Mercury in soils of British Columbia,a mercuriferous region     

M. K. John  C. J. van Laerhoven  V. E. Osborne  I. Cotic 《Water, air, and soil pollution》1975,5(2):213-220

Mercury concentrations in various horizons of British Columbia soils were determined to estimate natural background levels in soils from various geographical areas of the province. Highly enriched concentrations near the Pinchi Lake cinnibar deposit declined to background levels ranging from 10 to 310 ppb Hg in the district. In six other regions, concentrations in surface mineral horizons averaged 85 ppb and ranged to 490 ppb but surface horizons of peaty muck soils and those predominated by vegetative litter contained 164 ppb Hg on the average and as much as 741 ppb. Concentrations in subsurface horizons were lower than at the surface. A significant relationship between Hg concentration and organic matter content was observed. Comparison with soils from outside British Columbia indicated its location within a generalized mercuriferous belt accounted for the relatively high concentrations observed.  相似文献   

Genetic diversity in <Emphasis Type="Italic">Eremostachys superba</Emphasis> Royle ex Benth. (Lamiaceae), an endangered Himalayan species,as assessed by RAPD     

Susheel Verma  Jawahar L. Karihaloo  Shailesh K. Tiwari  Rani Magotra  Awtar K. Koul 《Genetic Resources and Crop Evolution》2007,54(2):221-229

Eremostachys superba Royle ex Benth. (Lamiaceae) has undergone a severe decline in population size since its discovery in the North-western Himalayas in late 19th century. One hundred and seventy-two plants from six populations in the Indian states of Uttar Pradesh and Jammu & Kashmir, located between 0.45 km and 455.72 km apart from each other were evaluated for RAPD polymorphism. Sixteen random primers generated 92 bands overall, 77 of which were polymorphic. Shannon’s index of genetic diversity within populations (H _o) ranged between 0.305 and 0.421; the average within-population diversity (H _pop) was 0.389; and the total species diversity (H _sp) was 0.478. The population from Mohand (representing the type locality) had the fewest plants, at 18, and was genetically the most depauperate. Among the other populations, ranging in size between 52 and 1,022 individuals, no relation between population size and genetic diversity was evident. It is suggested that these six populations represent relics of a larger, extended population, in which the presence of perennating rootstocks has helped preserve historic patterns of genetic diversity. AMOVA revealed that 83.01% of the variation exists within populations, which was consistent with earlier studies on the reproductive biology of E. superba, which indicated this species is predominantly allogamous. FST distances between all populations were significant, indicating geographic differentiation despite some of them being closely separated. Habitat restoration and protection from indiscriminate harvesting are proposed as primary strategies for conserving E. superba. Rejuvenation of the Mohand population through intrapopulation crossing between plants bearing diverse molecular phenotypes is also suggested.  相似文献   

Development of EST-SSR in foxtail millet (<Emphasis Type="Italic">Setaria italica</Emphasis>)     

Xiao-Ping Jia  Yun-Su Shi  Yan-Cun Song  Guo-Ying Wang  Tian-Yu Wang  Yu Li 《Genetic Resources and Crop Evolution》2007,54(2):233-236

The development of EST-SSR in foxtail millet (Setaria italica) for polymorphism and transferability study was reported here. From 1213 EST sequences, 30 SSRs were obtained and primers were designed for 26 SSRs. Among them, four pairs of SSR primers amplified polymorphic products in 12 foxtail millet cultivars and one accession of Setaria viridis, a wild relative of foxtail millet, with 10 alleles detected for the four loci and 2.5 alleles per locus. In addition, ten SSR markers could be transferred to other nine Gramineae species. The putative functions of 11 ESTs containing polymorphic and transferable SSRs were also identified.  相似文献   

Near-infrared spectroscopy for analysis of chemical and microbiological properties of forest soil organic horizons in a heavy-metal-polluted area     

Marcin Chodak  Maria Niklińska  Friedrich Beese 《Biology and Fertility of Soils》2007,44(1):171-180

In industrial areas, heavy metals may accumulate in forest soil organic horizons, affecting soil microorganisms and causing changes in the chemical composition of the accumulated organic matter. The objectives of this study were to test the ability of near-infrared spectroscopy (NIRS) to detect heavy metal effects on the chemical composition of forest soil O horizons and to test whether NIRS may be used to quantitatively determine total and exchangeable concentrations of Zn and Pb (Zn_t, Pb_t, Zn_ex, Pb_ex) and other chemical and microbial properties in forest soil O horizons polluted with heavy metals. The samples of O horizons (n = 79) were analyzed for organic C (C_org), total N and S (N_t, S_t), Zn_t, Pb_t, Zn_ex, Pb_ex, basal respiration (BR), microbial biomass (C_mic) and C_mic-to-C_org ratio. Spectra of the samples were recorded in the Vis-NIR range (400–2,500 nm). To detect heavy-metal-induced changes in the chemical composition of O horizons principal components (PC1–PC7) based on the spectral data were regressed against Zn_t + Pb_t values. A modified partial least squares method was used to develop calibration models for prediction of various chemical and microbial properties of the samples from their spectra. Regression analysis revealed a significant relationship between PC3 and PC5 (r = −0.27 and −0.34, respectively) and Zn_t + Pb_t values, indicating an effect of heavy metal pollution on the spectral properties of the O horizons and thus on their chemical composition. For quantitative estimations, the best calibration model was obtained for C_org-to-N_t ratio (r = 0.98). The models for C_org, N_t, and microbial properties were satisfactory but less accurate. NIRS failed to accurately predict S_t, C_org-to-S_t, Zn_t, Pb_t, Zn_ex, and Pb_ex.  相似文献   

