Effects of Alpine hydropower dams on particle transport and lacustrine sedimentation     

Flavio S. Anselmetti  Raphael Bühler  David Finger  Stéphanie Girardclos  Andy Lancini  Christian Rellstab  Mike Sturm 《Aquatic Sciences - Research Across Boundaries》2007,69(2):179-198

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IGNORANCE-AND LEARNING     

Raphael G. Kazmann 《Ground water》1966,4(2):2-4

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Optimizing Wellfield Operation in a Variable Power Price Regime          下载免费PDF全文

Peter Bauer‐Gottwein  Raphael Schneider  Claus Davidsen 《Ground water》2016,54(1):92-103

Wellfield management is a multiobjective optimization problem. One important objective has been energy efficiency in terms of minimizing the energy footprint (EFP) of delivered water (MWh/m³). However, power systems in most countries are moving in the direction of deregulated markets and price variability is increasing in many markets because of increased penetration of intermittent renewable power sources. In this context the relevant management objective becomes minimizing the cost of electric energy used for pumping and distribution of groundwater from wells rather than minimizing energy use itself. We estimated EFP of pumped water as a function of wellfield pumping rate (EFP‐Q relationship) for a wellfield in Denmark using a coupled well and pipe network model. This EFP‐Q relationship was subsequently used in a Stochastic Dynamic Programming (SDP) framework to minimize total cost of operating the combined wellfield‐storage‐demand system over the course of a 2‐year planning period based on a time series of observed price on the Danish power market and a deterministic, time‐varying hourly water demand. In the SDP setup, hourly pumping rates are the decision variables. Constraints include storage capacity and hourly water demand fulfilment. The SDP was solved for a baseline situation and for five scenario runs representing different EFP‐Q relationships and different maximum wellfield pumping rates. Savings were quantified as differences in total cost between the scenario and a constant‐rate pumping benchmark. Minor savings up to 10% were found in the baseline scenario, while the scenario with constant EFP and unlimited pumping rate resulted in savings up to 40%. Key factors determining potential cost savings obtained by flexible wellfield operation under a variable power price regime are the shape of the EFP‐Q relationship, the maximum feasible pumping rate and the capacity of available storage facilities.  相似文献   

Bismuth selenides from St. Andreasberg,Germany: an oxidised five-element style of mineralisation and its relation to post-Variscan vein-type deposits of central Europe     

Cabral  Alexandre Raphael  Ließmann  Wilfried  Jian  Wei  Lehmann  Bernd 《International Journal of Earth Sciences》2017,106(7):2359-2369

International Journal of Earth Sciences - Carbonate veinlets at Roter Bär, a former underground mine in the polymetallic St. Andreasberg vein district of the Harz Mountains, Germany, host...  相似文献   

Ocean urea fertilization for carbon credits poses high ecological risks     

Glibert PM  Azanza R  Burford M  Furuya K  Abal E  Al-Azri A  Al-Yamani F  Andersen P  Anderson DM  Beardall J  Berg GM  Brand L  Bronk D  Brookes J  Burkholder JM  Cembella A  Cochlan WP  Collier JL  Collos Y  Diaz R  Doblin M  Drennen T  Dyhrman S  Fukuyo Y  Furnas M  Galloway J  Granéli E  Ha DV  Hallegraeff G  Harrison J  Harrison PJ  Heil CA  Heimann K  Howarth R  Jauzein C  Kana AA  Kana TM  Kim H  Kudela R  Legrand C  Mallin M  Mulholland M  Murray S  O'Neil J  Pitcher G  Qi Y  Rabalais N  Raine R  Seitzinger S  Salomon PS  Solomon C 《Marine pollution bulletin》2008,56(6):1049-1056

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.  相似文献   

Comment on “Complex Inversion of MRT Signals under Different Loop Configurations for Groundwater Exploration” by Bin Chen,Xiangyun Hu,Jianhui Li,Yajun Liu, 2016, v. 55, no. 2: 171‐182          下载免费PDF全文

Mike Müller‐Petke  Chuandong Jiang  Thomas Günther  Raphael Dlugosch 《Ground water》2017,55(3):289-290

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The promise and pitfalls of Marine Stewardship Council certification: Maine lobster as a case study     

Wendy Goyert  Raphael Sagarin  John Annala 《Marine Policy》2010

As worldwide population continues to grow, so does demand for seafood by consumers. With this trend, interest in sustainably certified seafood is also increasing. The Maine lobster fishery is currently considering certification based on the Marine Stewardship Council (MSC) standard for sustainable and well-managed fisheries. Although certification is argued to provide a market-based incentive to improve sustainable fishing practices, it is a costly and time-consuming process, and often imposes additional requirements on fisheries in order to meet certification standards. To evaluate whether the costs of Maine lobster fishery certification are worth the presumed benefits, lobster industry members were interviewed to learn their opinions of MSC certification, seafood consumers were surveyed to understand their attitudes and purchasing preferences related to lobster, and lessons learned from other MSC-certified fisheries were compiled. MSC certification of the Maine lobster fishery could potentially provide benefits to the industry by differentiating Maine lobster and maintaining access to markets that are looking to exclusively source certified fish products. However, certification is unlikely to provide price premiums for the fishermen, and does not necessarily represent to consumers the most desirable aspects of Maine lobster. Certification programs may need to adapt to consumer preferences and market conditions if they are to continue to provide incentives for the sustainable management of fisheries.  相似文献   

