Toxicity of inorganic nanoparticles and commercial sunscreens on marine bacteria.

The Balearic Islands, a top tourist destination for sunny beaches, face physical and chemical pressures from human activities, impacting keystone species like the endemic seagrass Posidonia oceanica and its associated microbiome. This study evaluated the effects of ZnO and TiO2 nanoparticles and three commercial sunscreens with varying protection factors (50 or 90) and chemical complexities (1- SPF50_E "eco-friendly"; 2- SPF50 not "eco-friendly"; 3- SPF90 not "eco-friendly") on five heterotrophic bacteria (Pseudomonas azotifigens, Marinobacterium litorale, Thiothrix nivea, Sedimenticola thiotaurini and Cobetia sp) and two autotrophic cyanobacteria (Halothece sp. and Fischerella muscicola) associated to P. oceanica, as well as a natural leaf epiphytic community. Results indicated that TiO2 affected all heterotrophic bacteria, while ZnO was toxic to only two species, while autotrophs were unaffected. Commercial sunscreens impacted three heterotrophs and the natural epiphytic community, while autotrophs were only affected by SPF50. SPF50_E reduced phosphorus uptake, and both SPF50 and SPF90 decreased alkaline phosphatase activity. Reactive oxygen species production was mainly induced by SPF90, followed by SPF50_E and SPF50. Generally, the smallest bacteria were most sensitive to UV-filters (UVFs). This study indicates that UVFs exposure may alter the epiphytic community structure of P. oceanica.

The contribution of penguin guano to the Southern Ocean iron pool.

Iron plays a crucial role in the high-nutrient, low-chlorophyll Southern Ocean regions, promoting phytoplankton growth and enhancing atmospheric carbon sequestration. In this area, iron-rich Antarctic krill (Euphausia superba) and baleen whale species, which are among their main predators, play a large role in the recycling of iron. However, penguins have received limited attention despite their representing the largest seabird biomass in the southern polar region. Here, we use breeding site guano volumes estimated from drone images, deep learning-powered penguin census, and guano chemical composition to assess the iron export to the Antarctic waters from one of the most abundant penguin species, the Chinstrap penguin (Pygoscelis antarcticus). Our results show that these seabirds are a relevant contributor to the iron remobilization pool in the Southern Ocean. With an average guano concentration of 3 mg iron g-1, we estimate that the Chinstrap penguin population is recycling 521 tonnes iron yr-1, representing the current iron contribution half of the amount these penguins were able to recycle four decades ago, as they have declined by more than 50% since then.

Assessment of the environmental acceptability of potential artificial reef materials using two ecotoxicity tests: Luminescent bacteria and sea urchin embryogenesis.

Ecotoxicological analysis of construction products is a relatively unexplored area at international level. Aquatic toxicity tests on construction products has been recommended recently for freshwater environment. However, the biological effects of alternative materials on marine ecosystem are still not considered. In this study, the main aim was to assess the environmental impact of alternative mortars proposed as artificial reefs (ARs) materials. The ARs specimens were developed by 3D printing, based on cement and geopolymer mortars using recycled sands of glass and seashells. For this purpose, a leaching test and two different toxicity bioassays, luminosity reduction of marine bacteria Vibrio fischeri (Microtox®) and the success of embryo-larval development of sea-urchin Paracentrotus lividus, were conducted. From the leaching results it should be noted that the mobility of all trace elements considered in both, raw materials and mortars, meet the inert landfill limits, except As, Mo, Se or Sb in the leachates geopolymer mortars. However, the results obtained from the both bioassays show low environmental acceptability for those mortars containing shell sand, probably due to the degradation of the organic matter adhered to the shells. On the other hand, cement mortars obtain better results than geopolymer mortars, regardless of the aggregate used, showing certain consistency with the leaching behaviour, since they present the lowest mobility of trace chemical elements. Therefore, the results supporting the environmental acceptability of its potential use as alternative materials in the production of ARs.

