Mercury volatilization from a floodplain soil during a simulated flooding event

Middle-European floodplain soils are often contaminated with mercury (Hg) and periodically flooded. In this study, the influence of a flooding event and subsequent dewatering on the volatilization of elemental Hg and methylated species was investigated in a laboratory experiment. Undisturbed soil cores were taken from a topsoil (12.1 +/- 0.75 mg kg(-1) Hg) at the Elbe River in Lower Saxony, Germany. Soil columns were incubated at 20 A degrees C with varying soil moisture (water-saturated for 2 weeks, 95 and 90 % water content for 1 week each), and the redox potential (E-H) was recorded. The gaseous Hg that accumulated in the headspace of the flux chamber of the columns was pumped over cooled traps filled with adsorber material and analyzed by gas chromatography/inductively coupled plasma mass spectrometry for the various Hg species. The watering of the soil resulted in a rapid decrease in the E-H and the achievement of strongly reducing conditions (E-H < -100 mV). Mercury concentrations of the pore waters decreased continuously from 68.3 mu g L-1 Hg at the beginning to 5.78 mu g L-1 Hg at the end of the experiment. Species analyses revealed that exclusively elemental Hg volatilized. The volatilization rate was between 1.73 and 824 ng m(-2) h(-1) Hg, which is consistent with other studies at the Elbe River. Even when flooded for a longer period of time, floodplain soils should show neither emission of methylated Hg nor exceptionally high volatilization of elemental Hg

Zinc distribution within breast cancer tissue of different intrinsic subtypes

Purpose!#!To show feasibility of laser ablation inductively coupled mass spectrometry (LA-ICPMS) for analysis of zinc content and concentration in breast cancer tissue and to correlate this with validated prognostic and predictive markers, i.e. histological grading and expression of steroid receptors (estrogen receptor, ER; progesterone receptor, PR) and human epidermal growth-factor receptor 2 (Her2).!##!Methods!#!28 samples of human invasive ductal breast cancer tissue were subclassified into groups of four different intrinsic subtypes according to the expression of ER, PR and Her2 by immunohistological staining and then analyzed for zinc content and distribution by LA-ICPMS applying a calibration technique based on spiked polyacrylamide gels. A correlation of zinc concentration with histological grading and molecular subtypes was analyzed.!##!Results!#!Consistent with results of a pilot-study LA-ICPMS was feasible to show zinc accumulation in cancerous tissue, even more adjacent healthy stroma was with proportional increase of zinc. Zinc levels were most elevated in triple-positive (TPBC) and in triple-negative (TNB) breast cancers.!##!Conclusion!#!LA-ICPMS was feasible to confirm a connection between zinc and grade of malignancy; furthermore, focusing on a correlation of zinc and intrinsic breast cancer subtypes, LA-ICPMS depicted an upwards trend of zinc for 'high-risk-cancers' with highest levels in Her2-positive and in triple-negative (TNBC) disease. The currently uncommon alliance of clinicians and analytical chemists in basic research is most promising to exploit the full potential of diagnostic accuracy in the efforts to solve the enigma of breast cancer initiation and course of disease

Determining the contribution of tyre, clutch, brake and wearing course abrasion to the PM10 emissions of roads

Im Hinblick auf die prozessbezogenen Beiträge nicht-motorischer Partikelemissionen durch Abriebs- und Aufwirbelung existieren derzeit lediglich Studien, die an stark belasteten Innerortsstraßen oder in Tunneln durchgeführt wurden. Für die Emissionen von Autobahnen konnten die so gewonnenen Ergebnisse daher nicht ohne Weiteres als repräsentativ für die wesentlich häufiger anzutreffende Situation frei angeströmter Autobahnabschnitte betrachtet werden. Um diese Wissenslücke zu schließen, wurden im vorliegenden Projekt an der Autobahn A61 für mehr als 1 Jahr Luv-Lee Messungen durchgeführt. Mittels der NOx-Tracer-Methode wurden die in Tabelle 16 des Berichtes wiedergegebenen partikelmassen-bezogenen Emissionsfaktoren (EFs) ermittelt. Die EFs für PM10 sind mit Ergebnissen anderer Studien aus Deutschland beziehungsweise der Schweiz gut vergleichbar, während sich für die PM1-10-Fraktion geringere EFs ergaben, als aktuell angenommen. Mittels der Positiv-Matrix-Faktorisierung konnten neben den motorischen Emissionen vier nicht-motorische Quellfaktoren identifiziert und quantifiziert werden. Dabei zeigte sich neben einem deutlichen Einfluss durch Tausalzausbringung insbesondere die Relevanz von Bremsabrieb Diese Ergebnisse bestätigen somit auch für freiliegende Autobahnabschnitte die Signifikanz der nicht-motorischen Partikelemissionen für die PM10-Emissionen.Currently, only studies conducted at highly polluted streets within built-up areas or in tunnels exist concerning non-exhaust emissions from traffic caused by abrasion and resuspension. Results from these studies are therefore not directly transferable to emissions from highway traffic with free airflow. In order to close this gap of knowledge, upwind/downwind measurements at the German highway A61 were conducted for more than 1 year. Particle mass related emissions factors (EFs) (see table 16 of the report) were derived using the NOx tracer method. EFs for PM10 compare well with results from other studies from Germany and Switzerland, whereas the coarse fraction's EFs (PM1-10) are lower than those actually used in Germany. Using positive matrix factorisation (PMF) four non-exhaust sources could be identified and quantified. The relevance of brake abrasion was shown, together with a considerable influence due to road salting. These results confirm the importance of non-exhaust particle emissions regarding PM10 emissions also for highways in non-built-up areas with free air flow conditions

Role of Intestinal Microbiota in Transformation of Bismuth and Other Metals and Metalloids into Volatile Methyl and Hydride Derivatives in Humans and Mice▿

The present study shows that feces samples of 14 human volunteers and isolated gut segments of mice (small intestine, cecum, and large intestine) are able to transform metals and metalloids into volatile derivatives ex situ during anaerobic incubation at 37°C and neutral pH. Human feces and the gut of mice exhibit highly productive mechanisms for the formation of the toxic volatile derivative trimethylbismuth [(CH3)3Bi] at rather low concentrations of bismuth (0.2 to 1 μmol kg−1 [dry weight]). An increase of bismuth up to 2 to 14 mmol kg−1 (dry weight) upon a single (human volunteers) or continuous (mouse study) administration of colloidal bismuth subcitrate resulted in an average increase of the derivatization rate from approximately 4 pmol h−1 kg−1 (dry weight) to 2,100 pmol h−1 kg−1 (dry weight) in human feces samples and from approximately 5 pmol h−1 kg−1 (dry weight) to 120 pmol h−1 kg−1 (dry weight) in mouse gut samples, respectively. The upshift of the bismuth content also led to an increase of derivatives of other elements (such as arsenic, antimony, and lead in human feces or tellurium and lead in the murine large intestine). The assumption that the gut microbiota plays a dominant role for these transformation processes, as indicated by the production of volatile derivatives of various elements in feces samples, is supported by the observation that the gut segments of germfree mice are unable to transform administered bismuth to (CH3)3Bi