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51.
Zhiyuan Hu Jiaqi Zhang Yizhou Du Kangwei Shi Guangqian Ren Babar Iqbal Zhicong Dai Jian Li Guanlin Li Daolin Du 《Journal of Plant Ecology》2022,15(3):509
基质有效性调节加拿大一枝黄花入侵对土壤呼吸的抑制作用
外来植物入侵不仅会降低河边近岸湿地生态系统植被多样性,而且会改变湿地生态系统的地下碳过程。外来入侵植物加拿大一枝黄花(Solidago canadensis L.)已广泛入侵我国东南部地区,但加拿大一枝黄花入侵对入侵地生态系统地下土壤碳循环过程的影响却知之甚少。本研究通过野外原位观测实验和温室模拟入侵实验,探究外来植物加拿大一枝黄花入侵对入侵地土壤呼吸的影响规律及其驱动因素。野 外原位观测实验开展于2018年7月21日至12月15日,期间每周测定样地土壤呼吸。温室模拟入侵实验开展于2019年7月15日至12月15日,期间每月1日与15日上午测定土壤呼吸、自养呼吸和异养呼吸。土壤呼吸、自养呼吸和异养呼吸通过静态箱结合深埋根系隔离法测定。野外原位观测实验和温室模拟入侵实验结果均显示,加拿大一枝黄花的入侵降低了土壤二氧化碳的排放通量。加拿大一枝黄花入侵对土壤呼吸的抑制作用可能归因于其入侵引起的土壤可利用底物质量与数量的变化,表明外来入侵植物加拿大一枝黄花可通过改变植物释放基质以及与本地植物和/或土壤微生物争夺土壤有效基质而影响土壤碳循环。这些研究结果对于评估外来入侵植物对入侵地地下碳动态的影响以及对全球变暖的贡献具有重要意义。 相似文献
52.
53.
《Animal : an international journal of animal bioscience》2022,16(11):100659
Using agricultural by-products such as dehydrated orange pulp (DOP) in animal feeds is of interest to increase pig sector sustainability. With this aim, an assay was carried out to assess the effects of increasing inclusion levels of DOP in pig diets regarding animal performance, carcass quality, and environmental impact. Four experimental diets were designed, a control diet (T1) and three more diets with increasing levels of DOP with 80, 160, and 240 g/kg of DOP for diets T2, T3, and T4, respectively. One hundred and sixty growing pigs were used in the experiment. Growth performance (average daily gain, ADG; average daily feed intake, ADFI and feed conversion ratio, FCR) and in vivo backfat thickness (BF) and loin depth (LD) gain were recorded during the finishing phase (from 70 to 130 kg BW). Faecal samples were incubated for bacteria enumeration. At slaughter, carcass characteristics and meat quality traits were measured, and subcutaneous fat was sampled to analyse the fatty acid (FA) profile. Additionally, the slurry excreted by the animals was measured, characterised and subjected to a gaseous emission assay during its storage. The final BW and overall ADFI, ADG and FCR were similar among treatments. In vivo final LD and BF gain decreased (P ≤ 0.10) as the inclusion level of DOP increased. No differences were observed in carcass characteristics with the inclusion of DOP, except carcass weight that decreased linearly (P = 0.05) with DOP. Regarding the FA profile of the subcutaneous fat, the ratio of total monounsaturated to saturated FA increased with the inclusion level of DOP. Neither slurry excretion and characterisation nor bacterial counts from faeces showed any significant difference among treatments. The inclusion of DOP led to greater CH4 emissions in mg per L of slurry and hour, whereas these differences disappeared when expressed in mg per animal and day. In all, it has been demonstrated that the inclusion of DOP up to 240 mg/kg in pig diets had minor effects on growth performance, carcass quality traits or gaseous emissions from slurry, favouring the circular economy strategy and pig sector sustainability. 相似文献
54.
森林生态系统土壤CO2释放随海拔梯度的变化及其影响因子 总被引:2,自引:0,他引:2
联合国气候框架公约的签署提升了人们对全球变暖、碳循环的关注。土壤CO2释放作为土壤-大气CO2交换的主要途径之一,成为了各国生态学家研究的重点内容。通过对1800~2155m海拔梯度上森林生态系统土壤CO2释放进行研究,揭示了较小空间尺度上土壤CO2释放的变化规律及其控制机制。在研究区域内,随着海拔梯度的增加,森林土壤CO2释放由(1.94±006) μmol m-2 s-1逐渐增加至(2.22±0.07) μ mol m-2 s-1。土壤温度、土壤水分、土壤有机碳(SOC)、全N、全P与土壤CO2释放呈显著正相关(n=14, P<0.05);土壤容重与土壤CO2释放速率呈显著负相关(n=14,P<0.05);土壤pH对土壤CO2释放影响不显著。作为一个复杂的生态学过程,环境因子及其交互作用对土壤CO2释放产生影响,为了减少因子共线性影响,逐步降低因子维数,采用主成分分析(PCA)揭示了土壤温度、土壤水分、SOC、全N、全P、容重6个因子的联合作用,其累积贡献率达到了57%以上;进一步运用逐步回归分析方法,探讨了影响土壤CO2释放沿海拔梯度分布的主导因子,结果表明土壤水分是研究区域森林生态系统土壤CO2释放沿海拔梯度变化的主导因子。 相似文献
55.