Modelling the bioconcentration of Zn from commercial sunscreens in the marine bivalve Ruditapes philippinarum.

Sunscreens contain ZnO particles used as a UV filter cause adverse effects in the marine environment through the release of this metal into seawater and its bioaccumulation in organisms. A mathematical model using sunscreen colloidal residues, seawater and R. philippinarum clams as differentiated compartments, is proposed in order to interpret both the kinetic pattern and the bioaccumulation of Zn in clams. Two kinetic laboratory experiments were conducted, both with and without clams exposed to sunscreen concentrations from 0 to 200 mg L-1. Both the lowest value of uptake rate coefficient obtained when 5 mg L-1 of sunscreen is added (0.00688 L g-1 d-1) and the highest obtained at sunscreen addition of 100 mg L-1 (0.0670 L g-1 d-1), predict a lower bioavailability of Zn in a complex medium such as the seawater-sunscreen mixtures, in comparison to those studied in the literature. The efflux rate coefficient from clams to seawater increased from 0 to 0.162 d-1 with the sunscreen concentrations. The estimated value of the inlet rate coefficient at all studied concentrations indicates that there is a negligible colloidal Zn uptake rate by clams, probably due to the great stability of the organic colloidal residue. An equilibrium shift to higher values of Zn in water is predicted due to the bioconcentration of Zn in clams. The kinetic model proposed with no constant Zn (aq) concentrations may contribute to a more realistic prediction of the bioaccumulation of Zn from sunscreens in clams.

Products released from surgical face masks can provoke cytotoxicity in the marine diatom Phaeodactylum tricornutum.

Surgical face masks are more present than ever as personal protective equipment due to the COVID-19 pandemic. In this work, we show that the contents of regular surgical masks: i) polypropylene microfibres and ii) some added metals such as: Al, Fe, Cu, Mn, Zn and Ba, may be toxic to some marine life. This work has got two objectives: i) to study the release rate of the products from face masks in marine water and ii) to assess the toxicity in Phaeodactylum tricornutum of these by-products. To achieve these two objectives, we performed release kinetic experiments by adding masks in different stages of fragmentation to marine water (i.e. whole face masks and fragments of them 1.52 ± 0.86 mm). Released microfibres were found after one month in shaking marine water; 0.33 ± 0.24 and 21.13 ± 13.19 fibres·mL-1 were collected from the whole and fragmented face masks, respectively. Significant amounts of dissolved metals such as Mn, Zn and Ni, as well as functional groups only in the water containing the face mask fragments were detected. Water from both treatments was employed to study its toxicity on the marine diatom. Only the water from the face mask fragments showed a significant, dose-dependent, decrease in cell density in P. tricornutum; 53.09 % lower than in the controls. Although the water from the face mask fragments showed greater effects on the microalgae population than the water from the whole face mask, the latter treatment did show significant changes in the photosynthetic apparatus and intrinsic properties of the cells. These results indicate that during fragmentation and degradation face masks a significant chemical print can be observed in the marine environment.

Trace elements in Antarctic penguins and the potential role of guano as source of recycled metals in the Southern Ocean.

