Resource Model Updating For Compositional Geometallurgical Variables     

Prior  Ángel  Tolosana-Delgado  Raimon  van den Boogaart  K. Gerald  Benndorf  Jörg 《Mathematical Geosciences》2021,53(5):945-968

In the field of mineral resources extraction, one main challenge is to meet production targets in terms of geometallurgical properties. These properties influence the processing of the ore and are often represented in resource modeling by coregionalized variables with a complex relationship between them. Valuable data are available about geometalurgical properties and their interaction with the beneficiation process given sensor technologies during production monitoring. The aim of this research is to update resource models as new observations become available. A popular method for updating is the ensemble Kalman filter. This method relies on Gaussian assumptions and uses a set of realizations of the simulated models to derive sample covariances that can propagate the uncertainty between real observations and simulated ones. Hence, the relationship among variables has a compositional nature, such that updating these models while keeping the compositional constraints is a practical requirement in order to improve the accuracy of the updated models. This paper presents an updating framework for compositional data based on ensemble Kalman filter which allows us to work with compositions that are transformed into a multivariate Gaussian space by log-ratio transformation and flow anamorphosis. This flow anamorphosis, transforms the distribution of the variables to joint normality while reasonably keeping the dependencies between components. Furthermore, the positiveness of those variables, after updating the simulated models, is satisfied. The method is implemented in a bauxite deposit, demonstrating the performance of the proposed approach.

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Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico   总被引：1，自引：0，他引：1  

Huerta-Diaz MA  Delgadillo-Hinojosa F  Hernández-Ayón M  Segovia-Zavala JA  García-Esquivel Z  López-Zárate H  Siqueiros-Valencia A  Galindo-Bect S 《Marine environmental research》2008,66(3):345-358

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.  相似文献   

Coastal and estuarine habitat mapping, using LIDAR height and intensity and multi-spectral imagery   总被引：3，自引：1，他引：2  

Guillem Chust  Ibon Galparsoro  ngel Borja  Javier Franco  Adolfo Uriarte 《Estuarine, Coastal and Shelf Science》2008,78(4):633-643

The airborne laser scanning LIDAR (LIght Detection And Ranging) provides high-resolution Digital Terrain Models (DTM) that have been applied recently to the characterization, quantification and monitoring of coastal environments. This study assesses the contribution of LIDAR altimetry and intensity data, topographically-derived features (slope and aspect), and multi-spectral imagery (three visible and a near-infrared band), to map coastal habitats in the Bidasoa estuary and its adjacent coastal area (Basque Country, northern Spain). The performance of high-resolution data sources was individually and jointly tested, with the maximum likelihood algorithm classifier in a rocky shore and a wetland zone; thus, including some of the most extended Cantabrian Sea littoral habitats, within the Bay of Biscay. The results show that reliability of coastal habitat classification was more enhanced with LIDAR-based DTM, compared with the other data sources: slope, aspect, intensity or near-infrared band. The addition of the DTM, to the three visible bands, produced gains of between 10% and 27% in the agreement measures, between the mapped and validation data (i.e. mean producer's and user's accuracy) for the two test sites. Raw LIDAR intensity images are only of limited value here, since they appeared heterogeneous and speckled. However, the enhanced Lee smoothing filter, applied to the LIDAR intensity, improved the overall accuracy measurements of the habitat classification, especially in the wetland zone; here, there were gains up to 7.9% in mean producer's and 11.6% in mean user's accuracy. This suggests that LIDAR can be useful for habitat mapping, when few data sources are available. The synergy between the LIDAR data, with multi-spectral bands, produced high accurate classifications (mean producer's accuracy: 92% for the 16 rocky habitats and 88% for the 11 wetland habitats). Fusion of the data enabled discrimination of intertidal communities, such as Corallina elongata, barnacles (Chthamalus spp.), and stands of Spartina alterniflora and Phragmites australis, which presented misclassification when conventional visible bands were used alone. All of these results were corroborated by the kappa coefficient of agreement. The high classification accuracy found here, selecting data sources, highlights the value of integrating LIDAR data with multi-spectral imagery for habitat mapping in the intertidal complex fringe.  相似文献   

