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1.
Three hundred and seven accessions of Aegilops tauschii Coss., including 160 of subsp. tauschii and 147 of subsp. strangulata, representing all the species range—from Turkey to Kirgizstan, were analyzed electrophoretically. Twenty polymorphic enzyme-encoding loci were studied, 10 of which were essentially polymorphic in Ae. tauschii. Climatic data for each of the 307 Ae. tauschii habitats were taken from WORLDCLIM database of computer system ArcGIS. Forty-nine climatic parameters were considered: precipitation, minimum, mean and maximum temperatures for each month, and also the total annual level of precipitation. The data were analyzed with multivariate statistical methods, such as Principal Components Analysis (PCA), Multiple Correspondence Analysis (MCA) and Two-Block Partial Least Squares. Variability of climatic conditions among Ae. tauschii habitats is reflected by the two approximately orthogonal “vectors”. The “first vector” is mostly determined by negative impact of precipitation and minimum temperatures during winter. The “second vector” is mostly determined by negative impact of maximum temperatures during summer, and positive impact of precipitation during late spring and summer. Aegilops tauschii is essentially variable along the “second vector”, and especially high level of variation is characteristic for subsp. tauschii. This variation reflects that Ae. tauschii is very tolerable to the climatic variation during summer season. Aegilops tauschii subsp. strangulata is also characterized by the high level of variation along the “first vector”. Moreover, all the habitats of subsp. strangulata fall into the two distinct separate clusters: the habitats in Precaspian Iran, which have the highest minimum temperatures in winter,—and all the other habitats. In the plot of the first two factors of PCA, the “cluster of Precaspian Iran” can be further divided into “Western Precaspian Iran (WPI)”, having relatively higher level of annual rainfall, and relatively dryer “Eastern Precaspian Iran (EPI)”. This three groups of subsp. strangulata accessions, from WPI, EPI and other areas, are also distinctly differed in enzyme-encoding genes allelic variation, as revealed on the plot of the first two axes of MCA. In contrast to subsp. strangulata, the level of variation of subsp. tauschii along the “first vector” is rather low. It was pointed out that variation along “the first vector” reflects adaptive intraspecies divergence of Ae. tauschii: its subspecies strangulata “prefers” the habitats of seaside climate, with warm and moist winter; while subsp. tauschii mostly occupies the habitats with rather continental climate, with relatively cold and dry winter. Allelic variation of enzyme-encoding genes Acph1, Ak, Est2, Est5, Got1, Got2, and Got3 correlate with climate along “the first vector”. Apparently, polymorphism of these loci were involved into the process of Ae. tauschii intraspecies adaptive divergence. Allelic variation of Cat2 and Fdp loci correspond to climatic variation along “the second vector” in subsp. tauschii. Therefore Cat2 and Fdp are likely to be among the genes which polymorphism “helped” subsp. tauschii to succeed in vast geographical expansion far to the east from Caspian Sea.  相似文献   

2.

Purpose

Soil depth generally varies in peak-cluster depression regions in rather complex ways. Because conventional soil survey methods in these regions require a considerable amount of time, effort, and consequently relatively large budget, new methods are required in karst regions.

Materials and methods

This study explored the relationship between soil depth and terrain attributes abstracted from digital elevation models (DEMs) at different spatial resolutions in the Guohua Karst Ecological Experimental Area, a representative region of peak-cluster depression in Southwest China. A uniform 140 m?×?140 m grid combined with representative hillslope methodology was used to select 171 sampling points where soil depth was measured. Nine primary and secondary terrain attributes, such as elevation, slope, aspect, especial catchment area, wetness index, length-slope factor, stream power index, relief degree of land surface, and distance from ridge of mountains, were computed from DEMs at different spatial resolutions. The optimal DEM spatial resolution was determined by Grey relational analysis (GRA) to reflect the correlations between soil depth and terrain attributes.

Results and discussion

GRA revealed that the 10-m spatial resolution DEM can best reflect the relationship between soil depth and terrain attributes; therefore, the terrain attributes at this resolution were used for multiple linear stepwise regression (MLSR) analysis. The result of MLSR indicated that slope, TWI, and elevation could explain about 61.4 % of the total variability in soil depth in the study area.

