Conventional and microwave pyrolysis remediation of crude oil contaminated soil

The Nigerian economy has relied heavily on crude oil production since independence in 1960. As a consequence, it has seen an influx of multinational petroleum companies with oil exploration and associated activities having significant environmental impacts, particularly oil leakage and spillage into soil and the overall degradation of the ecosystem in the Niger Delta area. This study aims to find a viable solution to the remediation of polluted soil by comparing two thermal remediation techniques, namely microwave pyrolysis and traditional pyrolysis, which has been investigated using a Gray-King retort. The polluted soil was first examined to ascertain the distribution of the soil organic carbon (SOC) with 78% found to be solvent extractable in dichloromethane/methanol, while 95 % was thermally labile and removed under hydropyrolysis (HyPy) conditions at 550 °C. The remaining 5 % of the SOC was composed of a recalcitrant residue being defined as the black or stable polyaromatic carbon fraction. The solvent extractable organic matter (EOM) was then further separated into the maltene (free phase) and asphaltene (bound phase) fractions together for comparison with a sample of Nigerian crude oil provided by the Shell Petroleum Development Company (SPDC), Nigeria. The Nigerian crude oil is a light crude oil with the percentage of maltene (95.2 %) was far higher than the asphaltene (4.8 %). A closer margin was observed in the percentage between the maltene (88.3 %) and asphaltene (11.7 %) in the soil EOM due to biodegradation. The biomarker profile of the EOM was compared with that of a Nigerian crude oil to confirm that the EOM contains the crude oil in the soil. Their biomarker profiles revealed that the source inputs were terrigenous from deltaic settings, of Late Upper Cretaceous age and deposited under oxic conditions. Oleanane (a pentacyclic triterpene, abundant in oils from the Niger Delta) was present in both the crude oil and EOM and the hopane and the sterane distributions (m/z 191 and m/z 217 respectively) were similar in every respect, which indicates that the probable source of the pollutant crude oil in the soil is similar in composition to the Nigerian crude oil. Accordingly, the polluted soil was treated with microwave pyrolysis and Gray-King pyrolysis to remove the crude oil pollutant. The maximum average recovered products from the thermal remediation process with Gray-King pyrolysis is 99.4 % TOC and maximum crude oil pollutant removed by Gray-King pyrolysis was 85.3 % TOC with maximum oil recovery of 70 % TOC from all the different treatment conditions, while the shortest treatment time condition gave the lowest gas yield of 10.2 % TOC. This implies that 100 % removal with respect to EOM and 89 % removal with respect to HyPy as discussed above. Furthermore, the polluted soil was also treated with microwave pyrolysis with maximum pollutant removal of 77 % TOC, which is 98.7 % removal with respect to EOM and 81 % with respect to HyPy. In conclusion, Gray-King pyrolysis removed more of the soil organic carbon than microwave pyrolysis, but the latter does have advantages regarding operability and greater output within a short treatment time

Organic and isotopic geochemistry of source-rocks and crude oils from the East Sirte Basin (Libya)

