Stream bed temperature profiles as indicators of percolation characteristics beneath arroyos in the Middle Rio Grande Basin,USA

Stream bed temperature profiles were monitored continuously during water year 1990 and 1991 (WY90 and 91) in two New Mexico arroyos, similar in their meteorological features and dissimilar in their hydrological features. Stream bed temperature profiles between depths of 30 and 300 cm were examined to determine whether temporal changes in temperature profiles represent accurate indicators of the timing, depth and duration of percolation in each stream bed. These results were compared with stream flow, air temperature, and precipitation records for WY90 and 91, to evaluate the effect of changing surface conditions on temperature profiles. Temperature profiles indicate a persistently high thermal gradient with depth beneath Grantline Arroyo, except during a semi-annual thermal reversal in spring and autumn. This typifies the thermal response of dry sediments with low thermal conductivities. High thermal gradients were disrupted only during infrequent stream flows, followed by rapid re-establishment of high gradients. The stream bed temperature at 300 cm was unresponsive to individual precipitation or stream flow during WY90 and 91. This thermal pattern provides strong evidence that most seepage into Grantline Arroyo failed to percolate at a sufficient rate to reach 300 cm before being returned to the atmosphere. A distinctly different thermal pattern was recorded beneath Tijeras Arroyo. Low thermal gradients between 30 and 300 cm and large diurnal variations in temperature, suggest that stream flow created continuous, advection-dominated heat transport for over 300 days, annually. Beneath Tijeras Arroyo, low thermal gradients were interrupted only briefly during periodic, dry summer conditions. Comparisons of stream flow records for WY90 and 91 with stream bed temperature profiles indicate that independent analysis of thermal patterns provides accurate estimates of the timing, depth and duration of percolation beneath both arroyos. Stream flow loss estimates indicate that seepage rates were 15 times greater for Tijeras Arroyo than for Grantline Arroyo, which supports qualitative conclusions derived from analysis of stream bed temperature responses to surface conditions. © 1997 John Wiley & Sons, Ltd.     

How resilient is the labour market against natural disaster? Evaluating the effects from the 2010 earthquake in Chile

Natural disasters are one of the main channels through which ecological and socio-economic systems interact. In particular, the severe impacts of earthquakes could disrupt activities in the labour market. However, the literature barely researched the long-term effects of such events. To investigate this issue, this article is concentrated in Chile that is subject to recurring seismic movements. The 27 February 2010 Bío-Bío Chile earthquake (M_w 8.8) was the second strongest in the history of the country. This natural disaster can be used to evaluate the response of the labour market to an exogenous shock. Besides, the capacity for resilience in the labour market is crucial for people who rely on their job. This document analyses the impacts of the 2010 Bío-Bío earthquake and tsunami on Chilean labour market outcomes, in particular, the quality of employment. With this objective, different data are combined for analysing the effect in the short and long term. Also, distinct econometric techniques and exogenous measurements of seismic acceleration are used. The evidence shows that these catastrophes harmed the labour market in the short term. However, in the long term, the government’s reconstruction efforts and other factors could have attenuated the adverse effects over some variables in the most affected zones.

     

Suspended sediment yield and transfer processes in a small High-Arctic glacier basin,Svalbard

Observations of suspended sediment concentration and discharge at two sites on the proglacial river network draining from a predominantly cold-based, High-Arctic glacier (Austre Brøggerbreen) are described. Analysis of these observations illustrates: (i) the relatively low suspended sediment yield from this basin in comparison with many other glacier basins reported in the open literature; (ii) sustained and possibly increasing availability of suspended sediment to the fluvial system as the ablation season progresses; and (iii) the role of the proglacial sandur as both a sediment source and sink. Field observations coupled with the results of the data analysis are used to make inferences concerning the changing nature and relative importance of sediment sources within the basin. © 1998 John Wiley & Sons, Ltd.     

Silicic recharge of multiple rhyolite magmas by basaltic intrusion during the 22.6 ka Okareka Eruption Episode, New Zealand

