湖相沉积:从油页岩到蒸发岩

<正> 关于地表常温条件下水和岩石之间的关系、水的化学成分及湖泊蒸发沉积物的形成过程等问题是目前广泛引起注意的问题。本报告所涉及的具体内容局限于地表条件下的湖相沉积。 湖相沉积,以美国大盐湖为例,它涉及到犹他州、科罗拉多州与怀俄明州的古湖泊(图1),湖     

Genetic variation in natural honeybee populations,<Emphasis Type="Italic"> Apis mellifera capensis</Emphasis>

Genetic variation in honeybee, Apis mellifera, populations can be considerably influenced by breeding and commercial introductions, especially in areas with abundant beekeeping. However, in southern Africa apiculture is based on the capture of wild swarms, and queen rearing is virtually absent. Moreover, the introduction of European subspecies constantly failed in the Cape region. We therefore hypothesize a low human impact on genetic variation in populations of Cape honeybees, Apis mellifera capensis. A novel solution to studying genetic variation in honeybee populations based on thelytokous worker reproduction is applied to test this hypothesis. Environmental effects on metrical morphological characters of the phenotype are separated to obtain a genetic residual component. The genetic residuals are then re-calculated as coefficients of genetic variation. Characters measured included hair length on the abdomen, width and length of wax plate, and three wing angles. The data show for the first time that genetic variation in Cape honeybee populations is independent of beekeeping density and probably reflects naturally occurring processes such as gene flow due to topographic and climatic variation on a microscale.     

Recycling plant wax constituents for chemical defense: hemi-biosynthesis of triterpene saponins from β-amyrin in a leaf beetle

Several species of Doryphorina leaf beetles from Central- and South America produce oleanane triterpene glycosides in their defensive glands. The presence of pentacyclic triterpenes in insects is intriguing since they lack the key enzymes necessary to synthesize these compounds. Since -amyrin is a common constituent of leaf waxes, we hypothesized that these leaf beetles use this compound as a precursor to their oleanane glycosides. To test this hypothesis we first confirmed the presence of -amyrin in Ipomoea batatas, the food plant of Platyphora kollari. Next, adults of P. kollari were fed for 10 days with I. batatas leaf disks painted with a solution of [2,2,3-²H₃]-amyrin ([2,2,3-²H₃]-1). The secretion from their defensive glands was collected and analyzed by HPLC-ESIMS. The results demonstrated that the secretion of beetles fed with an amount of [2,2,3-²H₃]-amyrin corresponding to the quantity of unlabeled (natural) -amyrin present in the leaf disks contained on average 5.1% of [2,2,3-²H₃]-3-O--d-glucopyranosyl-(1-->4)--d-glucuronopyranosyl-hederagenin ([2,2,3-²H₃]-2), whereas the secretions of beetles fed with 10 times this amount of [2,2,3-²H₃]-amyrin contained on average 23.9% of [2,2,3-²H₃]-2. In both series of experiments, the percentage of labeled versus unlabeled triterpene glycoside in the secretion was positively correlated with the amount of deuterated -amyrin ingested. These results demonstrate for the first time that some leaf beetles are able to metabolize a widespread triterpenic constituent of leaf wax into more complex glycosides that are stored in their defensive glands.     

Cycads: their evolution,toxins, herbivores and insect pollinators

Palaeobiological evidence indicates that gymnosperms were wind-pollinated and that insect pollination began in angiosperms in the Lower Cretaceous (ca. 135 mya) leading to close associations between higher plants and their pollinators. Cycads, which were widespread and pervasive throughout the Mesozoic (250-65 mya) are among the most primitive living seed-plants found today. Because pollination by beetles and by thrips has now been detected in several modern cycads, it is attractive to speculate that some insects and cycads had already developed similar mutualistic interactions in the Triassic (250-205 mya), long before the advent of angiosperms. We also draw attention to another key factor in this insect-plant relationship, namely secondary, defensive plant substances which must always have controlled interspecific interactions. Cycads mainly produce toxic azoglucosides and neurotoxic non-protein amino acids (e.g. BMAA), which apparently are crucial elements in the development and maintenance of mutualism (pollination) and parasitism (herbivory) by cycad-linked herbivores. We now add new results on the uptake and storage of the main toxin, cycasin, of the Mexican cycad Zamia furfuracea by its pollinator, the weevil Rhopalotria mollis, and by a specialist herbivore of Zamia integrifolia, the aposematic Atala butterfly Eumaeus atala.     

