Genetic differentiation between morphotypes in the Antarctic limpet <Emphasis Type="Italic">Nacella concinna</Emphasis> as revealed by inter-simple sequence repeat markers

The limpet Nacella concinna (Strebel 1908) was the focus of numerous studies dealing with Antarctic benthos. One of the main characteristics of the species is the presence of two distinguishable morphotypes, one inhabiting the intertidal (during summer) and the other inhabiting the subtidal. For a long time these forms were considered as an expression of phenotypic plasticity, since previous studies did not found genetic differences between them. In the present work, we performed both a morphometric and a genetic differentiation analysis (using ISSR-PCR markers) of these two forms in three stations sampled at Potter Cove, South Shetland Islands. The results confirmed the morphological differences between intertidal and subtidal forms reported in other Antarctic localities. The genetic differences detected indicate that the two forms can be considered as genetically distinct populations maintaining low levels of gene flow. The degree of reproductive isolation of the ecotypes is discussed, as well as the possible origin of the divergence. The genetic differentiation observed can also have behavioral and physiological correlates, pointing out the importance of taking into account the potential differences in the response of both populations to different conditions in future studies in this species. M. C. de Aranzamendi and R. Sahade contributed equally to this paper.     

Analysis of PCB levels in snow from the Aconcagua Mountain (Southern Andes) using the stir bar sorptive extraction

This paper presents a first result of an investigation of the presence of anthropogenic pollutants named polychlorinated biphenyls (PCBs, sum of 25 congeners) in snow samples in the Aconcagua Mountains in the Andean Range, along an altitudinal gradient. Samples were taken during an expedition in 2003 and analysed by using a specific technique of thermodesorption and GC-MS adapted to small amount of sample. Mountain ecosystems could be efficient natural trap of persistent organic pollutants (POPs) transported by the atmosphere, and it is shown in this note that PCBs are also present in snow samples but at low concentrations, levels ranged from 0.02 to 0.190 ng/L. The detected congeners were those more persistent (PCB 138, PCB180) and compared to other mountain and cold areas around the world, detected levels are in the low range indicating that pollution levels are lower in the southern hemisphere. This results points out the need of investigating with some more detail the role of mountains in the trapping of POPs and the associated risks including the climate change.     

Calibration and predictive ability analysis of longitudinal solute transport models in mountain streams

The first step in developing travel time and water quality models in streams is to correctly model solute transport mechanisms. In this paper a comparison between two solute transport models is performed. The parameters of the Transient Storage model (TS) and the Aggregated Dead Zone model (ADZ) are estimated using data of thirty seven tracer experiments carried out under different discharges in five mountain streams of Colombian Los Andes. Calibration is performed with the generalized uncertainty estimation method (GLUE) based on Monte-Carlo simulations. Aspects of model parameters identifiability and model parsimony are analyzed and discussed. The TS model with four parameters shows excellent results during calibration but the model parameters present high interaction and poor identifiability. The ADZ model with two independent and clearly identifiable parameters gives sufficiently precise calibration results. As a conclusion, it is stated that the ADZ model with only two parameters is a parsimonious model that is able to represent solute transport mechanisms of advection and longitudinal dispersion in the studied mountain streams. A simple model parameter estimation methodology as a function of discharge is proposed in this work to be used in prediction mode of travel time and solute transport applications along mountain streams.     

Determination of BTEX by GC–MS in Air of Offset Printing Plants: Comparison between Conventional and Ecological Inks

The use of inks containing organic solvents by the offset printing process implies in the release of volatile organic compounds to the work environment. Many of these compounds such as benzene, toluene, ethylbenzene, and the xylene isomers (well known by the acronym BTEX) are extremely toxic. In this study, the BTEX concentrations were determined in two different printing plants that use distinct types of inks: the conventional and the so-called ecological, which is manufactured based on vegetal oil. Concentration ranges were 43–84, 15–3,480, 2–133, 5–459, and 2–236 μg m^?3 for benzene, toluene, ethylbenzene, m?+?p-xylene, and o-xylene, respectively, for the conventional printing plant. At the ecological printing plant, concentration ranges were below limit of detection (<LD)-31, <LD-618, <LD-1,690, <LD-10,500, <LD-3,360 μg m^?3 for benzene, toluene, ethylbenzene, m?+?p-xylene, and o-xylene, respectively. BTEX concentrations are lower at the ecological printing environment than in the conventional, where mineral oil-based inks are used. However, the worker who cleans the printing matrices is exposed to high concentrations of ethylbenzene and xylenes, due probably to the cleaning product’s composition (containing high amounts of BTEX). Although the BTEX concentrations found in both printing work environments were below the limits considered by the Brazilian Law for Activities and Unhealthy Operations (NR-15), the exposure to such vapors characterizes risk to the workers’ health for some of the evaluated samples, mainly the personal ones.     