The Sirte Basin is a major oil producing area in Libya, but the understanding of the processes that have led to the petroleum accumulation is still limited. Exploration studies of this area have shown that the oils are mixtures of several charges and may be from different source rocks. The main aims of this thesis are to improve our understanding of the petroleum accumulation history in the East Sirte Basin.Biomarker ratios, together with stable carbon (δ[superscript]1[superscript]3C) and hydrogen (δD) isotopic compositions of individual hydrocarbons have been applied to 24 crude oils from the East Sirte Basin to delineate their sources and respective thermal maturities. The crude oil samples are divided into two main families (A and B) based on differences in source inputs and thermal maturity. Using source-specific biomarker parameters based on pristane/phytane (Pr/Ph), hopane/sterane ratios, dibenzothiophene (DBT) / phenanthrene (P), Pr/n-C[subscript]1[subscript]7, Ph/n-C[subscript]l[subscript]8 and the distribution of tricyclic and tetracyclic terpanes, family B oils are ascribed a marine source rock deposited under sub-oxic conditions, whereas family A oils have a more terrestrial source affinity. This source classification is supported by the stable carbon isotopic compositions (δ[superscript]1[superscript]3C) of the n-alkanes. Family A oils were found to be more mature based on differences between the stable hydrogen isotopic compositions (δD) of Pr and Ph and the n-alkanes, as well as the δ[superscript]1[superscript]3C values of n-alkanes.Within a complex geological setting several potential source rocks have been recognised, ranging in age from Precambrian to Eocene. Biomarker ratios, together with δ[superscript]1[superscript]3C and δD of individual hydrocarbons have been applied to 21 source rock extracts from the East Sirte Basin to establish their respective thermal maturity and palaeoenvironmental conditions of deposition. Rock Eval pyrolysis data obtained from the source rocks of the Sirte, Tagrifet, Rakb, Rachmat, Bahi and Nubian Formations show that the organic matter (OM) is mainly dominated by a Type II/III kerogen. Vitrinite reflectance (% R[subscript]o range: 0.46 – 1.38) data support variations in thermal maturity and indicate mature to post mature rocks of Sirte and Rachmat Formations and early to mid stage maturities for the rest of the formations. The Sirte Formation in the studied area was found to be relatively more thermally mature than the Tagrifet, Rakb, Rachmat, Bahi, and Nubian Formations, reflected by δD of Pr and Ph (less depleted in D).Various unusual steroid biomarkers in the oils and East Sirte source-rocks were identified by gas chromatography- mass spectrometry (GC-MS) and GC- metastable reaction monitoring (MRM) mass spectrometry. These included 24-norcholestanes, dinosteranes, 4α-methyl-24-ethylcholestanes and triaromatic steroids. Diatoms, dinoflagellates and/or their direct ancestors are the proposed sources of these components. These biomarker parameters have been used to establish a Mesozoic oil-source correlation of the East Sirte Basin. This is consistent with the presence of dinoflagellate cysts in the Nubian Formation of Lower Cretaceous age

Determination of abundance, composition, and sources of carbonaceous components within particulate matter from urban environments within the UK

