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Sample records for aged pah-contaminated soil

  1. Long-term assessment of natural attenuation: statistical approach on soils with aged PAH contamination.

    PubMed

    Ouvrard, Stéphanie; Chenot, Elodie-Denise; Masfaraud, Jean-François; Schwartz, Christophe

    2013-07-01

    Natural attenuation processes valorization for PAH-contaminated soil remediation has gained increasing interest from site owners. A misunderstanding of this method and a small amount of data available does not encourage its development. However, monitored natural attenuation (MNA) offers a valuable, cheaper and environmentally friendly alternative to more classical options such as physico-chemical treatments (e.g., chemical oxidation, thermal desorption). The present work proposes the results obtained during a long-term natural attenuation assessment of historically contaminated industrial soils under real climatic conditions. This study was performed after a 10 year natural attenuation period on 60 off-ground lysimeters filled with contaminated soils from different former industrial sites (coking industry, manufactured gas plants) whose initial concentration of PAH varied between 380 and 2,077 mg kg(-1). The analysed parameters included leached water characterization, soil PAH concentrations, evaluation of vegetation cover quality and quantity. Results showed a good efficiency of the PAH dissipation and limited transfer of contaminants to the environment. It also highlighted the importance of the fine soil fractions in controlling PAH reactivity. PAH dissipation through water leaching was limited and did not present a significant risk for the environment. This PAH water concentration appeared however as a good indicator of overall dissipation rate, thereby illustrating the importance of pollutant availability in predicting its degradation potential.

  2. Effects of soil amendment with different carbon sources and other factors on the bioremediation of an aged PAH-contaminated soil.

    PubMed

    Teng, Ying; Luo, Yongming; Ping, Lifeng; Zou, Dexun; Li, Zhengao; Christie, Peter

    2010-04-01

    Carbon supplementation, soil moisture and soil aeration are believed to enhance in situ bioremediation of PAH-contaminated soils by stimulating the growth of indigenous microorganisms. However, the effects of added carbon and nitrogen together with soil moisture and soil aeration on the dissipation of PAHs and on associated microbial counts have yet to be fully assessed. In this study the effects on bioremediation of carbon source, carbon-to-nitrogen ratio, soil moisture and aeration on an aged PAH-contaminated agricultural soil were studied in microcosms over a 90-day period. Additions of starch, glucose and sodium succinate increased soil bacterial and fungal counts and accelerated the dissipation of phenanthrene and benzo(a)pyrene in soil. Decreases in phenanthrene and benzo(a)pyrene concentrations were effective in soil supplemented with glucose and sodium succinate (both 0.2 g C kg(-1) dry soil) and starch (1.0 g C kg(-1) dry soil). The bioremediation effect at a C/N ratio of 10:1 was significantly higher (P < 0.05) than at a C/N of either 25:1 or 40:1. Soil microbial counts and PAH dissipation were lower in the submerged soil but soil aeration increased bacterial and fungal counts, enhanced indigenous microbial metabolic activities, and accelerated the natural degradation of phenanthrene and benzo(a)pyrene. The results suggest that optimizing carbon source, C/N ratio, soil moisture and aeration conditions may be a feasible remediation strategy in certain PAH contaminated soils with large active microbial populations.

  3. [Interactive effect of spent mushroom compost and rhamnolipids to enhance the efficiency of alfalfa remediation of aged PAHs contaminated soil].

    PubMed

    Zhang, Jing; Lin, Xian-Gui; Li, Xuan-Zhen; Yin, Rui

    2010-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are a group of the most widespread organic pollutants, which distributed widely in soil and sediment. Pot experiment was conducted to improve efficiency of phytoremediation using alfalfa (Medicago sativa L.) in aged PAHs contaminated soil by introducing spent mushroom compost and rhamnolipids. Plant biomass, PAHs concentrations, number of soil microorganism, soil enzyme activity and soil microbial functional diversity were determined after 60 days of alfalfa growth. The results showed that within 60 days, removal ratio of PAHs in treatment of alfalfa alone (AL) reached to 14.43%, while removal ratio of PAHs in treatments of "GZ + RH0.5, + AL" and "GZ + RH1.0 + AL" reached to 32.64% and 36.95%, which were 115.45% and 156.06% higher than that of phytoremediation. Contrasted to the control, the treatment of "GZ + RH1.0 + AL" had more plant biomass than others, shoot and root dry weight were 1.05 g/pot and 0.20 g/pot, respectively. During the process of phytoremediation, the number of soil bacteria and fungi were greatly increased by "GZ + RH1.0 + AL" and reached to 31.37 x 10(6) CFU x g(-1) and 5.86 x 10(6) CFU x g(-1), especially the number of PAHs-degrading bacteria reached to 39.57 x 10(5) MPN x g(-1), which were 29 times more than control treatment and 4 times more than treatment of alfalfa alone (AL). Moreover, soil dehydrogenase activity and the functional diversity of soil microbial community were increased significantly by the treatment of "GZ + RH1.0 + AL", respectively. Therefore, interaction of spent mushroom compost and rhamnolipids to enhance the phytoremediation efficiency had satisfied results in removal aged PAHs from an agricultural soil, the feasibility of this method needed to be further proved by large-area scale field experiment.

  4. Impact of clay mineral, wood sawdust or root organic matter on the bacterial and fungal community structures in two aged PAH-contaminated soils.

    PubMed

    Cébron, Aurélie; Beguiristain, Thierry; Bongoua-Devisme, Jeanne; Denonfoux, Jérémie; Faure, Pierre; Lorgeoux, Catherine; Ouvrard, Stéphanie; Parisot, Nicolas; Peyret, Pierre; Leyval, Corinne

    2015-09-01

    The high organic pollutant concentration of aged polycyclic aromatic hydrocarbon (PAH)-contaminated wasteland soils is highly recalcitrant to biodegradation due to its very low bioavailability. In such soils, the microbial community is well adapted to the pollution, but the microbial activity is limited by nutrient availability. Management strategies could be applied to modify the soil microbial functioning as well as the PAH contamination through various amendment types. The impact of amendment with clay minerals (montmorillonite), wood sawdust and organic matter plant roots on microbial community structure was investigated on two aged PAH-contaminated soils both in laboratory and 1-year on-site pot experiments. Total PAH content (sum of 16 PAHs of the US-EPA list) and polar polycyclic aromatic compounds (pPAC) were monitored as well as the available PAH fraction using the Tenax method. The bacterial and fungal community structures were monitored using fingerprinting thermal gradient gel electrophoresis (TTGE) method. The abundance of bacteria (16S rRNA genes), fungi (18S rRNA genes) and PAH degraders (PAH-ring hydroxylating dioxygenase and catechol dioxygenase genes) was followed through qPCR assays. Although the treatments did not modify the total and available PAH content, the microbial community density, structure and the PAH degradation potential changed when fresh organic matter was provided as sawdust and under rhizosphere influence, while the clay mineral only increased the percentage of catechol-1,2-dioxygenase genes. The abundance of bacteria and fungi and the percentage of fungi relative to bacteria were enhanced in soil samples supplemented with wood sawdust and in the plant rhizospheric soils. Two distinct fungal populations developed in the two soils supplemented with sawdust, i.e. fungi related to Chaetomium and Neurospora genera and Brachyconidiellopsis and Pseudallescheria genera, in H and NM soils respectively. Wood sawdust amendment favoured the

  5. Feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate-based Fenton treatment via parametric and kinetic studies.

    PubMed

    Yap, Chiew Lin; Gan, Suyin; Ng, Hoon Kiat

    2015-01-01

    This study focuses on the feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate (EL)-based Fenton treatment via a combination of parametric and kinetic studies. An optimised operating condition was observed at 66.7 M H2O2 with H2O2/Fe(2+) of 40:1 for low soil organic carbon (SOC) content and mildly acidic soil (pH 6.2), and 10:1 for high SOC and very acidic soil (pH 4.4) with no soil pH adjustment. The desorption kinetic was only mildly shifted from single equilibrium to dual equilibrium of the first-order kinetic model upon ageing. Pretreatment with EL fc = 0.60 greatly reduced the mass transfer coefficient especially for the slow desorbed fraction (kslow) of high molecular weight (HMW) PAHs, largely contributed by the concentration gradient created by EL-enhanced solubility. As the major desorption obstacle was almost fully overcome by the pretreatment, the pseudo-first-order kinetic reaction rate constant of PAHs degradation of aged soils was statistically discernible from that of freshly contaminated soils but slightly reduced in high SOC and high acidity soil. Stabilisation of H2O2 by EL addition in combination with reduced Fe(2+) catalyst were able to slow the decomposition rate of H2O2 even at higher soil pH. PMID:25065478

  6. Feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate-based Fenton treatment via parametric and kinetic studies.

    PubMed

    Yap, Chiew Lin; Gan, Suyin; Ng, Hoon Kiat

    2015-01-01

    This study focuses on the feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate (EL)-based Fenton treatment via a combination of parametric and kinetic studies. An optimised operating condition was observed at 66.7 M H2O2 with H2O2/Fe(2+) of 40:1 for low soil organic carbon (SOC) content and mildly acidic soil (pH 6.2), and 10:1 for high SOC and very acidic soil (pH 4.4) with no soil pH adjustment. The desorption kinetic was only mildly shifted from single equilibrium to dual equilibrium of the first-order kinetic model upon ageing. Pretreatment with EL fc = 0.60 greatly reduced the mass transfer coefficient especially for the slow desorbed fraction (kslow) of high molecular weight (HMW) PAHs, largely contributed by the concentration gradient created by EL-enhanced solubility. As the major desorption obstacle was almost fully overcome by the pretreatment, the pseudo-first-order kinetic reaction rate constant of PAHs degradation of aged soils was statistically discernible from that of freshly contaminated soils but slightly reduced in high SOC and high acidity soil. Stabilisation of H2O2 by EL addition in combination with reduced Fe(2+) catalyst were able to slow the decomposition rate of H2O2 even at higher soil pH.

  7. Landfarming in a PAH-contaminated soil.

    PubMed

    Picado, A; Nogueira, A; Baeta-Hall, L; Mendonça, E; de Fátima Rodrigues, M; do Céu Sàágua, M; Martins, A; Anselmo, A M

    2001-01-01

    The present work describes a coke oven soil treatability study by land-farming, conducted on-site in a field scale facility covering 100 m2. The soil contamination was mainly due to high concentrations of polynuclear aromatic hydrocarbons (PAHs) up to 1,140 mg/Kg dry weight (sigma EPA). Along the treatment process the soil was characterised at the chemical, microbiological and ecotoxicological levels. After 3 months a reduction of 63% in total PAHs concentration was observed, being detected a more pronounced reduction for PAHs with 2, 3 and 4 rings (79%). Concomitantly, a change in the composition of the microbial population was observed with a significant increase in the PAHs degrading and total heterotrophic colonies. Concerning the ecotoxicity and genotoxicity data no effect was detected in the treated soil samples eluates.

  8. Bioremediation of PAH contaminated soil samples

    SciTech Connect

    Joshi, M.M.; Lee, S.

    1994-12-31

    Soils contaminated with polynuclear aromatic hydrocarbons (PAHs) pose a hazard to life. The remediation of such sites can be done using physical, chemical, and biological treatment methods or a combination of them. It is of interest to study the decontamination of soil using bioremediation. The experiments were conducted using Acinetobacter (ATCC 31012) at room temperature without pH or temperature control. In the first series of experiments, contaminated soil samples obtained from Alberta Research Council were analyzed to determine the toxic contaminant and their composition in the soil. These samples were then treated using aerobic fermentation and removal efficiency for each contaminant was determined. In the second series of experiments, a single contaminant was used to prepare a synthetic soil sample. This sample of known composition was then treated using aerobic fermentation in continuously stirred flasks. In one set of flasks, contaminant was the only carbon source and in the other set, starch was an additional carbon source. In the third series of experiments, the synthetic contaminated soil sample was treated in continuously stirred flasks in the first set and in fixed bed in the second set and the removal efficiencies were compared. The removal efficiencies obtained indicated the extent of biodegradation for various contaminants, the effect of additional carbon source, and performance in fixed bed without external aeration.

  9. Ethanol-enhanced bioremediation of PAH-contaminated soils

    SciTech Connect

    Lee, P.H.; Ong, S.K.; Golchin, J.

    1999-07-01

    Bioremediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) is highly challenging because of the low solubility and strong sorption properties of PAHs to soil organic matter. Two PAH-contaminated soils from former manufactured gas plant (MGP) sites were pretreated with ethanol to enhance the bioavailability of PAH compounds. The biodegradation of various PAHs in the pretreated soils was assessed using soil slurry reactor studies. The time needed to degrade 90% of the total PAH in the pretreated soils was at least 5 days faster than soils that were not pretreated with ethanol. A distinctive advantage with the pretreatment of soils with ethanol was the enhanced removal of 4-ring compounds such as chrysene. Approximately 90% of chrysene in the ethanol-treated soils were removed within 15 days while soils without pretreatment needed more than 30 days to obtain similar removal levels. After 35 days of biotreatment in the slurry reactors, approximately 40% of benzo(a)pyrene were removed in the ethanol-treated soils while only 20% were removed in soils not pretreated with ethanol.

  10. LAND TREATMENT OF PAH-CONTAMINATED SOIL: PERFORMANCE MEASURED BY CHEMICAL AND TOXICITY ASSAYS

    EPA Science Inventory

    The performance of a soil remediation process can be determined by measuring the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycyclic armomatic hydrocarbon (PAH)-contaminated soil from a ...

  11. LAND TREATMENT OF PAH-CONTAMINATED SOIL: PERFORMANCE MEASURED BY CHEMICAL AND TOXICITY ASSAYS

    EPA Science Inventory

    The performance of a soil remediation process can be determined by measuring the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycyclic aromatic hydrocarbon (PAH)-contaminated soil from a ...

  12. Ecotoxicity of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil.

    PubMed

    Eom, I C; Rast, C; Veber, A M; Vasseur, P

    2007-06-01

    us to identify inorganic water-extractable pollutants as responsible for toxicity on aquatic species, especially copper for effects on D. magna and C. dubia. The soil toxicity on collembolae and earthworms could be explained by 4 PAH congeners-fluorene, phenanthrene, pyrene, and fluoranthene. Yet, toxicity of the cokery soil as a whole was much lower than toxicity that could be deduced from the concentration of each congener in spiked soils, indicating that pollutants in the soil became less bioavailable with ageing.

  13. Plant--rhizosphere-microflora association during phytoremediation of PAH-contaminated soil.

    PubMed

    Muratova, A; Hūbner, Th; Tischer, S; Turkovskaya, O; Möder, M; Kuschk, P

    2003-01-01

    The capability of plants to promote the microbial degradation of pollutants in rhizosphere soil is a principal mechanism of phytoremediation of PAH-contaminated soil. The formation of a specific rhizosphere microbocenosis with a high degradative potential toward contaminants is largely determined by plant species. The comparative PAH-degradation in unplanted soil and in soil planted with reed (Phragmites australis) and alfalfa (Medicago sativa) was studied in pot experiments during 2 years. Both alfalfa and reed successfully remediated contaminated soil by degrading 74.5 and 68.7% of PAHs, respectively. The study of the rhizosphere, rhizoplane, and unplanted-soil microflora in experimental pots showed that alfalfa stimulated the rhizosphere microflora of PAH-contaminated soil more effectively than did reed. Alfalfa clearly enhanced both the total number of microorganisms (1.3 times, according to fluorescence microscopy data) and the rate of the PAH-degrading population (almost seven times, according to plate counting). The degradative potential of its rhizosphere microflora toward PAHs was higher than the degradative activity of the reed rhizosphere. This study provides relevant information for the successful application of alfalfa to phytoremediate PAH-contaminated soil.

  14. The effects of PAH contamination on soil invertebrate communities

    SciTech Connect

    Snow-Ashbrook, J.L.; Erstfeld, K.M.

    1995-12-31

    Soils were collected from an abandoned industrial site to study the effects of historic polycyclic aromatic hydrocarbons (PAHs) on soil invertebrate communities. Nematode abundance and diversity, microarthropod abundance (orders Collembola and Acarina) and earthworm growth were evaluated. Physical and chemical characteristics of soils may affect both invertebrate community structure and the mobility/bioavailability of pollutants in soils. Soil characteristics were measured and included with PAH data in multiple regression analyses to identify factors which influences the responses observed in the soil invertebrate community. Positive associations were observed between eight invertebrate community endpoints and soil PAH content. For all of these endpoints but one, a higher degree of variability was explained when both PAH content and soil characteristics were considered. It is theorized that the positive response to soil PAH content may be the result of an increased abundance of PAH-degrading soil microbes. Increased microbial abundance could stimulate invertebrate communities by providing a direct food source or increasing the abundance of microbially-produced nutrients. These results suggest that both PAH content and soil characteristics significantly influenced the soil invertebrate community. It is not clear whether these factors influenced the invertebrate community independently, or whether differences in soil characteristics affected the community response by influencing the mobility or bioavailability of PAHs.

  15. Effect of Rhizosphere Enzymes on Phytoremediation in PAH-Contaminated Soil Using Five Plant Species

    PubMed Central

    Liu, Rui; Dai, Yuanyuan; Sun, Libo

    2015-01-01

    A pot experiment was performed to study the effectiveness of remediation using different plant species and the enzyme response involved in remediating PAH-contaminated soil. The study indicated that species Echinacea purpurea, Festuca arundinacea Schred, Fire Phoenix (a combined F. arundinacea), and Medicago sativa L. possess the potential for remediation in PAH-contaminated soils. The study also determined that enzymatic reactions of polyphenol oxidase (except Fire Phoenix), dehydrogenase (except Fire Phoenix), and urease (except Medicago sativa L.) were more prominent over cultivation periods of 60d and 120d than 150d. Urease activity of the tested species exhibited prominently linear negative correlations with alkali-hydrolyzable nitrogen content after the tested plants were cultivated for 150d (R2 = 0.9592). The experiment also indicated that alkaline phosphatase activity in four of the five tested species (Echinacea purpurea, Callistephus chinensis, Festuca arundinacea Schred and Fire Phoenix) was inhibited during the cultivation process (at 60d and 120d). At the same time, the study determined that the linear relationship between alkaline phosphatase activity and effective phosphorus content in plant rhizosphere soil exhibited a negative correlation after a growing period of 120d (R2 = 0.665). Phytoremediation of organic contaminants in the soil was closely related to specific characteristics of particular plant species, and the catalyzed reactions were the result of the action of multiple enzymes in the plant rhizosphere soil. PMID:25822167

  16. [Bioremediation of PAHs contaminated soil from Beijing coking plant by Lasiodiplodia theobromae].

    PubMed

    Zhang, Zhi-yuan; Wang, Cui-ping; Liu, Hai-bin; Sun, Hong-wen

    2012-08-01

    Bioremediation of PAHs contaminated soil from Beijing Coking Plant was performed using a novel fungal strain Lasiodiplodia theobromae (L. theobromae). Moreover, enhanced bioremediation of PAHs contaminated soil was investigated in the presence of different concentrations of Tween 80 and hydroxypropyl-beta-cyclodextrin (HPCD). The correlation of the dynamics of enzyme activities during remediation and the degradation of PAHs was analyzed. The results showed that the degradation rate of PAHs increased to 45.3% on the 70th day after addition of L. theobromae, which was 30 percentage points higher than that of the control group. At an optimum concentration of 2 g x kg(-1) for Tween 80 and 1 g x kg(-1) for HPCD, the degradation rate of PAHs was enhanced to 65.8% and 63.9%, respectively, which was 50 percentage points higher than that of the control group. Hydrogen peroxidase and invertase activities in soil in the bioremediation group with only L. theobromae and the surfactant enhanced group were both enhanced twice more than that of the control group. These results showed that L. theobromae may produce hydrogen peroxidase and invertase or have synergic effect with indigenous microorganisms. Correlation analysis showed that the correlation coefficients of PAHs degradation rate and maximum enzyme activities of hydrogen peroxidase and invertase were 0.781 and 0.837, respectively. Therefore, the correlation between invertase activities and degradation rate was higher.

  17. [Bioremediation of PAHs contaminated soil from Beijing coking plant by Lasiodiplodia theobromae].

    PubMed

    Zhang, Zhi-yuan; Wang, Cui-ping; Liu, Hai-bin; Sun, Hong-wen

    2012-08-01

    Bioremediation of PAHs contaminated soil from Beijing Coking Plant was performed using a novel fungal strain Lasiodiplodia theobromae (L. theobromae). Moreover, enhanced bioremediation of PAHs contaminated soil was investigated in the presence of different concentrations of Tween 80 and hydroxypropyl-beta-cyclodextrin (HPCD). The correlation of the dynamics of enzyme activities during remediation and the degradation of PAHs was analyzed. The results showed that the degradation rate of PAHs increased to 45.3% on the 70th day after addition of L. theobromae, which was 30 percentage points higher than that of the control group. At an optimum concentration of 2 g x kg(-1) for Tween 80 and 1 g x kg(-1) for HPCD, the degradation rate of PAHs was enhanced to 65.8% and 63.9%, respectively, which was 50 percentage points higher than that of the control group. Hydrogen peroxidase and invertase activities in soil in the bioremediation group with only L. theobromae and the surfactant enhanced group were both enhanced twice more than that of the control group. These results showed that L. theobromae may produce hydrogen peroxidase and invertase or have synergic effect with indigenous microorganisms. Correlation analysis showed that the correlation coefficients of PAHs degradation rate and maximum enzyme activities of hydrogen peroxidase and invertase were 0.781 and 0.837, respectively. Therefore, the correlation between invertase activities and degradation rate was higher. PMID:23213912

  18. Determination of biodegradation potential by two culture-independent methods in PAH-contaminated soils.

    PubMed

    Moon, H S; Kahng, H-Y; Kim, J Y; Kukor, J J; Nam, K

    2006-04-01

    Biodegradation potentials of polycyclic aromatic hydrocarbons (PAHs) were determined with soil samples collected from various depths of a PAH-contaminated site and of a site nearby where PAHs were not found. Putative dioxygenase genes were amplified by a primer set specific for initial dioxygenases and identified by web-based database homology search. They were further categorized into several groups of which four dioxygenases were selected as probes for DNA hybridization. The hybridization signals according to the presence of putative dioxygenases were positively related to the extent of PAH contamination. However, the signal intensities varied depending on the probes hybridized and moreover were not consistent with PAH biodegradation activities determined by CO2 evolution. Despite widely accepted advantages of molecular biodegradation assessment, our data clearly present the variations of assessment results depending on the genetic information used and suggest that the methodology may tend to underestimate the real biodegradation capacity of a site probably due to the limited dioxygenase database available at the moment. Therefore, the molecular assessment of biodegradation potential should involve a very careful primer and probe design and an extensive microbiological examination of a site of interest to accurately delineate the biodegradation potential of the site.

  19. Importance of organic amendment characteristics on bioremediation of PAH-contaminated soil.

    PubMed

    Lukić, B; Huguenot, D; Panico, A; Fabbricino, M; van Hullebusch, E D; Esposito, G

    2016-08-01

    This study investigates the importance of the organic matter characteristics of several organic amendments (i.e., buffalo manure, food and kitchen waste, fruit and vegetables waste, and activated sewage sludge) and their influence in the bioremediation of a polycyclic aromatic hydrocarbons (PAH)-contaminated soil. The removal of low molecular weights (LMW) and high molecular weights (HMW) PAHs was monitored in four bioremediation reactors and used as an indicator of the role of organic amendments in contaminant removal. The total initial concentration of LMW PAHs was 234 mg kg(-1) soil (dry weight), while the amount for HMW PAHs was 422 mg kg(-1) soil (dry weight). Monitoring of operational parameters and chemical analysis was performed during 20 weeks. The concentrations of LMW PAH residues in soil were significantly lower in reactors that displayed a mesophilic phase, i.e., 11 and 15 %, compared to reactors that displayed a thermophilic phase, i.e., 29 and 31 %. Residual HMW PAHs were up to five times higher compared to residual LMW PAHs, depending on the reactor. This demonstrated that the amount of added organic matter and macronutrients such as nitrogen and phosphorus, the biochemical organic compound classes (mostly soluble fraction and proteins), and the operational temperature are important factors affecting the overall efficiency of bioremediation. On that basis, this study shows that characterization of biochemical families could contribute to a better understanding of the effects of organic amendments and clarify their different efficiency during a bioremediation process of PAH-contaminated soil.

  20. Importance of organic amendment characteristics on bioremediation of PAH-contaminated soil.

    PubMed

    Lukić, B; Huguenot, D; Panico, A; Fabbricino, M; van Hullebusch, E D; Esposito, G

    2016-08-01

    This study investigates the importance of the organic matter characteristics of several organic amendments (i.e., buffalo manure, food and kitchen waste, fruit and vegetables waste, and activated sewage sludge) and their influence in the bioremediation of a polycyclic aromatic hydrocarbons (PAH)-contaminated soil. The removal of low molecular weights (LMW) and high molecular weights (HMW) PAHs was monitored in four bioremediation reactors and used as an indicator of the role of organic amendments in contaminant removal. The total initial concentration of LMW PAHs was 234 mg kg(-1) soil (dry weight), while the amount for HMW PAHs was 422 mg kg(-1) soil (dry weight). Monitoring of operational parameters and chemical analysis was performed during 20 weeks. The concentrations of LMW PAH residues in soil were significantly lower in reactors that displayed a mesophilic phase, i.e., 11 and 15 %, compared to reactors that displayed a thermophilic phase, i.e., 29 and 31 %. Residual HMW PAHs were up to five times higher compared to residual LMW PAHs, depending on the reactor. This demonstrated that the amount of added organic matter and macronutrients such as nitrogen and phosphorus, the biochemical organic compound classes (mostly soluble fraction and proteins), and the operational temperature are important factors affecting the overall efficiency of bioremediation. On that basis, this study shows that characterization of biochemical families could contribute to a better understanding of the effects of organic amendments and clarify their different efficiency during a bioremediation process of PAH-contaminated soil. PMID:27083907

  1. Land treatment of PAH-contaminated soil: Performance measured by chemical and toxicity assays

    SciTech Connect

    Sayles, G.D.; Acheson, C.M.; Kupferle, M.J.; Shan, Y.; Zhou, Q.; Meier, J.R.; Chang, L.; Brenner, R.C.

    1999-12-01

    The performance of a soil remediation process can be determined by measuring the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycyclic aromatic hydrocarbon (PAH)-contaminated soil from a former wood-treating site was simulated at pilot scale in temperature-controlled sol pans. Nineteen two- through six-ring PAHs were monitored with time (initial total PAHs = 2,800 mg/kg). Twenty-five weeks of treatment yielded a final total PAH level of 1,160 mg/kg. Statistically significant decreases in concentrations were seen in total, two-, three-, and four-ring PAHs. Carcinogenic and five- and six-ring PAHs showed no significant change in concentration. Land treatment resulted in significant toxicity reduction based on root elongation, Allium chromosomal aberration, and solid-phase Microtox bioassays. Acute toxicity, as measured by the earthworm survival assay, was significantly reduced and completely removed. The Ames spiral plate mutagenicity assay revealed that the untreated soil was slightly mutagenic and that treatment may have reduced mutagenicity. The variety of results generated from the chemical and toxicity assays emphasize the need for conducting a battery of such tests to fully understand soil remediation processes.

  2. Aerobic Bioremediation of PAH Contaminated Soil Results in Increased Genotoxicity and Developmental Toxicity.

    PubMed

    Chibwe, Leah; Geier, Mitra C; Nakamura, Jun; Tanguay, Robert L; Aitken, Michael D; Simonich, Staci L Massey

    2015-12-01

    The formation of more polar and toxic polycyclic aromatic hydrocarbon (PAH) transformation products is one of the concerns associated with the bioremediation of PAH-contaminated soils. Soil contaminated with coal tar (prebioremediation) from a former manufactured gas plant (MGP) site was treated in a laboratory scale bioreactor (postbioremediation) and extracted using pressurized liquid extraction. The soil extracts were fractionated, based on polarity, and analyzed for 88 PAHs (unsubstituted, oxygenated, nitrated, and heterocyclic PAHs). The PAH concentrations in the soil tested, postbioremediation, were lower than their regulatory maximum allowable concentrations (MACs), with the exception of the higher molecular weight PAHs (BaA, BkF, BbF, BaP, and IcdP), most of which did not undergo significant biodegradation. The soil extract fractions were tested for genotoxicity using the DT40 chicken lymphocyte bioassay and developmental toxicity using the embryonic zebrafish (Danio rerio) bioassay. A statistically significant increase in genotoxicity was measured in the unfractionated soil extract, as well as in four polar soil extract fractions, postbioremediation (p < 0.05). In addition, a statistically significant increase in developmental toxicity was measured in one polar soil extract fraction, postbioremediation (p < 0.05). A series of morphological abnormalities, including peculiar caudal fin malformations and hyperpigmentation in the tail, were measured in several soil extract fractions in embryonic zebrafish, both pre- and postbioremediation. The increased toxicity measured postbioremediation is not likely due to the 88 PAHs measured in this study (including quinones), because most were not present in the toxic polar fractions and/or because their concentrations did not increase postbioremediation. However, the increased toxicity measured postbioremediation is likely due to hydroxylated and carboxylated transformation products of the 3- and 4-ring PAHs (PHE, 1

  3. Bioremediation of poly-aromatic hydrocarbon (PAH)-contaminated soil by composting

    SciTech Connect

    Loick, N.; Hobbs, P.J.; Hale, M.D.C.; Jones, D.L.

    2009-07-01

    This paper presents a comprehensive and critical review of research on different co-composting approaches to bioremediate hydrocarbon contaminated soil, organisms that have been found to degrade PAHs, and PAH breakdown products. Advantages and limitations of using certain groups of organisms and recommended areas of further research effort are identified. Studies investigating the use of composting techniques to treat contaminated soil are broad ranging and differ in many respects, which makes comparison of the different approaches very difficult. Many studies have investigated the use of specific bio-additives in the form of bacteria or fungi with the aim of accelerating contaminant removal; however, few have employed microbial consortia containing organisms from both kingdoms despite knowledge suggesting synergistic relationships exist between them in contaminant removal. Recommendations suggest that further studies should attempt to systemize the investigations of composting approaches to bio-remediate PAH-contaminated soil, to focus on harnessing the biodegradative capacity of both bacteria and fungi to create a cooperative environment for PAH degradation, and to further investigate the array of PAHs that can be lost during the composting process by either leaching or volatilization.

  4. Chemical-assisted phytoremediation of CD-PAHs contaminated soils using Solanum nigrum L.

    PubMed

    Yang, Chuanjie; Zhou, Qixing; Wei, Shuhe; Hu, Yahu; Bao, Yanyu

    2011-09-01

    A well-characterized cadmium (Cd) hyperaccumulating plant Solanum nigrum was grown in Cd and polycyclic aromatic hydrocarbons (PAHs) co-contaminated soil that was repeatedly amended with chemicals, including EDTA, cysteine (CY), salicylic acid (Sa), and Tween 80 (TW80), to test individual and combined treatment effects on phytoremediation of Cd-PAHs contaminated soils. Plant growth was negatively affected by exogenous chemicals except for EDTA. S. nigrum could accumulate Cd in tissues without assistant chemicals, while there was no visible effect on the degradation of PAHs. Cysteine had significant effects on phytoextraction of Cd and the highest metal extraction ratio (1.27%) was observed in 0.9 mmol/kg CY treatment. Both salicylic acid and Tween 80 had stimulative effects on the degradation of PAHs and there was the maximal degradation rate (52.6%) of total PAHs while 0.9 mmol/kg Sa was applied. Furthermore, the combined treatment T(0.1EDTA+0.9CY+0.5TW80) and T(0.5EDTA+0.9CY+03Sa) could not only increase the accumulation of Cd in plant tissues, but also promote the degradation of PAHs. These results indicated that S. nigrum might be effective in phytoextracting Cd and enhancing the biodegradation of PAHs in the co-contaminated soils with assistant chemicals. PMID:21972521

  5. Effect of land use activities on PAH contamination in urban soils of Rawalpindi and Islamabad, Pakistan.

    PubMed

    Ud Din, Ikhtiar; Rashid, Audil; Mahmood, Tariq; Khalid, Azeem

    2013-10-01

    Urbanization can increase the vulnerability of soils to various types of contamination. Increased contamination of urban soils with polycyclic aromatic hydrocarbon (PAH) could relate to increased number of petrol pump stations and mechanical workshops-a phenomenon that needs to be constantly monitored. This study was undertaken to explore the soil PAH levels in Rawalpindi and Islamabad urban areas in relation to land use activities. Composite soil samples from petrol pump stations and mechanical workshops (n = 32) areas were evaluated for five PAHs--naphthalene, phenanthrene, pyrene, benzo[a]pyrene, and indeno(1,2,3-cd)pyrene-and compared with control area locations with minimum petroleum-related activity (n = 16). Surface samples up to 3 cm depth were collected and extraction of analytes was carried out using n-hexane and dichloromethane. Prior to running the samples, standards (100 μg ml(-1)) were run on HPLC to optimize signal to noise ratio using acetonitrile as mobile phase at a flow rate of 1.25 ml/min at 40 °C. Significant differences between petrol pump stations and mechanical workshop areas were observed for individual PAH as well as with control area soil samples. Naphthalene was found to be the most abundant PAH in soil, ranging from 2.47 to 24.36 mg kg(-1). Correlation between the benzo[a]pyrene (BaP) level in soil and the total PAH concentration (r = 0.82, P < 0.0001) revealed that BaP can be used as a potential marker for PAH pollution. A clear segregation between petrogenic and pyrogenic sources of contamination was observed when low molecular weight PAHs detected in soil was plotted against high molecular weight PAHs. The former source comprised lubricants and used engine oil found at mechanical workshops, whereas the latter could be mostly attributed to vehicular emission at petrol pumps. The results indicate that PAH contamination in urban areas of Rawalpindi and Islamabad has direct relevance with land use for petroleum

  6. Application of supercritical fluid extraction (SFE) to predict bioremediation efficacy of long-term composting of PAH-contaminated soil

    SciTech Connect

    Toma Cajthaml; Vaclav Sasek

    2005-11-01

    Supercritical fluid extraction (SFE) with pure carbon dioxide was used to obtain desorption curves of PAHs from four contaminated industrial soils. These were from a former gas works, a former tar processing plant, a former wood presentation plant, and a former gas-holder site. Total PAH concentrations ranged from 1495 to 2439 mg/kg. The desorption curves were fitted with a simple two-site model to determine the rapidly released fraction (F) representing bioavailability of PAHs. The F data obtained under various SFE pressures were compared with degradation results of a composting method applied on the soils. After composting and consequent long-term maturation, the residual PAH contaminations ranged from 4 to 36% of the original values. A possible explanation of the result variations is the different bioavailability of the pollutants. The best correlations between degradation results and F fraction were obtained applying 50{sup o}C and 300 bar. The F values gave very good agreement with degradation efficiencies and the total regression coefficients (r{sup 2}) ranged from 0.81 to 0.99. The degradation results together with bioavailable fractions appeared to be consistent with organic carbon contents in the soils and with volatile fractions of organics. The results indicate that SFE could be a rapid test to predict bioremediation results of composting of PAH-contaminated soils. 23 refs., 2 figs., 3 tabs.

  7. Dynamic changes in bacterial community structure and in naphthalene dioxygenase expression in vermicompost-amended PAH-contaminated soils.

    PubMed

    Di Gennaro, Patrizia; Moreno, Beatriz; Annoni, Emanuele; García-Rodríguez, Sonia; Bestetti, Giuseppina; Benitez, Emilio

    2009-12-30

    The aim of the present study was to explore the potential for using vermicompost from olive-mill waste as an organic amendment for enhanced bioremediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated soils. The focus was to analyse the genetic potential and the naphthalene dioxygenase (NDO) expression of the bacterial communities involved in the degradation of naphthalene, as chemical model for the degradation of PAH. The structure of the metabolically active bacterial population was evidenced in the RNA-based denaturing gradient gel electrophoresis (DGGE) profiles. The relative expression of NDO was determined with real-time PCR in both the soil and the vermicompost cDNA. Naphthalene changed the structure of the metabolically active bacterial community in the vermicompost when this was artificially contaminated. When used as amendment, naphthalene-free vermicompost modified the bacterial population in the PAH-contaminated soil, evidenced in the DGGE gels after 1 month of incubation. In the amended soil, the vermicompost enhanced the NDO enzyme expression with a concomitant biodegradation of naphthalene. The effect of the vermicompost was to induce the expression of biodegradation indicator genes in the autochthonous bacterial community and/or incorporate new bacterial species capable of degrading PAH. The results indicated that vermicompost from olive-mill wastes could be considered a suitable technology to be used in PAH bioremediation.

  8. Modified Fenton oxidation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils and the potential of bioremediation as post-treatment.

    PubMed

    Venny; Gan, Suyin; Ng, Hoon Kiat

    2012-03-01

    This work focuses on the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using modified Fenton (MF) treatment coupled with a novel chelating agent (CA), a more effective technique among currently available technologies. The performance of MF treatment to promote PAH oxidation in artificially contaminated soil was investigated in a packed column with a hydrogen peroxide (H(2)O(2)) delivery system simulating in-situ soil flushing which is more representative of field conditions. The effectiveness of process parameters H(2)O(2)/soil, Fe(3+)/soil, CA/soil weight ratios and reaction time were studied using a 2(4) three level factorial design experiments. An optimised operating condition of the MF treatment was observed at H(2)O(2)/soil 0.05, Fe(3+)/soil 0.025, CA/soil 0.04 and 3h reaction time with 79.42% and 68.08% PAH removals attainable for the upper and lower parts of the soil column respectively. The effects of natural attenuation and biostimulation process as post-treatment in the remediation of the PAH-contaminated soil were also studied. In all cases, 3-aromatic ring PAH (phenanthrene) was more readily degraded than 4-aromatic ring PAH (fluoranthene) regardless of the bioremediation approach. The results revealed that both natural attenuation and biostimulation could offer remarkable enhancement of up to 6.34% and 9.38% in PAH removals respectively after 8 weeks of incubation period. Overall, the results demonstrated that combined inorganic CA-enhanced MF treatment and bioremediation serves as a suitable strategy to enhance soil quality particularly to remediate soils heavily contaminated with mixtures of PAHs.

  9. Remediation of PAH-contaminated soil by the combination of tall fescue, arbuscular mycorrhizal fungus and epigeic earthworms.

    PubMed

    Lu, Yan-Fei; Lu, Mang

    2015-03-21

    A 120-day experiment was performed to investigate the effect of a multi-component bioremediation system consisting of tall fescue (Festuca arundinacea), arbuscular mycorrhizal fungus (AMF) (Glomus caledoniun L.), and epigeic earthworms (Eisenia foetida) for cleaning up polycyclic aromatic hydrocarbons (PAHs)-contaminated soil. Inoculation with AMF and/or earthworms increased plant yield and PAH accumulation in plants. However, PAH uptake by tall fescue accounted for a negligible portion of soil PAH removal. Mycorrhizal tall fescue significantly enhanced PAH dissipation, PAH degrader density and polyphenol oxidase activity in soil. The highest PAH dissipation (93.4%) was observed in the combination treatment: i.e., AMF+earthworms+tall fescue, in which the soil PAH concentration decreased from an initial value of 620 to 41 mg kg(-1) in 120 days. This concentration is below the threshold level required for Chinese soil PAH quality (45 mg kg(-1) dry weight) for residential use.

  10. Comparison of commercial DNA extraction kits for isolation and purification of bacterial and eukaryotic DNA from PAH-contaminated soils.

    PubMed

    Mahmoudi, Nagissa; Slater, Greg F; Fulthorpe, Roberta R

    2011-08-01

    Molecular characterization of the microbial populations of soils and sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) is often a first step in assessing intrinsic biodegradation potential. However, soils are problematic for molecular analysis owing to the presence of organic matter, such as humic acids. Furthermore, the presence of contaminants, such as PAHs, can cause further challenges to DNA extraction, quantification, and amplification. The goal of our study was to compare the effectiveness of four commercial soil DNA extraction kits (UltraClean Soil DNA Isolation kit, PowerSoil DNA Isolation kit, PowerMax Soil DNA Isolation kit, and FastDNA SPIN kit) to extract pure, high-quality bacterial and eukaryotic DNA from PAH-contaminated soils. Six different contaminated soils were used to determine if there were any biases among the kits due to soil properties or level of contamination. Extracted DNA was used as a template for bacterial 16S rDNA and eukaryotic 18S rDNA amplifications, and PCR products were subsequently analyzed using denaturing gel gradient electrophoresis (DGGE). We found that the FastDNA SPIN kit provided significantly higher DNA yields for all soils; however, it also resulted in the highest levels of humic acid contamination. Soil texture and organic carbon content of the soil did not affect the DNA yield of any kit. Moreover, a liquid-liquid extraction of the DNA extracts found no residual PAHs, indicating that all kits were effective at removing contaminants in the extraction process. Although the PowerSoil DNA Isolation kit gave relatively low DNA yields, it provided the highest quality DNA based on successful amplification of both bacterial and eukaryotic DNA for all six soils. DGGE fingerprints among the kits were dramatically different for both bacterial and eukaryotic DNA. The PowerSoil DNA Isolation kit revealed multiple bands for each soil and provided the most consistent DGGE profiles among replicates for both

  11. Dynamics of nitrogen in a PAHs contaminated soil amended with biosolid or vermicompost in the presence of earthworms.

    PubMed

    Contreras-Ramos, S M; Alvarez-Bernal, D; Dendooven, L

    2007-05-01

    Nitrogen mineralization in PAHs contaminated soil in presence of Eisenia fetida amended with biosolid or vermicompost was investigated. Sterilized and unsterilized soil was contaminated with PAHs, added with E. fetida and biosolid or vermicompost and incubated aerobically for 70 days, while dynamics of inorganic N were monitored. Addition of E. fetida to sterilized soil increased concentration of NH(4)(+) 100> mg N kg(-1), while concentrations in unsterilized remained <60 mg N kg(-1) except for soil amended with biosolid plus PAHs where it increased to >80 mg kg(-1). Addition of PAHs had no significant effect on concentration of NH(4)(+) compared to the unamended soil, except in the soil added with biosolid. Addition of E. fetida to sterilized soil increased concentration of NO(2)(-) 15> mg N kg(-1) while concentrations in unsterilized soil remained <7.5 mg N kg(-1) except for soil amended with biosolid where it increased to >20 mg kg(-1). Addition of PAHs had no significant effect on concentration of NO(2)(-) compared to the unamended soil. Addition of biosolid and vermicompost increased concentration of NO(3)(-), while addition of E. fetida decreased concentration of NO(3)(-) in biosolid amended soil. It was found that NH(4)(+) and NO(2)(-) oxidizers were present in the gut of E. fetida, but their activity was not sufficient enough to inhibit a temporarily increase in concentrations of NH(4)(+) and NO(2)(-). Contamination with PAHs induced immobilization of N in biosolid or vermicompost amended soil, as did feeding of E. fetida on biosolid or vermicompost.

  12. PAHs contamination in urban soils from Lisbon: spatial variability and potential risks

    NASA Astrophysics Data System (ADS)

    Cachada, Anabela; Pereira, Ruth; Ferreira da Silva, Eduardo; Duarte, Armando

    2015-04-01

    reason is that once PAHs reach the soils, they can be incorporated into more stable solid phases over time, for instance, they can be retained in the organic phase, and this process known as aging, can be virtually irreversible. This phenomenon can be particularly relevant in urban soils since the highest levels are normally found in historical sites, suggesting a long-term accumulation as observed in the present study. The estimation of this fraction is traditionally performed by using bioassays (bioavailability), yet chemical methods can also be used (chemical availability). Following a higher tier of the risk assessment framework, some selected samples previously identified as representing a potential hazard were tested for their bioavailability (earthworm bioaccumulation assay, OECD test n° 317) and chemical availability (solid phase extraction with Tenax® and water). Results showed that in spite of the very high levels found in some samples, the risks can be negligible, since both the bioavailable and water soluble fractions were very low. The relationship between available fraction and soil properties is not clear, and differences observed between samples are probably related to the age of contamination since lower available fractions were observed in the most contaminated soils.

  13. PAH contamination in soils adjacent to a coal-transporting facility in Tapin district, south Kalimantan, Indonesia.

    PubMed

    Mizwar, Andy; Trihadiningrum, Yulinah

    2015-07-01

    This study was undertaken to determine the level of 16 polycyclic aromatic hydrocarbon (PAH), listed as priority pollutants by the United States Environmental Protection Agency (USEPA), in surface soils around a coal-transporting facility in the western part of South Kalimantan, Indonesia. Three composite soil samples were collected from a coal stockpile, coal-hauling road, and coal port. Identification and quantification of PAH was performed by gas chromatography-mass spectrometry. The total content of 16 USEPA-PAH ranged from 11.79 to 55.30 mg/kg with arithmetic mean value of 33.14 mg/kg and median of 32.33 mg/kg. The 16 USEPA-PAH measured levels were found to be greater compared with most of the literature values. The levels of high molecular-weight PAH (5- and 6-ring) were dominant and formed 67.77-80.69 % of the total 16 USEPA-PAH The most abundant of individual PAH are indeno[1,2,3-cd] pyrene and benzo[a]pyrene with concentration ranges of 2.11-20.56 and 1.59-17.84 mg/kg, respectively. The degree of PAH contamination and subsequent toxicity assessment suggest that the soils of the study area are highly contaminated and pose a potential health risk to humans.

  14. Biosurfactant from red ash trees enhances the bioremediation of PAH contaminated soil at a former gasworks site.

    PubMed

    Blyth, Warren; Shahsavari, Esmaeil; Morrison, Paul D; Ball, Andrew S

    2015-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent contaminants that accumulate in soil, sludge and on vegetation and are produced through activities such as coal burning, wood combustion and in the use of transport vehicles. Naturally occurring surfactants have been known to enhance PAH-removal from soil by improving PAH solubilization thereby increasing PAH-microbe interactions. The aim of this research was to determine if a biosurfactant derived from the leaves of the Australian red ash (Alphitonia excelsa) would enhance bioremediation of a heavily PAH-contaminated soil and to determine how the microbial community was affected. Results of GC-MS analysis show that the extracted biosurfactant was significantly more efficient than the control in regards to the degradation of total 16 US EPA priority PAHs (78.7% degradation compared to 62.0%) and total petroleum hydrocarbons (TPH) (92.9% degradation compared to 44.3%). Furthermore the quantification of bacterial genes by qPCR analysis showed that there was an increase in the number of gene copies associated with Gram positive PAH-degrading bacteria. The results suggest a commercial potential for the use of the Australian red ash tree as a source of biosurfactant for use in the accelerated degradation of hydrocarbons. PMID:26217887

  15. Biosurfactant from red ash trees enhances the bioremediation of PAH contaminated soil at a former gasworks site.

    PubMed

    Blyth, Warren; Shahsavari, Esmaeil; Morrison, Paul D; Ball, Andrew S

    2015-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent contaminants that accumulate in soil, sludge and on vegetation and are produced through activities such as coal burning, wood combustion and in the use of transport vehicles. Naturally occurring surfactants have been known to enhance PAH-removal from soil by improving PAH solubilization thereby increasing PAH-microbe interactions. The aim of this research was to determine if a biosurfactant derived from the leaves of the Australian red ash (Alphitonia excelsa) would enhance bioremediation of a heavily PAH-contaminated soil and to determine how the microbial community was affected. Results of GC-MS analysis show that the extracted biosurfactant was significantly more efficient than the control in regards to the degradation of total 16 US EPA priority PAHs (78.7% degradation compared to 62.0%) and total petroleum hydrocarbons (TPH) (92.9% degradation compared to 44.3%). Furthermore the quantification of bacterial genes by qPCR analysis showed that there was an increase in the number of gene copies associated with Gram positive PAH-degrading bacteria. The results suggest a commercial potential for the use of the Australian red ash tree as a source of biosurfactant for use in the accelerated degradation of hydrocarbons.

  16. Risk potentials for humans of original and remediated PAH-contaminated soils: application of biomarkers of effect.

    PubMed

    Roos, Peter H; Tschirbs, Sebastian; Pfeifer, Frank; Welge, Peter; Hack, Alfons; Wilhelm, Michael; Bolt, Hermann M

    2004-12-15

    Contaminated soils represent a potential health risk for the human population. Risk assessment for humans requires specific methods, which must reflect the peculiarities of human behaviour, physiology and biochemistry with respect to contaminant uptake and processing. Biomarkers of effect or exposure have become an appropriate tool. Organic pollutants influence the expression profile of cytochromes P450 (CYP), and CYP1A1 has been shown to be a suitable biomarker for polycyclic aromatic hydrocarbons (PAH). The latter are widely distributed in soils and constitute an important soil contamination. Upon intake of PAH-contaminated soils, CYP1A1 is induced in various organs of rats and minipigs. Increased CYP1A1-levels in lung, kidney and spleen, after oral soil intake, indicate that contaminants escape the primary duodenal and hepatic metabolism and reach further organs. Dose-response relationships reveal that induction effects are to be expected in children based on known exposure conditions. Generally, CYP1A1-induction does not correlate with results of toxicity tests with lower organisms, performed with the same soils. The organic carbon content is largely responsible for this discrepancy. It severely affects the toxicity of soil bound PAH for microorganisms, but obviously affects the mobilization efficiency for PAH in the gastro-intestinal tract of mammals to a minor extent. Soil remediation by different methods may result in a significant reduction of the PAH content and of toxicity. Ingestion of remediated soils by rats shows, however, that the induction potential for CYP1A1 is only slightly decreased after remediation. This means that the major inducing components resist biological remediation or soil washing and remain in the soil. Because data obtained with experimental animals form the guiding principle for in vitro tests to be developed, the suitability of the animal model used for extrapolations to humans has to be proven. Upon soil ingestion, minipigs show

  17. Efficient biodegradation of phenanthrene by a novel strain Massilia sp. WF1 isolated from a PAH-contaminated soil.

    PubMed

    Wang, Haizhen; Lou, Jun; Gu, Haiping; Luo, Xiaoyan; Yang, Li; Wu, Laosheng; Liu, Yong; Wu, Jianjun; Xu, Jianming

    2016-07-01

    A novel phenanthrene (PHE)-degrading strain Massilia sp. WF1, isolated from PAH-contaminated soil, was capable of degrading PHE by using it as the sole carbon source and energy in a range of pH (5.0-8.0), temperatures (20-35 °C), and PHE concentrations (25-400 mg L(-1)). Massilia sp. WF1 exhibited highly effective PHE-degrading ability that completely degraded 100 mg L(-1) of PHE over 2 days at optimal conditions (pH 6.0, 28 °C). The kinetics of PHE biodegradation by Massilia sp. WF1 was well represented by the Gompertz model. Results indicated that PHE biodegradation was inhibited by the supplied lactic acid but was promoted by the supplied carbon sources of glucose, citric acid, and succinic acid. Salicylic acid (SALA) and phthalic acid (PHTA) were not utilized by Massilia sp. WF1 and had no obvious effect on PHE biodegradation. Only two metabolites, 1-hydroxy-2-naphthoic acid (1H2N) and PHTA, were identified in PHE biodegradation process. Quantitatively, nearly 27.7 % of PHE was converted to 1H2N and 30.3 % of 1H2N was further metabolized to PHTA. However, the PHTA pathway was broken and the SALA pathway was ruled out in PHE biodegradation process by Massilia sp. WF1. PMID:27026540

  18. Long term impact of PAH contamination in soils on the water quality in rivers

    NASA Astrophysics Data System (ADS)

    Gateuille, David; Evrard, Olivier; Moreau-Guigon, Elodie; Chevreuil, Marc; Mouchel, Jean-Marie

    2014-05-01

    Polycyclic Aromatic Hydrocarbons constitute a large family of hazardous contaminants that are mainly released into the environment by incomplete combustion of organic matter. In the Seine River (France), high concentrations of these compounds measured in the water bodies might prevent to meet the international environmental targets requested by EU Water Framework Directive. This issue is of particular concern as PAH emissions have been steadily decreasing for several decades. Consequently, both the origin and the persistence of these pollutants have to be investigated. PAHs are known to bind onto organic matter in soils and large amount of these compounds may be found in this compartment. In order to investigate the role of soils as a contamination buffer, an ambitious sampling strategy was implemented in an upstream agricultural subcatchment (104 km²) for an entire hydrological year. The samples were collected in the different compartments (atmospheric fallout (n = 42), soil (n = 33), river water (n = 26) and suspended sediment (n=101)) and allowed to quantify the current fluxes of PAHs in the environment and to estimate their stocks in soils (12 to 220 kg.km-²). Annual mass balance calculation was conducted at the catchment scale and showed that current PAH losses were mainly due to losses (biodegradation, photo-oxidation and volatilization) within the catchments (about 80%), whereas exports due to soil erosion and riverine transport appeared to be of minor importance. When comparing the stocks in soils and the estimated annual losses, PAHs showed long decontamination times in soils (40 to 1850 years). The fate of PAHs in the catchment varied from one compound to another and was controlled by meteorological and hydrological parameters. This result highlights that soils are likely to play an important role as a secondary source for riverine contamination for a long period of time. To investigate further the relationship between the presence of PAHs in soils and

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

    PubMed

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

    2014-09-01

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

  20. Modeling in situ ozonation for the remediation of nonvolatile PAH-contaminated unsaturated soils.

    PubMed

    Kim, Jeongkon; Choi, Heechul

    2002-04-01

    Mathematical models were developed to investigate the characteristics of gaseous ozone transport under various soil conditions and the feasibility of in situ ozone venting for the remediation of unsaturated soils contaminated with phenanthrene. On the basis of assumptions for the mass transfer and reactions of ozone, three approaches were considered: equilibrium, kinetic, and lump models. Water-saturation-dependent reactions of gaseous ozone with soil organic matter (SOM) and phenanthrene were employed. The models were solved numerically by using the finite-difference method, and the model parameters were determined by using the experimental data of Hsu [The use of gaseous ozone to remediate the organic contaminants in the unsaturated soils, PhD Thesis, Michigan State Univ., East Lansing, MI, 1995]. The transport of gas-phase ozone is significantly retarded by ozone consumption due to reactions with SOM and phenanthrene, in addition to dissolution. An operation time of 156 h was required to completely remove phenanthrene in a 5-m natural soil column. In actual situations, however, the operation time is likely to be longer than the ideal time because of unknown factors including heterogeneity of the porous medium and the distribution of SOM and contaminant. The ozone transport front length was found to be very limited (< 1 m). The sensitivity analysis indicated that SOM is the single most important factor affecting in situ ozonation for the remediation of unsaturated soil contaminated with phenanthrene. Models were found to be insensitive to the reaction mechanisms of phenathrene with either gas-phase ozone or dissolved ozone. More study is required to quantify the effect of OH* formation on the removal of contaminant and on ozone transport in the subsurface.

  1. Modeling in situ ozonation for the remediation of nonvolatile PAH-contaminated unsaturated soils.

    PubMed

    Kim, Jeongkon; Choi, Heechul

    2002-04-01

    Mathematical models were developed to investigate the characteristics of gaseous ozone transport under various soil conditions and the feasibility of in situ ozone venting for the remediation of unsaturated soils contaminated with phenanthrene. On the basis of assumptions for the mass transfer and reactions of ozone, three approaches were considered: equilibrium, kinetic, and lump models. Water-saturation-dependent reactions of gaseous ozone with soil organic matter (SOM) and phenanthrene were employed. The models were solved numerically by using the finite-difference method, and the model parameters were determined by using the experimental data of Hsu [The use of gaseous ozone to remediate the organic contaminants in the unsaturated soils, PhD Thesis, Michigan State Univ., East Lansing, MI, 1995]. The transport of gas-phase ozone is significantly retarded by ozone consumption due to reactions with SOM and phenanthrene, in addition to dissolution. An operation time of 156 h was required to completely remove phenanthrene in a 5-m natural soil column. In actual situations, however, the operation time is likely to be longer than the ideal time because of unknown factors including heterogeneity of the porous medium and the distribution of SOM and contaminant. The ozone transport front length was found to be very limited (< 1 m). The sensitivity analysis indicated that SOM is the single most important factor affecting in situ ozonation for the remediation of unsaturated soil contaminated with phenanthrene. Models were found to be insensitive to the reaction mechanisms of phenathrene with either gas-phase ozone or dissolved ozone. More study is required to quantify the effect of OH* formation on the removal of contaminant and on ozone transport in the subsurface. PMID:11999632

  2. Modeling in situ ozonation for the remediation of nonvolatile PAH-contaminated unsaturated soils.

    SciTech Connect

    Kim, J.; Choi, H.; Environmental Research; Kwangju Inst. of Science and Technology

    2002-04-01

    Mathematical models were developed to investigate the characteristics of gaseous ozone transport under various soil conditions and the feasibility of in situ ozone venting for the remediation of unsaturated soils contaminated with phenanthrene. On the basis of assumptions for the mass transfer and reactions of ozone, three approaches were considered: equilibrium, kinetic, and lump models. Water-saturation-dependent reactions of gaseous ozone with soil organic matter (SOM) and phenanthrene were employed. The models were solved numerically by using the finite-difference method, and the model parameters were determined by using the experimental data of Hsu [The use of gaseous ozone to remediate the organic contaminants in the unsaturated soils, PhD Thesis, Michigan State Univ., East Lansing, MI, 1995]. The transport of gas-phase ozone is significantly retarded by ozone consumption due to reactions with SOM and phenanthrene, in addition to dissolution. An operation time of 156 h was required to completely remove phenanthrene in a 5-m natural soil column. In actual situations, however, the operation time is likely to be longer than the ideal time because of unknown factors including heterogeneity of the porous medium and the distribution of SOM and contaminant. The ozone transport front length was found to be very limited (<1 m). The sensitivity analysis indicated that SOM is the single most important factor affecting in situ ozonation for the remediation of unsaturated soil contaminated with phenanthrene. Models were found to be insensitive to the reaction mechanisms of phenanthrene with either gas-phase ozone or dissolved ozone. More study is required to quantify the effect of OH{sup {sm_bullet}} formation on the removal of contaminant and on ozone transport in the subsurface.

  3. Diffuse PAH contamination of surface soils: environmental occurrence, bioavailability, and microbial degradation.

    PubMed

    Johnsen, Anders R; Karlson, Ulrich

    2007-09-01

    The purpose of this review is to recognize the scientific and environmental importance of diffuse pollution with polycyclic aromatic hydrocarbons (PAHs). Diffuse PAH pollution of surface soil is characterized by large area extents, low PAH concentrations, and the lack of point sources. Urban and pristine topsoils receive a continuous input of pyrogenic PAHs, which induces a microbial potential for PAH degradation. The significance of this potential in relation to black carbon particles, PAH bioaccessibility, microbial PAH degradation, and the fate of diffuse PAHs in soil is discussed. Finally, the state-of-the-art methods for future investigations of the microbial degradation of diffuse PAH pollution are reviewed. PMID:17594088

  4. Bioremediation of PAH-contaminated soil by composting: a case study.

    PubMed

    Cajthaml, T; Bhatt, M; Sasek, V; Matĕjů, V

    2002-01-01

    Composting technique was used for bioremediation of industrial soil originating from a former tar-contaminated site. The composting process was regulated by aeration to keep optimal temperature gradient and concentrations of O2 and CO2 inside the composting pile. The efficiency of bioremediation was evaluated by performing analysis of 11 individual three- to six-ring unsubstituted aromatic hydrocarbons (PAH) and estimating of changes in ecotoxicity of the contaminated soil. After 42 d of composting, PAH with 3-4 rings were removed from 42 to 68%, other higher-molar mass PAH from 35 to 57%. Additional 100 d of compost maturation in open-air field did not result in a further decrease of PAH. Ecotoxicity tests performed with bioluminescent bacteria Vibrio fischerii showed a decrease in toxicity both after composting and maturation phases. However, toxicity tests on mustard-seed germination did not reveal any significant changes during composting and maturation phases.

  5. PAH contaminated soil remediation by reusing an aqueous solution of cyclodextrins.

    PubMed

    Petitgirard, Audrey; Djehiche, Mokhtar; Persello, Jacques; Fievet, Patrick; Fatin-Rouge, Nicolas

    2009-05-01

    We studied the possibility to re-use an aqueous solution of methyl-beta-cyclodextrin (bpmCD) in order to decontaminate a soil polluted by phenanthrene and pyrene. The loss of bpmCD in the soil was insignificant. In order to eliminate polycylic aromatic hydrocarbons (PAHs) from the contaminated aqueous solution, on one hand we tested their photodegradation using TiO(2) suspensions. But it was inefficient, because of the stabilisation of PAHs within the cavity of bpmCD. On the other hand, we removed PAHs by liquid-liquid extraction with colza oil. This allowed the regeneration of cyclodextrins, by concentrating the pollutants in the organic phase with a small loss of carrier. Contaminated soils were almost completely de-polluted after 2d of re-circulation, using a 10mM solution of bpmCD. To reduce the amount of bpmCD loss in the oil phase, we set the fraction of colza oil low, by using a micro-emulsion or by impregnating an organic membrane with the oil. We found this last possibility more interesting. PMID:19251300

  6. Bacterial communities in PAH contaminated soils at an electronic-waste processing center in China.

    PubMed

    Zhang, Wen; Wang, Hui; Zhang, Rui; Yu, Xie-Zhi; Qian, Pei-Yuan; Wong, M H

    2010-01-01

    Surface soils from Guiyu, China (an intense e-waste processing center) were analyzed for persistent organic pollutants (POPs) and variations in composition of the resident bacterial communities. Denaturing Gradient Gel Electrophoresis analysis of bacterial 16S rRNA gene showed that e-waste pollution altered the bacterial community structure by promoting changes in species composition and species richness. Bacterial diversity was not decreased at e-waste open-burning sites, compared with a non e-waste site (reservoir site), due to flourishing of possible POPs-consuming bacterial cohorts. PAH-incubated experiments confirmed that different levels of PAHs might affect the bacterial community by suppressing or favoring certain groups of bacteria, for instance, uncultured Clostridium sp. and Massilia sp., respectively. Taxonomic analysis indicated beta-proteobacteria and Firmicutes were abundant bacterial lineages in PAH-polluted soils. This study is the first reporting bacterial community structures at e-waste processing sites, and indicated that crude processing of e-waste has become a biohazard to the terrestrial environment warranting more extensive studies of microbial communities at e-waste polluted environments.

  7. Compound amino acids added in media improved Solanum nigrum L. phytoremediating CD-PAHS contaminated soil.

    PubMed

    Wei, Shuhe; Bai, Jiayi; Yang, Chuanjie; Zhang, Qianru; Knorrm, Klaus-Holger; Zhan, Jie; Gao, Qianhui

    2016-01-01

    Cd hyperaccumulator Solanum nigrum L. was a promising plant used to simultaneously remediate Cd-PAHs combined pollution soil through its extra accumulation capacity and rhizosphere degradation. This article compared the strengthening remediation role of cysteine (Cys), glycine (Gly) and glutamic acid (Glu) with EDTA and TW80. The results showed that the addition of 0.03 mmol L(-1) Cys, Gly, and Glu didn't significantly impact (p < 0.05) shoot biomass of S. nigrum, but obviously increased Cd concentration. Therefore, Cd capacity (µg pot(-1)) in shoots of S. nigrum was significantly increased (p < 0.05) by 37.7% compared to the control without reagent added. At the meantime, the PAHs degradation ratio in rhizoshpere was increased by 34.5%. Basically, the improving role of Cys, Gly, and Glu was higher than EDTA and TW80. The main reasons of enhanced the accumulation of S. nigrum to Cd might lie in the addition of Cys, Gly, and Glu which reduced pH and increased extractable Cd concentration in rhizosphere and phytochelatines (PCs) concentration in leaves. As for the degradation of PAHs in rhizosphere, increased microorganism number might be play important role.

  8. Heavy metal effects on the biodegradation of fluorene by Sphingobacterium sp. KM-02 isolated from PAHs-contaminated mine soil

    NASA Astrophysics Data System (ADS)

    Nam, I.; Chon, C.; Jung, K.; Kim, J.

    2012-12-01

    Polycyclic aromatic hydrocarbon compounds (PAHs) are widely distributed in the environment and occur ubiquitously in fossil fuels as well as in products of incomplete combustion and are known to be strongly toxic, often with carcinogenic and mutagenic properties. Fluorene is one of the 16 PAHs included in the list of priority pollutants of the Environmental Protection Agency. The fluorene-degrading bacterial strain Sphingobacterium sp. KM-02 was isolated from PAHs-contaminated soil near an abandoned mine impacted area by selective enrichment techniques. Fluorene added to the Sphingobacterium sp. KM-02 culture as sole carbon and energy source was 78.4% removed within 120 h. A fluorene degradation pathway is tentatively proposed based on mass spectrometric identification of the metabolic intermediates 9-fluorenone, 4-hydroxy-9-fluorenone, and 8-hydroxy-3,4-benzocoumarin. Further the ability of Sphingobacterium sp. KM-02 to bioremediate 100 mg/kg fluorene in mine soil was examined by composting under laboratory conditions. Treatment of microcosm soil with the strain KM-02 for 20 days resulted in a 65.6% reduction in total amounts. These results demonstrate that Sphingobacterium sp. KM-02 could potentially be used in the bioremediation of fluorene from contaminated soil. Mine impacted area comprises considerable amounts of heavy metals such as cadmium, lead, mercury, arsenic, and copper. Although some of these metals are necessary for biological life, excessive quantities often result in the inhibition of essential biological reactions via numerous pathways. A number of reports collectively show that various metals, such as Al, Co, Ni, Cu, Zn, Pb, and Hg at a range of concentrations have adverse effects on the degradation of organic compounds. However, at present there is only limited information on the effect of individual heavy metals on the biological degradation of polyaromatic hydrocarbons (PAHs) including fluorene. Moreover, heavy metal effects were not

  9. Tenax TA extraction to understand the rate-limiting factors in methyl-β-cyclodextrin-enhanced bioremediation of PAH-contaminated soil.

    PubMed

    Sun, Mingming; Luo, Yongming; Teng, Ying; Christie, Peter; Jia, Zhongjun; Li, Zhengao

    2013-06-01

    The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F sl and F vl ) became larger and the rate constants of slow and very slow desorption (k sl and k vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.

  10. Pilot scale ex-situ bioremediation of heavily PAHs-contaminated soil by indigenous microorganisms and bioaugmentation by a PAHs-degrading and bioemulsifier-producing strain.

    PubMed

    Sun, Guang-Dong; Xu, Yang; Jin, Jing-Hua; Zhong, Zhi-Ping; Liu, Ying; Luo, Mu; Liu, Zhi-Pei

    2012-09-30

    This study aims at the remediation of heavily PAH-contaminated soil containing 375 mg of total PAHs per kilogram dry soil. Pilot scale bioremediation experiments were carried out by three approaches with contaminated soil from abandoned sites of Beijing Coking Plant using outdoor pot trials. The first approach was bioaugmentation with a bacterial strain which degrades PAH and produces bioemulsifier, the second approach comprised of biostimulation of indigenous microorganisms with supplementing nutrients and the last approach involved the combination of both biostimulation and bioaugmentation. An on-site land farming group was set as a control in which the total PAHs and 4-6 ring-PAHs were reduced by 23.4% and 10.1%, respectively after 175 days. Meanwhile, in the first approach group, the total PAHs and 4-6 ring-PAHs were reduced by 26.82% and 35.36%, respectively; in the second approach group both percentages were 33.9% and 11.0%, respectively; while in the third approach group, these pollutants were reduced by 43.9% and 55.0%, respectively. The results obtained suggested that biostimulation and bioaugmentation combined could significantly enhance the removal of PAHs in the contaminated soil.

  11. {sup 32}P-postlabeling determination of DNA adducts in the earthworm Lumbricus terrestris exposed to PAH-contaminated soils

    SciTech Connect

    Walsh, P. |; El Adlouni, C.; Mukhopadhyay, M.J.; Nadeau, D.; Poirier, G.G.; Viel, G.

    1995-05-01

    The importance of the search for reliable biomarkers of DNA damage in environmental health assessment is well recognized by the scientific community and regulatory agencies. Among the major biomarkers of DNA damage is the measurement of DNA adducts in target cells or tissues. Up to now, DNA adduct determinations have been directed mostly toward human exposure to toxic substances from the workplace and environment. Moreover, techniques for measuring DNA adducts, and in particular the {sup 32}P-postlabelling technique, presented also the possibility of determining DNA adduct levels in endogenous animal populations exposed to polluted environments as early warning monitors of ecotoxicity. Soil contamination is becoming a major environmental issue. Therefore, numerous contaminated sites must now be remediated to protect human health and to permit new uses of these sites as agricultural, residential, or industrial areas. Fulfillment of this task requires standardized and sensitive bioassays to carry out site evaluations and to establish scientifically defensible soil quality criteria. To that effect, the earthworm appears to be one of the best organisms for use in soil toxicity evaluation. Earthworms are probably the most relevant soil species, representing 60 to 80% of the total animal biomass in soil. Present soil bioassays focus mostly on plant species with end points like seed germination, root elongation, seedling growth and seedling emergence, and on acute toxicity evaluation (re: LC 50) on the earthworm Eisenia fetida. As yet, a standardized soil invertebrate test for teratogenic or mutagenic end points has not been developed. In this paper, we report the feasibility of DNA adduct determination by {sup 32}P-postlabelling in the earthworm Lumbricus terrestris as a way to detect the presence of genotoxic substances in soils. 20 refs., 1 fig., 1 tab.

  12. [Comparison of bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil by composting in the spring and winter].

    PubMed

    Fang, Yun; Zhao, Xiu-Lan; Wei, Yuan-Song; Yang, Yu; Shen, Ying; Zheng, Jia-Xi

    2010-06-01

    In this study, lab-scale bioremediation experiments of soil contaminated by polycyclic aromatic hydrocarbon (PAHs) with aerated composting were compared in the Spring and Winter. Results showed that PAHs degradation rate in the winter was higher than that in the spring, and the total PAHs degradation rates were over 70% for both Pile 1 (the dry weight ratio of soil, swine manure and sawdust as 1: 1: 1) and Pile 2 (the dry weight ratio of soil, swine manure and sawdust as 1: 3: 1), but the PAHs degradation rate of Pile 1 as 74.61% was higher than that of Pile 2 the degradation rates of low, middle, high benzene-ring types PAHs were 66.46%, 79.12%, 75.88%, respectively. After composting most of kinds of PAHs contents in soil were less than 1 000 microg/kg (dry weight) except BbF, for example, BbF contents of these two piles in the Spring, 25 000 microg/kg and 20 000 microg/kg, respectively, were much higher than those in the winter experiments, both less than 5 000 microg/kg. The first reaction order model was used to simulate degradation of PAHs during composting, and results showed that the model was fitted better in winter (R2 > 0.6) than in spring, and the half-life of PAHs degradation in winter was about 13 d.

  13. Assessment of polycyclic aromatic hydrocarbons (PAHs) contamination in surface soil of coal stockpile sites in South Kalimantan, Indonesia.

    PubMed

    Mizwar, Andy; Priatmadi, Bambang Joko; Abdi, Chairul; Trihadiningrum, Yulinah

    2016-03-01

    Concentrations, spatial distribution, and sources of 16 polycyclic aromatic hydrocarbons (PAHs), listed as priority pollutants by the United States Environmental Protection Agency (USEPA), were investigated in surface soils of three different coal stockpile, agricultural, and residential sites in South Kalimantan Province, Indonesia. Total PAHs concentration ranged from 4.69 to 22.67 mg kg(-1)-dw. PAHs concentrations in soil of coal stockpile sites were higher than those in agricultural and residential soil. A complex of petrogenic origin and pyrolytic sources was found within the study area, as suggested by the isomeric ratios of PAHs. The results of principal component analysis and multiple linear regressions (PCA/MLR) showed that three sources contributed to the PAHs in the study area, including biomass and coal combustion (48.46%), raw coal (35.49%), and vehicular emission (16.05%). The high value of total benzo[a]pyrene equivalent concentration (B[a]Peq) suggests that local residents are exposed to a high carcinogenic potential.

  14. Effects of electrokinetic operation mode on removal of polycyclic aromatic hydrocarbons (PAHs), and the indigenous fungal community in PAH-contaminated soil.

    PubMed

    Wang, Jian; Li, Fengmei; Li, Xu; Wang, Xiujuan; Li, Xinyu; Su, Zhencheng; Zhang, Huiwen; Guo, Shuhai

    2013-01-01

    Electrokinetic remediation is an emerging physical remediation technology for the removal of heavy metals and organic chemicals from contaminated soil. We set up a soil chamber (24 × 12 × 8 cm) with two stainless steel electrodes (12 × 0.5 cm), and a constant voltage gradient of 1.0 v cm(-1) or 2.0 v cm(-1) was applied to study the effects of unidirectional and altered directional electric field operation modes on the moisture content and pH, the removal rate of PAHs, and the abundance and diversity of indigenous fungi in a PAH-contaminated soil at the Benxi Iron and Steel Group Corporation (N41°17'24.4″, E123°43'05.8″), Liaoning Province, Northeast China. Electrokinetic remediation increased the PAH removal rate, but had less effect on soil moisture content and pH, in comparison with the control. In the 1 v cm(-1) altered directional operation, in particular, the PAH removal rate by the end of the experiment (on day 23) had increased from 5.2% of the control to 13.84% and 13.69% at distances of 4 and 20 cm from the anode, respectively, and to 18.97% in the middle region of the soil chamber. On day 23, the indigenous fungal 18S rRNA gene copy numbers and community diversity were significantly higher in a voltage gradient of 1 v cm(-1) than in a voltage gradient 2 v cm(-1). An altered directional operation was more conducive to the fungal community's uniform distribution than was a unidirectional operation of the electric field. We found the major PAH-degrading fungi Fusarium oxysporum and Rhizophlyctis rosea to be present under EK remediation. We suggest that a 1 v cm(-1) altered directional operation could be an appropriate electrokinetic operation mode for PAH removal, and the maintenance of abundance and diversity of the indigenous fungal community.

