A teaching approach to time-geography: Some results of an educational experiment     

María Ángeles Díaz-Muñoz  María Jesús Salado-García  Concepción Díaz-Castillo 《GeoJournal》1999,48(3):159-166

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Comparison of Treatment Efficiency and Energy Consumption of Batch and Continuous Electrocoagulation in Urban Wastewater     

Alper Erdem Yılmaz  Yeşim Dede Sağsöz  Baybars Ali Fil  Murat Tolga Yılmaz 《洁净——土壤、空气、水》2023,51(1):2200032

In this study, domestic wastewater was used as the electrolyte. The work was carried out with an up-flow tubular reactor, made of stainless steel that was used as cathode, while the anode electrode material was aluminum and varying values of flow regime (25, 50, 75 and 100 mL/s for continuous system), initial pH value (5, 6, 7 and 7.8) and current intensity (10, 15 and 20 A) were applied. For domestic wastewater with natural pH, the effluent pH was >9 in the batch system, while in the continuous system the pH was 8–8.5. Likewise, while the effluent temperature was up to 60°C in the batch system, it was at most 35°C in the continuous system. However, the energy consumption values in the continuous system were considerably lower compared with the batch system. At a current intensity of 10 A, 80 kWh of energy per unit volume was consumed in the batch system, while it was 50 kWh for the continuous system. The present results show that the batch system can be used for small wastewater streams whereas the continuous system can be used for large wastewater streams for domestic wastewater treatment.  相似文献   

Pollen sequence from the Chilean Lake District during the Llanquihue glaciation in marine Oxygen Isotope Stages 4–2     

Calvin J. Heusser  Thomas V. Lowell  Linda E. Heusser  Andrs Moreira M.  Simn Moreira M. 《第四纪科学杂志》2000,15(2):115-125

Pollen stratigraphy of a core taken from a fen at Fundo Nueva Braunau (40°17.49′S, 73°04.83′W), situated 2 km beyond the western border of Llanquihue‐age glacial drift, spans an age range from an estimated 60 000–70 000 BP to about 14 000 ¹⁴C yr BP (marine Oxygen Isotope Stages 4–2). The location at present is in the contact zone of Valdivian Evergreen Forest and Lowland Deciduous Beech Forest. Early and late in the pollen record, as indicated by assemblages of southern beech (Nothofagus dombeyi type) and grass (Gramineae), the site was located in Subantarctic Parkland. Intervening assemblages represent expansion of Valdivian–North Patagonian Evergreen Forest (> 49 355 to about 40 000 ¹⁴C yr BP) and North Patagonian Evergreen Forest–Subantarctic Parkland (approximately 40 000 to 30 000 ¹⁴C yr BP). Climate over the time span was under the storm regime of the Southern Westerlies and apparently uninterruptedly wet. When Subantarctic Parkland expanded, cold conditions with summer temperatures estimated at 8–9°C (7°C lower than present) resulted in episodes of glacier maxima. Climate moderated during the period of forest expansion, at which time glaciers were in a state of recession. Contrasting with the continuously wet climate of the Lake District for the period of record, climate in semi‐arid–arid, subtropical Chile underwent extended intervals of precipitation. Data from both the terrestrial and marine realm implicate the Southern Westerlies as the cause of intensified storm activity at lower latitudes. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Modelling facies belt distribution in fan deltas coupling sequence stratigraphy and geostatistics: The Eocene Sant Llorenç del Munt example (Ebro foreland basin,NE Spain)     

P. Cabello  O. Falivene  M. López-Blanco  J. Howell  P. Arbués  E. Ramos 《Marine and Petroleum Geology》2010

The Eocene Sant Llorenç del Munt fan-delta complex developed in the Ebro foreland basin. The stratigraphy of this succession, about 1000 m thick, has been described as made up of several transgressive–regressive composite sequences, each composed of a stack of fundamental sequences, in turn made up of a transgressive systems tract and an overlying regressive systems tract. Systems tracts are composed of several facies belts: proximal alluvial fan, distal alluvial fan, fan-delta front, carbonate platform, and fan-delta slope and prodelta.  相似文献   

