In Appreciation: Don L. Boyer (1938–2020)

Environmental Fluid Mechanics -     

Maritime ports and beach management as sources of coastal macro-, meso-, and microplastic pollution

Environmental Science and Pollution Research - Plastic pollution is a major environmental issue that affects coasts all around the world. Many studies point out the importance of a better...     

Microbial Source Tracking Analysis Using Viral Indicators in Santa Lucía and Uruguay Rivers,Uruguay

The aim of this study was to determine the origin (human, bovine or porcine) and the concentration of the fecal sources of contamination in waters from Santa Lucía basin and Uruguay River in Uruguay by using host-specific viral markers (adenoviruses and polyomaviruses) as microbial source tracking (MST). Between June 2015 and May 2016, monthly collections of surface water samples were performed in six sites in Santa Lucía basin and four sites in Uruguay River (n = 120 samples). Viral concentration was carried out using an absorption-elution method. Detection and quantification of human and porcine adenovirus (HAdV and PAdV, respectively) and human and bovine polyomavirus (HPyV and BoPyV, respectively) were performed by quantitative PCR (qPCR). To evaluate the infectivity of circulating HAdV, an integrated cell culture-qPCR (ICC-qPCR) was used. A logistic regression analysis was carried out to estimate the influence of environmental variables on the virus presence in surface waters. Overall, HAdV was the prevalent (18%; 21/120) followed by BoPyV (11%; 13/120) and HPyV (3%; 3/120), whereas PAdV was not detected in this study. The mean concentration ranged from 1.5 × 10⁴ genomic copies/L (gc/L) for HAdV to 1.8 × 10² gc/L for HPyV. Infective HAdVs were observed in two out of ten analyzed samples. A significant effect of environmental temperature (p = 0.001) and river (p = 0.012) on the presence of human viruses was found. These results suggest that fecal contamination could affect the water quality of these rivers, showing deficiencies in the procedure of sewage discharge from regional cities, livestock and dairy farms.

     

A coffee agroecosystem model: I. Growth and development of the coffee plant

This paper is the first of three on the coffee production system consisting of (1) the coffee plant, (2) coffee berry borer (CBB) and (3) the role of CBB parasitoids. A previous simulation model of the coffee plant was developed using data from Brazil where coffee phenology is characterized by distinct seasonal flowering (Gutierrez et al., 1998). In contrast, flowering in Colombia is continuous with low seasonality. To capture the differences in coffee phenology and growth in the two climatic regions, the Gutierrez et al. (1998) model was modified using new data from Colombia.The modifications to the model include:

(1)

The effect of solar radiation on floral buds initiation;

(2)

An age structure population model to track the daily input and development of the floral buds;

(3)

The effect of leaf water potential on breaking dormancy in flower buds, and hence on the timing and intensity of flowering;

(4)

The incorporation of both the vegetative and the reproductive demands to predict the photosynthetic rate.

(5)

The effect of low temperature on photosynthesis and defoliation.

Other aspects of the model were re-interpreted and refinements made to generalize its structure for use across coffee varieties and geographic areas. The model, without modification, realistically simulates field data from Brazil and two Colombian locations having different varieties, patterns of rainfall and hence flowering phenology.The model will be used as the base trophic level for incorporating CBB and high tropic levels effects, and for the analysis of management options in the coffee production system.     

Regression models for exceedance data via the full likelihood

Many situations in practice require appropriate specification of operating characteristics under extreme conditions. Typical examples include environmental sciences where studies include extreme temperature, rainfall and river flow to name a few. In these cases, the effect of geographic and climatological inputs are likely to play a relevant role. This paper is concerned with the study of extreme data in the presence of relevant auxiliary information. The underlying model involves a mixture distribution: a generalized Pareto distribution is assumed for the exceedances beyond a high threshold and a non-parametric approach is assumed for the data below the threshold. Thus, the full likelihood including data below and above the threshold is considered in the estimation. The main novelty is the introduction of a regression structure to explain the variation of the exceedances through all tail parameters. Estimation is performed under the Bayesian paradigm and includes model choice. This allows for determination of higher quantiles under each covariate configuration and upper bounds for the data, where appropriate. Simulation results show that the models are appropriate and identifiable. The models are applied to the study of two temperature datasets: maxima in the U.S.A. and minima in Brazil, and compared to other related models.     

