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Le Heron D.P.,Royal Holloway, University of London | Armstrong H.A.,Durham University | Wilson C.,Durham University | Howard J.P.,CASP | Gindre L.,ASA Research
Sedimentary Geology | Year: 2010

Detailed outcrop studies at the flanks of Al Kufrah Basin, Libya, reveal the nature of glacially-related sedimentation and post-depositional deformation styles produced in association with the Late Ordovician glaciation, during which ice sheets expanded northward over North Africa to deposit the Mamuniyat Formation. At the SE basin flank (Jabal Azbah), the Mamuniyat Formation is sand-dominated, and incises interfingering braidplain and shallow marine deposits of the Hawaz Formation. The glacially-related sediments include intercalations of mud-chip bearing tabular sandstones and intraformational conglomerates, which are interpreted as turbidite and debrite facies respectively. These record aggradation of an extensive sediment wedge in front of a stable former ice margin. An increase in mudstone content northward is accompanied by the occurrence of more evolved turbidites. A widespread surface, bearing streamlined NW-SE striking ridges and grooves, punctuates this succession. The structures on the surface are interpreted to have formed during a regional north-westward ice advance. Above, siltstones bearing Arthrophycus burrows, and Orthocone-bearing sandstones beneath tidal bars testify to glaciomarine conditions for deposition of the underflow deposits beneath. By contrast, the northern basin margin (Jabal az-Zalmah) is appreciably different in recording shallower water/paralic sedimentation styles and major glaciotectonic deformation features, although facies analysis also reveals northward deepening. Here, a siltstone wedging from 8 to 50m toward the north was deposited (lower delta plain), succeeded by climbing ripple cross-laminated sandstones up to 60m in thickness (distal through proximal delta mouth bar deposits) with occasional diamictite interbeds. These rocks are deformed by thrusts and >50m amplitude fault-propagation folds, the deformation locally sealed by a diamictite then overlain by conglomeratic lag during ultimate deglaciation. Integrating observations from both basin margins, a model of fluvial-dominated delta systems feeding a pulsed debrite and turbidite fan system in a shallow proglacial shelf is proposed. © 2009 Elsevier B.V.


Hillier J.,University of Aberdeen | Brentrup F.,ASA Research | Wattenbach M.,Helmholtz Center Potsdam | Walter C.,Unilever | And 3 more authors.
Global Change Biology | Year: 2012

Major sources of greenhouse gas (GHG) emissions from agricultural crop production are nitrous oxide (N 2O) emissions resulting from the application of mineral and organic fertilizer, and carbon dioxide (CO 2) emissions from soil carbon losses. Consequently, choice of fertilizer type, optimizing fertilizer application rates and timing, reducing microbial denitrification and improving soil carbon management are focus areas for mitigation. We have integrated separate models derived from global data on fertilizer-induced soil N 2O emissions, soil nitrification inhibitors, and the effects of tillage and soil inputs of soil C stocks into a single model to determine optimal mitigation options as a function of soil type, climate, and fertilization rates. After Monte Carlo sampling of input variables, we aggregated the outputs according to climate, soil and fertilizer factors to consider the benefits of several possible emissions mitigation strategies, and identified the most beneficial option for each factor class on a per-hectare basis. The optimal mitigation for each soil-climate-region was then mapped to propose geographically specific optimal GHG mitigation strategies for crops with varying N requirements. The use of empirical models reduces the requirements for validation (as they are calibrated on globally or continentally observed phenomena). However, as they are relatively simple in structure, they may not be applicable for accurate site-specific prediction of GHG emissions. The value of this modelling approach is for initial screening and ranking of potential agricultural mitigation options and to explore the potential impact of regional agricultural GHG abatement policies. Given the clear association between management practice and crop productivity, it is essential to incorporate characterization of the yield effect on a given crop before recommending any mitigation practice. © 2012 Blackwell Publishing Ltd.


