建设创新型建筑业任重道远

在日前举办的首届建筑经济高峰论坛上，叶耀先教授就中国建筑业的技术进步和创新型企业的建立等有关问题接受了本刊的采访。叶教授在介绍中国建筑业情况时谈到，近几年来，中国建筑业的总产值所占份额逐年任提升，建筑业的就业人数占全国就业总人数的比重逐年增加，建筑业对其它行业的拉动作用在逐年增大，据不完全统计，建筑业每增加一亿元的产值，整个社会的总产值增加三亿元。     

Mobility of heavy metals as a function of pH of samples from an overbank sediment profile contaminated by mining activities

Parts of the flood plains north of the Harz Mountains are contaminated with heavy metals, such as Pb, Cu, Zn and Cd derived from mining, which has been carried out in the Harz Mts. since the Middle Ages. It is important to know the mobility of the heavy metals in these overbank sediments in order to estimate the danger to the environment arising from this source. This paper deals with the effect of pH on heavy-metal mobility, using a constant-pH method. The investigations were carried out on an overbank sediment profile near Salzgitter Bad, north of the Harz Mts. The mobility of the heavy metals in the overbank sediment profile is described as a function of pH and depth. Besides the mobile heavy-metal fraction at a certain pH, the buffering capacity of the sediment at this pH must be taken into consideration. The different layers of the overbank sediment profile show distinct differences in buffering capacity and a natural pH harrier could be identified in the upper part of the profile. Therefore, to avoid increasing heavy-metal mobility the natural layering of the overbank sediment profile should not be disturbed. Two different kinds of desorption experiments at constant pH are also discussed, as well as the conversion of the heavy-metal species in the ore minerals into the species in the sediment.     

Algal lipids as a possible contributor to the polymethylene chains in kerogen

Lipid fraction and cell-wall materials have been separated from three types of algae (blue green, Microcystis sp.; green, Scenedesmus sp. and diatomaceous Diatoma sp.) and their KMnO₄ oxidation products (aliphatic $\text{α,ω-C}{}_2\text{-C}{}_{12}$ dicarboxylic acids; aliphatic normal C₁₄–C₂₄ monocarboxylic acids; benzoic acid and C₁₈ isoprenoidal ketone) examined by gas chromatography and gas chromatographymass spectrometry. The results suggest that the lipid material could make a greater contribution to polymethylene chains in kerogen than the cell-wall material, when the kerogens are mainly derived from algal components.     

Influence of small-scale gold mining and toxic element concentrations in Bonsa river,Ghana: a potential risk to water quality and public health

A preliminary assessment of toxic element pollution caused by artisanal and small-scale gold mining in the Bonsa river of Ghana as well as the influence of TOC and SO₄ ^2? concentration on these traces in the sediment has been determined. With the exception of mercury (Hg), manganese (Mn), and arsenic (As), the concentration of aluminum (Al) in filtered river water exceeded the WHO guideline limit of 0.1 mg L^?1 in drinking water. Analyses of toxic element in sediment using Canadian Sediment Quality Criteria, contamination factor, geoaccumulation index, and enrichment factor indicate that river sediment is severely contaminated with Hg confirming the negative impact of the amalgamation technique in gold beneficiation in Ghana. The level of Hg in the surface water exceeded reported values from some rivers in Africa, Asia, and South America. The ranking order of the mean element concentration in both matrices followed the conservative order of traces found in the Earth crust except copper, which was below the detection limit of 0.01 mg kg^?1. A Pearson correlation matrix of the toxic element and geology of the river bedrock indicates that the Hg contamination is of anthropogenic origin whilst As, Mn, and Al are the result of natural enrichment. The partitioning of elements in the sediment compartments is independent of TOC and SO₄ ^2? concentration. Health-risk assessment based on average daily dose, hazard quotient, and cancer risk indicates that Hg is a health risk to the human population. In conclusion, the study has shown that there is a likely anthropic affection of the river and that this situation has worsened since earlier studies. In order to sustain aquatic life and to prevent future human health hazard, an immediate mercury remediation in the river is recommended.     

