Landfill gas contains numerous speciated organic compounds (SOCs) including alkanes, aromatics, chlorinated aliphatic hydrocarbons, alcohols, ketones, terpenes, chlorofluoro compounds, and siloxanes. The source, rate and extent of release of these compounds are poorly understood. The objective of this study was to characterize the release of SOCs and the regulated parameter, non-methane organic compounds (NMOCs) during the decomposition of residential refuse and its major biodegradable components [paper (P), yard waste (YW), food waste (FW)]. Work was conducted under anaerobic conditions in 8-L reactors operated to maximize decomposition. Refuse and YW were also tested under aerobic conditions. NMOC release during anaerobic decomposition of refuse, P, YW, and FW was 0.151, 0.016, 0.038, and 0.221 mg-C dry g(-1), respectively, while release during aerobic decomposition of refuse and YW was 0.282 and 0.236 mg-C dry g(-1), respectively. The highest NMOC release was measured under abiotic conditions (3.01 mg-C dry g(-1)), suggesting the importance of gas stripping. NMOC release was faster than CH4 production in all treatments. Terpenes and ketones accounted for 32-96% of SOC release in each treatment, while volatile fatty acids were not a significant contributor. Release in aerobic systems points to the potential importance of composting plants as an emissions source.

The impact of peroxidase addition on sorption-desorption of phenol, o-cresol, 2,4-dichlorophenol (DCP), and 1-naphthol was evaluated using two surface soils. Target chemicals were added to soils as single solutes or binary mixtures. Seven-day adsorption studies were followed by sequential fill-and-draw extractions with synthetic groundwater. Addition of horseradish peroxidase (HRP) with H2O2 was the primary treatment evaluated. HRP-mediated sorption enhancementwas related to contaminant solubility and increased in the order: naphthol < DCP < cresol < phenol. Little or no competition was observed in the presence of cosolutes. Contaminant desorption from soils was dramatically reduced upon HRP addition. Reduction in desorption was quantified using the Hysteresis Index and interpreted as attenuation of contaminant mobility. Desorption data predicted that mobility reductions followed the order: naphthol < DCP < cresol < phenol. It is believed that enzyme addition resulted in the production of hydrophobic polymers that, due to their low aqueous solubilities, readily partitioned on to the solid-phase. The adsorbed polymers were less likely to partition into the aqueous phase than the parent phenols resulting in a reduced risk to the environment.

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Plasmonic nanosensors may be used as tools for diagnostic testing in the field of medicine. However, quantification of plasmonic nanosensors often requires complex and bulky readout instruments. Here, we report the development of a portable smart phone-based plasmonic nanosensor readout platform (PNRP) for accurate quantification of plasmonic nanosensors. This device operates by transmitting excitation light from a LED through a nanosubstrate and measuring the intensity of the transmitted light using the ambient light sensor of a smart phone. The device is a cylinder with a diameter of 14 mm, a length of 38 mm, and a gross weight of 3.5 g. We demonstrated the utility of this smart phone-based PNRP by measuring two well-established plasmonic nanosensors with this system. In the first experiment, the device measured the morphology changes of triangular silver nanoprisms (AgNPRs) in an immunoassay for the detection of carcinoembryonic antigen (CEA). In the second experiment, the device measured the aggregation of gold nanoparticles (AuNPs) in an aptamer-based assay for the detection of adenosine triphosphate (ATP). The results from the smart phone-based PNRP were consistent with those from commercial spectrophotometers, demonstrating that the smart phone-based PNRP enables accurate quantification of plasmonic nanosensors.

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