Holocene paleoclimate inferred from stable isotope (δ18O and δ13C) values in Sphagnum cellulose,Mohos peat bog,Romania     

Túri  Marianna  Hubay  Katalin  Molnár  Mihály  Braun  Mihály  László  Elemér  Futó  István  Palcsu  László 《Journal of Paleolimnology》2021,66(3):229-248

Journal of Paleolimnology - We measured stable isotopes (δ18O and δ13C) in Sphagnum cellulose that was extracted from a long peat core drilled in the ombrotrophic Mohos peat bog, Ciomadul...  相似文献   

Seasonal patterns of pollen sedimentation in Lake Montcortès (Central Pyrenees) and potential applications to high-resolution paleoecology: a 2-year pilot study     

V. Rull  M. C. Trapote  E. Safont  N. Cañellas-Boltà  N. Pérez-Zanón  J. Sigró  T. Buchaca  T. Vegas-Vilarrúbia 《Journal of Paleolimnology》2017,57(1):95-108

Lakes with varved sediments are especially well suited for paleoecological study, from annual to even seasonal resolution. The interpretative power of such high-resolution paleoenvironmental reconstructions relies on the availability of modern analogs with the same temporal resolution. We studied seasonal pollen sedimentation in varved Lake Montcortès, Central Pyrenees (Spain), as a modern analog for high-resolution reconstruction of Late Holocene vegetation and landscape dynamics. Seasonal samples were obtained from sediment traps that were submerged near the maximum water depth for a 2-year period (fall 2013 to fall 2015). Seasonal pollen sedimentation was compared with meteorological variables from a nearby weather station. Bulk pollen sedimentation, dominated by Pinus (pine) and Quercus (oak), followed a clear seasonal pattern that peaked during the spring/summer, coinciding with maximum temperature and precipitation, minimum relative humidity and moderate winds from the SSE. Pollen sedimentation lags (PSL) were observed for most pollen types, as substantial amounts of pollen were found in the traps outside of their respective flowering seasons. Two pollen assemblages were clearly differentiated by their taxonomic composition, corresponding to spring/summer and fall/winter. This pattern is consistent with existing interpretation of the sediment varves, specifically, that varves are formed by two-layer couplets that represent the same seasonality as pollen. We concluded that pollen sedimentation in Lake Montcortès exhibits a strong seasonal signal in the quantity of pollen, the taxonomic composition of the pollen assembalges, and relationships between the pollen and meteorological variables. Thus, varved sediments provide a potentially powerful tool for paleoecological reconstruction at seasonal resolution. This method could be used not only to identify paleoenvironmental trends, but also to identify annual layers and therefore date sediments, even in the absence of evident sediment laminations. A satisfactory explanation of PSL will require further studies that examine internal lake dynamics and pollen production/dispersal patterns.  相似文献   

Evaluation of an automated EA-IRMS method for total carbon analysis of atmospheric aerosol at HEKAL     

István Major  Brigitta Gyökös  Marianna Túri  István Futó  Ágnes Filep  András Hoffer  Enikő Furu  A. J. Timothy Jull  Mihály Molnár 《Journal of Atmospheric Chemistry》2018,75(1):85-96

Comprehensive atmospheric studies have demonstrated that carbonaceous particles are one of the main components of atmospheric aerosols over Europe. The aim of our study was to establish an automated elemental analyser interfaced to a stable isotope mass spectrometer (EA-IRMS) method at the Hertelendi Laboratory of Environmental Studies (HEKAL), as a suitable method of quantification of total carbon mass in individual PM_2.5 aerosol samples. Total carbon (TC) mass and simultaneous stable isotopic ratios were determined for both test standard and genuine aerosol samples. Finally, the results were compared to the ones obtained independently by an alternative sealed tube combustion method developed previously at HEKAL. The TC recovery tests of standard material prepared by the sealed tube method confirmed at least a carbon recovery yield of 92% for a broad range of carbon mass (100–2000 μg). The stable isotopic results confirmed that sealed tube method is reproducible and suitable to be used as a reference to verify our new EA-IRMS method. The EA-IRMS TC measurements of genuine aerosols gave on average 3% higher carbon recovery yield, relative to the uncorrected results of the sealed tube method. The comparison of the stable isotopic results by the two methods for aerosols also showed minimal differences. Consequently, the possibility of simultaneous TC and stable isotopic analyses makes the EA-IRMS method a very attractive alternative for continuous measurement of aerosols, with an accuracy and reliability similar to other commercial devices.  相似文献   

Evaluation of methods of spatial interpolation for monthly rainfall data over the state of Rio de Janeiro,Brazil     

Gustavo?Bastos?Lyra  Tamíres?Partelli?Correia  José?Francisco?de?Oliveira-Júnior  Marcelo?ZeriEmail authorView author&#;s OrcID profile 《Theoretical and Applied Climatology》2018,134(3-4):955-965

