A Low-Cost Programmable Reversing Flow Column Apparatus for Investigating Mixing Zones

This note describes the development and testing of a novel, programmable reversing flow 1D (R1D) experimental column apparatus designed to investigate reaction, sorption, and transport of solutes in aquifers within dynamic reversing flow zones where waters with different chemistries mix. The motivation for constructing this apparatus was to understand the roles of mixing and reaction on arsenic discharging through a tidally fluctuating riverbank. The apparatus can simulate complex transient flux schedules similar to natural flow regimes The apparatus uses an Arduino microcontroller to control flux magnitude through two peristaltic pumps. Solenoid valves control flow direction from two separate reservoirs. In-line probes continually measure effluent electrical conductance, pH, oxidation–reduction potential, and temperature. To understand how sensitive physical solute transport is to deviations from the real hydrograph of the tidally fluctuating river, two experiments were performed using: (1) a simpler constant magnitude, reversing flux direction schedule (RCF); and (2) a more environmentally relevant variable magnitude, reversing flux direction schedule (RVF). Wherein, flux magnitude was ramped up and down according to a sine wave. Modeled breakthrough curves of chloride yielded nearly identical dispersivities under both flow regimes. For the RVF experiment, Peclet numbers captured the transition between diffusion and dispersion dominated transport in the intertidal interval. Therefore, the apparatus accurately simulated conservative, environmentally relevant mixing under transient, variable flux flow regimes. Accurately generating variable flux reversing flow regimes is important to simulate the interaction between flow velocity and chemical reactions where Brownian diffusion of solutes to solid-phase reaction sites is kinetically limited.     

Wegeners „Kontinentverschiebungen“ zu seiner Zeit und heute

Zusammenfassung Ausgangspunkt der Wegenerschen Theorie war der unmittelbare Eindruck von der Kongruenz der atlantischen Küsten. Das eigentliche Fundament bildeten jedoch die Argumente aus Paläontologie, Geophysik, Geologie, Paläoklimatologie und Astrogeodäsie. Wegener war nicht nur der Schöpfer, sondern auch der Propagandist seiner Theorie. Von bleibendem Wert erwiesen sich seine Forderungen: Jede Theorie der Entstehung der Ozeane und Kontinente muß von allen geowissenschaftlichen Disziplinen getragen werden und sie muß sich durch Messungen bestätigen lassen.

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The starting-point of Wegener's theory was the direct impression of the congruity of the Atlantic coastlines. The fundamental principle, however, is formed by the argumentation of paleontology, geophysics, geology, paleoclimatology and astrogeodesy. Wegener was not only the creator of his theory but he also propagated it. His demands proved to be of lasting value: every theory of the origin of oceans and continents has to be supported by all geosciences and it should be possible to be verified by physical measurements.

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Resume Le point de départ de la théorie de Wegener fut l'impression immédiate de la concordance des côtes atlantiques. Les bases véritables furent les arguments tirés de la Paléontologie, de la Géophysique, de la Géologie, de la Paléoclimatologie et de l'Astrogéodésie. Wegener fut non pas seulement le créateur de sa théorie, mais encore son propagandiste. Sa démarche reste valable d'une théorie de la genèse des continents et des océans qui soit étayée part toutes les sciences de la terre et verifée par des mesures physiques.

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Refined conceptualization of TOPMODEL for shallow subsurface flows

The TOPMODEL framework was used to derive expressions that account for saturated and unsaturated flow through shallow soil on a hillslope. The resulting equations were the basis for a shallow‐soil TOPMODEL (STOPMODEL). The common TOPMODEL theory implicitly assumes a water table below the entire watershed and this does not conceptually apply to systems hydrologically controlled by shallow interflow of perched groundwater. STOPMODEL provides an approach for extending TOPMODEL's conceptualization to apply to shallow, interflow‐driven watersheds by using soil moisture deficit instead of water table depth as the state variable. Deriving STOPMODEL by using a hydraulic conductivity function that changes exponentially with soil moisture content results in equations that look very similar to those commonly associated with TOPMODEL. This alternative way of conceptualizing TOPMODEL makes the modelling approach available to researchers, planners, and engineers who work in areas where TOPMODEL was previously believed to be unsuited, such as the New York City Watershed in the Catskills region of New York State. Copyright © 2002 John Wiley & Sons, Ltd.     

