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Chelating–Ultrafiltration Treatment of Some Heavy Metal Ions in Aqueous Solutions by Crosslinking Carboxymethyl Modified Cornstarch Texto completo
2012
Wang, Ting | Song, Ye | Li, Bin | Zhou, Xiaoguang
Crosslinking carboxymethyl starch (CCMS) powder of degree of substitution (DS) 0.43–0.59 was prepared by the process of two steps of alkali addition synthesis. The technique of powder coupling with ultrafiltration was used to absorb Cu2+, Zn2+, Ni2+, Pb2+, and Cd2+ from aqueous solutions. FTIR was used to demonstrate the successfully grafting of carboxymethyl groups, and the technique of microwave plasma torch atomic emission spectrometer was applied in rapid determination of the aforementioned heavy metals ions. The results revealed that the removal sequence of heavy metal ions followed the order of Pb2+>Cu2+>Cd2+>Zn2+>Ni2+. By assistant of diethylene triamine penlaacetic acid, the quaternary system of Pb2+/Ni 2+/Cd2+/Cu2+ mixture solution could have the ideal separation. Besides, the influence of pH, ζ potential, DS value, and membranes molecular weight cut-off on removal of 20 mg L−1 Pb2+ or Ni2+ was also investigated.
Mostrar más [+] Menos [-]Environmental Monitoring Using Electrical Resistivity Tomography (ERT) in the Subsoil of Three Former Petrol Stations in SE of Spain Texto completo
2012
Rosales, Rosa Ma | Martínez-Pagan, Pedro | Faz, Angel | Moreno-Cornejo, Jennifer
Electrical resistivity tomography (2D ERT) is a powerful tool for the diagnosis of the subsoil state and to pursue an environmental monitoring in time to detect and follow a temporal evolution of plumes in hydrocarbon-contaminated soils. In situ, 2D ERT was conducted to investigate the electrical properties of the subsoil in three petrol stations in Murcia semiarid Region (SE Spain), which have been active for many years, in order to look for anomalous areas that could be related to the presence of a non-aqueous phase liquid (NAPL) contaminant plume in the subsoil. A total of 18 ERT profiles in wet and dry season were conducted to study the seasonal effects in the resistivity values of the subsoil. Dipole–dipole array was set up to make the soil diagnosis, achieving a good vertical and lateral resistivity distributions for the sites investigated. Interpretations obtained from ERT pseudo-sections, after a processing and inversion data process with PROSYS II and RES2DINV software, show delimited highly resistive regions above 2,000 Ω·m at 2 m deep related to the underground storage tanks (USTs) position and the filling ports and anomalous resistivity areas where boreholes and further GC–FID determination in soil samples have been done. No significant differences have been found between results obtained in dry and wet seasons. Thus, the geo-electrical non-destructive technique ERT is presented as a tool to delineate the USTs positions and to point out anomaly in the subsoil that could contain NAPL, helping to design sampling strategies, saving cost and time.
Mostrar más [+] Menos [-]Evaluation of Premature Mortality Caused by Exposure to PM2.5 and Ozone in East Asia: 2000, 2005, 2020 Texto completo
2012
Nawahda, Amin | Yamashita, Ken | Ōhara, Toshimasa | Kurokawa, Junichi | Yamaji, Kazuyo
The aim of this study is to assess the premature mortality risks caused by exposure to particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) and ozone elevated concentrations for the years 2000, 2005, and 2020 in East Asia. The spatial distributions and temporal variations of PM2.5 and ozone concentrations are simulated using the Models-3 Community Multiscale Air Quality Modeling System coupled with the Regional Emission Inventory in Asia. The premature mortality risks caused by exposure to PM2.5 and ozone are calculated based on a relative risk (RR) value of 1.04 (95 % confidence interval (CI): 1.01â1.08) for PM2.5 concentrations above the annual mean limit of 10 μg mâ3 taken from the World Health OrganizationâAir Quality Guideline and based on a RR value of 1.003 (95 % CI: 1.001â1.004) for ozone concentration above 35 ppb of the SOMO35 index (the sum of ozone daily maximum 8-h mean concentrations above 35 ppb). We demonstrate one of the implications of the policy making in the area of environmental atmospheric management in East Asia by highlighting the annual premature mortalities associated with exposure to PM2.5 concentrations that just meet an annual mean concentration of 10 μg mâ3, as well as ozone concentrations that have a daily zero SOMO35 index in vulnerable places. Our results point to a growing health risk that may endanger human life in East Asia. We find that the effect of PM2.5 on human health is greater than the effect of ozone for the age group of 30 years and above. We estimate the corresponding premature mortality due to the effects of both ozone and PM2.5 in East Asia for the years 2000 and 2005 to be around 316,000 and 520,000 cases, respectively. For future scenarios of the year 2020, policy succeed case, reference, and policy failed case, the estimated annual premature mortality rates are 451,000, 649,000, and 1,035,000 respectively.
