临夏盆地13.0~4.3 Ma湖相沉积物中正构脂肪酮记录的古气候演化

本文主要采用气相色谱-质谱分析技术对临夏盆地13.0~4.3 Ma沉积地层剖面样品进行检测,根据样品中正构烷烃、正构脂肪酮-2和正构脂肪酮-3的分布特征,揭示了正构脂肪酮对环境气候的指示意义。正构脂肪酮-2、正构脂肪酮-3与正构烷烃具有相同的有机质来源。其中正构脂肪酮-2的C₂₁^-/C₂₂⁺及正构脂肪-3-酮的C₂₁^-/C₂₃⁺比值变化与地质历史时期的气候与环境条件具有较好的相关性,对环境温度及湿度等变化有一定的指示意义。正构脂肪酮-2、正构脂肪酮-3的高、低碳数优势的转化指示研究区在13.0~4.3 Ma间的古气候具有四个较为明显的变化阶段,其中10.77~9.42 Ma、7.17~6.92 Ma气候由干冷变为暖湿,9.42~7.17 Ma、6.92~6.45 Ma气候由暖湿变为干冷,临夏盆地的干旱化事件指示了我国西北内陆现代干旱气候可能从8 Ma左右开始。     

城中村雨水污水完善改造方案浅析

结合深圳盐田区城中村污水完善改造设计及施工服务中所遇到的问题,提出为彻底解除雨水污水混流现象而采取的措施和方法,以作为今后城中村雨水污水分流制改造过程中的借鉴或参考。     

汶川地震后图书馆的恢复重建与职能发挥

汶川地震给灾区的图书馆事业带来重创,全国图书馆界、灾区各类图书馆及其他相关部门立即行动起来,进行抗震救灾、恢复重建工作.图书馆通过及时地宣传、报道、捐款捐物、对民众进行心理干预、编制发放抗震救灾小册子等行动,再加上国家立法的有力支持,进行自救与协助重建,为夺取抗震救灾的最后胜利充分发挥图书馆的职能作用.     

湖南慈利马尾松树轮宽度对气候的响应及1854年以来冬季极端低温重建

利用采自湖南慈利的马尾松树轮样本,建立研究区的标准树轮宽度年表。树轮气候响应分析发现:马尾松径向生长与月最大日降水量在生长季之前部分月份显著负相关(p0.05),在生长季之内部分月份显著正相关(p0.05),与月平均温度、月平均最低温度、月极端最低温度在生长季之前和之内大多月份均显著正相关(p0.05),其中与上一年11月到当年2月(冬季)的平均极端最低温度相关最好(r=0.62,p0.01)。重建了湖南慈利地区1854年以来冬季极端最低温度,重建气温在十年尺度上表现出明显的反"S"型,1854—1916年和1981—2015年处于暖冬时期,1917—1980年处于寒冬时期。此外,共发现29个寒冬年,其中包括3个寒冬时段,分别为1922—1925年、1927—1930年和1953—1960年,其中1953—1960年是自1854年以来最冷的时段。空间相关性分析表明重建序列可以指示我国中东部的冬季低温变化,而冬季低温可能与热带印度洋、西太平洋海温变化异常有关。     

论长江流域生态危机与生态建设的对策

揭示了长江流域大面积山丘、水系生态系统普遍恶化,特别是中上游地区水土流失严重,以及因此而带来的一系列严重后果。根据史料、统计资料及实测成果等,分析了生态环境恶化的原因,着重研究了水土流失等生态失调现象与森林植被的紧密关系及其演变规律,探讨了进行绿色生态建设的必要性、可能性与可行性。最后提出了建设长江流域防护林体系的宏观战略和微观措施。     

基于重构相空间充填体变形规律的灰色预测研究

尾砂胶结充填体是非线性力学介质,其变形是能量耗散的复杂过程,必须研究其内在变形规律,才能正确预测采矿过程中充填体的稳定性.对不同配比的尾砂胶结充填体进行力学试验,得出了其应力-应变规律,对安庆铜矿高阶段充填体变形进行了监测.采用自适应滤波原理,研究基于重构相空间的测量数据去噪处理方法.用灰色理论研究充填体变形在相空间中相点距离的演变规律,建立了重构相空间的灰色预测模型.为减小预测误差,对预测结果采用残差模型修正.应用建立的模型,对安庆铜矿高阶段充填体变形进行分析,确定了采场合理回采周期.结果表明,充填体变形具有非线性混沌特性,不同配比的充填体表现出不同的非线性动力学行为,重构相空间能充分展示充填体变形的内在规律.     

