Clean-up operations

 
 

Former clean-up activities such as in reaction to the 1967 Torrey Canyon Oil Spill, caused more damage than the oil itself, because toxic dispersants had been used. Modern dispersants are no longer toxic. But also after more recent oil spills (Amoco Cadiz or Exxon Valdez) the clean-up activities were more destructive on the long term than the oil. Several different clean-up techniques were tested in the study area. The trials conducted were evaluated and compared to adjacent un-cleaned sites.

 
 

Following clean-up systems were tested:

  • a sprinkler-flusher for the mangroves on Qurma island,
  • a dry tiller at a mudflat in Dawhat al Musallamiyah
  • a tiller-flusher at a sand and mud site in Dawhat ad-Dafi
  • an autoflusher at a sand and mud flat in Dawhat ad-Dafi
  • an autoflusher at the same sand and mud flat in Dawhat ad-Dafi in 1993
  • a high pressure sea water jet at a rocky shore in Dawhat al Musallamiyah
  • mechanical removal of oiled sand on Karan island
  • dry tilling on cyanobacterial flat in spring 2001
 
tilling

Intertidal area in Dauhat al- Musallamiya

after dry-tilling. This technique breacks up

the surface tar layer, making the oil more

available to degradation (April 1993)

A large water jet flusher ("autoflusher")

is used to remove oil from open

soft-sediment shores (June 1992)

autoflusher
 
 
flusher

The manually operated version of the

"autoflusher" may be suitable for

application in mangrove and

salt-marsh areas (June 1992)

 

In general, the artificial clean-up showed nearly no success and in some cases even increased the damage to the ecosystem.

 
 

Cleanup techniques and their results:

 
 

technique

result

sprinkler-flusher for the mangroves on Qurma island

prevents oil from adhering to the pneumato-phores; plants seemed healthier where this system was applied

dry tiller at a mudflat in Dawhat al Musallamiyah

produces a marginal higher diversity after 3 years, although the sediment is still heavily disturbed. 

tiller-flusher at a sand and mud site in Dawhat ad-Dafi

No enhanced recovery obvious

autoflusher at a sand and mud flat in Dawhat ad-Dafi

flushing causes oil to penetrate deeper into the sandy sediment; operation has not enhanced recovery at this site

autoflusher at the same sand and mud flat in Dawhat ad-Dafi in 1993

flushing released liquid oil which reduced faunal diversity 50% and abundance by 90% in the upper eulittoral and 40% in the mid eulittoral (Jones et al. 1995). Overall negative effect.

high pressure sea water jet at a rocky shore in Dawhat al Musallamiyah

destroys pockets of surviving fauna; no enhanced recovery even when applied in stripes perpendicular to the shore; recovery only dependant on proximity to sources of repopulation

mechanical removal of oiled sand on Karan island

successful; turtles returned for breeding

dry tilling on cyanobacterial flat in spring 2001

not successful; cyanobacteria covers the whole area after one year

 
 

(Barth 2002 / Plaza & Al Sanei 1995)

 
 

Regarding the fact, that more than 50% of the Saudi Arabic Gulf shores are low energy shores which need significantly more time for recovery than 10 years, and the low efficiency of clean up operations, the consequence is, that oil must be prevented from drifting ashore.
Therefore, the future research effort must focus on the problem, how to prevent oil from settling within the upper intertidal zone. (Barth 2002)

 
 

Recommendations

 
 

Due to the number of oil installations, the petrochemical industry, and associated shipping, there is a reasonable probability of future oil accidents and oil spills along the Saudi Arabian coast. Most of these oil spills will be minor ones and therefore affect only short stretches of coastline, but they may still destroy a valuable habitat without counter action. Therefore it is essential not only to develop a contingency plan (as done by Watt 1994b), but also to develop new methods in dealing with spilled oil in the shallow waters of the Gulf and to implement a working and efficient information network. Based on this study, several recommendations are given how to deal with future oil spills threatening the Gulf shores.

In case of an oil spill at low energy shores, clean up activities should be concentrated on the mangrove ecosystems using sprinkler techniques to clean the pneumatopores of the Avicennia trees.

Additionally beaches on the offshore islands need cleaning, in order to provide clean sand as a breeding area for endangered species such as the green turtle.

For the rest of the area no cleanup operations are recommended.

What can be done in order to prevent oiling of the shallow shores?

All coastal ecosystems along the shores of the Arabian/Persian Gulf should be assessed in order to define environmentally sensitive areas which have to be treated as priority areas in case of an  oil spill.

The collected information should be stored in a geographical information system (GIS). This information is to be combined with the coastal topography (an other GIS layer) in order to find out suitable locations for the establishment of booms and skimmers, in order to divert  oil away and thus protect suitable locations (e.g. Qurmah island as suggested by Plaza et al. 1995)

More important still, is to push research dealing with modern oil spill response technologies. For the Gulf Region a new adsorber based technology developed by the University of Rostock, Germany, and the University of Szczecin, Poland, would be extremely efficient. The system is based on specially foamed small plastic elements (adsorbers) which have hydrophobic and oleophilic characteristics (EKU Development 2002). These adsorbers are distributed by plane, helicopter or ships.

The pore size of the adsorbers is adjusted to different viscosities of the oil. They are released from special containers under water to rise to the surface according to buoyancy. Oil within the water column will already be bound by the adsorbers on their way to the surface. The collection of the oil-soaked adsorbers is carried out by a conventional modified fishing technology which is carried by two ships.

The adsobers could also be collected from the beaches, where hardly any oil remains polluting the beaches. The adsorbers can be cleaned for future use or disposed. The main advantage of this technology is the possibility to act in extremely shallow water, during high wind speeds and rough water as well as high currents.

This highly effective system, which has been tested in temperate waters has still to be tested in the Arabian Gulf. Such tests should urgently be supported by decision makers and officials in the Gulf countries. By the means of such new technologies, combined with an effective information system, future oil spills might be under control before reaching the shores with their devastating effects to the biological communities.

An other important field of research is the computing of efficient hydrodynamic models which are able to simulate the movement of oil slicks under different weather conditions. These models must also be developed for the coastal embayment systems.

 
 
text: Hans-Jörg Barth (Barth 2002) (photos: F. Krupp)
 
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