Mostrar más [+] Menos [-]Monitoring of Aerosol and Fallout Radioactivity in Belgrade After the Fukushima Reactors Accident Texto completo
2012
Nikolic, Jelena | Pantelic, Gordana | Todorovic, Dragana | Janković, Marija | Savkovic, Maja Eremić
After the accident in Fukushima reactors, a daily monitoring programme was initiated in two laboratories in Belgrade, one at the Vinčа Institute for Nuclear Sciences and the other at Institute for Occupational Health Karajovic. Samples of aerosol and fallout, as well as the random samples of food and water, were collected and analysed, using gross alpha/beta and gamma spectrometry, in order to establish the presence of traces of isotopes indicating Fukushima fallout. Gamma spectrometry measurement of these samples showed clear evidence of fission products ¹³¹I, ¹³⁴Cs and ¹³⁷Cs wtihin 2 weeks after the accident. The activity diminished with time due to dispersion in air and, in case of ¹³¹I, short half-life.
Mostrar más [+] Menos [-]Evaluating Methane Oxidation Efficiencies in Experimental Landfill Biocovers by Mass Balance and Carbon Stable Isotopes Texto completo
2012
Capanema, Marlon A. | Cabral, Alexandre R.
Biocovers are an alternative for mitigating fugitive and residual emissions of methane from landfills. In this study, we evaluated the performance of two experimental passive methane oxidation biocovers (PMOBs) constructed within the existing final cover of the St-Nicéphore landfill (Quebec, Canada). The biocovers were fed in a controlled manner with raw biogas and surface fluxes were obtained using static chambers. This enabled calculating mass balances of CH₄ and oxidation efficiencies (f ₒ_MB). Most of the time, f ₒ_MB ≥ 92 % were obtained for loadings as high as 818 g CH₄ m⁻² day⁻¹ (PMOB-2) and 290 g CH₄ m⁻² day⁻¹ (PMOB-3B). The lowest efficiencies (f ₒ_MB = 45.5 % and 34.0 %, respectively) were obtained during cold days (air temperature ~0 °C). Efficiencies were also calculated using stable isotopes (f ₒ_SI); the highest f ₒ_SI were 66.4 % for PMOB-2 and 87.3 % for PMOB-3B; whereas the lowest were 18.8 % and 23.1 %, respectively. However, f ₒ_SI values reflect CH₄ oxidation up to a depth of 0.10 m, which may partly explain the difference in regards to mass balance-derived efficiencies. Indeed, it is expected that a significant fraction of the total CH₄ oxidation occurs within the zone near the surface, where there is greater O₂ availability. The influence of the values of fractionation factors α ₒₓ and α ₜᵣₐₙₛ were also evaluated in this paper.
Mostrar más [+] Menos [-]Nitrate and Phosphate Leaching under Turfgrass Fertilized with a Squid-based Organic Fertilizer Texto completo
2012
Fetter, Joseph C. | Brown, Rebecca N. | Görres, Josef H. | Lee, Chong | Amador, José A.
