Testing for the effects of sediment sorting on detrital-zircon age spectra by sampling multiple bedforms in single fluvial channels: Case studies from the Wood Canyon Formation (Terreneuvian) and Stirling Quartzite (Ediacaran), southeastern CA

Multiple bedforms were sampled from single fluvial channels in the Neoproterozoic (Ediacaran) upper member of the Stirling Quartzite and the Cambrian (Terreneuvian) middle member of the Wood Canyon Formation, southeastern California. Sampling strategy was designed to determine if sorting of detrital zircon populations by their textural properties can affect detrital-zircon age spectra in fluvial sandstones. Four samples derive from the middle member Wood Canyon Formation and two samples come from the upper member Stirling Quartzite. Sandstone samples vary in textural characteristics: grain sizes sampled range from fine to coarse sand, sorting ranges from moderately well to poorly sorted, and sampled sedimentary structures include tabular planar cross-stratification, tabular tangential cross-stratification, and plane stratification. Wood Canyon Formation samples contain whole detrital zircons with similar grain size ranges, from ~80 μm [micrometer] to ~300 μm. Whole detrital zircons in samples of the Stirling Quartzite range in size: sample SQ1-JM contains zircons from 76 μm to 288 μm, whereas SQ5-JM contains grains from 67 μm to 183 μm. Age spectra from each of the fluvial channels are compared quantitatively using Kolmogorov-Smirnov (K-S) testing, overlap, and likeness. Kolmogorov-Smirnov testing classifies all samples from each channel as similar. No two samples from the same channel have an overlap of less than 73 %. Likeness values are greater than 72 % for samples from the same fluvial channel, indicating similarity. Comparing the size, sphericity, and roundness of whole detrital zircons to their ages, yields no general correlations. Sorting of sediments by their textural properties does not affect detrital-zircon age spectra in the Stirling Quartzite or Wood Canyon Formation, and is not a general rule in fluvial sediments. The main factor controlling the detrital-zircon age spectra of a sedimentary rock is its provenance. The findings confirm that the high-frequency Grenvillian peak in the middle member of the Wood Canyon Formation results from provenance, not sampling bias. Rift-flank uplift caused by the Ouachita rift in modern Texas and Oklahoma may have generated a pulse of Grenvillian detrital zircons entering westward-flowing braided-alluvial systems that is recorded in the middle member of the Wood Canyon Formation

Scaling-up experiments of smouldering combustion as a remediation technology for contaminated soil

Self-sustaining Treatment for Active Remediation (STAR) is a novel, patent-pending process that uses smouldering combustion as a remediation technology for land contaminated with hazardous organic liquids. Compounds such as chlorinated solvents, coal tar and petroleum products, called Non-Aqueous Phase Liquids (NAPLs) for their low miscibility with water, have a long history of use in the industrialised world and are among the most ubiquitous of contaminants worldwide. These contaminants are toxic and many are suspected or known carcinogens. Existing remediation technologies are expensive and ineffective at reducing NAPL source zones sufficiently to restore affected water resources to appropriate quality levels. STAR introduces a self-sustaining smouldering reaction within the NAPL pool in the subsurface and allows that reaction to provide all of the post-ignition energy required by the reaction to completely remediate the NAPL source zone in the soil. Results from laboratory and field experiments have been very promising. Laboratory experiments have demonstrated STAR across a wide range of NAPL fuels and focused on coal tar to identify key parameters for successful remediation. Modelling has suggested that STAR efficiency will improve with scale as effects such as heat losses from boundaries become less significant. Observations from field experiments support the modelling theory - significantly lower relative air flow in a smouldering field experiment (330L) led to faster smouldering front propagation than observed in laboratory experiments (1L and 3L). Preliminary emissions monitoring by Fourier Transform Infrared (FTIR) spectroscopy has suggested that STAR emissions might be low enough to meet regulatory requirements, but further study is necessary. As emissions are expected to vary with each contaminant, activated carbon filters are being developed and tested in case emissions filtration is necessary. Experiments at all scales have demonstrated that STAR is controllable and self-terminating. Pilot-scale (2500L) field trials are underway to demonstrate STAR on excavated contaminated soil. The materials that will be studied in these trials are manufactured coal tar in coarse sand (which is the same material as used in the laboratory and field experiments) as well as two soils obtained from coal tar contaminated sites. This poster focuses on the scale-up to these field trials, including small scale characterisation, large scale performance, emissions monitoring and post-treatment soil analysis

