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Результаты 1321-1330 из 1,546
Exposure assessment of pesticides in a shallow groundwater of the Tagus vulnerable zone (Portugal): a multivariate statistical approach (JCA) Полный текст
2012
Silva, Emília | Mendes, Maria Paula | Ribeiro, Luis | Cerejeira, Maria José
PURPOSE: To assess groundwater exposure to pesticides, in agricultural areas of ‘Ribatejo’ region (Portugal), and the influence of some key factors in that exposure, field, laboratory and modelling studies were carried out. METHODS: The study was performed in maize, potato, sugar beet, tomato and vegetables agricultural areas, located in a shallow aquifer, with pesticides use and, in most cases, with irrigation practices. Pesticides used in the studied agricultural areas and having leaching potential were selected, being considered also other pesticides included in priority lists, defined in Europe. Evaluation of groundwater exposure to pesticides was carried out by successively: (1) groundwater sampling in seven campaigns over the period 2004–2006; (2) pesticide analysis [including isolation and concentration from the groundwater samples and further determination by gas chromatography–mass spectrometry (GC–MS) of 14 herbicides, four insecticides and two metabolites]; and (3) analysis and discussion of the results by applying joint correspondence analysis (JCA). RESULTS: From the 20 pesticides and metabolites selected for the study, 11 were found in groundwater. Pesticides and metabolites most frequently detected were atrazine, alachlor, metolachlor, desethylatrazine, ethofumesate, α-endosulfan, metribuzine, lindane and β-endosulfan. The results showed that groundwater exposure to pesticides is influenced by local factors—either environmental or agricultural, as precipitation, soil, geology, crops and irrigation practices. Spring and autumn were more associated with the detection of pesticides being more likely to observe mixtures of these compounds in a groundwater sample in these transition seasons. CONCLUSIONS: This work evidences the importance of models, which evaluate pesticides environmental behaviour, namely their water contamination potential (as Mackay multicompartimental fugacity model) and, specially, groundwater contamination potential (as GUS and Bacci and Gaggi leaching indices), in pesticide selection. Moreover, it reveals the importance to adapt proper statistical methods according to level of left-censored data. Using JCA was still possible to establish relations between pesticides and their temporal trend in a case study where there were more than 80% of data censored. This study will contribute to the Tagus river basin management plan with information on the patterns of pesticide occurrence in the alluvial aquifer system.
Показать больше [+] Меньше [-]Cloud point extraction for the preconcentration of palladium and lead in environmental samples and determination by flow injection flame atomic absorption spectrometry : CPE for preconcentration of Pd and Pb by FI-FAAS Полный текст
2012
Bakircioglu, Dilek
PURPOSE: An online cloud-point extraction (CPE) coupled with flow injection method is developed for the separation and preconcentration of palladium and lead from various matrices using flame atomic absorption spectrometry (FAAS). METHOD: The method employs the formation of complexes of the metallic species with dimethylglyoxime, which are subsequently entrapped in the micelles of the surfactant Triton X-114, upon increase of the solution temperature to 60°C and loaded into the flow injection system at a flow rate of 4.6 mL min−1. The surfactant rich-phase was retained in a minicolumn packed with animal wool at pH 6 and eluted with 1.0 mol L−1 nitric acid in methanol at a flow rate of 1.1 mL min−1 directly into the nebulizer of the FAAS. The CPE variables and flow injection conditions affecting the analytical performance of the combined methodology was studied and optimized. RESULTS: Under the optimized conditions for 25 mL of preconcentrated solution, the enrichment factors were 51 and 44, and the limit of detections were 1.0 and 1.4 ng mL−1 for palladium and lead, respectively. Finally, the developed method was applied for the determination of palladium and lead in street dust, soil, radiology waste, catalytic converter, and urban aerosol samples. CONCLUSIONS: Cloud-point extraction coupled with flow injection-FAAS was proposed as an effective preconcentration and separation method for Pd and Pb determination in radiology waste, road dust, soil, and urban aerosol samples. The most favorable feature of this method is its much higher selectivity, sensitivity, rapidity, good extraction efficiency, and employs the green chemistry concept, as it does not require the addition of toxic chemicals. In addition, this proposed method gives very low detection limits and good relative standard.
