Evaluating trace element bioavailability and potential transfer into marine food chains using immobilised diatom model species Phaeodactylum tricornutum, on King George Island, Antarctica

Mercury concentrations in Antarctic zooplankton with a focus on the krill species, Euphausia superba

The Antarctic is the most isolated region in the world; nevertheless, it has not avoided the negative impact of human activity, including the inflow of toxic mercury (Hg). Hg deposited in the Antarctic marine environment can be bioavailable and accumulate in the food web, reaching elevated concentrations in high-trophic-level biota, especially if methylated. Zooplankton, together with phytoplankton, are critical for the transport of pollutants, including Hg to higher trophic levels. For the Southern Ocean ecosystem, one of the key zooplankton components is the Antarctic krill Euphausia superba, the smaller euphausiid Thysanoessa macrura, and the amphipod Themisto gaudichaudii - a crucial food source for most predatory fish, birds, and mammals. The main goal of this study was to determine the Hg burden, as well as the distribution of different Hg forms, in these dominant Antarctic planktonic crustaceans. The results showed that the highest concentrations of Hg were found in T. gaudichaudii, a typically predatory taxon. Most of the Hg in the tested crustaceans was labile and potentially bioavailable for planktivorous organisms, with the most dangerous methylmercury (MeHg) accounting for an average of 16 % of the total mercury. Elevated Hg concentrations were observed close to the land, which is influenced by the proximity to penguin and pinniped colonies. In areas near the shore, volcanic activity might be a possible cause of the increase in mercury sulfide (HgS) content. The total Hg concentration increased with the trophic position and ontogenetic stage of predation, specific to adult organisms. In contrast, the proportion of MeHg decreased with age, indicating more efficient demethylation or elimination. The Hg magnification kinetics in the study area were relatively high, which may be related to climate-change induced alterations of the Antarctic ecosystem: additional food sources and reshaped trophic structure.

Antarctic heavy metal pollution and remediation efforts: state of the art of research and scientific publications

In Antarctica, human activities have been reported to be the major cause of the accumulation of heavy metal contaminants. A comprehensive bibliometric analysis of publications on heavy metal contamination in Antarctica from year 2000 to 2020 was performed to obtain an overview of the current landscape in this line of research. A total of 106 documents were obtained from Scopus, the largest citation database. Extracted data were analysed, and VOSviewer software was used to visualise trends. The result showed an increase in publications and citations in the past 20 years indicating the rising interest on heavy metal contamination in the Antarctic region. Based on the analysis of keywords, the publications largely discuss various types of heavy metals found in the Antarctic water and sediment. The analysis on subject areas detects multiple disciplines involved, wherein the environmental science was well-represented. The top countries and authors producing the most publication in this field were from Australia, China, Brazil and Chile. Numerous efforts have been exercised to investigate heavy metal pollution and its mitigation approaches in the region in the past decades. This paper not only is relevant for scholars to understand the development status and trends in this field but also offers clear insights on the future direction of Antarctic heavy metal contamination and remediation research.

Ecological risk assessment and phytomanagement of trace metals in the sediments of mangroves associated with the Ramsar sites of Kerala, southern India

