TBT Concentrations Research Articles

Bioconcentration and elimination of tributyltin chloride by embryos and larvae of minnows Phoxinus phoxinus

Accumulation, elimination and possible transformation of tributyltin chloride (TBT) were studied in embryos and yolk sac larvae of minnows Phoxinus phoxinus. Embryonic uptake of TBT was compared to larval uptake at aqueous TBT concentrations of nominal 8.9 μg/1. TBT, dibutyltin (DBT) and monobutyltin (MBT), were analyzed by GC-FPD in the water and in whole-body samples. Embryonic and larval uptake of TBT from water was rapid, being considerably lower in the embryonic, than in the larval phase. Whole body tissue concentrations did not reach plateaus, being 4.65 μ/g after embryonic-larval exposure for 164 h, and 4.35 μg/g after larval exposure for 96 h to 8.9 μg TBT/1. Calculated bioconcentration factors (wet wt./water) were 107 in embryos after 100 h exposure, and 538 in larvae after 96 h. Uptake and subsequent elimination were assessed after larval exposure to 4.5 μg/l. TBT concentrations in larvae reached 1.59 μg/g after 93 h exposure, and decreased to 1.48 μg/g after 75 h of depuration, indicating a slow elimination of this compound. The occurrence of only low and relatively constant concentrations of metabolites DBT and MBT indicate an absence, or an extremely slow catabolism of TBT in embryos and yolk sac larvae. These findings indicate a considerable potential of TBT for bioconcentration in fish early life stages.

Butyltin pollution in surface sediments of arcachon bay after ten years of restricted use of TBT ‐ based paints

Abstract Arcachon Bay is a site where TBT levels have been high from 1975 to 1981, but have fallen since then. It is therefore a convenient site for studies on the long term fate of butyltin pollution. Surface sediments throughout the Bay still contain all butyltin species. TBT concentration reaches up to 158 ng.g‐1 (as Sn) in marinas, but is only a few ng.g‐1 in remote areas. Amongst Butyltins, TBT predominates in marinas or mooring areas but MBT is the most abundant away from pollution sources. A general scheme of the pathways of butyltin compounds is proposed, the degradation of TBT in sediments beingmuch slower than in overlying waters.

A study of steady state and kinetic regulation of chloride ion and osmotic pressure in hemolymph of oysters,Crassostrea virginica, exposed to tri-n-butyltin

Two sets of experiments were made to determine if bis(tri-n-butyl)tin oxide (TBT) [IUPAC: hexabutyldistannoxane] influenced osmotic pressure or chloride ion concentration in hemolymph of adult American oysters, Crassostrea virginica. In the first set, oysters were acclimated to 5, 25 or 40%;, then exposed to bis(tri-n-butyl)tin oxide dissolved in seawater (0.5, 1.0 or 2.0 micrograms/L) for 11 days. Measurements of the total osmotic pressure and chloride ion concentration in hemolymph indicated that mean values of neither was significantly affected under steady state conditions. Oysters exposed to TBT exhibited a higher variation around the mean value for both total osmotic pressure and chloride ion concentration. There was significant mortality of oysters exposed to TBT in 25 and 40, but not in 5%. In a second experiment, adult oysters were acclimated to 25%, and simultaneously exposed to the TBT concentrations listed above for 10 days. Then, subgroups of oysters were abruptly moved to 5 or 40% and the time-course of adjustment of hemolymph osmotic pressure and chloride ion concentration was measured. During the first 25 hr, there was little adjustment to 5% in controls or TBT exposed oysters; apparently, they remained closed most or all of the time. In marked contrast, hemolymph of oysters moved to higher salinities rapidly readjusted. Exposure to TBT had a delaying effect on the schedule of the increase in hemolymph osmotic pressure and chloride ion concentration. Results of these experiments show that TBT has an indirect effect on osmotic pressure and chloride ion concentration adjustment in oysters; it does not appear to act strongly as an anionophore to influence anion transfer across epithelia.

Stratification and tributyltin variability in San Diego Bay

AbstractTributyltin (TBT), a biocidal antifoulant in many marine paints, was measured in near‐surface and near‐bottom water over a 25 h period at the entrance to a marina in San Diego Bay, USA. Surface water concentrations varied from 20 to 225 nanograms per liter (ng dm−3) as TBT chloride and bottom water varied from non‐detectable (<1 ng dm−3) to 77 ng dm−3. Surface water concentrations varied, with highest concentrations associated with ebbing tides, and lowest concentrations with flooding tides, indicating that the yacht basin is a source of TBT. Bottom water TBT concentrations were almost always lower than corresponding surface water concentrations. The highest bottom water concentrations were associated with flooding tides and lowest surface water TBT concentrations. Physical water column measurements indicate that vertical stratification developed during ebbing tides and dissipated during flooding tides. This accounted for maximum bottom water and minimum surface water TBT concentrations during flooding tides, due, at least in part, to vertical mixing and dilution during flood tides.

Chronic toxicity of tributyltin to Chesapeake bay biota

Chronic tributyltin toxicity experiments were conducted with the following Chesapeake Bay organisms: amphipod, Gammarus sp.; juvenile Atlantic menhaden, Brevoortia tyrannus and larval inland silverside, Menidia beryllina. TBT concentrations ranging from 29 to 579 ng L−1 did not significantly affect survival of the benthic amphipod, Gammarus sp. after 24-d exposures. The weight of Gammarus exposed to control conditions was 2.8 times greater than the weight of these test organisms exposed to 579 ng L−1 TBT. Twenty-eight day exposures to TBT concentrations of 93 and 490 ng L−1 did not significantly affect survival of juvenile B. tyrannus or larval M. beryllina. Histological examinations of B. tyrannus did not demonstrate absolute effects resulting from TBT exposure due to extensive variation between individuals. Various morphometric measurements of M. beryllina after TBT exposure did not demonstrate significant effects. However, significant reductions in growth were reported for M. beryllina at both TBT concentrations. Environmental concentrations of TBT in Chesapeake Bay and possible effects on the above biota are discussed.

Aryl hydrocarbon hydroxylase activity in a population of brown bullhead ( Ictalurus nebulosus) environmentally exposed to polycyclic hydrocarbons

Two marine flatfish species, English sole (Pleuronectes vetulus) and starry flounder (Platichthys stellatus), were exposed intermuscularly to tributyltin chloride (TBT) at 0.93 mg tin/kg body weight. The tissue concentrations of TBT and its biotransformation products dibutyltin (DBT) and monobutyltin (MBT) were monitored over a three week period. Tributyltin concentrations generally reached a maximum in all tissues by 24 h post exposure. At 24 h, the bile contained the greatest concentrations of tin, followed by the liver and kidney, and then by spleen and muscle. Total butyltins were generally present at higher concentrations in starry flounder than in English sole for all tissues, except gall bladder, at all time points. In both species the concentration of hepatic DBT increased with time. The time-point at which TBT and DBT concentrations became approximately equal was between 1 and 3 days for English sole and between 7 and 14 days for starry flounder. The ratios of hepatic TBT to DBT concentrations at all time-points from 1 to 21 days were significantly lower in English sole compared to starry flounder, suggesting more rapid biotransformation of TBT in English sole. First-order elimination rate constants for TBT in liver were 0.061 and 0.068 day−1 for English sole and starry flounder, respectively. The kidney TBT half-lives were shorter in flatfish than in rainbow trout.