Roelof Versteeg

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Arsenic concentrations measured by graphite-furnace atomic absorption range from <5 to 900 ug/L in groundwater pumped from 6000 wells within a 25 km 2 area of Bangladesh. The proportion of wells that exceed the local standard for drinking water of 50 ug/L arsenic increases with depth from 25% between 8-10 m to 75% between 15-30 m, then declines gradually to(More)
[1] Arsenic concentrations measured by graphite furnace atomic absorption range from < 5 to 900 mg/L in groundwater pumped from 6000 wells within a 25 km 2 area of Bangladesh. The proportion of wells that exceed the Bangladesh standard for drinking water of 50 mg/L arsenic increases with depth from 25% between 8 and 10 m to 75% between 15 and 30 m, then(More)
Previous work in the Instrumented OilField DDDAS project has enabled a new generation of data-driven, interactive and dynamically adaptive strategies for subsurface characterization and oil reservoir management. This work has led to the implementation of advanced multi-physics, multi-scale, and multi-block numerical models and an autonomic software stack(More)
We describe the design and implementation of a web-accessible scientific workflow system for environmental performance monitoring. This workflow environment integrates distributed automated data acquisition with server side data management and information visualization through flexible browser-based data access tools. Component technologies include a rich(More)
High frequency asymptotic approximation of the acoustic Green's function leads to eecient modeling and migration methods for primaries only reeection seismograms. A volume (as opposed to interface) oriented description of reeectivity allows symmetry between modeling and migration. With proper selection of amplitudes and dis-cretization, the migration and(More)
the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not(More)
Multi-offset, single-hole, borehole-radar reflection surveys were conducted at the U.S. Hampshire. The study was conducted to evaluate the benefits of applying multi-offset seismic processing techniques to borehole-radar reflection surveys in fractured rock. The multi-offset reflection surveys were conducted in conjunction with a saline tracer-injection(More)
Geophysical methods have been proposed as technologies for non-invasively monitoring geochemical alteration in permeable reactive barriers (PRBs). We conducted column experiments to investigate the effect of mineralogy on the electrical signatures resulting from iron corrosion and mineral precipitation in Fe0 columns using (a) Na2SO4, and (b) NaHCO3 plus(More)
Three-dimensional variably saturated flow and multicomponent biogeochemical reactive transport modeling, based on published and newly generated data, is used to better understand the interplay of hydrology, geochemistry, and biology controlling the cycling of carbon, nitrogen, oxygen, iron, sulfur, and uranium in a shallow floodplain. In this system,(More)