title: Dynamics of biocide emissions from buildings in a suburban stormwater catchment - concentrations, mass loads and emission processes.
abstract: Biocides such as isothiazolinones, carbamates, triazines, phenylureas, azoles and others are used to protect the surfaces of buildings, e.g. painted or unpainted render or wood. These biocides can be mobilized from the materials if rainwater gets into contact with these buildings. Hence, these biocides will be found in rainwater runoff (stormwater) from buildings that is traditionally managed as "clean water" in stormwater sewer systems and often directly discharged into surface waters without further treatment. By means of a 9 month event-based high resolution sampling campaign the biocide emissions in a small suburban stormwater catchment were analysed and the emission dynamics throughout the single rain events were investigated. Five out of twelve of the rain events (peak events) proved significantly higher concentrations than the rest (average) for at least one compound. Highest median concentrations of 0.045 and 0.052 μg L(-1) were found for terbutryn and carbendazim, while the concentrations for isoproturon, diuron, N-octylisothiazolinone, benzoisothiazolinone, cybutryn, propiconazole, tebuconazole, and mecoprop were one order of magnitude lower. However, during the peak events the concentrations reached up to 1.8 and 0.3 μg L(-1) for terbutryn and carbendazim, respectively. Emissions of an averaged single family house into the stormwater sewer turned out to be 59 and 50 μg event(-1) house(-1) terbutryn and carbendazim, respectively. Emissions for the other biocides ranged from 0.1 to 11 μg event(-1) house(-1). Mass load analysis revealed that peak events contributed in single events as much to the emissions as 11 average events. However, the mass loads were highly dependent on the amounts of rainwater, i.e. the hydraulic flow in the receiving sewer pipe. The analysis of the emission dynamics showed first flush emissions only for single parameters in three events out of twelve. Generally biocides seemed to be introduced into the stormwater system rather continuously during the respective events than in the beginning of them. Mass flows during the events did correlate to driving rain, whereas mass loads neither correlated to the length or the intensity of rainfall nor the length of dry period.
authors.affiliation: Aarhus University, Department of Environmental Science, Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Ulla E
authors.initials: UE
authors.lastname: Bollmann
authors.affiliation: Aalborg University, Department of Civil Engineering, Sohngaardsholmsvej 57, 9000 Aalborg, Denmark.
authors.forename: Jes
authors.initials: J
authors.lastname: Vollertsen
authors.affiliation: Empa, Laboratory for Building Science and Technology, Ueberlandsstrasse 129, CH-8600 Duebendorf, Switzerland.
authors.forename: Jan
authors.initials: J
authors.lastname: Carmeliet
authors.affiliation: Aarhus University, Department of Environmental Science, Frederiksborgvej 399, 4000 Roskilde, Denmark. Electronic address: kb@dmu.dk.
authors.forename: Kai
authors.initials: K
authors.lastname: Bester
mesh_terms: D004202:Disinfectants / Q000737:chemistry*; D004784:Environmental Monitoring; D005740:Gases; D006798:Housing; D015394:Molecular Structure; D014867:Water / Q000737:chemistry; D014872:Water Movements; D014874:Water Pollutants, Chemical
chemical_list: D004202:Disinfectants; D005740:Gases; D014874:Water Pollutants, Chemical; D014867:Water
keywords: Biocides; Carbendazim; Façade coatings; Separated sewer; Terbutryn