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Microplastic dispersal behavior in a novel overhead stirring aqueous exposure system Texto completo
2020
Salaberria, Iurgi | Nadvornik-Vincent, Colette | Monticelli, Giovanna | Altin, Dag | Booth, Andy
Microplastic dispersal behavior in a novel overhead stirring aqueous exposure system Texto completo
2020
Salaberria, Iurgi | Nadvornik-Vincent, Colette | Monticelli, Giovanna | Altin, Dag | Booth, Andy
Using nominal dose metrics to describe exposure conditions in laboratory-based microplastic uptake and effects studies may not adequately represent the true exposure to the organisms in the test system, making data interpretation challenging. In the current study, a novel overhead stirring method using flocculators was assessed for maintaining polystyrene (PS) microbeads (Ø10.4 μm; 1.05 g cm−3) in suspension in seawater during 24 h and then compared with static and rotational exposure setups. Under optimized conditions, the system was able to maintain 59% of the initial PS microbeads in suspension after 24 h, compared to 6% using a static system and 100% using a rotating plankton wheel. Our findings document for the first time that overhead stirring as well as other, commonly used exposure systems (static) are unable to maintain constant microplastic exposure conditions in laboratory setups whereas rotation is very effective. This suggests toxicological studies employing either static or overhead stirring systems may be greatly overestimating the true microplastic exposure conditions. | publishedVersion
Mostrar más [+] Menos [-]Microplastic dispersal behavior in a novel overhead stirring aqueous exposure system Texto completo
2020
Salaberria, Iurgi | Nadvornik-Vincent, Colette | Monticelli, Giovanna | Altin, Dag | Booth, Andy M.
Using nominal dose metrics to describe exposure conditions in laboratory-based microplastic uptake and effects studies may not adequately represent the true exposure to the organisms in the test system, making data interpretation challenging. In the current study, a novel overhead stirring method using flocculators was assessed for maintaining polystyrene (PS) microbeads (Ø10.4 μm; 1.05 g cm⁻³) in suspension in seawater during 24 h and then compared with static and rotational exposure setups. Under optimized conditions, the system was able to maintain 59% of the initial PS microbeads in suspension after 24 h, compared to 6% using a static system and 100% using a rotating plankton wheel. Our findings document for the first time that overhead stirring as well as other, commonly used exposure systems (static) are unable to maintain constant microplastic exposure conditions in laboratory setups whereas rotation is very effective. This suggests toxicological studies employing either static or overhead stirring systems may be greatly overestimating the true microplastic exposure conditions.
Mostrar más [+] Menos [-]Gaps in current Baltic Sea environmental monitoring – Science versus management perspectives Texto completo
2020
Kahlert, Maria | Eilola, Kari | Mack, Leoni | Meissner, Kristian | Sandin, Leonard | Strömberg, Helena | Uusitalo, Laura | Viktorsson, Lena | Liess, Antonia
Gaps in current Baltic Sea environmental monitoring – Science versus management perspectives Texto completo
2020
Kahlert, Maria | Eilola, Kari | Mack, Leoni | Meissner, Kristian | Sandin, Leonard | Strömberg, Helena | Uusitalo, Laura | Viktorsson, Lena | Liess, Antonia
Legislations and commitments regulate Baltic Sea status assessments and monitoring. These assessments suffer from monitoring gaps that need prioritization. We used three sources of information; scientific articles, project reports and a stakeholder survey to identify gaps in relation to requirements set by the HELCOM's Baltic Sea Action Plan, the Marine Strategy Framework Directive and the Water Framework Directive. The most frequently mentioned gap was that key requirements are not sufficiently monitored in space and time. Biodiversity monitoring was the category containing most gaps. However, whereas more than half of the gaps in reports related to biodiversity, scientific articles pointed out many gaps in the monitoring of pollution and water quality. An important finding was that the three sources differed notably with respect to which gaps were mentioned most often. Thus, conclusions about gap prioritization for management should be drawn after carefully considering the different viewpoints of scientists and stakeholders. | publishedVersion
Mostrar más [+] Menos [-]Gaps in current Baltic Sea environmental monitoring – Science versus management perspectives Texto completo
2020
Kahlert, Maria | Eilola, Kari | Mack, Leoni | Meissner, Kristian | Sandin, Leonard | Strömberg, Helena | Uusitalo, Laura | Viktorsson, Lena | Liess, Antonia
Legislations and commitments regulate Baltic Sea status assessments and monitoring. These assessments suffer from monitoring gaps that need prioritization. We used three sources of information; scientific articles, project reports and a stakeholder survey to identify gaps in relation to requirements set by the HELCOM's Baltic Sea Action Plan, the Marine Strategy Framework Directive and the Water Framework Directive. The most frequently mentioned gap was that key requirements are not sufficiently monitored in space and time. Biodiversity monitoring was the category containing most gaps. However, whereas more than half of the gaps in reports related to biodiversity, scientific articles pointed out many gaps in the monitoring of pollution and water quality. An important finding was that the three sources differed notably with respect to which gaps were mentioned most often. Thus, conclusions about gap prioritization for management should be drawn after carefully considering the different viewpoints of scientists and stakeholders.
