从第31届国际地质大会命题看：地球科学研究的热点和趋势

本文论述了第 31届国际地质大会学科和专题命题情况 ,统计了大会收到的论文和摘要数并将各命题重新排序。将位于前 12位的学科和前 5位的专题命题进一步列出重点讨论题目和摘要数。通过与第 30届国际地质大会命题的比较 ,试图大致了解国际地球科学研究的热点和趋势 ;通过上述分析和了解 ,就地球科学与可持续发展阐述了笔者的认识 ,提出了地球科学基础性研究和应用基础研究的重点领域     

Understanding conservationists’ perspectives on the new‐conservation debate

A vibrant debate about the future direction of biodiversity conservation centers on the merits of the so‐called new conservation. Proponents of the new conservation advocate a series of positions on key conservation ideas, such as the importance of human‐dominated landscapes and conservation's engagement with capitalism. These have been fiercely contested in a debate dominated by a few high‐profile individuals, and so far there has been no empirical exploration of existing perspectives on these issues among a wider community of conservationists. We used Q methodology to examine empirically perspectives on the new conservation held by attendees at the 2015 International Congress for Conservation Biology (ICCB). Although we identified a consensus on several key issues, 3 distinct positions emerged: in favor of conservation to benefit people but opposed to links with capitalism and corporations, in favor of biocentric approaches but with less emphasis on wilderness protection than prominent opponents of new conservation, and in favor of the published new conservation perspective but with less emphasis on increasing human well‐being as a goal of conservation. Our results revealed differences between the debate on the new conservation in the literature and views held within a wider, but still limited, conservation community and demonstrated the existence of at least one viewpoint (in favor of conservation to benefit people but opposed to links with capitalism and corporations) that is almost absent from the published debate. We hope the fuller understanding we present of the variety of views that exist but have not yet been heard, will improve the quality and tone of debates on the subject.     

Discounting in the presence of scarce ecosystem services

The discount rate for cost-benefit analysis has to take account of future scarcity of ecosystem services in consumption and production. Previous literature focuses on the first aspect and shows the importance of the relative price effect, for given growth rates of consumption and ecosystem services. This paper focuses on intermediate ecosystem services in production and shows that for limited substitutability and a low growth rate of these ecosystem services, the growth rate of consumption, and thus the discount rate, declines towards a low value. Using a Ramsey growth model, the paper distinguishes three cases. If ecosystem services can be easily substituted, the discount rate converges to the usual value in the long term. Secondly, if ecosystem services can be easily substituted in production but not in consumption, the relative price effect is important. Finally, and most interestingly, if ecosystem services cannot be easily substituted in production, the discount rate declines towards a low value and the relative price effect is less important. Another part of the previous literature has shown that a declining discount rate is the result of introducing several forms of uncertainty, but this paper reaches that conclusion from an endogenous effect on the growth rate of the economy.     

模拟气候升温对湿地土壤微生物群落及磷素形态的影响

通过构建微宇宙湿地柱模拟气候升温的方法,采用高通量测序和核磁共振技术,分别研究了湿地土壤微生物群落和磷素形态对暖化作用的响应特征.结果表明,暖化作用导致了Firmicutes、Clostridia、Clostridiales、Clostridiaceae和Clostridium的相对丰度分别显著下降65%~98%、69%~87%、67%~87%、73%~97%和74%~93%,这表明暖化作用对不同分类水平上的物种Firmicutes到Clostridium具有显著的抑制效应.通过主坐标分析和聚类分析,不同湿地柱采样点的暖化组与对照组样本表现出显著的分离特征,揭示了暖化作用能够诱导微生物群落组成发生显著性变化.磷酸单酯和正磷酸盐是各湿地柱土壤主导的磷素形态,同时暖化作用导致了XX湿地柱采样点的磷酸单酯和正磷酸盐相对丰度分别显著升高275%和下降20%,JH湿地柱采样点的磷酸单酯和多聚磷酸盐相对丰度分别显著升高85%和下降49%,这表明不同磷素形态对暖化作用的响应具有土壤异质性特征.通过典型对应分析,揭示了暖化条件下微生物群落组成的显著变化对磷素形态具有显著的影响效应.     

基于液相31P核磁共振(NMR)技术的巢湖沉积物中有机磷形态研究

利用改进的沉积物有机磷提取方法和液相31P核磁共振(NMR)分析方法,研究了巢湖表层沉积物有机磷形态.结果表明:西部湖区表层沉积物总磷含量高于东部湖区,其平均含量分别为(1089.82±108.14) mg·kg-1和(497.80±51.59) mg·kg-1;东部湖区沉积物中有机磷百分含量(31.88％±2.41％)高于西部湖区(20.86％±1.65％);表层沉积物主要磷份组成包括膦酸盐(Phon-P)、正磷酸盐(Ortho-P)、磷酸单酯(Mono-P)、磷脂(Lipid-P)、DNA(DNA-P)、焦磷酸盐(Pyro-P);磷酸单酯为有机磷的主要组分,平均含量占总磷的22.12％±5.32％;磷酸单酯和DNA百分含量东部湖区大于西部湖区,磷酸单酯百分含量分别为25.99％±2.29％和16.30％±1.06％,DNA百分含量分别为5.61％±0.24％和3.85％±1.01％.31P核磁共振技术可以有效的应用于巢湖等富营养化湖泊沉积物磷形态分析;巢湖表层沉积物以无机磷为主,有机磷种类丰富,以磷酸单酯为主.     

