Skip to content. | Skip to navigation

Personal tools

You are here: Home

Search results

RSS Subscribe to an always-updated RSS feed.

972 items matching your search terms.
Filter the results.
Item type



































New items since



Sort by relevance · date (newest first) · alphabetically
Manual Reference Potential impact of wash water effluents from scrubbers on water acidification in the southern North Sea
Sulphur Oxides (SOx) in atmospheric ship emissions resulting from the burning of fuel with high sulphur content are known to be harmful to human and ecosystem health. Since January 1st 2020, the International Maritime Organisation (IMO) lowered the previous limit for sulphur content in ship fuel from 3.5% m/m (mass by mass) to 0.50%. In the emission control areas (SECAs), the limit for the sulphur content had been set to 1.0% in 2010 and is kept below 0.1% since 2015. To comply with these limits, ship operators and owners can switch to fuel oil with lower sulphur content (LSFO). Alternatively, they can continue to burn fuel with high sulphur content by using technical means such as exhaust gas cleaning systems (or scrubbers) that reduce the atmospheric SOx emissions to a level equivalent to the required fuel oil sulphur limit. Scrubbers use sea water as cleaning media to remove SOx from the air emissions. There are three main categories of scrubbers: (1) the open-loop scrubbers that continuously discharge their wash water effluent, (2) the closed-loop scrubbers that treat the wash water before it is discharged, and (3) the hybrid scrubbers that can switch from open to closed modes. Scrubbers transform the air pollution into direct marine discharge. As hybrid scrubbers are more likely to discharge their sulphur waste into sea water rather than using land infrastructures, they are hereafter taken as open-loop ones. The effect of SOx contribution from ship on sea water pH is assessed for the English Channel and the southern North Sea by means of a marine biogeochemical model that includes a detailed description of the carbonate chemistry. This model allows testing different scenarios of SOx contribution resulting from the maritime traffic. To this end, realistic scenarios with ship traffic density estimated for the years 2019, 2020 and 2030, assuming a year-to-year ship traffic increase of 3.5% and several SOx pollution reduction strategies have been tested. An additional model simulation with null SOx contribution from the shipping sector is used as a reference level to comparatively assess the impact of each scenario on the sea water pH. Model results show a pH decrease of 0.004 units over the whole domain in case of a 2019-like ship traffic density with 15% of the fleet (in Gross Tonnage) using open-loop and hybrid scrubber systems. For future scenarios, assuming that 35% of the fleet is equipped with open-loop and hybrid scrubbers, the pH is estimated to decrease by 0.008 to 0.010 units in average over the whole domain. The magnitude of pH changes is not evenly distributed through space. According to the model results, the largest pH changes would occur in areas of high traffic density, such as along the Belgian and Dutch coasts and in the vicinity of large harbours such as Rotterdam. Ocean acidification rate attributed to climate change is estimated at 0.0017-0.0027 pH units per year. In comparison, the total pH decrease owing to the use of open-loop scrubbers would be equivalent to 2 to 4 years of climate change acidification on average over the whole domain, and to 10 to 50 years, in more local areas. The cumulative impact of ocean acidification due to climate change and to maritime traffic should therefore be considered in ecosystem assessment studies.
Located in Library / RBINS Staff Publications 2020
Article Reference Food nutrient availability affects epibiont prevalence and richness in natural Daphnia populations
Located in Library / RBINS Staff Publications 2020
Article Reference Quality-control tests for OC4, OC5 and NIR-red satellite chlorophyll-a algorithms applied to coastal waters
