江西临川茅排地区金表生地球化学作用研究

本文从水文地球化学角度研究了金的表生地球化学作用，并应用热力学方法计算了茅排地区水中金的存在形式，研究了水溶金的迁移和沉淀条件，得出了一个重要结论：是该区水中金的主要存在形式。在此基础上初步探讨了砂金矿的形成条件。     

The current status ofAtriplexon the Cape Verde Islands

Extensive areas of low lying coastal plains on Santiago Island, Republic of Cape Verde, are virtually devoid of natural vegetation. Of many introduced trees and shrubs, onlyAtriplexspecies have been found to thrive. Several plantations have been established during the past 15 years by the Cape Verde Government, FAO and other agricultural development groups. Results from these, together with local perceptions, indicate that although growth and survival are good, the primary objective of providing forage is not being met, owing to the unpalatability ofAtriplexto local stock. In recent field trials, severalAtriplexspecies showed good growth, but none were browsed and survival was quite poor, with onlyA. undulata(65%) andA. canescens(100%) exceeding 60% survival. Forage analysis identified high salt content in all species tested, and the highest protein content was found inA. glauca(16%),A. vesicaria(17%) andA. canescens(20%), which also had the lowest salt levels.Atriptex canescenswas identified as worthy of further introduction. An establishedA. halimusplantation that was observed to be browsed was compared to unbrowsed stands in terms of forage, soil and local drinking water analyses. Possible reasons for the unpalatability ofAtriplexto local stock and its resolution are discussed, along with the potential future ofAtriplexon the Cape Verde Islands.     

Analysis of raudhas vegetation in central Saudi Arabia

The present study analyses the vegetation of three raudhas in central Saudi Arabia (Kharj, Khuraim and Binban). Seventy-five stands were examined and the martrix of 68 species × 75 stands, based on species cover data, was classified using TWINSPAN and ordinated using DECORANA. Eleven vegetation groups were generated: one dominated byHammada elegansand five dominated byAcaciaspp. (A. iraquensis, A. elatior, A. seyal, A. tortilis-Ziziphus spina-christi-Rhazya strictaandA. abyssinica). TheAcaciaspp. communities represent the climax stage of the xerophytic vegetation in Saudi Arabia and have, in most cases, high species cover and low species diversity. Another five groups are dominated, fully or partly, by species that often inhabit disturbed areas (Prosopis juliflora, Heliotropium bacciferum-Tamarix arabica-Prosopis juliflora-Pulicaria crispa, Ziziphus spinsa-christi-Lagonychium farctum-Alhagi maurorum-Cynodon dactylon, Salsola imbricataandBassia eriophoria-Chloris virgata-Zygophyllum coccineum-Seidlitzia rosmarinus). Many of these groups have low species cover and relatively high species diversity. The effects of environmental factors and human impact on species diversity and abundance of these communities were assessed.     

Comparison of the Concentrations of Chemical Components in Cloudwater Samples Collected during Four Different Field Campaigns

In this study, the results of four different field experiments concerning the speciation of iron and the concentrations of some other chemical compounds in cloudwater samples are compared to one-another. Hydrogen peroxide concentrations were higher during campaigns, conducted at sites not much influenced by anthropogenic emissions as compared to those conducted at more polluted areas. In contrast, percentages of S(IV) in the cloudwater were lowest at the rural sites and highest at the sites polluted by human activities, indicating a consumption of hydrogen peroxide in the oxidation reaction with S(IV). The concentration of dissolved iron was observed to correlate with the percentage of S(IV), which may be an essential point for the reductive dissolution of oxidic iron compounds of the aerosol particles. As far as the speciation of the dissolved iron is concerned, it became obvious that the percentage of Fe(III) is anticorrelated to the concentration of dissolved iron. This clearly shows the important effect of the chemical and/or photo reductive ways of dissolving the iron(III)-compounds from the aerosol particles. However, a correlation between the pH-value and hydrogen peroxide was observed.     

