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Reduced defense against large herbivores has been suggested to be part of the "island syndrome" in plants. However, empirical evidence for this pattern is mixed. In this paper, we present two studies that compare putative physical and chemical defense traits from plants on the California Channel Islands and nearby mainland based on sampling of both field and common garden plants. In the first study, we focus on five pairs of woody shrubs from three island and three mainland locations and find evidence for increased leaf area, decreased marginal leaf spines, and decreased concentrations of cyanogenic glycosides in island plants. We observed similar increases in leaf area and decreases in defense traits when comparing island and mainland genotypes grown together in botanic gardens, suggesting that trait differences are not solely driven by abiotic differences between island and mainland sites. In the second study, we conducted a common garden experiment with a perennial herb—Stachys bullata (Lamiaceae)—collected from two island and four mainland locations. Compared to their mainland relatives, island genotypes show highly reduced glandular trichomes and a nearly 100-fold reduction in mono- and sesquiterpene compounds from leaf surfaces. Island genotypes also had significantly higher specific leaf area, somewhat lower rates of gas exchange, and greater aboveground biomass than mainland genotypes across two years of study, potentially reflecting a broader shift in growth habit. Together, our results provide evidence for reduced expression of putative defense traits in island plants, though these results may reflect adaptation to both biotic (i.e., the historical absence of large herbivores) and climatic conditions on islands. [ABSTRACT FROM AUTHOR]

Nitrite (NO2-) is a substrate for both oxidative and reductive microbial metabolism. NO2- accumulates at the base of the euphotic zone in oxygenated, stratified open-ocean water columns, forming a feature known as the primary nitrite maximum (PNM). Potential pathways of NO2- production include the oxidation of ammonia (NH3) by ammonia-oxidizing bacteria and archaea as well as assimilatory nitrate (NO3-) reduction by phytoplankton and heterotrophic bacteria. Measurements of NH3 oxidation and NO3- reduction to NO2- were conducted at two stations in the central California Current in the eastern North Pacific to determine the relative contributions of these processes to NO2- production in the PNM. Sensitive (< 10 nmol L-1), precise measurements of [NH4+] and [NO2-] indicated a persistent NH maximum overlying the PNM at every station, with concentrations as high as 1.5 µmol L-1. Within and just below the PNM, NH3 oxidation was the dominant NO2- producing process, with rates of NH3 oxidation to NO2- of up to 31 nmol L-1 d-1, coinciding with high abundances of ammonia-oxidizing archaea. Though little NO2- production from NO3- was detected, potentially nitrate-reducing phytoplankton (photosynthetic picoeukaryotes, Synechococcus, and Prochlorococcus) were present at the depth of the PNM. Rates of NO2- production from NO3- were highest within the upper mixed layer (4.6 nmol L-1 d-1 ) but were either below detection limits or 10 times lower than NH3 oxidation rates around the PNM. One-dimensional modeling of water column NO2- production agreed with production determined from 15N bottle incubations within the PNM, but a modeled net biological sink for NO2- just below the PNM was not captured in the incubations. Residence time estimates of NO2- within the PNM ranged from 18 to 470 days at the mesotrophic station and was 40 days at the oligotrophic station. Our results suggest the PNM is a dynamic, rather than relict, feature with a source term dominated by ammonia oxidation. [ABSTRACT FROM AUTHOR]

Abstract: In temperate conifer forests of the Western USA, there is active debate whether fuels reduction treatments and bioenergy production result in decreased carbon emissions and increased carbon sequestration compared to a no-action alternative. To address this debate over net carbon stocks, we performed a carbon life-cycle analysis on data from a fuels reduction treatment in a temperate, dry conifer forest in the northern Sierra Nevada of California, USA. The analysis tracks the net ecosystem carbon balance over 50years for two scenarios (1) fuels reduction treatment combined with bioenergy production, and (2) a baseline scenario of no action. The study includes above and belowground carbon stocks, removals from harvesting, emissions from harvesting and transporting the removed biomass, and disturbance by wildfire. We evaluate a range of fire rotations, from an historic short rotation to a modern long rotation. In this study, when the fire rotation is 31years or less, fuels treatment and bioenergy result in a net increase in carbon stocks after 50years compared to a baseline of no action. When fire rotations exceed 31years the carbon balance shifts and the baseline scenario holds more carbon after 50years than the fuels treatment. Over the 50-year period, future wildfire is the greatest source of emissions unless fire rotations are greater than 200years, when emissions from the combustion of biomass for energy are greater. Emissions from mechanical treatments and transportation of the woody biomass are each less than 1% of total emissions. The results of this case study suggest that there is no single answer to whether fuels reduction treatments with bioenergy production create net carbon benefit. Managers will need to evaluate fuels treatments on a case-by-case or regional basis to determine net carbon outcomes. The life cycle approach presented here is a useful methodology for such determinations. [Copyright &y& Elsevier]

