An experimental,analytical and numerical study on the thermal efficiency of energy piles in unsaturated soils

Energy piles are bi-functional foundation elements used as structural support as well as ground heat exchangers for shallow geothermal energy systems. Because they are relatively short, energy piles may be partially embedded in unsaturated soils. Saturation conditions influence the thermal properties of the ground and therefore the heat exchange rate, which in turn affects the efficiency of energy piles. This paper combines analytical, experimental and numerical investigations to evaluate the heat exchange rate of energy piles partially or fully embedded in unsaturated soils. The proposed analytical solution is based on the cylindrical heat source theory that treats the soil as a semi-infinite, homogeneous, and isotropic medium. The solution from this theory is multiplied by a function developed analytically in this paper and the outcome is the heat exchange rate for energy piles in unsaturated soils. The proposed function depends on soil saturation, soil and pile thermal properties, and pile geometry. The analytical solution was compared against a finite element solution; which was in turn validated against results from laboratory experiments. Very satisfactory agreements between the analytical, numerical and experimental outputs were observed. The proposed method can be used for a quick and simple evaluation of the efficiency of energy piles in unsaturated conditions. The proposed analytical solution can also be a useful tool for the verification of numerical codes developed for the design of energy piles in unsaturated soils.     

Magnetostratigraphy of Upper Cretaceous strata in Grand Staircase-Escalante National Monument,southern Utah: The Santonian–Campanian Stage boundary,reassessment of the C33N/C33R magnetochron boundary,and implications for regional sedimentation patterns within the Sevier Foreland Basin

Samples were collected for magnetostratigraphic analysis from the Upper Cretaceous Straight Cliffs and Wahweap formations within Grand Staircase-Escalante National Monument, southern Utah, in an attempt to locate the C34n–C33r and C33r–C33n boundaries; the former approximates the Santonian–Campanian Stage boundary. Locating both of these horizons within the Monument provides for refined temporal resolution of the many new fossil localities discovered in these units, while also adding to our understanding of the overall Straight Cliffs–Wahweap sequence stratigraphic architecture. Results indicate that the John Henry and Drip Tank members of the Straight Cliffs Formation are of normal polarity, and represent the later part of C34n, the Cretaceous Normal Polarity Super-Chron. The C34n–C33r boundary apparently resides in a significant hiatus determined to occur between the Drip Tank Member of the Straight Cliffs Formation and the lower part of the overlying Wahweap Formation. In stratigraphically ascending order, the informally named lower, middle, and most of the upper members of the Wahweap Formation are of reversed polarity. The C33r–C33n polarity change occurs in the upper part of the upper member, and C33n continues stratigraphically upward through the capping sand member of the Wahweap Formation and into the overlying Kaiparowits Formation. The presence of over 200 m of reversely magnetized strata above a level in the lower part of the middle member dated to 79.9 ± 0.3 Ma, which coincides with the GTS2012 date for the C33r–C33n boundary of 79.9 Ma, suggests that the published age of that boundary may be in error. A new date of approximately 78.91 Ma is proposed, in turn allowing for the thick sequence of reversely magnetized strata above the 79.9 Ma level. Age revision of the Kaiparowits Basin's Late Cretaceous record demonstrates that during late Santonian through early middle Campanian time, except in central Utah, a close correlation in time and facies successions with other successions throughout the Western Interior Basin suggests a eustatic influence on the depositional patterns. Starting in the late middle Campanian, the Kaiparowits record, along with those both to the north and south, appear to diverge in style and facies successions. We consider this to have resulted from a fundamental change in depositional controls triggered by the Laramide Orogeny. The anomalous central Utah record appears to have been profoundly influenced by a massive salient (Nebo-Charleston thrust system) in the Sevier Fold and Thrust belt that was active for much of the Late Cretaceous.     

