خيارات البحث
النتائج 1951 - 1960 من 3,208
Preliminary investigation on the potential use of two C4 turfgrass species to reduce nutrient release in a Mediterranean drained peatland النص الكامل
2015
Giannini, Vittoria | Pistocchi, Chiara | Silvestri, Nicola | Volterrani, Marco | Cantini, Valentina | Bonari, Enrico
This study compared dry matter production, nutrient uptake and tissue nutrient concentration of two C4 turfgrass species (Cynodon dactylon × Cynodon transvaalensis Burtt Davy and Paspalum vaginatum Swartz) supplied with three different nutrient solutions in a sand and peat culture. The 8-week experiment was performed in mesocosms and simulated the conditions of an open-field phyto-treatment system located in a Mediterranean drained peatland (Tuscany, Italy). Peat was collected on the site, and one of the solutions mimicked drainage water flowing into it. Three hypotheses were tested: (i) the species chosen efficiently removed nutrients from both the solution and the substrate; (ii) peat contributed to the nutrient load; and (iii) the species chosen were suitable in the open-field system. Both species adapted well to the experimental conditions and demonstrated considerable ability to remove nutrients. P. vaginatum took up nitrogen more efficiently, mainly in conditions of high nutrient availability. We observed supplementary nutrient uptake by plants in the peat treatment. Performances of the two C4 turfgrasses extrapolated to the field scale seemed effective from a phyto-treatment perspective.
اظهر المزيد [+] اقل [-]Can the origin of some metals in the seagrass Posidonia oceanica be determined by the indexes of metals pollutions? النص الكامل
2015
Stanković, Slavka | Jović, Mihajlo | Tanaskovski, Bojan | Mihajlović, Marija L. | Joksimović, Danijela | Pezo, Lato
To assess metal pollution, Fe, Mn, Cu, Zn, Pb, Ni, Co, As, Cd, and Hg contents in samples of the seagrass Posidonia oceanica and surface sediment, collected at eight locations along the Montenegrin coast, were determined. The metal pollution index (MPI) and metal enrichment factor (EF) were then calculated. MPI and EF were lower in sediment than in P. oceanica at the same locations. This was very evident for EF values of Hg and Cd. Based on the Pearson’s correlations and EF values, it was possible to conclude that the last two metals’ content in the seagrass did not originate from the crustal sources or natural weathering processes.
اظهر المزيد [+] اقل [-]Residential heating contribution to level of air pollutants (PAHs, major, trace, and rare earth elements): a moss bag case study النص الكامل
2015
Vuković, Gordana | Uros̆ević, Mira Aničić | Pergal, Miodrag | Jankovič, Milan | Goryainova, Zoya | Tomašević, Milica | Popović, Alexandre
In areas with moderate to continental climates, emissions from residential heating system lead to the winter air pollution peaks. The EU legislation requires only the monitoring of airborne concentrations of particulate matter, As, Cd, Hg, Ni, and B[a]P. Transition metals and rare earth elements (REEs) have also arisen questions about their detrimental health effects. In that sense, this study examined the level of extensive set of air pollutants: 16 polycyclic aromatic hydrocarbons (PAHs), and 41 major elements, trace elements, and REEs using Sphagnum girgensohnii moss bag technique. During the winter of 2013/2014, the moss bags were exposed across Belgrade (Serbia) to study the influence of residential heating system to the overall air quality. The study was set as an extension to our previous survey during the summer, i.e., non-heating season. Markedly higher concentrations of all PAHs, Sb, Cu, V, Ni, and Zn were observed in the exposed moss in comparison to the initial values. The patterns of the moss REE concentrations normalized to North American Shale Composite and Post-Archean Australian Shales were identical across the study area but enhanced by anthropogenic activities. The results clearly demonstrate the seasonal variations in the moss enrichment of the air pollutants. Moreover, the results point out a need for monitoring of air quality during the whole year, and also of various pollutants, not only those regulated by the EU Directive.