Five deterministic methods of spatial interpolation of monthly rainfall were compared over the state of Rio de Janeiro, southeast Brazil. The methods were the inverse distance weight (IDW), nearest neighbor (NRN), triangulation with linear interpolation (TLI), natural neighbor (NN), and spline tension (SPT). A set of 110 weather stations was used to test the methods. The selection of stations had two criteria: time series longer than 20 years and period of data from 1960 to 2009. The methods were evaluated using cross-validation, linear regression between values observed and interpolated, root mean square error (RMSE), coefficient of determination (r ²), coefficient of variation (CV, %), and the Willmott index of agreement (d). The results from different methods are influenced by the meteorological systems and their seasonality, as well as by the interaction with the topography. The methods presented higher precision (r ²) and accuracy (d, RMSE) during the summer and transition to autumn, in comparison with the winter or spring months. The SPT had the highest precision and accuracy in relation to other methods, in addition to having a good representation of the spatial patterns expected for rainfall over the complex terrain of the state and its high spatial variability.  相似文献   

Environmental factors influencing aggregation of manta rays (Manta birostris) off the northeastern coast of the Yucatan Peninsula          下载免费PDF全文

Ana Hacohen‐Domené  Raúl O. Martínez‐Rincón  Felipe Galván‐Magaña  Natalí Cárdenas‐Palomo  Jorge Herrera‐Silveira 《Marine Ecology》2017,38(3)

Manta rays inhabit tropical, subtropical and temperate waters. Aggregation sites of manta rays have been recognized worldwide, but the reasons for this behavior are still poorly understood. This study describes environmental factors influencing aggregation sites of the giant manta ray (Manta birostris) off the northeastern coast of the Yucatan Peninsula. Observations of manta rays were obtained from scientific surveys conducted during 2006–2011. Environmental data were obtained from satellite imagery. The maximum entropy (Maxent) method for habitat modeling was used to determine the effects of environmental conditions on the species and predict suitable habitat for manta rays in this region. Primary productivity and distance to the coast were the most influential variables, suggesting that aggregation occurs in highly productive coastal waters. The distribution of manta rays predicted by the Maxent model showed that the most suitable habitat within the study area is located off the northeastern coast of the Yucatán Peninsula, more precisely, northeast of Isla Holbox and northwest of Isla Contoy. Seasonal patterns of distribution suggest that the most suitable conditions are present from July through September.  相似文献   

Superposition of tectonic structures leading elongated intramontane basin: the Alhabia basin (Internal Zones,Betic Cordillera)     

Martínez-Martos  Manuel  Galindo-Zaldivar  Jesús  Martínez-Moreno  Francisco José  Calvo-Rayo  Raquel  Sanz de Galdeano  Carlos 《International Journal of Earth Sciences》2017,106(7):2461-2471

International Journal of Earth Sciences - The relief of the Betic Cordillera was formed since the late Serravallian inducing the development of intramontane basins. The Alhabia basin, situated in...  相似文献   

Soil contamination by metals with high ecological risk in urban and rural areas     

F. B. V. da Silva  C. W. A. do Nascimento  P. R. M. Araújo  F. L. da Silva  L. H. V. Lima 《International Journal of Environmental Science and Technology》2017,14(3):553-562

Industrial development, intensive agriculture and fast urbanization have caused the metal contents of soils to increase to many times the allowable limits. To assess this impact on urban and rural soils, we quantified the Cd, Cr, Cu, Pb, Ni and Zn contents of 258 soil samples from the Recife metropolitan region (RMR). The objectives of the study were to estimate the probability of ecological risk, to determine the spatial pattern of the metals’ accumulation in the soil and to identify potential sources for the metals using a multivariate geostatistical approach. Mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in soils were 65.2, 17.9, 16.5, 12.8, 6.3 and 1.5 mg kg^?1, respectively. The results demonstrated that the Cd was anthropogenic in origin, the Cr and Ni were lithogenic (natural) in origin and the Cu, Pb and Zn were mixed in origin. Cd contaminated 91% of the samples; the median content of Cd (1.4 mg kg^?1) was three times the quality reference value for soil. The Cd contents of sugarcane fields exceeded the allowable limit (3.0 mg kg^?1) for agricultural areas. The spatial variability of the metals in the RMR showed that metallurgy, cement production, vehicle exhaust and vehicular traffic were the main sources of metals in urban areas, while phosphate-based fertilizers were the main sources in rural areas. More than 80% of the metropolitan region surveyed in the study was at moderate to high ecological risk.  相似文献   

Seismic Characteristics of the Vulcanian Explosions from the 2003–2005 Eruption at Colima Volcano,Mexico     

Francisco Javier Núñez-Cornú  Juan Manuel Espíndola  Fidencio Alejandro Nava Pichardo  Carlos Suárez-Plascencia 《Pure and Applied Geophysics》2016,173(10-11):3513-3524

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P-Wave Velocity Tomography from Local Earthquakes in Western Mexico     

Juan A. Ochoa-Chávez  Christian R. Escudero  Francisco J. Núñez-Cornú  William L. Bandy 《Pure and Applied Geophysics》2016,173(10-11):3487-3511

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Seismic Anisotropy and Mantle Flow Driven by the Cocos Slab Under Southern Mexico     

Leslie A. Bernal-López  Berenice R. Garibaldi  Gerardo León Soto  Raúl W. Valenzuela  Christian R. Escudero 《Pure and Applied Geophysics》2016,173(10-11):3373-3393

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