Variations in carbon and oxygen isotope ratios as a possible guide to ore

Contour maps showing variations in carbon and oxygen isotope ratios may be useful as a guide to ore. Previous literature suggests that the isotopic composition of carbon is related to the environment in which it is deposited. Sedimentary syngenetic ore deposits are also related to the depositional environment in which they occur and should therefore be related to the isotopic composition of the carbon deposited along with the ore. Although metamorphism may obscure palaeontological and stratigraphic indicators of environment, the isotopic composition of organic carbon appears to be unaffected by it. Previous literature suggests that variations in oxygen isotopes can be used also as a guide to certain epigenetic ore deposits.

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Zusammenfassung Isotopenverteilungskarten sind nützliche Hilfsmittel bei der Erzprospektion. In der Literature wird auf die Abhängigkeit der Isotopen-Zusammensetzung vom Ablagerungsmilieu aufmerksam gemacht. Sedimentäre syngenetische Erzlagerstätten sind ohne Zweifel vom Ablagerungsmilieu abhängig. Es liegt deshalb nahe, die Isotopen-Zusammensetzung des darin enthaltenen Kohlenstoffs mit derjenigen der erzbildenden chemischen Elemente zu vergleichen. Obwohl metamorphe Prozesse paläontologische und stratigraphische Prozesse verwischen können, scheint die Isotopen-Zusammensetzung davon unbeeinflußt zu bleiben. Als Hilfsmittel können weiterhin die in der Literatur beschriebenen Isotopenverhältnisse des Sauerstoffs herangezogen werden.

     

Evaluation of cold-water carbonates as a possible paleoclimatic indicator

The common belief currently shared by many geoscientists concerning the climatic interpretation of limestones is that a warm-water environment is essential. This concept is not necessarily true because the rate and extent of terrigenous sediment dilution, rather than water temperature, is the primary factor determining whether or not a limestone forms at nearshore or continental shelf depths. Because carbonate productivity is lowest in cold climates, however, CaCO₃ abundance and the thickness of carbonate accumulations tend to be least at high latitudes. In this regard present-day continental shelves and beaches offer a poor model for comparing cold-water and warm-water carbonates because of the generally emergent continental tectonic framework, recent eustatic sea-level changes, and the presence of ice caps at the modern poles.Typically, the influence of climate on non-reef continental shelf and beach environments cannot be clearly distinguished by the presence or absence of major taxonomic groups. Faunal diversity and equitability are more sensitive in this regard. The absence of shelf-depth inorganic carbonate precipitates, micrite envelopes, and peloids may also point to the cold-water origin of a rock. Skeletal mineralogy and oxygen isotopes of certain unrecrystallized carbonates may be good paleoclimatic indicators; however, trace elements and physical-textural attributes of the carbonate fraction are probably temperature insensitive.Previous studies of high-latitude continental shelves have concentrated merely on the abundance of calcareous material and there is seemingly a disproportionate amount of information with respect to low-latitude carbonate studies. Further research on cold-water carbonates may open up new avenues for alternative paleoenvironmental and paleoclimatic interpretations.     

Lateritisation as a possible contributor to gold placers in Nilambur Valley, southwest India

Panning for placer gold in the river beds of Punna Puzha and Chaliyar Puzha in the Nilambur Valley, southwest India, has been in vogue among the local people for the last few centuries. The auriferous quartz veins and reefs associated with the Precambrian migmatitic gneisses of the region had been mined for several years. Of late, Au is also being recovered from the laterite matrix of gravels in the old river terraces and from the residual laterites overlying the gneisses. The size of Au nuggets associated with the laterites is much higher (0.5 mm) than that of the Au in vein quartz (0.2 mm) and the associated heavy minerals in the placers (0.2 mm). The Au nuggets show surface and internal textures characteristic of redeposition under low-temperature conditions. Our field and laboratory investigations suggest that dissolution, transport and redeposition of Au occurred in Nilambur concomitant with the lateritisation process.     

