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The effect of climate on the decomposition of chemical constituents of tree littersMcTiernan, Kevin B. January 1998 (has links)
No description available.
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Improving the understanding of fundamental mechanisms that influence ignition and burning behavior of porous wildland fuel bedsThomas, Jan Christian January 2017 (has links)
The phenomenon of a fire occurring in nature comes with a very high level of complexity. One central obstacle is the range of scales in such fires. In order to understand wildfires, research has to be conducted across these scales in order to study the mechanisms which drive wildfire behavior. The hazard related to such fires is ever more increasing as the living space of communities continues to increase and infringe with the wildland at the wildland-urban interface. In order to do so, a strong understanding on the possible wildfire behavior that may occur is critical. An array of factors impact wildfire behavior, which are generally categorized into three groups: (1) fuel (type, moisture content, loading, structure, continuity); (2) environmental (wind, temperature, relative humidity, precipitation); and (3) topography (slope, aspect). The complexity and coupling of factors impacting various scales of wildfire behavior has been the focus of much experimental and numerical work over the past decades. More recently, the need to quantify wildland fuel flammability and use the knowledge in mitigating risks, for example by categorizing vegetation according to their flammability has been recognized. Fuel flammability is an integral part of understanding wildfire behavior, since it can provide a quantification of the ignition and burning behavior of wildland fuel beds. Determining flammability parameters for vegetative fuels is however not a straight forward task and a rigorous standardized methodology has yet to be established. It is the intent of this work to aid in the path of finding a most suitable methodology to test vegetative fuel flammability. This is achieved by elucidating the fundamental heat and mass transfer mechanisms that drive ignition and burning behavior of porous wildland fuel beds. The work presented herein is a continuation of vegetative fuel flammability research using bench-scale calorimetry (the FM Global Fire Propagation Apparatus). This apparatus allows a high level of control of critical parameters. Experimental studies investigate how varying external heat flux (radiative), ventilation conditions (forced airflow rate, oxygen concentration, and temperature), and moisture content affect the ignition and burning behavior of wildland fuel. Two distinct ignition regimes were observed for radiative heating with forced convection cooling: (1) convection/radiation for low heating rates; and (2) radiation only for high heating rates. The threshold for the given convection conditions was near 45 kW.m-2. For forced convection, ignition behavior is dominated by convection cooling in comparison to dilution; ignition times were constant when the oxygen flow rate was varied (constant flow magnitude). Analysis of a radiative Biot number including heat losses (convection and radiation) indicated that the pine needles tested behaved thermally thin for the given heating rates (up to 60 kW.m-2). A simplified onedimensional, multi-phase heat transfer model for porous media is validated with experimental results (in-depth temperature measurements, critical heat flux and ignition time). The model performance was adequate for two species only, when the convective Froude number is less than 1.0 (only one packing ratio was tested). Increasing air flow rates resulted in higher heat of combustion due to increased pyrolysis rates. In the given experiments (ventilation controlled environment) combustion efficiency decreased with increasing O2 flow rates. Flaming combustion of pine needles in such environments resulted in four times greater CO generation rates compared to post flaming smoldering combustion. A link was made to live fuel flammability that is important for understanding the occurrence of extreme fire conditions such as crowning and to test if live fuel flammability contributes to the occurrence of a typical fire season. Significant seasonal variations were observed for the ignition and burning behavior of conditioned live pine needles. Variation and peak flammability due to ignition time and heat release rate can be associated to the growing season (physical properties and chemical composition of the needles). Seasonal trends were masked when unconditioned needles were tested as the release of water dominated effects. For wet fuel, ignition time increases linearly with fuel moisture content (FMC, R2 = 0.93). The peak heat release rate decreased non-linearly with FMC (R2 = 0.77). It was determined that above a threshold of 60% FMC (d.w.), seasonal variation in the heat release rate can be neglected. A novel live fuel flammability assessment to evaluate the seasonality of ignition and burning behavior is proposed. For the given case (NJ Pine Barrens, USA), the flammability assessment indicated that the live fuel is most flammable in August. Such assessment can provide a framework for a live fuel flammability classification system that is based on rigorous experimentation in well controlled fire environments.
