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Magmatic, Magmatic-Hydrothermal, and Deformational Mineral Evolution of Spodumene Pegmatites from the Musha-Ntunga Area (Rwanda)
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Pegmatites in the Mesoproterozoic Karagwe-Ankole belt of Central Africa are associated with large granitic complexes that were emplaced around 1 Ga. This study analyzes drill core samples of fresh albite-spodumene pegmatites from the Musha-Ntunga area (East Rwanda), spatially associated with the Lake Muhazi granitic pluton. We combine petrographic and cathodoluminescence microscopy with Raman spectroscopy and elemental geochemistry to study the paragenetic sequence, microtextural variations, and lithium distribution, from the magmatic and magmatic-hydrothermal stages to the hydrothermal stage and during deformation processes. Five textural types of spodumene are distinguished. Coarse-grained spodumene type 1 and symplectitic type 2 are interpreted to have formed during primary magmatic crystallization, whereas spodumene types 3 and 4 formed during magmatic-hydrothermal alteration. Deformation locally affected the pegmatite intrusions. Spodumene type 1 crystals deformed in a brittle and ductile manner, displaying sigma-clast-shaped porphyroclasts (“spodumene fish”) and boudinage textures. The large strained spodumene crystals were also partially recrystallized to fine-grained elongated crystals (type 5), which occur in bands along with mica, quartz, and apatite and define the main orientation of foliation. Montebrasite occurs both as a late primary magmatic phase with spodumene and as a secondary phase that recrystallized during magmatic-hydrothermal alteration and deformation. Eucryptite, lithiophilite, and cookeite occur as late-stage hydrothermal phases, replacing primary lithium assemblages. Associated phases muscovite, apatite, microcline, albite, quartz, and columbite-tantalite further demonstrate the transition from a magmatic to a (magmatic-)hydrothermal and deformational regime. Elevated lithium contents in tourmaline within the metasedimentary host rock indicate dispersion of lithium into the host rock during pegmatite emplacement, subsequent crystallization, and alteration. The results of this multimethod approach demonstrate that different generations of lithium-bearing minerals and associated textures not only record the full transition from a magmatic to hydrothermal regime but also document deformation-related processes that can impact the distribution of metals within pegmatites.
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RBINS Staff Publications 2025
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Generation of super-resolution gap-free ocean colour satellite products using data-interpolating empirical orthogonal functions (DINEOF)
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In this work we present a super-resolution approach for deriving high-spatial-resolution and high-temporal-resolution ocean colour satellite datasets. The technique is based on DINEOF (data-interpolating empirical orthogonal functions), a data-driven method that uses the spatio-temporal coherence of analysed datasets to infer missing information. DINEOF is used here to effectively increase the spatial resolution of satellite data and is applied to a combination of Sentinel-2 and Sentinel-3 datasets. The results show that DINEOF is able to infer the spatial variability observed in the Sentinel-2 data to the Sentinel-3 data while reconstructing missing information due to clouds and reducing the amount of noise in the initial dataset. In order to achieve this, the Sentinel-2 and Sentinel-3 datasets have undergone the same pre-processing, including a comprehensive, region-independent, and pixel-based automatic switching scheme for choosing the most appropriate atmospheric correction and ocean colour algorithm to derive in-water products. The super-resolution DINEOF has been applied to two different variables (turbidity and chlorophyll) and two different domains (Belgian coastal zone and the whole of the North Sea), and the sub-mesoscale variability of the turbidity along the Belgian coastal zone has been studied.
