Precipitation data in a mountainous catchment in Honduras: quality assessment and spatiotemporal characteristics   总被引：2，自引：0，他引：2  

I. Westerberg  A. Walther  J-L. Guerrero  Z. Coello  S. Halldin  C-Y. Xu  D. Chen  L-C. Lundin 《Theoretical and Applied Climatology》2010,101(3-4):381-396

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Latitudinal and altitudinal patterns of the endemic cacti from the Atacama desert to Mediterranean Chile     

P.C. Guerrero  A.P. Durán 《Journal of Arid Environments》2011,75(11):991-997

In this study we describe the biogeographic patterns of the endemic cacti from the Atacama Desert to the Mediterranean area of Chile. Our goals were: (1) to identify areas of high endemism, (2) to test Rapoport’s rule, (3) to test the geometric constraints hypothesis, (4) to explore temperature and precipitation as explanatory variables of species richness. We used a list of 72 species of cacti, ranging from 18° to 36° S and from 0 to 4500 m.a.s.l. A Bayesian analysis of Endemicity (BAE) was used to evaluate hierarchical relationships of endemism between different latitudinal bands. Rapoport’s rule was evaluated by examining the relationships between latitudinal/altitudinal mid-point, latitudinal/altitudinal range extent and species richness. The geometric constraints hypothesis was tested by examining the existence of mid-domain effect. The BAE indicated two areas of endemism: (1) the northern area between 18° S and 26° S, and (2) the southern area between 27° S and 36° S. The shape of the latitudinal gradient is non-linear, supporting the geometric constraints hypothesis. Altitudinal patterns, however, support Rapoport’s rule; a peak of endemism was found at low altitudes. The explanatory variables were elevation, minimum temperature of the coldest month, mean temperature of wettest quarter and annual precipitation.  相似文献   

Characterizing Atmospheric Aerosols off the Atlantic Canadian Coast During C-FOG     

Chisholm  Nicole  Nagare  Baban  Wainwright  Charlotte  Creegan  Ed  Salehpoor  Leyla  VandenBoer  Trevor C.  Bullock  Terry  Croft  Betty  Lesins  Glen  Osthoff  Hans  Fernando  H. J. S.  Chang  Rachel Y.-W. 《Boundary-Layer Meteorology》2021,181(2-3):345-364

Boundary-Layer Meteorology - Marine aerosols play an important role in the Earth’s climate, but their effects remain highly uncertain due to a poor understanding of their sources, properties,...  相似文献   

Paleosubsidence and active subsidence due to evaporite dissolution in the Zaragoza area (Huerva River valley, NE Spain): processes, spatial distribution and protection measures for transport routes     

Jesús Guerrero  Francisco Gutirrez  Pedro Lucha 《Engineering Geology》2004,72(3-4):309-329

The lowest 17-km long reach of the Huerva River valley, down to its confluence with the Ebro River in Zaragoza city, flows across salt-bearing evaporites of the Ebro Tertiary Basin (NE Spain). Upstream, the horizontally lying Miocene evaporites are interfingered with non-soluble distal alluvial fan facies (shales and sandstones). The proportion of soluble facies in the Huerva River valley increases in a downstream direction towards the basin depocenter. On the basis of the type and magnitude of the paleosubsidence features, the valley has been divided into four reaches. Along reach I, undeformed terrace deposits less than 4 m thick rest on insoluble detrital bedrock. In reaches II and III, dissolution at the alluvium–bedrock boundary has generated local thickening, deformation and paleocollapse structures, which only affect the alluvial mantle. In reach IV, terrace deposits thicken to over 60 m resulting from a large-scale synsedimentary subsidence. In this sector, subsidence locally affects to both the alluvium and the underlying bedrock. This indicates that dissolution acts at the rockhead beneath the alluvial cover (alluvial karst) and within the evaporitic substratum (interstratal karst). The development of an intraevaporitic karst in reach IV is attributed to gypsum and salt dissolution. Irregular terrace gravel bodies (gravel pockets) embedded in a fine-grained matrix associated with paleocollapse structures have been interpreted as liquefaction–fluidization structures resulting from ground acceleration and suction induced by catastrophic collapses. Subsidence is currently active in the region affecting areas with a thin alluvial cover in reaches III and IV. The low subsidence activity in most of Zaragoza city is explained by the presence of thickened (around 50 m) and indurated alluvial deposits. In the surrounding area, numerous buildings in Cadrete and Santa Fe villages have been severely damaged by subsidence. Natural and human-induced subsidence favours the development of slope movements in the gypsum scarp overlooking Cadrete village. Several transport routes including the Imperial Canal (irrigation canal) and the recently completed Madrid–Barcelona high-speed railway are affected by human-induced sinkholes. The paleocollapse structures exposed in the trenches of this railway and a ring road under construction point to hazardous locations underlain by cavities and collapse structures where special protection measures should be applied. Rigid structures are recommended beneath the high-speed railway with sufficient strength to span the larger sinkholes with no deformation. Electronic monitoring devices linked to a warning system can detect subtle subsidence-induced deformations in carriageways or railways. This research demonstrates that the study of the paleokarst helps to understand the processes involved in the present-day subsidence phenomena and their general spatial distribution.  相似文献   

