HEAVY METAL POLLUTION RECORDED IN THE SEDIMENTS OF KOUMOUNDOUROU LAKE, GREECE

HEAVY METAL POLLUTION RECORDED IN THE SEDIMENTS
OF KOUMOUNDOUROU LAKE, GREECE
ARISTOMENIS P. KARAGEORGIS
Hellenic Centre for Marine Research, Institute of Oceanography, 46.7 km Athens-Sounio
Avenue, 19013 Anavyssos, Greece.
[email protected]
Keywords: sediment, pollution, heavy metals, enrichment factor, Koumoundourou Lake, Greece
ABSTRACT
Lake Koumoundourou is a shallow (maximum depth 2.3 m) lake located ~11 km NW
of Athens. It communicates through a narrow weir with the Elefsis Bay. This study focuses
on the geochemistry of surface (25 samples) and core (14 samples) sediments recovered
from the lake and two coastal marine sediments. The sediments were analyzed for their
grain-size properties, organic carbon, as well as major and minor elements using standard
analytical techniques. The surface sediments of the lake are rich in sand, which is of
biogenic origin and it is composed by shells and their fragments, resulting in a mean
carbonate content of 70.7 wt%. The organic carbon content is between 2.04 and 7.50 wt%,
indicating anthropogenic inputs and/or temporary anoxic conditions in the lake. Heavy
metal and metalloid levels (V, Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Pb) appear to be low, when
compared (as absolute values) directly to other polluted lake, river, and marine sediments
from Greece. However, in our study we calculated enrichment factors (EFs) taking as a
reference sediment a pre-industrial core sample from the neighboring Saronikos Gulf. The
calculated EFs revealed that the surface sediments of the lake have been substantially
contaminated by heavy metals and metalloids in the order V, Mn, Ni, Co, Cr, Cu, Pb, Zn,
As, Mo. Vanadium exhibited the lowest EF (1.73) and Mo the highest (19.9). Similar
results were obtained when EFs were calculated using the ‘average shale’ as a reference
unpolluted sediment. Core sediments were characterized by high EFs for the same
elements.