Following the earthquake (ML=6.0) of 24 August 2016 that affected large part of the central Apennine between the municipalities of Norcia (PG) and Amatrice (RI) (central Italy), two soil gas profiles ...(i.e., 222Rn, 220Rn, CO2 and CO2 flux) were carried out across buried and exposed coseismic fault rupture of the Mt. Vettore fault during the seismic sequence. The objective of the survey was to explore the mechanisms of migration and the spatial behaviour of different gas species near still-degassing active fault. Results provide higher gas and CO2 flux values (about twice for 222Rn and CO2 flux) in correspondence of the buried sector of the fault than those measured across the exposed coseismic rupture. Anomalous peaks due to advective migration are clearly visible on both side of the buried fault (profile 1), whereas the lower soil gas concentrations measured across the exposed coseimic rupture (profile 2) are mainly caused by shallow and still acting diffusive degassing associated to faulting during the seismic sequence. These results confirm the usefulness of the soil gas survey to spatially recognise the shallow geometry of hidden faults, and to discriminate the geochemical migration mechanisms occurring at buried and exposed faults related to seismic activity.
The monitoring of the integrity of onshore geological carbon capture and storage projects will require an approach that integrates various methods with different spatial and temporal resolutions. One ...method proven to be quite effective for site assessment, leakage monitoring, and leakage verification is near-surface gas geochemistry, which includes soil gas concentration and gas flux measurements. Anomalous concentrations or fluxes, relative to the natural background values, can indicate the potential occurrence of a leak. However the natural background can be quite variable, especially for CO2, due to biological production and accumulation in the soil that changes as a function of soil type, land use, geology, temperature, water content, and various other parameters. To better understand how these parameters influence natural, near-surface background values, and to examine the potential of different sampling strategies as a function of the survey goals, this paper reports results from two highly different case studies, one from northern Europe (Voulund, Denmark) and one from southern Europe (Sulcis, Sardinia, Italy). The small Voulund site, with its homogeneous soil, climate, and topography, was surveyed twice (in fall and in spring) within the EU-funded SiteChar project to examine the effects of different land use practices and seasons on baseline values. Forested land was found to have lower CO2 concentrations during both campaigns compared to cultivated and heath land, and higher CH4 values during the spring sampling campaign. Continuous monitoring probes showed much more detail, highlighting seasonal changes in soil gas CO2 concentrations linked primarily to temperature variations. The much larger Sulcis site, studied within an ENEA-funded project on potential CO2-ECBM (Enhanced Coal Bed Methane) deployment, was surveyed at the regional scale and on detailed grids and transects for site assessment purposes. Despite the completely different soil and climate conditions, the statistical distribution of the Sulcis data was similar to that of Voulund. Much higher soil gas CO2 anomalies were found at this site, however, due to the less permeable sediments (i.e., better water retention and greater gas accumulation) and the warmer temperatures. Detailed surveys at this site highlighted various significant anomalies, some of which can be explained by near surface biological processes, whereas others, especially helium anomalies, were more difficult to explain. These results show the utility of baseline surveys, and highlight the need for follow-up studies to clarify any unexplained anomalies before any CO2 storage.