Spatial patterns of diversity and genetic erosion of traditional cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) in the Peruvian Amazon: An evaluation of socio-economic and environmental indicators     

Louise Willemen  Xavier Scheldeman  Víctor Soto Cabellos  Simón Rafael Salazar  Luigi Guarino 《Genetic Resources and Crop Evolution》2007,54(7):1599-1612

This study evaluates quantitatively the suitability of the use of site-specific socio-economic and environmental data as indicators to rapidly assess patterns of diversity and genetic erosion risk in cassava. Socio-economic data as well as farmers’ estimation of genetic erosion were collected in the study area, the Ucayali region of the Peruvian Amazon, through interviews with 285 cassava farmers in 50 communities, while diversity was assessed based on agromorphological characterization of 295 cassava accessions. Using multivariate regression analyses, 50 and 45% of the variation in respectively diversity and genetic erosion estimation could be explained by a selected set of socio-economic and environmental indicators. In both regression models four out of the total of 38 variables proved to contribute significantly (at p < 0.10 level). Additionally, the study revealed that farmers are a good direct source of information on the diversity present at community level, which can contribute to the development of methodologies to assess diversity more rapidly. The results of this study are valuable for the development of models to rapidly assess diversity dynamics in large areas.  相似文献   

Genetic diversity of potato landraces from northwestern Argentina assessed with simple sequence repeats (SSRs)     

Verónica Nilda Ispizúa  Irma Rosana Guma  Sergio Feingold  Andrea Martina Clausen 《Genetic Resources and Crop Evolution》2007,54(8):1833-1848

Andean potato varieties are cultivated in the northwest of Argentina and constitute the most important staple food for the local farmers. The genetic diversity of 155 accessions conserved at the Genebank of Balcarce (INTA) was tested using four microsatellites. Three commercial potato varieties of Tuberosum group and one accession of Curtilobum group were used as outgroups. The presence of bands was scored for each microsatellite and for each accession and the data were analysed by principal coordinate analysis. The polymorphism information content was obtained for each molecular marker from banding patterns. Analysis of molecular variance was carried out with a variable number of accessions for each landrace, from different departments and sites within departments. More than one genotype was detected in the majority of the potato landraces. Some accessions within each landrace did not differentiate. AMOVA revealed that most of the genetic variation occurred among sites within departments and among local varieties. These findings are discussed considering the agricultural practices carried out in the Andean farming system.  相似文献   

Certification of B-group vitamins (B1, B2, B6, and B12) in four food reference materials     

Ollilainen V  Finglas PM  van den Berg H  de Froidmont-Görtz I 《Journal of agricultural and food chemistry》2001,49(1):315-321

In 1989, the Community Bureau of Reference started a research program to improve the quality of vitamin analysis in food. To achieve this task, vitamin methodology was evaluated and tested by interlaboratory studies and the preparation of certified reference materials, which will be used for quality control of vitamin measurements. The main improvements in methodology were achieved by testing and standardizing the extraction condition and enzymatic hydrolysis procedures. Results for each individual material are derived from five replicate determinations using at least two independent methods: liquid chromatography (HPLC) and microbiological assay for vitamins B1, B2, and B6; and radioprotein binding and microbiological assays for vitamin B12. The certificate of analysis for four reference materials gives mass fraction values for water-soluble vitamins. These certified values were based on the acceptable statistical agreement of results from collaborating laboratories. Certified values with uncertainties (mg/kg dry matter) for each CRM are as follows: 4.63 (0.20) and 4.10 (0.51) for vitamins B1 and B6, respectively, in CRM 121 (wholemeal flour); 6.51 (0.24), 14.54 (0.3), 6.66 (0.43), and 0.034 (0.003) for vitamins B1, B2, B6, and B12, respectively, in CRM 421 (milk powder); 3.07 (0.17) and 4.80 (0.40) for vitamins B1 and B6, respectively, in CRM 485 (lyophilized mixed vegetables), and 8.58 (0.55), 106.8 (2.8), 19.3 1.5), and 1.12 (0.044) for vitamins B1. B2, B6, and B12, respectively, in CRM 487 (lyophilized pig liver).  相似文献   

Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)     

N. P. S. Dhillon  R. Ranjana  Kuldeep Singh  I. Eduardo  A. J. Monforte  M. Pitrat  N. K. Dhillon  P. P. Singh 《Genetic Resources and Crop Evolution》2007,54(6):1267-1283