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RBINS Staff Publications 2025
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A generalized physics-based correction for adjacency effects
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Atmospheric scattering occurs over a horizontal scale of several kilometers. This results in influence from neighboring surface features on the signal recorded over a given position, reducing contrast and the accuracy of quantitative retrievals of surface reflectance from satellite imagery. This atmospheric blurring, or adjacency effect, must be accounted for when both contrast in surface reflectance and magnitude of atmospheric scattering are significant. Taking into account the adjacency effect is of particular importance for aquatic remote sensing of inland and coastal waters due to the high contrast between water and different land cover types, as well as the small spatial scale of most inland water bodies. In this paper, we present a physics-based processor to retrieve surface reflectance over all surface types, regardless of the subscene composition and sensor waveband configuration. The processor is implemented in the free and open source ACOLITE software and is composed of two modules: (1) TSDSF for the estimation of aerosol properties and (2) RAdCor for the retrieval of surface reflectance. We demonstrate the performance of the TSDSF $+$ RAdCor processor for the Operational Land Imager (OLI) onboard Landsat 8 and the Multispectral Instrument (MSI) onboard Sentinel-2A and 2B over a set of small ($\lt1\;\rm km^2$) inland waters in Belgium, and compare the performance with other common processors for these sensors, including C2RCC, POLYMER, Sen2Cor, iCOR, ACOLITE/DSF, and LaSRC. For clear sky matchups, the relative deviation againstin situ data in the visible wavebands ranged between 6% and 18% for OLI, and between 14% and 31% for MSI, except for the MSI waveband centered at 443 nm where the relative deviation was 70%. In the near-infrared wavebands, the relative deviation varied from 70% to 150%, with the exception of the MSI waveband centered at 704 nm, for which the performance was 17%. Overall, the new processor outperformed the other evaluated processors in the visible range, with the exception of the MSI waveband centered at 443 nm, and was outperformed by C2RCC and POLYMER in the near-infrared wavebands. Recommendations on how to use TSDSF and RAdCor in ACOLITE are provided.
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RBINS Staff Publications 2025
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Atmospheric Correction Inter-Comparison eXercise, ACIX-III Land: An Assessment of Atmospheric Correction Processors for EnMAP and PRISMA over Land
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Correcting atmospheric effects on hyperspectral optical satellite scenes is paramount to ensuring the accuracy of derived bio-geophysical products. The open-access benchmark Atmospheric Correction Inter-comparison eXercise (ACIX) was first initiated in 2016 and has now been extended to provide a comprehensive assessment of atmospheric processors of space-borne imaging spectroscopy missions (EnMAP and PRISMA) over land surfaces. The exercise contains 90 scenes, covering stations of the Aerosol Robotic Network (AERONET) for assessing aerosol optical depth (AOD) and water vapour (WV) retrievals, as well as stationary networks (RadCalNet and HYPERNETS) and ad hoc campaigns for surface reflectance (SR) validation. AOD, WV, and SR retrievals were assessed using accuracy, precision, and uncertainty metrics. For AOD retrieval, processors showed a range of uncertainties, with half showing overall uncertainties of <0.1 but going up to uncertainties of almost 0.4. WV retrievals showed consistent offsets for almost all processors, with uncertainty values between 0.171 and 0.875 g/cm2. Average uncertainties for SR retrievals depend on wavelength, processor, and sensor (uncertainties are slightly higher for PRISMA), showing average values between 0.02 and 0.04. Although results are biased towards a limited selection of ground measurements over arid regions with low AOD, this study shows a detailed analysis of similarities and differences of seven processors. This work provides critical insights for understanding the current capabilities and limitations of atmospheric correction algorithms for imaging spectroscopy, offering both a foundation for future improvements and a first practical guide to support users in selecting the most suitable processor for their application needs.
