The Experts below are selected from a list of 25554 Experts worldwide ranked by ideXlab platform
Finlo Cottier - One of the best experts on this subject based on the ideXlab platform.
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moonlight drives ocean scale mass Vertical Migration of zooplankton during the arctic winter
Current Biology, 2016Co-Authors: Laura Hobbs, Jørgen Berge, Andrew S Brierley, Finlo CottierAbstract:In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological Migration have historically been considered non-existent [1]. However, diel Vertical Migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as yet, unexplained. Here, we present evidence of an unexpected uniform behavior across the entire Arctic, in fjord, shelf, slope and open sea, where Vertical Migrations of zooplankton are driven by lunar illumination. A shift from solar-day (24-hr period) to lunar-day (24.8-hr period) Vertical Migration takes place in winter when the moon rises above the horizon. Further, mass sinking of zooplankton from the surface waters and accumulation at a depth of ∼50 m occurs every 29.5 days in winter, coincident with the periods of full moon. Moonlight may enable predation of zooplankton by carnivorous zooplankters, fish, and birds now known to feed during the polar night [4]. Although primary production is almost nil at this time, lunar Vertical Migration (LVM) may facilitate monthly pulses of carbon remineralization, as they occur continuously in illuminated mesopelagic systems [5], due to community respiration of carnivorous and detritivorous zooplankton. The extent of LVM during the winter suggests that the behavior is highly conserved and adaptive and therefore needs to be considered as "baseline" zooplankton activity in a changing Arctic ocean [6-9]. VIDEO ABSTRACT.
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Arctic complexity: A case study on diel Vertical Migration of zooplankton
Journal of Plankton Research, 2014Co-Authors: Jørgen Berge, Finlo Cottier, Sawomir Kwasniewski, Colin Griffiths, Janne E. SØreide, Geir Johnsen, Øystein Varpe, Paul E Renaud, Stig Falk-petersen, Anaïs AubertAbstract:Diel Vertical Migration (DVM) of zooplankton is a global phenomenon, characteristic of both marine and limnic environments. At high latitudes, patterns of DVM have been documented, but rather little knowledge exists regarding which species perform this ecologically important behaviour. Also, in the Arctic, the Vertically migrating components of the zooplankton community are usually regarded as a single sound scattering layer (SSL) performing synchronized patterns of Migration directly controlled by ambient light. Here, we present evidence for hitherto unknown complexity of Arctic marine systems, where zooplankton form multiple aggregations through the water column seen via acoustics as distinct SSLs. We show that while the initiation of DVM during the autumnal equinox is light mediated, the Vertical positioning of the migrants during day is linked more to the thermal characteristics of water masses than to irradiance. During night, phytoplankton biomass is shown to be the most important factor determining the Vertical positioning of all migrating taxa. Further, we develop a novel way of representing acoustic data in the form of a Sound Image (SI) that enables a direct comparison of the relative importance of each potential scatterer based upon the theoretical contribution of their backscatter. Based on our comparison of locations with contrasting hydrography, we conclude that a continued warming of the Arctic is likely to result in more complex ecotones across the Arctic marine system.
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diel Vertical Migration of arctic zooplankton during the polar night
Biology Letters, 2009Co-Authors: Jørgen Berge, Finlo Cottier, Janne E. SØreide, Øystein Varpe, Stig Falkpetersen, Eva Leu, Ketil Eiane, Kate J Willis, Henrik Nygard, Daniel VogedesAbstract:High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel Vertical Migration (DVM) of zooplankton. DVM constitutes the largest synchronized movement of biomass on the planet, and is of paramount importance for marine ecosystem function and carbon cycling. Here we present acoustic data that demonstrate a synchronized DVM behaviour of zooplankton that continues throughout the Arctic winter, in both open and ice-covered waters. We argue that even during the polar night, DVM is regulated by diel variations in solar and lunar illumination, which are at intensities far below the threshold of human perception. We also demonstrate that winter DVM is stronger in open waters compared with ice-covered waters. This suggests that the biologically mediated Vertical flux of carbon will increase if there is a continued retreat of the Arctic winter sea ice cover.