Penguins dominate the Antarctic avifauna. As key animals in the Antarctic ecosystem, they are monitored to evaluate the ecological status of this pristine and remote region and specifically, they have been used as effective bioindicators suitable for long-term monitoring of metals in the Antarctic environment. However, studies about the role of this emblematic organism could play in the recycling of trace metals (TMs) in the Antarctic ecosystem are very limited. In this study we evaluate, using the peer review research articles already published and our own findings, the distribution of metals (i.e., Ca, Fe, Al, Na, Zn, Mg, Cu, K, Cd, Mn, Sr, Cr, Ni, Pb, Hg, V, Ba, Co, La, Ag, Rb, Hf, Sc, Au and Cs) and metalloids (As and Sb), measured in different biotic matrices, with emphasis on guano, of the Chinstrap (Pygoscelis antarcticus), Adélie (Pygoscelis adeliae) and Gentoo (Pygoscelis papua) penguins. Regarding bioactive metals, the high concentrations (µg g-1 dry weight) of Cu (2.0 ± 1.4) x 102, Fe (4.1 ± 2.9) x 102, Mn (30 ± 34) and Zn (210 ± 90) reported in the guano from all the penguin species studied including our data, are of the same order of magnitude as those reported for whale feces (µg g-1 dry weight): Cu (2.9 ± 2.4) x 102, Fe (1.5 ± 1.4) x 102, Mn (28 ± 17) and Zn (6.2 ± 4.3) x 102, and one order of magnitude higher than the metal contents in krill (µg g-1 dry weight) of Cu (10.2 ± 5.5), Fe (24 ± 29) and Zn (13.5 ± 1.7). This suggest that penguin's excretion products could be an important source of these essential elements in the surface water, with an estimated annual release on a breeding season for Cu, Fe, Mn, Zn respectively of 28, 56, 4 and 29 tons, for the Chinstrap, Adélie and Gentoo penguins. The results provide evidence on the potential influence of penguins recycling TMs in the surface layer of the water column.

Spatial distribution and level of contamination of potentially toxic elements in sediments and soils of a biological reserve wetland, northern Amazon region of Ecuador.

This study quantifies the degree of pollution and assess the ecological risk of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn in sediments and soils of the Limoncocha Biological Reserve (Ecuador), identified as a Ramsar site with high ecological and socioeconomic value. The hydrologic system of the Reserve is mainly formed by two rivers that drain into the Limoncocha lagoon, which occupies only five percent of the protected area but support a high anthropic influence. Local statistical baseline of studied potentially toxic elements is established using cumulative frequency method, and Al is selected as reference element due to the good correlation with the studied elements. The grade of pollution and the potential ecological risk are evaluated applying three individual (Contamination Factor, Geo-accumulation Index and Enrichment Factor) and six integrated (Degree and modified degree of contamination, Pollution Load Index, Nemerow and modified Nemerow pollution indexes and potential ecological risk index) indices. Results analysis are based on the combined application of traditional statistics, multivariate data analysis and self organizing maps. Outcomes suggest to classify sediments and soils as "moderate contamination and enrichment" due mainly to the concentrations of Cu (66.4-110 mg/kg) and Cd (0.0262-0.808 mg/kg), derived from domestic wastewaters and agricultural activities, and in a lesser extent due to Mo (0.822-4.37 mg/kg), Ni (10.3-25.8 mg/kg), Co (7.27-24.8 mg/kg) and V (60.3-178 mg/kg), derived from oil field drilling activities. The distributions of As (0.328-8.83 mg/kg), Ba (143-1100 mg/kg), Pb (7.20-26.5 mg/kg), Zn (60.1-276 mg/kg) and Cr (10.1-48.6 mg/kg) are heterogeneous in the studied sampling sites. Sediments located next to the pier and at the central area of the Limoncocha lagoon, show moderate potential risk and according to sediment quality guidelines, the calculated mean Effect Range Median quotient (mERMq) classify the sites as medium-low priority risk level. A three-level classification of a mean quotient based on soil quality and soil potential uses is proposed. Soil sites with high anthropogenic activities show low to moderate potential ecological risk being classified as poor soil quality sites but with all potential soil uses allowed according to the legal limits for land uses in Ecuador.

Minimal impact at current environmental concentrations of microplastics on energy balance and physiological rates of the giant mussel Choromytilus chorus.

