ALBERT

Description: Forests, Vol. 9, Pages 538: Recent Health and Safety Incident Trends Related to the Storage of Woody Biomass: A Need for Improved Monitoring Strategies Forests doi: 10.3390/f9090538 Authors: Sally Krigstin Suzanne Wetzel Nivatha Jayabala Christopher Helmeste Sebnem Madrali Joy Agnew Sylvain Volpe Self-heating fires, dust explosions and off-gassing during biomass storage are serious hazards which can have devastating consequences, resulting in worker fatalities and health impacts, as well as bioenergy plant destruction and complete loss of production. A compilation of incident reports involving biomass storage from 2000–2018 has revealed that these potential hazards continue to be a major concern in the bioenergy sector. Higher occurrence rates were found for incidents categorized as self-heating fires and fires of uncertain causes in recent years through our study of online reports. This paper highlights a critical need for improved safety protocols for bioenergy plant workers, detailed incident documentation and enhanced biomass monitoring strategies to drastically reduce the occurrence of threats associated with the storage of woody biomass. In order to manage the high risks associated with self-heating, a system for real-time monitoring of internal pile temperature was investigated. A monitoring system supplied by Braingrid Corporation was verified using embedded Tinytag thermologgers indicating that this methodology shows potential for preventing spontaneous combustion events by providing real time temperature data for superior pile management.

Description: Materials, Vol. 11, Pages 542: Quantifying Rock Weakening Due to Decreasing Calcite Mineral Content by Numerical Simulations Materials doi: 10.3390/ma11040542 Authors: Maria Wetzel Thomas Kempka Michael Kühn The quantification of changes in geomechanical properties due to chemical reactions is of paramount importance for geological subsurface utilisation, since mineral dissolution generally reduces rock stiffness. In the present study, the effective elastic moduli of two digital rock samples, the Fontainebleau and Bentheim sandstones, are numerically determined based on micro-CT images. Reduction in rock stiffness due to the dissolution of 10% calcite cement by volume out of the pore network is quantified for three synthetic spatial calcite distributions (coating, partial filling and random) using representative sub-cubes derived from the digital rock samples. Due to the reduced calcite content, bulk and shear moduli decrease by 34% and 38% in maximum, respectively. Total porosity is clearly the dominant parameter, while spatial calcite distribution has a minor impact, except for a randomly chosen cement distribution within the pore network. Moreover, applying an initial stiffness reduced by 47% for the calcite cement results only in a slightly weaker mechanical behaviour. Using the quantitative approach introduced here substantially improves the accuracy of predictions in elastic rock properties compared to general analytical methods, and further enables quantification of uncertainties related to spatial variations in porosity and mineral distribution.

Description: Remote Sensing, Vol. 10, Pages 315: Performance Assessment of Balloon-Borne Trace Gas Sounding with the Terahertz Channel of TELIS Remote Sensing doi: 10.3390/rs10020315 Authors: Jian Xu Franz Schreier Gerald Wetzel Arno de Lange Manfred Birk Thomas Trautmann Adrian Doicu Georg Wagner Short-term variations in the atmospheric environment over polar regions are attracting increasing attention with respect to the reliable analysis of ozone loss. Balloon-borne remote sensing instruments with good vertical resolution and flexible sampling density can act as a prototype to overcome the potential technical challenges in the design of new spaceborne atmospheric sensors and represent a valuable tool for validating spaceborne observations. A multi-channel cryogenic heterodyne spectrometer known as the TErahertz and submillimeter LImb Sounder (TELIS) has been developed. It allows limb sounding of the upper troposphere and stratosphere (10–40 km ) within the far infrared (FIR) and submillimeter spectral regimes. This paper describes and assesses the performance of the profile retrieval scheme for TELIS with a focus on the ozone ( O 3 ), hydrogen chloride ( HCl ), carbon monoxide ( CO ), and hydroxyl radical ( OH ) measured during three northern polar campaigns in 2009, 2010, and 2011, respectively. The corresponding inversion diagnostics reveal that some forward/instrument model parameters play important roles in the total retrieval error. The accuracy of the radiometric calibration and the spectroscopic knowledge has a significant impact on retrieval at higher altitudes, whereas the pointing accuracy dominates the total error at lower altitudes. The TELIS retrievals achieve a vertical resolution of ∼ 2–3 km through most of the stratosphere below the balloon height. Dominant water vapor ( H 2 O ) contamination and low abundances of the target species reduce the retrieval sensitivity at the lowermost altitudes measured by TELIS. An extensive comparison shows that the TELIS profiles are consistent with profiles obtained by other limb sounders. The comparison appears to be very promising, except for discrepancies in the upper troposphere due to numerical regularization. This study not only consolidates the validity of balloon-borne TELIS FIR measurements, but also demonstrates the scientific relevance and technical feasibility of terahertz limb sounding of the stratosphere.

