用动态时间序列周期分析预测模型作郑州汛期降水预报

动态时间序列周期分析预测模型是将多层递阶方法与逐步回归周期分析的基本原理相结合,可以有效地选取时间序列的各个隐含周期。利用所选取的隐含周期,可作更长时间的预测。本文以郑州汛期降水为样本,对该预测模型进行了应用及讨论。     

Mercury speciation in soil in vicinity of coal beds using sequential extraction

The sequential extraction procedure was proposed and used to study of mercury speciation in real samples of soil. Samples of soil profiles together with bedrock and coal were taken from sampling spots in the vicinity of surficial coal beds in an area with natural coal outcrops. The proposed sequential extraction procedure involves the following fractionation: organic mercury compounds, extractable mercury in an acidic medium, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS and residual mercury. The significant distribution of mercury between the two portions—mercury bound to humic substance and HgS was determined in the majority of samples. The mercury bound to humic substances created a significant contribution, especially to the top layer of soil. On the other hand, HgS was the dominant form in the samples from lower layers of the soil profile. The mercury content in the samples did not show a distinct mobility. The influence of soil parameters on the mercury distribution in the studied samples was investigated and discussed.     

Response of the coccolithophores Emiliania huxleyi and Coccolithus braarudii to changing seawater Mg and Ca concentrations: Mg/Ca, Sr/Ca ratios and δCa, δMg of coccolith calcite

Calcium and magnesium concentrations in seawater have varied over geological time scales. On short time scales, variations in the major ion composition of seawater influences coccolithophorid physiology and the chemistry of biogenically produced coccoliths. Validation of those changes via controlled laboratory experiments is a crucial step in applying coccolithophorid based paleoproxies for the reconstruction of past environmental conditions. Therefore, we examined the response of two species of coccolithophores, Emiliania huxleyi and Coccolithus braarudii, to changes in the seawater Mg/Ca ratio (≈0.5 to 10 mol/mol) by either manipulating the magnesium or calcium concentration under controlled laboratory conditions. Concurrently, seawater Sr/Ca ratios were also modified (≈2 to 40 mmol/mol), while keeping salinity constant at 35. The physiological response was monitored by measurements of the cell growth rate as well as the production rates of particulate inorganic and organic carbon, and chlorophyll a. Additionally, coccolithophorid calcite was analyzed for its elemental composition (Sr/Ca and Mg/Ca) as well as isotope fractionation of calcium and magnesium (Δ^44/40Ca and Δ^26/24Mg). Our results reveal that physiological rates were substantially influenced by changes in seawater calcium rather than magnesium concentration within the range estimated to have occurred over the past 250 million years when coccolithophores appear in the fossil record. All physiological rates of E. huxleyi decreased at a calcium concentration above 25 mmol L⁻¹, whereas C. braarudii displayed a higher tolerance to increased seawater calcium concentrations. Partition coefficient of Sr was calculated as 0.36 ± 0.04 (±2σ) independent of species. Partition coefficient of Mg²⁺ increased with increasing seawater Ca²⁺ concentrations in both coccolithophore species. Calcium isotope fractionation was constant at 1.1 ± 0.1‰ (±2σ) and not altered by changes in seawater Mg/Ca ratio. There is a well-defined inverse linear relationship between calcium isotope fractionation and partition coefficient of Sr²⁺ in all experiments, suggesting similar controls on both proxies in the investigated species. Magnesium isotope ratios were relatively stable for seawater Mg/Ca ratios ranging from 1 to 5, with a higher degree of fractionation in Emiliania huxleyi (by ≈0.2‰ in Δ^26/24Mg). Although Mg/Ca ratios in the calcite of coccolithophores and foraminifera are similar, the former have considerably higher Δ^26/24Mg (by >+3‰), presumably due to differences in calcification mechanisms between the two taxa. These observations suggest, a physiological control over magnesium elemental and isotopic fractionation during the process of calcification in coccolithophores.     

