Refine search
Results 1691-1700 of 2,503
Inoculation with arbuscular mycorrhizal fungi and addition of composted olive-mill waste enhance plant establishment and soil properties in the regeneration of a heavy metal-polluted environment
2014
Curaqueo, Gustavo | Schoebitz, Mauricio | Borie B., Fernando | Caravaca, Fuensanta | Roldán, Antonio
A greenhouse experiment was carried out in order to investigate the effects of arbuscular mycorrhizal (AM) fungi inoculation and the use of composted olive waste (COW) in the establishment of Tetraclinis articulata and soil properties in a heavy metal-polluted soil. The treatments assayed were as follows: AM + 0 % COW, AM + 1 % COW, and AM + 3 % COW. The higher doses of COW in combination with AM fungi increased shoot and root biomass production of T. articulata by 96 and 60 %, respectively. These treatments trended to improve the soil properties evaluated, highlighting the C compounds and N as well as the microbiological activities. In relation to the metal translocation in T. articulata, doses of COW applied decreased the Cr, Ni, and Pb contents in shoot, as well as Cr and As in root, although the most of them reached low levels and far from phytotoxic. The COW amendment aided Glomus mosseae-inoculated T. articulata plants to thrive in contaminated soil, mainly through an improvement in both nutrients uptake, mainly P and soil microbial function. In addition, the combined use of AM fungi plus COW could be a feasible strategy to be incorporated in phytoremediation programs because it promotes soil properties, a better performance of plants for supporting the stress in heavy metal-contaminated soils derived from the mining process, and also can be a good way for olive-mill waste disposal.
Show more [+] Less [-]The effect of structural compositions on the biosorption of phenanthrene and pyrene by tea leaf residue fractions as model biosorbents
2014
Xi, Zemin | Chen, Baoliang
To enhance the removal efficiency of polycyclic aromatic hydrocarbons (PAHs) by natural biosorbent, sorption of phenanthrene and pyrene onto raw and modified tea leaves as a model biomass were investigated. Tea leaves were treated using Soxhlet extraction, saponification, and acid hydrolysis to yield six fractions. The structures of tea leaf fractions were characterized by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The amorphous cellulose components regulated the sorption kinetics, capacity, and mechanism of biomass fractions. The adsorption kinetics fit well to pseudo-second-order model and isotherms followed the Freundlich equation. By the consumption of the amorphous cellulose under acid hydrolysis, both the aliphatic moieties and aromatic domains contributed to total sorption, thus sorption capacities of the de-sugared fractions were dramatically increased (5–20-fold for phenanthrene and 8–36-fold for pyrene). All de-sugared fractions exhibited non-linear sorption due to strong specific interaction between PAHs and exposed aromatic domains of biosorbent, while presenting a relative slow rate because of the condensed domain in de-sugared samples. The availability of strong sorption phases (aromatic domains) in the biomass fractions were controlled by polar polysaccharide components, which were supported by the FTIR, CHN, and SEM data.
Show more [+] Less [-]Assessment of 222Rn emanation from ore body and backfill tailings in low-grade underground uranium mine
2014
Mishra, Devi Prasad | Sahu, Patitapaban | Panigrahi, Durga Charan | Jha, Vivekanand | Patnaik, R Lokeswara
This paper presents a comparative study of²²²Rn emanation from the ore and backfill tailings in an underground uranium mine located at Jaduguda, India. The effects of surface area, porosity,²²⁶Ra and moisture contents on²²²Rn emanation rate were examined. The study revealed that the bulk porosity of backfill tailings is more than two orders of magnitude than that of the ore. The geometric mean radon emanation rates from the ore body and backfill tailings were found to be 10.01 × 10⁻³and 1.03 Bq m⁻² s⁻¹, respectively. Significant positive linear correlations between²²²Rn emanation rate and the²²⁶Ra content of ore and tailings were observed. For normalised²²⁶Ra content, the²²²Rn emanation rate from tailings was found to be 283 times higher than the ore due to higher bulk porosity and surface area. The relative radon emanation from the tailings with moisture fraction of 0.14 was found to be 2.4 times higher than the oven-dried tailings. The study suggested that the mill tailings used as a backfill material significantly contributes to radon emanation as compared to the ore body itself and the²²⁶Ra content and bulk porosity are the dominant factors for radon emanation into the mine atmosphere.