Conclusions

The terrain attributes of slope, WTI and elevation can be used to evaluate soil depth in this region very well. This proposed approach may be applicable to other peak-cluster depression regions in the karst areas at a larger scale.  相似文献   

3.
Spectroscopic techniques including X-ray photoelectron spectroscopy (XPS) can identify particular chemical groups of humic acids (HA) from “Terra Preta de Índios” (TPI) or Amazonian dark earth, the highly fertile anthropogenic soil found in the Amazonian region. The high fertility and resilience of these soils cannot be explained by their chemically inert pyrogenic C content alone, but the natural aging of this C generates reactive carboxyl functional groups attached directly to the recalcitrant polycondensed aromatic backbone. Through spectroscopic techniques used in this work, the HA fraction (the alkaline-soluble organic matter that precipitates at low pH) of the TPI soil was compared with humic and fulvic acids, obtained by oxidizing activated charcoal with sodium hypochlorite. The yields recovery of HA-like substances was 12 and 28 wt% by using 10 and 20 cmol L?1 of oxidizing agent, respectively. X-ray photoelectron spectroscopy, energy dispersive X-ray, and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopies were used to evaluate the elements and structures present in all samples. XPS C 1 s spectra of HA extracted from TPI soil and from prepared HA showed aromatic structures (C?=?C and π–π* shake-up satellite peak) bounded to carboxyl groups (COOH). The morphology and polycondensation level of aromatic C were evaluated by scanning electron microscopy (SEM). The similarities of the spectra indicated that the used method was efficient to obtain an organic amendment similar to TPI soil organic matter.  相似文献   

4.
Growth and vigor of trees show considerable variations in young teak plantations in Benin (Vertisols) as well as in Liberia (Ferralsols). Differences in growth are mainly related to topsoil acidity and the foliar Ca-status in Liberia. In Benin, waterlogging (followed by root decay) reduces the Mg-, K- and N-uptake. In addition, growth on the Vertisols is limited by a low KEX/CEC-ratio of usually <1%.  相似文献   

5.
Nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) were compared for their ability to solubilize Pb from a highly-contaminated (PbT 21%) soil collected from a battery recycling facility. For chelant concentrations below 0.04 M (representing a 1:1 chelant-to-PbT molar ratio), EDTA released 10 to 30% more Pb than NTA. NTA-to-Pb T ratios greater than 1:1 reduced Pb recovery because of readsorption of Pb(NTA)2 4? onto positively-charged oxide soil components at pH < 8.5. For the EDTA system, however, complexation completely bound all coordination sites of Pb and EDTA, leaving no functional groups available for surface adsorption. Thus, Pb recovery progressively increased with higher EDTA concentrations, although the additional Pb release with each EDTA increment became smaller. For pH < 5 and EDTA/Pb of 2:1, Pb recovery exceeded 90%. The addition of 0.5 M NaC1O4 enhanced Pb recovery by EDTA for pH 5 to 12, but substantially suppressed recovery by NTA for pH < 11. Because Pb release by NTA was diminished by high ionic strength and chelant-to-metal ratios, NTA may be limited as a soil washing reagent. Stronger complexation and consistent Pb desorption behavior by EDTA favors its use.  相似文献   

6.
We examined the effect of TiO2 nanoparticles (NPs) on the growth of maize and soybean plants and associated soil microbial communities. Plants were grown in a greenhouse, and low levels of undoped or nitrogen-doped TiO2 NPs were applied. Plant growth and nutrient content were determined, and effects of NPs on composition of soil microbial communities were examined using terminal restriction fragment length polymorphism analysis (TRFLP) of rDNA. We found no significant effects of TiO2 NPs on plant growth, nutrient content, or the composition of bacterial communities within the rhizosphere. However, arbuscular mycorrhizal fungal communities were affected by application of undoped and nitrogen-doped TiO2 NPs. This observation may be partially attributed to the small but significant TiO2 NP uptake levels in the root tissues of both plants. Our results suggest that even low concentrations of TiO2 NPs may influence some important groups of soil microbes, such as mycorrhizal fungi, but changes in the composition of microbial communities may not affect plant growth under conditions of adequate moisture and nutrients.  相似文献   