Microplastic particles (MP) uptake by marine organisms is a phenomenon of global concern. Nevertheless, there is scarce evidence about the impacts of MP on the energy balance of marine invertebrates. We evaluated the mid-term effect of the microplastic ingestion at the current higher environmental concentrations in the ocean on the energy balance of the giant mussel Choromytilus chorus. We exposed juvenile mussels to three concentrations of microplastics (0, 100, and 1000 particles L-1) and evaluated the effect on physiology after 40 days. The impacts of MP on the ecophysiological traits of the mussels were minimum at all the studied concentrations. At intermediate concentrations of MP, Scope for Growth (SFG) had little impact. Other relevant key life-history and physiological processes, such as size and metabolism, were not affected by microplastics. However, individuals treated with MP presented histopathological differences compared to control group, which could result in adverse health effects for mussels.

Acquiring an evolutionary perspective in marine ecotoxicology to tackle emerging concerns in a rapidly changing ocean.

Tens of thousands of anthropogenic chemicals and wastes enter the marine environment each year as a consequence of the ever-increasing anthropogenic activities and demographic growth of the human population, which is majorly concentrated along coastal areas. Marine ecotoxicology has had a crucial role in helping shed light on the fate of chemicals in the environment, and improving our understanding of how they can affect natural ecosystems. However, chemical contamination is not occurring in isolation, but rather against a rapidly changing environmental horizon. Most environmental studies have been focusing on short-term within-generation responses of single life stages of single species to single stressors. As a consequence, one-dimensional ecotoxicology cannot enable us to appreciate the degree and magnitude of future impacts of chemicals on marine ecosystems. Current approaches that lack an evolutionary perspective within the context of ongoing and future local and global stressors will likely lead us to under or over estimations of the impacts that chemicals will exert on marine organisms. It is therefore urgent to define whether marine organisms can acclimate, i.e. adjust their phenotypes through transgenerational plasticity, or rapidly adapt, i.e. realign the population phenotypic performances to maximize fitness, to the new chemical environment within a selective horizon defined by global changes. To foster a significant advancement in this research area, we review briefly the history of ecotoxicology, synthesis our current understanding of the fate and impact of contaminants under global changes, and critically discuss the benefits and challenges of integrative approaches toward developing an evolutionary perspective in marine ecotoxicology: particularly through a multigenerational approach. The inclusion of multigenerational studies in Ecological Risk Assessment framework (ERA) would provide significant and more accurately information to help predict the risks of pollution in a rapidly changing ocean.

A new approach for the determination of sunscreen levels in seawater by ultraviolet absorption spectrophotometry.

Sunscreen is released into the marine environment and is considered toxic for marine life. The current analytical methods for the quantification of sunscreen are mostly specific to individual chemical ingredients and based on complex analytical and instrumental techniques. A simple, selective, rapid, reproducible and low-cost spectrophotometric procedure for the quantification of commercial sunscreen in seawater is described here. The method is based on the inherent properties of these cosmetics to absorb in the wavelength of 300-400 nm. The absorption at 303 nm wavelength correlates with the concentration of most commercial sunscreens. This method allows the determination of sunscreens in the range of 2.5-1500 mg L-1, it requires no sample pretreatment and offers a precision of up to 0.2%. The spectrophotometric method was applied to quantify sunscreen concentrations at an Atlantic Beach with values ranging from 10 to 96.7 mg L-1 in the unfiltered fraction and from the undetectable value to 75.7 mg L-1 in the dissolved fraction. This method is suggested as a tool for sunscreen quantifications in environmental investigations and monitoring programs.

Repellency and mortality effects of sunscreens on the shrimp Palaemon varians: Toxicity dependent on exposure method.