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unsynchronised and synchronised Vertical Migration of zooplankton in a high arctic fjord
Limnology and Oceanography, 2006Co-Authors: Finlo Cottier, Geraint A. Tarling, Anette Wold, Stig FalkpetersenAbstract:We measured Vertical Migration of zooplankton in an arctic fjord at 79uN between June and September 2002 and transcending a period of continuous illumination to one of true day and night to investigate the changing influence of light cues on behavior. Observations made with a moored 300 kHz acoustic Doppler current profiler indicated that two modes of Vertical Migration occurred during the study period. During the weeks of continuous illumination, backscatter data indicated that there was no net Vertical displacement of the population at any time during the 24-h period, but Vertical velocity showed a continuous net downward movement in the surface layers and a net upward movement at depth. We interpreted this as unsynchronized Vertical Migrations by individuals with upward trajectories that slowed closer to the surface and downward trajectories that were most rapid in their initial phases. Synchronized Migrations, seen as an upward and downward movement of scattering layers at dusk and dawn respectively, began once true nighttime resumed toward autumn. It is likely that the relative rate of change in light was used as the proximal cue for synchronized Migrations. Concurrent net samples identified Calanus finmarchicus and C. glacialis as the most likely contributors to the unsynchronized Migration patterns. The high backscatter of the synchronized scattering layers suggests that they included additional taxa such as the euphausiid Thysanoessa spp., the pteropod Limacina helicina, or the hyperiid amphipod Themisto spp.
Thomas M Missimer - One of the best experts on this subject based on the ideXlab platform.
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Vertical Migration of municipal wastewater in deep injection well systems, South Florida, USA
Hydrogeology Journal, 2007Co-Authors: Robert G Maliva, Thomas M MissimerAbstract:Deep well injection is widely used in South Florida, USA for wastewater disposal largely because of the presence of an injection zone (“boulder zone” of Floridan Aquifer System) that is capable of accepting very large quantities of fluids, in some wells over 75,000 m^3/day. The greatest potential risk to public health associated with deep injection wells in South Florida is Vertical Migration of wastewater, containing pathogenic microorganisms and pollutants, into brackish-water aquifer zones that are being used for alternative water-supply projects such as aquifer storage and recovery. Upwards Migration of municipal wastewater has occurred in a minority of South Florida injection systems. The results of solute-transport modeling using the SEAWAT program indicate that the measured Vertical hydraulic conductivities of the rock matrix would allow for only minimal Vertical Migration. Fracturing at some sites increased the equivalent average Vertical hydraulic conductivity of confining zone strata by approximately four orders of magnitude and allowed for Vertical Migration rates of up 80 m/year. Even where Vertical Migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms. Les injections par puits profonds sont largement utilisées au sud de la Floride (Etats-Unis) pour stocker les eaux usées, essentiellement du fait de la présence d’une zone d’injection ("zone des blocs" du Système Aquifère de Floride) apte à accepter des quantités considérables de fluides : plus de 75,000 m^3/jour dans certains puits. Le plus grand risque potentiel associé à ces puits vis-à-vis de la santé publique est la Migration Verticale des eaux usées, qui contiennent des microorganismes pathogènes et des polluants, vers les zones aquifères d’eau saumâtre qui sont utilisées pour les projets alternatifs d’alimentation en eau, comme le stockage en aquifère et la reprise de pression. Des Migrations ascendantes d’eaux usées municipales ont été observées dans une minorité de systèmes d’injection du sud de la Floride. Les résultats de la modélisation du transport de solutés sous le programme SEAWAT indiquent que les perméabilités mesurées de la matrice rocheuse ne permettraient qu’une Migration Verticale minime. Sur certains sites, la fracturation a multiplié la perméabilité Verticale équivalente moyenne de la zone de confinement par quatre, permettant des vitesses de Migration Verticale de l’ordre de 80 m/an. Même aux endroits où la Migration Verticale a été rapide, les temps de transits théoriques sont susceptibles d’être suffisamment longs pour permettre l’inactivation des microorganismes pathogènes. La inyección de pozos profundos se usa ampliamente en el sur de Florida, Estados Unidos de América, para la eliminación de aguas