Is Denser Greener? An Evaluation of Higher Density Development as an Urban Stormwater‐Quality Best Management Practice1

Abstract: A simple spreadsheet model was used to evaluate potential water quality benefits of high‐density development. The question was whether the reduced land consumed by higher density development (vs. standard suburban developments) would offset the worse water quality generated by a greater amount of impervious surface in the smaller area. Total runoff volume and per acre loadings of total phosphorous, total nitrogen, and total suspended solids increased with density as expected, but per capita loadings and runoff decreased markedly with density. For a constant or given population, then, higher density can result in dramatically lower total loadings than more diffuse suburban densities. The model showed that a simple doubling of standard suburban densities [to 8 dwelling units per acre (DUA) from about 3 to 5 DUA] in most cases could do more to reduce contaminant loadings associated with urban growth than many traditional stormwater best management practices (BMPs), and that higher densities such as those associated with transit‐oriented development could outperform almost all traditional BMPs, in terms of reduced loadings per a constant population. Because higher density is associated with vibrant urban life, building a better city may be the best BMP to mitigate the water quality damage that will accompany the massive urban growth expected for the next several decades.     

Sustainability Appraisal of Water Governance Regimes: The Case of Guanacaste,Costa Rica

Sustainability appraisals produce evidence for how well water governance regimes operate and where problems exist. This evidence is particularly relevant for regions that face water scarcity and conflicts. In this study, we present a criteria-based and participatory sustainability appraisal of water governance in a region with such characteristics—the dry tropics of NW Costa Rica. Data collection included 47 interviews and three stakeholder workshops. The appraisal was conducted through a collaborative and iterative process between researchers and stakeholders. Out of the 25 sustainability criteria used, seven posed a significant challenge for the governance regime. We found challenges faced by the governance regime primarily clustered around and were re-enforced by failing coordination related to the use, management, and protection of groundwater resources; and inadequate leadership to identify collective goals and to constructively deliberate alternative ways of governing water with diverse groups. The appraisal yielded some positive impact in the study area, yet we found its application provided only limited strategic information to support broader problem-solving efforts. Insights from this study suggest key starting points for sustainable water governance in the Central American dry tropics, including investing in increasingly influential collective organizations that are already active in water governance; and leveraging policy windows that can be used to build confidence and disperse more governing authority to regional and local governing actors that are in-tune with the challenges faced in the dry tropics. We conclude the article with reflections on how to produce research results that are actionable for sustainable water governance.     

Automated Calibration of the METRIC‐Landsat Evapotranspiration Process

A remaining challenge to applying satellite‐based energy‐balance algorithms for operational estimation of evapotranspiration (ET) is the calibration of the energy‐balance model. Customized calibration for each image date is generally required to overcome biases associated with radiometric accuracy of the image, uncertainties in aerodynamic features of the landscape, background thermal conditions, and model assumptions. The CIMEC process (calibration using inverse modeling at extreme conditions) is an endpoint calibration procedure where near extreme conditions in the image are identified where the ET can be estimated and assigned. In the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC?) energy‐balance model, two endpoints represent the dry and wet ends of the ET spectrum. Generally, user‐intervention is required to select locations in the image to produce best accuracy. To bring the METRIC and similar processes into the domain of less experienced operators, a consistent, reproducible, and dependable statistics‐based procedure is introduced where relationships between vegetation amount and surface temperature are used to identify a subpopulation of locations (pixels) in an image that may best represent the calibration endpoints. This article describes the background and logic for the statistical approach, how the statistics were developed, area of interest requirements and assumptions, adjustment for dry conditions in desert climates, and implementation in a common image processing environment (ERDAS Imagine).