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Resultados 1431-1440 de 4,940
Short-term geochemical investigation and assessment of dissolved elements from simulated ash reclaimed soil into groundwater
2019
Wang, Jiao
A soil column migration trough was used to study the leaching behavior and geochemical partitioning of fifteen elements Al, As, Cr, Cu, Fe, Mg, Sn, Sb, Zn, V, Co, Mn, Pb, Ni and Cd in simulated ash reclaimed soil. According to the results of cluster analysis for the sampling stations, there were three clusters: Cluster 1 of 7 wells with relative good groundwater quality originated from the background control area, Cluster 2 of 9 wells with worst groundwater quality in the downstream parts of the simulated ash reclaimed soil, and Cluster 3 of 2 wells with representative of samples influenced by the combined effect of injection of leaching solution and the main current. Statistical analysis identified five factor types that accounted for 83.055% of the total variance, which declined in the order: ash-soil rate > leaching intensity > water depths > flow velocity > leaching time. As, Sb, Cd, Pb and Ni were the dominant contaminants. The water around ash reclaimed soil was unsuitable for drinking. As, Mn, Cd, Sb, Co and V were the largest contributors to health risks. Soils reclaimed with fly ash can consequently be a long-time source for the transfer of toxic elements into groundwater.
Mostrar más [+] Menos [-]A new pathway for hexavalent chromium formation in soil: Fire-induced alteration of iron oxides
2019
Burton, Edward D. | Choppala, Girish | Karimian, Niloofar | Johnston, Scott G.
Iron oxides are important pedogenic Cr(III)-bearing phases which experience high-temperature alteration via fire-induced heating of surface soil. In this study, we examine if heating-induced alteration of Cr(III)-substituted Fe oxides can potentially facilitate rapid high-temperature oxidation of solid-phase Cr(III) to hazardous Cr(VI). Synthetic Cr(III)-substituted ferrihydrite, goethite and hematite were heated up to 800 °C for 2 h. Corresponding heating experiments were also conducted on an unpolluted Ferrosol-type soil, which had a total Cr content of 220 mg kg⁻¹, initially undetectable Cr(VI) and Fe speciation comprising a mixture of hematite, goethite and ferrihydrite (according to Fe K-edge EXAFS spectroscopy). Up to ∼50% of the initial Cr(III) was oxidised to Cr(VI) during heating of Cr(III)-substituted ferrihydrite and hematite, with the greatest extent of Cr(VI) formation occurring at 200–400 °C. In contrast, heating of Cr(III)-substituted goethite resulted in up to ∼100% of Cr(III) oxidizing to Cr(VI) as the temperature approached 800 °C. In the Ferrosol-type soil, heating at ≥400 °C also resulted in large amounts of Cr(VI) formation, with a maximum total Cr(VI) concentration of 77 mg kg⁻¹ forming at 600 °C (equating to oxidation of ∼35% of the soil's total Cr content). A relatively large portion (31–42%) of the total Cr(VI) which formed during heating of the soil was exchangeable, implying a high level of potential mobility and bioaccessibility. Overall, the results show that Cr(VI) forms rapidly via the oxidation of Fe oxide-bound Cr(III) at temperatures which occur in surface soils during fires. On this basis and given the frequency and extent of wild-fires around the world, we propose that fire-induced oxidation of Fe oxide-bound Cr(III) may represent a globally-significant pathway for the natural formation of hazardous Cr(VI) in surface soil.
Mostrar más [+] Menos [-]Association between perfluoroalkyl substance concentrations and blood pressure in adolescents
2019
Ma, Siyu | Xu, Cheng | Ma, Ji | Wang, Zhiqi | Zhang, Yuxi | Shu, Yaqin | Mo, Xuming
The effects of exposure to some environmental chemicals on blood pressure have been determined, but the association between non-occupational exposure to perfluoroalkyl substances (PFASs) and blood pressure in adolescents remains unknown. The association between blood pressure and PFAS concentrations was studied by analysing data from 2251 participants filtered from the population enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2012. After adjusting for age, sex, race, BMI, cotinine level, dietary intake of calcium, caloric intake, sodium consumption, potassium consumption and sampling year, we estimated the coefficients (betas) and 95% confidence intervals (CIs) for the relationship between PFAS concentrations and blood pressure with multiple linear regression models. Potential non-linear relationships were assessed with restricted cubic spline models. Blood levels of perfluorooctane sulfonic acid (PFOS) had a strong positive association with diastolic blood pressure (DBP) in adolescents in the linear model, while the result was not significant in the non-linear model. No significant association was observed between the concentration of any other PFASs and blood pressure. According to the fully adjusted linear regression model (P = 0.041), the mean DBP values in boys in the higher PFOS quintile were 2.70% greater than the mean DBP values of boys in the lowest PFOS quintile. Furthermore, serum PFOS concentrations predominantly affected blood pressure in male adolescents compared with female adolescents. These results provide epidemiological evidence of PFOS-related increases in DBP. Further research is needed to address related issues.
