Measurement of I-129 in environmental samples by ICP-CRI-QMS: possibilities and limitations

129I is preconcentrated from environmental samples and its accessibility is addressed for inductively coupled plasma quadrupole mass spectrometer with collision/reaction interface (ICP-CRI-QMS). By applying oxygen as CRI gas through skimmer cone, the signal of the interfering 129Xe from the impurity of plasma gas can be eliminated while the formation of 127I1H1H+ can be partially removed. The improved ICP-QMS can be employed for investigation of 129I in environmental samples with a 129I/127I ratio down to 10-7. The detection capability was demonstrated by measuring 129I in seaweed samples collected around the nuclear fuel reprocessing plant at La Hague. The abundant 127I in the sample matrix causes a serious problem and degrades the detection capability of the instrument when the concentration of 127I is larger than 105ng/g. Even combined with a sufficient pre-concentration procedure, ICP-QMS is not considered as a suitable technique for the analysis of 129I in uncontaminated environmental samples with 129I/127I ratio of less than 10-7. Results are presented for seaweed samples collected around La Hague. In addition, time dependant I concentrations and ratios are given for colloids and water sampled from Lake Thu

The Impact of the Chernobyl Accident on a River/Groundwater Aquifer

The radionuclides 99mTc, 103Ru, 131I, 132Te, 134Cs and 137Cs, resulting from fallout from the damaged nuclear power plant at Chernobyl (USSR) were measured several times between May 2nd and 20th, 1986, in the River Glatt (Zürich, Switzerland) and in the adjacent shallow groundwater stream. Samples from the river and from different groundwater wells were filtered (0.45, 0.20, 0.05 Mm). The resulting water and the filters were assayed by 7-ray spectroscopy. For all these nuclides the main radioactivity ( > 75%) of the river water was found in the water passing the 0.05 Mm-filter. The fraction > 0.45 Mm contained the main particulate activity. Upon infiltration of river water into the groundwater stream iodine, ruthenium and tellurium are not, or only slightly sorbed, probably due to the formation of anionic or neutral species, whereas cesium is completely retained by the sediments. Particulate ( > 0.05 Mm) infiltration from the river into the groundwater is a negligible process

Human impacts and eutrophication patterns during the past ~200 years at Lago Grande di Avigliana (N. Italy)

A short sediment core from Lago Grande di Avigliana (Piedmont, Italy), the second most eutrophied lake in Italy, was analysed for pollen and diatoms to reconstruct land-use changes and to estimate baseline conditions for total phosphorus (TP) in the water column. Varve counts on sediment thin-sections and 210Pb, 226Ra, and 137Cs dating provided a reliable chronology for the past ~200 years. The main pollen-inferred land-use changes showed a sharp decrease of hemp retting around AD 1900, as well as a gradual change to less intensive agriculture and increasing abundance of exotic plants since AD ~1970. Diatom-inferred TP reconstructions indicated stable TP concentrations until AD ~1950, revealing baseline mesotrophic conditions (TP <25 µg l−1). After AD ~1950, TP values increased distinctly and continuously, culminating in the late 1960s with concentrations of 150 µg l−1. Subsequently, diatoms implied a linear decrease of TP, with an inferred value of 40 µg l−1 in the surface sediment sample. Comparison with instrumental TP measurements from the water column since AD 1980 showed a rapid recovery and allowed a direct validation of the diatom TP inference. However, although the TP concentration has decreased considerably, baseline conditions have not yet been reached. When compared to the limnological effects of sewage discharges on inferred-TP concentration, our results indicated that agricultural land use played a minor role in the lake's eutrophicatio

Time resolved sulphur and nutrient distribution in Norway spruce drill cores using ICP-OES

Methods were developed for detailed dendrochemical studies of low sulphur contents in Norway spruce (Picea abies L. Karst.). This tree species is the dominant conifer species in Northern and Central Europe and therefore predestined for a possible use as an environmental archive. Two independent digestion procedures were investigated with respect to their suitability for element determination and optimised for analysis of the low sulphur content in wood. A modified oxygen bomb combustion procedure and a microwave acid digestion procedure were evaluated with the goal to obtain sufficient detection limits in order to access low concentrated non-metals with an appropriate time resolution. Method development included evaluation of strategies preventing losses of volatile sulphur species. Digestion efficiency was demonstrated by recovery rates for various certified plant standard reference materials (NIST 1572, NIST 1547, RM 8436, BCR 101, NIST 1515, RM 8436, NIST 1573, NIST 1575) as well as self prepared standards with defined low sulphur content of 20 to 200mg kg−1, which are typical for Norway spruce wood samples. Ultra sonic nebulisation (USN) was evaluated with respect to signal enhancement for sample introduction to inductively coupled plasma optical emission spectrometry (ICP-OES). The optimised procedure was applied to Norway spruce drill cores from locations with different environmental conditions in Switzerland, in order to investigate the anthropogenic impact of sulphur and the suitability of Norway spruce as an environmental archive for sulphu

