368
R. Crema et aI.
developed in the northern Adriatic Sea. As part
of a research program aimed to investigate on
the effects of this activity, the "history" of a platform was studied by means of several field surveys; these were carried out over a long period,
beginning immediately prior to the installation
of the platform and extending up to 8 years after,
when all platform activity had terminated.
The platform is located off the city of
Ravenna, on muddy bottoms of about 15 m
depth. Data utilized in this paper pertain to surveys performed at the start and the end of the
investigation, namely the baseline, pre-installation survey and the long-term final survey performed long after platform activity had ended.
The aim was to investigate, excluding the
short-term physical or toxic effects of platform
discharges, the effects of the mere presence in the
site of the submerged structure on the surrounding biocenoses.
4424.5
Materials and Methods
The first environmental investigation in the oilfield was performed in June 1985, prior to the
installation of the platform. From August 1985 to
October 1986,9 wells were drilled. The platform
produced about 4,000 tons of cuttings and 200
tons (wet material) of water-based muds.
Drilling discharges have been completely
stopped since late 1986. Eight years later (1993,
late August) the final investigation was performed in the same seasonal period and site.
Samples were collected on the same sampling grid in 18 sampling points in the first investigation and in 30 sampling points in the second
(Fig. 1) The overall grid size was about 3 km wide
in WSW-ENE direction by 4.5 km long in the
NNW-SSE direction. Sampling was performed
with a hydraulic grab having a collecting surface
of 0.07 m 2 • Three replicates were collected at each
• - 80TH SURVEYS
4423.5
0
c:r
•
~
~ ......
4422.5
4421.5
1228.5
•
a-2nd
a
• • • •
• o~o·
. ~
•
•
•
a
•
0
•
1227.5
LONG. EST
SURV.ONLY
•
a
0
0
•
1228.5
Fig.l. Location and sampling grid
R. Crema et aI.
developed in the northern Adriatic Sea. As part
of a research program aimed to investigate on
the effects of this activity, the "history" of a platform was studied by means of several field surveys; these were carried out over a long period,
beginning immediately prior to the installation
of the platform and extending up to 8 years after,
when all platform activity had terminated.
The platform is located off the city of
Ravenna, on muddy bottoms of about 15 m
depth. Data utilized in this paper pertain to surveys performed at the start and the end of the
investigation, namely the baseline, pre-installation survey and the long-term final survey performed long after platform activity had ended.
The aim was to investigate, excluding the
short-term physical or toxic effects of platform
discharges, the effects of the mere presence in the
site of the submerged structure on the surrounding biocenoses.
4424.5
Materials and Methods
The first environmental investigation in the oilfield was performed in June 1985, prior to the
installation of the platform. From August 1985 to
October 1986,9 wells were drilled. The platform
produced about 4,000 tons of cuttings and 200
tons (wet material) of water-based muds.
Drilling discharges have been completely
stopped since late 1986. Eight years later (1993,
late August) the final investigation was performed in the same seasonal period and site.
Samples were collected on the same sampling grid in 18 sampling points in the first investigation and in 30 sampling points in the second
(Fig. 1) The overall grid size was about 3 km wide
in WSW-ENE direction by 4.5 km long in the
NNW-SSE direction. Sampling was performed
with a hydraulic grab having a collecting surface
of 0.07 m 2 • Three replicates were collected at each
• - 80TH SURVEYS
4423.5
0
c:r
•
~
~ ......
4422.5
4421.5
1228.5
•
a-2nd
a
• • • •
• o~o·
. ~
•
•
•
a
•
0
•
1227.5
LONG. EST
SURV.ONLY
•
a
0
0
•
1228.5
Fig.l. Location and sampling grid