Assessing hyporheic exchange and associated travel times by hydraulic, chemical, and isotopic monitoring at the Steinlach Test Site, Germany

First results of a multi-disciplinary hyporheic monitoring study are presented from the newly established Steinlach Test Site in Southern Germany. The site is located in a bend of the River Steinlach (mean discharge of 1.8 m³/s) underlain by an alluvial sandy gravel aquifer connected to the stream. The overall objective is a better understanding of hyporheic exchange processes at the site and their interrelations with microbial community dynamics and biochemical reactions at the stream–groundwater interface. The present paper focuses on the distribution of lateral hyporheic exchange fluxes and their associated travel times at the Steinlach Test Site. Water level dynamics in various piezometers correspond to the different domains of hydraulic conductivity in the shallow aquifer and confirms hyporheic exchange of infiltrated stream water across the test site. Hydrochemical compositions as well as increased damping of continuous time series of electrical conductivity (EC) and temperature at the respective piezometers confirmed the inferred distribution of hyporheic flowpaths. Mean travel times ranging from 0.5 days close to the stream to more than 8 days in the upstream part of the test site could be estimated from deconvolution of EC and δ¹⁸O–H₂O data. The travel times agree well with the presumed flowpaths. Mg/Ca ratios as well as model fits to the EC and δ¹⁸O data indicate the presence of an additional water component in the western part of the test site which most likely consists of hillslope water or groundwater. Based on the mean travel times, the total lateral hyporheic exchange flux at the site was estimated to be of the order of 1–2 L/s.     

Mineralogical and chemical evolution of ochreous precipitates from the Libiola Fe–Cu-sulfide mine (Eastern Liguria,Italy)

The mineralogical and chemical evolution of ochreous precipitates forming from acid mine drainage (AMD) from the abandoned Libiola Fe–Cu-sulfide mine (Eastern Liguria, Italy) was followed through a multianalytical approach (XRD, TEM, XRF, ICP) applied to surface precipitates and associated waters collected from several mine adits. The mineralogy of the precipitates changed significantly as a consequence of the variations of the chemical parameters of the circulating solutions (mainly pH, Eh, and sulfate concentrations) which, in turn, were mainly controlled by mixing with unpolluted stream and rill waters of the mining area. A progressive transition from jarosite-, to schwertmannite-, to goethite-, to ferrihydrite-, to amorphous-dominated precipitates was observed, mainly as a consequence of an increase in the pH of the associated solutions. This mineralogical evolution agrees well with the aqueous speciation and Eh–pH stability calculations performed on the waters associated with the different precipitate types. Furthermore, TEM analysis indicated that metastable pristine phases (schwertmannite) tend to transform progressively to well-crystallized more stable species, here represented by goethite. The comparison of the water chemistry and the crystal chemistry of the different precipitates showed a significant decrease in the Zn, Cu, Ni, Co contents in waters where the coexisting precipitates were almost exclusively composed of goethite. The distribution of V, Sr, As concentrations within the different precipitates showed that the most efficient scavenging phase for these elements was jarosite, whereas ferrihydrite efficiently took up Pb ions, and schwermannite acted as a natural sink for Cr.     

http://www.sciencedirect.com/science/article/pii/S1674987112000837

The Venda Nova Pluton(VNP) is a zoned ring structure emplaced in the southern portion of the Neoproterozoic Aracuai Belt,in Espirito Santo.Brazil.It is a slightly westward tilted cylinder-like intrusion,with an almost circular horizontal section.In the center of this structure,an off-centered gabbro-noritic core,surrounded by syeno-monzonitic rocks,intrudes an outer ring of charnockites and norite.These envelop the syeno-monzonitic and gabbro-noritic center,as a narrow discontinuous belt. While,in the core intrusion,mingling and mixing processes are widespread and well documented in the literature,in the outer ring,the norite and charnockite layers show predominantly homogeneous and isotropic internal structures.Nevertheless,smaller interaction zones between charnockites and norite denote a comparatively more restricted mingling process.The norite is a fine-grained rock with hypidiomorphic granular to intergranular texture.The charnockites are medium-grained and made up of: (a) orthopyroxene-tonalite.(b) orthopyroxene-quartz-diorite,and(c) orthopyroxene-granodiorite with hypidiomorphic granular to porphyritic textures.In all lithotypes both ortho- and clinopyroxene are replaced by hornblende and biotite.Two contrasting compositional sequences have been recognized,based on whole rock geochemistry:(1) a basic,with tholeiitic affinities(norite) and,(2) an intermediate. medium-K calc-alkaline,comprising the charnockites.Estimated crystallization temperatures,which have been calculated from micro-probe analysis of pyroxenes,range from 915±25℃to 960±50℃.Re-equilibration temperature(ilmenite-magnetite calibration) is around 600±50℃.This indicates oxygen fugacities four order of magnitude below the FMQ-buffer and a reduced environment. Coeval pressure conditions estimated from the Al-content in hornblende range from 5.5±0.6 kbar.Data obtained for the norite point toward an evolution from the partial melting of an anhydrous tholeiitic mantle magma.The charnockites may correspond to the differentiation of a calc-alkaline parental magma.The later could be the hybrid product from the contamination and mixing between the anhydrous tholeiitic magma with other deeper crustal sources.Further the magmatic system evolved through fractionation of orthopyroxene.clinopyroxene.plagioclase and ilmenite.Our results support the hypothesis for the evolution of the Venda Nova Pluton through a mantle-crust delamination process probably related to the collapse of the Aracuai orogeny.     

