A laboratory bench procedure was developed to efficiently extract naphthenic acids from bulk volumes of Athabasca oil sands tailings pond water (TPW) for use in mammalian oral toxicity testing. This solvent-based procedure involved low solvent losses and a good extraction yield with low levels of impurities. Importantly, labour-intensive centrifugation of source water to remove solids was avoided, allowing processing of much larger volumes of water compared with previous protocols. Naphthenic acids, present at an estimated concentration of 81 mg/l, were procured from 515.5 l of TPW at an overall extraction efficiency of approximately 85%. By using distillation to recover and recycle solvent, a high solvent:water ratio was maintained while actual solvent consumption was limited to 70 ml per liter of water processed. Electrospray ionization mass spectrometry suggested a highly heterogeneous naphthenic acid mixture that exhibited nearly identical proportions of monocyclic, polycyclic, and acyclic acids with molecular weights primarily between 220 and 360. Biphenyls, naphthalenes, and phenanthrene/anthracene were the most prominent impurities detected, but their levels were low (< or = 13 microg/l) even in a concentrated solution of the naphthenic acids (8549 mg/l). Naphthenic acids stored at 4 degrees C at this concentration were stable, exhibiting no significant change in concentration over a 10-month period. This bulk isolation procedure should be useful to others needing to process large volumes of tailings or other source water for the purpose of procuring moderate amounts of naphthenic acids. 相似文献
The effect of ammonium concentration on photosynthetic activity estimated as in vivo chlorophyll fluorescence, i.e. maximal quantum yield (Fv/Fm) and electron transport rate (ETR) and on the accumulation of mycosporine-like amino acids (MAAs), chlorophyll a (chl a), biliproteins (BP) and soluble proteins (SP) in the red algae Porphyra leucosticta Thuret in Le Jolis collected from Lagos (Málaga, Spain) and Porphyra umbilicalis (Linnaeus) J. Agardh from Helgoland (Germany) was evaluated. Discs of both species were incubated with three ammonium concentrations (0, 100 and 300 µM) under artificial PAR and UV radiation for 7 days. Photosynthetic activity decreased under the culture conditions due to UV radiation and ammonium availability. The decrease of both Fv/Fm and maximal ETR was related to ammonium supply, i.e. the lowest decrease occurred in algae growing with the highest concentration of ammonium. In both species, after 7 days of culture, the content of chl a, BP and SP was higher under 300 µM than that under 0 and 100 µM ammonium. In both species, the content of MAAs was increased under 300 µM ammonium compared to the initial value, whereas a decrease under 0 and 100 µM ammonium was observed only in P. leucosticta. The content of MAAs in P. umbilicalis did not present significant differences compared to the initial value, probably because of the high initial content of MAAs. In both Porphyra species, four MAAs were identified: shinorine, porphyra-334, palythine and asterina-330. However, P. leucosticta modified its MAA pattern during the incubation time, reaching the same percentages found for P. umbilicalis, which did not show any change during the experimental period. P. leucosticta exhibited a decrease in BP/SP and BP/chl a ratios through the incubation time and an increase in MAAs/BP. The ratio MAAs/chl a did not show any variation with time or treatment, as was also true for all ratios in P. umbilicalis. In summary, ammonium supply diminished the decrease of Fv/Fm, increased the content of photosynthetic pigments (chlorophyll and biliprotein) and soluble protein, and stimulated of the accumulation of MAAs in the red algae P. leucosticta and P. umbilicalis.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
For the first time we are able to report the identification and quantification of several unexpected alkylated tin compounds such as dimethyldiethyltin, trimethylethyltin and propyltrimethyltin in European municipal waste deposits, by using GC-ICP-MS. Future studies will reveal whether their origin is from the degradation of butyl-, or octyltin compounds or simply products of de novo synthesis within the landfill environment. 相似文献
Recent studies aiming at a fluorine mass balance analysis in sediments combined the determination of extractable organic fluorine (EOF) with target analysis. They reported high fractions of unidentified organic fluorine (UOF) compounds, as the target analysis covers only a limited number of per- and polyfluoroalkyl substances (PFAS). For this reason, in this study, a comprehensive approach was used combining target analysis with an extended PFAS spectrum, the EOF and a modified total oxidisable precursor (TOP) assay, which includes trifluoroacetic acid, to determine the PFAS contamination in sediments (n=41) and suspended solids (n=1) from water bodies in Northern Germany (Lower Saxony). PFAS are ubiquitous in the sediments (detected in 83% of the samples). Perfluorinated carboxylic acids (PFCAs) were found in 64% of the samples; perfluorinated sulfonic acids (PFSAs) were detected less frequently (21%), with the highest concentration observed for perfluorooctanesulfonic acid (PFOS). Levels of precursors and substitutes were lower. Applying the TOP assay resulted in an increase in PFCAs in 43% of the samples analysed. In most cases, target analysis and the TOP assay could not account for the EOF concentrations measured. However, as the fraction of UOF decreased significantly, the application of the TOP assay in fluorine mass balance analysis proved to be an important tool in characterising the PFAS contamination of riverine sediments.