residuales principalmente debido a la presencia de una zona de inyección (“zona de cantos rodados” del Sistema Acuífero Floridano) la cual es capaz de aceptar cantidades muy grandes de fluidos, en algunos pozos hasta 75,000 m^3/dia. El riesgo potencial más grande para la salud pública asociado con pozos de inyección profundos en el sur de Florida es la migración Vertical de agua residual, que contiene contaminantes y microorganismos patógenos, hacia zonas de acuífero de agua salobre que son usados en proyectos alternativos de abastecimiento de agua, tal como recuperación y almacenamiento de acuífero. Se ha registrado migración ascendente de agua residual municipal en una minoría de sistemas de inyección del sur de Florida. Los resultados del modelo de transporte de solutos usando el programa SEAWAT indican que las conductividades hidráulicas Verticales medidas en la matriz de la roca permitirían únicamente migración Vertical mínima. El fracturamiento en algunos sitios incrementa la conductividad hidráulica Vertical promedio equivalente de una zona de estratos confinantes en aproximadamente cuatro órdenes de magnitud y permitió tasas de migración Vertical de hasta 80 m/año. Aún cuando la migración Vertical fue rápida los tiempos de tránsito documentados probablemente son lo suficientemente largos para la desactivación de microorganismos patógenos.
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Vertical Migration of municipal wastewater in deep injection well systems south florida usa
Hydrogeology Journal, 2007Co-Authors: Robert G Maliva, Weixing Guo, Thomas M MissimerAbstract:Deep well injection is widely used in South Florida, USA for wastewater disposal largely because of the presence of an injection zone ("boulder zone" of Floridan Aquifer System) that is capable of accepting very large quantities of fluids, in some wells over 75,000m 3 / day. The greatest potential risk to public health associated with deep injection wells in South Florida is Vertical Migration of wastewater, containing pathogenic micro- organisms and pollutants, into brackish-water aquifer zones that are being used for alternative water-supply projects such as aquifer storage and recovery. Upwards Migration of municipal wastewater has occurred in a minority of South Florida injection systems. The results of solute-transport modeling using the SEAWAT program indicate that the measured Vertical hydraulic conductivi- ties of the rock matrix would allow for only minimal Vertical Migration. Fracturing at some sites increased the equivalent average Vertical hydraulic conductivity of confining zone strata by approximately four orders of magnitude and allowed for Vertical Migration rates of up 80m/year. Even where Vertical Migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms. Resume Les injections par puits profonds sont largement utilisees au sud de la Floride (Etats-Unis) pour stocker les eaux usees, essentiellement du fait de la presence d'une zone d'injection ("zone des blocs" du Systeme Aquifere de Floride) apte a accepter des quantites considerables de fluides : plus de 75,000m 3 /jour dans certains puits. Le plus
Jørgen Berge - One of the best experts on this subject based on the ideXlab platform.
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moonlight drives ocean scale mass Vertical Migration of zooplankton during the arctic winter
Current Biology, 2016Co-Authors: Laura Hobbs, Jørgen Berge, Andrew S Brierley, Finlo CottierAbstract:In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological Migration have historically been considered non-existent [1]. However, diel Vertical Migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as yet, unexplained. Here, we present evidence of an unexpected uniform behavior across the entire Arctic, in fjord, shelf, slope and open sea, where Vertical Migrations of zooplankton are driven by lunar illumination. A shift from solar-day (24-hr period) to lunar-day (24.8-hr period) Vertical Migration takes place in winter when the moon rises above the horizon. Further, mass sinking of zooplankton from the surface waters and accumulation at a depth of ∼50 m occurs every 29.5 days in winter, coincident with the periods of full moon. Moonlight may enable predation of zooplankton by carnivorous zooplankters, fish, and birds now known to feed during the polar night [4]. Although primary production is almost nil at this time, lunar Vertical Migration (LVM) may facilitate monthly pulses of carbon remineralization, as they occur continuously in illuminated mesopelagic systems [5], due to community respiration of carnivorous and detritivorous zooplankton. The extent of LVM during the winter suggests that the behavior is highly conserved and adaptive and therefore needs to be considered as "baseline" zooplankton activity in a changing Arctic ocean [6-9]. VIDEO ABSTRACT.