On radon emanation as a possible indicator of crustal deformation

Radon emanation has been monitored in shallow capped holes by a Tracketch method along several active faults and in the vicinity of some volcanoes and underground nuclear explosions. The measured emanation shows large temporal variations that appear to be partly related to crustal strain changes. This paper proposes a model that may explain the observed tectonic variations in radon emanation, and explores the possibility of using radon emanation as an indicator of crustal deformation. In this model the emanation variation is assumed to be due to the perturbation of near-surface profile of radon concentration in the soil gas caused by a change in the vertical flow rate of the soil gas which, in turn, is caused by the crustal deformation. It is shown that, for a typical soil, a small change in the flow rate (3 · 10⁻⁴ cm sec⁻¹) can effect a significant change (a factor of 2) in radon emanation detected at a fixed shallow depth (0.7 m). The radon concentration profile has been monitored at several depths at a selected site to test the model. The results appear to be in satisfactory agreement.     

Continental weathering as a possible origin of vein-type uranium deposits

Geochemical and geochronological data presently available, concerning pitchblende vein-type deposits in France, seem altogether too contradictory for use in building a genetic model. Mostly hydrothermal hypotheses have however been suggested, although the previously mentioned idea of formation through continental weathering remains quite relevant; indeed, it may be noted that: a) Uraniferous areas are predominantly connected with granites where geochemical uranium, found as uraninite, can easily be leached through slight weathering, in the absence of any vegetation, along with Si, Al, Na and Ca. b) Apart from Na, these are elements essentially found in mineral deposits of pitchblende with a quartz, clay or calcite matrix. c) Such weathering conditions occurred during the Permian period, about 245 million years ago, at which time these mineralizations may have been laid (geochronology U-Pb); d) Veined pitchblende deposits show much analogy in their mineral associations and sequences to the uraniferous concentrations from superficial sources, as is the case with certain deposits in the United States, formed by the circulation of vadose waters. If such a model proves correct, this type of deposit would be contemporaneous with red-bed series whose presence could then become a valuable guide-line for regional-scale exploration.     

GIS-based assessment of risk due to salt mining activities at Tuzla (Bosnia and Herzegovina)

Ground subsidence triggered by salt mining from deposits located beneath the city of Tuzla (Bosnia and Herzegovina) is one of the major dangers acting on a very densely urbanized area since 1950, when the salt deposit exploitation by means of boreholes began. As demonstrated in this paper, subsidence induced several hazard factors such as severe ground deformations, the arising of deep and superficial fractures and a very fast water table rise, connected with the brine extraction, now affecting several districts. The above mentioned factors have been quantified by the use of geomatic methodologies, including field surveys and analysis of geographical data. In order to estimate the historical sinking rates, authors processed the large (and never before processed) amount of topographical data collected during two periods; from 1956 to 1991, and from 1992 to 2003, with only poor data collected. Afterward, traditional surveys were completely and definitively stopped. The analysis reveals a cumulative subsidence as high as 12 m during the whole period, causing damage to buildings and infrastructures within an area that includes a large portion of the historical town, at present almost entirely destroyed. Modern sinking rates have been monitored with static GPS whereas the presence of superficial fractures monitored with kinematic GPS. Factors related to the presence of deep fractures and water table rise have been evaluated by curvature analysis techniques and piezometric data respectively. Finally, hazard factors have been combined in a risk map using the GIS (Geographical Information System) map algebra capabilities and a simple multicriteria decision analysis (MDA). In order to do that, a vulnerability map has been derived on the basis of information reported on a couple of recently sensed high resolution satellite imageries. The final risk, arisen from the combination of single hazard factors and vulnerability map, highlights critical scenarios and unsuspected threatening that are under consideration by the local decision makers and urban planners. In particular, as highlighted in the final risk map, the present-day water table rise, triggered by the decrease in brine pumping, is seriously posing a threat to a portion of the city which is not the most involved in ground deformations.     