Regional metamorphism and the alteration response of selected Silurian to Devonian mineral systems in the Nymagee area,Central Lachlan Orogen,New South Wales: a HyLogger™ case study

The southern Cobar Superbasin includes the Mount Hope, Cobar and Rast troughs and adjacent Winduck, Mouramba and Kopyje shelves. These stratotectonic units host a range of mineral systems within deformed upper Silurian to Lower Devonian rocks. Despite the metallogenic importance of the terrane the regional metamorphic- and alteration-related mineral assemblages have not been systematically described until now. Here, we present a study using the HyLogger? spectral scanner to systematically map changes in both background and alteration-related mineralogy for 14 mineral systems across the Nymagee area. The study found that, with the exception of the late diagenetic zone assemblages associated with the Winduck Shelf, the mineral assemblages for zones away from mineralisation are consistent with uniform sub- to lowest-greenschist facies metamorphic conditions, with no evidence for a regional, thermal field gradient across the basin. By contrast, proximal to mineralisation, there are significant changes in alteration-related mineral abundances and species reflecting elevated fluid temperatures. For several zones, including Browns Reef, Great Central, Hera, May Day, Nymagee and Shuttleton, there is a systematic change in chlorite composition from Fe- and/or Fe–Mg-chlorites to more Mg-rich varieties towards mineralisation. In addition, talc was noted for May Day, Mineral Hill and Shuttleton. The change in chlorite composition suggests that these ore-forming fluids were undersaturated with respect to iron. Furthermore, although present in discrete zones, carbonate alteration is not a dominant alteration type. However, at Manuka and Blue Mountain, the mineralisation is associated with carbonate-rich (calcite, ankerite, dolomite) units that have been dolomitised (Mg alteration) but not all dolomite-rich zones are mineralised. For Mineral Hill, there are systematic changes to mineral species/chemistry with observed data consistent with Parkers Hill being proximal to the centre of a mineralising system. The G and H Lode area (Southern Ore Zone) is slightly more distal whereas the Pearse deposit may represent a zone more distal again.     

Rock–water interactions and pollution processes in the volcanic aquifer system of Guadalajara,Mexico, using inverse geochemical modeling

In order to understand and mitigate the deterioration of water quality in the aquifer system underlying Guadalajara metropolitan area, an investigation was performed developing geochemical evolution models for assessment of groundwater chemical processes. The models helped not only to conceptualize the groundwater geochemistry, but also to evaluate the relative influence of anthropogenic inputs and natural sources of salinity to the groundwater. Mixing processes, ion exchange, water–rock–water interactions and nitrate pollution and denitrification were identified and confirmed using mass-balance models constraint by information on hydrogeology, groundwater chemistry, lithology and stability of geochemical phases. The water–rock interactions in the volcanic setting produced a dominant NaHCO₃ water type, followed by NaMgCaHCO₃ and NaCaHCO₃. For geochemical evolution modeling, flow sections were selected representing recharge and non-recharge processes and a variety of mixing conditions. Recharge processes are dominated by dissolution of soil CO₂ gas, calcite, gypsum, albite and biotite, and Ca/Na exchange. Non-recharge processes show that the production of carbonic acid and Ca/Na exchange are decreasing, while other minerals such as halite and amorphous SiO₂ are precipitated. The origin of nitrate pollution in groundwater are fertilizers in rural plots and wastewater and waste disposal in the urban area. This investigation may help water authorities to adequately address and manage groundwater contamination.     

The Yudomian of Siberia,Vendian and Ediacaran systems of the International stratigraphic scale

In Russia, the terminal Neoproterozoic formally includes the Vendian of western part of the East European platform and the concurrent Yudoma Group of Siberia. As is shown in this work, the designated subdivisions correspond in the stratotypes only to the upper, Yudomian Series of the Vendian. In the Siberian platform, the Ust-Yudoma and Aim horizons of the Yudomian are tightly interrelated. The lower of them, bearing remains of Ediacaran Fauna, represents the Ediacarian Stage, whereas the upper one containing small-shelled fossils (SSF) corresponds to the Nemakit-Daldynian Stage divided into the trisulcatus and antiqua superregional zones. In more complete sections of the platform periphery, sediments of these subdivisions conformably rest on siliciclastic succession that should be ranked as basal subdivision of the Yudomian. The succession is concurrent to the Laplandian Stage of the East European platform. According to geochronological dates obtained recently, the Yudomian Series spans interval of 600–540 Ma. In the East European platform, the Upper Vendian (Yudomian) begins with the Laplandian basal tillites of synonymous stage. In the west of the platform, tillites are dated at 600 Ma like the Upper Vendian base in Siberia. The next Ediacarian Stage of the East European platform is stratigraphic equivalent of the Redkino Horizon, while summary range of the Kotlin and Rovno horizons is concurrent to that of the Nemakit-Daldynian Stage. The Vendian of Russia is conformably overlain by the Tommotian Stage of the Lower Cambrian. Intense pre-Vendian events constrained distribution areas of the Lower Vendian sediments in Russia. The Lower Vendian deposits of the East European platform are most representative and well studied in the central Urals, where they are attributed to the Serebryanka Group. In Siberia, separate subdivisions representing the Lower Vendian are the Maastakh Formation of the Olenek Uplift, two lower members of the Ushakovka Formation in the Baikal region, and the Taseeva Group of the Yenisei Range. Chronological interval of the Lower Vendian corresponds to 650–600 Ma. The Marinoan Glaciation dated in Australia at 650–635 Ma is concurrent to basal part of the pre-Yudomian interval of the Vendian in Russia, whereas the Laplandian Tillite and Gaskiers Glaciation (600–580 Ma) correspond to onset of the Yudomian Epoch. The new Ediacaran System (Knoll et al., 2004) legalized in the International Neoproterozoic scale is close in range to the entire Vendian (635–544 Ma), although without basal beds (Marinoan Tillite) it deprives the terminal Neoproterozoic of its original sense. Inferiority of the system consists also in its indivisibility into stages. Hence, it is clear that the Vendian System subdivided in detail in Russia should be retained in the rank of terminal system of the Precambrian, one of the basic in general scale of the Neoproterozoic.     

