旅游者践踏对生态旅游景区土壤影响定量研究--以香格里拉碧塔海生态旅游景区为例

文章通过对云南省香格里拉县碧塔海生态旅游景区土壤、植被野外调查,实验室数据分析,构建景区旅游者对土壤践踏影响强度指标体系,建立旅游者沿游径横截面方向的正态分布模型,探寻景区旅游者分布与土壤践踏之间的规律并提出土壤践踏基础容量指标,以此反映自然状态下,生态旅游景区土壤因子对旅游者践踏的适应能力。研究结果将为景区的生态旅游环境管理提供理论依据。     

A NUMERICAL STUDY OF THE WINTERTIME CIRCULATION IN THE BOHAI AND HUANGHAI SEAS

The paper presents a numerical two-dimensional model (with a realistic sea basin and wind fields as exter nal forcing) to simulate the basic features of the wintertime circulation in the Bohai and Huanghai (Yellow) Seas (BHS) and to show how the circulation can be driven by wind. The main results can be summarized as follows (1) The basic features of the BHS wintertime circulation can be depicted by the wind-driven barotropi'c motion. (2) The traditionally named Huanghai Sea Warm Current (HSWC) is actually generated by the north wind field, at least in winter. (3) The southward coastal current off the Korean west coast plays a more significant role in the southern Huanghai Sea wintertime circulation than traditionally believed. (4) Though the coastal landform and bottom topography play important roles in the wintertime BHS circulation pattern, the wind is a primary forcing.     

书法文化的区域初步研究

由回顾地理视角下书法艺术研究的历史入手, 辩析了区域层面上的书法内涵和书法文化概念, 为开展系统的书法文化区域研究奠定了基础。然后由对中国以往书法文化区域研究的评价引出作者所构建的书法文化区域研究的理论框架： 空间维包括 ３ 个方面的内容, 即书法文化的地域空间研究; 书法文化空间相互作用研究; 异质性空间的书法文化研究。时间维着重不同时段书法文化的比较研究, 书法文化的演变态势研究; 实践维则强调从文化景观的角度来研究书法文化并拓展其应用领域。最后又对书法文化区域研究理论展开了实证分析, 尝试用这一理论把世界的书法划分为 ５ 大区域, 即汉文字圈书法文化区, 阿拉伯文字圈书法文化区, 拉丁文字圈书法文化区, 斯拉夫文字圈书法文化区, 印度文字圈书法文化区。     

Experiences with an expert system for gold exploration in Botswana

This article describes initial experiences with an expert system in the scope of an exploration project in Botswana. A simple and easy-to-use expert system shell for personal computers was applied to construct an inference network for epigenetic gold deposits. The main objective, however, was not the automation of human intelligence but the structural analysis of domain knowledge for a target assessment. Aspects of human reasoning are discussed and compared with machine reasoning. Some actual problems concerning the inversion of rules under uncertainty, contrary evidences, and prior probabilities are discussed. Technical aspects like costs and schedule are included in the exploration model. Three different approaches for constructing an inference network are described.     

1930s-2000年广西地区石漠化分布的变迁

根据民国时期《广西省各县石山林木保护办法》中对石山的定义,对应目前石漠化等级划分方法,把该时期的石山区解读为轻度及以上石漠化分布地区.通过对1930s国民政府参谋本部陆地测量总局编绘的1:10万广西省地形图上所绘石山范围进行数字化,并与2000年广西壮族自治区石漠化分布现状图进行比较,揭示了近70年来广西地区石漠化分布在空间上的变化.研究表明:① 1930s广西地区轻度及以上石漠化面积为31922.25 km²,比2000年的27123.21 km²多出4799 km²,说明民国时期广西地区轻度及以上石漠化土地分布范围比当代的大,但在空间变迁上表现出此增彼减的变化特点;② 2000年的数据中有47个县石漠化面积比1930s的少,减少的总面积为9045.5 km²,集中分布在广西西部和中部,都安瑶族自治县的变化最明显,近70年内减少了894.8 km²;③ 2000年有30个县的石漠化面积比1930s的多,共增加了4246 km²,集中分布在广西东北部,其中全州县增加了556.55 km².     

青藏高原湖泊沉积与环境演变研究：现状与展望

从空间尺度、不同时间尺度、重大气候环境变化事件、与其他研究结果的对比以及代用指标与气候要素的定量关系研究等几个方面总结了近十余年来青藏高原湖泊沉积与环境演变研究的主要成果。目前在高原上开展的湖泊沉积与环境演变研究主要分布在三个较为集中的地区：高原东北边缘区、高原西部西昆仑山湖泊群和高原中南部湖泊群。已有的湖泊沉积记录主要是以中长时间尺度的研究为主，而短时间尺度高分辨率的研究稍显不足。与其他地区全球变化研究结果的对比表明，湖泊沉积所反映的高原气候环境变化既具有全球性，又具有区域性的特征。湖泊沉积重建的环境序列的定量化研究仍处于探索阶段。由于湖泊沉积的环境代用指标存在着相对多解性，因此在实际研究中多学科交叉、多指标分析的方法是必需的。当前和今后需要深入开展环境代用指标与气候要素之间定量关系的研究，进一步提高沉积物定年的精确性，发现新的更为敏感的环境代用指标，不断完善多学科多环境代用指标的综合分析，并注重填补不同区域不同时间尺度的研究空白，加强高原上不同区域之间的对比研究。     

