Field accumulative behavior of organochlorine pesticides. The role of crabs and sediment characteristics in coastal environments     

Menone ML  Miglioranza KS  Botto F  Iribarne O  Aizpún de Moreno JE  Moreno VJ 《Marine pollution bulletin》2006,52(12):1717-1724

The influence of intertidal crab beds on the concentrations of organochlorine (OC) pesticides in sediment was studied in two different coastal environments in Argentina. Samples of male burrowing crabs (Chasmagnathus granulatus) were collected for this study. Our field data showed lower bioaccumulation of OC pesticides in crabs from sediments with a higher total organic carbon (TOC) and higher clay content. Thus, concentrations in crabs depend on the physico-chemical characteristics of the sediment where they live more than on the OC pesticide concentrations in the environment. The distribution patterns in sediment from inside and outside crab burrows were similar for both coastal areas being HCHs  γ-chlordane > p,p′-DDE for San Antonio Bay (SAO), and HCHs > p,p′-DDE  γ-chlordane for Mar Chiquita (MCh) coastal lagoon. OC pesticide concentrations in sediment were significantly lower inside than outside crab burrows, irrespective of the sediment physico-chemical characteristics due to the bioturbation activity of C. granulatus.  相似文献   

Hydrocarbons, popular protest and national imaginaries: Ecuador and Bolivia in comparative context   总被引：3，自引：0，他引：3  

Tom Perreault  Gabriela Valdivia 《Geoforum》2010,41(5):689-365

This paper examines contemporary struggles over hydrocarbon governance in Ecuador and Bolivia. Our comparative analysis illustrates the ways that petro-capitalism, nationalist ideologies, popular movements and place conjoin in the governance of oil and natural gas. In the case of Ecuador, state employees drew on their labor relations and political training to oppose the government’s efforts to privatize the state oil company. In Bolivia, urban popular movements opposed the privatization of the hydrocarbons industry and its domination by foreign firms. In both cases, hydrocarbons struggles involved the production of imaginative geographies of the nation and it hydrocarbon resources, which in turn drew on historical memories of nationhood. Whereas neoliberal political and economic restructuring sought to re-organize national hydrocarbons companies, redraw concessions, and draft new resource extraction laws, hydrocarbon movements aimed to counter these processes by re-centering hydrocarbon governance within a populist vision of the nation-state. In contrast to analyses of resource conflict in the environmental security and resource curse literatures, the cases of Ecuador and Bolivia demonstrate that such struggles cannot be reduced to models of opportunity structure, war profiteering, or resource scarcity (or abundance). Rather, these cases show that political economy and cultural politics are inseparable in the context of resource conflicts, which involve struggles over the meanings of development, citizenship and the nation itself.  相似文献   

Integrated spectroscopic study of 7 star clusters in the Small Magellanic Cloud     

M.L. Talavera  A.V. Ahumada  J.F.C. Santos  Jj. Clari  E. Bica  M.C. Parisi  M.C. Torres 《Astronomische Nachrichten》2010,331(3):323-329

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An assessment of global and regional climate change based on the EH5OM climate model ensemble     

Čedo Branković  Lidija Srnec  Mirta Patarčić 《Climatic change》2010,98(1-2):21-49

An analysis of climate change for global domain and for the European/Mediterranean region between the two periods, 1961–1990 (representing the twentieth century or “present” climate) and 2041–2070 (representing future climate), from the three-member ensemble of the EH5OM climate model under the IPCC A2 scenario was performed. Ensemble averages for winter and summer seasons were considered, but also intra-ensemble variations and the change of interannual variability between the two periods. First, model systematic errors are assessed because they could be closely related to uncertainties in climate change. A strengthening of westerlies (zonalization) over the northern Europe is associated with an erroneous increase in MSLP over the southern Europe. This increase in MSLP is related to a (partial) suppression of summer convective precipitation. Global warming in future climate is relatively uniform in the upper troposphere and it is associated with a 10% wind increase in the subtropical jet cores. However, spatial irregularities in the low-level temperature signal single out some regions as particularly sensitive to climate change. For Europe, the largest near-surface temperature increase in winter is found over its north-eastern part (more than 3°C), and the largest summer warming (over 3.5°C) is over south Europe. For south Europe, the increase in temperature averages is almost an order of magnitude larger than the increase in interannual variability. The magnitude of the warming is larger than the model systematic error, and the spread among the three model realisations is much smaller than the magnitude of climate change. This further supports the significance of estimated future temperature change. However, this is not the case for precipitation, implying therefore larger uncertainties for precipitation than for temperature in future climate projections.  相似文献   