Show more [+] Less [-]Genotoxicity and histological alterations in grey mullet Mugil liza exposed to petroleum water-soluble fraction (PWSF)
2014
Moreira, Cauê Bonucci | Rodrigues, Ricardo Vieira | Romano, Luis Alberto | Gusmão, Emeline Pereira | Seyffert, Bianca Hartwig | Sampaio, Luís André | Miranda-Filho, Kleber Campos
Petroleum hydrocarbons are considered one of the main organic chemicals found in water bodies. In the present study, the median lethal concentration (LC₅₀) was estimated for mullet Mugil liza after acute exposure to petroleum water-soluble fraction (PWSF). Furthermore, histopathological studies and micronuclei frequency were also performed in order to observe deleterious effects of medium-term exposition to PWSF. Mullets (25 ± 2.3 g) were exposed to chronic concentrations (1.7, 3.5 and 7 % of PWSF), plus the control group, for 14 and 7 days of clearance time. Throughout the experimental period (1, 4, 14 and 21 days), blood samples were collected for analysis of micronucleus (MN) and liver and gills for histopathological study. For these procedures, seven fish were sampled per concentration tested. The LC₅₀-96 h was estimated at 37.5 % of the PWSF. The time required for MN induction was 96 h of exposure. The time of clearance was sufficient to achieve a MN frequency similar to that of the control group. Histopathological studies showed severe changes in the gill and liver tissues. The most relevant histopathology in the gills was telangiectasia. Hepatic histopathology such as cholestasis, dilated sinusoids and inflammatory infiltrates were commonly described. The MN test and histological study effectively detected damages caused by medium-term exposition to the PWSF, and despite the toxicity, a few days without exposure can minimize PWSF genotoxicity in juveniles of M. liza.
Show more [+] Less [-]Impact of anthropogenic activities on urban stream water quality: a case study in Guangzhou, China
2014
Liu, Jin-Song | Guo, Ling-Chuan | Luo, Xian-Lin | Chen, Fan-Rong | Zeng, E. Y. (Eddy Y.)
Anthropogenic activities are increasingly impacting the quality of urban surface water, particularly in regions undergoing intensive urbanization, such as Guangzhou of South China with a large urban stream network. To examine such impacts, we conducted field sampling on December 24, 2010, May 24, 2011, and August 28, 2011, representative of the low-, normal-, and high-flow periods, respectively. The first sampling was timed immediately after the closing of the 16th Asian Games (November 12–27, 2010) and the 10th Asian Para Games (December 12–19, 2010) held in Guangzhou. Assessments based on a pollution index method showed that the urban streams under investigation were extremely polluted, with direct discharge of untreated domestic sewage identified as the main pollution contributor. In addition, stream water quality around urban villages with high population densities was worse than that within business districts away from the urban villages. Pollution control measures implemented in preparation for the Asian Games were effective for urban streams within the business districts, but less effective for those adjacent to the urban villages. However, short-term efforts may not be able to achieve sustainable urban water quality improvements. In the case of Guangzhou, minimizing or even eliminating direct point-source inputs to the urban streams is perhaps the best option.
Show more [+] Less [-]Molecular and ultrastructural insights into the earthworm Eisenia fetida of the assessment of ecotoxicity during colistin exposure
2014
Guo, Ruizi | Ding, Xueyao | Zhong, Xiaoxia | Gao, Shangji | Sun, Yongxue
Colistin is a peptide antibiotic widely used as a feed additive in animal farming, especially in poultry and swine production, for treatment and prevention of gram-negative bacterial infections, as well as for growth promotion use. When orally ingested, colistin is poorly absorbed and is eliminated almost unaltered by the enteric canal into the environment. Thus, risk of environmental toxicity cannot be ignored. In the present study, we examined the effects of colistin on Heath Shock Protein (HSP) 70, metallothionein (MT) gene expressions, and the ultrastructure of intestinal cells, following treatment of the soil indicator earthworm Eisenia fetida with 10, 20, and 100 mg/kg colistin for 7, 14, and 21 days. The results showed that, compared with the control, the expressions of HSP70 and MT genes changed significantly. Colistin caused up-regulations of HSP70’s expression while inhibited the expression of MT gene. In addition, most mitochondria and endoplasmic reticulum were damaged in the group treated with high concentration. The investigation of gene expressions of HSP70 and MT, as well as pathological alterations in the intestinal cells, may provide important information in terms of ecotoxicity of colistin and can be used as early warning system.