A new typology of benefits derived from marine protected areas     

Jorge A. Angulo-Valdés  Bruce G. Hatcher 《Marine Policy》2010

Global decline of marine resources has triggered a worldwide demand for changing the way ocean resources are managed. Ecosystem-based management approaches have emerged using marine protected areas (MPA) as the main tool. Several classifications of marine protected areas benefits have been made, but all have focused only on the benefits to humans, neglecting many important benefits accrued to nature. This paper presents a new comprehensive classification of MPA benefits that will provide scientists and managers with an inclusive framework to accurately identify and account for all possible benefits derived from MPAs. The paper also analyses the methods available for valuing these benefits. A total of 99 benefits were identified within nine main categories: fishery, non-fishery, management, education/research, cultural, process, ecosystem, population and species benefits. These categories are arranged in two main divisions (direct and indirect benefits), which, at the same time, fall within the realms of benefits to humans and to nature.  相似文献   

Litterfall dynamics and nutrient decomposition of arid mangroves in the Gulf of California: Their role sustaining ecosystem heterotrophy     

R. Sánchez-Andrés  S. Sánchez-Carrillo  L.C. Alatorre  S. Cirujano  M. Álvarez-Cobelas 《Estuarine, Coastal and Shelf Science》2010

This study shows results on litterfall dynamics and decay in mangrove stands of Avicennia germinans distributed along a latitudinal gradient (three forest sites) in the Gulf of California, in order to assess whether internal sources could support the observed mangrove ecosystem organic deficit in this arid tropic. Total mean annual litterfall production increased southward (712.6 ± 53.3, 1501.3 ± 145.1 and 1506.2 ± 280.5 g DW m⁻² y⁻¹, in the Yaqui, Mayo and Fuerte areas respectively), leaves being the main component of litter in all locations during the entire year, followed by fruits. The wet season (June–September) showed the highest litterfall rates through fruits. The temporal trend of litterfall production was significantly explained through mean air temperature (R² = 68%) whilst total annual litter production in the entire region showed a statistically significant relationship with total soil phosphorus, salinity, total nitrogen, organic matter and tree height (R² = 0.67). Throughout 117 days of the decomposition experiment, the litter lost 50% of its original dry weight in 5.8 days (average decay rate of 0.032 ± 0.04 g DW d⁻¹) and there were not significant differences in the remaining mass after 6 days. The percentage of both C and P released from the litter correlated significantly with the ratio of tidal inundated days to total experiment days (R² = 0.62, p = 0.03 and R² = 0.67, p = 0.02, respectively); however, the frequency of tidal inundation only showed a significant increase in C release from Avicennia litter after 6 and above 48 days of decomposition. Whereas the total C content of litter bags decreased linearly over the decomposition to (% Total C = 5.52 − 0.46 days, R² = 0.81, p = 0.0005), N content displayed an irregular pattern with a significant increase of decay between 48 and 76 days from the beginning of the experiment. The pattern for relative P content of litter revealed reductions of up to 99% of the original (%tot-P = −9.77 to 1.004 days, R² = 0.72, p = 0.01) although most of the P reduction occurred between 17 and 34 days after the experiment started. Soil N and P contents, which exhibited significant differences in the course of the decomposition experiment, appeared to show significant differences between sampling sites, although they were not related to tidal influence, nor by leaf and nutrient leaching. In a global basis, C/N litter ratios decreased linearly (C/N = 32.86 − 0.1006 days, R² = 0.62, p = 0.02), showing a strong and significant correlation with meteorological variables (R² = 0.99, p = 0.01). C/P ratios of litter increased through an exponential function (C/P = 119.35e^0.04day, R² = 0.89, p < 0.001). Changes in the remaining percentage of litter mass during the experiment were significantly correlated with soil C/N ratio (R² = 0.56, p = 0.03) as well as with the soil C/P ratio (R² = 0.98, p < 0.001). Our results of litter decomposition dynamics in this mangrove support the fact of null net primary productivity of the arid mangrove wetlands: fast litter decomposition compensates the ecosystem organic deficit in order to sustain the mangrove productivity. Litter decomposition plays a key role in the ecosystem metabolism in mangroves of arid tropics.  相似文献   

The 2010 tsunami in Chile: Devastation and survival of coastal small-scale fishing communities     

Andrés Marín  Stefan Gelcich  Gonzalo Araya  Gonzalo Olea  Miguel Espíndola  Juan C. Castilla 《Marine Policy》2010

