Methylmercury degradation and exposure pathways in streams and wetlands impacted by historical mining

The authors acknowledge financial support from the National Science Foundation: EAR-1226741 (to M.B.S.) and EAR-1225630 (to J.D.B.).Monomethyl mercury (MMHg) and total mercury (THg) concentrations and Hg stable isotope ratios (δ202Hg and Δ199Hg) were measured in sediment and aquatic organisms from Cache Creek (California Coast Range) and Yolo Bypass (Sacramento Valley). Cache Creek sediment had a large range in THg (87 to 3870 ng/g) and δ202Hg (− 1.69 to − 0.20‰) reflecting the heterogeneity of Hg mining sources in sediment. The δ202Hg of Yolo Bypass wetland sediment suggests a mixture of high and low THg sediment sources. Relationships between %MMHg (the percent ratio of MMHg to THg) and Hg isotope values (δ202Hg and Δ199Hg) in fish and macroinvertebrates were used to identify and estimate the isotopic composition of MMHg. Deviation from linear relationships was found between %MMHg and Hg isotope values, which is indicative of the bioaccumulation of isotopically distinct pools of MMHg. The isotopic composition of pre-photodegraded MMHg (i.e., subtracting fractionation from photochemical reactions) was estimated and contrasting relationships were observed between the estimated δ202Hg of pre-photodegraded MMHg and sediment IHg. Cache Creek had mass dependent fractionation (MDF; δ202Hg) of at least − 0.4‰ whereas Yolo Bypass had MDF of + 0.2 to + 0.5‰. This result supports the hypothesis that Hg isotope fractionation between IHg and MMHg observed in rivers (− MDF) is unique compared to + MDF observed in non-flowing water environments such as wetlands, lakes, and the coastal ocean.PostprintPeer reviewe

Non-local branches of cycles, bi-stability, and topologically

persistent mixed mode oscillation

The persistence of lead from past gasoline emissions and mining drainage in a large riparian system: Evidence from lead isotopes in the Sacramento River, California

Lead concentrations and isotope ratios measured in river water colloids and streambed sediment samples along 426 km of the Sacramento River, California reveal that the influence of lead from the historical mining of massive sulfide deposits in the West Shasta Cu-mining district (at the headwaters of the Sacramento River) is confined to a 60 km stretch of river immediately downstream of that mining region, whereas inputs from past leaded gasoline emissions and historical hydraulic Au-mining in the Sierra Nevadan foothills are the dominant lead sources in the remaining 370 km of the river. Binary mixing calculations suggest that more than 50% of the lead in the Sacramento River outside of the region of influence of the West Shasta Cu-mining district is derived from past depositions of leaded gasoline emissions. This predominance is the first direct documentation of the geographic extent of gasoline lead persistence throughout a large riparian system (\u3e160,000 km2) and corroborates previous observations based on samples taken at the mouth of the Sacramento River. In addition, new analyses of sediment samples from the hydraulic gold mines of the Sierra Nevada foothills confirm the present-day fluxes into the Sacramento River of contaminant metals derived from historical hydraulic Au-mining that occurred during the latter half of the 19th and early part of the 20th centuries. These fluxes occur predominantly during periods of elevated river discharge associated with heavy winter precipitation in northern California. In the broadest context, the study demonstrates the potential for altered precipitation patterns resulting from climate change to affect the mobility and transport of soil-bound contaminants in the surface environment

Anomalous Quantitation Standard Growth Curves in a Laboratory-Developed Hepatitis C Virus (HCV) RNA Quantification Assay Using the TaqMan HCV Analyte-Specific Reagent▿

A retrospective examination of quantitation standard growth curves associated with 1,000 unique clinical serum specimens tested by a laboratory-developed TaqMan hepatitis C virus analyte-specific reagent-based assay revealed anomalous growth curves associated with 0.40% (95% confidence interval, 0.11% to 1.00%) of these specimens

Energie Waermepumpe : Energie sparen durch Waermepumpenheizanlagen

Immer mehr oeffentliche, gewerbliche und private Investoren setzen auf die Nutzung von Umweltwaerme aus der Luft, dem Erdreich und aus dem Wasser. Durch die staendig sinkenden Transmissions-Waermeverluste von Gebaeuden wird der Energieanteil fuer die Bereitstellung von warmen Wasser immer wichtiger. Ebenso koennen elektrische Waermepumpenanlagen heutzutage mit guenstigem Investitionsaufwand errichtet werden, insbesondere wenn diese als monoenergetische Anlagen ausgefuehrt werden. Weitere Kostenvorteile werden durch Liberalisierung auf dem Strommarkt und die damit vebrundenen Strompreissenkungen erwartet. Zudem gibt es derzeit eine Vielzahl von Foerdermoeglichkeiten in Form von Zulagen, Zuschuessen und zinsguenstigen Darlehen. Neben der finanziellen Foerderung ist auch die Vermittlung des Wissens um die technischen Rahmenbedingungen an alle diejenigen notwendig, die Waermepumpenanlagen in Neubau oder bei der Altbaumodernisierung installieren moechten. Die vorliegende Infoschrift liefert in umfassender und dennoch kompakter Form alle Fachinformationen, die fuer Architekten, Planer, Handwerksfirmen, Bauherren und Investoren wichtig sind, um umweltvertraegliche, betriebssichere und kostenguenstige Waermepumpenheizanlagen zu errichten und damit diese innovative Zukunftstechnologie weiter voranzubringen. (orig.)Increasingly more public, commercial and private investors prefer to use environmental heat from the air, the ground and water. Due to the permanently decreasing transmission heat losses in buildings, the energy portion needed to prepare hot water gains more importance. Electrical heat pump systems can be erected with little investment nowadays, and this is especially true if they are built as monoenergetic systems. Further advantages relating to costs are expected from the liberalisation on the power market and the reductions in power prices connected with this. In addition, presently there are numerous ways of financial supports like bonuses, grants and loans with favourable interest rates. In addition to the financial support, however, it is necessary to provide those who want to install heat pump systems in new or modernized old buildings with knowledge about the technical frame conditions. This information brochure gives extensive but compact information important to architects, planners, craftsmen, constructors and investors in order to build heat pump systems not polluting the environment, safe to operate and with low costs thus further supporting this innovative future technology.SIGLEAvailable from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek2. ed.DEGerman