Description: Water, Vol. 10, Pages 1226: Engineering Analysis of Plant and Fungal Contributions to Bioretention Performance Water doi: 10.3390/w10091226 Authors: Alex Taylor Jill Wetzel Emma Mudrock Kennith King James Cameron Jay Davis Jenifer McIntyre While the use of bioretention for stormwater management is widespread, data about the impacts of plants and microorganisms on long-term treatment efficacy remain region-specific. To help address this knowledge gap for the Pacific Northwest region of the United States, we installed twelve under-drained bioretention mesocosms built to Washington State Department of Ecology stormwater management standards in an urban watershed in Seattle, WA that included a busy portion of Interstate 5. Six mesocosms were planted with Pacific ninebark (Physocarpus capitatus) and six were inoculated with the wine cap mushroom (Stropharia rugoso-annulata) resulting in four replicated factorial treatments. Because region-specific studies must be mindful of the prevailing regulatory framework, all mesocosms used the Washington State Department of Ecology design standard soil: a blend of 60% sand and 40% compost by volume, despite the known leaching problems with high compost volume fraction soils. Five water quality sampling events over 15 months of continuous stormwater loading were analyzed for dozens of water quality parameters. Multiple linear regression analyses of treatment differences over the 400-day loading period illustrate that incorporating fungi into the wood mulch slowed the release of total and ortho-phosphorus from the bioretention soil; however net export of phosphorus from this compost rich media continued through 400 days of loading for all treatments. Multivariate ordination methods illustrate that time and temperature dramatically affect performance of this media, but the impact of planting and fungal inoculation had marginal detectible effects on overall water quality during the study timeframe. These results demonstrate that future studies of this media blend must plan for at least one year of nutrient and metal leaching before the time-dependent heterogenous variance introduced by these exports will no longer pose an obstacle to analysis of other performance changing factors. The results highlight important physical and chemical considerations for this media blend, and the opportunity for continued research on the use of fungal inoculated mulch application as a new ecological engineering tool for reducing phosphorus leaching from soils.

Description: Discrepancies in ozone retrievals in MIPAS channels A (685–970 cm−1) and AB (1020–1170 cm−1) have been a long-standing problem in MIPAS data analysis, amounting to an interchannel bias (AB–A) of up to 8 % between ozone volume mixing ratios in the altitude range 30–40 km. We discuss various candidate explanations, among them forward model and retrieval algorithm errors, interchannel calibration inconsistencies and spectroscopic data inconsistencies. We show that forward-modelling errors as well as errors in the retrieval algorithm can be ruled out as an explanation because the bias can be reproduced with an entirely independent retrieval algorithm (GEOFIT), relying on a different forward radiative transfer model. Instrumental and calibration issues can also be refuted as an explanation because ozone retrievals based on balloon-borne measurements with a different instrument (MIPAS-B) and an independent level-1 data processing scheme produce a rather similar interchannel bias. Thus, spectroscopic inconsistencies in the MIPAS database used for ozone retrieval are practically the only reason left. To further investigate this issue, we performed retrievals using additional spectroscopic databases. Various versions of the HITRAN database generally produced rather similar channel AB–A differences. Use of a different database, namely GEISA-2015, led to similar results in channel AB, but to even higher ozone volume mixing ratios for channel A retrievals, i.e. to a reversal of the bias. We show that the differences in MIPAS channel A retrievals result from about 13 % lower air-broadening coefficients of the strongest lines in the GEISA-2015 database. Since the errors in line intensity of the major lines used in MIPAS channels A and AB are reported to be considerably lower than the observed bias, we posit that a major part of the channel AB–A differences can be attributed to inconsistent air-broadening coefficients as well. To corroborate this assumption we show some clearly inconsistent air-broadening coefficients in the HITRAN-2008 database. The interchannel bias in retrieved ozone amounts can be reduced by increasing the air-broadening coefficients of the lines in MIPAS channel AB in the HITRAN-2008 database by 6 %–8 %.