Mostrar más [+] Menos [-]Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
External damages are indicators of the overall quality of fish and fish welfare. Haddock is an important commercial species widespread in the North Atlantic, but few studies related to quality have been carried out on this species. We studied the levels of external damages on haddock captured with a demersal trawl in the Northeast Atlantic. Further, we investigated to what extent the compulsory sorting grid and diamond mesh codend gear configuration employed in this trawl fishery is responsible for the external damages observed during the capture process. We evaluated external damages on 563 haddock captured over 22 hauls. In general, the results showed that catching haddock without any gear inflicted damages using demersal trawls is challenging. However, the results also showed that the severity of most damages is low and the probability to catch haddock with no external damage can be significantly increased removing the grid and changing codend design. | publishedVersion
Mostrar más [+] Menos [-]Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
External damages are indicators of the overall quality of fish and fish welfare. Haddock is an important commercial species widespread in the North Atlantic, but few studies related to quality have been carried out on this species. We studied the levels of external damages on haddock captured with a demersal trawl in the Northeast Atlantic. Further, we investigated to what extent the compulsory sorting grid and diamond mesh codend gear configuration employed in this trawl fishery is responsible for the external damages observed during the capture process. We evaluated external damages on 563 haddock captured over 22 hauls. In general, the results showed that catching haddock without any gear inflicted damages using demersal trawls is challenging. However, the results also showed that the severity of most damages is low and the probability to catch haddock with no external damage can be significantly increased removing the grid and changing codend design. | publishedVersion
Mostrar más [+] Menos [-]Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
External damages are indicators of the overall quality of fish and fish welfare. Haddock is an important commercial species widespread in the North Atlantic, but few studies related to quality have been carried out on this species. We studied the levels of external damages on haddock captured with a demersal trawl in the Northeast Atlantic. Further, we investigated to what extent the compulsory sorting grid and diamond mesh codend gear configuration employed in this trawl fishery is responsible for the external damages observed during the capture process. We evaluated external damages on 563 haddock captured over 22 hauls. In general, the results showed that catching haddock without any gear inflicted damages using demersal trawls is challenging. However, the results also showed that the severity of most damages is low and the probability to catch haddock with no external damage can be significantly increased removing the grid and changing codend design.
Mostrar más [+] Menos [-]Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
External damages are indicators of the overall quality of fish and fish welfare. Haddock is an important commercial species widespread in the North Atlantic, but few studies related to quality have been carried out on this species. We studied the levels of external damages on haddock captured with a demersal trawl in the Northeast Atlantic. Further, we investigated to what extent the compulsory sorting grid and diamond mesh codend gear configuration employed in this trawl fishery is responsible for the external damages observed during the capture process. We evaluated external damages on 563 haddock captured over 22 hauls. In general, the results showed that catching haddock without any gear inflicted damages using demersal trawls is challenging. However, the results also showed that the severity of most damages is low and the probability to catch haddock with no external damage can be significantly increased removing the grid and changing codend design.
Mostrar más [+] Menos [-]Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery Texto completo
2020
Sistiaga, Manu | Herrmann, Bent | Brinkhof, Jesse | Larsen, Roger B. | Jacques, Nadine | Santos, Juan | Gjøsund, Svein Helge
External damages are indicators of the overall quality of fish and fish welfare. Haddock is an important commercial species widespread in the North Atlantic, but few studies related to quality have been carried out on this species. We studied the levels of external damages on haddock captured with a demersal trawl in the Northeast Atlantic. Further, we investigated to what extent the compulsory sorting grid and diamond mesh codend gear configuration employed in this trawl fishery is responsible for the external damages observed during the capture process. We evaluated external damages on 563 haddock captured over 22 hauls. In general, the results showed that catching haddock without any gear inflicted damages using demersal trawls is challenging. However, the results also showed that the severity of most damages is low and the probability to catch haddock with no external damage can be significantly increased removing the grid and changing codend design.