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RBINS Staff Publications 2025
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Contrasting toxicity between explosives– and chemical warfare agents–related compounds to the marine primary producer <i>Phaeodactylum tricornutum</i>
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Vast amounts of munitions dumped in the marine environment, have been reported to leak chemicals due to munition corrosion. The subsequent increased levels of explosives and related chemicals (E&RC), as well as chemical warfare agents and related chemicals (CWA&RC), raise risks for environmental and human health Yet, ecotoxicity data on primary producers is currently scarce. Therefore, this study investigated the acute effects of three CWA&RC (1,4-oxathiane, 1,4-dithiane, and thiodiglycol) and four E&RC (2,4,6-trinitrotoluene (TNT), tetryl, 1,3-dinitrobenzene (1,3-DNB), and picric acid) on Phaeodactylum tricornutum, a key marine diatom at the basis of the aquatic food web. Results showed that none of the three CWA&RC significantly inhibited the growth rate of Phaeodactylum tricornutum at the tested concentrations. Interestingly, picric acid stimulated growth up under the experimental conditions, suggesting a hormetic effect. TNT, tetryl, and 1,3-DNB strongly inhibited growth, with experimentally derived EC10 and EC50 values approaching environmentally relevant concentrations near dumpsites. Consequently, diatom biomass may be significantly affected by TNT, tetryl, and 1,3-DNB, potentially disturbing primary production and ocean chemistry. Future research should examine potential synergies between munition compounds and other marine pollutants, which may aggravate toxic effects, as well as consider long-term toxicity tests.
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RBINS Staff Publications 2026
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Assessing the chemical burden of the North-East Atlantic ecosystem through targeted and untargeted HRMS-based approaches
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Human activities have introduced significant amounts of anthropogenic chemicals into marine ecosystems, posing threats to aquatic biodiversity and human health. Although, traditional marine monitoring focus primarily on legacy pollutants, the presence and potential risks associated with complex emerging chemical mixtures should not be neglected. In the context of the present study organized via OSPAR Commission and supported by NORMAN network, 52 marine samples were gathered from North-East Atlantic Ocean. State-of-the-art HRMS-based analytical workflows were employed to identify their chemical fingerprint. 132 organic pollutants were identified through wide-scope target screening of more than 2,400 environmentally relevant organic pollutants. The HRMS data were digitally stored in NORMAN DSFP and 134 additional chemicals were tentatively identified through suspect screening of more than 65,000 chemicals. The list included legacy pollutants, along with emerging pollutants, their metabolites and transformation products. A simplified environmental risk assessment was conducted, aiming to prioritize substances based on their potential risks to the marine ecosystem. This study provides a valuable snapshot of the marine pollution, offering insights into chemical occurrence and risks. The findings can support marine scientists, environmental managers and policymakers in identifying pollutant sources, understanding their impacts, and informing regulatory measures to mitigate threats to marine ecosystems.
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RBINS Staff Publications 2025
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Diagnosing the Flocculation–Transport Dynamics of Suspended Particulate Matter Using a Two-Class Population Balance Model and Bayesian Calibration
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Abstract The dynamics of suspended particulate matter (SPM) plays a crucial role in determining water quality, sediment transport, and biogeochemical cycles in inland, estuarine, and coastal water resources. Flocculation processes strongly influence the SPM dynamics via aggregation and breakage under various hydrodynamic and biogeochemical conditions. This study introduces a mechanistic and diagnostic framework that combines a two-class population balance equation (TCPBE) model with Bayesian calibration to simulate flocculation?transport behavior in both laboratory- (time-dependent batch) and field-scale (one-dimensional vertical) systems. Laboratory experiments with biopolymer?clay and microalgae?clay mixtures and field observations from an estuarine turbidity maximum zone are used to derive a comprehensive data set for model validation. Bayesian inference enables the estimation of uncertain model parameters while characterizing their statistical properties, thus supporting the mechanistic interpretation of flocculation dynamics. By quantifying how ionic strength and microbial physiology regulate flocculation kinetics and elucidating the turbulence-driven coupling between flocculation kinetics and sediment transport over tidal cycles, the framework demonstrates its suitability as a process-based diagnostic tool capable of effectively capturing SPM dynamics under various conditions. This framework has strong potential to advance the understanding of flocculation dynamics and support a range of applications in inland and estuarine sediment-laden water systems, including river, reservoir, esturine and coastal waters.
