Design and characterization of a semi-open dynamic chamber for measuring biogenic volatile organic compound (BVOC) emissions from plants

With the accumulation of data about biogenic volatile organic compound (BVOC) emissions from plants based on branch-scale enclosure measurements worldwide, it is vital to assure that measurements are conducted using well-characterized dynamic chambers with good transfer efficiencies and less disturbance on natural growing microenvironments. In this study, a self-made cylindrical semi-open dynamic chamber with a Teflon-coated inner surface was characterized both in the lab with standard BVOC mixtures and in the field with typical broadleaf and coniferous trees. The lab simulation with a constant flow of standard mixtures and online monitoring of BVOCs by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) revealed lower real-time mixing ratios and shorter equilibrium times than theoretically predicted due to wall loss in the chamber and that larger flow rates (shorter residence times) can reduce the adsorptive loss and improve the transfer efficiencies. However, even when flow rates were raised to secure residence times of less than 1 min, transfer efficiencies were still below 70 % for heavier BVOCs like α-pinene and β-caryophyllene. Relative humidity (RH) impacted the adsorptive loss of BVOCs less significantly when compared to flow rates, with compound-specific patterns related to the influence of RH on their adsorption behaviour. When the chamber was applied in the field to a branch of a Mangifera indica tree, the ambient–enclosure temperature differences decreased from 4.5±0.3 to 1.0±0.2 ∘C and the RH differences decreased from 9.8 ± 0.5 % to 1.2±0.1 % as flow rates increased from 3 L min−1 (residence time ∼4.5 min) to 15 L min−1 (residence time ∼0.9 min). At a medium flow rate of 9 L min−1 (residence time ∼1.5 min), field tests with the dynamic chamber for Mangifera indica and Pinus massoniana branches revealed enclosure temperature increase within +2 ∘C and CO2 depletion within −50 ppm when compared to their ambient counterparts. The results suggested that substantially higher air circulating rates would benefit by reducing equilibrium time, adsorptive loss, and the ambient–enclosure temperature and RH differences. However, even under higher air circulating rates and with inert Teflon-coated inner surfaces, the transfer efficiencies for monoterpene and sesquiterpene species are not so satisfactory, implying that emission factors for these species might be underestimated if they are obtained by dynamic chambers without certified transfer efficiencies and that further efforts are needed for field measurements to improve accuracies and narrow the uncertainties of the emission factors.

Physicochemical Properties of Torrefied and Pyrolyzed Food Waste Biochars as Fuel: A Pilot-Scale Study

Food waste is an important constituent of municipal solid waste, and research has been conducted to develop various methods for treating food waste and recycling it (e.g., fuel, landfilling, composting, conversion into animal feed, drying, and carbonization). Among these, the drying and carbonization techniques can change food waste into fuel; however, they need more energy than fermentation and anaerobic digestion procedures. In this study, we investigated the physicochemical properties of food waste biochar produced under torrefaction (270 °C) and pyrolysis (450 °C) conditions to establish its applicability as fuel by comparing temperatures, residence times, and conditions before and after demineralization. The higher heating value increased after the demineralization process under both temperature conditions (270 °C and 450 °C), and the chlorine level was lower at 270 °C temperature demineralization than at 450 °C. During the demineralization process, Na and K were better removed than Ca and Mg. Additionally, Cr, Hg, Cd, and Pb levels were lower than those according to the European Union and Korean domestic bio-SRF recovered fuel criteria, confirming the applicability of biochar as fuel.

Single-molecule sizing through nano-cavity confinement

An approach relying on nano-cavity confinement is developed in this paper for the sizing of nanoscale particles and single biomolecules in solution. The approach, termed nano-cavity diffusional sizing (NDS), measures particle residence times within fluidic nano-cavities to determine their hydrodynamic radii. Using theoretical modelling and simulation, we show that the residence time of particles within nano-cavities above a critical timescale depends on the diffusion coefficient of the particle, which allows estimation of the particle's size. We demonstrate this approach experimentally through measurement of particle residence times within nano-fluidic cavities using single-molecule confocal microscopy. Our data show that the residence times scale linearly with the sizes of nanoscale colloids, protein aggregates and single DNA oligonucleotides. NDS thus constitutes a new single molecule optofluidic approach that allows rapid and quantitative sizing of nanoscale objects for potential application in nanobiotechnology, biophysics, and clinical diagnostics.