7.
The growth rates of two diatoms, acidophilic Asterionella ralfsii and circumneutral A. formosa, were differentially affected by varying pH, Al, and EDTA in chemically defined media. Free Al ion concentration increased as pH and EDTA concentration decreased. Free trace metal ion concentration decreased as EDTA levels increased but increased by orders of magnitude upon addition of Al. pH had an overriding species specific effect on growth rate; at low pH A. ralfsii had higher growth rates than A. formosa and vice versa at high pH. For both species higher EDTA levels depressed growth rates. Moderate additions of Al generally resulted in growth stimulation. The growth rate stimulations, especially at 200 and 400 μg L?1 Al additions, correlate to increases in free trace metal ion concentrations. The EDTA-AI interaction effects on growth rate were both pH and concentration dependent: at pH 7 both species were stimulated by addition of Al at all EDTA levels (except A. ralfsii at 5.0 mM EDTA and A. formosa at 0.5 mNM EDTA); at pH 6 Al addition either stimulated or had no effect on the growth rates of both species (except at low EDTA and high Al levels); at pH 5 A. formosa did not grow and additions of 200 μg L?1 Al stimulated growth of A. ralfsii. It is likely that the effect of pH, Al, and EDTA on speciation of essential or toxic trace metals affects growth rates of these diatoms in a species specific manner.  相似文献   

8.
Tetrahymena pyriformis, a common freshwater ciliate concentrated the four common HCH (Hexachlorocyclohexane) isomers viz., α, β, δ, and γ to varied extent. Bioconcentration factor [as expressed by the ratio of cellular insecticide in ng mg?1 (dry weight) to supernatant in ng μL?1 ranged from 342 to 2260 for α-HCH, 37 to 831 for β-HCH, 326 to 2806 for δ-HCH and from 106 to 1214 ppm for γ-HCH.  相似文献   

9.
The specific conductance of surface delivery waters to the Shark River Slough (Everglades National Park, Florida) has increased significantly since the completion of Levee 29 (L-29) and the S-12 water delivery system in the early 1960's. In order to document the response of specific conductance in the slough to changing environmental conditions, it was monitored continuously for a period of 12 mo at a location in central Shark approximately 17 km south of the water delivery site. In addition, variability in isoconductivity patterns throughout the slough was assessed by conducting biweekly surveys at 97 locations. Specific conductance was found to respond to a variety of natural and manmade environmental changes and proved to be an important management tool serving as an early indicator of potentially broad changes in water quality. Factors important in determining overall isoconductivity patterns in Shark Slough include:
  1. the ionic composition of surface delivered to Shark Slough via the S-12 delivery structures.
  2. the quantitative relationship between the amount of surface water delivered to the slough and the amount of precipitation falling directly upon the slough.
  3. the effects of evapotranspiration and concentration of biological organisms during seasonal periods of extreme drawdown.
  相似文献   

10.
This paper presents the findings of initial investigation of the role of Spartina alterniora Loisel. in the movement of chlorinated hydrocarbons. 14C-polychlorinated biphenyls and technical Aroclor® 1254 were used for the determinations. The findings demonstrate that Spartina accumulates 14C-radioactivity from sand and organic mud soil systems treated with 14C-PCB's. These findings also demonstrate that this plant has the capacity to accumulate 14C-radioactivity to levels elevated above that in the treated soil. Other experiments with Aroclor® 1254 demonstrate that cogeners of Aroclor® 1254 are present in Spartina stem and root extracts. These experiments also suggest that the chlorinated hydrocarbon uptake process is modulated by the plant and that this results in selective cogener uptake. The selectivity appears to be for the lesser chlorinated components of the commercial mixture. Overall, this study suggests that Spartina may act as an initial vector for mobilization of sediment bound chlorinated hydrocarbons to the estuarine food chain.  相似文献   

11.
This paper deals with the effect of solvents on the pesticide inhibition of ATPase in the gills and brains of a freshwater teleost Labeo rohita after in vitro treatment with chlordane (an organochlorine pesticide) and MetasystoxR (an organophosphate) pesticide after dissolving in different organic solvents viz. benzene, cyclohexane, cyclopentane, dimethylacetamide (DMA), dimethylformamide (DMF), dimethylsulfoxide (DMS), and acetone/ethanol (1:1) mixture. The inhibitory effect of chlordane was greatly reduced by cyclohexane, cyclopentane and benzene, to a less extent by DMA, DMF, and DMS and to a lesser extent by acetone/ethanol (1:1) mixture. ATPase inhibition by MetasystoxR showed less effect on the inhibition of ATPase activities. Effect on the inhibition of Na+, K+-ATPase was observed to be greater than on Mg++ ATPase in both tissues, but the activity of both the ATPase in gill homogenate was decreased compared to brain homogenate. Choice of solvents can have profound effects on the response of ATPase to chlorinated hydrocarbon pesticides.  相似文献   

