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MARINFORSK-Marine ressurser og miljø

Are rare earth elements emerging contaminants of concern in the marine environment in Norway? (ELEMENTARY)

Alternative title: Er sjeldne jordarter et økende miljøproblem i marint miljø i Norge?

Awarded: NOK 11.9 mill.

The 15 lanthanoid elements and yttrium form the group of rare earth elements and yttrium (REY). They are essential for the green shift and rated as technology critical elements as they are used in many products and applications reaching from batteries, magnets, light source components, fuel additives, fertilizers and medical contrast agents. The rapidly rising demand, production and use will lead to their release into the environment. However, knowledge on REY concentrations in Norwegian marine environments and their potential effects on marine species is lacking. In Elementary we analysed water samples and organisms collected at different sites where REY could be release from human activity. These were: Trondheimsfjord (Trondheim city and rivers as sources), Lindesnes (pharmaceutical plant) and in Porsgrunn (city and industries including fertiliser production plant). In laboratory experiments we studied effects of selected REYs, with a main focus on fish and gadolinium (Gd), a REY that is commonly used in MRI imaging, and compared effects of inorganic Gd to a Gd based contrast agent (GBCA). We detected anthropogenic Gd anomalies in influent and effluent samples in both wastewater treatment plants Trondheim, where anthropogenic Gd accounted for >90% of the total Gd concentrations. These large anthropogenic anomalies were not found in fjord water samples taken in vicinity to the outlet pipes, most likely due to rapid and strong dilution. However our data suggest that anthropogenic Gd from the southern North Sea and the Baltic Sea is transported northward along the Norwegian coast. Generally, shale-normalized REY patterns in Trondheimsfjord water resembled seawater/fjordwater, with higher concentrations of heavy compared to light REYs. Tributary rivers generally had higher REY concentrations showing typical boreal river patterns and no anthropogenic enrichment. Water samples from Lindesnes and Porsgrunn showed similar trends to those reported from Trondheimsfjord. Anthropogenic Gd enrichment was only observed in one sample taken in great depths in front of Porsgrunn. In Trondheimsfjord, Lindesnes and in Porsgrunn different seaweed species, crabs, blue mussels and tapes (only Porsgrunn) were sampled, and REY concentrations and patterns analysed. Generally, light REYs accumulated more in organisms compared to heavy REY, with REY patterns reflecting the negative seawater cerium (Ce) anomaly. We did not observe anthropogenic enrichment of single REYs in the organisms sampled in Trondheimsfjord, even though some difference in concentrations were found between sampling stations. In contrast, blue mussels downstream the pharmaceutical factory in Lindesnes had a distinct anthropogenic Gd anomaly (Gd/Gd* = 4.4), which was not found in other organisms. This indicates that blue mussels can be a suitable indicator species for REY pollution, due to their sessile nature and widespread abundance. In laboratory experiments we found that that unchelated ("free") Gd was toxic to Atlantic cod embryos and larvae in the µg/L (>50 to 100 µg/L) concentration range. In contrast, no significant effects were found from Gd in the contrast agent (GBCA). Free Gd caused increased larvae mortality and affected development (lack of head pigmentation, spine deformations, muscle filament deformation and abnormal behaviour). Molecular analysis showed that many genes were expressed differently, for example genes related to Ca2+ regulation and homeostasis, immune system and inflammation, eye/lens and inner-ear development. In zebrafish larvae, exposure to free Gd (GdCl3) caused effects on neuronal activity. Exposure to Gd, and two other REYs, neodymium (Nd) and ytterbium (Yb) also seemed to impact behaviour in zebrafish larvae and in exposed deepwater amphipods. Effects of REYs on neuronal function should therefore be studied in more detail. We further studied uptake and distribution of free Gd and Gd as GBCA in organs of exposed lumpfish, as well as effects of the exposure. Our results show that more Gd was taken up from inorganic Gd exposures, with uptake being highest in gills>kidney>liver>brain. Gd organ concentrations generally decreased after a 10-day recovery, however, not in kidneys and brain of fish exposed to inorganic Gd. Effects on blood parameters were limited, and molecular effects are still being processed. Taken together, we detected release of Gd from anthropogenic use in some samples. The accumulation of anthropogenic Gd in mussels suggest them to be suitable indicator species. We found free Gd to be toxic to developing fish, however at higher concentrations than measured at the studied sites. As concentrations of REY are expected to increase in future, for example at mining sites, we recommend further monitoring activities. Further, our findings on neural, behavioural and developmental effects highlight the need for in depth studies investigating toxic mode of action and effects from chronic exposure.

While we detected anthropogenic input of gadolinium (Gd) into the environment at some study locations, measured REY concentrations were in most cases as expected for background levels, probably due to high dilution in the environment. Anthropogenic Gd enrichment was either detected in water samples, or in soft tissues of mussels, suggesting that mussels can be suitable organisms for future biomonitoring. Our results further show that free Gd, used as representative REY for evaluating bioavailability and toxic effects in this project, is bioavailable for fish, and causes severe impacts in developing fish; however, not at concentrations that we found at in the environment at the sites that we studied in this project. Yet, with activities related to REY production predicted to increase in future, especially mining and potentially deep-sea mining activities, we recommend further (bio-) monitoring studies, especially around mining and wastewater effluent sites. Further, observed effects were different for a tested gadolinium based contrast agent and free Gd, with the contrast agent being more stable in the environment, but free Gd being the toxic form. As the long-term fate and stability of such contrast agents in seawater are not yet sufficiently investigated, we recommend more thorough studies to be conducted. As behaviour and/or neuronal activity was affected in animals exposed to inorganic Gd, toxic modes of action, as well as effect concentrations for sublethal/chronic exposures, should be studied in more detail.

ELEMENTARY will investigate the potential risks for coastal and marine environments associated with anthropogenically released rare earth elements (REEs) and their rapidly increasing production and use. Although REEs are technology critical elements widely used in a range of applications including batteries, light source components, fuel additives, fertilisers and medical agents, virtually nothing is known about anthropogenic REE anomalies in Norwegian marine environments and their potential effects on marine species. ELEMENTARY will determine REE concentrations at potential release hot-spots on the Norwegian coast associated with mining, urban wastewater release and agricultural runoff. In laboratory studies, REE uptake and effects will be investigated in fish and sensitive early life stages of fish, representing environmentally and economically important model organisms. Based on our recent findings that gadolinium (Gd) is taken up into the brain and kidneys of wild fish caught close to a wastewater treatment plant outlet, we will use Gd as a model REE in the controlled exposure experiments. Applying advanced molecular effect screening techniques and targeted biomarker analyses, ELEMENTARY will determine effects and effect mechanisms. Analyses of REEs in selected biota collected from release hot-spots will be compared with REE concentrations determined in water and sediment to provide an increased understanding of REE bioavailability from different sources. This environmental assessment, together with targeted laboratory uptake and effect studies will provide a first evaluation on potential risks for the Norwegian coastal environment associated with REE use. By effectively communicating the knowledge generated, the project will contribute to increasing awareness of REEs as potential emerging pollutants in the environment and will provide information for strategically important national regulatory organisations such as the Norwegian Environment Agency.

Publications from Cristin

Funding scheme:

MARINFORSK-Marine ressurser og miljø