Airborne ambient particulate matter (PM) has detrimental effects on human health and the environment and its concentrations are usually higher in urban areas. The carbonaceous component is a major constituent of particulate matter with an aerodynamic diameter of ≤2.5 μM (PM₂.₅). It comprises of black carbon (BC) and many individual species of organic compounds such as polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. Despite this importance, BC remains a poorly quantified and poorly characterised component of PM, relative to other PM fractions. The aims of this work were therefore to: 1) Determine the abundance and spatiotemporal trends of airborne BC in Glasgow, Scotland’s largest city. 2) Obtain samples of airborne PM from Glasgow and elsewhere in the UK, quantify the concentrations of PM-bound PAHs and estimate the associated health risks of exposure to these PM-bound PAHs. 3) Develop hydropyrolysis (hypy) methodology to isolate BChypy from airborne ambient PM, obtaining BC/Total Carbon % (BC/TC%) measurements. 4) Undertake source apportionment of the carbonaceous components (PAHs, n-alkanes, TC and BC) of PM from Glasgow and elsewhere. Radiocarbon (¹⁴C) analysis and delta carbon-13 (δ¹³C) were to be used for source apportionment of TC and BC. Principal component analysis (PCA) were to be used to determine sources of PAHs and n-alkanes. To determine the abundance and spatiotemporal trends in Glasgow, two portable microaethalometer instruments were used. These were calibrated through co-location against the UK BC network aethalometer at the Glasgow Townhead urban background site. In four Glasgow wards, one microaethalometer was placed at a fixed location whilst the other was used in mobile measurements to determine the relative and absolute spatiotemporal variations in BC. BC increment concentrations calculated through subtracting the background BC concentrations from Glasgow Townhead site and absolute concentrations exhibited spatial variation across the wards. The ‘mobile’ measurements showed the city centre to be a hotspot whilst Baillieston, a residential ward on the outskirts of the city, had the lowest BC increments. Population, population densities and socio-economic data could be used as valuable BC indicators to determine other BC hotspots in Glasgow and beyond. Temporally, median BC increments were significantly higher in mid-morning (10:30 – 11:30) than earlier morning (08:00 – 09:00). However, absolute BC concentrations had the opposite trend showing that background BC contributes highly to morning BC concentrations. This suggests that use of BC increments rather than BC concentrations can help improve understanding of local pollution events by removing background influences. BC increments were correlated strongly with NOx concentrations and bus/heavy goods vehicles average daily traffic counts at the sampling sites. This showed that Glasgow City Council could focus local air quality measures towards reducing emissions from buses and HGVs. Samples of PM2.5 were collected from two sites in Glasgow using a low volume air sampler: GLA-HH (University Avenue, Hillhead), GLA-CC (George Street, City). Samples of PM2.5, and of particulate matter with an aerodynamic diameter of ≤10 μM (PM10), from GLA-KS (Hope Street, City) were provided by Ricardo, an environmental consulting services company. Samples were also collected from a comparison site, an urban background site located in Manchester Fallowfield Campus (MAN-FF). The GLA-KS and MAN-FF samples were collected by high volume air samplers. For n-alkane and PAH analysis, samples were extracted by accelerated solvent extraction (ASE) using hexane and acetone, and then compound groups were separated using column chromatography. GLA-KS benzo(a)pyrene (BaP) concentrations exceeded the UK National Air Quality Objective (NAQO) of 0.25 ng m⁻³ and were close to the EU Fourth Air Quality Daughter Directive (FAQDD) limit value of 1 ng m⁻³. This implied that inhalation of PM2.5 from GLA-KS could be associated with potential health effects such as lung cancer. BaP concentrations in the MAN-FF samples did not exceed the NAQO or FAQDD values, suggesting that suburban areas had lower associated health risks than inner-city areas. The increased lung cancer risk through inhalation (ILCRᵢₙₕ) was calculated for PM-bound PAHs. The ILCRᵢₙₕ using the World Health Organization IUR₈ₐₚ value resulted in ILCRᵢₙₕ of 2.09 x 10⁻⁴ for GLA-KS(PM₂.₅) and 4.60 x 10⁻⁵ for GLA-KS(PM₁₀). This equated to 209 excess lung cancer cases per 1,000,000 people for PM₂.₅ and 46 excess lung cancer cases per 1,000,000 people for PM₁₀. When applied to the Anderston, City and Yorkhill ward population this translated to 6 excess annual cases of lung cancer, assuming continuous and homogenous exposure of inhabitants. This shows that health risks posed to those living in Anderston, City and Yorkhill ward is not negligible and should be improved through PM₂.₅ reductions. The hypy methodology was tested on various different materials. Purchased aerosol and dust standards (NIST 1649b Urban Dust, NIST 1648a Urban PM, BCR-723 Road dust and ERMCZ100 Fine Dust PM₁₀-like) were used in the study. Two of these materials represented urban aerosols (NIST 1649b and 1648a), and the other two materials (BCR-723 road dust and ERMCZ100 Fine Dust) represented aerosols with dominant vehicular emission sources as they were collected from traffic tunnels. An in-house road dust sample from Glasgow Hillhead was collected for analysis. Materials that represented end members of BC were also used. NIST 2975 diesel PM was used to represent high BC concentrations, whilst in-house charred biomass materials were used to represent lower BC concentrations. A purchased lignite material was used to represent a material with low BC content. Hypy successfully determined BC/TC% in materials that contain low, moderate and high BC contents. As expected the BC/TC% of NIST 2975 Diesel PM was around 100 %BC/TC, for the lignite material (BZ) it was around 2 %BC/TC. The biomass materials showed variability with BT/TC% of 16 % (DB) and 63 % (EB). The urban aerosols had similar BC/TC% (25 – 28 %). The road dusts had different BC/TC% due to different sampling site characteristics (14 – 41 %). The variability between replicates was extremely low with a maximum standard deviation of 5.3 %BC/TC and standard error of 1.3 %BC/TC across all materials. The BC/TC% for NIST 1649b (28 %BC/TC) was in agreement with other hypy-derived BC/TC% reported in the literature. A method was then developed for the use of hypy on airborne ambient PM for subsequent 14C analysis for source apportionment. Airborne ambient PM from two sites in Glasgow (Glasgow City Centre GLA-CC, and Glasgow Hillhead GLA-HH) and Fallowfield Manchester (MAN-FF) underwent 14C analysis for both TC and BC components. The results for the percentage modern carbon (%MC) for the TC were compared to other UK sites. The MC% to percentage fossil carbon (%FC), (%MC:%FC), proportions in TC sample for GLA-CC and GLA-HH were 46%:54% showing dominant fossil sources. Whilst for MAN-FF the %MC:%FC proportion was 63%:37%, hence exhibiting dominant modern carbon sources. Due to COVID-19 comparisons with other UK sites did not represent source apportionments for business-as-usual scenarios. The %MC (TC) followed this order: Auchencorth Moss > London Honor Oak Park > Chilbolton Observatory > Manchester Fallowfield > Glasgow Hillhead > Glasgow City Centre. Auchencorth Moss, a rural background site, had the highest proportion of modern carbon sources and Glasgow City Centre had the highest proportion of fossil carbon sources. The PAH and n-alkane and PAH sources were in agreement with those %MC (TC) for GLA-CC and GLA-HH as fossil fuel combustion sources were dominant sources according to source categorisations from PAH diagnostic ratios (PAH DRs) and carbon preference index (CPI) for n-alkanes. Principal component analysis showed that the variance in PAH and n-alkane concentrations could be explained by two principal components (PC), PC 1 (79.6 % of the variance) and PC 2 (20.1 % of the variance). These components represented diesel and wood combustion emissions (PC 1) and vehicular emissions (direct and indirect) (PC 2). The n-alkane distributions showed the presence of epicuticular wax n-alkanes (C29, C31 and C33) suggesting biogenic vegetative detritus sources in GLA-KS samples, with the possibility of regionally transported biomass combustion PM-bound PAHs. The n-alkanes showing odd/even carbon preference in MAN-FF differed from GLA-KS, suggesting different sources of epicuticular waxes. BCₕᵧₚᵧ was successfully isolated for urban aerosols and dust materials. The NIST 1649b %MC (BCₕᵧₚᵧ) of 6 %MC was in agreement with previous studies. BCₕᵧₚᵧ was then isolated for MAN-FF and GLA-HH samples. The reported %MC (BCₕᵧₚᵧ) was 24 % for GLA-HH and 20 – 25 % for MAN-FF. The two replicates of MAN-FF showed a good level of precision both yielding 25 %MC (BCₕᵧₚᵧ). The sources of carbonaceous components from GLA-HH and MAN-FF therefore dominantly fossil carbon. However, the ¹⁴C was higher than urban aerosol materials (6 – 12 %MC) and reported values in the literature for a UK site, Birmingham (11 % average %MC). This shows that the modern nature of BC has increased due to decreasing fossil fuel combustion emissions and an increase in biomass combustion sources

