Environmental change in subtropical South America for the last two millennia as shown by lacustrine pigments     

Lisa Coianiz  Daniel Ariztegui  Eduardo L. Piovano  Andrea Lami  Piero Guilizzoni  Stefano Gerli  Nicolas Waldmann 《Journal of Paleolimnology》2015,53(2):233-250

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Use of sedimentary pigments to infer past phosphorus concentration in lakes     

Piero Guilizzoni  Aldo Marchetto  Andrea Lami  Stefano Gerli  Simona Musazzi 《Journal of Paleolimnology》2011,45(4):433-445

We propose a palaeolimnological method for inferring past total phosphorus (TP) concentrations in lake water from spectrophotometrically-measured sedimentary pigments, particularly total carotenoids (TC). Our approach is based on a highly significant statistical correlation (P < 0.0001) between pigment concentrations (total carotenoids) in the surface sediment of 28 Italian lakes (subalpine, large, deep, shallow, volcanic) and TP concentrations measured in these lakes at overturn when the core was collected. A transfer function was developed from this “training” set, and used to estimate past TP concentrations from pigment concentrations in sediment cores. The results generally agreed with TP values as measured by long-term water quality monitoring programs. Contrasting results were obtained by a comparison with diatom-inferred TP. While the diatom model showed a tendency to overestimate TP values higher than 100 μg l⁻¹, the pigment model correctly estimated TP in lakes when TP was <100 μg l⁻¹, but not when lakes were rich in macrophytes. In fact, lakes with extensive populations of aquatic submersed macrophytes and epiphytes are outliers in terms of the TC versus TP relationship. The root mean square error of prediction of the pigment model is lower than those derived from certain diatom—based inference models. The predicted and residual values are not related to the estimated values and their average is not statistically different from zero. Errors were estimated via a ‘leave-one-out’ re-sampling technique. The proposed method permits rapid and relatively inexpensive determination of reference trophic conditions.  相似文献   

Defining ecological and chemical reference conditions and restoration targets for nine European lakes     

Helen Bennion  Gavin L. Simpson  N. John Anderson  Gina Clarke  Xuhui Dong  Anders Hob?k  Piero Guilizzoni  Aldo Marchetto  Carl D. Sayer  Hansj?rg Thies  Monica Tolotti 《Journal of Paleolimnology》2011,45(4):415-431

This paper aims to determine the ecological and chemical reference conditions (~1800?C1850 AD) and degree of floristic change at nine enriched lakes, covering a range of types across Europe, using fossil diatom assemblages in dated sediment cores and application of total phosphorus (TP) transfer functions. Additionally the study assesses the potential of analogue matching as a technique for identifying reference sites and for estimating reference TP concentrations for the study lakes using a training set of 347 European lakes and 719 diatom taxa. Oligotrophic, acidophilous to circumneutral taxa were predominant in the reference samples of several of the deep lakes, and benthic Fragilaria spp. dominated the reference samples of two high alkalinity shallow lakes. The degree of floristic change from the reference sample, assessed using the squared chord distance (SCD) dissimilarity coefficient, revealed that two sites had experienced slight change (Lago Maggiore, Felbrigg Lake), five experienced moderate change (Mjoesa, Loch Davan, Loch Leven, White Lough, Esthwaite Water), and two showed evidence of major change (Groby Pool, Piburger See). For three lakes, there were no analogues in the diatom dataset owing to the uniqueness and diversity of the diatom reference assemblages. For the remaining six sites the number of analogues ranged from 2 to 44. For two deep lakes most of the analogues seemed appropriate as they were of the same type and had low TP concentrations. However, for two other deep lakes and two shallow lakes some of the analogues differed markedly in their depth and alkalinity from the lake in question or had TP concentrations seemingly too high to represent reference conditions suggesting that the analogues may not be suitable as reference sites. For the deep lakes, similar reference TP values were calculated using the EDDI Combined TP transfer function and the analogue matching technique with concentrations typically <20 ??g L^?1. However, for the shallow lakes, the analogue matching method produced inferred values considerably higher than those of the transfer function. The wide ecological tolerances of many of the diatom taxa found in the reference samples most likely explain the selection of inappropriate analogue sites. In summary, the study demonstrates that palaeoecological techniques can play a valuable role in determining reference conditions and indicates that the analogue matching technique has the potential to be a useful tool for identifying appropriate reference sites for lakes impacted by eutrophication.  相似文献   