The determination of weakly and strongly bound copper,lead and cadmium in oslofjord samples

Weakly and strongly bound copper, lead and cadmium have been determined in the dissolved and particulate fractions of water samples from Oslofjord. The differentiation was made possible by using different sequences of filtration, acidification and digestion. The quantitative measurements were done by differential pulse anodic stripping voltammetry. Lead was found to be associated mostly with particulate matter, while cadmium was present only in the dissolved fraction. A strong digestion was needed for the determination of total metal. The advantage of pretreating sample bottles and filters with a conditioning solution is illustrated.     

The use of GPR and VES in delineating a contamination plume in a landfill site: a case study in SE Brazil

This paper presents the results of the application of the Ground Penetrating Radar (GPR) method, or Georadar, in outlining a zone of contamination due to solid residues at the waste burial site of Rio Claro in the state of São Paulo, SE Brazil. A total of eight GPR profiles with 50- and 100-MHz antennae were surveyed. Six profiles were located within the landfill site and the remaining two were outside. The main objective of the GPR survey was to evaluate the side extension of contamination. A Vertical Electric Sounding (VES) survey was performed at four points within the site in order to investigate the vertical extent of the contamination plume and to define the bottom of the landfill. Two additional VESs were done outside the landfill with the purpose of determining the top of the ground water table and the geoelectric stratigraphy of the background. From the interpretation of the GPR profiles, it was possible to locate the top of the contamination plume and to infer that it was migrating laterally beyond the limits of the waste disposal site. This was observed along the profile situated close to the highway SP-127, which was about 20 m from the limit of the site. The signature of the contaminant appears as a discontinuous reflector that is believed to be a shallow ground water table. The discontinuity is marked by a shadow zone, which is characteristic of conductive contaminant residues. The contamination did not move far enough to reach a sugar cane plantation located at approximately 100 m from the border of the site. In the regions free from contamination, the ground water table was mapped at approximately 10 m of depth, and it was characterized by a strong and continuous reflector. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 14 m deep, interpreted as the contact between the Rio Claro and the Corumbataí formations. The contact is marked by the presence of gravel characterized by ferruginous concretes, which cause the strong amplitude reflection in the GPR profile. Within the landfill site, the quantitative interpretation of the VES results showed the contamination zone. The base of the landfill varies between 11 and 15 m deep. Outside the landfill site, the VES results showed no indication of contamination and allowed the determination of the top of the ground water table and the contact between the Rio Claro and the Corumbataí formations. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology and information from several boreholes, about 17 m depth, on average. The bottom of the landfill reaches a maximum of 14.5 m depth.     

Collaborative Governance and Conflict Management: Lessons Learned and Good Practices from a Case Study in the Amazon Basin

Abstract

Given the linkages between natural resources and social conflicts, evidence increasingly shows that successful natural resource management requires conflict mitigation and prevention. However, there may be a gap in practice between knowing what processes and tools need to be used to manage conservation conflicts and how to actually implement them. We present learning from a practice-based case study of conflict management in the Amarakaeri Communal Reserve in the Peruvian Amazon that aimed to develop natural resource governance institutions and build stakeholder capacity, including of indigenous groups, to navigate existing conflict resolution mechanisms. Through applying good practices in conservation conflict management and collaborative governance, we generated important lessons on the practical considerations involved in collaborative conservation. These lessons, while specific to our case, could be applied to a variety of protected areas facing complex social-ecological systems dynamics and wicked problems.