La surveillance de l’intégrité des projets de stockage géologique du CO2 situé à terre requiert une approche intégrant diverses méthodes offrant différentes résolutions spatiales et temporelles. Parmi celles-ci, le relevé géochimique des gaz en surface s’est avéré très efficace pour l’évaluation des sites, la surveillance de fuites et la vérification de l’intégrité du stockage. Cette approche comprend des mesures de concentrations des gaz dans le sol et des mesures de flux de gaz. La détection de concentrations ou des flux anormaux est un signe éventuel de fuite. Toutefois, les concentrations en gaz et flux naturels peuvent être très variables, en particulier en ce qui concerne le CO2, de par son processus de production biologique et de son accumulation dans le sol qui dépendent du type de sol, de l’usage des terres, de la géologie, de la température, de la teneur en eau et de divers autres paramètres. Avec pour objectif la compréhension de l’influence de ces paramètres sur les valeurs naturelles en surface ainsi que l’évaluation du potentiel des différentes stratégies de sondage, ce papier présente deux études de cas très différents, l’un dans le nord de l’Europe (Voulund, Danemark) et l’autre dans le sud de l’Europe (Sulcis, en Sardaigne, Italie). Le petit site de Voulund, avec son sol, son climat et sa topographie homogènes, a fait l’objet de deux sondages (en automne et au printemps) dans le cadre du projet SiteChar financé par l’UE afin d’appréhender les effets de différentes pratiques d’utilisation des terres ainsi que ceux induits par les variations saisonnières sur les valeurs de référence. On constate que les deux campagnes ont relevé de plus faibles concentrations en CO2 dans les zones forestières que sur les terres cultivées et prospères, et que des valeurs plus élevées en CH4 ont été mesurées au printemps. Des sondes permettant des mesures en continu fournissent plus de détails, et montrent notamment que les changements saisonniers des concentrations en CO2 du sol sont principalement liés aux variations de température. Dans le cadre d’un projet financé par l’ENEA sur le potentiel de déploiement ECBM (Enhanced Coal Bed Methane) de CO2, le site de Sulcis, beaucoup plus grand que le précédent, a été étudié à l’échelle régionale au moyen d’un échantillonnage détaillé à des fins d’évaluation du site. En dépit de conditions totalement différentes du sol et du climat, la distribution statistique des données de Sulcis était semblable à celle de Voulund. Beaucoup plus d’anomalies relatives à des concentrations élevées en CO2 du sol ont été observées sur ce site, en raison de sédiments moins perméables (i.e. d’une meilleure rétention d’eau et d’une plus grande accumulation de gaz) et de températures plus élevées. Des sondages détaillés sur ce site ont mis en évidence diverses anomalies significatives, dont certaines peuvent être expliquées par des processus biologiques près de la surface, tandis que d’autres, en particulier les anomalies de la concentration en hélium, sont plus difficiles à expliquer. Ces résultats montrent l’intérêt des lignes de base, et confirment la nécessité des études de suivi pour clarifier les anomalies inexpliquées avant tout stockage de CO2.
Identification of the factors influencing the distribution of vulnerable species can be useful for predicting their occurrence at a local to regional scale and for identifying the most suitable ...measures of management and conservation. We used generalized additive models to assess the effects of spatiotemporal, environmental, and operational factors on the catches of two myliobatids: the Common Eagle Ray Myliobatis aquila and the Bull Ray Pteromylaeus bovinus. Fishing data were collected from commercial midwater trawlers operating in the north-central Adriatic Sea during 2006–2013. Presence/absence and abundance (CPUE) data were modeled separately, and eachmodel was then validated by using a test data set. The presence/absence and abundance of Common Eagle Rays and Bull Rays were mostly influenced by spatial (haul location) and temporal predictors. The major occurrences of Common Eagle Rays and Bull Rays were observed in the upper Adriatic Sea between late spring and early autumn. During winter, a southward shift in the catch was recorded for both species. In accordance with a significant effect of depth, Common Eagle Rays were more likely to be caught in hauls conducted between 10- and 60-m depths. The CPUEs of Common Eagle Rays and Bull Rays declined significantly with haul duration and net vertical opening. The validation procedure indicated that the predictive accuracy of the models was rather good. Giving new insight into the ecological requirements of Common Eagle Rays and Bull Rays, the results of this studymay contribute to the development of conservation strategies and can be used to direct future monitoring and research programs.
Understanding the movements of exploited fish has become a major concern for several management and conservation initiatives, such as the implementation of well designed marine protected areas. ...Movements of an important recreational target species from the Mediterranean Sea, the parrotfish Sparisoma cretense, were determined in a marine protected area using passive acoustic telemetry, to evaluate site fidelity and homing, quantify home range and identify temporal patterns. Six adult parrotfish (20.8–29.8 cm total length) were caught along the north-eastern coast of Lampedusa (Italy) and surgically implanted with acoustic transmitters. Three fish were caught and released at the same site within the integral (i.e. “no entry-no take”) reserve, whereas the others were caught outside the reserve boundary and released at the mid reserve 0.5 km apart. Two of the three fish that were released away from the capture site demonstrated homing abilities. Four fish showed a strong site fidelity, whereas the others moved frequently in and out of the monitoring area. Home range sizes estimated over the period of monitoring (up to 207 days) varied from 70,387 to 256,398 m2, with core areas of 16,688 to 84,946 m2. Home range size did not differ significantly between day and night. Home ranges of all fish extended beyond the reserve boundaries, showing example of potential spillover into take zones. Temporal activity patterns of fish were diurnal with a dominant diel rhythm, likely due to a resting behaviour at night. Though not specifically designed to protect exploited fish, the marine reserve of Lampedusa seems adequate for the conservation and management of S. cretense.