The study investigated trace metal accumulation in the sediments of three major mangrove ecosystems associated with the Ramsar sites of Kerala state, the ecological risks they pose, and the absorption, accumulation, and translocation of metals in five dominant mangrove species, as these systems are heavily impacted by anthropogenic interventions. The trace metal concentrations (mg kg^-1) in the sediment of different mangrove habitats of Kerala ranged from 20 to 295 for Cu, 65 to 350 for Zn, 72 to 151 for Pb, 11 to 210 for Ni, 42 to 228 for Mn, 0 to 6 for Cd,124 to 565 for Cr, and 0 to 2.9 for Ag. An overall enrichment of metals was recorded in sediment, exceeding the prescribed effects range median (ERM) of consensus-based sediment quality guidelines (SQGs) for Cu and Cr concentrations at Munroe Island and Ni at Vypin, indicating a detrimental risk to biota in the sediments. Principal component analysis and a higher geoaccumulation index indicated the contribution of trace metals from industries, agricultural runoff, and urban waste disposal. The ecological risk index suggested that cadmium poses a very high risk to the mangrove ecosystem at Vypin. Furthermore, the bioconcentration factor for various trace metals in Avicennia marina and Lumnitzera racemosa in Ayiramthengu was > 2, suggesting that these species can accumulate trace metals, particularly Cr, Cd, and Pb. Further, our findings suggest that A. marina may be considered as an efficient metal trap for Cd in aerial parts, as indicated by the significant translocation factor (> 1) combined with the bioconcentration factor. Therefore, the study revealed that Munroe island and Vypin had a considerable level of contamination for toxic metals and Avicennia marina could be a promising candidate species for the phytoremediation of these trace metals in the coastal settings of Kerala state.

Baseline concentrations, spatial distribution and origin of trace elements in marine surface sediments of the northern Antarctic Peninsula

Increased human activity in the Antarctic Peninsula combined with accelerated melting of its glaciers highlights the importance of monitoring trace element concentrations. Surface sediment samples were collected around King George Island, Hope Bay and in the Bransfield Strait in February 2020 and were analysed by X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry. The methods display a good correlation. Our results show clear distinctions between these regions for selected elements with high local heterogeneities. Hope Bay exhibited lower concentrations of Fe, Mn, Co, V, Zn while most stations in the Bransfield Strait and around King George Island showed moderate to significant enrichment in Cu, As and Cd. Twelve stations presented a moderate ecological risk. The consistency of our values supports a natural rather than anthropogenic origin, possibly related to volcanism and the geology of the area. However, our results suggest an increase in Cr that should be further investigated.

The microalga Phaeocystis antarctica is tolerant to salinity and metal mixture toxicity interactions

Salinity in the Antarctic nearshore marine environment is seasonally dynamic and climate change is driving greater variability through altered sea ice seasons, ocean evaporation rates, and increased terrestrial ice melt. The greatest salinity changes are likely to occur in the nearshore environment where elevated metal exposures from historical waste or wastewater discharge occur. How salinity changes affect metal toxicity has not yet been investigated. This study investigated the toxicity of cadmium, copper, nickel, lead, and zinc, and their equitoxic mixtures across a salinity gradient to the Antarctic marine microalga Phaeocystis antarctica. In the metal-free control exposures, algal population growth rates were significantly lower at salinities <20 PSU or >35 PSU compared to the control growth rate at 35 PSU of 0.60 ± 0.05 doublings per day and there was no growth below 10 or above 68 PSU. Salinity-induced changes to metal speciation and activity were investigated using the WHAM VII model. Percentages of free ion activity and metal-organic complexes increased at decreasing salinities while the activity of inorganic metal complexes increased with increasing salinities. Despite metal speciation and activity changes, toxicity was generally unchanged across the salinity gradient except that there was less copper toxicity and more lead toxicity than model predictions at salinities of 15 and 25 PSU and antagonistic interactions in metal-mixture treatments. In mixtures with and without copper, it was shown that copper was responsible for ∼50% of the antagonism from observed toxicity at salinities below 45 PSU. Across all treatments, using different metal fractions in toxicity models did not improve toxicity predictions compared to dissolved metal concentrations. These results provide evidence that P. antarctica is unlikely to be at a greater risk from metal contaminants as a result of salinity changes.

