Water Column Monitoring of the Biological Effects of Produced Water from the Ekofisk Offshore Oil Installation from 2006 to 2009

Abstract

The Norwegian water column monitoring program investigates the biological effects of offshore oil and gas activities in Norwegian waters. In three separate surveys in 2006, 2008, and 2009, bioaccumulation and biomarker responses were measured in mussels (Mytilus edulis) and Atlantic cod (Gadus morhua) held in cages at known distances from the produced water (PW) discharge at the Ekofisk oil field. Identical monitoring studies performed in all three years have allowed the biological effects and bioaccumulation data to be compared, and in addition, enabled the potential environmental benefits of a PW treatment system (CTour), implemented in 2008, to be evaluated. The results of the 2009 survey showed that caged animals were exposed to low levels of PW components, with highest tissue concentrations in mussels located closest to the PW discharge. Mussels located approximately 1-2 km away demonstrated only background concentrations of target compounds. Concentrations of polycyclic aromatic hydrocarbons (PAH) and alkyl phenol (AP) metabolites in the bile of caged cod were elevated at stations 200-250 m from the discharge. There was also a signal of exposure relative to discharge for the biomarkers CYP1A in fish and micronuclei in mussels. All other fish and mussel biomarkers showed no significant exposure effects in 2009. The mussel bioaccumulation data in 2009 indicated a lower exposure to the PW effluent than seen previously in 2008 and 2006, resulting in an associated general improvement in the health of the caged mussels. This was due to the reduction in overall discharge of PW components (measured as oil in water) into the area in 2009 compared to previous years as a result of the improved PW treatment system.

The Distribution of the MusselMytilusSpecies Along the Norwegian Coast

“…After 30 days caging of mussels at the Cecina estuary in Tyrrhenian coast, twofold increase of MN incidences in gill cells has been observed (Nigro et al, 2006). The gradient-related increase in MN was found in haemocytes of mussels and liver erythrocytes of Atlantic cod caged for 5-6 months at Norwegian oil platforms in the North Sea (Hylland et al, 2008, Brooks et al, 2011. Furthermore recovery was detected in the Haven oilship sinking zone using the MN test in caged mussels ten years after the oil spill (Bolognesi et al, 2006b).…”

“…Increased environmental genotoxicity and cytotoxicity has been described in an offshore Ekofisk oil extraction field (Rybakovas et al, 2009). The Water Column Monitoring Programme indicated increased genotoxicity in caged mussels in sites that were close to the Ekofisk oil platform indicating the ability to pinpoint source discharges with genotoxic endpoints in caged mussels (Baršienė, IRIS WCM Reports 2006Brooks et al, 2011). Significant MN elevation in fish and mussels was found after exposure to the crude oil extracted from the North Sea Bolognesi et al, 2006;Baršienė, Andreikėnaitė, 2007;Andreikėnaitė, 2010) and from arctic zones (Baršienė et al, unpublished data).…”

Monitoring of polycyclic aromatic hydrocarbons in a produced water disposal area in the Potiguar Basin, Brazilian equatorial margin

“…The estimated concentrations of PAH in seawater in the Potiguar Basin were comparable to the results found in the Norwegian sector of the North Sea (20-40 ng L −1 ), where blue mussels (Mytilus edulis) and SPMD were also used to estimate PAH concentrations in seawater (Utvik et al 1999;Durell et al 2000Durell et al , 2006Neff et al 2006;Brooks et al 2011a, b).…”

Advanced PAH pollution monitoring by bivalves

“…M. edulis has been used for biomonitoring studies in Norway (Aarab et al 2004(Aarab et al , 2008(Aarab et al , 2011; a suite of different biomarkers on their natural populations revealed differences between a previous aluminum smelter (encumbered by PAH) and a reference site. Furthermore, a real-time evaluation of a treatment system installed on an oil exploitation platform was made possible with the use of NR retention time and MN formation in sentinel M. edulis mussels (Brooks et al 2011;Sundt et al 2011).…”