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751.
Zygmunt Usydus Joanna Szlinder-Richert Lucyna Polak-Juszczak Katarzyna Komar Maria Adamczyk Magorzata Malesa-Ciecwierz Wiesawa Ruczynska 《Chemosphere》2009,74(11):1420-1428
Chemical analyses were performed on one hundred and twenty of the most popular varieties of fish products (smoked fish, salted fish, and marinated fish) of the fish market in Poland. The contents of the nutritive substances of fish products (protein, micro- and macronutrients, vitamins A1, D3, E, and fatty acids) and the chosen contaminant (toxic metals – mercury, cadmium, lead, arsenic; dioxin/furans – PCDDFs; dioxin-like PCB – dl-PCBs; seven congeners of polybrominated diphenyl ethers – PBDEs; organochlorine pesticides – ΣDDT, HCB, ΣHCH and marker polychlorinated biphenyls – PCB7) levels were determined. It was confirmed that fish products are a good source of digestible proteins, iodine, selenium, and vitamin D3. The fundamental nutritive benefit of processed fish lies in its highly beneficial fatty acid composition, which is what imparts them healthy nutritive qualities. The high content of long-chain polyunsaturated fatty acids (LC-PUFAs), which is not noted in other food products, is particularly important.The majority of contaminants studied were present in low levels. The possible threats, particularly in the case of pregnant/nursing women and young children, can pose the levels of dioxin/furans (PCDD/Fs) and dioxin-like (dl-PCBs) in smoked Baltic salmon and smoked sprat, elevated in a relation to particular requirements concerning the content of sum of PCDD/Fs and dl-PCBs in fish (8 pg WHO-TEQ g−1).The health benefits and risks stemming from consumption of fish products were determined according to the Provisional Tolerable Weekly Intake (PTWI) for chosen contaminants (Cd, Hg, As, PCDD/Fs + dl-PCB) and the quantity of ingredients that render a fish diet healthy based on data from the EFSA Journal [EFSA (European Food Safety Authority), 2005. Opinion of the scientific panel on contaminants in the food chain on a request from the European Parliament related to the safety assessment of wild and farmed fish. EFSA J. 236, 1–118]. In regard of high content of LC-PUFAa and other nutritive ingredients, fish products available in Polish market may be considered as healthy food.However, many authors point at contaminants (methylmercury, PCDD/Fs) occurring in fish and fish products as on potential health problem, and emphasize that the amount of that hazardous substances should be limited in human diet. 相似文献
752.
An improved method, a palladium-catalyzed cross-coupling reaction the so-called Suzuki-coupling, was used to synthesize 19 monofluorinated analogues (F-PCBs) of polychlorinated biphenyls (PCBs), including analogues of PCBs 28, 52 and 81. The coupling of chlorinated and/or fluorinated isomers of aryl boronic acids with bromo- and/or iodobenzenes gave the desired F-PCB congeners in good to excellent yields. The self-coupling product of the aryl boronic acids was the major impurity, but this limitation could be minimized. The influence of ortho-substitution by chlorine on the reaction time was studied in detail. The F-PCBs were characterized by means of 1H and 19F NMR and mass spectrometry (MS). F-PCBs show remarkably similar characteristics in many aspects to those of the corresponding non-fluorinated parent PCBs. Since fluorine is generally resistant to degradation, once incorporated into a substrate it functions as an indelible label that can be used to monitor structures and dynamics. F-PCBs may prove their usefulness as markers and tracers in mechanistic and toxicological studies. The aim of further research will be to test the suitability of fluorine as a sensitive probe in a broad range of applications, including synthesis, analytical, mechanistic and toxicological studies. 相似文献
753.
Valto P Knuutinen J Alén R 《Environmental science and pollution research international》2009,16(3):287-294
Background, aim, and scope In papermaking, there is a continuous interest both to minimize fresh water consumption and to reduce discharges into the
environment. These general trends mean an increase in the amounts of detrimental substances, such as resin and fatty acids,
in papermaking process waters. Resin acids, in particular, are responsible for much of the toxicity typically present in paper
mill effluents and, for this reason, the routine and rapid monitoring of these compounds in various process streams is necessary.
