Biomarker approach to evaluating the impact of scientific stations on the Antarctic environment using Trematomus bernacchii as a bioindicator organism

A biomonitoring study was performed to evaluate the human impact on two small coves adjacent to the Italian Scientific Station at Terra Nova Bay in November 1995. The study used the fish species Trematomus bernacchii as a bioindicator organism for a biomarker analysis based on porphyrin levels, and BPMO (Benzo(a)pyrene MonoOxygenase) and EROD (Ethoxyresorufin-O-deethylase) activities. Porphyrin levels and EROD and BPMO activities were found to be generally low. In contrast to previous years, no statistically significant difference was found between the potentially contaminated cove and the control cove after the Italian expedition had been active nearby for a period of one month. This indicates a marked decrease in certain types of contaminants such as organochlorines and trace metals, mainly due to improvements in waste disposal.     

A study of metal and metalloid contaminant availability in Antarctic marine sediments

Previous studies of impacted sites near Casey Station, Antarctica, have revealed elevated concentrations of metals and metalloids, particularly Cd, Cu, Fe, Pb, Sn and Zn in marine sediments. However, attempts to understand the availability and mobility of contaminant elements have not provided a true understanding of speciation. The current work shows, for the first time, that sediments in Brown Bay, an embayment adjacent to the Thala Valley waste disposal site, have elevated concentrations of sulfide, well in excess of that required to bind contaminant metals such as Cd, Cu, Pb and Zn. Furthermore, sediment characterisation using the BCR sequential extraction scheme has shown metal partitioning consistent with sulfides being the controlling factor in metal availability, thus explaining the low porewater concentrations of these metals. The speciation of Sn in Brown Bay, however, is still unclear with the BCR sequential extraction scheme partitioning Sn predominantly into the residual fraction despite Sn being readily extracted by dilute HCl.     

Volatile chlorinated hydrocarbons in Antarctic superficial snow sampled during Italian ITASE expeditions

In order to detect the presence of some volatile chlorinated hydrocarbons (VCHCs) and to understand their transport and deposition mechanism, superficial snow was sampled during two Italian ITASE (International Trans Antarctic Scientific Expedition) expeditions: the first traverse was carried out in 1998/1999 from Terra Nova Bay to Dome Concordia; the second traverse was carried out in 2001/2002 through Adélie, George V, Oates and Northern Victoria Lands. Some VCHCs (chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) were analysed using a highly sensitive and selective hyphenated technique composed of a purge-and-trap injector coupled to a gas chromatograph with a mass spectrometric detector (PTI-GC-MS) operating in SIM mode. Investigated VCHCs were present in all analysed snow samples with concentration levels of several units, tens, or sometimes hundreds of ng kg(-1). VCHC snow concentration levels remained approximately constant with changing distance from the coast and the comparison between fresh and aged snow did not show any substantial differences; on the basis of this evidence marine aerosol and dry deposition may be rejected as principal VCHC transport and deposition mechanism hypotheses. VCHC concentration levels in Antarctic snow samples were comparable to or greater than those found in snow from temperate zones.     

P and trace metal contents in biomaterials, soils, sediments and plants in colony of red-footed booby (Sula sula) in the Dongdao Island of South China Sea

Concentrations of P and trace metals Zn, Cu, Cd, Pb and Hg in the faeces, bones, eggshells and feathers of seabirds and in the plants, soils and sediments with and without seabird influence on Dongdao Island, South China Sea, were determined and analyzed. Among the seabird biomaterials, the levels of P, Zn, Cu and Cd are the highest in the droppings and several times those in other materials; the Hg concentration is the highest in the feathers; and the Pb content is comparable among these biomaterials. These marked differences indicate different intake-bioaccumulation-elimination pathways for different trace metals. The levels of P, Zn, Cu, Cd and Hg in the plant, soil and sediment samples with the influence of seabird droppings are significantly higher than those in the samples without, and they are significantly correlated with each other. Thus, P, Zn, Cu, Cd and Hg are very likely to have a common source-predominantly bird guano-and the faeces of red-footed booby is an important vector for the flux of nutrient phosphorus and trace metals Zn, Cu, Cd and Hg from marine to island ecosystems on Dongdao Island.     