Contamination by sunscreens has become a serious environmental problem due to the increasing use of these products in coastal regions. Their complex chemical composition supposes an input of different chemical compounds capable of producing toxic effects and repelling organisms. The aim of the current study was to experimentally check the repellency of three commercial sunscreens [A (lotion), B (gel) and C (milk spray)] by assessing the escape (displacement towards areas with lower sunscreen levels) of the estuarine shrimp Palaemon varians exposed (4 h) to a gradient (0-300 mg/L) of the sunscreens in a heterogeneous non-forced exposure scenario. Additionally, mortality and immobility (72 h) were checked in a traditional forced exposure scenario. Considering that the toxicity of sunscreens is a little controversial regarding their chemical availability in the medium, two different methods of sunscreen solubilisation were tested: complete homogenization and direct immersion. Very low mortality was observed in the highest concentration of sunscreens A and C applied by direct immersion; however, for sunscreen B, the main effect was the loss of motility when homogenization was applied. Repellency was evidenced for two sunscreens (A and B) applied by direct immersion. The homogenization in the medium seemed to lower the degree of repellency of the sunscreens, probably linked to the higher viscosity in the medium, preventing the motility of shrimps. By integrating both short-term responses (avoidance and mortality/immobility), the PID (population immediate decline) calculated showed that avoidance might be the main factor responsible for the reduction of the population at the local scale.

Sunscreens as a New Source of Metals and Nutrients to Coastal Waters.

Studies detailing the environmental impact of sunscreen products on coastal ecosystems are considered a high priority. In the present study, we have determined the release rate of dissolved trace metals (Al, Cd, Cu, Co, Mn, Mo, Ni, Pb, and Ti) and inorganic nutrients (SiO2, P-PO43-, and N-NO3-) from a commercial sunscreen in seawater, and the role of UV radiation in the mobilization of these compounds. Our results indicate that release rates are higher under UV light conditions for all compounds and trace metals except Pb. We have developed a kinetic model to establish the release pattern and the contribution to marine coastal waters of dissolved trace metals and inorganic nutrients from sunscreen products. We conservatively estimate that sunscreen from bathers is responsible for an increase of dissolved metals and nutrients ranging from 7.54 × 10-4 % for Ni up to 19.8% for Ti. Our results demonstrate that sunscreen products are a significant source of metals and inorganic nutrients to coastal waters. The normally low environmental concentrations of some elements (e.g., P) and the toxicity of others (e.g., Pb) could be having a serious adverse effect on marine ecology in the Mediterranean Sea. This risk must not be ignored.

Massive coastal tourism influx to the Mediterranean Sea: The environmental risk of sunscreens.

The Mediterranean region is, by far, the leading tourism destination in the world, receiving more than 330 million tourists in 2016. This tourism is undertaken mostly for seaside holidays, and during the summer season concentrates between 46% and 69% of the total international arrivals; this is equivalent to a density of 2.9 tourists per meter of Mediterranean coast, or double this number taking into account the local/permanent population in addition. Previous studies have reported not only the presence of sunscreen in the various environmental compartments (water, sediments and biota) of the Mediterranean Sea (MS) and other regions, but also show that sunscreen products are toxic for marine biota and are accumulated and biomagnificated. Here, we highlight that the environmental risk of these chemicals is likely to be exacerbated in the MS due to the massive influx of tourists and its densely populated coasts, the basin's limited exchanges with the ocean, the high residence time of surface waters, and its oligotrophic waters.

Multi-generational responses of a marine polychaete to a rapid change in seawater pCO2.

Little is known of the capacity that marine metazoans have to evolve under rapid p CO 2 changes. Consequently, we reared a marine polychaete, Ophryotrocha labronica, previously cultured for approximately 33 generations under a low/variable pH regime, under elevated and low p CO 2 for six generations. The strain used was found to be tolerant to elevated p CO 2 conditions. In generations F1 and F2 females' fecundity was significantly lower in the low p CO 2 treatment. However, from generation F3 onwards there were no differences between p CO 2 treatments, indicating that trans-generational effects enabled the restoration and maintenance of reproductive output. Whilst the initial fitness recovery was likely driven by trans-generational plasticity (TGP), the results from reciprocal transplant assays, performed using F7 individuals, made it difficult to disentangle between whether TGP had persisted across multiple generations, or if evolutionary adaptation had occurred. Nonetheless, both are important mechanisms for persistence under climate change. Overall, our study highlights the importance of multi-generational experiments in more accurately determining marine metazoans' responses to changes in p CO 2, and strengthens the case for exploring their use in conservation, by creating specific p CO 2 tolerant strains of keystone ecosystem species.