This also means that there is a continuous need to develop straightforward offline and online techniques to clarify problems
occurring, for example, as a result of the introduction of more intensively closed systems of water circulation. In the present
study, we describe the use of a novel, online, sample enrichment technique followed by atmospheric pressure chemical ionization–mass
spectrometry (APCI-MS) suitable for monitoring the concentration levels of common resin and fatty acids in papermaking process
waters.
Materials and methods The representative process water samples were taken from the grinding zone of a thermomechanical pulping mill. The samples
were first preconcentrated in a precolumn C18, and the analytes were transferred online to MS. The high intensive [M–H]− ion was used for the identification of each analyte since, according to the present ionization method, no other fragmentation
was observed. Laboratory-scale, online measurements with an online sample feed were carried out by connecting a centrifugal
pump and a ceramic filter to the APCI-MS.
Results Quality parameters, such as repeatability, linearity, and limit of detection (LOD), were determined by using dehydroabietic
acid (DHAA) in order to evaluate the suitability of the method for the rapid screening of concentration levels. This method
provided satisfactory linearity and a good correlation between analyte concentration and peak area. The suitability of the
system for the continuous analysis of the same acids was evaluated in laboratory-scale, online experiments. In all cases,
the response to changes in the analyte concentration was linear, and the repeatability of the system was also satisfactory.
Discussion Only a few studies have been published on the analysis of resin and fatty acids with MS techniques. The present method was
applied to the monitoring of dehydroabietic, oleic, and stearic acids. The quality parameters were highly comparable with
those reported earlier, and the LOD values of the DHAA were below the levels usually encountered in process waters. The quality
parameters were only slightly higher than those obtained by the traditional methods of analysis, probably due to the absence
of an effective sample clean-up before analysis.
Conclusions The results of the laboratory-scale, online experiments indicated that the online enrichment APCI-MS system is a suitable
alternative for monitoring the concentration levels of selected resin and fatty acids in papermaking process waters. The method
can be used, for example, to provide useful information about the concentration levels of these acids in different stages
of the process, thus signaling possibly impending problems. In general, faster and simpler measurements are needed to meet
the requirements for a reduction in fresh water usage in papermaking.
Recommendations and perspectives Compared to the conventional methods used for this purpose, the main benefits of the method are rapidity of measurement, simplicity
of use, and absence of the need for multistage sample treatments (short analysis time). For this reason, this online method
is more suitable for the control of papermaking by analyzing the concentration levels of interfering substances (i.e., selected
resin and fatty acids) than an offline analysis detailing all the individual extractives-based compounds in process streams.
It is also obvious that the technique can easily be modified for other environmental pollutants as well. 相似文献
754.
Xinghui Xia Gongchen Li Yumin Chen 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1352-1359
With an Xe arc lamp house as simulated sunlight, the influences of fulvic acid (FA) concentration and origins on photodegradation of acenaphthene, fluorine, phenanthrene, fluoranthene and pyrene in aqueous solution have been studied. Similar effects of FAs, collected from five places around China, on polycyclic aromatic hydrocarbon (PAH) photodegradation have been observed. Active oxygen was of significance in PAH photodegradation with the presence of FAs. For systems with 1.25 mg L−1 FAs, the contributions of OH to PAH photodegradation rates were from 33% to 69%. FAs had two opposite effects, i.e., stimulating the generation of active oxygen and advancing PAH photodegradation; competing with PAHs for energy and photons and restraining PAH photodegradation. Generally, photodegradation rates of the 5 PAHs decreased with the increase of FAs concentration; except fluoranthene and pyrene were advanced in solutions with low FA concentration. The influences of FA concentration on PAH photodegradation were more significant than FA origin. 相似文献
755.