Experimental studies of self-sustaining thermal aquifer remediation (STAR) for non-aqueous phase liquid (NAPL) sources

Self-sustaining Thermal Aquifer Remediation (STAR) is a novel technology that employs smouldering combustion for the remediation of subsurface contamination by non-aqueous phase liquids (NAPLs). Smouldering is a form of combustion that is slower and less energetic than flaming combustion. Familiar examples of smouldering involve solid fuels that are destroyed by the reaction (e.g., a smouldering cigarette or peat smouldering after a wildfire). In STAR, the NAPL serves as the fuel within an inert, porous soil medium. Results from experiments across a range of scales are very promising. Detailed characterisation has focused on coal tar, a common denser-than-water NAPL (DNAPL) contaminant. Complete remediation is demonstrated across this range of scales. Visual observations are supported bychemical extraction results. Further experiments suggest that STAR can be self-sustaining, meaning that once ignited the process can supply its own energy to propagate. Costly energy input is reduced significantly. Comparison of large scale to small scale laboratory experiments, a volume increase by a factor of 100, suggests that STAR process efficiency increases with scale. This increase in efficiency results from reduced heat losses at larger scales while maximum the temperature achieved by STAR is unaffected. The research also demonstrates the controllability of STAR, where the termination of airflow to the reaction terminates the STAR process. The scale-up process provides important guidance to the development of full scale STAR for ex situ remediation of NAPL-contaminated soil

Small-scale forward smouldering experiments for remediation of coal tar in inert media

This paper presents a series of experiments conducted to assess the potential of smouldering combustion as a novel technology for remediation of contaminated land by water-immiscible organic compounds. The results from a detailed study of the conditions under which a smouldering reaction propagates in sand embedded with coal tar are presented. The objective of the study is to provide further understanding of the governing mechanisms of smouldering combustion of liquids in porous media. A small-scale apparatus consisting of a 100 mm in diameter quartz cylinder arranged in an upward configuration was used for the experiments. Thermocouple measurements and visible digital imaging served to track and characterize the ignition and propagation of the smouldering reaction. These two diagnostics are combined here to provide valuable information on the development of the reaction front. Post-treatment analyses of the sand were used to assess the amount of coal tar remaining in the soil. Experiments explored a range of inlet airflows and fuel concentrations. The smouldering ignition of coal tar was achieved for all the conditions presented here and self-sustained propagation was established after the igniter was turned off. It was found that the combustion is oxygen limited and peak temperatures in the range 800-1080 °C were observed. The peak temperature increased with the airflow at the lower range of flows but decreased with airflow at the higher range of flows. Higher airflows were found to produce faster propagation. Higher fuel concentrations were found to produce higher peak temperatures and slower propagation. The measured mass removal of coal tar was above 99% for sand obtained from the core and 98% for sand in the periphery of the apparatus

ENV-634: MICROBIAL SUBSURFACE REPOPULATION FOLLOWING IN SITU STAR REMEDIATION

STAR (Self-sustaining Treatment for Active Remediation) is an emerging remediation technology that employs a self-sustaining smouldering reaction to destroy nonaqueous phase liquids (NAPLs) in the subsurface. The reaction front travels at rates of 0.5 to 5 m per day and subjects the soil to temperatures between 400°C and 1200°C (Pironi et al. 2011; Switzer et al. 2009). Consequently, not only does STAR cause an in situ destruction of NAPL, but it dries and sterilizes the soil through which it passes (Pape et al. 2015). Microbial recolonization of these sterile treated zones is important to the overall remediation of the site, since soils require microbial populations to cycle nutrients and provide a supportive base for above ground ecosystems (Nwaishi et al. 2016; Tisdall and Oades 2012). However, the smouldering process also acts to remove organics and nutrients, and lowers the cation exchange capacity of the soil. This creates a difficult environment for microbial repopulation to occur in. Indeed, it has been shown in a microcosm study that microbial recovery following thermal treatment at temperatures above 500 oC is up to three orders of magnitude lower than in soils which received thermal treatment at temperatures below 500 oC (Pape et al. 2015). Nevertheless, it is hypothesized that in situ post–STAR microbial repopulation will show more success, as organics and nutrients will be supplied to the treated zone by the influent groundwater. In this study, the microbial repopulation of an in situ STAR treatment zone is investigated at a field site in New Jersey called Pitt Consol. Final results will include analysis of bacteria and archaea population magnitude and diversity within soil cores taken from the treatment zone before and at regular intervals over six months following STAR treatment, allowing time for groundwater to re-infiltrate the treatment zone and for microbial populations to potentially reestablish. Samples from outside the treatment zones will also be analyzed to provide background data. Further, long term column experiments are looking into the effect of biostimulating the post-STAR treatment zone to enhance recovery time. Microbial abundance and diversity data from both the field observations and biostimulation experiments are expected to be compiled by late spring

