Investigation of interactions between surface water and petroleum-type pollutants

Background, Aims and Scope In oil spill investigations, one of the most important steps is a proper choice of approaches that imply an investigation of samples taken from different sedimentary environments, samples of oil contaminants taken in different periods of time and samples taken at different distances from the oil spill. In all these cases, conclusion on the influence of the environment, microorganisms or migration on the oil contaminants' composition can be drawn from the comparison of chemical compositions of the investigated contaminants. However, in case of water contaminants, it is very important to define which part of organic matter has been analyzed. Namely, previous investigations showed that there were some differences in chemical composition of the same oil contaminant depending on the intensity of its contact with ground water. The aim of this work is to define more precisely the interactions between oil contaminant and water, i.e. the influence of the intensity of interaction between the oil contaminant and water on its chemical composition. The study was based on a comparison of four fractionated extracts of an oil pollutant, after they had been analyzed in details. Methods Oil polluted surface water (wastewater canal, Pančevo, Serbia) was investigated. The study was based on a comparison of four extracts of an oil contaminant: extract 1 (decanted part), and extracts 2, 3 and 4 (extracted by shaking for 1 minute, 5 minutes and 24 hours, respectively). The fractionated extracts were saponified with a solution of KOH in methanol, and neutralized with 10% hydrochloric acid. The products were dissolved in a mixture of dichloromethane and hexane, and individually fractionated by column chromatography on alumina and silica gel (saturated hydrocarbon, aromatic, alcohol and fatty acid fractions). n-Alkanes and isoprenoid aliphatic alkanes, polycyclic alkanes of sterane and triterpane types, alcohols and fatty acids were analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). δ13CPDB values of individual n-alkanes in the aliphatic fractions were determined using gas chromatography-isotope ratio monitoring-mass spectrometry (GC-irmMS). Results and discussion. Extracts 1 and 2 are characterized by uniform distribution of n-alkanes, whereas extract 3 is characterized by an even-numbered members dominating the odd-ones, and extract 4 showed a bimodal distribution. Extract 1 is characterized by the least negative δ13CPDB values of C19-C26 n-alkanes. Sterane and triterpane analysis confirmed that all extracts originated from the same oil contaminant. n-Fatty acids, C19-C24, in all extracts are very low, being somewhat higher in extract 4. Even-numbered n-alcohols, C12–C16, were identified in the highest concentration in extract 3. It was assumed that algae were responsible for the composition of extract 3. Furthermore, a possible reason for higher concentrations of C19–C26 n-alkanes and C19–C24 fatty acids in extract 4 is the formation of inclusion compounds with colloidal micelles formed between the oil contaminant's NSO-compounds and water. Conclusion It was undoubtedly confirmed that there were specific differences in the compositions of the different extracts depending on the intensity of the interaction between the oil contaminant and the surface water. Recommendation and Outlook. When comparing the composition of oil contaminants from different water samples (regardless of the ultimate investigation goal) it is necessary to compare the extracts isolated under the same conditions, in other words, extracts that were in the same or very similar interaction with water.     

水中有机污染物超声强化氧化技术研究进展

超声波技术在化学、环境、制药以及生物等领域有着广阔的应用前景。在降解水中难降解有机污染物方面 ,超声强化氧化技术有一定优势 ,降解效果显著 ,符合绿色环保技术的要求。超声强化氧化技术主要可分为超声空化技术、超声强化化学 (催化 )氧化技术、超声强化电化学 (催化 )氧化技术、超声强化光化学 (催化 )氧化技术、超声 生物降解等几大类 ,本文对各类技术的优缺点进行了评述。     

AN INTEGRATIVE APPROACH TOWARDS UNDERSTANDING ECOLOGICAL RESPONSES TO DAM REMOVAL: THE MANATAWNY CREEK STUDY1

ABSTRACT: Dam removal has been proposed as an effective method of river restoration, but few integrative studies have examined ecological responses to the removal of dams. In 1999, we initiated an interdisciplinary study to determine ecological responses to the removal of a 2 m high dam on lower Manatawny Creek in southeastern Pennsylvania. We used an integrative monitoring program to assess the physical, chemical, and biological responses to dam removal. Following removal in 2000, increased sediment transport has led to major changes in channel form in the former impoundment and downstream reaches. Water quality did not change markedly following removal, probably because of the impoundment's short hydraulic residence time (less than two hours at base flow) and infrequent temperature stratification. When the impoundment was converted to a free flowing reach, the composition of the benthic macroinvertebrate and fish assemblages in this portion of Manatawny Creek shifted dramatically from lentic to lotic taxa. Some fish species inhabiting the free flowing reach downstream from the dam were negatively affected by large scale sediment transport and habitat alteration following dam removal, but this appears to be a short term response. Based on our observations and experiences in this study, we provide a list of issues to evaluate when considering future dam removals.     

Removal of organic contaminants from water or wastewater with liquefied gases

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Metallic contaminant profiles in sediment cores from Lake Valencia,Venezuela

Total extractable concentrations of AI, Fe, Mn, Pb, Cu, Zn, Hg and organic carbon (C_org) were determined along four sediment cores from Lake Valencia. In one selected core, the percentage labile fractions were determined in order to establish anthropic enrichment factors, the depth reached by the contaminants and their mobilities. The distribution patterns of concentration versus depth reflect the original concentrations of the settling sediments. Only Mn seems to show diagenetic cycling. No enrichment of Fe and Mn occurs in the upper part of the cores, in spite of good water circulation and aeration of bottom lake waters during five months of the year. This immobility can be attributed to the high pH of water (7.6 – 8.9). Pb, Zn, Cu and Hg are enriched in the upper part of the cores, probably reflecting the input of contaminants. These elements show enrichment factors of up to 3.0. Background concentrations of the studied metals are reached below a depth of 30 cm.     