Determining the impact of flow velocities on reactive processes associated with Enterococcus faecalis JH2-2

This study focuses on the impact of infiltration rates on colloidal transport and reactive processes associated with E. faecalis JH2-2 using water-saturated sediment columns. The infiltration rates influence the physical transport of bacteria by controlling the mean flow velocity. This, in turn, impacts biological processes in pore water owing to the higher or lower residence time of the bacteria in the column. In the present study, continuous injection of E. faecalis (suspended in saline water with varying conditions of dissolved oxygen and nutrient concentrations) into a lab-scale sediment column was performed at flow velocities of 0.02 cm min−1 and 0.078 cm min−1, i.e., at residence times of 1–5 hours. The impact of residence times on reactive processes is significant for field scale setups. A process-based model with a first-order rate coefficient for each biological process was fitted for each obtained condition-specific dataset from the experimental observations (breakthrough curves). The coefficients were converted to a dimensionless form to facilitate the comparison of biological processes. These results indicate that the processes of attachment and growth were flow-dependent. The growth process in the absence of dissolved oxygen was the most dominant process, with a Damkoehler number of approximately 48.

210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export

Estimating the particulate organic carbon (POC) export flux from the upper ocean is fundamental for understanding the efficiency of the biological carbon pump driven by sinking particles in the oceans. The downward POC flux from the surface ocean based on 210Po-210Pb disequilibria in seawater samples from the western North Pacific Ocean (w-NPO) was measured in the early summer (May-June) of 2018. All the profiles showed a large 210Po deficiency relative to 210Pb in the euphotic zone (0–150 m), while this 210Po deficiency vanished below ∼500 m (with 210Po/210Pb ∼1 or > 1). A one-dimensional steady-state irreversible scavenging model was used to quantify the scavenging and removal fluxes of 210Po and 210Pb in the euphotic zone of the w-NPO. In the upper ocean (0–150 m), dissolved 210Po (D-Po) was scavenged into particles with a residence time of 0.6–5.5 year, and the 210Po export flux out of the euphotic zone was estimated as (0.33–3.49) × 104 dpm/m2/year, resulting in a wide range of particulate 210Po (P-Po) residence times (83–921 days). However, in the deep ocean (150–1,000 m), 210Po was transferred from the particulate phase to the dissolved phase. Using an integrated POC inventory and the P-Po residence times (Eppley model) in the w-NPO euphotic zone, the POC export fluxes (mmol C/m2/d) varied from 0.6 ± 0.2 to 8.8 ± 0.4. In comparison, applying the POC/210Po ratio of all (>0.45 μm) particles to 210Po export flux (Buesseler model), the obtained POC export fluxes (mmol C/m2/d) ranged from 0.7 ± 0.1 to 8.6 ± 0.8. Both Buesseler and Eppley methods showed enhanced POC export fluxes at stations near the continental shelf (i.e., Luzon Strait and the Oyashio-Kuroshio mixing region). The Eppley model-based 210Po-derived POC fluxes agreed well with the Buesseler model-based fluxes, indicating that both models are suitable for assessing POC fluxes in the w-NPO. The POC export efficiency was < 15%, suggesting a moderate biological carbon pump efficiency in the w-NPO. These low export efficiencies may be associated with the dominance of smaller particles and the processes of degradation and subsequent remineralization of these small particles in the euphotic zone of oligotrophic regions in the w-NPO.

An integrated metagenomic and metabolite profiling study of hydrocarbon biodegradation and corrosion in navy ships

Naval vessels regularly mix fuel and seawater as ballast, a practice that might exacerbate fuel biodegradation and metal biocorrosion. To investigate, a metagenomic characterization and metabolite profiling of ballast from U.S. Navy vessels with residence times of 1-, ~20-, and 31 weeks was conducted and compared with the seawater used to fill the tanks. Aerobic Gammaproteobacteria differentially proliferated in the youngest ballast tank and aerobic-specific hydrocarbon degradation genes were quantitatively more important compared to seawater or the other ballast tanks. In contrast, the anaerobic Deltaproteobacteria dominated in the eldest ballast fluid with anaerobic-specific hydrocarbon activation genes being far more prominent. Gene activity was corroborated by detection of diagnostic metabolites and corrosion was evident by elevated levels of Fe, Mn, Ni and Cu in all ballast samples relative to seawater. The findings argue that marine microbial communities rapidly shift from aerobic to anaerobic hydrocarbonoclastic-dominated assemblages that accelerate fuel and infrastructure deterioration.

