The effect of recent climatic trends on Urticaceae pollination in two bioclimatically different areas in the Iberian Peninsula: Malaga and Vigo     

Marta Recio  F. Javier Rodríguez-Rajo  M. Victoria Jato  M. Mar Trigo  Baltasar Cabezudo 《Climatic change》2009,97(1-2):215-228

Malaga (Mediterranean coast) and Vigo (Atlantic coast) are representative of two bioclimatically different areas belonging to the Mediterranean and the Eurosiberian region, respectively. This contribution represents a study on recent trends in the principal meteorological parameters in these areas and their influence on the phenology of Urticaceae (nettle family) atmospheric pollen, one of the main causes of pollinosis in Spain. The study covers the period 1991–2006 for Malaga and 1995–2005 for Vigo, and compares the differences in climate and phenological behaviour observed at both localities. The sampling of atmospheric pollen was performed with Hirst volumetric pollen traps. The two localities present different tendencies as far as temperature is concerned: while the mean annual temperature in the Mediterranean region has increased by 0.06°C/year, the same parameter has decreased in the Atlantic area by 0.1°C/year. This tendency is even more pronounced as far as the minimum temperatures are concerned, especially during spring in Malaga and autumn in Vigo. On the other hand, wind speed has tended to increase, periods of calm have diminished and winds blowing off the sea have increased in both places. These changes in meteorological parameters have advanced the end of the pollen season in Malaga and delayed its start in Vigo. Total annual pollen counts have decreased in Vigo, while the number of pollen-free days has increased in both areas.  相似文献   

Ultraviolet-B radiation effects on natural phytoplankton assemblages of central San Francisco Bay     

Victoria E. Hogue  Frances P. Wilkerson  Richard C. Dugdale 《Estuaries and Coasts》2005,28(2):190-203

Since the discovery of a depletion of the stratospheric ozone layer over Antarctica in 1979, scientific attention has been directed towards the effects of increased doses of ultraviolet radiation on phytoplankton in other ecosystems. Little is known about the effects of ultraviolet-B (280–320 nm) radiation (UVBR) on temperate estuarine phytoplankton. Freshly collected phytoplankton samples from Central San Francisco Bay were exposed to ambient UVBR in quartz bottles and monitored for biomass and nutrient uptake rates for comparison with phytoplankton dispensed into bottles made of polycarbonate that effectively filtered out the UVBR to evaluate response to natural UVBR exposure. Short-term (10–12 h) exposure experiments were carried out monthly from October 1998 to October 1999. No significant effect of UVBR on chlorophylla concentrations was found but a clear deleterious effect of UVBR on nutrient uptake was observed.  相似文献   

A Discussion of “Women in the Field”: The Politics of Feminist Fieldwork     

Lynn A. Staeheli  Victoria A. Lawson 《The Professional geographer》1994,46(1):96-102

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Silicic recharge of multiple rhyolite magmas by basaltic intrusion during the 22.6 ka Okareka Eruption Episode, New Zealand   总被引：1，自引：0，他引：1  

Phil Shane  Ian A. Nairn  Victoria C. Smith  Miles Darragh  Kate Beggs  Jim W. Cole 《Lithos》2008,103(3-4):527-549

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.  相似文献   

The impact of heat waves on surface urban heat island and local economy in Cluj-Napoca city,Romania     

Ioana?Herbel  Adina-Eliza?CroitoruEmail author  Adina?Viorica?Rus  Cristina?Florina?Ro?ca  Gabriela?Victoria?Harpa  Antoniu-Flavius?Ciupertea  Ionu??Rus 《Theoretical and Applied Climatology》2018,133(3-4):681-695

The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day at city scale, cumulating more than 38 mil. EUR for the three cases considered.  相似文献   

Using suitability analysis to prioritize demolitions in a legacy city     

Victoria C. Morckel 《Urban geography》2017,38(1):90-111

Abandoned properties are a significant problem facing legacy cities. Given historic and ongoing population losses, many legacy cities turn to demolitions as one solution to their surplus property problems. Unfortunately, cities lack the resources needed to demolish all of the buildings that should arguably come down. Determining which properties should receive highest priority is a difficult task. Therefore, this paper presents an empirical method, based on basic suitability analysis, for prioritizing demolitions city-wide. Using Youngstown, Ohio as an example, every vacant property in the city was assigned a demolition score based on four factors: property characteristics, vacancy, neighborhood potential, and crime. Properties with higher scores were deemed stronger candidates for timely demolition. In addition to prioritizing demolitions, the proposed method can facilitate the creation of hotspot maps of proposed demolitions, and a per se strategic demolition plan.  相似文献   