挡水板高度对倾斜土槽污染物去除效果的影响

采用干湿交替方法,用5层倾斜土槽装置填充蜂窝煤渣和砂壤土等附着材料,探讨3种不同挡水板高度(90 mm、60 mm和30 mm)处理对模拟生活污水污染指标去除率的影响。结果表明:3种处理对污水中BOD5、COD、TP的去除率均在87%～95%以上、TN的去除率在69%～80%之间,对COD、TP平均去除率的影响不显著,但对BOD5和TN有显著影响,其平均去除率的顺序为:去除率90 mm≈去除率60 mm>去除率30 mm。本试验条件下采用60 mm为最适合水板高度,以满足装置一定污水流量的处理负荷。     

Vectors and Timing of Freshwater Invasions in Great Britain

Abstract: Nonindigenous freshwater species cause large ecological and economic impacts in Great Britain. In response the government is in the process of implementing a broad, new nonindigenous species strategy. We assembled a list of all nonindigenous freshwater species that are or were established in Great Britain, their date of first record, and their vector of introduction. This list provides a baseline against which the success of new policies can be assessed. Because the biota of Great Britain has been well recorded, our results provide a highly resolved case study of the vectors and drivers of species transport and establishment. A total of 117 nonindigenous freshwater species are currently established in Great Britain; a further 17 species were once established but are now extirpated. Between 1800 and 2000 the number of established species increased at an accelerating rate, and this increase correlated with the growth in human population and gross domestic product. The construction of large reservoirs in Great Britain occurred over a short period and overlapped high rates of new species establishment, indicating that habitat modification may have been an important driver of establishment. Nonindigenous species now account for 24% of fish, 12% of plant, 54% of amphibian, and 88% of decapod crustacean freshwater species richness in Great Britain. The ornamental trades have been responsible for the greatest percentages of intentionally (73%) and unintentionally (34%) introduced species that have become established. Shipping and aquaculture have also been strong vectors. These vectors should be prioritized for management within the new nonindigenous species strategy.     

卤代有机污染物抑制甲状腺激素代谢酶活性的研究进展

甲状腺激素(thyroid hormones,THs)对生物体细胞的正常发育和分化至关重要,甲状腺激素失调可引起中枢神经系统、肺、心血管和其他器官的异常发育。研究表明,环境中的卤代有机污染物(halogenated organic contaminants,HOCs)及其代谢产物具有甲状腺激素干扰效应。抑制参与THs代谢的生物酶,例如磺基转移酶(sulfotransferases,SULTs)和脱碘酶(deiodinases,DIs),是HOCs及其代谢产物干扰THs正常功能的重要方式。本文重点综述了HOCs对不同甲状腺激素代谢酶的抑制效应的研究,讨论了环境计算化学和预测毒理学方法在该领域的重要应用,期望为HOCs干扰甲状腺激素酶代谢活性的深入研究提供借鉴与参考。     

Decomposition of aqueous chlorinated contaminants by UV irradiation with H2O2

In the present study, the decomposition rates of carbon tetrachloride (CCl₄) and 2,4-dichlorophenol (2,4-DCP) in water by the ultraviolet (UV) light irradiation alone and H₂O₂/UV were experimentally investigated. The detailed experimental studies have been conducted for examining treatment capacities of the two different ultraviolet light sources (low and medium pressure Hg arc) in H₂O₂/UV processes. The low or medium UV lamp alone resulted in a 60%–90% decomposition of 2,4-DCP while a slight addition of H₂O₂ resulted in a drastic enhancement of the 2,4-DCP decomposition rate. The decomposition rate of 2,4-DCP with the medium pressure UV lamp alone was about 3–6 times greater than the low pressure UV lamp alone. In the direct photolysis of aqueous CCl₄, the medium pressure UV lamp had advantage over the low pressure UV lamp because the molar extinction coefficient of CCl₄ at shorter wavelength (210–220 nm) is about 20 to 50 times higher than that at 254 nm. However, adding H₂O₂ to the medium pressure UV lamp system rendered a negative oxidation rate because H₂O₂ acted as a UV absorber being competitive with CCl₄ due to negligible reaction between CCl₄ and OH radicals. The results from the present study indicated significant influence of the photochemical properties of the target contaminants on the photochemical treatment characteristics for designing cost-effective UV-based degradation of toxic contaminants.     

Modeling the combined effect of nutrients and pyrene on the plankton population: Validation using mesocosm experiment data and scenario analysis

A new integrated model that includes a hydrodynamic model coupled with a contaminant fate and effect sub-model and an ecological sub-model is presented and validated using data from mesocosm experiments. The experiments were carried out in the Isefjord (Denmark) and include the combined effects of nutrients and pyrene addition on the lower trophic levels of bacteria, zooplankton and phytoplankton. The model was able to correctly represent the main dynamics observed in the mesocosms during the 11 days of the experiment and thereby confirmed that it is possible to represent short-term changes in the system with a simplified food-web model on a small spatial and temporal scale. Finally, the validated model was used to carry out a scenario analysis to investigate the effects of a contaminant pulse at different pyrene concentrations and different release timings. Results showed that the ecosystem's vulnerability to a pyrene pulse depends on the initial condition of the system. Stronger biomass reduction was observed when the pulse was released during the zooplankton bloom. Conversely, when the pulse was added at low biomass and before the bloom, the system showed a tendency to behave non-linearly.