  15. Effects of electrokinetic operation mode on removal of polycyclic aromatic hydrocarbons (PAHs), and the indigenous fungal community in PAH-contaminated soil.

    PubMed

    Wang, Jian; Li, Fengmei; Li, Xu; Wang, Xiujuan; Li, Xinyu; Su, Zhencheng; Zhang, Huiwen; Guo, Shuhai

    2013-01-01

    Electrokinetic remediation is an emerging physical remediation technology for the removal of heavy metals and organic chemicals from contaminated soil. We set up a soil chamber (24 × 12 × 8 cm) with two stainless steel electrodes (12 × 0.5 cm), and a constant voltage gradient of 1.0 v cm(-1) or 2.0 v cm(-1) was applied to study the effects of unidirectional and altered directional electric field operation modes on the moisture content and pH, the removal rate of PAHs, and the abundance and diversity of indigenous fungi in a PAH-contaminated soil at the Benxi Iron and Steel Group Corporation (N41°17'24.4″, E123°43'05.8″), Liaoning Province, Northeast China. Electrokinetic remediation increased the PAH removal rate, but had less effect on soil moisture content and pH, in comparison with the control. In the 1 v cm(-1) altered directional operation, in particular, the PAH removal rate by the end of the experiment (on day 23) had increased from 5.2% of the control to 13.84% and 13.69% at distances of 4 and 20 cm from the anode, respectively, and to 18.97% in the middle region of the soil chamber. On day 23, the indigenous fungal 18S rRNA gene copy numbers and community diversity were significantly higher in a voltage gradient of 1 v cm(-1) than in a voltage gradient 2 v cm(-1). An altered directional operation was more conducive to the fungal community's uniform distribution than was a unidirectional operation of the electric field. We found the major PAH-degrading fungi Fusarium oxysporum and Rhizophlyctis rosea to be present under EK remediation. We suggest that a 1 v cm(-1) altered directional operation could be an appropriate electrokinetic operation mode for PAH removal, and the maintenance of abundance and diversity of the indigenous fungal community. PMID:23947706

  16. Different mechanisms of handling ingested polycyclic aromatic hydrocarbons in mammalian species: organ-specific response patterns of CYP1A1-induction after oral intake of PAH-contaminated soils.

    PubMed

    Roos, P H; Tschirbs, S; Hack, A; Welge, P; Wilhelm, M

    2004-09-01

    Potential effects of xenobiotics on humans are largely derived from studies with animal models. However, due to species-specific processing of xenobiotics, susceptibilities to xenobiotic-dependent adverse effects are known to differ between species. We analysed the basal expression of cytochrome P450 (CYP) enzymes in several organs of minipigs and rats, and their inducibility upon oral intake of soils containing polycyclic aromatic hydrocarbons (PAH). CYP-specific enzymatic activities were determined in duodenum, liver and kidney microsomes. Upon ingestion of PAH-contaminated soils, CYP1A1 is differentially induced in a tissue-specific and dose-dependent manner in duodenum, liver and kidney of minipigs and rats. In the duodenum, the induction response is low in rats (about 4-fold) but it is high in minipigs (8-230-fold). By contrast, induced hepatic CYP1A1-dependent EROD-activity is higher in rats than in minipigs. The dose-response profile for renal CYP1A1 parallels that in the liver of either species but EROD-activities are 10-20 times lower than in the liver. Liver microsomal CYP2E1 is only slightly modulated in its expression by ingestion of PAH-contaminated soils in both species, whereas CYP3A-dependent testosterone 2beta- and 6beta-hydroxylation is increased in liver of rats but not in minipigs. The hepatic capacity for catechol oestrogen formation, i.e., the 2-hydroxylation of 17beta-oestradiol, is markedly increased in rats but not in minipigs by ingested PAH. It is concluded that different metabolic and transport pathways are used by minipigs and rats to process ingested PAH. Whereas in minipigs the duodenum appears as the first efficient barrier, rats respond by efficient metabolism in the liver. What is not known is which response profile is operative in man.

  17. Micromorphology and stable-isotope geochemistry of historical pedogenic siderite formed in PAH-contaminated alluvial clay soils, Tennessee, U.S.A

    USGS Publications Warehouse

    Driese, S.G.; Ludvigson, Greg A.; Roberts, J.A.; Fowle, D.A.; Gonzalez, Luis A.; Smith, J.J.; Vulava, V.M.; McKay, L.D.

    2010-01-01

    Alluvial clay soil samples from six boreholes advanced to depths of 400-450 cm (top of limestone bedrock) from the Chattanooga Coke Plant (CCP) site were examined micromorphologically and geochemically in order to determine if pedogenic siderite (FeCO3) was present and whether siderite occurrence was related to organic contaminant distribution. Samples from shallow depths were generally more heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) than those at greater depth. The upper 1 m in most boreholes consisted of mixtures of anthropogenically remolded clay soil fill containing coal clinker, cinder grains, and limestone gravel; most layers of coarse fill were impregnated with creosote and coal tar. Most undisturbed soil (below 1 m depth) consisted of highly structured clays exhibiting fine subangular blocky ped structures, as well as redox-related features. Pedogenic siderite was abundant in the upper 2 m of most cores and in demonstrably historical (< 100 years old) soil matrices. Two morphologies were identified: (1) sphaerosiderite crystal spherulites ranging from 10 to 200 um in diameter, and (2) coccoid siderite comprising grape-like "clusters" of crystals 5-20 ??n in diameter. The siderite, formed in both macropores and within fine-grained clay matrices, indicates development of localized anaerobic, low-Eh conditions, possibly due to microbial degradation of organic contaminants. Stable-isotope compositions of the siderite have ??13C values spanning over 25%o (+7 to - 18%o VPDB) indicating fractionation of DIC by multiple microbial metabolic pathways, but with relatively constant ??18O values from (-4.8 ?? 0.66%o VPDB) defining a meteoric sphaerosiderite line (MSL). Calculated isotope equilibrium water ??18O values from pedogenic siderites at the CCP site are from 1 to 5 per mil lighter than the groundwater ??18O values that we estimate for the site. If confirmed by field studies in progress, this observation might call for a reevaluation of

  18. Response of microbial activities and diversity to PAHs contamination at coal tar contaminated land

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaohui; Sun, Yujiao; Ding, Aizhong; Zhang, Dan; Zhang, Dayi

    2015-04-01

    Coal tar is one of the most hazardous and concerned organic pollutants and the main hazards are polycyclic aromatic hydrocarbons (PAHs). The indigenous microorganisms in soils are capable to degrade PAHs, with essential roles in biochemical process for PAHs natural attenuation. This study investigated 48 soil samples (from 8 depths of 6 boreholes) in Beijing coking and chemistry plant (China) and revealed the correlation between PAHs contamination, soil enzyme activities and microbial community structure, by 16S rRNA denaturing gradient gel electrophoresis (DGGE). At the site, the key contaminants were identified as naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene and anthracene, and the total PAHs concentration ranged from 0.1 to 923.9 mg/kg dry soil. The total PAHs contamination level was positively correlated (p<0.05) with the bacteria count (0.9×107-14.2×107 CFU/mL), catalase activities (0.554-6.230 mL 0.02 M KMnO4/g•h) and dehydrogenase activities (1.9-30.4 TF μg/g•h soil), showing the significant response of microbial population and degrading functions to the organic contamination in soils. The PAHs contamination stimulated the PAHs degrading microbes and promoted their biochemical roles in situ. The positive relationship between bacteria count and dehydrogenase activities (p<0.05) suggested the dominancy of PAHs degrading bacteria in the microbial community. More interestingly, the microbial community deterioration was uncovered via the decline of microbial biodiversity (richness from 16S rRNA DGGE) against total PAHs concentration (p<0.05). Our research described the spatial profiles of PAHs contamination and soil microbial functions at the PAHs heavily contaminated sites, offering deeper understanding on the roles of indigenous microbial community in natural attenuation process.

  19. PAH contamination in Beijing's topsoil: A unique indicator of the megacity's evolving energy consumption and overall environmental quality.

    PubMed

    Li, Jinguo; Zheng, Yi; Luo, Xiaolin; Lin, Zhongrong; Zhang, Wei; Wang, Xuejun

    2016-01-01

    To improve its air quality, Beijing, the capital of China, has implemented high-cost pollution control measures mainly focused on shifting its energy mix. However, the effectiveness of these measures has long been questioned, especially given the recent problem of severe haze. The main study objectives are to achieve independent, although indirect, information on Beijing's air pollution by measuring the level of polycyclic aromatic hydrocarbon (PAH) contamination in topsoil and to examine how soil contamination reflects energy consumption. Soil sampling data from two years, 2004 and 2013, were used. The key findings are as follows: 1) although the total PAH content in the topsoil did not significantly decrease from 2004 to 2013, the composition changed considerably; 2) as of 2013, vehicle emissions replaced coal combustion as the leading source of soil PAHs, which validates the existing policy measures regarding vehicle purchasing and traffic volume; 3) the regional transport of atmospheric pollutants, as indicated by the contribution of coking sources in 2013, is not negligible; and 4) appropriate policy measures are needed to control the growing practice of burning biomass. Overall, this study demonstrates that the PAH contamination in topsoil represents an informative indicator of Beijing's energy consumption and overall environmental quality. PMID:27633056

  20. Characterization and FATE of PAH-contaminated sediments at the Wyckoff/Eagle Harbor Superfund Site.

    PubMed

    Brenner, Richard C; Magar, Victor S; Ickes, Jennifer A; Abbott, James E; Stout, Scott A; Crecelius, Eric A; Bingler, Linda S

    2002-06-15

    Eagle Harbor, a shallow marine embayment of Bainbridge Island, WA approximately 10 miles west of Seattle, WA), was formerly the site of the Wyckoff wood-treatment facility. The facility used large quantities of creosote in its wood-treating processes from the early 1900s to 1988. Historical creosote seepage into the harbor resulted in substantial accumulation of polycyclic aromatic hydrocarbon (PAH) contamination in the harbor sediments over time. This investigation focused on the distribution and fate of the PAH-contaminated harbor sediments. Analyses of 10 sediment cores using total petroleum hydrocarbon (TPH) fingerprinting, the distribution of 50 PAH analytes, and sediment age dating revealed the contributions of three distinct sources of PAHs to sediment contamination in the harbor during various periods over the past 100 years; namely, creosote, urban runoff, and natural background. Surface sediments (upper 20-30 cm) in the cores closestto the Wyckoff wood-treatment facility and southeast of an existing cap were dominated by urban runoff and weathered creosote; the deeper sediments (> 30 cm) were heavily contaminated with relatively unweathered creosote and some pure-phase creosote. Cores located the furthest from the area of contamination, in the center of the harbor, were dominated by urban runoff, showed no signs of creosote contamination, and had much lower PAH and TPH concentrations than those adjacent to the facility. In the four cores in the center of the Harbor, farthest from the former Wyckoff facility, PAH concentrations increased significantly (p < 0.01) with proximity to the northern shore of the harbor, which is more heavily developed than the southern shore and is where all automobile traffic enters and exits the island through the Bainbridge Island ferry terminal. Deeper portions of these cores were contaminated primarily with natural background PAHs, likely representing preurbanization sediments. Sedimentation rates ranged from 0.54 to 1.10 gm

  1. Using slow-release permanganate candles to remediate PAH-contaminated water.

    PubMed

    Rauscher, Lindy; Sakulthaew, Chainarong; Comfort, Steve

    2012-11-30

    Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO(4)) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2-4 h. Using (14)C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO(2)), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet-dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide proof-of-concept that permanganate candles could potentially provide a low-cost, low-maintenance approach to remediating PAH-contaminated water.

  2. A TOXICITY ASSESSMENT APPROACH TO EVALUATING IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Freshwater and marine sediment toxicity tests were used to measure baseline toxicity of sediment samples collected from New Jersey/New York Harbor (NJ/NY) (non-PAH- contaminated) sediment (ERC). Four freshwater toxicity tests were used: 1) amphipod (Hyalella azteca) mortality and...

  3. A TOXICITY ASSESSMENT APPROACH FOR THE EVALUATION OF IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Freshwater and marine sediment toxicity test were used to measure baseline toxicity of sediment samples collected from New York/New Jersey Harbor (NY/NJH) and East River (ER) (PAH contaminated) sediments and to determine the effectiveness of the developed biotreatment strategies ...

  4. PAH contamination in Beijing’s topsoil: A unique indicator of the megacity’s evolving energy consumption and overall environmental quality

    NASA Astrophysics Data System (ADS)

    Li, Jinguo; Zheng, Yi; Luo, Xiaolin; Lin, Zhongrong; Zhang, Wei; Wang, Xuejun

    2016-09-01

    To improve its air quality, Beijing, the capital of China, has implemented high-cost pollution control measures mainly focused on shifting its energy mix. However, the effectiveness of these measures has long been questioned, especially given the recent problem of severe haze. The main study objectives are to achieve independent, although indirect, information on Beijing’s air pollution by measuring the level of polycyclic aromatic hydrocarbon (PAH) contamination in topsoil and to examine how soil contamination reflects energy consumption. Soil sampling data from two years, 2004 and 2013, were used. The key findings are as follows: 1) although the total PAH content in the topsoil did not significantly decrease from 2004 to 2013, the composition changed considerably; 2) as of 2013, vehicle emissions replaced coal combustion as the leading source of soil PAHs, which validates the existing policy measures regarding vehicle purchasing and traffic volume; 3) the regional transport of atmospheric pollutants, as indicated by the contribution of coking sources in 2013, is not negligible; and 4) appropriate policy measures are needed to control the growing practice of burning biomass. Overall, this study demonstrates that the PAH contamination in topsoil represents an informative indicator of Beijing’s energy consumption and overall environmental quality.

  5. PAH contamination in Beijing’s topsoil: A unique indicator of the megacity’s evolving energy consumption and overall environmental quality

    PubMed Central

    Li, Jinguo; Zheng, Yi; Luo, Xiaolin; Lin, Zhongrong; Zhang, Wei; Wang, Xuejun

    2016-01-01

    To improve its air quality, Beijing, the capital of China, has implemented high-cost pollution control measures mainly focused on shifting its energy mix. However, the effectiveness of these measures has long been questioned, especially given the recent problem of severe haze. The main study objectives are to achieve independent, although indirect, information on Beijing’s air pollution by measuring the level of polycyclic aromatic hydrocarbon (PAH) contamination in topsoil and to examine how soil contamination reflects energy consumption. Soil sampling data from two years, 2004 and 2013, were used. The key findings are as follows: 1) although the total PAH content in the topsoil did not significantly decrease from 2004 to 2013, the composition changed considerably; 2) as of 2013, vehicle emissions replaced coal combustion as the leading source of soil PAHs, which validates the existing policy measures regarding vehicle purchasing and traffic volume; 3) the regional transport of atmospheric pollutants, as indicated by the contribution of coking sources in 2013, is not negligible; and 4) appropriate policy measures are needed to control the growing practice of burning biomass. Overall, this study demonstrates that the PAH contamination in topsoil represents an informative indicator of Beijing’s energy consumption and overall environmental quality. PMID:27633056

  6. Phototoxic evaluation of marine sediments collected from a PAH-contaminated site.

    PubMed

    Boese, B L; Ozretich, R J; Lamberson, J O; Cole, F A; Swartz, R C; Ferraro, S P

    2000-04-01

    The phototoxicity potential of PAH-contaminated field sediment was evaluated and compared to standard sediment toxicity test results. Marine sediments were collected from 30 sites along a presumed PAH sediment pollution gradient in Elliot Bay, WA. Standard 10-day acute and 28-day chronic sediment toxicity tests were conducted with the infaunal amphipods Rhepoxynius abronius and Leptocheirus plumulosus using mortality and the ability to rebury as endpoints. The survivors of these tests were then subjected to 1-h exposures to UV radiation with mortality and reburial again determined. The most highly toxic sediments identified in these experiments were evaluated further for toxicity and phototoxicity by serially diluting them with uncontaminated sediment and repeating the toxicity tests. Standard 10-day toxicity test results indicated that over 70% of the sites sampled in Elliot Bay exhibited measurable toxicity with nine sites being highly toxic to both species of amphipods. Results of standard 28-day chronic sediment toxicity tests were similar. In contrast, almost all of the sites were found to be highly phototoxic. Results indicated that exposure to UV increased toxicity five- to eightfold. This suggests that standard toxicity tests underestimate the potential ecological risk of PAH-contaminated sediments in animals exposed to sunlight. However, only when PAH contamination was between 0.05 and 1.0 toxic units would conducting a phototoxicity evaluation add information to that gained from conducting a standard sediment toxicity test alone.

  7. Comparison of rapid solvent extraction systems for the GC–MS/MS characterization of polycyclic aromatic hydrocarbons in aged, contaminated soil

    PubMed Central

    Haleyur, Nagalakshmi; Shahsavari, Esmaeil; Mansur, Abdulatif A.; Koshlaf, Eman; Morrison, Paul D.; Osborn, A. Mark; Ball, Andrew S.

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are a major class of organic hydrocarbons with high molecular weight that originate from both natural and anthropogenic sources. Sixteen PAHs are included in the U.S Environmental Protection agency list of priority pollutants due to their mutagenic, carcinogenic, toxic and teratogenic properties. In this study, the development and optimization of a simplified and rapid solvent extraction for the characterisation of 16 USEPA priority poly aromatic hydrocarbons (PAHs) in aged contaminated soils was established with subsequent analysis by GC–MS/MS. • Five different extraction solvent systems: dichloromethane: acetone, chloroform: methanol, dichloromethane, acetone: hexane and hexane were assessed in terms of their ability to extract PAHs from aged PAH-contaminated soils. • Highest PAH concentrations were extracted using acetone: hexane and chloroform: methanol. Given the greater toxicity associated with chloroform: methanol, acetone: hexane appears the best choice of solvent extraction system. • This protocol enables efficient extraction of PAHs from aged weathered soils. PMID:27200269

  8. Comparison of rapid solvent extraction systems for the GC-MS/MS characterization of polycyclic aromatic hydrocarbons in aged, contaminated soil.

    PubMed

    Haleyur, Nagalakshmi; Shahsavari, Esmaeil; Mansur, Abdulatif A; Koshlaf, Eman; Morrison, Paul D; Osborn, A Mark; Ball, Andrew S

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are a major class of organic hydrocarbons with high molecular weight that originate from both natural and anthropogenic sources. Sixteen PAHs are included in the U.S Environmental Protection agency list of priority pollutants due to their mutagenic, carcinogenic, toxic and teratogenic properties. In this study, the development and optimization of a simplified and rapid solvent extraction for the characterisation of 16 USEPA priority poly aromatic hydrocarbons (PAHs) in aged contaminated soils was established with subsequent analysis by GC-MS/MS. •Five different extraction solvent systems: dichloromethane: acetone, chloroform: methanol, dichloromethane, acetone: hexane and hexane were assessed in terms of their ability to extract PAHs from aged PAH-contaminated soils.•Highest PAH concentrations were extracted using acetone: hexane and chloroform: methanol. Given the greater toxicity associated with chloroform: methanol, acetone: hexane appears the best choice of solvent extraction system.•This protocol enables efficient extraction of PAHs from aged weathered soils.

  9. Characterization and risk assessment of PAH-contaminated river sediment by using advanced multivariate methods.

    PubMed

    Wang, Yeuh-Bin; Liu, Chen-Wuing; Kao, Yu-Hsuan; Jang, Cheng-Shin

    2015-08-15

    This study applied advanced multivariate methods and risk assessment to evaluate the characteristics of polycyclic aromatic hydrocarbons (PAHs) in the sediment of the severely polluted Erjen River in Taiwan. High-molecular-weight PAHs (HPAHs) dominated in the rainy season. The ecological risk of PAHs in the sediment was low, whereas the total health risk through ingestion and dermal contact was considerably high. The SOM (self-organizing map) analysis clustered the datasets of PAH-contaminated sediment into five groups with similar concentration levels. Factor analysis identified major factors, namely coal combustion, traffic, petrogenic, and petrochemical industry factors, accounting for 88.67% of the variance in the original datasets. The major tributary and the downstream of the river were identified as PAH-contamination hotspots. The PMF (positive matrix factorization) was combined with toxicity assessment to estimate the possible apportionment of sources and the associated toxicity. Spills of petroleum-related products, vehicle exhaust, coal combustion, and exhaust from a petrochemical industry complex constituted respectively 12%, 6%, 74%, and 86% of PAHs in the sediment, but contributed respectively 7%, 15%, 22%, and 56% of toxicity posed by PAHs in the sediment. To improve the sediment quality, best management practices should be adopted to eliminate nonpoint sources of PAHs flushed by storm water into the major tributary and the downstream of the Erjen River. The proposed methodologies and results provide useful information on remediating river PAH-contaminated sediment and may be applicable to other basins with similar properties that are experiencing resembled river environmental issues. PMID:25889545

  10. Review of PAH contamination in food products and their health hazards.

    PubMed

    Bansal, Vasudha; Kim, Ki-Hyun

    2015-11-01

    Public concern over the deleterious effects of polycyclic aromatic hydrocarbons (PAHs) has grown rapidly due to recognition of their toxicity, carcinogenicity, and teratogenicity. The aim of this review is to describe the status of PAH pollution among different food types, the route of dietary intake, measures for its reduction, and legislative approaches to control PAH. To this end, a comprehensive review is outlined to evaluate the status of PAH contamination in many important food categories along with dietary recommendations. Our discussion is also extended to describe preventive measures to reduce PAH in food products to help reduce the risks associated with human intake.

  11. Managing long-term polycyclic aromatic hydrocarbon contaminated soils: a risk-based approach.

    PubMed

    Duan, Luchun; Naidu, Ravi; Thavamani, Palanisami; Meaklim, Jean; Megharaj, Mallavarapu

    2015-06-01

    Polycyclic aromatic hydrocarbons (PAHs) are a family of contaminants that consist of two or more aromatic rings fused together. Soils contaminated with PAHs pose significant risk to human and ecological health. Over the last 50 years, significant research has been directed towards the cleanup of PAH-contaminated soils to background level. However, this achieved only limited success especially with high molecular weight compounds. Notably, during the last 5-10 years, the approach to remediate PAH-contaminated soils has changed considerably. A risk-based prioritization of remediation interventions has become a valuable step in the management of contaminated sites. The hydrophobicity of PAHs underlines that their phase distribution in soil is strongly influenced by factors such as soil properties and ageing of PAHs within the soil. A risk-based approach recognizes that exposure and environmental effects of PAHs are not directly related to the commonly measured total chemical concentration. Thus, a bioavailability-based assessment using a combination of chemical analysis with toxicological assays and nonexhaustive extraction technique would serve as a valuable tool in risk-based approach for remediation of PAH-contaminated soils. In this paper, the fate and availability of PAHs in contaminated soils and their relevance to risk-based management of long-term contaminated soils are reviewed. This review may serve as guidance for the use of site-specific risk-based management methods.

  12. TIE of a PAH-contaminated sediment using reproductive responses and EROD induction in rainbow trout

    SciTech Connect

    Brumley, C.M.; Kraak, G. van der; Munkittrick, K.R.

    1995-12-31

    PAH-contaminated sediments have been shown to cause a range of effects in fish. However, identifying the effective compounds can be time consuming and expensive. A toxicity identification evaluation (TIE) involves the analysis of mixtures by initially separating the mixture into toxic and non-toxic constituents. In this study, sediment was collected from Hamilton Harbor, Lake Ontario, and either extracted wet using methanol (MeOH) and dichloromethane (DCM), or freeze-dried and soxhlet extracted with MeOH and DCM. DCM extracts were solvent exchanged with dimethylsulfoxide (DMSO). Juvenile rainbow trout (Oncorhynchus mykiss) were exposed through the water to wet, freeze-dried, or extracted sediment, or to the MeOH or DMSO extracts for 4 days. Fish were analyzed for hepatic EROD activity, and plasma DMSO extracts, but was unaffected in fish exposed to extracted sediment. Estradiol levels were increased in fish exposed to the wet sediment, but not in fish exposed to the freeze-dried or extracted sediment, nor either of the solvent extracts. The response of testosterone to wet, freeze-dried and extracted sediment was inconsistent. Results indicate that both of the extraction methods efficiently removed from the sediment the compounds responsible for the effects on EROD activity and estradiol levels. However, neither method retained in the solvent extracts the compounds causing the increases in estradiol levels. Work continues to refine the freeze-drying and extraction methods; extracts will then be further fractionated using HPLC to identify the compounds of concern.

  13. Enhancing the intrinsic bioremediation of PAH-contaminated anoxic estuarine sediments with biostimulating agents.

    PubMed

    Bach, Quang-Dung; Kim, Sang-Jin; Choi, Sung-Chan; Oh, Young-Sook

    2005-08-01

    Estuarine sediments are frequently polluted with hydrocarbons from fuel spills and industrial wastes. Polycyclic aromatic hydrocarbons (PAHs) are components of these contaminants that tend to accumulate in the sediment due to their low aqueous solubility, low volatility, and high affinity for particulate matter. The toxic, recalcitrant, mutagenic, and carcinogenic nature of these compounds may require aggressive treatment to remediate polluted sites effectively. In petroleum-contaminated sediments near a petrochemical industry in Gwangyang Bay, Korea, in situ PAH concentrations ranged from 10 to 2,900 microg/kg dry sediment. To enhance the biodegradation rate of PAHs under anaerobic conditions, sediment samples were amended with biostimulating agents alone or in combination: nitrogen and phosphorus in the form of slow-release fertilizer (SRF), lactate, yeast extract (YE), and Tween 80. When added to the sediment individually, all tested agents enhanced the degradation of PAHs, including naphthalene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene. Moreover, the combination of SRF, Tween 80, and lactate increased the PAH degradation rate 1.2-8.2 times above that of untreated sediment (0.01-10 microg PAH/kg dry sediment/day). Our results indicated that in situ contaminant PAHs in anoxic sediment, including high molecular weight PAHs, were degraded biologically and that the addition of stimulators increased the biodegradation potential of the intrinsic microbial populations. Our results will contribute to the development of new strategies for in situ treatment of PAH-contaminated anoxic sediments.

  14. Sources, fate, and toxic hazards of oxygenated polycyclic aromatic hydrocarbons (PAHs) at PAH-contaminated sites.

    PubMed

    Lundstedt, Staffan; White, Paul A; Lemieux, Christine L; Lynes, Krista D; Lambert, Iain B; Oberg, Lars; Haglund, Peter; Tysklind, Mats

    2007-09-01

    In this paper we show that oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are important cocontaminants that should be taken into account during risk assessment and remediation of sites with high levels of PAHs. The presented data, which have been collected both from our own research and the published literature, demonstrate that oxy-PAHs are abundant but neglected contaminants at these sites. The oxy-PAHs show relatively high persistency and because they are formed through transformation of PAHs, their concentrations in the environment may even increase as the sites are remediated by methods that promote PAH degradation. Furthermore, we show that oxy-PAHs are toxic to both humans and the environment, although the toxicity seems to be manifested through other effects than those known to be important for polycyclic aromatic compounds in general, that is, mutagenicity and carcinogenicity. Finally, we present data that support the hypothesis that oxy-PAHs are more mobile in the environment than PAHs, due to their polarity, and thus have a higher tendency to spread from contaminated sites via surface water and groundwater. We believe that oxy-PAHs should be included in monitoring programs at PAH-contaminated sites, even if a number of other toxicologically relevant compounds that may also be present, such as nitro-PAHs and azaarenes, are not monitored. This is because oxy-PAH levels are difficult to predict from the PAH levels, because their environmental behavior differs substantially from that of PAHs, and oxy-PAHs may be formed as PAHs are degraded.

  15. Application of Equilibrium Partitioning Theory to Soil PAH Contamination (External Review Draft)

    EPA Science Inventory

    In March 2004, ORD's Ecological Risk Assessment Support Center (ERASC) received a request from the Ecological Risk Assessment Forum (ERAF) to provide insight into the issue of whether equilibrium partitioning (EqP) techniques can be used to predict the toxicity of polycyclic arom...

  16. Diversity and distribution of 16S rRNA and phenol monooxygenase genes in the rhizosphere and endophytic bacteria isolated from PAH-contaminated sites

    PubMed Central

    Peng, Anping; Liu, Juan; Ling, Wanting; Chen, Zeyou; Gao, Yanzheng

    2015-01-01

    This is the first investigation of the diversity and distribution of 16S rRNA and phenol monooxygenase (PHE) genes in endophytic and rhizosphere bacteria of plants at sites contaminated with different levels of PAHs. Ten PAHs at concentrations from 34.22 to 55.29 and 45.79 to 97.81 mg·kg−1 were measured in rhizosphere soils of Alopecurus aequalis Sobol and Oxalis corniculata L., respectively. The diversity of 16S rRNA and PHE genes in rhizosphere soils or plants changed with varying PAH pollution levels, as shown based on PCR-DGGE data. Generally, higher Shannon-Weiner indexes were found in mild or moderate contaminated areas. A total of 82 different bacterial 16S rRNA gene sequences belonging to five phyla; namely, Acfinobacteria, Proteobacteria, Chloroflexi, Cyanophyta, and Bacteroidetes, were obtained from rhizosphere soils. For the 57 identified PHE gene sequences, 18 were excised from rhizosphere bacteria and 39 from endophytic bacteria. The copy numbers of 16S rRNA and PHE genes in rhizosphere and endophytic bacteria varied from 3.83 × 103 to 2.28 × 106 and 4.17 × 102 to 1.99 × 105, respectively. The copy numbers of PHE genes in rhizosphere bacteria were significantly higher than in endophytic bacteria. Results increase our understanding of the diversity of rhizosphere and endophytic bacteria from plants grown in PAH-contaminated sites. PMID:26184609

  17. Diversity and distribution of 16S rRNA and phenol monooxygenase genes in the rhizosphere and endophytic bacteria isolated from PAH-contaminated sites.

    PubMed

    Peng, Anping; Liu, Juan; Ling, Wanting; Chen, Zeyou; Gao, Yanzheng

    2015-07-17

    This is the first investigation of the diversity and distribution of 16S rRNA and phenol monooxygenase (PHE) genes in endophytic and rhizosphere bacteria of plants at sites contaminated with different levels of PAHs. Ten PAHs at concentrations from 34.22 to 55.29 and 45.79 to 97.81 mg·kg(-1) were measured in rhizosphere soils of Alopecurus aequalis Sobol and Oxalis corniculata L., respectively. The diversity of 16S rRNA and PHE genes in rhizosphere soils or plants changed with varying PAH pollution levels, as shown based on PCR-DGGE data. Generally, higher Shannon-Weiner indexes were found in mild or moderate contaminated areas. A total of 82 different bacterial 16S rRNA gene sequences belonging to five phyla; namely, Acfinobacteria, Proteobacteria, Chloroflexi, Cyanophyta, and Bacteroidetes, were obtained from rhizosphere soils. For the 57 identified PHE gene sequences, 18 were excised from rhizosphere bacteria and 39 from endophytic bacteria. The copy numbers of 16S rRNA and PHE genes in rhizosphere and endophytic bacteria varied from 3.83 × 10(3) to 2.28 × 10(6) and 4.17 × 10(2) to 1.99 × 10(5), respectively. The copy numbers of PHE genes in rhizosphere bacteria were significantly higher than in endophytic bacteria. Results increase our understanding of the diversity of rhizosphere and endophytic bacteria from plants grown in PAH-contaminated sites.

  18. Diversity and distribution of 16S rRNA and phenol monooxygenase genes in the rhizosphere and endophytic bacteria isolated from PAH-contaminated sites

    NASA Astrophysics Data System (ADS)

    Peng, Anping; Liu, Juan; Ling, Wanting; Chen, Zeyou; Gao, Yanzheng

    2015-07-01

    This is the first investigation of the diversity and distribution of 16S rRNA and phenol monooxygenase (PHE) genes in endophytic and rhizosphere bacteria of plants at sites contaminated with different levels of PAHs. Ten PAHs at concentrations from 34.22 to 55.29 and 45.79 to 97.81 mg·kg-1 were measured in rhizosphere soils of Alopecurus aequalis Sobol and Oxalis corniculata L., respectively. The diversity of 16S rRNA and PHE genes in rhizosphere soils or plants changed with varying PAH pollution levels, as shown based on PCR-DGGE data. Generally, higher Shannon-Weiner indexes were found in mild or moderate contaminated areas. A total of 82 different bacterial 16S rRNA gene sequences belonging to five phyla; namely, Acfinobacteria, Proteobacteria, Chloroflexi, Cyanophyta, and Bacteroidetes, were obtained from rhizosphere soils. For the 57 identified PHE gene sequences, 18 were excised from rhizosphere bacteria and 39 from endophytic bacteria. The copy numbers of 16S rRNA and PHE genes in rhizosphere and endophytic bacteria varied from 3.83 × 103 to 2.28 × 106 and 4.17 × 102 to 1.99 × 105, respectively. The copy numbers of PHE genes in rhizosphere bacteria were significantly higher than in endophytic bacteria. Results increase our understanding of the diversity of rhizosphere and endophytic bacteria from plants grown in PAH-contaminated sites.

  19. Bioremediation of a PAH-contaminated gasworks site with the Ebiox vacuum heap system

    SciTech Connect

    Eiermann, D.R.; Bolliger, R.

    1995-12-31

    A former gasworks site in the industrial city of Winterthur, Switzerland, was extremely contaminated with polycyclic aromatic hydrocarbons (PAHs); benzene, toluene, ethylbenzene, and xylenes (BTEX); phenols; ammonia; and mineral oils. Three vacuum heaps, with a total volume of 10,500 m{sup 3} of contaminated soil, were bioremediated during 1993/94. Separating excavated soil material into different soil qualities was of particular importance because of the pathway definition of the specific soil material. Excavation of contamination took longer than 10 months, delivering continuously different contaminated soil-type material for bioremediation. Conditioning and subsequent biostimulation of the large soil volumes were the prerequisites for most advanced milieu optimization. The degradation results demonstrated the potential for successful application of bioremediation on former industrial sites. PAH-concentration reductions ranged from 75 to 83% for the soil values and from 87 to 98% for the elution values. Soil and elution target qualities were met within 6 to 12 months, depending on initial PAH-concentration and soil structure. The achieved target quality for the bioremediated soil allowed subsequent reuse as high-value backfill material for the ongoing building project.

  20. Fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp in Hong Kong following an oil spill.

    PubMed

    Ke, L; Wong, Teresa W Y; Wong, Y S; Tam, Nora F Y

    2002-01-01

    The fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp (Yi O) in Hong Kong after an oil spill accident was investigated. The concentrations and profiles of PAHs in surface sediments collected from five quadrats (each of 10 m x 10 m) covering different degrees of oil contamination and the most contaminated mangrove leaves were examined in December 2000 (30 days after the accident) and March 2001 (126 days later). The concentrations of total PAHs in surface sediments ranged from 138 to 2,135 ng g(-1), and PAHs concentrations decreased with time. In the most contaminated sediments, total PAHs dropped from 2,135 (30 days) to 1,196 ng g(-1) (120 days), and the decrease was smaller in less contaminated sediments. The percentage reduction in sediment PAHs over three months (44%) was less significant than that in contaminated leaves (85%), indicating PAH in or on leaves disappeared more rapidly. The PAH profiles were very similar in sediments collected from quadrats Q1 and Q2 with benzo[a]anthracene and pyrene being the most abundant PAH compounds, but were different in the other three quadrats. The proportion of the light molecular weight PAHs to total PAHs increased after three months, especially phenanthrene. Results suggest that physical and photo-chemical weathering (tidal washing and photo-oxidation) of crude oil in surface sediments and on plant leaves were important processes in the first few months after the oil spill. The PAH contamination in Yi O swamp came from both petrogenic and pyrolytic sources. The petrogenic characteristic in the most contaminated sediment was confirmed with high values of phenanthrene to anthracene ratio (>10) and low values of fluoranthene to pyrene ratio (0.3-0.4).

  1. Interrelationship of Pyrogenic Polycyclic Aromatic Hydrocarbon (PAH) Contamination in Different Environmental Media.

    PubMed

    Kim, Seung-Kyu; Lee, Dong Soo; Shim, Won Joon; Yim, Un Hyuk; Shin, Yong-Seung

    2009-01-01

    Interrelationships between pyrogenic polycyclic aromatic hydrocarbons (PAHs) were assessed in air, soil, water, sediment, and tree leaves by using multi-media monitoring data. Concurrent concentration measurements were taken bimonthly for a year for the multi-media at urban and suburban sites. PAH level correlations between air and other media were observed at the urban site but were less clear at the suburban site. Considering a closer PAHs distribution/fate characteristics to soil than suspended solids, contamination in sediment seemed to be governed primarily by that in soil. The partitioning of PAHs in waters could be better accounted for by sorption onto black carbon and dissolved organic carbon. PMID:22303141

  2. A TOXICITY ASSESSMENT APPROACH FOR EVALUATION OF IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Polycyclic aromatic hydrocarbons (PAHs) represent a group of organic contaminants known for their prevalence and persistence in petroleum-impacted environment such as groundwater, soils and sediments. Many high molecular weight PAHs are suspected carcinogens and the existence of...

  3. Chronic Polyaromatic Hydrocarbon (PAH) Contamination Is a Marginal Driver for Community Diversity and Prokaryotic Predicted Functioning in Coastal Sediments.

    PubMed

    Jeanbille, Mathilde; Gury, Jérôme; Duran, Robert; Tronczynski, Jacek; Ghiglione, Jean-François; Agogué, Hélène; Saïd, Olfa Ben; Taïb, Najwa; Debroas, Didier; Garnier, Cédric; Auguet, Jean-Christophe

    2016-01-01

    Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs) in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments, the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using high-throughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales.

  4. Chronic Polyaromatic Hydrocarbon (PAH) Contamination Is a Marginal Driver for Community Diversity and Prokaryotic Predicted Functioning in Coastal Sediments.

    PubMed

    Jeanbille, Mathilde; Gury, Jérôme; Duran, Robert; Tronczynski, Jacek; Ghiglione, Jean-François; Agogué, Hélène; Saïd, Olfa Ben; Taïb, Najwa; Debroas, Didier; Garnier, Cédric; Auguet, Jean-Christophe

    2016-01-01

    Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs) in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments, the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using high-throughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales. PMID:27594854

  5. Chronic Polyaromatic Hydrocarbon (PAH) Contamination Is a Marginal Driver for Community Diversity and Prokaryotic Predicted Functioning in Coastal Sediments

    PubMed Central

    Jeanbille, Mathilde; Gury, Jérôme; Duran, Robert; Tronczynski, Jacek; Ghiglione, Jean-François; Agogué, Hélène; Saïd, Olfa Ben; Taïb, Najwa; Debroas, Didier; Garnier, Cédric; Auguet, Jean-Christophe

    2016-01-01

    Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs) in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments, the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using high-throughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales.

  6. Chronic Polyaromatic Hydrocarbon (PAH) Contamination Is a Marginal Driver for Community Diversity and Prokaryotic Predicted Functioning in Coastal Sediments

    PubMed Central

    Jeanbille, Mathilde; Gury, Jérôme; Duran, Robert; Tronczynski, Jacek; Ghiglione, Jean-François; Agogué, Hélène; Saïd, Olfa Ben; Taïb, Najwa; Debroas, Didier; Garnier, Cédric; Auguet, Jean-Christophe

    2016-01-01

    Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs) in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments, the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using high-throughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales. PMID:27594854

  7. Monitoring PAH contamination in the field (South west Iberian Peninsula): biomonitoring using fluorescence spectrophotometry and physiological assessments in the shore crab Carcinus maenas (L.) (Crustacea: Decapoda).

    PubMed

    Dissanayake, Awantha; Bamber, Shaw D

    2010-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of the marine environment, arising predominantly from petrochemical contamination and pyrogenic sources. A biomarker of PAH exposure was employed in a field study (South West, Spain) in both captured (indigenous) and deployed (caged) shore crabs (Carcinus maenas) in the chronic PAH-exposed Bays of Algeciras and Gibraltar (from associated harbour and boating activity) compared to a relatively 'clean' site (Cadiz). Metabolite fluorescence was attributed to the following key priority PAH groups; naphthalenes (NAPs), pyrenes (PYRs) and benzo[a]pyrenes (BAPs). Temporal variability was assessed using deployed populations over an eight week period. Petrogenic and pyrogenic PAH contamination (as an indicator of the PAH type) was demonstrated using a ratio between FF(BAP + PYR)/FF(NAP). Physiological assessments from deployed crabs demonstrated both physiological and cellular alterations as shown by reduced heart rates (at rest) and increased cellular stress in crabs from the PAH contaminated sites.

  8. Degradation and formation of polycyclic aromatic compounds during bioslurry treatment of an aged gasworks soil.

    PubMed

    Lundstedt, Staffan; Haglund, Peter; Oberg, Lars

    2003-07-01

    The goals of this study were to investigate the relative degradation rates of polycyclic aromatic compounds (PACs) in contaminated soil, and to assess whether persistent oxidation products are formed during their degradation. Samples were taken on five occasions during a pilot-scale bioslurry treatment of soil from a former gasworks site. More than 100 PACs were identified in the soil, including unsubstituted polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkyl-PAHs), heterocyclic PACs, and oxygenated PAHs (oxy-PAHs), such as ketones, quinones, and coumarins. During the treatment, the low molecular weight PAHs and heterocyclics were degraded faster than the high molecular weight compounds. The unsubstituted PAHs also appear to have degraded more quickly than the corresponding alkyl-PAHs and nitrogen-containing heterocyclics. No new oxidation products that were not present in the untreated soil were identified after the soil treatment. However, oxy-PAHs that were present in the untreated soil were generally degraded more slowly than the parent compounds, suggesting that they were formed during the treatment or that they are more persistent. Two oxidation products, 1-acenaphthenone and 4-oxapyrene-5-one, were found at significantly higher concentrations at the end of the study. Because oxy-PAHs can be acutely toxic, mutagenic, or carcinogenic, we suggest that this group of compounds should also be monitored during the treatment of PAH-contaminated soil. PMID:12836964

  9. Potential of Endophytic Bacterium Paenibacillus sp. PHE-3 Isolated from Plantago asiatica L. for Reduction of PAH Contamination in Plant Tissues.

    PubMed

    Zhu, Xuezhu; Jin, Li; Sun, Kai; Li, Shuang; Ling, Wanting; Li, Xuelin

    2016-01-01

    Endophytes are ubiquitous in plants, and they may have a natural capacity to biodegrade polycyclic aromatic hydrocarbons (PAHs). In our study, a phenanthrene-degrading endophytic Paenibacillus sp. PHE-3 was isolated from P. asiatica L. grown in a PAH-contaminated site. The effects of environmental variables on phenanthrene biodegradation by strain PHE-3 were studied, and the ability of strain PHE-3 to use high molecular weight PAH (HMW-PAH) as a sole carbon source was also evaluated. Our results indicated that pH value of 4.0-8.0, temperature of 30 °C-42 °C, initial phenanthrene concentration less than 100 mg·L(-1), and some additional nutrients are favorable for the biodegradation of phenanthrene by strain PHE-3. The maximum biodegradation efficiency of phenanthrene was achieved at 99.9% after 84 h cultivation with additional glutamate. Moreover, the phenanthrene biodegradation by strain PHE-3 was positively correlated with the catechol 2,3-dioxygenase activity (ρ = 0.981, p < 0.05), suggesting that strain PHE-3 had the capability of degrading HMW-PAHs. In the presence of other 2-, 3-ringed PAHs, strain PHE-3 effectively degraded HMW-PAHs through co-metabolism. The results of this study are beneficial in that the re-colonization potential and PAH degradation performance of endophytic Paenibacillus sp. PHE-3 may be applied towards reducing PAH contamination in plants. PMID:27347988

  10. Potential of Endophytic Bacterium Paenibacillus sp. PHE-3 Isolated from Plantago asiatica L. for Reduction of PAH Contamination in Plant Tissues

    PubMed Central

    Zhu, Xuezhu; Jin, Li; Sun, Kai; Li, Shuang; Ling, Wanting; Li, Xuelin

    2016-01-01

    Endophytes are ubiquitous in plants, and they may have a natural capacity to biodegrade polycyclic aromatic hydrocarbons (PAHs). In our study, a phenanthrene-degrading endophytic Paenibacillus sp. PHE-3 was isolated from P. asiatica L. grown in a PAH-contaminated site. The effects of environmental variables on phenanthrene biodegradation by strain PHE-3 were studied, and the ability of strain PHE-3 to use high molecular weight PAH (HMW-PAH) as a sole carbon source was also evaluated. Our results indicated that pH value of 4.0–8.0, temperature of 30 °C–42 °C, initial phenanthrene concentration less than 100 mg·L−1, and some additional nutrients are favorable for the biodegradation of phenanthrene by strain PHE-3. The maximum biodegradation efficiency of phenanthrene was achieved at 99.9% after 84 h cultivation with additional glutamate. Moreover, the phenanthrene biodegradation by strain PHE-3 was positively correlated with the catechol 2,3-dioxygenase activity (ρ = 0.981, p < 0.05), suggesting that strain PHE-3 had the capability of degrading HMW-PAHs. In the presence of other 2-, 3-ringed PAHs, strain PHE-3 effectively degraded HMW-PAHs through co-metabolism. The results of this study are beneficial in that the re-colonization potential and PAH degradation performance of endophytic Paenibacillus sp. PHE-3 may be applied towards reducing PAH contamination in plants. PMID:27347988

  11. Transformation of PAHs during ethanol-Fenton treatment of an aged gasworks' soil.

    PubMed

    Lundstedt, Staffan; Persson, Ylva; Oberg, Lars

    2006-11-01

    PAH-contaminated soil from a former gasworks site was treated with Fenton's reagent in a number of lab-scale slurry reactors. The degradation result obtained by traditional Fenton oxidation and Fenton oxidation preceded by ethanol treatment were compared. The ethanol pre-treatment enhanced the depletion of all PAHs in the soil by facilitating their desorption from the soil matrix. However, some PAHs, especially anthracene, benzo[a]pyrene and perylene, were more extensively depleted than other PAHs with fewer or equal numbers of fused rings, indicating that the hydroxyl radicals react faster with these PAHs than with other kinds. The ethanol present in the slurry also appeared to influence the relative reactivity of the PAHs. Furthermore, the enhanced oxidation that occurred in the ethanol pre-treated soil resulted in the accumulation of oxidation products. For example, 1-indanone, anthracene-9,10-dione, 1-methylanthracenedione, 2-methylanthracenedione, 1,8-naphthalic anhydride, benz[a]anthracene-7,12-dione and two compounds tentatively identified as hydroxy-9-fluorenones were found at higher concentrations after the treatment than before it. The accumulation was most evident for the quinones, and in many cases it could be attributed to extensive oxidation of their parent PAHs, although the total oxidation efficiency in this study was relatively poor. PMID:16735053

  12. Aged refinery hydrocarbon biodegradation in soil

    SciTech Connect

    Drake, E.N.; Stokley, K.E.; Calcavecchio, P.

    1995-12-31

    Aged hydrocarbon biodegradation was investigated as a potential cleanup technology for refinery soil. Well-mixed field soil was amended with water and nutrients and tilled weekly for one year in laboratory mesocosms to stimulate biodegradation. Freon infrared analysis of total petroleum hydrocarbons (TPH), and gas chromatography/mass spectrometry (GC/MS) analysis of polynuclear aromatic hydrocarbons (PAHs) and triterpane biomarkers were used to determine the extent of biodegradation. Significant reductions in TPH (up to 68%) and methylene chloride extractable material (up to 55%) were observed. The combined trimethylated phenanthrene/anthracenes (C3P/A) were even more highly depleted than TPH. Nutrient amendment increased TPH, methylene chloride, and C3P/A removal, but not biomarker concentrations. Significant reduction of two to five ring PAHs occurred. Expected depletion patterns for PAHs were observed except in the case of naphthalene and derivatives, phenanthrene/anthracene and derivatives, and chrysene. A possible explanation is that the more readily degradable PAHs were already highly biodegraded before the study and the remaining portions were less available for biodegradation. These results are consistent with reports on the effects of aging on PAH biodegradation in soil. Biodegradation was influenced by PAH structure and molecular weight.

  13. Coupling extraction-flotation with surfactant and electrochemical degradation for the treatment of PAH contaminated hazardous wastes.

    PubMed

    Tran, Lan-Huong; Drogui, Patrick; Mercier, Guy; Blais, Jean-François

    2009-10-30

    The performance of a two-stage process combining extraction of polycyclic aromatic hydrocarbons (PAHs) with an amphoteric surfactant (CAS) followed by electro-oxidation of PAH-foam concentrate was studied for the decontamination of aluminum industry wastes (AIW) and polluted soils. The PAH suspensions extracted from AIW and soils were treated in a 2L-parallelepipedic electrolytic cell containing Ti/RuO2 anodes and stainless steel cathodes. Current densities varying from 4.6 to 18.5 mA cm(-2) have been tested with and without addition of a supporting electrolyte (6.25 to 50 kg Na2SO4 t(-1) of dry waste). The best performance for PAH degradation was obtained while the electrolytic cell was operated during 90 min at a current density of 9.2 mA cm(-2), with a total solids concentration of 2.0%, and in presence 12.5 kg Na(2)SO(4)t(-1). The application of the process on AIW (initial PAH content: 3424 mg kg(-1)) allowed extracting 42% of PAH, whereas 50% of PAH was electrochemically degraded in the resulting foam suspensions. By comparison, 44% to 60% of PAH was extracted from polluted soils (initial PAH content: 1758 to 4160 mg kg(-1)) and 21% to 55% of PAH was oxidized in the foam suspensions. The electrochemical treatment cost (including only electrolyte and energy consumption) recorded in the best experimental conditions varied from 99 to 188 USD $ t(-1) of soils or AIW treated.

  14. A comprehensive study of the impact of polycyclic aromatic hydrocarbons (PAHs) contamination on salt marsh plants Spartina alterniflora: implication for plant-microbe interactions in phytoremediation.

    PubMed

    Hong, Youwei; Liao, Dan; Chen, Jinsheng; Khan, Sardar; Su, Jianqiang; Li, Hu

    2015-05-01

    These pot experiments aimed to investigate the effects of polycyclic aromatic hydrocarbons (PAHs) on plant uptake, rhizophere, endophytic bacteria, and phytoremediation potentials of contaminated sediments. Salt marsh plant Spartina alterniflora was selected and cultivated in phenanthrene (PHE)- and pyrene (PYR)-contaminated sediments (for 70 days). The results indicated that the amount of PHE removed from the sediments ranged from 13 to 36 %, while PYR ranged from 11 to 30 %. In rhizophere sediment, dehydrogenase activities were significantly (P < 0.05) enhanced by higher concentration of PHE treatments, while polyphenol oxidase activities were prohibited more than 10 % in non-rhizophere sediment. Compared with the control, PHE treatments had also significantly (P < 0.05) lower total microbial biomass; especially for gram-negative bacteria, this decrease was more than 24 %. However, the PYR treatments had little effect on the dehydrogenase, polyphenol oxidase, and total phospholipid fatty acid analysis (PLFA) biomass. The greatest abundance of PAH-ring hydroxylating dioxygenases isolated from gram-negative bacteria (PAH-RHDα-GN) of rhizoplane and endophyte in roots were found at high concentration of PHE treatments and increased by more than 100- and 3-fold, respectively. These results suggested that PAH pollution would result in the comprehensive effect on S. alterniflora, whose endophytic bacteria might play important roles in the phytoremediation potential of PAH-contaminated sediments.

  15. Influence of aging on copper bioavailability in soils.

    PubMed

    Lock, Koen; Janssen, Colin R

    2003-05-01

    Because of long-term chemical processes, metal bioavailability in field soils decreases with time. Metal toxicity may, therefore, be overestimated if toxicity data with freshly spiked soils are used to derive soil quality criteria, a current practice. In the present study, effects of the long-term processes, called aging, on copper partitioning and ecotoxicity are investigated. Twenty-five field soils contaminated by copper runoff from bronze statues and 25 uncontaminated control soils sampled at 5-m distance from these statues were collected in Flanders (Belgium). The soils were selected so that parameters affecting copper bioavailability (pH, cation-exchange capacity, organic matter content, etc.) varied considerably. To assess the effect of aging on copper toxicity, control soils were spiked at total copper concentrations comparable to those of historically contaminated soils. Pore-water copper concentrations and 0.01 M CaCl2-extracted copper concentrations were significantly higher in freshly spiked soils compared to contaminated field soils. However, this could be a pH effect, because pH decreased after spiking. Acute toxicity to Enchytraeus albidus (14 d) as well as chronic toxicity to Folsomia candida (28-d reproduction) and Trifolium pratense (14-d growth) indicated a dose-response relationship between copper toxicity and pore-water copper concentration or the CaCl2-extracted copper fraction.

  16. Mean age distribution of inorganic soil-nitrogen

    NASA Astrophysics Data System (ADS)

    Woo, Dong K.; Kumar, Praveen

    2016-07-01

    Excess reactive nitrogen in soils of intensively managed landscapes causes adverse environmental impact, and continues to remain a global concern. Many novel strategies have been developed to provide better management practices and, yet, the problem remains unresolved. The objective of this study is to develop a model to characterize the "age" of inorganic soil-nitrogen (nitrate, and ammonia/ammonium). We use the general theory of age, which provides an assessment of the time elapsed since inorganic nitrogen has been introduced into the soil system. We analyze a corn-corn-soybean rotation, common in the Midwest United States, as an example application. We observe two counter-intuitive results: (1) the mean nitrogen age in the topsoil layer is relatively high; and (2) mean nitrogen age is lower under soybean cultivation compared to corn although no fertilizer is applied for soybean cultivation. The first result can be explained by cation-exchange of ammonium that retards the leaching of nitrogen, resulting in an increase in the mean nitrogen age near the soil surface. The second result arises because the soybean utilizes the nitrogen fertilizer left from the previous year, thereby removing the older nitrogen and reducing mean nitrogen age. Estimating the mean nitrogen age can thus serve as an important tool to disentangle complex nitrogen dynamics by providing a nuanced characterization of the time scales of soil-nitrogen transformation and transport processes.

  17. Analytical characterization of contaminated soils from former manufactured gas plants

    SciTech Connect

    Haeseler, F. |; Blanchet, D.; Vandecasteele, J.P.; Druelle, V.; Werner, P. |

    1999-03-15

    Detailed analytical characterization of the organic matter (OM) of aged polluted soils from five former manufactured gas plants (MGP) and of two coal tars was completed. It was aimed at obtaining information relevant to the physicochemical state of the polycyclic aromatic hydrocarbon (PAH) pollutants and to their in-situ evolution in time. Overall characterization of total OM (essentially polluting OM) was carried out directly on soil samples with or without prior extraction with solvent. It involved a technique of pyrolysis/oxidation coupled to flame ionization/thermal conductivity detection. Extracts in solvent were fractionated by liquid chromatography into saturated hydrocarbons, PAH, and resins, the first two fractions being further characterized by gas chromatography and mass spectrometry. The compositions of OM of soils were found to be very similar. A total of 28% of organic carbon, including all PAH, was extractable by solvent. The compositions of coal tars were qualitatively similar to those of OM of MGP soils but with a higher proportion (48%) of total extractable OM and of PAH, in particular lower PAH. Contamination of MGP soils appeared essentially as coal tar having undergone natural attenuation. The constant association of PAH with heavy OM in MGP soils is important with respect to the mobility and bioaccessibility of these pollutants.

  18. Earthworm metabolomic responses after exposure to aged PCB contaminated soils.

    PubMed

    Whitfield Åslund, Melissa; Simpson, Myrna J; Simpson, André J; Zeeb, Barbara A; Rutter, Allison

    2012-10-01

    (1)H NMR metabolomics was used to measure earthworm sub-lethal responses to polychlorinated biphenyls (PCBs) in historically contaminated (>30 years) soils (91-280 mg/kg Aroclor 1254/1260) after two and 14 days of exposure. Although our previous research detected a distinct earthworm metabolic response to PCBs in freshly spiked soil at lower concentrations (0.5-25 mg/kg Aroclor 1254), the results of this study suggest only weak or non-significant relationships between earthworm metabolic profiles and soil PCB concentrations. This concurs with the expectation that decades of contaminant aging have likely decreased PCB bioavailability and toxicity in the field. Instead of being influenced by soil contaminant concentration, earthworm metabolic profiles were more closely correlated to soil properties such as total soil carbon and soil inorganic carbon. Overall, these results suggested that (1)H NMR metabolomics may be capable of detecting both site specific responses and decreased contaminant bioavailability to earthworms after only two days of exposure, whereas traditional toxicity tests require much more time (e.g. 14 days for acute toxicity and >50 days for reproduction tests). Therefore, there is significant opportunity to develop earthworm metabolomics as a sensitive tool for rapid assessment of the toxicity associated with contaminated field soils.

  19. Microbial bioavailability of pyrene in three laboratory-contaminated soils under aerobic and anaerobic conditions.

    PubMed

    Pravecek, Tasha L; Christman, Russell F; Pfaender, Frederic K

    2006-06-30

    Changes in bioavailability of pyrene in three uncontaminated soils were examined under aerobic and anaerobic conditions. Three soils were aerobically aged with pyrene and [(14)C]pyrene for 63 days, then incubated with water, nitrate, or sulfate under aerobic or anaerobic conditions for one year. Under aerobic conditions, microorganisms in two soils mineralized 58-82% of the added [(14)C]pyrene. The two soils amended with nitrate were seen to have enhanced aerobic mineralization rates. In one of these soils, non-extractable pyrene was seen to decrease over the course of the study due to desorption and mineralization, nitrate amendment enhanced this effect. Under anaerobic conditions, generated with a N(2):CO(2)(g) headspace, two soils with nitrate or sulfate amendment showed an increase in extractable [(14)C]pyrene at 365 days relative to inhibited controls, presumably due to microbially mediated oxidation-reduction potential and pH alteration of the soil environment. These observations in different soils incubated under aerobic and anaerobic conditions have important implications relative to the impact of microbial electron acceptors on bioavailability and transport of non-polar organic compounds in the environment suggesting that, given enough time, under the appropriate environmental conditions, non-extractable material becomes bioavailable. This information should be considered when assessing site specific exposure risks at PAH contaminated locations. PMID:16574273

  20. Magnetic Properties of Different-Aged Chernozemic Soils

    NASA Astrophysics Data System (ADS)

    Fattakhova, Leysan; Shinkarev, Alexandr; Kosareva, Lina; Nourgaliev, Danis; Shinkarev, Aleksey; Kondrashina, Yuliya

    2016-04-01

    We investigated the magnetic properties and degree of mineral weathering in profiles of different-aged chernozemic soils derived from a uniform parent material. In this work, layer samples of virgin leached chernozem and chernozemic soils formed on the mound of archaeological earthy monument were used. The characterization of the magnetic properties was carried out on the data of the magnetometry and differential thermomagnetic analysis. The evaluation of the weathering degree was carried out on a loss on ignition, cation exchange capacity and X-ray phase analysis on the data of the original soil samples and samples of the heavy fraction of minerals. It was found that the magnetic susceptibility enhancement in humus profiles of newly formed chernozemic soils lagged significantly behind the organic matter content enhancement. This phenomenon is associated with differences in kinetic parameters of humus formation and structural and compositional transformation of the parent material. It is not enough time of 800-900 years to form a relatively "mature" magnetic profile. These findings are well consistent with the chemical kinetic model (Boyle et al., 2010) linking the formation of the soils magnetic susceptibility with the weathering of primary Fe silicate minerals. Different-aged chernozemic soils are at the first stage of formation of a magnetic profile when it is occur an active production of secondary ferrimagnetic minerals from Fe2+ released by primary minerals.

  1. Fate and lability of silver in soils: effect of ageing.

    PubMed

    Settimio, Lara; McLaughlin, Mike J; Kirby, Jason K; Langdon, Kate A; Lombi, Enzo; Donner, Erica; Scheckel, Kirk G

    2014-08-01

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the (110m)Ag radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectroscopy. After two weeks of ageing the E-values for Ag decreased by 20-90% with a further decrease of 10-40% after six months. The overall decrease in labile Ag for all soils after the 6 month ageing period was 50-100%. The ageing was more rapid and pronounced in the alkaline soils. XANES results for Ag in soils indicated that for the majority of soils the added Ag(+) was reduced to metallic Ag over time, and associations with Fe-oxohydroxides and reduced S groups in organic matter also decreased Ag lability. Strong positive correlations were found between metallic Ag and non-labile Ag and between organic carbon and Ag bonded with S species.

  2. Degradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils by Fenton's reagent: a multivariate evaluation of the importance of soil characteristics and PAH properties.

    PubMed

    Jonsson, Sofia; Persson, Ylva; Frankki, Sofia; van Bavel, Bert; Lundstedt, Staffan; Haglund, Peter; Tysklind, Mats

    2007-10-01

    In this study, we investigated how the chemical degradability of polycyclic aromatic hydrocarbons (PAHs) in aged soil samples from various contaminated sites is influenced by soil characteristics and by PAH physico-chemical properties. The results were evaluated using the multivariate statistical tool, partial least squares projections to latent structures (PLS). The PAH-contaminated soil samples were characterised (by pH, conductivity, organic matter content, oxide content, particle size, specific surface area, and the time elapsed since the contamination events, i.e. age), and subjected to relatively mild, slurry-phase Fenton's reaction conditions. In general, low molecular weight PAHs were degraded to a greater extent than large, highly hydrophobic variants. Anthracene, benzo(a)pyrene, and pyrene were more susceptible to degradation than other, structurally similar, PAHs; an effect attributed to the known susceptibility of these compounds to reactions with hydroxyl radicals. The presence of organic matter and the specific surface area of the soil were clearly negatively correlated with the degradation of bi- and tri-cyclic PAHs, whereas the amount of degraded organic matter correlated positively with the degradation of PAHs with five or six fused rings. This was explained by enhanced availability of the larger PAHs, which were released from the organic matter as it degraded. Our study shows that sorption of PAHs is influenced by a combination of soil characteristics and physico-chemical properties of individual PAHs. Multivariate statistical tools have great potential for assessing the relative importance of these parameters.

  3. Effect of Soil Aging on the Phytoremediation Potential of Zea mays in Chromium and Benzo[a]Pyrene Contaminated Soils.

    PubMed

    Chigbo, Chibuike

    2015-06-01

    This study compared the phytoremediation potential of Zea mays in soil either aged or freshly amended with chromium (Cr) and benzo[a]pyrene (B[a]P). Z. mays showed increased shoot biomass in aged soils than in freshly spiked soils. The shoot biomass in contaminated soils increased by over 50% in aged soil when compared to freshly amended soils, and over 29% more Cr was accumulated in the shoot of Z. mays in aged soil than in freshly amended soil. Planting Z. mays in aged soil helped in the dissipation of more than 31% B[a]P than in freshly spiked soil, but in the absence of plants, there seemed to be no difference between the dissipation rates of B[a]P in freshly and aged co-contaminated soil. Z. mays seemed to enhance the simultaneous removal of Cr and B[a]P in aged soil than in freshly spiked soil and hence can be a good plant choice for phytoremediation of co-contaminated soils.

  4. Correlation between biological and physical availabilities of phenanthrene in soils and soil humin in aging experiments

    SciTech Connect

    White, J.C.; Hunter, M.; Nam, K.; Pignatello, J.J.; Alexander, M.

    1999-08-01

    The bioavailability of an organic compound in a soil or sediment commonly declines with the soil-chemical contact time (aging). A series of parallel desorption and bioavailability experiments was carried out on phenanthrene previously aged up to {approximately}100 d in Mount Pleasant silt loam (Mt. Pleasant, NY, USA) or Pahokee peat soil to determine as a function of the aging period the degree of correlation between the reduction in bioavailability and the rate and extent of desorption and the influence of soil organic matter composition on availability. The mineralization of phenanthrene by two bacteria and the uptake of phenanthrene by earthworms showed expected declines with aging. Likewise, the rate of phenanthrene desorption in the absence of organisms decreased with aging. The decline in initial rate of mineralization or desorption was nearly an order of magnitude after 50 to 60 d of aging. Plots of normalized rates of mineralization or desorption practically coincided. Similarly, plots of normalized fraction mineralized or fraction desorbed during an arbitrary period gave comparable slopes. The partial removal of organic matter from the peat by extraction with dilute NaOH to leave the humin fraction reduced the biodegradation of phenanthrene aged for 38 and 63 d as compared to the nonextracted peat, but the effect disappeared at longer incubation times. The rate of desorption from samples of peat previously extracted with NaOH or Na{sub 4}P{sub 2}O{sub 7} declined with aging and, for a given aging period, was significantly slower than from nonextracted peat. This work shows that the reduction in bioavailability of phenanthrene over time in soil is directly correlated with reduction of its physical availability due to desorption limitations. In addition, this study shows that removal of extractable humic substances leads to a decline in the rate of desorption and in the bioavailability of the substrate.

  5. Soil microbial respiration from various microhabitats in Arctic landscape: impact of soil type, environmental conditions and soil age

    NASA Astrophysics Data System (ADS)

    Biasi, Christina; Jokinen, Simo; Marushchak, Maija; Trubnikova, Tatiana; Hämäläinen, Kai; Oinonen, Markku; Martikainen, Pertti

    2014-05-01

    Soil respiration is the second largest C flux between atmosphere and terrestrial ecosystems after gross primary production. Carbon dioxide released from soils is thus a major contributor to the atmospheric CO2 concentration. Despite the global importance, soil respiration and its components (heterotrophic and autotrophic respiration) remain poorly understood and not well constrained fluxes of the terrestrial C cycle. This is particularly true for the Arctic, where huge amounts of the Earth's soil carbon is stored. Here, we report on heterotrophic soil respiration rates from various Arctic tundra microhabitats measured in situ. The study site was Seida (67°07'N, 62°57'E, 100 m a.s.l.) which is characterized by typical sub-arctic permafrost landscape which comprises raised, vegetated permafrost peat plateaus, interspersed with spots of bare peat surfaces (peat circles), and upland mineral soils. We used isotope partitioning approach based on differences in natural abundance of 14C between soil and plants to separate sources of soil-respired CO2. In addition, the tradition trenching approach was employed. Complementary laboratory incubations with homogenized soil were conducted to assess primary decomposability of the soils and to identify age of the CO2 released and thus get more information on the nature of the sources of respiration. The major aim was to link SMR rates with of soil type, land cover class, soil physic-chemical properties (e.g. water content), soil C stocks and age of soil. Results show that, despite profound differences in soil characteristics and primary decomposability of organic matter, surface CO2 fluxes derived from soil microbial respiration rates were rather similar between microhabitats. The only factor which influenced, at least to some extent, the respiration rates was total soil C (and N) stocks in surface soils. There was some evidence for reduced soil-related CO2 emissions from peatlands, though results were not consistent between the

  6. Soil organic carbon pools in olive groves of different age

    NASA Astrophysics Data System (ADS)

    Massaccesi, Luisa; De Feudis, Mauro; Nasini, Luigi; Regni, Luca; D'Ascoli, Rosaria; Castaldi, Simona; Proietti, Primo; Agnelli, Alberto

    2016-04-01

    In the last years, the practices which favor the increase of soil organic carbon in the agroecosystem have been widely studied because of their influence on the reduction of atmospheric CO2 (Lal, 1993; Schlesinger, 2000). The accumulation of the organic carbon into the soil depends to a great extent upon climate and pedological properties (Burke et al., 1989; Miller et al., 1994), although in the agricultural soils the cultivation system also plays a key role. The olive grove might potentially represent a relevant land use to improve C sequestration in soil, but there are few data available to support this hypothesis. In a study site located in central Italy (Deruta, PG), we analyzed the soil organic carbon (SOC) pools in two olive groves of different age (7 and 30 years) and, as control, in a site adjacent to the groves cropped with cereals for at least 30 years. With the aim to isolate and quantify the active, intermediate and passive functional SOC pools in the olive groves and in the control, we used a combined physical and chemical fractionation method (Zimmermann et al., 2007). The main results shown that the total organic carbon content in the Ap horizons was the highest in the 30-years-old olive grove, followed by the 7-years-old olive grove, and then by the control soil. The content of active C, in form of particulate organic matter (POM) and water soluble organic matter (WEOM), was greater in the olive grove compared to the control soil and increase with the age of the grove. About the amount of C in the intermediate and passive pools, no significant differences were found among the olive groves and the control. These preliminary results indicated that the greater total organic C content occurred in the 30-year-old olive grove with respect to the 7-years-old grove and the control, has to be ascribed to the greater content of active organic matter (POM and WEOM), and not to the accumulation in soil of organic C in a more stabilised form.

  7. In situ soil remediation: Bacteria or fungi?

    SciTech Connect

    Cutright, T.J.; Lee, S.

    1995-07-01

    Contamination of the environment is not a new problem. For most of recorded history, the unwanted byproducts of industrial and residential processes have been dumped into unlined pits or nearby streams. Although disposal techniques have greatly improved, significant quantities of hazardous materials are still being released to the environment via accidental spills and leaking underground storage tanks. One particular group of contaminants of critical environmental concern is polycyclic aromatic hydrocarbons (PAHs). PAH-contaminated sites typically cover large areas; therefore, the development of in situ remediation techniques such as bioremediation is strongly emphasized. In situations when inherent microorganisms are not capable of degrading the contaminants, foreign strains must be used. Bioremediation experiments were conducted to compare the remediation efficiencies of a bacteria and a fungus for an industrially PAH contaminated soil. Specifically, the use of three supplemental nutrient solutions were investigated in conjunction with the bacteria Achromobacter sp. and fungus Cunninghamella echinulata var. elegans.

  8. Use of soil catena field data for estimating relative ages of moraines

    SciTech Connect

    Birkeland, P.W.; Berry, M.E. ); Swanson, D.K. )

    1991-03-01

    Soils at the crests of moraines are commonly used to estimate the relative ages of moraines. However, for various pedologic and geomorphic reasons, soil development at crest sites may not truly reflect the time since moraine formation; for example, some crest soils on moraines of greatly different age are similar in morphology and development. Soil catena data for soils at several sites aligned downslope from the crest can greatly improve on the usefulness of soil data for estimating moraine ages. For this purpose, the authors use the weighted mean catena profile development index, which condenses field data for all of the soils in each catena into a single value.

  9. Enzymatic bioremediation of polyaromatic hydrocarbons by fungal consortia enriched from petroleum contaminated soil and oil seeds.

    PubMed

    Balaji, V; Arulazhagan, P; Ebenezer, P

    2014-05-01

    The present study focuses on fungal strains capable of secreting extracellular enzymes by utilizing hydrocarbons present in the contaminated soil. Fungal strains were enriched from petroleum hydrocarbons contaminated soil samples collected from Chennai city, India. The potential fungi were isolated and screened for their enzyme secretion such as lipase, laccase, peroxidase and protease and also evaluated fungal enzyme mediated PAHs degradation. Total, 21 potential PAHs degrading fungi were isolated from PAHs contaminated soil, which belongs to 9 genera such as Aspergillus, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor Penicillium, Rhizopus, Trichoderma, and two oilseed-associated fungal genera such as Colletotrichum and Lasiodiplodia were used to test their efficacy in degradation of PAHs in polluted soil. Maximum lipase production was obtained with P. chrysogenum, M. racemosus and L. theobromae VBE1 under optimized cultural condition, which utilized PAHs in contaminated soil as sole carbon source. Fungal strains, P. chrysogenum, M. racemosus and L. theobromae VBE1, as consortia, used in the present study were capable of degrading branched alkane isoprenoids such as pristine (C17) and pyrene (C18) present in PAHs contaminated soil with high lipase production. The fungal consortia acts as potential candidate for bioremediation of PAHs contaminated environments.

  10. Enzymatic bioremediation of polyaromatic hydrocarbons by fungal consortia enriched from petroleum contaminated soil and oil seeds.

    PubMed

    Balaji, V; Arulazhagan, P; Ebenezer, P

    2014-05-01

    The present study focuses on fungal strains capable of secreting extracellular enzymes by utilizing hydrocarbons present in the contaminated soil. Fungal strains were enriched from petroleum hydrocarbons contaminated soil samples collected from Chennai city, India. The potential fungi were isolated and screened for their enzyme secretion such as lipase, laccase, peroxidase and protease and also evaluated fungal enzyme mediated PAHs degradation. Total, 21 potential PAHs degrading fungi were isolated from PAHs contaminated soil, which belongs to 9 genera such as Aspergillus, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor Penicillium, Rhizopus, Trichoderma, and two oilseed-associated fungal genera such as Colletotrichum and Lasiodiplodia were used to test their efficacy in degradation of PAHs in polluted soil. Maximum lipase production was obtained with P. chrysogenum, M. racemosus and L. theobromae VBE1 under optimized cultural condition, which utilized PAHs in contaminated soil as sole carbon source. Fungal strains, P. chrysogenum, M. racemosus and L. theobromae VBE1, as consortia, used in the present study were capable of degrading branched alkane isoprenoids such as pristine (C17) and pyrene (C18) present in PAHs contaminated soil with high lipase production. The fungal consortia acts as potential candidate for bioremediation of PAHs contaminated environments. PMID:24813008

  11. Sorption and dissipation of aged metolachlor residues in eroded and rehabilitated soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To accurately determine availability for offsite transport, sorption and dissipation of aged metolachlor were characterized in rehabilitated and eroded prairie soils using sequential batch slurry and accelerated solvent extraction (ASE). In the eroded upper slope, soil-landscape rehabilitation more ...

