Influence of water filtration on the determination of a wide range of dissolved contaminants at parts-per-trillion levels

The adsorption of dissolved organic contaminants on glass fibre filters throughout water dissolved/particulate phase decoupling studies was examined. A total of 49 different compounds were considered at low concentration levels (ng L(-1)), including PAHs, PCBs, organochlorine and organophosphorus pesticides, triazines, thiocarbamates, pyrethroids, phosphate esters and caffeine. Their adsorption on the filters was positively correlated with their log Kow and solubilities, indicating that filter adsorption increased with hydrophobicity. The influence of water properties (i.e. salinity and dissolved organic carbon (DOC) content) was also studied by means of a star experimental design (n=11). Salinity was the main factor in increasing the adsorption, due to the salting out effect. The influence of DOC suggested that part of the contaminant losses during water filtration may have been caused by the retention on the organic matter adsorbed on the filter surface. Nevertheless, a decrease in filter retention was observed for water with the highest DOC contents, which was probably due to an enhancement of the contaminant solubility in these conditions. Although several factors may control the adsorption process in naturally occurring waters, the extent of the retention of dissolved target analytes on the glass fibre filters should not be underestimated in the analysis of hydrophobic contaminants in marine and estuarine waters at very low concentrations (ppt level).

Fingerprinting petroleum hydrocarbons in plankton and surface sediments during the spring and early summer blooms in the Galician coast (NW Spain) after the Prestige oil spill

Plankton samples (20-350 microm and >350 microm) collected at three transects along the Galician coast (NW Spain) were analysed for individual aliphatic and aromatic hydrocarbons by GC-MS. Sample collection was performed in April-July 2003, after the Prestige oil spill (November 2002), to determine whether the hydrocarbons released into the water column as a consequence of the spill were accumulated by the planktonic communities during the subsequent spring and early summer blooms. Surface sediments were also collected to assess the presence of the spilled oil, removed from the water column by downward particle transport. Plankton concentrations of PAHs (Sigma14 parent components) were in the range of 25-898 ng g(-1)dw, the highest values being close to coastal urban areas. However, the individual distributions were highly dominated by alkyl naphthalenes and phenanthrenes, paralleling those in the water dissolved fraction. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes, and methyl phenanthrenes and dibenzothiophenes) showed the occurrence of background petrogenic pollution but not related with the Prestige oil, with the possible exception of the station off Costa da Morte in May 2003, heavily oiled after the accident. The dominant northerly wind conditions during the spring and early summer 2003, which prevented the arrival of fresh oil spilled from the wreck, together with the heavy nature of the fuel oil, which was barely dispersed in seawater, and the large variability of planktonic cycles, could be the factors hiding the acute accumulation of the spilled hydrocarbons. Then, with the above exception, the concentrations of PAHs found in the collected samples, mostly deriving from chronic pollution, can be considered as the reference values for the region.

Spatial and temporal trends of petroleum hydrocarbons in wild mussels from the Galician coast (NW Spain) affected by the Prestige oil spill

Polycyclic aromatic hydrocarbons (PAHs) were determined in tissues of wild mussels (Mytilus galloprovincialis) from the Galicia coast (NW Spain) in order to assess the extent of the environmental impact caused by the Prestige oil spill (November 13, 2002). Three sampling campaigns were carried out in February, June and November 2003 at 24 stations along the Galicia coast, from La Guardia (Pontevedra) to Ribadeo (Lugo). The spatial distribution of PAHs found in the first sampling period, clearly revealed the central area (Costa da Morte) as the most affected by the oil spill. In these stations, concentrations up to 7780 microg/kg dw of the sum of 13 parent PAHs were found 2-3 months after the spill. Molecular parameters within the aliphatic and aromatic fractions confirmed the presence of the Prestige oil in these samples. The levels markedly decreased at most of the stations in the second sampling and recovered to levels found before the spill in November 2003, 1 year after the accident (29-279 microg/kg dw, av. 133+/-83 microg/kg dw). However, a certain increase was observed in some sites which could be related to the remobilization of oil residues from still unclean intertidal spots or sediments due to the winter marine weather conditions.