Consumer demand for cleaned squid generates a substantial amount of waste that must be properly disposed of, creating an economic burden on processors. A potential solution to this problem involves converting squid by-products into an organic fertilizer, for which there is growing demand. Because fertilizer application to lawns can increase the risk of nutrient contamination of groundwater, we quantified leaching of NO3–N and PO4–P from perennial ryegrass turf (Lolium perenne L.) amended with two types of fertilizer: squid-based (SQ) and synthetic (SY). Field plots were established on an Enfield silt loam, and liquid (L) and granular (G) fertilizer formulations of squid and synthetic fertilizers were applied at 0, 48, 146, and 292 kg N ha−1 year−1. Levels of NO3–N and PO4–P in soil pore water from a depth of 60 cm were determined periodically during the growing season in 2008 and 2009. Pore water NO3–N levels were not significantly different among fertilizer type or formulation within an application rate throughout the course of the study. The concentration of NO3–N remained below the maximum contaminant level (MCL) of 10 mg L−1 until midSeptember 2009, when values above the MCL were observed for SQG at all application rates, and for SYL at the high application rate. Annual mass losses of NO3–N were below the estimated inputs (10 kg N ha−1 year−1) from atmospheric deposition except for the SQG and SYL treatments applied at 292 kg N ha−1 year−1, which had losses of 13.2 and 14.9 kg N ha−1 year−1, respectively. Pore water PO4–P levels ranged from 0 to 1.5 mg P L−1 and were not significantly different among fertilizer type or formulation within an application rate. Our results indicate that N and P losses from turf amended with squid-based fertilizer do not differ from those amended with synthetic fertilizers or unfertilized turf. Although organic in nature, squid-based fertilizer does not appear to be more—or less—environmentally benign than synthetic fertilizers.
Mostrar más [+] Menos [-]Multiparameter Quantitative Optimization in the Synthesis of a Novel Coagulant Derived from Tannin Extracts for Water Treatment Texto completo
2012
Beltrán-Heredia, Jesus | Sánchez-Martín, Jesus | Martín-García, Leticia
A novel tannin-based coagulant has been synthesized at lab scale. A multiparameter optimization was performed on the production process, and up to five variables were studied according to the response surface methodology in a face-centered design of experiments which included two temperatures, two pH levels, and the reaction time in the chemical process. The coagulant involved diethanolamine, formaldehyde, and a tannin extract from Acacia mearnsii de Wild. The results revealed an average optimum combination for dye and surfactant removal which was able to remove either Alizarin Violet 3R and sodium dodecylbenzene sulfonate efficiently from water effluents.
Mostrar más [+] Menos [-]Effectiveness of Plant-Derived Sorbents for the Remediation of Low-Energy Intertidal Wetlands Contaminated by Oil Spills Texto completo
2012
Chung, Seungjoon | Suidan, Makram T. | Venosa, Albert D.
The use of plant-derived sorbent was investigated as a remediation strategy for low-energy intertidal wetlands contaminated by crude oil spills. Effectiveness of plant-derived sorbent as a wicking agent was evaluated in microcosms simulating intertidal wetlands. Microcosms were designed to impose three different oil penetration depths (0.25, 0.5, and 1.0 cm), two different tidal amplitudes (±5 and ±10 cm above oil-contaminated surface), and two different types of sorbents (raw bagasse and hydrophobic-treated bagasse). We observed that the use of plant-derived sorbent was beneficial not only in removing oil but also in preventing further contamination. Oil penetration depth and tidal amplitude both negatively influenced the effectiveness of the sorbent. Effectiveness of the hydrophobic-treated sorbent was always higher than that of untreated one at any given oil penetration depth and tidal amplitude. Effectiveness of hydrophobic-treated sorbent was relatively low compared to that of raw bagasse. The most plausible explanation is that oil wicking mainly occurred during low tide. From a cost-effectiveness point of view, we suggest the use of raw bagasse immediately after an oil spill for remediation of low-energy intertidal wetlands. The observed results imply that this technique has potential to stimulate biodegradation by wicking oil out of contaminated intertidal wetlands subsurface to the aerobic zone where biodegradation can take place.