  12. Impact of temperature on the aging mechanisms of arsenic in soils: fractionation and bioaccessibility.

    PubMed

    Huang, Guanxing; Chen, Zongyu; Wang, Jia; Hou, Qinxuan; Zhang, Ying

    2016-03-01

    The present study focused on the influence of temperature variation on the aging mechanisms of arsenic in soils. The results showed that higher temperature aggravated the decrease of more mobilizable fractions and the increase of less mobilizable or immobilizable fractions in soils over time. During the aging process, the redistribution of both carbonate-bound fraction and specifically sorbed and organic-bound fraction in soils occurred at various temperatures, and the higher temperature accelerated the redistribution of specifically sorbed and organic-bound fraction. The aging processes of arsenic in soils at different temperatures were characterized by several stages, and the aging processes were not complete within 180 days. Arsenic bioaccessibility in soils decreased significantly by the aging, and the decrease was intensified by the higher temperature. In terms of arsenic bioaccessibility, higher temperature accelerated the aging process of arsenic in soils remarkably.

  13. Nutrient-stimulated biodegradation of aged refinery hydrocarbons in soil

    SciTech Connect

    Drake, E.N.; Stokley, K.E.; Calcavecchio, P.; Bare, R.E.; Rothenburger, S.J.; Prince, R.C.; Douglas, G.S.

    1995-12-31

    Aged hydrocarbon-contaminated refinery soil was amended with water and nutrients and tilled weekly for 1 year to stimulate biodegradation. Gas chromatography/mass spectrometry (GC/MS) analysis of polycyclic aromatic compounds (PAHs) and triterpane biomarkers, and Freon IR analysis of total petroleum hydrocarbons (TPH), were used to determine the extent of biodegradation. There was significant degradation of extractable hydrocarbon (up to 60%), but neither hopane, oleanane, nor the amount of polars decreased during this period of bioremediation, allowing them to be used as conserved internal markers for estimating biodegradation. Significant degradation of the more alkylated two- and three-ring compounds, and of the four-ring species pyrene and chrysene and their alkylated congeners, was seen. Substantial degradation (> 40%) of benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene also was seen. The results show that bioremediation can be a useful treatment in the cleanup of contaminated refinery sites.

  14. Effects of Forest Age on Soil Fungal Community in a Northern Temperate Ecosystem.

    PubMed

    Zhiguang, Han; Xin, Sui; Mengsha, Li

    2016-09-01

    The polymorphisms of soil fungal rDNA Internal Transcribed Spacer regions were studied in Korean pine forests of various ages (10-100-year-old trees) by means of cloned libraries, and analyzed to determine the effects of the trees' developmental stage on soil fungal community structure. The obtained Shannon diversity index (H) and richness (S) indicated that the diversity of the soil fungal community increased significantly with the development of Korean pines (P < 0.05). In addition, cluster analysis (UPGMA) showed that the soil fungal community variety associated with differently aged Korean pines was higher than 50 %. The soil fungal community diversity correlated significantly with the N content and C/N ratio of the soil (P < 0.05). The results of this study indicate that the age of in Korean pine can affect soil fungal community by altering soil properties, which in turn could affect the nutrient cycling in the forest ecosystem.

  15. Micromorphology of past urban soils: method and results (France, Iron Age - Middle Age)

    NASA Astrophysics Data System (ADS)

    Cammas, Cécilia

    2014-05-01

    Urban soils in French protohistoric and Roman towns and present-day towns of roman origin are several meters thick accumulations, with great spatial and vertical variability due to long duration of occupation. In order to improve our knowledge of both sedimentary and pedological characteristics as well as formation processes of urban soils, micromorphological analysis was carried out on buried towns. The studied sites include Iron Age towns (floodplain sites: Lattes or Lattara, Le Cailar; oppidum: Pech-Maho in the south of France), a roman buried town (Famars or Fanum Martis, North of France), and various towns occupied from the Roman period until now (urban and periurban sites in Paris, Strasbourg, Mâcon… North and East of France). Original method and sampling strategy were elaborated in order to try to encompass both spatial and vertical variability as well as the "mitage" of the present-day cities. In Lattes, representative elementary urban areas such as streets, courtyard, and houses were sampled for micromorphology during extensive excavation. These analyses revealed specific microscopic features related to complex anthropogenic processes (craft and domestic activities discarding, trampling, backfill, building), moisture and heat, and biological activity, which defined each kind of area. Comparison between well preserved buried town and current cities of roman origin, where the sequence of past urban soils is preserved in few place ("mitage") help to identify past activities, building rhythms as well as specific building materials. For example, in Paris, compacted sandy backfills alternate with watertight hardfloors during the Roman period (soils similar to Technosols). At the opposite, various kinds of loose bioturbated laminated dark earth resulting from activities such as craft refuses, backfills, compost or trampled layers were discriminated for Early Medieval Period (soils similar to Cumulic Anthroposol). Moreover, biological activity is usually

  16. POP and PAH contamination in the southern slopes of Mt. Everest (Himalaya, Nepal): Long-range atmospheric transport, glacier shrinkage, or local impact of tourism?

    PubMed

    Guzzella, Licia; Salerno, Franco; Freppaz, Michele; Roscioli, Claudio; Pisanello, Francesca; Poma, Giulia

    2016-02-15

    Due to their physico-chemical properties, POPs and PAHs are subjected to long-range atmospheric transport (LRAT) and may be deposited in remote areas. In this study, the contamination with DDx, PCBs, PBDEs, and PAHs was investigated in sediments and soils collected on the southern slopes of Mt. Everest (Himalaya, Nepal) in two different sampling campaigns (2008 and 2012). The results showed a limited contamination with POPs and PAHs in both soil and sediment samples. Therefore, the southern slopes of Mt. Everest can be considered a remote area in almost pristine condition. The LRAT mechanism confirmed its primary role in the transfer of contaminants to remote regions, while the gradual melting of glaciers, due to global warming, and the subsequent release of contaminants was suggested to be a secondary source of pollution of the lake sediments. In addition, the increase of tourism in this area during the last decades might have influenced the present concentrations of PAHs in the sediments and soils. PMID:26657383

  17. [Status and changes of soil nutrients in rhizosphere of Abelmoschus manihot different planting age].

    PubMed

    Tang, Li-Xia; Tan, Xian-He; Zhang, Yu; Liu, Xiao-Ning

    2013-11-01

    Using soil chemical analysis method and combining with ICP-AES determination of mineral nutrition element content in rhizosphere soil of different planting age Abelmoschus Corolla Results show that along with the increase of planting age, the nitrogen (total N), available P and organic matter in rhizosphere soil of Abelmoschus Corolla content declined year by year and the soil got acidification. Heavy metal element content in agricultural land does not exceed national standards, but the content of element mercury (Hg) in rhizosphere soil of different planting age Abelmoschus Corolla declined. Request of microelement such as manganese (Mn) and zinc (Zn) had a increase tendency, but the content of magnesium (Mg) and sodium (Na) increased, and other nutrient elements had no changed rules or unchanged apparently. Consequently, exploring the change rules of different planting age Abelmoschus Corolla soil in rhizosphere as theoretical guidance of rational fertilization and subducting continuous cropping obstscles.

  18. [Status and changes of soil nutrients in rhizosphere of Abelmoschus manihot different planting age].

    PubMed

    Tang, Li-Xia; Tan, Xian-He; Zhang, Yu; Liu, Xiao-Ning

    2013-11-01

    Using soil chemical analysis method and combining with ICP-AES determination of mineral nutrition element content in rhizosphere soil of different planting age Abelmoschus Corolla Results show that along with the increase of planting age, the nitrogen (total N), available P and organic matter in rhizosphere soil of Abelmoschus Corolla content declined year by year and the soil got acidification. Heavy metal element content in agricultural land does not exceed national standards, but the content of element mercury (Hg) in rhizosphere soil of different planting age Abelmoschus Corolla declined. Request of microelement such as manganese (Mn) and zinc (Zn) had a increase tendency, but the content of magnesium (Mg) and sodium (Na) increased, and other nutrient elements had no changed rules or unchanged apparently. Consequently, exploring the change rules of different planting age Abelmoschus Corolla soil in rhizosphere as theoretical guidance of rational fertilization and subducting continuous cropping obstscles. PMID:24558867

  19. Age of respired carbon in differently managed grassland and forest soils

    NASA Astrophysics Data System (ADS)

    Schoening, Ingo; Trumbore, Susan; Solly, Emily; Muhr, Jan; Schrumpf, Marion

    2013-04-01

    Grassland management (fertilization, grazing, mowing) and forest management (harvesting, thinning) directly affect biomass production and related leaf and root litter input to the soil. Understanding effects of land management on soil carbon fluxes is therefore critical. We examined the effect of land use and management on soil respiration and the age of respired soil carbon. Soil samples originated from grassland and forest plots in three different German regions. Sieved surface soil samples (0-10 cm) were incubated (20°C, 60% WHC) for 14 days. The respired CO2 was collected and 14C contents in the CO2 of 150 incubated samples were determined with accelerator mass spectrometry (AMS). Large changes recorded in 14C in the atmosphere since atmospheric weapons testing in the 1960s allow precise determination of the mean age of emitted soil carbon. In our study, the rate of respiration was higher in grassland soils (33 ± 10 µg C-CO2 per g dry soil per day) compared to forest soils (14 ± 7 µg C-CO2 per g dry soil per day). Results indicate a strong relation between respiration rates and grassland management with lower soil respiration in more fertilized plots. This relation was not found at sites where degraded peatlands were used as grasslands. At those sites, respiration rates were mainly driven by the soil organic carbon concentration. In forest soils, we did not find any relation between soil respiration and forest management. The 14C contents of the respired CO2 were lower in grassland soils (Percentage Modern carbon content: 104±2%) compared to forest soils (Percentage Modern Carbon content: 108±5%). This indicates that the carbon respired in forests is generally several years to more than a decade older than the carbon respired in grasslands. In grasslands, the 14C is positively related to the respiration rate and negatively related to fertilization. Again, degraded peat soils, where old carbon is released during incubation, were the exception to this

  20. Hydrocarbon status of soils under different ages of oil contamination

    NASA Astrophysics Data System (ADS)

    Gennadiev, A. N.; Pikovskii, Yu. I.; Kovach, R. G.; Koshovskii, T. S.; Khlynina, N. I.

    2016-05-01

    Modifications of the hydrocarbon status (HCS) of soils at the stages of the injection input of oil pollutants and the subsequent self-purification of the soil layer from technogenesis products have been revealed in studies conducted on an oil field. Comparison with the HCS of background soils has been performed. Changes in the composition and concentration of bitumoids, polycyclic aromatic hydrocarbons (PAHs), and hydrocarbon gases have been established. The HCS of a freshly contaminated soil is characterized by the predominance of butane (the highest component) in the gaseous phase, an abrupt increase in the concentration of second-kind bitumoids, and a 100-fold increase in the content of PAHs compared to the background soil. In the old contaminated soil, free and fixed methane becomes the predominant gas; the content of bitumoids in the upper soil horizons is lower than in the freshly contaminated soils by two orders of magnitude but higher than in the background soil by an order of magnitude; the PAH composition in the soil with old residual contamination remains slightly more diverse than in the background soil.

  1. Bioavailability of freshly added and aged naphthalene in soils under gastric pH conditions

    SciTech Connect

    Jin, Z.; Simkins, S.; Xing, B.

    1999-12-01

    The bioavailability of hydrophobic organic chemicals decreases with aging in soil because of sequestration. However, assessments of the risk of exposure to contaminated soils are usually dependent on either chemical concentrations, which are measured using vigorous extraction methods, or models that assume an equilibrium without considering the actual conditions. The objective of this research was to determine the availability and desorption kinetics of freshly added and aged naphthalene from a peat and a mineral soil; naphthalene was desorbed into solutions with pH levels that approximate those found in different gastric regions. Soil and peat samples were spiked with radiolabeled and unlabeled naphthalene at 2 and 20 {micro}g/g and were aged from 0 to 135 d. Desorption kinetics were determined using a simulated stomach solution and a neutral solution that represented the pH of intestinal conditions and most soils. Peat sorbed much more naphthalene than did soil, and it allowed little desorption. Though both acidic and neutral extracting solutions could desorb naphthalene, little apparent effect of aging was observed in peat, whereas desorption from soil declined markedly with aging. In addition, the percentage of naphthalene that desorbed from soil was greater for the higher incubation concentration. The desorption of naphthalene from the peat and soil was higher into the neutral solution than into the gastric solution. These results suggest that aging, exposure conditions, concentration effect, and organic matter content should be taken into account in predictive models and risk assessments.

  2. Different influences of field aging on nickel toxicity to Folsomia candida in two types of soil.

    PubMed

    Liu, Yu-Rong; Li, Jing; He, Ji-Zheng; Ma, Yi-Bing; Zheng, Yuan-Ming

    2015-06-01

    Metal aging in soils has been considered an important factor influencing its availability and toxicity to organisms. In this study, we report the influence of 5 years field aging on the nickel (Ni) toxicity to collembolan Folsomia candida based on two different types of soil from Dezhou (DZ) and Qiyang (QY) counties in China. Acute and chronic toxicity of Ni to F. candida was assessed in both freshly spiked and field aging contaminated soils. We found that 5 years field aging increased the EC50 and 2d-LC50 values of Ni to F. candida in the DZ soil, while little influence on the Ni toxicity was observed in the QY soil. There was no adverse effect of the long-term field aging on the Ni toxicity to the survival of F. candida in the two tested soils. In addition, field aging of the two soils impacted differently the water-soluble Ni concentrations, which were significantly correlated to the juvenile production of F. candida based on a logistic model. Our study highlights different effects of long-term field aging on the Ni toxicity to F. candida between divergent types of soil, and this should be taken into account in future toxicity testing and risk assessment practices.

  3. Effect of aging process on adsorption of diethyl phthalate in soils amended with bamboo biochar.

    PubMed

    Zhang, Xiaokai; Sarmah, Ajit K; Bolan, Nanthi S; He, Lizhi; Lin, Xiaoming; Che, Lei; Tang, Caixian; Wang, Hailong

    2016-01-01

    Biochar is a carbonaceous sorbent and can be used as a potential material to reduce the bioavailability of organic pollutants in contaminated soils. In the present study, the adsorption and desorption of diethyl phthalate (DEP) onto soils amended with bamboo biochar was investigated with a special focus on the effect of biochar application rates and aging conditions on the adsorption capacity of the soils. Biochar amendment significantly enhanced the soil adsorption of DEP that increased with increasing application rates of biochar. However, the adsorption capacity decreased by two aging processes (alternating wet and dry, and constantly moist). In the soil with low organic carbon (OC) content, the addition of 0.5% biochar (without aging) increased the adsorption by nearly 98 times compared to the control, and exhibited the highest adsorption capacity among all the treatments. In the soil with high OC content, the adsorption capacity in the treatment of 0.5% biochar without aging was 3.5 and 3 times greater than those of the treatments of biochar aged by alternating wet and dry, and constantly moist, respectively. Moreover, constantly moist resulted in a greater adsorption capacity than alternating wet and dry treatments regardless of biochar addition. This study revealed that biochar application enhanced soil sorption of DEP, however, the enhancement of the adsorption capacity was dependent on the soil organic carbon levels, and aging processes of biochar.

  4. [Population structure of soil arthropod in different age Pinus massoniana plantations].

    PubMed

    Tan, Bo; Wu, Fu-zhong; Yang, Wan-qin; Zhang, Jian; Xu, Zhen-feng; Liu, Yang; Gou, Xiao-lin

    2013-04-01

    An investigation was conducted on the population structure of soil arthropod community in the 3-, 8-, 14-, 31-, and 40-years old Pinus massoniana plantations in the upper reaches of the Yangtze River in spring (May) and autumn (October), 2011, aimed to search for the scientific management of the plantation. A total of 4045 soil arthropods were collected, belonging to 57 families. Both the individual density and the taxonomic group number of the soil arthropod community decreased obviously with increasing soil depth, and this trend increased with increasing stand age. The dominant groups and ordinary groups of the soil arthropod community varied greatly with the stand age of P. massoniana plantation, and a significant difference (P<0.05) was observed in the individual density and taxonomic group number among different age P. massoniana plantations. In comparison with other stand age P. massoniana plantations, 3years old P. massoniana plantation had a significant difference in the structure and diversity of soil arthropod community, and the similarity index of the soil arthropod community was lower. The individual density, taxonomic group number, and diversity of soil arthropod community were the highest in 8-years old P. massoniana plantation, and then, decreased obviously with increasing stand age. It was suggested that the land fertility of the P. massoniana plantations could be degraded with increasing stand age, and it would be appropriate to make artificial regulation and restoration in 8-years old P. massoniana plantation.

  5. Plant nutrient-acquisition strategies change with soil age.

    PubMed

    Lambers, Hans; Raven, John A; Shaver, Gaius R; Smith, Sally E

    2008-02-01

    Nitrogen (N) tends to limit plant productivity on young soils; phosphorus (P) becomes increasingly limiting in ancient soils because it gradually disappears through leaching and erosion. Plant traits that are regarded as adaptations to N- and P-limited conditions include mycorrhizas and cluster roots. Mycorrhizas 'scavenge' P from solution or 'mine' insoluble organic N. Cluster roots function in severely P-impoverished landscapes, 'mining' P fixed as insoluble inorganic phosphates. The 'scavenging' and 'mining' strategies of mycorrhizal species without and non-mycorrhizal species with cluster roots, respectively, allow functioning on soils that differ markedly in P availability. Based on recent advances in our understanding of these contrasting strategies of nutrient acquisition, we provide an explanation for the distribution of mycorrhizal species on less P-impoverished soils, and for why, globally, cluster-bearing species dominate on severely P-impoverished, ancient soils, where P sensitivity is relatively common.

  6. Soil biogeochemistry in the age of big data

    NASA Astrophysics Data System (ADS)

    Cécillon, Lauric; Barré, Pierre; Coissac, Eric; Plante, Alain; Rasse, Daniel

    2015-04-01

    Data is becoming one of the key resource of the XXIst century. Soil biogeochemistry is not spared by this new movement. The conservation of soils and their services recently came into the political agenda. However, clear knowledge on the links between soil characteristics and the various processes ensuring the provision of soil services is rare at the molecular or the plot scale, and does not exist at the landscape scale. This split between society's expectations on its natural capital, and scientific knowledge on the most complex material on earth has lead to an increasing number of studies on soils, using an increasing number of techniques of increasing complexity, with an increasing spatial and temporal coverage. From data scarcity with a basic data management system, soil biogeochemistry is now facing a proliferation of data, with few quality controls from data collection to publication and few skills to deal with them. Based on this observation, here we (1) address how big data could help in making sense of all these soil biogeochemical data, (2) point out several shortcomings of big data that most biogeochemists will experience in their future career. Massive storage of data is now common and recent opportunities for cloud storage enables data sharing among researchers all over the world. The need for integrative and collaborative computational databases in soil biogeochemistry is emerging through pioneering initiatives in this direction (molTERdb; earthcube), following soil microbiologists (GenBank). We expect that a series of data storage and management systems will rapidly revolutionize the way of accessing raw biogeochemical data, published or not. Data mining techniques combined with cluster or cloud computing hold significant promises for facilitating the use of complex analytical methods, and for revealing new insights previously hidden in complex data on soil mineralogy, organic matter and biodiversity. Indeed, important scientific advances have

  7. Effects of aging on the fraction distribution and bioavailability of selenium in three different soils.

    PubMed

    Li, Jun; Peng, Qin; Liang, Dongli; Liang, Sijie; Chen, Juan; Sun, Huan; Li, Shuqi; Lei, Penghui

    2016-02-01

    Aging refers to the processes by which the mobility and bioavailability of metals in soil decline with time. Although long-term aging is a key process that needs to be considered in risk assessment of metals, few investigations has been attempted to determine whether and how residence time influences the selenium (Se) fractions and bioavailability in soil. In this study, the fractions of Se in soils was evaluated, and bioavailability were assessed by measuring Se concentration in pak choi (Brassica chinensis L.). Results showed that the change of soil available Se in all tested soils divided into two phases: rapid decrease at the initial time (42 d) and slow decline thereafter. The second-order equation could describe the decrease processes of available Se in tested soils during the entire incubation time (R(2) > 0.99), while parabolic diffusion equation had less goodness of fit. Those results indicated that Se aging was controlled not only by diffusion process but also by other processes such as nucleation/precipitation, adsorption/desorption with soil component, occlusion by organic matter and reduction reaction. Soil available Se fractions tended to transform to more stable fractions during aging. The changes of Se concentration in pak choi were consistent with the variation in soil available Se content. In addition, 21 d could be reference for the time of Se aging reaching stabilization in krasnozems and fluvo-aquic soil, and 30 d for black soil. Results could provide theoretical basis to formulate environmental quality criterion and choose the equilibrium time before implementing a pot experiment in Se-spiked soils. PMID:26606190

  8. Changes in dissolved organic carbon of soil amendments with aging: effect on pesticide adsorption behavior.

    PubMed

    Cox, Lucia; Fernandes, M Conceicao; Zsolnay, Adam; Hermosín, M Carmen; Cornejo, Juan

    2004-09-01

    The effect of aging in the soil of three organic amendments (OAs), one liquid (LF) and two solid ones (SF and AL), has been investigated and related to changes in soil adsorption of metalaxyl and tricyclazole. LF and AL have very high dissolved organic carbon (DOC) contents with low humification index values, whereas SF has a low DOC content but the highest amounts of highly humified material. All OAs increased the adsorption of tricyclazole, whereas adsorption of metalaxyl decreased in soils amended with LF and AL, due to competition with DOC for mineral adsorption sites. With aging, DOC from SF amended soils is not significantly affected and neither is adsorption behavior. On the contrary, the great reduction of DOC from LF and AL with aging has been shown to affect adsorption of metalaxyl and tricyclazole, and this effect is dependent on the pesticide, the nature of the DOC, and the type of soil, in particular its clay mineralogy.

  9. Metolachlor Sorption and Degradation in Soil Amended with Fresh and Aged Biochars.

    PubMed

    Trigo, Carmen; Spokas, Kurt A; Hall, Kathleen E; Cox, Lucia; Koskinen, William C

    2016-04-27

    Addition of organic amendments such as biochar to soils can influence pesticide sorption-desorption processes and, in turn, the amount of pesticide readily availability for transport and biodegradation. Sorption-desorption processes are affected by both the physical and chemical properties of soils and pesticides, as well as soil-pesticide contact time, or aging. Changes in sorption-desorption of metolachlor with aging in soil amended with three macadamia nut shell biochars aged 0 (BCmac-fr), 1 year (BCmac-1yr), and 2 years (BCmac-2yr) and two wood biochars aged 0 (BCwood-fr) and 5 years (BCwood-5yr) were determined. Apparent sorption coefficient (Kd-app) values increased with incubation time to a greater extent in amended soil as compared to unamended soils; Kd-app increased by 1.2-fold for the unamended soil, 2.0-fold for BCwood-fr, 1.4-fold for BCwood-5yr, 2.4-fold for BCmac-fr, 2.5-fold for BCmac-1yr, and 1.9-fold for BCmac-4yr. The increase in calculated Kd-app value was the result of a 15% decrease in the metolachlor solution concentration extractable with CaCl2 solution with incubation time in soil as compared to a 50% decrease in amended soil with very little change in the sorbed concentration. Differences could possibly be due to diffusion to less accessible or stronger binding sites with time, a faster rate of degradation (in solution and on labile sites) than desorption, or a combination of the two in the amended soils. These data show that transport models would overpredict the depth of movement of metolachlor in soil if effects of aging or biochar amendments are not considered.

  10. Pb, Zn and Cd mobility, availability and fractionation in aged soil remediated by EDTA leaching.

    PubMed

    Udovic, Metka; Lestan, Domen

    2009-03-01

    Soil washing remediation techniques usually remove only the labile heavy metal (HM) species from the soil, leaving the residual ones in less available/mobile forms, thus disturbing the chemical equilibrium among different species of HM in the soil. Re-establishing such equilibrium and shifting HM back to more available/mobile chemical forms could occur after exposing the remediated soil to environmental abiotic (ageing) factors. Contaminated soil from a smelter site (Pb 4600 mg kg(-1), Zn 1800 mg kg(-1), Cd 30 mg kg(-1)) was leached with increasing EDTA concentrations (2.5, 5.0, 10.0, 20.0, 40.0 and 4-consecutive steps of 40.0 mmol EDTA kg(-1) of soil). A gradient of removed HM was reached: from 6% to 73% of initial Pb, from 3% to 23% of initial Zn and from 17% to 74% of initial Cd were removed. Repetitive temperature changes (105 degrees C and -20 degrees C) were used to mimic abiotic factors acting on residual HM after EDTA soil leaching in saturated soil at 10% and 90% of soil water holding capacity. Fractionation using sequential extractions, mobility, and phytoavailability of Pb, Zn and Cd and Pb oral bioavailability were determined for aged and non-aged soil. The ageing treatment consistently lowered HM phytoavailability in the original (non-leached) and all treated (chelant-leached) soils. However, Pb, Zn and Cd behaved differently from each other; Pb mobility increased, Cd mobility decreased, while Zn mobility did not change. The results indicate that abiotic (ageing) processes change the availability/mobility of residual HM in all leaching treatments and should thus be considered in final remediation effectivity evaluation.

  11. Metolachlor Sorption and Degradation in Soil Amended with Fresh and Aged Biochars.

    PubMed

    Trigo, Carmen; Spokas, Kurt A; Hall, Kathleen E; Cox, Lucia; Koskinen, William C

    2016-04-27

    Addition of organic amendments such as biochar to soils can influence pesticide sorption-desorption processes and, in turn, the amount of pesticide readily availability for transport and biodegradation. Sorption-desorption processes are affected by both the physical and chemical properties of soils and pesticides, as well as soil-pesticide contact time, or aging. Changes in sorption-desorption of metolachlor with aging in soil amended with three macadamia nut shell biochars aged 0 (BCmac-fr), 1 year (BCmac-1yr), and 2 years (BCmac-2yr) and two wood biochars aged 0 (BCwood-fr) and 5 years (BCwood-5yr) were determined. Apparent sorption coefficient (Kd-app) values increased with incubation time to a greater extent in amended soil as compared to unamended soils; Kd-app increased by 1.2-fold for the unamended soil, 2.0-fold for BCwood-fr, 1.4-fold for BCwood-5yr, 2.4-fold for BCmac-fr, 2.5-fold for BCmac-1yr, and 1.9-fold for BCmac-4yr. The increase in calculated Kd-app value was the result of a 15% decrease in the metolachlor solution concentration extractable with CaCl2 solution with incubation time in soil as compared to a 50% decrease in amended soil with very little change in the sorbed concentration. Differences could possibly be due to diffusion to less accessible or stronger binding sites with time, a faster rate of degradation (in solution and on labile sites) than desorption, or a combination of the two in the amended soils. These data show that transport models would overpredict the depth of movement of metolachlor in soil if effects of aging or biochar amendments are not considered. PMID:27050383

  12. Mechanisms of Heavy Metal Sequestration in Soils: Plant-Microbe Interactions and Organic Matter Aging

    SciTech Connect

    Teresa W.-M. Fan; Richard M. Higashi; David Crowley; Andrew N. Lane: Teresa A. Cassel; Peter G. Green

    2004-12-31

    For stabilization of heavy metals at contaminated sites, the three way interaction among soil organic matter (OM)-microbes-plants, and their effect on heavy metal binding is critically important for long-term sustainability, a factor that is poorly understood at the molecular level. Using a soil aging system, the humification of plant matter such as wheat straw was probed along with the effect on microbial community on soil from the former McClellan Air Force Base.

  13. Do Forest Age and Soil Depth Affect Carbon and Nitrogen Adsorption in Mineral Horizons?

    NASA Astrophysics Data System (ADS)

    Spina, P. G.; Lovett, G. M.; Fuss, C. B.; Goodale, C. L.; Lang, A.; Fahey, T.

    2015-12-01

    Mineral soils retain large amounts of organic matter through sorption on the surfaces of mineral soils, the largest pools of carbon (C) and nitrogen (N) in the forests of the northeastern U.S. In addition to determining organic matter storage, adsorption and desorption processes are important controllers of runoff chemistry. We are studying adsorption dynamics of mineral soils collected from a chronosequence of hardwood forest sites in the White Mountains, NH to determine how soils vary in their DOM adsorption capacities as a function of effective C and N saturation. We hypothesize that forest age determines proximity to saturation because young forests may need to mine soil organic matter (SOM) in mineral soils to obtain nitrogen to meet growth demands, while the soils of older forests have had time to reaccumulate SOM, eventually reaching C and N saturation. Consequently, we expect adsorption capacities to first increase with forest age in young forests, as the trees mine C and N from mineral surfaces. They will then decrease with forest age in older forests as mining slows and C and N begin to re-accumulate. Batch experiments were conducted with mineral soil samples and dilutions of forest floor leachate. However, preliminary results from a mature forest site (about 100 years old), which we predicted to be a low point of C and N saturation from decades of mining, contradict expectations. Dissolved organic carbon (DOC) adsorption in its shallow mineral soil layers (0-3 cm below E or A horizons) are lower than younger sites ranging from 20 to about 40 years old. In addition to forest age, soil depths also affect N retention dynamics in forest soils. We hypothesized that deeper mineral soils might have greater adsorption capacities due to the fact that they are exposed to less DOC and DON leaching from organic layers and therefore less saturated. Results from the same mature forest site confirm this. Soils from 3-10 cm depth have more potential to adsorb DOC and

  14. Strong Impact on the Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Community of a PAH-Polluted Soil but Marginal Effect on PAH Degradation when Priming with Bioremediated Soil Dominated by Mycobacteria▿

    PubMed Central

    Johnsen, Anders R.; Schmidt, Stine; Hybholt, Trine K.; Henriksen, Sidsel; Jacobsen, Carsten S.; Andersen, Ole

    2007-01-01

    Bioaugmentation of soil polluted with polycyclic aromatic hydrocarbons (PAHs) is often disappointing because of the low survival rate and low activity of the introduced degrader bacteria. We therefore investigated the possibility of priming PAH degradation in soil by adding 2% of bioremediated soil with a high capacity for PAH degradation. The culturable PAH-degrading community of the bioremediated primer soil was dominated by Mycobacterium spp. A microcosm containing pristine soil artificially polluted with PAHs and primed with bioremediated soil showed a fast, 100- to 1,000-fold increase in numbers of culturable phenanthrene-, pyrene-, and fluoranthene degraders and a 160-fold increase in copy numbers of the mycobacterial PAH dioxygenase gene pdo1. A nonpolluted microcosm primed with bioremediated soil showed a high rate of survival of the introduced degrader community during the 112 days of incubation. A nonprimed control microcosm containing pristine soil artificially polluted with PAHs showed only small increases in the numbers of culturable PAH degraders and no pdo1 genes. Initial PAH degradation rates were highest in the primed microcosm, but later, the degradation rates were comparable in primed and nonprimed soil. Thus, the proliferation and persistence of the introduced, soil-adapted degraders had only a marginal effect on PAH degradation. Given the small effect of priming with bioremediated soil and the likely presence of PAH degraders in almost all PAH-contaminated soils, it seems questionable to prime PAH-contaminated soil with bioremediated soil as a means of large-scale soil bioremediation. PMID:17209064

  15. Geophagy in chacma baboons: patterns of soil consumption by age class, sex, and reproductive state.

    PubMed

    Pebsworth, Paula A; Bardi, Massimo; Huffman, Michael A

    2012-01-01

    Despite baboons' widespread distribution across Africa, geophagy among all subspecies has been poorly documented. We used video camera traps and soil analyses to investigate geophagy in chacma baboons (Papio cynocephalus ursinus) inhabiting the Western Cape of South Africa. During an 18-month study, from August 2009 to January 2011, we continually monitored the largest and most frequently visited geophagy sites with camera traps for 545 days and captured soil consumption at one or more sites on 266 of those days (49%). In 3,500 baboon visits to geophagy sites, video camera traps captured 58.6 hr of geophagy. From these data, we evaluated site preference based on time spent consuming soil among these four geophagy sites. One hundred and seventy days of soil consumption data from the most frequently visited geophagy site allowed us to look for demographic trends in geophagy. Selected consumed soils from geophagy sites were analyzed for mineral, physical, and chemical properties. The baboons spent more time consuming white alkaline soils with high percentages of clay and fine silt, which contained higher concentrations of sodium than non-white acidic soils that contained higher concentrations of iron. Our data indicate that pregnant chacma baboons spent more time consuming soil at monitored geophagy sites than baboons of any other age class, sex, or reproductive state. Based on analytical results, the soils consumed would be effective at alleviating gastrointestinal distress and possibly supplementing minerals for all age/sex classes, but potentially for different age/sex requirements. PMID:21969111

  16. Ageing of atrazine in manure amended soils assessed by bioavailability to Pseudomonas sp. strain ADP.

    PubMed

    Glæsner, Nadia; Bælum, Jacob; Strobel, Bjarne W; Jacobsen, Carsten S

    2014-04-01

    Animal manure is applied to agricultural land in areas of high livestock production. In the present study, we evaluated ageing of atrazine in two topsoils with and without addition of manure and in one subsoil. Ageing was assessed as the bioavailability of atrazine to the atrazine mineralizing bacteria Pseudomonas sp. strain ADP. Throughout an ageing period of 90 days bioavailability was investigated at days 1, 10, 32, 60 and 90, where ~10(8) cells g(-1) of the ADP strain was inoculated to the (14)C-atrazine exposed soil and (14)CO2 was collected over 7 days as a measure of mineralized atrazine. Even though the bioavailable residue decreased in all of the three soils as time proceeded, we found that ageing occurred faster in the topsoils rich in organic carbon than in subsoil. For one topsoil rich in organic carbon content, Simmelkær, we observed a higher degree of ageing when treated with manure. Contrarily, sorption experiments showed less sorption to Simmelkær treated with manure than the untreated soil indicating that sorption processes are not the only mechanisms of ageing. The other topsoil low in organic carbon content, Ringe, showed no significant difference in ageing between the manure-treated and untreated soil. The present study illustrates that not simply the organic carbon content influences adsorption and ageing of atrazine in soil but the origin and composition of organic matter plays an important role.

  17. Effect of aging of chemicals in soil on their biodegradability and extractability

    SciTech Connect

    Hatzinger, P.B.; Alexander, M.

    1995-11-01

    A study was conducted to determine whether the time that a compound remains in a soil affects its biodegradability and the ease of its extraction. Phenanthrene and 4-nitrophenol were aged in sterilized loam and muck, and bacteria able to degrade the compounds were then added to the soils. increasingly smaller amounts of phenanthrene in the muck and 4-nitrophenol in both soils were mineralized with increasing duration of aging. Aging also increased the resistance of phenanthrene to biodegradation in nutrient-amended aquifer sand. The rate of miner- alization of the two compounds in both soils declined with increasing periods of aging. The amount of phenanthrene and 4-nitrophenol added to sterile soils that was recovered by butanol extraction declined with duration of aging, but subsequent Soxhlet extraction recovered phenanthrene from the loam but not the muck. The extents of mineralization of phenanthrene previously incubated for up to 27 days with soluble or insoluble organic matter from the muck were similar. Less aged than freshly added phenanthrene was biodegraded if aggregates in the muck were sonically disrupted. The data show that phenanthrene and 4-nitrophenol added to soil become increasingly more resistant with time to biodegradation and extraction.

  18. Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production.

    NASA Astrophysics Data System (ADS)

    Heitkötter, Julian; Marschner, Bernd

    2015-04-01

    Biochar is suggested for soil amelioration and carbon sequestration, based on its assumed role as the key factor for the long-term fertility of Terra preta soils. Several studies have shown that certain biochar properties can undergo changes through ageing processes, especially regarding charge characteristics. However, only a few studies determined the changes of different biochars under the same incubation conditions and in different soils. The objective of this study was to characterize the changes of pine chip (PC)- and corn digestate (CD)-derived biochars pyrolyzed at 400 or 600 °C during 100 days of laboratory incubation in a historical kiln soil and an adjacent control soil. Separation between soil and biochar was ensured by using mesh bags. Especially, changes in charge characteristics depended on initial biochar properties affected by feedstock and pyrolysis temperature and on soil properties affected by historic charcoal production. While the cation exchange capacity (CEC) markedly increased for both CD biochars during incubation, PC biochars showed no or only slight increases in CEC. Corresponding to the changes in CEC, ageing of biochars also increased the amount of acid functional groups with increases being in average about 2-fold higher in CD biochars than in PC biochars. Further and in contrast to other studies, the surface areas of biochars increased during ageing, likely due to ash leaching and degradation of tar residues. Changes in CEC and surface acidity of CD biochars were more pronounced after incubation in the control soil, while surface area increase was higher in the kiln soil. Since the two acidic forest soils used in this this study did not greatly differ in physical or chemical properties, the main process for inducing these differences in the buried biochar most likely is related to the differences in dissolved organic carbon (DOC). Although the kiln soil contained about 50% more soil organic carbon due to the presence of charcoal

  19. Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils.

    PubMed

    Christiansen, Karen S; Borggaard, Ole K; Holm, Peter E; Vijver, Martina G; Hauschild, Michael Z; Peijnenburg, Willie J G M

    2015-04-01

    Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87% of the pEC50(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

  20. Effects of Forest Age on Soil Fungal Community in a Northern Temperate Ecosystem.

    PubMed

    Zhiguang, Han; Xin, Sui; Mengsha, Li

    2016-09-01

    The polymorphisms of soil fungal rDNA Internal Transcribed Spacer regions were studied in Korean pine forests of various ages (10-100-year-old trees) by means of cloned libraries, and analyzed to determine the effects of the trees' developmental stage on soil fungal community structure. The obtained Shannon diversity index (H) and richness (S) indicated that the diversity of the soil fungal community increased significantly with the development of Korean pines (P < 0.05). In addition, cluster analysis (UPGMA) showed that the soil fungal community variety associated with differently aged Korean pines was higher than 50 %. The soil fungal community diversity correlated significantly with the N content and C/N ratio of the soil (P < 0.05). The results of this study indicate that the age of in Korean pine can affect soil fungal community by altering soil properties, which in turn could affect the nutrient cycling in the forest ecosystem. PMID:27407297

  1. Fate and lability of silver in soils: Effect of ageing

    EPA Science Inventory

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectrosco...

  2. Age calibration of carbonate rind thickness in late Pleistocene soils for surficial deposit age estimation, Southwest USA

    USGS Publications Warehouse

    Amoroso, L.

    2006-01-01

    Carbonate rinds have been used for cross-correlation of landforms as well as a quantitative indicator of soil age. Using the measured rind thickness of clasts found within a deposit, whose age has been independently determined, allows the construction of a calibrated surface-age proxy. Measurements were taken at sites within the Mojave Desert, the northwestern Sonoran Desert, the southern Great Basin, and the western Colorado Plateau. These sites are all within about 300 km of the intersection of the borders of the states of California, Arizona, and Nevada. In the study area, elevation varied from 200 to 1200 m, MAP was from 95 to 195 mm, and MAT was from 18.4?? to 23.3??. The calibrated proxy, while not accounting for the effects of parent material or climate on rind development, does show a strong correlation (R2 = 0.74, P < 0.05) between carbonate rind thickness and surface age for deposits of late to middle Pleistocene age. The calibrated chronosequence, rind thickness = 0.0889 + 0.0079 [surface age]), is in general valid over a large region of southwestern United States. This statistical relation suggests that parent material, climate, and elevation may not be as strong a control on carbonate accumulation as is age for younger soils.

  3. Application of vegetable oils in the treatment of polycyclic aromatic hydrocarbons-contaminated soils.

    PubMed

    Yap, C L; Gan, S; Ng, H K

    2010-05-15

    A brief review is conducted on the application of vegetable oils in the treatment of PAH-contaminated soils. Three main scopes of treatment strategies are discussed in this work including soil washing by oil, integrated oil-biological treatment and integrated oil-non-biological treatment. For each of these, the arguments supporting vegetable oil application, the applied treatment techniques and their efficiencies, associated factors, as well as the feasibility of the techniques are detailed. Additionally, oil regeneration, the environmental impacts of oil residues in soil and comparison with other commonly employed techniques are also discussed.

  4. Extraction agents for the removal of polycyclic aromatic hydrocarbons (PAHs) from soil in soil washing technologies.

    PubMed

    Lau, Ee Von; Gan, Suyin; Ng, Hoon Kiat; Poh, Phaik Eong

    2014-01-01

    Polycyclic aromatic hydrocarbons (PAHs) in soil have been recognised as a serious health and environmental issue due to their carcinogenic, mutagenic and teratogenic properties. One of the commonly employed soil remediation techniques to clean up such contamination is soil washing or solvent extraction. The main factor which governs the efficiency of this process is the solubility of PAHs in the extraction agent. Past field-scale soil washing treatments for PAH-contaminated soil have mainly employed organic solvents or water which is either toxic and costly or inefficient in removing higher molecular weight PAHs. Thus, the present article aims to provide a review and discussion of the alternative extraction agents that have been studied, including surfactants, biosurfactants, microemulsions, natural surfactants, cyclodextrins, vegetable oil and solution with solid phase particles. These extraction agents have been found to remove PAHs from soil at percentages ranging from 47 to 100% for various PAHs. PMID:24100092

  5. Effects of cultivation ages and modes on microbial diversity in the rhizosphere soil of Panax ginseng

    PubMed Central

    Xiao, Chunping; Yang, Limin; Zhang, Lianxue; Liu, Cuijing; Han, Mei

    2015-01-01

    Background Panax ginseng cannot be cultivated on the same land consecutively for an extended period, and the underlying mechanism regarding microorganisms is still being explored. Methods Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) and BIOLOG methods were used to evaluate the microbial genetic and functional diversity associated with the P. ginseng rhizosphere soil in various cultivation ages and modes. Results The analysis of microbial diversity using PCR-DGGE showed that microbial communities were significantly variable in composition, of which six bacterial phyla and seven fungal classes were detected in P. ginseng soil. Among them, Proteobacteria and Hypocreales dominated. Fusarium oxysporum, a soilborne pathogen, was found in all P. ginseng soil samples except R0. The results from functional diversity suggested that the microbial metabolic diversity of fallow soil abandoned in 2003 was the maximum and transplanted soil was higher than direct-seeding soil and the forest soil uncultivated P. ginseng, whereas the increase in cultivation ages in the same mode led to decreases in microbial diversity in P. ginseng soil. Carbohydrates, amino acids, and polymers were the main carbon sources utilized. Furthermore, the microbial diversity index and multivariate comparisons indicated that the augmentation of P. ginseng cultivation ages resulted in decreased bacterial diversity and increased fungal diversity, whereas microbial diversity was improved strikingly in transplanted soil and fallow soil abandoned for at least one decade. Conclusion The key factors for discontinuous P. ginseng cultivation were the lack of balance in rhizosphere microbial communities and the outbreak of soilborne diseases caused by the accumulation of its root exudates. PMID:26843819

  6. Nitrogen dynamics in arctic tundra soils of varying age: differential responses to fertilization and warming.

    PubMed

    Yano, Yuriko; Shaver, Gaius R; Rastetter, Edward B; Giblin, Anne E; Laundre, James A

    2013-12-01

    In the foothills of the Brooks Range, Alaska, different glaciation histories have created landscapes with varying soil age. Productivity of most of these landscapes is generally N limited, but varies widely, as do plant species composition and soil properties (e.g., pH). We hypothesized that the projected changes in productivity and vegetation composition under a warmer climate might be mediated through differential changes in N availability across soil age. We compared readily available [water-soluble NH4 (+), NO3 (-), and amino acids (AA)], moderately available (soluble proteins), hydrolyzable, and total N pools across three tussock-tundra landscapes with soil ages ranging from 11.5k to 300k years. The effects of fertilization and warming on these N pools were also compared for the two younger sites. Readily available N was highest at the oldest site, and AA accounted for 80-89 % of this N. At the youngest site, inorganic N constituted the majority (80-97 %) of total readily available N. This variation reflected the large differences in plant functional group composition and soil chemical properties. Long-term (8-16 years) fertilization increased the soluble inorganic N by 20- to 100-fold at the intermediate-age site, but only by twofold to threefold at the youngest site. Warming caused small and inconsistent changes in the soil C:N ratio and AA, but only in soils beneath Eriophorum vaginatum, the dominant tussock-forming sedge. These differential responses suggest that the ecological consequences of warmer climates on these tundra ecosystems are more complex than simply elevated N-mineralization rates, and that the responses of landscapes might be impacted by soil age, or time since deglaciation.

  7. [Ecological stoichiometry of soil carbon, nitrogen and phosphorus within soil aggregates in tea plantations with different ages].

    PubMed

    Li, Wei; Zheng, Zi-cheng; Li, Ting-xuan

    2015-01-01

    This study selected 4 tea plantations with different ages (12-15, 20-22, 30-33 and >50 year-old) located in Ya' an, Sichuan Province, China to investigate the distribution patterns of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) , and to examine the ecological stoichiometric characteristics of C, N and P within soil aggregates. The results showed that the coefficients of variation of SOC, TN and TP were 17.5%, 16.3% and 9.4%, respectively in the 0-20 cm soil layer and were 24.0%, 21.0% and 9.2%, respectively in the 20-40 cm soil layer. The spatial variation of TP was lower than that of SOC and TN but there were significant positive correlations among them. SOC and TN were distributed in the small-size aggregates and both of them had the greatest values in the >50 year-old tea plantation, however, the distribution of TP was relatively uniform among aggregates and ages. The coefficients of variation of C/N, C/P, and N/P were 9.4%, 14.0% and 14.9%, respectively in the 0-20 cm soil layer and were 7.4%, 24.9% and 21.8%, respectively in the 20-40 cm soil layer. Variation of C/N was lower than that of C/P and N/P. Averaged C/P and N/P values in the small-size aggregates were higher than in aggregates of other sizes, and the maximum values were in the >50 year-old plantation. C/N, C/P and N/P had good indication for soil organic carbon storage.

  8. Prediction of radionuclide aging in soils from the Chernobyl and Mediterranean areas.

    PubMed

    Roig, M; Vidal, M; Rauret, G; Rigol, A

    2007-01-01

    The aging of soil-pollutant interaction, which may lead to an increase in pollutant fixation, is the main driving force in the natural attenuation of contaminated soils. Here a test was evaluated to predict the aging of radiostrontium and radiocesium in soils from the Chernobyl and Mediterranean areas. After contamination, soils were maintained at various temperatures for up to 12 mo, with or without drying-wetting (DW) cycles. Changes in the quantity of radionuclide reversibly sorbed over time were monitored using an extraction test (1 mol L(-1) NH(4)Cl; 10 mL g(-1); 16 h). The fixed fraction could not be predicted from soil properties controlling the sorption step. Aging was not as relevant for Sr as for Cs. The time elapsed since contamination was the main factor responsible for the slight (up to 1.3-fold) decreases in Sr extraction yields. The additional effect of DW cycles was negligible. Instead, all factors accelerated Cs aging due to the enhancement of Cs trapping by clay interlayer collapse, with up to 20-fold increases in Cs fixation. The DW cycles also caused secondary effects on the Cs-specific sorption pool, which were beneficial or detrimental depending on the soil type. Extraction yields from laboratory aged samples agreed with those from field samples taken a few years after the Chernobyl accident. These results confirm the prediction capacity of the laboratory test and its usefulness in risk assessment exercises and in the design of intervention actions, particularly because neither fixation nor aging were related to the soil properties, such as clay content. PMID:17526873

  9. Changes of deep soil desiccation with plant growth age in the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Y. Q.; Shao, M. A.; Liu, Z. P.; Zhang, C. C.

    2012-10-01

    Negative water balance in soil can lead to soil desiccation and subsequent the formation of a dried soil layer (DSL). Essential progress on DSL temporal change has been hampered by difficulty in collecting deep soil water samples (i.e. > 1000 cm), which are necessary to quantify the real extent of DSL. We collected soil samples up to a depth of 1800 cm and investigated the evolution of soil water content (SWC) and DSL under three vegetation types (C. korshinskii, R. pseudoacacia, apple) in three zones (Ansai, Luochuan, and Changwu) of the Chinese Loess Plateau. As plant growth age increased, SWC, available soil water (ASW), SWC within DSL (DSL-SWC), and quantity of water deficit for DSL (DSL-QWD) showed similar change trends of decreasing at first and then increasing, whereas DSL thickness (DSLT) showed an increasing trend over time. A turning point in soil water change was found for the three vegetation types. In Changwu zone, the turning point, both in and out of DSL, was corresponded to the 17-year-old apple orchard. The period from 9 to 17 yr was vital to maintain the buffering function of deep soil water pool and to avoid the deterioration of soil desiccation because the highest mean decline velocity of ASW and the maximum mean forming velocity of DSLT were 165 mm yr-1 and 168 cm yr-1, respectively. Significant correlations were found between DSLT and growth age and root depth, and between DSL-QWD and root depth, whereas mean DSL-SWC had no significant correlation with either growth year or root depth. Soil water condition was highly dependent on the growth year of the plants. This information provides pertinent reference for water resource management in the Chinese Loess Plateau and possibly in other water-limited regions in the world.

  10. Podzol development in S Norway - a soil chronosequence of 31 pedons covering soil ages from 85 to 9650 years

    NASA Astrophysics Data System (ADS)

    Sauer, Daniela; Svendgård-Stokke, Siri; Sperstad, Ragnhild; Sørensen, Rolf; Fuchs, Markus; Gebers, Henrik; Schülli-Maurer, Isabelle

    2013-04-01

    The Oslofjord region in SE-Norway has undergone steady glacio-isostatic uplift all over the Holocene. Hence, in the coastal areas land surface age continuously increases with elevation, providing suitable conditions for studying soil development with time. A chronosequence of soils on beach sand and sandy terraces of the Lågen River, showing progressive podzolization with soil age, was studied on the western side of the Oslofjord. 31 pedons with soil ages ranging from 85 years (0.25 m a. s. l.) to ca. 9650 years (62 m a. s. l.) were described and are currently analysed. Soil ages were estimated by relating elevations of the sites to a Holocene relative sea level curve based on twelve AMS 14C-dates of gyttja from the isolation contact (marine / fresh water boundary) and six marine macrofossil 14C-dates (Sørensen et al., 2012). The climate in the study area is comparatively mild, with mean annual temperatures ranging from 5.3°C (Ramnes) to 6.3°C (Sandefjord, Larvik) and a mean annual precipitation of 909 mm (Sandefjord) - 1150 mm (Stokke). The vegetation consists predominantly of mixed forest. In this soil chronosequence, soil organic matter (SOM) accumulation in the A horizons reaches a steady state in less than 2300 years, while SOM in the B horizons continues to accumulate. Soil pH (in water) drops from pH 6.9 in the recent beach sand to pH 4.6 within about 4500 years and stays constant thereafter, which is attributed to sesquioxide buffering. Base saturation shows an exponential decrease with time. Progressive weathering is reflected by increasing Fed and Ald contents, and proceeding podzolization by increasing amounts of pyrophophate- and oxalate-soluble Fe and Al with soil age. Increases of most Fe and Al fractions can be best described by exponential models. Micromorphological analysis reveals accumulation of cloudy, iron-rich, reddish fine material in the Bs horizons that proceeds with soil age, leading to chitonic c/f-related distribution in the Bs

  11. Soil data from different-age Picea mariana stands near Delta Junction, Alaska

    USGS Publications Warehouse

    Manies, Kristen L.; Harden, Jennifer W.

    2011-01-01

    One objective of the U.S. Geological Survey\\'s Fate of Carbon in Alaskan Landscapes (FOCAL) project is to study the effects of fire and soil drainage on soil carbon storage in boreal forests. For this purpose, the project has measured the soil carbon content in several chronosequences (time since disturbance) of various soil-drainage types. One such chronosequence near Delta Junction, Alaska was initially studied in 2000 and 2001. Additional sites in the Delta Junction area were sampled in 2006 to expand the number of stand ages represented in the chronosequence. This report describes these additional sites, as well as the procedures used to describe, sample, and analyze the soils. We also present data tables containing, but not limited to, field descriptions, bulk density, moisture content, and total carbon (C) and total nitrogen (N) content.

  12. Effect of orchard age on soil nitrogen transformation in subtropical China and implications.

    PubMed

    Zhang, Yushu; Zhang, Jinbo; Zhu, Tongbin; Müller, Christoph; Cai, Zucong

    2015-08-01

    A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a (15)N tracing study was carried out to investigate the effects of converting woodland to orchard, and orchard age on the gross rates of N transformation occurring simultaneously in subtropical soils in Eastern China. The results showed that inorganic N supply rate was remained constant with soil organic C and N contents increased after converting woodland into citrus orchard and with increasing orchard age. This phenomenon was most probably due to the increase in the turnover time of recalcitrant organic-N, which increased with decreasing soil pH along with increasing orchard age significantly. The amoA gene copy numbers of both archaeal and bacterial were stimulated by orchard planting and increased with increasing orchard age. The nitrification capacity (defined as the ratio of gross rate of nitrification to total gross rate of mineralization) increased following the Michaelis-Menten equation, sharply in the first 10 years after woodland conversion to orchard, and increased continuously but much more slowly till 30 years. Due to the increase in nitrification capacity and unchanged NO3(-) consumption, the dominance of ammonium in inorganic N in woodland soil was shifted to nitrate dominance in orchard soils. These results indicated that the risk of NO3(-) loss was expected to increase and the amount of N needed from fertilizers for fruit growth did not change although soil organic N accumulated with orchard age.

  13. Release of aged 14C-atrazine residues from soil facilitated by dry-wet cycles

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Yu, K.; Koeppchen, S.; Burauel, P.

    2012-04-01

    Intermittent dry-wet cycles may have an important effect on soil structure and aged pesticide residues release (1). A laboratory study was conducted to assess the maximum potential of water extractable aged atrazine residues influenced by soil drying and wetting. The used soil was obtained from an outdoor lysimeter (gleyic cambisol; Corg: 1.45%), containing environmentally aged (22 years) 14C-atrazine residues. For the experiment, soil from 0-10 cm depth was used since most residual 14C activity was previously found in this layer (2,3). Triplicate soil samples with a residual water content of approx. 8% were either dried (45° C) prior water addition or directly mixed with distilled water (soil+water: 1+2, w:w). The samples were shaken (150 rmp, 60 min, at 21° C), centrifuged (approx. 2000 g), and the supernatants were filtered. Water-extracted residual 14C activity was detected via liquid scintillation counter. The total water-extracted 14C activity (the amount of residual 14C activity in a sample equals 100%) was significantly higher (p

  14. Changes in arsenic fractionation, bioaccessibility and speciation in organo-arsenical pesticide amended soils as a function of soil aging.

    PubMed

    Quazi, Shahida; Sarkar, Dibyendu; Datta, Rupali

    2011-09-01

    Although organoarsenical pesticides are being phased out, sites with high concentrations of organic arsenical residues still exist due to the long-term application of these pesticides. The biotic and abiotic speciation of dimethylarsinic acid (DMA) can result in the formation of inorganic arsenic (As) species. Oxidation state, retention, and thereby persistence, varies according to temporal changes, influencing the availability and toxicity of contaminants. The current greenhouse study aimed at evaluating temporal changes in the oxidation state of As, geochemical partitioning, and bioaccessibility. Four soils with varying physiochemical properties were contaminated with DMA at two concentrations (675 and 1,500 mg kg(-1) of As). Rice plants were grown for a 6 months period, following which, the soils were allowed to age. The operationally defined forms of As and its bioaccessibility was analyzed at 0, 6 months, 1 year, and 3 years. Changes in oxidation state of As were evaluated immediately after spiking and after 3 years of soil-pesticide equilibration. Results show that geochemical partitioning of As was affected significantly (P<0.05) by soil type, loading rates, and equilibration time. Arsenic was bound mainly to the poorly-crystalline Fe/Al-oxyhydroxides in the soil. However, these interactions did not affect As bioaccessibility, presumably due to the dissolution of the bound fractions of As in the acidic stomach. While 74-94% of the total bioaccessible As was transformed to As(V), 4-19% was transformed to the more toxic As(III). This study indicates that although aging affected the geochemical partitioning of As in the soil, bioaccesibility was controlled by the gastric pH. PMID:21722940

  15. Using synthetic models to simulate aging of Cu contamination in soils.

    PubMed

    Proffit, S; Marin, B; Cances, B; Ponthieu, M; Sayen, S; Guillon, E

    2015-05-01

    The Bureau Commun de Référence (BCR) sequential extraction scheme and micro-synchrotron-based X-ray fluorescence (μ-SXRF) analysis were used to determine the Cu fractionation in a calcareous vineyard soil and a synthetic soil (mixture of seven constituents: calcite, birnessite, ferrihydrite, goethite, lignocellulosic residue, kaolinite, and quartz) at different Cu contamination rates (190, 1270, and 6350 mg kg(-1) of Cu) and aging times (1, 30, 92, and 181 days). The Cu distribution in the spiked vineyard and synthetic soils was different from the original vineyard one and was influenced by the loading level. The newly added Cu was preferentially present in the acid soluble fraction. Aging of the contaminated vineyard and synthetic soils during 6 months led to the redistribution of Cu from the weakly bound acid soluble fraction to the strongly bound reducible one. The evolution with time could satisfactorily be simulated by the Elovich diffusion model for the synthetic soils. It was less significant as less marked in the contaminated vineyard soil than in the synthetic one, even though the trends observed in both were similar. This study supported the hypothesis that "simple" synthetic models could be used to approach the Cu fractionation and its evolution with time in vineyard soils.

  16. A statistical method for estimating rates of soil development and ages of geologic deposits: A design for soil-chronosequence studies

    USGS Publications Warehouse

    Switzer, P.; Harden, J.W.; Mark, R.K.

    1988-01-01

    A statistical method for estimating rates of soil development in a given region based on calibration from a series of dated soils is used to estimate ages of soils in the same region that are not dated directly. The method is designed specifically to account for sampling procedures and uncertainties that are inherent in soil studies. Soil variation and measurement error, uncertainties in calibration dates and their relation to the age of the soil, and the limited number of dated soils are all considered. Maximum likelihood (ML) is employed to estimate a parametric linear calibration curve, relating soil development to time or age on suitably transformed scales. Soil variation on a geomorphic surface of a certain age is characterized by replicate sampling of soils on each surface; such variation is assumed to have a Gaussian distribution. The age of a geomorphic surface is described by older and younger bounds. This technique allows age uncertainty to be characterized by either a Gaussian distribution or by a triangular distribution using minimum, best-estimate, and maximum ages. The calibration curve is taken to be linear after suitable (in certain cases logarithmic) transformations, if required, of the soil parameter and age variables. Soil variability, measurement error, and departures from linearity are described in a combined fashion using Gaussian distributions with variances particular to each sampled geomorphic surface and the number of sample replicates. Uncertainty in age of a geomorphic surface used for calibration is described using three parameters by one of two methods. In the first method, upper and lower ages are specified together with a coverage probability; this specification is converted to a Gaussian distribution with the appropriate mean and variance. In the second method, "absolute" older and younger ages are specified together with a most probable age; this specification is converted to an asymmetric triangular distribution with mode at the

  17. Effects of Forest Age on Soil Autotrophic and Heterotrophic Respiration Differ between Evergreen and Deciduous Forests

    PubMed Central

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Yang, Yuanhe; Zeng, Hui

    2013-01-01

    We examined the effects of forest stand age on soil respiration (SR) including the heterotrophic respiration (HR) and autotrophic respiration (AR) of two forest types. We measured soil respiration and partitioned the HR and AR components across three age classes ∼15, ∼25, and ∼35-year-old Pinus sylvestris var. mongolica (Mongolia pine) and Larix principis-rupprechtii (larch) in a forest-steppe ecotone, northern China (June 2006 to October 2009). We analyzed the relationship between seasonal dynamics of SR, HR, AR and soil temperature (ST), soil water content (SWC) and normalized difference vegetation index (NDVI, a plant greenness and net primary productivity indicator). Our results showed that ST and SWC were driving factors for the seasonal dynamics of SR rather than plant greenness, irrespective of stand age and forest type. For ∼15-year-old stands, the seasonal dynamics of both AR and HR were dependent on ST. Higher Q10 of HR compared with AR occurred in larch. However, in Mongolia pine a similar Q10 occurred between HR and AR. With stand age, Q10 of both HR and AR increased in larch. For Mongolia pine, Q10 of HR increased with stand age, but AR showed no significant relationship with ST. As stand age increased, HR was correlated with SWC in Mongolia pine, but for larch AR correlated with SWC. The dependence of AR on NDVI occurred in ∼35-year-old Mongolia pine. Our study demonstrated the importance of separating autotrophic and heterotrophic respiration components of SR when stimulating the response of soil carbon efflux to environmental changes. When estimating the response of autotrophic and heterotrophic respiration to environmental changes, the effect of forest type on age-related trends is required. PMID:24282560

  18. Effects of forest age on soil autotrophic and heterotrophic respiration differ between evergreen and deciduous forests.

    PubMed

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Yang, Yuanhe; Zeng, Hui

    2013-01-01

    We examined the effects of forest stand age on soil respiration (SR) including the heterotrophic respiration (HR) and autotrophic respiration (AR) of two forest types. We measured soil respiration and partitioned the HR and AR components across three age classes ~15, ~25, and ~35-year-old Pinus sylvestris var. mongolica (Mongolia pine) and Larix principis-rupprechtii (larch) in a forest-steppe ecotone, northern China (June 2006 to October 2009). We analyzed the relationship between seasonal dynamics of SR, HR, AR and soil temperature (ST), soil water content (SWC) and normalized difference vegetation index (NDVI, a plant greenness and net primary productivity indicator). Our results showed that ST and SWC were driving factors for the seasonal dynamics of SR rather than plant greenness, irrespective of stand age and forest type. For ~15-year-old stands, the seasonal dynamics of both AR and HR were dependent on ST. Higher Q10 of HR compared with AR occurred in larch. However, in Mongolia pine a similar Q10 occurred between HR and AR. With stand age, Q10 of both HR and AR increased in larch. For Mongolia pine, Q10 of HR increased with stand age, but AR showed no significant relationship with ST. As stand age increased, HR was correlated with SWC in Mongolia pine, but for larch AR correlated with SWC. The dependence of AR on NDVI occurred in ~35-year-old Mongolia pine. Our study demonstrated the importance of separating autotrophic and heterotrophic respiration components of SR when stimulating the response of soil carbon efflux to environmental changes. When estimating the response of autotrophic and heterotrophic respiration to environmental changes, the effect of forest type on age-related trends is required.

  19. Controlling Factors of Soil CO2 Efflux in Pinus yunnanensis across Different Stand Ages

    PubMed Central

    Wang, Shaojun; Zhao, Jixia; Chen, Qibo

    2015-01-01

    The characteristics of soil respiration (Rs) across different stand ages have not been well investigated. In this study, we identified temporal variation of Rs and its driving factors under three nature forest stands (e.g. 15-yr-old, 30-yr-old, and 45-yr-old) of Pinus yunnanensis in the Plateau of Mid-Yunnan, China. No consistent tendency was found on the change of Rs with the stand ages. Rs was ranked in the order of 30-yr-old > 45-yr-old >15-yr-old. Rs in 15-yr-old stand was the most sensitive to soil temperature (Ts) among the three sites. However, Ts only explained 30-40% of the seasonal dynamics of Rs at the site. Soil water content (Sw) was the major controlling factor of temporal variation at the three sites. Sw explained 88-93% of seasonal variations of Rs in the 30-yr-old stand, and 63.7-72.7% in the 15-yr-old and 79.1-79.6% in the 45-yr-old stands. In addition, we found that pH, available nitrogen (AN), C/N and total phosphorus (TP) contributed significantly to the seasonal variation of Rs. Sw was significantly related with pH, total nitrogen (TN), AN and TP, suggesting that Sw can affect Rs through improving soil acid-base property and soil texture, and increasing availability of soil nutrient. The results indicated that besides soil water, soil properties (e. g. pH, AN, C/N and TP) were also the important in controlling the temporal variations of Rs across different stand ages in the nature forestry. PMID:25996943

  20. Influence of soil properties and aging on the toxicity of copper on compost worm and barley.

    PubMed

    Daoust, Catherine M; Bastien, Christian; Deschênes, Louise

    2006-01-01

    Influence of soil properties and aging on Cu partitioning and toxicity was assessed on 10 artificial soils constituted using a statistical design considering pH (5.5 and 7.5), organic matter (1-30% [w/w]), and clay content (5-35% [w/w]). Total Cu as well as water-, CaCl2-, and diethylene triamine pentaacetic acid (DTPA)-extracted Cu fractions were determined for each soil mixture. Ecotoxic effect was assessed by determining growth inhibition of barley (Hordeum vulgare L.) and compost worm (Eisenia fetida) mortality. Analyses were repeated after a 16-wk aging period of the soils at pH 7.5 (8 x 2-wk wetting and drying cycle). Results indicated that pH was the main factor controlling Cu partitioning, ahead of organic matter and clay content. Calcium chloride (0.5 M)-extracted Cu fractions showed the best correlation with toxic responses (r = 0.55-0.66; p < 0.05), while total and DTPA-extracted Cu concentrations could not explain differences in toxicity. Direct regressions between toxicity and soil properties (pH, organic matter, and clay content) provided better explanation of variance: r2= 0.50 (p = 0.00006) for compost worm mortality, r2= 0.77 (p < 0.00001) for barley shoot inhibition, and r2= 0.92 (p < 0.00001) for barley root inhibition. Copper toxicity was mainly influenced by pH and, to a lesser extent, by organic matter and clay content. Aging in organic soils revealed a slight reduction in ecotoxicity while an increase was observed in soils with low organic matter content. Further investigation using longer aging periods would be necessary to assess the significance of this observation. PMID:16510700

  1. Effects, transfer, and fate of RDX from aged soil in plants and worms.

    PubMed

    Best, E P H; Geter, K N; Tatem, H E; Lane, B K

    2006-01-01

    The objectives of this study were to provide data that can be used to predict exposure-based effects of RDX in aged soil on multiple endpoint organisms representing two trophic levels. These data can be used for defining criteria or reference values for environmental management and conducting specific risk assessment. Dose-response experiments formed the basis for the evaluation of toxic effects and transfer of contaminants from soil into two trophic levels. Long-term exposure tests were conducted to evaluate chronic, sublethal, toxicity and transfer of aged soil-based explosives, with RDX as main contaminant. In these tests, plants were exposed for 55 days in the greenhouse, biomass was determined and residues of explosives parent compounds and RDX metabolites were analyzed using HPLC techniques. Worms were exposed for 28 days (Eisenia fetida) and 42 days (Enchytraeus crypticus) in the laboratory, biomass and number were determined, and tissues were analyzed for explosives compounds. The plants tolerated concentrations up to 1,540 mg RDX kg(-1) soil-DW. Biomass of Lolium perenne was not significantly related to soil-RDX concentration, while biomass of Medicago sativa significantly increased. No screening benchmark for RDX in soil for plants was calculated, since concentrations up to 1,540 mg kg(-1) soil failed to reduce biomass by 20% as required for a LOEC. RDX, RDX-metabolite MNX, and accompanying HMX concentrations in plants were significantly related to concentrations in soil after 55 days of exposure (RDX: R(2) = 0.77-0.89; MNX R(2) = 0.53-0.77; HMX: R(2) = 0.67-0.71). The average bioconcentration factors (BCF) were for RDX 17 in L. perenne and 37 in M. sativa, and for HMX 2 in L. perenne and 44 in M. sativa. The worms also tolerated concentrations up to 1,540 mg RDX kg(-1) soil-DW. Biomass of E. fetida adults decreased with soil-RDX concentration, and a LOEC of 1,253 mg kg(-1) soil-DW was estimated. RDX concentrations in E. fetida were significantly related

  2. Mutagenicity of an aged gasworks soil during bioslurry treatment

    PubMed Central

    Lemieux, Christine L; Lynes, Krista D; White, Paul A; Lundstedt, Staffan; Öberg, Lars; Lambert, Iain B

    2009-01-01

    This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) during pilot-scale bioslurry remediation. Slurry samples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic fractions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenicity using the Salmonella mutation assay. Most samples elicited a significant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; however, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of the fractions across treatment time and metabolic activation conditions suggests a pattern of formation and transformation of mutagenic compounds that may include a wide range of PAH derivatives such as aromatic amines, oxygenated PAHs, and S-heterocyclic compounds. The prior chemical analyses documented the formation of oxygenated PAHs during the treatment (e.g., 4-oxapyrene-5-one), and the mutagenicity analyses showed high corresponding activity in the semipolar fraction with and without metabolic activation. However, it could not be verified that these specific compounds were the underlying cause of the observed changes in mutagenic activity. The results highlight the need for concurrent chemical and toxicological profiling of contaminated sites undergoing remediation to ensure elimination of priority contaminants as well as a reduction in toxicological hazard. Moreover, the results imply that remediation efficacy and utility be evaluated using both chemical and toxicological metrics. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. PMID:19274766

  3. Mutagenicity of an aged gasworks soil during bioslurry treatment.

    PubMed

    Lemieux, Christine L; Lynes, Krista D; White, Paul A; Lundstedt, Staffan; Oberg, Lars; Lambert, Iain B

    2009-06-01

    This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) during pilot-scale bioslurry remediation. Slurry samples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic fractions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenicity using the Salmonella mutation assay. Most samples elicited a significant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; however, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of the fractions across treatment time and metabolic activation conditions suggests a pattern of formation and transformation of mutagenic compounds that may include a wide range of PAH derivatives such as aromatic amines, oxygenated PAHs, and S-heterocyclic compounds. The prior chemical analyses documented the formation of oxygenated PAHs during the treatment (e.g., 4-oxapyrene-5-one), and the mutagenicity analyses showed high corresponding activity in the semipolar fraction with and without metabolic activation. However, it could not be verified that these specific compounds were the underlying cause of the observed changes in mutagenic activity. The results highlight the need for concurrent chemical and toxicological profiling of contaminated sites undergoing remediation to ensure elimination of priority contaminants as well as a reduction in toxicological hazard. Moreover, the results imply that remediation efficacy and utility be evaluated using both chemical and toxicological metrics. PMID:19274766

  4. Phytotoxicity of nitroaromatic energetic compounds freshly amended or weathered and aged in sandy loam soil.

    PubMed

    Rocheleau, Sylvie; Kuperman, Roman G; Martel, Majorie; Paquet, Louise; Bardai, Ghalib; Wong, Stephen; Sarrazin, Manon; Dodard, Sabine; Gong, Ping; Hawari, Jalal; Checkai, Ronald T; Sunahara, Geoffrey I

    2006-01-01

    The toxicities of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to terrestrial plants alfalfa (Medicago sativa L.), Japanese millet (Echinochloa crusgalli L.), and perennial ryegrass (Lolium perenne L.) were determined in Sassafras sandy loam soil using seedling emergence, fresh shoot, and dry mass measurement endpoints. A 13-week weathering and aging of energetic materials in soils, which included wetting and drying cycles, and exposure to sunlight of individual soil treatments, was incorporated into the study design to better reflect the soil exposure conditions in the field than toxicity determinations in freshly amended soils. Definitive toxicity tests showed that dinitrotoluenes were more phytotoxic for all plant species in freshly amended treatments based on EC20 values for dry shoot ranging from 3 to 24mgkg(-1) compared with values for TNB or TNT ranging from 43 to 62mgkg(-1). Weathering and aging of energetic materials (EMs) in soil significantly decreased the toxicity of TNT, TNB or 2,6-DNT to Japanese millet or ryegrass based on seedling emergence, but significantly increased the toxicity of all four EMs to all three plant species based on shoot growth. Exposure of the three plant species to relatively low concentrations of the four compounds initially stimulated plant growth before the onset of inhibition at greater concentrations (hormesis).

  5. Understanding the solid phase chemical fractionation of uranium in soil and effect of ageing.

    PubMed

    Rout, Sabyasachi; Kumar, Ajay; Ravi, P M; Tripathi, R M

    2016-11-01

    The aim of the present work is to understand the solid phase chemical fractionation of Uranium (U) in soil and the mechanism involved. This study integrated batch experiments of U(VI) adsorption to soil, study of U in different soil fractions, ageing impact on fractionation of U and spectroscopic investigation of adsorbed U(VI) using X-ray Photoelectron Spectroscopy (XPS). For the study three soils, pedogenically different (S1: Igneous, S2: Sedimentary and S3: Metamorphic) were amended with U(VI) and chemical fractionation of U was studied by sequential extraction after an interval of one month and 12 months. It was found that there occurs a significant rearrangement of U in different fractions with ageing and no correlation was observed between the U content in different fractions and the adsorbents of respective fractions such as soil organic matter (SOM), Fe/Mn oxides (hydroxides) carbonates, soil cation exchange capacity (CEC). XPS study revealed that surface enrichment of U mainly governed by the carbonate minerals and SOM, whereas bulk concentration was controlled by the oxides (hydroxides) of Si and Al. Occlusion of U-Fe-oxides (hydroxides) on silica was identified as an important mechanism for bulk enrichment (Increase in residual fraction) and depletion of U concentration in reducible fraction.

