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Immobilization of Trace Metals in Contaminated Urban Soil Amended with Compost and Biochar
2015
Kargar, Maryam | Clark, O Grant | Hendershot, William H. | Jutras, Pierre | Prasher, Shiv O.
Urban soil amendment with organic matter can increase the steady state concentration of trace metals in urban soil. Different types of organic matter have different abilities to sorb and retain trace metals. The potential of urban soil amended with compost derived from mixed green and table waste and with maple-wood-derived biochar to retain trace metals (Cu, Zn, Cd, Pb) in the presence of de-icing salt (Na) was studied in a leaching test. Soil amended with compost retained significantly higher concentrations of Zn and Pb, as compared to soil amended with biochar, possibly due to the high cation exchange capacity of compost and its positive effect on soil pH. Indicating high ability for retaining trace metals, compost can bind contaminants originating from urban runoff water percolating through urban soil and provide a healthier medium for street tree growth.
Mostrar más [+] Menos [-]Bacterial Inactivation by Ultrasonic Waves: Role of Ionic Strength, Humic Acid, and Temperature
2015
Hwang, Gukhwa | Han, Yosep | Choi, Siyoung Q. | Cho, Sangho | Kim, Hyŏn-jŏng
The effects of ultrasonic wave irradiation on bacterial inactivation were investigated as functions of the ionic strength (IS), humic acid, and temperature. Escherichia coli (E. coli) D21g was selected as a model bacterium to better catch the effect of three parameters on the cell inactivation behavior. The Suwannee River humic acid (SRHA) was chosen as a representative humic acid, and the concentration for ultrasonic tests was kept to 10 ppm. The frequency of ultrasonic wave employed was 20 kHz, and the inactivation efficiency at two exposure times (5 and 10 min) was compared. The removal efficiency of E. coli D21g was confirmed to be 100 % at 10 min in all conditions except the 10-min temperature-controlled condition. The removal efficiency with the high IS was greater than that with the low IS, by 26 %, confirming an increase in the bacterial inactivation level with increasing IS. The bacterial removal efficiency with SRHA (96.6 %) was much greater than that without SRHA (69.6 %). The removal efficiency in the temperature-controlled condition (at a relatively low temperature) was significantly lower than that in the uncontrolled condition. Furthermore, the trend obtained using two other types of bacteria with more complex surface structure was consistent with that using the E. coli D21g cells.
Mostrar más [+] Menos [-]Analysis of Trace Elements in Groundwater Using ICP-OES and TXRF Techniques and Its Compliance with Brazilian Protection Standards
2015
Espinoza-Quiñones, Fernando R. | Módenes, Aparecido N. | de Pauli, Aline Roberta | Palácio, Soraya M.
In this work, an assessment of groundwater quality and its compliance with Brazilian environmental protection standards was carried out. Ground waters from the Serra Geral aquifer are currently used for human consumption at the western region of the Brazilian state of Paraná. Ground water samples from 10 wells covering the entire Toledo municipality rural region were collected and analysed by two highly accurate and sensitive spectrometric techniques: inductively coupled plasma–optical emission spectrometry (ICP-OES) and total reflection X-ray spectrometry (TXRF). Among all detected elements, 18 elements (As, Ba, Br, Ca, Pb, Cl, Co, Cu, Cr, Fe, P, S, Mn, Ni, K, Ti, V and Zn) were measured by the TXRF technique while three elements (B, Mg and Na) were measured by ICP-OES. Trace element concentration levels were then compared with Brazilian environmental legislation (BEL). From the results obtained, concentrations of chromium, iron, arsenic, selenium, manganese and barium were detectable in some wells at slightly above the maximum limits allowed by the BEL.
Mostrar más [+] Menos [-]Efficiency of Microfiltration Systems for the Removal of Bacterial and Viral Contaminants from Surface and Rainwater
2015
Dobrowsky, P. H. | Lombard, M. | Cloete, W. J. | Saayman, M. | Cloete, T. E. | Carstens, M. | Khan, S. | Khan, W.