We describe the effects of nitrogen oxide (NOx) and organic reactivity reductions on the frequency of high ozone days in California's San Joaquin Valley. We use sixteen years of observations of ozone, nitrogen oxides, and temperature at sites upwind, within, and downwind of three cities to assess the probability of exceeding the California 8h average ozone standard of 70.4 ppb at each location. The comprehensive data records in the region and the steep decreases in emissions over the last decade are sufficient to constrain the relative import of NOx and organic reactivity reductions on the frequency of violations. We show that high ozone has a large component that is due to local production, as the probability of exceeding the state standard is lowest for each city at the upwind site, increases in the city center, is highest at downwind locations, and then decreases at the receptor city to the south. We see that reductions in organic reactivity have been very effective in the central and northern regions of the San Joaquin but less so in the southern portion of the Valley. We find evidence for two distinct categories of reactivity sources: one source that has decreased and dominates at moderate temperatures, and a second source that dominates at high temperatures, particularly in the southern San Joaquin, and has not changed over the last twelve years. We show that NOx reductions are already effective or are poised to become so in the southern and central Valley, where violations are most frequent, as conditions in these regions have or are transitioning to NOx-limited chemistry when temperatures are hottest and high ozone most probable. [ABSTRACT FROM AUTHOR]

Abstract: Different organic compounds exhibit different propensities for ozone formation. Two approaches were used to study the ozone formation potentials or source reactivities of different anthropogenic organic compounds emission categories in California''s South Coast Air Basin (SoCAB). The first approach was based on the combination of total organic gases (TOG) emission speciation profiles and the maximum incremental reactivity (MIR) scale of organic species. The second approach quantified ozone impacts from different emission sources by performing 3-dimensional air quality model sensitivity analysis involving increased TOG emissions from particular sources. The source reactivities derived from these two approaches agree reasonably well for 58 anthropogenic organic compounds emission categories in the SoCAB. Both approaches identify TOG emissions from mobile sources as having the highest reactivity. Source reactivities from both approaches were also combined with TOG emissions from each source category to produce a 2005 reactivity-based anthropogenic TOG emission inventory for the SoCAB. The top five reactivity-based anthropogenic TOG emission sources in the SoCAB during 2005 were: light-duty passenger cars, off-road equipment, consumer products, light-duty trucks category 2 (i.e., 3751–5750 lb), and recreational boats. This is in contrast to the mass-based TOG emission inventory, which indicates that livestock waste and composting emission categories were two of the five largest mass-based anthropogenic TOG emission sources. The reactivity-based TOG emission inventory is an important addition to the mass-based TOG emission inventory because it represents the ozone formation potentials from emission sources and can be used to assist in determining targeted sources for developing organic compounds reduction policies. [Copyright &y& Elsevier]

Abstract: This paper investigates snow albedo changes in the Sierra Nevada Mountain area associated with potential deposition of absorbing aerosols in spring by using the snow albedo, aerosol optical depth, land surface temperature, and other relevant parameters available from the Moderate-Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Terra satellite during 2000–2009. Satellite pixels with 100% snow cover have been selected to derive the monthly mean snow albedo value, along with aerosol optical depth, surface temperature, and days after snowfall in March and April to perform multiple regression analysis. We show that aerosol optical depth, which generally includes dust and black carbon over the Sierra Nevada as a result of the transpacific transport from East Asia and local sources, represents a significant parameter affecting snow albedo variation, second only to the land surface temperature change. The regression analysis illustrates that a one standard deviation increase in land surface temperature (2.2 K) and aerosol optical depth (0.044) can lead to decreases in snow albedo by 0.038 and 0.026, respectively. This study also shows that approximately 26% of snow albedo reduction from March to April over the Sierra Nevada is caused by an increase in aerosol optical depth, which has a profound impact on available water resources in California. However, the results show that there are no significant trends for snow albedo, surface temperature, and aerosol optical depth of snow-covered areas over the Sierra Nevada Mountain area in this 10-year period. [Copyright &y& Elsevier]

