Chemistry Reference
In-Depth Information
Table 1:
Summarising characteristics and nomenclature for sea slicks and crude
oil spills.
Sea Slicks
Crude Oil Spills
Chemical constituents
surface-active substan-
ces
consisting of a
hy-
drophilic
head group and
a
hydrophobic
tail
alkanes, cycloalkanes
and aromatics with
pref-
erentially hydrophobic
character, no hydrophilic
head group
Distribution at the
water surface
a.) substances
spread
on
the water surface;
b.) substances
are being
spread
on the water sur-
face
c.) a sea slick
is gene-
rated (or produced)
at
the sea surface
a.) crude oil
is spilled
at
the sea surface
b.) a crude oil spill
is
generated (or produced)
at the sea surface
Thicknesses
monomolecular
, typi-
cally 2.4 - 2.7 nm
(2.4 x 10
-9
- 2.7 x 10
-9
m)
thicker layers, typically
Pm-range until mm-
range, if freshly spilled
even cm-range (in con-
nection with accidents)
Origin
both biogenic (secreted
by plankton or fish) and
man-made
nearly in all cases man-
made, in few cases oil
seeps (e.g., Gulf of Mex-
ico)
Water wave damping
mechanisms
resonance-type wave
damping in the short-
gravity-wave region,
(
Marangoni damping
)
damping by an inter-
facial layer of higher
viscosity
Microbial or photo-
chemical transforma-
tion of constituents
relatively fast: time scale
hours or few days (
soluble, highly polar
substances that disappear
in the bulk water)
very slow: several
months (
weathered
oil spills
formation of
surface active com-
pounds
slick
forma-
tion around thick spill
centres)
5.1. Generation of crude oil spills
Several drawbacks related to the generation of crude oil spills on the sea
surface have to be taken into account. While the spreading of artificial, but
quasi-biogenic, sea slicks such as oleyl alcohol slicks is absolute harmless
as they are part of natural processes at the sea surface, the spilling of crude