Conventional and microwave pyrolysis remediation of crude oil contaminated soil

The Nigerian economy has relied heavily on crude oil production since independence in 1960. As a consequence, it has seen an influx of multinational petroleum companies with oil exploration and associated activities having significant environmental impacts, particularly oil leakage and spillage into soil and the overall degradation of the ecosystem in the Niger Delta area. This study aims to find a viable solution to the remediation of polluted soil by comparing two thermal remediation techniques, namely microwave pyrolysis and traditional pyrolysis, which has been investigated using a Gray-King retort. The polluted soil was first examined to ascertain the distribution of the soil organic carbon (SOC) with 78% found to be solvent extractable in dichloromethane/methanol, while 95 % was thermally labile and removed under hydropyrolysis (HyPy) conditions at 550 °C. The remaining 5 % of the SOC was composed of a recalcitrant residue being defined as the black or stable polyaromatic carbon fraction. The solvent extractable organic matter (EOM) was then further separated into the maltene (free phase) and asphaltene (bound phase) fractions together for comparison with a sample of Nigerian crude oil provided by the Shell Petroleum Development Company (SPDC), Nigeria. The Nigerian crude oil is a light crude oil with the percentage of maltene (95.2 %) was far higher than the asphaltene (4.8 %). A closer margin was observed in the percentage between the maltene (88.3 %) and asphaltene (11.7 %) in the soil EOM due to biodegradation. The biomarker profile of the EOM was compared with that of a Nigerian crude oil to confirm that the EOM contains the crude oil in the soil. Their biomarker profiles revealed that the source inputs were terrigenous from deltaic settings, of Late Upper Cretaceous age and deposited under oxic conditions. Oleanane (a pentacyclic triterpene, abundant in oils from the Niger Delta) was present in both the crude oil and EOM and the hopane and the sterane distributions (m/z 191 and m/z 217 respectively) were similar in every respect, which indicates that the probable source of the pollutant crude oil in the soil is similar in composition to the Nigerian crude oil. Accordingly, the polluted soil was treated with microwave pyrolysis and Gray-King pyrolysis to remove the crude oil pollutant. The maximum average recovered products from the thermal remediation process with Gray-King pyrolysis is 99.4 % TOC and maximum crude oil pollutant removed by Gray-King pyrolysis was 85.3 % TOC with maximum oil recovery of 70 % TOC from all the different treatment conditions, while the shortest treatment time condition gave the lowest gas yield of 10.2 % TOC. This implies that 100 % removal with respect to EOM and 89 % removal with respect to HyPy as discussed above. Furthermore, the polluted soil was also treated with microwave pyrolysis with maximum pollutant removal of 77 % TOC, which is 98.7 % removal with respect to EOM and 81 % with respect to HyPy. In conclusion, Gray-King pyrolysis removed more of the soil organic carbon than microwave pyrolysis, but the latter does have advantages regarding operability and greater output within a short treatment time