Organic contaminant loads into the Western Mediterranean Sea: estimate of Ebro River inputs

Annual input estimates for several organic contaminants from the Ebro River into the Northwestern Mediterranean Sea were carried out on the basis of monthly sampling from November 2002 to October 2003. Some organochlorine compounds (DDT and its degradation products, DDD and DDE, PCBs (9 congeners), HCB and gamma-HCH) were selected due to their reported occurrence in the river. Furthermore, some polar pesticides used in the Ebro Delta were also determined (atrazine, simazine, diazinon, fenitrothion and molinate). Concentrations ranged from 0.4 to 19.5 ng l(-1) for the organochlorine compounds (sum of particulate and dissolved phases) and from not detected (ND) to 170 ng l(-1) for the more polar pesticides, which were only found in the dissolved phase. The sum of PCB congeners (mean 8.9 ng l(-1)) showed the highest concentrations among the organochlorine compounds and atrazine (mean 82 ng l(-1)) among the polar pesticides. Based on the contaminant concentrations and on hydrological data, contaminant discharges into the sea were estimated amounting in total to 167 and 1,258 kg year(-1) of organochlorine compounds and polar pesticides, respectively. Furthermore, it was observed that PCBs, DDTs and HCB inputs were basically influenced by spate periods due to an increase in suspended particulate matter associated to runoff and sediment resuspension. Whereas for more water soluble contaminants, such as the agrochemicals, their seasonal use had a higher incidence in contaminant fluxes. Bulk chemical parameters such as SPM, DOC, POC, %OC, %ON and C/N ratio provided additional information on the organic matter sources. This provides a better understanding of the temporal variability of the contaminant concentrations.

Occurrence and degradation of butyltins and wastewater marker compounds in sediments from Barcelona harbor, Spain

Contamination of Barcelona harbor sediments was assessed by the quantitative determination of butyltins (TBT, DBT and MBT) and surfactant intermediates, namely linear alkylbenzenes (LABs) and nonylphenols (NPs), as markers of urban and industrial wastewater contamination, respectively. Degradation indexes of TBT and LABs were calculated. Tributyltin predominated in the whole area over its degradation products, ranging from 98 to 4702 ng Sn/g. These elevated concentrations reveal a persistent historical contamination and a moderate degradation (BT(deg)). Moreover, the high LAB concentrations (1.2-53.1 microg/g) compared to the relatively low NP levels (3.8-72.0 ng/g) suggest a predominance of urban over industrial wastewater inputs, although a significant correlation (r(2) = 0.82, N = 12, P = 0.001) between LABs and NPs was found. Stormwater runoff and combined sewer overflows (CSO) were likely the most possible sources for both surfactant intermediates. The high degradation index values obtained for LABs could indicate an improvement in the wastewater management reducing its recent discharge into the Barcelona harbor area.

Spatial and temporal distribution of dissolved/dispersed aromatic hydrocarbons in seawater in the area affected by the Prestige oil spill

Seawater samples collected at three depths from 68 stations along the Northern Spanish coast were analysed for dissolved/dispersed petroleum aromatic hydrocarbons by UV-fluorescence and for 25 individual compounds by GC-MS. Sampling was performed in December 2002, just after the Prestige oil spill, and in February-March and September 2003. Higher concentrations of total aromatic hydrocarbons were found at all depths in the samples collected during December 2002 off the Galicia coast, with levels ranging between 0.19 and 28.8 microg/L eq. oil (0.1-4.8 microg/L chrysene eq.). These values decreased in the following cruises, till <0.05-2.86 microg/L oil eq. (av. 0.23 microg/L chrysene eq.) in September 2003, possibly representing the background levels for the region. However, in the Cantabrian coast they were still high at the surface in the March cruise, probably by the late arrival of the fuel-oil to this area. Some coastal hot spots were also identified, with values up to 29.2 microg/L fuel-oil eq., close to river mouths and urban areas. The individual PAH distributions in the December 2002 sampling off-Galicia were dominated by alkyl-naphthalene derivatives, consistently with the pattern distribution shown by the fuel-oil water accommodated fraction. The higher concentrations were found in the subsurface samples along the Costa da Morte, the area most heavily affected by the spill (av. 0.46 microg/L Sigma16 PAHs). The rest of the samples collected in other areas exhibited lower concentrations and a more even distribution of 2-4 ring PAHs, that ranged from 0.09 to 0.37 microg/L (av. 0.15 microg/L Sigma16 PAHs), with decreasing trends offshore and downward the water column. In September 2003, the values were rather uniform, averaging 0.09 microg/L (Sigma16 PAHs).