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Arctic complexity: A case study on diel Vertical Migration of zooplankton
Journal of Plankton Research, 2014Co-Authors: Jørgen Berge, Finlo Cottier, Sawomir Kwasniewski, Colin Griffiths, Janne E. SØreide, Geir Johnsen, Øystein Varpe, Paul E Renaud, Stig Falk-petersen, Anaïs AubertAbstract:Diel Vertical Migration (DVM) of zooplankton is a global phenomenon, characteristic of both marine and limnic environments. At high latitudes, patterns of DVM have been documented, but rather little knowledge exists regarding which species perform this ecologically important behaviour. Also, in the Arctic, the Vertically migrating components of the zooplankton community are usually regarded as a single sound scattering layer (SSL) performing synchronized patterns of Migration directly controlled by ambient light. Here, we present evidence for hitherto unknown complexity of Arctic marine systems, where zooplankton form multiple aggregations through the water column seen via acoustics as distinct SSLs. We show that while the initiation of DVM during the autumnal equinox is light mediated, the Vertical positioning of the migrants during day is linked more to the thermal characteristics of water masses than to irradiance. During night, phytoplankton biomass is shown to be the most important factor determining the Vertical positioning of all migrating taxa. Further, we develop a novel way of representing acoustic data in the form of a Sound Image (SI) that enables a direct comparison of the relative importance of each potential scatterer based upon the theoretical contribution of their backscatter. Based on our comparison of locations with contrasting hydrography, we conclude that a continued warming of the Arctic is likely to result in more complex ecotones across the Arctic marine system.
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diel Vertical Migration of arctic zooplankton during the polar night
Biology Letters, 2009Co-Authors: Jørgen Berge, Finlo Cottier, Janne E. SØreide, Øystein Varpe, Stig Falkpetersen, Eva Leu, Ketil Eiane, Kate J Willis, Henrik Nygard, Daniel VogedesAbstract:High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel Vertical Migration (DVM) of zooplankton. DVM constitutes the largest synchronized movement of biomass on the planet, and is of paramount importance for marine ecosystem function and carbon cycling. Here we present acoustic data that demonstrate a synchronized DVM behaviour of zooplankton that continues throughout the Arctic winter, in both open and ice-covered waters. We argue that even during the polar night, DVM is regulated by diel variations in solar and lunar illumination, which are at intensities far below the threshold of human perception. We also demonstrate that winter DVM is stronger in open waters compared with ice-covered waters. This suggests that the biologically mediated Vertical flux of carbon will increase if there is a continued retreat of the Arctic winter sea ice cover.
Richard B. Forward - One of the best experts on this subject based on the ideXlab platform.
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proximate control of diel Vertical Migration in phyllosoma larvae of the caribbean spiny lobster panulirus argus
The Biological Bulletin, 2010Co-Authors: Tracy A Ziegler, Jonathan H. Cohen, Richard B. ForwardAbstract:Phyllosoma larvae of the spiny lobster Panu- lirus argus undergo diel Vertical Migration (DVM), in which they are at depth during the day and nearer the surface at night. This study determined the visual spectral sensitivity of Stage I larvae and investigated whether light plays a proximate role in DVM as an exogenous cue and as an entrainment cue for an endogenous rhythm in Vertical Migration. Under constant conditions, larvae have a circa- dian rhythm (24.5-h period) in Vertical swimming that re- sulted in a twilight DVM pattern. The behavioral response spectrum and electroretinogram recording indicated two photoreceptor spectral classes with maxima at 360 and 486 nm. When stimulated in an apparatus that simulated the underwater angular light distribution, dark-adapted larvae showed only positive phototaxis, with a threshold intensity of 1.8 10 13 photons m -2 s -1 (3.0 10 -5 moles photons m -2 s -1 ). They have an avoidance response to predator shadows in which they descend upon sudden decreases in light intensity of more than 69%. When stimulated with relative rates of decrease in light intensity as occur at sunset they ascended, whereas they descended upon relative rates of light intensity increase as occur at sunrise. Thus, the DVM pattern is controlled by both an endogenous circadian rhythm in swimming and behavioral responses to light at sunrise and sunset.
