Biocide runoff from building facades: degradation kinetics in soil

TY - JOUR

T1 - Biocide runoff from building facades

T2 - degradation kinetics in soil

AU - Bollmann, Ulla E.

AU - Fernandez Calviño, David

AU - Brandt, Kristian Koefoed

AU - Storgaard, Morten S.

AU - Sanderson, Hans

AU - Bester, Kai

PY - 2017/4/4

Y1 - 2017/4/4

N2 - 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-1 biocides) 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-1 were detected for parent compounds as well as terbutryn degradation products in soils below biocide treated facades.

AB - 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-1 biocides) 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-1 were detected for parent compounds as well as terbutryn degradation products in soils below biocide treated facades.

KW - Disinfectants

KW - Kinetics

KW - Rain

KW - Soil

KW - Water Pollutants, Chemical

KW - Journal Article

U2 - 10.1021/acs.est.6b05512

DO - 10.1021/acs.est.6b05512

M3 - Journal article

C2 - 28287716

SN - 0013-936X

VL - 51

SP - 3694

EP - 3702

JO - Environmental Science & Technology

JF - Environmental Science & Technology

IS - 7

ER -