Constraints to Uranus' Great Collision III: The Origin of the Outer Satellites     

Adrián Brunini  Mirta Gabriela Parisi  Gonzalo Tancredi 《Icarus》2002,159(1):166-177

The theory of satellite loss resulting from a giant impact on Uranus (Parisi and Brunini 1997, Planet. Space Sci.45, 181-187) is revisited, in the light of the discovery of its five outer moons (Gladman et al. 1998, Nature392, 897-899; Gladman et al. 2000, Icarus147, 320-324; erratum 148, 320). Physical conditions and dynamical constraints in the great collision scenario and restrictions in the possible mechanisms for the origin of the outer uranian satellites are obtained from the knowledge of their actual orbital properties. We conclude that the existence of these moons implies that their origin must be connected to a breakup process. Other scenarios for their origin cast serious doubts on the occurrence of a giant collision at the end of Uranus' formation process to account for its large spin axis obliquity.  相似文献   

Seismic vulnerability and risk evaluation for old urban nuclei     

Duilio Benedetti  Gianmario Benzoni  Maria A. Parisi 《地震工程与结构动力学》1988,16(2):183-201

The evaluation of the seismic damageability of existing buildings is a primary element in the planning for mitigation of earthquake effects. To this purpose, the use of the vulnerability index has been recently proposed and adopted in various surveys in Italy. The index results from grading the status of various structural and non-structural components exposed to damage in a seismic event. The effectiveness of the vulnerability index as a measure of the health status of buildings is discussed on the basis of regional surveys of vulnerability index versus reported damage, carried out in various Italian areas such as Friuli and the city of Gubbio. Also, investigation of the items most effective in describing damageability among those contributing to the index is performed, in view of formulating a reduced survey procedure. A damage versus vulnerability index database collected in these surveys is presented as well. Finally, a vulnerability index based procedure to evaluate the expected damage in a territory is proposed.  相似文献   

Marginal cost based seismic decision: A probabilistic approach     

Maria A. Parisi 《地震工程与结构动力学》1987,15(3):367-377

Among various methodologies for seismic risk mitigation, the use of the marginal cost of saving a life as decision variable, proposed in the literature, does not require to assign a cost to human life. Also, optimization of resources over a territory can be profitably performed in terms of such a variable. Parameters of different type (seismic, structural, financial) enter into the analytical definition of the marginal cost of saving a life. These parameters are subject to intrinsic variability and uncertainty that are bound to affect the decision variable. This aspect was not originally taken into account systematically. The influence of the uncertainty in the various basic parameters on the decision variable is studied here. A procedure is suggested to develop constant probability of exceedance contours of the decision variable versus the design coefficient to be selected. The suggested procedure is exemplified for two regions of different seismicity.  相似文献   