Shark interactions in pelagic longline fisheries   总被引：1，自引：0，他引：1  

Eric Gilman  Shelley Clarke  Nigel Brothers  Joanna Alfaro-Shigueto  John Mandelman  Jeff Mangel  Samantha Petersen  Susanna Piovano  Nicola Thomson  Paul Dalzell  Miguel Donoso  Meidad Goren  Tim Werner 《Marine Policy》2008

Substantial ecological, economic and social problems result from shark interactions in pelagic longline fisheries. Improved understanding of industry attitudes and practices towards shark interactions assists with managing these problems. Information on fisher knowledge and new strategies for shark avoidance may benefit sharks and fishers. A study of 12 pelagic longline fisheries from eight countries shows that incentives to avoid sharks vary along a continuum, based on whether sharks represent an economic disadvantage or advantage. Shark avoidance practices are limited, including avoiding certain areas, moving when shark interaction rates are high, using fish instead of squid for bait and deeper setting. Some conventionally employed fishing gear and methods used to target non-shark species contribute to shark avoidance. Shark repellents hold promise; more research and development is needed. Development of specifically designed equipment to discard sharks could improve shark post release survival prospects, reduce gear loss and improve crew safety. With expanding exploitation of sharks for fins and meat, improved data collection, monitoring and precautionary shark management measures are needed to ensure that shark fishing mortality levels are sustainable.  相似文献   

Spatiotemporal patterns of burned areas,fire drivers,and fire probability across the equatorial Andes     

Xavier ZAPATA-ROS  Carmen LOPEZ-FABARA  Abigail NAVARRETE  Sandra TORRES-PAGUAY  Miguel FLORES 《山地科学学报》2021,(4):952-972

Field-based fire studies in the equatorial Andes indicate that fires are strongly associated with biophysical and anthropogenic variables. However, fire controls and fire regimes at the regional scale remain undocumented. Therefore, this paper describes spatial and temporal burned-area patterns, identifies biophysical and anthropogenic fire drivers, and quantifies fire probability across 6° of latitude and 3° of longitude in the equatorial Andes. The spatial and temporal burned-area analysis was carried out based on 18 years(2001-2018) of the MCD64 A1 MODIS burned-area product. Climate, topography, vegetation, and anthropogenic variables were integrated in a logistic regression model to identify the significance of explanatory variables and determine fire occurrence probability. A total of 5779 fire events were registered during the 18 years of this study, located primarily along the western cordillera of the Andes and spreading from North to South. Eighty-eight percent of these fires took place within two fire hotspots located in the northwestern and southwestern corners of the study area. Ninety-nine percent occurred during the second part of the year, between June and December. The largest density of fires was primarily located on herbaceous vegetation and shrublands. Results show that mean monthly temperature, precipitation and NDVI during the prefire season, the location of land cover classes such as forest and agriculture, distance to roads and urban areas, slope, and aspect were the most important determinants of spatial and temporal fire distribution. The logistic regression model achieved a good accuracy in predicting fire probability(80%). Probability was higher in the southwestern and northern corners of the study area, and lower towards the north in the western and eastern piedmonts of the Andes. This analysis contributes to the understanding of fires in mountains within the tropics. The results here presented have the potential to contribute to fire management and control in the region.  相似文献   

Capabilities of the bathymetric Hawk Eye LiDAR for coastal habitat mapping: A case study within a Basque estuary   总被引：1，自引：0，他引：1  

Guillem Chust  Maitane Grande  Ibon Galparsoro  Adolfo Uriarte  Ángel Borja 《Estuarine, Coastal and Shelf Science》2010