Distribution of deciduous stands in villages located in coniferous forest landscapes in Sweden

Termination of fire along with active removal of deciduous trees in favor of conifers together with anthropogenic transformation of productive forest into agricultural land, have transformed northern European coniferous forests and reduced their deciduous component. Locally, however, in the villages, deciduous trees and stands were maintained, and have more recently regenerated on abandoned agricultural land. We hypothesize that the present distribution of the deciduous component is related to the village in-field/out-field zonation in different regions, which emerges from physical conditions and recent economic development expressed as land-use change. We analyzed the spatial distribution of deciduous stands in in-field and out-field zones of villages in 6 boreal/hemiboreal Swedish regions (Norrbotten, Angermanland, J?mtland, Dalarna, Bergslagen, Sm?land). In each region 6 individual quadrates 5 x 5 km centered on village areas were selected. We found significant regional differences in the deciduous component (DEC) in different village zones. At the scale of villages Angermanland had the highest mean proportion of DEC (17%) and J?mtland the lowest (2%). However, the amounts of the DEC varied systematically in in-field and out-field zones. DEC was highest in the in-field in the south (Sm?land), but generally low further north. By contrast, the amount of DEC in the out-field was highest in the north. The relative amount of DEC in the forest edge peaked in landscapes with the strongest decline in active agriculture (Angermanland, Dalarna, Bergslagen). Because former and present local villages are vital for biodiversity linked to the deciduous component, our results indicate a need for integrated management of deciduous forest within entire landscapes. This study shows that simplified satellite data are useful for estimating the spatial distribution of deciduous trees and stands at the landscape scale. However, for detailed studies better thematic resolution is needed to determine biologically relevant differences in quality of deciduous stands.     

Degradation and leaching of the herbicides metolachlor and diuron: a case study in an area of Northern Italy

In this work the degradation of the herbicides metolachlor, diuron, monuron and of the metabolites 2-ethyl-6-methylaniline (EMA), and 3,4-dichloroaniline (DCA) was assessed in laboratory experiments on microbiologically active and sterilized soils. Their leaching potentials were calculated, using Gustafson's equation, by determining their mobility (as Koc) and persistence (expressed as DT50). Lysimeter experiments were also conducted to assess the actual leaching of the studied herbicides in a cereal crop tillage area vulnerable to groundwater contamination. The data obtained from the field were compared to the laboratory results. Moreover, some compounds of particular concern were searched for in the groundwater located near the experimental area in order to evaluate actual contamination and to test the reliability of the leaching potential. The GUS index, computed on data from microbiologically active soil, shows monuron as a leacher compound, EMA and DCA as non-leachers, metolachlor and diuron as transient ones. The presence of metolachlor in the groundwater monitored, even at concentrations up to 0.1 mug/l, confirms the possibility that transient compounds can be leached if microbial activity has not completely occurred in active surface soil.     

Microbial biomass and enzyme activities in submerged rice soil amended with municipal solid waste compost and decomposed cow manure

We studied the suitability of municipal solid waste compost (MSWC) application to submerged rice paddies in the perspective of metal pollution hazards associated with such materials. Experiments were conducted during the wet seasons of 1997, 1998 and 1999 on rice grown under submerged condition, at the Agriculture Experimental Farm, Calcutta University at Baruipur, West Bengal, India. The treatments consisted of control, no input; MSWC, at 60 kgNha(-1); well decomposed cow manure (DCM), at 60 kgNha(-1); MSWC (30 kgNha(-1)) +Urea (30 kgNha(-1)); DCM (30 kgNha(-1)) +U (30 kgNha(-1)) and Fertilizer, (at 60:30:30 NPK kgha(-1) through urea, single superphosphate and muriate of potash respectively). Soil microbial biomass-C (MBC), MBC as percentage of organic-C (ratio index value, RIV), urease and acid phosphatase activities were higher in DCM than MSWC-treated soils, due to higher amount of biogenic organic materials like water soluble organic carbon, carbohydrate and mineralizable nitrogen in the former. The studied parameters were higher when urea was integrated with DCM or MSWC, compared to their single applications. Soil MBC, urease and acid phosphatase activities periodically declined up to 60 day after transplanting (DAT) and then increased after crop harvest. The heavy metals in MSWC did not detrimentally influence MBC, urease and acid phosphatase activities of soil. In the event of long term MSWC application, changes in soil quality parameters should be monitored regularly, since heavy metals once entering into soil persist over a long period.     