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RBINS Staff Publications 2026
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Evaluating the toxicity of sea-dumped conventional and chemical munition degradation products to fish and human cells using a combination of cell viability assays
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The disposal of munitions in marine coastal areas after World Wars I and II has raised significant concerns about environmental contamination and human health risks. This study investigates the acute cytotoxicity of munition-related chemicals commonly detected near marine dumpsites, focusing on degradation products of explosives and related compounds (E&RC) and degradation products of chemical warfare agents and related compounds (CWA&RC). The research examines three CWA&RC (1,4-oxathiane, 1,4-dithiane, thiodiglycol) and four E&RC (2,4,6-trinitrotoluene, tetryl, 1,3-dinitrobenzene, picric acid) using the RTgill-W1 cell line (rainbow trout gill cells) as a proxy for fish toxicity and human cell lines (Caco2 and HepG2) to model potential human exposure via contaminated seafood. The results indicate low acute cytotoxicity of CWA&RC, while E&RC exhibit significantly higher toxicity. Notably, the EC10 and EC50 values for tetryl and 1,3-DNB in RTgill-W1 align with concentrations detected near North American dumpsites, reflecting environmentally relevant conditions. The study also reveals inter-species and inter-organ variability in toxicity mechanisms, identifying potential adverse outcome pathways such as AOP 220. These findings highlight the need for further research into chronic exposure scenarios at environmentally realistic concentrations and contribute crucial data to understanding the risks posed by the degradation products of these chemicals to aquatic life and human health.
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RBINS Staff Publications 2025
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Flocculation dynamics of suspended particulate matter under various tidal conditions
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Understanding the flocculation dynamics of suspended particulate matter is essential for a comprehensive understanding of sediment transport in estuarine and coastal ecosystems. Field observations were conducted during both spring and neap tidal cycles at two contrasting sites, the highly turbulent, low-salinity Xuliujing site of the Yangtze River estuary, and the weakly turbulent, high-salinity Belgian coastal station MOW1. The two sites exhibited different flocculation dynamics and floc size distributions (FSDs). At Xuliujing, strong river discharge and pronounced ebb dominance intensified turbulent shear, making the fragmentation of flocs the governing process. This resulted in multimodal FSDs with high proportions of microflocs (∼13 μm) and macroflocs (∼55 μm). In contrast, at MOW1, high salinity and relatively weak, symmetric tidal currents favored salt-enhanced aggregation, resulting in larger, more stable flocs and more uniform FSDs. These contrasts indicate that in freshwater environments, turbulence controls both aggregation and breakup, whereas in saline waters, salinity governs aggregation and turbulence primarily limits the maximum size of flocs. Furthermore, a one-dimensional vertical hydrodynamic model coupled with a population balance flocculation model demonstrated satisfactory accuracy in simulating current velocities, suspended particulate matter concentrations, and FSDs at both sites, showing its capability to capture flocculation dynamics under different environmental conditions.
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RBINS Staff Publications 2026
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Assessing the risk of booster biocides for the marine environment: A case study at the Belgian part of the North Sea
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The biofouling of submerged surfaces such as ship hulls is often prevented by using anti-fouling components in combination with booster biocides. These booster biocides enter the water column and may affect non-target organisms. Although different negative effects have been associated with the use of booster biocides, their effects on non-target organisms are often unknown. So far, the environmental risks for booster biocides have barely been quantified in the North Sea. In this work, the concentration of five commonly used booster biocides as well as tributyltin has been monitored at five dredged spoil disposal sites in the Belgian part of the North Sea and the harbour and ports of Nieuwpoort, Oostende, and Zeebrugge. Hotspots were discovered where the concentration of one or more booster biocides exceeded the predicted no-effect concentration. Tributyltin has been banned since 2008, but concentrations of 237- to 546-fold of the predicted no-effect concentration were detected in the harbours and ports. Moreover, TBT has been detected in the same order of magnitude in other sea basins, emphasizing the need to monitor the trends and impact of booster biocides and TBT in environmental monitoring programs.
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RBINS Staff Publications 2023