Показать больше [+] Меньше [-]Interpretation of ground-level ozone episodes with atmospheric stability index measurement Полный текст
2012
Zhang, Zhenyi | Wang, Fenjuan | Costabile, Francesca | Allegrini, Ivo | Liu, Fenglie | Hong, Weimin
PURPOSE: This paper presents a novel approach to interpret ground-level O3 with the measured atmospheric stability index (ASI). METHODS: O3 concentrations were monitored by automatic analysers at three types of stations: traffic site, residential site and regional background site in 2005, and the ASI was simultaneously measured by observing radon and its short-lived decay products. RESULTS: The observed results showed a clear annual variation of O3 concentrations with a maximum in spring, relatively high at the regional background site over 120 ppb, and lower at the residential and traffic sites at about 70 ppb. ASI gives information about the dilution properties of the lower boundary layer and allows to highlight the relevant role of the dilution factor in determining atmospheric pollution events. We demonstrated the analysis of O3 night peak episodes with vertical wind and ASI. CONCLUSIONS: With the advantage of ASI and vertical wind profiles, it was possible to isolate particular photochemical pollution phenomena of O3 peaks from the free troposphere reservoir or formed by local reactions. This shows that the index constitutes a powerful and valuable tool for describing O3 night-peak episodes at background station.
Показать больше [+] Меньше [-]Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009 Полный текст
2012
Li, Yi | Tang, Jie | Yu, Xiaolan | Xu, Xiaobin | Cheng, Hongbing | Wang, Shufeng
INTRODUCTION: Trends in precipitation pH and conductivity during 1992–2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35–5.01 and showed a statistically very significant (P < 0.01) decreasing trend with time. Annual mean conductivity showed a statistically significant (P < 0.05) increasing trend, although this was not the case for non-H conductivity. Increasing rainwater acidity was mainly caused by increasing amounts of acid substances entering the rain. The trends in precipitation pH and conductivity were directly associated with energy consumption. RESULTS AND DISCUSSIONS: Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO 4 2− and NO 3 − were the main anions, and NH 4 + and Ca2+ the main cations. The anion to cation ratio was 0.8–1.0, and that of [SO 4 2− ] to [NO 3 − ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH 4 + ] to [Ca2+] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl−] to [Na+] was about 0.67, somewhat lower than that of natural precipitation. CONCLUSIONS: Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.
Показать больше [+] Меньше [-]Long-term trends of continental-scale PCB patterns studied using a global atmosphere–ocean general circulation model Полный текст
2012
Stemmler, Irene | Lammel, Gerhard
Continental-scale distribution and inter-continental transport of four polychlorinated biphenyl (PCB) congeners (28, 101, 153, 180) from 1950 to 2010 were studied using the global multicompartment chemistry transport model MPI-MCTM. Following identical primary emissions for all PCB congeners into air, most of the burden is stored in terrestrial (soil and vegetation) compartments. Thereby, PCB-28, PCB-101 and PCB-153 show a shift of the soil burden maxima from source to remote regions. This shift is downwind with regard to the westerlies for Eurasia and upwind for North America and more prominent for the lighter PCBs than for PCB-153 or PCB-180. In meridional direction, all congeners’ distributions underwent a northward migration in Eurasia and North America since the 1950s. Inter-continental transport from Eurasian sources accounts largely for contamination of Alaska and British Columbia and determines the migration of the PCB distribution in soil in North America. Trans-Pacific transport occurs mainly in the gas phase in boreal winter (December–January–February) at 3–4 km altitude and is on a multi-year time scale strongly linked to the atmospheric pressure systems over the Pacific. Inter-continental transport of the lighter, more volatile PCBs is more efficient than for the heavier PCBs.