Reliable satellite estimates of chlorophyll-a concentration (Chl-a) are needed in coastal waters for applications such as eutrophication monitoring. However, because of the optical complexity of coastal waters, retrieving accurate Chl-a is still challenging. Many algorithms exist and give quite different performance for different optical conditions but there is no clear definition of the limits of applicability of each algorithm and no clear basis for deciding which algorithm to apply to any given image pixel (reflectance spectrum). Poor quality satellite Chl-a data can easily reach end-users. To remedy this and provide a clear decision on when a specific Chl-a algorithm can be used, we propose simple quality control tests, based on MERIS water leaving reflectance (ρw) bands, to determine on a pixel-by-pixel basis if any of three popular and complementary algorithms can be used. The algorithms being tested are: 1. the OC4 blue-green band ratio algorithm which was designed for open ocean waters; 2. the OC5 algorithm which is based on look-up tables and corrects OC4 overestimation in moderately turbid waters and 3. a near infrared-red (NIR-red) band ratio algorithm designed for eutrophic waters. Using a dataset of 348 in situ Chl-a / MERIS matchups, the conditions for reliable performance of each of the selected algorithms are determined. The approach proposed here looks for the best compromise between the minimization of the relative difference between In situ measurements and satellite estimations and the number of pixels processed. Conditions for a reliable application of OC4 and OC5 depend on ρw412/ρw443 and ρw560, used as proxies of coloured dissolved organic matter and suspended particulate matter (SPM), as compared to ρw560/ρw490, used as a proxy for Chl-a. Conditions for reliable application of the NIR-red band ratio algorithm depend on Chl-a and SPM. These conditions are translated into pixel-based quality control (QC) tests with appropriately chosen thresholds. Results show that by removing data which do not pass QC, the performance of the three selected algorithms is significantly improved. After combining these algorithms, 70\% of the dataset could be processed with a median absolute percent difference of 30.5\%. The QC tests and algorithm merging methodology were then tested on four MERIS images of European waters. The OC5 algorithm was found to be suitable for most pixels, except in very turbid and eutrophic waters along the coasts where the NIR-red band ratio algorithm helps to fill the gap. Finally, a test was performed on an OLCI-S3A image. Although some validations of water reflectance are still needed for the OLCI sensors, results show similar behavior to the MERIS applications which suggests that when applied to OLCI data the present methodology will help to accurately estimate Chl-a in coastal waters for the next decade.
Located in Library / RBINS Staff Publications 2022
Article Reference Monitoring of high biomass Phaeocystis globosa blooms in the Southern North Sea by in situ and future spaceborne hyperspectral radiometry
Phaeocystis globosa (P. globosa hereafter) is a phytoplankton species which commonly blooms at high biomass in April–May in the Southern North Sea and forms undesirable foam which accumulates on the beaches. Monitoring of this species is required by EU directives. Measurement of phytoplankton species composition has historically been made by pigment or microscopic analysis of water samples, which is spatially sparse and temporally infrequent e.g. weekly/monthly. In-water instruments such as flow cytometers can provide very high frequency data but at high acquisition and maintenance cost. Automated in situ above water radiometry has the potential to provide very high frequency data at single locations but requires very careful design of processing algorithms in turbid waters with high non-algal absorption. Spaceborne radiometry could provide both very good spatial coverage and moderate/high frequency of data, e.g. daily/weekly, but accurate determination of phytoplankton species composition is considerably more difficult in turbid waters than in open ocean waters. Prior studies based on a limited number of shipborne reflectance measurements suggested feasibility of P. globosa detection in turbid waters from hyperspectral radiometry. The availability of a new autonomous above water hyperspectral radiometer system has enabled further refinement and intensive testing of these techniques. From a time-series of 4356 water reflectance spectra measured near Ostend harbour in Belgian coastal waters from 2020/04/01 to 2020/08/18, two existing algorithms for P. globosa detection were successfully applied. Results show a high biomass P. globosa bloom occurring in late-April/early-May as found every year in water sample analyses for Belgian coastal waters. The high temporal resolution of the radiometric data allows to capture the evolution of the bloom at time scales sufficiently short (hourly and daily) compared to growth/decay and tidal processes. The challenges of extending the methods to future spaceborne instruments are also tested by simulating the impact of errors in sensor inter-band calibration, atmospheric correction and radiometric noise. Results show that because of their spectral coherence, atmospheric correction errors impact only slightly P. globosa detection whereas inaccuracy in inter-band calibration and radiometric noise are much more problematic as they affect each spectral band independently. Because radiometric noise should be reduced in the new generation of hyperspectral sensors and can always be reduced by spatial binning, the inter-band relative calibration uncertainty appears to be the main challenge for spaceborne mission design. Indeed, it was demonstrated that inter-band calibration error should be 0.25\% and ideally 0.1\% at top of the atmosphere highlighting the need for particular attention to inter-band calibration in sensor design and post processing treatments including vicarious calibration.