Speciation of metals in contaminated sediments from Oskarshamn Harbor,Oskarshamn, Sweden

Bottom sediments in coastal regions have been considered the ultimate sink for a number of contaminants, e.g., toxic metals. In this current study, speciation of metals in contaminated sediments of Oskarshamn harbor in the southeast of Sweden was performed in order to evaluate metal contents and their potential mobility and bioavailability. Sediment speciation was carried out by the sequential extraction BCR procedure for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn and the exchangeable (F1), reducible (F2), oxidizable (F3), and residual (R) fractions were determined. The results have shown that Zn and Cd were highly associated with the exchangeable fraction (F1) with 42–58 % and 43–46 %, respectively, of their total concentrations in the mobile phase. The assessment of sediment contamination on the basis of quality guidelines established by the Swedish Environmental Protection Agency (SEPA) and the Italian Ministry of Environment (Venice protocol for dredged sediments) has shown that sediments from Oskarshamn harbor are highly contaminated with toxic metals, especially Cu, Cd, Pb, Hg, As, and Zn posing potential ecological risks. Therefore, it is of crucial importance the implementation of adequate strategies to tackle contaminated sediments in coastal regions all over the world.     

Evaluation of diffusive gradients in thin film (DGT) samplers for measuring contaminants in the Antarctic marine environment

This work has been the first application of DGT samplers for measuring metals in water and sediment porewater in the Antarctic environment, and whilst DGT water sampling was restricted to quantification of Cd, Fe and Ni, preconcentration using Empore chelating disks provided results for an additional nine elements (Sn, Pb, Al, Cr, Mn, Co, Cu, Zn, As). Although higher concentrations were measured for some metals (Cd, Ni, Pb) using the Empore technique, most likely due to particulate-bound or colloidal species becoming entrapped in the Empore chelating disks, heavy metal concentrations in the impacted Brown Bay were found to be comparable with the non-impacted O'Brien Bay. Sediment porewater sampling using DGT also indicated little difference between Brown Bay and O'Brien Bay for many metals (Cd, Al, Cr, Co, Ni, Cu), however, greater amounts of Pb, Mn, Fe and As were accumulated in DGT probes deployed in Brown Bay compared with O'Brien Bay, and a higher accumulation of Sn was observed in Brown Bay inner than any of the other three sites sampled. Comparison of DGT derived porewater concentrations with actual porewater concentrations showed limited resupply of Cd, Pb, Al, Cr, Mn, Co, Ni, Cu, Zn and As from the solid phase to porewater, with these metals appearing to be strongly bound to the sediment, however, resupply of Fe and Sn was apparent. Based upon our observations here, we suggest that Sn, and to a lesser extent Pb, are critical contaminants.     

Characterization of polychlorinated dibenzo-p-dioxins and dibenzofurans in different particle size fractions of marine sediments

The distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was examined according to particle size in marine sediments, with a particular focus on fine particulates. Samples from different coastal sites were fractionated into five size groups (<2, 2-5, 5-10, 10-20, and 20-63 microm diameter) by gravitational split-flow thin fractionation. Despite the different size profiles and PCDD/F contents of the sediments at each site, PCDD/F levels in fractionations tended to increase as the particle size decreased; the PCDD/F levels in the finest particles were up to 16 times higher than in the coarsest particles, which was associated with their organic carbon contents. Log normalization showed high levels of PCDD/Fs in the fine silt particles (2-10 microm), which are consumable by aquatic biota. Because of the different toxicity and bioavailability of PCDD/Fs in different sediment particle sizes, it is important to study particle actions to understand their effects on the aquatic ecosystem.     

Taiwan's industrial heavy metal pollution threatens terrestrial biota

The bioconcentration levels of essential (Cu, Fe, Mg, Mn, and Zn) and non-essential (As, Cd, Hg, Pb, and Sn) elements have been investigated in different terrestrial biota such as fungi, plant, earthworm, snail, crab, insect, amphibian, lizard, snake, and bat including the associated soil, to investigate the ecosystem health status in Kenting National Park, Taiwan. High bioconcentrations of Cd, Hg, and Sn in snail, earthworm, crab, lizard, snake, and bat indicated a contaminated terrestrial ecosystem. High concentrations of Cd, Hg, and Sn in plant species, effective bioaccumulation of Cd by earthworm, snail, crab and bat, as well as very high levels of Hg found in invertebrates, amphibians, and reptiles revealed a strong influence from industrial pollution on the biotic community. This study for the first time presents data on the impact of heavy metal pollution on various terrestrial organisms in Taiwan.     