Enhanced spectral UV irradiance: a 1 year preliminary study     

J. M. Sabburg  A. V. Parisi  M. G. Kimlin   《Atmospheric Research》2003,66(4):261

The ultraviolet (UV) spectra on cloudy days were compared to those on cloud free days to determine which part of the UV spectrum has the greatest enhancement due to the cloud compared to both corresponding measured clear sky spectra as well as other enhanced spectra. In this preliminary study, cloud enhanced UV spectra selected for maximum UVA enhancement compared to a clear sky UV spectrum at similar solar zenith angle (SZA) and ozone values, showed that the ratio of the two sets of spectral irradiances was approximately wavelength independent (approximately 1.1) above the cut-off wavelength of approximately 306 nm. Similarly, above 306 nm the average ratio of the spectral irradiances of a maximum UVB enhanced UV spectrum compared to a clear sky spectrum was 1.2 with maximum values generally above this average between 316 and 344 nm and generally below 1.2 above the wavelength of 344 nm. The UVA and UVB enhanced spectra were separated into five SZA ranges and the irradiance at each wavelength averaged for each range and compared to clear sky spectra in each of the ranges. Above approximately 306 nm, the ratios are wavelength independent for all SZA. However, with the exception of the SZA range centred on 20°, there is an increasing dependency with shorter wavelengths below the 306 nm. Also there appears to be two distinct groupings of the average irradiance ratios, corresponding to the SZA range centred on 20°, 37° and 49° (ratio of 1.2) and 32° and 42° (ratio 1.0), the latter cases suggesting that on average there is no enhancement for these SZA, except for wavelengths less than 306 nm.  相似文献   

Within versus between-lake variability of sedimentary diatoms: the role of sampling effort in capturing assemblage composition in environmentally heterogeneous shallow lakes     

Gabriela S. Hassan 《Journal of Paleolimnology》2018,60(4):525-541

The effect of within-lake diatom assemblages variability on sample representativity and its subsequent impact on between-lake comparisons were addressed in three environmentally heterogeneous shallow lakes from the Argentinean Pampas. Surface sediment samples were collected from the open waters and the highly vegetated littoral areas on a seasonal basis and analyzed for diatom assemblages composition. Within-lake variability was assessed by comparing the Bray Curtis distances between original data and the Monte Carlo-simulated average assemblages composition through non-metric multidimensional scaling (NMDS). Diatom assemblages showed a high variability in composition, evidencing large dispersions of samples around the centroid in NMDS plots. Permutational multivariate analysis of variance tests signaled significant differences in average composition between the three lakes, related mainly to their differences in conductivity and depth. Representativity of original samples was assessed through principal coordinates analyses ordinations of the three lakes, being samples lying in the overlapping areas of the plot classified as poor representatives of between-lake differences. Several samples, both from littoral and open waters, were classified as poor representatives through this method. Simulation allowed us to evaluate the effect of sample replication on improving between-lake comparisons, and showed that collecting two littoral and two open-water samples allowed us to faithfully capture differences in average composition among the three lakes. Hence, the results suggest that using a single sample to estimate diatom assemblages composition in these lakes should be avoided, as it fails to capture between-lake differences, leading to biases in compositional comparisons among lakes and regions. Consequently, including multiple samples from each lake when constructing calibration sets would be the best option to obtain reliable paleoenvironmental reconstructions from single sediment cores in these environmentally heterogeneous shallow lakes.  相似文献   

Long term variation in rainfall erosivity in Uruguay: a preliminary Fournier approach     

Carolina Munka  Gabriela Cruz  Ruben Mario Caffera 《GeoJournal》2007,70(4):257-262

In order to explore the consequences of precipitation increase on soil erosion in Uruguay, the monthly Fournier Index (FI) and the annual Modified Fournier Index (MFI) were developed as a preliminary approach, covering consecutive decadal periods from 1931 to 2000. Rainfall data were used from 13 stations distributed all over the country. MFI shows a decrease in the 1940s, an increase during the 1950s, then a little decrease during the 1960s and 1970s and an increase in the 1980s, remaining near these last values during the 1990s. FI behavior in July and October in the last two decades shows a decrease in the Northeast region of the country—the region with highest annual precipitation—and a slight increase over the Southeast—the region with the lowest annual precipitation and the only region with a winter rainfall maximum. For the core months of winter and early spring there is a decline in erosivity in the Northeast, but an increase in the Southeast. January shows erosivity decreasing in the South during the last two decades. In April there is a peak in precipitation variability all across the country. FI shows an early increase during the 1940s in the Northwest, and generally very low values during the 1970s, with the return of high values in the 1990s, especially in the Northern corner. Results pose a challenge in order to improve research on the erosion problem, since the main source of freshwater nationwide remains surface river flow, which is prone to higher turbidity problems in areas of high soil erosion.  相似文献