خيارات البحث
النتائج 3341 - 3350 من 4,033
In situ stabilization of heavy metals in multiple-metal contaminated paddy soil using different steel slag-based silicon fertilizer
2016
Ning, Dongfeng | Liang, Yongchao | Song, Alin | Duan, Aiwang | Liu, Zhandong
Steel slag has been widely used as amendment and silicon fertilizer to alleviate the mobility and bioavailability of heavy metals in soil. The objective of this study was to evaluate the influence of particle size, composition, and application rate of slag on metal immobilization in acidic soil, metals uptake by rice and rice growth. The results indicated that application of slag increased soil pH, plant-available silicon concentrations in soil, and decreased the bioavailability of metals compared with control treatment, whereas pulverous slag (S1) was more effective than granular slag (S2 and S3). The acid-extractable fraction of Cd in the spiked soil was significantly decreased with application of S1 at rates of 1 and 3 %, acid-extractable fractions of Cu and Zn were decreased when treated at 3 %. Use of S1 at both rates resulted in significantly lower Cd, Cu, and Zn concentrations in rice tissues than in controls by 82.6–92.9, 88.4–95.6, and 67.4–81.4 %, respectively. However, use of pulverous slag at 1 % significantly promotes rice growth, restricted rice growth when treated at 3 %. Thus, the results explained that reduced particle size and suitable application rate of slag could be beneficial to rice growth and metals stabilization.
اظهر المزيد [+] اقل [-]Estimation of heavy metal loads from Tiber River to the Tyrrhenian Sea and environmental quality assessment
2016
Montuori, Paolo | Aurino, Sara | Garzonio, Fatima | Nardone, Antonio | Triassi, Maria
In order to evaluate the heavy metal pollution in the Tiber River and its environmental impact on the Tyrrhenian Sea (Central Mediterranean Sea), eight heavy metals (As, Hg, Cd, Cr, Cu, Ni, Pb and Zn) were determined in the water dissolved phase, suspended particulate matter and sediment samples collected from 21 sites in different seasons. Total heavy metal concentrations ranged from 34.88 to 4201.23 μg L⁻¹ in water (as the sum of the water dissolved phase and suspended particulate matter) and from 42.81 to 1686.84 mg kg⁻¹ in sediment samples. The total selected heavy metal load contribution into the sea is calculated in about 21,257.85 kg year⁻¹, showing that this River should account as one of the main contribution sources of heavy metals in the Mediterranean Sea. In relation to the ecological assessment, the Tiber River and Estuary would be considered as an area in which the ecological integrity is possibly at risk.
اظهر المزيد [+] اقل [-]Impact of northern and southern air mass transport on the temporal distribution of atmospheric 210Po and 210Pb in the east coast of Johor, Malaysia
2016
Sabuti, Asnor Azrin | Mohamed, Che Abd Rahim
Concentration activities of ²¹⁰Pb and ²¹⁰Po in the PM₁₀ were determined to discuss their distribution and chemical behavior in relation to meteorological parameters especially in air mass transport during monsoon events. Marine aerosol samples were collected between January 2009 and December 2010 at the coastal region of Mersing, which is located in the southern South China Sea and is about 160 km northeast of Johor Bahru, as part of the atmosphere–ocean interaction program in Malaysia. About 47 PM₁₀ samples were collected using the Sierra-Andersen model 1200 PM₁₀ sampler over a 2-year sampling campaign between January 2009 and December 2010. Samples were processed using acid digestion sequential extraction techniques to analyze various fractions such as Fe and Mn oxides, organic matter, and residual fractions. While, ²¹⁰Pb and ²¹⁰Po activities were measured with the Gross Alpha/Beta Counting System model XLB-5 Tennelec® Series 5 and the Alpha Spectrometry (model Alpha Analyst Spectroscopy system with a silicon-surface barrier detector), respectively. The distribution activities of ²¹⁰Pb and ²¹⁰Po in the PM₁₀ samples were varied from 162 to 881 μBq/m³ with mean value of 347 ± 170 μBq/m³ and from 85 to 1009 μBq/m³ with mean value of 318 ± 202 μBq/m³, respectively. The analysis showed that ²¹⁰Po activity in our samples lies in a border and higher range than global distribution values due to contributions from external sources injected to the atmosphere. The speciation of ²¹⁰Pb and ²¹⁰Po in marine aerosol corresponds to transboundary haze; e.g., biomass burning especially forest fires and long-range air mass transport of terrestrial dust has enriched concentrations of particle mass in the local atmosphere. The monsoon seems to play an important role in transporting terrestrial dust from Indo-China and northern Asia especially during the northeast monsoon, as well as biogenic pollutants originating from Sumatra and the southern ASEAN region during southwest monsoon events.
