Fate of 1,3,6,8-tetrachlorodibenzo-p-dioxin in an outdoor aquatic system

Abstract

Three outdoor pools (5.5 m3) were treated with [14C]1,3,6,8‐tetrachloridibenzo‐p‐dioxin (1,3,6,8‐T4CDD) at concentrations of 98, 245 and 980 ng/L, and the movements and accumulation of the compound were monitored in air, water, sediment and vegetation over a 426‐d period. The concentrations of 1,3,6,8‐T4CDD in the air above the treated pools ranged from 8.4 to 18.8 ng/m3 during the first day after treatment. Total 14C concentration in the water column declined rapidly, with more than 90% lost from the water phase within 96 h (t1/2 = 14.0 to 28.5 h). The sediments were the major reservoir for the compound, accounting for 34 to 80% of the added compound at 34 d and 5 to 14% at 426 d. Total [14C]T4CDD concentrations in the sediments increased at 90 d, in part because of the end‐of‐season deposition of rooted vegetation. 1,3,6,8‐T4CDD degraded in natural water in Pyrex flasks at similar rates in sterile and nonsterile waters (t1/2 = 6.3 to 8.0 d) in sunlight, but not under darkened conditions. A single, polar photodegradation product (retention time 0.82 relative to 1,3,6,8‐T4CDD) was detected by HPLC, and 20% of the 14C was unextractable within 10 d. Similar degradation products were noted in the water and sediments (90 and 426 d). In duckweed (Lemna sp.) and (Potamogeton sp.), concentration factors for 1,3,6,8‐T4CDD ranged from 2.5 to 3.4 × 104 and from 0.27 to 2.0 × 105, respectively. At 426 d posttreatment, 5 to 8% of the applied 1,3,6,8‐T4CDD could be accounted for in all aquatic compartments, with an additional 4 to 6% of 14C present as unidentified polar products and unextractable residue.

Polychlorinated dioxins and furans in sediments at a site colonized byDreissenain western lake Ontario, Canada

“…The lesser chlorinated PCDDs/PCDFs generally have higher vapor pressures and lower log K ow values but are more susceptible to biological or chemical degradation than the higher‐chlorinated isomers [24,28]. The results of some studies show that freely dissolved PCDDs/PCDFs have short residency times in the aqueous phase and are rapidly partitioned to suspended particulates and dissolved organic material in the water column [29,30]. Servos et al [30] reported half‐lives in the aqueous phase of 2.6 d for 2,3,7,8‐tetraCDD and 4.0 d for octaCDD in a study using lake enclosures.…”

Long‐term fate and bioavailability of sediment‐associated 2,3,7,8‐tetrachlorodibenzofuran in littoral enclosures

“…The half‐life of TCDF in the water column (1.7 to 1.9 d) was similar to those calculated by Servos et al [7] and Corbet etal. [11] for 1,3,6,8‐TCDD (2.6 and 0.6 to 1.2 d, respectively). Both TCDF and 1,3,6,8‐TCDD are hydrophobic, their log K ow s are relatively high (6.5 [29] and 7.1 [30]), and, consequently, they are mainly associated with particles.…”

Mobility and Profiles of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Sediment of Ya-Er Lake, China

“…Czuczwa and Hites (1986) found that the homologue profiles in the atmosphere and in lake sediments showed a significant enhancement of OCDD relative to all other homologues. In general, PCDF photodegrade much more rapidly than PCDD, and photolytic half-lives increase with increasing level of chlorination for both PCDD and PCDF (Corbet and Webster, 1998;Dobbs and Grant, 1979;Choudhry and Hutzinger, 1982). PCDD/Fs atmospheric degradation in vapor-phase has been suggested to explain the differences between the PCDD/Fs homologue profiles of sources and environmental sinks (Orth et al, 1990;Koester and Hites, 1992).…”

“…PCDD/Fs are highly persistent to chemical transformations and exhibit low biological degradation and high accumulation in biota (Fletcher and Mckay, 1993;Bonn, 1998;Corbet and Webster, 1998). Lake sediments seem to preserve the environmental impact of PCDD/Fs.…”