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结果 1511-1520 的 2,512
Integration of geophysical, geochemical and microbiological data for a comprehensive small-scale characterizationof an aged LNAPL-contaminated site 全文
2014
Arato, Alessandro | Wehrer, Markus | Biró, Borbala | Godio, Alberto
Characterization of aged hydrocarbon-contaminated sites is often a challenge due to the heterogeneity of subsurface conditions. Geoelectrical methods can aid in the characterization of such sites due to their non-invasive nature, but need to be supported by geochemical and microbiological data. In this study, a combination of respective methods was used to characterize an aged light non-aqueous phase liquid-contaminated site, which was the scene of a crude oil blow-out in 1994. As a consequence, a significant amount of crude oil was released into the subsurface. Complex resistivity has been acquired, both along single boreholes and in cross-hole configuration, in a two-borehole test site addressed with electrodes, to observe the electrical behaviour at the site over a two-year period (2010–2011). Geoelectrical response has been compared to results of the analysis of hydrocarbon contamination in soil and groundwater samples. Geochemical parameters of groundwater have been observed by collecting samples in a continuous multi-channel tubing (CMT) piezometer system. We have also performed a biological characterization on soil samples by drilling new boreholes close to the monitoring wells. Particular attention has been given to the characterization of the smear zone that is the sub-soil zone affected by the seasonal groundwater fluctuations. In the smear zone, trapped hydrocarbons were present, serving as organic substrate for chemical and biological degradation, as was indicated by an increase of microbial biomass and activity as well as ferrogenic-sulfidogenic conditions in the smear zone. The results show a good agreement between the intense electrical anomaly and the peaks of total organic matter and degradation by-products, particularly enhanced in the smear zone.
显示更多 [+] 显示较少 [-]Distribution, origin, and transformation of metal and metalloid pollution in vegetable fields, irrigation water, and aerosols near a Pb-Zn mine 全文
2014
Luo, Liqiang | Chu, Binbin | Liu, Ying | Wang, Xiaofang | Xu, Tao | Bo, Ying
Pollution of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) in vegetable fields was investigated near a Pb-Zn mine that has been exploited for over 50 years without a tailing reservoir. A total of 205 water, soil, and aerosol samples were taken and quantified by combined chemical, spectrometric, and mineral analytical methods. The pollution origins were identified by Pb isotopes and the pathways of transformation and transport of the elements and minerals was studied. The data showed that the vegetable fields were seriously polluted by As, Cd, and Pb. Some concentrations in the samples were beyond the regulatory levels and not suitable for agricultural activities. This study revealed that: (1) particulate matter is a major pollution source and an important carrier of mineral particles and pollutants; (2) the elements from the polluted water and soils were strongly correlated with each other; (3) Pb isotope ratios from the samples show that Pb minerals were the major pollution sources in the nearby vegetable fields, and the aerosols were the main carrier of mining pollution; (4) the alkaline, rich-carbonate, and wet conditions in this area promoted the weathering and transformation of galena into the secondary minerals, anglesite and cerussite, which are significant evidence of such processes; (5) the soil and the aerosols are a recycled secondary pollution source for each other when being re-suspended with wind.Highlights• Mining activities generated heavy metal pollution in fields around a Pb-Zn mine• The elements from water and soils are strongly correlated• Anglesite and cerussite are evidence of galena transformation into secondary minerals• Particulate matter is an important transport carrier of pollution.