Spatial distribution and ecotoxicity of petroleum hydrocarbons in sediments from the Galicia continental shelf (NW Spain) after the Prestige oil spill

The distribution of aliphatic and aromatic hydrocarbons was determined in surface sediments collected at 36 stations along the Galicia continental shelf (NW Spain), following the Prestige oil spill. Sampling was performed in December 2002, just after the accident, and in February and September 2003. Concentrations of PAHs (summation operator 13 parent components) were in the range of 0.9-422 microg/kgdw, the highest values being close to coastal urban areas (e.g. Pontevedra and A Coruña), whereas in the stations of the area most heavily impacted by the spill (off Costa da Morte) concentrations were in the range of 14.8-89.6 microg/kgdw, with a certain predominance of alkylated compounds, which may suggest a mixture of petrogenic and pyrolytic sources. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes) showed the occurrence of an old (weathered) petrogenic chronic pollution in the shelf sediments but not of the Prestige oil, with the possible exception of few stations in the area of Costa da Morte. This was attributed to the heavy nature of the spilled oil that was barely dispersed in the water column and mainly stranded on the coast or sedimented in the form of oil patches. The addition of increasing amounts of fuel oil to a representative sediment sample showed that the molecular indices were indicative of the presence of the Prestige oil when the amount was above 1g/kg of sediment. The toxicity of selected samples (showing the higher PAH concentrations) was tested using the bivalve embryogenesis bioassay. Embryogenesis success reached high values in all cases (80-88%, with 86% in the control), indicating a lack of toxicity in the sediments and supporting the conclusion that the patchiness of the fuel eventually reaching the seafloor reduced its impact on the benthic communities of the Galician shelf.

The prestige oil spill. I. Biodegradation of a heavy fuel oil under simulated conditions

In vitro biodegradation of the Prestige heavy fuel oil has been carried out using two microbial consortia obtained by enrichment in different substrates to simulate its environmental fate and potential utility for bioremediation. Different conditions, such as incubation time (i.e., 20 or 40 d), oil weathering, and addition of an oleophilic fertilizer (S200), were evaluated. Weathering slowed down the degradation of the fuel oil, probably because of the loss of lower and more labile components, but the addition of S200 enhanced significantly the extension of the biodegradation. n-Alkanes, alkylcyclohexanes, alkylbenzenes, and the two- to three-ring polycyclic aromatic hydrocarbons (PAHs) were degraded in 20 or 40 d of incubation of the original oil, whereas the biodegradation efficiency decreased for higher PAHs and with the increase of alkylation. Molecular markers were degraded according to the following sequence: Acyclic isoprenoids > diasteranes > C27-steranes > betabeta-steranes > homohopanes > monoaromatic steranes > triaromatic steranes. Isomeric selectivity was observed within the C1- and C2-phenanthrenes, dibenzothiophenes, pyrenes, and chrysenes, providing source and weathering indices for the characterization of the heavy oil spill. Acyclic isoprenoids, C27-steranes, C1- and C2-naphthalenes, phenanthrenes, and dibenzothiophenes were degraded completely when S200 was used. The ratios of the C2- and C3-alkyl homologues of fluoranthene/pyrene and chrysene/benzo[a]anthracene are proposed as source ratios in moderately degraded oils. The 4-methylpyrene and 3-methylchrysene were refractory enough to serve as conserved internal markers in assessing the degradation of the aromatic fraction in a manner similar to that of hopane, as used for the aliphatic fraction.