Seabirds enrich Antarctic soil with trace metals in organic fractions

Coastal areas of Antarctica are subjected to anthropic contamination from around the world by trace metals biotransported and accumulated by seabird excrements. To explore this hypothesis, this study investigated the influence of seabirds on the contents of trace metals in soil organic fractions from Antarctica under different climatic conditions and from different parent materials. For this, soil profiles from the Maritime Antarctica region were selected based on the criteria of ornithogenesis, parent material, and climate. The contents of C, N, and selected metals (Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn) were analysed in the organic matter associated with minerals (MAOM), the particulate fraction (POM), and in the total soil (MAOM + POM). The ornithogenic soils presented the highest amounts of C and N in the soil, MAOM, and POM as compared to nonornithogenic soils. Seabird activity resulted in an enrichment of Pb, Zn, and Cu. Among these biotransported metals, Cu and Zn seem to originate from natural biogenic processes in marine food chains, unlike Pb, which seems to come from anthropogenic sources. The soils developed from igneous rocks presented higher amounts of Ba, Co, Cu, Fe, Mn, and Sr in the soil, MAOM, and POM than soils from sedimentary rocks. The climate had no clear effect on most metals. Hence, seabirds enrich soils, MAOM, and POM with Cu, Zn, and Pb, whereas the amounts of Ba, Co, Cr, Fe, Mn, Ni, and Sr are mainly lithogenic, associated with the parent material. Monitoring biotransported trace metals in ornithogenic soils is of great importance, since they can create environmental toxicity to terrestrial plants and animals and can influence the food chain in the coastal areas of Antarctica.

Distribution of trace elements in benthic infralittoral organisms from the western Antarctic Peninsula reveals no latitudinal gradient of pollution

Antarctica is considered one of the most pristine regions on Earth, but evidences of global and local anthropogenic pollution exist. Chromium (Cr), lead (Pb) and mercury (Hg) are bioaccumulated and sometimes biomagnified through the trophic web. We aim to determine whether a latitudinal gradient of these trace elements exists in benthic organisms along the rocky shores of the Antarctic Peninsula and the South Shetland Islands. Levels of Cr, Pb, and Hg were measured by ICP-MS in two macroalgae (Palmaria decipiens and Desmarestia anceps or Desmarestia menziesii), one gastropod (Nacella concinna), two starfishes (Odontaster validus and Diplasterias brucei), and suspended particulate organic matter (SPOM) from five sampling sites ranging in latitude from 62°11'17″S to 67°33'47″S. Levels of trace elements differed among sites and species, but no latitudinal gradient was observed for these pollutants. Levels of Hg and Pb in animals were consistent with biomagnifications along the food web, as were higher is starfish than in limpets. However, macroalgae and SPOM are unlikely to be the main primary producers supporting those consumers, as Hg levels in macroalgae and Pb levels in SPOM were much higher than in animals. The levels of trace elements detected were similar or higher than in other Antarctic places and other regions of the world, thus indicating that the Antarctic Peninsula area is as polluted as the rest of the world.

Biomonitoring Assessment of Toxic and Trace Elements in Sterechinus neumayeri Sea Urchins from the Comandante Ferraz Station in Antarctica

In the present study, sea urchin Sterechinus neumayeri tissues were used for the passive biomonitoring of toxic and trace elements at the Comandante Ferraz Station, Antarctica and compared to a pristine region (Botany). As, Ba, Br, Ca, Co, Cr, Fe, K, Na, Rb, Sc, Se and Zn concentrations were determined by instrumental neutron activation analysis (INAA), while toxic metals (Cd, Hg, Ni and Pb), and Cu were determined by atomic absorption spectrometry (GF-AAS). The findings were compared to other organisms commonly applied for biomonitoring purposes and to the sediment concentrations of each sampling region. Urchins from the Ferraz Station area presented higher Br, Co, Cr, Cs, K, Se and Zn levels than the pristine location. The results obtained herein suggest S. neumayeri can be applied to the biomonitoring of Cr and Zn. The present study also contributes to knowledge of the mineral composition of the sea urchin S. neumayeri.