Portz G.,University of Sao Paulo | Molin J.P.,University of Sao Paulo | Jasper J.,ASA Research
Precision Agriculture | Year: 2012

Nitrogen management has been intensively studied on several crops and recently associated with variable rate on-the-go application based on crop sensors. Such studies are scarce for sugarcane and as a biofuel crop the energy input matters, seeking high positive energy balance production and low carbon emission on the whole production system. This article presents the procedure and shows the first results obtained using a nitrogen and biomass sensor (N-Sensor ™ ALS, Yara International ASA) to indicate the nitrogen application demands of commercial sugarcane fields. Eight commercial fields from one sugar mill in the state of São Paulo, Brazil, varying from 15 to 25 ha in size, were monitored. Conditions varied from sandy to heavy soils and the previous harvesting occurred in May and October 2009, including first, second, and third ratoon stages. Each field was scanned with the sensor three times during the season (at 0.2, 0.4, and 0.6 m stem height), followed by tissue sampling for biomass and nitrogen uptake at ten spots inside the area, guided by the different values shown by the sensor. The results showed a high correlation between sensor values and sugarcane biomass and nitrogen uptake, thereby supporting the potential use of this technology to develop algorithms to manage variable rate application of nitrogen for sugarcane. © 2011 Springer Science+Business Media, LLC.


The aim of this study was to gain a deeper knowledge of the effects of mechanical site preparation on the survival and growth of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and Norway spruce (Picea abies (L.) Karst.) seedlings in southern Sweden. The experiment was conducted on a fresh clearcut at the Asa experimental forest (57° 10′ N). The effects of five different site preparation treatments were investigated: control, patch, mound, invert and mix. In each treatment, 40 seedlings of Norway spruce and 40 of Douglas fir were planted in each of four blocks. Site preparation had little or no effect on the survival and growth of Norway spruce: only a few seedlings died during the first 2 years. For Douglas fir, however, all site preparation treatments increased survival compared with the control, where mortality was high. The most intensive soil preparation treatment, mix, significantly increased root growth and total biomass. Pine weevils caused more severe damage to Douglas fir seedlings than to Norway spruce and targeted different locations in the two species, causing comparatively more damage to the leading shoots of Douglas fir seedlings. © 2012 Institute of Chartered Foresters. All rights reserved.


Lokken T.V.,ASA Research
Journal of Natural Gas Science and Engineering | Year: 2013

An investigation of hygrometers for monitoring of water vapour (moisture) in natural gas has been performed, with respect to response on ethylene glycol co-exposure. The tested hygrometers are based on: 1. capacitor sensor, 2. quartz crystal microbalance (QCM), 3. fibre-optic sensor and 4. conversion of water to ethyne, quantified by a gas chromatograph (CaC2-GC). The moisture concentration level in the test gas was 50 μmol/mol during the experiments, corresponding to a frost point of approximately -48 °C (atmospheric pressure). The experiments were performed in the laboratory, using nitrogen as matrix gas. The QCM hygrometer responded with a downward drift of the frost point readings in the presence of traces of ethylene glycol (0.25 μmol/mol and 0.66 μmol/mol, respectively). The drift increased initially when the ethylene glycol concentration increased, and the frost point readings from the QCM hygrometer decreased close to 5 °C during a total of 20 days of ethylene glycol exposure. The QCM hygrometer seemed to recover slowly from the ethylene glycol exposure, indicated by a decreasing upward drift as soon as the ethylene glycol exposure ended. Both tested capacitor hygrometers responded significantly to ethylene glycol exposure. The responses were not uniform, though, with one performing considerably better than the other one. The experiments also demonstrated the insufficiency of chilled mirror techniques for interpreting water frost points or water dew points, with subsequent moisture concentration calculation, in the presence of ethylene glycol, even at trace amounts. This made the chilled mirror technique totally unsuitable for reference measurements after the introduction of ethylene glycol to the test gas. The fibre-optic sensor hygrometer and the CaC2-GC hygrometer showed minor response for ethylene glycol. In general the results from this work demonstrate the need for careful evaluation of individual moisture monitoring applications, before choosing a hygrometer. A well-considered strategy for quality control of the moisture monitoring, regardless of the chosen hygrometer, is of utmost importance to establish a moisture monitoring system with high accuracy. © 2013 Elsevier B.V.


