Fate of 2,3,7,8‐tetrachlorodibenzo‐P‐dioxin (TCDD) in an outdoor pond and in model aquatic ecosystems

Abstract

Environmental fate of TCDD was studied in an aquatic ecosystem, using an outdoor pond which had been dosed initially with 53.7 ppt of14C‐TCDD. The levels of radiocarbon reached an equilibrium in pondweeds after one month, in fish after two months and in the sediment after six months. Using the identical components from the outdoor pond, roughly comparable data were obtained in the laboratory for short‐term distribution of radiocarbon. The largest source of variance and discrepancy between the outdoor and the laboratory data was pondweeds. This material produced the largest shift in biomass due to rapid growth and subsequent massive death, causing a drastic change in distribution of radiocarbon in the second year in the outdoor ecosystem. The amounts of the total TCDD remaining in the pond after 12 and 25 months were 49.7 and 29.4%, respectively. The bulk of metabolites was detected in water and pondweeds.

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

“…The differences between the two studies may be attributed to the different sizes of the ponds, especially the plant compartment, as well as to different rates of transformation of the T,CDD isomers. A plant/sediment ratio of 0.5 was found by Tsushimoto et al [2], which compares with a ratio o f 0.02 in the present study. An additional factor influencing the apparent dissipation rates in sediment in the present study and in the pond used by Tsushimoto et al [2] was the deposition of plant material to which T,CDD was sorbed, especially at the end of the growing season.…”

“…For a large outdoor pond, Tsushimoto et al [2] reported that 49.7% of 2,3,7,8-T4CDD added at 53.7 ng/L was still present 1 year after the addition of the chemical, with most of the I4C present in the sediment (12.5%) and in pond weeds (87.5%). The differences between the two studies may be attributed to the different sizes of the ponds, especially the plant compartment, as well as to different rates of transformation of the T,CDD isomers.…”

“…The fate of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,CDD) in the aquatic environment has been studied in laboratory microcosms [I] and in outdoor ponds [2], but the behavior of other dioxin isomers that have entered aquatic ecosystems as trace contaminants in pesticides [3,4] or from combustion sources [5,6] has received much less attention. The 1,3,6,8-tetrachlorodibenzo-p-dioxin (1 ,3,6, isomer was identified as the major tetrachlorodioxin congener in various 2,4-D ester formulations [3], and it was also the principal T4CDD contaminant in diphenyl ether herbicides 141.…”

Advances in Microbial Ecology

“…The potential for calibrating the microcosm with the pond is apparent. Tsushimoto et al (1982) compared the fate of 2,3,7 ,8-tetrachlorodibenzop-dioxin (TCDD) in an outdoor pond (man-made) and in a 16-cm-diameter glass bottle microcosms. Data from each test system were roughly comparable for short-term distribution behavior.…”

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

“…The PCDDs and PCDFs quickly partition to particulate organic carbon and dissolved organic carbon (DOC) in the water column and sediment after entering an aquatic system [6][7][8]. The fate of PCDDs in natural waters and sediments has been more closely experimentally examined than has the fate of PCDFs [9][10][11][12] because of the toxicity of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) congener. When added to enclosures or ponds, pseudo-first-order half-lives (t ½ ) in the water column range from 0.4 [13] to 4 d [7][8][9] for various PCDD congeners.…”