J.W. Readman

Petroleum and PAH contamination of the Black Sea

Concern has been expressed regarding the extent of contamination of the Black Sea. Analyses of coastal sediments taken from throughout the region indicate, however, that levels of petroleum hydrocarbons (2-300 microg g(-1) dry wt total hydrocarbons) are generally comparable to those encountered in the Mediterranean and are lower than concentrations reported for highly contaminated areas such as the Gulf, Hong Kong, Taiwan and New York Bight. Highest concentrations of total hydrocarbons (>100 microg g(-1) dry wt) were associated with discharges from Odessa, Sochi and the River Danube. Chronic/degraded petroleum was the major contributor at these sites. Samples from the Ukrainian coastline were comparatively clean (<10 microg g(-1) dry wt total hydrocarbons). Major contributions of fresh oil (as indicated by sigma n-C14-34) occur through the River Danube. Concerning total PAH, concentrations (7-638 ng g(-1) dry wt) compare to relatively unpolluted locations in the Mediterranean and are much lower than levels reported for polluted UK estuaries (e.g. Mersey, Tyne, Thames). Both pyrolytic and petrogenic PAH are present in most samples, although petroleum derived PAH are dominant at Sochi and pyrolytic sources are prevalent in the Bosphorus region. The absence of a correlation between total hydrocarbons and PAH (R2 = 0.04) indicates different primary sources for the two.

Contamination of Mediterranean (Côte d'Azur) coastal waters by organotins and irgarol 1051 used in antifouling paints

Abstract A survey was recently conducted to investigate concentrations of selected antifouling agents in sub-surface waters from the Mediterranean (Cote dAzur) coastline. Substantial levels of tributyltin (TBT) and 2-methylthio-4-tert-butylamino-6-cyclopropylamino- s -triazine (Irgarol 1051) were detected in all marinas, with concentrations reaching 460 ng l −1 for TBT and 640 ng l −1 for Irgarol 1051. Triphenyltin (TPT) and the TBT degradation products (dibutylin (DBT) and monobutylin (MBT)) were also detected, but at lower concentrations than TBT. High ratios of TBT/DBT were recorded, which suggests recent inputs of the active biocide TBT. Despite restrictions on the use of organotin-based marine antifouling paints imposed in France in 1982 and throughout the Mediterranean in 1991, the concentrations encountered still represent an ecotoxicological risk. However, when compared with concentrations from our previous surveys, current contamination from TBT is substantially less than that recorded in October 1988. The levels of the antifouling triazine herbicide Irgarol 1051 are similar to those reported from a survey in 1992. Another triazine (terbutryn) was also encountered in a few marina waters, although the source of this compound is uncertain.

Petroleum hydrocarbons and trace metals in nearshore Gulf sediments and biota before and after the 1991 war: An assessment of temporal and spatial trends

Abstract Immediately following the 1991 Gulf War, a survey was organized to determine the extent and degree of contamination by petroleum hydrocarbons and trace metals that entered the Gulf from the massive oil spill and oil field fires in Kuwait. Between June–October 1991 samples of nearshore sediments, bivalves and fish were collected from Kuwait, Saudi Arabia, Bahrain, UAE and Oman. Analyses revealed that the highest levels of contamination were along the heavily-impacted coast of Saudi Arabia between Ras Al Khafji and Ras Al Ghar, where concentrations of total petroleum hydrocarbons (expressed as Kuwait crude oil equivalents) ranged from 62–1400 μg g−1 dry wt in surface sediments, 570–2600 μg g−1 dry wt in clams and 9.6–31 μg g−1 dry wt in fish muscle. Gas chromatographic analyses indicated that much of the oil in the intertidal zone had substantially degraded within a few months of the spill. Concentrations of the oil-related metals Ni and V were slightly elevated in oil-contaminated sediments from Saudi Arabia but elsewhere in the Gulf were similar to levels measured in earlier years at those sites. This initial regional survey demonstrated that hydrocarbon contamination originating from the war-related pollution events was restricted to approximately 400 km from the source, that levels of combustion derived PAHs in the marine environment at that time (e.g. 1–450 ng g−1 dry wt for pyrene in sediments) were of the same order as those which have been measured in several coastal areas of the eastern United States and northern Europe, and that outside the immediate area of impact, petroleum hydrocarbon and trace metal levels in sediment and bivalves were generally as low as, or lower than, those concentrations measured at the same sites before the war.

Herbicide contamination of Mediterranean estuarine waters: Results from a MED POL pilot survey☆

Abstract The reported data offers the first extensive evidence that significant concentrations of some herbicides persist in marine systems. In the areas studied (the Ebro delta on the Eastern Coast of Spain, the Rhone delta in the South of France, the River Po, Italy/the Northern Adriatic Sea, the Thermaikos and Amvrakikos Gulfs in Greece and the Nile delta in Egypt) the most commonly encountered herbicides were atrazine, simazine, alachlor, metolachlor and molinate. In general, aqueous concentrations encountered in the riverine inputs were comparable to (or below) those reported for rivers in other regions of the World. Concentrations generally declined from freshwater locations through estuaries to marine waters. The distributions of some herbicides (e.g. the triazines) in sediments endorsed the environmental persistence of these compounds. In contrast to the other areas studied, no herbicides were detected in samples from a preliminary survey of the Nile delta.

