title: Biocide Runoff from Building Facades: Degradation Kinetics in Soil.
abstract: Biocides are common additives in building materials. In-can and film preservatives in polymer-resin render and paint, as well as wood preservatives are used to protect facade materials from microbial spoilage. Biocides leach from the facade material with driving rain, leading to highly polluted runoff water (up to several mg L-1biocides) being infiltrated into the soil surrounding houses. In the present study the degradation rates in soil of 11 biocides used for the protection of building materials were determined in laboratory microcosms. The results show that some biocides are degraded rapidly in soil (e.g., isothiazolinones: T1/2< 10 days) while others displayed higher persistence (e.g., terbutryn, triazoles: T1/2≫ 120 days). In addition, mass balances of terbutryn and octylisothiazolinone were determined, including nine (terbutryn) and seven (octylisothiazolinone) degradation products, respectively. The terbutryn mass balance could be closed over the entire study period of 120 days and showed that relative persistent metabolites were formed, while the mass balances for octylisothiazolinone could not be closed. Octylisothiazolinone degradation products did not accumulate over time suggesting that the missing fraction was mineralized. Microtox-tests revealed that degradation products were less toxic toward the bacterium Aliivibrio fischeri than their parent compounds. Rain is mobilizing these biocides from the facades and transports them to the surrounding soils; thus, rainfall events control how often new input to the soil occurs. Time intervals between rainfall events in Northern Europe are shorter than degradation half-lives even for many rapidly degraded biocides. Consequently, residues of some biocides are likely to be continuously present due to repeated input and most biocides can be considered as "pseudo-persistent"-contaminants in this context. This was verified by (sub)urban soil screening, where concentrations of up to 0.1 μg g-1were detected for parent compounds as well as terbutryn degradation products in soils below biocide treated facades.
authors.affiliation: Department of Environmental Science, Aarhus University , Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Ulla E
authors.identifier: 0000-0001-7834-1364
authors.initials: UE
authors.lastname: Bollmann
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen , Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.|Department of Plant and Soil Science, University of Vigo , As Lagoas 1, 32004 Ourense, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Fernández-Calviño
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen , Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
authors.forename: Kristian K
authors.identifier: 0000-0001-7886-9708
authors.initials: KK
authors.lastname: Brandt
authors.affiliation: Department of Environmental Science, Aarhus University , Frederiksborgvej 399, 4000 Roskilde, Denmark.|Department of Bioscience, Zoophysiology, Aarhus University , C.F. Møllers Allé 3, 8000 Aarhus, Denmark.
authors.forename: Morten S
authors.initials: MS
authors.lastname: Storgaard
authors.affiliation: Department of Environmental Science, Aarhus University , Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Hans
authors.initials: H
authors.lastname: Sanderson
authors.affiliation: Department of Environmental Science, Aarhus University , Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Kai
authors.initials: K
authors.lastname: Bester
mesh_terms: D004202:Disinfectants / Q000737:chemistry; D007700:Kinetics; D011891:Rain; D012987:Soil; D014874:Water Pollutants, Chemical
chemical_list: D004202:Disinfectants; D012987:Soil; D014874:Water Pollutants, Chemical