Abstract: The rate of wave overtopping of a barrier beach is measured and modeled. Unique rate of wave overtopping field data are obtained from the measure of the Carmel River, California, lagoon filling during a time when the lagoon is closed-off with no river inflow. Volume changes are based on measured lagoon height changes applied to a measured hypsometric curve. Wave heights and periods are obtained from directional wave spectra data in 15m fronting the beach. Beach morphology was measured by GPS walking surveys. Three empirical overtopping models by Van der Meer and Janssen (1995), Hedges and Reis (1998) and Pullen et al. (2007) with differing parameterizations on wave height, period and beach slope and calibrated using extensive laboratory data obtained over plane, impermeable beaches are applied in a quasi-2D manner and compared with the field observations. Three overtopping events are considered when morphology data were available less than 2weeks prior to the event. The models are tuned to fit the data using a reduction factor to account for beach permeability, berm characteristics, non-normal wave incidence and surface roughness influence. In addition, the run-up model by Stockdon et al. (2006) based on field data is examined and found to underestimate run-up as the calculated values were too small to predict any of the observed overtopping. The three overtopping models performed similarly well with values of 0.72–0.87 for the two narrow-banded wave cases, with an average reduction factor of 0.78. The European model (Pullen et. al., 2007) performed best overall and in particular for the case of the broad-banded, double peaked wave spectrum. [Copyright &y& Elsevier]

Powder metallurgical research is rather like the examination of fractals. No matter how much you discover, there is always more detail to be investigated. One example of this is the deceptively simple hydrogen reduction of tungsten and molybdenum precursors, just a few facets of which were investigated in two papers at the recent MPIF Refractory and Hard Materials Conference in San Francisco. Ken Brookes investigates. [ABSTRACT FROM AUTHOR]

Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by 30% between 2001 and 2008. Here we use an observation-based method to quantify net ozone (O3) production rates in the out-flow from the Sacramento metropolitan region and examine the O3 decrease resulting from reductions in NOx emissions. This observational method does not rely on assumptions about detailed chemistry of ozone production, rather it is an independent means to verify and test these assumptions. We use an instantaneous steady-state model as well as a detailed 1-D plume model to aid in interpretation of the ozone production inferred from observations. In agreement with the models, the observations show that early in the plume, the NOx dependence for Ox (Ox =O3 +NO2) production is strongly coupled with temperature, suggesting that temperature-dependent biogenic VOC emissions and other temperature-related effects can drive Ox production between NOx-limited and NOxsuppressed regimes. As a result, NOx reductions were found to be most effective at higher temperatures over the 7 year period. We show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx concentrations (and presumably emissions) by an additional 30% (relative to 2007 levels) will eliminate violations of the state 1 h standard in the region. If current trends continue, a 30%decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the Sacramento region appears to be imminent. [ABSTRACT FROM AUTHOR]

Tidal wetlands can be important sources of methylmercury (MeHg) in aquatic ecosystems. As a result wetland restoration could increase MeHg concentrations. Previous research has shown that addition of Fe[II] to wetland sediment can reduce MeHg production by decreasing concentrations of bioavailable Hg complexes with dissolved sulfur species. In this study, the potential for reducing MeHg production via an iron amendment was evaluated in laboratory microcosms that used intact sediments from a tidal marsh in San Francisco Bay. The micracosms were maintained under simulated tidal conditions and amended at four iron doses (0, 180, 360, and 720 g-Fe/m²). Two experiments were conducted: one with devegetated sediments and one with live wetland vegetation. Following iron addition to the devegetated sediments, porewater S[-II] concentrations decreased for each dose relative to the control with the average weekly export of MeHg in the surface water decreased by 82% and 89% for the two highest doses, respectively. Despite substantial variability within treatment groups, similar trends were observed for the vegetated microcosms. The results suggest that iron addition has the potential to provide a landscape-scale control on MeHg released by restored tidal wetlands; however, additional research is required to evaluate the efficacy of this approach under field conditions. [ABSTRACT FROM AUTHOR]

