Biotransformation of Tributyltin to Tin in Freshwater River-Bed Sediments Contaminated by an Organotin Release

Abstract

The largest documented release of organotin compounds to a freshwater river system in the United States occurred in early 2000 in central South Carolina. The release consisted of an unknown volume of various organotin compounds such tetrabutyltin (TTBT), tributyltin (TBT), tetraoctyltin (TTOT), and trioctyl tin (TOT) and resulted in a massive fish kill and the permanent closures of a municipal wastewater treatment plant and a local city's only drinking-water intake. Initial sampling events in 2000 and 2001 indicated that concentrations of the ecologically toxic TTBT and TBT were each greater than 10 000 microg/kg in surface-water bed sediments in depositional areas, such as lakes and beaver ponds downstream of the release. Bed-sediment samples collected between 2001 and 2003, however, revealed a substantial decrease in bed-sediment organotin concentrations and an increase in concentrations of degradation intermediate compounds. For example, in bed sediments of a representative beaver pond located about 1.6 km downstream of the release, total organotin concentrations [the sum of TTBT, TBT, and the TBT degradation intermediates dibutyltin (DBT) and monobutyltin (MBT)] decreased from 38 670 to 298 microg/kg. In Crystal Lake, a large lake about 0.4 km downstream from the beaver pond, total organotin concentrations decreased from 28 300 to less than 5 microg/kg during the same time period. Moreover, bed-sediment inorganic tin concentrations increased from pre-release levels of less than 800 to 32 700 microg/kg during this time. These field data suggest that the released organotin compounds, such as TBT, are being transformed into inorganic tin by bed-sediment microbial processes. Microcosms were created in the laboratory that contained bed sediment from the two sites and were amended with tributyltin (as tributyltin chloride) under an ambient air headspace and sacrificially analyzed periodically for TBT, the biodegradation intermediates DBT and MBT, and tin. TBT concentrations decreased faster [half-life (t1/2) = 28 d] in the organic-rich sediments (21.5%) that characterized the beaver pond as compared to the slower (t1/2 = 78 d) degradation rate in the sandy, organic-poor, sediments (0.43%) of Crystal Lake. Moreover, the concentration of inorganic tin increased in microcosms containing bed sediments from both locations. These field and laboratory results suggest that biotransformation of the released organotins, in particular the ecologically detrimental TBT, does occur in this fresh surface-water system impacted with high concentrations of neat organotin compounds.

Organotin contamination in South American coastal areas

“…Organotin residues were recently detected in sediments from several areas associated with ship traffic in Europe (Chiavarini et al 2003a;Nogueira et al 2003;Díez et al 2002Díez et al , 2006, Asia (Harino et al 2007;Nhan et al 2005), Oceania (Haynes and Loong 2002), and North America (Landmeyer et al 2004). In South America, ten studies determined organotins in sediments from 25 different sites associated to maritime activities ( Fig.…”

Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products

“…Nevertheless the debutylation mechanism could be considered according to reported studies (Landmeyer et al 2004;Escalante et al 2009), as shown in Fig. 2.…”

“…DBT concentration increases during incubation, reaching around 30 % of the original TBT concentration (1.5 mM). No MBT was The degradation rate constants (k) were calculated following pseudo-first order kinetics after 7 days of incubation (Stasinakis et al 2005;Brandsch et al 2001;Landmeyer et al 2004). The degradation rate constant (k) was 0.022 [day -1 ] and TBT half-life (t 1/2 ) in culture was 4.3 days.…”

The management of the effects of navigation on the marine environment: the case of tributyltin (TBT)

“…In the marine environment, TBT soon abandoned the water column for sediment, the water distribution coefficient sediment (log 10 K oc ) is in the range 4.2-5.0 [4] given that the TBT molecule has a high specific mass, ∼ kg·L −1 at 20 • C [5], low solubility, <10 mg·L −1 at 20 • C and pH 7.0 [6] and the octanol/water distribution coefficient (log K ow ) is of ∼4.4 at pH 8 [7]. The result of this is that TBT's presence in water is extremely variable and is linked to the existence of active sources of contamination, whereas its duration in sediments is remarkably long.…”