  6. Effect of aging on bioaccessibility of arsenic and lead in soils.

    PubMed

    Liang, Shuang; Guan, Dong-Xing; Li, Jie; Zhou, Chun-Yang; Luo, Jun; Ma, Lena Q

    2016-05-01

    The effect of aging on the bioaccessibility of As and Pb in three soils spiked with As (40 or 400 mg kg(-1)), Pb (150 or 1500 mg kg(-1)) or As + Pb (40 mg kg(-1) As and 150 mg kg(-1) Pb) were investigated using the physiologically based extraction test (PBET). Prolonged aging in soils resulted in a decrease in As/Pb bioaccessibility, especially within the first month. After 76 weeks, As/Pb bioaccessibility in soils decreased to a stable level, with 48-84% and 8-34% for bioaccessible As and Pb respectively in the intestinal phase, illustrating that As in spiked soils was much more bioaccessible than Pb. Correlation analysis between sequential extraction data and PBET results showed that the non-specifically sorbed As contributed the most to bioaccessible As, while Pb bound with carbonates and exchangeable fractions were the source for bioaccessible Pb. For future work, minerals containing As and/or Pb instead of their soluble salts can be added to uncontaminated soils to better simulate the natural aging processes. PMID:26930247

  7. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) a...

  8. Bioremediation trial on aged PCB-polluted soils--a bench study in Iceland.

    PubMed

    Lehtinen, Taru; Mikkonen, Anu; Sigfusson, Bergur; Ólafsdóttir, Kristín; Ragnarsdóttir, Kristín Vala; Guicharnaud, Rannveig

    2014-02-01

    Polychlorinated biphenyls (PCBs) pose a threat to the environment due to their high adsorption capacity to soil organic matter, stability and low reactivity, low water solubility, toxicity and ability to bioaccumulate. With Icelandic soils, research on contamination issues has been very limited and no data has been reported either on PCB degradation potential or rate. The goals of this research were to assess the bioavailability of aged PCBs in the soils of the old North Atlantic Treaty Organization facility in Keflavík, Iceland and to find the best biostimulation method to decrease the pollution. The effectiveness of different biostimulation additives (N fertiliser, white clover and pine needles) at different temperatures (10 and 30 °C) and oxygen levels (aerobic and anaerobic) were tested. PCB bioavailability to soil fauna was assessed with earthworms (Eisenia foetida). PCBs were bioavailable to earthworms (bioaccumulation factor 0.89 and 0.82 for earthworms in 12.5 ppm PCB soil and in 25 ppm PCB soil, respectively), with less chlorinated congeners showing higher bioaccumulation factors than highly chlorinated congeners. Biostimulation with pine needles at 10 °C under aerobic conditions resulted in nearly 38 % degradation of total PCBs after 2 months of incubation. Detection of the aerobic PCB degrading bphA gene supports the indigenous capability of the soils to aerobically degrade PCBs. Further research on field scale biostimulation trials with pine needles in cold environments is recommended in order to optimise the method for onsite remediation.

  9. [Bacteria community in different aged Coptis chinensis planting soil revealed by PCR-DGGE analysis].

    PubMed

    Tan, Yuan; Chen, Qiang; Liu, Han-jun; Song, San-duo; Yu, Xiu-mei; Dong, Zhen-huan; Tang, Xue; Zhong, Yu-zhou

    2015-08-01

    In order to reveal the cause of disease occurred in the process of Coptis chinensis growth, this paper studied the bacterial species diversity index of different aged rhizospheric and non-rhizospheric soil planting normal or sick C. chinensis by using PCR-DGGE technique. The representative DGGE bands were chosen to be cloned, and sequenced, the phylogeny were constructed. The results showed that the bacterial communities were very different between the normal and diseased soil samples of C. chinensis, and the diversity index (H) of diseased soil samples were higher than that of normal soil samples. Sequencing analysis of representative cloned DGGE bands showed that the unculturable bacteria were the dominant groups, and bacteria belonged to genus Bacillus, Acidovorax, Acinetobacter, uncultured Kluyvera, and uncultured Comamonas were also existing, but the reported plant pathogenic bacteria were not found in the C. chinensis planting soil. The density and brightness of clone band d in diseased soil samples was higher than that in normal soil sample, and sequencing analysis showed that it belonged to genus Acidovorax. Obviously, during the process of C. chinensis growth, the rhizospheric bacteria population changed, and the quantity of bacteria belong Acidovorax increased, which probably resulted in the disease occurred during C. chinensis growth.

  10. Rates of Litter Decomposition and Soil Respiration in Relation to Soil Temperature and Water in Different-Aged Pinus massoniana Forests in the Three Gorges Reservoir Area, China

    PubMed Central

    Zeng, Lixiong; Huang, Zhilin; Lei, Jingpin; Zhou, Benzhi; Li, Maihe

    2014-01-01

    To better understand the soil carbon dynamics and cycling in terrestrial ecosystems in response to environmental changes, we studied soil respiration, litter decomposition, and their relations to soil temperature and soil water content for 18-months (Aug. 2010–Jan. 2012) in three different-aged Pinus massoniana forests in the Three Gorges Reservoir Area, China. Across the experimental period, the mean total soil respiration and litter respiration were 1.94 and 0.81, 2.00 and 0.60, 2.19 and 0.71 µmol CO2 m−2 s−1, and the litter dry mass remaining was 57.6%, 56.2% and 61.3% in the 20-, 30-, and 46-year-old forests, respectively. We found that the temporal variations of soil respiration and litter decomposition rates can be well explained by soil temperature at 5 cm depth. Both the total soil respiration and litter respiration were significantly positively correlated with the litter decomposition rates. The mean contribution of the litter respiration to the total soil respiration was 31.0%–45.9% for the three different-aged forests. The present study found that the total soil respiration was not significantly affected by forest age when P. masonniana stands exceed a certain age (e.g. >20 years old), but it increased significantly with increased soil temperature. Hence, forest management strategies need to protect the understory vegetation to limit soil warming, in order to reduce the CO2 emission under the currently rapid global warming. The contribution of litter decomposition to the total soil respiration varies across spatial and temporal scales. This indicates the need for separate consideration of soil and litter respiration when assessing the climate impacts on forest carbon cycling. PMID:25004164

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils Meike Sauerwein1, Alexander Hanke2, Klaus Kaiser3, Karsten Kalbitz2 1) Dept. of Soil Ecology, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany, meike.sauerwein@gmail.com 2) Institute of ecosystem dynamics and biodiversity, University of Amsterdam, 1018 WV, Netherlands, a.hanke@uva.nl, k.kalbitz@uva.nl 3) Soil Sciences, Martin Luther University Halle, 06099 Halle, Germany, klaus.kaiser@landw.uni-halle.de Current knowledge on dissolved organic matter (DOM) in soils is based mainly on observations and experiments in aerobic environments. Adsorption to soil minerals is an important mechanism of DOM retention and stabilization against microbial decay under oxic conditions. Under anoxic conditions where hydrous iron oxides, the potential main adsorbents of DOM, possibly dissolve, the importance of adsorption seems questionable. Therefore, we studied the adsorption of DOM to selected soil minerals and to mineral soils under oxic and anoxic conditions. In detail, we tested the following hypotheses: 1. Minerals and soils adsorb less DOM under anoxic conditions than under oxic ones. 2. The reduced adsorption under anoxic conditions is result of the smaller adsorption to hydrous Fe oxides whereas adsorption to clay minerals and Al hydroxides is not sensitive to changes in redox conditions 3. DOM adsorption will increase with the number of redox cycles, thus time of soil formation, due to increasing contents of poorly crystalline Fe oxides. This will, however, cause a stronger sensitivity to redox changes as poor crystalline Fe oxides are more reactive. 4. Aromatic compounds, being preferentially adsorbed under oxic conditions, will be less strongly adsorbed under anoxic conditions. We chose paddy soils as models because their periodically and regular exposure to changing redox cycles, with

  12. Weathering and aging of 2,4,6-trinitrotoluene in soil increases toxicity to potworm Enchytraeus crypticus.

    PubMed

    Kuperman, Roman G; Checkai, Ronald T; Simini, Michael; Phillips, Carlton T; Kolakowski, Jan E; Kurnas, Carl W

    2005-10-01

    Energetic materials are employed in a wide range of commercial and military activities and often are released into the environment. Scientifically based ecological soil-screening levels (Eco-SSLs) are needed to identify contaminant explosive levels in soil that present an acceptable ecological risk. Insufficient information for 2,4,6-trinitrotoluene (TNT) to generate Eco-SSLs for soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of TNT. Weathering and aging procedures for TNT amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated TNT-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests showed that toxicity for E. crypticus adult survival and juvenile production was increased significantly in weathered and aged soil treatments compared with toxicity in freshly amended soil based on 95% confidence intervals. The median effect concentration and 20% effective concentration for reproduction were 98 and 77 mg/kg, respectively, for TNT freshly amended into soil and 48 and 37 mg/kg, respectively, for weathered and aged TNT soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged TNT soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of energetic contaminants in soil.

  13. Assessment of bioavailability limitations during slurry biodegradation of petroleum hydrocarbons in aged soils.

    PubMed

    Huesemann, Michael H; Hausmann, Tom S; Fortman, Tim J

    2003-12-01

    In an effort to determine whether bioavailability limitations are responsible for the slow or incomplete hydrocarbon biodegradation in aged soils, both the rate of desorption (rdes) and biodegradation (rbio) was measured for n-alkanes and polynuclear aromatic hydrocarbons (PAHs) at different times during the slurry biotreatment of six different soils. While all n-alkanes were biodegraded to various degrees depending on their respective carbon number and the soil organic matter content, none of them were desorbed to a significant extent, indicating that these saturated hydrocarbons do not need to be transferred from the soil particles into the aqueous phase in order to be metabolized by microorganisms. Most two- and three-ring PAHs biodegraded as fast as they were desorbed (rbio = rdes); that is, desorption rates controlled biodegradation rates. By contrast, the biodegradation kinetics of four-, five-, and six-ring PAHs was limited by microbial factors during the initial phase (rbio < rdes) while becoming mass-transfer rate limited during the final phase of bioremediation treatment (rbio = rdes). Whenever PAH biodegradation stalled or did not occur at all (rbio = 0), it was never due to bioavailability limitations (rdes > 0) but was more likely caused by microbial factors. such as the absence of specific PAH degraders or cometabolic substrates. Consequently, PAHs that are found to be microbially recalcitrant in aged soils may not be so because of limited bioavailability and thus could pose a greater risk to the environment than previously thought.

  14. Ethylene limits abscisic acid- or soil drying-induced stomatal closure in aged wheat leaves.

    PubMed

    Chen, Lin; Dodd, Ian C; Davies, William J; Wilkinson, Sally

    2013-10-01

    The mechanism of age-induced decreased stomatal sensitivity to abscisic acid (ABA) and soil drying has been explored here. Older, fully expanded leaves partly lost their ability to close stomata in response to foliar ABA sprays, and soil drying which stimulated endogenous ABA production, while young fully expanded leaves closed their stomata more fully. However, ABA- or soil drying-induced stomatal closure of older leaves was partly restored by pretreating plants with 1-methylcyclopropene (1-MCP), which can antagonize ethylene receptors, or by inoculating soil around the roots with the rhizobacterium Variovorax paradoxus 5C-2, which contains 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase. ACC (the immediate biosynthetic precursor of ethylene) sprays revealed higher sensitivity of stomata to ethylene in older leaves than younger leaves, despite no differences in endogenous ACC concentrations or ethylene emission. Taken together, these results indicate that the relative insensitivity of stomatal closure to ABA and soil drying in older leaves is likely due to altered stomatal sensitivity to ethylene, rather than ethylene production. To our knowledge, this is the first study to mechanistically explain diminished stomatal responses to soil moisture deficit in older leaves, and the associated reduction in leaf water-use efficiency.

  15. Mutagenic hazards of complex polycyclic aromatic hydrocarbon mixtures in contaminated soil

    SciTech Connect

    Lemieux, C.L.; Lambert, A.B.; Lundstedt, S.; Tysklind, M.; White, P.A.

    2008-04-15

    The objective of the present study was to evaluate hazard/risk assessment methods for complex environmental mixtures that involve a targeted, priority chemical approach based on the cumulative hazard/risk of known mixture components or analyses of sufficiently similar mixtures. Ten polycyclic aromatic hydrocarbon (PAH)-contaminated soils were separated into nonpolar and semipolar fractions, and both fractions elicited positive responses on the Salmonella reverse mutation assay. Targeted and nontargeted methods of hazard prediction routinely overestimated mutagenic activities for the nonpolar soil fractions, suggesting nonadditive interactions of PAHs in complex mixtures. This suggests that current risk assessment methods for complex mixtures may provide conservative estimates regarding soils contaminated with priority PAHs alone. Significant underestimations of total risk, however, will be obtained if the soils also contain unidentified PAHs as well as polycyclic aromatic compounds and related compounds that contribute to the total mutagenic activity. Furthermore, estimates of excess lifetime cancer risk associated with the nondietary ingestion of the PAH-contaminated soils studied here indicate that a traditional risk assessment model based on identified priority PAHs and an assumption of additivity generally underestimates the risk associated with the nonpolar soil fractions (in comparison to bioassay-derived risk estimates). Additional cancer risk may be associated with the more polar compounds that also are found at these contaminated sites and that rarely are included in the standard risk assessment methodology.

  16. Polycyclic aromatic hydrocarbons in water, sediment and soil of the Songhua River Basin, China.

    PubMed

    Ma, Wan-Li; Liu, Li-Yan; Qi, Hong; Zhang, Zi-Feng; Song, Wei-Wei; Shen, Ji-Min; Chen, Zhong-Lin; Ren, Nan-Qi; Grabuski, Josey; Li, Yi-Fan

    2013-10-01

    The Songhua River is the third largest river in China and the primary source of drinking and irrigation water for northeastern China. The distribution of 16 priority polycyclic aromatic hydrocarbons (PAHs) in water [dissolved water (DW) and suspended particulate matter (SPM)], sediment, and soil in the river basin was investigated, and the associated risk of cancer from these PAHs was also assessed. The total concentration of PAHs ranged from 13.9 to 161 ng L(-1) in DW, 9.21 to 83.1 ng L(-1) in SPM, 20.5 to 632 ng g(-1) dw (dry weight) in sediment, and from 30.1 to 870 ng g(-1) dw in soil. The compositional pattern of PAHs indicated that three-ring PAHs were predominant in DW and SPM samples, while four-ring PAHs dominated in sediment and soil samples. The spatial distribution of PAHs revealed some site-specific sources along the river, with principal component analysis indicating that these were from pyrogenic sources (such as coal and biomass combustion, and vehicle emissions) and coke oven emission distinguished as the main source of PAHs in the Songhua River Basin. Based on the ingestion of PAH-contaminated drinking water from the Songhua River, cancer risk was quantitatively estimated by combining the Incremental Lifetime Cancer Risk assessment model and BaP-equivalent concentration for five age groups of people (adults, teenagers, children, toddlers, and infants). Overall, the results suggest that the estimated integrated lifetime cancer risk for all groups was in acceptable levels. This study is the first attempt to provide information on the cancer risk of PAHs in drinking water from the Songhua River.

  17. Identification of Anthraquinone-Degrading Bacteria in Soil Contaminated with Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Rodgers-Vieira, Elyse A.; Zhang, Zhenfa; Adrion, Alden C.; Gold, Avram

    2015-01-01

    Quinones and other oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are toxic and/or genotoxic compounds observed to be cocontaminants at PAH-contaminated sites, but their formation and fate in contaminated environmental systems have not been well studied. Anthracene-9,10-dione (anthraquinone) has been found in most PAH-contaminated soils and sediments that have been analyzed for oxy-PAHs. However, little is known about the biodegradation of oxy-PAHs, and no bacterial isolates have been described that are capable of growing on or degrading anthraquinone. PAH-degrading Mycobacterium spp. are the only organisms that have been investigated to date for metabolism of a PAH quinone, 4,5-pyrenequinone. We utilized DNA-based stable-isotope probing (SIP) with [U-13C]anthraquinone to identify bacteria associated with anthraquinone degradation in PAH-contaminated soil from a former manufactured-gas plant site both before and after treatment in a laboratory-scale bioreactor. SIP with [U-13C]anthracene was also performed to assess whether bacteria capable of growing on anthracene are the same as those identified to grow on anthraquinone. Organisms closely related to Sphingomonas were the most predominant among the organisms associated with anthraquinone degradation in bioreactor-treated soil, while organisms in the genus Phenylobacterium comprised the majority of anthraquinone degraders in the untreated soil. Bacteria associated with anthracene degradation differed from those responsible for anthraquinone degradation. These results suggest that Sphingomonas and Phenylobacterium species are associated with anthraquinone degradation and that anthracene-degrading organisms may not possess mechanisms to grow on anthraquinone. PMID:25819957

  18. Aging effect on the leaching behavior of heavy metals (Cu, Zn, and Cd) in red paddy soil.

    PubMed

    Huang, Bin; Li, Zhongwu; Huang, Jinquan; Chen, Guiqiu; Nie, Xiaodong; Ma, Wenming; Yao, Hongbo; Zhen, Jiamei; Zeng, Guangming

    2015-08-01

    Aging effect can influence the fractions distribution and mobility of metals after they are added into soil. In this study, incubation and soil column experiments under simulated acid rain condition were conducted to evaluate aging effect on the leaching characteristic of Cu, Zn, and Cd in artificial polluted red paddy soil. Our results showed that aging effect reduced metal contents in exchangeable and HoAc soluble fractions. Power function was the most excellent to describe the variation of exchangeable fraction, while pseudo first- and second-order functions were more successful to describe the leaching characteristic of metals from soil columns. The leaching amount of the metals from the polluted soil only accounted for a small part of their total content in soil, and the leachability of Cu was the weakest. Both the exchangeable and HoAc soluble fraction were available as indicators to evaluate the leachability of metals in red paddy soil. The shorter time the soil was contaminated, the more amounts of metals released from the soil. The reduction of exchangeable fraction caused by aging effect was the main reason for the decrease of metal mobility in soil. PMID:25821039

  19. Aging effect on the leaching behavior of heavy metals (Cu, Zn, and Cd) in red paddy soil.

    PubMed

    Huang, Bin; Li, Zhongwu; Huang, Jinquan; Chen, Guiqiu; Nie, Xiaodong; Ma, Wenming; Yao, Hongbo; Zhen, Jiamei; Zeng, Guangming

    2015-08-01

    Aging effect can influence the fractions distribution and mobility of metals after they are added into soil. In this study, incubation and soil column experiments under simulated acid rain condition were conducted to evaluate aging effect on the leaching characteristic of Cu, Zn, and Cd in artificial polluted red paddy soil. Our results showed that aging effect reduced metal contents in exchangeable and HoAc soluble fractions. Power function was the most excellent to describe the variation of exchangeable fraction, while pseudo first- and second-order functions were more successful to describe the leaching characteristic of metals from soil columns. The leaching amount of the metals from the polluted soil only accounted for a small part of their total content in soil, and the leachability of Cu was the weakest. Both the exchangeable and HoAc soluble fraction were available as indicators to evaluate the leachability of metals in red paddy soil. The shorter time the soil was contaminated, the more amounts of metals released from the soil. The reduction of exchangeable fraction caused by aging effect was the main reason for the decrease of metal mobility in soil.

  20. [Bacterial community structure and diversity in soils of different forest ages and types in Bao- tianman forest, Henan Province, China].

    PubMed

    Bai, Xiao-xu; Shi, Rong-ju; You, Ye-ming; Sheng, Hua-fang; Han, Si-qin; Zhang, Ying

    2015-08-01

    To compare the microbial compositions and diversities in soils of different forest ages and types in Baotianman forest, Henan Province, China, genomic DNA of forest soils was extracted for amplifying the 16S rRNA V4 hyper variable region by PCR and sequencing by Illumina MiSeq. The BIPES, UCHIME and QIIME were employed to analyze the soil bacterial community. It was shown that 60 phyla were identified, with Proteobacteria, Acidobacteria, and Verrucomicrobia representing the most dominant lineages and accounting for 29%, 18.5% and 10% of all sequences, respectively. At the genus level, 1209 genera were identified, the most abundant phylotypes were DA101 (6.3%), Acidobacteria-2 (5.9%), Candidatus Solibacter (2.9%) and Candidatus Nitrososphaera (2.6%). Different forest age and type soil samples had unique compositions and specific high and rare genus. Forest type and age both impacted the soil microbial community structure, and the influence of the former was stronger than the latter. The soil microbial diversity of the 80-year-old Quercus aliena forest was the lowest among all age and type forest soil samples. Soil pH, soil nitrogen and organic carbon contents were the most important factors affecting soil bacterial community structure.

  1. [Characteristics of soil nematode community along an age sequence of sandy desert soil cultivation in a marginal oasis of middle reaches of Heihe River].

    PubMed

    Wang, Xue-Feng; Su, Yong-Zhong; Yang, Rong

    2010-08-01

    This paper studied the characteristics of soil nematode community following the conversion of native sandy desert soil to irrigated farmland in a marginal oasis of the middle reaches of Heihe River basin, aimed to approach the bioindicating function of soil nematodes in soil evolution process. A total of 27921 soil nematode individuals were captured, belonging to 25 families and 34 genera. The total number of nematodes increased gradually with increasing age of cultivation. At all sampling sites, bacterivores and plant parasites were the dominant trophic groups, and made up the main parts of nematode community in oasis farmland. Through the analysis of the evenness index (J) and dominance index (lambda) of nematode community, the ecosystems were found to be fragile for the farmlands having cultivated for 0, 10, and > 50 years. The maturity index MI2-5 and MMI decreased with increasing cultivation age, suggesting that the practice of agricultural use enhanced the disturbance on farmland. The soil properties changed significantly after 10 years of cultivation, which was at a significant change stage for the structure stability of soil ecosystems. The characteristics of soil nematode community could be used as the bioindicator of soil evolution following the conversion of native desert soil to irrigated farmland.

  2. Rb-Sr age of a Luna 16 basalt and the model age of lunar soils.

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.; Wasserburg, G. J.

    1972-01-01

    An internal isochron was determined on a small basalt fragment (sample B-1) returned from the Luna 16 mission, which yields an age of 3.42 plus or minus 0.8 b.y. and a low initial Sr87/Sr86 value. A comparison is made of the data from four lunar missions to mare sites which shows that the last period of major flooding of the mare basins is confined to a narrow time interval of only 0.55 b.y. The direct evidence of major lunar magmatic activity appears to be confined to the interval from 3.1 to 4.0 b.y. The Sr87/Sr86 values for all mare basalts are extremely primitive and lie in a rather narrow range. A diagram is given for initial Sr87/Sr86 as a function of time for all lunar rocks.

  3. Soil Microbial Community Structure and Metabolic Activity of Pinus elliottii Plantations across Different Stand Ages in a Subtropical Area

    PubMed Central

    Wu, Zeyan; Haack, Stacey Elizabeth; Lin, Wenxiong; Li, Bailian; Wu, Linkun; Fang, Changxun; Zhang, Zhixing

    2015-01-01

    Soil microbes play an essential role in the forest ecosystem as an active component. This study examined the hypothesis that soil microbial community structure and metabolic activity would vary with the increasing stand ages in long-term pure plantations of Pinus elliottii. The phospholipid fatty acids (PLFA) combined with community level physiological profiles (CLPP) method was used to assess these characteristics in the rhizospheric soils of P. elliottii. We found that the soil microbial communities were significantly different among different stand ages of P. elliottii plantations. The PLFA analysis indicated that the bacterial biomass was higher than the actinomycic and fungal biomass in all stand ages. However, the bacterial biomass decreased with the increasing stand ages, while the fungal biomass increased. The four maximum biomarker concentrations in rhizospheric soils of P. elliottii for all stand ages were 18:1ω9c, 16:1ω7c, 18:3ω6c (6,9,12) and cy19:0, representing measures of fungal and gram negative bacterial biomass. In addition, CLPP analysis revealed that the utilization rate of amino acids, polymers, phenolic acids, and carbohydrates of soil microbial community gradually decreased with increasing stand ages, though this pattern was not observed for carboxylic acids and amines. Microbial community diversity, as determined by the Simpson index, Shannon-Wiener index, Richness index and McIntosh index, significantly decreased as stand age increased. Overall, both the PLFA and CLPP illustrated that the long-term pure plantation pattern exacerbated the microecological imbalance previously described in the rhizospheric soils of P. elliottii, and markedly decreased the soil microbial community diversity and metabolic activity. Based on the correlation analysis, we concluded that the soil nutrient and C/N ratio most significantly contributed to the variation of soil microbial community structure and metabolic activity in different stand ages of P

  4. Stand age, tree location and depth impacts on the hydrophobicity of forested dune soils

    NASA Astrophysics Data System (ADS)

    Walsh, Richard; McCreath, Iain; Ogden, Mike; Hallett, Paul

    2015-04-01

    The hydrology of a forest is one of the key mechanisms needed for its productivity. Paradoxically, biomass from forests such as decomposing needles and soil micro-organisms, may result in hydrophobic substances that impede water flow and decrease water retention. At the same time, the decomposition of plant biomass may alter soil pore structure to improve flow and retention of water. Although water repellency has been widely reported in boreal forests, including in unlikely locations in northern maritime climates, the effect of stand age and soil location in relation to trees has not been investigated. In this study it was hypothesised that water repellency would increase with stand age, and would be greater at the interface between the litter layer and soil than in the subsoil or the litter layer itself. Measurements were conducted with soil from Culbin Forest, which is located on the northeast coast of the UK. The forest was planted in phases, starting over 100 years ago, as a means to stabilise eroding sand dunes that were initially highly hydrophilic. Soils were sampled from the litter layer, at the interface between the litter and sand and in the subsoil at locations under the tree, in the drip line and outside of the tree. Field replicated areas planted with Scots Pine in 1888, 1925, 1969, 1992 and 2000 were selected to provide a chronosequence. A series of tests were carried out both in the field and the laboratory to determine the influence that the age of Scots pine trees have on the water repellency of the soil. These included the water drop penetration test and infiltration measurements within the field, while a modified Wilhelmy plate test and capillary rise measurements were measured in the laboratory. The soil was found to possess non-significant water repellency features within the field, likely due to high water content levels of the soil at the time of testing. But after drying, the soil was highly water repellent. The contact angle or repellency

  5. Toxicity of emerging energetic soil contaminant CL-20 to potworm Enchytraeus crypticus in freshly amended or weathered and aged treatments.

    PubMed

    Kuperman, Roman G; Checkai, Ronald T; Simini, Michael; Phillips, Carlton T; Anthony, J Steven; Kolakowski, Jan E; Davis, Emily A

    2006-03-01

    We investigated the toxicity of an emerging polynitramine energetic material hexanitrohexaazaisowurtzitane (CL-20) to the soil invertebrate species Enchytraeus crypticus by adapting then using the Enchytraeid Reproduction Test (ISO/16387:2003). Studies were designed to develop ecotoxicological benchmark values for ecological risk assessment of the potential impacts of accidental release of this compound into the environment. Tests were conducted in Sassafras Sandy Loam soil, which supports relatively high bioavailability of CL-20. Weathering and aging procedures for CL-20 amended into test soil were incorporated into the study design to produce toxicity data that better reflect soil exposure conditions in the field compared with the toxicity in freshly amended soils. Concentration-response relationships for measurement endpoints were determined using nonlinear regressions. Definitive tests showed that toxicities for E. crypticus adult survival and juvenile production were significantly increased in weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. The median effect concentration (EC50) and EC20 values for juvenile production were 0.3 and 0.1 mg kg-1, respectively, for CL-20 freshly amended into soil, and 0.1 and 0.035 mg kg-1, respectively, for weathered and aged CL-20 soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged CL-20 soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of emerging energetic contaminants in soil.

  6. Toxicity of emerging energetic soil contaminant CL-20 to potworm Enchytraeus crypticus in freshly amended or weathered and aged treatments.

    PubMed

    Kuperman, Roman G; Checkai, Ronald T; Simini, Michael; Phillips, Carlton T; Anthony, J Steven; Kolakowski, Jan E; Davis, Emily A

    2006-03-01

    We investigated the toxicity of an emerging polynitramine energetic material hexanitrohexaazaisowurtzitane (CL-20) to the soil invertebrate species Enchytraeus crypticus by adapting then using the Enchytraeid Reproduction Test (ISO/16387:2003). Studies were designed to develop ecotoxicological benchmark values for ecological risk assessment of the potential impacts of accidental release of this compound into the environment. Tests were conducted in Sassafras Sandy Loam soil, which supports relatively high bioavailability of CL-20. Weathering and aging procedures for CL-20 amended into test soil were incorporated into the study design to produce toxicity data that better reflect soil exposure conditions in the field compared with the toxicity in freshly amended soils. Concentration-response relationships for measurement endpoints were determined using nonlinear regressions. Definitive tests showed that toxicities for E. crypticus adult survival and juvenile production were significantly increased in weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. The median effect concentration (EC50) and EC20 values for juvenile production were 0.3 and 0.1 mg kg-1, respectively, for CL-20 freshly amended into soil, and 0.1 and 0.035 mg kg-1, respectively, for weathered and aged CL-20 soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged CL-20 soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of emerging energetic contaminants in soil. PMID:16213571

  7. Identification of soil bacteria able to degrade phenanthrene bound to a hydrophobic sorbent in situ.

    PubMed

    Regonne, Raïssa Kom; Martin, Florence; Mbawala, Augustin; Ngassoum, Martin Benoît; Jouanneau, Yves

    2013-09-01

    Efficient bioremediation of PAH-contaminated sites is limited by the hydrophobic character and poor bioavailability of pollutants. In this study, stable isotope probing (SIP) was implemented to track bacteria that can degrade PAHs adsorbed on hydrophobic sorbents. Temperate and tropical soils were incubated with (13)C-labeled phenanthrene, supplied by spiking or coated onto membranes. Phenanthrene mineralization was faster in microcosms with PAH-coated membranes than in microcosms containing spiked soil. Upon incubation with temperate soil, phenanthrene degraders found in the biofilms that formed on coated membranes were mainly identified as Sphingomonadaceae and Actinobacteria. In the tropical soil, uncultured Rhodocyclaceae dominated degraders bound to membranes. Accordingly, ring-hydroxylating dioxygenase sequences recovered from this soil matched PAH-specific dioxygenase genes recently found in Rhodocyclaceae. Hence, our SIP approach allowed the detection of novel degraders, mostly uncultured, which differ from those detected after soil spiking, but might play a key role in the bioremediation of PAH-polluted soils.

  8. Behavior of MCPA in four intensive cropping soils amended with fresh, composted, and aged olive mill waste

    NASA Astrophysics Data System (ADS)

    López-Piñeiro, Antonio; Peña, David; Albarrán, Angel; Sánchez-Llerena, Javier; Becerra, Daniel

    2013-09-01

    An evaluation was made of the impact of olive mill waste and its organic matter transformation on the sorption, desorption, leaching, and degradation of the herbicide MCPA when the waste was applied to four Mediterranean soils. The soils were amended in the laboratory with fresh, composted, and field-aged olive mill waste (OW, COW, and AOW treatments, respectively). It was found that the greater the amount of OW applied to the soils, but especially the greater its organic matter maturity, the greater the adsorption of MCPA. Compared with unamended soils, at the 5% rate of application the adsorption capacity increased by between 9.8% and 40%, 148% and 224%, and by 258% for the OW, COW, and AOW amended soils, respectively. The hysteresis coefficients were significantly lower in the OW-amended soils than in AOW or COW-amended soils, indicating that the adsorbed MCPA could be easily desorbed in OW-amended soils if the amendment is not aged or composted. While the OW addition greatly extended the persistence of MCPA, the application of COW enhanced MCPA degradation in all the soils, as corresponded to the increased soil microbial activity indicated by the higher levels of soil dehydrogenase activity. Fresh OW amendment significantly increased the amount of MCPA leached (from 13.7% in the most alkaline soil to 36.7% in the most acidic, at the 5% rate of application), favored by the higher levels of water soluble organic carbon content. However, leaching losses of the herbicide were reduced by up to 39.9% and 55.3% in the COW- and AOW-amended soils at the 5% loading rate, respectively. The use of OW with a high degree of organic matter maturity may be regarded as a potentially useful management practice to reduce MCPA leaching in soils with low organic matter content. The application of fresh OW, however, could well increase the risk of groundwater contamination by this herbicide, especially in acidic soils.

  9. Behavior of MCPA in four intensive cropping soils amended with fresh, composted, and aged olive mill waste.

    PubMed

    López-Piñeiro, Antonio; Peña, David; Albarrán, Angel; Sánchez-Llerena, Javier; Becerra, Daniel

    2013-09-01

    An evaluation was made of the impact of olive mill waste and its organic matter transformation on the sorption, desorption, leaching, and degradation of the herbicide MCPA when the waste was applied to four Mediterranean soils. The soils were amended in the laboratory with fresh, composted, and field-aged olive mill waste (OW, COW, and AOW treatments, respectively). It was found that the greater the amount of OW applied to the soils, but especially the greater its organic matter maturity, the greater the adsorption of MCPA. Compared with unamended soils, at the 5% rate of application the adsorption capacity increased by between 9.8% and 40%, 148% and 224%, and by 258% for the OW, COW, and AOW amended soils, respectively. The hysteresis coefficients were significantly lower in the OW-amended soils than in AOW or COW-amended soils, indicating that the adsorbed MCPA could be easily desorbed in OW-amended soils if the amendment is not aged or composted. While the OW addition greatly extended the persistence of MCPA, the application of COW enhanced MCPA degradation in all the soils, as corresponded to the increased soil microbial activity indicated by the higher levels of soil dehydrogenase activity. Fresh OW amendment significantly increased the amount of MCPA leached (from 13.7% in the most alkaline soil to 36.7% in the most acidic, at the 5% rate of application), favored by the higher levels of water soluble organic carbon content. However, leaching losses of the herbicide were reduced by up to 39.9% and 55.3% in the COW- and AOW-amended soils at the 5% loading rate, respectively. The use of OW with a high degree of organic matter maturity may be regarded as a potentially useful management practice to reduce MCPA leaching in soils with low organic matter content. The application of fresh OW, however, could well increase the risk of groundwater contamination by this herbicide, especially in acidic soils. PMID:23911783

  10. Behavior of MCPA in four intensive cropping soils amended with fresh, composted, and aged olive mill waste.

    PubMed

    López-Piñeiro, Antonio; Peña, David; Albarrán, Angel; Sánchez-Llerena, Javier; Becerra, Daniel

    2013-09-01

    An evaluation was made of the impact of olive mill waste and its organic matter transformation on the sorption, desorption, leaching, and degradation of the herbicide MCPA when the waste was applied to four Mediterranean soils. The soils were amended in the laboratory with fresh, composted, and field-aged olive mill waste (OW, COW, and AOW treatments, respectively). It was found that the greater the amount of OW applied to the soils, but especially the greater its organic matter maturity, the greater the adsorption of MCPA. Compared with unamended soils, at the 5% rate of application the adsorption capacity increased by between 9.8% and 40%, 148% and 224%, and by 258% for the OW, COW, and AOW amended soils, respectively. The hysteresis coefficients were significantly lower in the OW-amended soils than in AOW or COW-amended soils, indicating that the adsorbed MCPA could be easily desorbed in OW-amended soils if the amendment is not aged or composted. While the OW addition greatly extended the persistence of MCPA, the application of COW enhanced MCPA degradation in all the soils, as corresponded to the increased soil microbial activity indicated by the higher levels of soil dehydrogenase activity. Fresh OW amendment significantly increased the amount of MCPA leached (from 13.7% in the most alkaline soil to 36.7% in the most acidic, at the 5% rate of application), favored by the higher levels of water soluble organic carbon content. However, leaching losses of the herbicide were reduced by up to 39.9% and 55.3% in the COW- and AOW-amended soils at the 5% loading rate, respectively. The use of OW with a high degree of organic matter maturity may be regarded as a potentially useful management practice to reduce MCPA leaching in soils with low organic matter content. The application of fresh OW, however, could well increase the risk of groundwater contamination by this herbicide, especially in acidic soils.

  11. Mechanistic characterization of adsorption and slow desorption of phenanthrene aged in soils

    SciTech Connect

    Abdul Abu; Steve Smith

    2006-09-01

    Long-term adsorption of phenanthrene to soils was characterized in a silt-loam (LHS), a sandy soil (SBS) from an uncontaminated area of a former coal treatment facility in the north of England and a podzolized soil (CNS) by use of the Polanyi-Manes model, a Langmuir-type model, and a black carbon-water distribution coefficient (K{sub BC}) at a relative aqueous concentration (C{sub e}/S{sub w}) of 0.002 - 0.32. Aqueous desorption kinetic tests and temperature-programmed desorption (TPD) were also used to evaluate phenanthrene diffusivities and desorption activation energies. Adsorption contribution in soils was 48-70% after 30 days and 64-95% after 270 days. Significant increases in adsorption capacity with aging suggest that accessibility of phenanthrene to fractions of SBS soil matrix was controlled by sorptive diffusion at narrow meso- and micropore constrictions. Similar trends were not significant for LHS silt-loam or CNS podzol. Analysis of TPD profiles reveal desorption activation energies of 35-53 kJ/mol and diffusivities of 1.6 x 10{sup -7-}9.7 10{sup -8} cm{sup 2}/s. TPD tests also indicate that the fraction of phenanthrene mass not diffusing from soils was located within micropores and narrow width mesopores with a corresponding volume of 1.83 10{sup -5-}6.3710{sup -5} cm{sup 3}/g. These values were consistent with the modeled adsorption contributions, thus demonstrating the need for such complimentary analytical approach in the risk assessment of organic contaminants. 41 refs., 2 figs., 4 tabs.

  12. Climate and soil-age constraints on nutrient uplift by plants.

    NASA Astrophysics Data System (ADS)

    Porder, S.; Chadwick, O. A.

    2007-12-01

    We analyzed changes in nutrient availability and elemental losses from the entire weathering zone at 28 sites arrayed across climatic and soil-age gradients on the island of Hawai'i. The sites are located on three basaltic lava flows (10, 170, and 350 ky) each of which crosses a precipitation gradient from <500 to 2,500 mm yr- 1. The results identify a sweet spot of plant nutrient uplift where nutrient cations and phosphorus are retained in upper horizons as a result of plant activity. The gradients also elucidate several abiotic constraints on plant- driven retention of nutrients. At the dry sites (<750 mm yr-1on all three flows, plant slow the loss of nutrient (e.g. potassium) vs. non-nutrient (e.g. sodium) cations, but the effect is small because of low plant cover and productivity. At intermediate rainfall (750 - 1300 mm yr-1) plants substantially enrich both nutrient cations and P in the upper soils, an effect that increases with flow age. In contrast, at high rainfall (>1500 mm yr-1), the effect of plants on nutrient distributions diminishes with soil age and is largely absent after 350 ky of soil development. Unlike the major plant macronutrients, the distribution of the transition metals iron (Fe) and aluminum (Al) is driven more by chemical reactions than by plant uptake. Dry sites exhibit very little movement of either element, even after 350 ky of soil development. However at high rainfall the older flows show substantial Al and Fe translocations, and wet sites on all three flows have increased Al on soil exchange sites. These transition metals are key constituents of the secondary minerals that strongly influence the availability of cations and P to plants. The loss of Fe and Al is highly correlated with the loss of P in the older and wetter sites, and increased Al on exchange sites limits the availability of nutrient cations to plants. Thus redox driven redistribution of Fe and acid solublization of Al place a further abiotic constraint on nutrient

  13. Trajectories of soil particles on a hillslope conveyor: Implications for particle age and Be-10 field

    NASA Astrophysics Data System (ADS)

    Anderson, R. S.

    2015-12-01

    Many geomorphic systems act as conveyor belts onto which material is loaded at a particular rate, and is transported in one direction toward another system that serves as a sink. In general the material will evolve as it travels: it ages, it changes in grain size, it absorbs and releases nutrients, it weathers and it accumulates cosmogenic radionuclides. Here I address the hillslope conveyor. As many geochemical and physical processes are depth-dependent, the depth history of a particle becomes important to know. I calculate soil particle trajectories in the horizontal-depth plane and address three steady state cases, one in which horizontal speeds decline exponentially with depth, a second in which they are uniform with depth, and a third in which horizontal speeds are also uniform but all profile values are vertically well-mixed. Vertical speeds are governed by conservation of mass, which requires that strain rates in the horizontal enact strains rates of opposite sign in the vertical, and by the boundary conditions of zero vertical particle speed at the soil surface and the particle release rate at the saprolite interface. Particle trajectories must become surface-parallel at the surface. Knowledge of soil particle trajectories allows calculation of residence times and concentration profiles of 10Be in the soil. In all steady cases, the particle age and 10Be structure are uniform with distance from the divide. When significant vertical gradients in horizontal speed occur, the vertical profiles of particle age and 10Be concentration are dominated by the depth scale of the transport process. In unmixed cases, the particle age and 10Be concentration in near-surface samples can greatly exceed the vertically averaged values, reflecting the slowing of vertical speeds as particles approach the surface. Where horizontal speeds vary significantly with depth, the vertically-averaged concentration of 10Be within the soil can significantly under-predict the mean 10Be

  14. Assessment of the biological and chemical availability of the freshly spiked and aged DDE in soil.

    PubMed

    Škulcová, L; Neuwirthová, N; Hofman, J; Bielská, L

    2016-05-01

    The study compared the ability of various chemical methods (XAD, β-hydroxypropylcyclodextrin - HPCD) and solid phase micro-extraction (SPME)) to mimic earthworm uptake from two similar soils containing either spiked or aged p,p´-DDE, thus representing two extreme scenarios with regard to the length of pollutant-soil contact time and the way of contamination. The extent of bioaccumulation was assessed at fixed exposure periods (10 and 21 days) and at equilibrium derived from uptake curves by multiple-point comparison or kinetic modeling. The decision on the best chemical predictor of biological uptake differed. The degree of bioaccumulation at equilibrium was best predicted by XAD while HPCD rather reflected the extent of accumulation derived after 21 days when, however, steady-state was not reached for spiked p,p´-DDE. SPME seemed to underestimate the uptake of aged p,p´-DDE, probably of the fraction taken up via soil particles. Thus, the degree of predictability seems to be associated with the capability of the chemical method to mimic the complex earthworm uptake via skin and intestinal tract as well as with the quality of biological data where the insufficient length of exposure period appears to be the major concern. PMID:26840523

  15. Aging well: methanotrophic potential and community structure along a paddy soil chronosequence of 2000 years.

    NASA Astrophysics Data System (ADS)

    Ho, Adrian; Frenzel, Peter

    2010-05-01

    Given that rice paddies are anthropogenic methane sources and the inevitable need to increase rice production to sustain human population growth, it is pertinent to identify the effects of long term agriculture on the selection of methanotrophs. Methanotrophs play a crucial role in mitigating methane emission from rice paddies. Therefore, we analyzed the methanotroph community along a chronosequence of paddy soils from China covering recently reclaimed sites to paddies under permanent agriculture since 2000 years (Cheng et al., 2009; doi:10.1016/j.geoderma.2009.03.016). Maximum potential methane oxidation rate (PMOR) increased monotonically with age. Our results also showed that long-term agriculture imposes a selection pressure on different groups of methanotrophs. In contrast to younger soils, type Ib methanotrophs were observed to multiply in correspondence with increasing PMOR in ancient soils, while other groups showed a relatively stable community composition as revealed by pmoA-based fingerprints (T-RFLP) and quantitative PCR. Cloning and sequencing the pmoA (a key gene in methane oxidation), the soils were found to harbour known and putative methanotrophs, ammonium-oxidizing bacteria, and interestingly, sequences affiliated to Crenothrix, a methane oxidizer with an unusual pmoA (Stoecker et al., 2006; doi:10.1073/pnas.0506361103). In summary, long-term agriculture shapes the community and allows for an elevated level of potential methane oxidation.

  16. Age and origin of Terra Rossa soils in the Coonawarra area of South Australia

    NASA Astrophysics Data System (ADS)

    Mee, Aija C.; Bestland, Erick A.; Spooner, Nigel A.

    2004-03-01

    The famous Terra Rossa soil in the Coonawarra area, South Australia, is dominated by locally derived aeolian detritus, which probably accumulated over the last 120-130 ka. Four soil profiles and associated limestone and lunette deposits were investigated using the following methods: mass balance geochemistry of bulk soil samples (major and trace elements), quantitative X-ray diffraction (XRD) mineralogy, strontium isotopes (87/86), as well as grain-size analysis and cation exchange capacity. These data show that the Terra Rossa soil from the Coonawarra has a thick, clayey B-horizon which is geochemically homogeneous and dominated by smectite and kaolinite. Mass-balance calculations show unrealistic weathering scenarios when plotted using silicate residuum from the underlying limestone as parent. Realistic weathering scenarios are produced with fine-grained silicate material from local lunette deposits as parent. Strontium isotopes of silicate residuum from Gambier Limestone (0.78) contrast strongly with the clayey B-horizon (0.726). Strontium isotope ratios of silicate material from a local lunette (0.725) are similar to the B-horizon soil values. Strontium isotope ratios from regional geological units indicate that the strontium signature in the lunette and soil B-horizon is dominated by weathering products from the Palaeozoic Kanmantoo shales, extensively exposed upwind to the west on Kangaroo Island and the Fleurieu Peninsula. Optical (optically stimulated luminescence, OSL) dating of 61 individual quartz grains (single aliquot) from three samples in the Coonawarra soil profile (one from the A-horizon and two from the B-horizon) shows that most of the quartz sand grains have been buried for only a few thousand years. Many of the grains, however, have been buried for tens of thousands of years with three grains having exposure ages of between 105 and 109 ka. The large population of young exposure dates represents quartz sands recently exposed in the A-horizon and

  17. Toxicities of dinitrotoluenes and trinitrobenzene freshly amended or weathered and aged in a sandy loam soil to Enchytraeus crypticus.

    PubMed

    Kuperman, Roman G; Checkai, Ronald T; Simini, Michael; Phillips, Carlton T; Kolakowski, Jan E; Kurnas, Carl W

    2006-05-01

    Scientifically based ecological soil-screening levels are needed to identify concentrations of contaminant energetic materials (EMs) in soil that present an acceptable ecological risk at a wide range of military installations. Insufficient information regarding the toxicity of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), and 1,3,5-trinitrobenzene (TNB) to soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test (International Standardization Organization 16387:2003) and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of nitroaromatic EMs. Weathering and aging procedures for EMs amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated, EM-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests established that the order of EM toxicity to E. crypticus based on the median effect concentration values for juvenile production in either freshly amended or weathered and aged treatments was (from the greatest to least toxicity) TNB > 2,4-DNT > 2,6-DNT. Toxicity to E. crypticus juvenile production was significantly increased in 2,6-DNT weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. This result shows that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information regarding ecotoxicological effects of energetic contaminants in soil.

  18. Effect of aging on the bioavailability and fractionation of arsenic in soils derived from five parent materials in a red soil region of Southern China.

    PubMed

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

    2015-12-01

    The effects of aging time and soil parent materials on the bioavailability and fractionations of arsenic (As) in five red soils were studied. The results indicated that As bioavailability in all soils decreased during aging, especially with a sharp decline occurring in the first 30 days. After aging for 360 days, the highest available As concentration, which accounted for 12.3% of the total, was observed in soils derived from purple sandy shale. While 2.67% was the lowest proportion of the available As in soils derived from quaternary red clay. Furthermore, the best fit of the available As changing with aging time was obtained using the pseudo-second-order model (R(2) = 0.939-0.998, P < 0.05). Notably, Al oxides played a more crucial role (R(2) = 0.89, P<0.05) than did Fe oxides in controlling the rate of As aging. The non-specially and specially absorbed As constituted the primary forms of available As. PMID:26349069

  19. Polycyclic aromatic hydrocarbon-contaminated soils: bioaugmentation of autochthonous bacteria and toxicological assessment of the bioremediation process by means of Vicia faba L.

    PubMed

    Ruffini Castiglione, Monica; Giorgetti, Lucia; Becarelli, Simone; Siracusa, Giovanna; Lorenzi, Roberto; Di Gregorio, Simona

    2016-04-01

    Two bacterial strains, Achromobacter sp. (ACH01) and Sphingomonas sp. (SPH01), were isolated from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated soil (5431.3 ± 102.3 ppm) for their capacity to use a mixture of anthracene, pyrene, phenanthrene and fluorene as sole carbon sources for growth and for the capacity to produce biosurfactants. The two strains were exploited for bioaugmentation in a biopile pilot plant to increase the bioavailability and the degradation of the residual PAH contamination (99.5 ± 7.1 ppm) reached after 9 months of treatment. The denaturing gel gradient electrophoresis (DGGE) profile of the microbial ecology of the soil during the experimentation showed that the bioaugmentation approach was successful in terms of permanence of the two strains in the soil in treatment. The bioaugmentation of the two bacterial isolates positively correlated with the PAH depletion that reached 7.9 ± 2 ppm value in 2 months of treatment. The PAH depletion was assessed by the loss of the phyto-genotoxicity of soil elutriates on the model plant Vicia faba L., toxicological assessment adopted also to determine the minimum length of the decontamination process for obtaining both the depletion of the PAH contamination and the detoxification of the soil at the end of the process. The intermediate phases of the bioremediation process were the most significant in terms of toxicity, inducing genotoxic effects and selective DNA fragmentation in the stem cell niche of the root tip. The selective DNA fragmentation can be related to the selective induction of cell death of mutant stem cells that can compromise offsprings.

  20. Polycyclic aromatic hydrocarbon-contaminated soils: bioaugmentation of autochthonous bacteria and toxicological assessment of the bioremediation process by means of Vicia faba L.

    PubMed

    Ruffini Castiglione, Monica; Giorgetti, Lucia; Becarelli, Simone; Siracusa, Giovanna; Lorenzi, Roberto; Di Gregorio, Simona

    2016-04-01

    Two bacterial strains, Achromobacter sp. (ACH01) and Sphingomonas sp. (SPH01), were isolated from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated soil (5431.3 ± 102.3 ppm) for their capacity to use a mixture of anthracene, pyrene, phenanthrene and fluorene as sole carbon sources for growth and for the capacity to produce biosurfactants. The two strains were exploited for bioaugmentation in a biopile pilot plant to increase the bioavailability and the degradation of the residual PAH contamination (99.5 ± 7.1 ppm) reached after 9 months of treatment. The denaturing gel gradient electrophoresis (DGGE) profile of the microbial ecology of the soil during the experimentation showed that the bioaugmentation approach was successful in terms of permanence of the two strains in the soil in treatment. The bioaugmentation of the two bacterial isolates positively correlated with the PAH depletion that reached 7.9 ± 2 ppm value in 2 months of treatment. The PAH depletion was assessed by the loss of the phyto-genotoxicity of soil elutriates on the model plant Vicia faba L., toxicological assessment adopted also to determine the minimum length of the decontamination process for obtaining both the depletion of the PAH contamination and the detoxification of the soil at the end of the process. The intermediate phases of the bioremediation process were the most significant in terms of toxicity, inducing genotoxic effects and selective DNA fragmentation in the stem cell niche of the root tip. The selective DNA fragmentation can be related to the selective induction of cell death of mutant stem cells that can compromise offsprings. PMID:26769476

  1. Soil respiration and photosynthetic uptake of carbon dioxide by ground-cover plants in four ages of jack pine forest

    USGS Publications Warehouse

    Striegl, R.G.; Wickland, K.P.

    2001-01-01

    Soil carbon dioxide (CO2) emission (soil respiration), net CO2 exchange after photosynthetic uptake by ground-cover plants, and soil CO2 concentration versus depth below land surface were measured at four ages of jack pine (Pinus banksiana Lamb.) forest in central Saskatchewan. Soil respiration was smallest at a clear-cut site, largest in an 8-year-old stand, and decreased with stand age in 20-year-old and mature (60-75 years old) stands during May-September 1994 (12.1, 34.6, 31.5, and 24.9 mol C??m-2, respectively). Simulations of soil respiration at each stand based on continuously recorded soil temperature were within one standard deviation of measured flux for 48 of 52 measurement periods, but were 10%-30% less than linear interpolations of measured flux for the season. This was probably due to decreased soil respiration at night modeled by the temperature-flux relationships, but not documented by daytime chamber measurements. CO2 uptake by ground-cover plants ranged from 0 at the clear-cut site to 29, 25, and 9% of total growing season soil respiration at the 8-year, 20-year, and mature stands. CO2 concentrations were as great as 7150 ppmv in the upper 1 m of unsaturated zone and were proportional to measured soil respiration.

  2. The impact of biochar on the bioaccessibility of (14)C-phenanthrene in aged soil.

    PubMed

    Ogbonnaya, O U; Adebisi, O O; Semple, K T

    2014-11-01

    Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (14)C-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (14)C-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (14)C-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.

  3. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine.

    PubMed

    Trigo, Carmen; Spokas, Kurt A; Cox, Lucia; Koskinen, William C

    2014-11-12

    Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes.

  4. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine.

    PubMed

    Trigo, Carmen; Spokas, Kurt A; Cox, Lucia; Koskinen, William C

    2014-11-12

    Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes. PMID:25338136

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

    USGS Publications Warehouse

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

    1997-01-01

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

  6. Chemical changes in soil charcoal of differing ages inferred from DRIFT spectra

    NASA Astrophysics Data System (ADS)

    Hobley, E. U.; Willgoose, G. R.; Frisia, S.; Jacobsen, G.

    2012-04-01

    Visible charcoal fragments were manually isolated from a sandy soil from the Southern Highlands of NSW, Australia, at depths of 0 - 30 cm and 30 - 60 cm. In the topsoil, the charcoal had a radiocarbon age of 85 ± 35 years BP, whereas the charcoal from the 30 - 60 cm layer was radiocarbon dated at 2540 ± 35 years BP. Diffuse reflectance FTIR (DRIFT) spectra of the charcoal reveal differences in both the number of peaks detected and their magnitudes. In the IR region 750 - 3800 cm-1, the charcoal from the lower depth had less peaks (140) than that of the topsoil (217). In the 1400 - 1600 cm-1 region, generally attributed to aromatics, the peaks were larger and more numerous (22 peaks) in the 0 - 30 cm sample than those of the 30 - 60 cm depth (14 peaks). The C-H stretch of alkenes and aromatics (3000 - 3100 cm-1) was similar at both depths, but the peak generally associated with the C-H stretch of alkanes (methyl and methylene groups) at 2850 - 3000 cm-1 was smaller in 30 - 60 cm depth than in the topsoil. In contrast to the reduction in aromatic and alkane signatures, oxidised forms were more pronounced in the older, deeper charcoal. Peaks associated with the free hydroxyl O-H stretch (alcohols and phenols) at 3640 - 3610 cm-1, carboxylic acids (910 - 950 cm-1), aliphatic O-H (alcohols) (1050 - 1150 cm-1) and cellulose-like structures (1020 cm-1), which contain a large number of uncondensed, oxidised rings, were larger in the charcoal from 30 - 60 cm than in that from the topsoil. Our results confirm that charcoal is highly persistent in soils, being retained for millennia. Aromatic structures are present in both younger and older charcoal, but decay leads to a reduction in the number and area of peaks detected at 1400 - 1600 cm-1, indicating less aromaticity. Alkane C-H also decreases with aging, probably attributable to its preferential degradation by soil microbes compared with condensed aromatic structures. Concurrent with diminished aromatic and alkane

  7. Estimation of uncertainty in the sampling and analysis of polychlorinated biphenyls and polycyclic aromatic hydrocarbons from contaminated soil in Brighton, UK.

    PubMed

    Zhou, John L; Siddiqui, Ertan; Ngo, Huu Hao; Guo, Wenshan

    2014-11-01

    The heterogeneity of environmental samples is increasingly recognised, yet rarely examined in organic contamination investigations. In this study soil samples from an ex-landfill site in Brighton, UK were analysed for polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH) contamination by using a balanced sampling protocol. The analytical technique of gas chromatography-mass spectrometry was found to be fit for purpose by the use of duplicate samples and the statistical analysis of variances, as well as of certified reference materials. The sampling uncertainty was found to significantly overweigh the analytical uncertainty, by a factor of 3 and 6 for PCBs and PAHs, respectively. The soil samples showed a general trend of PCB concentration that was under the recommended target level of 20 ng/g dry weight. It is possible that one site alongside the main road may exceed the 20 ng/g target level, after taking into consideration the overall measurement uncertainty (70.8%). The PAH contamination was more severe, with seven sites potentially exceeding the effect-range medium concentrations. The soil samples with relatively high PCB and PAH concentrations were all taken from the grass verge, which also had the highest soil organic carbon content. The measurement uncertainty which was largely due to sampling can be reduced by sampling at a high resolution spacing of 17 m, which is recommended in future field investigations of soil organic contamination.

  8. Influence of soil ageing on bioavailability and ecotoxicity of lead carried by process waste metallic ultrafine particles.

    PubMed

    Schreck, E; Foucault, Y; Geret, F; Pradere, P; Dumat, C

    2011-11-01

    Ultrafine particulate matters enriched with metals are emitted into the atmosphere by industrial activities and can impact terrestrial and aquatic ecosystems. Thus, this study investigated the environmental effects of process particles from a lead-recycling facility after atmospheric deposition on soils and potential run-off to surface waters. The toxicity of lead-enriched PM for ecosystems was investigated on lettuce and bacteria by (i) germination tests, growth assays, lead transfer to plant tissues determination and (ii) Microtox analysis. The influence of ageing and soil properties on metal transfer and ecotoxicity was studied using three different soils and comparing various aged, spiked or historically long-term polluted soils. Finally, lead availability was assessed by 0.01 M CaCl(2) soil extraction. The results showed that process PM have a toxic effect on lettuce seedling growth and on Vibrio fischeri metabolism. Soil-PM interactions significantly influence PM ecotoxicity and bioavailability; the effect is complex and depends on the duration of ageing. Solubilisation or stabilisation processes with metal speciation changes could be involved. Finally, Microtox and phytotoxicity tests are sensitive and complementary tools for studying process PM ecotoxicity. PMID:21868052

  9. Influence of soil ageing on bioavailability and ecotoxicity of lead carried by process waste metallic ultrafine particles.

    PubMed

    Schreck, E; Foucault, Y; Geret, F; Pradere, P; Dumat, C

    2011-11-01

    Ultrafine particulate matters enriched with metals are emitted into the atmosphere by industrial activities and can impact terrestrial and aquatic ecosystems. Thus, this study investigated the environmental effects of process particles from a lead-recycling facility after atmospheric deposition on soils and potential run-off to surface waters. The toxicity of lead-enriched PM for ecosystems was investigated on lettuce and bacteria by (i) germination tests, growth assays, lead transfer to plant tissues determination and (ii) Microtox analysis. The influence of ageing and soil properties on metal transfer and ecotoxicity was studied using three different soils and comparing various aged, spiked or historically long-term polluted soils. Finally, lead availability was assessed by 0.01 M CaCl(2) soil extraction. The results showed that process PM have a toxic effect on lettuce seedling growth and on Vibrio fischeri metabolism. Soil-PM interactions significantly influence PM ecotoxicity and bioavailability; the effect is complex and depends on the duration of ageing. Solubilisation or stabilisation processes with metal speciation changes could be involved. Finally, Microtox and phytotoxicity tests are sensitive and complementary tools for studying process PM ecotoxicity.

  10. Effects of aging herbicide mixtures on soil respiration and plant survival in soils from a pesticide-contaminated site

    SciTech Connect

    Kruger, E.L.; Anhalt, J.C.; Anderson, T.A.

    1996-10-01

    Three herbicides, atrazine, metolachlor, and pendimethalin, were applied individually and in all possible combinations to soil taken from a pesticide-contaminated site in Iowa. The rate of application for each chemical was 50 {mu}g/g, representative of contamination problems at mixing and loading areas of agrochemical dealer sites. Treated soils were incubated at 24{degrees}C in the dark for 0, 21, and 63 d, and soil moisture tension was maintained at -33 kPa. Soil respiration was measured daily by using an infrared gas analyzer for 10 d at the end of each incubation period. Subsamples of treated soils were used in plant germination and survival studies. Concentrations of each herbicide were determined by gas chromatography at day 0, 21, and 63. Soil respiration was elevated for the first 6 d immediately following treatment, and then declined to very low levels. At the end of day 21 and 63, soil respiration remained at very low levels. The half-lives for atrazine, metolachlor, and pendimethalin individually in soil or in combination with one and/or the other herbicide will be reported. The results of germination and survival studies with kochia, giant foxtail, birdsfoot trefoil, crown vetch, and soybean will also be reported.

  11. Enrichment behavior and transport mechanism of soil-bound PAHs during rainfall-runoff events.

    PubMed

    Zheng, Yi; Luo, Xiaolin; Zhang, Wei; Wu, Bin; Han, Feng; Lin, Zhongrong; Wang, Xuejun

    2012-12-01

    Polycyclic Aromatic Hydrocarbons (PAHs) transported by surface runoff result in nonpoint source pollution and jeopardize aquatic ecosystems. The transport mechanism of PAHs during rainfall-runoff events has been rarely studied regarding pervious areas. An experimental system was setup to simulate the runoff pollution process on PAHs-contaminated soil. The enrichment behavior of soil-bound PAHs was investigated. The results show that soil organic matters (SOM), rather than clay particles, seem to be the main carrier of PAHs. The enrichment is highly conditioned on runoff and erosion processes, and its magnitude varies among PAH compounds. It is not feasible to build a simple and universal relationship between enrichment ratio and sediment discharge following the traditional enrichment theory. To estimate the flux of PAHs from pervious areas, soil erosion process has to be clearly understood, and both organic carbon content and composition of SOM should be factored into the calculation.

  12. Age chronosequence effects on restoration quality of reclaimed coal mine soils in Mississipian agroecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface coal mining causes drastic disturbances in landscape and soil properties, and reclamation has the potential to improve and re-store soil quality and biomass productivity. However, it is not clear how long it takes for an effective soil reclamation process to restore soil quality to the pre-...

  13. Accumulation of 2,4-dinitroanisole in the earthworm Eisenia fetida from chemically spiked and aged natural soils.

    PubMed

    Lotufo, Guilherme R; Coleman, Jessica G; Harmon, Ashley R; Chappell, Mark A; Bednar, Anthony J; Russell, Amber L; Smith, Jared C; Brasfield, Sandra M

    2016-07-01

    An initiative within the US military is targeting the replacement of traditional munitions constituents with insensitive munitions to reduce the risk of accidental detonation. The bioavailability and bioaccumulative potential of the insensitive munitions compound 2,4-dinitroanisole (DNAN) to Eisenia fetida was assessed in soils with different geochemical characteristics. Prior to exposure, soils were chemically spiked with DNAN and aged for 1 wk or 29 wk. Transformation products 2- and 4-amino-nitroanisole (2A-4NAN and 4A-2NAN) occurred in aged soils and their porewater but never at concentrations higher than the residual DNAN. The sum of DNAN, 2A-4NAN, and 4A-2NAN (sumDNAN) in soil decreased with aging, likely by irreversible binding. Both clay and organic matter contents of the soil appeared to affect the bioavailability of DNAN. The sumDNAN body residues of earthworms approached apparent steady state after 1 d and remained relatively constant through to day 7. Higher concentrations of 2A-4NAN and 4A-2NAN measured in worm tissues relative to those in soil suggest reductive transformation of DNAN in the tissues. Mean bioaccumulation factors (ratio of tissue to soil concentrations) varied from 1.2 to 4.3, whereas mean bioconcentration factors (ratio of tissue to porewater concentrations) ranged from 1.4 to 3.2. Porewater seems to play a significant role in the accumulation of DNAN in earthworms, consistent with equilibrium partitioning theory. The concentration of DNAN in soil porewater could serve as an indicator of bioavailability as well as a predictor of the concentration of that compound in earthworms. Environ Toxicol Chem 2016;35:1835-1842. Publlished 2015 SETAC. This article is a US Government work, and as such, is in the public domain in the United States of America. PMID:26666709

  14. Accumulation of 2,4-dinitroanisole in the earthworm Eisenia fetida from chemically spiked and aged natural soils.

    PubMed

    Lotufo, Guilherme R; Coleman, Jessica G; Harmon, Ashley R; Chappell, Mark A; Bednar, Anthony J; Russell, Amber L; Smith, Jared C; Brasfield, Sandra M

    2016-07-01

    An initiative within the US military is targeting the replacement of traditional munitions constituents with insensitive munitions to reduce the risk of accidental detonation. The bioavailability and bioaccumulative potential of the insensitive munitions compound 2,4-dinitroanisole (DNAN) to Eisenia fetida was assessed in soils with different geochemical characteristics. Prior to exposure, soils were chemically spiked with DNAN and aged for 1 wk or 29 wk. Transformation products 2- and 4-amino-nitroanisole (2A-4NAN and 4A-2NAN) occurred in aged soils and their porewater but never at concentrations higher than the residual DNAN. The sum of DNAN, 2A-4NAN, and 4A-2NAN (sumDNAN) in soil decreased with aging, likely by irreversible binding. Both clay and organic matter contents of the soil appeared to affect the bioavailability of DNAN. The sumDNAN body residues of earthworms approached apparent steady state after 1 d and remained relatively constant through to day 7. Higher concentrations of 2A-4NAN and 4A-2NAN measured in worm tissues relative to those in soil suggest reductive transformation of DNAN in the tissues. Mean bioaccumulation factors (ratio of tissue to soil concentrations) varied from 1.2 to 4.3, whereas mean bioconcentration factors (ratio of tissue to porewater concentrations) ranged from 1.4 to 3.2. Porewater seems to play a significant role in the accumulation of DNAN in earthworms, consistent with equilibrium partitioning theory. The concentration of DNAN in soil porewater could serve as an indicator of bioavailability as well as a predictor of the concentration of that compound in earthworms. Environ Toxicol Chem 2016;35:1835-1842. Publlished 2015 SETAC. This article is a US Government work, and as such, is in the public domain in the United States of America.

  15. Experimental increase in availability of a PAH complex organic contamination from an aged contaminated soil: consequences on biodegradation.

    PubMed

    Cébron, Aurélie; Faure, Pierre; Lorgeoux, Catherine; Ouvrard, Stéphanie; Leyval, Corinne

    2013-06-01

    Although high PAH content and detection of PAH-degraders, the PAH biodegradation is limited in aged-contaminated soils due to low PAH availability (i.e., 1%). Here, we tried to experimentally increase the soil PAH availability by keeping both soil properties and contamination composition. Organic extract was first removed and then re-incorporated in the raw soil as fresh contaminants. Though drastic, this procedure only allowed a 6-time increase in the PAH availability suggesting that the organic constituents more than ageing were responsible for low availability. In the re-contaminated soil, the mineralization rate was twice more important, the proportion of 5-6 cycles PAH was higher indicating a preferential degradation of lower molecular weight PAH. The extraction treatment induced bacterial and fungal community structures modifications, Pseudomonas and Fusarium solani species were favoured, and the relative quantity of fungi increased. In re-contaminated soil the percentage of PAH-dioxygenase gene increased, with 10 times more Gram negative representatives.

  16. Metal accumulation in roadside soil in Melbourne, Australia: Effect of road age, traffic density and vehicular speed.

    PubMed

    De Silva, Shamali; Ball, Andrew S; Huynh, Trang; Reichman, Suzie M

    2016-01-01

    Concentrations of vehicular emitted heavy metals in roadside soils result in long term environmental damage. This study assessed the relationships between traffic characteristics (traffic density, road age and vehicular speed) and roadside soil heavy metals. Significant levels were recorded for Cd (0.06-0.59 mg/kg), Cr (18-29 mg/kg), Cu (4-12 mg/kg), Ni (7-20 mg/kg), Mn (92-599 mg/kg), Pb (16-144 mg/kg) and Zn (10.36-88.75 mg/kg), with Mn concentrations exceeding the Ecological Investigation Level. Significant correlations were found between roadside soil metal concentration and vehicular speed (R = 0.90), road age (R = 0.82) and traffic density (R = 0.68). Recently introduced metals in automotive technology (e.g. Mn and Sb) were higher in younger roads, while the metals present for many years (e.g. Cd, Cu, Pb, Zn) were higher in medium and old age roads confirming the risk of significant metal deposition and soil metal retention in roadside soils.

  17. Metal accumulation in roadside soil in Melbourne, Australia: Effect of road age, traffic density and vehicular speed.

    PubMed

    De Silva, Shamali; Ball, Andrew S; Huynh, Trang; Reichman, Suzie M

    2016-01-01

    Concentrations of vehicular emitted heavy metals in roadside soils result in long term environmental damage. This study assessed the relationships between traffic characteristics (traffic density, road age and vehicular speed) and roadside soil heavy metals. Significant levels were recorded for Cd (0.06-0.59 mg/kg), Cr (18-29 mg/kg), Cu (4-12 mg/kg), Ni (7-20 mg/kg), Mn (92-599 mg/kg), Pb (16-144 mg/kg) and Zn (10.36-88.75 mg/kg), with Mn concentrations exceeding the Ecological Investigation Level. Significant correlations were found between roadside soil metal concentration and vehicular speed (R = 0.90), road age (R = 0.82) and traffic density (R = 0.68). Recently introduced metals in automotive technology (e.g. Mn and Sb) were higher in younger roads, while the metals present for many years (e.g. Cd, Cu, Pb, Zn) were higher in medium and old age roads confirming the risk of significant metal deposition and soil metal retention in roadside soils. PMID:26603093

  18. [Improving Agricultural Safety of Soils Contaminated with Polycyclic Aromatic Hydrocarbons by In Situ Bioremediation].

    PubMed

    Jiao, Hai-huan; Pan, Jian-gang; Xu, Shena-jun; Bai, Zhi-hui; Wang, Dong; Huang, Zhan-bin

    2015-08-01

    In order to reduce the risk of enrichment of polycyclic aromatic hydrocarbons (PAHs) in crops, reduce the potential hazards of food-sourced PAHs to human and increase the agricultural safety of PAHs contaminated soils, the bio-augmented removal of polycyclic aromatic hydrocarbons (PAHs) was investigated through in situ remediation by introducing Rhodobacter sphaeroides (RS) into the agricultural soil contaminated by PAHs. The 50-times diluted RS was sprayed on leaf surface (in area B) or irrigated to roots (in area D). The treatment of spraying water of the equal amount was taken as the control (A) and the wheat field without any treatment as the blank (CK). Treatments were conducted since wheat seeding. Soil and wheat samples were collected in the mature period to analyze the changes of community structure of the soil microorganisms and the concentration of PAHs in soils and investigate the strengthening and restoration effects of RS on PAHs contaminated soils. Compared to the CK Area, the areas B and D revealed that the variation ratio of phospholipid fatty acids (PLFAs) that were the biomarker of soil microorganisms was 29.6%, and the ratio of total PAHs removed was increased 1.59 times and 1.68 times, respectively. The dry weight of wheat grain of 50 spikes was increased by 8.95% and 12.5%, respectively, and the enrichment factor of total PAHs was decreased by 58.9% and 62.2% respectively in the wheat grains. All the results suggested that RS reduced enrichment of PAHs in wheat grains and increased wheat yield, which had great exploitation and utilization potentiality in repairing and improving the agricultural safety of the soils contaminated with PHAs.

  19. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  20. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  1. Impact of Hydrologic and Micro-topographic Variabilities on Spatial Distribution of Mean Soil-Nitrogen Age

    NASA Astrophysics Data System (ADS)

    Woo, D.; Kumar, P.

    2015-12-01

    Excess reactive nitrogen in soils of intensively managed agricultural fields causes adverse environmental impact, and continues to remain a global concern. Many novel strategies have been developed to provide better management practices and, yet, the problem remains unresolved. The objective of this study is to develop a 3-dimensional model to characterize the spatially distributed ``age" of soil-nitrogen (nitrate and ammonia-ammonium) across a watershed. We use the general theory of age, which provides an assessment of the elapsed time since nitrogen is introduced into the soil system. Micro-topographic variability incorporates heterogeneity of nutrient transformations and transport associated with topographic depressions that form temporary ponds and produce prolonged periods of anoxic conditions, and roadside agricultural ditches that support rapid surface movement. This modeling effort utilizes 1-m Light Detection and Ranging (LiDAR) data. We find a significant correlation between hydrologic variability and mean nitrate age that enables assessment of preferential flow paths of nitrate leaching. The estimation of the mean nitrogen age can thus serve as a tool to disentangle complex nitrogen dynamics by providing the analysis of the time scales of soil-nitrogen transformation and transport processes without introducing additional parameters.

  2. [Soil organic carbon storage in different aged Larix gmelinii plantations in Great Xing' an Mountains of Northeast China].

    PubMed

    Qi, Guang; Wang, Qing-Li; Wang, Xin-Chuang; Yu, Da-Pao; Zhou, Li; Zhou, Wang-Ming; Peng, Shun-Lei; Dai, Li-Min

    2013-01-01

    A sampling plot investigation was conducted to study the soil organic carbon (SOC) storage in 0-40 cm layer in 10-, 15-, 26- and 61 years old Larix gmelinii plantations in Great Xing' an Mountains of Northeast China as well as the temporal variation pattern of the SOC source/sink during the plantation management after the clear cutting of primary L. gmelinii forest. With the increasing age of the plantations, the SOC storage increased after an initial decrease, and the inflection point was at a stand age between 15- and 26-years old. Compared with that of primary forest, the SOC storage of the plantations played a role of carbon source at early stage (10-26 years old), but gradually transformed into carbon sink then, with a SOC storage of 158.91 t x hm(-2) in 61-year-old plantation. The SOC storage of the plantations increased with soil depth initially, but was higher in upper soil layer than in deeper soil layer after the stand age being 26, which implied that human disturbance had strong effects on the vertical distribution of SOC. It was considered that the appropriate cutting age for the L. gmelinii plantations in Great Xing' an Mountains could be at least 60 years old.

