Methodology for applying the Limits of Acceptable Change process to the management of recreational boating in the Balearic Islands, Spain (Western Mediterranean)     

Amy Diedrich  Pablo Balaguer Huguet  Joaquín Tintoré Subirana 《Ocean & Coastal Management》2011,54(4):341-351

The objective of this study is to propose a simple methodological approach, based on the Limits of Acceptable Change process, to support the formulation of management measures for recreational boating in bays. Management measures have been determined using statistical and geospatial analyses of data of biophysical characteristics, use, and user perceptions in a bay on the island of Mallorca. The results suggest that the optimal use level of the study site is being surpassed and a range of potential management options is provided. This methodology is applicable to additional management scenarios where balancing social and environmental needs is necessary and should be implemented as part of a broader Integrated Coastal Zone Management framework.  相似文献   

Small-scale distribution characteristics of Munida spp. populations (Decapoda: Anomura) off the Catalan coasts (western Mediterranean)     

Carme Huguet  Francesc Maynou  Pere Abell 《Journal of Sea Research》2005,53(4):283

The small-scale distribution characteristics of three species of the anomuran genus Munida, namely Munida rutllanti, Munida intermedia and Munida tenuimana, have been studied on the lower shelf and upper-middle continental slope near the coasts of Tarragona and the Ebro delta region in the western Mediterranean. The differential bathymetric distribution showed that a fair degree of overlap exists between M. rutllanti and M. intermedia, with the former being mainly found at shallower depths. The size population structure of the three species showed that polymodality, as indicative of a longer life-span and of a higher degree of population structuring was more evident in the deeper-living species, whereas unimodality, as an indication of a recruitment dependent population, was more evident in the shallowest-occurring species. Geostatistics have been applied to determine the degree of spatial variability occurring in M. intermedia abundance, the better-sampled species. The Mantel test has been used to assess the significance of the overlap between the three species distributions as well as the relation between certain population parameters. A discussion on the population characteristics of M. rutllanti is made in relation with its expansion along the western Mediterranean in the last decades.  相似文献   

One million years of cultural evolution in a stable environment at Atapuerca (Burgos,Spain)     

J. Rodríguez  F. Burjachs  G. Cuenca-Bescós  N. García  J. Van der Made  A. Pérez González  H.-A. Blain  I. Expósito  J.M. López-García  M. García Antón  E. Allué  I. Cáceres  R. Huguet  M. Mosquera  A. Ollé  J. Rosell  J.M. Parés  X.P. Rodríguez  C. Díez  J. Rofes  E. Carbonell 《Quaternary Science Reviews》2011,30(11-12):1396-1412

The present paper analyses the evidence provided by three sites (Sima del Elefante, Gran Dolina, and Galería) located in the Trinchera del Ferrocarril of the Sierra de Atapuerca. These three sites are cave infillings that contain sediments deposited from approximately 1.2 Ma to 200 kyr. Pollen, herpetofauna, and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the Sierra de Atapuerca throughout the one million-year period represented at these sites. Similarly, cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites. At least three periods with different cultural features, involving technology, subsistence and behavior, are determined from the available evidence. The first two periods correspond to the Mode 1 technology and Homo antecessor: the first is dated around 1.2 to 1.0 Ma and reflects opportunistic behavior both in technology and subsistence. The second period is around 800 kyr BP. Mode 1 technology is still maintained, but subsistence strategies include systematic hunting and the use of base camps. The third period is dated between 500 ka and 200 ka and corresponds to the Mode 2 technology and the acquisition of directional hunting and other organizational strategies by Homo heidelbergensis. A transition from Mode 2 to Mode 3 seems to appear at the end of this time-range, and may reflect the early phases of a fourth cultural change. With regard to the environment, our main conclusion is that there was an absence of extremely harsh conditions at Atapuerca throughout this time period. The presence of Mediterranean taxa was constant and the dominant landscape was a savannah-like open environment, probably with small forest patches. An alternation of Mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles, and steppes spread across the landscape during the drier periods. In any case, it is not possible to establish clear cut-off points separating entirely different environmental episodes. Our results show no evidence of any relationship between environmental change and cultural change at the Sierra de Atapuerca.  相似文献   

Properties of fluorescent dissolved organic matter in the Gironde Estuary   总被引：5，自引：0，他引：5  