Continuous ammonia (NH3) measurements with a temporal resolution of 5 min were implemented at selected SEARCH sites in the southeastern U. S. during 2007. The SEARCH continuous NH3 instrument uses a citric acid denuder difference technique employing a dual-channel nitric oxide-ozone chemiluminescence analyzer. Data from two SEARCH sites are presented, Jefferson Street, Atlanta (JST) (urban), and Yorkville, Georgia (YRK) (rural), for the period July–December, 2007. Highest NHx (total ammonia = gaseous NH3 + PM2.5 NH4+) values were observed in August and September at both JST and YRK. Highest NH3 values occurred in August and September at JST, but in August through October at YRK. Lowest NH3 and NHx values occurred in December at both sites. YRK is significantly impacted by nearby poultry sources, routinely experiencing hourly average NH3 mixing ratios above 20 ppbv. Wind sector analysis clearly implicates the nearby poultry operations as the source of the high NH3 values. Weekday versus weekend differences in composite hourly mean diurnal profiles of NH3 at JST indicate that mobile sources have a measurable but relatively small impact on NH3 observed at that site, and little or no impact on NH3 observed at YRK. A distinctive composite mean hourly diurnal variation was observed at both JST and YRK, exhibiting maxima in the morning and evening with a broad minimum during midday. Analysis of observed NH3 diurnal variations from the literature suggests a hypothesized mechanism for the observed behavior based on interaction of local emissions and dry deposition with the formation and collapse of the dynamically mixed atmospheric boundary layer during the day and shallow nocturnal layer at night. Simple mixed layer concentration box model simulations confirm the plausibility of the suggested mechanism. 相似文献
A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects. 相似文献
Based on a large monitoring data set from Danish coastal waters we tested the hypotheses: (1) The vertical pattern of algal
abundance is regulated by exposure in shallow water and by light limitation towards deeper water, resulting in a bell-shaped
abundance curve, with peak abundance located deeper at more exposed sites, (2) in deeper water, total algal abundance and
abundance of perennial algae decrease along a eutrophication gradient while (3) abundance and relative abundance of opportunists
increase. The vertical pattern of algal abundance showed a peak at intermediate water depths which was located deeper in more
exposed areas and thus confirmed our first hypothesis. For algae growing from depths of peak abundance and deeper, the study
demonstrated that total algal abundance and abundance of perennials and opportunists at given depths decreased significantly
along a eutrophication gradient and the relationships had high explanatory power (R2 =0.53–0.73). These results confirmed our second hypothesis. By contrast, the relative abundance of opportunists responded solely
to salinity and was largest in the most brackish areas, in contradiction to hypothesis three. The lack of coupling between
eutrophication and relative abundance of opportunists arises because both opportunists and the entire algal community were
light limited and their ratio therefore relatively insensitive to changing water clarity. The analyses indicated that algal
abundance initially responded slowly to increasing eutrophication but showed a more marked response at TN concentrations of
35–40 μM. However, the existence of possible threshold nutrient levels demands further analyses. 相似文献
Otolith microchemistry is widely used as a tool to track individual migration pathways of diadromous fish under the assumption
that the elemental composition of fish otoliths is directly influenced by the physicochemical properties of the surrounding
water. Nevertheless, several endogenous factors are reported to affect element incorporation into fish otoliths and might
lead to misinterpretations of migration studies. This study experimentally examined the influence of eight different diets
on the microchemical composition of European eel (Anguilla anguilla) otoliths using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Seven natural prey types and one
artificial diet were fed during 8 weeks in freshwater circuits. Results show for the first time that food has no significant
influence on the incorporation of Na, Sr, Ba, Mg, Mn, Cu and Y into European eel otoliths. This indicates that the incorporation
of elements usually chosen for migration studies is not affected by diet and that individual feeding behaviour of A. anguilla will not lead to any misinterpretation of migration pathways. 相似文献
The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities. 相似文献
That death is not a welfare issue appears to be a widespread view among animal welfare researchers. This paper demonstrates that this view is based on a mistaken assumption about harm, which is coupled to ‘welfare’ being conceived as ‘welfare at a time’. Assessments of welfare at a time ignore issues of longevity. In order to assess the welfare issue of death, it is necessary to structure welfare assessment as comparisons of possible lives of the animals. The paper also demonstrates that excluding the welfare issues of being deprived of life from the ethical assessment of killing distorts the ethical considerations. 相似文献