Atmospheric mercury concentrations and speciation measured from 2004 to 2007 in Reno, Nevada, USA

Atmospheric elemental, reactive and particulate mercury (Hg) concentrations were measured north of downtown Reno, Nevada, USA from November 2004 to November 2007. Three-year mean and median concentrations for gaseous elemental Hg (Hg⁰) were 1.6 and 1.5 ng m⁻³ (respectively), similar to global mean Hg⁰ concentrations. The three-year mean reactive gaseous Hg (RGM) concentration (26 pg m⁻³) was higher than values reported for rural sites across the western United States. Well defined seasonal and daily patterns in Hg⁰ and RGM concentrations were observed, with the highest Hg⁰ concentrations measured in winter and early morning, and RGM concentrations being greatest in the summer and mid-afternoon. Elevated Hg⁰ concentrations in winter were associated with periods of cold, stagnant air; while a regularly observed early morning increase in concentration was due to local source and surface emissions. The observed afternoon increase and high summer values of RGM can be explained by in situ oxidation of gaseous Hg⁰ or mixing of RGM derived from the free troposphere to the surface. Because both of these processes are correlated with the same environmental conditions it is difficult to assess their overall contribution to the observed trends.     

Reconnecting to the Biosphere

Humanity has emerged as a major force in the operation of the biosphere, with a significant imprint on the Earth System, challenging social-ecological resilience. This new situation calls for a fundamental shift in perspectives, world views, and institutions. Human development and progress must be reconnected to the capacity of the biosphere and essential ecosystem services to be sustained. Governance challenges include a highly interconnected and faster world, cascading social-ecological interactions and planetary boundaries that create vulnerabilities but also opportunities for social-ecological change and transformation. Tipping points and thresholds highlight the importance of understanding and managing resilience. New modes of flexible governance are emerging. A central challenge is to reconnect these efforts to the changing preconditions for societal development as active stewards of the Earth System. We suggest that the Millennium Development Goals need to be reframed in such a planetary stewardship context combined with a call for a new social contract on global sustainability. The ongoing mind shift in human relations with Earth and its boundaries provides exciting opportunities for societal development in collaboration with the biosphere--a global sustainability agenda for humanity.     

Determining sources of dissolved organic carbon and disinfection byproduct precursors to the McKenzie River, Oregon

This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous--derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 +/- 0.4 vs. 0.7 +/- 0.3 mg L(-1)) but comprised < 5% ofmainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs.     

Mason Valley Groundwater Model: Linking Surface Water and Groundwater in the Walker River Basin,Nevada1

Carroll, Rosemary W.H., Greg Pohll, David McGraw, Chris Garner, Anna Knust, Doug Boyle, Tim Minor, Scott Bassett, and Karl Pohlmann, 2010. Mason Valley Groundwater Model: Linking Surface Water and Groundwater in the Walker River Basin, Nevada. Journal of the American Water Resources Association (JAWRA) 46(3):554-573. DOI: 10.1111/j.1752-1688.2010.00434.x Abstract: An integrated surface water and groundwater model of Mason Valley, Nevada is constructed to replicate the movement of water throughout the different components of the demand side of water resources in the Walker River system. The Mason Valley groundwater surface water model (MVGSM) couples the river/drain network with agricultural demand areas and the groundwater system using MODFLOW, MODFLOW’s streamflow routing package, as well as a surface water linking algorithm developed for the project. The MVGSM is capable of simulating complex feedback mechanisms between the groundwater and surface water system that is not dependent on linearity among the related variables. The spatial scale captures important hydrologic components while the monthly stress periods allow for seasonal evaluation. A simulation spanning an 11-year record shows the methodology is robust under diverse climatic conditions. The basin-wide modeling approach predicts a river system generally gaining during the summer irrigation period but losing during winter months and extended periods of drought. River losses to the groundwater system approach 25% of the river’s annual budget. Reducing diversions to hydrologic response units will increase river flows exiting the model domain, but also has the potential to increase losses from the river to groundwater storage.     