Benthic foraminifera and heavy metals distribution: a case study from the Naples Harbour (Tyrrhenian Sea, Southern Italy)

The analysis of 90 surficial sediments from three docks of the Naples Harbour (Levante, Granili, and Diaz) permits to compare the distribution modes of heavy metals with grain sizes, total organic carbon content (TOC) and distribution patterns of benthic foraminifera. Foraminiferal density and species richness decrease with the increasing toxic elements concentrations from the Levante to the Diaz dock. Median concentrations of Ni, Pb, Zn, and Hg (medians of 21.43 mg/kg, 270.24 mg/kg, 489.65 mg/kg, and 1.18 mg/kg, respectively) were reported for the Diaz dock where foraminifera are absent, thus suggesting a possible impact of toxic elements on the benthic ecosystem balance. Compared to the unpolluted marine sediments of the Granili dock, the Levante area shows higher heavy metals levels and a quasi-oligotypic benthic assemblage. This is dominated by the tolerant species Ammonia tepida that may be used as bio-indicator of pollution of anthropised marine sediments.     

Trace metals in flounder, Platichthys flesus (Linnaeus, 1758), and sediments from the Baltic Sea and the Portuguese Atlantic coast

Trace metals were examined in the muscle tissue of flatfish species of flounder, Platichthys flesus (Linnaeus, 1758), sediments from two southern Baltic Sea sites (Gdańsk Bay and Ustecko-?ebskie as a reference) and in two areas of the Portuguese Atlantic coast (Douro River estuary and Atlantic fishing ground as a reference) to evaluate spatial differences in trace metals. Additionally, the accumulation of trace metals in flounder of different length classes was assessed. Flounder from the Gdańsk Bay area contained twofold more cupper (Cu), lead (Pb) and mercury (Hg) than did flounder from the Douro River estuary, but zinc (Zn) and cadmium (Cd) were at similar concentrations. The sediments from Gdańsk Bay contained significantly more Zn and threefold more Cd, while concentrations of Cu and Pb were twofold lower. The concentrations of metals in the sediments did not correlate with those in the flounder. Spatial differences were noted in metal concentrations in flounder from the southern Baltic Sea and the Portuguese Atlantic coast as well as within these regions, with higher concentrations in the flounder from the Baltic Sea Gdańsk Bay. The flounder in length class 25–30 cm from Gdańsk Bay contained metal concentrations comparable to those of class 40–45 cm specimens from the Atlantic coast. The accumulation of metals in flounder length classes differed in the two regions.     

Distribution and fractionation of heavy metals in the Tisa (Tisza) River sediments

Introduction In this work, sediments of the River Tisa (Tisza) are studied to assess their environmental pollution levels for some major heavy metals, as well as to predict the investigated elements’ mobility on the basis of their association type with the substrate. The Tisa River catchments area is a subbasin of the River Danube. Part of this river, 166 km long, belongs to the Serbian province of Vojvodina, before it flows into the Danube. It has been chosen for our investigation, because it has been exposed to intense pollution in the last decades. Materials and Methods The river sediment samples were collected at 32 locations. The proportions of sand, silt and clay fractions were determined. The sequential extraction procedure following a modified Tessier method was applied for speciation of the metal forms in the collected samples. The metal concentrations of Zn, Cd, Pb, Ni, Cu, Cr, Fe and Mn in extracts were determined by atomic absorption spectroscopy. Results and Discussion Granulometric analysis showed that some 50% of the Tisa River sediments were silt and clay, while the rest was sand with quartz, as the main constituent. The average metal content of the surface river sediment samples for every fraction of sequential extraction was presented and discussed in relation to pH, Eh and metal fractionation. The average metal content from the Tisa River sediments, obtained as an average of the metal’s concentration released in all five sequential extraction fractions was compared with: average metal contents of the Tisa River sediments in Hungary, metal content in soils formed on the Tisa River alluvium of Vojvodina, average metal content in soils of Vojvodina, and average metal content in soils of Hungary. An assessment of metal pollution levels in Tisa River sediments was made by comparing mean values for obtained results for the Tisa River sediments with the freshwater sediment’s Quality Guidelines as published by US EPA, Environment Canada and soil standards for Serbia. Conclusion According to US EPA and Canadian Quality Guidelines for freshwater sediments, the concentration of heavy metals in Tisa sediments were: (a) much higher than defined concentrations below which harmful effects on river biota are unlikely to be observed, (b) below defined concentrations above which harmful effects on river biota are likely to be observed. The concentration levels of Pb, Ni, Cu and Cr in Tisa River sediments are safe when compared with Serbian MAQ (Maximum Allowed Quantity) standards for soils, but they are unsafe in the case of Zn and Cd. Recommendations and Outlook The quality of sediments in the Tisa River was on the border line between potentially polluted and polluted. This line could very easily be exceeded since the quality of sediments in the Tisa River in Hungary was already worse than in Serbia. These results indicated the need for further monitoring of heavy metals in that locality.     

