MUD: a Model to investigate the migration of 137Cs in the Urban environment and Drainage and sewage treatment systems

A model is presented for the migration of 137Cs in the urban environment, including the drainage systems and the sewage treatment plants, with flexibility to be adapted to different configurations common in urban areas. The dynamics of 137Cs is simulated both under natural evolution and in case of forced decontamination, which can have a direct impact on the radioactivity going to sewers. The model assesses the activity concentrated in sewage sludge and that discharged with the treated or untreated effluent to the receiving watercourse. Tests made for two post-Chernobyl contamination scenarios in Sweden show differences between model predictions and observed results within the range of the experimental uncertainties. An uncertainty and sensitivity analysis of the main model parameters indicates that some parameters may have a significant influence on the results of the model. Moreover, the model uncertainty is driven by a few parameters; therefore, additional research could be necessary into these parameters, aiming at simplifying the model without losing its predictive power.     

Passengers of impaired drivers

IntroductionThe aims of this study are: (a) to estimate the prevalence of passengers riding with alcohol-impaired drivers; (b) to investigate the role of demographic factors (age, gender, race/ethnicity, educational status) and relevant driving conditions (time of the day, trip origin, vehicle ownership) on shaping the likelihood of alcohol-impaired driving; (c) to identify and estimate the prevalence of passengers as alternative drivers (PADs); and (d) to examine the role that vehicle ownership plays in shaping the occurrence of PADs.MethodData came from a unique convenience sample of passengers obtained from the 2007 National Roadside Survey, a random sample of drivers from the 48 contiguous states.ResultsThe prevalence of PADs in the targeted population (mostly weekend night vehicles) was higher with drivers at .00 < BAC < .08 (17%-43%) than at BAC ≥ .08 (6%-29%) drivers. The evidence suggests that targeted policies to encourage PADs to drive might be possible. However, vehicle ownership is a large impediment for PADs to act as designated drivers. We speculate that vehicle ownership may be a main reason for the less-than expected success of the “designated driver” concept.     

Effects of Motorized Tourboats on the Behavior of Nonbreeding American Flamingos in Yucatan, Mexico

We assessed the effect of motorized tourboats on the behavior of nonbreeding American flamingos (  Phoenicopterus ruber ruber) in the Celestún Estuary, a Special Biosphere Reserve in Yucatán, Mexico, from November 1994 through February 1995. We measured these effects by comparing activity budgets between flocks of flamingos disturbed and undisturbed by tourboats. Disturbance reduced feeding time from 40% before disturbance to 24% after, a 40% loss. Boat disturbance increased alert behavior by 400%. Tourboats averaged 13 per day and caused a disturbance 75% of the time or 3.3 hours per day. Potential loss of feeding time for individuals was estimated at 13% but is likely much higher on days with excessive numbers of tourboats. Flamingos returned to normal feeding rates (40%) within 20 minutes after disturbance. Most tourists (52%) were from Mexico, followed by Germany (14%), and 88% of Mexican visitors were willing to pay an entrance fee to the Celestún Reserve. Conservation efforts should focus on education of tourboat operators to reduce disturbance to flamingos, education of tourists through a visitor's center and brochures produced in Spanish and English, and expanded involvement of local people.     

Unmanned aerial vehicle images in the machine learning for agave detection

Environmental Science and Pollution Research - In this study, six supervised classification algorithms were compared. The algorithms were based on cluster analysis, distance, deep learning, and...     

Phosphorus mass balance and input load estimation from the wet and dry periods in tropical semiarid reservoirs

The dynamics of total phosphorus (TP) in 18 strategic reservoirs of the high-density reservoir network of the Brazilian semiarid was evaluated during the wet and dry periods for the past 12 years. Seasonal overlying concentrations presented no significant differences for about 90% of the reservoirs (p>0.05). This was attributed to a trade-off between the hydrological/limnological processes occurring in the two seasons. Then, a transient complete-mix mass balance model was applied with particular adaptations for the tropical semiarid reservoirs to estimate the TP load for each season. Because of the relatively well-mixed conditions and high hypolimnetic dissolved oxygen concentrations during the wet season, the wet load was assumed to represent the external TP load. On the other hand, because of the absence of reservoir inflow during the dry season, phosphorus release under anoxic sediment conditions and wind-induced resuspension under shallow water depths, the dry load was assumed to reflect the internal TP load. The maximum external loads were related to peak inflows, notably after drought periods. Consistently, the largest internal loads were obtained during the drought periods, when the reservoirs were shallower and more prone to phosphorus release and resuspension. By comparing the impact of the two input load types, the wet period load was predominant in 72% of the reservoirs. The areal phosphorus loads ranged from 0.66 to 7.29 gP m² year^?1, which were consistent with the literature, despite the very high density of reservoirs. Finally, power-law curves including data for all studied reservoirs were adjusted between the dry period load and volume, dry and wet period loads, wet period load and inflow, and total load and catchment area, resulting in satisfactory R² (0.84–0.98).

     

Ionic Dye Removal Using Solvent-Assisted Ionic Micellar Flocculation

Journal of Polymers and the Environment - The environmental impacts caused by dyes in industrial wastewater are incalculable, due to their adverse effects on the ecosystem and human life,...     

Electrocatalytic conversion of nitrate waste into ammonia: a review

Environmental Chemistry Letters - The electrocatalytic reduction of nitrate waste into ammonia allows both the removal of nitrate contaminants and an alternative production of ammonia compared to...     

Mining tailings and alkali activation: a comprehensive bibliometric review

Environmental Science and Pollution Research - Significant amounts of mining tailings are generated and disposed of every year in dams, leading to potentially serious environmental and safety...     

Annealing Effect on Pla/Eva Blends Performance

Journal of Polymers and the Environment - PLA has aroused industrial and scientific interest in recent years, mainly due to its biodegradable character. However, PLA is brittle and displays low...