Within a case study 'Ecobalance', the fate and effects of various chlo
rinated and non-chlorinated organic compounds and some heavy metals di
scharged from pulp and paper mills into water, sediment and aquatic an
imals were studied in a recipient area of southern Lake Saimaa, SE Fin
land. The main aim of the project was to find an empirical link betwee
n chemical emission parameters and ecotoxicological effects expressed
in the ecosystem. As part of the 'Ecobalance' project, principal compo
nent analysis (PCA) and partial least squares (PLS) methods were used
to interpret the data of the lake area. The PLS method was used to est
imate the lake area affected by mill effluents and to calculate the fr
action of wastewater in sampling sites. The study area is mainly affec
ted by one pollution source. There is, however, also another pollution
source, another pulp mill located near the research area. The effect
of this source can be seen in the sites near the outer margin of the a
rea. The effect of the major source effluents can be clearly seen in t
he data of exposed animals and sediment samples. (C) 1996 by John Wile
y & Sons, Ltd.