Mostrar más [+] Menos [-]Combined use of daily and hourly data sets for the source apportionment of particulate matter near a waste incinerator plant
2019
Lucarelli, F. | Barrera, V. | Becagli, S. | Chiari, M. | Giannoni, M. | Nava, S. | Traversi, R. | Calzolai, G.
A particulate matter (PM) source apportionment study was carried out in one of the most polluted districts of Tuscany (Italy), close to an old waste incinerator plant. Due to the high PM10 levels, an extensive field campaign was supported by the Regional Government to identify the main PM sources and quantify their contributions. PM10 daily samples were collected for one year and analysed by different techniques to obtain a complete chemical characterisation (elements, ions and carbon fractions). Hourly fine (<2.5 μm) and coarse (2.5–10 μm) aerosol samples were collected by a Streaker sampler for a shorter period and hourly elemental concentrations were obtained by PIXE.Positive Matrix Factorization (PMF) analysis of daily and hourly data allowed the identification of 10 main sources: six anthropogenic (Biomass Burning, Traffic, Secondary Nitrates, Secondary Sulphates, Incinerator, Heavy Oil combustion), two natural (Saharan Dust and Fresh Sea Salt) and two mixed sources (Local Dust and Aged Sea Salt). Biomass burning turned out to be the main source of PM, accounting for 30% of the PM10 mass as annual average, followed by Traffic (18%) and Secondary Nitrates (14%). Emissions from the Incinerator turned out to be only 2% of PM10 mass on average.PM10 composition and source apportionment have been assessed in a polluted area near a waste incinerator, by PMF analysis on daily and hourly compositional data sets.
Mostrar más [+] Menos [-]What is the most ecologically-meaningful metric of nitrogen deposition?
2019
Payne, Richard J. | Campbell, Claire | Britton, Andrea J. | Mitchell, R. J. (Ruth J.) | Pakeman, R. J. (Robin J.) | Jones, Laurence | Ross, L. C. (Louise C.) | Stevens, Carly J. | Field, Christopher | Caporn, Simon J.M. | Carroll, Jacky | Edmondson, Jill L. | Carnell, Edward J. | Tomlinson, Sam | Dore, Anthony J. | Dise, Nancy | Dragosits, Ulrike
Nitrogen (N) deposition poses a severe risk to global terrestrial ecosystems, and managing this threat is an important focus for air pollution science and policy. To understand and manage the impacts of N deposition, we need metrics which accurately reflect N deposition pressure on the environment, and are responsive to changes in both N deposition and its impacts over time. In the UK, the metric typically used is a measure of total N deposition over 1–3 years, despite evidence that N accumulates in many ecosystems and impacts from low-level exposure can take considerable time to develop. Improvements in N deposition modelling now allow the development of metrics which incorporate the long-term history of pollution, as well as current exposure. Here we test the potential of alternative N deposition metrics to explain vegetation compositional variability in British semi-natural habitats. We assembled 36 individual datasets representing 48,332 occurrence records in 5479 quadrats from 1683 sites, and used redundancy analyses to test the explanatory power of 33 alternative N metrics based on national pollutant deposition models. We find convincing evidence for N deposition impacts across datasets and habitats, even when accounting for other large-scale drivers of vegetation change. Metrics that incorporate long-term N deposition trajectories consistently explain greater compositional variance than 1–3 year N deposition. There is considerable variability in results across habitats and between similar metrics, but overall we propose that a thirty-year moving window of cumulative deposition is optimal to represent impacts on plant communities for application in science, policy and management.