Ecosystem development in roadside grasslands: biotic control, plant-soil interactions, and dispersal limitations

Roadside grasslands undergoing secondary succession are abundant, and represent ecologically meaningful examples of novel, human-created ecosystems. Interactions between plant and soil communities (hereafter plant-soil interactions) are of major importance in understanding the role of biotic control in ecosystem functioning, but little is known about these links in the context of ecosystem restoration and succession. The assessment of the key biotic communities and interactions driving ecosystem development will help practitioners to better allocate the limited resources devoted to roadside grassland restoration. We surveyed roadside grasslands from three successional stages (0-2, 7-9, and >20 years) in two Mediterranean regions of Spain. Structural equation modeling was used to evaluate how interactions between plants, biological soil crusts (BSCs), and soil microbial functional diversity (soil microorganisms) affect indicators of ecosystem development and restoration: plant similarity to the reference ecosystem, erosion control, and soil C storage and N accumulation. Changes in plant community composition along the successional gradient exerted the strongest influence on these indicators. High BSC cover was associated with high soil stability, and high soil microbial functional diversity from late-successional stages was associated with high soil fertility. Contrary to our expectations, the indirect effects of plants, mediated by either BSCs or soil microorganisms, were very weak in both regions, suggesting a minor role for plant-soil interactions upon ecosystem development indicators over long periods. Our results suggest that natural vegetation dynamics effectively improved ecosystem development within a time frame of 20 years in the grasslands evaluated. They also indicate that this time could be shortened if management actions focus on: (1) maintaining well-conserved natural areas close to roadsides to enhance plant compositional changes towards late-successional stages, (2) increasing BSC cover in areas under strong erosion risk, to avoid soil loss, and (3) enhancing soil microbial functional diversity in resource-limited areas, to enhance soil C and N accumulation.     

Human factors applied to alarm panel modernization of nuclear control room

Human factors deal with issues related to humans, their behavior and the physical aspect of the environment in which they work. A control room is a complex system where operators perform plant operation using control systems and carry out monitoring and administrative responsibilities. For safe operation of industrial installation, the performance of the control room crew plays an important role. In this respect, a well designed control room is crucial for safe and efficient operation. The aim of this paper is to propose a methodological framework applied to nuclear control room evaluation, through participatory ergonomics, using operator activity analysis and human factors questionnaire as aid tools. We describe a case study in which the methodology framework was used in the evaluation process of a nuclear control room. The information gathered made possible a series of recommendation for the adequacy of the control room design, assisting in the safety assessment of the nuclear plant operation and justifying the alarm panel modernization.     

Prospective thinking in a mustelid? <Emphasis Type="Italic">Eira barbara</Emphasis> (Carnivora) cache unripe fruits to consume them once ripened

The ability of nonhuman animals to project individual actions into the future is a hotly debated topic. We describe the caching behaviour of tayras (Eira barbara) based on direct observations in the field, pictures from camera traps and radio telemetry, providing evidence that these mustelids pick and cache unripe fruit for future consumption. This is the first reported case of harvesting of unripe fruits by a nonhuman animal. Ripe fruits are readily taken by a variety of animals, and tayras might benefit by securing a food source before strong competition takes place. Unripe climacteric fruits need to be harvested when mature to ensure that they continue their ripening process, and tayras accurately choose mature stages of these fruits for caching. Tayras cache both native (sapote) and non-native (plantain) fruits that differ in morphology and developmental timeframes, showing sophisticated cognitive ability that might involve highly developed learning abilities and/or prospective thinking.     

Improving the environmental performance of machine-tools: influence of technology and throughput on the electrical energy consumption of a press-brake

Machine-tools have been identified as one of the main energy-using products to be analyzed in an Ecodesign perspective, targeting the reduction of their environmental impact. Following this, machine-tool manufacturers are committed to anticipate eminent regulations and are looking for guidelines to improve their products on an effective and low-cost manner. This paper describes part of the energy consumption study followed in the frame of the Ecodesign of a commercial press-brake. All-hydraulic and all-electric commercially available systems, of different capacities and working in real production scenarios, have been included. From this study, a preliminary version of an LCI dataset for the bending process is proposed, structured in technology, machine capacity and usage mode categories, and using the bending cycle as the reference unit. The energy consumption per category was estimated based on a specific process energy model built as a function of the referred parameters. The contribution of the respective machine-tool structure to the environmental impact of the machining process is to be included, targeting the completion of such machining unit process dataset. The full LCA of an all-hydraulic system revealed the significant contribution of the machine-tool structure to the global life-cycle environmental impact of the machine (about 40%), while electricity during use phase contributes with about 46% to the total impact. This contradicts the general results published for other metal and non-metal forming processes, and is understood to be related with the discrete loading character of such forming processes here discussed.