ENV-601: A NEW METHOD FOR CONVERTING SEWAGE TO ENERGY USING SELF-SUSTAINING SMOULDERING

A major challenge in designing resilient infrastructure is to meet the needs of sustainable development (Kennedy & Corfee-Morlot, 2013). Sustainable development requires a high degree of energy efficiency. Municipal wastewater treatment plants (WWTPs), in particular, have the potential to be much more sustainable. In the U.S., 3 – 4% of the total energy consumed is dedicated to WWTPs and drinking water services, accounting for 30 – 40% of energy consumed by municipalities (U.S. EPA, 2014). In Canada, 25% of the $123 billion municipal deficit in 2006 was tied to water supply systems (i.e., drinking water, wastewater, and storm water) (Mirza, 2006). This problem becomes further complicated as much of North America’s WWTP infrastructure approaches the end of its design life. An estimated$298 billion and $39 billion is required in the U.S. and Canada, respectively, to satisfactorily refurbish WWTP infrastructure (ASCE, 2013; Félio et al., 2012). Within WWTPs, around 50% of the operating and capital costs are dedicated to managing the solid by-product, biosolids, making it the most expensive system component (Khiari et al., 2004). In Canada, 90% of biosolids are either incinerated or land applied for agricultural purposes (Apedaile, 2001). These methods are expensive, requiring high energy inputs in various forms (e.g., fuel, labour, transportation) (Wang et al., 2008). Land application is also subject to limitations and uncertain risks due to the potential for introducing synthetic contaminants into the environment (Hale et al., 2001; U.S. EPA, 1995). In general, managing biosolids persists as a major energy intensive challenge within WWTPs and there is a strong need to provide novel solutions (Tyagi & Lo, 2013). Self-sustaining smouldering combustion of organic wastes was originally developed as a chemical waste management and soil-clean up technology (Pironi et al., 2011; Scholes et al., 2015; Switzer et al., 2009). Smouldering is a flameless form of combustion for solid and liquid fuels, where a common example is glowing red charcoal in a traditional barbeque (Ohlemiller, 1985). The fuel (e.g. oil sludge) is mixed with sand to form a fixed-bed; this increases the surface area for reaction, provides porosity for the oxidant (air), and efficiently transfers, stores, and recycles the released reaction energy (Switzer et al., 2009). The smouldering reaction typically reaches temperatures between 500-800°C for many minutes in one location resulting in upwards of 99% conversion of organic waste to heat (Pironi et al., 2011). Smouldering in this configuration is unique as it supports an extremely energy efficient, self-sustaining reaction; therefore, following ignition, no external energy is required to sustain the reaction indefinitely. As a result, the process can smoulder fuels containing little energy or significant water contents that would otherwise not burn (e.g., via incineration) (Switzer et al., 2009; Yermán et al., 2015). Proof-of-concept experiments demonstrated for the first time that biosolids, obtained from Greenway Pollution Control Centre (London, ON) could be successfully destroyed via self-sustained smouldering. Thirty experiments in 40 cm tall, 15 cm diameter fixed-bed columns mapped the parameter space of self-sustained smouldering as a function of sand dilution, biosolids water content, and injected air flow rate. The results demonstrate that a self-sustaining reaction was achieved using biosolids with water contents as high as 80% (1.6 MJ/kg, effective calorific value). With little input of energy, the biosolids were converted to heat, steam, and emissions dominated by carbon dioxide. These ENV-601-2 results suggest that smouldering presents strong potential as a cost and energy effective waste management alternative for WWTP biosolids, achieving on-site destruction with minimal energy input and limited preliminary processing (Rashwan et al., 2016). This underscores the beneficial application of smouldering as a novel waste management technique that may be useful in designing resilient infrastructure