Abstract: A benefit of wetland preservation and restoration is the ecosystem service of improving water quality, typically assessed based on bacterial loading. The Ballona Wetlands, a degraded salt marsh of approximately 100 ac located on the southern border of Marina Del Rey (Los Angeles County, California, USA) are currently the focus of publicly funded restoration planning. The wetlands receive tidal water, usually contaminated with fecal indicator bacteria (FIB: total and fecal coliforms, Escherichia coli, enterococci) from the adjacent Ballona Creek and Estuary. During the summer of 2007, two 24-h studies were conducted to determine FIB tidal dynamics within the wetland. Measurements of water flow and mean FIB concentrations (n = 3) were measured every 1.5 h to determine total FIB load estimates. FIB loading rates (MPN/s) were greatest during flood tides as water entered the wetlands, and then again during spring tide conditions when sediments were resuspended during swifter spring ebb flows. During daylight hours, the wetland acted as a sink for these bacteria as loads diminished, presumably by sunlight and other processes. Conversely, during late afternoon and night, the wetlands shifted to being a source as excess FIB departed on ebb flows. Therefore, the wetlands act as both a source and sink for FIB depending on tidal conditions and exposure to sunlight. Future restoration actions would result in a tradeoff – increased tidal channels offer a greater surface area for FIB inactivation, but also would result in a greater volume of FIB-contaminated resuspended sediments carried out of the wetlands on stronger ebb flows. As levels of FIB in Ballona Creek and Estuary diminish through recently established regulatory actions, the wetlands could shift into a greater sink for FIB. [ABSTRACT FROM AUTHOR]

Chromium stable isotope ratios show promise at indicators of Cr(VI) reduction in groundwater, but no published study has yet demonstrated that expected relationships between 53Cr/52Cr and Cr(VI) concentration, position, and time occur in an actual groundwater plume. We present an extensive data set from a point-source plume in Berkeley, CA; data extend over 5 years and 14 locations covering the entire plume. We interpret the data using a Rayleigh distillation model with an effective fractionation factor that incorporates an intrinsic fractionation factor determined from incubations of site sediments and accounts for reservoir effects in the restricted subsurface zones where Cr(VI) reduction is thought to occur. The groundwater 53Cr/52Cr and Cr(VI) concentration data are consistent with a scenario where the system has reached a steady state: Cr(VI) reduction continues, the extent of reduction at any point is constant over time, reduction proceeds to completion at the downgradient edge of the plume, and the plume is no longer advancing. The overall consistency of the results with a reasonable model for the site supports the use of Cr isotope-based estimates of reduction, hut we discuss current uncertainties and limitations of the approach as well. [ABSTRACT FROM AUTHOR]

A personalized account is presented that reveals the real stories behind the development of copper hydride chemistry at UCSB over the past decade: names, events, and the thinking behind the discoveries. Both achirally ligated and nonracemically complexed copper hydride reagents are discussed within the context of the field as a whole. 1 Introduction 2 Early Ligand Effects 3 The BIPHEP Story 4 Enter JOSIPHOS 5 Copper Hydride + SEGPHOS: Another Great Match 6 Copper Hydride Contained... in a Bottle 7 (BDP)CuH: A 'Hot' Achiral Source of Copper Hydride 8 New Areas for Copper Hydride Chemistry 8.1 Reductive Aldol Reactions 8.2 Copper Hydride Chemistry in Water 9 Summary and Outlook [ABSTRACT FROM AUTHOR]

Ammonium perchlorate, a component of rocket fuel, entered Lake Mead through drainage and shallow groundwater in the Las Vegas Valley, Nevada, and is now found in the lower Colorado River from Lake Mead to the international boundary with Mexico. Perchlorate is a threat to human health through reduction of thyroid hormone production. Perchlorate has been found in water throughout the lower Colorado system and in crops in the California’s Imperial Valley, as well as in several other states, but it has not previously been included in investigations of the Salton Sea. Because perchlorate behaves conservatively in the Colorado River, it was postulated that it could be accumulating at high levels along with other salts in the Salton Sea. Results show that perchlorate is not accumulating in the Sea, although it is present in tributaries to the Sea at levels similar to those found in the Colorado River. Bacterial reduction of perchlorate is the most likely explanation for the observed results. [ABSTRACT FROM AUTHOR]

We present results from field studies at two central California dairies that demonstrate the prevalence of saturated-zone denitrification in shallow groundwater with ³H/³He apparent ages of <35 years. Concentrated animal feeding operations are suspected to be major contributors of nitrate to groundwater, but saturated zone denitrification could mitigate their impact to groundwater quality. Denitrification is identified and quantified using N and 0 stable isotope compositions of nitrate coupled with measurements of excess N2 and residual NO3- concentrations. Nitrate in dairy groundwater from this study has δ15N values (4.3–61‰), and δ18O values (-4.5–24.5‰) that plot with δ18O/δ15N slopes of 0.47–0.66, consistent with denitrification. Noble gas mass spectrometry is used to quantify recharge temperature and excess air content. Dissolved N2 is found at concentrations well above those expected for equilibrium with air or incorporation of excess air, consistent with reduction of nitrate to N2. Fractionation factors for nitrogen and oxygen isotopes in nitrate appear to be highly variable at a dairy site where denitrification is found in a laterally extensive anoxic zone 5 m below the water table, and at a second dairy site where denitrification occurs near the water table and is strongly influenced by localized lagoon seepage. [ABSTRACT FROM AUTHOR]

