Bleached kraft pulp mill discharged organic matter in recipient lake sediment

Abstract

Environmental properties of organic matter contained halogen and sulfur were studied in sediments of bleached kraft pulp mill effluent (BKME) recipient lakes and 2 m(3) outdoor enclosures (mesocosms). The BKME contributed to 1% (v/v) of the total water flow in the lake downstream of the pulp mill where the sediments contained 1.7 to 4 mg of tetrahydrofuran extractable organic halogen (EOX-Cl) and 0.6 to 0.8 mg of tetrahydrofuran extractable organic sulfur (EOS-S) g(-1) of organic matter. Upstream sediment contained 0.03 mg of EOXCl and 0.7 mg of EOS-S g(-1) of organic matter. EOX was a better indicator for the influence of BKME in the recipient sediment than EOS. The polarity of BKME contained EOX corresponded to log K(ow) of < 1, and that of the downstream sediment contained EOX to > 4.5. HP-SEC analysis of the molecular weight distribution (MWD) of the EOX showed a peak between 300 to 600 g mol(-1) for the BKME and between 1000 to 2000 g mol(-1) for the downstream sediment. The MWD of the BKME contained EOS peaked at 300 to 1000 g mol(-1), and that of the downstream sediment contained EOS at 1000 to 5000 g mol(-1). These results indicate that BKME contained organic halogen and sulfur undergo major structural transformations when incorporated into sediment. The biota-to-sediment accumulation factor (BSAF) of EOX from sediments formed downstream of the mill and in the mesocosms to the lipids of Lumbriculus variegatus was 0.4 to 0.7. This is of a similar order of magnitude to the BSAF reported for 2,3,7,8-tetrachlorodibenzop-dioxin and 2,3,7,8-tetrachlorodibenzofuran.