胶州湾表层沉积物重金属污染分布特征及其生态风险评价

根据2009年对胶州湾东岸表层沉积物中重金属调查结果,对重金属含量分布及富集特征进行分析,并采用潜在生态危害指数(RI)法对其生态危害程度进行评价。结果表明,胶州湾东岸表层沉积物中的重金属含量,除7月的Cu、Cr平均含量略低于12月外,其他重金属(Cd、Zn、Pb、As)平均含量7月均高于12月。在表层沉积物中Cd的污染程度最高,7月平均污染指数达1.68。单个重金属潜在生态危害系数(Eir)表明,Cd的Eir大于其他重金属的Eir,其他重金属的Eir均小于轻微危害程度的划分标准,表明对胶州湾东岸生态环境具有潜在影响的重金属主要是Cd,从多个重金属的RI均值看,均小于150,属于轻微生态危害。     

Influence of sediment acidification on the bioaccumulation of metals in Ruditapes philippinarum

Background, aim and scope

The influence of pH (range 6.5–8.5) on the uptake of Zn, Cd, Pb, Cu, Ni, Cr, Hg, and As by juveniles of the clam Ruditapes philippinarum was examined in order to understand whether variation in sediment pH has significant repercussions on metal bioaccumulation.

Materials and methods

Clams were exposed to sediments collected in three locations in the Gulf of Cadiz (Huelva, Guadalquivir and Bay of Cadiz) and to contaminated particles derived from an accidental mining spill in Spain.

Results

With a notable exception of metal Cd, the concentration of metals within clams significantly increased (p?<?0.1) when sediment pH was lowered by one or two units. Moreover, the magnitude of this effect was dependent on the type of sediment contamination.

Discussion

Lower pH increases metal solubility and reduces or invert the metal sorption of metals to sediments. Increases in free metal ions in water favors metal uptake by clams, hence pH is an important factor controlling the mobility of these metals within sediments and their subsequent bioaccumulation within biota. Although sediment-water exchange of Cd can increase with acidification, this excess may be counterbalanced by the presence of ligands in seawater preventing the uptake by organism. Besides chlorines, Cd has also an affinity with carbonates and other ligands present in sea water. These Cd-carbonate complexes may reduce the bioavailable to organisms.

Conclusions

These results highlight the potential implications of sediment acidification, either due to the storage excess of organic matter or to the forced capture of CO₂, on the increasing metal availability to benthic organisms.

Recommendations and perspectives

This kind of studies should be increased to address the influence of acidification in the behavior, bioavailability, toxicity, and risk assessment of contaminants associated with sediments either above sub-seabed geological formations in marine environments or in high enriched by organic matter in estuarine areas. Recently, the capture of CO₂ in marine environments has been approved and started; it is necessary to address the potential impacts associated with leakages or other events occurring during the procedure of injection and storage of CO2.     

Lead and zinc in sediments and biota from Maarmorilik, West Greenland: an assessment of the environmental impact of mining wastes on an Arctic fjord system

Lead and zinc levels in sediments and biota from the fjord system surrounding the lead/zinc mine at Maarmorilik, West Greenland, were investigated to evaluate the impact of waste rock and marine-deposited tailings on the marine biota. Concentrations of metal in the sediment were up to 8,922 +/- 622 microg g(-1) (dry wt.) for lead and 19,351+/- 476 microg g(-1) (dry wt.) for zinc. Levels of lead and zinc were also elevated in a suite of monitor organisms. The feeding modes of the organisms were used to explain the sources of metals to the organisms. After closure of the mine, the concentrations of metals in the upper centimetres of the sediments decreased, and a decreased impact of metals on the brown alga Fucus distichus was observed. However, the metals in the sediments still affect the marine biota in the area.     