Dissolved Organic Carbon in Seepage Water – Production and Transformation during Soil Passage

Dissolved organic carbon (DOC) in seepage water can combine with organic pollutants, with Al and heavy metal ions and transport them through the soil profile with a potential to contaminate groundwater. We studied the production of DOC in aerobic decomposition experiments at 8 °C and moisture close to field capacity in soils from two sites with different microbial activities (spodic dystric Cambisols with moder (SLB) and mor‐moder (SLS) layers) using ¹³C‐depleted plants of differing decomposability (Epilobium angustifolium and Calamagrostis epigeios). Additionally, we investigated the DOC transformation during soil passage in decomposition experiments and in the field for the sites SLB and SLS. For SLS, decomposition of Epilobium resulted in a cumulative CO₂ production of 14% of the added C within 128 days. Priming effects were negligible. CO₂ production for the experiments using Calamagrostis was less with 11% for SLB and 10% for SLS. Cumulative DOC production was markedly high in the Epilobium decomposition experiment, being 25 g m^–2, out of which 11 g m^–2 were Epilobium‐derived (2% of the added C). For the Calamagrostis experiments, cumulative productions of DOC and Calamagrostis‐derived DOC (0.1% of the added C for SLS and SLB) were much less. During the soil passage, much of the DOC was removed by sorption or decomposition processes. Field studies at SLS and SLB using ¹³C natural abundance showed that ¹³C distribution of soil organic matter increased with depth, probably mainly due to a discrimination of C isotopes by decomposing microorganisms. DOC, however, showed a depletion of ¹³C from –28γ PDB to –29γ (SLB at 40 cm) or –28 to –30γ (SLS at 20 cm) with depth, owing to preferential decomposition of ¹³C‐enriched substances or preferential adsorption. This study indicates that DOC production is strongly affected by litter composition and that significant changes in DOC composition may occur during its passage through a soil depth of 40 cm.     

Effects of base geogrid on geocell-reinforced foundation beds

The effect of a base geogrid layer below the geocell mattress in sand, sand overlying soft clay, and soft clay foundation beds has been studied using a series of laboratory scale load tests. A rigid circular model footing was used to apply static monotonic loading on the foundation beds with and without geocell reinforcement. The model test results show that the provision of an additional layer of planar geogrid at the base of the geocell mattress further increases the performance of the footing in terms of bearing capacity and reduction in surface heave of the foundation bed. It is also observed that the beneficial effect of the base geogrid layer becomes negligible with increasing height of the geocell mattress beyond the influence of the depth of the footing. Strain measurements in the base geogrid layer indicate that it is more effective with the limited heights of the geocell mattress. The earth pressure cells embedded in the subgrade soil provide evidence that when the base geogrid is provided below the geocell mattress, the footing pressure is distributed more uniformly over an extended area.     

近50年来山东城市体系的演化过程--基于城市中心性的分析

在前人工作的基础上,在简单讨论已有的相对中心性测度方法的基础上,根据研究目的对Tietz公式进行了一定的补充。利用1955年私营商业调查,1982年和2000年人口普查数据,通过NegF法和SumF法分析了近50年山东省中心城市的分布,及其紧密腹地、松散腹地的变动,勾勒出了1955年到2000年山东城市体系的动态演化过程。认识到山东省城市体系的发展是一个逐步复杂化、有序化的过程,由分别以青岛和济南为中心城市的两个子体系逐步演化至以青岛为中心城市的单一共同体系。在这一过程中,中心城市的等级性逐渐显化。     

辽东湾粒状海冰弯曲力学行为试验研究

弯曲破坏是冰与船舶和锥形海洋结构物相互作用时经常发生的一种冰破坏模式。全球变暖延长了渤海海冰的冻结期,导致冰层中粒状冰的比例呈增加趋势。为了更好地理解渤海粒状海冰的弯曲力学行为,使用2010－2011年冬季在辽东湾收集的粒状海冰进行了实验室三点弯曲试验。在?5、?10和?15°C条件下,共测试了42个海冰试样。应变速率范围为1×10?6~6×10?4 s?1,加载方向垂直于原始冰面。在试验过程中,测量每个冰试样的盐度和密度以计算孔隙率。试验分别给出了弯曲强度和有效弹性模量关于孔隙率的参数化关系,归一化后,弯曲强度在整个应变速率范围内没有速率依赖性。相比之下,有效弹性模量随着应变速率的增大而增大。以孔隙率和应变速率为因子,建立了冰试样有效弹性模量的参数化方程。