Depuration Experiments Research Articles

Levels of some polybrominated diphenyl ether (PBDE) flame retardants along the Dutch coast as derived from their accumulation in SPMDs and blue mussels ( Mytilus edulis)

Aqueous concentrations of individual brominated diphenyl ethers (BDEs) were determined for five stations in the Scheldt estuary and the North Sea along the Dutch coast using passive sampling by semipermeable membrane devices (SPMDs). Values of 0.1– 5 pg l −1 were observed. The highest levels were found in the Scheldt estuary. Concentration differences between February and October were a factor of 4–8 for BDE209, and were smaller than a factor of 2 for the other BDEs. Bioaccumulation was studied for native mussels and for mussels that were transplanted from an uncontaminated area into the Scheldt estuary for 6 weeks. Concentrations in native mussels were higher by a factor of 10 and 2 for BDEs and PCBs, respectively. Field based bioaccumulation factors (BAFs) were higher for BDEs than for PCBs by a factor of 10. Depuration experiments showed that the larger part of the BDE209 content in mussels was associated with ingested particles, whereas no such effect was observed for the other BDEs or PCBs.

Toxicokinetics of waterborne bisphenol a in landlocked salmon (Salmo salar m. Sebago) eggs at various temperatures

Eye-pigmented eggs of landlocked salmon were exposed to waterborne [14C]-labeled bisphenol A at four temperatures (2, 6, 8, and 12 degrees C). Both in accumulation and depuration experiments, the eggs were exposed to a bisphenol A concentration of 1 microg/L for 196 h. In the depuration experiment, the exposed eggs were placed into clean water for 96 h. At each sampling time, the eggs were dissected into three parts (eggshell, embryo, and yolk sac), and all of these parts were weighed and analyzed separately in a liquid scintillation counter. The results show that waterborne bisphenol A accumulates in developing salmon eggs. Accumulation of bisphenol A showed a clear trend both in whole eggs and in dissected parts: the higher the temperature, the higher the uptake rate constant and the concentration of bisphenol A. Steady state was reached only in the embryos at the lowest temperature; in other cases, accumulation was linear. Depuration was significant only in the embryos at 2 and 6 degrees C. As the accumulation and the depuration results show, the elimination of bisphenol A was evidently more significant at lower temperatures.

Uptake and elimination of tributyltin in clams, Venerupis decussata

This paper considers the use of Venerupis decussata as a bioindicator of tributyltin (TBT) exposure using kinetic approaches. Clams, V. decussata, were exposed in a daily renewal protocol to different TBTCl concentrations: 0.004, 0.0814, 0.242, 0.740 and 2.47 μg L−1. The time course of accumulation in the whole soft tissues was determined for a maximum exposure period of 60 days. In 2.47 μg L−1 a steady state was reached within 30 days and in lower exposure concentrations within 40 days. Bioconcentration factors (BCF) for TBT in clams ranged between 10 000 and 40 000. TBT data during the accumulation experiments were fitted to the one-order kinetic model and kinetic parameters, uptake and depuration rate constants, were calculated. Depuration was studied in a flow through system for a period of 100 days. TBT data during the depuration experiments were fitted to both one-compartment and two-compartment models. Using a one-compartment model, half-life values for TBT were calculated and ranged between 11 and 36 days, increasing for lower concentrations.

Bioconcentration of polycyclic heteroaromatic hydrocarbons in the guppy ( Poecilia reticula)

Bioconcentration factors (BCFs) of 19 parent and hetero polycyclic aromatic hydrocarbons (PAH) were obtained from static bioconcentration experiments with Poecilia reticulata by monitoring the decrease in the initial aqueous concentration. The BCFs were obtained by fitting the observed concentrations to a one-compartment first-order kinetic model. The BCFs thus obtained showed a satisfactory linear relationship with the experimental n-octanol/water partition coefficient, log K ow ( r = 0.91, s = 0.30). By comparison with a limited number of semi-static tests, it was concluded that the static bioconcentration experiment is a satisfactory alternative for more laborious bioconcentration tests to obtain BCFs of (hetero) PAH. However, the static tests are less valuable for the acquisition of kinetic bioconcentration parameters such as, e.g., uptake or elimination rate constants. For several of the compounds in this study, the estimates resulting from the static tests did not match with those from a limited number of depuration experiments carried out in this study or with values expected from the relationship between the depuration rate constant and the log K ow, reported in the literature. The distribution of three parent PAH within the fish after a 7-day semi-static exposure was also investigated. Relatively high concentrations were found in liver and kidneys. The major part of the body burden was found in muscle and the gastro-intestinal tract.

