28 research outputs found

    Investigation of novel chemical in-situ treatment methods to mitigate cyanobacteria harmful algal blooms in surface waters

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    As water scarcity is becoming a universal problem to address, it is essential to maintain a high surface water quality and protect the biodiversity of current aquatic biotopes worldwide. Surface water contamination events caused by high nutrient and organic matter loads lead to the formation of cyano-HABs, which are mostly unpredictable. Therefore, highly efficient methods are required for the in-situ restoration of water quality. Several methods have been applied over the years to mitigate cyano-HABs with varying efficiencies. Current trends ask for more environmentally friendly approaches to be implemented in order to safeguard the overall aquatic ecosystems and reduce treatment costs. Hydrogen peroxide is currently being used as an emerging chemical alternative to copper algicides. Even though its broad application showed high efficiency on mitigating dense blooms, the required H2O2 doses for each case and treatment application differ, and in some instances high doses were applied with undesirable side effects on the entire lake ecosystem. Herein, calcium peroxide granules were utilized due to their slow H2O2 releasing properties, which simulate multiple liquid H2O2 doses. Specifically, granules were used in surface waters spiked with Microcystis, Aphanizomenon, and Cylindrospermopsis sp. and in actual water samples during blooming

    Shipborne vertical profiles of dust aerosols obtained with Unmanned Aerial Vehicles in the Mediterranean and the Middle East: First results ofthe AQABA campaign

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    International audienceAtmospheric aerosols have a large role in the earth climate through direct or indirect effects on the radiative energy budget. As the aerosol characteristics are highly variable spatially and in time, observations of these characteristics are needed in regions, where the climate change effects are the most severe. One of these types of hotspots is the East Mediterranean and Middle East (EMME region) (Lelieveld et al., 2012), however, high quality in-situ observations in the Middle East and Arabian Peninsula region are still missing. To gain such a high quality observations in this region, the "Air Quality and climate change in the Arabian Basin" (AQABA) oceanographic campaign was organized during summer 2017, shipping from France, through the Suez Canal and around the Arabian Peninsula to Kuwait and back to France. The total length of the campaign was more than 2 months. A wide spectrum of environmental conditions was encountered during the campaign, ranging from pristine conditions over the Indian Ocean, to dusty (low polluted) atmosphere in the Red Sea affected by the Saharan dust and the highly dusty and polluted Gulf. To add on the remote sensing data of aerosol characteristics above the sea surface collected on the ship, the Cyprus Institute's Unmanned Systems Research Laboratory (USRL) team deployed Unmanned Aerial Vehicles (UAVs) to gain in-situ observations of aerosol properties inside and above the marine boundary layer. A small, fixed wing UAV was hand launched from the ship, which then climbed up to 2000 m (a.s.l.) and then returned to the ship and landed on a net. A modified AlphaSense N-2 Optical Particle Counter (OPC) was used on board the UAV to observe the number size distribution of aerosol particles (range: 0.38-17.5 µm, with 16 channels). Meteorological parameters (T, RH and P), as well as a video was recorded also. A total of 16 Successful flights were made, mostly in the Mediterranean and in the Persian Gulf, with few flights in the Red Sea and the Arabian Sea. The presentation will show data acquired on board the UAVs and comparison with ceilometer data obtained on the ship to identify possible dust layers and other interesting events. The differences in aerosol size distributions inside and above the boundary layer will be discussed, as well as any interesting case studies or events during the measurements

    On-flight intercomparison of three miniature aerosol absorption sensors using unmanned aerial systems (UASs)

