RC - What is RC? - Rotterdam Convention

outdoors. This relatively short disappearance time was possibly due
to heterogeneous reactions on the vessel walls, as suggested by the
authors of the report. Hydrogen chloride was found to be the main
degradation product after exposure of samples to xenon arc
radiations (wavelength > 290 nm) (Pearson & McConnell, 1975).
4.2.3 Hydrolysis
Hexachlorobutadiene is highly resistant to chemical
degradation
by strong acids and alkalis in the absence of appropriate solvents,
although it is readily degraded by ethanolic alkali (Roedig &
Bernemann, 1956). Based on the measured hydrolysis rate of the
compound in a 1:1 acetone-water mixture, a half-life of over 1800 h
was calculated (Hermens et al., 1985).
was
and
4.3 Biodegradation
Hexachlorobutadiene, at concentrations of 5 or 10 mg/litre,
completely degraded by adapted aerobic microorganisms within 7 days
in a static-culture flask screening procedure at 25 °C, as shown by
gas chromatography and by determination of total and dissolved
organic carbon. The inoculum was taken from settled domestic waste
water (Tabak et al., 1981). Approximately 70% adsorption to sludge
and 10% degradation was found to occur within 8 days in a pilot
low-loaded biological sewage treatment plant (Schröder, 1987).
Anaerobic degradation of hexachlorobutadiene at 100 mg/litre
was not observed in 48-h batch assays at 37 °C using an inoculum
from a laboratory digester (Johnson & Young, 1983).
4.4 Bioaccumulation
Considering the low water solubility of 3.2 mg/litre and the
high log Kow of 4.78-4.90 (Table 1), a strong bioaccumulating
potential would be expected. Both laboratory and field data support
this prediction. In flow-through laboratory tests with algae,
crustaceans, molluscs and fish in fresh or marine waters,
bioconcentration factors (on a wet weight basis) were between 71
17 000. The results appear to be highly dependent on the exposure
period and there is great variability between organisms (Leeuwangh
et al., 1975; Pearson & McConnell, 1975; Laseter et al., 1976;
Oliver & Niimi, 1983). Steady state was clearly demonstrated to be
reached in only one of these tests. Oliver & Niimi (1983) exposed
rainbow trout (Salmo gairdnerii) to aqueous solutions of
hexachlorobutadiene at 0.10 and 3.4 ng/litre and found average
bioconcentration factors of 5800 and 17 000, steady states having
been reached after 69 and 7 days, respectively. When Oligochaete
worms were exposed via spiked Lake Ontario sediments to a pore
water
concentration of 32 ng/litre in a flow-through system, steady state
was reached within 4 to 11 days and the average bioconcentration
factor was 29 000, based on dry weight of which about 8% is lipid
(Oliver, 1987). Biomagnifi-cation, the concentrating of a substance