Mostrar más [+] Menos [-]Biodegradation of weathered crude oil in seawater with frazil ice Texto completo
2020
Lofthus, Synnøve | Bakke, Ingrid | Tremblay, Julien | Greer, Charles | Brakstad, Odd Gunnar
Biodegradation of weathered crude oil in seawater with frazil ice Texto completo
2020
Lofthus, Synnøve | Bakke, Ingrid | Tremblay, Julien | Greer, Charles | Brakstad, Odd Gunnar
As ice extent in the Arctic is declining, oil and gas activities will increase, with higher risk of oil spills to the marine environment. To determine biotransformation of dispersed weathered oil in newly formed ice, oil dispersions (2–3 ppm) were incubated in a mixture of natural seawater and frazil ice for 125 days at −2 °C. Dispersed oil in seawater without frazil ice were included in the experimental setup. Presence or absence of frazil ice was a strong driver for microbial community structures and affected the rate of oil degradation. n-alkanes were degraded faster in the presence of frazil ice, the opposite was the case for naphthalenes and 2–3 ring PAHs. No degradation of 4–6 ring PAHs was observed in any of the treatments. The total petroleum oil was not degraded to any significant degree, suggesting that oil will freeze into the ice matrix and persist throughout the icy season. | publishedVersion
Mostrar más [+] Menos [-]Biodegradation of weathered crude oil in seawater with frazil ice Texto completo
2020
Lofthus, Synnøve | Bakke, Ingrid | Tremblay, Julien | Greer, Charles W. | Brakstad, Odd Gunnar
As ice extent in the Arctic is declining, oil and gas activities will increase, with higher risk of oil spills to the marine environment. To determine biotransformation of dispersed weathered oil in newly formed ice, oil dispersions (2–3 ppm) were incubated in a mixture of natural seawater and frazil ice for 125 days at −2 °C. Dispersed oil in seawater without frazil ice were included in the experimental setup. Presence or absence of frazil ice was a strong driver for microbial community structures and affected the rate of oil degradation. n-alkanes were degraded faster in the presence of frazil ice, the opposite was the case for naphthalenes and 2–3 ring PAHs. No degradation of 4–6 ring PAHs was observed in any of the treatments. The total petroleum oil was not degraded to any significant degree, suggesting that oil will freeze into the ice matrix and persist throughout the icy season.
Mostrar más [+] Menos [-]A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants Texto completo
2020
Liber, Yohan | Cornet, Denis | Tournebize, Régis | Feidt, Cyril | Mahieu, Maurice | Laurent, François | Bedell, Jean-Philippe
A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants Texto completo
2020
Liber, Yohan | Cornet, Denis | Tournebize, Régis | Feidt, Cyril | Mahieu, Maurice | Laurent, François | Bedell, Jean-Philippe
Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data.
Mostrar más [+] Menos [-]A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants Texto completo
2020
Liber, Yohan | Cornet, Denis | Tournebize, Régis | Feidt, Cyril | Mahieu, Maurice | Laurent, François | Bedell, Jean-Philippe
Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data. Graphical abstract
Mostrar más [+] Menos [-]A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants Texto completo
2020
Liber, Yohan | Cornet, Denis | Tournebize, Régis | Feidt, Cyril | Mahieu, Maurice | Laurent, Francois | Bedell, Jean-Philippe | Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA) ; Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS) | ToxAlim (ToxAlim) ; Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Ecole Nationale Vétérinaire de Toulouse (ENVT) ; Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Ecole d'Ingénieurs de Purpan (INP - PURPAN) ; Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro ; Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro) | Département Systèmes Biologiques (Cirad-BIOS) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | Agrosystèmes tropicaux (ASTRO) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Unité de Recherches Animal et Fonctionnalités des Produits Animaux (URAFPA) ; Université de Lorraine (UL)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Unité de Recherches Zootechniques (URZ) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | This study was funded by convention DRTT2017-162-68 of the prefectures of Guadeloupe and Martinique in the framework of the Plan Chlordecone III. | ANR-16-CE21-0008,INSSICCA,Stratégies innovantes pour sécuriser les systèmes d'élevage dans les zones contaminées par la chlordécone. Une approche modèle développée dans les Antilles et applicable dans les zones contaminées à l'échelle mondiale(2016)
International audience | Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data.