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    The present study investigates and compares the ground and in-flight performance of three miniaturized aerosol absorption sensors integrated on board small-sized Unmanned Aerial Systems (UASs). These sensors were evaluated during two contrasted field campaigns performed at an urban site, impacted mainly by local traffic and domestic wood burning sources (Athens, Greece), and at a remote regional background site, impacted by long-range transported sources including dust (Cyprus Atmospheric Observatory, Agia Marina Xyliatou, Cyprus). The miniaturized sensors were first intercompared at the ground-level against two commercially available instruments used as a reference. The measured signal of the miniaturized sensors was converted into the absorption coefficient and equivalent black carbon concentration (eBC). When applicable, signal saturation corrections were applied, following the suggestions of the manufacturers. The aerosol absorption sensors exhibited similar behavior against the reference instruments during the two campaigns, despite the diversity of the aerosol origin, chemical composition, sources, and concentration levels. The deviation from the reference during both campaigns concerning (eBC) mass was less than 8 %, while for the absorption coefficient it was at least 15 %. This indicates that those sensors that report black carbon mass are tuned and corrected to measure eBC more accurately than the absorption coefficient. The overall potential use of miniature aerosol absorption sensors on board small UASs is also illustrated. UAS-based absorption measurements were used to investigate the vertical distribution of eBC over Athens up to 1 km above sea level during January 2016, exceeding the top of the planetary boundary layer (PBL). Our results reveal a heterogeneous boundary layer concentration of absorbing aerosol within the PBL intensified in the early morning hours due to the concurrent peak traffic emissions at ground-level and the fast development of the boundary layer. After the full development of the PBL, homogenous concentrations are observed from 100 m a.g.l. to the PBL top

    Calcium peroxide (CaO2) granules enclosed in textile materials as H2O2 delivery systems to mitigate Microcystis sp.

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    The past years, hydrogen peroxide (H2O2) has been introduced as an environmentally friendly method to combat in-situ toxic cyanobacteria blooms because of its selective oxidation and zero waste production. Treatment with H2O2 proved to be efficient for several occasions and blooming events as it selectively suppresses cyanobacteria by inhibiting their photosynthetic activity [1,2]. However, blooms of Microcystissp. that were more persistent required higher H2O2 doses (> 7 mg/L) during treatment, doses that found to cause mobility issues to the zooplankton community of the aquatic ecosystem [3]. Calcium peroxide (CaO2) granules are an alternative to liquid H2O2 due to their slow H2O2 release properties, simulating multiple H2O2 doses [4]. In this study, concentrations of 0.5, 1.0, and 2.0 g/L CaO2 granules were (a) added into a surface water matrix to investigate their H2O2 releasing properties, (b) enclosed in four types of textile materials as delivery systems to evaluate their overall oxidant releasing capacity and (c) enclosed systems A – C were applied on a dense Microcystis sp. bloom to further investigate their suitability to combat cyanobacteria. No difference was observed between the maximum H2O2 concentrations of the direct application of granules and the fabric delivery systems of types A – C, which released up to 12 mg/L H2O2 from 2.0 g/L CaO2 granules. Fabric system type D had the lowest H2O2 releasing capacity (2.0 mg/L of H2O2 from 2.0 g/L CaO2 granules). Treatment experiments showed that granules enclosed in fabrics (GEF) type B of concentration 2 g/L and type C concentrations of 1 g/L and 2g/L were sufficient to reduce the photosynthetic activity of Microcystis species (<1000 RFU), proving that these delivery systems have the potential to become a more environmentally friendly alternative to H2O2. The process minimizes granules availability into the water matrix, and hence eliminate adverse impact on nontargeted species. Moreover, GEF systems promote circular economy by implementing practices that make use of reused and recycled fabrics

    Climate change due to heat and drought stress can alter the physiology of Maratheftiko local Cyprian grapevine variety

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    The effect of climate change (CC) on viticulture in Europe is of great concern and several international and indigenous grapevine cultivars have been examined for their adaptation to CC. In this study we focused on the short-term effects of light and moderate drought stress (DS) as well as heat stress (HS) on physiological and biochemical stress markers in Maratheftiko cultivar. We showed that leaf photosynthetic rate was decreased with DS and HS after 8 and 20 days. The leaf stomatal conductance was decreased in the case of DS after 8 days, while no differences could be found due to HS. Total phenols and flavonoids content and antioxidant capacity (FRAP and ABTS) were increased and seemed to be dependent on the relevant DS, HS and the period of stress exposure. Chlorophyll fluorescence was decreased in 50% volumetric water content (VWC) after 8 days of DS compared with the 100% VWC (control treatment). Leaf K and P content increased in moderate (50% VWC) irrigation stress and HS. Leaf hydrogen peroxide and lipid peroxidation increased after 8 days of DS, and this resulted in the increase of antioxidant enzymes activity. Overall, Maratheftiko performance against environmental stresses is related more to short-term DS than HS