  3. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  4. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  5. Climate control on soil age and weathering thresholds in young, post-glacial soils of New Zealand

    NASA Astrophysics Data System (ADS)

    Dixon, J. L.; Chadwick, O.; Vitousek, P.

    2014-12-01

    Climate is often invoked as a major driver of soil and landscape evolution. But a coherent story has failed to emerge for how climate controls soil properties and weathering rates - partially due to competing influences of mineral residence times and supply rates in eroding landscapes. Here, we combine insights and methods across the related fields of geomorphology, soil science and geochemistry, to explore weathering thresholds in non-eroding, young soils along a strong precipitation gradient (400-4000 mm/yr) in the South Island of New Zealand. We studied ~30 soil profiles developed in thin (~1m) loess deposits that mantle LGM and post LGM moraines and outwash in the Waitaki catchment, extending from Lake Benmore to just below the Tasman glacier in the north. We find repeated thresholds (sharp, non-linear transitions) in soil chemistry, including exchangeable cations, pH and total elemental abundances. Abundance of pedogenic iron and aluminum increase with precipitation, stabilizing at ~2000 mm/yr. Plant-available phosphorous and exchangeable Ca and Mg are rapidly depleted as precipitation exceeds 1000 mm/yr. However total elemental abundances show up to 50% of major cations are retained at wetter sites, likely in less labile minerals. Preliminary numerical modeling of cation weathering kinetics provides some support for this interpretation. Together our data identify nonlinear changes in weathering intensity with rainfall, and show clear climate control on relatively young, post-glacial soil development. Additionally, we measured profiles and inventories of meteoric 10Be to quantify soil residence times across the climate gradient. This nuclide is cosmogenically produced in the atmosphere and binds strongly to reactive surfaces in soil following fallout. Exchangeable beryllium does not decrease with rainfall, despite decreasing pH along the climate gradient. Therefore we are confident that nuclide concentrations do not reflect leaching. Instead, these

  6. Metolachlor sorption and degradation in soil amended with fresh and aged biochar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Addition of organic amendments such as biochar to soils can influence pesticide sorption-desorption processes, and in turn, pesticide availability and biodegradation. Availability is affected by both the physical and chemical properties of soils and pesticides, as well as soil-pesticide contact time...

  7. Soil sterilization affects aging-related sequestration and bioavailability of p,p'-DDE and anthracene to earthworms.

    PubMed

    Slizovskiy, Ilya B; Kelsey, Jason W

    2010-10-01

    Laboratory experiments investigated the effects of soil sterilization and compound aging on the bioaccumulation of spiked p,p'-DDE and anthracene by Eisenia fetida and Lumbricus terrestris. Declines in bioavailability occurred as pollutant residence time in both sterile and non-sterile soils increased from 3 to 203 d. Accumulation was generally higher in sterile soils during initial periods of aging (from 3-103 d). By 203 d, however, bioavailability of the compounds was unaffected by sterilization. Gamma irradiation and autoclaving may have altered bioavailability by inducing changes in the chemistry of soil organic matter (SOM). The results support a dual-mode partitioning sorption model in which the SOM components associated with short-term sorption (the 'soft' or 'rubbery' phases) are more affected than are the components associated with long-term sorption (the 'glassy' or microcrystalline phases). Risk assessments based on data from experiments in which sterile soil was used could overestimate exposure and bioaccumulation of pollutants. PMID:20708831

  8. Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.

    PubMed

    Mousset, Emmanuel; Huguenot, David; van Hullebusch, Eric D; Oturan, Nihal; Guibaud, Gilles; Esposito, Giovanni; Oturan, Mehmet A

    2016-04-01

    The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (p

  9. Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.

    PubMed

    Mousset, Emmanuel; Huguenot, David; van Hullebusch, Eric D; Oturan, Nihal; Guibaud, Gilles; Esposito, Giovanni; Oturan, Mehmet A

    2016-04-01

    The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (p

  10. Development of a differential volume reactor system for soil biodegradation studies

    SciTech Connect

    Webb, O.F.; Bienkowski, P.R.; Reed, G.D.

    1991-12-31

    A bench scale experimental system was developed for the analysis of polycyclic aromatic hydrocarbon (PAH) degradation by mixed microbial cultures in PAH contaminated Manufactured Gas Plant (MGP) soils and on sand. The reactor system was chosen in order to provide a fundamental protocol capable for evaluating the performance of specific mixed microbial cultures on specific soil systems by elucidating the important system variables and their interactions. The reactor design and peripherals are described. A plug flow differential volume reactor (DVR) was used in order to remove performance effects related to reactor type, as opposed to system structure. This reactor system could be well represented mathematically. Methods were developed for on-line quantitative determination of PAH liquid phase concentrations. The mathematical models and experimental data are presented for the biodegradation of naphthalene on artificial and MGP soils.

  11. Development of a differential volume reactor system for soil biodegradation studies.

    PubMed

    Webb, O F; Phelps, T J; Bienkowski, P R; DiGrazia, P M; Reed, G D; Applegate, B; White, D C; Sayler, G S

    1991-01-01

    A bench scale experimental system was developed for the analysis of polycyclic aromatic hydrocarbon (PAH) degradation by mixed microbial cultures in PAH contaminated Manufactured Gas Plant (MGP) soils and on sand. The reactor system was chosen in order to provide a fundamental protocol capable for evaluating the performance of specific mixed microbial cultures on specific soil systems by elucidating the important system variables and their interactions. The reactor design and peripherals are described. A plug flow differential volume reactor (DVR) was used in order to remove performance effects related to reactor type, as opposed to system structure. This reactor system could be well represented mathematically. Methods were developed for on-line quantitative determination of PAH liquid phase concentrations. The mathematical models and experimental data are presented for the biodegradation of naphthalene on artificial and MGP soils.

  12. Potential nitrogen fixation activity of different aged biological soil crusts from rehabilitated grasslands of the hilly Loess Plateau, China

    USGS Publications Warehouse

    Zhao, Y.; Xu, M.; Belnap, J.

    2010-01-01

    Biological soil crusts (biocrusts) cover up to 60–70% of the soil surface in grasslands rehabilitated during the "Grain for Green" project implemented in the hilly Loess Plateau region in 1999. As biocrusts fix nitrogen (N), they are an important part of restoring soil fertility. We measured nitrogenase activity (NA) in biocrusts from sites rehabilitated at six different time periods to estimate 1) the effects of moisture content and temperature on NA in biocrusts of different ages and 2) the potential N contribution from biocrusts to soils and plants in this region. Results show that NA in the biocrusts was mostly controlled by the species composition, as the activity of biocrusts dominated by free-living soil cyanobacteria was significantly higher than that of moss-dominated biocrusts. Nitrogenase activity was also influenced by soil moisture content and ambient temperature, with a significant decline in activity when moisture levels were decreased to 20% field water-holding capacity. The optimal temperature for NA was 35–40 °C and 30–40 °C for cyanobacteria- and moss-dominated biocrusts, respectively. Biocrust fixed N is likely an important source of N in this ecosystem, as we estimated annual potential N inputs per hectare in these grasslands to be up to 13 kg N ha-1 and 4 kg N ha-1 for cyanobacteria- and moss-dominated biocrusts, respectively.

  13. [Aging Law of PAHs in Contaminated Soil and Their Enrichment in Earthworms Characterized by Chemical Extraction Techniques].

    PubMed

    Zhang, Ya-nan; Yang, Xing-lun; Bian, Yong-rong; Gu, Cheng-gang; Liu, Zong-tang; Li, Jiao; Wang, Dai-zhang; Jiang, Xin

    2015-12-01

    To evaluate the effect of aging on the availability of PAHs, chemical extraction by exhaustive ( ASE extraction) and nonexhaustive techniques (Tenax-TA extraction, hydroxypropyl-p-cyclodextrin ( HPCD ) extraction, n-butyl alcohol ( BuOH) extraction) as well as PAHs accumulation in earthworms (Eisenia fetida) were conducted in yellow soil from Baguazhou, Nanjing, China, and red soil from Hainan, China, spiked with phenanthrene, pryene and benzo(a) pyrene and aged 0, 7, 15, 30 and 60 days. The results showed that the concentration of PAHs extracted by ASE and three nonexhaustive techniques and accumulated by earthworms significantly decreased with aging time, except the ASE extracted concentration between 30-and 60-day aging time. Furthermore, the relationships were studied in this experiment between chemical extracted PAHs concentration and accumulated concentration in earthworms. PAHs accumulated concentration in earthworms was not significantly correlated with the exhaustive extracted concentration of PAHs in soil (R² 0.44-0.56), which indicated that ASE extraction techniques could not predict PAHs bioavailability to earthworms because it overestimated the risk of PAHs. However, the PAHs accumulated concentration in earthworms was significantly correlated with the three nonexhaustive extracted concentrations of PAHs in soil, which indicated that all the three nonexhaustive techniques could predict PAHs bioavailability to earthworm to some extent, among which, HPCD extraction (R² 0.94-0.99) was better than Tenax-TA extraction (R² 0.62-0.87) and BuOH extraction (R² 0.69-0.94). So HPCD extraction was a more appropriate and reliable technique to predict bioavailability of PAHs in soil.

  14. [Aging Law of PAHs in Contaminated Soil and Their Enrichment in Earthworms Characterized by Chemical Extraction Techniques].

    PubMed

    Zhang, Ya-nan; Yang, Xing-lun; Bian, Yong-rong; Gu, Cheng-gang; Liu, Zong-tang; Li, Jiao; Wang, Dai-zhang; Jiang, Xin

    2015-12-01

    To evaluate the effect of aging on the availability of PAHs, chemical extraction by exhaustive ( ASE extraction) and nonexhaustive techniques (Tenax-TA extraction, hydroxypropyl-p-cyclodextrin ( HPCD ) extraction, n-butyl alcohol ( BuOH) extraction) as well as PAHs accumulation in earthworms (Eisenia fetida) were conducted in yellow soil from Baguazhou, Nanjing, China, and red soil from Hainan, China, spiked with phenanthrene, pryene and benzo(a) pyrene and aged 0, 7, 15, 30 and 60 days. The results showed that the concentration of PAHs extracted by ASE and three nonexhaustive techniques and accumulated by earthworms significantly decreased with aging time, except the ASE extracted concentration between 30-and 60-day aging time. Furthermore, the relationships were studied in this experiment between chemical extracted PAHs concentration and accumulated concentration in earthworms. PAHs accumulated concentration in earthworms was not significantly correlated with the exhaustive extracted concentration of PAHs in soil (R² 0.44-0.56), which indicated that ASE extraction techniques could not predict PAHs bioavailability to earthworms because it overestimated the risk of PAHs. However, the PAHs accumulated concentration in earthworms was significantly correlated with the three nonexhaustive extracted concentrations of PAHs in soil, which indicated that all the three nonexhaustive techniques could predict PAHs bioavailability to earthworm to some extent, among which, HPCD extraction (R² 0.94-0.99) was better than Tenax-TA extraction (R² 0.62-0.87) and BuOH extraction (R² 0.69-0.94). So HPCD extraction was a more appropriate and reliable technique to predict bioavailability of PAHs in soil. PMID:27011997

  15. Cancer risk assessment of polycyclic aromatic hydrocarbon contaminated soils determined using bioassay-derived levels of benzo[a]pyrene equivalents.

    PubMed

    Lemieux, Christine L; Long, Alexandra S; Lambert, Iain B; Lundstedt, Staffan; Tysklind, Mats; White, Paul A

    2015-02-01

    Here we evaluate the excess lifetime cancer risk (ELCR) posed by 10 PAH-contaminated soils using (i) the currently advocated, targeted chemical-specific approach that assumes dose additivity for carcinogenic PAHs and (ii) a bioassay-based approach that employs the in vitro mutagenic activity of the soil fractions to determine levels of benzo[a]pyrene equivalents and, by extension, ELCR. Mutagenic activity results are presented in our companion paper.1 The results show that ELCR values for the PAH-containing fractions, determined using the chemical-specific approach, are generally (i.e., 8 out of 10) greater than those calculated using the bioassay-based approach; most are less than 5-fold greater. Only two chemical-specific ELCR estimates are less than their corresponding bioassay-derived values; differences are less than 10%. The bioassay-based approach, which permits estimation of ELCR without a priori knowledge of mixture composition, proved to be a useful tool to evaluate the chemical-specific approach. The results suggest that ELCR estimates for complex PAH mixtures determined using a targeted, chemical-specific approach are reasonable, albeit conservative. Calculated risk estimates still depend on contentious PEFs and cancer slope factors. Follow-up in vivo mutagenicity assessments will be required to validate the results and their relevance for human health risk assessment of PAH-contaminated soils.

  16. Effects of ageing and soil properties on the oral bioavailability of benzo[a]pyrene using a swine model.

    PubMed

    Duan, Luchun; Palanisami, Thavamani; Liu, Yanju; Dong, Zhaomin; Mallavarapu, Megharaj; Kuchel, Tim; Semple, Kirk T; Naidu, Ravi

    2014-09-01

    Oral bioavailability of benzo[a]pyrene (B[a]P) was studied in a swine model using eight spiked soil samples after incubation for 50 and/or 90 days. Silica sand was used as a reference material and the relative bioavailability (RB) of B[a]P in soils was calculated as the quotient of the area under the plasma B[a]P curve (AUC) for soil and AUC for the silica sand. Significantly reduced RB was observed in all study soils after 90 days ageing, ranging from 22.1±0.4% to 62.7±10.1%, except for one very sandy soil (sand content 87.6%) where RB was unchanged (108.1±8.0%). Apart from this, bioavailability decreased during ageing with the decrease (from day 50 to day 90) being only significant for a clayey soil containing expandable clay minerals. Statistical analyses of B[a]P RB at day 90 (eight soils) and soil properties showed no direct correlation between RB and specific soil properties such as total organic carbon (TOC) and clay content which were commonly linked to organic contaminant sequestration. However, strongly significant relationships (p<0.001) were found between RB and the fine particle associated carbon (FPAC) defined as (Silt+Clay)/TOC, and between RB and the soil mesopore (<6nm; p<0.001) fraction, after two samples with high pH and high EC being excluded from the analyses. The bioaccessibility estimated by four in vitro extraction methods: dichloromethane/acetone sonication (DCM/Ace), butanol vortex (BuOH), hydroxypropyl-β-cyclodextrin extraction (HPCD) and Milli Q water leaching methods at different sampling time (1 day, 50 days and 90 days after spiking) also showed a decreasing trend. Significant correlations were found between B[a]P RB and DCM/Ace (R(2)=0.67, p<0.05) extractable fraction and BuOH (R(2)=0.75, p<0.01) extractable fraction. PMID:24937044

  17. Phytoremediation of mixed-contaminated soil using the hyperaccumulator plant Alyssum lesbiacum: evidence of histidine as a measure of phytoextractable nickel.

    PubMed

    Singer, Andrew C; Bell, Thomas; Heywood, Chloe A; Smith, J A C; Thompson, Ian P

    2007-05-01

    In this study we examine the effects of polycyclic aromatic hydrocarbons (PAHs) on the ability of the hyperaccumulator plant Alyssum lesbiacum to phytoextract nickel from co-contaminated soil. Planted and unplanted mesocosms containing the contaminated soils were repeatedly amended with sorbitan trioleate, salicylic acid and histidine in various combinations to enhance the degradation of two PAHs (phenanthrene and chrysene) and increase nickel phytoextraction. Plant growth was negatively affected by PAHs; however, there was no significant effect on the phytoextraction of Ni per unit biomass of shoot. Exogenous histidine did not increase nickel phytoextraction, but the histidine-extractable fraction of soil nickel showed a high correlation with phytoextractable nickel. These results indicate that Alyssum lesbiacum might be effective in phytoextracting nickel from marginally PAH-contaminated soils. In addition, we provide evidence for the broader applicability of histidine for quantifying and predicting Ni phytoavailability in soils. PMID:17084494

  18. Electro-migration of heavy metals in an aged electroplating contaminated soil affected by the coexisting hexavalent chromium.

    PubMed

    Zhang, Weihua; Zhuang, Luwen; Tong, Lizhi; Lo, Irene M C; Qiu, Rongliang

    2012-02-01

    Cr(VI) was often reported to oxidize soil organic matter at acidic environments due to its high ORP, probably thus changing cationic metal species bound to soil organic matter, and influencing their electro-migration patterns. However, such an effect on the electro-migration was not confirmed in most previous studies. Therefore, this study applied a fixed voltage direct current field on an aged electroplating contaminated clayed soil, with a special interest in the direct or indirect influence of Cr(VI) on the electro-migration of other coexisting metals. After 353 h electrokinetic process, 81% of Zn, 53% of Ni and 22% of Cu in the original soil were electro-migrated into the electrolyte, and most of the remaining concentrated near the cathode. The Cr(VI) oxidized some soil organic matter along its migration pathway, with a pronounced reaction occurred near the anode at low pHs. The resulting Cr(III) reversed its original movement, and migrated towards the cathode, leading to the occurrence of a second Cr concentration peak in the soil. Metal species analyses showed that the amount of metals bound to soil organic matter significantly decreased, while a substantial increase in the Cr species bound to Fe/Mn (hydro-)oxides was observed, suggesting an enhancement of cationic metal electro-migration by the reduction of Cr(VI) into Cr(III). However, the Cr(VI) may form some stable lead chromate precipitates, and in turn demobilize Pb in the soil, as the results showed a low Pb removal and an increase in its acid-extractable and residual fractions after electrokinetic remediation. PMID:22197017

  19. Biodegradation of pyrene by Phanerochaete chrysosporium and enzyme activities in soils: effect of SOM, sterilization and aging.

    PubMed

    Wang, Cuiping; Sun, Hongwen; Liu, Haibin; Wang, Baolin

    2014-05-01

    The impacts of soil organic matter (SOM), aging and sterilization on the production of lignin peroxidase (LiP) and manganese peroxidase (MnP) by Phanerochaete chrysosporium during the biodegradation of pyrene in soils were investigated. The biodegradation of pyrene by P. chrysosporium decreased with increasing SOM content, whereas the maximum activities of LiP and MnP increased, which indicates that SOM outweighed pyrene in controlling enzyme production. Sterilization enhanced the degradation of pyrene due to the elimination of competition from indigenous microbes, whereas aging led to a reduction in the degradation of pyrene primarily through changes in its sorbed forms. Both sterilization and aging could reduce SOM content and alter its structure, which also influenced the bioavailability of pyrene and the enzyme activity. The sterilization and aging processes caused changes in the degradation of pyrene, and the enzyme activities were greater in soils with high SOM contents. MnP was related to the degradation of pyrene to a greater extent, whereas LiP was more related to the decomposition of SOM.

  20. Toxicity in lead salt spiked soils to plants, invertebrates and microbial processes: Unraveling effects of acidification, salt stress and ageing reactions.

    PubMed

    Smolders, Erik; Oorts, Koen; Peeters, Sofie; Lanno, Roman; Cheyns, Karlien

    2015-12-01

    The fate and effects of toxic trace metals in soil freshly spiked soluble metal salts do not mimic those of metals in the field. This study was set up to test the magnitude of effects of salinity, acidification, and ageing on toxicity of lead (Pb) to plants, invertebrates and soil microbial processes. Three soils were spiked with Pb2+ salts up to a concentration of 8000 mg Pb/kg and were tested either after spiking, after soil leaching followed by pH correction, or after a 5-year outdoor ageing period with free drainage followed by pH correction. Soil solution ionic strength exceeded 150 mmol/L in soils tested directly after spiking and this decreased partially after leaching and returned back to background values after 5-year outdoor equilibration. Chronic toxicity to two plants, two invertebrates, and three microbial endpoints was consistently found in all spiked soils that were not leached. This toxicity significantly decreased or became absent after 5 years of ageing in 19 of the 20 toxicity tests by a factor 8 (median factor; range: 1.4->50), measured by the factor increase of total soil Pb dose required to induce 10% inhibition. The toxicity of Pb in leached soils was intermediate between the other two treatments. The lowest detectable chronic thresholds (EC10) in aged soils ranged 350-5300 mg Pb/kg. Correlation analysis, including data of Pb2+ speciation in soil solution, suggests that reduced ionic strength rather than acidification or true ageing is the main factor explaining the soil treatment effects after spiking. It is suggested that future toxicity studies should test fine PbO powder as a relevant source for Pb in soils to exclude the confounding salt effects.

  1. PILOT LAND TREATMENT OF PAH-CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Hazardous dredged sediments are typically placed in confined disposal facilities (CDFs) which are designed to dewater and contain but not treat sediments. Since navigational dredging in the U.S. is quickly filling many CDFs, these facilities have little available capacity for ne...

  2. Chemical and microbiological characterization of an aged PCB-contaminated soil.

    PubMed

    Stella, T; Covino, S; Burianová, E; Filipová, A; Křesinová, Z; Voříšková, J; Větrovský, T; Baldrian, P; Cajthaml, T

    2015-11-15

    This study was aimed at complex characterization of three soil samples (bulk soil, topsoil and rhizosphere soil) from a site historically contaminated with polychlorinated biphenyls (PCB). The bulk soil was the most highly contaminated, with a PCB concentration of 705.95 mg kg(-1), while the rhizosphere soil was the least contaminated (169.36 mg kg(-1)). PCB degradation intermediates, namely chlorobenzoic acids (CBAs), were detected in all the soil samples, suggesting the occurrence of microbial transformation processes over time. The higher content of organic carbon in the topsoil and rhizosphere soil than in the bulk soil could be linked to the reduced bioaccessibility (bioavailability) of these chlorinated pollutants. However, different proportions of the PCB congener contents and different bioaccessibility of the PCB homologues indicate microbial biotransformation of the compounds. The higher content of organic carbon probably also promoted the growth of microorganisms, as revealed by phospholipid fatty acid (PFLA) quantification. Tag-encoded pyrosequencing analysis showed that the bacterial community structure was significantly similar among the three soils and was predominated by Proteobacteria (44-48%) in all cases. Moreover, analysis at lower taxonomic levels pointed to the presence of genera (Sphingomonas, Bulkholderia, Arthrobacter, Bacillus) including members with reported PCB removal abilities. The fungal community was mostly represented by Basidiomycota and Ascomycota, which accounted for >80% of all the sequences detected in the three soils. Fungal taxa with biodegradation potential (Paxillus, Cryptococcus, Phoma, Mortierella) were also found. These results highlight the potential of the indigenous consortia present at the site as a starting point for PCB bioremediation processes.

  3. Sentinel surveillance of soil-transmitted helminthiasis in preschool-aged and school-aged children in selected local government units in the Philippines: follow-up assessment.

    PubMed

    Belizario, Vicente Y; Totañes, Francis Isidore G; de Leon, Winifreda U; Ciro, Raezelle Nadine T; Lumampao, Yvonne F

    2015-03-01

    This study was a follow-up to the baseline nationwide survey of soil-transmitted helminth (STH) infections in preschool-aged children in the Philippines and in school-aged children in selected sentinel sites to assess the Integrated Helminth Control Program of the Department of Health. The objective of the study was to describe the current prevalence and intensity of STH infections in preschool-aged and school-aged children in 6 sentinel provinces and to compare these data with baseline findings. A cross-sectional study design was used to determine the prevalence and intensity of STH infections. Parasitological assessment involved the examination of stool samples by the Kato-Katz method. Although parasitological parameters in the 2 age groups at follow-up showed significant reductions from the baseline, these parameters remained high despite 3 years of mass drug administration (MDA). Efforts toward achieving high MDA coverage rates, provision of clean water, environmental sanitation, and promotion of hygiene practices must be prioritized.

  4. Forest age stands affect soil respiration and litterfall in a Black pine forest managed by a shelterwood system in the Central Spain?

    NASA Astrophysics Data System (ADS)

    Hedo de Santiago, Javier; Borja, Manuel Esteban Lucas; Candel, David; Viñegla Pérez, Benjamin

    2016-04-01

    This study aims to investigate the effects that stand age and forest structure generates on soil respiration and litterfall quantity. The effect of stand age on these variables was studied in a shelterwood system Spanish Black pine chronosequence in central Iberian Peninsula composed of 0-20, 20-40, 40-60, 60-80, 80-100-year-old. For each stand age, six forest stands with similar characteristics of soil type and site preparation were used. Also, a forest area ranging 80-120 years old and without forest intervention was selected and used as control. We also measured organic matter, C:N ratio, soil moisture and pH in the top 10 mineral soil at each compartment. Soil respiration measurements were carried out in three time points (3, 8 and 12 days). Results showed a clear trend in soil respiration, comparing all the experimental areas. Soil respiration showed the same trend in all stands. It initially showed higher rates, reaching stability in the middle of the measurement process and finally lightly increasing the respiration rate. The older stands had significantly higher soil respiration than the younger stands. Soil organic matter values were also higher in the more mature stands. C:N ratio showed the opposite trend, showing lower values in the less mature stands. More mature stands clearly showed more quantity of litterfall than the younger ones and there was a positive correlation between soil respiration and litterfall. Finally, the multivariate PCA analysis clearly clustered three differenced groups: Control plot; from 100 to 40 years old and from 39 to 1 years old, taking into account both soil respiration and litterfall quantity, also separately. Our results suggest that the control plot has a better soil quality and that extreme forest stand ages (100-80 and 19-1 years old) and the associated forest structure generates differences in soil respiration.

  5. Design and field-scale implementation of an "on site" bioremediation treatment in PAH-polluted soil.

    PubMed

    Pelaez, A I; Lores, I; Sotres, A; Mendez-Garcia, C; Fernandez-Velarde, C; Santos, J A; Gallego, J L R; Sanchez, J

    2013-10-01

    An "on site" bioremediation program was designed and implemented in soil polluted with polycyclic aromatic hydrocarbons (PAHs), especially naphthalene. We began by characterizing the soil's physical and chemical properties. A microbiological screening corroborated the presence of microorganisms capable of metabolizing PAHs. We then analyzed the viability of bioremediation by developing laboratory microcosms and pilot scale studies, to optimize the costs and time associated with remediation. The treatment assays were based on different types of biostimulants, such as a slow or fast-release fertilizer, combined with commercial surfactants. Once the feasibility of the biostimulation was confirmed, a real-scale bioremediation program was undertaken in 900 m(3) of contaminated soil. The three-step design reduced PAH contamination by 94.4% at the end of treatment (161 days). The decrease in pollutants was concomitant with the selection of autochthonous bacteria capable of degrading PAHs, with Bacillus and Pseudomonas the most abundant genera.

  6. Impact of Zn, Cu, Al and Fe on the partitioning and bioaccessibility of (14)C-phenanthrene in soil.

    PubMed

    Obuekwe, Ifeyinwa S; Semple, Kirk T

    2013-09-01

    This investigation considered the effects of Zn, Cu, Al and Fe (50 and 500 mg kg(-1)) on the loss, sequential extractability, using calcium chloride (CaCl2), hydroxypropyl-β-cyclodextrin (HPCD) and dichloromethane (DCM) and biodegradation of (14)C-phenanthrene in soil over 63 d contact time. The key findings were that the presence of Cu and Al (500 mg kg(-1)) resulted in larger amounts of (14)C-phenanthrene being extracted by CaCl2 and HPCD. Further, the CaCl2 + HPCD extractions directly predicted the biodegradation of the PAH in the presence of the metals, with the exception of 500 mg kg(-1) Cu and Zn. The presence of high concentrations of some metals can impact on the mobility and accessibility of phenanthrene in soil, which may impact on the risk assessment of PAH contaminated soil. PMID:23770460

  7. Analysis and Sources of Polycyclic Aromatic Hydrocarbons in Soil and Plant Samples of a Coal Mining Area in Nigeria.

    PubMed

    Ugwu, K E; Ukoha, P O

    2016-03-01

    This study analysed coal, plant and soil samples collected from the vicinity of Okobo coal mine in Nigeria for Polycyclic aromatic hydrocarbons (PAHs) and evaluated the sources of the PAH contamination in the environmental samples. The environmental samples were extracted by sonication using a ternary solvent system and analysed for 16 PAHs by gas chromatography-mass spectrometry (GC-MS). The results of the analysis of the samples identified some of the target PAHs. The ranges of total concentrations (in mg/kg) of PAHs in the coal, plant and soil samples were, 0.00-0.04, 0.00-0.16 and 0.00-0.01 respectively. The evaluation of the results of the PAH analysis of the environmental samples using diagnostic ratios revealed that the PAHs in the soil samples were mainly of petrogenic origin, while those in plant samples indicated mixture of petrogenic and pyrolytic origins.

  8. Effects, uptake, and fate of 2,4,6-trinitrotoluene aged in soil in plants and worms.

    PubMed

    Best, Elly P H; Tatem, Henry E; Geter, Kaaren N; Wells, Melissa L; Lane, Brian K

    2008-12-01

    The present study was aimed at providing data to be used at predicting exposure-based effects of 2,4,6-trinitrotoluene (TNT) aged in soil on endpoint organisms representing two trophic levels. These data can be used to define criteria or reference values for environmental management and conducting specific risk assessment. Long-term exposure tests were conducted to evaluate sublethal toxicity and uptake of aged soil-based explosives, with TNT as the main contaminant. In these tests, plants were exposed for 55 d, and biomass and explosives residues were determined. Worms were exposed for 28 and 42 d, and biomass, number, and tissue residues were determined. Biomass of Lolium perenne significantly decreased with soil-TNT concentration, and an effective concentration causing a 20% decrease in biomass (EC20) for TNT metabolites of 3.75 mg/kg was calculated. The concentrations of TNT metabolites in shoots and roots were significantly related to concentrations in soil, as were concentrations of hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The mean bioconcentration factors, indicating the potential of a chemical to accumulate in an organism, were 0.9 for TNT metabolites, 71.8 for RDX, and 12.2 for HMX in L. perenne shoots. Biomass of Eisenia fetida adults significantly decreased with soil-TNT concentration, and an EC20 for TNT of 3.70 mg/kg was calculated. The TNT, RDX, and HMX levels in E. fetida were below detection.

  9. Unravelling the importance of forest age stand and forest structure driving microbiological soil properties, enzymatic activities and soil nutrients content in Mediterranean Spanish black pine(Pinus nigra Ar. ssp. salzmannii) Forest.

    PubMed

    Lucas-Borja, M E; Hedo, J; Cerdá, A; Candel-Pérez, D; Viñegla, B

    2016-08-15

    This study aimed to investigate the effects that stand age and forest structure have on microbiological soil properties, enzymatic activities and nutrient content. Thirty forest compartments were randomly selected at the Palancares y Agregados managed forest area (Spain), supporting forest stands of five ages; from 100 to 80years old to compartments with trees that were 19-1years old. Forest area ranging from 80 to 120years old and without forest intervention was selected as the control. We measured different soil enzymatic activities, soil respiration and nutrient content (P, K, Na, Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb and Ca) in the top cm of 10 mineral soils in each compartment. Results showed that the lowest forest stand age and the forest structure created by management presented lower values of organic matter, soil moisture, water holding capacity and litterfall and higher values of C/N ratio in comparison with the highest forest stand age and the related forest structure, which generated differences in soil respiration and soil enzyme activities. The forest structure created by no forest management (control plot) presented the highest enzymatic activities, soil respiration, NH4(+) and NO3(-). Results did not show a clear trend in nutrient content comparing all the experimental areas. Finally, the multivariate PCA analysis clearly clustered three differentiated groups: Control plot; from 100 to 40years old and from 39 to 1year old. Our results suggest that the control plot has better soil quality and that extreme forest stand ages (100-80 and 19-1years old) and the associated forest structure generates differences in soil parameters but not in soil nutrient content.

  10. [Effects of aging time on the form transformation and eco-toxicity threshold (ECx) of added Zn in typical China soils].

    PubMed

    Lin, Lei; Chen, Shi-Bao; Liu, Ji-Fang; Ma, Yi-Bing

    2013-07-01

    Six typical China soils with different properties were selected and added with seven concentrations of ZnCl2 to study the effects of different aging time (14, 90, 180, 360, and 540 days) on the form transformation and eco-toxicity threshold (ECx) of added Zn in the soils, with the main affecting factors analyzed. The results indicated that with the increase of aging time, the fraction of 0.01 mol x L(-1) CaCl2-extracted Zn in the soils decreased sharply initially, then slowed down, and reached the dynamic balance after 540 d incubation. The eco-toxicity thresholds (ECx, x = 10, 50) of Zn to bok choy increased significantly with aging time (P < 0.05), which implied the marked decrease of the phyto-toxicity of Zn. The measured aging factors AF10 and AF50 of Zn ranged from 1.077-1.743 and 1.174-1.441, respectively, and increased with aging time. The balanced concentration of Zn in the soils was significantly negatively correlated with soil pH, CEC, and organic carbon (Org-C) content, and soil pH was the most important controlling factor, followed by CEC and Org-C. It took shorter time to reach Zn balance in the soils with higher pH. The prediction model of the ECx of Zn was developed based on the aging factors and the main soil properties, and could be well validated by the measured ECx under field condition. This study would provide theoretical basis for the normalization of the eco-toxicity thresholds of added Zn in different soils and the formulation of the environmental criterion of Zn in China soils.

  11. [Effects of aging time on the form transformation and eco-toxicity threshold (ECx) of added Zn in typical China soils].

    PubMed

    Lin, Lei; Chen, Shi-Bao; Liu, Ji-Fang; Ma, Yi-Bing

    2013-07-01

    Six typical China soils with different properties were selected and added with seven concentrations of ZnCl2 to study the effects of different aging time (14, 90, 180, 360, and 540 days) on the form transformation and eco-toxicity threshold (ECx) of added Zn in the soils, with the main affecting factors analyzed. The results indicated that with the increase of aging time, the fraction of 0.01 mol x L(-1) CaCl2-extracted Zn in the soils decreased sharply initially, then slowed down, and reached the dynamic balance after 540 d incubation. The eco-toxicity thresholds (ECx, x = 10, 50) of Zn to bok choy increased significantly with aging time (P < 0.05), which implied the marked decrease of the phyto-toxicity of Zn. The measured aging factors AF10 and AF50 of Zn ranged from 1.077-1.743 and 1.174-1.441, respectively, and increased with aging time. The balanced concentration of Zn in the soils was significantly negatively correlated with soil pH, CEC, and organic carbon (Org-C) content, and soil pH was the most important controlling factor, followed by CEC and Org-C. It took shorter time to reach Zn balance in the soils with higher pH. The prediction model of the ECx of Zn was developed based on the aging factors and the main soil properties, and could be well validated by the measured ECx under field condition. This study would provide theoretical basis for the normalization of the eco-toxicity thresholds of added Zn in different soils and the formulation of the environmental criterion of Zn in China soils. PMID:24175536

  12. Sorption Characteristic of Phenanthrene on Biochar-Amended Soils: Effect of feedstock, pyrolysis temperature, and aging duration

    NASA Astrophysics Data System (ADS)

    Hyun, S.; Kim, C.; Kim, Y. S.; Kim, J.

    2015-12-01

    The high sorption capacity of biochar is widely known in environmental studies. Especially, biochar is effective for removal of hydrophobic organic compounds (HOCs) due to high surface area and porosity. In this study, the sorption characteristic of biochar-amended soil was evaluated by sorption kinetic experiment of phenanthrene (PHE). For PHE sorption test, the effect of biochar feedstock (sludge waste char (SWC), municipal waste char (MWC) and wood char (WC), Giant Miscanthus (GM)), pyrolysis temperature (400°C, 500°C and 700°C,), and duration of amending period (0, 3, 6, and 12 months) was assessed. Field Emission-Scanning Electron Microscopy (FE-SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR) techniques were used to detect pore structure and the surface functional group of biochar amended soils. For all kinetic tests, apparent sorption equilibrium was attained in 24 hr. The result showed that sorption capacity of biochar amended soils was greatly influenced by biochar feedstock and pyrolysis temperature. For all samples, the sorption capacity of PHE by biochar amended soils decreased with aging period. This observation is due to the fact that the aromatic characters of biochar are different by feedstock and pyrolysis temperature and the amount of O-containing hydrophilic functional groups increased surfaces of biochar by natural oxidation (e.g. carboxyl groups) as confirmed by the result of FT-IR and FE-SEM. In addition, biochar pore blockage by inorganic minerals, which tended to increase with aging period, might attenuate the sorption capacity of samples. In conclusion, biochar derived from various feed stocks are all effective for PHE sorption. But the sorption capacity of biochar amended soils decreased with increasing aging duration most likely due to increasing hydrophilic functional groups of biochar surfaces and pore blockage by inorganic minerals in the weathering processes. Therefore, for the design of biochar amendment to attenuate

  13. Determining soil-transmitted helminth infection status and physical fitness of school-aged children.

    PubMed

    Yap, Peiling; Fürst, Thomas; Müller, Ivan; Kriemler, Susi; Utzinger, Jürg; Steinmann, Peter

    2012-01-01

    Soil-transmitted helminth (STH) infections are common. Indeed, more than 1 billion people are affected, mainly in the developing world where poverty prevails and hygiene behavior, water supply, and sanitation are often deficient. Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Ancylostoma duodenale and Necator americanus, are the most prevalent STHs. The estimated global burden due to hookworm disease, ascariasis, and trichuriasis is 22.1, 10.5, and 6.4 million disability-adjusted life years (DALYs), respectively. Furthermore, an estimated 30-100 million people are infected with Strongyloides stercoralis, the most neglected STH species of global significance which arguably also causes a considerable public health impact. Multiple-species infections (i.e., different STHs harbored in a single individual) are common, and infections have been linked to lowered productivity and thus economic outlook of developing countries. For the diagnosis of common STHs, the World Health Organization (WHO) recommends the Kato-Katz technique, which is a relatively straightforward method for determining the prevalence and intensity of such infections. It facilitates the detection of parasite eggs that infected subjects pass in their feces. With regard to the diagnosis of S. stercoralis, there is currently no simple and accurate tool available. The Baermann technique is the most widely employed method for its diagnosis. The principle behind the Baermann technique is that active S. stercoralis larvae migrate out of an illuminated fresh fecal sample as the larvae are phototactic. It requires less sophisticated laboratory materials and is less time consuming than culture and immunological methods. Morbidities associated with STH infections range from acute but common symptoms, such as abdominal pain, diarrhea, and pruritus, to chronic symptoms, such as anemia, under- and malnutrition, and cognitive impairment. Since the symptoms are generally unspecific and subtle

  14. Determining Soil-transmitted Helminth Infection Status and Physical Fitness of School-aged Children

    PubMed Central

    Yap, Peiling; Fürst, Thomas; Müller, Ivan; Kriemler, Susi; Utzinger, Jürg; Steinmann, Peter

    2012-01-01

    Soil-transmitted helminth (STH) infections are common. Indeed, more than 1 billion people are affected, mainly in the developing world where poverty prevails and hygiene behavior, water supply, and sanitation are often deficient1,2. Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Ancylostoma duodenale and Necator americanus, are the most prevalent STHs3. The estimated global burden due to hookworm disease, ascariasis, and trichuriasis is 22.1, 10.5, and 6.4 million disability-adjusted life years (DALYs), respectively4. Furthermore, an estimated 30-100 million people are infected with Strongyloides stercoralis, the most neglected STH species of global significance which arguably also causes a considerable public health impact5,6. Multiple-species infections (i.e., different STHs harbored in a single individual) are common, and infections have been linked to lowered productivity and thus economic outlook of developing countries1,3. For the diagnosis of common STHs, the World Health Organization (WHO) recommends the Kato-Katz technique7,8, which is a relatively straightforward method for determining the prevalence and intensity of such infections. It facilitates the detection of parasite eggs that infected subjects pass in their feces. With regard to the diagnosis of S.stercoralis, there is currently no simple and accurate tool available. The Baermann technique is the most widely employed method for its diagnosis. The principle behind the Baermann technique is that active S.stercoralis larvae migrate out of an illuminated fresh fecal sample as the larvae are phototactic9. It requires less sophisticated laboratory materials and is less time consuming than culture and immunological methods5. Morbidities associated with STH infections range from acute but common symptoms, such as abdominal pain, diarrhea, and pruritus, to chronic symptoms, such as anemia, under- and malnutrition, and cognitive impairment10. Since the symptoms are generally

  15. Aging effect on Zn retention on a calcareous soil: column experiments and synchrotron X-ray micro-spectroscopic investigation.

    PubMed

    Sayen, Stéphanie; Guillon, Emmanuel

    2014-07-15

    In this study, a combination of column experiments and micro-analytical techniques exploiting synchrotron generated X-rays was used to assess the effect of aging time on Zn retention and mobility in the specific case of calcareous soils (high pH value, ≈ 8). The samples were subjected to aging for 2, 6, 17, and 63 days. Freshly added Zn mainly existed as an exchangeable form, and this metal fraction decreased over time due to Zn redistribution to stronger binding sites. Thus, after aging for 63 days, 45% of Zn is remobilized from exchangeable sites to stronger binding sites. μ-XRF maps were used to find correlations among elements in the sample, and μ-XANES spectra were recorded to precise Zn speciation. These analyses evidenced an increasing partitioning of Zn from organic matter to iron oxy(hydr)oxides over time. The occurrence of hydrozincite is evidenced in all samples.

  16. The AgroEcoSystem (AgES) response-function model simulates layered soil water dynamics in semi-arid Colorado: sensitivity and calibration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simulation of vertical soil hydrology is a critical component of simulating even more complex soil water dynamics in space and time, including land-atmosphere and subsurface interactions. The AgroEcoSystem (AgES) model is defined here as a single land unit implementation of the full AgES-W (Watershe...

  17. Identification and quantification of biomarkers and polycyclic aromatic hydrocarbons (PAHs) in an aged mixed contaminated site: from source to soil.

    PubMed

    Kao, Nien-Hsin; Su, Ming-Chien; Fan, Jheng-Rong; Chung, Ying-Yung

    2015-05-01

    The sources of the spill and the contaminated soils of an aged oil spill contaminated site with unknown mixed pollutants were investigated by using a set of developed forensic chemical procedures which include analysis of oil products, site investigation, gas chromatography/mass spectrometry (GC/MS) screening, biomarker identification, and finally, the confirmation of pollutants. Adamantanes (17 compounds), 10 bicyclic sesquiterpanes, 6 newly detected compounds, 16 polycyclic aromatic hydrocarbons, and 10 alkylated naphthalenes compounds in several gasoline, diesel oil samples, and contaminated soil samples were examined and quantified. GC/MS method, retention indices, relative response factors, and diagnostic ratio were used to identify and quantify pollutant compounds. The study revealed the key factors for distinguishing among gasoline and diesel oil products in the market, created a new set of retention indices for 10 bicyclic sesquiterpane compounds, and discovered 6 quantifiable compounds in analysis of fresh oil products. The suggested diagnostic ratios for BSs and the new compounds in the analysis of the biomarker show the differences among diesel products, link between the source of pollutants with contaminated soil, and the recognition of the signs of an aged spill, and the indications of weathering effects. PMID:25712884

  18. Biodegradation of aged diesel in diverse soil matrixes: impact of environmental conditions and bioavailability on microbial remediation capacity.

    PubMed

    Sutton, Nora B; van Gaans, Pauline; Langenhoff, Alette A M; Maphosa, Farai; Smidt, Hauke; Grotenhuis, Tim; Rijnaarts, Huub H M

    2013-07-01

    While bioremediation of total petroleum hydrocarbons (TPH) is in general a robust technique, heterogeneity in terms of contaminant and environmental characteristics can impact the extent of biodegradation. The current study investigates the implications of different soil matrix types (anthropogenic fill layer, peat, clay, and sand) and bioavailability on bioremediation of an aged diesel contamination from a heterogeneous site. In addition to an uncontaminated sample for each soil type, samples representing two levels of contamination (high and low) were also used; initial TPH concentrations varied between 1.6 and 26.6 g TPH/kg and bioavailability between 36 and 100 %. While significant biodegradation occurred during 100 days of incubation under biostimulating conditions (64.4-100 % remediation efficiency), low bioavailability restricted full biodegradation, yielding a residual TPH concentration. Respiration levels, as well as the abundance of alkB, encoding mono-oxygenases pivotal for hydrocarbon metabolism, were positively correlated with TPH degradation, demonstrating their usefulness as a proxy for hydrocarbon biodegradation. However, absolute respiration and alkB presence were dependent on soil matrix type, indicating the sensitivity of results to initial environmental conditions. Through investigating biodegradation potential across a heterogeneous site, this research illuminates the interplay between soil matrix type, bioavailability, and bioremediation and the implications of these parameters for the effectiveness of an in situ treatment.

  19. Bacterial biodegradation of melamine-contaminated aged soil: influence of different pre-culture media or addition of activation material.

    PubMed

    Hatakeyama, Takashi; Takagi, Kazuhiro

    2016-08-01

    This study aimed to investigate the biodegrading potential of Arthrobacter sp. MCO, Arthrobacter sp. CSP, and Nocardioides sp. ATD6 in melamine-contaminated upland soil (melamine: approx. 10.5 mg/kg dry weight) after 30 days of incubation. The soil sample used in this study had undergone annual treatment of lime nitrogen, which included melamine; it was aged for more than 10 years in field. When R2A broth was used as the pre-culture medium, Arthrobacter sp. MCO could degrade 55 % of melamine after 30 days of incubation, but the other strains could hardly degrade melamine (approximately 25 %). The addition of trimethylglycine (betaine) in soil as an activation material enhanced the degradation rate of melamine by each strain; more than 50 % of melamine was degraded by all strains after 30 days of incubation. In particular, strain MCO could degrade 72 % of melamine. When the strains were pre-cultured in R2A broth containing melamine, the degradation rate of melamine in soil increased remarkably. The highest (72 %) melamine degradation rate was noted when strain MCO was used with betaine addition.

  20. Bacterial biodegradation of melamine-contaminated aged soil: influence of different pre-culture media or addition of activation material.

    PubMed

    Hatakeyama, Takashi; Takagi, Kazuhiro

    2016-08-01

    This study aimed to investigate the biodegrading potential of Arthrobacter sp. MCO, Arthrobacter sp. CSP, and Nocardioides sp. ATD6 in melamine-contaminated upland soil (melamine: approx. 10.5 mg/kg dry weight) after 30 days of incubation. The soil sample used in this study had undergone annual treatment of lime nitrogen, which included melamine; it was aged for more than 10 years in field. When R2A broth was used as the pre-culture medium, Arthrobacter sp. MCO could degrade 55 % of melamine after 30 days of incubation, but the other strains could hardly degrade melamine (approximately 25 %). The addition of trimethylglycine (betaine) in soil as an activation material enhanced the degradation rate of melamine by each strain; more than 50 % of melamine was degraded by all strains after 30 days of incubation. In particular, strain MCO could degrade 72 % of melamine. When the strains were pre-cultured in R2A broth containing melamine, the degradation rate of melamine in soil increased remarkably. The highest (72 %) melamine degradation rate was noted when strain MCO was used with betaine addition. PMID:27080407

  1. Bioavailability to grains of rice of aged and fresh DDD and DDE in soils.

    PubMed

    Yao, Fenxia; Yu, Guifen; Bian, Yongrong; Yang, Xinglun; Wang, Fang; Jiang, Xin

    2007-05-01

    DDT had been widely used around the world before 1980s and is still under production and use for non-agricultural purposes in China. Because of their special physicochemical properties, p,p'-DDT and its main metabolites, p,p'-DDD and p,p'-DDE, accumulated and persisted in the environment, presenting potential menace on biota. A green-house study was conducted to determine the bioavailability of p,p'-DDD and p,p'-DDE to grains of rice and the influences of traditional Chinese farming practices on their bioaccumulation. Paddy rice and dry rice were grown in submerged paddy soils and non-submerged upland soils, respectively. Two types of soil, Hydragric Anthrosols (An) and Hydragric Acrisols (Ac), were employed. Bioaccumulation factors (BAFs) of DDE ranged from 0.67 for rice grown in non-submerged An to 0.84 in submerged An in the control group, whilst BAFs were all below 0.04 in experimental groups. BAFs of DDD varied from 1.39 for submerged An to 2.26 for submerged Ac in original soils. In contrast, BAFs were between 0.05 for non-submerged Ac and 0.08 for submerged An in DDD-contaminated soils. Flooding seemed to have two contradictory effects on the DDE/DDD accumulation by rice: on one hand, it made the pollutants more mobile and bioavailable; while on the other hand, it enhanced the degradation and binding of POPs. Adding rice straw to the soils protected DDE from being taken up yet promoted DDD accumulation by rice. Furthermore, the distinct inorganic component of the soils might also play an important role in the environmental activities of POPs.

  2. Mobility and age of black carbon in two temperate grassland soils revealed by differential scanning calorimetry and radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Leifeld, Jens; Feng, Xiaojuan; Eglinton, Timothy; Wacker, Lukas

    2015-04-01

    Black carbon (BC) is a natural component of soil organic matter (SOM) and abundant in many ecosystems. Its stability, due to its relative resistance to microbial decomposition, means it plays an important role in soil C sequestration. A recent review suggests that BC may be mobile in soil; hence, its contribution to a stable SOM pool may change over time due to its lateral or vertical reallocation (Rumpel et al. 2014). However, direct evidence of the mobility of BC, particularly with reference to its vertical mobility, is scarce. We studied the amount of BC in two temperate grassland fields (eutric clayey Camibsol,) that were established in 2001 on former cropland. Volumetric soil samples (0-50 cm, 5 cm increments) were taken at 10 spots in each field in 2001, 2006 and 2011. One of the fields was ploughed in 2007 and the sward was re-sown. BC content was measured by differential scanning calorimetry for a total number of c. 500 samples. The mean BC/OC ratio was 0.10 (±0.05) and reached 0.25 in some samples. Radiocarbon measurements from 24 bulk soil samples revealed relatively small 14C contents in 2001 (92±2.7 pMC) which increased over time (2006: 99.0±1.1 pMC; 2011: 99.1±1.1 pMC). Thermal fractionation of BC by DSC revealed calibrated BC ages of 400 to 1000 years (pMC 87-94), suggesting that BC originates from medieval and post-medieval fire clearings. The change in soil signature may have been caused by a preferential transport of old BC down the soil profile, leading to a selective enrichment of younger soil C over time. In line with this interpretation the DSC measurements suggest that in both fields, BC concentrations significantly decreased for most layers between 2001 and 2006. However, between 2006 and 2011, no further vertical reallocation was observed in the continuous grassland, whereas BC contents of the field ploughed in 2007 significantly increased in the top layers. Together, these data suggest that ploughing in 2001 triggered subsequent

  3. Polycyclic aromatic hydrocarbon removal from contaminated soils using fatty acid methyl esters.

    PubMed

    Gong, Zongqiang; Wang, Xiaoguang; Tu, Ying; Wu, Jinbao; Sun, Yifei; Li, Peng

    2010-03-01

    In this study, solubilization of PAHs from a manufactured gas plant (MGP) soil and two artificially spiked soils using fatty acid methyl esters (FAME) was investigated. PAH removals from both the MGP and the spiked soils by FAME, methanol, soybean oil, hydroxypropyl-beta-cyclodextrin, Triton X-100, and Tween 80 were compared. The effect of FAME:MGP soil ratios on PAH removals was also investigated. Results showed that the FAME mixture synthesized by our lab was more efficient than the cyclodextrin and the two surfactants used for PAH removal from the spiked soils with individual PAH concentrations of 200 and 400 mg kg(-1). However, the difference among three PAH removals by the FAME, soybean oil and methanol was not quite pronounced. The FAME synthesized and market biodiesel exhibited better performance for PAH removals (46% and 35% of total PAH) from the weathered contaminated MGP soil when compared with the other agents (0-31%). Individual PAH removals from the weathered MGP soil were much lower than those from the spiked soils. The percentages of total PAH removals from the MGP soil were 59%, 46%, and 51% for the FAME:MGP soil ratios of 1:2, 1:1, and 2:1, respectively. These results showed that the FAME could be a more attractive alternative to conventional surfactants in ex situ washing of PAH-contaminated soils. PMID:20149410

  4. Environmental fate of the herbicide MCPA in agricultural soils amended with fresh and aged de-oiled two-phase olive mill waste.

    PubMed

    Peña, David; López-Piñeiro, Antonio; Albarrán, Ángel; Becerra, Daniel; Sánchez-Llerena, Javier

    2015-09-01

    Olive oil agrifood industry generates large amounts of waste whose recycling as organic amendment represents an alternative to their disposal. The impact of de-oiled two-phase olive mill waste (DW) on the fate of 4-chloro-2-methylphenoxyacetic acid (MCPA) in Mediterranean agricultural soils was evaluated. Furthermore, the effect of the transformation of organic matter from this waste under field conditions was assessed. Four Mediterranean agricultural soils were selected and amended in laboratory with fresh DW and field-aged DW (DW and ADW treatments, respectively). Adsorption capacity increased by factors between 1.18 and 3.59, for the DW-amended soils, and by factor of 4.93, for ADW-amended soil, with respect to unamended soils, when 5% amendment was applied. The DW amendment had inhibitory effect on dehydrogenase activity and slowed herbicide dissipation, whereas the opposite effect was observed in ADW treatments. In the field-amended soil, the amount of MCPA leached was significantly reduced from 56.9% for unamended soil to 15.9% at the 5% rate. However, leaching losses of MCPA increased in the laboratory-amended soils, because of their high water-soluble organic carbon values which could enhance MCPA mobility, especially in the acidic soils. Therefore, the application of DW as organic amendment in Mediterranean agricultural soils could be an important management strategy to reduce MCPA leaching, especially if the organic matter had been previously transformed by ageing processes.

  5. U-ages in soils and groundwater evidencing wet periods 400-600kyr ago in southeast Brazil.

    PubMed

    Bonotto, D M; Jiménez-Rueda, J R

    2007-07-01

    (238)U and its radiogenic daughter (234)U have been utilized for dating soil formation and groundwater residence time during the last 1.5 million years, in this case based on the U-dissolution/precipitation occurring during modifications of the oxidation-reduction conditions. In this paper, we report a 400-600kyr proxy of wet periods from sediments occurring in a soil profile developed over rocks outcropping at the Paraná sedimentary basin in Brazil, and from groundwater exploited of Guarani aquifer at the same basin. The approaches indicated successful use of the U-modeled ages for suggesting wet periods exceeding the past 116-210kyr from previous studies.

  6. Mt. Blanco revisited: soil-geomorphic implications for the ages of the upper Cenozoic Blanco and Blackwater Draw Formations

    SciTech Connect

    Holliday, V.T.

    1988-06-01

    Mt. Blanco, on the eastern edge of the Southern High Plains of Texas, contains stratigraphic features significant in interpreting the late Cenozoic history of the region and the vertebrate paleontology of the Great Plains; however, the stratigraphic relations are confused in the literature or are unreported. Mt. Blanco is the type locality for the Blanco Formation and the Blanco Local Fauna, which occurs throughout North America and is the type fauna for the Blancan Land Mammal Age in North America. Here also occur exposures of the Blackwater Draw Formation, an extensive (120,000 km/sup 2/) eolian sheet that is the surficial cover of the region and contains the 1.4 Ma Guaje Ash and several buried soils. A reexamination of the section shows that (1) the Blackwater Draw Formation, an eolian deposit, contains three well-expressed buried soils (5 YR hues, argillic horizons greater than or equal to 1 m thick, Stages III and IV calcic horizons) and the similar regional surface soil (Paleustalf); (2) the Guaje Ash is within the lower Blackwater Draw Formation but is separated from the Blanco Formation, a lacustrine unit, by about 1 m of sediment, including the lowest buried soil; and (3) the lowest buried soil shows a Stage IV calcrete formed at the top of the Blanco Formation and the base of the Blackwater Draw Formation and probably took about 200 ka to form. These new data suggested that deposition of the type Blanco sediments may have ended by about 1.6 Ma or earlier. Since that time, the Blackwater Draw Formation has accumulated episodically; periods of nondeposition are characterized by landscape stability and pedogenesis.

  7. Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth.

    PubMed

    Gong, Zongqiang; Li, Peijun; Wilke, B M; Alef, Kassem

    2008-01-01

    Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soil for a remediation purpose, with some of the oil remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soil was not known. The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soil properties after soil extraction for a better understanding of the soil remediation. Addition of sunflower oil and column experiment were performed on a PAH contaminated soil and/or a control soil, respectively. Soils were incubated for 90 d, and soil pH was measured during the soil incubation. Higher plant growth bioassays with Avena sativa L. (oat) and Brassica rapa L. (turnip) were performed after the incubation, and then soil organic carbon contents were measured. The results show that both the nutrient amendment and the sunflower oil degradation resulted in the decrease of soil pH. When these two process worked together, their effects were counteracted due to the consumption of the nutrients and oil removal, resulting in different pH profiles. Growth of A. sativa was adversely affected by the sunflower oil, and the nutrient amendments stimulated the A. sativa growth significantly. B. rapa was more sensitive to the sunflower oil than A. sativa. Only 1% sunflower oil addition plus nutrient amendment stimulated B. rapa growth. All the other treatments on B. rapa inhibited its growth significantly. The degradation of the sunflower oil in the soils was proved by the soil organic carbon content.

  8. Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth.

    PubMed

    Gong, Zongqiang; Li, Peijun; Wilke, B M; Alef, Kassem

    2008-01-01

    Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soil for a remediation purpose, with some of the oil remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soil was not known. The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soil properties after soil extraction for a better understanding of the soil remediation. Addition of sunflower oil and column experiment were performed on a PAH contaminated soil and/or a control soil, respectively. Soils were incubated for 90 d, and soil pH was measured during the soil incubation. Higher plant growth bioassays with Avena sativa L. (oat) and Brassica rapa L. (turnip) were performed after the incubation, and then soil organic carbon contents were measured. The results show that both the nutrient amendment and the sunflower oil degradation resulted in the decrease of soil pH. When these two process worked together, their effects were counteracted due to the consumption of the nutrients and oil removal, resulting in different pH profiles. Growth of A. sativa was adversely affected by the sunflower oil, and the nutrient amendments stimulated the A. sativa growth significantly. B. rapa was more sensitive to the sunflower oil than A. sativa. Only 1% sunflower oil addition plus nutrient amendment stimulated B. rapa growth. All the other treatments on B. rapa inhibited its growth significantly. The degradation of the sunflower oil in the soils was proved by the soil organic carbon content. PMID:19209632

  9. Changes in sorption of indaziflam and three transformation products in soil with aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To evaluate environmental risks of pesticides in soil it is necessary to study the effect of contact time on sorption-desorption processes. This has been reported for a number of pesticides, however few studies have been carried out on the metabolites arising from the degradation of these chemicals....

  10. Plant-enhanced phenanthrene and pyrene biodegradation in acidic soil.

    PubMed

    Chouychai, Waraporn; Thongkukiatkul, Amporn; Upatham, Suchart; Lee, Hung; Pokethitiyook, Prayad; Kruatrachue, Maleeya

    2009-01-01

    A study was undertaken to assess if corn plant (Zea may L.) maybe able to enhance the degradation of phenanthrene and pyrene in acidic soil inoculated with a bacterial strain (Pseudomonas putida MUB1) capable of degrading polycyclic aromatic hydrocarbons (PAHs). Planting with corn, inoculating with MUB1, ora combination of the two were found to promote the degradation of phenanthrene and pyrene in acidic soil at different rates. In the presence of corn plants, the rates of phenanthrene and pyrene removal were 41.7 and 38.8% in the first 10 days, while the rates were 58.8 and 53.6%, respectively in the treatment which received MUB1 only. After 60 days, the corn + MUB1 treatment led to the greatest reduction in both phenanthrene and pyrene biodegradation (89 and 88.2%, respectively). In control autoclaved soil, the rates of phenanthrene and pyrene removal were 14.2 and 28.7%, respectively while in non-autoclaved soil, the rates were 68.7 and 53.2%, respectively. These results show that corn, which was previously shown to grow well in PAH-contaminated acidic soil, also can enhance PAH degradation in such soil. Inoculation with a known PAH degrader further enhanced PAH degradation in the presence of corn.

  11. Evaluation of soil bioremediation techniques in an aged diesel spill at the Antarctic Peninsula.

    PubMed

    de Jesus, Hugo E; Peixoto, Raquel S; Cury, Juliano C; van Elsas, Jan D; Rosado, Alexandre S

    2015-12-01

    Many areas on the Antarctic continent already suffer from the direct and indirect influences of human activities. The main cause of contamination is petroleum hydrocarbons because this compound is used as a source of energy at the many research stations around the continent. Thus, the current study aims to evaluate treatments for bioremediation (biostimulation, bioaugmentation, and bioaugmentation + biostimulation) using soils from around the Brazilian Antarctic Station "Comandante Ferraz" (EACF), King George Island, Antarctic Peninsula. The experiment lasted for 45 days, and at the end of this period, chemical and molecular analyses were performed. Those analyses included the quantification of carbon and nitrogen, denaturing gradient gel electrophoresis (DGGE) analysis (with gradient denaturation), real-time PCR, and quantification of total hydrocarbons and polyaromatics. Molecular tests evaluated changes in the profile and quantity of the rrs genes of archaea and bacteria and also the alkB gene. The influence of the treatments tested was directly related to the type of soil used. The work confirmed that despite the extreme conditions found in Antarctic soils, the bacterial strains degraded hydrocarbons and bioremediation treatments directly influenced the microbial communities present in these soils even in short periods. Although the majority of the previous studies demonstrate that the addition of fertilizer seems to be most effective at promoting bioremediation, our results show that for some conditions, autochthonous bioaugmentation (ABA) treatment is indicated. This work highlights the importance of understanding the processes of recovery of contaminated environments in polar regions because time is crucial to the soil recovery and to choosing the appropriate treatment.

  12. Finger printing of mixed contaminants from former manufactured gas plant (MGP) site soils: Implications to bioremediation.

    PubMed

    Thavamani, Palanisami; Megharaj, Mallavarapu; Krishnamurti, G S R; McFarland, Ross; Naidu, Ravi

    2011-01-01

    Contaminants in general do not occur as single chemicals but as mixtures at any contaminated site. Gasworks sites are the typical mixed contaminated sites. These sites are not only subjected to PAH contamination but also varying degrees of heavy metal contamination. Bioremediation in these sites is often hindered by the presence of heavy metals. The co-occurrence of PAHs with heavy metals has not been systematically investigated. Metals are reported to inhibit the general soil microbiological processes. The total concentration of soluble metal in the system includes both free metal ion and complexed forms. Within bioavailable fraction, the most toxic form is the free metal species, which was not addressed well so far in gas works site characterisation. This study underpins the science and importance of metal bioavailability and speciation based site characterisation in mixed contaminated sites. In this study a detailed elemental chemistry of the gas works site soils are discussed using different methods. The PAH contamination was contributed by both low and high molecular weight PAHs. The total PAHs concentration ranged from 335 to 8645 mg/kg. Among most toxic metals Pb was found in high concentration ranging from 88 to 671 mg/kg, Cd 8 to 112 mg/kg and Zn varied from 64 to 488 mg/kg. Thermodynamic chemical equilibrium model VMINTEQ (Ver 2.52) was used to calculate the free metal species in gas works site soils. The percentage free metal species showed a different trend compared to total metal concentrations, free Zn species ranged 18-86%, free Cd was 26-87% and Pb showed lowest free metal percentage (0-17%). The bioavailable metal species and its implications to bioremediation have also been discussed. PMID:20875686

  13. Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils.

    PubMed

    Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

    2012-06-01

    Principal component analysis (PCA) was used to provide an overview of the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in former manufactured gas plant (MGP) site soils. PCA is the powerful multivariate method to identify the patterns in data and expressing their similarities and differences. Ten PAHs (naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]pyrene) and four toxic heavy metals - lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) - were detected in the site soils. PAH contamination was contributed equally by both low and high molecular weight PAHs. PCA was performed using the varimax rotation method in SPSS, 17.0. Two principal components accounting for 91.7% of the total variance was retained using scree test. Principle component 1 (PC1) substantially explained the dominance of PAH contamination in the MGP site soils. All PAHs, except anthracene, were positively correlated in PC1. There was a common thread in high molecular weight PAHs loadings, where the loadings were inversely proportional to the hydrophobicity and molecular weight of individual PAHs. Anthracene, which was less correlated with other individual PAHs, deviated well from the origin which can be ascribed to its lower toxicity and different origin than its isomer phenanthrene. Among the four major heavy metals studied in MGP sites, Pb, Cd and Cr were negatively correlated in PC1 but showed strong positive correlation in principle component 2 (PC2). Although metals may not have originated directly from gaswork processes, the correlation between PAHs and metals suggests that the materials used in these sites may have contributed to high concentrations of Pb, Cd, Cr and Zn. Thus, multivariate analysis helped to identify the sources of PAHs, heavy metals and their association in MGP site, and thereby better characterise the site risk, which would not be possible if one uses chemical analysis

  14. Response of soil respiration and ecosystem carbon budget to vegetation removal in Eucalyptus plantations with contrasting ages

    PubMed Central

    Wu, Jianping; Liu, Zhanfeng; Huang, Guomin; Chen, Dima; Zhang, Weixin; Shao, Yuanhu; Wan, Songze; Fu, Shenglei

    2014-01-01

    Reforested plantations have substantial effects on terrestrial carbon cycling due to their large coverage area. Although understory plants are important components of reforested plantations, their effects on ecosystem carbon dynamics remain unclear. This study was designed to investigate the effects of vegetation removal/understory removal and tree girdling on soil respiration and ecosystem carbon dynamics in Eucalyptus plantations of South China with contrasting ages (2 and 24 years old). We conducted a field manipulation experiment from 2008 to 2009. Understory removal reduced soil respiration in both plantations, whereas tree girdling decreased soil respiration only in the 2-year-old plantations. The net ecosystem production was approximately three times greater in the 2-year-old plantations (13.4 t C ha−1 yr−1) than in the 24-year-old plantations (4.2 t C h−1 yr−1). The biomass increase of understory plants was 12.6 t ha−1 yr−1 in the 2-year-old plantations and 2.9 t ha−1 yr−1 in the 24-year-old plantations, accounting for 33.9% and 14.1% of the net primary production, respectively. Our findings confirm the ecological importance of understory plants in subtropical plantations based on the 2 years of data. These results also indicate that Eucalyptus plantations in China may be an important carbon sink due to the large plantation area. PMID:25179343

  15. Response of soil respiration and ecosystem carbon budget to vegetation removal in Eucalyptus plantations with contrasting ages.

    PubMed

    Wu, Jianping; Liu, Zhanfeng; Huang, Guomin; Chen, Dima; Zhang, Weixin; Shao, Yuanhu; Wan, Songze; Fu, Shenglei

    2014-09-02

    Reforested plantations have substantial effects on terrestrial carbon cycling due to their large coverage area. Although understory plants are important components of reforested plantations, their effects on ecosystem carbon dynamics remain unclear. This study was designed to investigate the effects of vegetation removal/understory removal and tree girdling on soil respiration and ecosystem carbon dynamics in Eucalyptus plantations of South China with contrasting ages (2 and 24 years old). We conducted a field manipulation experiment from 2008 to 2009. Understory removal reduced soil respiration in both plantations, whereas tree girdling decreased soil respiration only in the 2-year-old plantations. The net ecosystem production was approximately three times greater in the 2-year-old plantations (13.4 t C ha(-1) yr(-1)) than in the 24-year-old plantations (4.2 t C h(-1) yr(-1)). The biomass increase of understory plants was 12.6 t ha(-1) yr(-1) in the 2-year-old plantations and 2.9 t ha(-1) yr(-1) in the 24-year-old plantations, accounting for 33.9% nd 14.1% of the net primary production, respectively. Our findings confirm the ecological importance of understory plants in subtropical plantations based on the 2 years of data. These results also indicate that Eucalyptus plantations in China may be an important carbon sink due to the large plantation area.

  16. SCR and GCR exposure ages of plagioclase grains from lunar soil

    NASA Technical Reports Server (NTRS)

    Etique, P.; Baur, H.; Signer, P.; Wieler, R.

    1986-01-01

    The concentrations of solar wind implanted Ar-36 in mineral grains extracted from lunar soils show that they were exposed to the solar wind on the lunar surface for an integrated time of 10E4 to 10E5 years. From the bulk soil 61501 plagioclase separates of 8 grain size ranges was prepared. The depletion of the implanted gases was achieved by etching aliquot samples of 4 grain sizes to various degrees. The experimental results pertinent to the present discussion are: The spallogenic Ne is, as in most plagioclases from lunar soils, affected by diffusive losses and of no use. The Ar-36 of solar wind origin amounts to (2030 + or - 100) x 10E-8 ccSTP/g in the 150 to 200 mm size fraction and shows that these grains were exposed to the solar wind for at least 10,000 years. The Ne-21/Ne-22 ratio of the spallogenic Ne is 0.75 + or - 0.01 and in very good agreement with the value of this ratio in a plagioclase separate from rock 76535. This rock has had a simple exposure history and its plagioclases have a chemical composition quite similar to those studied. In addition to the noble gases, the heavy particle tracks in an aliquot of the 150 to 200 mm plagioclase separate were investigated and found 92% of the grains to contain more than 10E8 tracks/sq cm. This corresponds to a mean track density of (5 + or - 1) x 10E8 tracks/sq cm. The exploration of the exposure history of the plagioclase separates from the soil 61501 do not contradict the model for the regolith dynamics but also fail to prove it.

  17. Mechanisms of Heavy Metal Sequestration in Soils: Plant-Microbe Interactions and Organic Matter Aging

    SciTech Connect

    Fan, Teresa W. M.; Higashi, Richard M.; Crowley

    2001-06-25

    The myriad of human activities including strategic and energy development at various DOE installations have resulted in the contamination of soils and waterways that can seriously threaten human and ecosystem health. Development of efficacious and economical remediation technologies is needed to ameliorate these immensely costly problems. Bioremediation (both plant and microbe-based) has promising potential to meet this demand but still requires advances in fundamental knowledge. For bioremediation of heavy metals, the three-way interaction of plant root, microbial community, and soil organic matter (SOM)1 in the rhizosphere is critically important for long-term sustainability but often underconsidered. Particularly urgent is the need to understand processes that lead to metal ion stabilization in soils, which is crucial to all of the goals of bioremediation: removal, stabilization, and transformation. This project will build on the knowledge that we have generated on the role of root exudation and metabolism for metal mobilization and accumulation, to address the following objectives: (1) Identify molecular markers and characterize the chemical nature of recalcitrant SOM pools that are involved in below ground metal ion interactions, which are likely to be markers for sustainable sequestration; (2) Utilize (1) to determine plant and microbial factors that contribute to sustainable metal sequestration or mobility, as well as bioavailability; (3) Utilize information from (1) and (2) to explore efficacious means for enhancing sustainable phytostabilization of heavy metals in the subsurface zone.

  18. Using the accumulation of CBD-extractable iron and clay content to estimate soil age on stable surfaces and nearby slopes, Front Range, Colorado

    NASA Astrophysics Data System (ADS)

    Dethier, David P.; Birkeland, Peter W.; McCarthy, James A.

    2012-11-01

    In many transport-limited environments, morphology, pedogenic iron and clay content provide a basis for estimating the exposure age of soils and associated landforms. We measured citrate-buffered dithionite (CBD)-extractable Fe (Fed) and clay concentration in fresh rock, saprolite, morainal and colluvial materials, and soil horizons from stable surfaces and hillslopes in the Colorado Front Range. Fresh igneous and high-grade metamorphic rocks contain < 1% Fed and 1 to 5% clay. As bedrock and surficial deposits age, Fed and clay accumulate from weathering and dustfall. Late Holocene regolith at warm, dry sites contains small amounts of Fed and clay, but relatively moist soils developed on early Holocene cirque deposits contain as much as 1.5% Fed and 8% clay. Concentrations and total profile accumulation of Fed and clay increase with age in soils developed on stable surfaces of glacial deposits as old as ~ 130 kyr. On stable sites, Fed and clay accumulation from weathering and dust is ~ 0.02 g cm- 2 kyr- 1 and ~ 0.2 g cm- 2 kyr- 1, respectively. We used the Fed and clay inventory in soil profiles at dated, stable Front Range surfaces to calculate accumulation functions, which allowed us to estimate soil age at hillslope sites. Heterogeneous parent material, particularly on hillslopes, and climate-related effects add to variability in measured relations. Mobile regolith in Gordon Gulch, one of the Boulder Creek Critical Zone Observatory (CZO) catchments, yields profile ages from about 0.5 to 5 × 104 yr, comparable to values measured using other techniques. Calculated profile ages are older on a north- vs. south-facing slope and increase from the drainage divide to the footslope. Ages calculated for stabilized colluvium and well-developed buried profiles at nearby hillslope sites (Lefthand, Ward and Rollinsville) suggest that these soils have stabilized over periods > 105 yr. In the absence of radiometric ages, the accumulation of Fed and clay in soils on stable

  19. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO₃) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils.

    PubMed

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A M; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J

    2015-08-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value.

  20. Productivity of aboveground coarse wood biomass and stand age related to soil hydrology of Amazonian forests in the Purus-Madeira interfluvial area

    NASA Astrophysics Data System (ADS)

    Cintra, B. B. L.; Schietti, J.; Emillio, T.; Martins, D.; Moulatlet, G.; Souza, P.; Levis, C.; Quesada, C. A.; Schöngart, J.