Arsenic and mercury bioaccumulation in the aquatic plant, Vallisneria neotropicalis

Arsenic (As) and mercury (Hg) are among the most toxic metals/metalloids. The overall goal of this study was to investigate the bioaccumulation of these trace elements in Vallisneria neotropicalis, a key trophic species in aquatic environments. For this purpose, As and Hg concentrations were determined in sediments and natural populations of V. neotropicalis in sub-estuaries of Mobile Bay (Alabama, USA), differing with respect to past and present anthropogenic impact. Analyses indicate that the Fish River is the most contaminated among the sub-estuaries investigated; levels of As found in Fish River sediments fall within a range that could potentially cause adverse effects in biota. Sediment As concentrations were only moderately correlated with those in V. neotropicalis; no correlation was found between sediment and plant Hg levels. However, several parameters could have masked such potential relationships (e.g., differences in sediment characteristics and “biological dilution” phenomena). Results presented herein highlight the numerous parameters that can influence metal/metalloids accumulation in aquatic plants as well as species-specific responses to trace element contamination. Finally, this study underscores the need for further investigation into contaminant bioaccumulation in ecologically and economically important coastal environments.     

Metal concentrations in Kandalaksha Bay, White Sea (Russia) following the spring snowmelt

Elevated concentrations of dissolved and particulate Cd, Cu, Pb and Zn have been determined in the waters of Kandalaksha Bay (White Sea, Russia), following the ice melt in the spring of 2000. Dissolved metal maxima in the surface waters were observed at some stations and concentrations generally decreased with depth. The suspended particulate matter (SPM) comprised a non-lithogenic fraction in the range 12-83%, and had elevated metal concentrations that showed no trend with depth or salinity and was compositionally distinct from the sediments. A log-linear relationship existed between the concentrations of metals in sediments and in SPM and their respective Al concentrations, indicating a source of metal-rich particles, with low Al content, to the Bay. The results suggest that Kandalaksha Bay has been impacted by industrial activity on the Kola Peninsula and that restricted water exchange will hinder its recovery from metal contamination.     

Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent.     

Major, minor and trace element content derived from aquacultural activity of marine sediments (Central Adriatic, Croatia)

Introduction and purpose

Studies examining the environmental impact of marine aquaculture have increased significantly in number during the last few decades. The present paper investigates a region of rapid growth in intensive aquaculture and its influence on the local marine ecosystem.

Discussion

This study was undertaken with the specific aim of assessing the effect of fish farming on marine sediment at a farm near the island of Vrgada in the Central Adriatic. Data obtained regarding major (Si, Al, K, Na, Fe, Ca, Mg), minor (Mn, P, Ti) and trace (As, Au, Ba, Cd, Co, Cr, Cs, Cu, Ga, Hf, Hg, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Se, Sr, Ta, Th, Tl, U, V, Y, Zn, Zr) elements were used to estimate the spatial and temporal distribution of metals in the sediment and their possible relationship with local aquacultural activity.

Results

Although the measured concentrations of heavy metals in sediment below fish cages were notably different and potentially a result of farming activity, the values were generally lower than background concentrations observed in the Central Adriatic. In contrast, concentrations of heavy metals at a reference site unaffected by aquaculture varied from lower levels to values even higher than those observed below the high-production cages. Furthermore, calculated environmental index values indicate that the sediment below the farm is either uncontaminated or suffers from only low levels of contamination.

Conclusion

Such results suggest that the effect of observed fish farm activity on the local marine ecosystem is practically negligible.     