Show more [+] Less [-]Application of HYDRUS 1D model for assessment of phenol–soil adsorption dynamics
2014
Pāl, Supriẏā | Mukherjee, Somnath | Ghosh, Sudipta
Laboratory-scale batch, vertical, and horizontal column experiments were conducted to investigate the attenuative capacity of a fine-grained clayey soil of local origin in the surrounding of a steel plant wastewater discharge site in West Bengal, India, for removal of phenol. Linear, Langmuir, and Freundlich isotherm plots from batch experimental data revealed that Freundlich isotherm model was reasonably fitted (R² = 0.94). The breakthrough column experiments were also carried out with different soil bed heights (5, 10, and 15 cm) under uniform flow to study the hydraulic movements of phenol by evaluating time concentration flow behavior using bromide as a tracer. The horizontal migration test was also conducted in the laboratory using adsorptive phenol and nonreactive bromide tracer to explore the movement of solute in a horizontal distance. The hydrodynamic dispersion coefficients (D) in the vertical and horizontal directions in the soil were estimated using nonlinear least-square parameter optimization method in CXTFIT model. In addition, the equilibrium convection dispersion model in HYDRUS 1D was also examined to simulate the fate and transport of phenol in vertical and horizontal directions using Freundlich isotherm constants and estimated hydrodynamic parameters as input in the model. The model efficacy and validation were examined through statistical parameters such as the coefficient of determination (R²), root mean square error and design of index (d).
Show more [+] Less [-]Acetamide hydrolyzing activity of Bacillus megaterium F-8 with bioremediation potential: Optimization of production and reaction conditions
2014
Sogani, Monika | Bakre, Prakash P. | Mathur, Nupur | Sharma, Pratibha | Bhatnagar, Pradeep
Bacillus megaterium F-8 exhibited an intracellular acetamide hydrolyzing activity (AHA) when cultivated in modified nutrient broth with 3 % tryptone, 1.5 % yeast extract, and 0.5 % sodium chloride, at pH 7.2, 45 °C for 24 h. Maximum AHA was recorded in the culture containing 0.1 M of sodium phosphate buffer, (pH 7.5) at 45 °C for 20 min with 0.2 % of acetonitrile and resting cells of B. megaterium F-8 equivalent to 0.2 ml culture broth. This activity was stable up to 55 °C and was completely inactivated at or above 60 °C. Maximum acyl transferase activity (ATA) was recorded in the reaction medium containing 0.1 M of potassium phosphate buffer, (pH 8.0) at 55 °C for 5 min with 0.85 mM of acetamide as acyl donor and hydroxylamine hydrochloride as acyl acceptor and resting cells of B. megaterium F-8 equivalent to 0.94 mg cells (dry weight basis). This activity was stable up to 60 °C and a rapid decline in enzyme activity was recorded above it. Under the optimized conditions, this organism hydrolyzed various nitriles and amides such as propionitrile, propionamide, caprolactam, acetamide, and acrylamide to corresponding acids. Acyl group transfer capability of this organism was used for the production of acetohydroxamic acid. ATA of B. megaterium F-8 showed broad substrate specificity such as for acetamide followed by propionamide, acrylamide, and lactamide. This amide hydrolyzing and amidotransferase activity of B. megaterium F-8 has potential applications in enzymatic synthesis of hydroxamic acids and bioremediation of nitriles and amides contaminated soil and water system.