显示更多 [+] 显示较少 [-]Genotoxic assessment and optimization of pressmud with the help of exotic earthworm Eisenia fetida 全文
2014
Bhat, Sartaj Ahmad | Jasawindara Siṅgha, | Vig, Adarsh Pal
Genotoxicity of pressmud (PM) to Allium cepa was investigated to assess its toxic potential and to elucidate the effect of vermicomposting to reduce its toxicity. The PM produced as a waste by product of the sugar cane industry was mixed with cow dung (CD) at different ratios of 0:100 (V₀), 25:75 (V₂₅), 50:50 (V₅₀), 75:25 (V₇₅) and 100:0 (V₁₀₀) (PM:CD) on a dry weight basis for vermicomposting with Eisenia fetida. Different concentrations of 100 % PM sludge extract (10 %, 20 %, 40 %, 60 %, 80 % and 100 %) and negative control (distilled water) and positive control (maleic hydrazide) were analyzed with A. cepa assay to evaluate frequency of chromosomal aberrations before and after vermicomposting. Percent aberration was greatest (30.8 %) after exposure to 100 % PM extract after 6 h but was reduced to 20.3 % after vermicomposting. Exposure to the extract induced c-mitosis, delayed anaphase, laggards, stickiness and vagrant aberrations. Microscopic examination of root meristem exposed to PM sludge extract showed significant inhibition of mitotic index. Also, the mitotic index decreased with increase in concentration of PM sludge extract. After vermicomposting the mitotic index was increased. However, increasing percentages of PM significantly affected the growth and fecundity of the worms and maximum population size was reached in the 25:75 (PM:CD) feed mixture. Nitrogen, phosphorus, sodium, electrical conductivity (EC) and pH increased from initial feed mixture to the final products (i.e., vermicompost), while organic carbon, C/N ratio and potassium declined in all products of vermicomposting. Scanning electron microscopy (SEM) was recorded to identify the changes in texture with numerous surface irregularities and high porosity that proves to be good vermicompost manure. It could be concluded that vermicomposting could be an important tool to reduce the toxicity of PM as evidenced by the results of genotoxicity.
显示更多 [+] 显示较少 [-]Rhizofiltration of lead using an aromatic medicinal plant Plectranthus amboinicus cultured in a hydroponic nutrient film technique (NFT) system 全文
2014
Ignatius, A. | Arunbabu, V. | Neethu, J. | Ramasamy, E.V.
Heavy metal contamination of water bodies and groundwater is a major concern of the modern world. Rhizofiltration—the use of plant root system to remove/extract pollutants from wastewater—has proven advantages over conventional methods of treatment. However, commercialization of this in situ remediation technology requires a better understanding of plant–metal interactions especially on the ability of different plant species to accumulate metals at different parts of the plant system which is critical for the successful remediation of contaminated medium. Many aquatic and terrestrial plants have been reported to accumulate heavy metals when grown hydroponically. Therefore, a batch experiment with different concentrations of lead and a nutrient film technique (NFT) experiment with recycling of wastewater were employed in this study in order to investigate the rhizofiltration of lead-containing wastewater using Plectranthus amboinicus, an aromatic medicinal plant. Results show that P. amboinicus is tolerant to a wide range of lead concentrations and nutrient deficiency. The plant accumulates considerable amount of lead, particularly in the roots, and translocation to the stem and leaf was limited, indicating that the use of leaves/above-ground parts of the plant for medicinal purposes is not hindered by its ability to remove lead from the soil or water. The study also suggests that the plant can be considered for the clean-up of lead-contaminated wastewater in combination with safe biomass disposal alternatives.
显示更多 [+] 显示较少 [-]A Visual Basic simulation software tool for performance analysis of a membrane-based advanced water treatment plant 全文
2014
Pal, P. | Kumar, R. | Srivastava, N. | Chowdhury, J.
A Visual Basic simulation software (WATTPPA) has been developed to analyse the performance of an advanced wastewater treatment plant. This user-friendly and menu-driven software is based on the dynamic mathematical model for an industrial wastewater treatment scheme that integrates chemical, biological and membrane-based unit operations. The software-predicted results corroborate very well with the experimental findings as indicated in the overall correlation coefficient of the order of 0.99. The software permits pre-analysis and manipulation of input data, helps in optimization and exhibits performance of an integrated plant visually on a graphical platform. It allows quick performance analysis of the whole system as well as the individual units. The software first of its kind in its domain and in the well-known Microsoft Excel environment is likely to be very useful in successful design, optimization and operation of an advanced hybrid treatment plant for hazardous wastewater.
