Hydrogeology Journal - Geological and hydrogeological conceptualizations of the five main aquifers of Malta were performed by means of characterization of the groundwater bodies’ geometries... 相似文献
Summary The complexation of aluminium(III) and silicon(IV) was studied in a simplified seawater medium (0.6 M Na(Cl)) at 25 °C. The
measurements were performed as potentiometric titrations using a hydrogen electrode with OH− ions being generated coulometrically. The total concentrations of Si(IV) and Al(III) respectively [Sitot] and [Altot], and −log[H+] were varied within the limits 0.3 < [Sitot] < 2.5 mM, 0.5 < [Altot] < 2.6 mM, and 2 ≤ -log[H+] ≤ 4.2. Within these ranges of concentration, evidence is given for the formation of an AlSiO(OH)
32+
complex with a formation constant log β1,1-1 = −2.75 ± 0.1 defined by the reaction
Al3++Si (OH)4 ↔ AlOSi(OH)
32+
+H+
An extrapolation of this value to I=0 gives log β1,1-1 = −2.30. The calculated value of logK (Al3++SiO(OH)
3−
↔ AlOSi(OH)
32+
) = 6.72 (I=0.6 M) can be compared with corresponding constants for the formation of AlF2+ and AlOH2+ , which are equal to 6.16 and 8.20. Obviously, the stability of these Al(III) complexes decreases within the series OH−>SiO(OH)
3−
> F−相似文献
Data discoverability, accessibility, and integration are frequent barriers for scientists and a major obstacle for favorable results on environmental research. To tackle this issue, the Group on Earth Observations (GEO) is leading the development of the Global Earth Observation System of Systems (GEOSS), a voluntary effort that connects Earth Observation resources world‐wide, acting as a gateway between producers and users of environmental data. GEO recognizes the importance of capacity building and education to reach large adoption, acceptance and commitment on data sharing principles to increase the capacity to access and use Earth Observations data. This article presents “Bringing GEOSS services into practice” (BGSIP), an integrated set of teaching material and software to facilitate the publication and use of environmental data through standardized discovery, view, download, and processing services, further facilitating the registration of data into GEOSS. So far, 520 participants in 10 countries have been trained using this material, leading to numerous Spatial Data Infrastructure implementations and 1,000 tutorial downloads. This workshop lowers the entry barriers for both data providers and users, facilitates the development of technical skills, and empowers people. 相似文献
Gaussian beam depth migration overcomes the single‐wavefront limitation of most implementations of Kirchhoff migration and provides a cost‐effective alternative to full‐wavefield imaging methods such as reverse‐time migration. Common‐offset beam migration was originally derived to exploit symmetries available in marine towed‐streamer acquisition. However, sparse acquisition geometries, such as cross‐spread and ocean bottom, do not easily accommodate requirements for common‐offset, common‐azimuth (or common‐offset‐vector) migration. Seismic data interpolation or regularization can be used to mitigate this problem by forming well‐populated common‐offset‐vector volumes. This procedure is computationally intensive and can, in the case of converted‐wave imaging with sparse receivers, compromise the final image resolution. As an alternative, we introduce a common‐shot (or common‐receiver) beam migration implementation, which allows migration of datasets rich in azimuth, without any regularization pre‐processing required. Using analytic, synthetic, and field data examples, we demonstrate that converted‐wave imaging of ocean‐bottom‐node data benefits from this formulation, particularly in the shallow subsurface where regularization for common‐offset‐vector migration is both necessary and difficult. 相似文献
Morishita's “multiple analysis” of the whaling issue [Morishita J. Multiple analysis of the whaling issue: Understanding the dispute by a matrix. Marine Policy 2006;30:802–8] is essentially a restatement of the Government of Japan's whaling policy, which confuses the issue through selective use of data, unsubstantiated facts, and the vilification of opposing perspectives. Here, we deconstruct the major problems with Morishita's article and provide an alternative view of the whaling dispute. For many people in this debate, the issue is not that some whales are not abundant, but that the whaling industry cannot be trusted to regulate itself or to honestly assess the status of potentially exploitable populations. This suspicion has its origin in Japan's poor use of science, its often implausible stock assessments, its insistence that culling is an appropriate way to manage marine mammal populations, and its relatively recent falsification of whaling and fisheries catch data combined with a refusal to accept true transparency in catch and market monitoring. Japanese policy on whaling cannot be viewed in isolation, but is part of a larger framework involving a perceived right to secure unlimited access to global marine resources. Whaling is inextricably tied to the international fisheries agreements on which Japan is strongly dependent; thus, concessions made at the IWC would have potentially serious ramifications in other fora. 相似文献
Ophiolites with different magmatic characteristics are closely associated in space with one another in northern Pindos. Some have affinities with ocean-floor magmas (Group I), and others represent melts which are frequently strongly depleted in «incompatible» elements (Group II). Group I is composed of cumulates, dolerites and lavas, whereas Group II occurs mainly as pillows and dykes, and postdates Group I. The two groups have different geochemical, mineralogical and petrographic features. They exhibit different Ti, Cr, Ni, Y, Zr, P, Si and Mg contents, and clinopyroxenes and spinels of Group I have higher Ti/Al and Ti/Mn ratios, and lower Cr/(Cr + Al) values respectively than those of Group II. Many rocks of Group II are chemically similar to boninites and associated rocks as well as to low-Ti basalts from other areas and ophiolitic complexes. It is concluded that geochemical and mineralogical data alone do not allow a definitive answer about the original tectonic setting of the investigated rocks, although a genesis above a subduction zone seems to be plausible hypothesis. 相似文献
Trace element partition coefficients between clinopyroxenes and associated glassy matrix (Cpx/LD) have been determined for 13 REE, HFSE4+,5+, U, Th, Sr, Pb, Sc and V from combined LA-ICP-MS/EMP analyses in selected trachytes and trachyphonolites from Campi Flegrei.