Trophic relationships in tidepool fish assemblages of the tropical Southwestern Atlantic          下载免费PDF全文

Caio R. Pimentel  Lucy S. H. Soares  Raphael M. Macieira  Jean‐Christophe Joyeux 《Marine Ecology》2018,39(2)

Trophic studies are fundamental to understanding the dynamics of assemblages and functional roles of species within ecosystems, contributing to the identification of factors responsible for the organization and structure of communities. This study aimed to analyse the trophic organization of tidepool fish assemblages in the tropical Southwestern Atlantic, based on the underlying idea that food resources are not limiting and that trophic guild formation is not driven by food competition. Diets were based on feeding index values of food categories for 12 representative species collected in six tidepools (20º49′ S, 40º36′ W) at quarterly intervals (2005 to 2007). The main food categories were small crustaceans, polychaetes and macroalgae. Multivariate techniques evidenced two multispecific trophic guilds: small‐prey carnivores, including Bathygobius soporator, Bathygobius geminatus, Malacoctenus delalandii and Halichoeres poeyi, and herbivores, including Sparisoma axillare and Acanthurus bahianus. Other species presented significantly different diets and were classified into the following guilds: omnivores feeding on filamentous algae and copepods (Abudefduf saxatilis); large‐prey carnivores (Labrisomus nuchipinnis); omnivores feeding on polychaetes and filamentous algae (Stegastes fuscus); and polychaete feeders (Ahlia egmontis). Gymnothorax funebris and Gymnothorax moringa were classified as carcinophagores and piscivores, respectively. Trophic organization appears related to species convergence toward the use of abundant food resources, driven by a combination of factors allowing some resource partitioning through inter‐specific differences in consumer size, microhabitat, behavior, and trophic specialization.  相似文献   

Deformation-induced cordierite breakdown–An example from western Maine,USA     

Ioan V. Sanislav  Ahmed S. A. A. Abu Sharib  Raphael S. A. Quentin de Gromard 《Journal of Metamorphic Geology》2020,38(8):831-852

Preservation of partially completed metamorphic reactions in the form of partial pseudomorphs is very important as it provides direct insight onto the reaction mechanism and the phases involved in the reaction. The staurolite and andalusite grade rocks in western Maine, USA, contain cordierite porphyroblasts partly pseudomorphed by coarse-grained muscovite and biotite. The pseudomorphs consist of a cordierite core surrounded by a reaction rim. Modal mineralogy, calculated using the ImageJ processing software based on backscatter images and X-ray compositional maps, reveals that the core consists of cordierite (53.5%), muscovite (22.8%), biotite (9.1%), quartz (1 0.4%), plagioclase (3.1%) and ilmenite/pyrrhotite and apatite (1.1%) whereas the reaction rim consists of cordierite (1.8%), muscovite (51.6%), biotite (30.4%), quartz (4.3%), plagioclase (10%), garnet (1.2%), ilmenite/pyrrhotite and apatite (0.8%). The net effect of the cordierite breakdown reaction is an increase of 226% in muscovite, 334% in biotite and 323% in plagioclase content and a decrease of 97% in cordierite. The reaction involved exchange of components with the matrix requiring addition of H₂O, K⁺, Na⁺ and Ti⁴⁺ and removal of SiO₂, Mg²⁺ and PO₄^3- from the reaction site. PT estimates using the garnet–biotite, Ti-in-biotite, Na-in-cordierite thermometers and the garnet–biotite–muscovite–plagioclase barometer indicate that cordierite breakdown occurred at ~550°C and 3.5 kbar. thermocalc modelling using the bulk rock composition suggests that cordierite is not stable at these conditions, whereas modelling using a thin section-derived bulk composition indicates that cordierite stability extends to higher pressures, and most likely that the cordierite breakdown was not PT dependent. The incorporation of Na (up to 0.18 a.f.u.) into the cordierite structure has the effect of stabilizing the cordierite under a variety of H₂O activity and limiting the role of fluids into destabilizing it. The cordierite cores contain evidence of plastic and brittle deformation in the form of subgrains and microcracks, which facilitated the infiltration of fluids that destabilized cordierite at constant PT conditions by leaching Na and introducing K. New mica growth along these structural heterogeneities suggests that deformation played an important role promoting breakdown of cordierite to muscovite and biotite.  相似文献   

Physical-Ecological Response of the California Current System to ENSO events in ROMS-NEMURO     

Cordero-Quirós  Nathalí  Miller  Arthur J.  Pan  Yunchun  Balitaan  Lawrence  Curchitser  Enrique  Dussin  Raphael 《Ocean Dynamics》2022,72(1):21-36

Ocean Dynamics - We analyze the bottom-up El Niño/Southern Oscillation (ENSO) driven physical-biological response of the California Current System (CCS) in a high-resolution,...  相似文献