A. Huguet  L. Vacher  S. Relexans  S. Saubusse  J.M. Froidefond  E. Parlanti 《Organic Geochemistry》2009,40(6):706-719

The isolation, characterization and study of the properties of aquatic dissolved organic matter (DOM) still represent a challenge because of the heterogeneity, complexity and low concentration of organic material in natural waters. Based on its ability to interact with contaminants and thus to modify their transport and bioavailability, DOM is of interest for environmental purposes. The objective of this work was to better characterize DOM in the Gironde Estuary (southwestern France). The estuary represents an exchange zone between the continent and the Atlantic Ocean and conditions the transfer of organic and inorganic substances from the continental to the oceanic environment. Several samples were collected along the estuary during three cruises in 2002 and 2006. They were analysed using excitation–emission matrix (EEM) spectroscopy, a sensitive technique that allows direct analysis of water samples. Fluorescent DOM and dissolved organic carbon (DOC) did not behave conservatively in this estuarine system, i.e. the organic material did not undergo simple dilution from the upstream to the downstream part of the estuary. A seasonal variability in DOC content was pointed out, whereas few seasonal variations in DOM fluorescence were observed. DOM sources and processing in the estuary were further evaluated by determining two fluorescence indices – the humification index (HIX) and the index of recent autochthonous contribution (BIX). By applying these indices, the relative degree of humification (HIX) and autotrophic productivity (BIX) could be assessed. Based on the fluorescence and DOC results, the estuary was divided into three zones depending on salinity (S) and characterized by specific DOM: (i) A turbid zone of low salinity (S < 5) and high suspended particulate matter concentration with increase in the intensities of the α′ and α fluorophores, characteristic of humic-like compounds. (ii) A mid-estuarine zone (5 < S < 25) characterized by low autotrophic productivity and containing strongly degraded organic material, as shown by the low values of BIX and high values of HIX. (iii) A higher salinity area (S > 25) characterized by increased autotrophic productivity and a marked marine influence, and associated with high and low values of BIX and HIX, respectively. The HIX and BIX indices were shown as useful tools for readily defining and classifying DOM characteristics in estuarine waters.  相似文献   

Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert,northwestern China     

Sun  Qingfeng  Zamanian  Kazem  Huguet  Arnaud  Bayat  Omid  Wang  Hong  Badawy  Hanan S. 《中国地球化学学报》2022,41(5):811-822

Acta Geochimica - Desert rhizoliths are generally found as weathered, broken and scattered samples on dune field surface, but rarely in-situ in their initial states buried under the soil of desert...  相似文献   

Selective preservation of soil organic matter in oxidized marine sediments (Madeira Abyssal Plain)   总被引：1，自引：0，他引：1  

Carme Huguet  Gert J. de Lange  Jack J. Middelburg  Jaap S. Sinninghe Damsté  Stefan Schouten 《Geochimica et cosmochimica acta》2008,72(24):6061-6068

In ocean margin sediments both marine and terrestrial organic matter (OM) are buried but the factors governing their relative preservation and degradation are not well understood. In this study, we analysed the degree of preservation of marine isoprenoidal and soil-derived branched glycerol dialkyl glycerol tetraethers (GDGTs) upon long-term oxygen exposure in OM-rich turbidites from the Madeira Abyssal Plain by analyzing GDGT concentrations across oxidation fronts. Relative to the anoxic part of the turbidites ca. 7-20% of the soil-derived branched GDGTs were preserved in the oxidized part while only 0.2-3% of the marine isoprenoid GDGT crenarchaeol was preserved. Due to these different preservation factors the Branched Isoprenoid Tetraether (BIT) index, a ratio between crenarchaeol and the major branched GDGTs that is used as a tracer for soil-derived organic matter, substantially increases from 0.02 to 0.4. Split Flow Thin Cell (SPLITT) separation of turbidite sediments showed that the enhanced preservation of soil-derived carbon was a general phenomenon across the fine particle size ranges (<38 μm). Calculations reveal that, despite their relatively similar chemical structures, degradation rates of crenarchaeol are 2-fold higher than those of soil-derived branched GDGTs, suggesting preferential soil OM preservation possibly due to matrix protection.  相似文献   

Basics of Gas-Dynamics and Radiative Transfer     

E. Huguet 《Astrophysics and Space Science》1998,260(1-2):3-13

This article is intended to review some basics of gas-dynamics (Sect. 1) and radiative transfer (Sect. 2) which are the necessary background to introduce out-of-equilibrium high energy flows. The two first sections deal with general aspects, the more specific problem of out-of-equilibrium flows is tackled in Sect. 3 through the example of radiative shock waves. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Bound states in monopoles: sources for UHECR?     