► We assess movement patterns of parrotfish within and across the boundaries of an MPA. ► Some parrotfish demonstrated homing abilities. ► Home range of parrotfish included areas outside the MPA. ► Activity patterns of parrotfish were basically diurnal with a dominant diel rhythm.
Modeling the relationships between environmental factors and the distribution at sea of species of conservation interest can be useful in predicting their occurrence from a local to a regional scale. ...This information is essential for planning management and conservation initiatives. In this study, generalized additive models (GAMs) were applied to investigate the influence of environmental, temporal and spatial variables on the catch rates of the twaite shad Alosa fallax (Lacepède) by the pelagic trawl fishery in the north‐central Adriatic Sea. Presence/absence and abundance catch per unit effort (CPUE) data between 2006 and 2012 were separately modeled, and the two models were then validated using a test data set. The most important factor influencing the presence and abundance of adult twaite shads was the spatial predictor (latitude × longitude). Two areas of major shads aggregations were observed, the most important of which being located near the estuaries of three main river systems of northern Italy. The twaite shad presence was also significantly affected by season, the largest and lowest occurrences being observed in autumn and spring, respectively. Among the environmental variables tested, only sea surface temperature was included in both models. Alosa fallax showed a wide thermal tolerance (6–27°C) with preference for temperature around 23°C. The model developed from the abundance data showed a moderate predictive power, whereas the accuracy of the presence/absence model was rather low. Some conclusions on the ecological requirements of A. fallax at sea arising from this study are useful to orient future monitoring and research programs and to develop effective conservation actions.
The movements of a commercially important species, Diplodus vulgaris, were assessed in a marine-protected area to test whether their spatial and temporal activity patterns differ during and outside ...of their spawning season. Twelve adults were caught along the north-eastern coast of a small Mediterranean island, tagged with acoustic transmitters and released within or just outside the integral reserve. Fish detected, during both the seasons showed strong fidelity for the study area before and during the spawning season and their home range did not differ between seasons. Home ranges reached an asymptote between 12 and 174 days after release. Home range estimated by kernel utilization distributions ranged from 9, 876 to 89, 914 m.sup.2, with core areas of 946 to 7, 274 m.sup.2. Temporal patterns frequently showed a dominant diel rhythm with most of detections occurring at daytime, independently of season. The variability in the movement patterns of D. vulgaris was lower between seasons (i.e., during and outside the spawning season) than at smaller temporal scale (i.e., between day and night) and was largely affected by inter-individual differences. Some conclusions arising from this and previous findings are useful to orient future studies on coastal fish movement and have direct implications for MPAs design.
Abstract
Modeling the relationships between environmental factors and the distribution at sea of species of conservation interest can be useful in predicting their occurrence from a local to a ...regional scale. This information is essential for planning management and conservation initiatives. In this study, generalized additive models (
GAM
s) were applied to investigate the influence of environmental, temporal and spatial variables on the catch rates of the twaite shad
Alosa fallax
(Lacepède) by the pelagic trawl fishery in the north‐central Adriatic Sea. Presence/absence and abundance catch per unit effort (
CPUE
) data between 2006 and 2012 were separately modeled, and the two models were then validated using a test data set. The most important factor influencing the presence and abundance of adult twaite shads was the spatial predictor (latitude × longitude). Two areas of major shads aggregations were observed, the most important of which being located near the estuaries of three main river systems of northern Italy. The twaite shad presence was also significantly affected by season, the largest and lowest occurrences being observed in autumn and spring, respectively. Among the environmental variables tested, only sea surface temperature was included in both models.
Alosa fallax
showed a wide thermal tolerance (6–27°C) with preference for temperature around 23°C. The model developed from the abundance data showed a moderate predictive power, whereas the accuracy of the presence/absence model was rather low. Some conclusions on the ecological requirements of
A. fallax
at sea arising from this study are useful to orient future monitoring and research programs and to develop effective conservation actions.