Experimentelle Simulation der Expulsion von Kohlenwasserstoffen

Investigating generation, expulsion and primary migration usually suffers from inadequate methodologies, failing in the provision of natural conditions, prevailing during the genesis of oil and gas. Destructive sample preparation, inappropriate pressure regimes and pyrolysis in closed mode and/or in the absence of water caused results not representative for natural processes. To overcome these limitations, a newly designed apparatus was developed and built, capable to perform pyrolysis experiments with intact rock samples under pressure regimes, prevailing during catagenesis. In detail, lithostatic (or overburden-) pressures and hydrostatic (or pore-) pressures, corresponding to 3000 m depth and beyond, can be simulated by this apparatus, the “Expulsinator” device. Additionally, the experiments are conducted as hydrous, semi-open pyrolysis, allowing the time-based sampling of the expelled products. Thus, generation/expulsion profiles are generated for each investigated source-rock. Comparison of generation and expulsion efficiency of the Expulsinator with established pyrolysis methodologies (MSSV, HyPy, Rock Eval and closed small vessel pyrolysis (CSVP)) reveals striking differences: Expulsinator experiments yielded more bitumen and released lower gas amounts than classic pyrolysis. This is caused by secondary alteration of products in case of classic pyrolysis, e.g. oil to gas cracking at higher temperatures and polymerization to pyrobitumen. The open setup of the Expulsinator experiments prevents successfully secondary alteration, increasing the liquid product yields and lowering the gas formation. This is mirrored in TOC conversion rates as well: Expulsinator conversion exceeds 81 %, whereas those of hydrous CSVP remains at 65 %. Further, interactions between kerogen, bitumen, pyrobitumen and pyrite are reduced in case of Expulsinator experiments. In contrast, CSVP experiments residues show enrichment of nitrogen and oxygen and depletion of sulphur, indicating intense interaction between the mentioned components. Investigating the impact of catagenesis onto the yields and composition of expelled products was carried out by a stepwise experimental setup, simulating burial depths of ~2000 m, ~2500 m and 3000 m, implementing overburden pressures from 600 bar to 900 bar and hydrostatic pressures from 200 bar to 300 bar. Each experiment step shows a distinct expulsion maximum of liquid hydrocarbons, reaching the total maximum at 3000 m. Confrontation of Expulsinator results with comparative CSVP and MSSV experiments reveal expulsion and primary migration effects onto the n-alkane distribution in dependence of maturation and subsidence. An n-alkane increase towards larger molecular size with ongoing expulsion is associated with molecular size controlled retention effects. The expulsion progress is mirrored in trends of isoprenoid-ratios (pristane vs. phytane) and isoprenoid – n-alkane-ratios (pristane vs. n-C17), caused mainly by generation controlled effects. However, both ratios qualify as expulsion indicator, taking into account generation and expulsion are concurrent processes. Generation/expulsion classification is done with eight different source-rocks (two type-I, type-II (-I/II), type-IIS and type-III kerogens, each) with different lithologies, using the catagenesis experiment setup described above. Again, formation of pyrobitumen shows to affect the maturity assessment of the source-rock, increasing the measured Tmax in case of kerogen type-I samples, but decreasing the measured value for type-II and –IIS kerogens. Type-III kerogen shows earliest onset of generation, followed by type-IIS and –II kerogen and type-I kerogen with the latest generation onset. The early generation and the concomitant high expulsion rate, observed for type-III kerogen, is contrasted by results of natural systems where this kerogen type usually shows very low expulsion rates. The Expulsinator setup provides excellent expulsion conditions, leading to early release of generated hydrocarbons. In contrast, accumulation within the kerogen pore space and subsequent condensation to solid bitumen leads to low generation and expulsion in natural systems. Differences between the generation/expulsion profiles of the different source-rocks are not only caused by the nature of the organic matter, but the lithology of the rock sample as well. Sturdy lithologies with very high pressure resistance and low permeability lithologies show lowered expulsion efficiency. An increase of the CO2-yields with increasing temperatures and pressures was observed for lithologies with high inorganic carbon content.Die Untersuchung von Öl- und Gas Expulsion und Migration wurde bisher durch unzureichende Methodiken erschwert, da Bedingungen, die während der Bildung freier Kohlenwasserstoffe vorherrschen, zumeist nicht oder nur teilweise durch diese Methodiken simuliert werden. Destruktive Probenvorbereitung, unzureichende Druckregime und Pyrolyse in geschlossenen Systemen und/oder in Abwesenheit von Wasser entsprechen nicht den Bedingungen natürlicher