First screening of biocides, persistent organic pollutants, pharmaceutical and personal care products in Antarctic phytoplankton from Deception Island by FT-ICR-MS

In recent years, the Antarctic territory has seen a rise in the number of tourists and scientists. This has led to an increase in the anthropogenic footprint in Antarctic ecosystems, namely in terms of emerging contaminants, such as Biocides, Persistent Organic Pollutants (POPs) as well as Pharmaceutical and Personal Care Products (PPCPs). Yet scarce information on the presence of these emerging contaminants is available for trophic compartments, especially the phytoplankton community. Using high resolution Fourier-transform ion cyclotron-resonance mass spectrometry (FT-ICR-MS), an untargeted screening of the metabolome of the phytoplankton community was performed. Seventy different contaminant compounds were found to be present in phytoplankton collected at two sites in Port Foster Bay at Deception Island. These emerging contaminants included 1 polycyclic aromatic hydrocarbon (PAH), 10 biocides (acaricides, fungicides, herbicides, insecticides and nematicides), 11 POPs (flame retardants, paints and dyes, polychlorinated biphenyl (PCB), phthalates and plastic components), 5 PCPs (cosmetic, detergents and dietary compounds), 40 pharmaceutical compounds and 3 illicit drugs. Pharmaceutical compounds were, by far, the largest group of emerging contaminants found in phytoplankton cells (anticonvulsants, antihypertensives and beta-blockers, antibiotics, analgesic and anti-inflammatory drugs). The detection of several of these potentially toxic compounds at the basis of the marine food web has potentially severe impacts for the whole ecosystem trophic structure. Additionally, the present findings also point out that the guidelines proposed by the Antarctic Treaty and Protocol on Environmental Protection to the Antarctic Treaty should be revisited to avoid the proliferation of these and other PPCPs in such sensitive environments.

Assessing metal contaminants in Antarctic soils using diffusive gradients in thin-films

Metal contaminants in Antarctic soils are typically found around research stations which are concentrated in ice-free coastal areas. The risk of these contaminants to the Antarctic environment is not well understood, given Antarctica's unique organisms and climate. This study assessed the use of diffusive gradients in thin-films (DGT), a passive sampler that measures fluxes of labile metals from soils to porewaters, in Antarctic soils. DGT-labile measurements were compared to three chemical extractants of increasing strength including high-purity water, dilute acid (1 M HCl), and concentrated acids (3:1 v/v HNO₃:HCl), to understand differences in contaminant geochemistry that may affect environmental risk. One site had high lead concentrations measured with dilute (114 ± 4 mg kg^-1) and concentrated (150 ± 10 mg kg^-1) acids, while DGT-labile concentrations were below the method detection limit (0.5 μg L^-1), indicating that the lead species has low solubility or lability. Another site had low concentrations of zinc measured by dilute (36.2 ± 0.5 mg kg^-1) or concentrated (76 ± 6 mg kg^-1) acid extracts, but had high DGT-labile concentrations (350 ± 80 μg L^-1). This reflects an active source of zinc supplied from soil to pore water over time. Copper was found to be acid extractable, water-soluble, and DGT-labile, with DGT-labile concentrations of up to 12 μg L^-1. Despite the soil and metal-specific geochemical differences, any of the extracts could be used with statistical clustering techniques to identify differences in sites with elevated metal concentrations. This study shows that the DGT-method can identify contaminated sites comparably to chemical extracts but provides environmentally relevant measurements of metal contaminant lability in Antarctic soils.

