Kp. Suominen et al., SEDIMENT ACCUMULATION OF ORGANIC HALOGENS IN PRISTINE FOREST LAKES, Environmental science and pollution research international, 4(1), 1997, pp. 21-30
Sediment accumulation of organic halogen was studied in two forest lak
es, one pristine and one which received 30 m(3) of biologically purifi
ed bleaching wastewater from a kraft pulp mill in 1979 equivalent to c
a. 2 kg of adsorbable organic halogen (AOX). Lake sediments were dated
with Pb-210, Cs-134 and Cs-137 and the annual deposition rates of org
anic halogens and organic matter were calculated. Organic bound haloge
n contents of the sediment aged 150 years was 180 mu g Cl g(-1) d.w. i
n both lakes. The concentration of organic bound halogen at the topmos
t 6 cm of the sediments (less than 20-years-old) ranged from 45 to 80
mu g Cl g(-1) d.w. This suggests that solvent extractable halogen had
enriched in the older sediment layers. The deposition of extractable o
rganic halogen (EOX) in the lakes in 1950's was 4 to 5 mg Cl m(-2) a(-
1). Since then, the deposition of EOX doubled in both lakes. The depos
ition of organic matter increased concomitantly from 50 g to 110 g m(-
2) a(-1) in Lake Mustalampi and from 35 g m a(-1) to 62 g m(-2) a(-1)
in Lake Pyylampi suggesting that the increase in the deposition of org
anic halogen followed the increase in the deposition of organic matter
. Of the 2 kg of organic halogen discharged into the lake, 5 % or less
was detected in the sediment in tetrahydrofuran extractable form 15 y
ears later.