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Background
Evidence of trivalent manganese (Mn3+) in the aqueous phase of soils is unknown so far although this strong oxidant has large environmental implications.Aims
We aimed to modify a spectrophotometric protocol (porphyrin method) and to discriminate between Mn2+ and Mn3+ in the aqueous phase of forest soils based on kinetic modeling.Methods
We investigated manganese speciation in 12 forest floor solutions and 41 soil solutions from an acidic forest site by adjusting pH and correcting for absorbance.Results
The solutions showed broad ranges in pH (3.4−6.3), dissolved organic carbon (DOC, 1.78−77.1 mg C L−1), and total Mn (MnT, 23.9−908 µg L−1). For acidic solutions, a pH-buffer was added to increase the pH of the solutions to 7.5−8.0, and background absorption was corrected for colored solutions, that is, solutions high in DOC. This was done to accelerate the reaction kinetics and avoid overestimation of MnT concentrations. After the pH and color adjustments, the comparison of MnT concentrations between the porphyrin method and optical emission spectrometry showed good agreement. Trivalent Mn, which is stabilized by organic ligands, constitutes significant proportions in both forest floor solutions (10−87%) and soil solutions (0.5−74%).Conclusions
The dissolved Mn3+ is present in acidic forest soils. Thus, we revise the paradigm that this species is not stable and encourage to apply the revised method to other soils. 相似文献103.
Red clover (Trifolium pratense) is an important perennial forage crop that is widely cultivated in Europe. Clover rot remains a major disease in red clover, but resistance breeding is hampered by the lack of available sources of resistance. Moreover, little is known about the factors that influence clover rot resistance. In this paper we evaluated the variation in clover rot susceptibility among a diverse collection of 113 red clover accessions, with the aim of identifying more resistant accessions. Clover rot susceptibility was assessed with a high throughput bio-test on young plants. We found significant variation in clover rot susceptibility, within and among accessions. ‘Tedi’, ‘Maro’ and ‘No 292’ were the most resistant accessions. Fifteen diploid accessions were more susceptible than the average accession with the cultivar ‘Nemaro’ being the most susceptible. Clover rot susceptibility was not correlated with isoflavone levels from Mullaney et al. (Agronomy abstract. ASA, Madison, p 195, 2000). Cultivars were more resistant than landraces and wild accessions and tetraploid cultivars were more resistant than diploid cultivars. Besides the in-depth analysis for clover rot susceptibility, possible correlations with plant architecture and other diseases were investigated. Growth habit, branching, plant yield, flowering date and susceptibility to mildew, virus and rust diseases were investigated in a 3-year field trial. Unlike previously suggested, clover rot susceptibility was not correlated with branching or with plant yield over three years. On the other hand, late flowering accessions and accessions with erect growth habit were less susceptible to clover rot. Clover rot susceptibility was not correlated with susceptibility to rust disease (Uromyces trifolii) or viral diseases, but negatively with susceptibility to mildew (Erysiphe polygoni). Because no completely resistant accessions were found, the best way to improve clover rot resistance would be to select recurrently for resistant genotypes among diverse cultivars and landraces with lower susceptibility. Tetraploidisation of diploid populations with a higher resistance level can provide an additional level of protection. 相似文献
104.
There is a need to accurately estimate the carbon sequestration potential of many of our agricultural and horticultural industries now that the Australian Government has introduced the Carbon Farming Initiative and is planning to introduce an emissions trading scheme in 2015. This study estimates that the carbon sequestration of macadamia plantations is around 3t CO2e/ha/yr, and provides a methodology to assess the carbon footprint of the Australian Macadamia Industry. This study attempts to estimate the growth rate, and subsequently the sequestration rate of plantation grown Macadamia spp. through regression analysis of stem characteristics of destructively sampled Macadamia integrifolia var. 344. A volume increment curve was also derived using three common genetic varieties (A4, A16 & A42). This curve is used to extrapolate a carbon sequestration rate for the national macadamia plantation estate. Once volume estimates and sequestration rates are determined, an economic benefit of the carbon sequestration can be estimated by auditing the amount of carbon produced by activities such as “on farm” fuel use, fuel used in transport, and energy used in producing the product. In this way, a life cycle carbon budget can be developed that will aid the sustainable development of the macadamia and horticultural industries in Australia through the production of carbon credits from the carbon stored in the trees. 相似文献
105.
Tim Waelbers Kathelijne Peremans Simon Vermeire André Dobbeleir Vincent Boer Hendrik de Leeuw Maarten Vente Koen Piron Myriam Hesta Ingeborgh Polis 《Journal of Veterinary Behavior: Clinical Applications and Research》2013,8(6):444-449
Single-photon emission computed tomography (SPECT) can be used to study the regional distribution of the cerebral blood flow in the feline brain without interference of anesthetics. When the tracer, 99mtechnetium-ethyl cysteinate dimer (99mTc-ECD), is injected in the awake animal, the acquisition can be performed afterward under general anesthesia, whereas the tracer distribution still represents the regional cerebral blood flow (rCBF) in the awake animal. The aim of this study was to look at the in vivo stability of 99mTc-ECD in the feline brain. For this purpose, 6 cats (n = 6) were used, and 3 serial acquisitions were performed starting at 40 (T40), 60 (T60), and 85 (T85) minutes after tracer injection. Total counts and perfusion indices (PIs), normalized to the total brain and to the cerebellum, were calculated. When T85 was compared with T40, total counts decreased, depending on the brain region, with 29% (left thalamus) to 51% (bulbus olfactorius). These regional differences in tracer clearance resulted in significantly altered PIs at T85 as compared with T40. This study shows that 99mTc-ECD SPECT can be used in cats for studying the rCBF and that the clearance of 99mTc-ECD in the feline brain is region dependent. As a result, the acquisition should be started between 40 and 60 minutes after tracer injection. 相似文献
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