Vulnerability and adaptive capacity of Inuit women to climate change: a case study from Iqaluit,Nunavut     

Anna Bunce  James Ford  Sherilee Harper  Victoria Edge  IHACC Research Team 《Natural Hazards》2016,83(3):1419-1441

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Air transport cruise altitude restrictions to minimize contrail formation     

Victoria WilliamsRobert B Noland  Ralf Toumi 《Climate Policy》2003,3(3):207-219

While quantification of the effects of NO_x and water vapor is still at an early stage there is evidence that contrail formation could make a significant contribution to global warming. This paper builds on previous research that analyzed a policy of restricting air transport cruise altitudes to eliminate contrail formation. Our previous work [Transport. Res. D 7(6) (2002) 451], examined altitude restrictions in European airspace and concluded that this could be a beneficial policy for reducing climate change impacts from aviation. Since most of the flights in European airspace are short-haul flights, this paper evaluates the trade-offs between altitude restrictions, fuel burn and journey times for longer haul flights of up to 6000 nm. Our focus is on the North Atlantic and US airspace and we examine potential contrail fraction to determine optimal cruise altitudes for reducing contrail formation. Changes in fuel burn and travel times associated with flight levels of 18,000 and 31,000 ft for different aircraft types are analyzed. We find that, in most cases, CO₂ emission increases would be unlikely to entirely counteract the benefit of possible reductions in contrail formation. For some aircraft types, the percentage increase in emitted CO₂ was found to be strongly dependent on journey length. In general, journey times appear not to be a major issue except for some aircraft types. Our results suggest that reducing aircraft cruise altitudes could be a beneficial policy for mitigating climate change impacts from the aviation sector. This is clearly dependent on aircraft type and the distances traveled, but more importantly on ambient atmospheric conditions which can vary significantly between regions and due to daily variation. This suggests that real time flight planning to minimize contrail formation should be investigated as a possible climate mitigation policy.  相似文献   

Extending the generality of ecological models to artificial floating habitats     

Cole VJ  Glasby TM  Holloway MG 《Marine environmental research》2005,60(2):195-210

Marine assemblages on natural hard substrata are generally different from those on artificial habitats. There is, however, the potential for certain ecological processes to operate on both types of structures. On the sides of floating pontoons in Sydney Harbour, there were strong patterns of vertical distribution of sessile epibiotic organisms and molluscan grazers across relatively small spatial scales (in three defined zones, namely splash, shallow and deep). Patterns of vertical distribution of the tubeworms Hydroides spp. were reversed depending on the cover of mussels. A manipulative experiment was done to test if patterns of vertical distribution of Hydroides spp. were due to (1) the functioning of mussels or (2) the structure provided by mussels. Neither the functioning nor structure of mussels accounted for the patterns of distribution of Hydroides spp. Mussels increased recruitment of Hydroides spp., in the shallow and deep zones, and this was not due to increased surface area of the mussel shells. Manipulation of numbers of grazers and covers of sessile epibiota showed that the observed negative relationship between grazers and epibiota was due to grazers reducing recruitment of epibiota and epibiota decreasing survival of grazers. Most importantly, processes that accounted for patterns of distribution of mobile and sessile organisms on artificial floating structures were similar to those repeatedly shown to create such patterns on natural rocky shores.  相似文献   

Temporal analysis of groundwater nitrate concentrations from wells in Prince Edward Island,Canada: application of a linear mixed effects model   总被引：1，自引：0，他引：1  

Victoria S. Benson  John A. VanLeeuwen  Henrik Stryhn  George H. Somers 《Hydrogeology Journal》2007,15(5):1009-1019

Changes in nitrate concentration in groundwater from wells in Prince Edward Island, Canada were investigated over time using two datasets. Temporal trends in groundwater nitrate concentrations were assessed annually during 1981–1996 (1,299 observations), and both seasonally and monthly during 1988–1991 (1,868 observations). Data were analysed using linear mixed models with random effects and correlation structures. The average nitrate concentration in the monthly dataset was 3.99 mg/L as NO₃–N, with January, May, and November concentrations being higher (p?=?0.018). A seasonal effect was present when season was combined with land use type in an interaction term (p?=?0.004). Wells located in agricultural areas had greater nitrate concentrations than urban areas, which in turn, had greater values than low human-impact areas. Row-cropped areas had higher groundwater nitrate concentrations in the summer, whereas manure storage areas were higher in the spring and autumn. Nitrate in groundwater in areas with low human impact and with centralized sewage disposal infrastructure remained relatively low and stable throughout the seasons. There was no significant annual trend (p?=?0.954), but for individual sites, 9.6% significantly increased in nitrate concentration over time, and 6.6% significantly decreased over time.  相似文献