Eric Huguet  Patrick Peter   《Astroparticle Physics》2000,12(4):277-289

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Effects of long term oxic degradation on the U37K′, TEX86 and BIT organic proxies     

Carme Huguet  Jung-Hyun Kim  Gert J. de Lange  Jaap S. Sinninghe Damsté  Stefan Schouten 《Organic Geochemistry》2009,40(12):1188-1194

One of the primary prerequisites for the application of organic proxies is that they should not be substantially affected by diagenesis. However, studies have shown that oxic degradation of biomarker lipids can affect their relative distribution. We tested the diagenetic stability of the $U_{37}^{K^{\prime }}$ and TEX₈₆ palaeothermometers upon long term oxygen exposure. For this purpose, we studied the distributions of alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) in different sections of turbidites at the Madeira Abyssal Plain (MAP) that experienced different degrees of oxygen exposure. Sediments were deposited anoxically on the shelf and then transported by turbidity currents to the MAP, which has oxic bottom water. This resulted in partial degradation of the turbidite organic matter as a result of long term exposure to oxic bottom water. Concentrations of GDGTs and alkenones were reduced by one to two orders of magnitude in the oxidized parts of the turbidites compared to the unoxidized parts, indicating substantial degradation. High-resolution analysis of the Pleistocene F-turbidite showed that the $U_{37}^{K^{\prime }}$ index of long chain alkenones increased only slightly (0.01, corresponding to <0.5 °C) in the oxidized part of the turbidite, suggesting minor preferential degradation of the C_37:3 alkenone, in agreement with previous studies. TEX₈₆ values showed a small increase (0.02, corresponding to ～2 °C) in the F-turbidite, like $U_{37}^{K^{\prime }}$, while for other Pliocene/Miocene turbidites it either remained unchanged or decreased substantially (up to 0.06, corresponding to ～6 °C). Previous observations showed that the BIT index, a proxy for the contribution of soil organic matter to total organic carbon, was always substantially higher in the oxidized part in all the turbidites, as a result of preferential degradation of marine-derived GDGTs. This relative increase in soil-derived GDGTs affects TEX₈₆, as the isoprenoid GDGT distribution on the continent can be quite different from that in the marine environment. Our results indicate that the organic proxies are affected by long term oxic degradation to different extents; this should be taken into account when applying these proxies in palaeoceanographic studies of sediments which have been exposed to prolonged oxic degradation.  相似文献   

Biomarker seasonality study in Lake Van, Turkey     

C. Huguet  S. FietzM. Stockhecke  M. SturmF.S. Anselmetti  A. Rosell-Melé 《Organic Geochemistry》2011,42(11):1289-1298

The endorheic Lake Van in eastern Anatolia (Turkey) is the world’s largest soda lake and it is an important site in paleoclimate studies to understand past continental conditions in western Asia. In order to gain further insights into the biomarker signatures in Lake Van’s sediments we have analyzed particulate material in sediment traps deployed between August 2006 and July 2007. The biomarkers used were long chain alkenones (LCAs C₃₇-C₃₉, haptophyte lipids), isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs, Archaea membrane lipids) and pigments (chlorins and fucoxanthin). The biomarker fluxes indicate a strong seasonality in export primary productivity and the phytoplankton community structure. The highest total mass and organic carbon fluxes were found in summer, coupled to strong stratification while the lowest mass fluxes occurred in winter at the time of water column mixing. With increasing temperatures in early spring, phytoplankton export productivity grew, coupled with an increase of total mass flux and organic carbon, which might be associated to enhanced nutrient input from snowmelt runoff. The percentage of C_37:4 shows some correspondence with observed seasonal changes in Lake Van’s stratification structure. We also evaluated the potential applicability of molecular temperature proxies derived from Archaea and haptophyte lipids. The use of the TEX₈₆ proxy was precluded by low GDGT abundances. Estimated LCA temperatures were consistent with temperatures in the photic zone but no seasonality changes were observed despite the wide annual temperature range measured at Lake Van.  相似文献