Transmission Sources of Waterborne Viruses in South Sudan Refugee Camps          下载免费PDF全文

Laura Guerrero‐Latorre  Ayalkibet Hundesa  Rosina Girones 《洁净——土壤、空气、水》2016,44(7):775-780

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Simultaneous Growth of Spirulina platensis and Removal of Hardness in Van Lake Water     

Olcayto Keskinkan  Oya Işık  Turan Yılmaz  Behzat Balcı  Leyla H. Uslu  Çağatayhan B. Ersü 《洁净——土壤、空气、水》2012,40(1):34-38

In this study, batch experiments were carried out to investigate simultaneous growth of Spirulina platensis and removal of hardness in the Van Lake Water (VLW). Laboratory‐scale studies showed ample Spirulina growth observed in VLW when exposed to light. Spirulina was the only algal specimen inoculated in the water during the study. VLW percentages were varied between 0.1 and 100% while pH values were 8.7–10.42 in the flasks. On a dry‐weight basis the biomass concentration was 1.18 g L^?1 at pH 10 after 17 days of incubation in the VLW. The increase of pH to above 10.38 associated with Spirulina growth resulted in the precipitation of hardness causing compounds while providing 70% hardness removal from the VLW medium. Experimental results indicated that the proposed method can be used to design batch systems for producing S. platensis and removal of hardness from the VLW.  相似文献   

Assessment of the distribution of sponge chips in the sediment of East Pacific Ocean reefs          下载免费PDF全文

Jose Luis Carballo  Humberto Ovalle‐Beltrán  Benjamin Yáñez  Eric Bautista‐Guerrero  Héctor Nava‐Bravo 《Marine Ecology》2017,38(1)

Sponges are one of the principal agents of bioerosion and sediment production in coral reefs. They generate small carbonate chips that can be found in the sediments, and we investigated whether these could provide a means for assessment of bioerosion applicable to reef monitoring. We tested this hypothesis on samples from 12 Mexican coral reefs distributed along the Pacific coast, where boring sponges were particularly abundant, and quantified the amount of chips in samples of superficial sediment in three grain‐size fractions: fine (<44 μm), medium (44–210 μm) and coarse (>210 μm). The grain‐size distribution varied among reefs, with the majority of the sediment of most reefs being composed of coarse sands, and the medium and fine fractions dominating only at La Entrega and Playa Blanca. All the reefs presented clear evidence of bioerosion by sponges, with the characteristic chips present in the sediment, although at most sites the percentage of chips was very low (from 1% to 3% of the total sediment). Only at La Entrega and Playa Blanca did they constitute a significant fraction of the total sediment (18% and 16%, respectively). While not statistically significant, there was an interesting trend between sponge chips versus sponge abundance that suggests that quantification of the chips in the sediment could be used as a proxy for sponge erosion of the entire community, which cannot be estimated in by laboratory experiments. However, while this methodology could provide an integrated approach to monitor sponge bioerosion, more studies are necessary due to the influence of environmental factors on the transport and deposition of these chips.  相似文献   

Ecological risk assessment using trace elements from surface sediments of Izmit Bay (Northeastern Marmara Sea) Turkey   总被引：16，自引：0，他引：16  

Pekey H  Karakaş D  Ayberk S  Tolun L  Bakoğlu M 《Marine pollution bulletin》2004,48(9-10):946-953