    2013-04-01

    The ongoing demand for information on forest productivity has increased the number of permanent monitoring plots across the Amazon. Those plots, however, do not comprise the whole diversity of forest types in the Amazon. The complex effects of soil, climate and hydrology on the productivity of seasonally waterlogged interfluvial wetland forests are still poorly understood. The presented study is the first field-based estimate for tree ages and wood biomass productivity in the vast interfluvial region between the Purus and Madeira rivers. We estimate stand age and wood biomass productivity by a combination of tree-ring data and allometric equations for biomass stocks of eight plots distributed along 600 km in the Purus-Madeira interfluvial area that is crossed by the BR-319 highway. We relate stand age and wood biomass productivity to hydrological and edaphic conditions. Mean productivity and stand age were 5.6 ± 1.1 Mg ha-1 yr-1 and 102 ± 18 yr, respectively. There is a strong relationship between tree age and diameter, as well as between mean diameter increment and mean wood density within a plot. Regarding the soil hydromorphic properties we find a positive correlation with wood biomass productivity and a negative relationship with stand age. Productivity also shows a positive correlation with the superficial phosphorus concentration. In addition, superficial phosphorus concentration increases with enhanced soil hydromorphic condition. We raise three hypotheses to explain these results: (1) the reduction of iron molecules on the saturated soils with plinthite layers close to the surface releases available phosphorous for the plants; (2) the poor structure of the saturated soils creates an environmental filter selecting tree species of faster growth rates and shorter life spans and (3) plant growth on saturated soil is favored during the dry season, since there should be low restrictions for soil water availability.

  1. Soil amendments, plant age, and intercropping impact p,p'-DDE bioavailability to Cucurbita pepo.

    PubMed

    White, Jason C; Parrish, Zakia D; Gent, Martin P N; Iannucci-Berger, William; Eitzer, Brian D; Isleyen, Mehmet; Mattina, MaryJane Incorvia

    2006-01-01

    Field experiments were conducted to optimize the phytoextraction of weathered p,p'-DDE (p,p'-dichlorodiphenyldichloroethylene) by Cucurbita subspecies. The effects of two soil amendments, mycorrhizae or a biosurfactant, on p,p'-DDE accumulation was determined. Also, p,p'-DDE uptake was assessed during plant growth (12, 26, 38, and 62 d), and cultivars that accumulate weathered p,p'-DDE were intercropped with cultivars known not to have that ability. Cucurbita pepo L. ssp. pepo accumulated large amounts of the contaminant, having stem bioconcentration factors, amounts of p,p'-DDE translocated, and contaminant phytoextraction that were 14, 9.9, and 5.0 times greater than C. pepo L. ssp. ovifera (L.) D.S. Decker, respectively. During 62 d, the stem BCF (bioconcentration factor) for p,p'-DDE in subspecies pepo remained constant and the total amount of contaminant accumulated was correlated with plant biomass (r(2) = 0.86). For subspecies ovifera, the stem BCF was highest at 12 d (1.5) but decreased to 0.39 by 62 d, and p,p'-DDE removal was not correlated with plant biomass. Mycorrhizal inoculation increased p,p'-DDE accumulation by both subspecies by an average 4.4 times. For subspecies pepo, mycorrhizae increased the percentage of contaminant extracted from 0.72 to 2.1%. Biosurfactant amendment also enhanced contaminant accumulation by both subspecies, although treatment reduced subspecies ovifera biomass by 60%. The biosurfactant had no effect on the biomass of subspecies pepo, increased the average contaminant concentration by 3.6-fold, and doubled the overall amount of p,p'-DDE removed from the soil. Soil amendments that enhance the mobility of weathered persistent organic pollutants will significantly increase the amount of contaminant phytoextraction by Cucurbita pepo.

  2. Short-term controls on the age of microbial carbon sources in boreal forest soils

    NASA Astrophysics Data System (ADS)

    Czimczik, Claudia I.; Trumbore, Susan E.

    2007-09-01

    One predicted positive feedback of increasing temperatures in the boreal region is carbon (C) loss through enhanced microbial decomposition of soil organic matter (SOM). The degree to which temperature sensitivity for decomposition varies across a range of C-substrates remains uncertain. Using incubations, we tested whether microorganisms shift to more recalcitrant substrates (with longer turnover times) at higher temperatures at low or increased soil moisture. We measured the radiocarbon (Δ14C) and stable isotope (δ13C) signature of CO2 respired from organic soils from six black spruce forests (0 to 150 years since fire). We identified major C substrates contributing to decomposition by comparing Δ14C of CO2 to Δ14C of roots, mosses, needles, and wood separated from bulk SOM. The Δ14C signatures of these components allow an estimation of their turnover times, further constraining their relative contribution to respiration. Fastest turnover rates were observed for herbaceous litter and needles (annual to decadal) for mosses, with intermediate turnover times for roots. Dominant microbial C sources in 5 to 40 year old stands were fire remnants and litter of early succession species, while substrates with longer turnover times accounted for a larger proportion of CO2 in mature stands. At both low and increased moisture levels, the increase in CO2 efflux at higher temperatures was accompanied by a decline in δ13CO2, but no shift in Δ14CO2. This suggests that temperature sensitivity is not greater for recalcitrant C and that changes in δ13C likely reflect temperature dependence of microbial fractionation processes rather than a substrate shift.

  3. An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

    USGS Publications Warehouse

    Mahan, S.A.; Brown, D.J.

    2007-01-01

    There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

  4. Effects of chemical, biological, and physical aging as well as soil addition on the sorption of pyrene to activated carbon and biochar.

    PubMed

    Hale, Sarah E; Hanley, Kelly; Lehmann, Johannes; Zimmerman, Andrewr; Cornelissen, Gerard

    2011-12-15

    In this study, the suitability of biochar and activated carbon (AC) for contaminated soil remediation is investigated by determining the sorption of pyrene to both materials in the presence and absence of soil and before as well as after aging. Biochar and AC were aged either alone or mixed with soil via exposure to (a) nutrients and microorganisms (biological), (b) 60 and 110 °C (chemical), and (c) freeze-thaw cycles (physical). Before and after aging, the pH, elemental composition, cation exchange capacity (CEC), microporous SA, and sorption isotherms of pyrene were quantified. Aging at 110 °C altered the physicochemical properties of all materials to the greatest extent (for example, pH increased by up to three units and CEC by up to 50% for biochar). Logarithmic K(Fr) values ranged from 7.80 to 8.21 (ng kg(-1))(ng L(-1))(-nF) for AC and 5.22 to 6.21 (ng kg(-1))(ng L(-1))(-nF) for biochar after the various aging regimes. Grinding biochar to a smaller particle size did not significantly affect the sorption of d(10) pyrene, implying that sorption processes operate on the subparticle scale. Chemical aging decreased the sorption of pyrene to the greatest extent (up to 1.8 log unit for the biochar+soil). The sorption to AC was affected more by the presence of soil than the sorption to biochar was. Our results suggest that AC and biochar have a high sorption capacity for pyrene that is maintained both in the presence of soil and during harsh aging. Both materials could therefore be considered in contaminated land remediation.

  5. Linking soil water balance and water age with leaching of nitrate to groundwater in an agricultural setting

    NASA Astrophysics Data System (ADS)

    Sigler, W.; Ewing, S. A.; Payn, R. A.; Jones, C. A.; Weissmann, G. S.

    2013-12-01

    The effects of land management on groundwater chemistry are often poorly understood due to uncertainties about residence times of water and solutes in the unsaturated and the saturated zones. In central Montana, a strath terrace mantled with 20-100 cm of loess-derived clay loam is composed of 5-10 meters of gravel hosting a shallow aquifer overlying shale. The landform is isolated from mountain front stream recharge and drained by springs at the gravel/shale interface surrounding the terrace. Ninety three percent of the terrace surface is cultivated, predominantly for production of small grains. A typical cropping system on the terrace is a three year rotation of winter wheat, spring wheat or barley, and fallow, where each phase represents a different regime of evapotranspiration, recharge, fertilizer application, mineralization and nitrate leaching to groundwater. Age of water in discharge from the perched aquifer in the gravel can potentially be characterized by monitoring springs and streams that are ultimately sourced by infiltration and recharge across the terrace. Work presented here couples a simple daily soil water balance model with ground and surface water chemistry to infer travel times through the unsaturated and saturated zones. These results are evaluated against estimates of groundwater age derived from pool turnover time calculations, finite difference groundwater flow modeling, and use of chemical age tracers.

  6. Earthworm bioassays and seedling emergence for monitoring toxicity, aging and bioaccumulation of anthropogenic waste indicator compounds in biosolids-amended soil.

    PubMed

    Kinney, Chad A; Campbell, Bryan R; Thompson, Regina; Furlong, Edward T; Kolpin, Dana W; Burkhardt, Mark R; Zaugg, Steven D; Werner, Stephen L; Hay, Anthony G

    2012-09-01

    Land application of biosolids (treated sewage sludge) can be an important route for introducing xenobiotic compounds into terrestrial environments. There is a paucity of available information on the effects of biosolids amendment on terrestrial organisms. In this study, the influence of biosolids and biosolids aging on earthworm (Eisenia fetida) reproduction and survival and lettuce (Lactuca sativa) seedling emergence was investigated. Earthworms were exposed to soils amended with varying quantities of biosolids (0, 1, 2, 3, or 4% dry mass). To investigate the influence of biosolids aging, the biosolids used in the study were aged for differing lengths of time (2 or 8 weeks) prior to exposure. All of the adult earthworms survived in the biosolids-amended soils at all concentrations that were aged for 2 weeks; however, only 20% of the adults survived in the soil amended with the highest concentration of biosolids and aged for 8 weeks. Reproduction as measured by mean number of juveniles and unhatched cocoons produced per treatment correlated inversely with biosolids concentration, although the effects were generally more pronounced in the 8-week aged biosolids-soil samples. Latent seedling emergence and reduced seedling fitness correlated inversely with biosolids concentration, but these effects were tempered in the 8-week aged versus the 2-week aged soil-biosolids mixtures. Anthropogenic waste indicator compounds (AWIs) were measured in the biosolids, biosolids-soil mixtures, and earthworm samples. Where possible, bioaccumulation factors (BAFs) were calculated or estimated. A wide variety of AWIs were detected in the biosolids (51 AWIs) and earthworm samples (≤19 AWI). The earthworms exposed to the 8-week aged biosolids-soil mixtures tended to accumulate greater quantities of AWIs compared to the 2-week aged mixture, suggesting that the bioavailability of some AWIs was enhanced with aging. The BAFs for a given AWI varied with treatment. Notably large BAFs were

  7. Assessment of environmentally persistent free radicals in soils and sediments from three Superfund sites.

    PubMed

    dela Cruz, Albert Leo N; Cook, Robert L; Dellinger, Barry; Lomnicki, Slawomir M; Donnelly, Kirby C; Kelley, Matthew A; Cosgriff, David

    2014-01-01

    We previously reported the presence of environmentally persistent free radicals (EPFRs) in pentachlorophenol (PCP) contaminated soils at a closed wood treatment facility site in Georgia. The reported EPFRs were pentachlorophenoxyl radicals formed on soils under ambient conditions via electron transfer from PCP to electron acceptors in the soil. In this study, we present results for soil and sediment samples from additional Superfund sites in Montana and Washington. Paramagnetic centers associated with different chemical environments were characterized by distinct g-factors and line widths (ΔHp-p). EPFR concentrations in contaminated samples were ~30×, ~12×, and ~2× higher than background samples at the Georgia, Montana, and Washington sites, respectively. EPR signals in the Montana contaminated soils were very similar to those previously observed for pentachlorophenol contaminated soils at the Georgia site, i.e., g = 2.00300 and ΔHp-p = 6.0 G, whereas signals in the Washington sediment samples were similar to those previously observed for other PAH contaminated soils, i.e., g = 2.00270 and ΔHp-p = 9.0 G. Total carbon content measurements exhibited direct correlation with EPFR concentration. The presence of radicals in sites contaminated a decade to a century ago suggests continuous formation of EPFRs from molecular contaminants in the soil and sediment. PMID:24244947

  8. Assessment of Environmentally Persistent Free Radicals in Soils and Sediments from Three Superfund Sites

    PubMed Central

    dela Cruz, Albert Leo N.; Cook, Robert L.; Dellinger, Barry; Lomnicki, Slawomir M.; Donnelly, Kirby C.; Kelley, Matthew A.; Cosgriff, David

    2014-01-01

    We previously reported the presence of environmentally persistent free radicals (EPFRs) in pentachlorophenol (PCP) contaminated soils at a closed wood treatment facility site in Georgia. The reported EPFRs were pentachlorophenoxyl radicals formed on soils under ambient conditions via electron transfer from PCP to electron acceptors in the soil. In this study, we present results for soil and sediment samples from additional Superfund sites in Montana and Washington. Paramagnetic centers associated with different chemical environments were characterized by distinct g-factors and line widths (ΔHp-p). EPFR concentrations in contaminated samples were ~30x, ~12x, and ~2x higher than background samples at the Georgia, Montana, and Washington sites, respectively. EPR signals in the Montana contaminated soils were very similar to those previously observed for pentachlorophenol contaminated soils at the Georgia site, i.e., g = 2.00300 and ΔHp-p = 6.0 G, whereas signals in the Washington sediment samples were similar to those previously observed for other PAH contaminated soils, i.e., g = 2.00270 and ΔHp-p = 9.0G. Total carbon content measurements exhibited direct correlation with EPFR concentration. The presence of radicals in sites contaminated a decade to a century ago suggests continuous formation of EPFRs from molecular contaminants in the soil and sediment. PMID:24244947

  9. Effects of bacterial inoculation and nonionic surfactants on degradation of polycyclic aromatic hydrocarbons in soil

    SciTech Connect

    Madsen, T.; Kristensen, P.

    1997-04-01

    The aim of the study was to examine the effects of introduced bacteria and nonionic surfactants on the degradation of polycyclic aromatic hydrocarbons (PAHs) in soil. Mineralization experiments were conducted with freshly added [{sup 14}C]phenanthrene or [{sup 14}]pyrene, whereas other experiments focused on the degradation of selected PAHs present in a coal tar-contaminated soil. Inoculation of soil samples with phenanthrene-utilizing bacteria stimulated the mineralization of [{sup 14}]phenanthrene. This effect, however, was most notable in soil with a low indigenous potential for PAH degradation, and a large inoculum was apparently required to establish phenanthrene mineralization in the soil. Addition of alcohol ethoxylate and glycoside surfactants to soil samples enhanced the mineralization of [{sup 14}]phenanthrene and [{sup 14}]pyrene. The nonionic surfactants also enhanced the degradation of contaminant PAHs that were present in the soil coal tar. As an example, pyrene, benzo[b,j,k]fluoranthene, and benzo[a]pyrene were resistant to degradation in the absence of surfactants, whereas significant degradation of these PAHs was observed when surfactants were added. The surfactant-related enhancement of the degradation of PAH contaminants was less convincing when a rapidly degradable glycoside surfactant was used. This suggests that surfactants that are mineralized at moderate rates may be more applicable for increasing the availability of PAHs in soil.

  10. Role of phosphate and Fe-oxides on the acid-aided extraction efficiency and readsorption of As in field-aged soil.

    PubMed

    Im, Jinwoo; Yang, Kyung; Moon, Seheum; Kim, Young-Jin; Nam, Kyoungphile

    2015-12-30

    This study was conducted to investigate arsenic (As) readsorption phenomenon in acid-treated soil using phosphate as a competing ion. Three field-aged soils (i.e., S1, paddy soil; S2, field soil; S3, forest soil) originally contaminated with As ranging from 30 to 59 mg/kg-soil were collected from a former smelter site. When 0.2M hydrochloric acid (HCl) alone was used as an extraction solution, As bound to iron (Fe) oxides was removed but significant amount of the released As was readsorbed onto residual Fe-oxides, yielding low As extraction efficiency of 11-27%. Readsorption of the released As seemed to occur preferentially on amorphous Fe-oxides. In contrast, As extraction efficiency was greatly increased by 0.2M HCl solution supplemented with monopotassium phosphate (KH2PO4), which was greatly influenced by the molar ratio of acid to phosphate. In addition, by the extraction solution with an optimal ratio of 0.2M HCl/0.1M KH2PO4, As extraction efficiency differed with soil types, showing 79.6, 44.1, and 61.0% in S1, S2, and S3, respectively. The reason can be ascribed to the blocking of the available As readsorption sites by phosphate ions, the sites seemed to mainly reside on the residual amorphous Fe-oxides in soil. PMID:26177492

  11. Visualizing and Quantifying Bioaccessible Pores in Field-Aged Petroleum Hydrocarbon-Contaminated Clay Soils Using Synchrotron-based X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Chang, W.; Kim, J.; Zhu, N.; McBeth, J. M.

    2015-12-01

    Microbial hydrocarbon degradation is environmentally significant and applicable to contaminated site remediation practices only when hydrocarbons (substrates) are physically bioaccessible to bacteria in soil matrices. Powerful X-rays are produced by synchrotron radiation, allowing for bioaccessible pores in soil (larger than 4 microns), where bacteria can be accommodated, colonize and remain active, can be visualized at a much higher resolution. This study visualized and quantified such bioaccessible pores in intact field-aged, oil-contaminated unsaturated soil fractions, and examined the relationship between the abundance of bioaccessible pores and hydrocarbon biodegradation. Using synchrotron-based X-ray Computed Tomography (CT) at the Canadian Light Source, a large dataset of soil particle characteristics, such as pore volumes, surface areas, number of pores and pore size distribution, was generated. Duplicate samples of five different soil fractions with different soil aggregate sizes and water contents (13, 18 and 25%) were examined. The method for calculating the number and distribution of bioaccessible pores using CT images was validated using the known porosity of Ottawa sand. This study indicated that the distribution of bioaccessible pore sizes in soil fractions are very closely related to microbial enhancement. A follow-up aerobic biodegradation experiment for the soils at 17 °C (average site temperature) over 90 days confirmed that a notable decrease in hydrocarbon concentrations occurred in soils fractions with abundant bioaccessible pores and with a larger number of pores between 10 and 100 μm. The hydrocarbon degradation in bioactive soil fractions was extended to relatively high-molecular-weight hydrocarbons (C16-C34). This study provides quantitative information about how internal soil pore characteristics can influence bioremediation performance.

  12. Earthworm bioassays and seedling emergence for monitoring toxicity, aging and bioaccumulation of anthropogenic waste indicator compounds in biosolids-amended soil

    USGS Publications Warehouse

    Kinney, Chad A.; Campbell, Bryan R.; Thompson, Regina; Furlong, Edward T.; Kolpin, Dana W.; Burkhardt, Mark R.; Zaugg, Steven D.; Werner, Stephen L.; Hay, Anthony G.

    2012-01-01

    Land application of biosolids (treated sewage sludge) can be an important route for introducing xenobiotic compounds into terrestrial environments. There is a paucity of available information on the effects of biosolids amendment on terrestrial organisms. In this study, the influence of biosolids and biosolids aging on earthworm (Eisenia fetida) reproduction and survival and lettuce (Lactuca sativa) seedling emergence was investigated. Earthworms were exposed to soils amended with varying quantities of biosolids (0, 1, 2, 3, or 4% dry mass). To investigate the influence of biosolids aging, the biosolids used in the study were aged for differing lengths of time (2 or 8 weeks) prior to exposure. All of the adult earthworms survived in the biosolids–amended soils at all concentrations that were aged for 2 weeks; however, only 20% of the adults survived in the soil amended with the highest concentration of biosolids and aged for 8 weeks. Reproduction as measured by mean number of juveniles and unhatched cocoons produced per treatment correlated inversely with biosolids concentration, although the effects were generally more pronounced in the 8-week aged biosolids–soil samples. Latent seedling emergence and reduced seedling fitness correlated inversely with biosolids concentration, but these effects were tempered in the 8-week aged versus the 2-week aged soil–biosolids mixtures. Anthropogenic waste indicator compounds (AWIs) were measured in the biosolids, biosolids–soil mixtures, and earthworm samples. Where possible, bioaccumulation factors (BAFs) were calculated or estimated. A wide variety of AWIs were detected in the biosolids (51 AWIs) and earthworm samples (≤ 19 AWI). The earthworms exposed to the 8-week aged biosolids–soil mixtures tended to accumulate greater quantities of AWIs compared to the 2-week aged mixture, suggesting that the bioavailability of some AWIs was enhanced with aging. The BAFs for a given AWI varied with treatment. Notably large

  13. Biosurfactant-enhanced bioremediation of aged polycyclic aromatic hydrocarbons (PAHs) in creosote contaminated soil.

    PubMed

    Bezza, Fisseha Andualem; Chirwa, Evans M Nkhalambayausi

    2016-02-01

    The potential for biological treatment of an environment contaminated by complex petrochemical contaminants was evaluated using creosote contaminated soil in ex situ bio-slurry reactors. The efficacy of biosurfactant application and stimulation of in situ biosurfactant production was investigated. The biosurfactant produced was purified and characterised using Fourier transform infrared (FTIR) spectroscopy. Biosurfactant enhanced degradation of PAHs was 86.5% (with addition of biosurfactant) and 57% in controls with no biosurfactant and nutrient amendments after incubation for 45 days. A slight decrease in degradation rate observed in the simultaneous biosurfactant and nutrient, NH4NO3 and KH2PO4, supplemented microcosm can be attributed to preferential microbial consumption of the biosurfactant supplemented. The overall removal of PAHs was determined to be mass transport limited since the dissolution rate caused by the biosurfactant enhanced the bioavailability of the PAHs to the microorganisms. The consortium culture was predominated by the aromatic ring-cleaving species Bacillus stratosphericus, Bacillus subtilis, Bacillus megaterium, and Pseudomonas aeruginosa.

  14. Rapamycin: An InhibiTOR of Aging Emerges From the Soil of Easter Island.

    PubMed

    Arriola Apelo, Sebastian I; Lamming, Dudley W

    2016-07-01

    Rapamycin (sirolimus) is a macrolide immunosuppressant that inhibits the mechanistic target of rapamycin (mTOR) protein kinase and extends lifespan in model organisms including mice. Although rapamycin is an FDA-approved drug for select indications, a diverse set of negative side effects may preclude its wide-scale deployment as an antiaging therapy. mTOR forms two different protein complexes, mTORC1 and mTORC2; the former is acutely sensitive to rapamycin whereas the latter is only chronically sensitive to rapamycin in vivo. Over the past decade, it has become clear that although genetic and pharmacological inhibition of mTORC1 extends lifespan and delays aging, inhibition of mTORC2 has negative effects on mammalian health and longevity and is responsible for many of the negative side effects of rapamycin. In this review, we discuss recent advances in understanding the molecular and physiological effects of rapamycin treatment, and we discuss how the use of alternative rapamycin treatment regimens or rapamycin analogs has the potential to mitigate the deleterious side effects of rapamycin treatment by more specifically targeting mTORC1. Although the side effects of rapamycin are still of significant concern, rapid progress is being made in realizing the revolutionary potential of rapamycin-based therapies for the treatment of diseases of aging. PMID:27208895

  15. Rapamycin: An InhibiTOR of Aging Emerges From the Soil of Easter Island.

    PubMed

    Arriola Apelo, Sebastian I; Lamming, Dudley W

    2016-07-01

    Rapamycin (sirolimus) is a macrolide immunosuppressant that inhibits the mechanistic target of rapamycin (mTOR) protein kinase and extends lifespan in model organisms including mice. Although rapamycin is an FDA-approved drug for select indications, a diverse set of negative side effects may preclude its wide-scale deployment as an antiaging therapy. mTOR forms two different protein complexes, mTORC1 and mTORC2; the former is acutely sensitive to rapamycin whereas the latter is only chronically sensitive to rapamycin in vivo. Over the past decade, it has become clear that although genetic and pharmacological inhibition of mTORC1 extends lifespan and delays aging, inhibition of mTORC2 has negative effects on mammalian health and longevity and is responsible for many of the negative side effects of rapamycin. In this review, we discuss recent advances in understanding the molecular and physiological effects of rapamycin treatment, and we discuss how the use of alternative rapamycin treatment regimens or rapamycin analogs has the potential to mitigate the deleterious side effects of rapamycin treatment by more specifically targeting mTORC1. Although the side effects of rapamycin are still of significant concern, rapid progress is being made in realizing the revolutionary potential of rapamycin-based therapies for the treatment of diseases of aging.

  16. The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic

    PubMed Central

    2009-01-01

    The polycyclic aromatic hydrocarbon (PAH) contamination of urban, agricultural and forest soil samples was investigated from samples obtained in the surroundings of Valasske Mezirici. Valasske Mezirici is a town located in the north-east mountainous part of the Czech Republic, where a coal tar refinery is situated. 16 PAHs listed in the US EPA were investigated. Organic oxidizable carbon was also observed in the forest soils. The PAH concentrations ranged from 0.86-10.84 (with one anomalous value of 35.14) and 7.66-79.39 mg/kg dm in the urban/agricultural and forest soils, respectively. While the PAH levels in the urban/agricultural soils are within the range typically found in industrialized areas, the forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. The PAH concentrations and their molecular distribution ratios were studied as functions of the sample location and the meteorological history. The soils from localities at higher altitudes above sea level have the highest PAH concentrations, and the PAH concentrations decrease with increasing distance from the town. PMID:20003407

  17. Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

    SciTech Connect

    Hoylman, A.M.; Walton, B.T.

    1994-01-01

    Under laboratory conditions selected to maximize root uptake, plant tissue distribution of PAH-derived {sup 14}C was largely limited to root tissue of Malilotus alba. These results suggest that plant uptake of PAHs from contaminated soil via roots, and translocation to aboveground plant tissues (stems and leaves), is a limited mechanism for transport into terrestrial food chains. However, these data also indicate that root surface sorption of PAHs may be important for plants grown in soils containing elevated concentration PAHs. Root surface sorption of PAHs may be an important route of exposure for plants in soils containing elevated concentrations of PAHS. Consequently, the root-soil interface may be the site of plant-microbial interactions in response to a chemical stress. In this study, evidence of a shift in carbon allocation to the root zone of plants exposed to phenanthrene and corresponding increases in soil respiration and heterotrophic plate counts provide evidence of a plant-microbial response to a chemical stress. The results of this study establish the importance of the root-soil interface for plants growing in PAH contaminated soil and indicate the existence of plant-microbial interactions in response to a chemical stress. These results may provide new avenues of inquiry for studies of plant toxicology, plant-microbial interactions in the rhizosphere, and environmental fates of soil contaminants. In addition, the utilization of plants to enhance the biodegradation of soil contaminants may require evaluation of plant physiological changes and plant shifts in resource allocation.

  18. Short-Term Rhizosphere Effect on Available Carbon Sources, Phenanthrene Degradation, and Active Microbiome in an Aged-Contaminated Industrial Soil

    PubMed Central

    Thomas, François; Cébron, Aurélie

    2016-01-01

    Over the last decades, understanding of the effects of plants on soil microbiomes has greatly advanced. However, knowledge on the assembly of rhizospheric communities in aged-contaminated industrial soils is still limited, especially with regard to transcriptionally active microbiomes and their link to the quality or quantity of carbon sources. We compared the short-term (2–10 days) dynamics of bacterial communities and potential PAH-degrading bacteria in bare or ryegrass-planted aged-contaminated soil spiked with phenanthrene, put in relation with dissolved organic carbon (DOC) sources and polycyclic aromatic hydrocarbon (PAH) pollution. Both resident and active bacterial communities (analyzed from DNA and RNA, respectively) showed higher species richness and smaller dispersion between replicates in planted soils. Root development strongly favored the activity of Pseudomonadales within the first 2 days, and of members of Actinobacteria, Caulobacterales, Rhizobiales, and Xanthomonadales within 6–10 days. Plants slowed down the dissipation of phenanthrene, while root exudation provided a cocktail of labile substrates that might preferentially fuel microbial growth. Although the abundance of PAH-degrading genes increased in planted soil, their transcription level stayed similar to bare soil. In addition, network analysis revealed that plants induced an early shift in the identity of potential phenanthrene degraders, which might influence PAH dissipation on the long-term. PMID:26903971

  19. Soil physical restrictions and hydrology regulate stand age and wood biomass turnover rates of Purus-Madeira interfluvial wetlands in Amazonia

    NASA Astrophysics Data System (ADS)

    Cintra, B. B. L.; Schietti, J.; Emillio, T.; Martins, D.; Moulatlet, G.; Souza, P.; Levis, C.; Quesada, C. A.; Schöngart, J.

    2013-11-01

    In Amazonia, wetlands constitute about 30% of its entire basin, of which ancient fluvial terraces located in vast interfluvial regions cover a large portion. Although the increased number of permanent plots in the recent years has contributed to improved understanding of regional variation in forest dynamics across the Amazon Basin, the functioning of large lowland interfluvial wetlands remain poorly understood. Here we present the first field-based estimate for tree ages, wood biomass productivity and biomass turnover rates for eight 1 ha plots in wetland and non-flooded forests distributed along the BR-319 Highway along a distance of about 600 km crossing the Purus-Madeira rivers interfluvial region in central-southwestern Amazon Basin. We estimate stand age, wood biomass productivity and biomass turnover rates combining tree-ring data and an allometric equation based on diameter, tree height and wood density and relate these structural parameters to physical soil and hydrological restrictions. Wood biomass and productivity varied twofold among the plots, with wood biomass stocks ranging between 138-294 Mg ha-1 and productivity varying between 3.4-6.6 Mg ha-1 yr-1. Soil effective depth, topography, structure and mainly soil water saturation significantly affected stand age (64-103 yr) and forest dynamics in terms of annual biomass turnover rates (2.0-3.2%). On harsher soils characterized by a poor structure, low effective depth and high water saturation, biomass turnover rates were increased and forests stands were younger compared to well-drained sites. We suggest that soil constraints, especially soil water saturation, limit the development of the stand structure, resulting in forests with younger stand ages and higher biomass turnover rates compared to forests growing on well-drained soils. We do not find, however, any relation between physical soil restrictions or hydrology and wood biomass productivity, but there is a trend of increasing wood biomass

  20. TCP Final Report: Measuring the Effects of Stand Age and Soil Drainage on Boreal Forest

    SciTech Connect

    Michael L. Goulden

    2007-05-02

    This was a 6-year research project in the Canadian boreal forest that focused on using field observations to understand how boreal forest carbon balance changes during recovery from catastrophic forest fire. The project began with two overarching goals: (1) to develop techniques that would all the year round operation of 7 eddy covariance sites in a harsh environment at a much lower cost than had previously been possible, and (2) to use these measurements to determine how carbon balance changes during secondary succession. The project ended in 2006, having accomplished its primary objectives. Key contributions to DOE during the study were: (1) Design, test, and demonstrate a lightweight, fully portable eddy flux system that exploits several economies of scale to allow AmeriFlux-quality measurements of CO{sub 2} exchange at many sites for a large reduction in cost (Goulden et al. 2006). (2) Added seven year-round sites to AmeriFlux, at a relatively low per site cost using the Eddy Covariance Mesonet approach (Goulden et al. 2006). These data are freely available on the AmeriFlux web site. (3) Tested and rejected the conventional wisdom that forests lose large amounts of carbon during the first decade after disturbance, then accumulate large amounts of carbon for {approx}several decades, and then return to steady state in old age. Rather, we found that boreal forests recovers quickly from fire and begins to accumulate carbon within {approx}5 years after disturbance. Additionally, we found no evidence that carbon accumulation declines in old stands (Goulden et al. 2006, Goulden et al. in prep). (4) Tested and rejected claims based on remote sensing observations (for example, Myneni et al 1996 using AVHRR) that regions of boreal forest have changed markedly in the last 20 years. Rather, we assembled a much richer data set than had been used in the past (eddy covariance observations, tree rings, biomass, NPP, AVHRR, and LandSat), which we used to establish that the

  1. Impact of aging on the formation of bound residues after peroxidase-mediated treatment of 2,4-DCP contaminated soils.

    PubMed

    Palomo, Mónica; Bhandari, Alok

    2006-05-15

    This study evaluated the impact of solute-soil contact time on the formation of "bound" residue in two surface soils exposed to solutions containing 2,4-dichlorophenol (DCP) or DCP polymerization products (DPP). DPP was generated by horseradish peroxidase (HRP) mediated oxidative polymerization of 14C-labeled DCP in the soil slurry. Soils were preloaded with DCP or DPP for durations ranging from 2 h to 84 days. Bound residue was described as solute that was resistant to methanol extraction. Alkali extractions were conducted to estimate the 14C-activity associated with the humic acid, fulvic acid, and humin/mineral components of the soil. Changes in the distribution of the preloaded 14C-DCP and 14C-DPP were observed as a function of the solute-soil contact time. Results suggest that an assumption of sorption equilibrium based solely on the achievement of constant aqueous- or solid-phase solute concentrations can lead to erroneous conclusions about the establishment of true thermodynamic sorption equilibrium. This work also illustrated that (i) significant "irreversible" binding of phenolic contaminants to soils can be achieved during peroxidase-mediated treatment; and (ii) the "aging" process can lead to greater bound-residue formation over time.

  2. Influence of soil moisture on sunflower oil extraction of polycyclic aromatic hydrocarbons from a manufactured gas plant soil.

    PubMed

    Gong, Zongqiang; Wilke, B-M; Alef, Kassem; Li, Peijun

    2005-05-01

    The influence of soil moisture on efficiency of sunflower oil extraction of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil was investigated. The PAH-contaminated soil was collected from a manufactured gas plant (MGP) site in Berlin, Germany. Half of the soil was air-dried, and the other half was kept as field-moist soil. Batch experiments were performed using air-dried and field-moist soils, and sunflower oil was used as extractant at oil/soil ratios of 2:1 and 1:1 (v/m). The experimental data were fitted to a first-order empirical model to describe mass-transfer profiles of the PAHs. Column extraction experiments were also conducted. Field-moist and air-dried soils in the column were extracted using sunflower oil at an oil/soil ratio of 2:1. In the batch experiments, PAHs were more rapidly extracted from air-dried soil than from field-moist soil. Removal rate of total PAH increased 23% at oil/soil ratio of 1:1 and 15.5% at oil/soil ratio of 2:1 after the soil was air dried. The most favorable conditions for batch extraction were air-dried soil, with an oil/soil ratio of 2:1. In the column experiments, the removal rate of total PAH from air-dried soil was 30.7% higher than that from field-moist soil. For field-moist soil, extraction efficiencies of the batch extraction (67.2% and 81.5%) were better than that for column extraction (65.6%). However, this difference between the two methods became less significant for the air-dried soil, with a total removal rate of 96.3% for column extraction and 90.2% and 97% for batch extractions. A mass-balance test was carried out for analytical quality assurance. The results of both batch and column experiments indicated that drying the soil increased efficiency of extraction of PAHs from the MGP soil.

  3. Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

    SciTech Connect

    Sleiman, Mohamad; Kirchstetter, Thomas W.; Berdahl, Paul; Gilbert, Haley E.; Quelen, Sarah; Marlot, Lea; Preble, Chelsea V.; Chen, Sharon; Montalbano, Amandine; Rosseler, Olivier; Akbari, Hashem; Levinson, Ronnen; Destaillats, Hugo

    2014-01-09

    Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon, humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products₋single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles₋and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. In conclusion, this accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.

  4. Calibrated, late Quaternary age indices using clast rubification and soil development on alluvial surfaces in Pilot Knob Valley, Mojave Desert, southeastern California

    NASA Astrophysics Data System (ADS)

    Helms, John G.; McGill, Sally F.; Rockwell, Thomas K.

    2003-11-01

    The orange coating (varnish) that forms on the undersides (ventral sides) of clasts in desert pavements constitutes a potential relative-age indicator. Using Munsell color notation, we semiquantified the color of the orange, ventral varnish on the undersides of clasts from 15 different alluvial fan and terrace surfaces of various ages ranging from less than 500 to about 25,000 yr. All of the surfaces studied are located along the central portion of the left-lateral Garlock fault, in the Mojave Desert of southern California. The amount of left-lateral offset may be used to determine the relative ages of the surfaces. The previously published slip rate of the fault may also be used to estimate the absolute age of each surface. The color of the ventral varnish is strongly correlated with surface age and appears to be a more reliable age-indicator than the percentage coverage of dorsal varnish. Soil development indices also were not as strongly correlated with age, as were the colors of the ventral varnish. In particular, rubification appears to be more useful than soils for distinguishing relative ages among Holocene surfaces. Humidity sensors indicated that the undersides of clasts condensed moisture nightly for a period of several days to over a week after each rain. These frequent wet-dry cycles may be responsible for the rapid development of clast rubification on Holocene surfaces.

  5. Potassium permanganate oxidation of phenanthrene and pyrene in contaminated soils.

    PubMed

    de Souza e Silva, Paula Tereza; da Silva, Valdinete Lins; Neto, Benício de Barros; Simonnot, Marie-Odile

    2009-09-15

    Potassium permanganate, widely used in water treatment, has shown its applicability to reduce PAH contamination in groundwater and soils. The first stage to design a treatment at the site scale is the feasibility study at the bench scale, generally performed by means of batch experiments. The aim of the present contribution was to investigate the influence of two factors on PAH degradation in spiked soils, following the method of factorial designs. These factors were the weight ratio KMnO(4)/PAH and the reaction time. Three factorial designs were performed and batch experiments were run to study the degradation of phenanthrene and pyrene on soils spiked at different concentrations, between 700 and 2100 mg kg(-1). We showed that treatment with potassium permanganate significantly reduced PAH concentration, but pyrene was more recalcitrant than phenanthrene. Both variables had negative main effects and a positive two-factor interaction effect: increasing the weight ratio or the reaction time enhanced PAH degradation but the reduction produced by the two factors was lower than the sum of the individual contributions. The comparison of these results with results that we published previously under comparable conditions showed that Fenton's reagent was more efficient than potassium permanganate.

  6. Reduction of polycyclic aromatic hydrocarbons (PAHs) from petroleum-contaminated soil using thermal desorption technology

    SciTech Connect

    Silkebakken, D.M.; Davis, H.A.; Ghosh, S.B.; Beardsley, G.P.

    1995-12-31

    The remediation of petroleum-contaminated soil typically requires the selection of a treatment option that addresses the removal of both volatile and semi-volatile organic compounds. Volatile organic compounds (VOCs), primarily BTEX (benzene, toluene, ethylbenzene, and xylenes) compounds, can be readily removed from the soil by a variety of well-established technologies. The semivolatile organic compounds, especially the polycyclic aromatic hydrocarbons (PAHS) that are characteristic of petroleum-contaminated soil, are not as amenable to conventional treatment. Low temperature thermal volatilization (LTTV) can be a viable treatment technology depending on the initial contaminant concentrations present and applicable cleanup objectives that must be attained. A-two-phase treatability study was conducted at 14 former underground storage tank (UST) sites to evaluate the applicability and effectiveness of LTTV for remediation of approximately 31,000 tons of PAH-contaminated soil. The PAHs of primary concern included benzo(a)anthracene, chrysene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, dibenz(a,h) anthracene, and indeno(1,2,3-cd)pyrene. During Phase 1, LTTV operational parameters were varied by trial-and-error and changes in soil treatment effectiveness were monitored. Phase B of the treatability study incorporated the appropriate treatment regime established during Phase 1 to efficiently remediate the remaining contaminated soil.

  7. Use of nutrient supplements to increase the microbial degradation of PAH in contaminated soils

    SciTech Connect

    Carmichael, L.M.; Pfaender, F.K.

    1994-12-31

    The microbial degradation of polycyclic aromatic hydrocarbons (PAH) is often low in soils due to unavailability of PAH and/or to conditions in the soil that are not favorable to microbial activity. As a result, successful bioremediation of PAH contaminated soils may require the addition of supplements to impact PAH availability or soil conditions. This paper reports on the addition of supplements (Triton X-100, Inopol, nutrient buffer, an organic nutrient solution, salicylic acid) on the fate of (9-{sup 14}C) phenanthrene, a model PAH, in creosote contaminated soils. Phenanthrene metabolism was assessed using a mass balance approach that accounts for metabolism of phenanthrene to CO{sub 2}, relative metabolite production, and uptake of phenanthrene into cells. Most of the supplements did not drastically alter the fate of phenanthrene in the contaminated soils. Additions of Inopol, however, increased phenanthrene mineralization, while salicylic acid decreased phenanthrene mineralization but greatly increased the production of polar and water soluble metabolites. All supplements (excluding salicylic acid and the organic nutrient solution) increased populations of heterotrophic microorganisms, as measured by plate counts. Phenanthrene degrader populations, however, were only slightly increased by additions of the nutrient buffer, as measured by the Most Probable Number assay.

  8. Evaluation of aromatic pathway induction for creosote contaminated soils in slurried soil media designed to achieve environmentally acceptable treatment endpoints

    SciTech Connect

    Glaser, J.; McCauley, P.; Potter, C.; Herrmann, R.; Dosani, M.

    1995-12-31

    Polyaromatic hydrocarbon contaminants (PAHs) are commonly associated with the use of creosote for wood preservation and the process residues left by municipal gas production. The biological treatment of this set of organic compounds has been found to be difficult since they have low water solubility and reactivity in soil systems. Liquid culture studies have shown that inducer chemicals may assist the biotreatment of PAH contaminated soils. A set of designed experimental treatments were conducted to evaluate the incorporation of potential inducer compounds. The inducers chosen for evaluation were 2-hydroxybenzoic acid and phthalic acid with treatment controls of 3-hydroxybenzoic acid and terephthalic acid at three concentrations in slurried creosote-contaminated soil. An abiotic treatment control of formaldehyde was used for contrast. The designed treatment evaluation used 250mL Erlenmeyer flask slurry reaction vessels. The flask study used an orbital shaker to maintain slurry suspension. At selected time points throughout the study individual flask reactors were sacrificed and the contents were analyzed for PAH concentration, nutrients, and biomass (FAME Analysis). Depletion of individual PAHs, total PAHs, 2 and 3-ring, and 4 and 6-ring PAHs was correlation with the biomass. The effect of selected surfactant addition was also evaluated. Rates of PAH depletion and applications to larger scale investigations will be discussed.

  9. [Study on degradation of polycyclic aromatic hydrocarbons (PAHs) with different additional carbon sources in aged contaminated soil].

    PubMed

    Yin, Chun-Qin; Jiang, Xin; Wang, Fang; Wang, Cong-Ying

    2012-02-01

    This study was conducted with different additional carbon sources (such as: glucose, DL-malic acid, citrate, urea and ammonium acetate) to elucidate the degradation of polycyclic aromatic hydrocarbons (PAHs) in aged contaminated soil under an indoor simulation experiment. The results showed that the quantity of CO2 emission in different additional carbon sources treatments was obviously much more than that of check treatment in the first week, and the quantity of CO2 emission in DL-malic acid treatment was the largest. The average CO2 production decreased in an order urea > glucose approximately citrate approximately DL-malic acid approximately ammonium acetate > check. Meanwhile, the amount of volatized PAHs in applied carbon sources treatments was significantly less than that in check treatment. The amount of three volatized PAHs decreased in an order phenanthrene > fluoranthene > benzo(b)fluoranthene. Compared with the check treatment, the average degradation rates of the three PAHs were significantly augmented in the supplied carbon sources treatments, in which rates of the three PAHs were much higher in DL-malic acid and urea treatments than those in other treatments. The largest proportion of residual was benzo(b)fluoranthene (from 72% to 81%) among three PAHs compounds, followed by fluoranthene (from 53% to 70% ) and phenanthrene (from 27% to 44%).

  10. The diversity of arbuscular mycorrhizal fungi amplified from grapevine roots (Vitis vinifera L.) in Oregon vineyards is seasonally stable and influenced by soil and vine age.

    PubMed

    Schreiner, R Paul; Mihara, Keiko L

    2009-01-01

    The diversity of arbuscular mycorrhizal fungi (AMF) in 10 Oregon vineyards was assessed by examining spores in soil and amplifying mycorrhizal DNA from roots. Seventeen spore morphotypes were found in soil, including seven species in the Acaulosporaceae. Eighteen phylotypes were amplified from grape roots with AM1 and NS31 primers, and clones were dominated by Glomus spp. (> 99%). A few clones (< 1%) representing a single phylotype within Gigasporaceae, and a single clone within Archaeosporaceae were amplified from roots with AM1-NS31 primers. A separate experiment employing known proportions of grape roots colonized by Glomus intraradices or by Gigaspora rosea showed that fungi within Gigasporaceae might be underrepresented in clone abundance when Glomus spp. co-occur in roots. No clones representing fungi within the Acaulosporaceae were amplified from vineyards, although specific fungi within Acaulosporaceae were shown to colonize Pinot noir roots in sterilized soil and were amplified from these roots. Four Glomus phylotypes, including G. intraradices, were found in roots from all 10 vineyards, and these fungi accounted for 81% of clones. AMF phylotypes amplified from roots did not change during the growing season, although six phylotypes varied with soil type. The presence of three phylotypes was affected by vineyard age, and phylotype richness appeared to decline as vineyard age increased beyond 20 y. PCA analysis supported the hypothesis that the AMF community is different in red-hill soils than in valley soils and indicated certain phylotypes might be associated with lower soil and vine nutrient status. However, the changes in the AMF community in grape roots across vineyards were subtle because most root samples were dominated by the same three or four phylotypes. A separate analysis using primers to amplify AMF from the Archeasporaceae/Paraglomeraceae showed most root samples also were colonized by at least one Paraglomus or Archaeospora phylotype.

  11. Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests.

    PubMed

    Waring, Bonnie G; Adams, Rachel; Branco, Sara; Powers, Jennifer S

    2016-01-01

    Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling. PMID:26390155

  12. Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests.

    PubMed

    Waring, Bonnie G; Adams, Rachel; Branco, Sara; Powers, Jennifer S

    2016-01-01

    Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling.

  13. Toxicological responses of red-backed salamander (Plethodon cinereus) exposed to aged and amended soils containing lead.

    PubMed

    Bazar, Matthew A; Quinn, Michael J; Mozzachio, Kristie; Bleiler, John A; Archer, Christine R; Phillips, Carlton T; Johnson, Mark S

    2010-05-01

    The use of lead in military and civilian small arms projectiles is widely acknowledged to have resulted in high soil lead concentrations at many small arms ranges. These ranges are often adjacent to wildlife habitat or have become habitat when no longer used. To assess the potential toxicity of lead to terrestrial amphibians in contaminated areas, we exposed 100 red-backed salamanders (Plethodon cinereus) to either a control soil or one of four soil treatments amended with lead acetate for 28 days. Analytical mean soil concentrations were 14 (control), 553, 1700, 4700, and 9167 mg Pb/kg soil dry weight. An additional 60 salamanders were also exposed for 28 days to one of six field-collected soil samples from a small arms range and a skeet range. The field soil concentrations ranged from 11 (background) to 16,967 mg Pb/kg soil dry weight. Food consisted of uncontaminated flightless Drosophila melanogaster. Salamander survival was reduced in amended soil treatments of 4700 and 9167 mg/kg by 15% and 80%, respectively. Inappetence was observed at 4700 and 9167 mg/kg and growth decreased in the 9167 mg/kg treatment. Total white blood cells decreased 32% at 4700 mg/kg compared to controls and were 22% lower in the 9167 mg/kg treatment. In contrast, survival was 100% for all field-collected soils with no hematological effects. At 16,967 mg/kg there was evidence of soil avoidance and decreased growth. These data suggest marked differences in toxicity and bioavailability of the lead-amended soil in contrast to the field-collected soil containing lead.

  14. Composition, sources, and potential toxicology of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in Liaoning, People's Republic of China.

    PubMed

    Cao, Xiu Feng; Liu, Miao; Song, Yu Fang; Ackland, M Leigh

    2013-03-01

    Surface soil (0-20 cm) samples (n = 143) were collected from vegetable, maize, and paddy farmland used for commercial crops in Liaoning, China. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) listed in US Environmental Protection Agency were analyzed by high-performance liquid chromatography using a fluorescence detector. The soil concentrations of the 16 PAH ranged from 50 to 3,309 ng/g with a mean of 388 ng/g. The highest concentration of total PAHs found in soil of the vegetable farmland was 448 ng/g in average, followed by maize and paddy with total PAHs of 391 and 331 ng/g, respectively. Generally, the low molecular weight PAHs were more predominant than the high molecular weight PAHs in most of the soils. The evaluation of soil PAH contamination based on the Canadian criterion indicated that only naphthalene, phenanthrene, and pyrene were over the target values in several sampling sites. Isomer pair ratios and principal component analysis indicated that biomass and coal combustion were the main sources of PAHs in this area. And the average value of total B[a]Peq concentration in vegetable soils was higher than paddy and maize soils. We suggest that biomass burning should be abolished and commercial farming should be carried out far from the highways to ensure the safety of food products derived from commercial farming.

  15. Ecotoxicological risks associated with land treatment of petrochemical wastes. I. Residual soil contamination and bioaccumulation by cotton rats (Sigmodon hispidus).

    PubMed

    Schroder, Jackie; Basta, Nicholas; Payton, Mark; Wilson, James; Carlson, Ruth; Janz, David; Lochmiller, Robert

    2003-02-28

    Petrochemical waste contains both organic and inorganic contaminants that can pollute soil and may pose significant ecological risks to wildlife. Petrochemical waste typically is disposed of in land treatment units, which are widespread throughout Oklahoma and the United States. Few studies have been conducted evaluating possible toxicity risks to terrestrial organisms residing on these units. In this study, the extent of soil contamination with fluoride (F), metals, and organic hydrocarbons, the bioaccumulation of F and metals in cotton rats (Sigmodon hispidus), the relationship between contaminants in soil and in tissues of cotton rats, and the level of potentially toxic polycyclic aromatic hydrocarbons (PAHs) in soil were determined on land treatment units. Over a 2-yr period, cotton rats and soils were collected and analyzed from 5 land treatment and matched reference units. The number of land treatment units with soil metal contamination (in parentheses) included: Cr, Cu, Pb (5). Al, As, Ni, Sr, Zn (4). Ba (3). and Cd, V (2). The number of land treatment units with soil PAH contamination (in parentheses) were naphthalene, phenanthrene, benzo[g,h,i]perylene (3). acenaphthene, anthracene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenz[a,h]anthracene (2). and acenaphthylene, fluorene, fluoranthene, benzo[k]fluoranthene (1). Total PAH and total petroleum hydrocarbons (TPH) were elevated at all five land treatment units. Mean sums of benzo[a]pyrene (BaP) equivalents (BaPequiv ) were not affected on

  16. Oral Bioavailability, Bioaccessibility, and Dermal Absorption of PAHs from Soil-State of the Science.

    PubMed

    Ruby, Michael V; Lowney, Yvette W; Bunge, Annette L; Roberts, Stephen M; Gomez-Eyles, Jose L; Ghosh, Upal; Kissel, John C; Tomlinson, Priscilla; Menzie, Charles

    2016-03-01

    This article reviews the state of the science regarding oral bioavailability, bioaccessibility, and dermal absorption of carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in soil by humans, and discusses how chemical interactions may control the extent of absorption. Derived from natural and anthropomorphic origins, PAHs occur in a limited number of solid and fluid matrices (i.e., PAH sources) with defined physical characteristics and PAH compositions. Existing studies provide a strong basis for establishing that oral bioavailability of cPAHs from soil is less than from diet, and an assumption of 100% relative bioavailability likely overestimates exposure to cPAHs upon ingestion of PAH-contaminated soil. For both the oral bioavailability and dermal absorption studies, the aggregate data do not provide a broad understanding of how different PAH source materials, PAH concentrations, or soil chemistries influence the absorption of cPAHs from soil. This article summarizes the existing studies, identifies data gaps, and provides recommendations for the direction of future research to support new default or site-specific bioavailability adjustments for use in human health risk assessment. PMID:26824144

  17. Draft genome sequence of Mycobacterium rufum JS14(T), a polycyclic-aromatic-hydrocarbon-degrading bacterium from petroleum-contaminated soil in Hawaii.

    PubMed

    Kwak, Yunyoung; Li, Qing X; Shin, Jae-Ho

    2016-01-01

    Mycobacterium rufum JS14(T) (=ATCC BAA-1377(T), CIP 109273(T), JCM 16372(T), DSM 45406(T)), a type strain of the species Mycobacterium rufum sp. . belonging to the family Mycobacteriaceae, was isolated from polycyclic aromatic hydrocarbon (PAH)-contaminated soil in Hilo (HI, USA) because it harbors the capability of degrading PAH. Here, we describe the first genome sequence of strain JS14(T), with brief phenotypic characteristics. The genome is composed of 6,176,413 bp with 69.25 % G + C content and contains 5810 protein-coding genes with 54 RNA genes. The genome information on M. rufum JS14(T) will provide a better understanding of the complexity of bacterial catabolic pathways for degradation of specific chemicals.

  18. Draft genome sequence of Mycobacterium rufum JS14(T), a polycyclic-aromatic-hydrocarbon-degrading bacterium from petroleum-contaminated soil in Hawaii.

    PubMed

    Kwak, Yunyoung; Li, Qing X; Shin, Jae-Ho

    2016-01-01

    Mycobacterium rufum JS14(T) (=ATCC BAA-1377(T), CIP 109273(T), JCM 16372(T), DSM 45406(T)), a type strain of the species Mycobacterium rufum sp. . belonging to the family Mycobacteriaceae, was isolated from polycyclic aromatic hydrocarbon (PAH)-contaminated soil in Hilo (HI, USA) because it harbors the capability of degrading PAH. Here, we describe the first genome sequence of strain JS14(T), with brief phenotypic characteristics. The genome is composed of 6,176,413 bp with 69.25 % G + C content and contains 5810 protein-coding genes with 54 RNA genes. The genome information on M. rufum JS14(T) will provide a better understanding of the complexity of bacterial catabolic pathways for degradation of specific chemicals. PMID:27486485

  19. The age of root and soil respired CO2 in a Pacific Northwest old-growth forest: Implications of seasonality and drought effects on carbon source use

    NASA Astrophysics Data System (ADS)

    Taylor, A.; Hopkins, F. M.; Lai, C.; Xu, X.; Randerson, J. T.; Bush, S.; Ehleringer, J. R.

    2013-12-01

    Abstract Climate change has the potential to impact the carbon (C) cycle in unknown ways. Factors such as temperature, light, and moisture can strongly influence whether forest ecosystems are net sources or sinks of CO2. In this study, we used radiocarbon (14C) to determine the age and source of soil- and root-respired CO2 using a combination of soil chamber and biomass incubation measurements in an old-growth forest at the Wind River Field Station, WA. We had two main goals for this study. The first was to determine if the contribution of recent photosynthate to root respiration changed between spring and summer seasons. 14C measurements were used to determine the average age of respired CO2, since respired CO2 fueled by recent photosynthates have Δ14C values similar to that of the current atmosphere (~ 25‰ in 2012), whereas C stored by trees from prior years would be 30‰ or higher. This study occurred over two growing seasons, examining the effects of seasonality and water stress on root/soil respiration. Because of the summer drought conditions consistently experienced by this old-growth forest, this study provides a new dataset to test the hypothesis that plants allocate their C resources in response to stress. Initial results showed soil organic matter components had Δ14C values 80-120‰ greater than that of the background atmosphere, suggesting turnover times on the order of years to decades. In contrast, root respiration was much lower in Δ14C (~40‰), but still elevated with respect to current atmospheric Δ14C values, suggesting that root respiration was at least partially composed of C stored for > 1 year. The second goal was to partition the contribution of autotrophic to heterotrophic respiration and to determine how this ratio differs on diurnal and seasonal timescales. We used the difference between autotrophic and heterotrophic Δ14C values to partition total soil respiration. Preliminary results for April 2013 showed that ~1/3 of soil

  20. Iron and aluminum soil/paleosol extractions as age/environment indicators: Some examples from a catchment in southern Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Mahaney, William C.; Hancock, Ronald G. V.; Somelar, Peeter; Milan, Alison

    2016-10-01

    Various chemical extractions of Fe and Al from bulk soil samples, including Na-pyrophosphate (Fep, Alp), acid ammonium oxalate (Feo, Alo), and Na-dithionite (Fed, Ald), have been used over the last half century to distinguish soil ages over varying time frames from 102 to 106 years and even as far into antiquity as the Oligocene (30 × 106) years. Problems with mineral/chemical uniformity of sediments, free drainage of open system profiles, and variable climate over long time frames have produced problems and uncertainties as to just what each extraction removes from the bulk material analyzed. Some problems have been resolved by the work of Parfitt and Childs (1988); but some persist, especially with respect to the solubility of some extractant forms and the actual composition of others, particularly Alp, Alo, and Ald. A recent test of soils and paleosols in a fluvial chronosequence in southern Ontario illustrates the soil-paleosol evolutionary time trend over a period of ~ 11 ky, essentially post-Iroquois time in the Ontario basin (Jackson et al., 2000). This work highlights the importance of isolated, free draining weathering systems, mineral uniformity, and new relationships between secondary forms of Fed and Ald, the latter previously considered of little importance in age relationship quests.

  1. Enhanced dissipation of polycyclic aromatic hydrocarbons in the rhizosphere of the Athel tamarisk (Tamarix aphylla L. Karst.) grown in saline-alkaline soils of the former lake Texcoco.

    PubMed

    Betancur-Galvis, Liliana A; Carrillo, Hernando; Luna-Guido, Marco; Marsch, Rodolfo; Dendooven, Luc

    2012-09-01

    Remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated alkaline saline soil with phreatophyte or "water loving plants" was investigated by spiking soil from the former lake Texcoco with 100 mg phenanthrene (Phen) kg(-1) soil, 120 mg anthracene (Ant)kg(-1) soil and 45 mg benzo(a)pyrene (BaP) kg(-1) soil and vegetating it with Athel tamarisk (Tamarix aphylla L Karst.). The growth of the Athel tamarisk was not affected by the PAHs. In soil cultivated with Athel tamarisk, the leaching of PAHs to the 32-34 cm layer decreased 2-fold compared to the uncultivated soil. The BaP concentration decreased to 39% of the initial concentration at a distance smaller than 3 cm from the roots and to 45% at a distance larger than 3cm, but 59% remained in unvegetated soil after 240 days. Dissipation of Ant and Phen decreased with depth, but not BaP. The biodegradation of PAHs was affected by their chemical properties and increased in the presence of T. aphylla, but decreased with depth.

  2. Characteristics of polycyclic aromatic hydrocarbons in agricultural soils at a typical coke production base in Shanxi, China.

    PubMed

    Duan, Yonghong; Shen, Guofeng; Tao, Shu; Hong, Jianping; Chen, Yuanchen; Xue, Miao; Li, Tongchao; Su, Shu; Shen, Huizhong; Fu, Xiaofang; Meng, Qingchun; Zhang, Jing; Zhang, Bing; Han, Xiaoying; Song, Kang

    2015-05-01

    There is wide concern about polycyclic aromatic hydrocarbons (PAHs) because of their carcinogenic and mutagenic potential. The coking industry is an important source of PAHs. In this study, 36 arable soil samples, a sensitive medium from the perspective of food safety and health, were collected from one of the largest coke production bases in China. The concentration of total 21 PAHs ranged from 294 to 1665 ng g(-1), with a mean of 822±355 ng g(-1). Approximately 60% of the soil samples were heavily polluted with the level higher than 600 ng g(-1). Particularly high abundances of high molecular weight PAHs were found, and the calculated BaPeq was as high as 54.3 ng g(-1). Soil PAH levels were positively correlated with soil organic matter content. The soil PAHs were from complex mixture sources, and high-temperature pyrogenic sources were most likely responsible for the heavy PAH contamination. Effective control strategies and probable remediation approaches should be proposed to improve soil quality.

  3. The impact of biochars on sorption and biodegradation of polycyclic aromatic hydrocarbons in soils--a review.

    PubMed

    Anyika, Chinedum; Abdul Majid, Zaiton; Ibrahim, Zahara; Zakaria, Mohamad Pauzi; Yahya, Adibah

    2015-03-01

    Amending polycyclic aromatic hydrocarbon (PAH)-contaminated soils with biochar may be cheaper and environmentally friendly than other forms of organic materials. This has led to numerous studies on the use of biochar to either bind or stimulate the microbial degradation of organic compounds in soils. However, very little or no attention have been paid to the fact that biochars can give simultaneous impact on PAH fate processes, such as volatilization, sorption and biodegradation. In this review, we raised and considered the following questions: How does biochar affect microbes and microbial activities in the soil? What are the effects of adding biochar on sorption of PAHs? What are the effects of adding biochar on degradation of PAHs? What are the factors that we can manipulate in the laboratory to enhance the capability of biochars to degrade PAHs? A triphasic concept of how biochar can give simultaneous impact on PAH fate processes in soils was proposed, which involves rapid PAH sorption into biochar, subsequent desorption and modification of soil physicochemical properties by biochar, which in turn stimulates microbial degradation of the desorbed PAHs. It is anticipated that biochar can give simultaneous impact on PAH fate processes in soils.

  4. Degradation of phenanthrene and pyrene in spiked soils by single and combined plants cultivation.

    PubMed

    Cheema, Sardar Alam; Imran Khan, Muhammad; Shen, Chaofeng; Tang, Xianjin; Farooq, Muhammad; Chen, Lei; Zhang, Congkai; Chen, Yingxu

    2010-05-15

    The present study was conducted to investigate the capability of four plant species (tall fescue, ryegrass, alfalfa, and rape seed) grown alone and in combination to the degradation of phenanthrene and pyrene (polycyclic aromatic hydrocarbons, PAHs) in spiked soil. After 65 days of plant growth, plant biomass, dehydrogenase activity, water-soluble phenolic (WSP) compounds, plant uptake and accumulation and residual concentrations of phenanthrene and pyrene were determined. Our results showed that presence of vegetation significantly enhanced the dissipation of phenanthrene and pyrene from contaminated soils. Higher degradation rates of PAHs were observed in the combined plant cultivation (98.3-99.2% phenanthrene and 88.1-95.7% pyrene) compared to the single plant cultivation (97.0-98.0% phenanthrene and 79.8-86.0% pyrene). Contribution of direct plant uptake and accumulation of phenanthrene and pyrene was very low compared to the plant enhanced dissipation. By contrast, plant-promoted biodegradation was the predominant contribution to the remediation enhancement. The correlation analysis indicates a negative relation between biological activities (dehydrogenase activity and WSP compounds) and residual concentrations of phenanthrene and pyrene in planted soils. Our results suggest that phytoremediation could be a feasible choice for PAHs contaminated soil. Moreover, the combined plant cultivation has potential to enhance the process.

  5. Surfactant-Enhanced Desorption and Biodegradation of Polycyclic Aromatic Hydrocarbons in Contaminated Soil

    PubMed Central

    Zhu, Hongbo; Aitken, Michael D.

    2010-01-01

    We evaluated two nonionic surfactants, one hydrophobic (Brij 30) and one hydrophilic (C12E8), for their ability to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil after it had been treated in an aerobic bioreactor. The effects of each surfactant were evaluated at doses corresponding to equilibrium aqueous-phase concentrations well above the surfactant’s critical micelle concentration (CMC), slightly above the CMC, and below the CMC. The concentrations of all 3- and 4-ring PAHs were significantly lower in the soil amended with Brij 30 at the two lower doses compared to controls, whereas removal of only the 3-ring PAHs was significantly enhanced at the highest Brij 30 dose. In contrast, C12E8 did not enhance PAH removal at any dose. In the absence of surfactant, <5% of any PAH desorbed from the soil over an 18-d period. Brij 30 addition at the lowest dose significantly increased the desorption of most PAHs, whereas the addition of C12E8 at the lowest dose actually decreased the desorption of all PAHs. These findings suggest that the effects of the two surfactants on PAH biodegradation could be explained by their effects on PAH bioavailability. Overall, this study demonstrates that the properties of the surfactant and its dose relative to the corresponding aqueous-phase concentration are important factors in designing systems for surfactant-enhanced bioremediation of PAH-contaminated soils in which PAH bioavailability is limited. PMID:20586488

  6. Application of aqueous saponin on the remediation of polycyclic aromatic hydrocarbons-contaminated soil.

    PubMed

    Kobayashi, Takayuki; Kaminaga, Hirohisa; Navarro, Ronald R; Iimura, Yosuke

    2012-01-01

    The aim of this research was to evaluate the feasibility of aqueous saponin for the removal and biodegradation of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil. Dissolution test confirmed the ability of saponin to increase the apparent solubility of the tested 3-5 rings PAH above the critical micelle concentration (approximately 1000 mg/L). Microbial test with pure culture of Sphingomonas sp. showed that saponin significantly enhanced the degradation of pyrene. For example, the percent degradation was 2.1 times higher in the presence of 2500 mg/L saponin than that of control without saponin after 60 hours incubation at around 10(8) CFU/mL initial cell loading. These results suggest that the binding of pyrene with saponin does not pose a serious constraint to bacterial uptake. Contrary to pyrene, saponin was chemically stable against the PAHs degrader. It is also not toxic to the cell at least up to 2500 mg/L. Finally, using a spiked soil sample, extraction tests with 10,000 mg/L of saponin showed that around 52.7% and 0.3% of pyrene was removed from low and high organic spiked soils, respectively. The results from this study indicate that aqueous saponin is appropriate as a washing agent as well as biodegradation enhancer for the detoxification of PAHs-contaminated low organic carbon soil.

  7. Re-cycling of remediated soil--evaluation of leaching tests as tools for characterization.

    PubMed

    Dalgren, Kristin Elgh; Düker, Anders; Arwidsson, Zandra; von Kronhelm, Thomas; van Hees, Patrick A W

    2011-02-01

    In Sweden, leaching tests with deionized water (D.W.) are utilized in risk assessment of materials entering landfills, but implementation of these results to evaluate the risk of spreading of pollutants in the environment is difficult. One problem is that most leaching procedures only consider heavy metals release, whereas organic pollutants are left out. The aim of the present study was to assess the possible pollutant mitigation in four remediated soils, three with heavy metals and one with polycyclic aromatic hydrocarbons (PAH) contamination. The mitigation was evaluated by standardized batch and column leaching tests utilizing three different leaching solutions: D.W., a weak ionic solution (0.001 M CaCl(2)) and an artificially made soil water (ASW). In general, batch leaching tests implied larger contaminant removal than column leaching test, possibly due to the more rough treatment of the soil particles, and guidelines would at times be exceeded by the batch leaching test but not by column leaching tests. Utilization of CaCl(2) was found to release less heavy metal than D.W., whereas the metals mobilized by ASW were removed from solution by the filtration of soil leachates. Low molecular weight PAH was most efficiently mobilized by CaCl(2), while D.W. worked better for high molecular weight PAH. Despite very low initial PAH-concentrations, tap- and groundwater criteria were exceeded by all leaching solutions.

  8. Size-fractionation and characterization of landfill leachate and the improvement of Cu2+ adsorption capacity in soil and aged refuse.

    PubMed

    Lou, Ziyang; Chai, Xiaoli; Niu, Dongjie; Ou, Yuanyang; Zhao, Youcai

    2009-01-01

    Leachate was collected from an anaerobic lagoon at Shanghai Laogang refuse landfill, the largest landfill in China, and the sample was separated into six fractions using micro-filtration membranes, followed by ultra-filtration membranes. Several parameters of the samples were measured, including chemical oxygen demand (COD), total organic carbon (TOC), total solids (TS), pH, total phosphate (TP), total nitrogen (TN), fixed solids (FS), NH4+, orthophosphate, color, turbidity, and conductivity. These parameters were then quantitatively correlated with the molecular weight cutoff of the membrane used. Organic matter in the dissolved fraction (MW<1kDa) predominated in the leachate, accounting for 65% of TOC. Thermal infrared spectroscopy was used to characterize the filter residues. Asymmetric and symmetric stretching of methyl and methylene groups, and of functional groups containing nitrogen and oxygen atoms, were observed. In addition, the ability of two different samples to adsorb heavy metals was tested. Cu2+ was chosen as the representative heavy metal in this study, and the samples were soil; aged refuse, which had spent 8 years in a conventional sanitary landfill; and samples of soil and aged refuse treated for 48h with leachate in the ratio of 5g of sample per 50ml of leachate. Cu2+ uptake by the raw soil was approximately 4.60microg/g, while uptake by the leachate-contacted soil and leachate-contacted aged refuse were 5.66 and 5.11microg/g, respectively. These results show that the organic matter in the leachate enhanced the capacity of aqueous solutions to adsorb Cu2+.

  9. Size-fractionation and characterization of landfill leachate and the improvement of Cu{sup 2+} adsorption capacity in soil and aged refuse

    SciTech Connect

    Lou Ziyang; Chai Xiaoli; Niu Dongjie; Ou Yuanyang; Zhao Youcai

    2009-01-15

    Leachate was collected from an anaerobic lagoon at Shanghai Laogang refuse landfill, the largest landfill in China, and the sample was separated into six fractions using micro-filtration membranes, followed by ultra-filtration membranes. Several parameters of the samples were measured, including chemical oxygen demand (COD), total organic carbon (TOC), total solids (TS), pH, total phosphate (TP), total nitrogen (TN), fixed solids (FS), NH{sub 4}{sup +}, orthophosphate, color, turbidity, and conductivity. These parameters were then quantitatively correlated with the molecular weight cutoff of the membrane used. Organic matter in the dissolved fraction (MW < 1 kDa) predominated in the leachate, accounting for 65% of TOC. Thermal infrared spectroscopy was used to characterize the filter residues. Asymmetric and symmetric stretching of methyl and methylene groups, and of functional groups containing nitrogen and oxygen atoms, were observed. In addition, the ability of two different samples to adsorb heavy metals was tested. Cu{sup 2+} was chosen as the representative heavy metal in this study, and the samples were soil; aged refuse, which had spent 8 years in a conventional sanitary landfill; and samples of soil and aged refuse treated for 48 h with leachate in the ratio of 5 g of sample per 50 ml of leachate. Cu{sup 2+} uptake by the raw soil was {approx}4.60 {mu}g/g, while uptake by the leachate-contacted soil and leachate-contacted aged refuse were 5.66 and 5.11 {mu}g/g, respectively. These results show that the organic matter in the leachate enhanced the capacity of aqueous solutions to adsorb Cu{sup 2+}.

  10. Effects of biochar and Arbuscular mycorrhizae on bioavailability of potentially toxic elements in an aged contaminated soil.

    PubMed

    Qiao, Yuhui; Crowley, David; Wang, Kun; Zhang, Huiqi; Li, Huafen

    2015-11-01

    Biochar pyrolyzed from corn stalks at 300°C/500°C and arbuscular mycorrhizae (AMF) were examined independently and in combination as possible treatments for soil remediation contaminated with Cd, Cr, Ni, Cu, Pb, Zn after 35 years following land application of sewage sludge in the 1970s. The results showed that biochar significantly decreased the heavy metal concentrations and their bioavailability for plants, and both biochars had similar such effects. AMF inoculation of corn plants had little effect on heavy metal bioavailability in either control or biochar amended soil, and no interaction between biochar and AMF was observed. Changes in DTPA extractable metals following biochar addition to soil were correlated with metal uptake by plants, whereas pore water metal concentrations were not predictive indicators. This research demonstrates positive benefits from biochar application for contaminated soil remediation, but remain ambiguous with regard to the benefits of simultaneous AMF inoculation on reduction of heavy metal bioavailability.

  11. Mycoextraction by Clitocybe maxima combined with metal immobilization by biochar and activated carbon in an aged soil.

    PubMed

    Wu, Bin; Cheng, Guanglei; Jiao, Kai; Shi, Wenjin; Wang, Can; Xu, Heng

    2016-08-15

    To develop an eco-friendly and efficient route to remediate soil highly polluted with heavy metals, the idea of mycoextraction combined with metal immobilization by carbonaceous sorbents (biochar and activated carbon) was investigated in this study. Results showed that the application of carbonaceous amendments decreased acid soluble Cd and Cu by 5.13-14.06% and 26.86-49.58%, respectively, whereas the reducible and oxidizable fractions increased significantly as the amount of carbonaceous amendments added increased. The biological activities (microbial biomass, soil enzyme activities) for treatments with carbonaceous sorbents were higher than those of samples without carbonaceous amendments. Clitocybe maxima (C. maxima) simultaneously increased soil enzyme activities and the total number of microbes. Biochar and activated carbon both showed a positive effect on C. maxima growth and metal accumulation. The mycoextraction efficiency of Cd and Cu in treatments with carbonaceous amendments enhanced by 25.64-153.85% and 15.18-107.22%, respectively, in response to that in non-treated soil, which showed positive correlation to the augment of biochar and activated carbon in soil. Therefore, this work suggested the effectiveness of mycoextraction by C. maxima combined the application of biochar and activated carbon in immobilising heavy metal in contaminated soil.

  12. Implications of polluted soil biostimulation and bioaugmentation with spent mushroom substrate (Agaricus bisporus) on the microbial community and polycyclic aromatic hydrocarbons biodegradation.

    PubMed

    García-Delgado, Carlos; D'Annibale, Alessandro; Pesciaroli, Lorena; Yunta, Felipe; Crognale, Silvia; Petruccioli, Maurizio; Eymar, Enrique

    2015-03-01

    Different applications of spent Agaricus bisporus substrate (SAS), a widespread agro-industrial waste, were investigated with respect to the remediation of a historically polluted soil with Polycyclic Aromatic Hydrocarbons (PAH). In one treatment, the waste was sterilized (SSAS) prior to its application in order to assess its ability to biostimulate, as an organic amendment, the resident soil microbiota and ensuing contaminant degradation. For the other treatments, two bioaugmentation approaches were investigated; the first involved the use of the waste itself and thus implied the application of A. bisporus and the inherent microbiota of the waste. In the second treatment, SAS was sterilized and inoculated again with the fungus to assess its ability to act as a fungal carrier. All these treatments were compared with natural attenuation in terms of their impact on soil heterotrophic and PAH-degrading bacteria, fungal growth, biodiversity of soil microbiota and ability to affect PAH bioavailability and ensuing degradation and detoxification. Results clearly showed that historically PAH contaminated soil was not amenable to natural attenuation. Conversely, the addition of sterilized spent A. bisporus substrate to the soil stimulated resident soil bacteria with ensuing high removals of 3-ring PAH. Both augmentation treatments were more effective in removing highly condensed PAH, some of which known to possess a significant carcinogenic activity. Regardless of the mode of application, the present results strongly support the adequacy of SAS for environmental remediation purposes and open the way to an attractive recycling option of this waste.