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zooplankton diel Vertical Migration a review of proximate control
Oceanography and Marine Biology, 2009Co-Authors: Jonathan H. Cohen, Richard B. ForwardAbstract:Diel Vertical Migration (DVM) is a characteristic behavioural pattern performed by zooplankton in which their Vertical distribution changes over the 24-h day. Here the proximate control of zooplankton DVM is reviewed. Light has emerged as the major proximate cue controlling DVM behaviour and the understanding of zooplankton visual physiology and the light-mediated behaviour underlying DVM is expanding. Field and laboratory evidence exist to support each of the three major hypotheses for the exogenous role of light in DVM: (1) preferendum or isolume, (2) absolute intensity threshold, and (3) relative rate of change. Light may also play an endogenous role in DVM by entraining circadian rhythms in Vertical movement or activity. This appreciation of the role of light has improved modelling efforts into the causes and consequences of DVM. The most important recent advance in the study of DVM is the recognition that this behaviour is a phenotypic response in many species and is most commonly activated by chemical cues (kairomones) from fish predators. High levels of kairomones signal high levels of predation pressure, and DVM-related photobehaviours, such as swimming responses on relative rates of irradiance change, are altered such that Migration occurs and zooplankton achieve a refuge from visual predators.
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the ontogeny of the endogenous rhythm in Vertical Migration of the blue crab callinectes sapidus at metamorphosis
Journal of Experimental Marine Biology and Ecology, 2007Co-Authors: Richard B. Forward, Humberto Diaz, Matthew B OgburnAbstract:Postlarvae or megalopae of the blue crab Callinectes sapidus are transported from offshore areas into estuaries where they settle and metamorphose in areas of submerged vegetation. Separate previous studies found that both intermolt megalopae and juvenile crabs have circadian rhythms in Vertical Migration with different phasing. Intermolt megalopae Vertically migrate during the day phase of the entrainment cycle whereas juvenile crabs Vertically migrate during the night phase. The present study considered (1) whether the switch in Vertical Migration activity from the day to night phase at metamorphosis occurred in individual animals and (2) whether the rhythm continued after metamorphosis without re-entrainment to the light:dark cycle and (3) whether exposure to offshore or estuarine water affected the rhythm. Vertical Migration of individual animals was monitored under constant conditions with a video system. Re-entrainment was not necessary because the circadian rhythm in individual animals continued and the switch in phase occurred when C. sapidus was held under constant condition from the intermolt megalopa stage through metamorphosis to the first crab stage. Offshore and estuarine waters only affected the phasing of the rhythm around the time of metamorphosis but did not affect the ontogeny of the rhythm. The continuation of the rhythm and change in phase at metamorphosis contribute to horizontal transport in estuaries.
