Lipid biomarkers and bacterial lipase activities as indicators of organic matter and bacterial dynamics in contrasted regimes at the DYFAMED site, NW Mediterranean

This study investigated the relationships between dissolved organic matter (DOM) composition and bacterial dynamics on short time scale during spring mesotrophic (March 2003) and summer oligotrophic (June 2003) regimes, in a 0–500 m depth water column with almost no advection, at the DYFAMED site, NW Mediterranean. DOM was characterized by analyzing dissolved organic carbon (DOC), colored dissolved organic matter (CDOM) and lipid class biotracers. Bacterial dynamic was assessed through the measurement of in situ bacterial lipase activity, abundance, production and bacterial community structure. We made the assumption that by coupling the ambient concentration of hydrolysable acyl-lipids with the measurement of their in situ bacterial hydrolysis rates (i.e. the free fatty acids release rate) would provide new insights about bacterial response to change in environmental conditions. The seasonal transition from spring to summer was accompanied by a significant accumulation of excess DOC (+5 μM) (ANOVA, p<0.05, n=8) in the upper layer (0–50 m). In this layer, the free fatty acids release rate to the bacterial carbon demand (BCD) ratio increased from 0.6±0.3 in March to 1.3±1.0 in June (ANOVA, p<0.05, n=8) showing that more uncoupling between the hydrolysis of the acyl-lipids and the BCD occurred during the evolution of the season, and that free fatty acids contributed to the excess DOC. The increase of lipolysis index and CDOM absorbance (from 0.24±0.17 to 0.39±0.13 and from 0.076±0.039 to 0.144±0.068; ANOVA, p<0.05, n=8, respectively), and the higher contribution of triglycerides, wax esters and phospholipids (from <5% to 12–31%) to the lipid pool reflected the change in the DOM quality. In addition to a strong increase of bacterial lipase activity per cell (51.4±29.4–418.3±290.6 Ag C cell⁻¹ h⁻¹), a significant percentage of ribotypes (39%) was different between spring and summer in the deep chlorophyll maximum (DCM) layer in particular, suggesting a shift in the bacterial community structure due to the different trophic conditions. At both seasons, in the chlorophyll layers, diel variations of DOM and bacterial parameters reflected a better bioavailability and/or DOM utilization by bacteria at night (the ratio of free fatty acids release rate to bacterial carbon demand decreased), most likely related to the zooplankton trophic behaviour. In mesotrophic conditions, such day/night pattern was driving changes in the bacterial community structure. In more oligotrophic period, diel variations in bacterial community structure were depth dependent in relation to the strong summer stratification.     

Origin of Sierra Nevadan granite: evidence from small scale composite dikes

Composite dikes at Hell Hole Meadow, in the central Sierra Nevada, contain hybrids created by small scale mixing of andesitic and rhyolitic magmas. Early rhyolitic injections had partially solidified when subsequent andesitic magmas arrived and mixed with small increments of remnant rhyolitic magma. In major element chemistry, the hybrid rocks define linear MgO-variation diagrams that closely resemble those for the Half Dome, Mt. Givens, and Eagle Peak granodiorites. The patterns suggest that mixing of mafic and felsic magmas has been important in the evolution of these plutons.Hornblendes in three Hell Hole Meadow hybrid rocks ranging from dacite to andesite display indistinguishable crystal-chemical variation patterns. The crystals apparently developed as phenocrysts of endmember andesitic magma prior to the mixing event and retained their compositional character in the hybridization event. Plutonic hornblendes (Dodge et al. 1968; Noyes et al. 1983) display crystal-chemical patterns nearly identical to those in the dike cores making it unlikely that the plutonic hornblendes represent restite of a complex lower crust.Hornblende chemical data from a suite of rocks collected across the width of the compositionally zoned Half Dome granodiorite (Yosemite National Park) define clusters, like their Hell Hole Meadow counterparts, that are very similar to one another despite the large range in host rock bulk composition. Sr isotopic data (Kistler et al. 1986) and linear MgO-variation patterns for the major elements (Reid et al. 1983) suggest that the Half Dome is a mixture of high-alumina basalt and rhyolitic magmas. We propose that while the bulk chemistry of hybrid granodiorites is determined by the proportions of the constituent mafic and felsic magmas, the hornblendes in the mixed rocks largely retain compositions created in the mafic component prior to mixing. Mixing may occur either by incremental addition of felsic magma into a relatively large volume of mafic magma (as at Hell Hole Meadow), or by the chilling and subsequent disaggregation of mafic pillows in a largely felsic host.     

Taking stock of Climate Change Acts in Europe: living policy processes or symbolic gestures?

