Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 424920
Title Transport and biodegradation of volatile organic compounds : influence on vapor intrusion into buildings
Author(s) Picone, S.
Source Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Tim Grotenhuis; P.F.M. van Gaans. - S.l. : s.n. - ISBN 9789461732767 - 149
Department(s) Environmental Technology
WIMEK
Publication type Dissertation, internally prepared
Publication year 2012
Keyword(s) vluchtige verbindingen - organische verbindingen - biodegradatie - biochemisch transport - gebouwen - grondwaterverontreiniging - binnenklimaat - volatile compounds - organic compounds - biodegradation - biochemical transport - buildings - groundwater pollution - indoor climate
Categories Environmental Pollution
Abstract

Vapor intrusion occurs when volatile subsurface contaminants, migrating from the saturated zone through the unsaturated zone, accumulate in buildings. It is often the most relevant pathway for human health risks at contaminated sites, especially in urban areas; yet its assessment is controversial. Field assessment of vapor intrusion risk is complicated by two interrelated main factors that are controlled by the contaminant’s properties: transport processes in the unsaturated zone and biodegradation in the unsaturated zone. Commonly available vapor intrusion models either overlook significant properties at the field scale or, conversely, are too complex to be applicable at this scale. Specifically, moisture variation, liquid diffusion, dynamic processes such as water table variations, and biodegradation are not adequately accounted for. As a result, the soil gas and indoor air concentrations predicted by existing models frequently overestimate measured concentrations by several orders of magnitude.
This thesis addressed transport and biodegradation processes of volatile organic compounds, focusing on aerobic unsaturated zones. The main aims were to i) characterize significant transport processes influencing vapor intrusion and ii) quantify and mechanistically describe biodegradation in unsaturated soils. Field experience, numerical modeling and laboratory experiments with toluene and vinyl chloride as reference compounds were combined to separate out the relevant processes influencing vapor intrusion.
The main conclusions from this thesis indicate that soil moisture variations and aerobic biodegradation are crucial aspects to be jointly considered for the assessment of vapor intrusion. These may contribute to a significant reduction in the risk associated with dissolved volatile organic contaminants. Specific and relevant implications for modeling and monitoring vapor intrusion can be derived. With respect to vapor intrusion modeling, when including unsaturated zone biodegradation, the use of liquid phase biodegradation rates as derived from liquid mixed batches may underestimate by several orders of magnitude the liquid degradation rates in the unsaturated system. Therefore, biodegradation rates derived from unsaturated system appear more appropriate. With respect to monitoring, vertical soil moisture variations and contaminant/oxygen concentration profiles need to be measured in the field, in order to account for the above processes.

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