1,720,986 research outputs found
Integration of a dynamic organism model into the DynA Model: Development and application to the case of DDT in Lake Maggiore, Italy
No full textPredicting chemical bioavailable concentrations in freshwater ecosystems for five european environmental scenarios
No full textEvaluating the spatial variability of PAH atmospheric concentrations through precipitation sampling
No full textHighly dynamic multimedia fate models in risk assessment of contaminated sites: why is “one fits all” unsuited?
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A spatially explicit dynamic multimedia fate model to investigate pesticide fate in mountain river basins
No full textEvaluating the temporal variability of concentrations of POPs in a glacier-fed stream food chain using a combined modeling approach
Full text linkFalling snow acts as an efficient scavenger of contaminants from the atmosphere and, accumulating on the ground surface, behaves as a temporary storage reservoir; during snowaging and metamorphosis, contaminants may concentrate and be subject to pulsed release during intense snow melt events. In high-mountain areas, firn and ice play a similar role. The consequent concentration peaks in surfacewaters can pose a risk to high-altitude ecosystems, since snow and ice melt often coincide with periods of intense biological activity. In such situations, the role of dynamic models can be crucialwhen assessing environmental behavior of contaminants and their accumulation patterns in aquatic organisms. In the present work, a dynamic fatemodeling approach was combined to a hydrological module capable of estimating water discharge and snow/ice melt contributions on an hourly basis, starting from hourly air temperatures. The model was applied to the case study of the Frodolfo glacierfed stream (Italian Alps), for which concentrations of a number of persistent organic pollutants (POPs), such as polychlorinated biphenyl (PCBs) and p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) in stream water and four macroinvertebrate groups were available. Considering the uncertainties in input data, results showed a satisfying agreement for both water and organism concentrations. This study showed the model adequacy for the estimation of pollutant concentrations in surface waters and bioaccumulation in aquatic organisms, as well as its possible role in assessing the consequences of climate change on the cycle of POPs
Pesticide fate in cultivated mountain basins: The improved DynAPlus model for predicting peak exposure and directing sustainable monitoring campaigns to protect aquatic ecosystems
No full textAgricultural activities can involve the use of plant protection products (PPPs) and the use of such chemicals can occur near surface waters bodies, thus creating a potential for adverse effects on aquatic ecosystems. In mountain watersheds, where runoff fluxes are particularly rapid due to side slopes, exposure is generally characterized by short but intense concentration peaks. Monitoring campaigns are often inadequate or too expensive to be carried out and modelling tools are therefore vital for exposure assessment and their use is encouraged by current legislation. However, currently adopted models and scenarios (e.g., FOCUS for PPPs) are often too conservative and/or “static” to accurately capture exposure variability, and the need for more realistic and dynamic tools is now one of the major challenges for risk assessment. In a previous work, the new fate model DynAPlus was developed to improve pesticide fate predictions in cultivated mountain basins and was successfully evaluated against chlorpyrifos water concentrations measured in a mountain stream in Northern Italy. However, the need for some model improvements (e.g., the inclusion of dissolved organic matter and macrophytes in water) was highlighted. In this work, DynAPlus was improved by replacing the water-sediment unit with ChimERA fate, a recently-published model capable of predicting bioavailable chemical concentrations in shallow water environments accounting for the presence and temporal variations of particulate/dissolved organic carbon and primary producers. The model was applied to preliminarily characterize the risk associated to the use of four PPPs (two insecticides and two fungicides) in a sub-basin of the Adda River (Valtellina Valley, Northern Italy), surrounded by apple orchards. Results revealed the potential magnitude of exposure peaks for the four PPPs and suggested that monitoring campaigns should prioritize, in the selected case study, chlorpyrifos, etofenprox and fluazinam. The potential role of DynAPlus in providing more realistic exposure predictions for ecological risk assessment, as well as for planning efficient monitoring campaigns and help pesticide management practices, was also stressed
Do environmental dynamics matter in fate models? Exploring scenario dynamics for a terrestrial and an aquatic system
No full textNowadays, there is growing interest in inserting more ecological realism into risk assessment of chemicals. On the exposure evaluation side, this can be done by studying the complexity of exposure in the ecosystem, niche partitioning, e.g. variation of the exposure scenario. Current regulatory predictive approaches, to ensure simplicity and predictive ability, generally keep the scenario as static as possible. This could lead to under or overprediction of chemical exposure depending on the chemical and scenario simulated. To account for more realistic exposure conditions, varying temporally and spatially, additional scenario complexity should be included in currently used models to improve their predictive ability. This study presents two case studies (a terrestrial and an aquatic one) in which some polychlorinated biphenyls (PCBs) were simulated with the SoilPlusVeg and ChimERA models to show the importance of scenario variation in time (biotic and abiotic compartments). The results outlined the importance of accounting for planetary boundary layer variation and vegetation dynamics to accurately predict air concentration changes and the timing of chemical dispersion from the source in terrestrial systems. For the aquatic exercise, the results indicated the need to account for organic carbon forms (particulate and dissolved organic carbon) and vegetation biomass dynamics. In both cases the range of variation was up to two orders of magnitude depending on the congener and scenario, reinforcing the need for incorporating such knowledge into exposure assessment
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