Mostrar más [+] Menos [-]Cd contamination status and cost-benefits analysis in agriculture soils of Yangtze River basin
2019
Zhou, Xi-Yin | Wang, Xiuru
Soil is a fundamental carrier to support for human living and development and has been polluted seriously by heavy metals. This fact highlights the urgency to realize soil heavy metal pollution prevention through soil heavy metals contamination status assessment and root cause analysis. The previous research tends to focus status assessment and source identification without consideration of economic aspect. This study realized the systematic analysis from status assessment, sources identification and economic-environmental cost-benefits analysis in the Yangtze River basin. Through the spatial difference comparison among the provinces of upper, middle and lower in the Yangtze River basin, it revealed that anthropogenic influence is the main reason caused the current Cd contamination in Yangtze River basin. An interesting finding is that the human caused Cd concentration contribution amount is nearly the same between upstream and downstream which is all about 0.1 mg/kg, while they have quite different economic scale. It indicated that due to the difference of the scale and structure of local economy, and the level of cleaner production and pollution treatment, some regions could own high economic-benefits and low environmental cost, which it is opposite in other regions. The geographic location and natural resources is the root cause to form the environmental cost-economic benefits difference among regions. The convenient traffic promoted downstream to develop large amount and high quality of economy. The natural mineral resources promoted midstream to develop resources based economy. The poor condition of traffic and natural resources has restricted the development of Qinghai province, and made it has the highest Cd pollution intensity. The results would provide effective economic management measures for better soil quality and sustainable development goals achievement.
Mostrar más [+] Menos [-]Characterization of a multianalyte GC-MS/MS procedure for detecting and quantifying polycyclic aromatic hydrocarbons (PAHs) and PAH derivatives from air particulate matter for an improved risk assessment
2019
Mueller, Andrea | Ulrich, Nadin | Hollmann, Josef | Zapata Sanchez, Carmen E. | Rolle-Kampczyk, Ulrike E. | von Bergen, Martin
A correct description of the concentration and distribution of particle bound polycyclic aromatic hydrocarbons is important for risk assessment of atmospheric particulate matter. A new targeted GC-MS/MS method was developed for analyzing 64 PAHs including compounds with a molecular weight >300, as well as nitro-, methyl-, oxy- and hydroxyl derivatives in a single analysis. The instrumental LOD ranged between 0.03 and 0.7 pg/μL for PAHs, 0.2–7.9 pg/μL for hydroxyl and oxy PAHs, 0.1–7.4 pg/μL for nitro PAHs and 0.06–0.3 pg/μL for methyl-PAHs. As an example for the relevance of this method samples of PM₁₀ were collected at six sampling sites in Medellin, Colombia, extracted and the concentration of 64 compounds was determined. The 16 PAHs from the EPA priority list contributed only from 54% to 69% to the sum of all analyzed compounds, PAH with high molecular weight accounted for 8.8%–18.9%. Benzo(a)pyrene equivalents (BaPₑq) were calculated for the estimation of the life time cancer (LCR). The LCR according to the samples ranged from 2.75 × 10⁻⁵ to 1.4 × 10⁻⁴ by a calculation with toxic equivalent factors (TEF) and 5.7 × 10⁻⁵ to 3.8 × 10⁻⁴ with potency equivalent factor (PEF). By using the new relative potency factors (RPF) recommended by US Environmental Protection Agency (U.S.EPA) the LCR ranged from 1.3 × 10⁻⁴ to 7.2 × 10⁻⁴. Hence, it was around six times higher than the well-known TEF. The novel method enables the reliable quantification of a more comprehensive set of PAHs bound on PM and thus will facilitate and improve the risk assessment of them.
Mostrar más [+] Menos [-]Insight into the nitrification kinetics and microbial response of an enriched nitrifying sludge in the biodegradation of sulfadiazine
2019
Wang, Bingzheng | Ni, Bing-Jie | Yuan, Zhiguo | Guo, Jianhua
The intensive use of antibiotics results in the continuous release of antibiotics into wastewater treatment systems, leading to the spread of antibiotic resistance. Nitrifying system is reported to be capable of degrading antibiotics, yet few studies have systematically investigated the inherent correlation among ammonium oxidation rate, antibiotic degradation and genetic expression of nitrifying bacteria along the process. This study selected a widely used sulfonamide antibiotic, sulfadiazine (SDZ), to investigate its biodegradation potential by an enriched nitrifying culture and the response of nitrifying bacteria against antibiotic exposure. Our results demonstrated that SDZ degradation was mainly contributed by cometabolism of ammonia-oxidizing bacteria (AOB), rather than biomass adsorption. The quantitative reverse transcription PCR (RT-qPCR) analysis revealed that the expression level of amoA gene was down-regulated due to the SDZ exposure. In addition, the degradation products of SDZ did not exhibit inhibitory effect on Escherichia coli K12, indicating the biotoxicity of SDZ could be mitigated after biodegradation. The findings offer insights regarding the biodegradation process of sulfonamide antibiotics via cometabolism by AOB.
