Evaluating and classifying contaminated areas based on loss functions using annealing simulations     

Joaquim C.B. Queiroz  José R. Sturaro  Augusto C.F. Saraiva  Paulo M.B. Landim 《Journal of Geochemical Exploration》2009

This paper presents a methodology based on geostatistical theory for quantifying the risks associated with heavy-metal contamination in the harbor area of Santana, Amapá State, Northern Brazil. In this area there were activities related to the commercialization of manganese ore from Serra do Navio. Manganese and arsenic concentrations at unsampled sites were estimated by postprocessing results from stochastic annealing simulations; the simulations were used to test different criteria for optimization, including average, median, and quantiles. For classifying areas as contaminated or uncontaminated, estimated quantiles based on functions of asymmetric loss showed better results than did estimates based on symmetric loss, such as the average or the median. The use of specific loss functions in the decision-making process can reduce the costs of remediation and health maintenance. The highest global health costs were observed for manganese.  相似文献   

Groundwater overexploitation and soil subsidence monitoring on Recife plain (Brazil)     

Rejane Maria Rodrigues de Luna  Silvio Jacks dos Anjos Garnés  Jaime Joaquim da Silva Pereira Cabral  Sylvana Melo dos Santos 《Natural Hazards》2017,85(3):1363-1392

Facing natural disasters is a priority challenge for cities, exacerbated by increases in urban population and climate change. Improving the resilience of cities is a critical need for the international community and especially for territories exposed to multiple risks, such as Chile. Although disasters are always tragic, the recovery and reconstruction post-disaster may provide a unique opportunity to prevent future suffering, enhancing the resilience of local communities. This paper presents the analysis of two Chilean reconstruction programmes applied in Mehuin and Dichato, after the earthquake and tsunami of 22 May 1960 and 27 February 2010, respectively. In both cases, reconstruction programmes were supported by the Chilean Government, but using different approaches: one focused on providing housing for people injured in the earthquake, while the other also included urban amenities and services. This article proposes an urban morphology analysis framework; in addition, it presents the assessment of the two case studies before and after a disaster, thus evaluating their resilience. By comparing urban morphology resilience pre- and post-disaster, a discussion about the effectiveness of two reconstruction approaches is presented. Finally, conclusions and recommendations to better integrate resilience into urban planning are proposed, with the aim of opening the discussion about how to make cities more resilient to natural disasters.  相似文献   

An alternative practical design method for structures with viscoelastic dampers     

Joaquim Mimusse Tchamo  Ying Zhou 《地震工程与工程振动(英文版)》2018,17(3):459-473

Viscoelastic dampers (VEDs) are one of the most common passive control devices used in new and retrofit building projects which reduce the structure responses and dissipate seismic energy during an earthquake. Various methods to design this kind of dampers have been proposed based on the desired level of additional damping, eigenvalue assignment, modal strain energy, linear quadratic regulator control theories, and other approaches. In the current engineering practice, the popular method is the one based on the modal strain energy that uses the inter-story lateral stiffness as one of the main variables for damper design. However, depending on the configuration of the structure, in some cases the resulting interstory lateral stiffness can be very large. Consequently, the dampers size would also be large producing much more damping than that effectively necessary, resulting in an increase of the overall cost of the supplemental damping system and causing excessive stress on the structural elements connected to the dampers. In this paper an alternative practical design method for structures with VEDs is proposed. This method uses the inter-story shear forces as one of the main variables to accomplish the damper design compared to what was done in previous studies. Nonlinear time-history analyses were conducted on a 7-story reinforced concrete (RC) structure to check the reliability and effectiveness of the proposed method. Comparisons on the seismic performance between the structure without dampers and that equipped with VEDs were carried out. It is concluded that the proposed method results in a very suitable size of dampers, which are able to improve the performance of the structure at all levels of earthquake ground motions and satisfying the drift requirement prescribed in the codes.  相似文献   