The biokinetic behavior of 95mTc in juvenile Coho Salmon, Oncorhynchus kisutch (Walbaum)

Juvenile coho salmon, Onchorynchus kisutch, were exposed to 95mTc in both saltwater and freshwater to study the biokinetic behavior of this element in an anadromous fish. In freshwater, equilibrium whole-body concentration factors (CF 5) ranged from 28 to 32 in two separate experiments, in sharp contrast to an equilibriumCF of < 5 in saltwater. While the uptake kinetics were unimodal in saltwater, in freshwater, biomodal uptake kinetics were observed. Technetium-95m retention was biphasic in freshwater depuration experiments, an initial rapid loss of 21% to 26% of the steady-state activity with an elimination half-life of 3 to 5 days was followed by a slower loss rate, with a whole-body elimination half-life ranging from 23 to 33 days. In saltwater, retention was monophasic with an elimination half-life of 5–16 days. Dramatic decreases in 95mTc body burdens when freshwater-labeled fish are transferred to Tc-labeled saltwater indicate that the changes in physiology accompanying saltwater acclimation lead to the loss of 95mTc.

Bioconcentration of cypermethrin, deltamethrin, fenvalerate and permethrin by Chironomus tentans larvae in sediment and water

AbstractThe bioconcentration of four synthetic pyrethroid insecticides (cis‐ and trans‐cypermethrin, deltamethrin, fenvalerate and cis‐ and trans‐permethrin) by larvae of the midge Chironomus tentans was studied in sand, silt and clay sediments and water (sediment/water ratio, 1:5). Larvae were exposed for 24 h in sediment and for 48 h in water above sediment that contained 12 to 640 ng/g 14C‐labeled cypermethrin and 5 and 50 ng/g of the other compounds. Depuration of radioactivity following transfer to clean sand/water systems was monitored for 96 h. Bioconcentration factors for larvae held in sand ranged from 135 for trans‐permethrin to 316 for deltamethrin. Larvae in water above sand accumulated 5‐ to 15‐fold greater concentrations of each pyrethroid than did larvae held in water above silt or clay sediments. The lower bioavailability of each compound to larvae in water above silt and clay was attributed to greater sorption to suspended particulates and to dissolved organic carbon in these systems than in relatively particulate‐free sand/water systems. The accumulation of pyrethroids by larvae in silt and clay sediments was best accounted for by the uptake of the dissolved portion of each compound in pore water. Depuration of the four pyrethroids by Chironomus larvae was rapid, with an overall half‐life for radioactivity of 27 ± 8 h. Exposure for 24 h in sediments containing 5 ng/g concentrations of each pyrethroid had little effect on the behavior of the larvae, but at higher concentrations the animals were immobilized, although many survived following transfer to depuration experiments.

Experimental studies on the bioaccumulation of plutonium from sea water and a deep-sea sediment by clams and polychaetes

The bioavailability of 237Pu in the (III + IV) and (V + VI) oxidation states from sea water and a NE Atlantic deep-sea sediment has been studied for clams ( Venerupis decussata) and polychaete worms ( Hermione hystrix). After 22 days' exposure in sea water transfer factors (TF) had not reached equilibrium, and were 74 ± 5 and 61 ± 1 for clams and 370 ± 10 and 275 ± 11 for polychaetes, for Pu (III + IV) and Pu (V + VI) respectively. Depuration rates after sea water exposure followed a single exponential form ( T b 1 2 = 50 days ) for clams, and for polychaetes at least a two component from with T b 1 2 = 1·3 days and 54 days. TF values for 237Pu bioaccumulation from sediments were very low, 6 × 10 −3 and 5 × 10 −2 for clams and polychaetes, respectively, after 20 days' exposure. Plotonium appears to be about 50% more bioavailable to the same species than americium as measured by laboratory experiments using a similar deep-sea sediment. Depuration experiments with clams after 40 days' exposure to labelled sediment indicated loss followed a single exponential form with a T b 1 2 = 24 days . Significant differences in the behaviour of Pu introduced into the uptake and loss experiments in different oxidation states were not observed in general.

Heavy metals in Tasmanian shellfish 1 — monitoring heavy metal contamination in the Derwent estuary: Use of oysters and mussels

AbstractThe contamination of an estuary with heavy metals by a single large ore processing plant provided a unique opportunity to assess the use of mussels and oysters as indicators of heavy metal contamination. Field accumulation and depuration experiments, variation of metal content with size and prediction of water movements are described from shellfish surveys covering the Derwent River and adjacent coastal waters. Oysters were found to be suitable for monitoring zinc, cadmium, lead and copper contamination. Mussels were also suitable for monitoring zinc, cadmium and lead, but in this instance were found unsuitable for monitoring copper as the surveys indicate that copper accumulation is suppressed in mussels in a contaminated environment. The rate of accumulation and depuration of metals by oysters and mussels in field trials has been related to the anatomy of the animals and the sequestering of some metals in granulocytes. Uneven metal distribution between gonad and other tissues has been found to cause seasonal variation of heavy metals in oysters.