Показать больше [+] Меньше [-]Development of a country-specific CO₂ emission factor for domestic anthracite in Korea, 2007–2009 Полный текст
2012
Lee, Jeongwoo | Kim, Jinsu | Kim, Seungjin | Im, Gikyo | Lee, Seehyung | Jeon, Eui-Chan
INTRODUCTION: Korea has been making efforts to reduce greenhouse gas (GHG) emissions, including a voluntary commitment to the target of a 30% reduction, based on business-as-usual of the total GHG emission volume, by 2020; 2006 IPCC Guidelines provided default values, applying country-specific emission factors was recommended when estimating national greenhouse gas emissions. RESULTS AND DISCUSSION: This study focused on anthracite produced in Korea in order to provide basic data for developing country-specific emission factor. This study has estimated CO₂ emission factors to use worksheet of which five steps consisted according to the fuel analysis method. CONCLUSION: As a result, the average of net colorific value for 3 years (2007∼2009) was 4,519 kcal/kg, and the CO₂ emission factor was calculated to be 111,446 kg/TJ, which is about 11.8% lower than the 2006 IPCC guidelines default value, and about 7.9% higher than the US EPA emission factor.
Показать больше [+] Меньше [-]Exploratory data analysis in the study of 7Be present in atmospheric aerosols Полный текст
2012
García, F Piñero | García, M. A Ferro | Drożdżak, J. | Ruiz-Samblás, C.
PURPOSE: Exploratory data analysis (EDA) is applied in this research to study the behavior of radioactive aerosols present in the surface atmosphere of Granada, using 7Be as radiotracer. The reason for this study is to reduce the large number of parameters involved in understanding their behavior, given the complexity of the atmosphere. METHODS: Aerosol particles were collected weekly in Granada (Spain) over a 5-year period. Low-background gamma spectrometry was used to determine concentrations of 7Be-aerosol activity. The variables studied were: 7Be concentration, cosmic ray intensity, temperature, temperature interval, rainfall, relative humidity, and Saharan intrusions. Least significant difference test (LSD), hierarchical cluster analysis (HCA), and principal component analysis (PCA) with varimax rotation have been applied to study the datasets. RESULTS AND DISCUSSION: The results of our study reveal that aerosol behavior is represented by two principal components which explain 86.23 % of total variance. Components PC1 and PC2 respectively explain 74.61 and 11.62 % of total variance. PC1 explains the cyclical and seasonal pattern of the samples, while PC2 is related to the production of 7Be. In addition, PCA and HCA show good distribution of the samples by families with two groups, summer and winter, at the extremes and spring–autumn in the middle. This result corroborates that there are no differences between spring and autumn in the climate of Granada. CONCLUSIONS: EDA has been found to be quite useful in studying the behavior of radioactive aerosols in the surface atmosphere of a city with the climate and geographical characteristics of Granada.
Показать больше [+] Меньше [-]Biodegradability and ecotoxicitiy of tramadol, ranitidine, and their photoderivatives in the aquatic environment Полный текст
2012
Bergheim, Marlies | Gieré, Reto | Kümmerer, Klaus
PURPOSE: This study was designed to assess the fate and the overall potential impacts of the widely prescribed drugs ranitidine and tramadol after their introduction into the aquatic environment. METHODS: The probability to detect these two drugs in the aquatic environment was studied by analyzing their abiotic and biotic degradation properties. For this purpose, samples were irradiated with different light sources, and three widely used biodegradability tests from the OECD series, the closed bottle test (OECD 301 D), the manometric respirometry test (OECD 301 F) and the Zahn–Wellens test (OECD 302 B), were conducted. The ecotoxicity of the photolytically formed transformation products was assessed by performing the bacterial growth inhibition test (EN ISO 10712). Furthermore, quantitative structure–activity relationship analysis and a risk analysis based on the calculation of the predicted environmental concentrations have also been conducted to assess the environmental risk potential of the transformation products. The possible formation of stable products by microbial or photolytical transformation has been investigated with DOC and LC-MS analytics. RESULTS: In the present study, neither ranitidine, nor tramadol, nor their photoderivatives were found to be readily or inherently biodegradable according to test guidelines. The photolytic transformation was faster under a UV lamp compared to the reaction under an Xe lamp with a spectrum that mimics sunlight. No chronic toxicity against bacteria was found for ranitidine or its photolytic decomposition products, but a low toxicity was detected for the resulting mixture of the photolytic transformation products of tramadol. CONCLUSIONS: The study demonstrates that transformation products may have a higher environmental risk potential than the respective parent compounds.