显示更多 [+] 显示较少 [-]Genotoxicity and cytotoxicity induced by municipal effluent in multiple organs of Wistar rats 全文
2014
da Silva, Victor Hugo Pereira | de Moura, Carolina Foot Gomes | Ribeiro, Flavia Andressa Pidone | Cesar, Augusto | Pereira, Camilo Dias Seabra | Silva, Marcelo Jose Dias | Vilegas, Wagner | Ribeiro, Daniel Araki
The aim of this study was to evaluate cytotoxicity and genotoxicity in multiple organs of rats induced by municipal effluent released by submarine outfall in city of Santos. A total of 20 male Wistar rats were exposed to effluents by drinking water ad libitum at concentrations of 0, 10, 50, and 100 % for 30 days. Microscopic analysis revealed severe lesions such as necrosis and hemorrhagic areas in liver and kidney from animals exposed to effluent at 50 and 100 % concentration. DNA damage in peripheral blood, liver, and kidney cells were detected by comet assay at higher concentrations of effluent. Moreover, a decrease DNA repair capacity was detected in liver cells. Significant statistical differences (p < 0.05) for micronucleated cells from liver were noticed at 50 % concentration of effluent. Taken together, our results demonstrate that municipal effluent is able to induce cytotoxicity and genotoxicity in multiple organs of Wistar rats.
显示更多 [+] 显示较少 [-]Pyrolysis temperature influences ameliorating effects of biochars on acidic soil 全文
2014
Wan, Qing | Yuan, Jin-Hua | Xu, Ren-Kou | Li, Xing-Hui
The biochars were prepared from straws of canola, corn, soybean, and peanut at different temperatures of 300, 500, and 700 °C by means of oxygen-limited pyrolysis. Amelioration effects of these biochars on an acidic Ultisol were investigated with incubation experiments, and application rate of biochars was 10 g/kg. The incorporation of these biochars induced the increase in soil pH, soil exchangeable base cations, base saturation, and cation exchange capacity and the decrease in soil exchangeable acidity and exchangeable Al. The ameliorating effects of biochars on acidic soil increased with increase in their pyrolysis temperature. The contribution of oxygen-containing functional groups on the biochars to their ameliorating effects on the acidic soil decreased with the rise in pyrolysis temperature, while the contribution from carbonates in the biochars changed oppositely. The incorporation of the biochars led to the decrease in soil reactive Al extracted by 0.5 mol/L CuCl₂, and the content of reactive Al was decreased with the increase in pyrolysis temperature of incorporated biochars. The biochars generated at 300 °C increased soil organically complexed Al due to ample quantity of oxygen-containing functional groups such as carboxylic and phenolic groups on the biochars, while the biochars generated at 500 and 700 °C accelerated the transformation of soil exchangeable Al to hydroxyl-Al polymers due to hydrolysis of Al at higher pH. Therefore, the crop straw-derived biochars can be used as amendments for acidic soils and the biochars generated at relatively high temperature have great ameliorating effects on the soils.
显示更多 [+] 显示较少 [-]Field performance evaluation during fog-dominated wintertime of a newly developed denuder-equipped PM1 sampler 全文
2014
Singh, Dharmendra Kumar | Lakshay, | Gupta, Tarun
This study presents the performance evaluation of a novel denuder-equipped PM₁(particles having aerodynamic diameter less than 1 μm) sampler, tested during fog-dominated wintertime, in the city of Kanpur, India. One PM₁sampler and one denuder-equipped PM₁sampler were co-located to collect ambient PM₁for 25 days. The mean PM₁mass concentration measured on foggy days with the PM₁sampler and the denuder-equipped PM₁sampler was found to be 165.95 and 135.48 μg/m³, respectively. The mean PM₁mass concentration measured on clear days with the PM₁sampler and the denuder-equipped PM₁sampler was observed to be 159.66 and 125.14 μg/m³, respectively. The mass concentration with denuder-fitted PM₁sampler for both foggy and clear days was always found less than the PM₁sampler. The same drift was observed in the concentrations of water-soluble ions and water-soluble organic carbon (WSOC). Moreover, it was observed that the use of denuder leads to a significant reduction in the PM positive artifact. The difference in the concentration of chemical species obtained by two samplers indicates that the PM₁sampler without denuder had overestimated the concentrations of chemical species in a worst-case scenario by almost 40 %. Denuder-fitted PM₁sampler can serve as a useful sampling tool in estimating the true values for nitrate, ammonium, potassium, sodium and WSOC present in the ambient PM.