Elkasabi Y.,U.S. Department of Agriculture | Mullen C.A.,U.S. Department of Agriculture | Pighinelli A.L.M.T.,U.S. Department of Agriculture | Pighinelli A.L.M.T.,ASA Research | Boateng A.A.,U.S. Department of Agriculture
Fuel Processing Technology | Year: 2014

In this paper, we sought to elucidate the relationships between biomass feedstock type and the suitability of their fast-pyrolysis bio-oils for hydrodeoxygenation (HDO) upgrading. Switchgrass, Eucalyptus benthamii, and equine manure feedstocks were pyrolyzed into bio-oil using a continuous fast-pyrolysis system. We also synthesized variations of switchgrass bio-oil using catalytic pyrolysis methods (HZSM-5 catalyst or tail-gas recycle method). Bio-oil samples underwent batch HDO reactions at 320 C under ~ 2100 psi H 2 atmosphere for 4 h, using Pt, Ru, or Pd on carbon supports. Hydrogen consumption was measured and correlated with compositional trends. The resulting organic, aqueous, and gas phases were analyzed for their chemical compositions. Mass balances indicate little coke formation. Switchgrass bio-oil over Pt/C performed the best in terms of hydrogen consumption efficiency, deoxygenation efficiency, and types of upgraded bio-oil compounds. Eucalyptus feedstocks consistently consumed more than twice the normal amount of hydrogen gas per run, primarily due to the elevated syringol content. Catalytically pyrolyzed bio-oils deoxygenated poorly over Pt/C but hydrogenated more extensively than other oils. Although the relative deoxygenation (%DO rel) varied based on feedstock and catalyst, the absolute deoxygenation (%DOabs) depended only on the overall yield. The total extent of upgrading (hydrogenation + deoxygenation) remained independent of feedstock and catalyst. © 2014 Elsevier B.V.


Nilsson U.,Swedish University of Agricultural Sciences | Elfving B.,Swedish University of Agricultural Sciences | Karlsson K.,ASA Research
Silva Fennica | Year: 2012

Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during precommercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.


Senbayram M.,ASA Research | Senbayram M.,University of Kiel | Chen R.,CAS Nanjing Institute of Soil Science | Budai A.,Norwegian University of Life Sciences | And 3 more authors.
Agriculture, Ecosystems and Environment | Year: 2012

Amending agricultural soils with organic residues is frequently recommended to improve soil fertility and to sequester carbon for counteracting global warming. However, such amendments will enhance microbial respiration, hence denitrification. Therefore, the assessment of effects on global warming must take N 2O emission and the N 2O/(N 2O+N 2) product ratio of denitrification into account. There are some indications that the product ratio of denitrification is positively correlated with the ratio of available NO 3 - and available organic C in soils, but more research is needed to unravel quantitative relationships in well defined experiments. We conducted two laboratory incubation experiments, with the objective (i) to test the impact of the application of various N containing organic substrates including biogas residue on the denitrification rate and on N 2O emission, and (ii) to investigate the effect of various NO 3 - concentrations on the denitrification rate and the N 2O/(N 2O+N 2) product ratio under standardized anoxic conditions in soils collected from long-term organic or inorganic fertilizer plots. In experiment 1, we found that biogas residue was more recalcitrant than maize straw, despite a high concentration of soluble organic C. High respiration (treatments with maize straw and sucrose) resulted in a transient peak in N 2O emission, declining rapidly towards zero as nitrate concentrations reached less than 20mg NO 3 --Nkg -1 dry soil. Application of biogas residue had a more moderate effect on soil respiration and denitrification, and resulted in a more long lasting peak in N 2O emission. The results were interpreted as a result of a gradual increase in the relative activity of N 2O reductase (thus lowering of the N 2O/(N 2O+N 2) product ratio of denitrification) throughout the incubation, most likely controlled by concentration of available NO 3 - in soil. In the second experiment, we found low N 2O/(N 2O+N 2) product ratios for the treatment where NO 3 - concentrations were ≤2mM, and the ratios were clearly lower in manure fertilized than in mineral fertilizer treated soil. Much higher N 2O/(N 2O+N 2) product ratios were found for the treatments with ≥10mM NO 3 -, and the ratios were remarkably independent of the soil's fertilizer history. We conclude that (i) in N-fertilized agricultural soils, application of organic matter with high contents of labile C may trigger denitrification-derived N 2O emission whereas (ii) in soils with low NO 3 - contents such application may substantially lower the N 2O/(N 2O+N 2) product ratio and hence N 2O emission. © 2011 Elsevier B.V.


