Papers by Geoffrey Abbott
Over the last few decades, the Barents Sea experienced substantial warming, an expansion of relat... more Over the last few decades, the Barents Sea experienced substantial warming, an expansion of relatively warm Atlantic water and a reduction in sea ice cover. This environmental change forces the entire Barents Sea ecosystem to adapt and restructure and therefore changes in pelagic–benthic coupling, organic matter sedimentation and long-term carbon sequestration are expected. Here we combine new and existing organic and inorganic geochemical surface sediment data from the western Barents Sea and show a clear link between the modern ecosystem structure, sea ice cover and the organic carbon and CaCO<sub>3</sub> contents in Barents Sea surface sediments. Furthermore, we discuss the sources of total and reactive iron phases and evaluate the spatial distribution of organic carbon bound to reactive iron. Consistent with a recent global estimate we find that on average 21.0 ± 8.3 per cent of the total organic carbon is associated to reactive iron (fOC-Fe<sub>R</sub>) in Barents Sea surface sediments. The spatial distribution of fOC-Fe<sub>R</sub>, however, seems to be unrelated to sea ice cover, Atlantic water inflow or proximity to land. Future Arctic warming might, therefore, neither increase nor decrease the burial rates of iron-associated organic carbon. However, our results also imply that ongoing sea ice reduction and the associated alteration of vertical carbon fluxes might cause accompanied shifts in the Barents Sea surface sedimentary organic carbon content, which might result in overall reduced carbon sequestration in the future.This article is part of the theme issue 'The Changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystems'.
Journal of Plant Nutrition and Soil Science, Feb 1, 2013
ABSTRACT Recently, indirect evidence was obtained for inhibition of soil net N mineralization by ... more ABSTRACT Recently, indirect evidence was obtained for inhibition of soil net N mineralization by sterols in soil organic matter, which could have been caused by their antioxidant or antimicrobial properties. The objective of this study was to test the effect of potential inhibitors (i.e., individual compounds with known antioxidant and/or antimicrobial properties) on soil microbial mineralization processes during incubation for 7 and 14 d. A sandy agricultural soil was amended with four substances: two phenolic acids differing in their antioxidant capacity (AOC) (acetovanillone with no AOC, ferulic acid with large AOC), Trolox, an analogue of vitamin E (large AOC), and β-sitosterol (no AOC, but potential antimicrobial properties). The two compounds with large AOC (ferulic acid and Trolox) showed no significant inhibition of C and net N mineralization; and the Trolox amendment actually caused a significant increase in C and net N mineralization after 7 d of incubation. Acetovanillone with no measurable AOC caused a significant increase in C mineralization (109% of substance C added), indicating degradation of the substance, and a very pronounced negative net N mineralization within 7 d (–356%), which was interpreted as N immobilization. Only β-sitosterol showed strong inhibition of net N mineralization after 7 and 14 d (–59% and –26%, respectively) which was not interpreted as N immobilization, since there was no concomitant increase in C mineralization. Thus, an antimicrobial effect of β-sitosterol specificly on microorganisms of the N cycle was suggested, but there was no clear inhibitory effect caused by the antioxidant compounds.
Comparative biochemistry and physiology. B. Comparative biochemistry, May 1, 1992
The red colour of some terebratulid brachiopod shells is caused by a small chromoprotein that occ... more The red colour of some terebratulid brachiopod shells is caused by a small chromoprotein that occurs within the calcium carbonate matrix of the shell. 2. This carotenoid-protein complex was isolated from within the calcite shell of three different brachiopod genera and may therefore be involved in the process of biomineralization. 3. The apparent molecular weight of this protein, as judged by SDS-PAGE, is 6.5 kDa. 4. The partial N-terminal amino acid sequence of the protein is virtually identical in three different brachipod genera, indicating homology. 5. Two carotenoids are present in Terebratella sanguinea: canthaxanthin and the tentatively identified monoacetylinic analogue of astaxanthin.
