Remediation of a marine shore tailings deposit and the importance of water-rock interaction on element cycling in the coastal aquifer

We present the study of the geochemical processes associated with the first successful remediation of a marine shore tailings deposit in a coastal desert environment (Bahia de Ite, in the Atacama Desert of Peru). The remediation approach implemented a wetland on top of the oxidized tailings. The site is characterized by a high hydrauliz gradient produced by agricultural irrigation on upstream gravel terraces that pushed river water (similar to 500 mg/L SO(4)) toward the sea and through the tailings deposit. The geochemical and isotopic (delta(2)H(water) and delta(18)O(water), delta(34)S(sulfate) , delta(18)O(sulfate)) approach applied here revealed that evaporite horizons (anhydrite and halite) in the gravel terraces are the source of increased concentrations of SO(4), Cl, and Na up to similar to 1500 mg/L in the springs at the base of the gravel terraces. Deeper groundwater interacting with underlying marine sequences increased the concentrations of SO(4), Cl, and Na up to 6000 mg/L and increased the alkalinity up to 923 mg/L CaCO(3) eq. in the coastal aquifer. These waters infiltrated into the tailings deposit at the shelf-tailings interface. Nonremediated tailings had a low-pH oxidation zone (pH 1-4) with significant accumulations of efflorescent salts (10-20 cm thick) at the surface because of upward capillary transport of metal cations in the arid climate. Remediated tailings were characterized by neutral pH and reducing conditions (pH similar to 7, Eh similar to 100 mV). As a result, most bivalent metals such as Cu, Zn, and Ni had very low concentrations (around 0.01 mg/L or below detection limit) because of reduction and sorption processes. In contrast, these reducing conditions increased the mobility of iron from two sources in this system: (1) The originally Fe(III)-rich oxidation zone, where Fe(II) was reduced during the remediation process and formed an Fe(II) plume, and (2) reductive dissolution of Fe(III) oxides present in the original shelf lithology formed an Fe-Mn plume at 10-m depth. These two Fe-rich plumes were pushed toward the shoreline where more oxidizing and higher pH conditions triggered the precipitation of Fe(HI)hydroxide coatings on silicates. These coatings acted as a filter for the arsenic, which naturally infiltrated with the river water (similar to 500 mu g/L As natural background) into the tailings deposit.

Multi-modal Change Detection, Application to the Detection of Flooded Areas: Outcome of the 2009-2010 data fusion contest

The 2009-2010 Data Fusion Contest organized by the Data Fusion Technical Committee of the IEEE Geoscience and Remote Sensing Society was focused on the detection of flooded areas using multi-temporal and multi-modal images. Both high spatial resolution optical and synthetic aperture radar data were provided. The goal was not only to identify the best algorithms (in terms of accuracy), but also to investigate the further improvement derived from decision fusion. This paper presents the four awarded algorithms and the conclusions of the contest, investigating both supervised and unsupervised methods and the use of multi-modal data for flood detection. Interestingly, a simple unsupervised change detection method provided similar accuracy as supervised approaches, and a digital elevation model-based predictive method yielded a comparable projected change detection map without using post-event data.

Development of a multistrain bacterial bioreporter platform for the monitoring of hydrocarbon contaminants in marine environments.

Petroleum hydrocarbons are common contaminants in marine and freshwater aquatic habitats, often occurring as a result of oil spillage. Rapid and reliable on-site tools for measuring the bioavailable hydrocarbon fractions, i.e., those that are most likely to cause toxic effects or are available for biodegradation, would assist in assessing potential ecological damage and following the progress of cleanup operations. Here we examined the suitability of a set of different rapid bioassays (2-3 h) using bacteria expressing the LuxAB luciferase to measure the presence of short-chain linear alkanes, monoaromatic and polyaromatic compounds, biphenyls, and DNA-damaging agents in seawater after a laboratory-scale oil spill. Five independent spills of 20 mL of NSO-1 crude oil with 2 L of seawater (North Sea or Mediterranean Sea) were carried out in 5 L glass flasks for periods of up to 10 days. Bioassays readily detected ephemeral concentrations of short-chain alkanes and BTEX (i.e., benzene, toluene, ethylbenzene, and xylenes) in the seawater within minutes to hours after the spill, increasing to a maximum of up to 80 muM within 6-24 h, after which they decreased to low or undetectable levels. The strong decrease in short-chain alkanes and BTEX may have been due to their volatilization or biodegradation, which was supported by changes in the microbial community composition. Two- and three-ring PAHs appeared in the seawater phase after 24 h with a concentration up to 1 muM naphthalene equivalents and remained above 0.5 muM for the duration of the experiment. DNA-damage-sensitive bioreporters did not produce any signal with the oil-spilled aqueous-phase samples, whereas bioassays for (hydroxy)biphenyls showed occasional responses. Chemical analysis for alkanes and PAHs in contaminated seawater samples supported the bioassay data, but did not show the typical ephemeral peaks observed with the bioassays. We conclude that bacterium-based bioassays can be a suitable alternative for rapid on-site quantitative measurement of hydrocarbons in seawater.

Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls

Agro-ecosystems have recently experienced dramatic losses of biodiversity due to more intensive production methods. In order to increase species diversity, agri-environment schemes provide subsidies to farmers who devote a fraction of their land to ecological compensation areas (ECA). Several studies have shown that invertebrate biodiversity is actually higher in ECA than in nearby intensively cultivated farmland. It remains poorly understood, however, to what extent ECA also favour vertebrates, such as small mammals and their predators, which would contribute to restore functioning food chains within revitalized agricultural matrices. We studied small mammal populations among eight habitat types - including wildflower areas, a specific ECA in Switzerland - and habitat selection (radiotracking) by the barn owl Tyto alba, one of their principal predators. Our prediction was that habitats with higher abundances of small mammals would be more visited by foraging Barn owls during the period of chicks' provisioning. Small mammal abundance tended to be higher in wildflower areas than in any other habitat type. Barn owls, however, preferred to forage in cereal fields and grassland. They avoided all types of crops other than cereals, as well as wildflower areas, which suggests that they do not select their hunting habitat primarily with respect to prey density. Instead of prey abundance, prey accessibility may play a more crucial role: wildflower areas have a dense vegetation cover, which may impede access to prey for foraging owls. The exploitation of wildflower areas by the owls might be enhanced by creating open foraging corridors within or around wildflower areas. Wildflower areas managed in that way might contribute to restore functioning food chains within agro-ecosystems.

Identification of potential rockfall source areas at a regional scale using a DEM-based geomorphometric analysis

The availability of high resolution Digital Elevation Models (DEM) at a regional scale enables the analysis of topography with high levels of detail. Hence, a DEM-based geomorphometric approach becomes more accurate for detecting potential rockfall sources. Potential rockfall source areas are identified according to the slope angle distribution deduced from high resolution DEM crossed with other information extracted from geological and topographic maps in GIS format. The slope angle distribution can be decomposed in several Gaussian distributions that can be considered as characteristic of morphological units: rock cliffs, steep slopes, footslopes and plains. A terrain is considered as potential rockfall sources when their slope angles lie over an angle threshold, which is defined where the Gaussian distribution of the morphological unit "Rock cliffs" become dominant over the one of "Steep slopes". In addition to this analysis, the cliff outcrops indicated by the topographic maps were added. They contain however "flat areas", so that only the slope angles values above the mode of the Gaussian distribution of the morphological unit "Steep slopes" were considered. An application of this method is presented over the entire Canton of Vaud (3200 km2), Switzerland. The results were compared with rockfall sources observed on the field and orthophotos analysis in order to validate the method. Finally, the influence of the cell size of the DEM is inspected by applying the methodology over six different DEM resolutions.

Geochemical compositions of marine fossils as proxies for reconstructing ancient environmental conditions.

A brief summary is given here about some of the geochemical methodologies that are often used to obtain information from fossils and sediments about the past environment. Such methods are frequently applied in our project in which the formation of Paleogene phosphate sequences in North Africa is investigated. These layers were deposited in shallow marine seas during a period of extreme warm climate with a high CO(2) concentration in the atmosphere. Some of the characteristics of this greenhouse interval are similar to the modern anthropogenic situation hence it is intensively investigated from several aspects by many scientists. Here the geochemical compositions of fossils deposited during this time are discussed, focusing on how the data are obtained and how they could be evaluated in terms of palaeo-environmental conditions.

Effectiveness of intermittent preventive treatment with sulfadoxine-pyrimethamine during pregnancy on placental malaria, maternal anaemia and birthweight in areas with high and low malaria transmission intensity in Tanzania.

OBJECTIVE: To assess the effectiveness of IPTp in two areas with different malaria transmission intensities. METHODS: Prospective observational study recruiting pregnant women in two health facilities in areas with high and low malaria transmission intensities. A structured questionnaire was used for interview. Maternal clinic cards and medical logs were assessed to determine drug intake. Placental parasitaemia was screened using both light microscopy and real-time quantitative PCR. RESULTS: Of 350 pregnant women were recruited and screened for placental parasitaemia, 175 from each area. Prevalence of placental parasitaemia was 16.6% (CI 11.4-22.9) in the high transmission area and 2.3% (CI 0.6-5.7) in the low transmission area. Being primigravida and residing in a high transmission area were significant risk factors for placental malaria (OR 2.4; CI 1.1-5.0; P = 0.025) and (OR 9.4; CI 3.2-27.7; P < 0.001), respectively. IPTp was associated with a lower risk of placental malaria (OR 0.3; CI 0.1-1.0; P = 0.044); the effect was more pronounced in the high transmission area (OR 0.2; CI 0.06-0.7; P = 0.015) than in the low transmission area (OR 0.4; CI 0.04-4.5; P = 0.478). IPTp use was not associated with reduced risk of maternal anaemia or low birthweight, regardless of transmission intensity. The number needed to treat (NNT) was four (CI 2-6) women in the high transmission area and 33 (20-50) in the low transmission area to prevent one case of placental malaria. CONCLUSION: IPTp may have an effect on lowering the risk of placental malaria in areas of high transmission, but this effect did not translate into a benefit on risks of maternal anaemia or low birthweight. The NNT needs to be considered, and weighted against that of other protective measures, eventually targeting areas which are above a certain threshold of malaria transmission to maximise the benefit.