اظهر المزيد [+] اقل [-]Changes in dissolved organic matter composition and metabolic diversity of bacterial community during the degradation of organic matter in swine effluent
2016
Li, Lei | Liu, Ming | Li, Yanli | Ma, Xiaoyan | Tang, Xiaoxue | Li, Zhongpei
In this study, an incubation experiment was conducted with effluent collected from the concentrated swine-feeding operations (CSFOs) located in Yujiang County of Jiangxi Province, China. The purpose of this study was to elucidate the relationships between the composition of dissolved organic matter (DOM) and the community-level physiological profiles (CLPPs) of microorganisms in swine effluent. For all samples examined, the concentrations of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were decreased by an average of 58.2 ± 30.4 and 49.2 ± 38.7 %, whereas total dissolved phosphorus (TDP) exhibited an average final accumulation of 141.5 ± 43.0 %. In the original samples, ammonium nitrogen accounted for 88.9 ± 4.9 % of the TDN, which was reduced to a final average of 83.9 ± 9.6 %. Two protein-like (tyrosine and tryptophan) and two humic-like (fulvic acids and humic acids) components were identified using a three-dimensional excitation-emission matrix. With the increase in incubation time, the relative concentrations of two protein-like components in effluent were reduced by an average of 83.2 ± 24.7 %. BIOLOG™ ECO plates were used to determine the metabolic fingerprint of the bacterial community, and a shift in the utilization patterns of substrates was observed over the study period. Additionally, the Shannon–Wiener index of CLPP was ultimately reduced by an average of 43.5 ± 8.5 %, corresponding to the metabolic diversity of the bacterial community. The redundancy analysis identified significant relationships between environmental parameters and the CLPP of microorganisms. To a certain degree, the DOM compositions were linked with the substrate utilization patterns of the bacterial community during the degradation of organic matter in swine effluent.
اظهر المزيد [+] اقل [-]Magnitude of anthropogenic phosphorus storage in the agricultural production and the waste management systems at the regional and country scales
2016
Chowdhury, Rubel Biswas | Chakraborty, Priyanka
Based on a systematic review of 17 recent substance flow analyses of phosphorus (P) at the regional and country scales, this study presents an assessment of the magnitude of anthropogenic P storage in the agricultural production and the waste management systems to identify the potential for minimizing unnecessary P storage to reduce the input of P as mineral fertilizer and the loss of P. The assessment indicates that in case of all (6) P flow analyses at the regional scale, the combined mass of annual P storage in the agricultural production and the waste management systems is greater than 50 % of the mass of annual P inflow as mineral fertilizer in the agricultural production system, while this is close to or more than 100 % in case of half of these analyses. At the country scale, in case of the majority (7 out of 11) of analyses, the combined mass of annual P storage in the agricultural production and the waste management systems has been found to be roughly equivalent or greater than 100 % of the mass of annual P inflow as mineral fertilizer in the agricultural production system, while it ranged from 30 to 60 % in the remaining analyses. A simple scenario analysis has revealed that the annual storage of P in this manner over 100 years could result in the accumulation of a massive amount of P in the agricultural production and the waste management systems at both the regional and country scales. This study suggests that sustainable P management initiatives at the regional and country scales should put more emphasis on minimizing unwanted P storage in the agricultural production and the waste management systems.