Mostrar más [+] Menos [-]Identification of 7–9 ring polycyclic aromatic hydrocarbons in coals and petrol coke using High performance liquid chromatography – Diode array detection coupled to Atmospheric pressure laser ionization – Mass spectrometry (HPLC-DAD-APLI-MS)
2019
Thiäner, Jan B. | Nett, Linus | Zhou, Shangbo | Preibisch, Yves | Hollert, Henner | Achten, Christine
Polycyclic aromatic hydrocarbons containing at least 24 carbon atoms (≥C₂₄-PAH) are often associated with pyrogenic processes such as combustion of fuel, wood or coal, and occur in the environment in diesel particulate matter, black carbon and coal tar. Some of the ≥C₂₄-PAH, particularly the group of dibenzopyrenes (five isomers, six aromatic rings) are known to show high mutagenic and carcinogenic activita.Gas chromatography – mass spectrometry is a well-established method for the analysis of lower molecular weight PAH but is not optimally suited for the analysis of ≥C₂₄-PAH due to their low vapor pressures. Also, hundreds of ≥C₂₄-PAH isomers are possible but only a few compounds are commercially available as reference standards. Therefore, in this study, a combination of multidimensional liquid chromatography, UV–Vis diode array detection, PAH selective and highly sensitive atmospheric pressure laser ionization – mass spectrometry is used to detect and unequivocally identify PAH. For identification of PAH in two bituminous coals and one petrol coke sample, unique and compound specific UV–Vis spectra were acquired. It was possible to identify ten compounds (naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[e,ghi]perylene, dibenzo[cd,lm]perylene, benzo[a]coronene, phenanthrol[5,4,3,2-abcde]perylene, benzo[ghi]naphtho[8,1,2-bcd]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene, naphtho[8,1,2-abc]coronene and tribenzo[e,ghi,k]perylene) by comparison of acquired spectra with spectra from literature. Additionally, it was possible to detect similar distribution patterns in different samples and signals related to alkylated naphthopyrenes, naphthofluoranthenes or dibenzopyrenes. Subsequent effect-directed analysis of a bituminous coal sample using the microEROD (ethoxyresorufin-O-deethylase) bioassay showed high suitability and revealed lower EROD induction for the ≥C₂₄-PAH (TEQ range 0.67–10.07 ng/g) than for the allover < C₂₄-PAH containing fraction (TEQ 84.00 ng/g). Nevertheless, the toxicity of ≥C₂₄-PAH has a significant impact compared with <C₂₄-PAH and must be considered for risk assessment. The LC-DAD-APLI-MS method, presented in this study, is a powerful tool for the unequivocal identification of these ≥ C₂₄-PAH.
Mostrar más [+] Menos [-]Occurrence of organophosphate flame retardants in farmland soils from Northern China: Primary source analysis and risk assessment
2019
Ji, Yan | Wang, Yu | Yao, Yiming | Ren, Chao | Lan, Zhonghui | Fang, Xiangguang | Zhang, Kai | Sun, Weijie | Alder, Alfredo C. | Sun, Hongwen
Ninety-eight soil samples were collected from farmland soils from Beijing-Tianjin-Hebei core area, Northern China, where agricultural lands were subjected to contamination from intense urban and industrial activities. Twelve organophosphates flame retardants (OPFRs) were analyzed with total soil concentrations ranging from 0.543 μg/kg to 54.9 μg/kg. Chlorinated OPFRs were dominating at mean level of 3.64 μg/kg and Tris(2-chloroisopropyl) phosphate contributed the most (mean 3.36 ± 5.61 μg/kg, 98.0%). Tris(2-ethylhexyl) phosphate was fully detected at levels of 0.041–1.95 μg/kg. Generally, tris(2-butoxyethyl) phosphate and triphenyl phosphate contributed the most to alkyl- (53.6%) and aryl-OPFRs (54.3%), respectively. The levels of ∑OPFRs close to the core urban areas were significantly higher than those from background sites. The occurrence and fate of OPFRs in soil were significantly associated with total organic carbon content and mostly with fine soil particles (<0.005 mm), and a transfer potential from the atmosphere was predicted with logKSA values. Comparable soil levels with poly brominated diphenyl ethers s in other studies suggested that the contamination of OPFRs occurred in farmland soil with an increasing trend but currently showed no significant environmental risk based on risk quotient estimation (<1). This investigation warrants further study on behaviors of OPFRs in a soil system and a continual monitoring for their risk assessment.
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