This title appears in the Scientific Report :
2003
Please use the identifier:
http://hdl.handle.net/2128/152 in citations.
Umweltverhalten von MTBE nach Grundwasserkontamination
Umweltverhalten von MTBE nach Grundwasserkontamination
Since the late seventies, methyl-tert-butyl ether (MTBE) has become one of the mort widely produced chemicals in Europe and the USA due to its use as a fuel additive. MTBE was first used as a substitute for the environmental poison tetraethyl lead because of its anti-knock properties. Statutory requ...
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Personal Name(s): | Linnemann, Volker (Corresponding author) |
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Contributing Institute: |
Agrosphäre; ICG-IV |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2003
|
Dissertation Note: |
Universität Bonn, Diss., 2002 |
ISBN: |
3-89336-339-4 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Chemie und Dynamik der Geo-Biosphäre |
Series Title: |
Schriften des Forschungszentrums Jülich. Reihe Umwelt / Environment
40 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
Since the late seventies, methyl-tert-butyl ether (MTBE) has become one of the mort widely produced chemicals in Europe and the USA due to its use as a fuel additive. MTBE was first used as a substitute for the environmental poison tetraethyl lead because of its anti-knock properties. Statutory requirements for minimum volumes of oxygen-containing additives in motor fuels, to protect the atmosphere against the cl imate-relevant trace gases carbon monoxide (CO) and ozone (Os), greatly increased the demand for MTBE in the USA. One consequence was an increasing number of groundwater and soil contaminations as well as complaints of damage to health associated with MTBE. Since the air had been kept clean at the expense of the groundwater and the soil, the use of MTBE is prohibited in the USA after 2003. In Europe increased numbers of MTBE-contaminations in the groundwater and surface waters have been reported. Goal of this PhD thesis was the investigation of the MTBE mass transport into the atmosphere after a contamination of the groundwater. For this studies a tripartite experimental concept was selected: First of all, a soil column experimental setup for studying mass transport in undisturbed soil monoliths was designed, constructed and validated. With this facility it was possible to create under defined and reproducible experimental conditions an aquifer below the soilcore, variable in height, in which a contamination with MTBE had been simulated in a real concentration range of 100 to 200 mg L$^{-1}$. A stream of air flowed over the soil surface through the artificial atmosphere, and was collected and analysed with respect to the composition of volatile organic chemicals. Adsorption onto multibed solid adsorbent material with subsequent thermodesorption GC/MS analysis was developed for air collection and displayed good sampling performance with excellent detection limits. The groundwater samples were analysed by radioactivity-HPLC, -GPC or a new direct injection- GC/MS analytical technique. For this liquid-injection-methods the detection limit still has to be improved. In the first experiment, up to 47 ppb (170 ng m$^{-3}$) of MTBE was detected in the air. MTBE was not continuously recovered in the air but only occurred in pulses. Maximum values were measured, in particular, in the first few days. The mass transfer rates through the soil into the atmosphere were in the region of 1.94 ± 1.88 $\mu$g m$^{-2}$ h$^{-1}$ in the first experiment with an equilibrium value of approx . 0.45 ± 0.02 $\mu$g m$^{-2}$ h$^{-1}$. In the second experiment with [$\alpha$,$\alpha$'-$^{14}$M] MTBE, only low volatilization was measurable. At the same time, the water balance in the experimental System was also recorded, which enabled a qualitative relation to the MTBE loss to be established. The simulated aquifer was redesigned for a scale-up experiment and also the air sampler adapted for volatile hydrocarbons at the fieldlike wind tunnel with a lysimeter. The new sampling unit was validated in several preliminary experiments and displayed good collecting efficiency for the high volume flows applied. Analogously to the second column experiment, over an experimental period of 4 weeks hardly any mass transport of MTBE through the soil was determined. The recovery rate in both experiments with $^{14}$C-MTBE was in the region of 83 to 102 % of the applied radioactivity (AR). As described in the literature only slight adsorption to the soil particles was found for MTBE. Since the soil columns and the lysimeter represented a compartment of the ecosystem with functioning microflora, the microbial aerobic degradation in the soil was determined in two laboratory studies. A maximum mineralization of 1.6 % AR was detected as a function of the previous contaminations of the soil and the soil type. Moreover, rapid volatilization of the MTBE from the surface took place perceptibly reducing the bioavailability . The results obtained were readily applicable to the transport studies. |