Comparison of sampling devices for the determination of polychlorinated biphenyls in the sea surface microlayer

Over 30 sea surface microlayer (SML) samples from two contrasting sites in the North Western Mediterranean -- Barcelona (Spain) and Banyuls-sur-Mer (France) -- were collected using three different sampling devices, namely, glass plate, metal screen (MS) and a surface slick sampler (SS), and compared with the corresponding underlying water (16 samples). The distributions of 41 polychlorinated biphenyl congeners (PCBs) were determined in the different phases: particulate (1.17-10.8 SigmaPCB ng L(-1)), truly dissolved (0.080-16.7 SigmaPCB ng L(-1)) and colloidal matter (1.17-43.0 SigmaPCB ng L(-1)), being the last two estimated from the analysis of the apparently dissolved phase. Concentrations of PCBs in the SML were higher than those in the underlying water (ULW), giving rise to enrichment factors (EF=[C](SML)/[C](ULW)) up to first-order of magnitude. The ANOVA statistical approach was used to assess differences of bulk data (e.g. dissolved organic carbon, DOC; particulate organic carbon, POC; suspended particulate matter, SPM) among sampling devices, whilst p-tailed t paired tests were used in order to compare the enrichments obtained for each sampling date. In this respect, no significantly different enrichment factors were found among sampling devices (p < 0.05), although the surface SS showed lower enrichments, probably due to the dilution of the SML with the ULW during sampling. The MS seemed to be the most suitable device for the determination of PCBs in the SML in terms of sampling efficiency under a variety of meteorological conditions.

Evaluation of sampling devices for the determination of polycyclic aromatic hydrocarbons in surface microlayer coastal waters

The sea surface microlayer (SML) may play an important role on the transport and fate of persistent organic pollutants in the marine environment. In order to evaluate the appropriateness of a number of sampling devices for the analysis of 14 parent polycyclic aromatic hydrocarbons (3-5 aromatic rings), marine SML waters were sampled using a glass plate, a rotating drum/roller, a metal screen and a surface slick sampler. The underlying waters were also sampled for the determination of the corresponding enrichment factors (EF = [C](microlayer)/[C](underlying water)). The EFs were phase dependent, ranging from 1 to 3 for the dissolved phase and between 4 and 7 for the particulate phase. In order to better assess the performance of the different sampling methods, in terms of phase partitioning, the truly dissolved and colloidal phases were also estimated. Generally, no significant differences were found for the enrichment factors provided by the different methods, due to the observed large variability in concentrations that can be attributed to small-scale coastal processes. However, the metal screen is recommended as the most efficient sampling method for the study of PAHs taking into account the amount of water collected versus time.

Factors affecting the organochlorine pollutant load in biota of a rice field ecosystem (Ebro Delta, NE Spain)

The concentrations of PCBs, DDTs, HCHs, HCB and OCS were determined in sediments and associated biota, both invertebrates (Physella acuta, Hirudo medicinalis, chironomid larvae, Hydrous pistaceus, Helochares lividus) and vertebrates (Rana perezi), in a temporary aquatic system, a rice field in the Ebro Delta (NE Spain). The qualitative and quantitative distribution of organochlorine compounds in sediments and aquatic biota has been explained by two mechanisms: equilibrium partitioning and/or biomagnification through the trophic web. Nevertheless, bioaccumulation processes are by far more complex, since several biotic and abiotic factors contribute to the observed pollutant loads in the organisms. In this respect, the biological characteristics of the organisms considered (e.g. species, age, lipid contents, feeding habits, etc.), as well as ecological factors (e.g. the habitat of the species and vertical distribution), have been shown to account for the organochlorine levels observed.

Fast solid-phase extraction–gas chromatography–mass spectrometry procedure for oil fingerprinting

A rapid and simple fractionation procedure using solid-phase extraction (SPE) cartridges was developed for an accurate determination of aliphatic and polycyclic aromatic hydrocarbons in petroleum residues and further application in chemical fingerprinting of oil spills by gas chromatography-mass spectrometry (GC-MS). Among the adsorbents evaluated, SiO2/C3-CN exhibited the best selectivity, providing, by elution with n-hexane (4 ml) and n-hexane-CH2Cl2 (1:1) (5 ml), two well-resolved aliphatic and aromatic hydrocarbon fractions, with recoveries of 97 +/- 7.2 and 99.7 +/- 13.9%, respectively. The SPE fractionation procedure was compared with the conventional silica-alumina adsorption chromatography showing similar results but practical advantages in terms of reproducibility, analysis time, solvent reduction and cost. Moreover, is particularly suitable for routine analysis with a high sample throughput. The developed methodology was tested in the characterization of fuel-oil samples collected along the Spanish north-west coast, after the Prestige oil spill accident.