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Uptake of airborne organic pollutants in pine needles : geographical and seasonal variations /Hellström, Anna. January 2003 (has links)
Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003. / Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.
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A comparison of atmospheric PAHs in pine needles and high-volume sampler filters in the dayton metro areaTomashuk, Timothy A. 16 July 2010 (has links)
No description available.
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Comparing the Ignitability of Mulch Materials for a Firewise LandscapeDeGomez, Tom, Rogstad, Alix, Schalau, Jeff, Kelly, Jack 09 1900 (has links)
5 pp. / Eight different landscape mulches were tested for their flammability using a propane torch, charcoal briquette, and a cigarette at two different times of the year. Three randomized compete blocks with eight one square meter plots were tested at three locations; Tucson, Prescott, and Flagstaff, Arizona. Each of the mulches was subjected to the heat of a handheld propane torch (15 seconds), a glowing charcoal briquette (five minutes), and a lit cigarette (until burned out). We found that the least dense mulches (pine needles and straw) burned rapidly when subjected to the torch and ignited after the briquette was removed. The medium density mulches (pine bark nuggets and wood chips) had low flame lengths and smoldered. Heavy density mulches (garden compost and shredded bark) only smoldered. The decomposed granite and sod did not ignite or smolder.
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Comandra Blister RustOlsen, Mary W., Young, Deborah 05 1900 (has links)
3 pp. / Mondell pine should not be planted within a mile of Comandra populations. Infection of pine occurs through needles by spores produced on Comandra, but spores produced on pine cannot re-infect pine. This article gives information about the disease cycle, the symptoms and prevention and control methods for blister rust.
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Assessing industrial pollution by means of environmental samples in the Kemi-Tornio regionPöykiö, R. (Risto) 29 November 2002 (has links)
Abstract
The results of the comparison of various dissolution methods for sulphur showed, that HNO3 together with
H2O2 gave more complete decomposition of organic components than HNO3
alone. The acid procedure with a mixture of HNO3+H2O2 slightly
underestimated the S concentrations of plant material. The losses of sulphur were the highest in the dry ashing digestion procedure
(HF(DAC)). The Leco combustion technique with infrared (IR) detection gave good precision and accuracy for sulphur. For the determination
of heavy metals in plant materials, both the HNO3 and
HNO3+H2O2 procedures were especially effective for determining Cr.
However, the HNO3+HClO4 procedure gave lower results, and HF and HF(DAC) procedures greater
values for Cr.
Sulphur accumulation in pine needles around the pulp and paper mills was clearly higher than other points in the Kemi area. For
example, within a radius of about 1-1.5 km around the mills of Oy Metsä-Botnia Ab Kemi Mills, the sulphur concentrations for (C) and
(C+1) needles were 28 % and 26 % higher than those in the corresponding background samples collected in Kuivaniemi at a distance about 25
km from Kemi. Pine needles do not appeared to be appropriate a method for monitoring the accumulation of Fe, Zn, V and Pb emitted from pulp
and paper mills. However, the Ca concentrations in (C+1) needles in the vicinity of the Oy Metsä-Botnia Ab Kemi Mills was 48 % higher
than
the average Ca concentration calculated from all (C+1) needles; thus it is likely that part of the Ca in the needles is derived from the
mills.
The regional distribution pattern of Cr and Ni in mosses in the Kemi-Tornio area in 2000 showed clearly that the most polluted area
(Cr > 200 μg/g and Ni > 20 μg/g) appeared to lie within a few kilometres of the ferrochrome and stainless steel works of
AvestaPolarit Stainless Oy. Within this area, the Cr concentrations in mosses were 4-13 times higher than those outside the urban area of
Tornio. The area most polluted by the opencast chromium mining complex (Cr > 200 μg/g and Ni < 20 μg/g) appeared to be in
the immediate vicinity of complex.
All the 95th percentile values for TSP (total suspended particles) in the mine area of AvestaPolarit
Chrome Oy Kemi Mine were below the current Finnish air quality limit value of 300 μg/m3. However, the
98th percentile value exceeded the Finnish air quality guideline value of 120
μg/m3 at one monitoring site.