Chinese Trade in Latin America Compared to the European Union and the United States: The Case of Technology-Intensive Exports

Using trade data submitted by United Nations member states from 1995 to 2013, this article contributes to understanding China's trade with Latin America. By employing and building on the TECH score methodology, this project highlights China's growing economic connectivity with nine large and important Latin American economies. The analysis conducted here shows that compared with exports originating from other, more traditional foreign investors (i.e., the United States and the European Union member states), Chinese exports to these Latin American countries—although growing in sophistication over time—are relatively less technologically sophisticated during the study period. This work clarifies that in spite of these Latin American economies being highly complementary (for their natural resources and consumer markets) to China's manufacturing-intensive economy and despite the rapid growth in bilateral and biregional trade, China's displacement of traditional foreign actors, in terms of its technology-intensive exports to the region, is not supported by the data to date.     

Human–Wildlife Conflicts and their Associated Livelihood Impacts in and Around Chebera-Churchura National Park,Ethiopia

Human–wildlife conflict is one of the major challenges in conservation biology. Here, we investigated the human–wildlife conflicts and their impacts in and around Chebera-Churchura National Park, Ethiopia. We conducted semistructured interview for 300 people and five focus group discussions from November 2010 to January 2011. In addition, scats of 60 spotted hyenas were collected and analyzed. Totally, 12 carnivores, 6 herbivores, and 2 primate species posing a significant problem were identified. Intensive human–wildlife conflict was observed in Churchura, Sere, and Chebera villages which were very close to the park. The carnivore’s attacks during 2007–2011 had caused about 30.49% of livestock losses. The overall economic loss by wildlife attacks was estimated to be US$ 75,234 (US$ 83/household/year). Scat analysis confirmed a substantial contribution (59%) of livestock to spotted hyena’s diet. Thus, combined strategies like improving livestock husbandries and strengthen the capacity of managers are imperative to mitigate the problems.     

The nexus approach to water–energy–food security: an option for adaptation to climate change

Developing countries face a difficult challenge in meeting the growing demands for food, water, and energy, which is further compounded by climate change. Effective adaptation to change requires the efficient use of land, water, energy, and other vital resources, and coordinated efforts to minimize trade-offs and maximize synergies. However, as in many developing countries, the policy process in South Asia generally follows a sectoral approach that does not take into account the interconnections and interdependence among the three sectors. Although the concept of a water–energy–food nexus is gaining currency, and adaptation to climate change has become an urgent need, little effort has been made so far to understand the linkages between the nexus perspective and adaptation to climate change. Using the Hindu Kush Himalayan region as an example, this article seeks to increase understanding of the interlinkages in the water, energy, and food nexus, explains why it is important to consider this nexus in the context of adaptation responses, and argues that focusing on trade-offs and synergies using a nexus approach could facilitate greater climate change adaptation and help ensure food, water, and energy security by enhancing resource use efficiency and encouraging greater policy coherence. It concludes that a nexus-based adaption approach – which integrates a nexus perspective into climate change adaptation plans and an adaptation perspective into development plans – is crucial for effective adaptation. The article provides a conceptual framework for considering the nexus approach in relation to climate change adaptation, discusses the potential synergies, trade-offs, and offers a broader framework for making adaptation responses more effective.