The bathymetric LiDAR system is an airborne laser that detects sea bottom at high vertical and horizontal resolutions in shallow coastal waters. This study assesses the capabilities of the airborne bathymetric LiDAR sensor (Hawk Eye system) for coastal habitat mapping in the Oka estuary (within the Biosphere Reserve of Urdaibai, SE Bay of Biscay, northern Spain), where water conditions are moderately turbid. Three specific objectives were addressed: 1) to assess the data quality of the Hawk Eye LiDAR, both for terrestrial and subtidal zones, in terms of height measurement density, coverage, and vertical accuracy; 2) to compare bathymetric LiDAR with a ship-borne multibeam echosounder (MBES) for different bottom types and depth ranges; and 3) to test the discrimination potential of LiDAR height and reflectance information, together with multi-spectral imagery (three visible and near infrared bands), for the classification of 22 salt marsh and rocky shore habitats, covering supralittoral, intertidal and subtidal zones. The bathymetric LiDAR Hawk Eye data enabled the generation of a digital elevation model (DEM) of the Oka estuary, at 2 m of horizontal spatial resolution in the terrestrial zone (with a vertical accuracy of 0.15 m) and at 4 m within the subtidal, extending a water depth of 21 m. Data gaps occurred in 14.4% of the area surveyed with the LiDAR (13.69 km²). Comparison of the LiDAR system and the MBES showed no significant mean difference in depth. However, the Root Mean Square error of the former was high (0.84 m), especially concentrated upon rocky (0.55–1.77 m) rather than in sediment bottoms (0.38–0.62 m). The potential of LiDAR topographic variables and reflectance alone for discriminating 15 intertidal and submerged habitats was low (with overall classification accuracy between 52.4 and 65.4%). In particular, reflectance retrieved for this case study has been found to be not particularly useful for classification purposes. The combination of the LiDAR-based DEM and derived topographical features with the near infrared and visible bands has permitted the mapping of 22 supralittoral, intertidal and subtidal habitats of the Oka estuary, with high overall classification accuracies of between 84.5% and 92.1%, using the maximum likelihood algorithm. The airborne bathymetric Hawk Eye LiDAR, although somewhat limited by water turbidity and wave breaking, provides unique height information obscured from topographic LiDAR and acoustic systems, together with an improvement of the habitat mapping reliability in the complex and dynamic coastal fringe.  相似文献   

Distribution of diagenetic alterations within depositional facies and sequence stratigraphic framework of fluvial sandstones: Evidence from the Petrohan Terrigenous Group,Lower Triassic,NW Bulgaria     

Mohamed Ali Kalefa El-Ghali  Sadoon Morad  Howri Mansurbeg  Miguel Angel Caja  George Ajdanlijsky  Neil Ogle  Ihsan Al-Aasm  Manhal Sirat 《Marine and Petroleum Geology》2009

Sequence stratigraphy of fluvial deposits is a controversial topic because changes in relative sea level will eventually have indirect impact on the spatial and temporal distribution of depositional facies. Changes in the relative sea level may influence the accommodation space in fluvial plains, and hence have impact on types of fluvial system, frequency of avulsion, and style of vertical and lateral accretion. This study aims to investigate whether depositional facies and changes in the fluvial system of the Lower Triassic Petrohan Terrigenous Group sandstones (NW Bulgaria) in response to changes in the relative sea level have an impact on the spatial and temporal distribution of diagenetic alterations.  相似文献   

Climatic regimes and the recruitment rate of anchoveta, Engraulis ringens, off Peru   总被引：2，自引：0，他引：2  

Sandra M. Cahuin  Luis A. Cubillos  Miguel iquen  Rubn Escribano 《Estuarine, Coastal and Shelf Science》2009,84(4):591-597

The recruitment rate of Peruvian anchoveta, Engraulis ringens, was studied to test the hypothesis that long-term environmental variation (regime shifts) had a significant impact on density-dependent processes governing the anchovy recruitment during the period 1963–2004. On the basis of previous defined regimes and turning points for the Humboldt Current System, we identified two groups of years for increased recruitment of anchoveta (1963–1971 and 1986–2004), and one unfavorable period (1972–1985). A common intercept and significantly different slopes were found when the recruitment rate was plotted as a function of the spawning stock biomass during those groups of years, suggesting that density-dependent effects on recruitment were affected during different climate regimes. The favorable (unfavorable) regime was characterized by higher (lower) zooplankton volumes, and with a higher frequency of colder (warmer) waters. Dome-shaped relationships between recruitment rate, spawning stock biomass and SST, were detected with a Generalized Additive Model for the favorable regime. Thus, recruitment could be explained by non-linear effects of environmental variables. Ultimately, climatic regimes are affecting the density-dependent effects on recruitment of anchoveta and the mechanisms involved may be associated with changes in the carrying capacity of the spawning habitat of anchoveta off Peru, which in turn are related with the effects of cold and warm regimes.  相似文献   