  13. Implications of polluted soil biostimulation and bioaugmentation with spent mushroom substrate (Agaricus bisporus) on the microbial community and polycyclic aromatic hydrocarbons biodegradation.

    PubMed

    García-Delgado, Carlos; D'Annibale, Alessandro; Pesciaroli, Lorena; Yunta, Felipe; Crognale, Silvia; Petruccioli, Maurizio; Eymar, Enrique

    2015-03-01

    Different applications of spent Agaricus bisporus substrate (SAS), a widespread agro-industrial waste, were investigated with respect to the remediation of a historically polluted soil with Polycyclic Aromatic Hydrocarbons (PAH). In one treatment, the waste was sterilized (SSAS) prior to its application in order to assess its ability to biostimulate, as an organic amendment, the resident soil microbiota and ensuing contaminant degradation. For the other treatments, two bioaugmentation approaches were investigated; the first involved the use of the waste itself and thus implied the application of A. bisporus and the inherent microbiota of the waste. In the second treatment, SAS was sterilized and inoculated again with the fungus to assess its ability to act as a fungal carrier. All these treatments were compared with natural attenuation in terms of their impact on soil heterotrophic and PAH-degrading bacteria, fungal growth, biodiversity of soil microbiota and ability to affect PAH bioavailability and ensuing degradation and detoxification. Results clearly showed that historically PAH contaminated soil was not amenable to natural attenuation. Conversely, the addition of sterilized spent A. bisporus substrate to the soil stimulated resident soil bacteria with ensuing high removals of 3-ring PAH. Both augmentation treatments were more effective in removing highly condensed PAH, some of which known to possess a significant carcinogenic activity. Regardless of the mode of application, the present results strongly support the adequacy of SAS for environmental remediation purposes and open the way to an attractive recycling option of this waste. PMID:25437949

  14. Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

    NASA Astrophysics Data System (ADS)

    Lobo, E.; Dalling, J. W.

    2013-11-01

    Treefall gaps are the major source of disturbance in most tropical forests. The frequency and size of these gaps have important implications for forest ecosystem processes as they can influence the functional trait distribution of tree communities, stand-level aboveground biomass and productivity. However, we still know little about the relative importance of environmental drivers of gap disturbance regimes because existing studies vary greatly in criteria used for defining gaps, in the spatial extent of the study area, and the spatial resolution of canopy height measurements. Here we use lidar (light detecting and ranging) to explore how forest age, topography and soil type affect canopy disturbance patterns across a 1500 ha tropical forest landscape in central Panama. We characterize disturbance based on the frequency distribution of gap sizes (the "gap size distribution"), and the area of the forest affected by gaps (the "gap area fraction"). We found that slope and forest age had significant effects on the gap size distribution, with a higher frequency of large gaps associated with old-growth forests and more gentle slopes. Slope and forest age had similar effects on the gap area fraction, however gap area fraction was also affected by soil type and by aspect. We conclude that variation in disturbance patterns across the landscape can be linked to factors that act at the fine scale (such as aspect or slope), and factors that show heterogeneity at coarser scales (such as forest age or soil type). Awareness of the role of different environmental factors influencing gap formation can help scale up the impacts of canopy disturbance on forest communities measured at the plot scale to landscape and regional scales.

  15. Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

    NASA Astrophysics Data System (ADS)

    Lobo, E.; Dalling, J. W.

    2013-04-01

    Treefall gaps are the major source of disturbance in most tropical forests. The frequency and size of these gaps have important implications for forest ecosystem processes as they can influence the functional trait distribution of tree communities, stand-level above-ground biomass and productivity. However, we still know little about the relative importance of environmental drivers of gap disturbance regimes because existing studies vary greatly in criteria used for defining gaps, in the spatial extent of the study area, and the spatial resolution of canopy height measurements. Here we use LiDAR (light detecting and ranging) to explore how forest age, topography and soil type affect canopy disturbance patterns across a 1500 ha tropical forest landscape in central Panama. We characterize disturbance based on the frequency distribution of gap sizes (the "gap size distribution"), and the area of the forest affected by gaps (the "gap area fraction"). We found that slope and forest age had significant effects on the gap size distribution, with a higher frequency of large gaps associated with old-growth forests and more gentle slopes. Slope and forest age had similar effects on the gap area fraction, however gap area fraction was also affected by soil type and by aspect. We conclude that variation in disturbance patterns across the landscape can be linked to factors that act at the fine scale (such as aspect or slope), and factors that show heterogeneity at coarser scales (such as forest age or soil type). Awareness of the role of different environmental factors influencing gap formation can help scale-up the impacts of canopy disturbance on forest communities measured at the plot scale to landscape and regional scales.

  16. Structure and function of soil microbial community in artificially planted Sonneratia apetala and S. caseolaris forests at different stand ages in Shenzhen Bay, China.

    PubMed

    Yang, Q; Lei, A P; Li, F L; Liu, L N; Zan, Q J; Shin, P K S; Cheung, S G; Tam, N F Y

    2014-08-30

    The present study examined the relationships between soil characteristics, microbial community structure and function in the forests artificially planted with exotic Sonneratia apetala at stand ages of 1-, 2-, 7-, 10- and 14-years and Sonneratia caseolaris of 1-, 4-, 7-, 10- and 14-years in Futian National Nature Reserve, Shenzhen Bay, China. The 7-years old forests of both Sonneratia species reached peak growth and had the highest content of nitrogen and phosphorus, enzymatic activities, including dehydrogenase, cellulase, phosphatase, urease and ß-glucosidase, except arylsulphatase which increased continuously with stand ages. The microbial community structure reflected by phospholipid fatty acid (PLFA) profiles also reached the maximum value in the 7-years old forests and soil bacterial PLFAs in both forests were significantly higher than fungal PLFAs. The canonical correlation analysis revealed that differences in microbial structural variables were significantly correlated to the differences in their functional variables, and the highest correlation was found between the soil enzymatic activities and the content of carbon and nitrogen.

  17. Leaf-age and soil-plant relationships: key factors for reporting trace-elements hyperaccumulation by plants and design applications.

    PubMed

    Losfeld, Guillaume; L'Huillier, Laurent; Fogliani, Bruno; Mc Coy, Stéphane; Grison, Claude; Jaffré, Tanguy

    2015-04-01

    Relationships between the trace-elements (TE) content of plants and associated soil have been widely investigated especially to understand the ecology of TE hyperaccumulating species to develop applications using TE phytoextraction. Many studies have focused on the possibility of quantifying the soil TE fraction available to plants, and used bioconcentration (BC) as a measure of the plants ability to absorb TE. However, BC only offers a static view of the dynamic phenomenon of TE accumulation. Accumulation kinetics are required to fully account for TE distributions in plants. They are also crucial to design applications where maximum TE concentrations in plant leaves are needed. This paper provides a review of studies of BC (i.e. soil-plant relationships) and leaf-age in relation to TE hyperaccumulation. The paper focuses of Ni and Mn accumulators and hyperaccumulators from New Caledonia who were previously overlooked until recent Ecocatalysis applications emerged for such species. Updated data on Mn hyperaccumulators and accumulators from New Caledonia are also presented and advocate further investigation of the hyperaccumulation of this element. Results show that leaf-age should be considered in the design of sample collection and allowed the reclassification of Grevillea meisneri known previously as a Mn accumulator to a Mn hyperaccumulator. PMID:25138558

  18. Cultivation of Tuber melanosporum in firebreaks: short-term persistence of the fungus and effect of seedling age and soil treatment.

    PubMed

    Garcia-Barreda, Sergi; Reyna, Santiago

    2013-01-01

    Wildfires are a major threat to Mediterranean forests. Firebreaks are built as a prevention measure, but require a periodic and expensive maintenance. Cultivating the ectomycorrhizal mushroom Tuber melanosporum Vitt. in firebreaks could reduce costs and improve their sustainability. But firebreaks are built on forest soil, considered nonoptimum for T. melanosporum cultivation. A pot experiment was used to study the persistence of T. melanosporum in firebreak soils in the short term, as a first step to assess the viability of these plantations. The influence of seedlings, soil heating, and liming was also tested. During the 2 y after plantation, T. melanosporum mycorrhizas increased their number, showing its ability to proliferate. Percent root colonisation by native fungi importantly increased from month 12 to 22; although T. melanosporum remained dominant, with a colonisation level similar to those in standard truffle plantations. The age of seedlings at the time of planting influenced T. melanosporum proliferation, supporting a key role for nursery seedling quality in the performance of young plantations. Heating the soil before planting reduced the richness of native fungi, suggesting that this could increase plantation success. The results tend to support the viability of T. melanosporum cultivation in firebreaks, and encourage experimental field plantations.

  19. Electrokinetic-Enhanced Remediation of Phenanthrene-Contaminated Soil Combined with Sphingomonas sp. GY2B and Biosurfactant.

    PubMed

    Lin, Weijia; Guo, Chuling; Zhang, Hui; Liang, Xujun; Wei, Yanfu; Lu, Guining; Dang, Zhi

    2016-04-01

    Electrokinetic-microbial remediation (EMR) has emerged as a promising option for the removal of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils. The aim of this study was to enhance degradation of phenanthrene (Phe)-contaminated soils using EMR combined with biosurfactants. The electrokinetic (EK) remediation, combined with Phe-degrading Sphingomonas sp. GY2B, and biosurfactant obtained by fermentation of Pseudomonas sp. MZ01, degraded Phe in the soil with an efficiency of up to 65.1 % at the anode, 49.9 % at the cathode after 5 days of the treatment. The presence of biosurfactants, electricity, and a neutral electrolyte stimulated the growth of the degrading bacteria as shown by a rapid increase in microbial biomass with time. The electrical conductivity and pH changed little during the course of the treatment, which benefitted the growth of microorganisms and the remediation of Phe-contaminated soil. The EMR system with the addition of biosurfactant had the highest Phe removal, demonstrating the biosurfactant may enhance the bioavailability of Phe and the interaction with the microorganism. This study suggests that the EMR combined with biosurfactants can be used to enhance in situ bioremediation of PAH-contaminated soils. PMID:26683200

  20. Land use history, floodplain development, and soil erosion in the vicinity of a millstone production center since the Iron Age in the Segbachtal near Mayen (eastern Eifel, Germany)

    NASA Astrophysics Data System (ADS)

    Dotterweich, Markus; Wenzel, Stefan; Schreg, Rainer; Fülling, Alexander; Engel, Max

    2015-04-01

    In Roman times, the stone and pottery production near Mayen in western Germany reached a very high intensity which would have satisfied the needs of a much wider area. The rate and volume of production was unprecedented and never reached the same level thereafter. The Segbach valley study site with an area of only a few square kilometres offers a very special geoarchaeological archive. The Roman land use structures were completely preserved under a 2 meter thick layer of sediment and are now partially exposed in a gully due to erosion. Pedological, sedimentological and geophysical studies at the colluvium and floodplain sediments as well as relict field structures showed that in the last 2500 years there has been a considerable human impact on both water and sediment budgets. This also had various implications on the further development of water courses, soils and relief. Evidence for the development of flood plain sediments can be traced as far back as the late La Tène period, the Roman Iron Age, and since the Middle Ages. On one particular south-facing slope we found evidence of recultivation measures on a former quarry tailing heap dating from the Middle Ages. This and other human construction activities and land uses lead to a significant change in erosion and sedimentation patterns. It is surprising that sedimentation in flood plains was largely absent during the Roman Iron Age despite intensive land use. Evidence shows that flash flood events with intensive accumulation of soil matter in flood plains only occurred during the High Middle Ages. Sediments from the late Middle ages and the Modern Times are largely missing. The research undertaken in Segbach valley not only offers new insights into specific local historical land uses and land use changes but also fundamental knowledge about the principles and impacts of long-term human-environment interactions.

  1. Cyprodinil retention on mixtures of soil and solid wastes from wineries. Effects of waste dose and ageing.

    PubMed

    Rodríguez-Salgado, Isabel; Paradelo-Pérez, Marcos; Pérez-Rodríguez, Paula; Cutillas-Barreiro, Laura; Fernández-Calviño, David; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2014-01-01

    In spite of its wide-world economic relevance, wine production generates a huge amount of waste that threatens the environment. A batch experiment was designed to assess the effect of the amendment of an agricultural soil with two winery wastes (perlite and bentonite wastes) in the immobilization of cyprodinil. Waste addition (0, 10, 20, 40, and 80 Mg ha(-1)) and different times of incubation of soil-waste mixtures (1, 30, and 120 days) were tested. The addition of wastes improved the soil's ability to immobilize cyprodinil, which was significantly correlated to total C content in soil-waste mixtures. Longer incubation times decreased the cyprodinil sorption possibly due to the mineralization of organic matter but also as a consequence of the high pH values reached after bentonite waste addition (up to 10.0). Cyprodinil desorption increased as the amount of waste added to soil, and the incubation time increased. The use of these winery wastes contributes to a more sustainable agriculture preventing fungicide mobilization to groundwater.

  2. Polycyclic aromatic hydrocarbons (PAHs) concentration levels, pattern, source identification and soil toxicity assessment in urban traffic soil of Dhanbad, India.

    PubMed

    Suman, Swapnil; Sinha, Alok; Tarafdar, Abhrajyoti

    2016-03-01

    Present study was carried out to assess and understand potential health risk and to examine the impact of vehicular traffic on the contamination status of urban traffic soils in Dhanbad City with respect to polycyclic aromatic hydrocarbons (PAHs). Eight urban traffic sites and two control/rural site surface soils were analyzed and the contents of 13 priority PAHs was determined. Total PAH concentration at traffic sites ranged from 1.019 μg g(-1) to 10.856 μg g(-1) with an average value of 3.488 μg g(-1). At control/rural site, average concentration of total PAHs was found to be 0.640 μg g(-1). PAH pattern was dominated by four- and five-ring PAHs (contributing >50% to the total PAHs) at all the eight traffic sites. On the other hand, rural soil showed a predominance of low molecular weight three-ring PAHs (contributing >30% to the total PAHs). Indeno[123-cd]pyrene/benz[ghi]perylene (IP/BgP) ratio indicated that PAH load at the traffic sites is predominated by the gasoline-driven vehicles. The ratio of Ant/(Ant+Phe) varied from 0.03 to 0.44, averaging 0.10; Fla/(Fla+Pyr) from 0.39 to 0.954, averaging 0.52; BaA/(BaA+Chry) from 0.156 to 0.60, averaging 0.44; and IP/(IP+BgP) from 0.176 to 0.811, averaging 0.286. The results indicated that vehicular emission was the major source for PAHs contamination with moderate effect of coal combustion and biomass combustion. Carcinogenic potency of PAH load in traffic soil was nearly 6.15 times higher as compared to the control/rural soil.

  3. [Effects of fungi on co-metabolic degradation of benzo [a] pyrene in droughty red soil].

    PubMed

    Liu, Shi-liang; Luo, Yong-ming; Wu, Long-hua; Cao, Zhi-hong

    2010-08-01

    Simulated bioslurry remediation of PAHs contaminated soil was carried out. Penicillium, Aspergillus niger and white-rot fungus etc. three strains of fungi isolated from petroleum-contaminated soils were inoculated into droughty red soils differently in application rates of phenanthrene and phthalic acid, to investigate their effects of co-metabolic degradation of B[a]P. Results show that in natural soils, some native microorganisms were able to degrade B[a] P and with addition of low molecular weight PAHs-phenanthrene increased degradation rate of B[a] P in the soil. The effect was greater when the application rate of phenanthrene was 100 mg x kg(-1) than 200 mg x kg(-1). But the addition of phthalic acid did not show much effect. In sterilized soils, degradation of B[a]P in soils was hardly observed, and application of co-metabolism has no significant effect. However, inoculation of Penicillium stimulated degradation of B[a]P in all three treatments, i.e., phenanthrene at 100 mg x kg(-1), phenanthrene at 200 mg x kg(-1) and phthalic acid, but the effect of phenanthrene treatment was better than that of phthalic acid treatment. Inoculation of Aspergillus niger also showed similar effect, however, was inhibited by the presence of phenanthrene and phthalic acid in the soil. The degradation ability of white-rot fungus to B[a]P was very poor, but both kinds of phenanthrene concentration and phthalic acid treatments all could promote white-rot fungus to degrade B[a]P in soils, and the effect of phenanthrene was better than that of phthalic acid.

  4. Human brains found in a fire-affected 4000-years old Bronze Age tumulus layer rich in soil alkalines and boron in Kutahya, Western Anatolia.

    PubMed

    Altinoz, M A; Ince, B; Sav, A; Dincer, A; Cengiz, S; Mercan, S; Yazici, Z; Bilgen, M N

    2014-02-01

    Undecomposed human bodies and organs always attracted interest in terms of understanding biological tissue stability and immortality. Amongst these, cases of natural mummification found in glaciers, bog sediments and deserts caused even more attention. In 2010, an archeological excavation of a Bronze Age layer in a tumulus near the Western Anatolia city Kütahya revealed fire affected regions with burnt human skeletons and charred wooden objects. Inside of the cracked skulls, undecomposed brains were discernible. To analyze the burial taphonomy of the rare phenomenon of brain preservation, we analyzed brains, bone, teeth and surrounding soils elements using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Adipocere formation or saponification of postmortem tissue fat requires high levels of alkalinity and especially potassium. Indeed, ICP-MS analysis of the brain, teeth and bone and also of the surrounding soil revealed high levels of potassium, magnesium, aluminum and boron, which are compatible with the famous role of Kütahya in tile production with its soil containing high level of alkalines and tile-glazing boron. Fatty acid chromatography revealed simultaneous saturation of fats and protection of fragile unsaturated fatty acids consistent with soil-presence of both pro-oxidant and anti-oxidant trace metals. Computerized tomography revealed protection of diencephalic, metencephalic and occipital tissue in one of the best-preserved specimens. Boron was previously found as an intentional preservative of Tutankhamen and Deir el Bahari mummies. Here, in natural soil with its insect-repellant, anti-bacterial and fire-resistance qualities it may be a factor to preserve heat-affected brains as almost bioporcellain specimens. PMID:24060546

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

    PubMed Central

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

    2014-01-01

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

  6. Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds.

    PubMed

    Lambert, Timothy W; Lane, Stephanie

    2004-01-01

    This study evaluated lead, arsenic, and polycyclic aromatic hydrocarbon (PAH) contamination in the residential communities adjacent to the Sydney, Nova Scotia, tar ponds, the area considered Canada's worst contaminated site. The tar pond remediation policy has been limited to the site and some residential properties. We compared background concentrations in 91 soil samples taken 5-20 km from the coke oven site with those in soil samples from the three communities surrounding the tar ponds: Whitney Pier, Ashby, and North End. These surrounding communities were statistically different from background regarding arsenic, lead, and PAHs. Twenty percent of the background soil samples and 95% of the tar pond soil samples were above the Canadian health-risk-based soil guidelines for arsenic (12 ppm), and 5% of the background samples and 80% of the tar pond soil samples were above the Canadian guidelines for lead (140 ppm). Regarding dust lead and arsenic loading, the results provide no evidence that Whitney Pier is significantly different than Ashby and North End. Children in these communities are predicted to have a 1-15% chance of blood lead > 10 microg/dL. The results suggest that lead and arsenic found in the homes originate outside. The lead content of paint in the homes was not evaluated, but consideration of painted wood at the doorway did not confound the results of the study. The results indicate that the residential environment has been adversely affected by PAHs, lead, and arsenic and should be considered for remediation.

  7. Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds.

    PubMed Central

    Lambert, Timothy W; Lane, Stephanie

    2004-01-01

    This study evaluated lead, arsenic, and polycyclic aromatic hydrocarbon (PAH) contamination in the residential communities adjacent to the Sydney, Nova Scotia, tar ponds, the area considered Canada's worst contaminated site. The tar pond remediation policy has been limited to the site and some residential properties. We compared background concentrations in 91 soil samples taken 5-20 km from the coke oven site with those in soil samples from the three communities surrounding the tar ponds: Whitney Pier, Ashby, and North End. These surrounding communities were statistically different from background regarding arsenic, lead, and PAHs. Twenty percent of the background soil samples and 95% of the tar pond soil samples were above the Canadian health-risk-based soil guidelines for arsenic (12 ppm), and 5% of the background samples and 80% of the tar pond soil samples were above the Canadian guidelines for lead (140 ppm). Regarding dust lead and arsenic loading, the results provide no evidence that Whitney Pier is significantly different than Ashby and North End. Children in these communities are predicted to have a 1-15% chance of blood lead > 10 microg/dL. The results suggest that lead and arsenic found in the homes originate outside. The lead content of paint in the homes was not evaluated, but consideration of painted wood at the doorway did not confound the results of the study. The results indicate that the residential environment has been adversely affected by PAHs, lead, and arsenic and should be considered for remediation. PMID:14698928

  8. Soil-borne polycyclic aromatic hydrocarbons in El Paso, Texas: Analysis of a potential problem in the United States/Mexico border region

    PubMed Central

    De La Torre-Roche, Roberto J.; Lee, Wen-Yee; Campos-Díaz, Sandra I.

    2009-01-01

    Ultrasonic extraction followed by Stir Bar Sorptive Extraction (SBSE) and thermal desorption inline coupled with Gas Chromatography and Mass Spectrometry (TD/GC/MS)was used to perform a comprehensive determination of soil-borne polycyclic aromatic hydrocarbons (PAHs) in El Paso, Texas. The method provided good sensitivity and faster processing time for the analysis. The total PAHs in El Paso soil ranged from 0.1 to 2225.5 µg kg−1. Although the majority of PAH concentrations did not exceed the soil screening levels regulated by the United States Environmental Protection Agency, the existence of PAHs in this ecosystem is ubiquitous. Naphthalene were found in 100% of the soil samples; while the heavy PAHs (five- and six-ring) were not often detected and mostly remained in closer proximity to industrial areas and major traffic points. The results ruled out the possibility of petroleum refining as the significant source of local soil-borne PAH contamination, but they suggested that the PAHs found in El Paso soil were closely linked to human activities and possible other industrial processes. PMID:18768257

  9. Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

    SciTech Connect

    Hoylman, A.M.

    1993-01-01

    Plant uptake and translocation of polycyclic aromatic hydrocarbons (PAHs) from soil was investigated to explore plant-microbial interactions in response to a chemical stress in the root zone. Plant uptake of individual PAHs was examined under laboratory conditions which maximized root exposure. White sweetclover, Melilotus alba, was grown in soils dosed with [sup 14]C-naphthalene, -phenanthrene, -pyrene, and -fluoranthene. The highest [sup 14]C concentrations were associated with roots, with decreasing concentrations observed in stems and leaves; however, the greatest percentage of recoverable [sup 14]C remained in the soil ([ge]86%) for all four PAHs. No evidence of bioaccumulation of the individual PAHs was found in M. alba over a 5-day exposure period. Root uptake and translocation of PAHs from soil to aboveground plant tissues proved to be a limited mechanism for PAH transport into terrestrial food chains. However, root surface sorption of PAHs may be important for plants in soils containing elevated concentrations of PAHs. Consequently, the root-soil interface may be important for plant-microbial interactions in response to a chemical stress. [sup 14]CO[sub 2] pulse-labeling studies provide evidence of a shift in [sup 14]C-allocation from aboveground tissue to the root zone when plants were exposed simultaneously to phenanthrene in soil. In addition, soil respiration and heterotrophic plate counts of rhizosphere microorganisms increased in plants exposed to phenanthrene as compared to controls. This study demonstrates the importance of the root-soil interface for plants growing in PAH contaminated soil and provides supportive evidence for a plant-microbial defense response to chemical toxicants in the root zone. Lipophilic toxicants in soils may reach high concentrations in the root zone, but rhizosphere microbial communities under the influence of the plant may reduce the amount of the compound that is actually taken up by the root.

  10. Successful Control of Soil-Transmitted Helminthiasis in School Age Children in Burkina Faso and an Example of Community-Based Assessment via Lymphatic Filariasis Transmission Assessment Survey

    PubMed Central

    Drabo, François; Ouedraogo, Hamado; Bougma, Roland; Bougouma, Clarisse; Bamba, Issouf; Zongo, Dramane; Bagayan, Mohamed; Barrett, Laura; Yago-Wienne, Fanny; Palmer, Stephanie; Chu, Brian; Toubali, Emily; Zhang, Yaobi

    2016-01-01

    Background Burkina Faso is endemic with soil-transmitted helminth infections. Over a decade of preventive chemotherapy has been implemented through annual lymphatic filariasis (LF) mass drug administration (MDA) for population aged five years and over, biennial treatment of school age children with albendazole together with schistosomiasis MDA and biannual treatment of pre-school age children through Child Health Days. Assessments were conducted to evaluate the current situation and to determine the treatment strategy for the future. Methodology/Principal Findings A cross-sectional assessment was conducted in 22 sentinel sites across the country in 2013. In total, 3,514 school age children (1,748 boys and 1,766 girls) were examined by the Kato-Katz method. Overall, soil-transmitted helminth prevalence was 1.3% (95% CI: 1.0–1.8%) in children examined. Hookworm was the main species detected, with prevalence of 1.2% (95% CI: 0.9–1.6%) and mean egg counts of 2.1 epg (95% CI: 0–4.2 epg). Among regions, the Centre Ouest region had the highest hookworm prevalence of 3.4% (95% CI: 1.9–6.1%) and mean egg counts of 14.9 epg (95% CI: 3.3–26.6 epg). A separate assessment was conducted in the Centre Nord region in 2014 using community-based cluster survey design during an LF transmission assessment survey (TAS). In this assessment, 351 children aged 6–7 years and 345 children aged 10–14 years were examined, with two cases (0.6% (95% CI: 0.2–2.1%)) and seven cases (2.0% (95% CI: 1.0–4.1%)) of hookworm infection was identified respectively. The results using both age groups categorized the region to be 2% to <10% in STH prevalence according to the pre-defined cut-off values. Conclusions/Significance Through large-scale preventive chemotherapy, Burkina Faso has effectively controlled STH in school age children in the country. Research should be conducted on future strategies to consolidate the gain and to interrupt STH transmission in Burkina Faso. It is also

  11. Combined effects of DOM and biosurfactant enhanced biodegradation of polycylic armotic hydrocarbons (PAHs) in soil-water systems.

    PubMed

    Yu, Hui; Huang, Guo-He; Xiao, Huining; Wang, Lei; Chen, Wei

    2014-09-01

    This study systematically investigated the interactive effects of dissolved organic matter (DOM) and biosurfactant (rhamnolipid) on the biodegradation of phenanthrene (PHE) and pyrene (PYR) in soil-water systems. The degradations of two polycyclic aromatic hydrocarbons (PAHs) were fitted well with first order kinetic model and the degradation rates were in proportion to the concentration of biosurfactant. In addition, the degradation enhancement of PHE was higher than that of PYR. The addition of soil DOM itself at an environmental level would inhibit the biodegradation of PAHs. However, in the system with co-existence of DOM and biosurfactant, the degradation of PAHs was higher than that in only biosurfactant addition system, which may be attributed to the formation of DOM-biosurfactant complex micelles. Furthermore, under the combined conditions, the degradation of PAH increased with the biosurfactant concentration, and the soil DOM added system showed slightly higher degradation than the compost DOM added system, indicating that the chemical structure and composition of DOM would also affect the bioavailability of PAHs. The study result may broaden knowledge of biosurfactant enhanced bioremediation of PAHs contaminated soil and groundwater.

  12. PAH-sequestration capacity of granular and powder activated carbon amendments in soil, and their effects on earthworms and plants.

    PubMed

    Jakob, Lena; Hartnik, Thomas; Henriksen, Thomas; Elmquist, Marie; Brändli, Rahel C; Hale, Sarah E; Cornelissen, Gerard

    2012-07-01

    A field lysimeter study was carried out to investigate whether the amendment of 2% powder and granular activated carbon (PAC and GAC) to a soil with moderate PAH contamination had an impact on the PAH bioaccumulation of earthworms and plants, since AC is known to be a strong sorbent for organic pollutants. Furthermore, secondary effects of AC on plants and earthworms were studied through growth and nutrient uptake, and survival and weight gain. Additionally, the effect of AC amendments on soil characteristics like pH, water holding capacity, and the water retention curve of the soil were investigated. Results show that the amendment of 2% PAC had a negative effect on plant growth while the GAC increased the growth rate of plants. PAC was toxic to earthworms, demonstrated by a significant weight loss, while the results for GAC were less clear due to ambiguous results of a field and a parallel laboratory study. Both kinds of AC significantly reduced biota to soil accumulation factors (BSAFs) of PAHs in earthworms and plants. The GAC reduced the BSAFs of earthworms by an average of 47 ± 44% and the PAC amendment reduced them by 72 ± 19%. For the investigated plants the BSAFs were reduced by 46 ± 36% and 53 ± 22% by the GAC and PAC, respectively.

  13. Effect of pre-heating on the chemical oxidation efficiency: implications for the PAH availability measurement in contaminated soils.

    PubMed

    Biache, Coralie; Lorgeoux, Catherine; Andriatsihoarana, Sitraka; Colombano, Stéfan; Faure, Pierre

    2015-04-01

    Three chemical oxidation treatments (KMnO4, H2O2 and Fenton-like) were applied on three PAH-contaminated soils presenting different properties to determine the potential use of these treatments to evaluate the available PAH fraction. In order to increase the available fraction, a pre-heating (100 °C under N2 for one week) was also applied on the samples prior oxidant addition. PAH and extractable organic matter contents were determined before and after treatment applications. KMnO4 was efficient to degrade PAHs in all the soil samples and the pre-heating slightly improved its efficiency. H2O2 and Fenton-like treatments presented low efficiency to degrade PAH in the soil presenting poor PAH availability, however, the PAH degradation rates were improved with the pre-heating. Consequently H2O2-based treatments (including Fenton-like) are highly sensitive to contaminant availability and seem to be valid methods to estimate the available PAH fraction in contaminated soils.

  14. Contamination, source, and input route of polycyclic aromatic hydrocarbons in historic wastewater-irrigated agricultural soils.

    PubMed

    Wang, Ning; Li, Hong-Bo; Long, Jin-Lin; Cai, Chao; Dai, Jiu-Lan; Zhang, Juan; Wang, Ren-Qing

    2012-12-01

    Contamination by polycyclic aromatic hydrocarbons (PAHs) of historic wastewater-irrigated agricultural topsoil (0-5 cm) and the contribution of groundwater irrigation and atmospheric deposition to soil PAHs were studied in a typical agricultural region, i.e. Hunpu region, Liaoning, China. Concentrations of total PAHs ranged from 0.43 to 2.64 mg kg⁻¹ in topsoil, being lower than those found in other wastewater-irrigated areas. The levels of PAHs in soil declined as the distance from a water source increased. Concentrations of individual PAHs were generally higher in upland than in paddy topsoils. The calculated nemerow composite index showed that agricultural soil in the region was "polluted" by PAHs. A human health risk assessment based on the total toxic equivalent concentration showed that the presence of elevated concentrations of PAHs in the soil might pose a great threat to the health of local residents. Ratios of pairs of PAHs and principal component analysis (PCA) showed that pyrogenesis, such as coal combustion, was the main source of PAHs, while petroleum, to some extent, also had a strong influence on PAHs contamination in upland soil. The distribution patterns of individual PAHs and composition of PAHs differed between irrigation groundwater and topsoil, but were similar between atmospheric deposition and topsoil. There were significant linear correlations (r = 0.90; p < 0.01) between atmospheric deposition rates and average concentrations of the 16 individual PAHs in soils, while no significant relationships were observed between irrigation groundwater and topsoil in levels of PAHs. These suggested that PAHs in agricultural soils were mainly introduced from atmospheric deposition, rather than from groundwater irrigation after the phasing out of wastewater irrigation in the region since 2002. This study provides a reference to ensure agricultural product safety, pollution control, and proper soil management.

  15. Molecular and chemical features of the excreted extracellular polysaccharides in Induced Biological Soil Crusts of different ages

    NASA Astrophysics Data System (ADS)

    Rossi, Federico; Lanzhou, Chen; Liu, Yongding; Adessi, Alessandra; De Philippis, Roberto

    2014-05-01

    Biological Soil Crusts (BSCs) are complex microbial associations widely distributed in arid and semiarid environments. These microbial associations have recently been acknowledged as important in restoration ecology (Bowker 2007). The primary colonization of cyanobacteria and other crust organisms after events such as fire or cessation of plowing is considered critical for later vascular plant establishment, due to the control of seed germination and due to the complex pathways that BSCs are capable to establish between plants and crust organisms and exudates (Rossi et al. 2013). In a ten year study carried out in the hyper-arid region of Inner Mongolia (China), introduction of man - made BSCs (induced BSCs, IBSCs) proved to be effective in producing a shift of the ecosystem state from high abiotic to low abiotic stress, evidenced by an increase in photothrophic abundance and subshrub cover. The prerequisite for an efficient exploitation of crust organisms as soil colonizers is their capability to secrete large amount of exopolysaccharides (EPS) which are important, among the reasons, as they lead to soil and BSC stabilization and represent a noticeable source of C that can be respired by the crustal community. By these means, a deep chemical and physiological knowledge concerning these exudates is required. Notwithstanding the large amount of literature available, recently thoroughly reviewed by Mager and Thomas (2011), the chemical characteristics of EPS from BSCs, and in particular from IBSCs, have not been investigated yet. We analyzed the monosaccharidic composition and the molecular weight distribution of two EPS fractions, the more soluble fraction and the fraction more tightly bound to cells, extracted from IBSCs collected in the Inner Mongolian desert, inoculated in different years (namely 4, 6 and 8 years before the sampling), thus characterized by different developmental stages. We thereafter investigated the degradation processes involving EPS

  16. Ecotoxicological effects of an aged TiO2 nanocomposite measured as apoptosis in the anecic earthworm Lumbricus terrestris after exposure through water, food and soil.

    PubMed

    Lapied, Emmanuel; Nahmani, Johanne Y; Moudilou, Elara; Chaurand, Perrine; Labille, Jérôme; Rose, Jérôme; Exbrayat, Jean-Marie; Oughton, Deborah H; Joner, Erik J

    2011-08-01

    Titanium dioxide nanoparticles seem to have a low toxicity to terrestrial organisms, though few studies are published in this area. TiO(2) used in sunscreens are nanocomposites where TiO(2) has been coated with magnesium, silica or alumina, as well as amphiphilic organics like polydimethyl siloxane (PDMS), and these coatings are modified by ageing. We assessed the ecotoxicity and propensity for bioaccumulation of an aged TiO(2) nanocomposite used in sunscreen cosmetics, and its potential effect on the frequency of apoptosis in different earthworm tissues. The earthworm Lumbricus terrestris was exposed to the TiO(2) nanocomposite for 7 days in water or 2-8 weeks in soil with the nanocomposite mixed either into food or soil at concentrations ranging from 0 to 100 mg kg(-1). Apoptosis was then measured by immunohistochemistry and Ti localized by XRF microscopy. Results showed no mortality, but an enhanced apoptotic frequency which was higher in the cuticule, intestinal epithelium and chloragogenous tissue than in the longitudinal and circular musculature. TiO(2) nanoparticles did not seem to cross the intestinal epithelium/chloragogenous matrix barrier to enter the coelomic liquid, or the cuticule barrier to reach the muscular layers. No bioaccumulation of TiO(2) nanocomposites could thus be observed. PMID:21324526

  17. A Reactive Transport Model for the Distribution and Age of Carbon in Soils and Sediments Through Direct Simulation of the Stable and Radiogenic Isotopologues

    NASA Astrophysics Data System (ADS)

    Druhan, J. L.; Lawrence, C. R.

    2015-12-01

    We present a reactive transport (RT) approach to link hydrologic transport, geochemical transformations and microbial activity influencing the magnitude and residence time of different carbon pools under variably saturated conditions. This model explicitly simulates the simultaneous transport, transformation, fractionation and decay of the three isotopes of carbon (12C, 13C and 14C) through a mechanistic framework. This is demonstrated with a modification of the CrunchTope multi-component RT software to extend the isotope-specific versions of both microbially-mediated and transition state theory (TST) rate laws to accommodate a three-isotope system. In addition both aqueous and solid phase decay of 14C are tracked, yielding in an implicit means of accounting for the 13C/12C correction in normalized radiocarbon ages. The capacity of this approach to quantify the storage and flux of carbon through subsurface compartments is demonstrated using two examples distinguished by timescale. The first considers a simplified flow path in which an influent containing labile organic carbon is distributed by biogenic reduction and mineralization into a suite of reaction products. The residence time of these pools and their characteristic stable isotope ratios are tracked through a variety of transient processes occurring at short timescales (e.g. months). These include a change in fluid flow rate, a limitation of ammonium supporting anabolic growth and an influx of oxygenated fluid. The second example considers the distribution of carbon over the timescale of soil development (e.g., millennia), using a dataset of stable isotope ratios and radiocarbon ages of organic and inorganic carbon present in both dissolved and solid phases from a soil chronosequence near Santa Cruz, CA. The results of these model simulations suggest the promise of this tool for improving our understanding of coupling between hydrologic transport and biogeochemical reactions in soils.

  18. Evaluating the Effects of Bioremediation on Genotoxicity of Polycyclic Aromatic Hydrocarbon-Contaminated Soil Using Genetically Engineered, Higher Eukaryotic Cell Lines

    PubMed Central

    Hu, Jing; Nakamura, Jun; Richardson, Stephen D.; Aitken, Michael D.

    2012-01-01

    Bioremediation is one of the commonly applied remediation strategies at sites contaminated with polycyclic aromatic hydrocarbons (PAHs). However, remediation goals are typically based on removal of the target contaminants rather than on broader measures related to health risks. We investigated changes in the toxicity and genotoxicity of PAH-contaminated soil from a former manufactured-gas plant site before and after two simulated bioremediation processes: a sequencing batch bioreactor system and a continuous-flow column system. Toxicity and genotoxicity of the residues from solvent extracts of the soil were determined by the chicken DT40 B-lymphocyte isogenic cell line and its DNA-repair-deficient mutants. Although both bioremediation processes significantly removed PAHs from the contaminated soil (bioreactor 69% removal; column 84% removal), bioreactor treatment resulted in an increase in toxicity and genotoxicity over the course of a treatment cycle, whereas long-term column treatment resulted in a decrease in toxicity and genotoxicity. However, when screening with a battery of DT40 mutants for genotoxicity profiling, we found that column treatment induced DNA damage types that were not observed in untreated soil. Toxicity and genotoxicity bioassays can supplement chemical analysis-based risk assessment for contaminated soil when evaluating the efficacy of bioremediation. PMID:22443351

  19. Spatial Variability of PAHs and Microbial Community Structure in Surrounding Surficial Soil of Coal-Fired Power Plants in Xuzhou, China

    PubMed Central

    Ma, Jing; Zhang, Wangyuan; Chen, Yi; Zhang, Shaoliang; Feng, Qiyan; Hou, Huping; Chen, Fu

    2016-01-01

    This work investigated the spatial profile and source analysis of polycyclic aromatic hydrocarbons (PAHs) in soil that surrounds coal-fired power plants in Xuzhou, China. High-throughput sequencing was employed to investigate the composition and structure of soil bacterial communities. The total concentration of 15 PAHs in the surface soils ranged from 164.87 to 3494.81 μg/kg dry weight. The spatial profile of PAHs was site-specific with a concentration of 1400.09–3494.81 μg/kg in Yaozhuang. Based on the qualitative and principal component analysis results, coal burning and vehicle emission were found to be the main sources of PAHs in the surface soils. The phylogenetic analysis revealed differences in bacterial community compositions among different sampling sites. Proteobacteria was the most abundant phylum, while Acidobacteria was the second most abundant. The orders of Campylobacterales, Desulfobacterales and Hydrogenophilales had the most significant differences in relative abundance among the sampling sites. The redundancy analysis revealed that the differences in bacterial communities could be explained by the organic matter content. They could also be explicated by the acenaphthene concentration with longer arrows. Furthermore, OTUs of Proteobacteria phylum plotted around particular samples were confirmed to have a different composition of Proteobacteria phylum among the sample sites. Evaluating the relationship between soil PAHs concentration and bacterial community composition may provide useful information for the remediation of PAH contaminated sites. PMID:27598188

  20. Spatial Variability of PAHs and Microbial Community Structure in Surrounding Surficial Soil of Coal-Fired Power Plants in Xuzhou, China.

    PubMed

    Ma, Jing; Zhang, Wangyuan; Chen, Yi; Zhang, Shaoliang; Feng, Qiyan; Hou, Huping; Chen, Fu

    2016-01-01

    This work investigated the spatial profile and source analysis of polycyclic aromatic hydrocarbons (PAHs) in soil that surrounds coal-fired power plants in Xuzhou, China. High-throughput sequencing was employed to investigate the composition and structure of soil bacterial communities. The total concentration of 15 PAHs in the surface soils ranged from 164.87 to 3494.81 μg/kg dry weight. The spatial profile of PAHs was site-specific with a concentration of 1400.09-3494.81 μg/kg in Yaozhuang. Based on the qualitative and principal component analysis results, coal burning and vehicle emission were found to be the main sources of PAHs in the surface soils. The phylogenetic analysis revealed differences in bacterial community compositions among different sampling sites. Proteobacteria was the most abundant phylum, while Acidobacteria was the second most abundant. The orders of Campylobacterales, Desulfobacterales and Hydrogenophilales had the most significant differences in relative abundance among the sampling sites. The redundancy analysis revealed that the differences in bacterial communities could be explained by the organic matter content. They could also be explicated by the acenaphthene concentration with longer arrows. Furthermore, OTUs of Proteobacteria phylum plotted around particular samples were confirmed to have a different composition of Proteobacteria phylum among the sample sites. Evaluating the relationship between soil PAHs concentration and bacterial community composition may provide useful information for the remediation of PAH contaminated sites. PMID:27598188

  1. Evolution of soils and dynamics of the climate of steppes in the southeast of the russian plain during the late eneolithic and bronze ages (fourth to second millennia BC)

    NASA Astrophysics Data System (ADS)

    Demkin, V. A.; Borisov, A. V.; Demkina, T. S.; Khomutova, T. E.; Kashirskaya, N. N.

    2010-12-01

    On the basis of studies of subkurgan pedochronoseries, the main mechanisms of the development of soils of arid and desert steppes in drained landscapes of the southeastern Russian plain in the Late Eneolithic and Bronze ages (6000-3000 years ago) were established. During the fourth to third millennia BC, evolution of soils took place at the level of subtypes with a shift of boundaries of soil subzones toward the north. In each of the studied natural regions (Central Russian Upland, Volga Upland, Ergeni Hills, and Caspian Depression), an increase in the aridization of the climate in the second half of the third millennium BC can be distinctly traced, owing to which a convergence of the topsoil with the transformation of dark-chestnut, chestnut, and light-chestnut soils in chestnut-like semiarid soils, which dominated the region 4200-3900 years ago, occurred. In the first half of the second millennium BC, another change in the conditions of soil formation occurred that was caused by an increase in the degree of atmospheric humidity. It induced the divergence of the topsoil with a secondary formation of areas of zonal chestnut soils and solonetzes in place of chestnut-like soils by the middle of the second millennium BC. The obtained data gives reason to suggest that the age of modern chestnut solonetz complexes of the region does not exceed 3500 years.

  2. Complete genome sequence of the phenanthrene-degrading soil bacterium Delftia acidovorans Cs1-4

    SciTech Connect

    Shetty, Ameesha R.; de Gannes, Vidya; Obi, Chioma C.; Lucas, Susan; Lapidus, Alla; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Samuel; Peters, Linda; Mikhailova, Natalia; Teshima, Hazuki; Han, Cliff; Tapia, Roxanne; Land, Miriam; Hauser, Loren J.; Kyrpides, Nikos; Ivanova, Natalia; Pagani, Ioanna; Chain, Patrick S. G.; Denef, Vincent J.; Woyke, Tanya; Hickey, William J.

    2015-08-15

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and microbial biodegradation is an important means of remediation of PAH-contaminated soil. Delftia acidovorans Cs1-4 (formerly Delftia sp. Cs1-4) was isolated by using phenanthrene as the sole carbon source from PAH contaminated soil in Wisconsin. Its full genome sequence was determined to gain insights into a mechanisms underlying biodegradation of PAH. Three genomic libraries were constructed and sequenced: an Illumina GAii shotgun library (916,416,493 reads), a 454 Titanium standard library (770,171 reads) and one paired-end 454 library (average insert size of 8 kb, 508,092 reads). The initial assembly contained 40 contigs in two scaffolds. The 454 Titanium standard data and the 454 paired end data were assembled together and the consensus sequences were computationally shredded into 2 kb overlapping shreds. Illumina sequencing data was assembled, and the consensus sequence was computationally shredded into 1.5 kb overlapping shreds. Gaps between contigs were closed by editing in Consed, by PCR and by Bubble PCR primer walks. A total of 182 additional reactions were needed to close gaps and to raise the quality of the finished sequence. The final assembly is based on 253.3 Mb of 454 draft data (averaging 38.4 X coverage) and 590.2 Mb of Illumina draft data (averaging 89.4 X coverage). The genome of strain Cs1-4 consists of a single circular chromosome of 6,685,842 bp (66.7 %G+C) containing 6,028 predicted genes; 5,931 of these genes were protein-encoding and 4,425 gene products were assigned to a putative function. Genes encoding phenanthrene degradation were localized to a 232 kb genomic island (termed the phn island), which contained near its 3’ end a bacteriophage P4-like integrase, an enzyme often associated with chromosomal integration of mobile genetic elements. Other biodegradation pathways reconstructed from the genome sequence included: benzoate (by the acetyl-CoA pathway

  3. Complete genome sequence of the phenanthrene-degrading soil bacterium Delftia acidovorans Cs1-4

    DOE PAGES

    Shetty, Ameesha R.; de Gannes, Vidya; Obi, Chioma C.; Lucas, Susan; Lapidus, Alla; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Samuel; Peters, Linda; Mikhailova, Natalia; et al

    2015-08-15

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and microbial biodegradation is an important means of remediation of PAH-contaminated soil. Delftia acidovorans Cs1-4 (formerly Delftia sp. Cs1-4) was isolated by using phenanthrene as the sole carbon source from PAH contaminated soil in Wisconsin. Its full genome sequence was determined to gain insights into a mechanisms underlying biodegradation of PAH. Three genomic libraries were constructed and sequenced: an Illumina GAii shotgun library (916,416,493 reads), a 454 Titanium standard library (770,171 reads) and one paired-end 454 library (average insert size of 8 kb, 508,092 reads). The initial assembly contained 40 contigs inmore » two scaffolds. The 454 Titanium standard data and the 454 paired end data were assembled together and the consensus sequences were computationally shredded into 2 kb overlapping shreds. Illumina sequencing data was assembled, and the consensus sequence was computationally shredded into 1.5 kb overlapping shreds. Gaps between contigs were closed by editing in Consed, by PCR and by Bubble PCR primer walks. A total of 182 additional reactions were needed to close gaps and to raise the quality of the finished sequence. The final assembly is based on 253.3 Mb of 454 draft data (averaging 38.4 X coverage) and 590.2 Mb of Illumina draft data (averaging 89.4 X coverage). The genome of strain Cs1-4 consists of a single circular chromosome of 6,685,842 bp (66.7 %G+C) containing 6,028 predicted genes; 5,931 of these genes were protein-encoding and 4,425 gene products were assigned to a putative function. Genes encoding phenanthrene degradation were localized to a 232 kb genomic island (termed the phn island), which contained near its 3’ end a bacteriophage P4-like integrase, an enzyme often associated with chromosomal integration of mobile genetic elements. Other biodegradation pathways reconstructed from the genome sequence included: benzoate (by the acetyl

  4. Complete genome sequence of the phenanthrene-degrading soil bacterium Delftia acidovorans Cs1-4.

    PubMed

    Shetty, Ameesha R; de Gannes, Vidya; Obi, Chioma C; Lucas, Susan; Lapidus, Alla; Cheng, Jan-Fang; Goodwin, Lynne A; Pitluck, Samuel; Peters, Linda; Mikhailova, Natalia; Teshima, Hazuki; Han, Cliff; Tapia, Roxanne; Land, Miriam; Hauser, Loren J; Kyrpides, Nikos; Ivanova, Natalia; Pagani, Ioanna; Chain, Patrick S G; Denef, Vincent J; Woyke, Tanya; Hickey, William J

    2015-01-01

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and microbial biodegradation is an important means of remediation of PAH-contaminated soil. Delftia acidovorans Cs1-4 (formerly Delftia sp. Cs1-4) was isolated by using phenanthrene as the sole carbon source from PAH contaminated soil in Wisconsin. Its full genome sequence was determined to gain insights into a mechanisms underlying biodegradation of PAH. Three genomic libraries were constructed and sequenced: an Illumina GAii shotgun library (916,416,493 reads), a 454 Titanium standard library (770,171 reads) and one paired-end 454 library (average insert size of 8 kb, 508,092 reads). The initial assembly contained 40 contigs in two scaffolds. The 454 Titanium standard data and the 454 paired end data were assembled together and the consensus sequences were computationally shredded into 2 kb overlapping shreds. Illumina sequencing data was assembled, and the consensus sequence was computationally shredded into 1.5 kb overlapping shreds. Gaps between contigs were closed by editing in Consed, by PCR and by Bubble PCR primer walks. A total of 182 additional reactions were needed to close gaps and to raise the quality of the finished sequence. The final assembly is based on 253.3 Mb of 454 draft data (averaging 38.4 X coverage) and 590.2 Mb of Illumina draft data (averaging 89.4 X coverage). The genome of strain Cs1-4 consists of a single circular chromosome of 6,685,842 bp (66.7 %G+C) containing 6,028 predicted genes; 5,931 of these genes were protein-encoding and 4,425 gene products were assigned to a putative function. Genes encoding phenanthrene degradation were localized to a 232 kb genomic island (termed the phn island), which contained near its 3' end a bacteriophage P4-like integrase, an enzyme often associated with chromosomal integration of mobile genetic elements. Other biodegradation pathways reconstructed from the genome sequence included: benzoate (by the acetyl-CoA pathway

  5. Pre-aged soil organic carbon as a major component of the Yellow River suspended load: Regional significance and global relevance

    NASA Astrophysics Data System (ADS)

    Tao, Shuqin; Eglinton, Timothy I.; Montluçon, Daniel B.; McIntyre, Cameron; Zhao, Meixun

    2015-03-01

    Large rivers connect the continents and the oceans, and corresponding material fluxes have a global impact on marine biogeochemistry. The Yellow River transports vast quantities of suspended sediments to the ocean, yet the nature of the particulate organic carbon (POC) carried by this system is not well known. The focus of this study is to characterize the sources, composition and age of suspended POC collected near the terminus of this river system, focusing on the abundance and carbon isotopic composition (13C and 14C) of specific biomarkers. The concentrations of vascular plant wax lipids (long-chain (≥C24) n-alkanes, n-fatty acids) and POC co-varied with total suspended solid (TSS) concentrations, indicating that both were controlled by the overall terrestrial sediment flux. POC exhibited relatively uniform δ13C values (-23.8 to -24.2‰), and old radiocarbon ages (4000-4640 yr). However, different biomarkers exhibited a wide range of 14C ages. Short-chain (C16, C18) fatty acid 14C ages were variable but generally the youngest organic components (from 502 yr to modern), suggesting they reflect recently biosynthesized material. Lignin phenol 14C ages were also variable and relatively young (1070 yr to modern), suggesting rapid export of carbon from terrestrial primary production. In contrast, long-chain plant wax lipids display relatively uniform and significantly older 14C ages (1500-1800 yr), likely reflecting inputs of pre-aged, mineral-associated soil OC from the Yellow River drainage basin. Even-carbon-numbered n-alkanes yielded the oldest 14C ages (up to 26 000 yr), revealing the presence of fossil (petrogenic) OC. Two isotopic mass balance approaches were explored to quantitively apportion different OC sources in Yellow River suspended sediments. Results indicate that the dominant component of POC (53-57%) is substantially pre-aged (1510-1770 yr), and likely sourced from the extensive loess-paleosol deposits outcropping within the drainage basin. Of

  6. Activated carbon adsorption of PAHs from vegetable oil used in soil remediation.

    PubMed

    Gong, Zongqiang; Alef, Kassem; Wilke, Berndt-Michael; Li, Peijun

    2007-05-01

    Vegetable oil has been proven to be advantageous as a non-toxic, cost-effective and biodegradable solvent to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated soils for remediation purposes. The resulting vegetable oil contained PAHs and therefore required a method for subsequent removal of extracted PAHs and reuse of the oil in remediation processes. In this paper, activated carbon adsorption of PAHs from vegetable oil used in soil remediation was assessed to ascertain PAH contaminated oil regeneration. Vegetable oils, originating from lab scale remediation, with different PAH concentrations were examined to study the adsorption of PAHs on activated carbon. Batch adsorption tests were performed by shaking oil-activated carbon mixtures in flasks. Equilibrium data were fitted with the Langmuir and Freundlich isothermal models. Studies were also carried out using columns packed with activated carbon. In addition, the effects of initial PAH concentration and activated carbon dosage on sorption capacities were investigated. Results clearly revealed the effectiveness of using activated carbon as an adsorbent to remove PAHs from the vegetable oil. Adsorption equilibrium of PAHs on activated carbon from the vegetable oil was successfully evaluated by the Langmuir and Freundlich isotherms. The initial PAH concentrations and carbon dosage affected adsorption significantly. The results indicate that the reuse of vegetable oil was feasible.

  7. Fate and bioavailability of ¹⁴C-pyrene and ¹⁴C-lindane in sterile natural and artificial soils and the influence of aging.

    PubMed

    Smídová, Klára; Hofman, Jakub; Ite, Aniefiok E; Semple, Kirk T

    2012-12-01

    Soil organic matter is used to extrapolate the toxicity and bioavailability of organic pollutants between different soils. However, it has been shown that other factors such as microbial activity are crucial. The aim of this study was to investigate if sterilization can reduce differences in the fate and bioavailability of organic pollutants between different soils. Three natural soils with increasing total organic carbon (TOC) content were collected and three artificial soils were prepared to obtain similar TOCs. Soils were sterilized and spiked with (14)C-pyrene and (14)C-lindane. Total (14)C radioactivity, HPCD extractability, and bioaccumulation in Eisenia fetida were measured over 56 days. When compared to non-sterile soils, differences between the natural and artificial soils and the influence of soil-contaminant contact time were generally reduced in the sterile soils (especially with middle TOC). The results indicate the possibility of using sterile soils as "the worst case scenario" in soil ecotoxicity studies.

  8. A quantitative PCR approach for quantification of functional genes involved in the degradation of polycyclic aromatic hydrocarbons in contaminated soils

    PubMed Central

    Shahsavari, Esmaeil; Aburto-Medina, Arturo; Taha, Mohamed; Ball, Andrew S.

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are major pollutants globally and due to their carcinogenic and mutagenic properties their clean-up is paramount. Bioremediation or using PAH degrading microorganisms (mainly bacteria) to degrade the pollutants represents cheap, effective methods. These PAH degraders harbor functional genes which help microorganisms use PAHs as source of food and energy. Most probable number (MPN) and plate counting methods are widely used for counting PAHs degraders; however, as culture based methods only count a small fraction (<1%) of microorganisms capable of carrying out PAH degradation, the use of culture-independent methodologies is desirable.•This protocol presents a robust, rapid and sensitive qPCR method for the quantification of the functional genes involved in the degradation of PAHs in soil samples.•This protocol enables us to screen a vast number of PAH contaminated soil samples in few hours.•This protocol provides valuable information about the natural attenuation potential of contaminated soil and can be used to monitor the bioremediation process. PMID:27054096

  9. Coupling Sorption to Soil Weathering during Reactive Transport: Impacts of Mineral Transformation and Sorbate Aging on Contaminant Speciation and Mobility

    SciTech Connect

    Carl I. Steefel; Aaron Thompson; Jon Chorover

    2006-06-01

    The Hanford subsurface has become contaminated with highly alkaline, radioactive waste generated as a result of weapons production. The radioactive brine was stored in underground storage tanks, a number of which developed leaks and contaminated the surrounding subsurface. The high pH and ionic strength of these wastes has been predicted to accelerate the degree of soil weathering to produce new mineral phases--cancrinite and sodalite among the most abundant. Previous work has demonstrated that Cs and Sr, which along with I represent the most radioactive components in the waste, are sequestered by these neo-formed solids. The present work is aimed at assessing the stability of these neo-formed solids, with special emphasis on the degree of Cs, Sr and I release under ambient (neutral pH, low ionic strength) conditions expected to return to the Hanford area after the caustic radioactive brine waste is removed.

  10. Soils, vegetation, and climate of the southern Transural region in the Middle Bronze Age (by the example of the Arkaim fortress)

    NASA Astrophysics Data System (ADS)

    Prikhod'ko, V. E.; Ivanov, I. V.; Manakhov, D. V.; Gerasimenko, N. P.; Inubushi, K.; Kawahigashi, M.; Nagano, Kh.; Sugihara, S.

    2013-09-01

    Paleosols of the unique fortress of Arkaim located in the steppe zone of the southern Transural region (Chelyabinsk oblast) were investigated. The dating of the buried soils was performed using the radiocarbon method. The time of building this archeological monument is the Middle Bronze Age (the Sintashta culture; the calibrated dating with 1σ confidence is 3700-4000 years ago). Seven pits of paleosols and ten pits of background ordinary chernozems were studied. The soils are loamy and sandy-loamy. The morphological and chemical properties of the buried and background ordinary chernozems are similar; they differ by the lower content of readily soluble salts in the paleosols as compared to the background ones. The sporepollen spectrum of the Arkaim paleosol is transitional from the steppe to the forest-steppe type. During the existence of this settlement, pine forests with fern ground cover grew, and hygrophytic species (alder and spruce) that nowadays are not recorded in the plant cover occurred. The main feature of the paleosols is the presence of pollen of xerophytic and halophytic herbaceous plants there. The few pollen grains of broad-leaved species testify to a higher heat supply as compared to the current one. Judging by the results of the spore-pollen and microbiomorphic analyses, the climate during the time of building the walls of the settlement was somewhat moister and warmer (or less continental) than the present-day climate. The duration of this period appeared to be short; therefore, soil properties corresponding to the changed environment could not be formed. They reflect the situation of the preceding period with the climatic characteristics close to the present-day ones.

  11. [Enhanced bioremediation of coking plant soils contaminated with polycyclic aromatic hydrocarbons].

    PubMed

    Lu, Xiao-Xia; Li, Xiu-Li; Ma, Jie; Wu, Shu-Ke; Chen, Chao-Qi; Wu, Wei

    2011-03-01

    Soil samples contaminated with polycyclic aromatic hydrocarbons (PAHs) were collected from Beijing Coking Plant. The purposes were to isolate PAHs degrading bacteria from the soils, determine their appropriate living condition, enrich them and apply them in the enhanced bioremediation of the contaminated soils. Using each of the 16 USEPA priority PAHs as the sole carbon source, PAHs degrading bacteria were isolated using the method of plate streaking and identified by genetic analysis. In total seven species of PAHs degrading bacteria were obtained. When mixed, these bacteria could degrade the 16 (2-6 cyclic) PAHs studied at appropriate concentrations. In the liquid medium, when the total concentration of the 16 PAHs (sigma PAH16) was 17 microg/mL, single bacteria could grow well and degrade the PAHs. However, when sigma PAH16 was 166 microg/mL, the growth and activity of either single PAHs degrading bacteria or a mixture of the seven PAHs degrading bacteria were inhibited. Aiming at the contaminated soils from Beijing coking plant, five treatments were performed, i.e., control (C), addition of nutrient (N), addition of nutrient and PAHs degrading bacteria (N + B), addition of nutrient and surfactant (N +S), addition of nutrient and PAHs degrading bacteria and surfactant (N + B + S). After five weeks of experiment, compared to the C treatment, the mean removal rate of the 16 PAHs in the N + B treatment was increased 32%, and the mean removal rate of the 16 PAHs in the N + B + S treatment was increased 46% (the mean removal rate of the 10 4-6 cyclic PAHs was increased 52%). The addition of PAHs degrading bacteria and surfactant could significantly enhance the degradation of PAHs in the soils. This study provides evidence for the enhanced bioremediation of PAHs contaminated soil for Beijing coking plant and other coking plants.

  12. Rapid Re-Infection with Soil-Transmitted Helminths after Triple-Dose Albendazole Treatment of School-Aged Children in Yunnan, People's Republic of China

    PubMed Central

    Yap, Peiling; Du, Zun-Wei; Wu, Fang-Wei; Jiang, Jin-Yong; Chen, Ran; Zhou, Xiao-Nong; Hattendorf, Jan; Utzinger, Jürg; Steinmann, Peter

    2013-01-01

    Post-treatment soil-transmitted helminth re-infection patterns were studied as part of a randomized controlled trial among school-aged children from an ethnic minority group in Yunnan province, People's Republic of China. Children with a soil-transmitted helminth infection (N = 194) were randomly assigned to triple-dose albendazole or placebo and their infection status monitored over a 6-month period using the Kato-Katz and Baermann techniques. Baseline prevalence of Trichuris trichiura, Ascaris lumbricoides, hookworm, and Strongyloides stercoralis were 94.5%, 93.3%, 61.3%, and 3.1%, respectively, with more than half of the participants harboring triple-species infections. For the intervention group (N = 99), the 1-month post-treatment cure rates were 96.7%, 91.5%, and 19.6% for hookworm, A. lumbricoides, and T. trichiura, respectively. Egg reduction rates were above 88% for all three species. Rapid re-infection with A. lumbricoides was observed: the prevalence 4 and 6 months post-treatment was 75.8% and 83.8%, respectively. Re-infection with hookworm and T. trichiura was considerably slower. PMID:23690551

  13. The cuticular hydrocarbons of the giant soil-burrowing cockroach Macropanesthia rhinoceros saussure (Blattodea: Blaberidae: Geoscapheinae): analysis with respect to age, sex and location.

    PubMed

    Brown, W V; Rose, H A; Lacey, M J; Wright, K

    2000-11-01

    The cuticular hydrocarbons of a widespread species of soil-burrowing cockroach, Macropanesthia rhinoceros, have been sampled from most of its known geographical locations. Analysis of extracts from individual insects has enabled a study of differences within a population as well as among geographical locations. In the case of M. rhinoceros, except for newly hatched first-instar nymphs, variations in hydrocarbon composition among individuals of different cohorts of M. rhinoceros, based on age and sex, are no greater than those among individuals of a single cohort. Geographical populations of this species are variable in hydrocarbon composition unless they occur within a few kilometres of each other. A few populations showed very different hydrocarbon patterns but, in the absence of any correlating biological differences, it is uncertain whether this signifies the presence of otherwise unrecognizable sibling species or just extreme examples of the geographical variation characteristic of this group of insects.

  14. Soil transmitted helminth infections and schistosomiasis in school age children in sub-Saharan Africa: efficacy of chemotherapeutic intervention since World Health Assembly Resolution 2001.

    PubMed

    Uneke, C J

    2010-01-01

    Soil transmitted helminth infections (STH) and schistosomiasis constitute major public health challenges among school-age children in sub-Saharan Africa. This review assessed the efficacy of chemotherapeutic intervention in line with the World Health Assembly (WHA) resolution since the passage in 2001. Using the Medline Entrez-Pubmed search, relevant publications were identified via combinations of key words such as helminth infection, school children, chemotherapy, Africa. Albendazole, mebendazole, and praziquantel were the antihelminthic drugs most commonly evaluated. Cure rates >80% and egg reduction rates >90% were recorded in most cases of schistosomiasis using praziquantel. Albendazole was very effective against A. lumbricoides and hookworm infections with majority of the studies recording cure rates >75%, but the efficacy of the drug was poor against T. trichiura. To ensure the realization of the WHA resolution, there is need for regular treatment of school children, development of alternative antihelminthic drugs and vaccines, environmental control measures and health education.

  15. Soil transmitted helminth infections and schistosomiasis in school age children in sub-Saharan Africa: efficacy of chemotherapeutic intervention since World Health Assembly Resolution 2001.

    PubMed

    Uneke, C J

    2010-01-01

    Soil transmitted helminth infections (STH) and schistosomiasis constitute major public health challenges among school-age children in sub-Saharan Africa. This review assessed the efficacy of chemotherapeutic intervention in line with the World Health Assembly (WHA) resolution since the passage in 2001. Using the Medline Entrez-Pubmed search, relevant publications were identified via combinations of key words such as helminth infection, school children, chemotherapy, Africa. Albendazole, mebendazole, and praziquantel were the antihelminthic drugs most commonly evaluated. Cure rates >80% and egg reduction rates >90% were recorded in most cases of schistosomiasis using praziquantel. Albendazole was very effective against A. lumbricoides and hookworm infections with majority of the studies recording cure rates >75%, but the efficacy of the drug was poor against T. trichiura. To ensure the realization of the WHA resolution, there is need for regular treatment of school children, development of alternative antihelminthic drugs and vaccines, environmental control measures and health education. PMID:20737834

  16. Phytoextraction of metals and rhizoremediation of PAHs in co-contaminated soil by co-planting of Sedum alfredii with ryegrass (Lolium perenne) or castor (Ricinus communis).

    PubMed

    Wang, Kai; Huang, Huagang; Zhu, Zhiqiang; Li, Tingqiang; He, Zhenli; Yang, Xiaoe; Alva, Ashok

    2013-01-01

    A pot experiment was conducted to investigate the potential for phytoextraction of heavy metals and rhizoremediation of polycyclic aromatic hydrocarbons (PAHs) in co-contaminated soil by co-planting a cadmium/zinc (Cd/Zn) hyperaccumulator and lead (Pb) accumulator Sedum alfredii with ryegrass (Lolium perenne) or castor (Ricinus communis). Co-planting with castor decreased the shoot biomass of S. alfredii as compared to that in monoculture. Cadmium concentration in S. alfredii shoot significantly decreased when grown with ryegrass or castor as compared to that in monoculture. However, no reduction of Zn or Pb concentration in S. alfredii shoot was detected in co-planting treatments. Total removal of either Cd, Zn, or Pb by plants was similar across S. alfredii monoculture or co-planting with ryegrass or castor, except enhanced Pb removal in S. alfredii and ryegrass co-planting treatment. Co-planting of S. alfredii with ryegrass or castor significantly enhanced the pyrene and anthracene dissipation as compared to that in the bare soil or S. alfredii monoculture. This appears to be due to the increased soil microbial population and activities in both co-planting treatments. Co-planting of S. alfredii with ryegrass or castor provides a promising strategy to mitigate both metal and PAH contaminants from co-contaminated soils.

  17. Bioremediation of high molecular weight polyaromatic hydrocarbons co-contaminated with metals in liquid and soil slurries by metal tolerant PAHs degrading bacterial consortium.

    PubMed

    Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

    2012-11-01

    Bioremediation of polyaromatic hydrocarbons (PAH) contaminated soils in the presence of heavy metals have proved to be difficult and often challenging due to the ability of toxic metals to inhibit PAH degradation by bacteria. In this study, a mixed bacterial culture designated as consortium-5 was isolated from a former manufactured gas plant (MGP) site. The ability of this consortium to utilise HMW PAHs such as pyrene and BaP as a sole carbon source in the presence of toxic metal Cd was demonstrated. Furthermore, this consortium has proven to be effective in degradation of HMW PAHs even from the real long term contaminated MGP soil. Thus, the results of this study demonstrate the great potential of this consortium for field scale bioremediation of PAHs in long term mix contaminated soils such as MGP sites. To our knowledge this is the first study to isolate and characterize metal tolerant HMW PAH degrading bacterial consortium which shows great potential in bioremediation of mixed contaminated soils such as MGP.

  18. Soil-Transmitted Helminths in Pre-School-Aged and School-Aged Children in an Urban Slum: A Cross-Sectional Study of Prevalence, Distribution, and Associated Exposures

    PubMed Central

    Davis, Stephanie M.; Worrell, Caitlin M.; Wiegand, Ryan E.; Odero, Kennedy O.; Suchdev, Parminder S.; Ruth, Laird J.; Lopez, Gerard; Cosmas, Leonard; Neatherlin, John; Njenga, Sammy M.; Montgomery, Joel M.; Fox, LeAnne M.

    2014-01-01

    Soil-transmitted helminths (STHs) are controlled by regular mass drug administration. Current practice targets school-age children (SAC) preferentially over pre-school age children (PSAC) and treats large areas as having uniform prevalence. We assessed infection prevalence in SAC and PSAC and spatial infection heterogeneity, using a cross-sectional study in two slum villages in Kibera, Nairobi. Nairobi has low reported STH prevalence. The SAC and PSAC were randomly selected from the International Emerging Infections Program's surveillance platform. Data included residence location and three stools tested by Kato-Katz for STHs. Prevalences among 692 analyzable children were any STH: PSAC 40.5%, SAC 40.7%; Ascaris: PSAC 24.1%, SAC 22.7%; Trichuris: PSAC 24.0%, SAC 28.8%; hookworm < 0.1%. The STH infection prevalence ranged from 22% to 71% between sub-village sectors. The PSAC have similar STH prevalences to SAC and should receive deworming. Small areas can contain heterogeneous prevalences; determinants of STH infection should be characterized and slums should be assessed separately in STH mapping. PMID:25157123

  19. Soil-transmitted helminths in pre-school-aged and school-aged children in an urban slum: a cross-sectional study of prevalence, distribution, and associated exposures.

    PubMed

    Davis, Stephanie M; Worrell, Caitlin M; Wiegand, Ryan E; Odero, Kennedy O; Suchdev, Parminder S; Ruth, Laird J; Lopez, Gerard; Cosmas, Leonard; Neatherlin, John; Njenga, Sammy M; Montgomery, Joel M; Fox, LeAnne M

    2014-11-01

    Soil-transmitted helminths (STHs) are controlled by regular mass drug administration. Current practice targets school-age children (SAC) preferentially over pre-school age children (PSAC) and treats large areas as having uniform prevalence. We assessed infection prevalence in SAC and PSAC and spatial infection heterogeneity, using a cross-sectional study in two slum villages in Kibera, Nairobi. Nairobi has low reported STH prevalence. The SAC and PSAC were randomly selected from the International Emerging Infections Program's surveillance platform. Data included residence location and three stools tested by Kato-Katz for STHs. Prevalences among 692 analyzable children were any STH: PSAC 40.5%, SAC 40.7%; Ascaris: PSAC 24.1%, SAC 22.7%; Trichuris: PSAC 24.0%, SAC 28.8%; hookworm < 0.1%. The STH infection prevalence ranged from 22% to 71% between sub-village sectors. The PSAC have similar STH prevalences to SAC and should receive deworming. Small areas can contain heterogeneous prevalences; determinants of STH infection should be characterized and slums should be assessed separately in STH mapping.

  20. Determination of the provenance of cocoa by soil protolith ages and assessment of anthropogenic lead contamination by pb/nd and lead isotope ratios.

    PubMed

    Manton, William I

    2010-01-27

    The Pb contents of chocolate and the products it flavors are among the highest of all commonly consumed substances. Others have shown that this Pb is acquired by cocoa beans after harvesting and is concentrated in their shells, portions of which are ground up with the cotyledons during processing. It is shown here that the shells also contain the lanthanides Nd and Sm, which they appear to take up more slowly than Pb when dried on bare soil. Consideration of Pb/Nd ratios, model Sm-Nd ages and the isotope ratios of Pb and Sr indicates that, in the absence of contamination, the relationship between Pb and Nd in shells is y = 13.1x(-0.383), where x is the Nd concentration in microg/kg and y is the Pb/Nd ratio. For cocoa powders, the relationship is y = 114x(-0.988). Samples that plot above these curves are probably contaminated. Model ages indicate where the cocoa of cocoa powders is grown, and these same considerations point to African samples being uncontaminated but samples from Asia containing 50% anthropogenic Pb of Australian origin. No measurable Pb contamination occurs during the transport of beans and the manufacture of chocolate.

  1. Impact of community-directed treatment on soil transmitted helminth infections in children aged 12 to 59 months in Mazabuka District, Zambia.

    PubMed

    Halwindi, Hikabasa; Magnussen, Pascal; Siziya, Seter; Handema, Ray; Meyrowitsch, Dan W; Olsen, Annette

    2011-10-01

    This study assessed the impact of adding community-directed treatment (ComDT) to the routine health facility (HF)-based treatment on prevalence and intensity of soil transmitted helminth (STH) infections among children aged 12 to 59 months. Repeated cross-sectional surveys were conducted among randomly selected children of this age group from the intervention area (HF+ComDT area) and the comparison area (HF area) at baseline (n=986), 12 months (n=796) and 18 months (n=788) follow-up. The prevalence of Ascaris lumbricoides was significantly higher in the HF+ComDT as compared to the HF area at baseline (P=0·048), but not at 12 and 18 months follow-up. At baseline the HF+ComDT area had significantly higher intensities of A. lumbricoides compared to the HF area (P<0·001), but not at 12 and 18 months follow-ups. Prevalence and intensity of hookworm did not differ significantly between treatment arms at any time. Analysis of trends showed a significant decrease in prevalence of A. lumbricoides and hookworm in the HF+ComDT area (P<0·001), of hookworm in the HF area (P<0·05), but not of A. lumbricoides in the HF area. It is concluded that the ComDT approach generally enhanced the treatment effect among under-five year children and that this alternative approach may also have advantages in other geographical settings.

