Distribution of Persistent Organic Pollutants and Mercury in Freshwater Ecosystems Under Changing Climate Conditions - Climate Change Impacts on Freshwater Ecosystems - page 188

Lakes in the Pyrenees

PCB 101 PCB 118 PCB 138 PCB 153 PCB 180

1 10 10 10

10

0.1 1 1

1

0.01 0.1 1

0.1

281 276

BDE 47

272 281 276 272 281 276 272

281 276 272 281 276 272

BDE 99 BDE 100 BDE 153 BDE 154

1 1 1 1 1

0.1 0.1 0.1

0.1 0.01 0.01

0.1 0.01

281 276 272 276

281 276 272 281 272 281 276 272 281 276 272

Temperature (K)

Lakes in the Tatras

PCB 101 PCB 118 PCB 138 PCB 153 PCB 180

10 10 10 10

10

1 1 1

1

1 0.1 0.1

0.1 0.1

276 272 276 272 276 272 276 272

276 272

BDE 47 BDE 99 BDE 100 BDE 153 BDE 154

0.1

1 1

0.1 0.1

0.1 0.1

0.01 0.01 0.01

0.01 0.01

276 272 276 272 276 272 276 272 276 272

Temperature (K)

Figure 8.2 Temperature dependence of the concentrations of various congeners of
PCBs and PBDEs in fish. There is a correlation between the accumulation of high
molecular weight PCBs and temperature in both cases but only in the Pyrenees for
PBDEs. (Based on Gallego et al . 2007.)

in Lake Redon (Pyrenees). OCs with an octanol-water partition coefficient ( K ow )
higher than 10 6 showed lower concentrations in food than expected from
theoretical octanol-water partition (Fig. 8.4), indicating that the distribution of
these compounds does not reach equilibrium within the life span of the food web
organisms (c.1 year). On the other hand, the degree of biomagnification in fish
increased with K ow , except in the case of the largest compound analysed, PCB
180, which contains seven chlorine substituents.
Examination of OC exchange at fish gill and gut using a fugacity model
(expressing transfer of compounds between compartments) based on the water,
food and fish concentrations showed a net gill loss and a net gut uptake for all
compounds (Fig. 8.5). A pseudo-stationary state was only achieved for compounds
with log( K ow ) < 6. Calculation of average residence times for OCs in fish in apparent
steady state gave values of days to a few weeks for HCHs, 1 year for HCB and 4,4´-
DDE and 2-3 years for 4,4'´-DDT, PCB 28 and PCB 52. Residence times longer
than one decade were found for the more chlorinated PCB (Catalan et al . 2004).
The OC concentrations in aquatic insects change depending on the life-history
stage. Increasing concentrations of OCs and PBDEs from larvae to pupae, indepen-
dent of physico-chemical properties, has been observed. These concentration
increases may result from the weight loss of pupae during metamorphosis as a