Estimation of inelastic seismic material properties of a surgical sea-bed from multi-component marine seismic data

To date, state-of-the-art seismic material parameter estimates from multi-component sea-bed seismic data are based on the assumption that the sea-bed consists of a fully elastic half-space. In reality, however, the shallow sea-bed generally consists of soft, unconsolidated sediments that are characterized by strong to very strong seismic attenuation. To explore the potential implications, we apply a state-of-the-art elastic decomposition algorithm to synthetic data for a range of canonical sea-bed models consisting of a viscoelastic half-space of varying attenuation. We find that in the presence of strong seismic attenuation, as quantified by Q-values of 10 or less, significant errors arise in the conventional elastic estimation of seismic properties. Tests on synthetic data indicate that these errors can be largely avoided by accounting for the inherent attenuation of the seafloor when estimating the seismic parameters. This can be achieved by replacing the real-valued expressions for the elastic moduli in the governing equations in the parameter estimation by their complex-valued viscoelastic equivalents. The practical application of our parameter procedure yields realistic estimates of the elastic seismic material properties of the shallow sea-bed, while the corresponding Q-estimates seem to be biased towards too low values, particularly for S-waves. Given that the estimation of inelastic material parameters is notoriously difficult, particularly in the immediate vicinity of the sea-bed, this is expected to be of interest and importance for civil and ocean engineering purposes.

Automatic low baseline stereo in urban areas

In this work we propose a new automatic methodology for computing accurate digital elevation models (DEMs) in urban environments from low baseline stereo pairs that shall be available in the future from a new kind of earth observation satellite. This setting makes both views of the scene similarly, thus avoiding occlusions and illumination changes, which are the main disadvantages of the commonly accepted large-baseline configuration. There still remain two crucial technological challenges: (i) precisely estimating DEMs with strong discontinuities and (ii) providing a statistically proven result, automatically. The first one is solved here by a piecewise affine representation that is well adapted to man-made landscapes, whereas the application of computational Gestalt theory introduces reliability and automation. In fact this theory allows us to reduce the number of parameters to be adjusted, and tocontrol the number of false detections. This leads to the selection of a suitable segmentation into affine regions (whenever possible) by a novel and completely automatic perceptual grouping method. It also allows us to discriminate e.g. vegetation-dominated regions, where such an affine model does not apply anda more classical correlation technique should be preferred. In addition we propose here an extension of the classical ”quantized” Gestalt theory to continuous measurements, thus combining its reliability with the precision of variational robust estimation and fine interpolation methods that are necessary in the low baseline case. Such an extension is very general and will be useful for many other applications as well.

Review of Stability Berm Alternatives for Environmentally Senstitive Areas, 2005

Stability berms are commonly constructed where roadway embankments cross soft or unstable ground conditions. Under certain circumstances, the construction of stability berms cause unfavorable environmental impacts, either directly or indirectly, through their effect on wetlands, endangered species habitat, stream channelization, longer culvert lengths, larger right-of-way purchases, and construction access limits. Due to an ever more restrictive regulatory environment, these impacts are problematic. The result is the loss of valuable natural resources to the public, lengthy permitting review processes for the department of transportation and permitting agencies, and the additional expenditures of time and money for all parties. The purpose of this project was to review existing stability berm alternatives for potential use in environmentally sensitive areas. The project also evaluates how stabilization technologies are made feasible, desirable, and cost-effective for transportation projects and determines which alternatives afford practical solutions for avoiding and minimizing impacts to environmentally sensitive areas. An online survey of engineers at state departments of transportation was also conducted to assess the frequency and cost effectiveness of the various stabilization technologies. Geotechnical engineers that responded to the survey overwhelmingly use geosynthetic reinforcement as a suitable and cost-effective solution for stabilizing embankments and cut slopes. Alternatively, chemical stabilization and installation of lime/cement columns is rarely a remediation measure employed by state departments of transportation.

State Library and Library Service Areas Plan of Service FY05-06

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