Trace elements in two odontocete species (Kogia breviceps and Globicephala macrorhynchus) stranded in New Caledonia (South Pacific)

Liver, muscle and blubber tissues of two short-finned pilot whales (Globicephala macrorhynchus) and two pygmy sperm whales(Kogia breviceps) stranded on the coast of New Caledonia have been analysed for 12 trace elements (Al, Cd, Co, Cr, Cu. Fe, organic and total Hg, Mn, Ni, Se, V, and Zn). Liver was shown to be the most important accumulating organ for Cd, Cu, Fe, Hg, Se, and Zn in both species, G. macrorhynchus having the highest Cd, Hg, Se and Zn levels. In this species, concentrations of total Hg are particularly elevated, reaching up to 1452 microg g(-1) dry wt. Only a very low percentage of the total Hg was organic. In both species,the levels of Hg are directly related to Se in liver. Thus, a molar ratio of Hg:Se close to 1.0 was found for all specimens, except for the youngest K. breviceps. Our results suggest that G. macrorhynchus have a physiology promoting the accumulation of high levels of naturally occurring toxic elements. Furthermore, concentrations of Ni, Cr and Co are close to or below the detection limit in the liver and muscles of all specimens. This suggests that mining activity in New Caledonia, which typically elevates the levels of these contaminants in the marine environment, does not seem to be a significant source of contamination for these pelagic marine mammals.     

Twentieth century overview of heavy metals in the Galician Rias (NW Iberian Peninsula)

The 18 Galician Rias, comprising 25% of the Iberian Peninsula coastline, form a unique system within the European continental Atlantic coast and provide a useful reference area for studies of metals. These rias are sensitive to anthropogenic influence due to the socioeconomic importance generated in these areas by industry, aquaculture, port activities, fishing, tourism and, accordingly, several islands lying within close proximity to the rias have recently been declared natural parks. Aquaculture in the Galician Rias is a growth industry and in 2000 the rias supported 3386 mussel rafts producing 2.5 x 10(8) kg year(-1), i.e. 40% of European Union total seafood production. The Galician Rias are partially stratified estuaries with positive residual circulation with fresh (runoff lower than 100 m3 s(-1) and salt water mixing inside the basins. This behaviour has direct consequences on metal fluxes whereby the rias behave as a barrier and accumulate metals in the sediments. Metals tend to deposit close to point sources and remobilization occurs inside the ria, leading to a seaward decrease in metal concentration. With the exception of the Ulla (Arosa Ria) and Eume (Ares-Betanzos Ria) head rivers and the Lagares river (Vigo Ria) the available data suggest that riverine freshwater inputs are not the main source of contamination. Metal studies reported in the literature mainly relate to Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, and to a lesser extent Hg and Sn. Studies of other harmful metals such as Ag, Se and As are notably lacking. In addition, the studies have been localized and mainly restricted to the surface sediment. Data of heavy metals in the dissolved phase, suspended particulate matter and biota is scarce in the mainstream literature and should be considered in the future research. From the entire Galician coast, data from seven rias of socio-economic importance form the bulk of the published work. There is an urgent need to standardize procedures, employ 'clean' procedures to avoid contamination of samples and regular assessment of analytical accuracy with CRMs in order that results can be compared among the scientific community and produce reliable results. The continuation of coastal environmental studies requires an enlargement of the sampling locations as well as systematic and periodic analysis of known pollution sources in order to decide whether coastal regeneration action is needed. Studies dedicated to metals in the water column are lacking and need more attention in future research. The majority of the available data correspond to the fluvial front (30%) at ria head and, to a lesser extent, to the oceanic front (3%), under summer upwelling events. Current awareness of the rias suggests that they are not contaminated although there is some evidence of important localized anthropogenically induced enrichments at the outflow of the Lagares River (Pb, Zn), the San Simón inlet (Pb) and near to the harbor (Pb, Zn, Cu) in the Vigo Ria, the inner part (Cu, Zn, Hg, Pb) of the Pontevedra Ria, the Ulla River estuary (Cu, Cr, Mn, Ni; Zn) in the Arosa Ria, the inner zone (Cu, Pb, Zn) of the Coru?a Ria, the Ferrol Ria (Zn) and the Eume Estuary (Zn, Mn, Ni, Co) in the Ares-Betanzos Ria. In addition, TBT enrichment has been found along the Galician coast, being highest in the industrial bays (Vigo, Coru?a and Ferrol). Nevertheless, it is important to point out the lack of information concerning the relationship between metal concentrations in different fractions of sediments and/or water and their bioavailability and toxicity on biota in order to confirm metal contamination dangers. The present paper reviews all the information published on metals in the rias up to the year 2000 and takes a biogeochemical standpoint, i.e. metal presence in the ria reservoirs: water column, suspended particulate matter, sediments and biota, as well as the fluvial and oceanic frontiers.