociated lactic acid, while the low pHi heterogeneity at pHex 7.5 most probably corresponded to lower concentrations of non-dissociated lactic acid which facilitated the cells to reach the highest maximum active cell counts of the three pH set points.

  8. Influence of Environmental Parameters on Trichoderma Strains with Biocontrol Potential

    Directory of Open Access Journals (Sweden)

    Zsuzsanna Antal

    2003-01-01

    Full Text Available Several mycoparasitic strains belonging to the filamentous fungal genus Trichoderma are promising candidates for the biological control of plant pathogenic fungi. When planning the application of antagonistic Trichoderma strains for the purposes of biological control, it is very important to consider the environmental parameters affecting the biocontrol agents in the soil. A series of abiotic and biotic environmental parameters has an influence on the biocontrol efficacy of Trichoderma. Some important parameters to be considered are the effects of temperature, water potential and pH, and the presence of pesticides, metal ions and antagonistic bacteria in the soil. Most of the Trichoderma strains are mesophilic. Low temperatures in winter may cause a problem during biological control by influencing the activity of the biocontrol agents. Another problem emerging during the application of Trichoderma strains as biocontrol agents is that they cannot tolerate dry conditions, however, we may need biocontrol agents against plant pathogenic fungi which are able to grow and cause disease even in dry soils. The pH characteristics of the soil also belong to the most important environmental parameters affecting the activities of mycoparasitic Trichoderma strains. Within the frames of a complex integrated plant protection strategy, we may have to combine Trichoderma strains with chemical pesticides or metal compounds, therefore it is important to collect information about the effects of pesticides and metal ions on the biocontrol strains. Antagonistic soil bacteria may also have negative effects on the biocontrol abilities of Trichoderma strains, therefore it may be advantageous if a biocontrol strain possesses bacterium- degrading abilities as well. This review will discuss the literature about the influence of temperature, water potential, pH, pesticides, metal ions and antagonistic bacteria on mycoparasitic Trichoderma strains including the results of our

  9. Amending Jasper County, Missouri soils with biochar and ...

    Science.gov (United States)

    Abandoned mines and the residuals from mining across the U.S. pose a considerable, pervasive risk to human health and the environment. Many soils in the Tri-State-Mining District (TSMD), located where Missouri, Kansas and Oklahoma meet, have been affected by the residuals of historic lead and zinc mining. Here we describe a research collaboration between ORD and Region 7 to investigate the use of customized soil amendments, which will include biochar, as a tool to provide both soil remediation and reestablishment of a soil-stabilizing native plant community at sites in the TSMD. Biochar is a charcoal-like, carbon-rich, porous by-product of thermal pyrolysis or gasification. A benefit of using biochar is the ability to engineer its properties to correspond to specific soil remediation needs. Specifically, it has properties that make it well suited for use in remediating mine soils and reestablishing vegetation, with studies indicating that biochar can complex and immobilize heavy metals. This is of critical importance for mining influenced sites. However, the optimized biochar properties for the remediation of acidic mine soils are not yet fully known. Biochar can be produced to have a range of pH values, depending upon feedstock and pyrolysis or gasification conditions, and post-production activation. Therefore, this material may be used as a liming agent to raise soil pH. Additionally, some biochars have been shown to improve soil water holding capacities and

  10. Peptide functionalized gold nanoparticles: the influence of pH on binding efficiency

    Science.gov (United States)

    Harrison, Emma; Hamilton, Jeremy W. J.; Macias-Montero, Manuel; Dixon, Dorian

    2017-07-01

    We report herein on the synthesis of mixed monolayer gold nanoparticles (AuNPs) capped with both polyethylene glycol (PEG) and one of three peptides. Either a receptor-mediated endocytosis peptide, an endosomal escape pathway (H5WYG) peptide or the Nrp-1 targeting RGD peptide (CRGDK) labeled with FITC. All three peptides have a thiol containing cysteine residue which can be used to bind the peptides to the AuNPs. In order to investigate the influence of pH on peptide attachment, PEGylated AuNPs were centrifuged, the supernatant removed, and the nanoparticles were then re-suspended in a range of pH buffer solutions above, below and at the respective isoelectric points of the peptides before co-functionalization. Peptide attachment was investigated using dynamic light scattering, Ultra-violet visible spectroscopy (UV/Vis), FTIR and photo luminescence spectroscopy. UV/Vis analysis coupled with protein assay results and photoluminescence of the FITC tagged RGD peptide concluded that a pH of ∼8 optimized the cysteine binding and stability, irrespective of the peptide used.

  11. Stabilization of Organic Matter by Biochar Application in Compost-amended Soils with Contrasting pH Values and Textures

    Directory of Open Access Journals (Sweden)

    Shih-Hao Jien

    2015-09-01

    Full Text Available Food demand and soil sustainability have become urgent concerns because of the impacts of global climate change. In subtropical and tropical regions, practical management that stabilizes and prevents organic fertilizers from rapid decomposition in soils is necessary. This study conducted a short-term (70 days incubation experiment to assess the effects of biochar application on the decomposition of added bagasse compost in three rural soils with different pH values and textures. Two rice hull biochars, produced through slow pyrolization at 400 °C (RHB-400 and 700 °C (RHB-700, with application rates of 1%, 2%, and 4% (w/w, were separately incorporated into soils with and without compost (1% (w/w application rate. Experimental results indicated that C mineralization rapidly increased at the beginning in all treatments, particularly in those involving 2% and 4% biochar. The biochar addition increased C mineralization by 7.9%–48% in the compost-amended soils after 70 days incubation while the fractions of mineralized C to applied C significantly decreased. Moreover, the estimated maximum of C mineralization amount in soils treated with both compost and biochar were obviously lower than expectation calculated by a double exponential model (two pool model. Based on the micromorphological observation, added compost was wrapped in the soil aggregates formed after biochar application and then may be protected from decomposing by microbes. Co-application of compost with biochar may be more efficient to stabilize and sequester C than individual application into the studied soils, especially for the biochar produced at high pyrolization temperature.

  12. Investigation of Influence Zones Induced by Shallow Tunnelling in Soft Soils

    NARCIS (Netherlands)

    Vu Minh, N.; Broere, W.; Bosch, J.W.

    2017-01-01

    The extent of the influence zone affected by shallow tunnelling depends on the value of volume loss which normally represents the amount of over-excavation and stress changes induced in the soil. This paper combines upper and lower estimates of volume loss for different soft soils and

  13. Sewage sludge biochar influence upon rice (Oryza sativa L) yield, metal bioaccumulation and greenhouse gas emissions from acidic paddy soil.

    Science.gov (United States)

    Khan, Sardar; Chao, Cai; Waqas, Muhammad; Arp, Hans Peter H; Zhu, Yong-Guan

    2013-08-06

    Biochar addition to