The aim of this study was to study ecological risk assessment of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in Izmit Bay surface sediments in the <63 microm fraction. Sediment samples were collected from 8 sites along the north coastline of the bay. Samples were subjected to a total digestion technique and analyzed for major (organic carbon) and minor (As, Cd, Cr, Cu, Ni, Pb and Zn) elements. Sediments heavily contaminated are evaluated by the Sediment Quality Guidelines (SQG) of US EPA. The degree of contamination (Cd) is estimated as very high at each site. Two sets of SQGs, effect range-low/effect range median values and TEL/probable effect level (PEL) values were used in our study. Sediments from the each site are judged toxic when two or more of the PEL values exceed EPA guidelines. Our results are in agreement with previously reported sediment toxicity test results.  相似文献   

Contribution of spectral coherency analysis and tracer test to study leakage at the Doosti Dam reservoir,Iran and Turkmenistan     

Morteza Mozafari  Ezzat Raeisi  Jesús Guerrero 《Environmental Earth Sciences》2018,77(4):139

The Doosti Dam was built across the Harirood River on the border between Turkmenistan and Iran. During the reservoir impounding, leakage occurred as new springs through the sandstone layers of the Pesteleigh Aquifer and limy sandstone and limestone layers of the Neyzar–Kalat Aquifer, at the right abutment of the dam. To evaluate the grout curtain operation, a tracer test was carried out by injection of Uranine in a borehole located at the upstream of grout curtain in the Pesteleigh Aquifer. Tracer test results demonstrated a diffuse flow component through the grout curtain in the Pesteleigh Aquifer, but no tracer was detected at the main leakage point, SP1 Spring, emerged downstream of grout curtain from the Neyzar–Kalat Aquifer. Using the spectral coherency function, the lag time between changes in the water level of the injection borehole and water level in the tracer detected boreholes or discharge of the tracer detected springs was determined. Linear regression analyses indicated that the estimated lag time by the time series analysis was close to the first arrival time of the tracer. Therefore, the estimated velocities based on the lag time of time series could be considered close to the calculated velocities based on the first arrival time of the tracer. The estimated groundwater velocities based on the time series analysis ranged from 3.91 to 20.31 m h^?1, showed that diffuse flow dominated pathways from the reservoir toward the downstream boreholes in the Neyzar–Kalat Aquifer, while conduit flow was present within the pathways toward the SP1 Spring. Regarding the reservoir volume, the negligible amount of leakage at the maximum water level of the reservoir confirmed well overall operation of the grout curtain at the dam site.  相似文献   

Hierarchical analysis of the population genetic structure in Concholepas concholepas,a marine mollusk with a long‐lived dispersive larva          下载免费PDF全文

Leyla Cárdenas  Juan Carlos Castilla  Frédérique Viard 《Marine Ecology》2016,37(2):359-369

For most marine invertebrate species, dispersal is achieved mainly or exclusively by pelagic larvae. When the duration of the pelagic larval stage is long, genetic homogeneity over large geographic scales is expected. However, genetic structure has often been reported over small spatial scales, suggesting that more complex processes occur than a simple positive relationship between pelagic larval duration and gene flow. Concholepas concholepas has a larval stage that can last up to 3 months in the water column with a wide distributional range covering from 6°S to 56°S. We used a hierarchical sampling technique to test if the genetic homogeneity of this highly dispersive species is maintained throughout its total geographic range in spite of environmental heterogeneity. In the three studied regions (Antofagasta Bay, Valdivia and Patagonia), a spatial pattern of isolation by distance in conjunction with a spatial genetic structure was observed. Within each region, different spatial genetic patterns were detected. In Antofagasta Bay and Valdivia there was evidence of substantial gene flow among populations, whereas in Patagonia, populations showed genetic structure and a unique, genetically isolated location was identified. These results revealed the existence of spatial differences in the genetic patterns among regions with different coastal topographies in C. concholepas, and give us new insights into the inter‐relationships of larval dispersal potential, actual larval dispersal and physical processes. Regarding the sustainable management of C. concholepas, two important issues are derived from this study: (i) to highlight the need for a regional context in the management of C. concholepas, (ii) to determine the distinctiveness of the most austral population and to focus on the conservation efforts due to the relevance of this area.  相似文献