Description: A new type of gas chimney exhibiting unconventional linear planform has been observed on 3D seismic data offshore Angola, and is termed Linear Chimneys. These chimneys occur in the shallow buried hemipelagic succession which was affected by syn-sedimentary remobilisation processes related to hydrocarbon migrations. Linear Chimneys are oriented parallel to the adjacent faults, within preferentially oriented tier-bound fault networks of diagenetic origin (also known as anisotropic Polygonal Faults, PFs) in the salt-deformational domain. These anisotropic PFs are parallel to salt-tectonic-related structures indicating their submission to horizontal stress perturbations generated by the latter. Only in anisotropic PF areas chimneys and their associated gas-related structures, e.g. methane-derived authigenic carbonates and pockmarks, show linear planforms. In areas without anisotropic PFs where the stress state is isotropic, gas expulsion structures of the same range of sizes exhibit circular geometry. In areas experiencing a transitional stress field, Linear Chimneys follow the trend of weak anisotropic PFs rather than the nearby tectonic structures. Therefore, the development of Linear Chimneys is interpreted to have been predominantly affected by the anisotropic stress field of PFs. The initiation of polygonal faulting formed 40 to 80m below the seafloor and predates Linear Chimneys. The majority of Linear Chimneys nucleated at the lower part of the PF tier below the impermeable, upper portion of PFs, where gas accumulation was facilitated by a regional impermeable barrier. The permeable part of polygonal fault-bound traps is evidenced by PF cells filled with gas. These PF gas traps restricted the leakage points of overpressured gas-charged fluids to occur along the lower portion of PFs and hence, controlling the nucleation sites of chimneys. Gas leaking along the lower portion of PFs pre-configured the spatial organisation of chimneys. Anisotropic stress fields of tectonic and polygonal faults couple with partial impermeability of PFs determined directions of gas migration, linear geometry of chimneys, long term migration pathways and successive leaking events. Methane-related carbonates that precipitated above Linear Chimneys inherited the same linear planform geometry, both structures record the timing of gas leakage, the orientation of palaeo stress and thus can be used as a tool of stress reconstruction in sedimentary successions.

Description: A new type of gas chimney exhibiting an unconventional linear planform is found. These chimneys are termed Linear Chimneys, which have been observed in 3-D seismic data offshore of Angola. Linear Chimneys occur parallel to adjacent faults, often within preferentially oriented tier-bound fault networks of diagenetic origin (also known as anisotropic polygonal faults, PFs), in salt-deformational domains. These anisotropic PFs are parallel to salt-tectonic-related structures, indicating their submission to horizontal stress perturbations generated by the latter. Only in areas with these anisotropic PF arrangements do chimneys and their associated gas-related structures, such as methane-derived authigenic carbonates and pockmarks, have linear planforms. In areas with the classic isotropic polygonal fault arrangements, the stress state is isotropic, and gas expulsion structures of the same range of sizes exhibit circular geometry. These events indicate that chimney's linear planform is heavily influenced by stress anisotropy around faults. The initiation of polygonal faulting occurred 40 to 80 m below the present day seafloor and predates Linear Chimney formation. The majority of Linear Chimneys nucleated in the lower part of the PF tier below the impermeable portion of fault planes and a regional impermeable barrier within the PF tier. The existence of polygonal fault-bound traps in the lower part of the PF tier is evidenced by PF cells filled with gas. These PF gas traps restricted the leakage points of overpressured gas-charged fluids along the lower portion of PFs, hence controlling the nucleation sites of chimneys. Gas expulsion along the lower portion of PFs preconfigured the spatial organisation of chimneys. Anisotropic stress conditions surrounding tectonic and anisotropic polygonal faults coupled with the impermeability of PFs determined the directions of long-term gas migration and linear geometries of chimneys. Methane-related carbonates that precipitated above Linear Chimneys inherited the same linear planform geometry, and both structures record the timing of gas leakage and palaeo-stress state; thus, they can be used as a tool to reconstruct orientations of stress in sedimentary successions. This study demonstrates that overpressure hydrocarbon migration via hydrofracturing may be energetically more favourable than migration along pre-existing faults.

Description: Discrepancies in ozone retrievals in MIPAS channels A (685–970 cm−1) and AB (1020–1170 cm−1) have been a long-standing problem in MIPAS data analysis, amounting to an inter-channel ozone bias (AB-A) of up to 8 % in the altitude range 30–40 km. We discuss various candidate explanations, among them forward model and retrieval algorithm errors, inter-channel calibration inconsistencies, and spectroscopic data inconsistencies. We show that forward modelling errors as well as errors in the retrieval algorithm can be ruled out as an explanation because the bias can be reproduced with an entirely independent retrieval algorithm (GEOFIT) relying on a different forward radiative transfer model. Instrumental and calibration issues can also be refuted as explanation because ozone retrievals based on balloon-borne measurements with a different instrument (MIPAS-B) and an independent level-1 data processing scheme produce a rather similar inter-channel bias. Thus spectroscopic inconsistencies are practically the only reason left. To further investigate this issue, we performed retrievals using various versions of the HITRAN spectroscopic database which, however, generally produce rather similar channel AB-A differences. Use of a different database, namely GEISA-2015, leads to similar results in channel AB, but to even higher ozone amounts for channel A retrievals, i.e. to a reversal of the bias. We show that the differences in MIPAS channel A retrievals result from about 13 % lower air-broadening coefficients of the strongest lines in the GEISA-2015 database. Since the errors in line intensity of the major lines used in MIPAS channels A and AB are reported to be considerably lower than the observed bias, we posit that a major part of the inter-channel differences can be attributed to inconsistent air-broadening coefficients as well. To corroborate this assumption we show some clearly inconsistent air-broadening coefficients in the HITRAN-2008 data base. The inter-band bias in retrieved ozone profiles can be reduced by, e.g., increasing the air-broadening coefficients of the lines in MIPAS band AB in the HITRAN-2008 database by 6–8 %.