Since the UK introduced a Climate Change Act (CCA) in 2008, similar legislation has followed in a number of states, with each having a slightly different take. What unites these examples is that they all represent framework legislation that aims to facilitate climate change mitigation by creating continuous policy processes whereby mechanisms for the reduction of greenhouse gas (GHG) emissions are developed and implemented. This article is concerned with the extent to which they are living policy processes or rather symbolic gestures. We analyse seven European CCAs with regard to GHG emission reduction targets, planning/implementation mechanisms, and feedback/evaluations prescribed by the laws. These three features correspond with three aspects of climate policy integration (CPI): interpretations of CPI as a norm; CPI as a process of governing; CPI as a policy outcome. We show that CCAs address all three aspects of CPI and constitute living policy processes, although to varying extents. However, CCAs are also policy processes in that they are part of a political system, affected by political forces external to the legislation, positively and negatively.

Key policy insights

• CCAs can provide a normative basis for policymaking on climate change at the national level, especially through quantitative emission reduction targets.

• Whilst CCAs can bring some stability and predictability to policymaking on climate change (mainly because legislation is more difficult to amend or remove than policy strategies), they are still vulnerable to political developments.

• Most CCAs lack either short/medium-term (Denmark, Finland, Ireland, Sweden) or long-term (Austria) targets. Given EU Member States’ aim to decarbonise in the next three decades and the Paris Agreement's global goal of pursuing efforts to limit warming to 1.5°C, states need to find ways to guide this process. One approach could be the inclusion of short-term, medium-term and long-term targets in their CCAs.

• Since sanctioning mechanisms are lacking across all the CCAs analysed here, it is not clear what will happen if legally binding targets are not met. Just as it is difficult to imagine speed limits and speed cameras without accompanying penalties, it is hard to imagine how CCAs without sanctions can deliver decarbonization.

     

Getting Canadians prepared for natural disasters: a multi-method analysis of risk perception,behaviors, and the social environment

As part of our broader research agenda on the psychology of risk communication and of risk management, we use a socio-ecological approach, inspired by Bronfenbrenner (Am Psychol 32:513–531, 1977. https://doi.org/10.1037/0003-066x.32.7.513), to better understand how Canadians perceive and prepare for risks originating from natural disasters. In this article, we present three empirical mixed-method studies as layers of analysis—a national survey, a social-spatial multi-level analysis, and a series of qualitative interviews—to bring a better understanding of how to engage Canadians in disaster preparedness and risk management. From our data, we examined how individuals perceived and understood natural disaster risks in Canada and how these fit in their social and life contexts. Given the increasingly diverse Canadian population, we used a cultural lens to contrast immigrants to Canadian-born individuals. After introducing the conceptual background and presenting our empirical studies, we conclude with a discussion on the implications for risk communication and management for natural disasters. Our findings suggest that Canadians could benefit from culturally targeted disaster risk reduction strategies that engage individuals–communities–government at all levels and are more attuned to the realities and specificities of life stressors.

     

Retrieval of Substrate Bearing Strength from Hyperspectral Imagery during the Virginia Coast Reserve (VCR’07) Multi-Sensor Campaign

Hyperspectral imagery (HSI) derived from remote sensing can delineate surface properties of substrates such as type, moisture, and grain size. These are critical parameters that determine the substrate bearing strength. Although HSI only sees the surface layer, statistics can be derived that relate surface properties to the likely bearing strength of soils in particular regions. This information can be used to provide an initial map estimate on large scales of potential bearing strength. We describe an initial validation study at the Virginia Coast Reserve relating airborne HSI to in situ spectral and geotechnical measurements through a spectral-geotechnical lookup table (LUT).     

Identification and characterization of secondary minerals formed in tungsten mine tailings using transmission electron microscopy

Secondary minerals formed in tailings derived from a W-rich deposit were investigated in detail using transmission electron microscopy (TEM). The study focused on secondary minerals that formed in the vicinity of oxidized sphalerite [ZnS] and tennantite [Cu₁₀(Fe,Zn)₂As₄S₁₃] grains. Samples for TEM analysis were prepared directly from petrographic thin sections using a focused ion beam instrument. This method insured that spatial relationships among primary grains, secondary minerals and the pore spaces were maintained. The results from this study indicate that the secondary coatings associated with sphalerite and tennantite are composed of several discrete phases. The phases identified in this study include an Fe–Zn–As–O phase, secondary sulfides, native Cu, an Fe–Si–O phase, an In–O phase, and wulfenite [PbMoO₄]. The Fe–Zn–As–O phase precipitates directly from the pore water and the nearby primary mineral grains act as a source for some of the elements (e.g., Zn from sphalerite, As from tennantite). Secondary Cu sulfides were found at the outer margins of sphalerite and roquesite [CuInS₂] grains. It is likely that these Cu sulfides form as a result of interactions between the primary grain and aqueous Cu(II) present in the pore water, similar to what occurs in supergene environments. A secondary sulfide that was composed of variable amounts of Cu, Zn, As, Fe and S was also identified along the outer margins of tennantite. Native Cu was found in association with chalcopyrite [CuFeS₂] inclusions that were present in one of the sphalerite grains and probably represents a low-temperature secondary phase. The oxidation of chalcopyrite in the presence of aqueous Si leads to the formation of a nanocrystalline or amorphous Fe–Si–O phase. Roquesite oxidation leads to the formation of a crystalline In–O phase, which is likely dzhalindite [In(OH)₃]. Wulfenite was found in the interstitial voids present in the Fe–Zn–As–O phase suggesting that it forms by direct precipitation from the local pore water. The results from this study indicate that secondary coatings consist of complex secondary phases that may only be distinguished at the nanoscale. The TEM investigations reveal details regarding mineralogical sinks and sources for aqueous components that may otherwise be overlooked.     