The aegean sea oil spill in the Galicia Coast (NW Spain). I. Distribution and fate of the crude oil and combustion products in subtidal sediments

The spatial distribution and fate of petrogenic and pyrogenic hydrocarbons in coastal sediments following the Aegean Sea oil spill (Galicia, NW Spain) was investigated through a detailed study of chemical markers. Alkanes and acyclic isoprenoid hydrocarbons were degraded within six months of the accident, but triterpane and sterane distributions were still detectable and were useful in monitoring, respectively, the oil source and weathering. Aromatic steranes were also useful source indicators, and oil degradation was clear from the decrease of certain alkyl dibenzothiophene and phenanthrene isomers. The pyrogenic polycyclic aromatic hydrocarbons produced in the tanker wreck were found more persistent than the petrogenic ones. However, the presence of the oil in the sediments was recognized even one year after the accident and was found particularly preserved in the subsurface layers.

A potential source of organic pollutants into the northeastern Atlantic: the outflow of the Mediterranean deep-lying waters through the Gibraltar Strait

Small and large-size particles were collected in the water column (50-3000 m) of a Northeastern Atlantic area where deep Mediterranean waters, outflowing through the Strait of Gibraltar, are incorporated at mid-depth. Particles collected by water filtration (0.7 micron pore size) and by vertical hauls of a neuston net (50 microns mesh size) were analyzed for organic pollutants, namely aliphatic and aromatic hydrocarbons, and organochlorine compounds. Small-size particles represented the largest bulk of particulate organic carbon as well as of hydrophobic organic pollutants. Surface concentrations of n-alkanes [C14-C35), aromatic hydrocarbons (12 parent compounds), PCBs (7 congeners), and DDTs (DDT + DDE) were, respectively, in the range of 50-63 ng/L, 23-68 pg/L, 8-13 pg/L, and 0.05-1.7 pg/L. These concentrations showed a general decrease with depth, particularly significant in the upper 200 m, consistently with the POC contents. Compositional changes with depth were also evident in small-size particles and included the depletion of low molecular weight n-alkanes and low chlorinated PCB congeners as well as a decrease of the fossil to pyrolytic PAHs ratio. Unusual increases of concentrations were observed at mid-depths (900-1100 m), indicating additional particle inputs, either by in-situ formation or by advective transport from the Mediterranean. The latter was recognized because small-size particles within these water veins exhibited distribution patterns out of the vertical sequence and similar to those of deep Mediterranean waters. An input of 8 and 0.5 tons per year of the above PAH and PCB compounds, respectively, has tentatively been calculated as the contribution of these Mediterranean waters to the Northeastern Atlantic.

The integrated use of chemical analysis, cytochrome P450 and stress proteins in mussels to assess pollution along the Galician coast (NW Spain)

Aliphatic and polycyclic aromatic hydrocarbons (PAHs) as well as biochemical markers, such as cytochrome P450, benzo(a)pyrene hydroxylase (BPH) and stress-70 proteins, were determined in mussels (Mytilus galloprovincialis) collected in October 1995 from several locations along the Galician coast (NW Spain). The survey proved the existence of a pollution gradient among sampling sites and a chronic exposure to petrogenic and pyrolitic hydrocarbons. This was reflected in mussel tissue levels of PAHs which ranged from 22 to 562 ng/g wet weight. High levels of total cytochrome P450 were detected in mussels from the most polluted sites, but differences were not statistically significant. BPH activity did not show either differences among sampling sites. Conversely, stress-70 proteins were significantly induced in the most polluted locations, and levels of the 72-kDa band correlated well (r2 = 0.854) with the sum of the PAHs from four to six rings accumulated by mussels.