Prozesse. Um eine naturnahe Simulation der Generierung und Freisetzung von Öl und Gas zu ermöglichen, wurde im Rahmen dieser Arbeit eine Apparatur entwickelt, der „Expulsinator“, der eine wässrige Pyrolyse mit einem intakten Erdöl-Muttergestein unter Druckbedingungen durchführen kann, die während der Katagenese vorherrschen. Im Einzelnen ist es möglich, lithostatische und hydrostatische Drücke (oder Porendruck) bis zu einer Tiefe von 3000 m und darüber hinaus zu simulieren. Die wässrige Pyrolyse wird in einem semi-offenen Modus durchgeführt, was eine zeitbasierte Beprobung der freigesetzten Produkte ermöglicht. Dadurch können individuelle Generierungs-/Expulsions-Profile für jedes untersuchte Muttergestein erstellt werden. Ein Vergleich der Generierungs- und Expulsionseffizienz der Expulsinator-Versuche mit den Ergebnissen etablierter Pyrolyse-Methodiken (MSSV, HyPy, Rock Eval und closed small vessel pyrolysis (CSVP)) offenbart große Unterschiede. So wurden, verglichen zu klassischer Pyrolyse, durch Expulsinator-Versuche wesentlich größere Mengen an Bitumen generiert, bei gleichzeitig niedrigeren Gasmengen. Als Ursache werden sekundäre Abbaureaktionen gesehen, die im Falle der klassischen Pyrolysemethoden verstärkt zur Öl-zu-Gas Aufspaltung bei höheren Pyrolysetemperaturen und Polymerisation zu Pyrobitumen führen. Das offene Verfahren, das beim Expulsinator zur Anwendung kommt, verhindert dagegen sekundäre Reaktionen, was die Ausbeute flüssiger Produkte erhöht und gleichzeitig die Gasgenerierung reduziert, welches ebenfalls durch TOC Umwandlungsraten bestätigt wird: Während die Umwandlungsrate des Expulsinator-Versuchs 81 % übersteigt, erreicht die wässrige CSVP gerade einmal 65 %. Des Weiteren werden Reaktionen zwischen dem generierten Bitumen und dem verbleibenden Kerogen, dem Pyrobitumen und Pyrit im Falle des Expulsinators stark reduziert. Dagegen zeigt das Residuum von CSVP-Experimenten erhöhte Werte für Stickstoff und Sauerstoff sowie eine Abnahme an Schwefel, was ein Zeichen verstärkter Interaktion zwischen den oben genannten Komponenten ist. Um den Einfluss der Katagenese auf die Menge und Komposition der freigesetzten Pyrolyseprodukte zu untersuchen, wurde ein Experiment mit schrittweiser Erhöhung der Drücke (lithostatisch: 600 bis 900 bar, hydrostatisch: 200 bis 300 bar) und Temperatur gewählt, wodurch Versenkungstiefen von ~2000 m, ~2500 m und 3000 m simuliert wurden. Jede einzelne Stufe des Experiments zeigte für flüssige Kohlenwasserstoffe ein deutliches Expulsionsmaximum, wobei das Gesamtmaximum bei 3000 m erreicht wurde. Die Gegenüberstellung der Expulsinator-Experimente mit CSVP- und MSSV-Experimenten zeigt deutlich eine Auswirkung von Expulsion und primärer Migration auf die n-Alkan-Verteilung und zwar in Abhängigkeit der Reife und der Versenkung. Mit fortlaufender Expulsion konnte dabei eine Zunahme von n-Alkanen mit zunehmender Molekülgröße festgestellt werden, was klar im Zusammenhang mit durch Molekülgröße beeinflussten Zurückhaltungseffekten steht. Isoprenoid-Verhältnisse (Pristan vs. Phytan) und Isoprenoid- n-Alkan-Verhältnisse (Pristan vs. n-C17) zeigen Trends, die die Expulsionsentwicklung wiedergeben, was hauptsächlich durch Generierungseffekte beeinflusst wird. Allerdings eignen sich beide Verhältnisse dennoch als Expulsionsindikator, da Generierung und Expulsion zeitlich verbundene Prozesse sind. Um eine Klassifizierung von Generierung und Expulsion durchzuführen, wurden insgesamt acht lithologisch unterschiedliche Muttergesteine (jeweils zwei Typ-I, Typ-II (-I/II), Typ-IIS und Typ-III Kerogene) mit dem oben beschriebenen Versuchsaufbau verglichen. Auch hier zeigt sich, das Pyrobitumen entscheidend die Reifebewertung eines Muttergesteins beeinflussen kann. Dabei wurde durch Pyrobitumen der gemessene Tmax im Fall vom Kerogen Typ-I erhöht, bei Typ-II und –IIS allerdings erniedrigt. Typ-III Kerogen zeigte einen sehr frühen Generierungsbeginn, gefolgt von Typ-IIS und –II und zuletzt Typ-I Kerogen mit dem spätesten Beginn der Generierung. Damit stehen die beobachtete frühe Generierung und die begleitende hohe Expulsionrate beim Typ-III Kerogen im Wiederspruch zu Beobachtungen in natürlichen Systemen, wo dieser Kerogentyp eher niedrige Expulsionsraten zeigt. Die Ursache liegt in den idealen Expulsions-Bedingungen, die durch den Expulsinator bereitgestellt werden und zu früher Freisetzung der generierten Produkte führt. Dagegen verursacht im natürlichen System Akkumulation von Bitumen im Porenraum des Kerogens und nachfolgende Kondensation zu festem Bitumen zu geringer Generierung und Expulsion. Weitere Unterschiede zwischen den Generierungs/Expulsions-Profilen der unterschiedlichen Muttergesteine werden nicht nur durch die unterschiedliche Beschaffenheit des organischen Materials verursacht, sondern auch maßgeblich durch die unterschiedlichen Lithologien. So zeigen widerstandsfähige Litho-Typen mit hoher Druckresistenz und mit niedriger Permeabilität verringerte Expulsionsraten. Des Weiteren zeigen Lithologien mit hohem Karbonatanteil mit Temperatur und Druck zunehmende CO2-Mengen, was für einen hohen anorganischen Beitrag zum CO2 spricht