Presence of plastic debris in loggerhead turtle stranded along the Tuscany coasts of the Pelagos Sanctuary for Mediterranean Marine Mammals (Italy)

This work evaluated the presence and the frequency of occurrence of marine litter in the gastrointestinal tract of 31 Caretta caretta found stranded or accidentally bycaught in the North Tyrrhenian Sea. Marine debris were present in 71% of specimens and were subdivided in different categories according to Fulmar Protocol (OSPAR 2008). The main type of marine debris found was user plastic, with the main occurrence of sheetlike user plastic. The small juveniles showed a mean ± SD of marine debris items of 19.00 ± 23.84, while the adult specimens showed higher values of marine litter if compared with the juveniles (26.87 ± 35.85). The occurrence of marine debris observed in this work confirms the high impact of marine debris in the Mediterranean Sea in respect to other seas and oceans, and highlights the importance of Caretta caretta as good indicator for marine litter in the Marine Strategy Framework Directive (MSFD) of European Union.     

Environmental Impact Assessment of High Pressure Water Scrubbing Biogas Upgrading Technology

The aim of this work was to assess the burdens of a process in terms of environmental and health impacts, resource depletion issues, and energy demand based on the ability of the Life Cycle Assessment methodology to link the environmental impacts with the mass and energy flows. The analysis was done in terms of process and environmental performances of high pressure water scrubbing (HPWS) system applied for biogas upgrading. The application of process simulation based on the Aspen Plus® software has been considered as supportive for the calculation of mass and energy balances. Data processed using GaBi 4: Software showed that global warming, acidification, and human toxicity potentials were the main impact categories associated with the HPWS process. These indicators are largely related to the exhaust gas from the desorption column and the indirect emissions generated during energy consumption. The life cycle inventory study resulted in the development of a database with a vast inventory of data regarding HPWS technology. A basis for assessing potential improvements in the environmental performance of the system is provided. Future studies in this area will address the economical evaluation of the HPWS technology, so as to maximize economic efficiency and minimize environmental impacts.     

C/1995 O1 Hale–Bopp: Short and Long Distance activity from a Theoretical Model

A theoretical model of the nucleus thermal evolutionand differentiation is used to simulatethe evolution along the orbit of the gasand dust emissions of comet Hale–Bopp. The model was already applied to this comet (Capria et al., 2000b): At that time only the results of the observations obtained shortly after the perihelion were available. Now much more data have been published and we present more refined and complete results about the production rates of gasand dust along the orbit and the internal stratigraphy. The results of our model on long distance activity and its explanation are also presented.     

Using a WebMapping Platform to Engage Volunteers to Collect Data on Invasive Plants Distribution

WebMapping and citizen science are increasing their importance as tools both in science communication and in gathering abundant data. Nevertheless, gathering good and plentiful data from citizens when the scientific theme is unknown to them is a demanding challenge. Invasoras.pt is a science communication endeavor that targets the general public and one of its core elements is a WebMapping platform that intends to engage volunteers to geolocate invasive plants in Portugal. Besides gathering data for scientific research and to support management, the platform raises awareness about invasive plants. The platform has been available since March 2013 and receives data from a smartphone application and a Web application. Validated sightings are shown on an online map. All data is available through a Google Fusion Table and GBIF database (open data logic). Several strategies (interactive contents, printed materials, workshops and social media) were used to overcome the challenges of engaging contributors and making them better skilled to contribute with good data. After two years of steady growth in members (ca. 600) and sightings (>5400) the results are better than expected particularly amongst a population not familiarized with either citizen science or invasive plants. The outcomes of the platform and the efficacy of each strategy are analyzed and the accuracy and usefulness of the data are discussed.     

A Numerical Study of Wind-Turbine Wakes for Three Atmospheric Stability Conditions

The effects of atmospheric stability on wind-turbine wakes are studied via large-eddy simulations. Three stability conditions are considered: stable, neutral, and unstable, with the same geostrophic wind speed aloft and the same Coriolis frequency. Both a single 5-MW turbine and a wind farm of five turbines are studied. The single-turbine wake is strongly correlated with stability, in terms of velocity deficit, turbulence kinetic energy (TKE) and temperature distribution. Because of the Coriolis effect, the wake shape deviates from a Gaussian distribution. For the wind-farm simulations, the separation of the core region and outer region is clear for the stable and neutral cases, but less distinct for the unstable case. The unstable case exhibits strong horizontal variations in wind speed. Local accelerations such as related to aisle jets are also observed, whose features depend on stability. The added TKE in the wind farm increases with stability. The highest power extraction and lowest power deficit are observed for the unstable case.     

Fusion of airborne LiDAR and multispectral sensors reveals synergic capabilities in forest structure characterization

Forest stand structure is an important concept for ecology and planning in sustainable forest management. In this article, we consider that the incorporation of complementary multispectral information from optical sensors to Light Detection and Ranging (LiDAR) may be advantageous, especially through data fusion by back-projecting the LiDAR points onto the multispectral image. A multivariate data set of both LiDAR and multispectral metrics was related with a multivariate data set of stand structural variables measured in a Scots pine forest through canonical correlation analysis (CCA). Four statistically significant pairs of canonical variables were found, which explained 83.0% accumulated variance. The first pair of canonical variables related indicators of stand development, i.e. height and volume, with LiDAR height metrics. CCA also found attributes describing stand density to be related to LiDAR and spectral variables determining canopy coverage. Other canonical variables pertained to Lorenz curve-derived attributes, which are measures of within-stand tree size variability and heterogeneity, able to discriminate even-sized from uneven-sized stands. The most relevant result was to find that metrics derived from the multispectral sensor showed significant explanatory potential for the prediction of these structural attributes. Therefore, we concluded that metrics derived from the optical sensor have potential for complementing the information from the LiDAR sensor in describing structural properties of forest stands. We recommend the use of back-projecting for jointly exploiting the synergies of both sensors using similar types of metrics as they are customary in forestry applications of LiDAR.