Dioxins, furans and AHH-active PCB congeners in eggs of two gull species from the western Mediterranean

Polychlorinated biphenyls, dibenzodioxins and dibenzofurans were analysed in eggs of a protected gull species, the Audouin's Gull (Larus audouinii) and compared to those of the Yellow-legged Gull (Larus cachinnans), both breeding in the Western Mediterranean (Ebro Delta and Medes Islands, respectively). Differences in concentrations as well as in congener profiles reflected differences in both habitat and diet of the two species. Levels of AHH-active PCB congeners were lower in Yellow-legged Gull (0.4-1.6 micrograms/g d.w) than in Audouin's Gull eggs (1.2-33.9 micrograms/g d.w.). These concentrations, expressed in international toxic equivalence factors (i-TEQ/g d.w.), were on average 24 times higher in the Audouin's gull. I-TEQ levels due to dioxins were also higher in this species by a factor of ca. 7. I-TEQ levels related to PCBs resulted 90-230 times higher than those of dioxins and furans. Thus, AHH-inducing PCBs might represent even higher toxicological hazards than dioxins and furans to some populations of seabirds. The necessity of assessing the impact of these compounds in rare and protected species is pointed out.

The use of biomarkers for assessing the effects of organic pollution in mussels

Wild mussels were collected from two stations with different pollution loads. Soft tissues were analyzed for their aromatic hydrocarbon and polychlorinated biphenyl content. Mixed function oxidase (MFO) system components and antioxidant defenses (catalase, superoxide dismutase and glutathione peroxidase) were determined in digestive gland microsomal and cytosolic fractions, respectively, and the magnitude of biochemical responses related with pollutant tissue levels. Results showed that significant differences existed in hydrocarbon content between mussels from the two stations, while a smaller difference in the biological response was detected.

Sources and seasonal variability of mutagenic agents in the Barcelona City aerosol

Organic extracts (dichloromethane) isolated from airborne particulate matter, collected in two sampling sites located in the Barcelona City, were mutagenic in the Salmonella typhimurium (TA98 +/-S9) bioassay. The highest direct-acting mutagenicity (69-78 rev m-3) was detected during fall and spring, which corresponds to the highest levels of mutagenic nitroarenes (248 to 350 pg m-3). On the other hand, the highest level of indirect-acting mutagenicity was obtained in summer, paralleling with the highest concentrations of polycyclic aromatic ketones and polycyclic aromatic quinones. Furthermore, the sources of PAH in the urban particulate matter were estimated from the ratio of the less reactive components (i.e. benzofluranthenes/benzo[e]pyrene, indeno[1,2,3-cd]pyrene/benzo[ghi]perylene, methylphenantherenes/phenanthrene) and reflected a predominance of pyrolytic mobile sources (i.e. vehicular emissions). Nevertheless, a contribution of stationary sources in winter was also apparent. Finally, the seasonal variability of polycyclic aromatic ketones, quinones, aromatic lactones and aldehydes reflected a major contribution of the atmospheric transformation processes from related PAH rather than a direct emission from combustion sources.

Bioaccumulation patterns of hydrocarbons and polychlorinated biphenyls in bivalves, crustaceans, and fishes

Hydrocarbons and polychlorinated biphenyls (PCBs) were determined in tissues of marine organisms (mussels, crabs, benthic, and pelagic fishes) from six sites along the Catalan Coast (Western Mediterranean). Both aliphatic and aromatic hydrocarbons as well as seven PCB congeners (PCB-28, 52, 101, 118, 138, 153, 180) were quantified and differences in concentrations interpreted in terms of geographical distribution, trophic level, and biological cycle of the organisms. The bioaccumulation patterns of the different chemicals varied substantially. Hydrocarbons were metabolized along the food web, contrarily to PCBs, which exhibited a higher bioaccumulation in fishes. Considering 36 peaks of the GC-ECD profiles, encompassing 40 PCB congeners, from tri- to octa-chlorinated isomers, a relative enrichment was observed in the higher chlorinated ones from: mussels < mullets < tuna < crabs. The slopes of the correlation plots between the bioconcentration factor (log BCF) and the octanol-water partition coefficient (log K(ow)) for the different PCB congeners reflected the feeding behavior of the organisms, mussels exhibiting a preferential uptake by direct partitioning from water, and mullets and crabs with a certain uptake from sediments. Increasing metabolic degradation following a similar trend among species was also observed for aromatic hydrocarbons and PCB congeners containing meta and para vicinal H-atoms. Accordingly, mussels and benthic fishes were the best indicators of coastal pollution in the water column and sediments, respectively, although the above features should not be overlooked in the interpretation of biomonitoring data.