The use of stable isotopes for the characterisation of natural organic matter and investigation of the different organic precursors of aquatic systems

This study assesses the potential of compound specific stable carbon isotope analysis (CSIA) to complement traditional molecular analysis and to improve the overall characterisation of Natural Organic Matter (NOM) in drinking water systems. CSIA for characterising NOM fractions and for following their fate from catchment to tap is examined here on a range of samples, including contrasting surface reservoir NOM, biofoulants from water treatment filtration membranes and biofilms from distribution systems

Fully-Automated Verification of Linear Systems Using Inner- and Outer-Approximations of Reachable Sets

Reachability analysis is a formal method to guarantee safety of dynamical systems under the influence of uncertainties. A major bottleneck of all reachability algorithms is the requirement to adequately tune certain algorithm parameters such as the time step size, which requires expert knowledge. In this work, we solve this issue with a fully-automated reachability algorithm that tunes all algorithm parameters internally such that the reachable set enclosure satisfies a user-defined accuracy in terms of distance to the exact reachable set. Knowing the distance to the exact reachable set, an inner-approximation of the reachable set can be efficiently extracted from the outer-approximation using the Minkowski difference. Finally, we propose a novel verification algorithm that automatically refines the accuracy of the outer- and inner-approximation until specifications given by time-varying safe and unsafe sets can either be verified or falsified. The numerical evaluation demonstrates that our verification algorithm successfully verifies or falsifies benchmarks from different domains without any requirement for manual tuning.Comment: 16 page