Persistent organochlorine residues in sediments from the Black Sea

The extent of contamination of the Black Sea by selected organochlorine compounds has been assessed through the analysis of surficial sediments taken from throughout the region. Concentrations of HCHs at sites influenced by the Danube delta are among the highest recorded on a global basis (up to 40 ng g(-1) dry wt). The ratio between the alpha- and gamma-isomers was relatively low indicating contamination through the use of lindane. Concentrations of DDTs (0.06-72 ng g(-1) dry wt) and PCBs (0.06-72 ng g(-1) dry wt) were not especially high in comparison to levels reported from throughout the world. The DDE/DDT ratio was, however, low indicating fresh inputs and hence current usage of DDT within the Black Sea region.

Organotin compounds in the Mediterranean: A continuing cause for concern

Abstract Extensive survey data for butyltins are reported for Mediterranean coastal waters together with the first phenyltin concentrations from the region. Elevated levels of tributyltin (TBT) are reported for most marina/harbour waters. In the great majority of cases, the ‘no observable effect’ aqueous concentration of 20ng litre−1 is exceeded. The TBT concentrations encountered are comparable to those reported in a previous MEDPOL pilot survey. This questions the efficacy of current legislation in the Mediterranean. The movement of foreign vessels painted outside of the scope of legislation offers an explanation for this observation and endorses the need for region-wide control measures and enforcement. The Contracting Parties to the Barcelona Convention have recently agreed to adopt such control measures to protect the Mediterranean; these are described and discussed. Concerning triphenyltin, concentrations of 21–94 ng litre−1 are reported, with most of the compound associated with the particulate phase. The distribution in samples collected from marinas and in proximity to dry docks attributes the origin of the compound to antifouling paint leachates.

Comparison of the performance of solid-phase extraction techniques in recovering organophosphorus and organochlorine compounds from water

Solid-phase extraction (SPE) of 11 organochlorine and 24 organophosphorus compounds from aqueous solution was evaluated using different Amberlite (XAD-2 and XAD-7) resin mixtures, reversed-phase C18 bonded-silica disks, and poly(styrene-divinylbenzene) (SDB) co-polymer disks. Macroreticular resins provided low recoveries and unacceptable reproducibility for some compounds including malathion, methylparathion, ethylparathion, chlorthion and endosulfan compounds. This is probably due to irreversible adsorption or chemical degradation. No relationship was observed between the recoveries and the log Kow of the compounds. Octadecyl-bonded silica and styrene-divinylbenzene disks provided comparable results for the selected compounds with recovery efficiencies depending on the polarity of the compounds. Good recoveries were achieved for compounds with water solubilities below 300 mg/l or with log Kow greater than 2. Poor recoveries were obtained for dichlorvos, monocrotophos and dimethoate.

PCBs in the western Mediterranean. Temporal trends and mass balance assessment

Comparison of data reported for polychlorinated biphenyl (PCB) concentrations in different environmental compartments of the western Mediterranean (dissolved and particulate phases of water, sediment and biota) over the last two decades shows a substantial decline in PCB concentrations, which coincides with legislated restrictions in the use of these compounds. Nevertheless, localised chronic (“hotspot”) contamination continues, which underscores the importance of these compounds as environmental contaminants in certain specific areas of the region. n nData on depositional fluxes are used to estimate and model transport processes to investigate the fate of these chemicals in the study area. A tentative mass balance of the compounds suggests that dry and wet deposition (12 t year−1) account for most of the input. This comparess with approximately 1 t year−1 discharged from rivers and sewage outfalls into coastal environments. Sedimentation is estimated to remove 5 t year−1 from the water column. Losses through volatilization are difficult to model owing to the critical dependance within calculations on atmospheric and dissolved seawater concentrations, for which very few data exist.

Recovery of the coastal marine environment in the Gulf following the 1991 war-related oil spills

Results from a 1991 rapid assessment survey to investigate the extent of hydrocarbon contamination resulting from the massive spillage of petroleum and the burning of oil wells revealed that war-related pollution in the Gulf was restricted to approximately 400 km from the sources. Subsequent surveys of the impacted zone were organized during 1992 and 1993 to investigate temporal changes in petroleum hydrocarbon contamination and recovery. Sub-tidal surface sediments from the coastlines of Kuwait and Saudi Arabia were sampled and analysed for petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs). At most locations by 1992, degradation had resulted in a composition (as determined by gas chromatography) dominated by an unresolved complex mixture, with only the most resistant resolved compounds surviving. Levels of contamination at impacted sites were generally shown to have decreased by approximately 50% between 1991 and 1992. A much lesser reduction in contamination was recorded for the period 1992 to 1993, and an increase in hydrocarbon concentrations was noted for stations in Kuwait and northern Saudi Arabia, possibly as a result of increased tanker activity and associated deballasting. PAH concentrations are shown to remain comparatively low, with oil rather than combustion being the major source.

MED POL survey of organotins in the Mediterranean

A pilot survey of tributyltin (TBT) and its derivatives in Mediterranean areas was undertaken in 1988 within the framework of the MED POL activities. The areas studied were the French Mediterranean coast, the Northern Tyrrhenian coast, the Southern coast of Turkey and the Alexandria (Egypt) coastal area. 113 water samples were analysed from the first three areas and 35 sediment samples from the fourth. Samples were collected at sites selected according to differing environmental conditions and potential inputs of TBT. Two shellfish-culture areas in the South of France located near marinas were included. The data reported represent the first coordinated survey of butyltin levels in seawater and sediments from Mediterranean areas. The concentrations generally exceed the no-observed effect level (NOEL) of 20 ng l−1 and are comparable to those previously reported for similar situations outside the Mediterranean area.