Preferential flow and aging of NAPL in the unsaturated soil zone of a hazardous waste site: implications for contaminant transport     

Kai U. Totsche  Ingrid Kgel‐Knabner  Bettina Haas  Stefan Geisen  Rainer Scheibke 《植物养料与土壤学杂志》2003,166(1):102-110

Flow of non‐aqueous phase liquids (NAPL) in the unsaturated zone is thought to be driven by gravity with a dominant vertical flow direction, and lateral spreading to be limited to the gradient of the relative permeabilities. The effect of soil profile build‐up, preferential flow, aging, and groundwater level fluctuations is mostly neglected. The objective of our study was to check the effects of such processes on the fate of NAPL in the unsaturated soil zone. At a hazardous waste site, we conducted a field survey of the unsaturated soil zone and monitored the groundwater for a two year period. We conducted spatially resolved and depth dependent soil sampling and analysis and the evaluation of former ram and core drilling protocols. The samples were analyzed for the 16 EPA PAH and alkanes with GC‐MS and GC‐FID. ¹³C‐NMR spectroscopy was used to assess structural changes of the NAPL phase. Flow of bulk NAPL along macropores and along preferential permeability structures, like sedimentation discontinuities, are the dominant transport pathways which cause large lateral spreading beyond those expected by the relative permeability gradient. Accumulation of NAPL was found at locations with abrupt textural changes and within the zone of capillary rise. Aging of NAPL results in the depletion in soluble and volatile compounds but also in oxidation and polymerization. It increases the chemical diversity and decreases the mobility of the NAPL. Thus, NAPL flow ceases much earlier than expected from the capillary forces. As chemical transformation is restricted to the NAPL water/air interface, a skin‐like thin film is formed which encapsulates and preserves the bulk NAPL from further hardening, limiting contaminant mass transfer from the NAPL to the aqueous phase.  相似文献   

Sorption of Selected Aromatic Substances��Application of Kinetic Concepts and Quantum Mechanical Modeling     

Sabine Klepsch  Adelia J. A. Aquino  Ursula Haas  Daniel Tunega  Georg Haberhauer  Martin H. Gerzabek  Hans Lischka 《Water, air, and soil pollution》2011,215(1-4):449-464

Prediction of the sorption behavior of environmental pollutants is of utmost importance within the framework of risk assessments. In this work two approaches are presented with the aim to describe sorption of aromatic substances to geosorbents. First, analytical solutions of kinetic models were fitted to experimental data of batch sorption experiments with aniline and 1-naphthylamine onto animal manure-treated soil and the soil mineral montmorillonite. The models, accounting for equilibrium and nonequilibrium sorption coupled to transformation and/or irreversible sorption processes, could well reproduce the concentration course of the sorbates. Results suggest that the amounts transformed/degraded and irreversibly bound were higher for the soil than for the clay mineral. In the second part, quantum chemical calculations were performed on aniline and 1-naphthylamine interacting with acetic acid, acetamide, imidazole, and phenol as models of functional groups present in humic substances. Molecular modeling showed that formation of hydrogen bonds is the dominating binding mechanism in all modeled complexes, which are energetically very similar between aniline and 1-naphthylamine.  相似文献   

Efficacy and safety of a new 450 mg/ml florfenicol formulation administered intramuscularly in the treatment of bacterial bovine respiratory disease     

Thiry J  Rubion S  Sarasola P  Bonnier M  Hartmann M  de Haas V 《The Veterinary record》2011,169(20):526

The objective of the study was the safety and efficacy evaluation of a new 450 mg/ml florfenicol formulation in the treatment of naturally occurring respiratory disease when administered intramuscularly, compared with a positive control group treated with the well-established 300 mg/ml formulation. A total of 174 calves, selected from five sites in France and Spain, aged from 1 to 17 months, showing severe signs of respiratory disease, were randomly assigned to treatment with either the 300 mg/ml (3 ml/45 kg; Nuflor; MSD Animal Health) or 450 mg/ml (2 ml/45 kg; Nuflor Minidose; MSD Animal Health) florfenicol formulation, both administered intramuscularly twice, two days apart. Animals were clinically observed daily for 14 days following treatment initiation. The predominant pathogens present in pretreatment respiratory tract samples were Mannheimia haemolytica and Pasteurella multocida. Mycoplasma bovis and Histophilus somni were also present. All isolates were subjected to in vitro sensitivity testing and found susceptible to florfenicol. In both treatment groups, rectal temperature dropped and clinical index (depression and respiratory signs) significantly improved (P<0.05) after treatment. As a result, 97.7 per cent of the 450 mg/ml florfenicol formulation-treated animals were considered treatment successes on day 5. On day 14, 67.82 per cent of the animals were classified as treatment successes and among them 63.22 per cent were cured. The intramuscular injection of the new 450 mg/ml florfenicol formulation was found equally efficacious as the original 300 mg/ml formulation.  相似文献   

The presence of crown gall of grape incited byagrobacterium tumefaciens biovar 3 in Israel     

Jerry H. Haas  Aida Zveibil  D. Zutra  Edna Tanne  Shulamit Manulis 《Phytoparasitica》1991,19(4):311-318

Crown gall was previously reported on grape in Israel but the pathogen was not isolated and characterized. The three recognized biovars ofAgrobacterium tumefaciens can be tumorigenic on grape, but biovar 3 is the most important world wide. A single occurrence of tumors in a vineyard yielded bacteria which incited galls on grape,Nicotiana glauca and tomato, but not on bryophyllum. The bacteria were confirmed asA. tumefaciens because they contained DNA which hybridized with T-DNA from a Ti plasmid. Biochemical and physiological tests, octopine production and utilization, and agrocin 84 insensitivity conformed with those of bv. 3. Subsequent occurrences of the grape disease have not been found, but the presence ofA. tumefaciens bv. 3 in Israel is a potential threat to nurseries and vineyards.  相似文献   

Draws attention to early one-health wonder     

Haas KB 《Journal of the American Veterinary Medical Association》2008,233(5):706

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Rhodococcus equi research 2008–2012: Report of the Fifth International Havemeyer Workshop     

S. Cauchard  S. Giguère  M. Venner  G. Muscatello  J. Cauchard  N. D. Cohen  A. Haas  S. A. Hines  M. K. Hondalus  D. W. Horohov  W. G. Meijer  J. F. Prescott  J. Vázquez‐Boland 《Equine veterinary journal》2013,45(5):523-526

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Comments on veterinarians' responsibility to society     

Haas KB 《Journal of the American Veterinary Medical Association》2007,230(3):341

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Kinetic limitations on the selective precipitation treatment of electronics wastes     

S. B. Karra  C. N. Haas  V. Tare  H. E. Allen 《Water, air, and soil pollution》1985,24(3):253-265

Laboratory studies on the precipitation of metals from a synthetic wastewater simulating the composition of semiconductor manufacturing were performed. Residual soluble metals, in many cases, were dependent upon the age of the waste prior to precipitation. Based upon these studies, it was concluded that equilibrium information alone does not provide a complete understanding of metal removal by chemical precipitation.  相似文献   

THE SIZE OF THE UNIVERSE AND THE FUNDAMENTAL CONSTANTS OF PHYSICS     

Haas A 《Science (New York, N.Y.)》1936,84(2191):578-579

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Ralph R. Parker: 1888-1949     

Haas VH 《Science (New York, N.Y.)》1950,111(2873):56-57

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