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Diel Vertical Migration of the marine copepod Calanopia americana. II. Proximate role of exogenous light cues and endogenous rhythms
Marine Biology, 2005Co-Authors: Jonathan H. Cohen, Richard B. ForwardAbstract:The marine copepod Calanopia americana Dahl undergoes twilight diel Vertical Migration (DVM) in the Newport River estuary, North Carolina, USA, in synchrony with the light:dark cycle. Copepods ascend to the surface at sunset, descend to the bottom around midnight, and make a second ascent and descent before sunrise. Behavioral assays with C. americana in the laboratory during fall 2002/2003 and summer 2004 investigated aspects of three hypotheses for the proximate role of light in DVM: (1) preferendum hypothesis (absolute irradiance), (2) rate of change hypothesis (relative rates of irradiance change), and (3) endogenous rhythm hypothesis. Results suggest that C. americana responds to exogenous light cues consistent with its DVM pattern; changes in absolute irradiance evoked swimming responses that would result in an ascent at sunset and descent at sunrise, while relative rates of irradiance decrease at sunset (−0.0046 s−1) evoked an ascent response, and relative rates of irradiance increase at sunrise (0.0042 s−1) evoked a descent response. Furthermore, C. americana expressed an endogenous rhythm in Vertical Migration that was positively correlated with field observations of twilight DVM. Collectively, these results indicate that both exogenous light cues and endogenous rhythms play a proximate role in twilight DVM of C. americana, providing redundancy in the causes of its Vertical Migration.
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endogenous swimming rhythms of larval atlantic menhaden brevoortia tyrannus latrobe implications for Vertical Migration
Journal of Experimental Marine Biology and Ecology, 1996Co-Authors: Richard B. Forward, Richard A Tankersley, John S BurkeAbstract:Atlantic menhaden, Brevoortia tyrannus Latrobe, spawn on the continental shelf. Larvae are transported shoreward where they enter estuaries and metamorphose. Field studies suggest that while offshore, larvae may undergo nocturnal diel Vertical Migration (DVM), in which they are near the surface during the night and at depth during the day. The DVM pattern is more pronounced in estuaries but the timing of the nocturnal ascent may be related to tides. Larvae appear to swim in the water column during nocturnal rising tide and are less abundant at all other times. This Migration pattern would result in up-estuary movement by selective tidal stream transport. The present study measured endogenous swimming rhythms of Atlantic menhaden larvae and related them to possible Vertical Migration patterns in offshore and estuarine areas. Larvae reared in the laboratory on a diel light:dark cycle were measured at three sizes (7–9 mm, 14–17 mm and 23–27 mm total length [TL]) as representative of larvae in offshore areas, while estuarine larvae (25–30 mm TL) were collected in the Newport River Estuary (N.C.). Swimming was monitored in a column under constant conditions in the laboratory with a time-lapse video system. In all cases, larvae had a similar circadian rhythm. The smallest laboratory reared larvae ascended into the upper portion of the column during the time of night and descended during the time of day. The other laboratory reared and field caught larvae had increased swimming activity during the time of night and reduced activity during the time of day. This circadian activity rhythm would contribute to the nocturnal DVM in offshore and estuarine areas. However, there was no evidence that larvae developed a tidal rhythm in activity that could contribute to selective tidal stream transport in estuaries.
Robert G Maliva - One of the best experts on this subject based on the ideXlab platform.
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Vertical Migration of municipal wastewater in deep injection well systems, South Florida, USA
Hydrogeology Journal, 2007Co-Authors: Robert G Maliva, Thomas M MissimerAbstract:Deep well injection is widely used in South Florida, USA for wastewater disposal largely because of the presence of an injection zone (“boulder zone” of Floridan Aquifer System) that is capable of accepting very large quantities of fluids, in some wells over 75,000 m^3/day. The greatest potential risk to public health associated with deep injection wells in South Florida is Vertical Migration of wastewater, containing pathogenic microorganisms and pollutants, into brackish-water aquifer zones that are being used for alternative water-supply projects such as aquifer storage and recovery. Upwards Migration of municipal wastewater has occurred in a minority of South Florida injection systems. The results of solute-transport modeling using the SEAWAT program indicate that the measured Vertical hydraulic conductivities of the rock matrix would allow for only minimal Vertical