Rare earths, zirconium and hafnium distribution in coastal areas: The example of Sabella spallanzanii (Gmelin, 1791)

Global natural concentrations of Rare Earth Elements in aquatic organisms: Progress and lessons from fifty years of studies

Rare Earth Elements (REEs) consist of a coherent group of elements with similar physicochemical properties and exhibit comparable geochemical behaviors in the environment, making them excellent tracers of environmental processes. For the past 50 years, scientific communities investigated the REE concentrations in biota through various types of research (e.g. exploratory studies, environmental proxies). The extensive development of new technologies over the past two decades has led to the increased exploitation and use of REEs, resulting in their release into aquatic ecosystems. The bioaccumulation of these emerging contaminants has prompted scientific communities to explore the fate of anthropogenic REEs within aquatic ecosystems. To achieve this, it is necessary to determine the natural concentration levels of REEs in aquatic organisms and the factors controlling REE dynamics. However, knowledge gaps still exist, and no comprehensive approach currently exists to assess the REE concentrations at the ecosystem scale or the factors controlling these concentrations in aquatic organisms. Based on a database comprising 102 articles, this study aimed to: i) provide a retrospective analysis of research topics over a 50-year period; ii) establish reference REE concentrations in several representative phyla of aquatic ecosystems; and iii) examine the global-scale influences of habitat and trophic position as controlling factors of REE concentrations in organisms. This study provides reference concentrations for 16 phyla of freshwater or marine organisms. An influence of habitat REE concentrations on organisms has been observed on a global scale. A trophic dilution of REE concentrations was highlighted, indicating the absence of biomagnification. Lastly, the retrospective approach of this study revealed several research gaps and proposed corresponding perspectives to address them. Embracing these perspectives in the coming years will lead to a better understanding of the risks of anthropogenic REE exposure for aquatic organisms.

Trace elements in the muscle, ova and seminal fluid of key clupeid representatives from the Gdansk Bay (South Baltic Sea) and Iberian Peninsula (North-East Atlantic)

BACKGROUND

Baltic herring and European sardine are pelagic, fish of particular ecological importance, on the one hand control numbers of planktonic organisms, and on the other hand exist as food for predators on higher trophic levels. Moreover, these fish are among the main species caught for human consumption. Rare earth elements (REEs) come mainly from geogenic sources but, due to their use in technology, agriculture and medicine, the importance of anthropogenic sources is growing steadily.

METHODS

Samples used for the study were available on the market. Fresh materials of fish muscle, ova and seminal fluid were mineralized and elements were determined by means of inductively coupled plasma - mass spectrometry (ICP-MS).

RESULTS

The conducted research indicated the presence of REEs in the muscles of the Baltic herring (∑REE = 0.076 ± 0.047 mg/kg) and European sardine (∑REE = 0.191 ± 0.163 mg/kg), with a clear dominance of heavy REEs in both fish species. Trace elements (TE) in the muscles of the tested fish demonstrated a similar system of concentration (Baltic herring: Zn > As > Se > Cu > Cr > Ni > Pb > Cd; European sardine: Zn > As > Se > Cu > Ni > Cr > Pb > Cd). REEs and TEs in these fish were presence in ova and seminal fluid indicates intergenerational transfer.

CONCLUSION

Changes in the concentrations of some trace elements (As, Cu, Cd) in the muscles of herring indicate increases compared to the historical data. The availability of metals in the aquatic environment may be determined by ongoing climate changes, effected water salinity and warming increased availability of labile forms of trace metals. Decline trends in the condition of pelagic fish need to extend the research in the context of contemporary environmental threats.

Alimentary exposure and elimination routes of rare earth elements (REE) in marine mammals from the Baltic Sea and Antarctic coast

Marine mammals found at the top of the trophic pyramid are excellent bioindicators of pollutants in the marine environment, the concentrations of which increase along with the trophic level of the organism. As these animals are usually protected species, their contamination has to be assessed non-invasively by analysing excrement and epidermal structures such as fur or claws. The present study involved testing the excrement and fur of the grey seal (Halichoerus grypus) from the Southern Baltic coast and the Southern elephant seal (Mirounga leonine) from Admiralty Bay, along with fish muscle (food) and the lithological background of both areas, for the presence of rare earth elements (REE). The soil on the Baltic coast is characterized by the predomination of light rare earth elements (LREE): yttrium, lanthanum and cerium (∑REE = 7.86 mg·kg^-1 dw). In the soil and bedrock of Admiralty Bay all REEs were found except for terbium, thulium and lutetium (∑REE = 96.1 mg·kg^-1 dw). The REE levels found in the muscles of Baltic herring (∑REE = 0.057 mg·kg^-1 ww) were lower than those in the muscles of marbled rockcod (∑REE = 0.540 mg·kg^-1 ww). The situation was analogous in the mammals, with the REE concentrations in grey seal fur (∑REE = 0.489 mg·kg^-1 dw) and excrement (∑REE = 0.676 mg·kg^-1 dw) being lower than those found in the fur (∑REE = 10.1 mg·kg^-1 dw) and excrement (∑REE = 83.6 mg·kg^-1 dw) of the elephant seal. The LREE/HREE partition coefficients in the grey seal excrement (3.37) and its fur (4.00), but also in the faeces of the elephant seal (2.63) and its fur (2.65), indicate that in each species the process of elimination from the body occurs in similar proportions.

Tracking hospital effluent-derived gadolinium in Atlantic coastal waters off Brazil

The use of gadolinium (Gd) complexes as contrast agents in magnetic resonance imaging (MRI) has resulted in point source releases of anthropogenic Gd into the environment and presents the opportunity to trace the fate of wastewater plumes. Here we collected seawater samples along the coast of Northeast Brazil to investigate the influence of two submarine sewage outfalls on the distribution of Gd and other rare earth elements (REE) in the coastal waters. The shale-normalized REEs only show a small light over heavy REE enrichment and negative Ce anomalies, likely reflecting the influence of freshwater inputs. Positive Gd anomalies are observed at most of the sampling sites, indicating the ubiquitous presence of anthropogenic Gd in coastal waters. The highest Gd anomalies are found in the vicinity of the submarine sewage outfalls and decrease with increasing distance from point source. The total daily discharge of 216 ± 82 g Gd and 92.0 ± 19.3 g Gd was calculated for the Rio Vermelho (ERV) and Boca do Rio (EBR) submarine outfalls, respectively, which on population bases equates to 11.5 ± 4.3 g Gd d^-1 for ERV and 15.5 ± 3.3 g Gd d^-1 for EBR per 100 000 persons. It is estimated that in 2016 the annual emission of anthropogenic Gd by hospitals and clinics in Brazil varied between 527 kg and 5.3 tons. It was roughly estimated that between 698 and 2021 g Gd d^-1 are discharged into the Tropical and South Atlantic waters due to submarine outfall sewage along the coast of Brazil.