اظهر المزيد [+] اقل [-]Effects of surrounding land use on metal accumulation in environments and submerged plants in subtropical ponds النص الكامل
2015
Liu, Hui | Bu, Hongmei | Liu, Guihua | Wang, Zhixiu | Liu, Wenzhi
Ponds are widely used as stormwater treatment facilities to retain contaminants, including metals, and to improve water quality throughout the world. However, there is still a limited understanding of the effects of surrounding land use on metal accumulation in pond environments and organisms. To address this gap, we measured the concentrations of nine metals (i.e., Al, Ba, Ca, K, Li, Mg, Na, Se, and Sr) in water, sediments, and submerged plants collected from 37 ponds with different surrounding land uses in southwestern China and assessed the metal accumulation capacity of four dominant submerged plant species. Our results showed that Al, Ca, and K concentrations in the water were above drinking water standards. In the sediments, the average concentrations of Ca and Sr were higher than the corresponding soil background values. Ceratophyllum demersum L. could accumulate more K in aboveground biomass than Myriophyllum spicatum L. and Potamogeton maackianus A. Benn. The K concentration in submerged plants was positively influenced by the corresponding metal concentration in the water and negatively influenced by water temperature. Among the nine studied metals, only the water K concentration in ponds receiving agricultural runoff was significantly higher than that for ponds receiving urban and forested runoff. This result suggests that surrounding land use types have no significant effect on metal accumulation in sediments and submerged plants in the studied ponds. A large percentage of the metals in these ponds may be derived from natural sources such as the weathering of rocks.
اظهر المزيد [+] اقل [-]A multiscale modelling methodology applicable for regulatory purposes taking into account effects of complex terrain and buildings on pollutant dispersion: a case study for an inner Alpine basin النص الكامل
2015
Oettl, D.
Dispersion modelling in complex terrain always has been challenging for modellers. Although a large number of publications are dedicated to that field, candidate methods and models for usage in regulatory applications are scarce. This is all the more true when the combined effect of topography and obstacles on pollutant dispersion has to be taken into account. In Austria, largely situated in Alpine regions, such complex situations are quite frequent. This work deals with an approach, which is in principle capable of considering both buildings and topography in simulations by combining state-of-the-art wind field models at the micro- (<1 km) and mesoscale γ (2–20 km) with a Lagrangian particle model. In order to make such complex numerical models applicable for regulatory purposes, meteorological input data for the models need to be readily derived from routine observations. Here, use was made of the traditional way to bin meteorological data based on wind direction, speed, and stability class, formerly mainly used in conjunction with Gaussian-type models. It is demonstrated that this approach leads to reasonable agreements (fractional bias < 0.1) between observed and modelled annual average concentrations in an Alpine basin with frequent low-wind-speed conditions, temperature inversions, and quite complex flow patterns, while keeping the simulation times within the frame of possibility with regard to applications in licencing procedures. However, due to the simplifications in the derivation of meteorological input data as well as several ad hoc assumptions regarding the boundary conditions of the mesoscale wind field model, the methodology is not suited for computing detailed time and space variations of pollutant concentrations.
اظهر المزيد [+] اقل [-]Spatial distribution, health risk assessment and statistical source identification of the trace elements in surface water from the Xiangjiang River, China النص الكامل
2015
Zeng, Xiaoxia | Liu, Yunguo | You, Shaohong | Zeng, Guangming | Tan, Xiaofei | Hu, Xinjiang | Hu, Xi | Huang, Lei | Li, Fei
Surface water samples were collected from the sampling sites throughout the Xiangjiang River for investigating spatial variation, risk assessment and source identification of the trace elements. The results indicated that the mean concentrations of the elements were under the permissible limits as prescribed by guidelines except arsenic (As). Based on the health risk indexes, the primary contributor to the chronic risks was arsenic (As), which was suggested to be the most important pollutant leading to non-carcinogenic and carcinogenic concerns. Individuals, who depend on surface water from the Xiangjiang River for potable and domestic use, might be subjected to the integrated health risks for exposure to the mixed trace elements. Children were more sensitive to the risks than the adults, and the oral intake was the primary exposure pathway. Besides, multivariate statistical analyses revealed that arsenic (As), cadmium (Cd), lead (Pb), selenium (Se), and mercury (Hg) mainly derived from the chemical industrial wastewaters and the coal burning, and zinc (Zn) copper (Cu) and chromium (Cr) mainly originated from the natural erosion, the mineral exploitation activities, and the non-point agricultural sources. As a whole, the upstream of the Xiangjiang River was explained as the high polluted region relatively.