Migration. Fracturing at some sites increased the equivalent average Vertical hydraulic conductivity of confining zone strata by approximately four orders of magnitude and allowed for Vertical Migration rates of up 80 m/year. Even where Vertical Migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms. Les injections par puits profonds sont largement utilisées au sud de la Floride (Etats-Unis) pour stocker les eaux usées, essentiellement du fait de la présence d’une zone d’injection ("zone des blocs" du Système Aquifère de Floride) apte à accepter des quantités considérables de fluides : plus de 75,000 m^3/jour dans certains puits. Le plus grand risque potentiel associé à ces puits vis-à-vis de la santé publique est la Migration Verticale des eaux usées, qui contiennent des microorganismes pathogènes et des polluants, vers les zones aquifères d’eau saumâtre qui sont utilisées pour les projets alternatifs d’alimentation en eau, comme le stockage en aquifère et la reprise de pression. Des Migrations ascendantes d’eaux usées municipales ont été observées dans une minorité de systèmes d’injection du sud de la Floride. Les résultats de la modélisation du transport de solutés sous le programme SEAWAT indiquent que les perméabilités mesurées de la matrice rocheuse ne permettraient qu’une Migration Verticale minime. Sur certains sites, la fracturation a multiplié la perméabilité Verticale équivalente moyenne de la zone de confinement par quatre, permettant des vitesses de Migration Verticale de l’ordre de 80 m/an. Même aux endroits où la Migration Verticale a été rapide, les temps de transits théoriques sont susceptibles d’être suffisamment longs pour permettre l’inactivation des microorganismes pathogènes. La inyección de pozos profundos se usa ampliamente en el sur de Florida, Estados Unidos de América, para la eliminación de aguas residuales principalmente debido a la presencia de una zona de inyección (“zona de cantos rodados” del Sistema Acuífero Floridano) la cual es capaz de aceptar cantidades muy grandes de fluidos, en algunos pozos hasta 75,000 m^3/dia. El riesgo potencial más grande para la salud pública asociado con pozos de inyección profundos en el sur de Florida es la migración Vertical de agua residual, que contiene contaminantes y microorganismos patógenos, hacia zonas de acuífero de agua salobre que son usados en proyectos alternativos de abastecimiento de agua, tal como recuperación y almacenamiento de acuífero. Se ha registrado migración ascendente de agua residual municipal en una minoría de sistemas de inyección del sur de Florida. Los resultados del modelo de transporte de solutos usando el programa SEAWAT indican que las conductividades hidráulicas Verticales medidas en la matriz de la roca permitirían únicamente migración Vertical mínima. El fracturamiento en algunos sitios incrementa la conductividad hidráulica Vertical promedio equivalente de una zona de estratos confinantes en aproximadamente cuatro órdenes de magnitud y permitió tasas de migración Vertical de hasta 80 m/año. Aún cuando la migración Vertical fue rápida los tiempos de tránsito documentados probablemente son lo suficientemente largos para la desactivación de microorganismos patógenos.
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Vertical Migration of municipal wastewater in deep injection well systems south florida usa
Hydrogeology Journal, 2007Co-Authors: Robert G Maliva, Weixing Guo, Thomas M MissimerAbstract:Deep well injection is widely used in South Florida, USA for wastewater disposal largely because of the presence of an injection zone ("boulder zone" of Floridan Aquifer System) that is capable of accepting very large quantities of fluids, in some wells over 75,000m 3 / day. The greatest potential risk to public health associated with deep injection wells in South Florida is Vertical Migration of wastewater, containing pathogenic micro- organisms and pollutants, into brackish-water aquifer zones that are being used for alternative water-supply projects such as aquifer storage and recovery. Upwards Migration of municipal wastewater has occurred in a minority of South Florida injection systems. The results of solute-transport modeling using the SEAWAT program indicate that the measured Vertical hydraulic conductivi- ties of the rock matrix would allow for only minimal Vertical Migration. Fracturing at some sites increased the equivalent average Vertical hydraulic conductivity of confining zone strata by approximately four orders of magnitude and allowed for Vertical Migration rates of up 80m/year. Even where Vertical Migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms. Resume Les injections par puits profonds sont largement utilisees au sud de la Floride (Etats-Unis) pour stocker les eaux usees, essentiellement du fait de la presence d'une zone d'injection ("zone des blocs" du Systeme Aquifere de Floride) apte a accepter des quantites considerables de fluides : plus de 75,000m 3 /jour dans certains puits. Le plus