Sondeo arqueológico Cueva Pintada sector 13 [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Cytochrome P450 Enzymes Involved in Metoprolol Metabolism and Use of Metoprolol as a CYP2D6 Phenotyping Probe Drug

Metoprolol is used for phenotyping of cytochrome P450 (CYP) 2D6, a CYP isoform considered not to be inducible by inducers of the CYP2C, CYP2B, and CYP3A families such as rifampicin. While assessing CYP2D6 activity under basal conditions and after pre-treatment with rifampicin in vivo, we surprisingly observed a drop in the metoprolol/α-OH-metoprolol clearance ratio, suggesting CYP2D6 induction. To study this problem, we performed in vitro investigations using HepaRG cells and primary human hepatocytes (before and after treatment with 20 μM rifampicin), human liver microsomes, and CYP3A4-overexpressing supersomes. While mRNA expression levels of CYP3A4 showed a 15- to 30-fold increase in both cell models, mRNA of CYP2D6 was not affected by rifampicin. 1′-OH-midazolam formation (reflecting CYP3A4 activity) increased by a factor of 5–8 in both cell models, while the formation of α-OH-metoprolol increased by a factor of 6 in HepaRG cells and of 1.4 in primary human hepatocytes. Inhibition studies using human liver microsomes showed that CYP3A4, 2B6, and 2C9 together contributed 19.0 ± 2.6% (mean ± 95%CI) to O-demethylation, 4.0 ± 0.7% to α-hydroxylation, and 7.6 ± 1.7% to N-dealkylation of metoprolol. In supersomes overexpressing CYP3A4, metoprolol was α-hydroxylated in a reaction inhibited by the CYP3A4-specific inhibitor ketoconazole, but not by the CYP2D6-specific inhibitor quinidine. We conclude that metoprolol is not exclusively metabolized by CYP2D6. CYP3A4, 2B6, and 2C9, which are inducible by rifampicin, contribute to α-hydroxylation, O-demethylation, and N-dealkylation of metoprolol. This contribution is larger after CYP induction by rifampicin but is too small to compromise the usability of metoprolol α-hydroxylation for CYP2D6 phenotyping

Postglacial vegetational and fire history: pollen, plant macrofossil and charcoal records from two Alaskan lakes

Pollen, plant macrofossil and charcoal analyses of sediments from two Alaskan lakes provide new data for inferring Lateglacial and Holocene environmental change. The records span the past 14,700 years at Lost Lake, 240m a.s.l., central Alaska, north of the Alaska Range and 9600 years at Grizzly Lake, 720m a.s.l., Copper River Plateau, south of the Alaska Range. Salix shrubs expanded in the herb tundra about 14,400 cal b.p., and Betula shrub tundra became established at ca. 13,200 cal b.p. Diminished Betula shrub cover in association with the increased abundance of herbaceous taxa occurred at 12,500-11,600 cal b.p., although the timing of these changes is not well constrained. Populus expanded at 11,200 cal b.p. and formed dense stands until 9600-9400 cal b.p. when Picea glauca forests or woodlands became established at both sites. The abundance of Alnus viridis increased markedly around 8500 cal b.p. at both sites, marking the development of alder shrub thickets around the lakes and on mountain slopes in these areas. Boreal forests dominated by Picea mariana became established around 7200 cal b.p. at Grizzly Lake and 5700 cal b.p. at Lost Lake. At Grizzly Lake, marked vegetational oscillations occurred within the past 8500 years; for example, A. viridis expanded at 2750 cal b.p. and 450 cal b.p. and declined at 150 cal b.p. Some of these oscillations coincide with large-scale climatic events, such as the Little Ice Age cooling (LIA), and they probably reflect vegetational sensitivity to climatic change at this high site. Microscopic charcoal at Lost Lake suggests that fire was important in the lateglacial birch tundra, probably because of severe moisture deficits of the regional climate and/or high abundance of fine fuels. On the basis of the Grizzly Lake microscopic charcoal record, regional fires were common between 8500 and 6800 cal b.p. and between 450 and 150 cal b.p. Around Grizzly Lake, the mean return intervals of local fires estimated from macroscopic charcoal were ∼386 years between 6800 and 5500 cal b.p. when Picea glauca dominated over P. mariana, ∼254 years between 5500 and 3900 cal b.p. when P. mariana was more abundant than P. glauca, and ∼200 years after 3900 cal b.p. in both P. glauca and P. mariana dominated forests. Correlation analysis of pollen and microscopic charcoal at Grizzly Lake reveals that increased fire activity led to the reductions of P. glauca, P. mariana, and tree Betula in association with the expansions of A. viridis, Epilobium, Lycopodium clavatum, and L. annotinu