Soil carbon sequestration and land use change associated with biofuel production: empirical evidence 下载免费PDF全文
Zhangcai Qin Jennifer B. Dunn Hoyoung Kwon Steffen Mueller Michelle M. Wander 《Global Change Biology Bioenergy》2016,8(1):66-80
Soil organic carbon (SOC) change can be a major impact of land use change (LUC) associated with biofuel feedstock production. By collecting and analyzing data from worldwide field observations of major LUCs from cropland, grassland, and forest to lands producing biofuel crops (i.e. corn, switchgrass, Miscanthus, poplar, and willow), we were able to estimate SOC response ratios and sequestration rates and evaluate the effects of soil depth and time scale on SOC change. Both the amount and rate of SOC change were highly dependent on the specific land transition. Irrespective of soil depth or time horizon, cropland conversions resulted in an overall SOC gain of 6–14% relative to initial SOC level, while conversion from grassland or forest to corn (without residue removal) or poplar caused significant carbon loss (9–35%). No significant SOC changes were observed in land converted from grasslands or forests to switchgrass, Miscanthus, or willow. The SOC response ratios were similar in both 0–30 and 0–100 cm soil depths in most cases, suggesting SOC changes in deep soil and that use of top soil only for SOC accounting in biofuel life cycle analysis (LCA) might underestimate total SOC changes. Soil carbon sequestration rates varied greatly among studies and land transition types. Generally, the rates of SOC change tended to be the greatest during the 10 years following land conversion and had declined to approach 0 within about 20 years for most LUCs. Observed trends in SOC change were generally consistent with previous reports. Soil depth and duration of study significantly influence SOC change rates and so should be considered in carbon emission accounting in biofuel LCA. High uncertainty remains for many perennial systems and forest transitions, additional field trials, and modeling efforts are needed to draw conclusions about the site‐ and system‐specific rates and direction of change. 相似文献
56.
57.
The translocator protein 18 kDa (TSPO) is an attractive target for molecular imaging of neuroinflammation and tumor progression. [18F]PBR06, a fluorine-18 labeled form of PBR06, is a promising PET TSPO radioligand originally developed at NIMH. [11C]PBR06, a carbon-11 labeled form of PBR06, was designed and synthesized for the first time. The standard PBR06 was synthesized from 2,5-dimethoxybenzaldehyde in three steps with 71% overall chemical yield. The radiolabeling precursor desmethyl-PBR06 was synthesized from 2-hydroxy-5-methoxybenzaldehyde in five steps with 12% overall chemical yield. The target tracer [11C]PBR06 was prepared by O-[11C]methylation of desmethyl-PBR06 with [11C]CH3OTf in CH3CN at 80 °C under basic condition and isolated by HPLC combined with SPE purification with 40–60% decay corrected radiochemical yield and 222–740 GBq/μmol specific activity at EOB. On the similar grounds, [18F]PBR06 was also designed and synthesized. The previously described Br-PBR06 precursor was synthesized from 2,5-dimethoxybenzaldehyde in two steps with 78% overall chemical yield. A new radiolabeling precursor tosyloxy-PBR06, previously undescribed tosylate congener of PBR06, was designed and synthesized from ethyl 2-hydroxyacetate, 4-methylbenzene-1-sulfonyl chloride, and N-(2,5-dimethoxybenzyl)-2-phenoxyaniline in four steps with 50% overall chemical yield. [18F]PBR06 was prepared by the nucleophilic substitution of either new tosyloxy-PBR06 precursor or known Br-PBR06 precursor in DMSO at 140 °C with K[18F]F/Kryptofix 2.2.2 for 15 min and HPLC combined with SPE purification in 20–60% decay corrected radiochemical yield, >99% radiochemical purity, 87–95% chemical purity, and 37–222 GBq/μmol specific activity at EOB. Radiosynthesis of [18F]PBR06 using new tosylated precursor gave similar radiochemical purity, and higher specific activity, radiochemical yield and chemical purity in comparison with radiosynthesis using bromine precursor. 相似文献
58.
Variability and application of the chlorophyll fluorescence emission ratio red/far-red of leaves 总被引:1,自引:0,他引:1
Buschmann C 《Photosynthesis research》2007,92(2):261-271
59.
Johannsen B 《Amino acids》2005,29(4):307-311
Summary. Radioactive isotopes are uniquely applicable to observe reactions or circuits of reactions at the molecular level without
disturbing the system being studied. The advent of molecular imaging modalities, particularly positron emission tomography
(PET), is a major breakthrough for the visualisation and quantitative assessment of cellular and molecular processes occurring
in living tissues. The recent development of animal PET scanners that offers 2-mm resolution and is tailored to laboratory
rodent models, has made a further great impact on in vivo biochemistry. With these live-imaging modalities at hand, radiotracer-based technologies allow to look directly at biochemical
distribution and interaction processes. Tremendous progress made in radiotracer chemistry, primarily in carbon-11 and fluorine-18
radiochemistry, and in the design of imaging devices strengthens the usefulness of radiotracers in nuclear medicine and drug
research and development and opens exciting opportunities for new applications, e.g., in food science. 相似文献
60.
Hubert F. Loyke 《Biological trace element research》1992,33(1-3):129-133
With reports of either no change or reduction of blood pressure, the relationship between selenium and blood pressure has
not been clear. Normal Se values are not available for the Sprague Dawley (SD) rat or in the young and adult rat with various
models of experimental hypertension. This study measured serum Se levels in the young and adult normotensive (NT), Grollman
renal hypertensive (RH), and Okamoto-Aoki spontaneous hypertensive rats (SHR). The young animals have statistically significant
(P<0.001) lower Se values as measured by the fluorometric method than those found at adulthood. Selenium levels were found to
be altered in the adult SHR animals when compared with the RH and NT animals. The serum Se value for the normotensive SD rat
was found to be 65.0±3.5 μg/dL, and for the two experimental models, 63.7±4.6 μg/dL for the RH, whereas the SHR level was
elevated to 75.04±4.8 μg/dL (P<0.001). Elevated serum Se values in the adult SHR animals suggests an altered metabolism in SHR animals. 相似文献