ORGANIC HALOGEN, HEAVY-METALS AND BIOLOGICAL-ACTIVITIES IN PRISTINE AND PULP-MILL RECIPIENT LAKE-SEDIMENTS

In order to create a basis for prognosing future intrinsic remediation potential of past pollution by pulping industry, we analyzed biochemi cal activities and levels of pollution in sediments dated with Pb-210 and Cs-137. A small pristine forest lake and a pulp mill recipient are a of a large oligotrophic Lake Saimaa were test sites. Sediment concen tration of EOX ranged from 40 to 130 mu g Cl (g d.w.)(-1) in the prist ine lake and from 770 to 4700 mu g Cl (g d.w.)(-1) in the pulp mill re cipient area and the C:Cl (w/w) ratio of sediment organic matter range d from 2000 to 5100 and 42 to 230, respectively. The organic matter in 10 to 20 years old pulp mill recipient sediment was mainly of waste w ater origin. The activity gradients of beta-glucosidase, butyrate-este rase, methane oxidation potential and endogenous respiration from surf ace to deeper layers were less steep in polluted than in pristine sedi ment. Methane oxidation potential was 120 mu mol CH(4)d(-1) (g C)-1 at the sediment surface of pristine lake sediment and 26 mu mol CH(4)d(- 1) (g C)-1 at the polluted site, endogenous respiration rates of the s urface sediment were 670 and 310 mu mol CO(2)d(-1) (g C)(-1), respecti vely. In the most polluted layer we found a depressed potential for me thane oxidation, inhibition of phosphatase and butyrate-lipase activit ies and moderately increased induction ratio of beta-galactosidase to phosphatase in the SOS-Chromotest strain E. coli PQ 37. The results su ggest that at the concentrations observed these effects in the sedimen t were not due to heavy metals. (C) 1998 IAWQ. Published by Elsevier S cience Ltd.