Oil Bioremediation in the Marine Environment of Antarctica: A Review and Bibliometric Keyword Cluster Analysis

Bioremediation of hydrocarbons has received much attention in recent decades, particularly relating to fuel and other oils. While of great relevance globally, there has recently been increasing interest in hydrocarbon bioremediation in the marine environments of Antarctica. To provide an objective assessment of the research interest in this field we used VOSviewer software to analyze publication data obtained from the ScienceDirect database covering the period 1970 to the present, but with a primary focus on the years 2000–2020. A bibliometric analysis of the database allowed identification of the co-occurrence of keywords. There was an increasing trend over time for publications relating to oil bioremediation in maritime Antarctica, including both studies on marine bioremediation and of the metabolic pathways of hydrocarbon degradation. Studies of marine anaerobic degradation remain under-represented compared to those of aerobic degradation. Emerging keywords in recent years included bioprospecting, metagenomic, bioindicator, and giving insight into changing research foci, such as increasing attention to microbial diversity. The study of microbial genomes using metagenomic approaches or whole genome studies is increasing rapidly and is likely to drive emerging fields in future, including rapid expansion of bioprospecting in diverse fields of biotechnology.

Assessing the Risk of Metals and Their Mixtures in the Antarctic Nearshore Marine Environment with Diffusive Gradients in Thin-Films

Robust environmental assessments and contaminant monitoring in Antarctic near-shore marine environments need new techniques to overcome challenges presented by a highly dynamic environment. This study outlines an approach for contaminant monitoring and risk assessment in Antarctic marine conditions using diffusive gradients in thin-films (DGT) coupled to regionally specific ecotoxicology data and environmental quality standards. This is demonstrated in a field study where DGT samplers were deployed in the near-shore marine environment of East Antarctica around the operational Casey station and the abandoned Wilkes station to measure the time-averaged biologically available fraction of metal contaminants. The incorporation of DGT-labile concentrations to reference toxicity mixture models for three Antarctic organisms predicted low toxic effects (<5% effect to the growth or development of each organism). The comparison of metal concentrations to the Australian and New Zealand default water quality guideline values (WQGVs) showed no marine site exceeding the WQGVs for 95% species protection. However, all sites exceeded the 99% WQGVs due to copper concentrations that are likely of geogenic origin (i.e., not from anthropogenic sources). This study provides evidence supporting the use of the DGT technique to monitor contaminants and assess their environmental risk in the near-shore marine environment of Antarctica.

Impacts of phytoplankton blooms on trace metal recycling and bioavailability during dredging events in the Sado estuary (Portugal)

This work evaluates the impact of phytoplankton blooms on metal availability driven by dredging, in an area of the Sado estuary (Portugal), subject to ongoing dredging operations during the entire sampling period. In situ changes of chlorophyll a concentration, bioavailable trace metals (Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) in the water column, metal content in particulate matter, and particulate metal to bioavailable metal ratios were investigated during pre-bloom, bloom and post-bloom conditions to evaluate the potential of the phytoplankton-mediated metal removal. Metals in particulate matter significantly enhanced concomitantly with the decline of metals (mostly Mn, Co, Cu, Zn, and Pb) in the water column during the bloom, in comparison with pre- and post-bloom periods. During the peak of the phytoplankton bloom, bioavailable Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb were reduced to 30, 99, 100, 87, 98, 72, 84 and 88% of their original levels (pre-bloom values). Copper and Pb, and to a lesser extent, Zn and Mn, were ranked as more particle reactive. Volume particulate matter concentrations of Mn, Ni, Cu and Pb much higher than the bioavailable concentrations, indicated that phytoplankton is likely to be a dominant sink of these metals during the bloom period. Thus, Mn, Ni, Cu and Pb are prone to be transferred and biomagnified into the marine food web. These results highlight phytoplankton blooms as important biological sinks of trace metals during dredging, which should be taken into consideration in planning and management of dredging, to minimise environmental impacts and protect estuarine and coastal ecosystems.