Show more [+] Less [-]The evaluation of heavy metal accumulation and application of a comprehensive bio-concentration index for woody species on contaminated sites in Hunan, China
2014
Zhao, Xiulian | Liu, Jianfeng | Xia, Xinli | Chu, Ran | Wei, Yuan | Shi, Shengqing | Chang, Ermei | Yin, Weilun | Jiang, Zeping
Fast-growing metal-accumulating woody plants are considered potential candidates for phytoextraction of metals. Shuikoushan mining, one of the biggest Pb and Zn production bases in China, presents an important source of the pollution of environment during the last 100 years. Over 150 km²of fertile soil have been contaminated by the dust, slag, and tailings from this mining. The goal of the present work has been to determine the content of Pb, Zn, Cd, and Cu in wild woody plants (18 species) naturally growing in this area. Two hundred five plant and soil samples from 11 contaminated sites were collected and analyzed. In addition, to assess the ability of multi-metal accumulation of these trees, we proposed a predictive comprehensive bio-concentration index (CBCI) based on fuzzy synthetic assessment. Our data suggest some adult trees could also accumulate a large amount of metals. Pb concentrations in leaves of Paulownia fortunei (Seem.) Hemsl. (1,179 mg/kg) exceeded the hyperaccumulation threshold (1,000 mg/kg). Elevated Pb concentrations (973.38 mg/kg) were also found in the leaves of Broussonetia papyrifera (L.) Vent., with a Pb bio-concentration factor of up to 0.701. Endemic species, Zenia insignis Chun exhibited huge potential for Zn and Cd phytoextraction, with the highest concentrations of Zn (1,968 mg/kg) and Cd (44.40 mg/kg), characteristic root nodules, and fast growth rates in poor soils. As for multi-metal accumulation ability, native species B. papyrifera was calculated to have the most exceptional ability to accumulate various metals simultaneously (CBCI 2.93), followed by Amorpha fruticosa L. (CBCI 2.72) and Lagerstroemia indica L. (CBCI 2.53). A trend of increasing metal from trunks to leaves (trunks < branches < leaves) and towards fine roots has been shown by metal partitioning between tissues. The proposed CBCI would allow for the selection of suitable trees for phytoremediation in the future.
Show more [+] Less [-]Chronic dietary exposure to pyrolytic and petrogenic mixtures of PAHs causes physiological disruption in zebrafish - part I: Survival and growth
2014
Vignet, Caroline | Le Menach, Karyn | Mazurais, David | Lucas, Julie | Perrichon, Prescilla | Le Bihanic, Florane | Devier, Marie-Hélène | Lyphout, Laura | Frère, Laura | Bégout, Marie-Laure | Zambonino-Infante, José-Luis | Budzinski, Hélène | Cousin, Xavier
The release of polycyclic aromatic hydrocarbons (PAHs) into the environment has increased very substantially over the last decades leading to high concentrations in sediments of contaminated areas. To evaluate the consequences of long-term chronic exposure to PAHs, zebrafish were exposed, from their first meal at 5 days post fertilisation until they became reproducing adults, to diets spiked with three PAH fractions at three environmentally relevant concentrations with the medium concentration being in the range of 4.6–6.7 μg g⁻¹for total quantified PAHs including the 16 US-EPA indicator PAHs and alkylated derivatives. The fractions used were representative of PAHs of pyrolytic (PY) origin or of two different oils of differing compositions, a heavy fuel (HO) and a light crude oil (LO). Fish growth was inhibited by all PAH fractions and the effects were sex specific: as determined with 9-month-old adults, exposure to the highest PY inhibited growth of females; exposure to the highest HO and LO inhibited growth of males; also, the highest HO dramatically reduced survival. Morphological analysis indicated a disruption of jaw growth in larvae and malformations in adults. Intestinal and pancreatic enzyme activities were abnormal in 2-month-old exposed fish. These effects may contribute to poor growth. Finally, our results indicate that PAH mixtures of different compositions, representative of situations encountered in the wild, can promote lethal and sublethal effects which are likely to be detrimental for fish recruitment.
Show more [+] Less [-]