Chemical Physics Letters, Jun 1, 1978
The first observation iu the vapour phase of strongly fluorescent euciplexes between complex poly... more The first observation iu the vapour phase of strongly fluorescent euciplexes between complex polyatomic molecules is reported. Systems studied were electronically excited 9-cyano anthracene as electron acceptors with Methyl and tributyl amine and dimethyl aniline as electron donors, at temperatures III the 185-23 l°C range_ Fluorescence spectra, excitation spectra and preliiinary decay time data are reported.
Organic Geochemistry, Dec 1, 1999
... Barry Bennett and Geoffrey D. Abbott Corresponding Author Contact Information , E-mail The Co... more ... Barry Bennett and Geoffrey D. Abbott Corresponding Author Contact Information , E-mail The Corresponding Author. ... study on samples from this horizon (Bishop and Abbott, 1993) as well as a more recent study on an adjacent carbonate concretionary horizon ( Farrimond et al ...
Summary Phenolic compounds play a crucial role in northern peatland dynamics by inhibiting the de... more Summary Phenolic compounds play a crucial role in northern peatland dynamics by inhibiting the degradation of organic matter in surficial peat layers. There is uncertainty as to how the phenolic content of both Sphagnum moss and northern peats will respond to intensified drought events, which are increasing in occurrence. This research aims to disentangle the fate of ‘free’ phenolics in peatlands by identifying and tracking a series of targeted, water-soluble phenolic acids, and determining their antioxidant capacity (following their release into peat DOM from peat/moss). The source, stability and fate of these compounds and the extent at which they contribute to the antioxidant pool in northern peats remains unknown.
AGUFM, Dec 1, 2010
Northern peatlands store around one third of global soil C and thus represent a key reservoir. To... more Northern peatlands store around one third of global soil C and thus represent a key reservoir. To elucidate how these systems might respond to climate change, field- and laboratory-based experimental incubation studies are being conducted at sites across a natural peatland gradient in the boreonemoral zone of central Sweden (Ryggmossen). The site comprises four successional stages, from edge to centre;
Several species of peat moss and vascular plants were collected from field incubation litterbag e... more Several species of peat moss and vascular plants were collected from field incubation litterbag experiments set up in a peatland located in the boreonemoral zone of central Sweden. These were then analysed using THM in the presence of TMAH which revealed the distributions of both lignin-and Sphagnum-derived phenols within specific species. THM of seven species of Sphagnum indicated the presence of four Sphagnum-specific biomarkers; methylated 4-isopropenylphenol, methylated cis and trans 3-(4'hydroxyphen-1-yl)-but-2-enoic acid, and methylated 3-(4'-hydroxyphen-1-yl)-but-3-enoic acid.
Organic Geochemistry, 2012
... Lambda (Λ) was calculated as the summed amounts of the following methylated syringyl, guaiacy... more ... Lambda (Λ) was calculated as the summed amounts of the following methylated syringyl, guaiacyl and cinnamyl phenols (G4 + G5 + G6 + S4 + S5 + S6 + G18 + P18) normalised to 100 mg of organic carbon (OC) ( [Hedges and Mann, 1979] , [Hedges et al., 1982] and [Kögel ...