The aim of this study was to evaluate the efficiency of a passive point-of-use treatment system, namely, a polyvinyl (alcohol) (PVA) nanofiber membrane/activated carbon column, for the treatment of harvested rainwater. The efficiency of SMI-Q10 [quaternized poly (styrene-co-maleimide)] nanofiber membrane disks placed in a filtration assembly for the treatment of surface water (Plankenburg River, Western Cape, South Africa) and harvested rainwater was also assessed. Two rainwater harvesting tanks were installed at the Welgevallen Experimental farm, Stellenbosch, South Africa, with the filtration system intermittently attached to the tanks for collection of rainwater samples throughout the study period. Parameters used to monitor the filtration systems included heterotrophic bacteria, Escherichia coli, and total coliform enumeration and the presence/absence of adenovirus. When compared to drinking water guidelines, the results indicated that 3 L of potable water could be produced by the synthesized PVA nanofiber membrane/activated carbon column. However, PCR assays indicated that adenovirus and numerous bacteria such as Klebsiella spp., Legionella spp., Pseudomonas spp., and Yersinia spp. were not effectively removed by the filtration system utilized. Additionally, the SMI-Q10 nanofiber membrane disks did not remove viruses from the river or tank water samples as bovine adenovirus 3 strain, simian adenovirus, and human adenovirus A strain were detected in all water samples analyzed. Thus, while the microfiltration system was efficient in reducing the level of indicator organisms to within drinking water standards, further optimization of the electrospun filtration membranes is required as molecular analysis revealed that numerous opportunistic bacterial pathogens and viruses persisted after filtration.
Mostrar más [+] Menos [-]Effects of Leaf Area and Transpiration Rate on Accumulation and Compartmentalization of Cadmium in Impatiens walleriana
2015
Lai, Hung-Yu
The efficiency of phytoextraction is limited because of the low growth exhibited by plants under the stress of heavy metals. Impatiens (Impatiens walleriana) cuttings were grown in soils artificially contaminated with cadmium (Cd) and modified with chemical fertilizer to study the relationship among the leaf area, transpiration rate, and Cd accumulation. The subcellular distribution of Cd in various impatiens organs was also measured. Experimental results showed that there were positive, linear relationships between the leaf area and the transpiration rate. A similar relationship was found between the transpiration rate and the Cd accumulation in the shoots. Suitable management practices can be conducted to increase the transpiration rate and thus the plant’s phytoextraction efficiency. In the roots and leaves, Cd was mainly compartmentalized in the soluble fraction and the cell wall fraction, respectively. The varied subcellular distribution of Cd in the different organs was responsible for the high accumulation capacity.
Mostrar más [+] Menos [-]Analysis of a Study of Lead Wheel Weight Deposition and Abrasion in New Jersey
2015
Root, Robert A.
This paper analyzes the implications for children’s health of shortcomings in the methods and results of a study of lead in the environment, “Quantity of Lead Released to the Environment in New Jersey in the Form of Motor Vehicle Wheel Weights,” by the New Jersey Department of Environmental Protection (Aucott and Caldarelli, Water, Air, & Soil Pollution, 223, 1743–1752, 2012). The study significantly understates the amount of lead deposited in New Jersey streets as 12 metric tons per year and incorrectly concludes that only 40 kg per year of the lead from wheel weights is abraded into small particles. The 2012 New Jersey Department of Environmental Protection (NJDEP) study misleads regulators and the public into believing that little toxic particulate lead from abraded wheel weights occurs on the streets of New Jersey and by implication that little occurs elsewhere in the United States, thus minimizing the potential health risk that lead wheel weights may have to our nation’s children and indeed all of us.
Mostrar más [+] Menos [-]Investigation of Critical Body Residues and Modes of Toxic Action Based on Injection and Aquatic Exposure in Fish
2015
Wen, Yang | Su, Limin | Qin, Weichao | Zhao, Yuanhui | Madden, Judith C. | Steinmetz, Fabian P. | Cronin, Mark T. D.
