A mitochondrial DNA PCR-RFLP marker for population studies of the black scabbardfish (Aphanopus carbo)     

Quinta  Ricardo; Gomes  Laurentina; Teia dos Santos  Ana 《ICES Journal of Marine Science》2004,61(5):864-867

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Multi-level assessment of chronic toxicity of estuarine sediments with the amphipod Gammarus locusta: I. Biochemical endpoints     

Neuparth T  Correia AD  Costa FO  Lima G  Costa MH 《Marine environmental research》2005,60(1):69-91

We report on biomarker responses conducted as part of a multi-level assessment of the chronic toxicity of estuarine sediments to the amphipod Gammarus locusta. A companion article accounts for organism and population-level effects. Five moderately contaminated sediments from two Portuguese estuaries, Sado and Tagus, were assessed. Three of them were muddy and two were sandy sediments. The objective was to assess sediments that were not acutely toxic. Three of the sediments met this criterion, the other two were diluted (50% and 75%) with clean sediment until acute toxicity was absent. Following 28-d exposures, the amphipods were analysed for whole-body metal bioaccumulation, metallothionein induction (MT), DNA strand breakage (SB) and lipid peroxidation (LP). Two of the muddy sediments did not cause chronic toxicity. These findings were consistent with responses at organism and population levels that showed higher growth rates and improvement of reproductive traits for amphipods exposed to these two sediments. Two other sediments, one muddy and one sandy, exhibited pronounced chronic toxicity, affecting SB, MT induction (in muddy sediment), survival and reproduction. Potential toxicants involved in these effects were identified. The last sandy sediment exhibited some loss of DNA integrity, however growth was also enhanced. Present results, together with the organism/population-level data, and also benthic communities information, were analysed under a weight-of-evidence approach. By providing evidence of exposure (or lack of it) to contaminants in sediments, the biomarkers here applied assisted in distinguishing toxicants' impacts in test organisms from the confounding influence of other geochemical features of the sediments.  相似文献   

Isotopic evidence for the origin of an acid sulphate alteration,Styrian basin,Austria     

Ana‐Voica Bojar  Stanislaw Halas  Hans‐Peter Bojar  Janina Szaran 《地学学报》2008,20(1):45-51

The Gossendorf volcanic body is the only one in the Styrian basin that shows extensive hydrothermal alteration. K‐Ar dating of primary volcanic biotite and alteration products (alunite) suggests that the emplacement of the volcanic body and hydrothermal alteration took place synchronously, 15 Ma ago. The stable isotope compositions of the alteration products such as opal, barite, pyrite and alunite combined with crystallographia investigations indicate temperatures between 150 and 200 °C for the formation of the alteration zones. The calculated stable isotopic compositions of the parent fluid, responsible for the alteration, show an exogene marine component, which interacted with the host rock. Sulphur isotopic compositions of sulphur, sulphides and sulphates indicate disequilibrium, and progressive oxidation. This fact, combined with the mineral zonation of the alteration zone, reflects not only change in the pH but also change in the fO₂ of the ascending fluids.  相似文献   

Quantifying the impact of no-till on runoff in southern Brazil at hillslope and catchment scales     

Ana L. Londero  Jean P. G. Minella  Fabio J. A. Schneider  Dinis Deuschle  Danrlei Menezes  Olivier Evrard  Madalena Boeni  Gustavo H. Merten 《水文研究》2021,35(3):e14094

No-till (NT) is a conservation system that improves the hydrological regime of agricultural slopes by providing greater surface protection and benefits to the physical and hydrological properties of soils. However, the isolated use of NT is not enough to control runoff and its associated degradation processes. Therefore, this study aimed to evaluate the runoff of agricultural slopes under NT under different runoff control conditions by monitoring 63 rainfall events in two 2.4-ha zero-order catchments and 27 rainfall events in four 0.6-ha macroplots. The catchments are paired and similar in terms of the type of soil and relief, but different regarding the presence of terraces. The macroplots have different soil and crop management systems. By using monitoring techniques, the hyetographs and hydrographs revealed the influence of the different types of management on the catchments and macroplots and allowed rainfall characteristics, runoff volume, runoff coefficients, water infiltration, peak runoff, response times, and curve number to be analysed. The terraces positively affected the NT and controlled runoff and related variables, in addition to infiltration significantly increasing and runoff reducing in the terraced catchment. All the hydrological information assessed pointed to the positive effects provided by the presence of the terraces. The results in the macroplots showed that high amounts of phytomass and/or chiselling do not control runoff and its correlated variables in medium and high magnitude events. The study concludes by underlining the need for additional measures to control runoff (terraces), even in areas under NT and with high phytomass production. Additionally, the study emphasizes the importance of monitoring at the catchment scale to better understand the hydrological behaviour of agricultural areas and provide the necessary parameters to effectively control runoff.  相似文献   

Unravelling evapotranspiration controls and components in tropical Andean tussock grasslands     

Ana E. Ochoa-Sánchez  Patricio Crespo  Galo Carrillo-Rojas  Franklin Marín  Rolando Célleri 《水文研究》2020,34(9):2117-2127