اظهر المزيد [+] اقل [-]Distribution and variability of total mercury in snow cover—a case study from a semi-urban site in Poznań, Poland
2016
Siudek, Patrycja
In the present paper, the inter-seasonal Hg variability in snow cover was examined based on multivariate statistical analysis of chemical and meteorological data. Samples of freshly fallen snow cover were collected at the semi-urban site in Poznań (central Poland), during 3-month field measurements in winter 2013. It was showed that concentrations of atmospherically deposited Hg were highly variable in snow cover, from 0.43 to 12.5 ng L⁻¹, with a mean value of 4.62 ng L⁻¹. The highest Hg concentration in snow cover coincided with local intensification of fossil fuel burning, indicating large contribution from various anthropogenic sources such as commercial and domestic heating, power generation plants, and traffic-related pollution. Moreover, the variability of Hg in collected snow samples was associated with long-range transport of pollutants, nocturnal inversion layer, low boundary layer height, and relatively low air temperature. For three snow episodes, Hg concentration in snow cover was attributed to southerly advection, suggesting significant contribution from the highly polluted region of Poland (Upper Silesia) and major European industrial hotspots. However, the peak Hg concentration was measured in samples collected during predominant N to NE advection of polluted air masses and after a relatively longer period without precipitation. Such significant contribution to the higher Hg accumulation in snow cover was associated with intensive emission from anthropogenic sources (coal combustion) and atmospheric conditions in this area. These results suggest that further measurements are needed to determine how the Hg transformation paths in snow cover change in response to longer/shorter duration of snow cover occurrence and to determine the interactions between mercury and absorbing carbonaceous aerosols in the light of climate change.
اظهر المزيد [+] اقل [-]Substrate- and plant-mediated removal of citrate-coated silver nanoparticles in constructed wetlands
2016
Auvinen, Hannele | Sepúlveda, Viviana Vásquez | Rousseau, Diederik P. L. | Du Laing, Gijs
The growing production and commercial application of engineered nanoparticles (ENPs), such as Ag, CeO₂, and TiO₂ nanoparticles, induce a risk to the environment as ENPs are released during their use. The comprehensive assessment of the environmental risk that the ENPs pose involves understanding their fate and behavior in wastewater treatment systems. Therefore, in this study, we investigate the effect of plants and different substrates on the retention and distribution of citrate-coated silver nanoparticles (Ag-NPs) in batch experimental setups simulating constructed wetlands (CWs). Sand, zeolite, and biofilm-coated gravel induce efficient removal (85, 55, and 67 %, respectively) of Ag from the water phase indicating that citrate-coated Ag-NPs are efficiently retained in CWs. Plants are a minor factor in retaining Ag as a large fraction of the recovered Ag remains in the water phase (0.42–0.58). Most Ag associated with the plant tissues is attached to or taken up by the roots, and only negligible amounts (maximum 3 %) of Ag are translocated to the leaves under the applied experimental conditions.
اظهر المزيد [+] اقل [-]Phalangeal bone anomalies in the European common toad Bufo bufo from polluted environments
2016
Kaczmarski, Mikołaj | Kolenda, Krzysztof | Rozenblut-Kościsty, Beata | Sośnicka, Wioletta
Every spring, many of amphibians are killed by motor vehicles on roads. These road-killed animals can be used as valuable material for non-invasive studies showing the effect of environmental pollution on amphibian populations. The aims of our research were to check whether the phalanges of road-killed toads may be useful as material for histological analysis, and whether various degrees of human impact influence the level in bone abnormalities in the common toad. We also examined whether the sex and age structure of toads can differ significantly depending in the different sites. We chose three toad breeding sites where road-killed individuals had been observed: near the centre of a city, the outskirts of a city, and a rural site. We collected dead individuals during spring migration in 2013. The sex of each individual was determined and the toes were used to determine age using the skeletochronology method. While performing age estimates, we looked for abnormalities in relation to normal bone tissue structure. In urban site, females dominate males (sex ratio 2.6:1), but in populations from rural and semi-urban sites, sex ratio was reverse (1:2.2 and 1:1.4, respectively). However, we did not find any significant differences between age structure of all populations (average age of each population: approximately 4 years). We observed abnormalities in more than 80 % of all toads from the city, compared to approximately 20 % from the rural and semi-urban sites. In particular, we found hypertrophic bone cells, misaligned intercellular substance, and irregular outer edges of bones. We suggest that these malformations are caused by different pollution, e.g. with heavy metals.