Composition of clinopyroxene and glass is pretty homogeneous in the trachyphonolites, pointing to an overall attainment of
the equilibrium conditions. In trachytes, conversely, phases show some compositional heterogeneity (due to the presence of
clinopyroxene xenocrysts) that requested a more careful petrographic and geochemical inspection of the samples to assess the
equilibrium clinopyroxene composition. In the trachyte clinopyroxenes, REE are compatible from Nd to Lu (Cpx/LD up to 2.9), like Y, Ti, Sc and V. The Cpx/LD for Eu is lower than those of the adjacent REE, highlighting Eu2+ contribution. High D values are also shown by U, Th, Pb, Zr, Hf, Nb and Ta relatively to basaltic and andesitic systems, whereas the DSr is roughly similar to that found for less evolved magmas. Trachyphonolites are characterized by an overall decrease of the
Cpx/LD for highly-charged cations (with the exception of V), and by a slight increase of DSr. REE are still compatible from Nd to Lu (Cpx/LD up to 2.1), like Ti, Y, Sc and V. This variation is also predicted for REE and Y by models based on the elastic strain theory,
being consistent with the slightly lower polymerization degree estimated for the trachyphonolites. However, the observed Cpx/LD(REE,Y) are matched by the modelled ones only considering very low T (≤825°C), which are believed unlikely. This mismatch cannot be attributed to effects induced by the water-rich composition
of the trachyte–trachyphonolite suite, since they would lower the observed Cpx/LD(REE,Y). Moreover, the anomalous inflections of measured Cpx/LD for HREE suggests some crystal-chemical control, such as the entrance of these elements in a site distinct from M2. It is
concluded that the large Cpx/LD determined for trachytes and trachyphonolites are likely induced by hitherto unconstrained changes of the Z3+ activities related to the composition of melt and/or solid. All these considerations strongly highlight the importance of
a direct characterization of trace element partitioning in natural samples from magmatic systems poorly characterized by experimental
studies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
We present the background, development, and preparation of a state-of-the-art 4D variational (4DVAR) data assimilation system in the Regional Ocean Modeling System (ROMS) with an application in the Intra-Americas Sea (IAS). This initial application with a coarse model shows the efficacy of the 4DVAR methodology for use within complex ocean environments, and serves as preparation for deploying an operational, real-time assimilation system onboard the Royal Caribbean Cruise Lines ship Explorer of the Seas. Assimilating satellite sea surface height and temperature observations with in situ data from the ship in 14 day cycles over 2 years from January 2005 through March 2007, reduces the observation-model misfit by over 75%. Using measures of the Loop Current dynamics, we show that the assimilated solution is consistent with observed statistics. 相似文献
Conventional hydrogeological practice is to formulate a conceptual model, which is often the basis of a numerical model. The numerical model is then used to test groundwater management strategies. A workflow is proposed, employing the numerically enhanced conceptual model (NECoM) of the Mean Sea Level Aquifer (MSLA) on the island of Malta. The Malta MSLA is overexploited and under threat of salinization. Data (heads, chloride concentrations, electrical conductivity logs, tidal tests and qualitative analyses) were assimilated into a fast-running numerical model. Simultaneously, strategies for optimal acquisition of further data were examined through the modelling process. The model was delivered through the Energy and Water Agency, with suggestions for flexible model deployment. These workflows will, hopefully, spawn model improvements through further revision of the base concepts. The model allows the agency to make predictions, which have uncertainties that are quantified and reduced through data assimilation as new data become available. Contemplated management plans can therefore be properly assessed before implementation. The proposed NECoM approach can be generalized since it bases model usage on the premise that modelling should make maximum use of existing data by assimilating its information content, thereby highlighting the uncertainties of decision-critical predictions that remain because of data insufficiency. Thus, the presently disjointed process of modelling on the one hand, and data acquisition on the other, can be better aligned. Conceptual and numerical model development become parallel, rather than sequential, activities. Together, they enable predictions of future system behaviour for which bias is reduced and uncertainties quantified.