显示更多 [+] 显示较少 [-]Combined effects of silver nanoparticles and 17α-ethinylestradiol on the freshwater mudsnail Potamopyrgus antipodarum 全文
2014
Völker, Carolin | Gräf, Tonya | Schneider, Ilona | Oetken, Matthias | Oehlmann, Jörg
Ecotoxicological studies have shown that nanosilver is among the most toxic nanomaterials to aquatic organisms. However, research has so far focused on the determination of acute effects. Combined effects of nanosilver with other substances have not yet been studied in aquatic organisms. The present study aimed to investigate the chronic toxicity of nanosilver as well as the potential of nanosilver to influence the effects of co-occurring substances on the freshwater mudsnail Potamopyrgus antipodarum. In 28-day chronic toxicity experiments, the effects of nanosilver on the reproduction of P. antipodarum were assessed. In order to evaluate the influence of nanosilver on other substances, 17α-ethinylestradiol (EE₂) was chosen as model compound due to the well-characterized effects on P. antipodarum. In addition to effects on reproduction, exposure to nanosilver and EE₂was monitored by determining the expression of estrogen-responsive transcripts (estrogen receptor and vitellogenin encoding genes). Exposure to nanosilver decreased the reproduction of P. antipodarum (EC₁₀: 5.57 μg l⁻¹; EC₅₀: 15.0 μg l⁻¹). Exposure to EE₂significantly stimulated the embryo production at 25 ng l⁻¹. The presence of nanosilver led to increased EE₂effects at EE₂concentrations that had no influence on reproduction when applied in absence of nanosilver. In contrast, combined exposure to nanosilver decreased EE₂effects at concentrations that stimulated reproduction and the expression of estrogen responsive genes when applied in the absence of nanosilver. This is the first study demonstrating an influence of nanosilver on the effects of co-contaminants on aquatic organisms. The study further highlights the need for chronic experiments to properly assess environmental risks of nanosilver and their effects on co-occurring contaminants.
显示更多 [+] 显示较少 [-]Pathways of reductive degradation of crystal violet in wastewater using free-strain Burkholderia vietnamiensis C09V 全文
2014
Gan, Li | Fan, Zhushan | Palanisami, Thavamani | Chen, Zuliang | Megharaj, Mallavarapu | Naidu, R.
A new strain isolated from activated sludge and identified as Burkholderia vietnamiensis C09V was used to biodegrade crystal violet (CV) from aqueous solution. To understand the degradation pathways of CV, batch experiments showed that the degradation using B. vietnamiensis C09V significantly depended on conditions such as pH, initial dye concentration and media components, carbon and nitrogen sources. Acceleration in the biodegradation of CV was observed in presence of metal ions such as Cd and Mn. More than 98.86C of CV (30 mg l⁻¹) was degraded within 42 h at pH 5 and 30 °C. The biodegradation kinetics of CV corresponded to the pseudo first-order rate model with a rate constant of 0.046 h⁻¹. UV–visible and Fourier transform infrared spectroscopy (FTIR) were used to identify degradation metabolites. Which further confirmed by LC-MS analysis, indicating that CV was biodegraded to N,N-dimethylaminophenol and Michler’s ketone prior to these intermediates being further degraded. Finally, the ability of B. vietnamiensis C09V to remove CV in wastewater was demonstrated.
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