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21.
Characterization of water extractable organic matter in a deep soil profile   总被引:5,自引:0,他引:5  
The aim of this study was to identify qualitative and quantitative differences of water extractable organic matter (WEOM) isolated from each horizon along a deep soil profile and to evaluate any relationship between the WEOC and the total organic carbon (TOC) content. The soil profile "Monte Pietroso" is located in the Murge area, Apulia region in Southern Italy. Samples from the eight horizons (Ap1, Ap2, Ab1, Ab2, Bt1, 2B, 2Bt2, and 2B/C) were collected in October 2002. The WEOM characterization was carried out by means of UV absorbance, fluorescence spectroscopy in the emission and excitation/emission matrix (EEM) modes, and additional spectroscopic derived indexes. Soil organic carbon was shown to accumulate in the top horizons (Ap) and, in general, to decrease with depth, whereas, the WEOM/TOC ratio increases with increasing depth. The aromaticity and the humification index of the WEOM decrease dramatically downward the soil profile, whereas the fluorescence efficiency index tends to increase markedly. The WEOM fractions feature three main fluorophores with different wavelength and relative intensity. In general WEOM transport phenomena are suggested to occur downward the soil profile, depending on the nature of the organic material and on the chemical and mineral characteristics of the various horizons.  相似文献   
22.
Water is a precious resource in arid rural areas with irrigated agriculture. Nonetheless, water and agricultural policies in Europe show different management scopes and objectives, usually translated in divergent drivers of rural change. This paper has a double aim: to propose a specific method for quantitative biophysical analysis of water use in rural systems with the multi-scale integrated analysis of societal and ecosystem metabolism approach and to show the usefulness of this method for the assessment of the integration of water and agricultural policies. The river basin scale is chosen, since it is the socioecological unit for water management established in the water framework directive 2000/60/CE. A multi-scale water use accounting is provided for a Mediterranean river basin in Andalusia, integrating water cycle, ecosystems and social levels. Particularly focusing on agricultural production, a relevant set of indicators is proposed in order to analyze and compare different metabolic patterns. Finally, the integration of water and agricultural planning is assessed in terms of external (biophysical) and internal (economic, institutional) constraints of the new water-use patterns generated by the scenarios posed in these policies. While on a European level water policy is ambitious in terms of ecological conservation, the lack of integration within the common agricultural policy and the entanglement of multiple scales of political and economic organization of local ruralities blur its priority in a rather slow transition to a new water culture.  相似文献   
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Estrogens are a class of micro-pollutants found in water at low concentrations (in the ng L−1 range), but often sufficient to exert estrogenic effects due to their high estrogenic potency. Disinfection of waters containing estrogens through oxidative processes has been shown to lead to the formation of disinfection byproducts, which may also be estrogenic. The present work investigates the formation of disinfection byproducts of 17β-estradiol (E2) and estrone (E1) in the treatment of water with ozone. Experiments have been carried out at two different concentrations of the estrogens in ground water (100 ng L−1 and 100 μg L−1) and at varying ozone dosages (0-30 mg L−1). Detection of the estrogens and their disinfection byproducts in the water samples has been performed by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a triple quadrupole (QqQ) and a quadrupole-time of flight (QqTOF) instrument. Both E2 and E1 have been found to form two main byproducts, with molecular mass (MM) 288 and 278 in the case of E2, and 286 and 276 in the case of E1, following presumably the same reaction pathways. The E2 byproduct with MM 288 has been identified as 10epsilon-17beta-dihydroxy-1,4-estradieno-3-one (DEO), in agreement with previously published results. The molecular structures and the formation pathways of the other three newly identified byproducts have been suggested. These byproducts have been found to be formed at both high and low concentrations of the estrogens and to be persistent even after application of high ozone dosages.  相似文献   
25.