Dissipation of chlorpyrifos in two soil environments of semi-arid India

The dissipation of chlorpyrifos (20 EC) at environment-friendly doses in the sandy loam and loamy sand soils of two semi-arid fields and the presence of pesticide residues in the harvested groundnut seeds, were monitored. The movement of chlorpyrifos through soil and its binding in the loamy sand soil was studied using 14C chlorpyrifos. Chlorpyrifos was moderately stable in both loamy sand and sandy loam soils, with half-life of 12.3 and 16.4 days, respectively. With 20 EC treatments the dissipation was slower for standing crop than seed treatment, indicative of the high degradation rates in the bioactive rhizosphere. In soil, 3,5,6-trichloro-2-pyridinol (TCP) was the principal breakdown product. Presence of 3,5,6-trichloro-2-methoxypyridine (TMP), the secondary metabolite, detected in the rhizospheric samples during this study, has not been reported earlier in field soils. The rapid dissipation of the insecticide from the soil post-application might have resulted from low sorption due to the alkalinity of the soil and its low organic matter content, fast topsoil dissipation possibly by volatilization and photochemical degradation, aided by the low water solubility, limited vertical mobility due to confinement of residues to the upper 15 cm soil layers and microbial mineralization and nucleophilic hydrolysis. Contrary to the reports of relatively greater mobility of its metabolites in temperate soils, TMP and TCP remained confined to the top 15 cm soil. The formation of bound residues (half-life 13.4 days) in the loamy sand soil was little and not "irreversible." A decline in bound residues could be correlated to decreasing TCP concentration. Higher pod yields were obtained from pesticide treated soils in comparison to controls. Post-harvest no pesticide residues were detected in the soils and groundnut seeds.     

Tracer diffusion coefficients in sedimentary rocks: correlation to porosity and hydraulic conductivity

Matrix diffusion is an important transport process in geologic materials of low hydraulic conductivity. For predicting the fate and transport of contaminants, a detailed understanding of the diffusion processes in natural porous media is essential. In this study, diffusive tracer transport (iodide) was investigated in a variety of geologically different limestone and sandstone rocks. Porosity, structural and mineralogical composition, hydraulic conductivity, and other rock properties were determined. The effective diffusion coefficients were measured using the time-lag method. The results of the diffusion experiments indicate that there is a close relationship between total porosity and the effective diffusion coefficient of a rock (analogous to Archie's Law). Consequently, the tortousity factor can be expressed as a function of total porosity. The relationship fits best for thicker samples (> 1.0 cm) with high porosities (> 20%), because of the reduced influence of heterogeneity in larger samples. In general, these correlations appear to be a simple way to determine tortuosity and the effective diffusion coefficient from easy to determine rock porosity values.     

Results of an "emergency quality control study" as confirmation of a PCDD/PCDF-contamination of milk and butter samples

Elevated PCDD/F levels in four butter samples and one milk sample had to be confirmed under considerable time pressure. These samples should demonstrate a raising dioxin contamination in different regions of Germany caused by the use of Brazilian citrus pulp as feedstuff. Above all, the increase of 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD had to be confirmed. Thus, an "emergency quality control study" was performed including five laboratories from the official food control in Germany. The results had to be reported about two to three weeks after the first announcement of the samples (including time for shipment). The five laboratories applied different extraction and clean-up methods, used different GC-columns and GC/MS-equipment and different standard solutions. The results are in a good agreement. Slightly different results for most individual congeners were of minor importance. A difference was observed only in the 2,3,7,8-TCDF content of one laboratory which was not relevant for the evaluation of the increase of the dioxin contamination in milk and dairy products. The laboratory's individual methods proved to give correct results even under a very tight schedule.