Policy relevance

This article draws attention to the importance of the interlinkages in the water, energy, and food nexus, and the implications for sustainable development and adaptation. The potential synergies and complementarities among the sectors should be used to guide formulation of effective adaptation options. The issues highlight the need for a shift in policy approaches from a sectoral focus, which can result in competing and counterproductive actions, to an integrated approach with policy coherence among the sectors that uses knowledge of the interlinkages to maximize gain, optimize trade-offs, and avoid negative impacts.     

Validation of the ESA CCI soil moisture product in China

The quality of a newly merged soil moisture product (ECV_SM v0.1) from active and passive microwave sensors has attracted widespread international attention. The performance evaluation of this product will benefit studies on climate, meteorology, agriculture, hydrology, ecology and the environment. In this study, meteorological station data and the Noah soil moisture product were used to validate the ECV_SM product in China. First, some conventional statistical measures, such as correlation coefficients, bias, root mean square difference (RMSD) and mean relative error (MRE), were computed to describe the level of agreement between the meteorological station data and ECV_SM values. The accuracy was moderately high (the correlation was significant at the 0.05 level), although the two datasets differed slightly for various types of land cover. Compared with cropland and urban and built-up areas, the performance of ECV_SM was best in grassland regions. Second, the triple collocation technique was used to assess the random error in the meteorological station data, Noah soil moisture product and ECV_SM product. The mean errors in these three datasets were 0.108, 0.079 and 0.075 m³ m⁻³, respectively, on July 8, 2010 and 0.099, 0.061 and 0.059 m³ m⁻³, respectively, on October 8, 2010. Only two days of data were used for the triple collocation test as a representative, but this cannot precisely indicate that the test results on any other day correspond with the test results on these two days. Additionally, a trend analysis of ECV_SM during 2003–2010 was carried out using the Mann–Kendall trend test.     

Great new insights from failed experiments,unanticipated results and embracing controversial observations

Experimental data and observations, whether telescopic or analytical, are never wrong, though data derived from such sources can be misinterpreted or applied inappropriately to derive conclusions that are incorrect. Given that nature always behaves according to the laws of physics and chemistry, rather than according to currently popular models and theories, experimental results should always be considered correct even when the results are far from those that one might initially expect. We discuss a number of cases where the results of experiments, even one carried out as a simple calibration measure, produced wildly different results that generally required many years of effort or contemplation to understand. On the positive side, exploration of the circumstances that produced the “errant” results often led to new and interesting insights concerning processes that might occur in natural environments and that were well worth the effort involved.Specifically, we show how an experiment that “failed” due to a broken conductor led to experiments that made the first refractory oxide solids containing mass independently fractionated oxygen isotopes and to 1998 predictions of the oxygen isotopic composition of the sun that were confirmed by the analysis of Genesis samples in 2011. We describe a calibration experiment that unexpectedly produced single magnetic domain iron particles. We discuss how tracking down a persistent source of “contamination” in experiments intended to produce amorphous iron and magnesium silicate smokes led to a series of studies on the synthesis of carbonaceous grain coatings that turn out to be very efficient Fischer–Tropsch catalysts and have great potential for trapping the planetary noble gases found in meteorites. We describe how models predicting the instability of silicate grains in circumstellar environments spurred new measurements of the vapor pressure of SiO partially based on previous experiments showing unexpected but systematic non-equilibrium behavior instead of the anticipated equilibrium products resembling meteoritic minerals. We trace the process that led from observations of the presence of crystalline minerals detected in the comae of some comets to the 1999 prediction of large-scale circulation of materials from the hot, innermost regions of the solar nebula out to the cold dark nebular environments where comets form. This large-scale circulation was ultimately confirmed by analyses of highly refractory Stardust samples collected from the Kuiper Belt Comet Wild 2. Finally we discuss a modern and still unresolved conflict between the assumptions built into three well known processes: the CO Self Shielding Model for mass independent isotopic fractionation of oxygen in solar system solids, rapid and thorough mixing within the solar nebula, and the efficient conversion of CO into organic coatings and volatiles on the surfaces of nebular grains via Fischer–Tropsch-type processes.