Langvall O.,ASA Research | Bergh J.,ASA Research
Silva Fennica | Year: 2012

The purpose of the study was to create a near optimal environment for seedling establishment and growth, without the restrain of water and nutrients but under climate conditions typical for the region. This to give us valuable knowledge about the growth potential of different seedling types in the field. The experimental site was situated in southern Sweden. Six treatment combinations were applied including two site treatments; 1) soil inversion, i.e. the control treatment, and 2) soil inversion, drip irrigation and fertilization combined with plastic cover mulch, i.e. the optimization treatment, and three seedling types of Norway spruce (Picea abies L. Karst.), (a) a 2-year-old Plug+1 seedling, (b) a 1.5-year-old containerized seedling and (c) a 10-week-old mini seedling. Effects on seedling nutrient status and growth were studied during the first three years after planting. Height, diameter and biomass of the seedlings grown in the optimized environment were significantly greater than for seedlings grown in the control. The Plug+1 seedlings grown in the optimization treatment had, after three years, reached a height of 124 cm, while the containerized seedlings were 104 cm and the mini seedlings 45 cm. In practical plantations, this height is usually gained after 5-10 years depending on planting conditions. Biomass partitioning did not differ between optimization treatments, but between seedling types. The mini seedlings allocated less biomass to the roots and more biomass to needles and stem in comparison with the two other seedling types. Mini seedlings also broke bud earlier. Throughout the experimental period, seedling nutrient status for all treatment combinations was followed and a balanced nutrient supply of macro- and micronutrients was given in the optimization treatment. Nutrient concentrations were constantly higher in seedlings grown in the optimization treatment, but the difference decreased over time. Results from this study shows that, by improving site conditions associated with fast establishment, growth check can be avoided.


Jordan O.D.,ASA Research | Jordan O.D.,Imperial College London | Mountney N.P.,University of Leeds
Sedimentology | Year: 2010

The Pennsylvanian to Permian lower Cutler beds comprise a 200 m thick mixed continental and shallow marine succession that forms part of the Paradox foreland basin fill exposed in and around the Canyonlands region of south-east Utah. Aeolian facies comprise: (i) sets and compound cosets of trough cross-bedded dune sandstone dominated by grain flow and translatent wind-ripple strata; (ii) interdune strata characterized by sandstone, siltstone and mudstone interbeds with wind-ripple, wavy and horizontal planar-laminated strata resulting from accumulation on a range of dry, damp or wet substrate-types in the flats and hollows between migrating dunes; and (iii) extensive, near-flat lying wind-rippled sandsheet strata. Fluvial facies comprise channel-fill sandstones, lag conglomerates and finer-grained overbank sheet-flood deposits. Shallow marine facies comprise carbonate ramp limestones, tidal sand ridges and bioturbated marine mudstones. During episodes of sand sea construction and accumulation, compound transverse dunes migrated primarily to the south and south-east, whereas south-westerly flowing fluvial systems periodically punctuated the dune fields from the north-east. Several vertically stacked aeolian sequences are each truncated at their top by regionally extensive surfaces that are associated with abundant calcified rhizoliths and bleaching of the underlying beds. These surfaces record the periodic shutdown and deflation of the dune fields to the level of the palaeo-water-table. During episodes of aeolian quiescence, fluvial systems became more widespread, forming unconfined braid-plains that fed sediment to a coastline that lay to the south-west and which ran approximately north-west to south-east for at least 200 km. Shallow marine systems repeatedly transgressed across the broad, low-relief coastal plain on at least 10 separate occasions, resulting in the systematic preservation of units of marine limestone and calcarenite between units of non-marine aeolian and fluvial strata, to form a series of depositional cycles. The top of the lower Cutler beds is defined by a prominent and laterally extensive marine limestone that represents the last major north-eastward directed marine transgression into the basin prior to the onset of exclusively non-marine sedimentation of the overlying Cedar Mesa Sandstone. Styles of interaction between aeolian, fluvial and marine facies associations occur on two distinct scales and represent the preserved expression of both small-scale autocyclic behaviour of competing, coeval depositional systems and larger-scale allocyclic changes that record system response to longer-term interdependent variations in climatic and eustatic controlling mechanisms. The architectural relationships and system interactions observed in the lower Cutler beds demonstrate that the succession was generated by several cyclical changes in both climate and relative sea-level, and that these two external controls probably underwent cyclical change in harmony with each other in the Paradox Basin during late Pennsylvanian and Permian times. This observation supports the hypothesis that both climate and eustasy were interdependent at this time and were probably responding to a glacio-eustatic driving mechanism. © 2010 The Authors. Journal compilation © 2010 International Association of Sedimentologists.

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