Black carbon influence on urban soil ecosystem services: from its contribution to the soil carbon cycle to its role in mitigating the risks of heavy metals exposure into urban horticulture produce

Urban soils underpin the provision of all ecosystem services delivered by urban greenspaces which are essential in strengthening urban resilience and mitigating many of the environmental and health challenges faced by urban populations. Understanding how to enhance ecosystem service provision by urban soils is crucial to support future greenspace management strategies, such as urban horticulture expansion or the increased multifunctionality of urban greenspaces. Through different experiments and field studies the role of urban soils in carbon sequestration, pollutant bioavailability and mitigation, urban food and nutritional security has been explored, highlighting the crucial contribution of soil black carbon across all these. Black carbon in the form of soot was demonstrated to play an active role in urban soil carbon dynamics by both suppressing the mineralisation of soil labile organic carbon and contributing to soil CO2 effluxes. Field experimental results revealed that soil application of an engineered form of black carbon (biochar) at the rate of 20 t ha-1 to a clayey loam urban soil under three different vegetation covers did not influence urban soil ecosystem service provision. The first UK-wide assessment of heavy metals and metalloids concentrations (total and bioavailable) across UK urban horticultural soils demonstrated that growing food across these soils poses a low risk to the urban grower’s health and that soil black carbon contributes to mitigating the risk of heavy metals and metalloids uptake into urban horticulture produce. A large-scale field study showed that the long-term exposure to heavy metals and metalloids through consumption of urban horticulture produce is unlikely to pose detrimental human health risks. It also demonstrated that the consumption of urban horticulture produce contributes to the daily intake of all essential minerals, but their concentrations is often lower than those found in equivalent commercial horticultural crops. Future research possibilities are discussed along with the key findings of this research

Thermally altered microbialites of the terminal Ediacaran Dengying Formation, Sichuan Basin, South China

In the Sichuan Basin and surrounding areas, the terminal Ediacaran Dengying Formation hosts diverse microbialite forms. Interest in this formation has mainly centered around oil and gas reservoir development, but recent research aims to characterize its paleobiology via petrographic and molecular fossil analysis. This study aims to characterize the paleobiology and diagenetic history of samples from the Moxi area (central basin), Micangshan Uplift (NW basin margin), and Dabashan thrust belt (N basin margin). Moxi samples are all core samples of Dengying Member 4. Michangshan and Dabashan samples are from outcrop; the Micangshan samples are from Dengying Member 3 and the Dabashan samples are from unknown members of the Dengying Formation and underlying the Doushantuo Formation. All samples were photographed using a petrographic microscope in plane-polarized light (transmitted and reflected), with crossed nicols and in blue-violet light. Hydrocarbon geochemistry and extractable biomarkers were isolated from outcrop samples and characterized. Microbialites in the core samples are mostly stromatolitic and occasionally thrombolitic in texture, while outcrop microbialites are oncolitic and thrombolitic. All samples show putative evidence of hydrothermal alteration and tectonic strain. Extractable biomarkers were limited to a low concentration of n-alkanes with an abnormal distribution of chain lengths. Kerogen geochemical data confirms the samples’ low amenability to biomarker extraction; the maximum hydrogen index (HI) is 51 for all Dengying samples and among the samples with acceptable total organic carbon ( 0.5%) the maximum HI is only 6. Based on mass spectra and free oil measurements, extracted hydrocarbons can be attributed to contamination. The Dengying Formation represents a microbially-dominated system that preserves no convincing evidence of eukaryotes, despite the presence of putative metazoans in nearby sections of the Doushantuo. Extraction of saturated alkanes produced poor yields in the outcrop samples and would likely not be feasible for the core samples based on petrographic analysis showing thermal and tectonic stress. Literature has drawn mixed conclusions about the Dengying Formation’s potential as a source of geologic biomarkers; this study provides more evidence that the Dengying is unlikely to yield any significant biomarker information