A large daylight geodesic dome for quantification of whole-ecosystem CO2 and water vapour fluxes in arid shrublands

We designed, constructed, calibrated and field-tested a lightweight (30 kg), 4.2 m diameter, 16.4 m³ polyethylene-covered dome static chamber ecosystem gas exchange cuvette that can quantify ecosystem CO₂ and water vapour fluxes as low as 0.1 μmol CO₂ m⁻² s⁻¹ and 0.1 mmol H₂O m⁻² s⁻¹ with little impact on environmental conditions. Fluxes measured in May 2001 in an intact Great Basin sagebrush ecosystem at midday were significantly higher than in an adjacent post-wildfire successional ecosystem, with observed ranges from –0.71 to 1.49 μmol CO₂ m⁻² s⁻¹ for CO₂ and from –0.09 to 0.53 mmol H₂O m⁻² s⁻¹ for water vapour.     

Behavioural response of blackfly larvae (Simuliidae, Diptera) to different current velocities

Video equipment was used to record and to compare the behaviour of different blackfly species at two flow velocities 0.25 m s⁻¹ and 1.35 m s⁻¹. Simulium noelleri Friederichs, Simulium ornatum (complex) Meigen and Simulium variegatum Meigen were studied. Effects of flow velocity on larval locomotive activties were analysed. Looping activity and the time needed to attach for filter feeding again were affectet to some extend, depending on species and flow velocity. While in S. ornatum no differences were recorded in locomotive activity, larvae of S. noelleri and S. variegatum were less active at high flow velocities. Larvae of S. noelleri also moved over shorter distances when exposed to high flow velocities. Consequences of the differences in behavioural response to flow velocities are discussed with respect to drift and silk pad adhesion.     

一种特殊的实时图象处理—图环图象展开

作者在文中给出了一种将圆环域图象展开成矩形图象的方法，这种方法主要采用八分之一圆扫描方法，快速找出某个圆的所有象素，然后通过双线性插值或抽值将其变为展开图中对应的象素。     

Management of the old field vegetation in the Namaqua National Park, South Africa: conflicting demands of conservation and tourism

Springtime mass displays of wild flowers are especially prominent on old fields and other disturbed sites in Namaqualand, an arid region in the north–western part of South Africa. This springtime floral spectacle draws thousands of tourists annually. However, there is a potential conflict between biodiversity conservation and the mass flowering that is a valuable source of income to the region. To develop a management plan for the old field vegetation in the Namaqua National Park, the questions of whether to disturb or not, how often to disturb and what type of disturbance should be applied are of vital importance. The aim of this paper is to report on experimental work to determine the impact of disturbance on mass flowering displays and biodiversity. Results show that although species diversity increased with time since last cultivation, the mass effect of the flowering display diminished. The loss of the mass effect appears to be primarily caused by the increased abundance of a short–lived perennial species ( Leysera gnaphalodes ) that suppressed the flowering display of the prominent annual species. To maintain mass displays as a tourist attraction, regular disturbance by tilling therefore seems essential. Initially, a four–year rotational tilling programme is proposed to produce a mosaic of fields of different ages to ensure that there will always be some old fields producing a spectacular and uncluttered display. Frequency of disturbance should thereafter be determined by an adaptive management policy. If the management of the old field vegetation is seen in the context of conserving total landscape ecodiversity, this includes conserving cultural bio–landscapes and their intrinsic values. Viewed in this context, human–induced disturbance in the small area set aside for mass displays in the Namaqua National Park (less than 0.05% of the park) becomes justified.     

系统矿物学与矿物种

系统矿物学是矿物学领域中的一个分支学科。它是对已发现的全部矿物种的特征及其分类体系进行全面的综合系统研究。它具有完全性、系统性、连续性和阶段性的学科特点。文内分析了1979年底以前的矿物种、1980～1989年新矿物和我国发现的新矿物在系统矿物学晶体化学分类体系中大类和类中的分配,探讨了控制矿物种数的人为因素和自然因素,并提出了系统矿物学当前的迫切任务。     

新疆北部石炭纪单体珊瑚新资料

文中描述的10属10个新种单体珊瑚,全部是小型角锥状、弯锥状,具中轴者居多.系发育边缘厚结带,鳞板不发育的类型.其中Rylstonia,Fasciculiamplexus,Homalophy-llites.and Tetralasma等在新疆属首次发现,不仅丰富了本区石炭纪珊瑚的属种,而且为相关地区石炭纪地层的对比提供了新的依据.同时也证明当时的北极海与我国的北方海槽及华南海是相互沟通的.