Dredged material characterization and management frameworks: A case study at the port Vilagarcia (NW, Spain).

The potential impact of dredged sediment has been assessed at sixteen areas of the high-traffic port of Vilagarcia (Northwest Spanish Atlantic coast). The assessment has been done by three weight-of-evidence tools, which integrated data on sediment characteristics and toxicity responses of Ampelisca brevicornis, Vibrio fischeri and eggs and embryos of Paracentrotus lividus. Two of the tools also represented management options regarding the disposal of dredged material. The comparison of the logic in these tools revealed essential differences in the type and the necessity of bioassays and threshold values for chemical concentrations. However, despite this difference, assessment results and the derived management options coincided in most of the sediments. The potential toxicity of sediments was relatively low especially for eggs and embryos possibly due to different contaminant availability in solid and liquid phases. The importance of a battery of toxicity tests in the dredged material quality assessment has been emphasized to avoid an underestimation of sediment toxicity for solid phase organisms, if only liquid phase responses are considered. The potential false implications, which may result from the application of the third tool, were highlighted. The strengths and weaknesses of the tools were discussed from the dredged material management perspective.

Laboratory simulation system, using Carcinus maenas as the model organism, for assessing the impact of CO2 leakage from sub-seabed injection and storage.

The capture and storage of CO2 in sub-seabed geological formations has been proposed as one of the potential options to decrease atmospheric CO2 concentrations in order to mitigate the abrupt and irreversible consequences of climate change. However, it is possible that CO2 leakages could occur during the injection and sequestration procedure, with significant repercussions for the marine environment. We investigate the effects of acidification derived from possible CO2 leakage events on the European green crab, Carcinus maenas. To this end, a lab-scale experiment involving direct release of CO2 was conducted at pH values between 7.7 and 6.15. Female crabs were exposed for 10 days to sediment collected from two different coastal areas, one with relatively uncontaminated sediment (RSP) and the other with known contaminated sediment (MZ and ML), under the pre-established seawater pH conditions. Survival rate, histopathological damage and metal (Fe, Mn, Cu, Zn, Cr, Cd and Pb) and As accumulation in gills and hepatopancreas tissue were employed as endpoints. In addition, the obtained results were compared with the results of the physico-chemical characterization of the sediments, which included the determination of the metals Fe, Mn, Cu, Zn, Cr, Pb and Cd, the metalloid As, certain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), as well as nonchemical sediment properties (grain size, organic carbon and total organic matter). Significant associations were observed between pH and the histological damage. Concentrations of Fe, Mn, Cr, Pb, Cd and PAHs in sediment, presented significant negative correlations with the damage to gills and hepatopancreas, and positive correlations with metal accumulation in both tissues. The results obtained in this study reveal the importance of sediment properties in the biological effects caused by possible CO2 leakage. However, a clear pattern was not observed between metal accumulation in tissues and pH reduction. Animals' avoidance behavior and degree of tolerance to acidification are confounding factors for assessing metal bioaccumulation. Further research is required to find a suitable assay that would allow us to predict the risk to environmental health of possible negative side effects of metal mobility derived from CO2 leakage during its injection and storage in sub-seabed formations.

Evaluation of the threat of marine CO2 leakage-associated acidification on the toxicity of sediment metals to juvenile bivalves.

The effects of the acidification associated with CO2 leakage from sub-seabed geological storage was studied by the evaluation of the short-term effects of CO2-induced acidification on juveniles of the bivalve Ruditapes philippinarum. Laboratory scale experiments were performed using a CO2-bubbling system designed to conduct ecotoxicological assays. The organisms were exposed for 10 days to elutriates of sediments collected in different littoral areas that were subjected to various pH treatments (pH 7.1, 6.6, 6.1). The acute pH-associated effects on the bivalves were observed, and the dissolved metals in the elutriates were measured. The median toxic effect pH was calculated, which ranged from 6.33 to 6.45. The amount of dissolved Zn in the sediment elutriates increased in parallel with the pH reductions and was correlated with the proton concentrations. The pH, the pCO2 and the dissolved metal concentrations (Zn and Fe) were linked with the mortality of the exposed bivalves.