Located in Library / RBINS Staff Publications 2022
Article Reference Using Hyperspectral Remote Sensing to Monitor Water Quality in Drinking Water Reservoirs
At the Blankaart Water Production Center, a reservoir containing 3 million m3 of raw surface water acts as a first biologic treatment step before further processing to drinking water. Over the past decade, severe algal blooms have occurred in the reservoir, hampering the water production. Therefore, strategies (e.g., the injection of algaecide) have been looked at to prevent these from happening or try to control them. In this context, the HYperspectral Pointable System for Terrestrial and Aquatic Radiometry (HYPSTAR), installed since early 2021, helps in monitoring the effectiveness of these strategies. Indeed, the HYPSTAR provides, at a very high temporal resolution, bio-optical parameters related to the water quality, i.e., Chlorophyll-a (Chla) concentrations and suspended particulate matter (SPM). The present paper shows how the raw in situ hyperspectral data (a total of 8116 spectra recorded between 2021-02-03 and 2022-08-03, of which 2988 spectra passed the quality check) are processed to find the water-leaving reflectance and how SPM and Chla are derived from it. Based on a limited number of validation data, we also discuss the potential of retrieving phycocyanin (an accessory pigment unique to freshwater cyanobacteria). The results show the benefits of the high temporal resolution of the HYPSTAR to provide near real-time water quality indicators. The study confirms that, in conjunction with a few water sampling data used for validation, the HYPSTAR can be used as a quick and cost-effective method to detect and monitor phytoplankton blooms.
Located in Library / RBINS Staff Publications 2022
Article Reference The HYPERMAQ dataset: bio-optical properties of moderately to extremely turbid waters
Because of the large diversity of case 2 waters ranging from extremely absorbing to extremely scattering waters and the complexity of light transfer due to external terrestrial inputs, retrieving main biogeochemical parameters such as chlorophyll-a or suspended particulate matter concentration in these waters is still challenging. By providing optical and biogeochemical parameters for 180 sampling stations with turbidity and chlorophyll-a concentration ranging from 1 to 700 FNU and from 0.9 to 180 mg m−3 respectively, the HYPERMAQ dataset will contribute to a better description of marine optics in optically complex water bodies and can help the scientific community to develop algorithms. The HYPERMAQ dataset provides biogeochemical parameters (i.e. turbidity, pigment and chlorophyll-a concentration, suspended particulate matter), apparent optical properties (i.e. water reflectance from above water measurements) and inherent optical properties (i.e. absorption and attenuation coefficients) from six different study areas. These study areas include large estuaries (i.e. the Rio de la Plata in Argentina, the Yangtze estuary in China, and the Gironde estuary in France), inland (i.e. the Spuikom in Belgium and Chascomùs lake in Argentina), and coastal waters (Belgium). The dataset is available from Lavigne et al. (2022) at https://doi.org/10.1594/PANGAEA.944313.
Located in Library / RBINS Staff Publications 2022
Article Reference Microrestes gen. nov., a new genus in the Oriental stick insect tribe Datamini Rehn & Rehn, 1939 with a new species and a new combination (Phasmida: Heteropterygidae: Dataminae)
Located in Library / RBINS Staff Publications 2020
Article Reference Lasioglossum dorchini (Hymenoptera: Apoidea: Halictidae) a new species of bee from Israel
This paper describes a new species, Lasioglossum dorchini, occuring in sand dunes in Israel. It is close to Lasioglossum leptocephalum. Its phylogenetic relationships with the other species of the virens/littorale group are analyzed
Located in Library / RBINS Staff Publications 2020
Inproceedings Reference A masculinizing supergene underlies the male dimorphism of Oedothorax gibbosus
Located in Library / RBINS Staff Publications 2023 OA
Inproceedings Reference Finding the balance between efficiency and budget: preventive invasive mosquito species (IMS) surveillance
Located in Library / RBINS Staff Publications 2023 OA