Journal of the Geological Society, Sep 1, 1995
Like many examples of Mississippi Valley-type mineralization, the South Pennine Orefield is well-... more Like many examples of Mississippi Valley-type mineralization, the South Pennine Orefield is well-known for the occurrence of hydrocarbons within hydrothermal mineral veins. Bitumens from this area along with oils from the East Midlands have been characterized using standard organic geochemical techniques and compared with potential source rocks. Lower Namurian mudstones from the Widmerpool Gulf and the Gainsborough and Goyt Troughs were rejected as possible sources for the bitumens and oils on the grounds of lack of sufficient thermal maturity and/or essential biomarker correlation. Lower Namurian mudstones with type II kerogen from the Edale Gulf are proposed to offer a likely hydrocarbon source for the area, with a minor, more localized contribution from organic-rich type II mudstone partings within the Dinantian limestones. Simple geochemical models, consistent with recent sequence stratigraphic interpretation, suggest a late Carboniferous age for hydrocarbon generation, where geothermal gradients were slightly higher (c.50°C km−1) than the present day. Microthermometric analysis of fluid inclusions from fluorite and calcite allowed three fluid types to be distinguished. One Na–Ca–Cl bearing fluid was discerned to be dominant throughout the orefield, being of low temperature (uncorrected Th = 70-110 °C) and high salinity (c. 20equiv. wt% NaCl). A second high salinity Na–Ca–Cl fluid (uncorrected Th = 70-120 °C, c. 24equiv. wt% NaCl), distinguished from the first by varying Na-Ca contents, was observed in the westernmost extremities of the orefield. A third NaCl bearing fluid of higher temperature (T h = 100-145 °C) and lower salinity (4 wt% NaCl) was detected in the northernmost part of the orefield. Hydrocarbon-bearing inclusions were not observed in any of the three fluids in this study. Sulphur isotopic analyses performed on a selection of sulphides, sulphates and bitumens to gauge the role of organic matter in sulphate reduction reactions proved inconclusive. The mineralization is thought to have occurred as several events. That in the north is thought to be derived from the dewatering of the Edale Gulf towards the end of the Carboniferous, whilst other mineralization events occurred from the early Permian onwards, with the ore fluids having more distal sources, predominantly from the east with a minor input from the west. The main phases of hydrocarbon generation and mineralization appear to be unrelated.
Organic Geochemistry, Aug 1, 2008
... Straw (4 g dry weight) was then placed into 250 ml amber glass jars (separate jars were used ... more ... Straw (4 g dry weight) was then placed into 250 ml amber glass jars (separate jars were used for each time point in the series ... 95% v/v ethanol/water) were added to each sample, and the samples ultrasonically agitated for 5 min in a Hilsonic ultrasonic bath (Hilbre Ultrasonics Ltd ...
Journal of Photochemistry and Photobiology, 1978
SO9 5NH, Hants.(Gt. Britain) Simple tertiary aliphatic amines have been known to be strongly fluo... more SO9 5NH, Hants.(Gt. Britain) Simple tertiary aliphatic amines have been known to be strongly fluorescent for some but the excitation energy dependence of this emission has not hitherto been investigated.
Philosophical transactions of the Royal Society of London, Jul 25, 1985
226Ra. Since the source of these surpluses is nearbottom shelf or slope water, and since the half... more 226Ra. Since the source of these surpluses is nearbottom shelf or slope water, and since the half-life of 222Rn is only 3.8 days, such surpluses are indicative of rapid offshore advective and/or mixing processes. Concentrations of 226Ra exhibit a small but measurable increase when moving from the Sargasso Sea, through the slope water, and up onto the shelf.
Philosophical Transactions of the Royal Society B, Sep 30, 1991
Brachiopods contain both proteins and lipids within the biocrystals of their shell. One intracrys... more Brachiopods contain both proteins and lipids within the biocrystals of their shell. One intracrystalline chromoprotein causes red shell coloration, whereas the other molecules may be involved with biomineralization, may strengthen the biocrystal, or may simply have been inadvertently engulfed by calcite during shell growth. Evidence is presented which suggests that at least some of the breakdown products of indigeneous intracrystalline molecules can be recovered from the biocrystals of fossil brachiopod shells. Investigations of the remains of these intracrystalline molecules in fossils have geological application in fields such as environmental reconstruction, isotopic determinations, taxonomy and the interpretation of colour in extinct organisms.