Occurrence of Irgarol 1051 and its major metabolite in Maryland waters of Chesapeake Bay   总被引：1，自引：0，他引：1  

Hall LW  Killen WD  Gardinali PR 《Marine pollution bulletin》2004,48(5-6):554-562

Irgarol and its major metabolite (GS26575) were measured in Maryland waters of Chesapeake Bay: (1) in and near 10 marinas, a mainstem Bay site and two Severn River locations during a general survey in July and December of 2002; (2) at various sites in the Port Annapolis Marina and the Severn River area during March of 2002 before the boating season began; and (3) during July (peak boating season) in the same Port Annapolis Marina and Severn River sites area during both an ebb and flood tide. Irgarol concentrations ranged from 1.82 ng/l at the mid-Bay site to 585 ng/l in Port Annapolis marina during the July and December general survey. An Irgarol 90th centile of 239 ng/l was reported for the 10 marina sites, two Severn River sites and one mainstem site sampled during the general survey conducted in July and December. Temporal analysis of all pooled data showed that 90th centiles were over seven times higher in July when compared to December. A comparison of Irgarol concentrations at 12 sites in the Port Annapolis marina and Severn River area during both an ebb and flood tide in July showed no consistent trend with tidal cycle by site although significant reductions in concentrations were reported with distance from the three Port Annapolis marina sites. Ecological risk from Irgarol exposure was judged to be low for most Chesapeake Bay sites sampled. Possible exceptions were Port Annapolis marina, Severn River sites in close proximity to this marina and Chesapeake Harbor marina where Irgarol concentrations exceeded a conservative effects threshold during the peak boating season in July. Ecological risk from GS26575 exposure was low for all sites.  相似文献   

Reply to the Discussion by Maravelis and Zelilidis on “Unravelling provenance from Eocene–Oligocene sandstones of the Thrace Basin,North‐east Greece” by Caracciolo et al. (2011), Sedimentology, 58, 1988–2011.     

Luca Caracciolo  Salvatore Critelli  Fabrizio Innocenti  Niko Kolios  Piero Manetti 《Sedimentology》2013,60(3):865-869

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A downturn in intergalactic C iv as redshift 6 is approached     

Emma V. Ryan-Weber †  Max Pettini  Piero Madau  Berkeley J. Zych 《Monthly notices of the Royal Astronomical Society》2009,395(3):1476-1490

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Magma-induced strain localization in centrifuge models of transfer zones   总被引：1，自引：0，他引：1  

Giacomo Corti  Marco Bonini  Francesco Mazzarini  Mario Boccaletti  Fabrizio Innocenti  Piero Manetti  Genene Mulugeta  Dimitrios Sokoutis 《Tectonophysics》2002,348(4)

Scaled centrifuge experiments have been used to investigate the dynamic relations between deformation and magma distribution in rift-related transfer zones. The physical models were built using suitable analogue materials, such as sand to represent the brittle upper crust, various kinds of silicone mixtures to simulate the lower crust and upper mantle and glycerol to reproduce magma. Models simulated the development of transfer zones across pre-existing glycerol reservoirs placed at the base of the analogue continental crust. In plan view, different geometries, dimensions and positions of subcrustal reservoirs were reproduced in three different sets of experiments; to compare results, models were also performed without magma-simulating glycerol.Set 1 experiments, incorporating a narrow rectangular glycerol reservoir, show that the low-viscosity material is able to localise deformation into the overlying crust, giving rise to discrete transfer zones. This concentrated surface deformation corresponds at depth to major magma accumulation. Set 2 experiments, with an initial wide squared glycerol reservoir, show instead that deformation is distributed across the whole model surface, corresponding at depth to relatively minor magma accumulation. Set 3 experiments explored various positions of a small squared reservoir that invariably localised faulting in the overlying analogue brittle crust at the onset of model deformation.The overall model behaviour suggests that magma distribution at depth can effectively control the strain distribution in the overlying crust and the deformative pattern of transfer zones. Strain distribution, in turn, may control magma emplacement as localized deformation would favour major accumulation of magma at transfer zones. Coupled to a strong thermal weakening of the country rocks, this process may ultimately lead to a positive feedback interaction between magma and deformation.  相似文献   