Anomalous Stochastic Transport of Particles with Self-Reinforcement and Mittag–Leffler Distributed Rest Times

We introduce a persistent random walk model for the stochastic transport of particles involving self-reinforcement and a rest state with Mittag–Leffler distributed residence times. The model involves a system of hyperbolic partial differential equations with a non-local switching term described by the Riemann–Liouville derivative. From Monte Carlo simulations, we found that this model generates superdiffusion at intermediate times but reverts to subdiffusion in the long time asymptotic limit. To confirm this result, we derived the equation for the second moment and find that it is subdiffusive in the long time limit. Analyses of two simpler models are also included, which demonstrate the dominance of the Mittag–Leffler rest state leading to subdiffusion. The observation that transient superdiffusion occurs in an eventually subdiffusive system is a useful feature for applications in stochastic biological transport.

Crystal Specific Constraints on Subvolcanic Processes Preceding Eruptions at Mt Taranaki, New Zealand

<p>Andesitic magmas are the product of a complex interplay of processes including fractional crystallisation, crystal accumulation, magma mixing and crustal assimilation. Recent studies have suggested that andesitic rocks are in many cases a complex mixture of a crystal cargo and melts with more silicic compositions than andesite. In situ glass- and mineral-specific geochemical techniques are therefore key to unravelling the processes and timescales over which andesitic magmas are produced, assembled and transported to the surface. To this end, this thesis presents a detailed in situ glass- and mineral-specific study of six Holocene eruptions (Kaupokonui, Maketawa, Inglewood a and b, and Korito) at Mt Taranaki to investigate the petrogenetic processes responsible for producing these sub-plinian eruptions at this long-lived (130 000 yr) andesitic volcano. Mt Taranaki is an andesitic stratovolcano located on the west coast of New Zealand’s North Island and as such it is distinct from the main subduction related volcanism. Crystal-specific major and trace element data were combined with textural analysis and quantitative modelling of intensive magmatic parameters and crystal residence times to identify distinct mineral populations and constrain the magmatic histories of the crystal populations. Least-squares mixing modelling of glass and phenocryst compositions demonstrates that the andesitic compositions of bulk rock Mt Taranaki eruptives results from mixing of a daciticrhyolitic melt and a complex crystal cargo (plagioclase, pyroxene, amphibole) that crystallised from multiple melts under a wide range of crustal conditions. Magma mixing of compositionally similar end members that mix efficiently also occurred beneath Mt Taranaki, and as such only produced prominent disequilibrium textures in a small proportion of the minerals in the crystal cargo. The chemistry of the earliest crystallising amphibole indicates crystallisation from an andesitic-dacitic melt at depths of ca. 20-25 km, within the lower crust. Magmas then ascended through the crust relatively slowly via a complex magmatic plumbing system. However, most of the crystal cargo formed by decompression-driven crystallisation at depth so 6-10 km, as is indicated by the dominance of oscillatory zoning and the equilibrium obtained between mineral rims and the host glasses. Taranaki magmas recharge on timescales of 1000-2000 yrs. The eruptions investigated here provide a snapshot of the end of one cycle and the beginning of another. The younger Kaupokonui and Maketawa eruptions (ca. 2890 - <1950 yr BP) are the least evolved magmas, record a stronger mixing signal in the crystal cargo, and are volumetrically smaller than the earlier Inglewood a and b and Korito eruptions (ca. 4150-3580 yr BP). The Kaupokonui and Maketawa eruptions may reflect arrival of a new pulse of magma from the lower crust, or that these are early eruptions within a recharge sequence, which have not had as much time to further differentiate and evolve as the earlier Inglewood a and b and Korito eruptions that represent the end of a magma recharge cycle. One of the six investigated eruptions was identified to come from Fantham’s Peak on the basis of its distinctive glass and mineral chemistry and petrology. Glass trace element data indicate that this eurption’s magmatic system was distinct from that of the other main vent Holocene eruptions investigated in this study. Crystal residence times were investigated using Fe-Mg interdiffusion in clinopyroxene and indicate that magma bodies stall in upper crustal storage chambers for timescales of a few months to years. The younger eruptions of the least evolved magmas with the strongest mixing signal return the shortest residence times, which may indicate that magma mixing events occurring a few months before eruption may have been the trigger for these eruptions at Mt Taranaki. Amphibole geospeedometry for these eruptives reveal rapid magma transport from depths of 6-10 km to the surface on timescales of < 1 week.</p>