Sources of elevated heavy metal concentrations in sediments and benthic marine invertebrates of the western Antarctic Peninsula

Antarctica is one of the least anthropogenically-impacted areas of the world. Metal sources to the marine environment include localised activities of research stations and glacial meltwater containing metals of lithogenic origin. In this study, concentrations of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were examined in three species of benthic invertebrates collected from four locations near Rothera Research Station on the western Antarctic Peninsula: Laternula elliptica (mudclam, filter feeder), Nacella concinna (limpet, grazer) and Odontaster validus (seastar, predator and scavenger). In addition, metals were evaluated in sediments at the same locations. Metal concentrations in different body tissues of invertebrates were equivalent to values recorded in industrialized non-polar sites and were attributed to natural sources including sediment input resulting from glacial erosion of local granodioritic rocks. Anthropogenic activities at Rothera Research Station appeared to have some impact on metal concentrations in the sampled invertebrates, with concentrations of several metals higher in L. elliptica near the runway and aircraft activities, but this was not a trend that was detected in the other species. Sediment analysis from two sites near the station showed lower metal concentrations than the control site 5 km distant and was attributed to differences in bedrock metal content. Differences in metal concentrations between organisms were attributed to feeding mechanisms and habitat, as well as depuration routes. L. elliptica kidneys showed significantly higher concentrations of eight metals, with some an order of magnitude greater than other organs, and the internal structure of O. validus had significantly higher Ni. This study supports previous assessments of N. concinna and L. elliptica as good biomonitors of metal concentrations and suggests O. validus as an additional biomonitor for use in future Antarctic metal monitoring programs.

Preliminary study of cellular metal accumulation in two Antarctic marine microalgae - implications for mixture interactivity and dietary risk

Localised sites in Antarctica are contaminated with mixtures of metals, yet the risk this contamination poses to the marine ecosystem is not well characterised. Recent research showed that two Antarctic marine microalgae have antagonistic responses to a mixture of five common metals (Koppel et al., 2018a). However, the metal accumulating potential and risk to secondary consumers through dietary exposure are still unknown. This study investigates cellular accumulation following exposure to a mixture of cadmium, copper, nickel, lead, and zinc for the Antarctic marine microalgae, Phaeocystis antarctica and Cryothecomonas armigera. In both microalgae, cellular cadmium, copper, and lead concentrations increased with increasing exposures while cellular nickel and zinc did not. For both microalgae, copper in the metal mixture drives inhibition of growth rate with R² values > -0.84 for all cellular fractions in both species and the observed antagonism was likely caused by zinc competition, having significantly positive partial regressions. Metal accumulation to P. antarctica and C. armigera is likely to be toxic to consumer organisms, with low exposure concentrations resulting in cellular concentrations of 500 and 1400 × 10^-18 mol Zn cell^-1 and 160 and 320 × 10^-18 mol Cu cell^-1, respectively.

Pollution and toxicity of sediment in potential dredging sites of the Marmara Sea, Turkey

This study aims to assess the impact of the sediment in the potential dredging areas of the Marmara Sea. To that aim, sediments were analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and heavy metals, sources were discussed, and toxicity tests were applied. For assessment, lower and upper limits of Turkish draft regulation (L_TR, U_TR) and UNEP-MAP's guidance document (LCT, UCT), and effects range low and median (ERL, ERM) were used. Total concentrations were found between 562 and 8643 µg kg^-1 for PAHs, 4-36 µg kg^-1 for PCBs, and 14-190 µg kg^-1 for OCPs. The highest ∑PAH concentrations were measured in Golden Horn, and none of the PAH compounds was above ERM. ERL and UCT were exceeded in İstinye and Golden Horn stations. The highest ∑PCBs and ∑OCPs levels were determined in İzmit Bay (IB). ΣPCBs in IB were higher than ERL and L_TR, while ΣDDT were found above ERM and UCT. High concentrations of chromium (∼190 mg kg^-1) and copper (∼180 mg kg^-1) in Golden Horn and mercury in IB (∼4 mg kg^-1) were detected. The highest toxicities were observed in İstinye and İzmit Bay. According to the regulations, none of the sediments can be dumped.

Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica

Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ¹³C, δ¹⁵N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and birds). Diet and trophic position were also characterised using Bayesian mixing models. Then, relationships between stable isotopes, diet and TEs (Cd, Cr, Co, Cu, Hg, Ni, Pb and V) were assessed in order to evaluate if and how horizontal (organic matter pathways) and vertical (trophic position) food web features influence TE transfer to the biota. Regressions between log[TE] and δ¹³C revealed that the sympagic pathway drives accumulation of V in primary consumers and Cd and Hg in secondary consumers, and that a coupled benthic/pelagic pathway drives Pb transfer to all consumers. Regressions between log[TE] and δ¹⁵N showed that only Hg biomagnifies across trophic levels, while all the others TEs showed a biodilution pattern, consistent with patterns observed in temperate food webs. Although the Cd behavior needs further investigations, the present findings provide new insights about the role of basal sources in the transfer of TEs in polar systems. This is especially important nowadays in light of the forecasted trophic changes potentially resulting from climate change-induced modification of sea-ice dynamics.

Assessment of heavy metal contamination from penguins and anthropogenic activities on Fildes Peninsula and Ardley Island, Antarctic

Fildes Peninsula, with a high density of scientific stations, has been significantly impacted by anthropogenic activities. However, the contamination from penguins, a biovector that transports pollutants from ocean to land, has seldom been assessed. In this study, 32 lacustrine surface sediment samples on Fildes Peninsula and 8 lacustrine surface sediment samples on Ardley Island were collected to determine Cu, Zn, Pb, Ni, Cr, Cd, Co, Sb, Hg and P levels. The results showed that the heavy metal contents of lacustrine sediments on Ardley Island are significantly higher than those on Fildes Peninsula. The contaminants on Fildes Peninsula are mainly derived from anthropogenic activities, while the contaminants on Ardley Island are transported to the lacustrine sediments in the form of penguin guanos after a series of biomagnification in the food chain. The results indicated that the impact of penguin-transported contamination on Antarctic environment outweighs human activities near scientific stations in some areas. Therefore, more attention should be paid to the impacts of Antarctic animals on the Antarctic environment.

Phytomanagement of trace metals in mangrove sediments of Hormozgan, Iran, using gray mangrove (Avicennia marina)

Trace elements (Zn, Cu, Pb, and Cd) in root and leaf tissues of the gray mangrove (Avicennia marina) and in corresponding sediment samples were studied. Samples were taken from the inflow/outflow points in two distinct habitats, i.e., the Hara Protected Area and the Azini Bay, of Hormozgan Province in south Iran. Heavy metal concentrations (μg g^-1 of dry weight) in the sediments of the Hara Protected Area ranged from 16.0 to 68.0 for Pb, 15.0 to 52.0 for Zn, 9.0 to 27.0 for Cu, and 1.0 to 3.3 for Cd. In the Azini Bay, these concentrations ranged from 7.1 to 27.5 for Pb, 17.1 to 55.9 for Zn, 12.1 to 37.9 for Cu, and 0.2 to 2.3 for Cd. The accumulation trend of heavy metal concentrations in the roots of A. marina was in the order Pb (16.1) > Zn (15.8) > Cu (9.3) > Cd (1.3) μg g^-1 of dry weight in the Hara Protected Area and in the order Zn (13.7) > Cu (9.4) > Pb (5.5) > Cd (0.6) μg g^-1 of dry weight in the Azini Bay. The value of translocation factor (TLF) was smaller than 1 in both regions. It was estimated from 0.44 to 0.62 in the Hara Protected Area and from 0.51 to 1.01 in the Azini Bay. The enrichment coefficient for root (ECR) varied from 0.32 to 0.93 in the Hara Protected Area and from 0.32 to 0.51 in the Azini Bay. The ratio of heavy metals in leaves/sediments (ECL) also varied from 0.01 to 0.67 in the Hara Protected Area and from 0.01 to 0.47 in the Azini Bay. The enrichment coefficient for leaf (ECL) was always lower than ECR in both regions. Based on the above findings, A. marina can be regarded as an excluder for the heavy metals examined in this study, given its low efficiency in translocating and accumulating the heavy metals in the shoots. Apart from serving as a baseline for the study area, findings could be useful for mitigating heavy metal contamination in these sensitive ecosystems through possible phytomanagement using gray mangrove.

