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Результаты 1231-1240 из 3,243
Tree Growth and Climate Relationship: Dynamics of Scots Pine (Pinus Sylvestris L.) Growing in the Near-Source Region of the Combined Heat and Power Plant During the Development of the Pro-Ecological Strategy in Poland
2015
Since the 1990s, the emission of pollutants was reduced in a majority of Polish and developing country factories whereas the level of energy production was similar to that prior to the 1990s. The conifer investigated in this study has grown for many years under the stress of industrial pollution. Despite this, the trees are preserved, to a large extent, sensitive to the natural climatic factors. We present a complex analysis of the climatic (sunshine, temperature, precipitation, humidity, and wind circulation) and anthropogenic factors influencing the radial increment dynamics of Scots pine (Pinus sylvestris L.) growing in the vicinity of the combined heat and power station in Łaziska (Poland). We analyzed the spatiotemporal distribution of growth reductions, the depth of reduction with respect to the distance from the emitter, the relationship between tree growth and climate during the industry development period and during proecological strategy application . Samples of carbon isotopic composition in pine needles from 2012 to 2013 were additionally determined. Pines series of 3 positions indicate that they have a similar sensitivity to most climatic elements of the previous and given year, but there is also a different rhythm between the studied populations of incremental growth of pines. The causes of diversity are due to the different types of habitat (site types) and industrial pollution. The variation in carbon stable isotopic composition in pine needles was connected with an increase of CO₂.
Показать больше [+] Меньше [-]Arsenic Removal and Transformation by Pseudomonas sp. Strain GE-1-Induced Ferrihydrite: Co-precipitation Versus Adsorption
2015
Xiu, Wei | Guo, Huaming | Liu, Qiong | Liu, Zeyun | Zou, Yan’e | Zhang, Baogang
Hundreds of millions of people are at risk from drinking arsenic (As)-contaminated groundwater in the world, making As removal from aquatic systems of utmost importance. However, characteristics of As removal by bacteria-induced ferrihydrite and coupled with redox processes are still not clear. Two-line ferrihydrite was formed in the presence of aerobic Fe(II)-oxidizing bacterium, Pseudomonas sp. strain GE-1. Arsenic co-precipitation with and adsorption onto ferrihydrite induced by Pseudomonas sp. strain GE-1 and redox processes of As were investigated. Results demonstrated that co-precipitation performed better in As(V) removal than As(III) removal, while adsorption showed higher capacity for As(III) removal. X-ray absorption near-edge spectroscopy (XANES) indicated that As(III) oxidation occurred in solid phases during co-precipitation and adsorption. Detection of As species in solution showed that As(V) was reduced to As(III) during co-precipitation, although no As(V) reduction occurred during adsorption. Arsenic immobilization by Pseudomonas sp. strain GE-1-induced ferrihydrite in the presence of the strains may be applied as an alternative remediation strategy.
Показать больше [+] Меньше [-]Effect of Swine Manure on Sulfamethazine Degradation in Aerobic and Anaerobic Soils
2015
Lertpaitoonpan, Warisara | Moorman, Thomas B. | Ong, Say Kee
Degradation and fate of sulfamethazine (SMZ) were determined under aerobic and anaerobic conditions in soil with and without swine manure amendment. For both aerobic and anaerobic conditions, SMZ disappeared rapidly during the first 7 days followed by slow disappearance which may indicate that SMZ had become more persistent and less available. For soils receiving 100 mg/kg of SMZ, the percent of SMZ remaining in the soil after 63 days were between 25 and 60 %. Depending on the initial SMZ concentration, estimated half-lives for aerobic and anaerobic incubations ranged from 1.2 to 6.6 and 2.3 days to more than 63 days, respectively. Addition of manure (0.054 g/g soil) did not significantly affect the half-lives of SMZ. Inhibitory effects of SMZ on anaerobic microbial respiration were observed in unamended soil at concentrations of 50 mg/kg or higher, but only transient inhibitory effects were found in aerobic soil. Five to 22 % of the¹⁴C[phenyl]-SMZ added were extracted at the end of the incubations while 70 to 91 % of the¹⁴C were converted to bound (non-extractable) forms in both manure amended and unamended soil. Only 0.1 to 1.5 % of¹⁴C-SMZ was mineralized to¹⁴CO₂. Disappearance of SMZ in sterilized soil was not completely halted indicating possible contribution of abiotic processes to the disappearance of SMZ in soil.