A feasibility evaluation identified chemical reduction and biostimulation as a potential remedy for a plume containing hexavalent chromium (Cr(VI)) and tetrachloroethene (PCE) at an industrial site in southern California. The objectives of this laboratory study were to determine the stoichiometry of calcium polysulfide (CaS x ) reaction with Cr(VI) in the presence of sediment, the effect of CaS x on the potential for in situ biological reductive dechlorination of PCE, and the potential to reduce Cr(VI) and PCE by addition of only an electron donor. Approximately 1 L of CaS x solution (containing 50 g S 2- /L) was required per 1000 L of groundwater containing 45 mg/L of Cr(VI) (i.e., 1.8 mol S 2- per mol Cr(VI)). The sediment also exerted a sulfide demand (≥0.38 g S 2 - per kg sediment), but at a slower rate than the Cr(VI). In microcosms prepared with lactate, corn syrup, soybean oil, or methanol, but no CaS x , the Cr(VI) was biologically reduced in the treatments with lactate and corn syrup, but much more slowly than with CaS x . Even after 20 months of incubation, no significant reductive dechlorination of PCE occurred in any of the microcosms, including those in which the Cr(VI) was removed with CaS x . Bioaugmentation was tested with the microcosms that received lactate and corn syrup (following 20 months of incubation), using an enrichment culture that actively dechlorinates trichloroethene. PCE dechlorination began within 1 month in the lactate-only treatment; in the corn syrup–amended treatment, PCE dechlorination occurred in only one of the three bottles. However, no PCE dechlorination occurred following bioaugmentation of the lactate and corn syrup microcosms that were initially treated with CaS x , indicating that CaS x (and/or its reaction products) exerted a negative impact on the chlororespiring microbes. This outcome highlights the need to evaluate sites on a case-by-case basis when in situ chemical treatment is applied prior to microbial reductive dechlorination. [ABSTRACT FROM AUTHOR]

Presents a study that examined the depth distribution and temperature dependence of sulfate reduction by thermophilic bacteria in hydrothermal surface sediments of the southern trough of the Guaymas Basin in California. Description of the hydrothermal sediments; Profiles of temperature and sulfate; Examination of the reduction of sulfate in sediment cores; Influence of temperature on sediment sulfate reduction.

Dissimilatory reduction of arsenate (DAsR) occurs in the arsenic-rich, anoxic water column of Mono Lake, California, yet the microorganisms responsible for this observed in situ activity have not been identified. To gain insight as to which microorganisms mediate this phenomenon, as well as to some of the biogeochemical constraints on this activity, we conducted incubations of arsenate-enriched bottom water coupled with inhibition/amendment studies and Denaturing Gradient Gel Electrophoresis (DGGE) characterization techniques. DAsR was totally inhibited by filter-sterilization and by nitrate, partially inhibited (~50%) by selenate, but only slightly (~25%) inhibited by oxyanions that block sulfate-reduction (molybdate and tungstate). The apparent inhibition by nitrate, however, was not due to action as a preferred electron acceptor to arsenate. Rather, nitrate addition caused a rapid, microbial re-oxidation of arsenite to arsenate, which gave the overall appearance of no arsenate loss. A similar microbial oxidation of As(III) was also found with Fe(III), a fact that has implications for the recycling of As(V) in Mono Lake's anoxic bottom waters. DAsR could be slightly (10%) stimulated by substrate amendments of lactate, succinate, malate, or glucose, but not by acetate, suggesting that the DAsR microflora is not electron donor limited. DGGE analysis of amplified 16S rDNA gene fragments from incubated arsenate-enriched bottom waters revealed the presence of two bands that were not present in controls without added arsenate. The resolved sequences of these excised bands indicated the presence of members of the epsilon (Sulfurospirillum) and delta (Desulfovibrio) subgroups of the Proteobacteria, both of which have representative species that are capable of anaerobic growth using arsenate as their electron acceptor. [ABSTRACT FROM AUTHOR]