Use of different intertidal habitats by faunal communities in a temperate coastal lagoon     

Cheila Almeida  Rui CoelhoMarco Silva  Luís BentesPedro Monteiro  Joaquim RibeiroKarim Erzini  Jorge M.S. Gonçalves 《Estuarine, Coastal and Shelf Science》2008

The faunal communities of four intertidal habitats namely sand, mud, seagrass (Zostera noltii) and seagrass patches (mixSM) of a temperate coastal lagoon, Ria Formosa (southern Portugal), were sampled. A total of 47 species were taken in 428 bottomless drop sampler samples, with the highest number of species and the more commonly occurring species belonging to the Mollusca phylum. The dominance of these gastropod species underlines the importance of the grazing food chain in these habitats. Bittium reticulatum was the most abundant species, being especially abundant in the seagrass habitat. The most frequent and highest biomass species in the community was Carcinus maenas, a predator that makes use of the available resources and that is adapted to the highly variable intertidal environment. Pomatoschistus microps was the most abundant fish species, with highest densities in the mud habitat, which demonstrates an ability to occupy a low depth area. The seagrass habitat had the highest diversity, abundance and biomass, followed by the mixSM habitat and was different from all the others. Assemblages were highly influenced by the presence of vegetation, providing forage and refuge from predation. A well defined summer group was identified in all habitats. These results highlight the importance of seagrass beds and the idea that their decrease implies the decrease of lagoon production through the impoverishment of the trophic structure of the lagoon.  相似文献   

Fish assemblages and rapid colonization after enlargement of an artificial reef off the Algarve coast (Southern Portugal)     

Francisco Leitão  Miguel N. Santos  Karim Erzini  Carlos C. Monteiro 《Marine Ecology》2008,29(4):435-448

Artificial reefs (ARs) have been deployed in Algarve (Southern Portugal) coastal waters to contribute to the sustainability of local nearshore fisheries. Herein, we describe the colonization process of the recently deployed Faro/Ancão AR, and assess the time until the fish assemblage reaches stability and their seasonal patterns. In addition, we compare the results from the present study with those previously reported for an older AR. The fish assemblages were monitored monthly over a 2‐year period by means of visual census. A rapid increase in fish colonization occurred within the first 4 months. After this initial period the assemblage structure showed high similarity (> 73%). The high rate of colonization of the AR was related to the maturity already achieved by the nearby 14‐year‐old AR and to the fish migration from the Ria Formosa lagoon, a nearby nursery habitat. The reef fish assemblage structure showed a seasonal pattern, mainly associated with recruitment episodes of occasional demersal species (Boops boops, Trachurus trachurus and Pagellus spp.) in spring and summer. A total of 66% of the species found in AR are of commercial and recreational importance. The overall mean density and biomass were 2.8 ind·m^?3 and 207 g·m^?3. The occasional demersal species accounted for 42% of the fish density. The most important species in terms of biomass belong to the Sparidae family along with Dicentrarchus labrax. The fish assemblage of the new ARs showed higher mean number of species, diversity, density and biomass values than those reported for the older AR. This result was associated with enlargement of the AR area and with the fishing exploitation of the isolated, small and patchy old AR. Moreover, the high biomass values recorded in the new ARs were mainly due to the increased density of D. labrax after AR enlargement. The results of the present study are used to define guidelines for suitable management strategies for the AR areas that are exploited by the local commercial and recreational fisheries.  相似文献   

Mesoscale and Nutrient Conditions Associated with the Massive 2008 Cochlodinium polykrikoides Bloom in the Sea of Oman/Arabian Gulf     

Adnan R. Al-Azri  Sergey A. Piontkovski  Khalid A. Al-Hashmi  Joaquim I. Goes  Helga do R. Gomes  Patricia M. Glibert 《Estuaries and Coasts》2014,37(2):325-338