Pollution effects of the Tuy River on the central Venezuelan coast: Anthropogenic organic compounds and heavy metals in Tivela mactroidea     

Rudolf Jaffe  Ivan Leal  Jose Alvarado  Piero Gardinali  Jos Sericano 《Marine pollution bulletin》1995,30(12):820-825

Bivalve samples were collected at seven sampling stations located between the town of Machurucuto and the Bay of Higuerote, Venezuela, covering approximately 70 km of coastline. Samples were collected both east and west of the Tuy River mouth, which has a plume known to move in a north-westerly direction. Petroleum hydrocarbons, both aliphatic (n-alkanes and UCM) and polyaromatic (PAHs), were detected and quantified in the samples. These hydrocarbons were found to be primarily derived from fossil fuels. Halogenated organics consisted mostly of polychlorinated biphenyls (PCBs) and some chlorinated pesticides, primarily of the DDT group. Heavy metals such as Pb, Cu, Ni, Zn, Cr and Cd were analysed in the samples. The results clearly show the influence of the Tuy River plume on the water quality of the coastal zone, particularly that located west of the river mouth. One sampling station, located just east of the river mouth, also showed significant influence from the river plume.  相似文献   

Fractionation of Nb and Ta from Zr and Hf at Mantle Depths: the Role of Titanian Pargasite and Kaersutite   总被引：8，自引：4，他引：8  

TIEPOLO  M.; BOTTAZZI  P.; FOLEY  S. F.; OBERTI  R.; VANNUCCI  R.; ZANETTI  A. 《Journal of Petrology》2001,42(1):221-232

Selective enrichment or depletion in either Zr and Hf (HFSE⁴⁺)or Nb and Ta (HFSE⁵⁺) is a feature commonly observed in manymantle-derived melts and amphiboles occurring as either disseminatedminerals in mantle xenoliths and peridotite massifs or in veinassemblages cutting these rocks. The fractionation of Nb fromZr seen in natural mantle amphiboles suggests that their incorporationis governed by different crystal-chemical mechanisms. An extensiveset of new partitioning experiments between pargasite–kaersutiteand melt under upper-mantle conditions shows that HFSE incorporationand fractionation depends on amphibole major-element compositionand the presence or absence of dehydrogenation. Multiple regressionanalysis shows that ^Amph/LD_Nb/Zr is strongly dependent on themg-number of the amphibole as a result of a combination of amphiboleand melt structure effects, so that the following generalizationsapply: (1) high-mg-number amphiboles crystallized from unmodifiedmantle melts more easily incorporate Zr relative to Nb leadingto an increase of the Nb/Zr ratio in the residual melt; (2)low-mg-number amphiboles, such as those found in veins cuttingperidotites, may strongly deplete the residual melt in Nb andcause very low Nb/Zr in residual melts. Implications and applicationsto mantle environments are discussed. KEY WORDS: trace elements; high field strength elements; partition coefficients; amphibole; upper mantle  相似文献   

AN ION PROBE CONTRIBUTION TO RARE EARTH ELEMENT INVESTIGATION OF GABBRO GOG-1 USING SECONDARY ION MASS SPECTROMETRY   总被引：1，自引：0，他引：1  

Luisa OTTOLINI  Piero BOTTAZZI  Riccardo VANNUCCI  Massimo ODDONE 《Geostandards and Geoanalytical Research》1992,16(1):13-19

An updated REE measurement of Gabbro GOG-1 was carried out by means of secondary ion mass spectrometry (SIMS). The availability of high amount of rock powder allowed the sample to be well ground and homogenized before analysis. Fused glass pellets were employed for SIMS investigations. REE data were compared with new ICP-AES and NAA analyses. REE results from all employed analytical techniques show good agreement and are consistent with in-situ SIMS measurements of REE in major mineral phases forming GOG-1. Extensive homogeneity tests seem to confirm the possibility to using this rock as a reference material for earth sciences.  相似文献