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31.
Contaminant exposure and effects in Baltic ringed and grey seals as assessed by biomarkers 总被引：3，自引：0，他引：3
Nyman M Bergknut M Fant ML Raunio H Jestoi M Bengs C Murk A Koistinen J Bäckman C Pelkonen O Tysklind M Hirvi T Helle E 《Marine environmental research》2003,55(1):73-99
The Baltic Sea ecosystem has suffered from a heavy pollutant load for more than three decades. Persistent organic pollutants (POPs) and heavy metals have been of most concern due to their persistence and toxic properties. Ringed seals (Phoca hispida baltica) and grey seals (Halichoerus grypus) living in the Baltic Sea have been suffering from pathological impairments, including reproductive disturbances, which have resulted in a depressed reproductive capacity. We investigated several biochemical parameters as potential biomarkers for exposure to and effects of the contaminant load in the Baltic seals. Seals from less polluted areas were used as reference material in terms of the pollution load. In both Baltic seal populations, the levels of some biochemical parameters diverged from those in the reference seals, and some of these showed a clear correlation with the individual contaminant load. Of the potential bioindicators, we propose cytochrome P4501A activity and vitamin E levels, in blubber or plasma, as exposure biomarkers for polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) in both species. The arylhydrocarbon receptor-mediated chemical-activated luciferase gene expression (CALUX) response reflects the whole PCB and DDT burden in ringed seals. Retinyl palmitate (vitamin A) levels showed a negative correlation with the individual POP load, and is proposed as potential effect biomarkers for the depletion of the vitamin A stores. As the nutritional levels of both vitamin A and E have an impact on the vitamin levels in the seals, more information on the dietary vitamin levels is needed before any conclusions can be drawn. As the relationship between biochemical parameters and contaminants varied between the two species, species-specific characteristics has to be considered when monitoring the health status and possible toxic effects of the contaminant load in ringed and grey seals. 相似文献
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In the area surrounding the El Teniente giant porphyry copper deposit, eight soil sites were sampled at three depth levels
in the summer 2004. The sites were selected for their theoretical potential of being influenced by past SO2 emissions from the smelter and/or seepage from a now idle tailings impoundment. The soil mineralogy, grain size distribution,
total organic matter contents, major element composition, cation exchange capacity, and Cu, Mo, Pb, Zn, As and SO4
2− concentrations were determined for all samples after nitric acid extraction and separate leaches by ammonium acetate (pH
7) and sodium acetate (pH 5). For water rinses, only Cu could be determined with the analytical set-up used. Cu and SO4
2− enrichment in topsoils was found at six sites either downwind from the smelter or within the combined influence of the smelter
and the tailings impoundment. Both elements were released partially by ammonium and sodium acetate extractions. Due to the
scarce background trace element concentrations of soil and rock outside the immediate mine area, assessment of trace element
mobility for Mo, Zn, Pb and As was difficult. Arsenic was found to be concentrated in soil horizons with high smectite and/or
organic matter contents. Mo appears to be linked to the presence of windblown tailings sediment in the soils. Mobilization
of Mo, Zn, and As for the acetate extractions was minimal or below the detection limits for the AAS technique used. The presence
of windblown tailings is considered to be an additional impact on the soils in the foothills of the El Teniente compound,
together with the potential of acidity surges and Cu mobilization in topsoils after rainfalls. Two sites located at the western
limit of the former SO2 saturated zone with strongly zeolitized soils and underlying rock did not show any Cu or SO4
2− enrichment in the topsoils, and remaining total trace element concentrations were below the known regional background levels. 相似文献
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Sheila J. Seaman Helle Gylling John P. Hogan Frank Karner G. Christopher Koteas 《Contributions to Mineralogy and Petrology》2011,162(6):1291-1314
The Tunk Lake pluton of coastal Maine, USA is a concentrically zoned granitic body that grades from an outer hypersolvus granite
into subsolvus rapakivi granite, and then into subsolvus non-rapakivi granite, with gradational contacts between these zones.
The pluton is partially surrounded by a zone of basaltic and gabbroic enclaves, interpreted as quenched magmatic droplets
and mushes, respectively, as well as gabbroic xenoliths, all hosted by high-silica granite. The granite is zoned in terms
of mineral assemblage, mineral composition, zircon crystallization temperature, and major and trace element concentration,
from the present-day rim (interpreted as being closer to the base of the chamber) to the core (interpreted as being closer
to the upper portions of the chamber). The ferromagnesian mineral assemblage systematically changes from augite and hornblende
with augite cores in the outermost hypersolvus granite to hornblende, to hornblende and biotite, and finally, to biotite only
in the subsolvus granite core of the pluton. Sparse fine-grained basaltic enclaves that are most common in the outermost zone
of the pluton suggest that basaltic magma was present in the lower portions of the magma chamber at the same time that the
upper portions of the magma chamber were occupied by a granitic crystal mush. However, the slight variations in initial Nd
isotopic ratio in granites from different zones of the pluton suggest that contamination of the granitic melt by basaltic
melt played little role in generating the compositional gradation of the pluton. The zone of basaltic and gabbroic chilled
magmatic enclaves, and gabbroic xenoliths, hosted by high-silica granite, that partially surround the pluton is interpreted
as mafic layers at the base of the pluton that were disrupted by invading late-stage high-silica magma. These mafic layers
are likely to have consisted of basaltic lava layers and basalt that chilled against granitic magma to produce coarse-grained
gabbroic mush. Basaltic and gabbroic magmatic enclaves and gabbroic xenoliths are hornblende-bearing, suggesting that their
parent melts were relatively hydrous. The water-rich nature of the underplating mafic magmas may have prevented extensive
invasion of the granitic magma by these magmas, owing to the much greater viscosity of the granitic magma than the mafic magmas
in the temperature range over which magma interaction could have occurred. 相似文献
35.