Показать больше [+] Меньше [-]Dynamic of sulphate-reducing microorganisms in petroleum-contaminated marine sediments inhabited by the polychaete Hediste diversicolor
2015
Stauffert, Magalie | Cravo-Laureau, Cristiana | Duran, Robert
The behaviour of sulphate-reducing microbial community was investigated at the oxic–anoxic interface (0–2 cm) of marine sediments when submitted to oil and enhanced bioturbation activities by the addition of Hediste diversicolor. Although total hydrocarbon removal was not improved by the addition of H. diversicolor, terminal restriction fragment length polymorphism (T-RFLP) analyses based on dsrAB (dissimilatory sulphite reductase) genes and transcripts showed different patterns according to the presence of H. diversicolor which favoured the abundance of dsrB genes during the early stages of incubation. Complementary DNA (cDNA) dsrAB libraries revealed that in presence of H. diversicolor, most dsrAB sequences belonged to hydrocarbonoclastic Desulfobacteraceae, suggesting that sulphate-reducing microorganisms (SRMs) may play an active role in hydrocarbon biodegradation in sediments where the reworking activity is enhanced. Furthermore, the presence of dsrAB sequences related to sequences found associated to environments with high dinitrogen fixation activity suggested potential N₂ fixation by SRMs in bioturbated-polluted sediments.
Показать больше [+] Меньше [-]Biotransformation of Endocrine-Disrupting Compounds in Groundwater: Bisphenol A, Nonylphenol, Ethynylestradiol and Triclosan by a Laccase Cocktail from Pycnoporus sanguineus CS43
2015
Garcia-Morales, R. | Rodríguez-Delgado, M. | Gomez-Mariscal, K. | Orona-Navar, C. | Hernandez-Luna, C. | Torres, E. | Parra, R. | Cárdenas-Chávez, D. | Mahlknecht, J. | Ornelas-Soto, N.
The biodegradation of organic compounds present in water at trace concentration has become a critical environmental problem. In particular, enzymatic oxidation by fungal laccases offers a promising alternative for efficient and sustainable removal of organic pollutants in water. In this work, the biocatalytic ability of laccases from the Pycnoporus sanguineus CS43 fungus was evaluated. A filtered culture supernatant (laccase cocktail) evidenced an enhanced biotransformation capability to remove common endocrine-disruptor compounds (EDCs), such as bisphenol A, 4-nonylphenol, 17-α-ethynylestradiol and triclosan. A biodegradation of around 89–100 % was achieved for all EDCs using synthetic samples (10 mg L⁻¹) and after the enzymatic treatment with 100 U L⁻¹ (50.3 U mg ⁻¹). The biodegradation rates obtained were fitted to a first order reaction. Furthermore, enzymatic biocatalytic activity was also evaluated in groundwater samples coming from northwestern Mexico, reaching biotransformation percentages between 55 and 93 % for all tested compounds. As far as we know this is the first study on real groundwater samples in which the enzymatic degradation of target EDCs by a laccase cocktail from any strain of Pycnoporus sanguineus was evaluated. In comparison with purified laccases, the use of cocktail offers operational advantages since additional purification steps can be avoided.
Показать больше [+] Меньше [-]Fluoroquinolone Antibacterial Agent Contaminants in Soil/Groundwater: A Literature Review of Sources, Fate, and Occurrence
2015
Chen, Guoli | Li, Miao | Liu, Xiang
Fluoroquinolone antibacterial agents (FQs) are the most commonly detected antibiotics in soil/groundwater which cause chronic effects on human beings as well as aquatic ecosystems. The current situation of the regulation, occurrence, fate, and sources of FQs in soil/groundwater was systematically analyzed in this paper. And then, the important factors affecting milligram per liter concentration of FQs sorption in soil, such as pH, cation exchange, clay minerals, organic content, surface complexation, and microbial degradation or transformation, were summarized. Actually, nanogram-microgram per liter concentration is detected frequently in soil/groundwater by far. Due to the extensive application of FQs and its relatively stable physicochemical characteristics, the higher concentration in soil/groundwater would appear in the coming decades which may exert a threat to freshwater and human beings. To the knowledge of the authors, no full-scale fate, occurrence, spatial, and temporal variations of FQs in soil/groundwater have been reported in the scientific literature. Therefore, it is recommended that more comprehensive studies are required to fill knowledge gaps in low-concentration transport, fate and occurrence, spatial, and temporal variations of FQs in soil/groundwater and their potential risk assessment to human and ecosystem.
Показать больше [+] Меньше [-]Effects of Nano-maghemite on Trace Element Accumulation and Drought Response of Helianthus annuus L. in a Contaminated Mine Soil
2015
Martínez-Fernández, Domingo | Vítková, Martina | Bernal, M Pilar | Komárek, Michael
Although recent studies show that the iron oxides do not enter or accumulate in plants, they may preclude the transport of water and nutrients in the plants through/as a consequence of their aggregation on the surface of the roots. The feasibility of using iron oxide nanoparticles to modify the availability of trace elements (TEs) to Helianthus annuus in the soil as well as their interference with the plant response during an imposed water deficiency stress were studied in a pot experiment. Plants were grown in a compost pre-amended contaminated soil with and without nano-maghemite (NM) and later exposed to drought. The nano-amendment promoted the growth of H. annuus (higher (25 %) dry weight than in the same soil without NM), mainly due to the insolubilisation of pore water Zn in the soil and the consequent reduction of its availability to the plants. During the water stress, NM did not cause an increase in the accumulation of proline or total amino acids in the plants, which are normally used as drought stress indicators, compared to the control plants without NM. In conclusion, NM could be useful soil amendments during phytoremediation procedures, since it can immobilise TEs in the soil without disrupting the plant water balance.
