Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

• Published in: Journal of hazardous materials 2016-04, Vol.307, p.263-273
• Main Authors: Furdek, Martina, Mikac, Nevenka, Bueno, Maite, Tessier, Emmanuel, Cavalheiro, Joana, Monperrus, Mathilde
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Constraining; Contamination; Degradation; Degradation kinetics; Desorption; Grain size; Isotopically enriched tracers; Marine; Organic matter; Organotin compounds; Sediments; Tracers; Tributyltin
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.12.037

[Display omitted] •Limiting step in OTC degradation in sediments is their desorption into porewater.•TBT persistence in contaminated sediments increases in sediments rich in organic matter.•DBT does not accumulate in sediments as degradation product of TBT.•TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days.•PhTs degradation is slower than BuTs degradation in oxic porewaters. This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9±0.1 and 9.1±0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.