(Fwd) PCBs from Pulp Bleaching & Trends in PCDD/Fs & PCBs in S

["Pat Costner" <pat.costner@dialb.greenpeace.org>]

 In the paper cited below, trends in concentrations of dioxins and 
furans and PCBs in lake sediment core samples from Kamloops Lake in 
British Columbia, Canada, are reported.  The core samples ranged in 
age from 1878 through 1994.  In general, the concentrations of the 
dioxins and furans were low (e.g., 0.1 ppt for 2378-TCDD) and began 
increasing in the early 1940s.   PCB concentrations in the oldest 
sediment were somewhat higher and begin increasing during the 
1930-40s.  

 Concentrations of the dioxins and furans showed a rapid increase 
following construction of  Weyerhauser pulp and paper mill in 1965.  
For most dioxins, concentrations began a rapid decline in the late 
1980s, coinciding with the conversion from 30% to 10% chlorine 
dioxide.   In the latest sediment samples, 1993-4, the levels of all 
of the dioxins are higher than those of the late 1800s.  For example, 
in the most recently deposited sediment, 2378-TCDD is 9 times higher 
and 2378-TCDF is 246 times higher than in the earliest sediment, 
although some of the penta- and hexa-, 2,3,7,8-substituted dioxins 
and furans are only two to six times higher.  

 Besides the pulp mill's estimated contribution of 5-9 grams per year 
of 2378-TCDF, the authors suggest that resuspension of older river 
and lake sediments also account for a substantial portion of this 
chemical in recently-deposited sediment.  In the mid- to late 1980s, 
the mill may have been releasing as much as 600 g/yr of 2378-TCDF.

 Three of the PCBs -- CB13, CB15 and CB 37 --  followed the same 
pattern as the dioxins and furans, suggesting that these compounds 
are produced during bleaching of pulp with chlorine.  This is 
apparently the first report of such findings.


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Robie W. Macdonald, Michael G. Ikonomou, and David W. 
Paton.  Historical Inputs of PCDDs, PCDFs, and PCBs to a British 
Columbia Interior Lake: The Effect of Environmental Controls on Pulp 
Mill Emissions. Environ. Sci. Technol., 32 (3), 331 -337, 1998.  
 


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Pat Costner
P.O. Box 548, or 512 CR 2663
Eureka Springs, Arkansas 72632 USA
ph:  501-253-8440
fx:  501-253-5540
em:  pat.costner@dialb.greenpeace.org
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