اظهر المزيد [+] اقل [-]Simultaneously degradation of 2,4-Dichlorophenol and EDTA in aqueous solution by the bimetallic Cu–Fe/O2 system النص الكامل
2015
Liu, Xin | Fan, Jin-Hong | Ma, Luming
Oxidative degradation of aqueous organic contaminants 2,4-dichlorophenol (2,4-DCP) using ethylenediaminetetraacetic acid (EDTA)-enhanced bimetallic Cu–Fe system in the presence of dissolved oxygen was investigated. The proposed process was applied for the pH range of 3~7 with the degradation efficiency of 2,4-DCP and EDTA varying within 10 %, and achieved at 100 % degradation of 40 mg L⁻¹2,4-DCP in 1 h, at the initial pH of 3, 25 g L⁻¹of bimetallic Fe–Cu powder (WCᵤ/WFₑ = 0.01289) and initial EDTA of 0.57 mM. However, the removal efficiency of 2,4-DCP in control tests were 7.52 % (Cu–Fe/O₂system) and 84.32 % (EDTA-enhanced Fe/O₂process), respectively, after 3 h, reaction. The proposed main mechanism, involves the in situ generation of H₂O₂by the electron transfer from Fe⁰to O₂which was enhanced by ethylenediaminetetraacetic acid (EDTA), and the in situ generation of ·OH via advanced oxidation reaction. Accordingly, 2,4-DCP was attacked by ·OH to achieve complete dechlorination and low molecular weight organic acids, even mineralized. Systematic studies on the effects of initial EDTA and 2,4-DCP concentration, Cu–Fe dosing, Cu content, and pH revealed that these effects need to be optimized to avoid the excessive consumption of ·OH and new EDTA and heavy metal Cu pollution.
اظهر المزيد [+] اقل [-]Persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil النص الكامل
2015
Mumbo, John | Henkelmann, Bernhard | Abdelaziz, Ahmed | Pfister, Gerd | Nguyen, Nghia | Schroll, Reiner | Munch, Jean Charles | Schramm, Karl-Werner
Halogenated carbazoles have recently been detected in soil and water samples, but their environmental effects and fate are unknown. Eighty-four soil samples obtained from a site with no recorded history of pollution were used to assess the persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil under controlled conditions for 15 months. Soil samples were divided into two temperature conditions, 15 and 20 °C, both under fluctuating soil moisture conditions comprising 19 and 44 drying–rewetting cycles, respectively. This was characterized by natural water loss by evaporation and rewetting to −15 kPa. Accelerated solvent extraction (ASE) and cleanup were performed after incubation. Identification and quantification were done using high-resolution gas chromatogram/mass spectrometer (HRGC/MS), while dioxin-like toxicity was determined by ethoxyresorufin-O-deethylase (EROD) induction in H4IIA rat hepatoma cells assay and multidimensional quantitative structure–activity relationships (mQSAR) modelling. Carbazole, 3-chlorocarbazole and 3,6-dichlorocarbazole were detected including trichlorocarbazole not previously reported in soils. Carbazole and 3-chlorocarbazole showed significant dissipation at 15 °C but not at 20 °C incubating conditions indicating that low temperature could be suitable for dissipation of carbazole and chlorocarbazoles. 3,6-Dichlorocarbazole was resistant at both conditions. Trichlorocarbazole however exhibited a tendency to increase in concentration with time. 3-Chlorocarbazole, 3,6-dibromocarbazole and selected soil extracts exhibited EROD activity. Dioxin-like toxicity did not decrease significantly with time, whereas the sum chlorocarbazole toxic equivalence concentrations (∑TEQ) did not contribute significantly to the soil assay dioxin-like toxicity equivalent concentrations (TCDD-EQ). Carbazole and chlorocarbazoles are persistent with the latter also toxic in natural conditions.