اظهر المزيد [+] اقل [-]Differential effects on adiposity and serum marker of bone formation by post-weaning exposure to methylparaben and butylparaben
2016
Hu, Pan | Kennedy, Rebekah C. | Chen, Xin | Zhang, Jia | Shen, Chwan-Li | Chen, Jiangang | Zhao, Ling
Paraben esters and their salts are widely used as preservatives in cosmetics, personal care products, pharmaceuticals, and foods. We and others have reported that parabens promote adipogenesis in vitro. Here, we investigated the effects of post-weaning exposure to parabens (methylparaben and butylparaben) on body weight, white adipose tissue mass, and obesity associated metabolic biomarkers in female obesity-prone C57BL/6J mice fed with a chow diet or a high fat diet. Methylparaben exposure by daily oral gavage (100 mg/kg/day) increased adiposity and serum leptin levels compared to the controls when fed the chow diet, but not the high fat diet. In contrast, butylparaben exposure did not induce such effects. Exposure to either paraben induced changes in gene expression related to adipocyte differentiation and lipogenesis in the white adipose tissue (WAT) and the liver, regardless of diet. Moreover, exposure to both parabens under the chow diet significantly decreased serum procollagen type 1 N-terminal propeptide (P1NP) but had no effects on C-terminal telopeptide of type I collagen (CTX-I) levels, suggesting that post-weaning exposure to paraben may negatively affect bone formation, but not bone resorption. Taken together, our results demonstrate that post-weaning exposure to paraben, methylparaben in particular, promotes adipogenesis but suppresses serum marker of bone formation in vivo. Our results add to the growing body of literature indicating potential negative health outcomes associated with paraben exposure. Further study of early life exposure to paraben on the development of fat and bone is warranted.
اظهر المزيد [+] اقل [-]Biotransformation of petroleum asphaltenes and high molecular weight polycyclic aromatic hydrocarbons by Neosartorya fischeri
2016
Hernández-López, E Lorena | Perezgasga, Lucia | Huerta-Saquero, Alejandro | Mouriño-Pérez, Rosa | Vazquez-Duhalt, Rafael
Neosartorya fischeri, an Aspergillaceae fungus, was evaluated in its capacity to transform high molecular weight polycyclic aromatics hydrocarbons (HMW-PAHs) and the recalcitrant fraction of petroleum, the asphaltenes. N. fischeri was able to grow in these compounds as sole carbon source. Coronene, benzo(g,h,i)perylene, and indeno(1,2,3-c,d)pyrene, together with the asphaltenes, were assayed for fungal biotransformation. The transformation of the asphaltenes and HMW-PAHs was confirmed by reverse-phase high-performance liquid chromatography (HPLC), nano-LC mass spectrometry, and IR spectrometry. The formation of hydroxy and ketones groups on the PAH molecules suggest a biotransformation mediated by monooxygenases such as cytochrome P450 system (CYP). A comparative microarray with the complete genome from N. fischeri showed three CYP monooxygenases and one flavin monooxygenase genes upregulated. These findings, together with the internalization of aromatic substrates into fungal cells and the microsomal transformation of HMW-PAHs, strongly support the role of CYPs in the oxidation of these recalcitrant compounds.
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