    The role of cavity losses on non-adiabatic couplings and dynamics in polaritonic chemistry

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    We present a non-Hermitian formulation of the polaritonic structure of azobenzene strongly coupled to a photonic mode that explicitly accounts for the fleeting nature of the photon-molecule interaction. This formalism reveals that the polaritonic non-adiabatic couplings that facilitate cis-trans isomerization can be dramatically modified by photonic dissipation. We perform Fewest-Switches Surface Hopping dynamics on the surfaces that derive from our non-Hermitian formalism and find that the polaritonic isomerization yields are strongly suppressed for moderate dissipation rates, and that cavity-free isomerization dynamics are recovered under large dissipation rates. These findings highlight the important role that the finitelifetime of photonic degrees of freedom play in polaritonic chemistry.</p

    Climate change due to heat and drought stress can alter the physiology of Maratheftiko local Cyprian grapevine variety

    No full text
    The effect of climate change (CC) on viticulture in Europe is of great concern and several international and indigenous grapevine cultivars have been examined for their adaptation to CC. In this study we focused on the short-term effects of light and moderate drought stress (DS) as well as heat stress (HS) on physiological and biochemical stress markers in Maratheftiko cultivar. We showed that leaf photosynthetic rate was decreased with DS and HS after 8 and 20 days. The leaf stomatal conductance was decreased in the case of DS after 8 days, while no differences could be found due to HS. Total phenols and flavonoids content and antioxidant capacity (FRAP and ABTS) were increased and seemed to be dependent on the relevant DS, HS and the period of stress exposure. Chlorophyll fluorescence was decreased in 50% volumetric water content (VWC) after 8 days of DS compared with the 100% VWC (control treatment). Leaf K and P content increased in moderate (50% VWC) irrigation stress and HS. Leaf hydrogen peroxide and lipid peroxidation increased after 8 days of DS, and this resulted in the increase of antioxidant enzymes activity. Overall, Maratheftiko performance against environmental stresses is related more to short-term DS than HS

    Effects of selenium and/or arbuscular mycorrhizal fungal inoculation on strawberry grown in hydroponic trial

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    Strawberry is considered as a fruit of high nutritional value, with appreciated benefits on human health. Arbuscular mycorrhizal fungi (AMF) are commonly used plant symbionts that affect plant growth and its effectiveness is plant species specific. Additionally, selenium (Se) projects a special interest to humans for its antioxidant specialties, and to plants, because of the potential to make them grow faster when added to the nutrient solution. Nonetheless, the performance of arbuscular mycorrhizal fungi (AMF) in Se biofortification in strawberry is unexplored. The purpose of the present study experiment was to determine whether mycorrhizal inoculation of AMF can have a positive impact on growth and quality of strawberries, and whether Se contributes in this effort or will adversely affect the plants. Four Se concentrations (0, 1, 5 and 10 mg L−1 ) in the nutrient solution, with or without mycorrhizal inoculation of AMF to the root system, were evaluated. Results demonstrated that Se of 10 mg L−1 negatively affected plant growth, photosynthetic rates, decreased fruit firmness and total soluble solids, induced oxidative stress in fruits and affected nutrient accumulation in different plant organs. Mycorrhizal inoculation of AMF mainly stimulated antioxidative mechanisms of the fruits and increased nutrient accumulation for plants grown at high Se levels. Based on our observations, mycorrhizal inoculation can enhance the nutritional value of strawberry fruits and strawberry plants seem to be a strong candidate for Se biofortification, allowing the rise of Se of the consumers’ intake
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