Sorption of phosphate onto calcite; results from batch experiments and surface complexation modeling 总被引：3，自引：0，他引：3
The adsorption of phosphate onto calcite was studied in a series of batch experiments. To avoid the precipitation of phosphate-containing minerals the experiments were conducted using a short reaction time (3 h) and low concentrations of phosphate (?50 μM). Sorption of phosphate on calcite was studied in 11 different calcite-equilibrated solutions that varied in pH, PCO2, ionic strength and activity of Ca2+, and . Our results show strong sorption of phosphate onto calcite. The kinetics of phosphate sorption onto calcite are fast; adsorption is complete within 2-3 h while desorption is complete in less than 0.5 h. The reversibility of the sorption process indicates that phosphate is not incorporated into the calcite crystal lattice under our experimental conditions. Precipitation of phosphate-containing phases does not seem to take place in systems with ?50 μM total phosphate, in spite of a high degree of super-saturation with respect to hydroxyapatite (SIHAP ? 7.83). The amount of phosphate adsorbed varied with the solution composition, in particular, adsorption increases as the activity decreases (at constant pH) and as pH increases (at constant activity). The primary effect of ionic strength on phosphate sorption onto calcite is its influence on the activity of the different aqueous phosphate species. The experimental results were modeled satisfactorily using the constant capacitance model with >CaPO4Ca0 and either >CaHPO4Ca+ or > as the adsorbed surface species. Generally the model captures the variation in phosphate adsorption onto calcite as a function of solution composition, though it was necessary to include two types of sorption sites (strong and weak) in the model to reproduce the convex shape of the sorption isotherms. 相似文献
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The application of tree-rings and stable isotopes for reconstructions of climate conditions in the Russian Altai 总被引：2，自引：0，他引：2
O. V. Sidorova R. T. W. Siegwolf V. S. Myglan D. V. Ovchinnikov V. V. Shishov G. Helle N. J. Loader M. Saurer 《Climatic change》2013,120(1-2):153-167
We present new tree-ring width, δ13C, and δ18O chronologies from the Koksu site (49°N, 86° E, 2,200 m asl), situated in the Russian Altai. A strong temperature signal is recorded in the tree-ring width (June-July) and stable isotope (July-August) chronologies, a July precipitation signal captured by the stable isotope data. To investigate the nature of common climatic patterns, our new chronologies are compared with previously published tree-ring and stable isotope data from other sites in the Altai region. The temperature signal preserved in the conifer trees is strongly expressed at local and regional scales for all studied sites, resulting in even stronger temperature and precipitation signals in combined average chronologies compared to separate chronologies. This enables the reconstruction of June-July and July-August temperatures for the last 200 years using tree-ring and stable carbon isotopes. A July precipitation reconstruction based on oxygen isotopic variability recorded in tree-rings can potentially improve the understanding of hydrological changes and the occurrence of extreme events in the Russian Altai. 相似文献
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Per Johan Brandvik Øistein JohansenFrode Leirvik Umer FarooqPer S. Daling 《Marine pollution bulletin》2013
Size distribution of oil droplets formed in deep water oil and gas blowouts have strong impact on the fate of the oil in the environment. However, very limited data on droplet distributions from subsurface releases exist. The objective of this study has been to establish a laboratory facility to study droplet size versus release conditions (rates and nozzle diameters), oil properties and injection of dispersants (injection techniques and dispersant types). This paper presents this facility (6 m high, 3 m wide, containing 40 m3 of sea water) and introductory data. Injection of dispersant lowers the interfacial tension between oil and water and cause a significant reduction in droplet size. Most of this data show a good fit to existing Weber scaling equations. Some interesting deviations due to dispersant treatment are further analyzed and used to develop modified algorithms for predicting droplet sizes in a second paper (Johansen et al., 2013). 相似文献
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The adsorption and desorption of arsenate (As(V)) and arsenite (As(III)) on calcite was investigated in a series of batch experiments in calcite-equilibrated solutions. The solutions covered a broad range of pH, alkalinity, calcium concentration and ionic strength. The initial arsenic concentrations were kept low (<33 μM) to avoid surface precipitation. The results show that little or no arsenite sorbs on calcite within 24 h at an initial As concentration of 0.67 μM. In contrast, arsenate sorbs readily and quickly on calcite. Likewise, desorption of arsenate from calcite is fast and complete within hours, indicating that arsenate is not readily incorporated into the calcite crystal lattice. The degree of arsenate sorption depends on the solution chemistry. Sorption increases with decreasing alkalinity, indicating a competition for sorption sites between arsenate and (bi)carbonate. pH also affects the sorption behavior, likely in response to changes in arsenate speciation or protonation/deprotonation of the adsorbing arsenate ion. Finally, sorption is influenced by the ionic strength, possibly due to electrostatic effects. The sorption of arsenate on calcite was modeled successfully using a surface complexation model comprising strong and weak sites. In the model, the adsorbing arsenate species were and . The model was able to correctly predict the adsorption of arsenate in the wide range of calcite-equilibrated solutions used in the batch experiments and to describe the non-linear shape of the sorption isotherms. Extrapolation of the experimental results to calcite bearing aquifers suggests a large variability in the mobility of arsenic. Under reduced conditions, arsenite, which does not sorb on calcite, will dominate and, hence, As will be highly mobile. In contrast, when conditions are oxidizing, arsenate is the predominant species and, because arsenate adsorbs strongly on calcite, As mobility will be significantly retarded. The estimated retardation factors for arsenate in carbonate aquifers range from 25 to 200. 相似文献