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.  相似文献   

Composition and transformation of 1.4 nm minerals in cutan and matrix of alfisols in central China     

Li Huang  Wenfeng Tan  Fan Liu  Hongqing Hu  Qiaoyun Huang 《Journal of Soils and Sediments》2007,7(4):240-246

Background, Aims, and Scope  Hydroxy interlayered vermiculite (HIV) and vermiculite are commonly referred to as 1.4 nm minerals. In the subtropical soils of central China, the concentration of vermiculites decreased while that of HIVs increased gradually from north to south as the intensity of soil formation or eluviation increases in the same direction. The cutans in these soils closely interact with air, roots, microbes, water and dissolved ions in soils. Cutans may therefore be expected to exert an important influence on the formation of 1.4 nm minerals relative to the matrix soils. However, little is known about the transformation of 1.4 nm minerals in Alfisols in central China. Here, we investigate the compositional differences of 1.4 nm minerals in cutans and matrix soils, and the probable transformation of vermiculite to HIV or vice versa when sodium citrate and sodium acetate are added to matrix Alfisols. Methods  Cutans and matrix soils were separated from three soils in the northern subtropical zone in China. The samples were analyzed for Fe, Mn, exchangeable cations, organic matter(O.M.), pH, and clay minerals. To 10 mL of matrix soil, suspensions containing about 250 mg (oven-dry weight) of clay was added with 5 mL of 0.4 mol/dm³ or 2 mol/dm³ of sodium citrate or sodium acetate solution and 5 mL of 0.2 mol/dm³ mixed solutions of CaCl₂, Mg(NO₃)₂ and KCl. After its pH was adjusted to 6.0, the mixture was ‘incubated’ for 120 or 210 days (more than one season or half a year) during which period it was shaken for 1 hour every day. The clay mineral composition of the samples was determined after incubation. Results  Both vermiculites and HIVs were present in matrix soils, but only vermiculties were detected in cutans. The addition of organic ligands (citrate and acetate) promoted the transformation of HIV to vermiculite. This transformation was obvious for the matrix soils that had been incubated with 0.5 mol/dm³ sodium citrate for 210 days while sodium acetate was less effective in this regard. The promoting effect of organic ligands is dependent on type and concentration as well as incubation time. This would suggest the reverse transformation occurred in the formation of cutans compared with a vermiculite-to-HIV transformation in the subtropical soils of central China from north to south. Discussion  The position and environment of cutans in the B horizon together with the pH, organic matter and exchangeable base status in cutans seem conducive to the co-existence of vermiculite and HIV in the soils, but only vermiculite is found in cutans. The transformation of HIV to vermiculite in incubation experiments could be divided into two steps: 1) Cheluviation of organic matter to the interlayer hydroxy-aluminums from HIVs. 2) Rebasification of hydrated cations into the interlayers of vermiculites. Conclusions  The clay minerals in cutans can interact with organic ligands and nutrient elements excreted by roots. Under conditions of frequent wetting and drying and high pH, and when the concentrations of exchangeable bases, iron-manganese oxides, clays, and organic matter are high, the exchangeable cations can be incorporated into the interlayers of HIV, thereby promoting the partial transformation of HIV to vermiculite in rhizosphere soils. Recommendations and Perspectives  Cutan is at the interface of material and energy exchange involved in physical, chemical and biochemical reactions in the rhizosphere. These factors strongly affect the compositions of cutans. HIVs in (upper or adjacent) matrix soils may transform to vermiculites during cutan formation in these special soil environments. ESS-Submission Editor: Jizheng (Jim) He (jzhe@rcees.ac.cn)  相似文献   

Assessment of genetic relationships between <Emphasis Type="Italic">Rhus</Emphasis> L. species using RAPD markers     

Surya Prakash  Johannes Van Staden 《Genetic Resources and Crop Evolution》2007,54(1):7-11

Genetic diversity of seven Rhus L. species was assessed using random amplified polymorphic DNA (RAPDs) markers. Initially, 90 primers were screened, of which 25 produced reproducible amplification products. These primers generated a total of 296 bands, with an average of 11.8 bands per primer. Out of 296 bands scored, 236 (80%) were polymorphic and 62 (20%) were monomorphic. Primers OPC-05 and OPD-05 generated 100% polymorphic bands. The resolving power of primers ranged from 9.4 to 26.8. Similarity matrix values ranged from 0.45 to 0.63. The dendrogram generated using Unweighted Pair Group Method using Arithmetic Averages (UPGMA) grouped all the species of Rhus in one major group with two sister groups, whilst R. pyroides Burch. and R. dentata Thunb. were outliers. R. gerrardii (Harv. ex Engl.) Diels, R. glauca Thunb. and R. pentheri Zahlbr. constituted one sister group, while R. natalensis Bernh. ex C. Krauss and R. gueinzii Sond. were included in the other. The degree of genetic diversity observed between seven species of Rhus with RAPD markers suggest that this approach could be used for studying the phylogeny of the genus.  相似文献