Deposits of the 22.6 ka Okareka Eruption Episode from Tarawera Volcanic Complex record the sequential and simultaneous eruption of three discrete rhyolite magmas following a silicic recharge event related to basaltic intrusion. The episode started with basaltic eruption ( 0.01 km³ magma), and rapidly changed to a plinian eruption involving a moderate temperature (750 °C), cummingtonite-bearing rhyolite magma (T1) with a volume of  0.3 km³. Hybrid basalt/rhyolite clasts demonstrate direct basaltic intrusion that helped trigger the eruption. Crystals, shards and lapilli of two other rhyolite magmas then joined the eruption sequence. They comprise a cooler (720 °C) crystal-rich biotite–hornblende rhyolite magma (T2) ( 0.3 km³), and a hotter (780 °C), crystal-poor, pyroxene–hornblende rhyolite magma (T3) ( 4.5 km³). All mid to late-stage ash units contain various mixtures of T1, T2 and T3 components with a general increase in abundance of T3 and rapid decline of T1 with time. About 4 km³ of T3 magma was extruded as lavas at the end of the episode. Contrasts in melt composition, crystal and volatile contents, and temperatures influenced viscosity and miscibility, and thus limited pre-eruption mixing of the rhyolite magmas. The eruption sequence and the restricted direct basaltic intrusion into only one magma (T1) is consistent with the rhyolites occupying separate melt pods within a large crystal-mush zone. Melt–crystal equilibria and volatile contents in melt inclusions indicate temporary magma storage depths of < 8 km. Each of the magmas display quartz crystals containing melt inclusions that are compositionally highly evolved relative to the accompanying matrix glass, and thus point to a stage of more complete crystallisation. The matrix glass, enriched in Sr and Ti, represents a re-melting event of underlying the crystal pile induced by basaltic intrusion, presumably part of the same event that erupted scoria at the start of the eruption. This recharge rhyolite melt percolated upward and hybridised with the resident melts in each of the three magma pods. The Okareka episode rhyolites contrast with other well-documented rhyolites that are either continuously or discontinuously zoned, or have been homogenised during re-activation to a uniform composition. Rapid basalt dike intrusion to shallow levels appears to have (prematurely?) triggered the Okareka rhyolites into eruption, so that their early ponding in separate melt pods has been recorded before it could be masked by mixing or stratification had amalgamation into a larger body occurred.     

Resource use and resource efficiency in the Asia–Pacific region

Over the last few decades, the Asia–Pacific region has experienced the most dynamic economic development of any of the world's regions, leading to a rapid increase in resource use and associated emissions. The region is now a major driver towards overshooting global resource use limits. In this paper, we provide an estimate of material use and resource efficiency in the Asia–Pacific region and its sub-regions for the first time, to complement existing knowledge on global resource use. We show that the Asia–Pacific has become the single largest user of resources globally, and that the efficiency of resource use in the region decreased over the period 1970–2005. Furthermore we show that the region's share of total resource use is now so significant that decreasing resource efficiency there has driven a decrease in overall global resource efficiency, for the first time in a century. Using an IPAT framework we found that rising per capita incomes contributed more strongly to growing material use than did population growth. Technology did not moderate material use growth to the extent expected. We argue that a failure to make these issues a central and immediate focus of public policy in the Asia–Pacific region would compromise competitiveness, resource security, and poverty reduction in the region over the medium to long term.     

Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001

Martian meteorites can provide valuable information about past environmental conditions on Mars. Allan Hills 84001 formed more than 4 Gyr ago, and owing to its age and long exposure to the Martian environment, and this meteorite has features that may record early processes. These features include a highly fractured texture, gases trapped during one or more impact events or during formation of the rock, and spherical Fe‐Mg‐Ca carbonates. In this study, we have concentrated on providing new insights into the context of these carbonates using a range of techniques to explore whether they record multiple precipitation and shock events. The petrographic features and compositional properties of these carbonates indicate that at least two pulses of Mg‐ and Fe‐rich solutions saturated the rock. Those two generations of carbonates can be distinguished by a very sharp change in compositions, from being rich in Mg and poor in Fe and Mn, to being poor in Mg and rich in Fe and Mn. Between these two generations of carbonate is evidence for fracturing and local corrosion.     

An assessment of the non-market value of the ecosystem services provided by the Catalan coastal zone,Spain

A spatial value transfer analysis was performed to generate baseline estimates of the value of ecosystem services in the coastal zone of Catalonia, Spain. The study used the best available conceptual frameworks, data sources, and analytical techniques to generate non-market monetary value estimates that can be used to identify scarce ecosystem services among competing coastal uses. The approach focused on natural and seminatural, terrestrial and marine systems, which provide essential services that are not considered in current economic markets. Results show that in 2004 a substantial economic value of $3,195 million USD/yr was delivered to local citizens by surrounding ecosystems. In a spatially explicit manner, the approach illustrates the contribution made by natural environmental systems to the well being of communities in the coastal zone of Catalonia. It is hoped that this study will highlight the need to consider these coastal systems in future management strategies to ensure their proper maintenance and conservation.