Mostrar más [+] Menos [-]Digestive Cecum and Tissue Redistribution in Gills of Telescopium telescopium as Indicators of Ni Bioavailabilities and Contamination in Tropical Intertidal Areas Texto completo
2012
Yap, C. K. | Noorhaidah, A. | Tan, S. G.
The relationships between the Ni concentrations of the mudflat snails Telescopium telescopium and the surface sediments have not been reported yet from tropical intertidal areas. In this study, telescope snails and surface sediments were collected from 18 geographical sampling sites in intertidal areas of Peninsular Malaysia. The concentrations of Ni were measured in seven different soft tissues of the snails namely foot, cephalic tentacles, mantle, muscle, gill, digestive cecum, and remaining soft tissues. It was found that different concentrations of Ni were found in the different soft tissues, indicating different mechanisms of sequestration and regulation of Ni in these different tissues. By comparing the Ni concentrations in the similar tissues, spatial variations of Ni were found in the different sampling sites although there was no consistent pattern of Ni in these sites. The highest Ni variation based on the ratio of maximum to minimum values indicated that cephalic tentacle and foot were the main organs having high Ni variation. The use of correlation analysis and multiple linear stepwise regression analysis revealed that digestive cecum of T. telescopium could be used to reflect the Ni contamination of the sampling site. Also, the digestive cecum and gill were found to be the main bioaccumulation and storage sites for Ni. From the Ni accumulation patterns in all the populations investigated, tissue redistributions of Ni in gill was identified and could be proposed as an indicator of high Ni bioavailability and contamination in the sampling site. To our knowledge, this is the first and most comprehensive study on Ni accumulation in the different soft tissues of T. telescopium from tropical intertidal areas, in relation to the sediment data.
Mostrar más [+] Menos [-]Remediation of Nitrate-Nitrogen Contaminated Groundwater by a Heterotrophic-Autotrophic Denitrification Approach in an Aerobic Environment Texto completo
2012
Huang, Guoxin | Fallowfield, Howard | Guan, Huade | Liu, Fei
A novel heterotrophic-autotrophic denitrification (HAD) approach supported by mixing granulated spongy iron, methanol, and mixed bacteria was proposed for the remediation of nitrate-nitrogen (NO₃-N) contaminated groundwater in a dissolved oxygen (DO)-rich environment. The HAD process involves biological deoxygenation, chemical reduction (CR) of NO₃-N and DO, heterotrophic denitrification (HD), and autotrophic denitrification (AD). Batch experiments were performed to: (1) investigate deoxygenation capacities of HAD; (2) determine the contributions of AD, HD, and CR to the overall NO₃-N removal in the HAD; and (3) evaluate the effects of environmental parameters on the HAD. There were 174, 205, and 2,437 min needed to completely reduce DO by the HAD, spongy iron-based CR, and by the mixed bacteria, respectively. The HAD depended on abiotic and biotic effects to remove DO. CR played a dominant role in deoxygenation in the HAD. After 5 days, approximately 100, 63.0, 20.1, and 9.7 % of the initial NO₃-N was removed in the HAD, HD, AD + CR, and CR incubations, respectively. CR, HD, and AD all contributed to the overall NO₃-N removal in the HAD. HD was the most important NO₃-N degradation mechanism in the HAD. There existed symbiotic, synergistic, and promotive effects of CR, HD, and AD within the HAD. The decrease in NO₃-N and the production of nitrite-nitrogen (NO₂-N) and ammonium-nitrogen (NH₄-N) in the HAD were closely related to the C to N weight ratio. The C to N ratio of 3.75:1 was optimal for complete denitrification. Denitrification rate at 27.5°C was 1.36 times higher than at 15.0°C.
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