خيارات البحث
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Evaluation of fate and exposure models - Fate of pulp mill effluent compounds in a Finnish watercourse.
1994
Trapp S. | Rantio T. | Paasivirta J.
Chloroorganic chemicals emitted from the pulp and paper mill at Nekoski in central Finland were monitored for several years. Concentration time series are used for evaluating the environmental fate and the applicability and validity of an exposure models. Fitted elimination rates of 3,4,5-Tri-, 4,5,6-Tri-, Tetrachloroguaiacol and 2,4,6-Trichlorophenol are approx. 0.22 per day, or rather the half-lives are approx. 3 days. The elimination is most likely by biodegradation and transport-controlled. For 2,3,6-trichloro-p-cymene, fate simulations indicate significant volatilization and sedimentation. Good agreement is achieved with a one-dimensional steady-state box model, except for concentrations in fish. For a reliable assessment of environmental damage, laboratory experiments, monitoring and simulations need to be in tune.
اظهر المزيد [+] اقل [-]Observations on long-term air-soil exchange of organic contaminants.
1994
Jones K.C.
Evidence for long-term changes in the soil composition of selected organic compounds, brought about by exchanges with the atmosphere, is briefly reviewed. In the case of some compounds - such as benzo(a)pyrene and octachlorodibenzo-p-dioxin, soils may be significant long-term environmental sinks for atmospherically-derived material. In other cases - such as phenanthrene and some of the lighter PCBs, de-gassing or volatilisation from soil back to the air can occur under certain conditions. Hence the soil may act as a "short-term" sink, and a potential source to atmosphere. Indeed, for some 'semi-volatile' compounds used in large quantities in the past - such as PCBs, soil outgassing may actually be an extremely important source to contemporary air. Furthermore, soil outgassing from areas of former high use may provide an important driving mechanism for continued "global cycling" of a range of semi-volatile organochlorine compounds.
اظهر المزيد [+] اقل [-]A wind tunnel for measuring the gaseous losses of environmental chemicals from the soil/plant system under field-like conditions
1994
Stork, A. (Forschungszentrum Juelich GmbH (Germany). Inst. fuer Radioagronomie) | Witte, R. | Fuehr, F.
Volatilization from treated areas is a major source of pesticide residues in air, fog, and rain. This may lead to long-range transport of pesticide residues to remote areas. Up to now most information on pesticide volatilization has come from laboratory experiments under controlled conditions. A new system has been designed and developed to measure the volatile losses of (l4)C-labelled chemicals after application; the method compares with agricultural practice of treating soils or plants grown in lysimeters. Sensitive analytical methods guarantee a distinction between residues of unchanged pesticide, its metabolites or (14)CO2 as a mineralization product released into the air.
اظهر المزيد [+] اقل [-]Volatile hydrocarbons in and around Vienna, Austria
1990
Lanzerstorfer, C. (Technical Univ., Vienna (Austria). Inst. for Analytical Chemistry) | Puxbaum, H.