The internal concentration represented by the critical body residue (CBR) is an ideal indicator to reflect the intrinsic toxicity of a chemical. Whilst some studies have been performed on CBR, the effect of exposure route on internal toxicity has not been investigated for fish. In this paper, acute toxicity data to fish comprising LC₅₀ and LD₅₀ values were used to investigate CBR. The results showed that exposure route can significantly affect the internal concentration. LD₅₀ and CBR calculated from LC₅₀ and BCF both vary independently of hydrophobicity as expressed by log Kₒw; conversely, LC₅₀ is related to log Kₒw. A poor relationship was observed between LC₅₀ and LD₅₀, but the relationship can be improved significantly by introduction of log Kₒw because log CBR is positively related to log LD₅₀. The parallel relationship of log CBR-log Kₒw and log LD₅₀-log Kₒw indicates that LD₅₀ does not reflect the actual internal concentration. The average LD₅₀ is close to the average CBR for less inert and reactive compounds, but greater than the average CBR for baseline compounds. This difference is due to the lipid fraction being the major storage site for most of the baseline compounds. Investigation on the calculated and observed CBRs shows that calculated CBRs are close to observed CBRs for most of compounds. However, systemic deviations of calculated CBRs have been observed for some compounds. The reasons for these systemic deviations may be attributed to BCF, equilibrium time and experimental error of LC₅₀. These factors are important and should be considered in the calculation of CBRs.
Mostrar más [+] Menos [-]Gene Expression of Secale cereale (Fall Rye) Grown in Petroleum Hydrocarbon (PHC) Impacted Soil With and Without Plant Growth-Promoting Rhizobacteria (PGPR), Pseudomonas putida
2015
Gurska, Jolanta | Glick, Bernard R. | Greenberg, Bruce M.
Phytoremediation employs plants to sequester, degrade, and transform contaminants. This remediation technology depends on sufficient plant growth, often not achievable with high contaminant concentrations. One way to improve plant growth on impacted soils is by using plant growth-promoting rhizobacteria (PGPR). PGPR are naturally occurring soil microbes that stimulate plant growth through variety of means. We examined what changes in gene expression occurred in a grass species Secale cereale treated with PGPR, Pseudomonas putida PGPR (UW4), grown in petroleum hydrocarbon (PHC) impacted soil. UW4 promoted plant growth on the PHC impacted soil. Using differential display polymerase chain reaction (ddPCR), six genes were identified based on their altered expression as an effect of PHC exposure and plant PGPR treatment. The changes in levels of expression of selected genes were measured using quantitative PCR (qPCR). There was upregulation of all six genes examined, two of which were statistically significant. In roots, two genes were upregulated significantly and one gene appeared to be downregulated.
Mostrar más [+] Menos [-]A Review on Phytoremediation of Crude Oil Spills
2015
Yavari, Sara | Malakahmad, Amirhossein | Sapari, Nasiman B.
Changes in crude oil production and distribution have increased the incidence of oil spills throughout the world. Oil spills often cause destructive effects on aquatic and land ecosystems. The oil spill cleanup and recovery techniques are challenging and usually involve complex mechanical, chemical, and biological methods. Usually, mechanical removal of free oil is utilized as an effective strategy for cleanup in aquatic and terrestrial environments; however, they are expensive and need specialist personnel and equipment. The other commonly used method is the application of chemical materials such as dispersants, cleaners, demulsifiers, biosurfactants, and soil oxidizers. Nevertheless, these reagents can have potential harmful environmental impacts, which may limit their application. As an alternative, bioremediation can offer reduced environment risk; however, the limitations of microbial activity in the soil can make this option unsuitable. One area of bioremediation is phytoremediation, which offers potential for restoring large areas of contaminated ground. Plants are able to remove pollutants through processes such as biodegradation, phytovolatilization, accumulation, and metabolic transformation. This review presents the fate of crude oil spills in aquatic and land ecosystems and their environmental effects. Furthermore, the paper focuses on crude oil phytoremediation and its applications in polluted ecosystems.
Mostrar más [+] Menos [-]CO2 Capture on Metallic Oxide Powders Prepared Through Chemical Combustion and Calcination Methods
2015
Granados-Correa, F. | Bonifacio-Martínez, J. | Hernández-Mendoza, H. | Bulbulian, S.
Mg, Zn, Mn, and Al oxide powders have been synthesized through chemical combustion and calcination methods to compare their CO₂ capture performances. The characteristic properties of the adsorbents were evaluated by X-ray diffraction analysis, scanning electron microscopy, and N₂ physisorption measurements. The porous γ-Al₂O₃ prepared through combustion with a BET-specific surface area of 192.1 m²/g, achieving a maximum gas adsorption capacity of 1.71 mmol/g at 60 °C and 1.5 MPa. The MgO adsorbent performed poorly during CO₂ capture, while that Zn and Mn oxides showed no CO₂ adsorption. The results showed theoretical contribution to the field of separation science.
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