  2. Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbate Aging on Contaminant Speciation and Mobility

    SciTech Connect

    Chorover, Jon; Mueller, Karl T.; O'Day, Peggy; Serne, R. Jeff; Um, Wooyong; Steefel, Carl

    2006-06-01

    Our work is aimed at developing a predictive-mechanistic understanding of the coupling between mineral weathering from caustic waste release and contaminant (Cs, Sr, I) fate and transport in waste-impacted sediments across space, time and geochemical gradients that encompass the process-level heterogeneity observed at the Hanford DOE site. Our specific objectives are: (1) to assess the molecular-scale mechanisms responsible for time-dependent sequestration of contaminants (Cs, Sr and I) during penetration of waste-induced weathering fronts through sedimentary media; (2) to determine the rate and extent of contaminant release from the sorbed state; (3) to develop a reactive transport model based on molecular mechanisms and macroscopic flow experiments (from (1) and (2)) that accurately simulates adsorption, aging, and desorption at the bench-scale, and that can be applied to--and validated at--field sites such as Hanford.

  3. Toenail selenium as an indicator of selenium intake among middle-aged men in an area with low soil selenium.

    PubMed

    Ovaskainen, M L; Virtamo, J; Alfthan, G; Haukka, J; Pietinen, P; Taylor, P R; Huttunen, J K

    1993-05-01

    Toenail selenium concentration has been proposed as a long-term (6-12 mo) indicator of human selenium status. This study investigated the association between toenail selenium concentration and selenium intake and other dietary factors among 166 urban men aged 55-69 y. The dietary information was collected by food records covering a 6-mo period. Toenail clippings were collected by mail 9-10 mo after food recording. The mean selenium intake from food was 42.5 micrograms/d and the dietary intake was equal to that of users and nonusers of selenium supplements. The mean toenail selenium concentration was 0.47 mg/kg. The mean selenium intake from supplements was 29.7 micrograms/d among supplement users. In the analysis of covariance the best predictors of toenail selenium concentration were selenium intake from supplements and food, and among supplement users dietary beta-carotene also.

  4. Distribution, compositional pattern and sources of polycyclic aromatic hydrocarbons in urban soils of an industrial city, Lanzhou, China.

    PubMed

    Jiang, Yufeng; Yves, Uwamungu J; Sun, Hang; Hu, Xuefei; Zhan, Huiying; Wu, Yingqin

    2016-04-01

    The level, distribution, compositional pattern and possible sources of polycyclic aromatic hydrocarbons (PAHs) in Lanzhou urban soil of Northwest China were investigated in this study. The total level of 22 PAHs ranged from 115 to 12,100 µg kg(-1) and that of 16 priority PAHs from 82.4 to 10,900 µg kg(-1). Seven carcinogenic PAHs generally accounted for 6.18-57.4% of total 22 PAHs. Compared with data from those reported about urban areas, PAH contamination in Lanzhou urban soils was moderate. Among different functional areas, higher level of PAHs was found along roadsides and in the industrial district (p<0.01), while lower levels were detected in the commercial, park and residential districts. The composition of PAHs was characterized by high molecular weight PAHs (≥4 rings), among which fluoranthene, benz[a]anthracene and phenanthrene were the most dominant components. Correlation analysis suggested that low molecular weight PAHs and high molecular weight PAHs originated from different sources and further corroborated that TOC was an important factor in the accumulation of PAHs in soil. Isomer ratios and principal component analysis indicated that PAHs in urban soil derived primarily from emissions resulting from the combustion of biomass, coal and petroleum products. Toxic equivalent concentrations (BaP(eq)) of soil PAHs ranged from 6.12 to 1302 µg BaP(eq) kg(-1), with a mean of 138 µg BaP(eq) kg(-1). The results suggested that human exposure to those soils which polluted by high concentrations of PAHs through direct ingestion or inhalation of suspended soil particles probably poses a significant risk to human health from the carcinogenic effects of PAHs.

  5. Ecological and health risk-based characterization of agricultural soils contaminated with polycyclic aromatic hydrocarbons in the vicinity of a chemical plant in China.

    PubMed

    Liu, Geng; Niu, Junjie; Guo, Wenjiong; An, Xiangsheng; Zhao, Long

    2016-11-01

    Polycyclic aromatic hydrocarbons (PAHs) from chemical plants can cause serious pollution of surrounding agricultural soils. A comprehensive study of agricultural soils was conducted in the vicinity of a chemical plant in China to characterize the soil PAH concentration, as well as their composition and sources. Human health and a screening-level ecological risk assessment were conducted for PAH contamination in agricultural soils. The results showed that the total concentrations of 16 priority PAHs ranged from 250.49 to 9387.26 ng g(-1), with an average of 2780.42 ng g(-1). High molecular weight PAHs (four to six rings) were the dominant component, accounting for more than 60% of all PAHs. Principal component analysis (PCA) and positive matrix factorization model (PMF) suggested that diesel emissions, coal combustion, coke ovens, and fuel combustion and gasoline emissions were the main sources of PAHs in agricultural soils. The ecological risk assessment results based on the effects range-low (ERL), the effects range-median (ERM), and the ecological screening levels (ESL) indicated that the exposure to ∑PAH16 was >ERL, >ERM, and ≥ERL and soil sampling stations, the exposure to ∑PAH16 was >ESL at 78.1% of the soil sampling stations, and could induce biological effects in mammals. The Bapeq concentrations posed a potential carcinogenic risk to humans. Further risk management and control of soil PAHs in these agricultural soils is required to ensure the safety of the biocoenosis and human health. PMID:27565314

  6. 16S rDNA-based probes for two polycyclic aromatic hydrocarbon (PAH)-degrading soil Mycobacteria

    SciTech Connect

    Govindaswami, M.; Feldhake, D.J.; Loper, J.C.

    1994-12-31

    PAHs are a class of widespread pollutants, some of which have been shown to be genotoxic, hence the fate of these compounds in the environment is of considerable interest. Research on the biodegradation of 4 and 5 ring PAHs has been limited by the general lack of microbial isolates or consortia which can completely degrade these toxicants. Heitkamp and Cerniglia have described an oxidative soil Mycobacterium-strain PYR-1 that metabolizes pyrene and fluoranthene more rapidly than the 2 and 3 ring naphthalene and phenanthrene; although some metabolites of benzo-(a)-pyrene (BaP) were detected, no mineralization of BaP was observed. In 1991 Grosser et al. reported the isolation of a Mycobacterium sp. which mineralizes pyrene and also causing some mineralization of BaP. Their study describes a comparative analysis of these two strains, which show very similar colony morphology, growth rate and yellow-orange pigmentation. Genetic differences were shown by DNA amplification fingerprinting (DAF) using two arbitrary GC-rich octanucleotide primers, and by sequence comparison of PCR amplified 16S rDNA, although both strains show similarity closest to that of the genus Mycobacteria. These 16S rDNA sequences are in use for the construction of strain-specific DNA probes to monitor the presence, survival and growth of these isolates in PAH-contaminated soils in studies of biodegradation.

  7. Effects of elevated CO{sub 2}, soil nutrient levels, and foliage age on the performance of two generations of Neodiprion lecontei (Hymenoptera: Diprionidae) feeding on loblolly pine

    SciTech Connect

    Williams, R.S. |; Thomas, R.B.; Strain, B.R.; Lincoln, D.E.

    1997-12-01

    We investigated how changes in loblolly pine needle phytochemistry caused by elevated CO{sub 2}, leaf age, and soil nutrient levels affected the performance of 2 individual generations of the multivoltine folivorous insect pest Neodiprion lecontei. In 2 feeding trials, mature needles produced in the previous (spring) and current (fall) year from seedlings grown in open-topped chambers under 4 CO{sub 2} and 2 soil nutrient levels were fed to 2 separate generations of red beaded pine sawfly larvae. Strong seasonal differences (i.e., spring versus fall) in leaf nutritional and defensive constituents resulted in significant between-generation differences in the growth, consumption, and growth efficiency of sawfly larvae. Enriched CO{sub 2}-grown needles bad higher levels of starch and starch/nitrogen ratios in older, overwintering spring needles, which were lower in leaf nitrogen and monoterpenes than younger, current year needles (fall). Overall, larval growth was higher and consumption lower on the fall needles, presumably because of higher levels of leaf nitrogen compared with the spring needles. The plant CO{sub 2} concentration significantly contributed to the larval consumption responses between seasons (significant CO{sub 2} X season interaction), demonstrating that the 2 sawfly generations were affected differently by CO{sub 2}-induced phytochemical alterations in spring versus fall needles. The data presented here suggests that when investigating multivoltine folivorous insect responses to elevated CO{sub 2}-grown tree seedlings in which multiple leaf flushes within a growing season expose insects to an array of leaf phytochemical changes, >1 insect generation should be investigated. 54 refs., 3 figs., 1 tab.

  8. Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbent Aging on Contaminant Speciation and Mobility

    SciTech Connect

    Chorover, J.; Mueller, K. T.; O'Day, P. A.; Serne, R. J.; Steefel, C. I.

    2009-10-30

    This project aimed for a predictive-mechanistic understanding of the coupling between mineral weathering and contaminant (Cs, Sr, I) transport/fate in caustic waste-impacted sediments. Based on our prior studies of model clay mineral systems, we postulated that contaminant uptake to Hanford sediments would reflect concurrent adsorption and co-precipitation effects. Our specific objectives were: (1) to assess the molecular-scale mechanisms responsible for time-dependent sequestration of contaminants (Cs, Sr and I) during penetration of waste-induced weathering fronts; (2) to determine the rate and extent of contaminant release from the sorbed state; (3) to develop a reactive transport model based on molecular mechanisms and macroscopic flow experiments [(1) and (2)] that simulates adsorption, aging, and desorption dynamics. Progress toward achieving each of these objectives is discussed below. We observed unique molecular mechanisms for sequestration of Sr, Cs and I during native silicate weathering in caustic waste. Product solids, which included poorly crystalline aluminosilicates and well-crystallized zeolites and feldspathoids, accumulate contaminant species during crystal growth.

  9. Chemical contamination of soils in the New York City area following Hurricane Sandy.

    PubMed

    Mandigo, Amy C; DiScenza, Dana J; Keimowitz, Alison R; Fitzgerald, Neil

    2016-10-01

    This paper presents a unique data set of lead, arsenic, polychlorinated biphenyl (PCB), and polycyclic aromatic hydrocarbon (PAH) concentrations in soil samples collected from the metropolitan New York City area in the aftermath of Hurricane Sandy. Initial samples were collected by citizen scientists recruited via social media, a relatively unusual approach for a sample collection project. Participants in the affected areas collected 63 usable samples from basements, gardens, roads, and beaches. Results indicate high levels of arsenic, lead, PCBs, and PAHs in an area approximately 800 feet south of the United States Environmental Protection Agency (US EPA) Superfund site at Newtown Creek. A location adjacent to the Gowanus Canal, another Superfund site, was found to have high PCB concentrations. Areas of high PAH contamination tended to be near high traffic areas or next to sites of known contamination. While contamination as a direct result of Hurricane Sandy cannot be demonstrated conclusively, the presence of high levels of contamination close to known contamination sites, evidence for co-contamination, and decrease in number of samples containing measureable amounts of semi-volatile compounds from samples collected at similar locations 9 months after the storm suggest that contaminated particles may have migrated to residential areas as a result of flooding.

  10. Chemical contamination of soils in the New York City area following Hurricane Sandy.

    PubMed

    Mandigo, Amy C; DiScenza, Dana J; Keimowitz, Alison R; Fitzgerald, Neil

    2016-10-01

    This paper presents a unique data set of lead, arsenic, polychlorinated biphenyl (PCB), and polycyclic aromatic hydrocarbon (PAH) concentrations in soil samples collected from the metropolitan New York City area in the aftermath of Hurricane Sandy. Initial samples were collected by citizen scientists recruited via social media, a relatively unusual approach for a sample collection project. Participants in the affected areas collected 63 usable samples from basements, gardens, roads, and beaches. Results indicate high levels of arsenic, lead, PCBs, and PAHs in an area approximately 800 feet south of the United States Environmental Protection Agency (US EPA) Superfund site at Newtown Creek. A location adjacent to the Gowanus Canal, another Superfund site, was found to have high PCB concentrations. Areas of high PAH contamination tended to be near high traffic areas or next to sites of known contamination. While contamination as a direct result of Hurricane Sandy cannot be demonstrated conclusively, the presence of high levels of contamination close to known contamination sites, evidence for co-contamination, and decrease in number of samples containing measureable amounts of semi-volatile compounds from samples collected at similar locations 9 months after the storm suggest that contaminated particles may have migrated to residential areas as a result of flooding. PMID:26486130

  11. DEVELOPMENT AND APPLICATION OF EQUILIBRIUM PARTITIONING SEDIMENT GUIDELINES IN THE ASSESSMENT OF SEDIMENT PAH CONTAMINATION

    EPA Science Inventory

    The U.S. Environmental Protection Agency used insights and methods from its water quality criteria program to develop ESGs. The discovery that freely-dissolved contaminants were the toxic form led to equilibrium partitioning being chosen to model the distribution of contaminants...

  12. Monitoring PAH contamination in water: comparison of biological and physico-chemical tools.

    PubMed

    Bourgeault, A; Gourlay-Francé, C

    2013-06-01

    The suitability of biological methods and chemical-based passive samplers to determine exposure to PAHs was tested by deploying zebra mussels and SPMDs along the Seine River over 11 months. The concentration of 13 PAHs was analyzed every month in both water and mussels. The sum of the PAH concentrations in mussels, initially at 299 ng gdry wt(-1), reached 2654, 3972 and 3727 ng g(-1) at the end of exposure in the three sampling points taken through the river. The respective SPMD-available concentrations of TPAHs reached 9, 52 and 34 ng L(-1). Results showed seasonal variations of total PAH concentrations in the mussels, characterized by a decrease during spawning. The non-achievement of steady state concentration that was observed in mussels may be accounted for by the temporal variation of environmental concentrations. Thus, a bioaccumulation model based on kinetic rather than simple equilibrium partitioning was found to be more appropriate to describe PAH content in mussels. Moreover, biodynamic kinetic modeling proved useful to better understand the uptake and loss processes of pyrene. It clearly shows that these processes are markedly influenced by the biological state of the zebra mussels. The most realistic hypothesis is that the temporal variation of the biodynamic parameters may originate from a decrease of the mussels' metabolization of PAHs during spawning. Since SPMD passive samplers cannot integrate such biological factors, they are poor predictors of PAH bioavailability in mussels. PMID:23562685

  13. PAHs contamination in bank sediment of the Yamuna river, Delhi, India.

    PubMed

    Agarwal, Tripti; Khillare, P S; Shridhar, Vijay

    2006-12-01

    This study was performed to elucidate the distribution, concentration trend and possible sources of PAHs in bank sediment of river Yamuna in Delhi, India. The levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed during pre-monsoon, monsoon and post-monsoon seasons in the sediment fraction < 53 microm. Reference standards and internal standards were used for identification and quantification of PAHs by HPLC. The sum of 16 PAH compounds ranged from 4.50 to 23.53 microg/g with a mean concentration of 10.15 +/- 4.32 microg/g (dry wt.). Among 5 sites studied, the site, Income Tax Office (ITO) was found to be the hotspot attaining highest concentration. Predominance of 2-4 ring PAHs suggests a relatively recent local sources of PAHs in the study area. Moreover, molecular indices based source apportionment also illustrates pyrogenic source fingerprint of PAHs. No significant temporal trend was observed. PMID:16763739

  14. CHARACTERIZATION AND FATE OF PAH-CONTAMINATED SEDIMENTS AT THE WYCKOFF/EAGLE HARBOR SUPERFUND SITE

    EPA Science Inventory

    Eagle Harbor is a shallow marine embayment of Bainbridge Island, WA and formerly the site of the Wyckoff wood-treatment facility. The facility became operational in the early 1900s and used large quantities of creosote in its wood-treating processes. Creosote percolated through t...

  15. Over a century of PAH contamination history to New York City

    NASA Astrophysics Data System (ADS)

    Yan, B.; Bopp, R.; Chillrud, S. N.; Abrajano, T.

    2015-12-01

    Spatially and temporally integrated urban lake sediments have the potential to be used for reconstructing air contamination history, with data being available even before the start of urban air quality monitoring. In a previous study, fine-grained sediment sample cores were collected from the Lower Hudson River basin and dated via radionuclides. An objective source appointment method has been established based on several source-sensitive molecular indicators we found. An over 100 year historical record of energy usage in New York City has been reconstructed in cores from Central Park Lake. The reconstructed history is consistent with historical energy consumption data of NYS complied by the US Department of Energy. Wood combustion was dominant one century ago in Manhattan, followed by coal combustion dominance from the 1900s to the 1940s. Petroleum combustion, mainly from motor vehicles in Manhattan, increased gradually from the 1920s, and became the dominant PAH input after 1940s. In most samples collected from elsewhere in the lower Hudson River Basin, petroleum combustion was the dominant PAH input in the last half century. From 2001 to 2012, indoor and outdoor air filter samples were collected from NYC apartments; though non-volatile PAH levels were quite stable, pyrene, which is a semi-volatile PAHs compound, increased over these 12 years, especially in the heating season. The burning of No.6 oil in NYC boilers is thought to lead to this increase and the recent effort in switching No. 6 heating oil to No.2 oil has the potential to overturn the increasing trend.

  16. UTILIZATION OF BIOREMEDIATION PROCESSES FOR THE TREATMENT OF PAH-CONTAMINATED SEDIMENTS. (R825513C020)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. PAHs contamination in bank sediment of the Yamuna river, Delhi, India.

    PubMed

    Agarwal, Tripti; Khillare, P S; Shridhar, Vijay

    2006-12-01

    This study was performed to elucidate the distribution, concentration trend and possible sources of PAHs in bank sediment of river Yamuna in Delhi, India. The levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed during pre-monsoon, monsoon and post-monsoon seasons in the sediment fraction < 53 microm. Reference standards and internal standards were used for identification and quantification of PAHs by HPLC. The sum of 16 PAH compounds ranged from 4.50 to 23.53 microg/g with a mean concentration of 10.15 +/- 4.32 microg/g (dry wt.). Among 5 sites studied, the site, Income Tax Office (ITO) was found to be the hotspot attaining highest concentration. Predominance of 2-4 ring PAHs suggests a relatively recent local sources of PAHs in the study area. Moreover, molecular indices based source apportionment also illustrates pyrogenic source fingerprint of PAHs. No significant temporal trend was observed.

  18. Determination of polynuclear aromatic hydrocarbons (PAHs) in soil and water by a magnetic particle-based enzyme immunoassay system

    SciTech Connect

    Rubio, F.M.; Lawruk, T.S.; Lachman, C.E.; Herzog, D.P.; Fleeker, J.R.

    1995-12-31

    Use of immunoassays as field-screening methods to detect environmental contaminants has increased dramatically in recent years. Immunochemical assays are sensitive, rapid, reliable, cost-effective and can be used for lab or field analysis. A magnetic particle-based immunoassay system has been developed for the quantitation of polynuclear aromatic hydrocarbons (PAHs) in soil and water. Paramagnetic particles used as the solid-phase allow for the precise addition of antibody and nondiffusion limited reaction kinetics. The magnetic particle-based immunoassay is ideally suited for on-site investigation and remediation processes to delineate PAH contamination. This system includes easy-to-use materials for collection, extraction, filtration and dilution of soil samples prior to analysis by immunoassay. When analyzing water samples, a simple dilution of the sample with methanol is performed during sample collection. The method detects PAHs, including anthracene, chrysene, fluoranthene, phenanthrene, pyrene and benzo[a]pyrene, at sub-parts-per-million levels in soil and at less than 1 ppb in water. The typical precision of the assay (within assay) in soil and water is less than 15% and 12%, respectively. Recovery studies (based on phenanthrene) from soil averaged 108%, and 107% from water. The analysis of soil samples by this ELISA correlate well with Method 8310, yielding a correlation coefficient (r) of 0.963; when water samples were compared to method 8270, a regression (r) of 0.987 was obtained. The application of this ELISA method permits the cost-effective evaluation of samples with minimal solvent disposal and can result in savings of time and money. The system`s flexibility allows the analysis of PAHs in many other sample matrices with minimum sample preparation.

  19. Soil-transmitted helminth infections and physical fitness in school-aged Bulang children in southwest China: results from a cross-sectional survey

    PubMed Central

    2012-01-01

    Background Chronic soil-transmitted helminth (STH) infections have been associated with reduced physical fitness, but available evidence is limited. The aim of this cross-sectional survey was to assess the feasibility of measuring children's physical fitness and to relate it to STH infections. Our study was carried out among school-aged children of the Bulang ethnic group in rural southwest People's Republic of China (P.R. China). Standardized, quality-controlled methods were employed to determine STH infections (Kato-Katz technique), haemoglobin levels, anthropometry (body weight and height) and physical fitness (20-m shuttle run test). Results A compliance of 87% suggested good acceptance of the methods used. Among 69 children with complete data records, infection prevalence of Trichuris trichiura, Ascaris lumbricoides and hookworm were 81%, 44% and 6%, respectively. The maximum volume of oxygen that can be utilized within 1 min during exhaustive exercise (VO2 max estimate) of T. trichiura-infected children was 1.94 ml kg-1 min-1 lower than that of their non-infected counterparts (P = 0.005). Until exhaustion, T. trichiura-infected children had completed 6.14 20-m laps less (P = 0.004). Additionally, the mean VO2 max estimate of stunted children was lowered by 1.63 ml kg-1 min-1 (P = 0.002) and they completed 5.32 20-m laps less (P = 0.001) compared to children of normal stature. No significant association between stunting and infection with any STH species could be established. Conclusions Implementation of physical fitness tests in rural, resource-constraint settings is feasible. The physical fitness of children who are stunted or infected with STHs, particularly T. trichiura, is significantly impaired. We have launched a larger study and will determine the dynamics of school-aged children's physical fitness over a 7-month period after administration of anthelminthic drugs. PMID:22424138

  20. Polycyclic aromatic hydrocarbons in soil of the Canadian River floodplain in Oklahoma

    USGS Publications Warehouse

    Sartori, F.; Wade, T.L.; Sericano, J.L.; Mohanty, B.P.; Smith, K.A.

    2010-01-01

    The accumulation of polycyclic aromatic hydrocarbons (PAH) in soil, plants, and water may impart negative eff ects on ecosystem and human health. We quantified the concentration and distribution of 41 PAH (n = 32), organic C, total N, and S (n = 140) and investigated PAH sources using a chronosequence of floodplain soils under a natural vegetation succession. Soil samples were collected between 0- and 260-cm depth in bare land (the control), wetland, forest, and grassland areas near a closed municipal landfill and an active asphalt plant (the contaminant sources) in the north bank of the Canadian River near Norman, OK. Principal component, cluster, and correlation analyses were used to investigate the spatial distribution of PAH, in combination with diagnostic ratios to distinguish pyrogenic vs. petrogenic PAH suites. Total PAH concentration (??PAH) had a mean of 1300 ng g-1, minimum of 16 ng g-1, and maximum of 12,000 ng g-1. At 0- to 20-cm depth, ??PAH was 3500 ?? 1600 ng g-1 (mean ?? 1 SE) near the contaminant sources. The most common compounds were nonalkylated, high molecular weight PAH of pyrogenic origin, i.e., fluoranthene (17%), pyrene (14%), phenanthrene (9%), benzo(b)fluoranthene (7%), chrysene (6%), and benzo(a)anthracene (5%). ??PAH in the control (130 ?? 23 ng g -1) was comparable to reported concentrations for the rural Great Plains. Perylene had a unique distribution pattern suggesting biological inputs. The main PAH contamination mechanisms were likely atmospheric deposition due to asphalt production at the 0- to 20-cm depth and past landfill operations at deeper depths. Copyright ?? 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  1. Soil-Transmitted Helminth Reinfection and Associated Risk Factors among School-Age Children in Chencha District, Southern Ethiopia: A Cross-Sectional Study

    PubMed Central

    Zerdo, Zerihun; Yohanes, Tsegaye; Tariku, Befikadu

    2016-01-01

    Mass drug administration (MDA) to the most risky population including school-age children (SAC) is the central strategy to control soil-transmitted helminth (STH) infection. The present study was aimed at estimating the prevalence of STHs reinfection three months posttreatment and associated risk factors among SAC in Chencha district. A cross-sectional study design was employed from April 20 to May 5, 2015, to enroll 408 SAC. Structured questionnaire and Kato-Katz thick smear technique were used to interview parents or guardians and quantify the number of eggs per gram of stool. Pearson chi-square and logistic regression were used to assess the association between predictor variable and STH reinfection. The prevalence of STHs within three months of mass chemotherapy among SAC was 36.8% which is 93.4% of the prevalence (39.4%) before treatment. The estimated prevalence of reinfection (95%CI) for Ascaris lumbricoides, Trichuris trichiura, and hookworms was 23.8% (21.1–28.2), 16.2% (12.7–20.1), and 1.0% (0.3–2.5), respectively. Children of merchant fathers were more likely to be reinfected by STHs in Chencha district. In conclusion, there is rapid reinfection after mass chemotherapy among SAC in Chencha district. Further studies should be carried out to generate cost efficient methods that can supplement mass drug administration to accelerate the control of STHs. PMID:26941997

  2. Shifts in bryophyte carbon isotope ratio across an elevation × soil age matrix on Mauna Loa, Hawaii: do bryophytes behave like vascular plants?

    PubMed

    Waite, Mashuri; Sack, Lawren

    2011-05-01

    The carbon isotope ratio (δ(13)C) of vascular plant leaf tissue is determined by isotope discrimination, primarily mediated by stomatal and mesophyll diffusion resistances and by photosynthetic rate. These effects lead to predictable trends in leaf δ(13)C across natural gradients of elevation, irradiance and nutrient supply. Less is known about shifts in δ(13)C for bryophytes at landscape scale, as bryophytes lack stomata in the dominant gametophyte phase, and thus lack active control over CO(2) diffusion. Twelve bryophyte species were sampled across a matrix of elevation and soil ages on Mauna Loa, Hawaii Island. We tested hypotheses based on previous findings for vascular plants, which tend to have less negative δ(13)C at higher elevations or irradiances, and for leaves with higher leaf mass per area (LMA). Across the matrix, bryophytes spanned the range of δ(13)C values typical of C(3) vascular plants. Bryophytes were remarkably similar to vascular plants in exhibiting less negative δ(13)C with increasing elevation, and with lower overstory cover; additionally δ(13)C was related to bryophyte canopy projected mass per area, a trait analogous to LMA in vascular plants, also correlated negatively with overstory cover. The similarity of responses of δ(13)C in bryophytes and vascular plants to environmental factors, despite differing morphologies and diffusion pathways, points to a strong direct role of photosynthetic rate in determining δ(13)C variation at the landscape scale.

  3. Soil-Transmitted Helminth Reinfection and Associated Risk Factors among School-Age Children in Chencha District, Southern Ethiopia: A Cross-Sectional Study.

    PubMed

    Zerdo, Zerihun; Yohanes, Tsegaye; Tariku, Befikadu

    2016-01-01

    Mass drug administration (MDA) to the most risky population including school-age children (SAC) is the central strategy to control soil-transmitted helminth (STH) infection. The present study was aimed at estimating the prevalence of STHs reinfection three months posttreatment and associated risk factors among SAC in Chencha district. A cross-sectional study design was employed from April 20 to May 5, 2015, to enroll 408 SAC. Structured questionnaire and Kato-Katz thick smear technique were used to interview parents or guardians and quantify the number of eggs per gram of stool. Pearson chi-square and logistic regression were used to assess the association between predictor variable and STH reinfection. The prevalence of STHs within three months of mass chemotherapy among SAC was 36.8% which is 93.4% of the prevalence (39.4%) before treatment. The estimated prevalence of reinfection (95%CI) for Ascaris lumbricoides, Trichuris trichiura, and hookworms was 23.8% (21.1-28.2), 16.2% (12.7-20.1), and 1.0% (0.3-2.5), respectively. Children of merchant fathers were more likely to be reinfected by STHs in Chencha district. In conclusion, there is rapid reinfection after mass chemotherapy among SAC in Chencha district. Further studies should be carried out to generate cost efficient methods that can supplement mass drug administration to accelerate the control of STHs. PMID:26941997

  4. Environmental carcinogenic polycyclic aromatic hydrocarbons in soil from Himalayas, India: Implications for spatial distribution, sources apportionment and risk assessment.

    PubMed

    Devi, Ningombam Linthoingambi; Yadav, Ishwar Chandra; Shihua, Qi; Dan, Yang; Zhang, Gan; Raha, Priyankar

    2016-02-01

    The Indian Himalayan Region (IHR) is one of the important mountain ecosystems among the global mountain system which support wide variety of flora, fauna, human communities and cultural diversities. Surface soil samples (n = 69) collected from IHR were analysed for 16 priority polycyclic aromatic hydrocarbons (PAH) listed by USEPA. The ∑16PAH concentration in surface soil ranged from 15.3 to 4762 ngg(-1) (mean 458 ngg(-1)). The sum total of low molecular weight PAH (∑LMW-PAHs) (mean 74.0 ngg(-1)) were relatively lower than the high molecular weight PAH (∑HMW-PAHs) (mean 384 ngg(-1)). The concentration of eight carcinogenic PAHs (BaA, CHR, BbF, BkF, BaP, DahA, IcdP, BghiP) were detected high in mountain soil from IHR and ranged from 0.73 to 2729 ngg(-1) (mean 272 ngg(-1)). Based on spatial distribution map, high concentration of HMW- and LMW-PAHs were detected at GS1 site in Guwahati (615 and 4071 ngg(-1)), and lowest concentration of HMW-PAHs were found at IS6 in Itanagar (5.80 ngg(-1)) and LMW-PAHs at DS2 (17.3 ngg(-1)) in Dibrugarh. Total organic carbon (TOC) in mountain soil was poorly connected with ∑PAHs (r(2) = 0.072) and Car-PAHs (r(2) = 0.048), suggesting the little role of TOC in adsorption of PAHs. Isomeric ratio of PAHs showed the source of PAH contamination in IHR is mixed of petrogenic and pyrogenic origin and was affirmed by PAHs composition profile. These source apportionment results were further confirmed by principal component analysis (PCA). Eco-toxicological analysis showed the calculated TEQ for most carcinogenic PAH were 2-4 times more than the Dutch allowed limit, while TEQ of BaP was 25 times high, suggesting increasing trend of carcinogenicity of surface soil. PMID:26386774

  5. Environmental carcinogenic polycyclic aromatic hydrocarbons in soil from Himalayas, India: Implications for spatial distribution, sources apportionment and risk assessment.

    PubMed

    Devi, Ningombam Linthoingambi; Yadav, Ishwar Chandra; Shihua, Qi; Dan, Yang; Zhang, Gan; Raha, Priyankar

    2016-02-01

    The Indian Himalayan Region (IHR) is one of the important mountain ecosystems among the global mountain system which support wide variety of flora, fauna, human communities and cultural diversities. Surface soil samples (n = 69) collected from IHR were analysed for 16 priority polycyclic aromatic hydrocarbons (PAH) listed by USEPA. The ∑16PAH concentration in surface soil ranged from 15.3 to 4762 ngg(-1) (mean 458 ngg(-1)). The sum total of low molecular weight PAH (∑LMW-PAHs) (mean 74.0 ngg(-1)) were relatively lower than the high molecular weight PAH (∑HMW-PAHs) (mean 384 ngg(-1)). The concentration of eight carcinogenic PAHs (BaA, CHR, BbF, BkF, BaP, DahA, IcdP, BghiP) were detected high in mountain soil from IHR and ranged from 0.73 to 2729 ngg(-1) (mean 272 ngg(-1)). Based on spatial distribution map, high concentration of HMW- and LMW-PAHs were detected at GS1 site in Guwahati (615 and 4071 ngg(-1)), and lowest concentration of HMW-PAHs were found at IS6 in Itanagar (5.80 ngg(-1)) and LMW-PAHs at DS2 (17.3 ngg(-1)) in Dibrugarh. Total organic carbon (TOC) in mountain soil was poorly connected with ∑PAHs (r(2) = 0.072) and Car-PAHs (r(2) = 0.048), suggesting the little role of TOC in adsorption of PAHs. Isomeric ratio of PAHs showed the source of PAH contamination in IHR is mixed of petrogenic and pyrogenic origin and was affirmed by PAHs composition profile. These source apportionment results were further confirmed by principal component analysis (PCA). Eco-toxicological analysis showed the calculated TEQ for most carcinogenic PAH were 2-4 times more than the Dutch allowed limit, while TEQ of BaP was 25 times high, suggesting increasing trend of carcinogenicity of surface soil.

  6. Determination of low levels of polycyclic aromatic hydrocarbons in soil by high performance liquid chromatography with tandem fluorescence and diode-array detectors.

    PubMed

    Huang, Yujuan; Wei, Jing; Song, Jing; Chen, Mengfang; Luo, Yongming

    2013-08-01

    Risk assessment of polycyclic aromatic hydrocarbons (PAHs) contaminated soil and source apportionment require accurate analysis of the concentration of each PAH congener in the soil. However, determination of low level PAH congeners in soil is difficult because of similarity in the chemical properties of 16 PAHs and severe matrix interferences due to complex composition of soils. It is therefore imperative to develop a sensitive and accurate method for determination of low level PAHs in soil. In this work, high performance liquid chromatography equipped with fluorescence and diode-array detectors (HPLC-FLD-DAD) was used to determine the concentration of 16 PAHs in soil. The separation of the 16 PAHs was achieved by optimization of the mobile phase gradient elution program and FLD wavelength switching program. Qualitative analysis of the 16 PAHs was based on the retention time (RT) and each PAH specific spectrum obtained from DAD. In contrast, the quantitative analysis of individual PAH congeners was based on the peak areas at the specific wavelength with DAD and FLD. Under optimal conditions the detection limit was in the range 1.0-9.5 μg L(-1) for 16 PAHs with DAD and 0.01-0.1 μg L(-1) for 15 PAHs with FLD, and the RSD of PAHs was less than 5% with DAD and 3% with FLD. The spiked recoveries were in the range 61-96%, with the exception of NaP (<40%). The results show that HPLC-FLD-DAD can provide more accurate and reliable analysis of low level PAH congeners in soil samples.

  7. Polycyclic aromatic hydrocarbons in soil of the Canadian river floodplain in Oklahoma.

    PubMed

    Sartori, Fabio; Wade, Terry L; Sericano, Jose L; Mohanty, Binayak P; Smith, Kevin A

    2010-01-01

    The accumulation of polycyclic aromatic hydrocarbons (PAH) in soil, plants, and water may impart negative effects on ecosystem and human health. We quantified the concentration and distribution of 41 PAH (n = 32), organic C, total N, and S (n = 140) and investigated PAH sources using a chronosequence of floodplain soils under a natural vegetation succession. Soil samples were collected between 0- and 260-cm depth in bare land (the control), wetland, forest, and grassland areas near a closed municipal landfill and an active asphalt plant (the contaminant sources) in the north bank of the Canadian River near Norman, OK. Principal component, cluster, and correlation analyses were used to investigate the spatial distribution of PAH, in combination with diagnostic ratios to distinguish pyrogenic vs. petrogenic PAH suites. Total PAH concentration (SigmaPAH) had a mean of 1300 ng g(-1), minimum of 16 ng g(-1), and maximum of 12,000 ng g(-1). At 0- to 20-cm depth, SigmaPAH was 3500 +/- 1600 ng g(-1) (mean +/- 1 SE) near the contaminant sources. The most common compounds were nonalkylated, high molecular weight PAH of pyrogenic origin, i.e., fluoranthene (17%), pyrene (14%), phenanthrene (9%), benzo(b)fluoranthene (7%), chrysene (6%), and benzo(a)anthracene (5%). SigmaPAH in the control (130 +/- 23 ng g(-1)) was comparable to reported concentrations for the rural Great Plains. Perylene had a unique distribution pattern suggesting biological inputs. The main PAH contamination mechanisms were likely atmospheric deposition due to asphalt production at the 0- to 20-cm depth and past landfill operations at deeper depths. PMID:20176830

  8. Age chronosequence and landscape effects on the quality characteristics of reclaimed coal mine soils under forest and pasture based system in Mississippi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface coal mining leads to reclamation which uses materials favorable to plant growth; however, these materials may initially be low in organic C. It is important to study the soil organic C sequestration potential of reclaimed mine soils under different land use and management systems. Few studie...

  9. Response of bacterial pdo1, nah, and C12O genes to aged soil PAH pollution in a coke factory area.

    PubMed

    Han, Xue-Mei; Liu, Yu-Rong; Zheng, Yuan-Ming; Zhang, Xiao-Xia; He, Ji-Zheng

    2014-01-01

    Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) is threatening human health and environmental safety. Investigating the relative prevalence of different PAH-degrading genes in PAH-polluted soils and searching for potential bioindicators reflecting the impact of PAH pollution on microbial communities are useful for microbial monitoring, risk evaluation, and potential bioremediation of soils polluted by PAHs. In this study, three functional genes, pdo1, nah, and C12O, which might be involved in the degradation of PAHs from a coke factory, were investigated by real-time quantitative PCR (qPCR) and clone library approaches. The results showed that the pdo1 and C12O genes were more abundant than the nah gene in the soils. There was a significantly positive relationship between the nah or pdo1 gene abundances and PAH content, while there was no correlation between C12O gene abundance and PAH content. Analyses of clone libraries showed that all the pdo1 sequences were grouped into Mycobacterium, while all the nah sequences were classified into three groups: Pseudomonas, Comamonas, and Polaromonas. These results indicated that the abundances of nah and pdo1 genes were positively influenced by levels of PAHs in soil and could be potential microbial indicators reflecting the impact of soil PAH pollution and that Mycobacteria were one of the most prevalent PAHs degraders in these PAH-polluted soils. Principal component analysis (PCA) and correlation analyses between microbial parameters and environmental factors revealed that total carbon (TC), total nitrogen (TN), and dissolved organic carbon (DOC) had positive effects on the abundances of all PAH-degrading genes. It suggests that increasing TC, TN, and DOC inputs could be a useful way to remediate PAH-polluted soils. PMID:24777329

  10. Response of bacterial pdo1, nah, and C12O genes to aged soil PAH pollution in a coke factory area.

    PubMed

    Han, Xue-Mei; Liu, Yu-Rong; Zheng, Yuan-Ming; Zhang, Xiao-Xia; He, Ji-Zheng

    2014-01-01

    Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) is threatening human health and environmental safety. Investigating the relative prevalence of different PAH-degrading genes in PAH-polluted soils and searching for potential bioindicators reflecting the impact of PAH pollution on microbial communities are useful for microbial monitoring, risk evaluation, and potential bioremediation of soils polluted by PAHs. In this study, three functional genes, pdo1, nah, and C12O, which might be involved in the degradation of PAHs from a coke factory, were investigated by real-time quantitative PCR (qPCR) and clone library approaches. The results showed that the pdo1 and C12O genes were more abundant than the nah gene in the soils. There was a significantly positive relationship between the nah or pdo1 gene abundances and PAH content, while there was no correlation between C12O gene abundance and PAH content. Analyses of clone libraries showed that all the pdo1 sequences were grouped into Mycobacterium, while all the nah sequences were classified into three groups: Pseudomonas, Comamonas, and Polaromonas. These results indicated that the abundances of nah and pdo1 genes were positively influenced by levels of PAHs in soil and could be potential microbial indicators reflecting the impact of soil PAH pollution and that Mycobacteria were one of the most prevalent PAHs degraders in these PAH-polluted soils. Principal component analysis (PCA) and correlation analyses between microbial parameters and environmental factors revealed that total carbon (TC), total nitrogen (TN), and dissolved organic carbon (DOC) had positive effects on the abundances of all PAH-degrading genes. It suggests that increasing TC, TN, and DOC inputs could be a useful way to remediate PAH-polluted soils.

  11. Monitoring of contaminated toxic and heavy metals, from mine tailings through age accumulation, in soil and some wild plants at Southeast Egypt.

    PubMed

    Rashed, M N

    2010-06-15

    This study includes tailing from gold mine, at Allaqi Wadi Aswan, Egypt, used by incident Egyptian and after by some English companies. Tailings, soils and wild plants (Acia Raddiena and Aerva Javanica) were sampled and analysed for toxic metals (Hg, Cd, Pb and As) and associated heavy metals (Cr, Ag, Ni, Au, Mo, Zn, Mn and Cu) using ICP-MS, ICP-AES, CVAAS and FAAS techniques. The present work concerns the distribution and mobility of these metals from tailing to the surrounding soils and wild flora. The results reveal that Cr, Cu, Zn, Ni, Ag, Au, Mn, Hg, As, Ag, Au and Pb in soil decreased as faraway from the tailing, after then irregular trends as a result of input from surrounding rocks. Acia Raddiena plant accumulated As, Cd and Pb in higher levels than Aerva Javanica. Quantification of soil and plant pollution was studied using enrichment factors, contamination factor, pollution index and bioaccumulation factors and show good interpretations of the results. The overall results of this study show that the soil and plants near the gold mine tailing were highly toxic, and the plants and soil must not be uses for grazing or agriculture.

  12. Monitoring of contaminated toxic and heavy metals, from mine tailings through age accumulation, in soil and some wild plants at Southeast Egypt.

    PubMed

    Rashed, M N

    2010-06-15

    This study includes tailing from gold mine, at Allaqi Wadi Aswan, Egypt, used by incident Egyptian and after by some English companies. Tailings, soils and wild plants (Acia Raddiena and Aerva Javanica) were sampled and analysed for toxic metals (Hg, Cd, Pb and As) and associated heavy metals (Cr, Ag, Ni, Au, Mo, Zn, Mn and Cu) using ICP-MS, ICP-AES, CVAAS and FAAS techniques. The present work concerns the distribution and mobility of these metals from tailing to the surrounding soils and wild flora. The results reveal that Cr, Cu, Zn, Ni, Ag, Au, Mn, Hg, As, Ag, Au and Pb in soil decreased as faraway from the tailing, after then irregular trends as a result of input from surrounding rocks. Acia Raddiena plant accumulated As, Cd and Pb in higher levels than Aerva Javanica. Quantification of soil and plant pollution was studied using enrichment factors, contamination factor, pollution index and bioaccumulation factors and show good interpretations of the results. The overall results of this study show that the soil and plants near the gold mine tailing were highly toxic, and the plants and soil must not be uses for grazing or agriculture. PMID:20188467

  13. Distribution of P, K, Ca, Mg, Cd, Cu, Fe, Mn, Pb and Zn in wood and bark age classes of willows and poplars used for phytoextraction on soils contaminated by risk elements.

    PubMed

    Zárubová, Pavla; Hejcman, Michal; Vondráčková, Stanislava; Mrnka, Libor; Száková, Jiřina; Tlustoš, Pavel

    2015-12-01

    Fast-growing clones of Salix and Populus have been studied for remediation of soils contaminated by risk elements (RE) using short-rotation coppice plantations. Our aim was to assess biomass yield and distributions of elements in wood and bark of highly productive willow (S1--[Salix schwerinii × Salix viminalis] × S. viminalis, S2--Salix × smithiana clone S-218) and poplar (P1--Populus maximowiczii × Populus nigra, P2--P. nigra) clones with respect to aging. The field experiment was established in April 2008 on moderately Cd-, Pb- and Zn- contaminated soil. Shoots were harvested after four seasons (February 2012) and separated into annual classes of wood and bark. All tested clones grew on contaminated soils, with highest biomass production and lowest mortality exhibited by P1 and S2. Concentrations of elements, with exception of Ca and Pb, decreased with age and were higher in bark than in wood. The Salix clones were characterised by higher removal of Cd, Mn and Zn compared to the Populus clones. Despite generally higher RE content in young shoots, partly due to lower wood/bark ratios and higher RE concentrations in bark, the overall removal of RE was higher in older wood classes due to higher biomass yield. Thus, longer rotations seem to be more effective when phytoextraction strategy is considered. Of the four selected clones, S1 exhibited the best removal of Cd and Zn and is a good candidate for phytoextraction.

  14. Carbon and nitrogen status of litterfall, litter decomposition and soil in even-aged larch, red pine and rigitaeda pine plantations.

    PubMed

    Kim, Choonsig; Jeong, Jaeyeob; Cho, Hyun-Seo; Son, Yowhan

    2010-07-01

    The carbon (C) and nitrogen (N) status in forest ecosystems can change upon establishment of plantations because different tree species have different nutrient cycling mechanisms. This study was carried out to evaluate C and N status of litterfall, litter decomposition and soil in three adjacent plantations consisting of one deciduous (larch: Larix leptolepis) and two evergreen (red pine: Pinus densiflora; rigitaeda pine: P. rigida x P. taeda) species planted in the same year (1963). Both the pine plantations showed comparatively higher C input from needle litter but significantly lower N concentration and input than the larch plantation (P < 0.05). During the decomposition process, the deciduous larch needle litter showed low C concentration and C remaining in soil, but high N concentration and N remaining in soil compared to the two evergreen pine needle litters. However, the soil C and N concentration and their content at a soil depth of 0-10 cm were not affected significantly (P > 0.05) by the plantation type. These results demonstrate the existence of considerable variation in C and N status resulting from needle litter input and litter decomposition in these three plantations grown at sites with similar environmental conditions.

  15. Land use effects on microbial biomass C, ß-glucosidase and ß-glucosaminidase activities, and availability, storage, and age of organic C in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is scant information that describes the functioning of Vertisols in the tropics with regards to C and N storage capacity and turnover, distribution, and biological indicators of ecosystem health as affected by land-use. These soils play a significant role in the amounts of carbon (C) sequeste...

  16. Transformation and accumulation of PAH and bound residues in soil under extreme conditions - a risk assessment approach

    NASA Astrophysics Data System (ADS)

    Eschenbach, Annette

    2010-05-01

    The degradation of PAH in contaminated soil does not proceed completely in the majority of cases. However microorganisms which are able to degrade PAH are present in PAH-contaminated soils normally. A total degradation of PAH in contaminated soils is often limited by a lack of bioavailability, which results from a lack of mass transfer. The analytical depletion of contaminants in soil is not only based on degradation processes but also on a fixation or immobilization of the xenobiotic substances as stronger adsorbed to or bound residues in the soil matrix. These bound residues were verified by using 14C-labelled PAH in different soil samples. To evaluate the long term fate of theses PAH-residues the stability and transformation of 14C-labelled non-extractable PAH-residues was investigated in detail under different extreme ecological and climate conditions such as biological stress, freezing and thawing cycles, and chemical worst case conditions. The transformation and remobilization of non-extractable PAH-residues was observed in long-time experiments and was very limited in general (Eschenbach et al. 2001). Only small amounts of non extractable residues were transformed and converted to CO2 and thereby detoxified. However the treatment with a complexing agent led to an increase of extractable 14C-activity. In a further set of experiments the long term risk of a groundwater contamination was assessed. Therefore the elution rate of 14C-PAH was investigated by a routinely usable column test system. It was found that the PAH elution was not solely controlled by desorption processes. The extractable PAH concentrations and elution rates were affected by the mineralization and formation of bound residues as well. For the assessment of the maximum PAH release rate the soil material was treated by extreme and worst case conditions as well. The impact of the elution of bidestillated water, of repeated freeze-thaw cycles and a simulation of acidic rain was investigated. The

  17. Soil carbon dynamics

    NASA Astrophysics Data System (ADS)

    Trumbore, Susan; Barbosa de Camargo, Plínio

    The amount of organic carbon (C) stored in the upper meter of mineral soils in the Amazon Basin (˜40 Pg C) represents ˜3% of the estimated global store of soil carbon. Adding surface detrital C stocks and soil carbon deeper than 1 m can as much as quadruple this estimate. The potential for Amazon soil carbon to respond to changes in land use, climate, or atmospheric composition depends on the form and dynamics of soil carbon. Much (˜30% in the top ˜10 cm but >85% in soils to 1 m depth) of the carbon in mineral soils of the Oxisols and Ultisols that are the predominant soil types in the Amazon Basin is in forms that are strongly stabilized, with mean ages of centuries to thousands of years. Measurable changes in soil C stocks that accompany land use/land cover change occur in the upper meter of soil, although the presence of deep roots in forests systems drives an active C cycle at depths >1 m. Credible estimates of the potential for changes in Amazon soil C stocks with future land use and climate change are much smaller than predictions of aboveground biomass change. Soil organic matter influences fertility and other key soil properties, and thus is important independent of its role in the global C cycle. Most work on C dynamics is limited to upland soils, and more is needed to investigate C dynamics in poorly drained soils. Work is also needed to relate cycles of C with water, N, P, and other elements.

  18. Effect of oxidant dosage on integrated electrochemical remediation of contaminant mixtures in soils.

    PubMed

    Reddy, Krishna R; Karri, Madhusudhana R

    2008-07-01

    Many sites are contaminated with contaminant mixtures, commonly heavy metals and polycyclic aromatic hydrocarbons (PAHs), which pose a great challenge for remediation. The objective of this research was to investigate coupled Fenton-like oxidation and electrokinetic remediation of low permeability soils contaminated with both heavy metals and PAHs. This remediation process aims at simultaneous oxidation of organic contaminants and removal of heavy metals. Fenton's reagent, consisting of hydrogen peroxide (H(2)O(2)) and native iron catalyst, is utilized for chemical oxidation. Laboratory batch and electrokinetic experiments were performed on kaolin (a low permeability soil) spiked with nickel and phenanthrene each at a concentration of 500 mg/kg of dry soil to represent typical heavy metal and PAH contaminants found at contaminated sites. Experiments were conducted using H(2)O(2) solution in 5%, 10%, 20% and 30% concentrations and also using deionized (DI) water as control. For electrokinetic experiments, a voltage gradient of 1 VDC/cm was applied and H(2)O(2) solution was introduced at the anode for a total duration of four weeks. Batch tests showed that phenanthrene oxidation increases from 76% to 87% when the H(2)O(2) concentration increases from 5% to 30%. The electrokinetic experiments showed substantial electroosmotic flow in all the tests. Approximately one pore volume of flow was generated in the DI baseline test and about 1.2-1.6 pore volumes were generated in case of H(2)O(2) tests. Phenanthrene was partially oxidized in the H(2)O(2) tests and its removal from the soil was insignificant. Oxidation of phenanthrene increased with increasing concentration of H(2)O(2); a maximum of 56% oxidation was observed with 30% H(2)O(2). Nickel migrated from anode to cathode. This migration was more pronounced in the H(2)O(2) tests as compared to the DI baseline test. Nickel precipitated in all the tests near the cathode due to high pH conditions. These results emphasize

  19. Fine root biomass, necromass and chemistry during seven years of elevated aluminium concentrations in the soil solution of a middle-aged Picea abies stand.

    PubMed

    Eldhuset, Toril D; Lange, Holger; de Wit, Helene A

    2006-10-01

    Toxic effects of aluminium (Al) on Picea abies (L.) Karst. (Norway spruce) trees are well documented in laboratory-scale experiments, but field-based evidence is scarce. This paper presents results on fine root growth and chemistry from a field manipulation experiment in a P. abies stand that was 45 years old when the experiment started in 1996. Different amounts of dissolved aluminium were added as AlCl3 by means of periodic irrigation during the growing season in the period 1997-2002. Potentially toxic concentrations of Al in the soil solution were obtained. Fine roots were studied from direct cores (1996) and sequential root ingrowth cores (1999, 2001, 2002) in the mineral soil (0-40 cm). We tested two hypotheses: (1) elevated concentration of Al in the root zone leads to significant changes in root biomass, partitioning into fine, coarse, living or dead fractions, and distribution with depth; (2) elevated Al concentration leads to a noticeable uptake of Al and reduced uptake of Ca and Mg; this results in Ca and Mg depletion in roots. Hypothesis 1 was only marginally supported, as just a few significant treatment effects on biomass were found. Hypothesis 2 was supported in part; Al addition led to increased root concentrations of Al in 1999 and 2002 and reduced Mg/Al in 1999. Comparison of roots from subsequent root samplings showed a decrease in Al and S over time. The results illustrated that 7 years of elevated Al(tot) concentrations in the soil solution up to 200 microM are not likely to affect root growth. We also discuss possible improvements of the experimental approach.

  20. Characterization of ‘Aged’ Metolachlor Sorption in Soil Using an Accelerated Solvent Extraction (ASE) Technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorption interactions of pesticides with soil determine pesticide availability for transport and degradation in soil. Thus, knowing and understanding pesticide sorption, particularly in aged soils, is important in determining pesticide fate in soils. Sorption of pesticides is traditionally character...

  1. Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture.

    PubMed

    Locke, Anna M; Ort, Donald R

    2014-12-01

    Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K(leaf)), a measure of the leaf's water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K(leaf) would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g(s)) and leaf water potential (Ψ(leaf)) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K(leaf) was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K(leaf) were further correlated with decreases in g(s), although the relationship was not as strong as that with A. Separate experiments investigating the response of K(leaf) to drought demonstrated no acclimation of K(leaf) to drought conditions to protect against cavitation or loss of g(s) during drought and confirmed the effect of leaf age in K(leaf) observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K(leaf)becoming limiting to transpiration water flux. PMID:25281701

  2. Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture.

    PubMed

    Locke, Anna M; Ort, Donald R

    2014-12-01

    Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K(leaf)), a measure of the leaf's water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K(leaf) would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g(s)) and leaf water potential (Ψ(leaf)) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K(leaf) was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K(leaf) were further correlated with decreases in g(s), although the relationship was not as strong as that with A. Separate experiments investigating the response of K(leaf) to drought demonstrated no acclimation of K(leaf) to drought conditions to protect against cavitation or loss of g(s) during drought and confirmed the effect of leaf age in K(leaf) observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K(leaf)becoming limiting to transpiration water flux.

  3. Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture

    PubMed Central

    Locke, Anna M.; Ort, Donald R.

    2014-01-01

    Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K leaf), a measure of the leaf’s water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K leaf would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g s) and leaf water potential (Ψleaf) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K leaf was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K leaf were further correlated with decreases in g s, although the relationship was not as strong as that with A. Separate experiments investigating the response of K leaf to drought demonstrated no acclimation of K leaf to drought conditions to protect against cavitation or loss of g s during drought and confirmed the effect of leaf age in K leaf observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K leaf becoming limiting to transpiration water flux. PMID:25281701

  4. Gestational age

    MedlinePlus

    Fetal age - gestational age; Gestation; Neonatal gestational age; Newborn gestational age ... Gestational age can be determined before or after birth. Before birth, your health care provider will use ultrasound to ...

  5. Distribution of Endophytic Bacteria in Alopecurus aequalis Sobol and Oxalis corniculata L. from Soils Contaminated by Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Peng, Anping; Liu, Juan; Gao, Yanzheng; Chen, Zeyou

    2013-01-01

    The distributions of endophytic bacteria in Alopecurus aequalis Sobol and Oxalis corniculata L. grown in soils contaminated with different levels of polycyclic aromatic hydrocarbons (PAHs) were investigated with polymerase chain reaction followed by denaturing gradient gel electrophoresis technology (PCR-DGGE) and cultivation methods. Twelve types of PAHs, at concentrations varying from 0.16 to 180 mg·kg−1, were observed in the roots and shoots of the two plants. The total PAH concentrations in Alopecurus aequalis Sobol obtained from three different PAH-contaminated stations were 184, 197, and 304 mg·kg−1, and the total PAH concentrations in Oxalis corniculata L. were 251, 346, and 600 mg·kg−1, respectively. The PCR-DGGE results showed that the endophytic bacterial communities in the roots and shoots of the two plants were quite different, although most bacteria belonged to Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. A total of 68 endophytic bacterial strains were isolated from different tissues of the two plants and classified into three phyla: Firmicutes, Proteobacteria and Bacteroidetes. In both plants, Bacillus spp. and Pseudomonas spp. were the dominant cultivable populations. With an increase in the PAH pollution level, the diversity and distribution of endophytic bacteria in the two plants changed correspondingly, and the number of cultivable endophytic bacterial strains decreased rapidly. Testing of the isolated endophytic bacteria for tolerance to each type of PAH showed that most isolates could grow well on Luria-Bertani media in the presence of different PAHs, and some isolates were able to grow rapidly on a mineral salt medium with a single PAH as the sole carbon and energy source, indicating that these strains may have the potential to degrade PAHs in plants. This research provides the first insight into the characteristics of endophytic bacterial populations under different PAH pollution levels and provides a species

  6. Novel Application of Cyclolipopeptide Amphisin: Feasibility Study as Additive to Remediate Polycyclic Aromatic Hydrocarbon (PAH) Contaminated Sediments

    PubMed Central

    Groboillot, Anne; Portet-Koltalo, Florence; Le Derf, Franck; Feuilloley, Marc J. G.; Orange, Nicole; Poc, Cécile Duclairoir

    2011-01-01

    To decontaminate dredged harbor sediments by bioremediation or electromigration processes, adding biosurfactants could enhance the bioavailability or mobility of contaminants in an aqueous phase. Pure amphisin from Pseudomonas fluorescens DSS73 displays increased effectiveness in releasing polycyclic aromatic hydrocarbons (PAHs) strongly adsorbed to sediments when compared to a synthetic anionic surfactant. Amphisin production by the bacteria in the natural environment was also considered. DSS73’s growth is weakened by three model PAHs above saturation, but amphisin is still produced. Estuarine water feeding the dredged material disposal site of a Norman harbor (France) allows both P. fluorescens DSS73 growth and amphisin production. PMID:21673923

  7. GENETIC STRUCTURE OF FUNDULUS HETEROCLITUS FROM PAH-CONTAMINATED AND NEIGHBORING SITES IN THE ELIZABETH AND YORK RIVERS. (R826593)

    EPA Science Inventory

    Abstract

    Population genetic characteristics of mummichog, Fundulus heteroclitus, from the heavily industrialized Elizabeth River and nearby York River (Virginia USA) were assessed relative to sediment PAH concentrations. Allozyme genotype frequencies for all loc...

  8. Weighing the evidence of ecological risk from PAHs contamination in the estuarine environment of Salina Cruz Bay, México.

    PubMed

    Salazar-Coria, L; Schifter, I; González-Macías, C

    2010-03-01

    Results of bulk-phase chemical measurements, toxicological tests combined with bioaccumulation measures in fishes, were used to evaluate the toxicity of the 16 USEPA priority polycyclic aromatic hydrocarbons from the sediment collected from eight stations of the Ventosa Estuarine System, located close to the main center of processing oil in the Mexican Pacific coast. Levels of the sum of polycyclic aromatic hydrocarbons varied from 22 to 6,850 microg kg(-1) dry weight. Based on sediment quality guidelines, the compounds with high environmental priority were acenaphtylene, acenaphtene, and phenanthrene. Acute toxicity tests with Vibrio fischeri and Daphnia magna as well as chronic toxicity with Panagrellus redivivus were performed. The quantification of hepatic ethoxyresorufin O-deethylase activity was used to assess the induction of the mixed function oxygenase system of brown trout. However, because it is often difficult to blend the results from such very different assays into a unified decision about the potential for impacts, a weight-of-evidence (WOE) approach to sediment quality investigations was followed. These assays provided measurement endpoints that could be used to develop an overall evaluation of the potential for environmental impacts from the oil processing operations. WOE provides a valuable tool for assessing the results of environmental investigations because it provides a framework for considering the strengths and weaknesses of environmental measurements, an approach for addressing uncertainty in the measurements, and documentation of the evaluation and its assumptions.

  9. Integrated assessment of PAH contamination in the Czech Rivers using a combination of chemical and biological monitoring.

    PubMed

    Blahova, Jana; Divisova, Lenka; Kodes, Vit; Leontovycova, Drahomira; Mach, Samuel; Ocelka, Tomas; Svobodova, Zdenka

    2014-01-01

    This study investigated polycyclic aromatic hydrocarbons (PAH) pollution of selected rivers in the Czech Republic. Integrated evaluation was carried out using combination of chemical and biological monitoring, in which we measured content of 1-hydroxypyrene (1-OHP) in chub bile and priority PAH in water samples obtained by exposing the semipermeable membrane devices at each location. The concentrations of 1-OHP in bile samples and sum of priority PAH in water sampler ranged from 6.8 ng mg protein(-1) to 106.6 ng mg protein(-1) and from 5.2 ng L(-1) to 173.9 ng L(-1), respectively. The highest levels of biliary metabolite and PAH in water were measured at the Odra River (the Bohumín site), which is located in relatively heavily industrialized and polluted region. Statistically significant positive correlation between biliary 1-OHP and sum of PAH in water was also obtained (P < 0.01, r s = 0.806).

  10. Combined column and cell flotation process for the treatment of PAH contaminated hazardous wastes produced by an aluminium production plant.

    PubMed

    Dhenain, Aurélie; Mercier, Guy; Blais, Jean-François; Chartier, Myriam

    2009-06-15

    The aluminium electrolytic plants generate PAH and fluoride contaminated wastes which are usually classified as hazardous material. These residues are generally disposed in secure landfill sites. A flotation cell process was previously developed to remove PAH from these aluminium industry wastes. The tests were done on composite samples made of particle size fractions under 50mm. The efficiency of the flotation cell process was demonstrated but the high quantity of concentrate produced (14.0%) during the air injection period, because of the solid entrainment, raised the treatment cost. The aim of this study was to reduce the entrainment of fine particles in order to obtain an efficient and economic technology. The process initially developed was modified: the smallest particle size fraction (<0.5mm) of the composite sample was treated in a flotation column, whereas the other particle size fractions (0.5-50mm) were treated in a flotation cell. The separated treatment allowed to reduce the entrainment during the air injection period of the flotation cell step from 14.0% to 10.1%. The optimum total solids of the pulp and cocamidopropylhydroxysultaine (CAS) concentration were 3.33% and 0.50% (ww(-1)) for the flotation column, and 15% and 0.25% (ww(-1)) for the flotation cell. This combined flotation process minimized the total entrainment which allowed a 23.6% abatement of the concentrate quantity initially produced, and reduced the PAH concentrations of the wastes under the authorized limit of 1000 mg kg(-1).

  11. REFERENCE VALUES FOR FISH EXPOSURE TO PAH CONTAMINANTS: COMPARISON OF OHIO AND THE MID-ATLANTIC REGION

    EPA Science Inventory

    Reference values for exposure of wildlife to contaminants are needed to cost effectively determine if a site is contaminated and to rank sites that are above background levels. Epidemiological techniques originally developed for clinical chemistry and for determining exposures t...

  12. Water quality concerns due to forest fires: polycyclic aromatic hydrocarbons (PAH) contamination of groundwater from mountain areas.

    PubMed

    Mansilha, C; Carvalho, A; Guimarães, P; Espinha Marques, J

    2014-01-01

    Water quality alterations due to forest fires may considerably affect aquatic organisms and water resources. These impacts are cumulative as a result of pollutants mobilized from fires, chemicals used to fight fire, and postfire responses. Few studies have examined postfire transport into water resources of trace elements, including the polycyclic aromatic hydrocarbons (PAH), which are organic pollutants produced during combustion and are considered carcinogenic and harmful to humans. PAH are also known to adversely affect survival, growth, and reproduction of many aquatic species. This study assessed the effects of forest wildfires on groundwater from two mountain regions located in protected areas from north and central Portugal. Two campaigns to collect water samples were performed in order to measure PAH levels. Fifteen of 16 studied PAH were found in groundwater samples collected at burned areas, most of them at concentrations significantly higher than those found in control regions, indicating aquifer contamination. The total sum of PAH in burned areas ranged from 23.1to 95.1 ng/L with a median of 62.9 ng/L, which is one- to sixfold higher than the average level measured in controls (16.2 ng/L). In addition, in control samples, the levels of light PAH with two to four rings were at higher levels than heavy PAH with five or six rings, thus showing a different profile between control and burned sites. The contribution of wildfires to groundwater contamination by PAH was demonstrated, enabling a reliable assessment of the impacts on water quality and preparation of scientifically based decision criteria for postfire forest management practices.

  13. Water quality concerns due to forest fires: polycyclic aromatic hydrocarbons (PAH) contamination of groundwater from mountain areas.

    PubMed

    Mansilha, C; Carvalho, A; Guimarães, P; Espinha Marques, J

    2014-01-01

    Water quality alterations due to forest fires may considerably affect aquatic organisms and water resources. These impacts are cumulative as a result of pollutants mobilized from fires, chemicals used to fight fire, and postfire responses. Few studies have examined postfire transport into water resources of trace elements, including the polycyclic aromatic hydrocarbons (PAH), which are organic pollutants produced during combustion and are considered carcinogenic and harmful to humans. PAH are also known to adversely affect survival, growth, and reproduction of many aquatic species. This study assessed the effects of forest wildfires on groundwater from two mountain regions located in protected areas from north and central Portugal. Two campaigns to collect water samples were performed in order to measure PAH levels. Fifteen of 16 studied PAH were found in groundwater samples collected at burned areas, most of them at concentrations significantly higher than those found in control regions, indicating aquifer contamination. The total sum of PAH in burned areas ranged from 23.1to 95.1 ng/L with a median of 62.9 ng/L, which is one- to sixfold higher than the average level measured in controls (16.2 ng/L). In addition, in control samples, the levels of light PAH with two to four rings were at higher levels than heavy PAH with five or six rings, thus showing a different profile between control and burned sites. The contribution of wildfires to groundwater contamination by PAH was demonstrated, enabling a reliable assessment of the impacts on water quality and preparation of scientifically based decision criteria for postfire forest management practices. PMID:25072713

  14. CHRONIC LABORATORY EXPOSURE OF MUMMICHOG, FUNDULUS HETEROCLITUS, TO PAH-CONTAMINATED SEDIMENT AND DIET CAUSES LIVER NEOPLASMS

    EPA Science Inventory

    The mummichog, Fundulus heteroclitus, is a common estuarine teleost inhabiting tidal marshes of the eastern United States. We previoiusly reported on high prevalences of hepatic and extra-hepatic neoplasms in populations of this species from chemically contaminated environments ...

  15. Spatial Patterns of bphA Gene Diversity Reveal Local Adaptation of Microbial Communities to PCB and PAH Contaminants.

    PubMed

    Hoostal, Matthew J; Bouzat, Juan L

    2016-10-01

    Biphenyl dioxygenases, encoded by the bphA gene, initiate the oxidation of polychlorinated biphenyls (PCBs) and specify the substrate range of PCB congeners metabolized by bacteria. Increased bphA gene diversity within microbial communities may allow a broader range of PCB congeners to be catabolized, thus resulting in greater PCB degradation. To assess the role of PCBs in modulating bphA gene diversity, 16S ribosomal RNA (rRNA) gene and bphA environmental DNA libraries were generated from bacterial communities in sediments with a steep gradient of PCB contamination. Multiple measures of sequence diversity revealed greater heterogeneity of bphA sequences in polluted compared to unpolluted locations. Codon-based signatures of selection in bphA sequences provided evidence of purifying selection. Unifrac analysis of 16S rRNA sequences revealed independent taxonomic lineages from polluted and unpolluted locations, consistent with the presence of locally adapted bacterial communities. Phylogenetic analysis of bphA sequences indicated that dioxygenases from sediments were closely related to previously characterized dioxygenases that metabolize PCBs and polynuclear aromatic hydrocarbons (PAHs), consistent with high levels of these contaminants within the studied sediments. Structural analyses indicated that the BphA protein of Rhodococcus jostii, capable of metabolizing both PCBs and PAHs, provided a more optimal modeling template for bphA sequences reported in this study than a BphA homologue with more restricted substrate specificity. Results from this study suggest that PCBs and PAHs may drive local adaptation of microbial communities by acting as strong selective agents for biphenyl dioxygenases capable of metabolizing a wide range of congeners.

  16. Integrated Assessment of PAH Contamination in the Czech Rivers Using a Combination of Chemical and Biological Monitoring

    PubMed Central

    Blahova, Jana; Divisova, Lenka; Kodes, Vit; Leontovycova, Drahomira; Mach, Samuel; Ocelka, Tomas; Svobodova, Zdenka

    2014-01-01

    This study investigated polycyclic aromatic hydrocarbons (PAH) pollution of selected rivers in the Czech Republic. Integrated evaluation was carried out using combination of chemical and biological monitoring, in which we measured content of 1-hydroxypyrene (1-OHP) in chub bile and priority PAH in water samples obtained by exposing the semipermeable membrane devices at each location. The concentrations of 1-OHP in bile samples and sum of priority PAH in water sampler ranged from 6.8 ng mg protein−1 to 106.6 ng mg protein−1 and from 5.2 ng L−1 to 173.9 ng L−1, respectively. The highest levels of biliary metabolite and PAH in water were measured at the Odra River (the Bohumín site), which is located in relatively heavily industrialized and polluted region. Statistically significant positive correlation between biliary 1-OHP and sum of PAH in water was also obtained (P < 0.01, rs = 0.806). PMID:24616653

  17. FINAL REPORT: Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbent Aging on Contaminant Speciation and Mobility

    SciTech Connect

    Mueller, Karl T; Chorover, John C; ODay, Peggy A; Um, Wooyong; Steefel, Carl I

    2009-10-05

    This project aimed for a predictive-mechanistic understanding of the coupling between mineral weathering and contaminant (Cs, Sr, I) transport/fate in caustic waste-impacted sediments. Based on our prior studies of model clay mineral systems, we postulated that contaminant uptake to Hanford sediments would reflect concurrent adsorption and co-precipitation effects. Our specific objectives were: (1) to assess the molecular-scale mechanisms responsible for time-dependent sequestration of contaminants (Cs, Sr and I) during penetration of waste-induced weathering fronts; (2) to determine the rate and extent of contaminant release from the sorbed state; (3) to develop a reactive transport model based on molecular mechanisms and macroscopic flow experiments [(1) and (2)] that simulates adsorption, aging, and desorption dynamics. Progress toward achieving each of these objectives is discussed in this Final Report.

  18. Amelioration of soil PAH and heavy metals by combined application of fly ash and biochar

    NASA Astrophysics Data System (ADS)

    Masto, Reginald; George, Joshy; Ansari, Md; Ram, Lal

    2016-04-01

    Generation of electricity through coal combustion produces huge quantities of fly ash. Sustainable disposal and utilization of these fly ash is a major challenge. Fly ash along with other amendments like biochar could be used for amelioration of soil. In this study, fly ash and biochar were used together for amelioration of polycyclic aromatic hydrocarbon (PAH) contaminated soil. Field experiment was conducted to investigate the effects of fly ash and biochar on the amelioration of soil PAH, and the yield of Zea mays. The treatments were control, biochar (4 t/ha), fly ash (4 t/ha), ash + biochar ( 2 + 2 t/ha). Soil samples were collected after the harvest of maize crop and analysed for chemical and biological parameters. Thirteen PAHs were analysed in the postharvest soil samples. Soil PAHs were extracted in a microwave oven at 120 °C using hexane : acetone (1:1) mixture. The extracted solutions were concentrated, cleaned and the 13 PAHs [Acenaphthene (Ace), fluorene (Flr), phenanthrene (Phn), anthracene(Ant), pyrene(Pyr), benz(a)anthracene (BaA), chrysene (Chy), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene, benzo(g,h,i)perylene (BghiP), dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene)(Inp)] were analysed using GC-MS. The mean pH increased from 6.09 in control to 6.64 and 6.58 at biochar and fly ash treated soils, respectively. N content was not affected, whereas addition of biochar alone and in combination with fly ash, has significantly increased the soil organic carbon content. P content was almost double in combined (9.06 mg/kg) treatment as compared to control (4.32 mg/kg). The increase in K due to biochar was 118%, whereas char + ash increased soil K by 64%. Soil heavy metals were decreased: Zn (-48.4%), Ni (-41.4%), Co (-36.9%), Cu (-35.7%), Mn (-34.3%), Cd (-33.2%), and Pb (-30.4%). Soil dehydrogenase activity was significantly increased by ash and biochar treatments and the maximum activity was observed for the combined

  19. Amelioration of soil PAH and heavy metals by combined application of fly ash and biochar

    NASA Astrophysics Data System (ADS)

    Masto, Reginald; George, Joshy; Ansari, Md; Ram, Lal

    2016-04-01

    Generation of electricity through coal combustion produces huge quantities of fly ash. Sustainable disposal and utilization of these fly ash is a major challenge. Fly ash along with other amendments like biochar could be used for amelioration of soil. In this study, fly ash and biochar were used together for amelioration of polycyclic aromatic hydrocarbon (PAH) contaminated soil. Field experiment was conducted to investigate the effects of fly ash and biochar on the amelioration of soil PAH, and the yield of Zea mays. The treatments were control, biochar (4 t/ha), fly ash (4 t/ha), ash + biochar ( 2 + 2 t/ha). Soil samples were collected after the harvest of maize crop and analysed for chemical and biological parameters. Thirteen PAHs were analysed in the postharvest soil samples. Soil PAHs were extracted in a microwave oven at 120 °C using hexane : acetone (1:1) mixture. The extracted solutions were concentrated, cleaned and the 13 PAHs [Acenaphthene (Ace), fluorene (Flr), phenanthrene (Phn), anthracene(Ant), pyrene(Pyr), benz(a)anthracene (BaA), chrysene (Chy), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene, benzo(g,h,i)perylene (BghiP), dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene)(Inp)] were analysed using GC-MS. The mean pH increased from 6.09 in control to 6.64 and 6.58