ENV-654: NUMERICAL MODELLING OF SMOULDERING COMBUSTION TO OPTIMIZE EX SITU SOIL TREATMENT SYSTEM DESIGN

There is widespread soil contamination at thousands of cites in Canada resulting from the historical improper storage and disposal of industrial liquids (Story et al., 2014). Large financial resources are allocated to remediation efforts due to the human and environmental health risks associated with exposure to such contamination, with over $582 million CAN spent on remediation in 2014-15 by the Canadian government alone (Treasury Board of Canada, 2016). Our scientific understanding of site remediation has evolved greatly over the past decades and it is now widely accepted that remediation of the contaminant source zone is necessary to achieve a high level of long-term remediation (Kueper et al., 2014). Non-aqueous phase liquids, or NAPLS, are one of the most prevalent contaminants at contaminated sites and are challenging to remediate due to their highly recalcitrant nature (Kueper et al., 2003). Although many remediation technologies have been developed over the past decades, the challenge in source zone remediation of NAPLs persists. The application of smouldering combustion to treat NAPL contaminated soils has been proven as an effective technology with both the laboratory experiments and applied in situ at a field site (Switzer et al., 2009, Pironi et al., 2011, Switzer et al, 2014, Salman et al., 2015, Scholes et al., 2015). This technology, titled “Self-sustaining treatment for active remediation”, or STAR, utilizes the high calorific value of NAPLs to ignite and sustain a smouldering oxidation reaction, effectively destroying the contaminant in the process. A phenomenological model developed by MacPhee et al. (2012) uniquely combined a multiphase flow model, perimeter expansion model, and analytical expression for the forward smouldering front velocity. This model is able to predict the propagation of the reaction front in response to the interplay between a heterogeneous distribution of permeability and the time-dependent distribution of air flux. After subsequent calibration by Hasan et al. (2014), the model was shown to correctly predict the ultimate extent and time of remediation during treatment for 2D lab scale experiments

In Situ Biological Contamination Studies of the Moon: Implications for Future Planetary Protection and Life Detection Missions

NASA and ESA have outlined visions for solar system exploration that will include a series of lunar robotic precursor missions to prepare for, and support a human return to the Moon, and future human exploration of Mars and other destinations. One of the guiding principles for exploration is to pursue compelling scientific questions about the origin and evolution of life. The search for life on objects such as Mars will require that all spacecraft and instrumentation be sufficiently cleaned and sterilized prior to launch to ensure that the scientific integrity of extraterrestrial samples is not jeopardized by terrestrial organic contamination. Under the Committee on Space Research's (COSPAR's) current planetary protection policy for the Moon, no sterilization procedures are required for outbound lunar spacecraft, nor is there yet a planetary protection category for human missions. Future in situ investigations of a variety of locations on the Moon by highly sensitive instruments designed to search for biologically derived organic compounds would help assess the contamination of the Moon by lunar spacecraft. These studies could also provide valuable "ground truth" data for Mars sample return missions and help define planetary protection requirements for future Mars bound spacecraft carrying life detection experiments. In addition, studies of the impact of terrestrial contamination of the lunar surface by the Apollo astronauts could provide valuable data to help refine future Mars surface exploration plans for a human mission to Mars

Tethered Particle Motion Reveals that LacI·DNA Loops Coexist with a Competitor-Resistant but Apparently Unlooped Conformation

AbstractThe lac repressor protein (LacI) efficiently represses transcription of the lac operon in Escherichia coli by binding to two distant operator sites on the bacterial DNA and causing the intervening DNA to form a loop. We employed single-molecule tethered particle motion to observe LacI-mediated loop formation and breakdown in DNA constructs that incorporate optimized operator binding sites and intrinsic curvature favorable to loop formation. Previous bulk competition assays indirectly measured the loop lifetimes in these optimized DNA constructs as being on the order of days; however, we measured these same lifetimes to be on the order of minutes for both looped and unlooped states. In a range of single-molecule DNA competition experiments, we found that the resistance of the LacI-DNA complex to competitive binding is a function of both the operator strength and the interoperator sequence. To explain these findings, we present what we believe to be a new kinetic model of loop formation and DNA competition. In this proposed new model, we hypothesize a new unlooped state in which the unbound DNA-binding domain of the LacI protein interacts nonspecifically with nonoperator DNA adjacent to the operator site at which the second LacI DNA-binding domain is bound