Geochemical study of graywackes as a possible starting material of para-amphibolites

The possibility of para-amphibolites originating from the metamorphic transformation of graywackes is investigated. A series of 35 samples of Vosges graywackes has been studied and the geochemical trends for major and trace elements have been determined to this end. The strong similarity of the geochemical characteristics of this group of graywackes to those of a series of para-amphibolites of the Western Alps conforms to the present hypothesis. By comparing sedimentary geochemical trends with igneous trends one is able to distinguish ortho- from para-derivatives.     

Powerful seismovibrators as a possible source of acoustic and electromagnetic disturbances

The observations of the disturbances of the acoustic, electric and magnetic fields at various distances from a vibroseismic source (5–12 Hz frequency range) are presented. Two centrifugal vibrosources (VS) with sinusoidal vibrational force onto the ground of 100 and 40 tons are used. Infrasonic signals are reliably recorded at distances up to 50 km. When the acoustic signal is large, a seismic signal with the same arrival time is also detected. Magnetic and atmospheric electric fields are detected at distances of several kilometers. These signals have practically zero lag time and precede the acoustic and seismic signals. The disturbances caused by the VS were also registered by telluric field measurements at distances up to 2 km from the source.     

Variations of the cosmic ray fluxes as a possible earthquake precursor

Variations of the air pressure, cosmic ray fluxes, sunspot numbers, and interplanetary magnetic field in connection with strong earthquake occurrences are studied. The results of this investigation permits one to consider the variations of the cosmic rays as one of the possible cause of air pressure variations and one of the possible earthquake precursors.     

Polyunsaturated fatty acids in a lacustrine sediment as a possible indicator of paleoclimate

Polyunsaturated fatty acids (C_18:2 and C_18:3ω3 were analyzed in the upper 20m layer of a 200 m long sediment core taken from Lake Biwa. Concentration maxima occur in layers at depths of 0.2, 1–5, 11–12, and 16m. The vertical changes in the $\text{(C}{}_{\mathrm{18:2}}\text{C(C}{}_{\mathrm{18:0}}$ ratio appear to correlate with paleoclimatic condition suggested from palynological evidence. On the basis of $\text{C}{}_{\mathrm{18:2}}\text{C}{}_{\mathrm{18:0}}$ ratios, it was suggested that it has been colder at 200, 1000–4000, 15,000 and 20,000 yr BP than at other times.     

Evaluation of the removal of heavy metals in a natural wetland impacted by mining activities in Mexico

This research is focused on evaluating heavy metals (Cd, Cu, Fe, Mn, Pb, and Zn) uptake and removal by Eleocharis ovata, Cyperus manimae, Typha dominguensis, and Pteridium aquilinum in a natural wetland impacted by mining activities. We analyzed heavy metals content and distribution in native plants, soils, and water of a semipermanent natural wetland in Taxco de Alarcón, Guerrero, and we also determined the physicochemical characteristics of the water. Translocation factor (TF) and bioconcentration factor (BCF) were evaluated. Results showed that physical and chemical conditions are favorable for plants development. Correlation analysis showed a good and positive relation (0.95) between Cu and Pb in soils and plants. In the analyzed matrices: Zn (0.62–2.20 mg/L) exceeded the permissible limits in water, high concentrations of Pb and Zn (26.57–525.67 and 266.67–983.33 mg/kg, respectively) were detected in the studied soils, and Pb exceeded the normal range for E. ovata and P. aquilinum in the analyzed plants. Uptake of heavy metals in the tissues of different species was found in the following order: root > leaf. Data of TF and BCF showed that E. ovata is a tolerant plant with respect to heavy metals exposure since TF value was greater than 1. This study showed that E. ovata could be considered as a bioaccumulator of heavy metals in contaminated soils.     