Phytoplankton community-level bio-optical assessment in a naturally mercury contaminated Antarctic ecosystem (Deception Island)

Mercury naturally contaminated environments, like Deception Island (Antarctica), are field labs to study the physiological consequences of chronic Hg-exposure at the community level. Deception Island volcanic vents lead to a continuous chronic exposure of the phytoplanktonic communities to potentially toxic Hg concentrations. Comparing Hg-contaminated areas (Fumarolas Bay - FB, Gabriel de Castilla station - GdC station), no significant differences in chlorophyll a concentrations were detected, indicating that biomass production was not impaired by Hg-exposure despite the high Hg levels found in the cells. Moreover, the electron transport energy, responsible for energy production, also presented rather similar values in phytoplankton from both locations. Regarding FB communities, although the cells absorbed and trapped lower amounts of energy, the effect of Hg was not relevant in the photochemical work produced by the electronic transport chain. This might be due to the activation of alternative internal electron donors, as counteractive measure to the energy accumulated inside the cells. In fact, this alternative electron pathway, may have allowed FB communities to have similar electron transport energy fluxes without using respiration as photoprotective measure towards excessive energy. Hg-exposed cells also showed a shift from the energy flux towards the PS I (photosystem I), alleviating the excessive energy accumulation at the PS II (photosystem II) and preventing an oxidative burst. Our findings suggest a higher energy use efficiency in the communities exposed to volcanic Hg, which is not observable in cultured phytoplankton species grown under Hg exposure. This may constitute a metabolic adaptation, driven from chronic exposure allowing the maintenance of high levels of primary productivity under the assumingly unfavourable conditions of Deception Island.

Marine sponges as a powerful tool for trace elements biomonitoring studies in coastal environment

In this work, we performed a comparative study on six marine sponge species collected along the French Mediterranean and Irish coasts for their TEs accumulation. Intra and inter-species variabilities were examined. Among the Mediterranean species, Cymbaxinella damicornis accumulates significantly more As and Cu than others sponge species; Chondrilla nucula more Ni and Mo and Acanthella acuta more Ag. Among Irish samples, Hymeniacidon perlevis showed higher accumulation properties for most of TEs in comparison to Halichondria panicea. Bioconcentration Factors were > 1 in all species for most of TEs. This study suggests that TEs bioaccumulation is most likely associated to differences in morphological features and/or to specific bacterial communities associated to different species. The determination of Pb isotope ratios revealed mainly natural Pb sources for Mediterranean and Kilkieran Bay's samples, and rather anthropogenic influence for Belfast samples. This study confirms that sponges represent a powerful tool for biomonitoring studies.

Heavy metal concentrations in the benthic trophic web of Martel Inlet, Admiralty Bay (King George Island, Antarctica)

Knowledge of the metals behaviour in the Antarctic environment is important for conserving this continent, which can be impacted by local activities, such as research stations and by atmospheric and oceanic transport over long distances. As, Cd Cr, Cu, Hg, Ni, Pb and Zn levels and the nitrogen isotope ratio were investigated using benthic samples from Martel Inlet, Admiralty Bay. The results showed the biodilution of As and a tendency of increasing concentrations of Cd and Cu along the trophic web. Biomagnification was verified only for Zn, and this was attributed to its essentiality to the biota, and to the acting of metallothioneins proteins that participate in homeostasis, store and detoxify metals. These results can be used as baseline levels for the biota in the Antarctic region and assist the monitoring and management work developed by the Brazilian INCT-APA (National Institute of Science and Technology for Environmental Research Antarctic).