Geochimica et Cosmochimica Acta, Jun 1, 1995
AImtract--Involatile hydrocarbons were identified following the heating of 5a(H)-cholestane in wa... more AImtract--Involatile hydrocarbons were identified following the heating of 5a(H)-cholestane in water with reaction vessel walls composed of 316 grade stainless steel and borosilicate glass. These analyses were compared with the hydrocarbon product compositions from closed-system pyrolysis experiments with no added water. Unsaturated hydrocarbons dominate their saturated counterparts following hydrous pyrolysis in both stainless steel-316 and borosilicate glass. In the absence of added water the converse is true in that saturated components dominate the hydrocarbon mixture. Backbone rearrangement in the steroid nucleus leading to spirosterene formation was only observed under aqueous conditions in both borosilicate glass and stainless steel-316 vessels. These comparisons demonstrate that water, as opposed to reaction vessel surface catalytic effects, plays a central role in mediating hydrocarbon degradation during closedsystem hydrous pyrolysis. 5a(H ) -cholestane degradation under aqueous conditions is a complex composite of dissociative and rearrangement processes. These include ( 1 ) carbon-carbon bond cleavage in the sidechains as well as the ring system, (2) dehydrogenation, and (3) backbone rearrangement. These laboratory experiments provide a product description of the involatile hydrocarbons which will be the basis for a mechanistic study of 5a(H)-cholestane degradation in hot water.
Journal of Analytical and Applied Pyrolysis, Jun 1, 2023
Summary Increases in Arctic sea ice extent have been observed over the past decades with warming ... more Summary Increases in Arctic sea ice extent have been observed over the past decades with warming at the high latitudes especially pronounced, including in the northern Barents Sea. To track variability between years in the timing and extent of ice-out we compared surface sediment pigment, fatty acid and sterol compositions between ice abundant (2017 and 2019) and ice-free (2018) summer sampling seasons across a south to north 30° E gradient. We found total chlorophyll-derived pigments varied predictably across the transect, and were usually markedly higher at station closest to the Polar Front transition. In 2018 which had an unusually low ice-extent and an early ice-out in the northern Barents Sea confirmed by satellite imagery, highest concentrations were present in the northerly station, indicative of increased production from phytoplankton. This trend was mirrored by total fatty acid methyl esters (FAMEs) which in 2018 showed progressive increases from southern to northern stations, with the pattern driven predominantly by short-chain FAMEs which are abundant in phytoplankton. Our findings have consequences for the functioning of the Arctic carbon cycle – if retreat of Arctic sea ice persists and ‘atlantification’ continues, then delivery of phytoplankton bloom-derived carbon to the seafloor could intensify.
Organic Geochemistry, 1988
The kinetics of the aromatisation of both rearranged and non-rearranged monoaromatics have been i... more The kinetics of the aromatisation of both rearranged and non-rearranged monoaromatics have been investigated in the laboratory under free radical conditions. These studies have indicated that the aromatisation rate constant for the non-rearranged is greater than that for the rearranged isomers at any one particular temperature. Since the members of the rearranged series coelute with their non-rearranged counterparts when both series are present in geological extracts, these results suggest that care needs to be exercised when assessing extents of maturation using monoaromatic and triaromatic steroid hydrocarbons.
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Papers by Geoffrey Abbott
Topics connecting the various papers are properties of materials, preferences and choices of actors, the temporality of matter, being and becoming, the relationality between actors, matter, things and space (landscape, urban space, built space), and perceptions of the following generations dealing with the petrified matter, practices, and social relations. Contributors to this volume study specifically whether particular processes of petrification are confined to the material world or can be seen as mirroring, following, triggering, or contradicting changes in social life and general world views. Each of the authors explores – for a period or a specific feature – practices and changes that led to increased conformity and regularity. Some authors additionally focus on the methods and scrutinize them and their applications for their potential to create objects of investigation: things, people, periods, in order to raise awareness for these or to shape or “invent” categories. This volume is of interest to archaeologists, geologists, architectural historians, conservationists, and historians.