Pollution levels in the southern barents sea sediments: Results from the ongoing mareano programme and the need for new research
|Location||International Geological Congress,oslo 2008|
|Author||Jensen, Henning K. B.۱; Knies, Jochen۱; Finne, Tor Erik۱; Klungsّyr, Jarle۲; Thorsnes, Terje۱; Boitsov, Stepan۲|
|Holding Date||08 October 2008|
The Barents Sea covers ca. 1400 thousand km2 with mainly shallow sea depths. The Barents Sea is a pristine marine environment, which has not been subjected to the massive activities like the North Sea. However, this is now changing with increasing oil- and gas activities, major fishing activities and increasing shipping along the coast of Northern Norway. It is of vital importance to document the status of the environment before major industrial activities commence. Hence there is a big need to establish the current situation when it comes to levels of pollution in the marine sediments. The following requirements must be met:
Identification of relevant locations for sediment sampling requires high-quality maps of the sedimentary surface. This is accomplished by multibeam acoustic mapping, which generates data about hard versus soft sediment bottoms.
Contaminants are mainly associated with fine-grained sedimentary environments with continuous sedimentation. Hydrocarbon analyses are important for assessing the impact of the oil- and gas-exploration activities, since there are known natural sources of hydrocarbons in the Barents Sea, and background levels of these compounds may be relatively high. Geochemical analyses of sediment cores allow assessing the sources and temporal variations in the levels of contaminants.
Results from the current Mareano-programme indicate that the investigated areas are classified as being minimally affected by pollution by either heavy metals or organic pollutants. The temporal variations obtained from 210Pb-dated cores suggest an anthropogenic contribution of Hg and Pb in recent times, increasing from background levels. Hydrocarbon levels are generally low; there are, however, indications of a limited anthropogenic influence in the samples taken from fjord areas, with an apparent increase in recent times. In open sea areas, hydrocarbons of petrogenic and sometimes biogenic origin seem to predominate.
Good control of human activities in areas with continuous sedimentation is of great importance. Disturbed sediments from either trawling activities or natural sliding in one particular case gave misleadingly high sedimentation rates and a disturbed geochemical picture for levels of different pollutants in the sediments subjected to this event. This stresses the importance of getting supplementary information to explain observed variations in geochemical profiles. New research is necessary to assess the significance of natural sources of organic pollutants like THC and PAH from either source rocks or trapped hydrocarbons from the Goliath oilfield which lies underneath the investigated area. Another important theme is the increasing number of organic pollutants, which are produced and entering the marine environment.