State University and Russian Academy of Sciences as contributors to the innovative restructuring of Moscow

Both University and Academy of Sciences have traditionally been important economic actors of the Russian capital city, although their research activity was covered mostly from the federal budget. Links with Moscow city authorities have been regulated from the top (Communist party directives etc.) and channelled within focused research programs, hardly financed extra to stable budget salaries. At the present stage, when more and more financial mechanisms are involved, their links with Moscow Government are based on initiative from the bottom and look rather like a survival strategy than as a real motivated innovative activity. Academy seems to be more successful in establishing network of contract research for the city: in 1993– 95 out of 83 proposals 55 have been financed through the cooperation program Academy to Moscow, Moscow to the Academy (most of them in the field of environment, industry, transport, cultural heritage and healthcare). Out of 159 university proposals only 9 were selected and none really financed. In reality links between scientists and Moscow government are much more intensive than officially registered due to their participation in expert commissions, consultancies and research contracts, developed on the basis of informal networks. University science park is a special case-study in this paper, providing an example of a successful innovative activity in Moscow. The main barriers for the use of innovative potential of the main Russian fundamental science centres in Moscow are 1) the lack of economic innovative policy by the city authorities, 2) weakly developed mechanisms of bringing the results of fundamental research into practice, 3) rising taxes, other intermediate charges and bureaucratic obstacles, making any kind of research activity for the benefit of Moscow economically disadvantageous, 4) low synergy effect of technologically innovative research, 5) conservatism of a big part of the personnel (especially in the University) and negative attitude to any kind of commercial activity in cathedrals of science. Nevertheless, there are evident signs that the role of Academy and University in creation of innovative millieu in Moscow is growing, both as producing new knowledge and labour force training, and as centres of direct enterpreneurial activity (see Castells and Hall 1994).     

Proteins as a possible source material of low molecular weight petroleum hydrocarbons

Low temperature cracking experiments of a representative protein, at temperatures not far above the observed temperature range of 130–160°C of mature California oil source rocks, indicate the formation of all gaseous and of some gasoline range hydrocarbons of petroleum. Based on protein derivatives only it is estimated that a maximum of at least 3–8% by weight of the total organic matter of oil source sediments may be converted into such hydrocarbons. This is in addition to hydrocarbons originating from lipids.     

An integrated approach to environmental risk assessment of cumulatively impacted drainage basin from mining activities in southwestern Ghana

Acid rock/mine drainage and metal leaching constitute major environmental management risks in the mining industry. This paper assesses the environmental risks due to acid rock/mine drainage, and the metal leaching potential of multiple mines of gold and manganese on the Ankobra River Drainage Basin in Southwestern Ghana. The basin is a hub of mining activity in Ghana, hosting several mines. A combination of mineralogical, and static geochemical acid drainage predictive investigation of overburden of varied geological units, complimented with hydrochemical drainage quality analysis was used to assess potential environmental risks posed by acid-generating lithologies and mine spoil. Mineralogical investigations revealed sulphide-bearing lithological units with profound compositional variations due to the incorporation of potentially toxic heavy metals and metalloids, in association with carbonates and silicates. Accounting Base Accounting (ABA) and Net acid generation potential pH (NAGpH) tests delimited two tailing sites as potentially acid generating with NAGpH of 3.5 and 4.8, respectively. Five other samples, representing specific lithological units in the stratigraphic sequence, with net acid neutralization potential ratio (NNPR) less than 5.0, were classified as being potentially acid generating according to the categorization requirement of the US Forestry Service. The rest of the samples exhibited moderate to very strong buffering capabilities. The assessment also evaluated drainage quality of the network of streams and rivers constituting the basin and identified sources of drainage contaminants. Acidic waters emanate from identified acid generating sources, while high metal load regimes were identified with both low pH waters and high pH regimes, coincident with high sulphide and carbonate alteration sites, respectively. The study results show that Zn, Cu, Ni, As, Co, Sb, SO₄ ²⁻, pH, alkalinity and conductivity are essential and adequate parameters in routine environmental risk monitoring programmes of mines in the area. Sites characterized by low pH (<5.5) with high sulphate and metal ions are suggestive of acid mine drainage, while sites with high pH (>7.5), metal ions and sulphate are suggestive of net acid neutralizing.