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974.
John W. Leung 《Journal of environmental science and health. Part. B》2013,48(2):341-363
Abstract A fluorometric method was developed to quantify glyphosate loss from glass surfaces after exposure to the natural forest environment. The method was based on the principle of converting glyphosate into glycine, followed by the fluorogenic labeling with o‐phthalaldehyde. A fluorometer (with λ Ex = 360 nm / λEm =430 nm) was used to quantify the derivatized fluorogenic compound. Response was linear over the concentration range of 143, 286, 572, 858 and 1144 μg of glyphosate (acid equivalent, AE) per mL of the diluted Vision® formulation. Three end‐use mixtures of Vision® were prepared, each at a concentration of 28.6 g AE/L, without and with two adjuvants, Ethomeen® T/25 at 4.5 mL/L and Silwet® L‐77 at 1.5 mL/L. Several dilutions of the end‐use mixtures were applied on glass slides without and with the coating of cuticular wax extracted from trembling aspen foliage. The slides were left for 5 days in a forest opening to determine rainfastness, volatilization and photostability of glyphosate. The residues were quantified using the method developed. Three calibration curves were required because Silwet decreased the fluorometric response of glyphosate, whereas Ethomeen increased it. The minimum detection limit was 143 μg of glyphosate/mL. Glyphosate was resistant to volatilization and sunlight‐mediated degradation, regardless of the presence of wax coating or the adjuvants. About 64% of the applied glyphosate was washed off after a 9.6 mm rainfall when no adjuvant was present. Both adjuvants provided some amount of rain‐protection to glyphosate, but Silwet reduced the washoff to a greater extent (46%) than Ethomeen (55%). 相似文献
975.
The 24-h average coarse (PM10) and fine (PM2.5) fraction of airborne particulate matter (PM) samples were collected for winter, summer and monsoon seasons during November 2008-April 2009 at an busy roadside in Chennai city, India. Results showed that the 24-h average ambient PM10 and PM2.5 concentrations were significantly higher in winter and monsoon seasons than in summer season. The 24-h average PM10 concentration of weekdays was significantly higher (12-30%) than weekends of winter and monsoon seasons. On weekends, the PM2.5 concentration was found to slightly higher (4-15%) in monsoon and summer seasons. The chemical composition of PM10 and PM2.5 masses showed a high concentration in winter followed by monsoon and summer seasons.The U.S.EPA-PMF (positive matrix factorization) version 3 was applied to identify the source contribution of ambient PM10 and PM2.5 concentrations at the study area. Results indicated that marine aerosol (40.4% in PM10 and 21.5% in PM2.5) and secondary PM (22.9% in PM10 and 42.1% in PM2.5) were found to be the major source contributors at the study site followed by the motor vehicles (16% in PM10 and 6% in PM2.5), biomass burning (0.7% in PM10 and 14% in PM2.5), tire and brake wear (4.1% in PM10 and 5.4% in PM2.5), soil (3.4% in PM10 and 4.3% in PM2.5) and other sources (12.7% in PM10 and 6.8% in PM2.5). 相似文献
976.
Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d−1 kg−1 pig at swine finishing barns and from 2.3 to 45.2 g d−1 m−2 at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors. 相似文献
977.
为实现工业园区企业污染排放精细化管控,捕捉工业园区内企业污染排放与污染物浓度之间的响应关系,提出一种集成大气环境容量(AEC)和时空特征的工业园区PM2.5浓度预测模型.通过有限体积法获得工业园区日均大气自净能力指数(ASI),结合工业园区日排放数据作为AEC特征;同时利用小波分析和Pearson相关系数法提取时空特征,包括目标监测站PM2.5浓度的时间变化特征和其与周围监测点PM2.5的空间相关特征.通过CNN获取训练数据中PM2.5的关联特征,并利用BILSTM充分反映时间序列训练数据中隐含的关键历史长短期依赖关系,确保快速准确的预测性能,以2018~2020年濮阳市工业园区大气污染物观测数据、气象数据及排放数据进行实验验证.结果表明:本文提出的CNN-BILSTM预测模型相较于传统LSTM模型预测精度提升10%;AEC特征和时空特征有利于提高模型精度和稳定性,集成AEC和时空特征的CNN-BILSTM预测模型在PM2.5污染天数预测准确率最高,达93%;分季节预测结果表明... 相似文献
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本文利用了1998—2012年中国241个城市的空间面板数据对中国雾霾污染和FDI的区域分布特征及空间溢出效应进行经验考察,结合系统广义矩估计(SGMM)方法构建了动态空间面板模型,采用了Moran’s I和Geary’s C指数对中国FDI与雾霾(PM_(2.5))污染空间自相关性进行了全域和局域分析。结果发现:(1)雾霾(PM_(2.5))污染与FDI存在显著的空间正相关性,证明了雾霾(PM_(2.5))污染空间的溢出效应以及FDI的辐射效应的存在。同时FDI高值集聚区域一般是雾霾(PM_(2.5))高值集聚区,FDI低值集聚区域一般是雾霾(PM_(2.5))低值集聚区,表明一个地区的引资效果和雾霾(PM_(2.5))污染在地理上的集聚密切相关。雾霾(PM_(2.5))污染表现出显著的"叠加效应"和"溢出效应",说明中国雾霾(PM_(2.5))污染在空间维度、时间维度以及时空维度上分别表现出交叉、累积、持续的演变特征。(2)全样本下,FDI对雾霾(PM_(2.5))浓度的影响表现出增促效应。FDI存量每升高1%,雾霾(PM_(2.5))浓度升高0.011%。(3)分地区样本下,东部城市FDI存量每升高1%,雾霾(PM_(2.5))浓度升高0.001 9%;中部城市FDI存量每升高1%,雾霾(PM_(2.5))浓度升高0.018 3%;而西部城市FDI存量对雾霾(PM_(2.5))浓度影响不显著。上述实证结果说明中国雾霾污染存在着显著的空间依赖性和区域异质性,FDI对中国大部分城市的雾霾污染存在显著的增促效应。 相似文献
980.
Toledo VE de Almeida Júnior PB Quiterio SL Arbilla G Moreira A Escaleira V Moreira JC 《Environmental monitoring and assessment》2008,139(1-3):49-59
The Oswaldo Cruz Foundation Campus (FIOCRUZ), in a suburban region of the city of Rio de Janeiro, was selected as a case study
to assess the pollution released from vehicle and industrial facilities in Basin III, the most polluted area of the city.
Concentrations of particulate matter (PM10) and trace metals in airborne particles were determined in an intensive field campaign.
The samplings were performed every six days for 24 h periods, using a PM10 high volume sampler, from September 2004 to August
2005. PM10 mass concentrations were determined gravimetrically and the metals by ICP-OES. For PM10, the arithmetic mean for
the period is 169 ± 42 μg m−3 which is 3.4 times the national recommended standard of 50 μg m−3. Additionally, 51% of the samplings exceeded the recommended 24 h limit of 150 μg m−3. Ca, Mg, Fe, Zn and Al were the metals that presented the higher concentrations. The correlation matrix gave two main clusters
and three significant principal components (PC). Both PC1 and PC2 are associated to crustal, vehicular and industrial emissions
while PC3 is mainly associated to geological material. Enrichment factors for Zn, Cu, Cd and Pb indicate that for these elements,
anthropic sources prevail over natural inputs. PM10 levels showed a good correlation with hospital admissions for respiratory
diseases in children and elderly people. 相似文献