Cochlodinium polykrikoides formed large blooms in the coastal waters of Oman from October 2008 through mid-January 2009, and satellite images from Aqua-MODIS and region-wide reports suggest that this bloom was found throughout the Arabian Gulf and Sea of Oman for more than 10 months. The unusual occurrence of this species appears to have supplanted the more regularly occurring bloom species, Noctiluca scintillans, in 2008–2009. For the first 2 weeks of the coastal Omani bloom, C. polykrikoides abundance was near monospecific proportions, with cell densities ranging from 4.6?×?10³ to 9?×?10⁶ cells L^?1 and very high levels of chlorophyll a (78.0 μg L^?1) were also recorded. The regional progression of the bloom likely began with stronger than normal upwelling along the Iranian and northern Omani coasts during the southwest monsoon in late summer, followed by discharge of unusually warm coastal plume water along the coast of Oman with the reversal of monsoonal winds in late October. The occurrence and persistence of high densities of C. polykrikoides in Oman coastal water were also significantly influenced by an elevated nutrient load and warmer than normal temperatures. Concentrations of nutrients, especially NH₄ ⁺, urea, PO₄ ^3?, and organic nitrogen and phosphorus, were manyfold higher than observed in the year prior or since. These findings suggest that mesoscale features were important in bloom dynamics more regionally, but locally the bloom was sustained by nutrient enrichment supplemented by its mixotrophic capabilities.  相似文献   

Oligocene to Present kilometres scale subsidence and exhumation of the Ligurian Alps and the Tertiary Piedmont Basin (NW Italy) revealed by apatite (U–Th)/He thermochronology: correlation with regional tectonics     

Giovanni Bertotti  Pietro Mosca  Joaquim Juez  Riccardo Polino  Tibor Dunai 《地学学报》2006,18(1):18-25

The Ligurian Alps segment of the Alpine–Apennine orogen in NW Italy is unconformably covered by Upper Eocene to Holocene sediments in the Tertiary Piedmont Basin (TPB) and Po Plain. These sediments dip towards the north demonstrating the erosional nature of the southern border of the succession and implying that the adjacent orogenic belt formed the substratum rather than the margin of the sedimentary basin. Apatite (U–Th)/He and fission track thermochronology shows that the orogen first subsided and was buried at >4 km from 30 to 26 Ma and began its exhumation thereafter. From 26 Ma to present, this upward movement was contemporaneous with subsidence in the northern TPB. The couple exhumation in the S and subsidence in the N migrated northwards through time. Vertical movements in the area are similar to those reconstructed in Corsica. In both cases, the onset of exhumation becomes younger away from the Ligurian‐Provençal basin and has little correlation with the opening of the surrounding oceanic basins.  相似文献   

Deep-water stands of Cystoseira zosteroides C. Agardh (Fucales,Ochrophyta) in the Northwestern Mediterranean: Insights into assemblage structure and population dynamics     

Enric Ballesteros  Joaquim Garrabou  Bernat Hereu  Mikel Zabala  Emma Cebrian  Enric Sala 《Estuarine, Coastal and Shelf Science》2009

Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m⁻². Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m⁻², and densities ranging from 4 to 7 plants m⁻². The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m⁻² and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.  相似文献   

Straw Blankets Sewn With Recycled Plastic Threads for Erosion and Urban Sediments Control     

Terezinha Cássia de Brito Galvão  Aloisio Rodrigues Pereira  Arnaldo Teixeira Coelho  Paula Rodrigues Pereira  Joaquim Fernandes Teixeira Coelho 《Geotechnical and Geological Engineering》2011,29(1):49-55