Показать больше [+] Меньше [-]Invertebrates control metal/metalloid sequestration and the quality of DOC/DON released during litter decay in slightly acidic environments Полный текст
2012
Schaller, Jörg | Machill, Susanne
Plant litter and organic sediments are a main sink for metals and metalloids in aquatic ecosystems. The effect of invertebrate shredder (a key species in litter decay) on metal/metalloid fixation by organic matter is described only under alkaline water conditions whereas for slightly acidic waters nothing can be found. Furthermore, less is known about the effect of invertebrate shredders on the quality of dissolved organic carbon (DOC) and nitrogen (DON) released during litter decay. We conducted an experiment to investigate the impact of invertebrate shredder (Gammarus pulex) on metal/metalloid fixation/remobilization and on the quality of DOC/DON released under slightly acidic water conditions. During decomposition of leaf litter, invertebrate shredder facilitated significantly the emergence of smaller particle sizes of organic matter. The capacity of metal fixation was significantly higher in smaller particles (POM 2,000–63 μm) compared to original leaf litter and litter residues. Thus, G. pulex enhanced metal fixation by organic partition of sediments by increasing the amount of smaller particle of organic matter in aquatic ecosystems. In contrast, the capacity of metal/metalloid fixation in the smallest fraction of POM (<63 μm) was lower compared with leaf residues in treatment without invertebrates. Remobilization of metals and metalloids was very low for all measured elements. A significant effect of invertebrates on quantitative formation of DOC/DON was confirmed. The quality of released DOC/DON, which may affect metal/metalloid remobilization, was also significantly affected by invertebrate shredders (e.g., more carboxylates). Hence, invertebrate shredder enhanced significantly the fixation of metals/metalloids into POM in slightly acidic environments.
Показать больше [+] Меньше [-]Metal pollution does not bias offspring sex ratio in great tit (Parus major) Полный текст
2012
Eeva, Tapio | Sillanpää, Saila | Lehikoinen, Esa
PURPOSE: We measured offspring sex ratios in a resident insectivorous passerine bird, the Great tit Parus major, to find out whether metal pollution around a Finnish copper smelter would bias sex ratios in this territorial forest bird species. Besides a direct effect of pollutants, we were interested in possible indirect effects of pollution-related resource limitation, i.e., changes in food quality and quantity, on sex ratio. METHODS: We manipulated the diet quantity and quality (carotenoid levels) of P. major nestlings in polluted and unpolluted environments to find out if variation in dietary resource levels has any effect on fledgling sex ratios. Faecal metal levels of nestlings were analysed to monitor the level of pollution exposure at each territory. Near the time of fledging (at the age of 15 days), feather samples were collected for molecular sex determination. RESULTS: We did not find any association between metal exposure levels and offspring sex ratio, and thus, our results do not support the hypothesis that metal pollution would have direct effects on P. major offspring sex ratio. We found that, irrespective of pollution level, high nestling mortality was associated with male-biased sex ratio, most likely due to sex-specific mortality. Our feeding treatment, however, showed no significant effects on offspring sex ratio, possibly because natural variation in food availability outweighed the effect of our food manipulation on nestling mortality. CONCLUSIONS: We conclude that metal exposure at the levels found in our study area does not bias fledgling sex ratios in this species, but biased sex ratios may follow under natural or pollution-related resource limitation.
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