Defining geo-habitats for groundwater ecosystem assessments: an example from England and Wales (UK)

Groundwater ecosystems comprising micro-organisms and metazoans provide an important contribution to global biodiversity. Their complexity depends on geology, which determines the physical habitat available, and the chemical conditions within it. Despite this, methods of classifying groundwater habitats using geological data are not well established and researchers have called for higher resolution habitat frameworks. A novel habitat typology for England and Wales (UK) is proposed, which distinguishes 11 geological habitats (geo-habitats) on hydrogeological principles and maps their distribution. Hydrogeological and hydrochemical data are used to determine the characteristics of each geo-habitat, and demonstrate their differences. Using these abiotic parameters, a new method to determine abiotic habitat quality is then developed. The geo-habitats had significantly different characteristics, validating the classification system. All geo-habitats were highly heterogeneous, containing both high quality habitat patches that are likely to be suitable for fauna, and areas of low quality that may limit faunal distributions. Karstic and porous habitats generally were higher quality than fractured habitats. Overall, 70% of England and Wales are covered by lower quality fractured habitats, with only 13% covered by higher quality habitats. The main areas of high quality habitats occur in central England as north–south trending belts, possibly facilitating dispersal along this axis. They are separated by low quality geo-habitats that may prevent east-west dispersal of fauna. In south-west England and Wales suitable geo-habitats occur as small isolated patches. Overall, this paper provides a new national-scale typology that is adaptable for studies in other geographic areas.     

EUREC<Superscript>4</Superscript>A: A Field Campaign to Elucidate the Couplings Between Clouds,Convection and Circulation

Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization.     

The occurrence and behavior of radium in saline formation water of the U.S. Gulf Coast region

Radium has been measured in deep saline formation waters produced from a variety of U.S. Gulf Coast subsurface environments, including oil reservoirs, gas reservoirs and water-producing geopressured aquifers. A strong positive correlation has been found between formation-water salinity and Ra activity, resulting from the interaction of formation water with aquifer matrix. Ra isotopes enter the fluid phase after being produced by the decay of parent elements U and Th, which are located at sites on and within the solid matrix.Processes that are belived to be primarily responsible for transferring Ra from matrix to formation water are chemical leaching and alpha-particle recoil. Factors controlling the observed salinity—Ra relationship may be one or a combination of the following factors: (a) ion exchange; (b) increased solubility of matrix silica surrounding Ra atoms, coupled with a salinity-controlled rate of reequilibration of silica between solution and quartz grains; and (c) the equilibration of Ra in solution with detrial barite within the aquifer.No difference was found in the brine-Ra relation in water produced from oil or gas wells and water produced from wells penetrating only water-bearing aquifers, although the relation was more highly correlated for water-bearing aquifers than hydrocarbon-containing reservoirs.     

An integrated model of clastic injectites and basin floor lobe complexes: implications for stratigraphic trap plays

Injectites sourced from base‐of‐slope and basin‐floor parent sandbodies are rarely reported in comparison to submarine slope channel systems. This study utilizes the well‐constrained palaeogeographic and stratigraphic context of three outcrop examples exposed in the Karoo Basin, South Africa, to examine the relationship between abrupt stratigraphic pinchouts in basin‐floor lobe complexes, and the presence, controls, and character of injectite architecture. Injectites in this palaeogeographic setting occur where there is: (i) sealing mudstone both above and below the parent sand to create initial overpressure; (ii) an abrupt pinchout of a basin‐floor lobe complex through steep confinement to promote compaction drive; (iii) clean, proximal sand beds aiding fluidization; and (iv) a sharp contact between parent sand and host lithology generating a source point for hydraulic fracture and resultant injection of sand. In all outcrop cases, dykes are orientated perpendicular to palaeoslope, and the injected sand propagated laterally beneath the parent sand, paralleling the base to extend beyond its pinchout. Understanding the mechanisms that determine and drive injection is important in improving the prediction of the location and character of clastic injectites in the subsurface. Here, we highlight the close association of basin‐floor stratigraphic traps and sub‐seismic clastic injectites, and present a model to explain the presence and morphology of injectites in these locations.