In 2010, a tsunami generated by a magnitude 8.8 earthquake struck the central-south zone of Chile. This short communication reports the direct impacts on the small-scale artisanal fishing capacity and coastal livelihoods along approximately 600 km of the coastline. Despite the magnitude of the catastrophe, the absence of official warnings, and the failure of telecommunication networks only 8 fisher victims were reported out of a total death toll of more than 170. Results show that this trend is explained by socio-cultural assets and a natural hazard subculture. This highlights the need to integrate contextual and behavioural approaches in disaster management and rehabilitation policies.  相似文献   

HAND contour: a new proxy predictor of inundation extent          下载免费PDF全文

Antonio Donato Nobre  Luz Adriana Cuartas  Marcos Rodrigo Momo  Dirceu Luís Severo  Adilson Pinheiro  Carlos Afonso Nobre 《水文研究》2016,30(2):320-333

Tools for accurately predicting environmental risks, such as the location and spatial extent of potential inundation, are not widely available. A dependence on calibration and a lack of available flood data have prevented the widespread application of existing hydrodynamic methods for predicting the extent of inundation. We use the height above the nearest drainage (HAND) terrain model to develop a simple static approach for mapping the potential extent of inundation that does not depend on flood observations and extends beyond methods for mapping low‐lying areas. While relying on the contour concept, the method utilizes drainage‐normalized topography and flowpaths to delineate the relative vertical distances (drop) to the nearest river. The HAND‐delineated relative drop is an effective distributed predictor of flood potential, which is directly related to the river stage height. We validated the new HAND contour approach using a flood event in Southern Brazil for which high‐resolution maps were available. The results indicated that the flood hazard‐mapping method accurately predicted the inundation extent of the channel carrying the flood wave and the channels influenced by flooding. For channels positioned outside of the flood‐wave area, the method overestimated the actual flood extent. As an original static assessment of floodwaters across the landscape, the HAND contour method could be used to map flood hazards in areas with poor information and could promote the development of new methods for predicting hydrological hazards. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

How much water do Chilean forests use? A review of interception losses in forest plot studies          下载免费PDF全文

Sylvia Soto‐Schönherr  Andrés Iroumé 《水文研究》2016,30(25):4674-4686

After several years of decreased annual rainfall and water shortages, the Chilean society is demanding that forest plantations take accountability of their role in consuming scarce water resources. Evidence has shown that interception losses are considerable when determining water production in watersheds. The aim of this study was to determine if site and stand variables explain interception losses by Chilean forests for the development of an empirical model that could predict the potential impacts of forest management practices and land‐use change. A total of 127 data from annual water balance plot studies in Chile were compiled to derive relationships between interception and precipitation, species composition, plantation age and other stand and site variables. The reviewed data indicated that annual interception losses are mainly explained by annual rainfall and basal area of the forest stands, with a clear difference between the northern (dryer) and southern (wetter) regions of Chile. For a wide latitudinal gradient, forest composition and age, annual interception accounted for approximately 21% of incoming precipitations. Broadleaved forest stands (including native broadleaved and eucalypt forests) generally presented higher interception losses than conifers. Interception was higher in northern zones, indicating that forests have greater impacts on water resources in dryer regions. Our results were compiled in empirical models, which can be used to estimate forest interception in a latitudinal gradient in Chile and to support policy making. These results are also proposed as an approximate analogue of the changes in forest interception losses, which may occur as vegetation belts shift latitudinally as a result of the impact of climate change. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Rotation axes of asteroids: Results for 14 objects     

V. Zappalà  Z. Knežević 《Icarus》1984,59(3):436-455

In this paper results of determinations of the rotation axis direction (as given by ecliptic coordinates of its intersection with geocentric celestial sphere) for 14 asteroids are presented for which a sufficient number of good observations are available. The calculation is performed by using the improved amplitude-magnitude method developed by V. Zappalà, M. Di Martino, P. Farinella, and P. Paolicchi (1983, In Asteroids, Comets, Meteors, pp. 73–76). Additionally, an improvement of the method is described regarding a weighting procedure. Whenever possible, the results are compared with already existing data, coming from other methods (mainly from photometric astrometry). In general, very good agreement was found, which can be considered as strongly encouraging for further application of the adopted procedure. Some preliminary approaches for a statistical investigation are given.  相似文献