The study of the environmental factors that control evapotranspiration and the components of evapotranspiration leads to a better understanding of the actual evapotranspiration (ET) process that links the functioning of the soil, water and atmosphere. It also improves local, regional and global ET modelling. Globally, few studies so far focussed on the controls and components of ET in alpine grasslands, especially in mountainous sites such as the tussock grasslands located in the páramo biome (above 3300 m a.s.l.). The páramo occupies 35 000 km² and provides water resources for many cities in the Andes. In this article, we unveiled the controls on ET and provided the first insights on the contribution of transpiration to ET. We found that the wet páramo is an energy-limited region and net radiation (Rn) is primarily controlling ET. ET was on average 1.7 mm/day. The monthly average evaporative fraction (ET/Rn) was 0.47 and it remained similar for wet and dry periods. The secondary controls on ET were wind speed, aerodynamic resistance and surface resistance that appeared more important for dry periods, where significantly higher ET rates were found (20% increase). During dry events, transpiration was on average 1.5 mm/day (range 0.7–2.7 mm/day), similar to other tussock grasslands in New Zealand (range 0.6–3.3 mm/day). Evidence showed interception contributes more to ET than transpiration. This study sets a precedent towards a better understanding of the evapotranspiration process and will ultimately lead to a better land-atmosphere fluxes modelling in the tropics.  相似文献   

Observed and simulated inter-decadal changes in the structure of Southern Hemisphere large-scale circulation     

Ana C. V. Freitas  Jorgen S. Frederiksen  Jennifer Whelan  Terence J. O’Kane  Tércio Ambrizzi 《Climate Dynamics》2015,45(11-12):2993-3017

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Estimation of flood risk thresholds in Mediterranean areas using rainfall indicators: case study of Valencian Region (Spain)     

Ana M. Camarasa-Belmonte  D. Butrón 《Natural Hazards》2015,78(2):1243-1266

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The Risk Atlas of Mexico City,Mexico: a tool for decision-making and disaster prevention     

Novelo-Casanova  David A.  Suárez  Gerardo  Cabral-Cano  Enrique  Fernández-Torres  Enrique A.  Fuentes-Mariles  Oscar A.  Havazli  Emre  Jaimes  Miguel Á.  López-Espinoza  Erika D.  Martin-Del Pozzo  Ana Lillian  Morales-Barrera  Wendy V.  Morales-Rodríguez  Hipólito L.  Nieto-Torres  Amiel  Rodríguez-Elizarrarás  Sergio R.  Solano-Rojas  Darío  Velasco-Herrera  Victor M. 《Natural Hazards》2022,111(1):411-437

Natural Hazards - We present a Risk Atlas of Mexico City based on a Geographical Information System (RA-GIS). We identified the prevalent social risk to the more relevant hazards in Mexico City...  相似文献   

Carbonate tufas as archives of climate and sedimentary dynamic in volcanic settings,examples from Gran Canaria (Spain)     

lvaro Rodríguez-Berriguete  Jon Camuera  Ana Maria Alonso-Zarza 《Sedimentology》2022,69(1):199-218

Three Holocene tufas from Gran Canaria volcanic island were studied with the aim of deciphering their sedimentary evolution through space and time. Las Temisas tufa (south-eastern arid part of the island) is dominantly composed of oncoids, intraclasts, phytoclasts, coated stems, minor thin stromatolites, and a high amount of siliciclastics. It was deposited in a fluvial system with variable flow velocities and palustrine conditions areas, which alternated with high energy events. Azuaje tufa (northern humid part of the island) is composed of coated stems, stromatolites, oncoids and phytoclasts, with relatively low amounts of siliciclastics, suggesting slow-flowing and palustrine conditions and a relatively low incidence of (high energy) floodings. Los Berrazales tufa (north-west of Gran Ganaria, the most humid one), is mainly composed of coated stems and crystalline crusts, formed in a laminar flow regime. Dominant clastic sedimentation in Las Temisas and high calcite growth rates in Los Berrazales led to a poor development of stromatolites in comparison with Azuaje. Las Temisas and Azuaje deposits have similar upward evolution with decreasing trend in siliciclastics and increasing trend in carbonates. However, Las Temisas has higher siliciclastic and lower phytoclastic contents suggesting a less vegetated area and more arid climate than in the other deposits. Additionally, tufas record local events common in volcanic terrains. Azuaje presents three units bounded by erosive discontinuities, which reveal significant erosion by enhanced runoff that could be caused by loss of vegetation due to wildfires related to volcanic eruptions at headwaters. Las Temisas record a possible interruption in sedimentation represented by aligned boulders due to rockfalls from the hillsides. These deposits formed from waters with similar chemistry providing to the carbonates their similar signals in δ¹³C–δ¹⁸O stable isotopes and ⁸⁷Sr/⁸⁶Sr ratios like that of the volcanic rocks. This work shows how, in volcanic areas, tufas are unique archives of the climate, vegetation and volcanic-related processes, because all imprint the sedimentary regime of tufa deposition.  相似文献   

Tidal variation in a rocky inter‐tidal fish population: the case of white seabream Diplodus sargus juveniles          下载免费PDF全文

Ana Ribeiro Gonçalves  Liliana de Sousa  Pedro Duarte‐Coelho  Vitor Carvalho Almada 《Marine Ecology》2015,36(4):1468-1471

The rocky inter‐tidal habitat is a harsh and fluctuating environment, subject to frequent disturbances. Field observations of juvenile white seabream Diplodus sargus in inter‐tidal rocky habitats were conducted to analyse the spatial distribution and feeding activity of this species in relation to the tidal cycle. The depth at which fish were observed did not change in most tidal phases while feeding activity changed with tidal level, showing the occurrence of tidal migrations and that feeding may be limited by habitat availability in shallow waters and thus be dependent on tidal changes. The present results show the exploitation of available feeding areas in the rocky inter‐tidal by juvenile white seabream, which corroborates the importance of these habitats for the first developmental stages of this fish species.  相似文献