12.
Air pollution and atmospheric deposition by PCBs and organochlorine pesticides (isomers of HCH and p,p′-DDE) were studied at Paris from January 1986 to June 1987. The deposition measured as total (wet plus dry) was also followed during 1986 on two suburban and two rural sites. The distribution of the pollutants between the vapor phase and aerosols was evaluated by sampling air through a glass microfiber filter connected to a Tenax resin cartridge. The study shows that in the atmosphere as in waters of the catchment area of the Seine river, PCBs are the main organochlorine pollutants. Pollution by OCL is of the same order as the one described in literature (mean γ-HCH concentration 1.4 ng m?3) while PCB concentrations in the atmosphere are equal to or higher than those observed in USA and Europe (range 5 to 44 ng m?3). On the average, 93% of the PCBs are in the vapor phase with a composition approximating Aroclor 1242. In aerosols and precipitations the composition is closely related to Aroclor 1254. The total fallout for 1986 was 40 μg m?2 for PCBs and 20 μg m?2 for γ-HCH, rainfall being 611 mm.  相似文献   

13.
Comparisons of stream water chemistry over a 2 yr period in East Fork, which drains an entirely forested watershed, and Big Run, which drains a forested watershed 8 % of which is occupied by Big Run Bog, indicated that Big Run Bog had no effect on stream water H+ or Cl? concentrations, but with increasing stream discharge the wetland was a source of Ca++ Mg++, K+, Na+, NO3 ?, and SO4 ?, and a sink for Fe+ +. Further comparisons with Tub Run, which drains a forested watershed, 13 and 12% of which is occupied by Tub Run Bog and an abandoned, unreclaimed coal surface mine, respectively, suggested that Tub Run Bog removes H+, Ca ++, Mg++, Fe++, and 504 ? from inputs of acid mine drainage. Wetland areas on the landscape contribute to the regulation of stream water chemistry in ways that are different from upland areas, and wetlands may have considerable applied potential for minimizing the impact of the mine drainage on stream water quality.  相似文献   

14.
The acute toxicity of commercial herbicide, Paraquat was determined by 96-hr static bioassay on the freshwater chlorophytes Scenedesmus dimorphus (Trup.) Kuetz., Scenedesmus quadricauda (Trup.) de Brebisson and Ankistrodesmus falcatus (Cord) Ralfs. The 96-hr EC50 values of Paraquat for reducing growth and metabolic products of the three algae were determined. The number of days required for cell division increased with increasing Paraquat concentration. The three algae and their test parameters respond differently to Paraquat. Scenedesmus dimorphus was the most susceptible alga and the chlorophyll a was the most sensitive response parameter. On the other hand, the dry weight of the test algae was the most resistant parameter. It was observed that Paraquat has inhibitory effect on the primary producers.  相似文献   

15.
A protozoological survey was performed to analyze the organisms of the subphylum Sarcodina Schmarda, present in waste stabilization ponds located at Santo Tomás Atzingo, México, from March to December 1981. The amoebae isolated were identified and counted. Several physicochemical parameters were also determined and correlated with the biological data. Thirteen amoebic species were isolated and identified: one definite pathogen, Entamoeba histolytica Schaudinn; three species that have shown pathogenic strains for humans: Acanthamoeba polyphaga Page, Acanthamoeba castellanii Douglas, and Naegleria sp. (Alexeieff) Calkins; two opportunist species: Entamoeba coli (Grassi) Casagrandi and Barbagallo, and Iodamoeba bühschlii (Von Prowazek) Dobell; and seven free-living amoebae: Acanthamoeba astronyxis Ray and Hayes, Amoeba proteus (Pallas) Leidy, Hartmannella exundans Page, Hartmannella vermiformis Page, Pelomyxa palustris Leidy, Vahlkampfia avara Page, and Vahlkampfia russelli Singh. A clear correlation between the number of amoebae and the temperature and alkalinity of the system was found. The removal capacity of the ponds for E. histolytica varied from 30 to 100% during the survey. The amoebae showed a succession in space and time in the system studied.  相似文献   

16.
Coliform and faccal coliform were isolated from drinking water samples obtained from tap water (TW) and storage tanks (ST) in Baghdad city. All isolates were identified and tested for their resistance to twelve antibiotics. Bacterial identification revealed that Ent. cloacae and Kl. pneumoniae were the predominant organisms from TW and ST water samples, respectively. Overall, 66% of the isolates from TW and 38% from ST were resistant to one or more of the drugs tested. Ampicillin, Carbenicillin, Cefalotin and Colistin resistance in particular were more frequent among bacterial isolates. The overall frequency of multiple antibiotic resistance among bacterial isolates in TW and ST samples were 47% and 33%, respectively. All bacterial strains isolated from drinking water were sensitive to Rifampicin. Results demonstrated the need for periodical bacteriological examination of drinking water and restriction in the use of antibiotics in this country.  相似文献   