Seeing (and doing) conservation through cultural lenses

In this paper, we first discuss various vantage points gained through the authors’ experience of approaching conservation through a “cultural lens.” We then draw out more general concerns that many anthropologists hold with respect to conservation, summarizing and commenting on the work of the Conservation and Community Working Group within the Anthropology and Environment Section of the American Anthropological Association. Here we focus on both critiques and contributions the discipline of anthropology makes with regard to conservation, and show how anthropologists are moving beyond conservation critiques to engage actively with conservation practice and policy. We conclude with reflections on the possibilities for enhancing transdisciplinary dialogue and practice through reflexive questioning, the adoption of disciplinary humility, and the realization that “cross-border” collaboration among conservation scholars and practitioners can strengthen the political will necessary to stem the growing commoditization and ensuing degradation of the earth’s ecosystems.     

Some flame retardants and the antimicrobials triclosan and triclocarban enhance the androgenic activity in vitro

Contaminants including flame retardants, antimicrobial agents and phthalates, occurring as residues in human tissues were associated with altered endocrine function. In our study we analysed the flame retardants tetrabromobisphenol A (TBBPA), hexabromocyclodecane (HBCD), penta-bromodiphenylether (BDE-100) and hexa-BDE (BDE-155), the antimicrobial compounds triclosan (TCS) and triclocarban (TCC) and eight phthalates for their androgenic and antiandrogenic activity in vitro in the MDA-kb2 cell line. No or only weak androgenic activity was observed for all the tested compounds. TBBPA showed weak antiandrogenic activity, which was demonstrated for the first time. The flame retardants HBCD, BDE-100 and BDE-155 enhanced the dihydrotestosterone-dependent activation of androgen receptor-responsive gene expression but exhibited little or no agonistic activity. The enhancement reached 150%, which was similar to the antimicrobials (TCS up to 180%, and TCC up to 130%). This enhancement of androgenic activity represents a novel mode of action of the endocrine activity of flame retardants. In contrast, most phthalates showed antiandrogenic activity. Butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and diethyl phthalate (DEP) showed strong antiandrogenicity, whereas the action of diethylhexyl phthalate (DEHP), dipentyl phthalate (DPP), dimethyl phthalate (DMP), and the DEHP metabolite monoethylhexyl phthalate (MEHP) was lower. Our in vitro study demonstrates for the first time a weak antiandrogenic activity of TBBPA, and a significant enhancement of the androgenic activity of HBCD, BDE-100 and BDE-155, which represents a novel mechanism of hormonal activity of flame retardants.     

Life Cycle Analyses and Resource Assessments

Prof. Ulgiati stresses that we should always use an ecosystem view when transforming energy from one form to another. Sustainable growth and development of both environmental and human-dominated systems require optimum use of available resources for maximum power output. We have to adapt to the laws of nature because nature has to take care of all the waste products we produce. The presentation addresses a much needed shift away from linear production and consumption pattern, toward reorganization of economies and lifestyle that takes complexity—of resources, of the environment and of the economy—into proper account. The best way to reach maximum yield from the different kinds of biomass is to use biorefineries. Biorefinery is defined as the sustainable processing of biomass into a spectrum of marketable products like heat, power, fuels, chemicals, food, feed, and materials. However, biomass from agricultural land must be used for the production of food and not fuel. Prof. Voss focuses on the sustainability of energy supply chains and energy systems. Life cycle analyses (LCA) provides the conceptual framework for a comprehensive comparative evaluation of energy supply options with regard to their resource requirements as well as the health and environmental impact. Full scope LCA considers not only the emissions from plant operation, construction, and decommissioning but also the environmental burdens and resource requirements associated with the entire lifetime of all relevant upstream and downstream processes within the energy chain. This article describes the results of LCA analyses for state-of-the-art heating and electricity systems as well as of advanced future systems. Total costs are used as a measure for the overall resource consumption.