Показать больше [+] Меньше [-]Removal of Fluoride from Contaminated Water Using Natural Calcium-Rich Attapulgite as a Low-Cost Adsorbent
2015
Yin, Hongbin | Kong, Ming | Tang, Wanying
In this study, natural calcium-rich attapulgite (NCAP) was used to develop a low-cost adsorbent for removing fluoride (F⁻) from contaminated water. The results showed that calcination can dramatically increase the F⁻ sorption capacity of NCAP and that the maximum F⁻ sorption capacity occurred at 700 °C. The sorption of F⁻ on NCAP heated at 700 °C (NCAP700) followed pseudo-second-order kinetics and was described by the Langmuir equilibrium model. The estimated F⁻ sorption capacity was approximately 140.0 mg/g at pH 8.0, which was comparable with the sorption capacities of some nanomaterials. The sorption of F⁻ on NCAP700 performed well at pH values of 7 to 10. In addition, anions such as NO₃ ⁻ and SO₄ ²⁻ did not affect fluoride removal, but PO₄ ³⁻ and HCO₃ ⁻ moderately influenced fluoride removal. A column study conducted using NCAP700 with a particle size of 0.2–0.5 mm indicated that the adsorbent could effectively purify nearly 200 bed volumes (BV) of water containing 3.0 mg F/l at pH 8.5. The removal of F⁻ from water mainly resulted from the formation of calcium fluoride precipitates and the complexation of fluoride with the –OH group of NCAP700, which was further confirmed by scanning electron microscopy–energy dispersive spectrometry (SEM-EDS) and X-ray photoelectron spectroscopy (XPS).
Показать больше [+] Меньше [-]Degradation of p-Nitrophenol in Soil by Dielectric Barrier Discharge Plasma
2015
Li, Rui | Liu, Yanan | Sun, Yu | Zhang, Wenjuan | Mu, Ruiwen | Li, Xiang | Chen, Hong | Gao, Pin | Xue, Gang | Ognier, Stephanie
Dielectric barrier discharges (DBDs) were utilized for the remediation of soil contaminated with p-nitrophenol (PNP). The effect of treatment time, applied discharge voltage, initial PNP concentration, pH of contaminated soil, and airflow rate were investigated in this study. The results showed that 63.2 % of the PNP in the contaminated soil was degraded in 50 min with a voltage of 38.2 kV with no airflow. This degradation reaction followed the first order reaction kinetics. The degradation by ozone alone was compared with the plasma treatment to identify the role of ozone. Chromatographic analysis was applied to monitor the intermediates produced during the oxidation process, and the main byproducts were maleic acid, p-benzoquinone, 4-nitrocatechol, methanoic acid, acetic acid, oxalic acid, NO₂ ⁻, and NO₃ ⁻. Possible pathways for the degradation of PNP in this system were deduced, which would provide evidence for the researches about the remediation of soils polluted by organic pollutants.
Показать больше [+] Меньше [-]Assessment of the Responsiveness to Different Stresses of the Microbial Community from Long-Term Hydrocarbon-Contaminated Soils
2015
Pessacq, Jorge | Medina, Rocio | Terada, Claudia | Bianchini, Flavia E. | Morelli, Irma S. | Del Panno, María T.
Soils exposed to long-term contamination with hydrocarbons may present extreme challenges to maintain the biological resilience to the stress. To elucidate the relationships between the initial event of contamination and the responsiveness to the stress, we investigated the extent of the microbial resilience of biological functions from two contaminated soils sampled from a petrochemical area (S1, underwent diffuse hydrocarbon contamination, and S2, from a land farming unit where an alkaline petrochemical sludge was treated) after the Cd, saline, and acid stresses. Both contaminated soils were characterized by low organic matter content compared with a pristine soil. Although similar Shannon diversity index and heterotrophic bacterial count were observed, different bacterial community structures (PCR-DGGE) and less enzymatic activities characterized the contaminated soils. Particularly, functional diversity determined by Biolog EcoPlates™ was not detected in S2 soil. Only the S1 soil showed resilience of the enzymatic activities and functional diversity, suggesting the presence of a well-adapted microbial community able to face with the stresses. The S2 was the most disturbed and less responsive soil. However, an increase in the functional diversity was evidenced after acidification, and it is possible to correlate this responsiveness with the sludge properties treated in the land farming unit. In addition, if the selected stress can reverse the soil condition provoked for the first disturbance, responsiveness could be expected.
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