Predicting the impact of aqueous ions on fate and transport of munition compounds

A model framework for natural water has been developed using computational chemistry techniques to elucidate the interactions between solvated munition compounds and eight common ions in naturally occurring water sources. The interaction energies, residence times, coordination statistics, and surface preferences of nine munition related compounds with each ion were evaluated. The propensity of these interactions to increase degradation of the munition compound was predicted using accelerated replica QM/MM simulations. The degradation prediction data qualitatively align with previous quantum mechanical studies. The results suggest that primary ions of interest for fate and transport modeling of munition compounds in natural waters may follow the relative importance of SO₄²⁻, Cl⁻ ≫ HCO₃⁻, Na⁺, Mg²⁺ > Ca²⁺, K⁺, and NH₄⁺.

Geological and hydrogeological characterization of the landfill areas located around Bucharest city in the context of environmental management

The process of risk assessment and investigation of potentially contaminated soil and groundwater is highly dependent on a proper understanding of the geological and hydrogeological conditions of the investigated site. The current paper aims at identifying the general geological and hydrogeological conditions of the landfill areas around Bucharest city based on interpretations of the data available in research articles, books, public reports, and geological and hydrogeological maps. Several soil samples were collected, and laboratory analyses were conducted to validate the initial expectations in terms of physical properties of the underlying strata. Results were presented as cross-sections and piezometric maps suitable for developing tridimensional models, conceptual site models and contaminant fate and transport modeling with sufficient accuracy for environmental urban planning. The research provides a quick method which may be used when assessing the general geological and hydrogeological conditions of various sites in environmental studies. The vulnerability of the Romanian legislation in data management and decision-making was also highlighted, therefore a series of recommendations to improve the data availability and quality were provided.

Numerical Modeling of Microbial Fate and Transport in Natural Waters: Review and Implications for Normal and Extreme Storm Events

Degradation of water quality in recreational areas can be a substantial public health concern. Models can help beach managers make contemporaneous decisions to protect public health at recreational areas, via the use of microbial fate and transport simulation. Approaches to modeling microbial fate and transport vary widely in response to local hydrometeorological contexts, but many parameterizations include terms for base mortality, solar inactivation, and sedimentation of microbial contaminants. Models using these parameterizations can predict up to 87% of variation in observed microbial concentrations in nearshore water, with root mean squared errors ranging from 0.41 to 5.37 log10 Colony Forming Units (CFU) 100 mL−1. This indicates that some models predict microbial fate and transport more reliably than others and that there remains room for model improvement across the board. Model refinement will be integral to microbial fate and transport simulation in the face of less readily observable processes affecting water quality in nearshore areas. Management of contamination phenomena such as the release of storm-associated river plumes and the exchange of contaminants between water and sand at the beach can benefit greatly from optimized fate and transport modeling in the absence of directly observable data.

Groundwater Solute Transport Modeling:Effects of Transport and Fate

In this paper, the solution of the advection-dispersion equation with different sorption values is used for the prediction of solute concentration in groundwater. Sorption process in the groundwater is complex, due to increasing the groundwater pollution the effect of different chemical transport plotted. The fate and sorption process of different chemical different degradation constant. We used the analytical solution to evaluate the transport phenomenon and analysis of the chemical dissolved in groundwater. The solute transport model simulated with the analytical solution and final result obtained using MATLAB software. The solution of a test problem based on the sequential degradation of the different chemical in the groundwater. This solution of equilibrium and rate of sorption dynamics of processes is imperative for accurate fate and transport modeling. The present study shows the effects of advection, dispersion/diffusion, and sorption equation on the saturated media of soil. MATLAB software used for analyzing the solution of groundwater and showing the different case taking care of saturated aquifer and with different void ratio of soil its shows that the soil parameter is also impotent parameter and its effect can see in plot between concertation vs time. The solute transport model simulated with the analytical solution and final result obtained using MATLAB software. The solution of a test problem based on the sequential degradation of the different chemical in the groundwater. This study compares the solute concentration with respect to distance and its different hydraulics conductivity of dense sad and lose.