The movements of a commercially important species,
Diplodus vulgaris
, were assessed in a marine-protected area to test whether their spatial and temporal activity patterns differ during and outside ...of their spawning season. Twelve adults were caught along the north-eastern coast of a small Mediterranean island, tagged with acoustic transmitters and released within or just outside the integral reserve. Fish detected, during both the seasons showed strong fidelity for the study area before and during the spawning season and their home range did not differ between seasons. Home ranges reached an asymptote between 12 and 174 days after release. Home range estimated by kernel utilization distributions ranged from 9,876 to 89,914 m
2
, with core areas of 946 to 7,274 m
2
. Temporal patterns frequently showed a dominant diel rhythm with most of detections occurring at daytime, independently of season. The variability in the movement patterns of
D. vulgaris
was lower between seasons (i.e., during and outside the spawning season) than at smaller temporal scale (i.e., between day and night) and was largely affected by inter-individual differences. Some conclusions arising from this and previous findings are useful to orient future studies on coastal fish movement and have direct implications for MPAs design.
Underwater oil and gas extraction and distribution, as well as the investigation of solutions for CO 2 storage underwater, demand for new technologies to perform pervasive real life monitoring and ...control of underwater critical infrastructures. In this paper we present a system, named CO2Net, we have developed to perform accurate real-life monitoring of underwater CO 2 storage infrastructures. The basic component of our system is the CO2Probe, a new underwater monitoring node which combines sensing, acoustic communications and networking capabilities. CO2Probes are connected via acoustic links in an underwater sensor network which provides robust, real-life communications of the monitored data both in single-hop and multi-hop deployments. The user has a realtime control on the monitoring system, being able to change alarm threshold values and sampling rates. The proposed CO2Net approach overcomes the major limitations of system currently available on the market, and provides a first easy to use, flexible and easy to extend, complete monitoring system for underwater infrastructures, based on the emerging underwater sensor networking paradigm. A first prototype of CO2Net has been tested during summer-fall 2011 at the NATO Undersea Research Centre (NURC) in La Spezia. Results of these experiments confirm system reliability, and its adaptability: all requested data where provided in real-time, the system was remotely accessible and end user could change monitoring parameters.
Carbon dioxide (CO2) geological storage relies on safe, long-term injection of large quantities of CO2 in underground porous rocks. Wells, whether they are the conduit of the pumped fluid or are ...exposed to CO2 in the storage reservoir (observation and old wells) are man-made disturbances to the geological storage complex, and are thus viewed by some as a possible risk factor to the containment of the injected CO2.
Wells are composite structures, with an inner steel pipe separated from the borehole rock wall by a thin cement sheath (∼2 cm) that prevents vertical fluid migration. Both carbon steel and cement react in the presence of CO2, although evidence from production of CO2-rich fluids in the oil and gas industry and from lab experiments suggests that competent, defect-free cement offers an effective barrier to CO2 migration and leaks.
However, reactivity of cement and steel may result in CO2 migration pathways degrading over time, thus in the leakage risk increasing during the life of the storage project. The issue then becomes how to best integrate preventive verification of zonal isolation/well integrity in the storage site monitoring plan. An analysis of the order of magnitude of possible CO2 leaks, and of their path to potable aquifers or the atmosphere, is also necessary to optimize the assurance (mitigation) monitoring of the storage site.
Evidence gathered during the MovECBM project indicates that migration of small quantities of CO2 happened during injection in a coal seam in Southwest Poland. The evidence, gathered from casing and cement logging as well as soil gas monitoring over a 3-year period, was coupled with laboratory testing and extensive modeling of the chemo-mechanical behavior of cement and steel to determine if CO2 migration might have been responsible of the observed behavior.
The three lines of evidence were: The detection of very small CO2 fluxes, coupled with less controversial helium concentration in soil; the occurrence of a thin pathway at the interface between cement and casing; and the change in mechanical properties of cement, suggestive of partial carbonation.
Whereas the observations suggest that limited CO2 migration might have happened in the well, they are by no means proof that the migration did happen. Nonetheless, the integration of measurement and modeling yields important lessons for wellbore monitoring.
First, it puts a probable ceiling on the order of magnitude of expected leaks from reasonably well-cemented wells at around 100 metric tons per year (less than 0.05% of the injected mass in a well like Sleipner or In Salah). It also suggests that cement may be a very effective leak detector: Exposure to CO2 modifies its mechanical properties, which in turn can be detected using cement evaluation logs. Finally, coupling with dispersion modeling suggests the precision and accuracy required from soil gas and atmospheric monitoring, as well as the placement of sampling points; it also suggest that hysteresis, due to the accumulation in CO2 in surface aquifers and to the time required for it to be transported to the survey points, may delay initial detection; the same hysteresis may at the same time prolong the occurrence of CO2 shows long after the leak has stopped.
PDF