Predicting the impacts of CO2 leakage from subseabed storage: effects of metal accumulation and toxicity on the model benthic organism Ruditapes philippinarum.

The urgent need to minimize the potential harm deriving from global climate change and ocean acidification has led governmental decision-makers and scientists to explore and study new strategies for reducing the levels of anthropogenic CO2. One of the mitigation measures proposed for reducing the concentration of atmospheric CO2 is the capture and storage of this gas in subseabed geological formations; this proposal is generating considerable international interest. The main risk associated with this option is the leakage of retained CO2, which could cause serious environmental perturbations, particularly acidification, in marine ecosystems. The study reported is aimed at quantifying the effects of acidification derived from CO2 leakage on marine organisms. To this end, a lab-scale experiment involving direct release of CO2 through marine sediment was conducted using Ruditapes philippinarum as a model benthic organism. For 10 days bivalves were exposed to 3 sediment samples with different physicochemical characteristics and at pre-established pH conditions (8.0-6.1). End points measured were: survival, burrowing activity, histopathological lesions, and metal accumulation (Fe, Al, Mn, Cu, and Zn) in whole body. Correlations analyses indicated highly significant associations (P < 0.01) between pH and the biological effects measured in R philippinarum, except for metal concentrations in tissues. Further research to understand and predict the biological and economic implications for coastal ecosystems deriving from acidification by CO2 leakages is urgently needed.

Simulation of CO2 leakages during injection and storage in sub-seabed geological formations: metal mobilization and biota effects.

To assess the potential effects on metal mobilization due to leakages of CO2 during its injection and storage in marine systems, an experimental set-up was devised and operated, using the polychaete Hediste diversicolor as the model organism. The objective was to study the effects of such leakage in the expected scenarios of pH values between 8.0 and 6.0. Polychaetes were exposed for 10 days to seawater with sediment samples collected in two different coastal areas, one with relatively uncontaminated sediment as reference (RSP) and the other with known contaminated sediment (ML), under pre-determined pH conditions. Survival and metal accumulation (Al, Fe, Mn, Cu, Zn, As and Hg) in the whole body of H. diversicolor were employed as endpoints. Mortality was significant at the lowest pH level in the sediment with highest metal concentrations. In general, metal concentrations in tissues of individuals exposed to the contaminated sediment were influenced by pH. These results indicate that ocean acidification due to CO2 leakages would provoke increased metal mobilization, causing adverse side effects in sediment toxicity.

Effects on the mobility of metals from acidification caused by possible CO2 leakage from sub-seabed geological formations.

Carbon dioxide capture and storage (CCS) in submarine geological formations has been proposed as a mitigation measure for the prevention of global warming. However, leakage of CO2 to overlying sediments may occur over time, leading to various effects on ecosystems. Laboratory-scale experiments were performed, involving direct release of carbon dioxide into sediment, inside non-pressurized chambers, in order to provide data on the possible effects of CO2 leakage from geological storage sites on the fate of several metals. Marine sediments from three sites with different levels of contamination were sampled and submitted to acidification by means of CO2 injection. The experiment lasted 10 days and sediment samples were collected at the beginning and end of the experiment and pore water was extracted for metal analysis. The results revealed that mobility of metals from sediment to pore water depends on the site, metal and length of time exposed. Mobilization of the metals Al, Fe, Zn, Co, Pb and Cu increases with acidification, and this response generally increases with time of exposure to CO2 injection. The geochemical model applied suggests that acidification also influences the speciation of metals, transforming metals and metalloids, like As, into species much more toxic to biota. The data obtained from this study will be useful for calculating the potential risk of CCS activities to the marine environment.