Mostrar más [+] Menos [-]Interactions of cadmium and zinc in high zinc tolerant native species andropogon gayanus cultivated in hydroponics: growth endpoints, metal bioaccumulation, and ultrastructural Texto completo
2020
Ribeiro, Paula Godinho | Martins, Gabriel Caixeta | Moreira, Cristiano Gonçalves | Oliveira, Cynthia de | Andrade, Maria Luiza de Carvalho | Sales, Thais Silva | Chagas, Wantuir Filipe Teixeira | Labory, Cláudia Regina Gontijo | Carvalho, Teotonio Soares de | Guilherme, Luiz Roberto Guimarães
Cadmium (Cd) and zinc (Zn) toxicity causes physiological disorders and harms plants, interfering with the rehabilitation of areas affected by mining activities. This study evaluated how the exposure to Zn and/or Cd affects the growth of native andropogon grass (Andropogon gayanus Kunth) plants originally found in areas contaminated with Cd and/or Zn due to zinc mining activities. Plants were cultivated for 7 weeks in a nutrient solution treated with Zn (142.3–854.0 μM) or Cd (0.9–13.3 μM) separately or combined with a molar ratio of 64:1 (Zn:Cd). A control treatment was grown in a complete Hoagland and Arnon solution (without Cd). Plant height, stem diameter, internode length, dry weight, Cd and Zn concentration, and accumulation in shoots/roots, as well as ultrastructure of roots and leaves were analyzed at the end of the experiment. The root dry weight was not significantly affected by the addition of the metals. Moreover, Zn provided higher shoot dry weight (up to 160%) relative to control. Andropogon grass tolerated both metals better separately than when applied together. Transmission electron microscopy analyses showed modifications such as vesiculation and vacuolation in the ultrastructure of andropogon tissues by Cd and/or Zn. The andropogon grass was tolerant to the doses tested, evidencing that it has potential for recovering areas contaminated with Zn and/or Cd.
Mostrar más [+] Menos [-]Biocontrol potential of methyl chavicol for managing Spodoptera frugiperda (Lepidoptera: Noctuidae), an important corn pest Texto completo
2020
Menezes, Claubert Wagner Guimarães de | Carvalho, Geraldo Andrade | Alves, Dejane Santos | Carvalho, Alexandre Alves de | Aazza, Smail | Ramos, Vinicius de Oliveira | Pinto, José Eduardo Brasil Pereira | Bertolucci, Suzan Kelly Vilela
Synthetic insecticides applied to control Spodoptera frugiperda (Lepidoptera: Noctuidae) can have negative impacts on environment and human health. Botanical essential oils can be sources of organic molecules with biocontrol potential and advantages, such as minor impacts on the selection of resistant pest insects and low toxicity to humans. The aim of this study was to investigate the biocontrol action of essential oils from Brazilian species and methyl chavicol compounds on the development and metabolism of S. frugiperda. Essential oils of Eremanthus erythropappus (Asteraceae), Ocimum selloi, Hyptis suaveolens, and Hyptis marrubioides (Lamiaceae) were distilled by the steam distillation method and analyzed by gas chromatograph techniques. The essential oils were incorporated into an artificial diet (at 1, 2, and 4 mg mL−1) and offered to S. frugiperda caterpillars. Larvae of S. frugiperda at 48 h of age were fed an artificial diet containing the major constituent of O. selloi (methyl chavicol). The major compounds of the essential oils were methyl chavicol for O. selloi, α-bisabolol for E. erythropappus, bicyclogermacrene for H. suaveolens, and β-thujone for H. marrubioides. O. selloi caused 100% mortality in S. frugiperda larvae at a concentration of 1 mg mL−1 after 48 h. H. marrubioides essential oil caused 100% mortality in larvae at a concentration of 4 mg mL−1 after 48 h. O. selloi and H. marrubioides inhibited acetylcholinesterase (AchE) activity in 72.87% and 81.69% of larvae, respectively. O. selloi presented the highest toxicity to S. frugiperda and the lowest inhibition of AchE. Methyl chavicol was lethal to all larvae within 24 h at a concentration of 0.92 mg mL−1 of diet. Methyl chavicol showed the best insecticidal activity and potential to be used as a natural insecticide to control S. frugiperda.