The production of copolymers of poly-β-hydroxyalkanoates (PHA) is generally a high cost process. To reduce the production costs, inexpensive carbon sources such as volatile fatty acids (VFAs) from acidified wastewater can be used. Therefore, isolation of bacterial strains that can produce PHA copolymers using VFAs as a sole carbon source would be a beneficial alternative. In this study, a strain of PHA accumulating bacterium was isolated from the wastewater treatment plant of a soybean processing facility in Harbin. The strain was identified as γ-proteobacterium according to its 16S rDNA information and was originally named as strain WD-3. The strain accumulated a mass of PHA up to 45% of its dry cell weight when it was cultured under the optimum fermentation condition in this study when butyrate was used as the carbon source. In addition, WD-3 could synthesize PHA copolymers of poly-hydroxybutyrate and poly-hydroxyvalerate (PHV) either from C-even substrates or from C-odd substrates, and one-third of the copolymer was PHV. Results from this study demonstrated that small molecule organic acids can be used by the strain of WD-3 as the carbon source for growth and PHA production. The maximum PHA yield in the study was 0.45 g g−1 dry cell. 相似文献
756.
The removal of organic precursors of disinfection by-products (DBPs), i.e. natural organic matter (NOM), prior to disinfection and distribution is considered as the most effective approach to minimise the formation of DBPs. This study investigated the impact of the addition of powdered activated carbon (PAC) to an enhanced coagulation treatment process at an existing water treatment plant on the efficiency of NOM removal, the disinfection behaviour of the treated water, and the water quality in the distribution system. This is the first comprehensive assessment of the efficacy of plant-scale application of PAC combined with enhanced coagulation on an Australian source water. As a result of the PAC addition, the removal of NOM improved by 70%, which led to a significant reduction (80-95%) in the formation of DBPs. The water quality in the distribution system also improved, indicated by lower concentrations of DBPs in the distribution system and better maintenance of disinfectant residual at the extremities of the distribution system. The efficacy of the PAC treatment for NOM removal was shown to be a function of the characteristics of the NOM and the quality of the source water, as well as the PAC dose. PAC treatment did not have the capacity to remove bromide ion, resulting in the formation of more brominated DBPs. Since brominated DBPs have been found to be more toxic than their chlorinated analogues, their preferential formation upon PAC addition must be considered, especially in source waters containing high concentrations of bromide. 相似文献
757.
The spectroscopic studies of humic acid extracted from sediment collected at different seasons 总被引:1,自引:0,他引:1
Gocza?kowice Reservoir is the biggest water reservoir in the south of Poland. For our studies bottom sediments were collected from eight different places of the reservoir at various seasons of the year.EPR spectroscopy was applied to analyse both quantitatively and qualitatively the humic acids (HA) present in the samples. EPR spectra of the extracted HA exhibited broad lines from the paramagnetic metal ions and narrow lines from free radicals. The values of the free radical concentration obtained for HA amounted to 1.14-13.6 × 1016 spin g−1 depending on the season and the place of sample collection. The values of the g factor obtained for HA were of the range 2.0027-2.0035.The EPR studies show that HA extracted from bottom sediment collected at various points of the Gocza?kowice Reservoir exhibit similar physical-chemical properties. It was also observed that the depth of the reservoir affects the content of the oxygen functional groups as well as the free radical concentration in HA.The identification of the functional groups was done by means of IR. UV/VIS spectroscopy was used to estimate the maturity of the HA. 相似文献
758.
Characterization of extractable and non-extractable polycyclic aromatic hydrocarbons in soils and sediments from the Pearl River Delta, China 总被引:1,自引:0,他引:1
Formation of bound residues of pollutants in soils and sediments is an important process to control the fate of pollutants in the environment. The most of bound residue is not solvent extractable. In this paper, we measured both extractable and non-extractable polycyclic aromatic hydrocarbons (PAHs) in different organic matter fractions of samples from the Pearl River Delta, China. Non-extractable PAHs concentration was 234.45-1424.57 μg/kg and accounted for 33.78-57.44% of total PAHs. 2-3 Ring PAHs were the dominant species and differed in concentration substantially between the samples. The atomic ratio of PAHs over organic-C in the fractions ordered as solvent soluble organic matter > humin > humic acids, matching the content of aliphatic moieties in the fractions of organic matter. The ratio of extractable and non-extractable PAHs may relate to the aging process of PAHs in soil and sediment. 相似文献