اظهر المزيد [+] اقل [-]Distribution of PCDD/Fs in the fly ash and atmospheric air of two typical hazardous waste incinerators in eastern China النص الكامل
2015
Chen, Tong | Zhan, Ming-xiu | Lin, Xiao-qing | Fu, Jian-ying | Lu, Sheng-yong | Li, Xiao-dong
Distribution of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the fly ash and atmospheric air of one medical waste incinerator (MWI) and one industrial hazardous waste incinerator (IHWI) plants were characterized. The PCDD/F concentrations of the stack gas (fly ash) produced from MWI and IHWI were 17.7 and 0.7 ng international toxic equivalent (I-TEQ)/Nm³(4.1 and 2.5 ng I-TEQ/g), respectively. For workplace air, the total concentrations of PCDD/Fs were 11.32 and 0.28 pg I-TEQ/Nm³(819.5 and 15.3 pg/Nm³). We assumed that the large differences of PCDD/F concentrations in workplace air were due to the differences in chlorine content of the waste, combustion conditions, and other contamination sources. With respect to the homologue profiles, the concentrations of PCDFs decreased with the increase of the substituted chlorine number for each site. Among all of the PCDD/F congeners, 2,3,4,7,8-PeCDF was the most important contributor to the I-TEQ value accounting for ca. 43 % of two sites. The gas/particle partition of PCDD/Fs in the atmosphere of the workplace in the MWI was also investigated, indicating that PCDD/Fs were more associated in the particle phase, especially for the higher chlorinated ones. Moreover, the ratio of the I-TEQ values in particle and gas phase of workplace air was 11.0. At last, the relationship between the distribution of PCDD/Fs in the workplace air and that from stack gas and fly ash was also analyzed and discussed. The high correlation coefficient might be a sign for diffuse gas emissions at transient periods of fumes escaping from the incinerator.
اظهر المزيد [+] اقل [-]Cancer risks and long-term community-level exposure to pentachlorophenol in contaminated areas, China النص الكامل
2015
Cheng, Pan | Zhang, Qinghe | Shan, Xiaomei | Shen, Denghui | Wang, Bingshuang | Tang, Zhenhai | Jin, Yu | Zhang, Chi | Huang, Fen
Widespread use of pentachlorophenol (PCP) in schistosomiasis endemic areas had led to ubiquitous exposure to PCP and its residues. Numerous studies had revealed that occupational PCP exposure probably increased risk of cancers, but whether long-term community-level exposure to PCP generates the similarly carcinogenic effect, seldom studies focused on it. This study was to explore the cancer risks of long-term community-level PCP exposure from drinking water in a Chinese general population. Incident (2009–2012) cancer records were identified by local government national registry. And PCP concentration of raw drinking water samples in each district was measured by GC-MS/MS analysis for further division of three PCP exposure categories by interquartile range (high vs. medium vs. low). Internal comparisons were performed, and standard rate ratio was calculated to describe the relationship between PCP exposure and cancer risks by using low-exposure group as the reference group. PCP was detected in all 27 raw drinking water samples ranging from 11.21 to 684.00 ng/L. A total of 6,750 cases (4,409 male and 2,341 female cases) were identified, and age-standardized rate (world) was 154.95 per 100,000 person-years. The cancer incidence for the high-exposure group was remarkably high. Internal comparisons indicated that high PCP exposure might be positively associated with high cancer risks in the community population, particularly for leukemia (SRR = 5.93, 95 % CI = 5.24–6.71), maligant lymphoma (SRR = 2.27, 95 % CI = 2.10–2.54), and esophageal cancer (SRR = 2.42, 95 % CI = 2.35–2.50). Long-term community-level exposure to PCP was probably associated with hemolymph neoplasm, neurologic tumors, and digestive system neoplasm.
اظهر المزيد [+] اقل [-]