17.
A theoretical model describing the general interaction between atmospheric trace gases, such as S02, NH3, C02 and 02, chemical reactant gaseous product H2SO4 and hydrometeors containing NaCl is proposed to study a possible mechanism for HCl production in non-precipitating cloud and the determination of the pH value of cloud droplets. Four different cloud droplet distributions have been used to estimate the upper limit of the amount of gaseous HCl released into the atmosphere resulting from the evaporation of cloud droplets. It is shown that the acid production and the amount of HCl released depend on the following factors: (a) the temperature of the cloud; (b) the oxidation rates; (c) the ambient concentration of SO2, NH3, and H2SO4; (d) the life cycle of the cloud; and (e) the liquid content of the cloud. This proposed chemical model also predicts a pH value spectrum depending on the cloud droplet distribution. Field measurements for the dependence of pH value on particle size and spatial distribution of gaseous HCl are recommended.  相似文献   

18.
The coastal dune aquifer, providing drinking water for a large part of the population of the western Netherlands, is recharged by fainfall and artificial infiltration of Rhine water. Chernobyl fall-out has been detected in both water sources. At the Castricum lysimeter station the rainfall-derived water, draining from 2.25 m of unsaturated sandy soil, shows levels of Cs-137 around the detection limit of 20 to 40 mBq kg?1. At this site, the soil itself retained some Chernobyl-derived Cs-137 in the top 10 cm, where a similar quantity of old Cs-137 has also been retained. Penetration of old Cs-137 is deeper (up to 70 cm) under oak vegetation than in the bare soil. In the infiltration channels, fed by Rhine water, the bottom mud contains only Chernobyl-derived Cs nuclides. Radioactivity from Cs-137 is about one tenth of that from natural radioactivity due to K-40. Cesium levels are apparently unrelated to adsorptive properties.  相似文献   

19.
This study examined the effects of exposing the eggs of the purple sea urchin (Arbacia punctulata) to two commercial polychlorinated biphenyl mixtures (PCB's), Aroclors 1254 and 1016, on fertilization through pluteus (larva) development. Eggs were exposed to various concentrations of the PCB's (0.5, 1.0, 5.0, and 10.0 mg L?1) beginning 25 min prior to insemination, with continuous exposure post-insemination for the 72 hr observation period employed in this study. The PCB's were administered as a component of a filtered sea water (FSW) medium. A FSW control and a FSW-acetone conditioned control where used since acetone was utilized in a 49 : 1, acetone: PCB ratio, to emulsify the PCB's. Since Arbacia eggs cleave synchronously following insemination, the percentage of the eggs cleaving at 1.75 hr post-insemination was used to determine the fertilization efficiency. Pluteus development and morphology was assayed at 24 hr intervals. The results of the fertilization efficiency studies were tested using Chi square and Pearson's-Product-Moment-Correlation Coefficient (r) at a 95% level of confidence. The morphology data were treated with a two-tailed t-test (99% confidence level) and (r). Both PCB's affected fertilization efficiency with the Aroclor 1016 being an order of magnitude more toxic than the Aroclor 1254. Likewise, both Aroclors were toxic to the pluteus development process with Aroclor 1016 being the more toxic of the two mixtures. At the highest PCB level employed, Aroclor 1254 proved more lethally toxic than Aroclor 1016 although both treatment-groups exhibited more than 90% toxicity to the morphogenic process.  相似文献   

20.
Contamination of the Spring River in southwest Missouri by 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD) is believed to result from several well-defined point source waste disposal sites. Analyses of 31 fish samples and samples of crayfish, mussels, other aquatic invertebrates, and sediments collected in 1981-1983 demonstrated a rapid decline in TCDD levels in biota both upstream and downstream of the area of contamination and are believed to indicate a continuing, long term input of TCDD into the river. Mean concentrations of TCDD 0.5 km downstream from the area of contamination were 38 parts per trillion (pptr) in whole fish and 20 pptr in fish fillet; mean concentrations beyond 14 km downstream were below 4 pptr in both whole fish and fillets. Caged mussels (65 day exposure) did not accumulate TCDD (detection limit, 10 pptr). High fish consumption by local sportsmen may indicate maximum permissible concentrations of less than 5 pptr. in fish fillets.  相似文献   

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