WTO框架下重构农村公共服务体系的探讨

目前,我国已经加入WTO,由于在谈判过程中我国在农业方面的让步比较大,如果不利用“绿箱政策”加强农村公共服务体系建设,农业和农村经济的竞争力必然大大下降．“绿箱”政策是一种间接式的保护政策,不在《农业协议》限制之列,而且“绿箱”政策中许多条款都涉及到保护本国农业的可持续发展能力,得到了各国的一致赞同．因此,我国有必要对农村公共服务体系的改革与发展历程进行一次系统清理,在此基础上认真总结正反两方面的经验和教训,重新构筑农村公共服务体系．     

Quantifying inconsistencies in old cadastral maps and their impact on land-use reconstructions

ABSTRACT

Old cadastral maps represent a historical reference dataset for long-term land-use reconstructions. This study presents identification of inconsistencies in the nineteenth century Franziscean cadastre, one of the largest sets of old cadastral maps worldwide, by comparing three versions of the maps and written documents created in the same period. We identified all parcels and their land-use in the four sub-sources in six study areas. The overall share of inconsistencies among 5 771 identified parcels is 7.4%, with the biggest share of inconsistency in agroforestry and forestry classes. The most frequent inconsistencies are of ‘Not differentiable land use’ (n = 212) and ‘Different land-use’ categories across the sub-sources (n = 113). We conclude that the frequency of uncertainties in old cadastral maps may limit the validity of historical land-use reconstructions, affecting the eventual restoration and management efforts based on such data. We provide a summary for the use of Franziscean cadastre.     

Extensions to minimum relative entropy inversion for noisy data

Minimum relative entropy (MRE) and Tikhonov regularization (TR) were compared by Neupauer et al. [Water Resour. Res. 36 (2000) 2469] on the basis of an example plume source reconstruction problem originally proposed by Skaggs and Kabala [Water Resour. Res. 30 (1994) 71] and a boxcar-like function. Although Neupauer et al. [Water Resour. Res. 36 (2000) 2469] were careful in their conclusions to note the basis of these comparisons, we show that TR does not perform well on problems in which delta-like sources are convolved with diffuse-groundwater contamination response functions, particularly in the presence of noise. We also show that it is relatively easy to estimate an appropriate value for epsilon, the hyperparameter needed in the minimum relative entropy solution for the inverse problem in the presence of noise. This can be estimated in a variety of ways, including estimation from the data themselves, analysis of data residuals, and a rigorous approach using the real cepstrum and the Akaike Information Criterion (AIC). Regardless of the approach chosen, for the sample problem reported herein, excellent resolution of multiple delta-like spikes is produced from MRE from noisy, diffuse data. The usefulness of MRE for noisy inverse problems has been demonstrated.     

Groundwater conditions under a reconstructed prairie chronosequence

Chronosequences are useful to evaluate long-term changes in ecosystem services but assessing groundwater quality changes using this approach has rarely been done. In this study, groundwater level and quality comparisons were made in a watershed-scale reconstructed prairie chronosequence that extended back in time approximately 13 years at the Neal Smith National Wildlife Refuge (NSNWR) near Prairie City, Iowa. Our objectives were to determine whether groundwater conditions varied significantly across the chronosequence and quantify the rate of nitrate concentration reduction when row crop fields are replaced by prairie. We installed 19 groundwater wells at upland locations selected to provide similar soil type, landscape position and slope. Water samples were collected on five occasions in 2006 and 2007 and analyzed for field parameters, anions and NO₃-N, NH₄-N and PO₄-P. Significant groundwater changes were primarily associated with groundwater levels, and groundwater nitrate and chloride concentrations. The groundwater was deeper under the older prairie plantings but fluctuated similarly among all well sites. Groundwater nitrate and chloride concentrations decreased 0.58 and 0.52 mg/l per year over the 13-year chronosequence, respectively. Results are seen to provide some guidance to land managers regarding possible nitrate concentration reductions achievable from converting cropland to perennial land cover in similar geomorphic settings.