Soil erosion, transport and deposition of sediments represent invisible threats that along time can affect negatively the existing infrastructure of roads and dams, and the quality of air and water resources. In the last decades, a great number of researches were devoted to study erosion and sediments transportation processes. However, they addressed mostly areas of agriculture, water impoundments for dams, and land conservation. A lack of studies for erosion processes in urban areas is evident, in special those aiming to diminish the deposition of sediments originated from urban areas into the rivers and air, in special as airborne particulate. Traditionally, the costs associated in controlling erosion and sediments in urban areas are high and in some case, out of the range for most developing countries. Factors responsible for those high prices are the use of heavy equipments for soil grading and transportation, the use of costly building materials, and the need for employing more specialized personnel. In the case of gullies in urban areas, another concern is to ensure proper equipment access to the area for remediation operations. Hereby, it is presented a cost-effective method to recover an extensive gully erosion area of about 11,000 m² located in urban area. Estimated sediments released from this area to the water resources and air were estimated on about 66,000,000 tons. In this study area, bioengineering works were performed in 60 days, with hardly any sediment generated outside the work area resulting from bioengineering operations. A combination of bioengineering techniques were chosen for this study area, which was a mixture of rigid and biological products including biologs, silt fence, biodegradable straw blankets sewn with plastic threads derived from recycled PET bottles, among others. An efficient drainage system was implemented for preventing upland flow, sub-seepage and seepage. Biologs were used aiming to fulfill a double role, the first as barrier to soil sediments flow, and the second as filler for empty spaces, avoiding expensive grading operations. All engineering works were concluded in about 60 days at a cost of US0.89/m < sup > 2 < /sup > . This price is cost-effective if compared with the traditional engineering cost of approximately US 0.89/m². This price is cost-effective if compared with the traditional engineering cost of approximately US 2.92/m² because it includes extensive use of grading and soil transportation. An environmental advantage of the bioengineering method is the immediate reduction of airborne particulates. Furthermore, the overall visual aesthetics improved shortly after the implementation of the works because the bare ground was substituted by native vegetation. After 6 months the vegetation in the gully erosion area was totally established. Monitoring was performed after 12 months and no erosion and sediment transport was visually noticed. The ease implementation of this technique without the need for specialized workers in combination with low prices makes this method a model for developing countries.  相似文献   

The variable link between PNA and NAO in observations and in multi-century CGCM simulations   总被引：1，自引：1，他引：0  

Joaquim G. Pinto  Mark Reyers  Uwe Ulbrich 《Climate Dynamics》2011,36(1-2):337-354

The link between the Pacific/North American pattern (PNA) and the North Atlantic Oscillation (NAO) is investigated in reanalysis data (NCEP, ERA40) and multi-century CGCM runs for present day climate using three versions of the ECHAM model. PNA and NAO patterns and indices are determined via rotated principal component analysis on monthly mean 500?hPa geopotential height fields using the varimax criteria. On average, the multi-century CGCM simulations show a significant anti-correlation between PNA and NAO. Further, multi-decadal periods with significantly enhanced (high anti-correlation, active phase) or weakened (low correlations, inactive phase) coupling are found in all CGCMs. In the simulated active phases, the storm track activity near Newfoundland has a stronger link with the PNA variability than during the inactive phases. On average, the reanalysis datasets show no significant anti-correlation between PNA and NAO indices, but during the sub-period 1973?C1994 a significant anti-correlation is detected, suggesting that the present climate could correspond to an inactive period as detected in the CGCMs. An analysis of possible physical mechanisms suggests that the link between the patterns is established by the baroclinic waves forming the North Atlantic storm track. The geopotential height anomalies associated with negative PNA phases induce an increased advection of warm and moist air from the Gulf of Mexico and cold air from Canada. Both types of advection contribute to increase baroclinicity over eastern North America and also to increase the low level latent heat content of the warm air masses. Thus, growth conditions for eddies at the entrance of the North Atlantic storm track are enhanced. Considering the average temporal development during winter for the CGCM, results show an enhanced Newfoundland storm track maximum in the early winter for negative PNA, followed by a downstream enhancement of the Atlantic storm track in the subsequent months. In active (passive) phases, this seasonal development is enhanced (suppressed). As the storm track over the central and eastern Atlantic is closely related to the NAO variability, this development can be explained by the shift of the NAO index to more positive values.  相似文献