According to leaching studies, the sum of calculated annual airborne pollution impact of water-soluble fraction
(H2O) and environmentally mobile (CH3COONH4) fraction from the
AvestaPolarit Chrome Oy Kemi Mine was Cr 1.2 kg, Fe 29 kg, Cu 63 kg, Ni 2.5 kg and Cd < 100 mg.
According to the homogeneity studies of heavy metal deposition on TSP filters, Cr, Ni, Cu and Fe were non-uniformly distributed over
the glass fibre filters. The rsd values varied between 5.4-33.9 % for Cr, between 7.5-35.0 % for Ni, between 3.6-25.9 % for Cu, and between
6.6-19.9 % for Fe.
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Comparison of MP-AES and ICP-MS for thedetermination of potentially toxic elements in (polluted) plant materialBaysal, Ramazan January 2024 (has links)
The purpose of this study was to assess the metal content present in pine needles collected from an old shooting range known for elevated lead levels in the soil by different analytical methods. The focus on conifers originated from their evergreen nature year-round, and their ability to absorb potentially harmful elements. Research on needles as biomonitors for environmental contamination, particularly in areas affected by heavy metal pollution, has gained significant global attention. Four trees, two Norway spruces (Picea abies), and two Scots pines (Pinus sylvestris) were identified within the designated area. Samples of conifer needles were collected in plastic bags. The needles underwent washing, drying, and grinding into powder for subsequent digestion method and quantitative determination of metal content using ICP-MS and MPAES. The study focused on elements commonly found in various types of ammunition, specifically manganese, iron, nickel, copper, zinc, molybdenum, antimony, and lead. Results obtained from both analytical methods, which was only manganese, showed statistically significant differences. During the analysis, only manganese could be quantified using MPAES, as the other analytes were below the detection limit. For ICP-MS, the LOD values were much lower, making this method more suitable, as all analytes were above LOD and could be quantified. The recovery values for the CRM were good for all elements when ICP-MS was utilized. However, the calculated recovery value for manganese decreased based on the results obtained from MPAES compared to the calculated recovery value for manganese based on the results obtained from ICP-MS. Interestingly, the analysis of conifer needles revealed no noticeable contamination from the shooting range. Instead, it highlighted variances among different pine needle species. The metal content in the pine needles remained within acceptable limits according to external literature sources.
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Aluminum levels in the O-horizon of soils near Sundsvall, Sweden : Are levels of Al elevated due to smelter emission? / Aluminium koncentrationer i jordars O horisont nära Sundsvall, Sverige : Är Al koncentrationerna förhöjda till följd av utsläpp från smältverket?Sundin, Mattias January 2023 (has links)
Aluminum (Al) is a potentially toxic element for humans, animals, and plants. Al emitted from smelter plants is one source of Al that may be responsible for increased exposure to humans and the environment. In this study I investigated whether the Kubikenborg aluminum smelter (Kubal AB) emitted Al to such extent that it can be detected above regional background concentrations in soils and plants. The study was conducted by analyzing O- horizon cores and Scots’ pine (Pinus sylvestris) needles along two transects using X-ray fluorescence spectrometry (XRF). In the O-horizon cores, Al concentrations along the two transects (mean conc. 5250 mg kg-1 in T1 and 3472 mg kg-1 in T2) did not decrease with distance from the smelter. In Scots’ pine needles, Al concentrations (mean conc. 491 mg kg-1 in T1 and 590 mg kg-1 in T2) decreased significantly with distance along transect T2. Aluminum showed high negative co-variance with soil organic matter content (R2 = 0.47) and positive with silicon (Si) and titanium (Ti) in the soil (R = 0.84 and R = 0.86 respectively), suggesting that mineral dust is the main source of Al. However, the Al/Si ratio of the soil decreased with increasing distance from the smelter along T1, indicating a possible additional source of Al besides that of soil dust that may originate from smelter emission. Nevertheless, I found no strong support for detectable Al emissions in humus and Scots’ pine needles near the Kubal AB smelter.
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