Quantifying effects of soil heterogeneity on groundwater pollution at four sites in the USA

Four sites located in the north-eastern region of the United States of America have been chosen to investigate the impacts of soil heterogeneity in the transport of solutes (bromide and chloride) through the vadose zone (the zone in the soil that lies below the root zone and above the permanent saturated groundwater). A recently proposed mathematical model based on the cumulative beta distribution has been deployed to compare and contrast the regions' heterogeneity from multiple sample percolation experiments. Significant differences in patterns of solute leaching were observed even over a small spatial scale, indicating that traditional sampling methods for solute transport, for example the gravity pan or suction Iysimeters, or more recent inventions such as the multiple sample percolation systems may not be effective in estimating solute fluxes in soils when a significant degree of soil heterogeneity is present. Consequently, ignoring soil heterogeneity in solute transport studies will likely result in under- or overprediction of leached fluxes and potentially lead to serious pollution of soils and/or groundwater. The cumulative beta distribution technique is found to be a versatile and simple technique of gaining valuable information regarding soil heterogeneity effects on solute transport. It is also an excellent tool for guiding future decisions of experimental designs particularly in regard to the number of samples within one site and the number of sampling locations between sites required to obtain a representative estimate of field solute or drainage flux.

Quantifying minimum monolith size and solute dilution from multi-compartment percolation sampler data

Preferential flow affects solute transport in natural soils, leading to high spatiotemporal variation of concentration. A multicompartment solute sampler (MCS), yielding multiple breakthrough curves at a given depth, can monitor tracer movement in a heterogeneous soil. We present a technique to estimate from MCS data whether a soil monolith is sufficiently large to capture preferential flow, which is a necessity for tracer breakthrough curves to be representative. For several soils, we estimate that an MCS should be larger than 0.1 to 0.2 m². We also expand dilution theory to analyze the concentration variations of a tracer passing the control plane monitored by the MCS, in addition to the conventional plume spreading analysis. We characterize the set of locally observed breakthrough curves by the entropy-based dilution index. For given first and second-central moment, the spatially uniform log-normal breakthrough curve maximizes the dilution index. The ratio between observed and maximum dilution index is denoted reactor ratio. For a 300-compartment solute sampler, covering an area of 0.75 m², we compute a reactor ratio of 0.665, compared with 0.04 for stochastic-convective and 1 for convective-dispersive transport. With a single, large collector the reactor ratio would be 0.958, severely underestimating concentration variations. Large collector areas are clearly inadequate to estimate dilution. Values of the dilution index and the reactor ratio for individual sampling compartments indicate efficient longitudinal mixing in most but not all cases, and considerable spatial variation of the leaching process.

Networking of Multimedia Women Event : beyond epsilon science - "where to look and how to realize new opportunities"

"Networking of Multimedia Women" event is a continuation of an on-going conversation in the multimedia research community and efforts by the ACM SIGMM to engage and promote female researchers in multimedia community, enable networking of junior and senior female researchers, and give insights towards successful professional careers based on examples. This year, the event will have a theme, called "Beyond Epsilon Science", where preeminent senior female researchers from academia, industry and government, Svetha Venkatesh, Nalini Venkatasubramanian, Dulce Ponceleon, Susanne Boll, and Maria Zemankova will present and discuss how to go beyond epsilon science, where to look for big ideas with high social impact, as well as how to obtain funding to realize these ideas, innovations and opportunities. Their current research projects and funding efforts, and their personal experiences will drive the event's discussions, awareness of major research and funding initiatives, answers to open questions and insights into successful professional careers.

Between context-aware media capture and multimedia content analysis - where do we find the promised land?

Various issues related to the multimedia information retrieval and media access are discussed. The feasible solutions for automatic signal-based analysis of media content are analyzed. The extent of user involvement in the content creation process is emphasized. The applications driving the creation and usage of context and metadata are also elaborated.