59 research outputs found
Integrating Lagrangian simulations of plastic pollution with chemical advection-diffusion processes to account for cetacean ingestion risk within the Pelagos Sanctuary
No full textThe Mediterranean Sea is heavily impacted by anthropogenic activities. Under the Marine Strategy Framework Directive, marine litter (Descriptor 10) has been recognized as one of the principal causes of marine pollution, and plastics is raising concern about impacts on marine wildlife. We investigated the risk of ingestion of plastic debris by marine biota by interlacing a decade (2000-2010) of microplastic concentration fields obtained through Lagrangian simulations with a Habitat Suitability Model (HSM) for our target species Balaenoptera physalus, an endangered cetacean for which there is increasing evidence of impacts due to microplastic ingestion. We released particles on a wide area embracing the Pelagos International Sanctuary for the Protection of Mediterranean Marine Mammals (North-Western Mediterranean, between France, Italy and Monaco), which harbors the summer feeding grounds of the fin whale. Maps of species exposure were obtained by feeding the HSM with chlorophyll-a satellite data and then overlapped with maps of plastic litter distribution derived from our oceanographic modelling, to obtain a spatially explicit indicator of the risk of plastic ingestion for the cetaceans feeding in the Sanctuary. Plastics also act as vectors of pollutants, in terms of both additives used for their production and other chemicals sorbed from the environment they float in. Therefore we propose a coupling of Lagrangian simulations with chemical advection-diffusion processes to start developing an integrated framework that allows a comprehensive analysis of the multi-faceted problems related to plastic contamination in the Mediterranean Sea
A parsimonious mechanistic model of reproductive and vegetative growth in fruit trees predicts consequences of fruit thinning and branch pruning
No full textProductivity of fruit tree crops depends on the interaction between plant physiology, environmental conditions and agricultural practices. We develop a mechanistic model of fruit tree crops that reliable simulates the dynamics of variables of interest for growers and consequences of agricultural practices while relying on a minimal number of inputs and parameters. The temporal dynamics of carbon content in the different organs (i.e., shoots-S, roots-R and fruits-F) are the result of photosynthesis by S, nutrient supply by R, respiration by S, R and F, competition among different organs, photoperiod and initial system conditions partially controlled by cultural practices. We calibrate model parameters and evaluate model predictions using unpublished data from a peach (Prunus persica) experimental orchard with trees subjected to different levels of branch pruning and fruit thinning. Fiinally, we evaluate the consequences of different combinations of pruning and thinning intensities within a multi-criteria analysis. The predictions are in good agreement with the experimental measurements and for the different conditions (pruning and thinning). Our simulations indicate that thinning and pruning practices actually used by growers provide the best compromise between total shoot production, which impacts next year's abundance of shoots and fruits, and current year's fruit production in terms of quantity (yield) and quality (average fruit size). This suggests that growers are not only interested in maximizing current year's yield but also in its quality and its durability. The present work provides for modelers a system of equations based on acknowledged principles of plant science easily modifiable for different purposes. For horticulturists, it gives insights on the potentialities of pruning and thinning. For ecologists, it provides a transparent quantitative framework that can be coupled with biotic and abiotic stressors
Influenza della modalità di coltivazione, essiccamento e stoccaggio sulla presenza di aflatossine in granella di mais
No full textOn the predictive ability of mechanistic models for the Haitian cholera epidemic
No full textPredictive models of epidemic cholera need to resolve at suitable aggregation levels spatial data pertaining to local communities, epidemiological records, hydrologic drivers, waterways, patterns of human mobility and proxies of exposure rates. We address the above issue in a formal model comparison framework and provide a quantitative assessment of the explanatory and predictive abilities of various model settings with different spatial aggregation levels and coupling mechanisms. Reference is made to records of the recent Haiti cholera epidemics. Our intensive computations and objective model comparisons show that spatially explicit models accounting for spatial connections have better explanatory power than spatially disconnected ones for short-to-intermediate calibration windows, while parsimonious, spatially disconnected models perform better with long training sets. On average, spatially connected models show better predictive ability than disconnected ones. We suggest limits and validity of the various approaches and discuss the pathway towards the development of case-specific predictive tools in the context of emergency management
Relazione tra contenuti di aflatossine della granella di mais e dei mangimi che la contengono.
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