Speciation of organic phosphorus in a sediment profile of Lake Taihu II. Molecular species and their depth attenuation

The understanding of organic phosphorus(P) dynamics in sediments requires information on their species at the molecular level,but such information in sediment profiles is scarce.A sediment profile was selected from a large eutrophic lake,Lake Taihu(China),and organic P species in the sediments were detected using solution phosphorus-31 nuclear magnetic resonance spectroscopy(31 P NMR) following extraction of the sediments with a mixture of 0.25 mol/L NaOH and 50 mmol/L EDTA(NaOH-EDTA) solution.The results showed that P in the NaOH-EDTA extracts was mainly composed of orthophosphate,orthophosphate monoesters,phospholipids,DNA,and pyrophosphate.Concentrations of the major organic P compound groups and pyrophosphate showed a decreasing trend with the increase of depth.Their half-life times varied from 3 to 27 years,following the order of orthophosphate monoesters > phospholipids DNA > pyrophosphate.Principal component analysis revealed that the detected organic P species had binding phases similar to those of humic acid-associated organic P(NaOH-NRP HA),a labile organic P pool that tends to transform to recalcitrant organic P pools as the early diagenetic processes proceed.This demonstrated that the depth attenuation of the organic P species could be partly attributed to their increasing immobilization by the sediment solids,while their degradation rates should be significantly lower than what were suggested in previous studies.     

Investigation on the changes effected by tool profile on mechanical and tribological properties of friction stir processed AZ31B magnesium alloy

The present study investigates the effect of tool shoulder profile on the mechanical and tribological properties of friction stir processed AZ31B magnesium alloy. The tool rotational speed and feed rate are the chosen process parameters. The experiments were conducted with 3 level 2 factors full factorial design. The recorded responses were tensile strength, wear losses and corrosion rate. The results were analyzed with the help microstructures of the processed samples. The study reveals that, for concave shoulder tool, the strain hardening effect was playing a major role in determining the properties of the processed materials and for the step shoulder tool, the grain size plays a major role in determining the properties of the processed materials.     

储罐钢08MnNiVR和SPV490Q在石油沉积水中腐蚀性能对比

采用电化学试验、浸泡试验和慢应变速率拉伸试验研究储罐钢08MnNiVR和SPV490Q在石油沉积水中的腐蚀性能差异。电化学试验结果表明,08MnNiVR在石油沉积水中的自腐蚀电流比SPV490Q略大。浸泡试验结果表明,中短期试验时,08MnNiVR的腐蚀率略大;较长期试验时,SPV490Q的腐蚀率略大。慢应变速率拉伸试验结果表明,08MnNiVR和SPV490Q在石油沉积水中均具有高应力腐蚀抗力。     

Scale-up modeling of the twin roll casting process for AZ31 magnesium alloy

In the present study, a 2-D finite-element method (FEM) thermal-fluid-stress model has been developed and validated for the twin roll casting (TRC) of AZ31 magnesium alloy. The model was then used to quantify how the thermo-mechanical history experienced by the strip during TRC would change as the equipment was scaled up from a laboratory size (roll diameter = 355 mm) to a pilot scale (roll diameter = 600 mm) and to an industrial scale (roll diameter = 1150 mm) machine. The model predictions showed that the thermal history and solidification cooling rate experienced by the strip are not affected significantly by caster scale-up. However, the mechanical history experienced by the strip did change remarkably depending on the roll diameters. Casting with bigger rolls led to the development of higher stress levels at the strip surface. The roll separating force/mm width of strip was also predicted to increase significantly when the TRC was scaled to larger sizes. Using the model predicted results, the effect of both casting speed and roll diameter was integrated into an empirical equation to predict the exit temperature and the roll separating force for AZ31. Using this approach, a TRC process map was generated for AZ31 which included roll diameter and casting speed.     

Challenges with eradicating illegal mining in Ghana: A perspective from the grassroots

This paper argues that artisanal mining communities are somewhat bound to their operations, and helps explain why formalisation, alternative livelihood projects and military intervention—the traditional strategies employed by governments to tackle illegal mining—have proved ineffective. Findings from recent research carried out in Noyem (Eastern Region of Ghana) are used to illustrate why illegal artisanal mining is such a deeply rooted activity in sub-Saharan Africa. The analysis provides four explanations in support of this: a heavy involvement of traditional leaders in operations; the mindsets of many operators toward alternative income-earning activities; the numerous and diverse range of employment opportunities provided by the sector; and the level of investment in operations.