基于SWAT模型的典型农业小流域氮污染时空分布特征及关键源解析

水资源恶化、水体富营养化严重威胁生态环境健康,农业活动所产生的氮是造成水污染的主要原因之一.本研究以句容水库农业流域为研究对象,基于实地监测数据验证了SWAT模型模拟当地氮污染的适用性,并分析了氮素负荷的时空分布特征及其关键源.结果 表明:硝态氮(NO3-N)和总氮(TN)的年均入库量分别为9.98和27.22 t.时...     

论人类健康可持续发展

健康是人类生存和发展的基础,提高人类健康水平是可持续发展的一项重要目标。在可持续发展系统内,人类健康是判断人与自然以及人与人之间关系和谐与否的标尺;人类健康可持续发展是人类杜会可持续发展的基础。人类健康可持续发展要求在满足当代人健康需求的同时又不损害后代人满足其健康需求的能力;在满足本区域人群健康需求的同时又不损害其他区域满足其人群健康需求的能力;在促进生态、经济、社会朝可持续方向发展的同时,自身在生理、心理、社会幸福感方面也获得全面发展。现代文明发展道路应是生产发展、生活富裕、生态良好、生命健康的发展道路。     

Absorption of gamma-rays by X-ray photons around an accretion binary source

Simulation calculations have been made to examine the modification effect of a hot X-ray photon field on a-ray spectrum by the photon-photon pair production and inverse Compton scattering processes. The Cyg X-3 system was used as a paradigm. It is shown that a-ray spectrum can change significantly when passing through the ambient keV X-ray photon field of an accretion binary source. For Cyg X-3, a significant amount of r-rays originated near the central source in the range of 10²-10⁴ MeV could be absorbed by the extended X-ray photons from accretion disk corona in a high X-ray luminosity state and, on the other hand, the inverse Compton effect of secondary electrons could cause a considerable increase in intensity of-rays between ~ 10 MeV and ~ 50 MeV. The relevance of the absorption effect for observations is discussed.     

Benützung von Kulturen in der Blaualgentaxonomie

Ohne Zusammenfassung     

Geochemical and mineralogical control on the mobility of arsenic in a waste rock pile at Dlouhá Ves,Czech Republic

A waste rock pile with initial high sulfide (10–20 wt.%) and low carbonate content (1–2 wt.%) located at Dlouhá Ves in the Czech Republic has been investigated in two profiles (excavation and outcrop) using powder X-ray diffraction, electron microprobe analysis, bulk composition analysis and Mössbauer spectroscopy. The mobility of arsenic and other contaminants was evaluated by leaching experiments. The primary source of the arsenic was arsenopyrite, which was significantly oxidized in both profiles. The principal As-bearing phase at the excavation profile was goethite, located at the top of the profile, and minerals of the jarosite group which were found down to its base. Melanterite, rich in copper and zinc, was found in a sulfide-rich, lower part of the profile together with anglesite. At the outcrop profile, minerals of the jarosite–beudantite group, scorodite and kaňkite prevail and no Fe(II)-minerals were found. The paste pH was lower at the excavation profile (minimum about 1.9) than at the outcrop profile (minimum of about 2.8). Processes in the pile are affected by the pyrite/arsenopyrite ratio, where high pyrite content decreases the As/S ratio and results in the formation of jarosite group minerals and low pH conditions. Where arsenopyrite predominates, sulphides are coated by scorodite and other Fe–As phases like schwertmannite, which limit their further oxidation.     

融合空间尺度特征的时空序列预测建模方法

假定原始的时空数据由较大尺度下的全局趋势项与较小尺度下的局部偏差项构成,提出了融合空间尺度特性的时空序列建模方法。首先,将原始数据转换为较大尺度下的数据,此部分反映原始数据的趋势特征。然后,将趋势部分剔除,剩余部分反映原始数据的偏差特征。最后,用灰色系统模型和BP神经网络模型分别对趋势项和偏差项建模,它们的组合预测结果即为原始时空序列预测值。采用该方法对实际的年降水数据以及日平均PM2.5浓度数据进行预测建模分析,实验结果表明:融合空间尺度特性的时空序列预测模型可以用于多空间尺度预测,并且预测精度优于不考虑空间尺度特性的建模方法。