Is delta-aminolevulinic acid dehydratase activity in bivalves from south-west Iberian Peninsula a good biomarker of lead exposure?     

Kalman J  Riba I  Blasco J  DelValls TA 《Marine environmental research》2008,66(1):38-40

The coast of Huelva is considered as a heavily contaminated area where the Tinto and Odiel rivers discharge after running through a metalliferous mining area in the Iberian Pyrite Belt and end in common estuary called Ría of Huelva. Lead is a highly toxic and widely distributed element in the aquatic environment; therefore there is a great interest in assessing the impact of this contaminant on aquatic organisms. To study the bioavailability and sources of lead, the bivalve species Chamelea gallina was collected from six sampling sites along the coast of Huelva. Besides the effect of this metal on the enzyme activity, delta-aminolevulinic acid dehydratase (ALA-D) was determined in the whole tissue. Results show the inverse relationship between the lead concentration and the activity of ALA-D measured in whole tissues (r2=0.7). Individuals collected from the Ría of Huelva estuary had the highest levels of total lead concentrations and the lowest activity of ALA-D. Lead isotope analyses demonstrated the different sources of lead contamination and also confirmed the influence of Ría of Huelva on the metal input to the marine environment.  相似文献   

The frequency and distribution of recent landslides in three montane tropical regions of Puerto Rico   总被引：12，自引：0，他引：12  

Matthew C. Larsen  Angel J. Torres-Snchez 《Geomorphology》1998,24(4):309-331

Landslides are common in steep mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high. Each year, landslides cause extensive damage to property and occasionally result in loss of life. Average population density is high, 422 people/km², and is increasing. This increase in population density is accompanied by growing stress on the natural environment and physical infrastructure. As a result, human populations are more vulnerable to landslide hazards. The Blanco, Cibuco, and Coamo study areas range in surface area from 276 to 350 km² and represent the climatologic, geographic, and geologic conditions that typify Puerto Rico. Maps of recent landslides developed from 1:20,000-scale aerial photographs, in combination with a computerized geographic information system, were used to evaluate the frequency and distribution of shallow landslides in these areas. Several types of landslides were documented—rainfall-triggered debris flows, shallow soil slips, and slumps were most abundant. Hillslopes in the study area that have been anthropogenically modified, exceed 12° in gradient, are greater than 300 m in elevation, and face the east-northeast, are most prone to landsliding. A set of simplified matrices representing geographic conditions in the three study areas was developed and provides a basis for the estimation of the spatial controls on the frequency of landslides in Puerto Rico. This approach is an example of an analysis of the frequency of landslides that is computationally simple, and therefore, may be easily transferable to other settings.  相似文献   

Electron spin resonance and related studies of lignite and ball clay from South Devon,England     

Peter L. Hall  B.R. Angel  J. Braven 《Chemical Geology》1974,13(2):97-113

Electron spin resonance and infrared spectroscopic studies of lignite and ball clay from South Devon, and of extracts obtained from them by solvent fractionation, revealed similarities between corresponding organic components associated with both materials. All fractions exhibited a free radical resonance at g = 2.0037, which occurred with greatest intensity in the humic acids. Additional ESR features due to Fe³⁺, Mn²⁺ and VO²⁺ complexes were observed. Ferric ions give rise to resonances at g = 4.2 which have not been previously reported in the case of natural carbonaceous materials. It is shown that the paramagnetic species associated with the ball clay and lignite extracts do not significantly contribute to the observed ESR spectra of kaolinites, the latter being attributable to substituted Fe³⁺ ions and defect centres within the kaolinite lattice.  相似文献   

Editorial     

Martin Angel  James J. O&#x;Brien 《Progress in Oceanography》1984,13(1):i

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Editorial     

James J. O&#x;Brien  Martin V. Angel 《Progress in Oceanography》1981,10(1):i

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The diel migrations and distributions within a mesopelagic community in the North East Atlantic. 3. Planktonic ostracods, a stable component in the community     

M. V. Angel 《Progress in Oceanography》1984,13(3-4)

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Kinetics of inorganic arsenopyrite oxidation in acidic aqueous solutions     

M.A. McKibben  B.A. TallantJ.K. del Angel 《Applied Geochemistry》2008

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A contribution to the postglacial vegetation history of the Rila Mountains, Bulgaria: The pollen record of Lake Trilistnika     

Spassimir Tonkov  Elissaveta Bozilova  Gran Possnert  Angel Vel ev 《Quaternary International》2008,190(1):58

Pollen analysis of sediments from the glacial Lake Trilistnika (2216 m) in the Northwestern Rila Mountains (Bulgaria), supplemented by 13 radiocarbon dates, allowed the reconstruction of the palaeoenvironment and vegetation history in postglacial time. The exact time of the cirque glacier retreat is still under discussion but the lake was free of ice before 15,000 cal. BP, when sedimentation of gray silt began. The lateglacial vegetation, composed of Artemisia, Chenopodiaceae and Poaceae, with isolated stands of Pinus and Juniperus–Ephedra shrubland, dominated during the stadials and partly retreated during the Bølling/Allerød interstadial complex. The afforestation in the early Holocene (11,500–7800 cal. BP) started with the distribution of pioneer Betula forests with groups of Pinus (P. mugo, P. sylvestris and P. peuce) at mid-high altitudes, and Quercus forests with Tilia, Ulmus, Fraxinus, Corylus below the birch zone. The change to more humid and cooler climate ca. 7800–7500 cal. BP favored the vertical migration of Abies, P. sylvestris and P. peuce. The establishment of Fagus sylvatica took place after 5200 cal. BP, when pure or mixed beech communities were formed. The last tree which invaded the coniferous belt between 4300 and 3400 cal. BP was Picea abies. The first expansion maximum of spruce was recorded after ca. 2700 cal. BP. The vegetation development in historical times was also influenced by human interference, indicated by the continuous presence of pollen anthropogenic indicators such as Triticum, Secale, Hordeum, Plantago lanceolata, Rumex, Scleranthus, Juniperus.  相似文献   

Kumdykolite,kokchetavite, and cristobalite crystallized in nanogranites from felsic granulites,Orlica-Snieznik Dome (Bohemian Massif): not an evidence for ultrahigh-pressure conditions     

Silvio Ferrero  Martin A. Ziemann  Ross J. Angel  Patrick J. O’Brien  Bernd Wunder 《Contributions to Mineralogy and Petrology》2016,171(1):1-23

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Analysis of an illustrative interaction between structural features and earthworm populations in Brazilian ferralsols     

Michel Brossard  Gustavo Adolfo de Freitas Fregonezi  Maria de Fátima Guimarães  Cristiane de Conti Medina  Amarildo Pasini  Lourival Vilela  Miguel Angel Ayarza 《Comptes Rendus Geoscience》2012,344(1):41-49

Ferralsols are characterized by poorly-defined horizons, weak macrostructure and strong development of a fine granular structure comprising subangular micro-aggregates. In this study, the morphological and physical modifications caused by earthworm activity in a clayey ferralsol were analysed. After describing soil structures, undisturbed samples were taken for evaluating aggregates and determining clod bulk density and particle density. Soil water retention properties were measured and an inventory of soil invertebrate macrofauna was created. The structural and porous transformations were due to aggregates created by earthworm activity. Changes in bulk density can be associated with pore modifications caused by a change in the proportions of aggregate types, and a notable reduction of total porosity was measured, tending to increase soil volume with dense aggregates. Structural modifications affected the topsoil down to 0.5 m and water retention between −1 and −33 kPa, the principal water compartment of these soils.  相似文献