Mostrar más [+] Menos [-]Physical limitation of pesticides (chlordecone) decontamination in volcanic soils: Fractal approach and numerical simulation Texto completo
2020
Woignier, Thierry | Rangon, Luc | Clostre, Florence | Mottes, Charles | Cattan, Philippe | Primera, Philippe | Jannoyer, Magalie
Physical limitation of pesticides (chlordecone) decontamination in volcanic soils: Fractal approach and numerical simulation Texto completo
2020
Woignier, Thierry | Rangon, Luc | Clostre, Florence | Mottes, Charles | Cattan, Philippe | Primera, Philippe | Jannoyer, Magalie
In the French West Indies, the chlordecone (organochloride pesticide) pollution is now diffuse becoming new contamination source for crops and environment (water, trophic chain). Decontamination by bioremediation and chemical degradation are still under development but the physical limitations of these approaches are generally not taken into account. These physical limitations are related to the poor physical accessibility to the pesticides in soils because of the peculiar structural properties of the contaminated clays (pore volume, transport properties, permeability, and diffusion). Some volcanic soils (andosols), which represent the half of the contaminated soils in Martinique, contain nanoclay (allophane) with a unique structure and porous properties. Andosols are characterized by pore size distribution in the mesoporous range, a high specific surface area, a large pore volume, and a fractal structure. Our hypothesis is that the clay microstructure characteristics are crucial physico-chemical factors strongly limiting the remediation of the pesticide. Our results show that allophane microstructure (small pore size, hierarchical microstructure, and tortuosity) favors accumulation of chlordecone, in andosols. Moreover, the clay microporosity limits the accessibility of microorganisms and chemical species able to decontaminate because of poor transport properties (permeability and diffusion). We model the transport properties by two approaches: (1) we use a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster–cluster aggregation model. From the simulated data, we derived the pore volume, specific surface area, tortuosity, permeability, and diffusion. We show that transport properties strongly decrease because of the presence of allophane. (2) The fractal approach. We characterize the fractal features (size of the fractal aggregate, fractal dimension, tortuosity inside allophane aggregates) and we calculate that transport properties decrease of several order ranges inside the clay aggregates. These poor transport properties are important parameters to explain the poor accessibility to pollutants in volcanic soils and should be taken into account by future decontamination process. We conclude that for andosols, this inaccessibility could render inefficient some of the methods proposed in the literature.
Mostrar más [+] Menos [-]Physical limitation of pesticides (chlordecone) decontamination in volcanic soils: fractal approach and numerical simulation Texto completo
2020
Woignier, Thierry | Rangon, Luc | Clostre, Florence | Mottes, Charles | Cattan, Philippe | Primera, Juan | Jannoyer, Magalie
In the French West Indies, the chlordecone (organochloride pesticide) pollution is now diffuse becoming new contamination source for crops and environment (water, trophic chain). Decontamination by bioremediation and chemical degradation are still under development but the physical limitations of these approaches are generally not taken into account. These physical limitations are related to the poor physical accessibility to the pesticides in soils because of the peculiar structural properties of the contaminated clays (pore volume, transport properties, permeability, and diffusion). Some volcanic soils (andosols), which represent the half of the contaminated soils in Martinique, contain nanoclay (allophane) with a unique structure and porous properties. Andosols are characterized by pore size distribution in the mesoporous range, a high specific surface area, a large pore volume, and a fractal structure. Our hypothesis is that the clay microstructure characteristics are crucial physico-chemical factors strongly limiting the remediation of the pesticide. Our results show that allophane microstructure (small pore size, hierarchical microstructure, and tortuosity) favors accumulation of chlordecone, in andosols. Moreover, the clay microporosity limits the accessibility of microorganisms and chemical species able to decontaminate because of poor transport properties (permeability and diffusion). We model the transport properties by two approaches: (1) we use a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster–cluster aggregation model. From the simulated data, we derived the pore volume, specific surface area, tortuosity, permeability, and diffusion. We show that transport properties strongly decrease because of the presence of allophane. (2) The fractal approach. We characterize the fractal features (size of the fractal aggregate, fractal dimension, tortuosity inside allophane aggregates) and we calculate that transport properties decrease of several order ranges inside the clay aggregates. These poor transport properties are important parameters to explain the poor accessibility to pollutants in volcanic soils and should be taken into account by future decontamination process. We conclude that for andosols, this inaccessibility could render inefficient some of the methods proposed in the literature.
Mostrar más [+] Menos [-]Size-dependent escape risk of lumpfish (Cyclopterus lumpus) from salmonid farm nets Texto completo
2020
Herrmann, Bent | Sistiaga, Manu | Jørgensen, Terje
In the last decade, the salmon aquaculture industry has considerably increased the use of lumpfish juveniles as cleaner fish. Potential escape of reared lumpfish into the wild may spread diseases or genetically contaminate wild stocks. The guidelines for minimum sizes of cleaner fish to use in aquaculture cages are currently based on simple mesh penetration tests. However, these guidelines do not consider the potential compressibility of fish or changes in mesh state due to factors such as sea conditions and maintenance operations. This study shows that the industry-recommended minimum stocking sizes for a given mesh size may result in escape risk and that ignoring fish compressibility and mesh state can lead to underestimation of the lumpfish sizes that are able to escape. Our results can be used to develop new guidelines that will contribute to reduced escape of lumpfish from salmonid farms and lessen the potential environmental consequences. | acceptedVersion
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