Uncoupled transport of chlorofluorocarbons and anthropogenic carbon in the subpolar North Atlantic     

Marta Álvarez  Claire Gourcuff 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(7):860-868

Chlorofluorocarbon (CFC) 11 and 12 transports across the transoceanic World Ocean Circulation Experiment (WOCE) A25 section in the subpolar North Atlantic are derived from an inverse model using hydrographic and ADCP data (Lherminier et al., 2007). CFC and anthropogenic carbon (C_ANT) advective transports contrary to expected are uncoupled: C_ANT is transported northeastwards (82±39 kmol s^?1) mainly within the overturning circulation, while CFC-11 and CFC-12 are transported southwestwards (?24±4 and ?11±2 mol s^?1, respectively) as part of the large-scale horizontal circulation. The main reason for this uncoupled behaviour is the complex CFC vs. C_ANT relation in the ocean, which stems from the contrasting temperature relation for both tracers: more C_ANT dissolves in warmer waters with a low Revelle factor, while CFC’s solubility is higher in cold waters. These results point to C_ANT and CFC having different routes of uptake, accumulation and transport within the ocean, and hence: C_ANT transport would be more sensitive to changes in the overturning circulation strength, while CFC to changes in the East Greenland Current and Labrador Sea Water formation in the Irminger Sea. Additionally, C_ANT and CFCs would have different sensitivities to circulation and climate changes derived from global warming as the slowdown of the overturning circulation, increase stratification due to warming and changes in wind stress.  相似文献   

Middle Pleistocene large‐mammal faunas from North Iberia: palaeobiogeographical and palaeoecological implications          下载免费PDF全文

Diego J. Álvarez‐Lao 《Boreas: An International Journal of Quaternary Research》2016,45(2):191-206

The rich Quaternary fossil record from the Cantabrian region (NW Iberia) is virtually restricted to the Late Pleistocene, with Middle Pleistocene findings very rare. This work presents the study of two Middle Pleistocene palaeontological sites in the Cantabrian region: Llantrales quarry and Mestas de Con mine, both discovered and first described in the 1950s but never studied in detail thereafter. The material was here re‐analysed and re‐evaluated. Taxonomic attributions have been changed in most cases and, consequently, chronological assignments of the fossils have also been changed. This first detailed study of the assemblage from Llantrales quarry revealed the occurrence of the large‐sized deer Praemegaceros solilhacus, which has never been reported previously in North Iberia. Cervus cf. elaphus and Stephanorhinus cf. hundsheimensis were also identified. The age of these fossils was originally regarded as Pontian (late Miocene), but new palaeontological results indicate a much younger age, most likely from around 0.8 to 0.5 Ma. A taxonomic re‐evaluation of the fossils from Mestas de Con provided different results with respect to the 1950s works. The faunal association is composed of a large‐sized deer (probably corresponding to Praemegaceros), Cervus elaphus, Capreolus cf. capreolus, Bison sp. (small sized), Equus sp. (large sized), Stephanorhinus hemitoechus, Ursus sp. and Homotherim latidens. This faunal association was evaluated within a western European context and proves to be highly analogous to other contemporary assemblages there. The chronology was initially regarded as late Villafranchian (in a broader sense). New results, documenting the co‐occurrence of Stephanorhinus hemitoechus and Homotherium latidens, indicate a more precise and younger age, most likely between 0.6 and 0.4 Ma. These two fossil assemblages provide new and relevant information on the Middle Pleistocene faunas from a geographical region where this information, compared with other western European areas, is rare and poorly known.  相似文献