The transport of chromium by the emulsion pertraction technology (EPERT) using Hostarex A327 (tertiary amine) as a carrier has been investigated. The permeation of the metal is studied as a function of various experimental variables: hydrodynamic conditions, concentration of Cr(VI) and HCl in the source phase, carrier concentration and diluent in the organic phase, strippant concentration in the stripping phase and support characteristics of the membrane. The mass transfer coefficient and the thickness of the aqueous source boundary layer were estimated from the experimental data. Furthermore, the selectivity of the Hostarex A327-bases EPERT towards different metal ions and the behaviour of the system against other carriers are presented.  相似文献   
26.
A population of the regular sea urchin Lytechinus variegatus was sampled, and the gonad volume and test diameter recorded at monthly intervals for 10 years. Parameters abstracted from the data included the size and date when the gonads were full and when they were spent, the spawning pattern, and the spawn output. Environmental parameters available were sea temperature and rainfall. Correlations were determined among these. A correlation was also found between the appearance in successive years of a brood of young urchins on the shore and the temperature and rainfall.Contribution No. 1490 from Rosenstiel School of Marine and Atmospheric Science, University of Miami, 10 Rickenbacker Causeway, Miami, Florida 33149, USA. We are indebted to the Federal Water Quality Administration for supporting this work under Grant No. DI WP-01433.  相似文献   
27.
We study the horizontal surface mixing and the transport induced by waves in a coastal environment. A comparative study is addressed by computing the Lagrangian coherent structures, via Finite Size Lyapunov Exponents, that arise in two different numerical settings: with and without wave coupled to currents. In general, we observe that mixing is increased in the area due to waves. Besides, the methodology presented here is tested by deploying a set of eight Lagrangian drifters at different locations. This dynamical approach is shown as a valuable tool to extract information about transport, mixing and residence embedded in the Eulerian time dependent velocity fields obtained from numerical models.  相似文献   
28.
Environmental Science and Pollution Research - The aim of this study is to assess—for the first time—the concentration of the 16 polycyclic aromatic hydrocarbons (PAHs) in the muscle...  相似文献   
29.
The assessment of human-induced pressures on the coastal area is essential to target management plans effectively, and moreover is required by the EU Water Framework Directive. A simple and cost-effective assessment of human-induced pressures on the coastal zone is applied using two methodologies: a qualitative visual assessment which uses satellite images; and a quantitative assessment based on governmental census data. These methods are applied to defined areas (23 areas) of four Italian regions: Liguria, Tuscany, Latium and Sardinia. The results show a high agreement (83%) between these two methods, in which only four of the 23 areas are classified differently. These differences may mainly be ascribed to the qualitative or quantitative properties of the methods, and to the different geographical units adopted. These characteristics however provide complementary information, which suggests that the application of both proposed methods confirms reliability and allows fine-tuning of the assessment. The pressure assessment proposed is simple, time and cost-effective, and repeatable over time and space. It therefore can be applied in different contexts to respond to legislative requirements or to target management plans and remedial actions effectively.  相似文献   
30.
The sirenomelia sequence with fusion, rotation, hypotrophy or atrophy of the lower limbs in combination with severe urogenital and gastrointestinal malformations is a rare and usually lethal disorder. We present the case of a 28-year-old woman, who was referred to our department because of an intraabdominal cystic structure in the 9th week of gestation. Subsequent scans confirmed the diagnosis of a sirenomelia sequence with the fusion of the lower extremities without fusion of the bones according to Stocker I classification. The size of the intraabdominal cyst decreased during follow-up. After counseling, termination of pregnancy was induced. The postmortem X-ray confirmed the ultrasound diagnosis. The exact etiological mechanism of this malformation is still unknown. An early alteration of the embryological vascular network damaging the caudal mesoderm is thought to lead to arrested development of the lower limbs and other affected organs. The cyst we saw in the 9th week might fit with this theory, either as an expression of the complex malformation of the lower abdomen or as the sonographic appearance of necrosis. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
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