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931.
Bushey Joseph T. Ebbs Stephen D. Dzombak David A. 《Water, air, and soil pollution》2004,157(1-4):281-293
Water, Air, &; Soil Pollution - A method for free cyanide and strongly-complexed cyanide measurement within plant tissue was developed to study uptake and movement of cyanide species separately... 相似文献
932.
Lake Victoria and its basin supports more than 30 million people, while its fishes are exported the world over. This second largest fresh water body is however experiencing stress due to eutrophication, sedimentation, declining levels and more recently the motor vehicle sector. This contribution examines the general pollution from motor vehicle and gives an in-depth analysis of motor vehicle washing along the lakeshore. The results indicate the water samples from the motor vehicle washing and urban runoff points to be slightly acidic (i.e., average pH of 6.7) and average Total Phosphorus levels of 0.4 and 2.4 ppm respectively. This implies that there was high soap input at these points. The conductivity for the motor vehicle washing points averaged at 150 μS/cm, while the urban runoffs point was more varied ranging from below 150 μS/cm to over 400 μS/cm (average 301 μS/cm). A positive correlation coefficient of more than 0.7 is obtained between the total daily count of vehicles and each of the water quality parameter tested. This signifies a strong correlation between motor vehicle related activities and the pollution of the lake. In general, the motor vehicle industry is found to have a noticeable negative effect on the Lake. 相似文献
933.
Joseph A. Kozak Robert M. Aiken Gerald N. Flerchinger David C. Nielsen Liwang Ma Lajpat Ahuja 《Soil & Tillage Research》2007,95(1-2):84-96
RZ-SHAW is a hybrid model, comprised of modules from the Simultaneous Heat and Water (SHAW) model integrated into the Root Zone Water Quality Model (RZWQM) that allows more detailed simulation of different residue types and architectures that affect heat and water transfer at the soil surface. RZ-SHAW allows different methods of surface energy flux evaluation to be used: (1) the SHAW module, where evapotranspiration (ET) and soil heat flux are computed in concert with a detailed surface energy balance; (2) the Shuttleworth–Wallace (S–W) module for ET in which soil surface temperature is assumed equal air temperature; and (3) the PENFLUX module, which uses a Penman transformation for a soil slab under incomplete residue cover. The objective of this study was to compare the predictive accuracy of the three RZ-SHAW modules to simulate effects of residue architecture on net radiation, soil temperature, and water dynamics near the soil surface. The model was tested in Akron, Colorado in a wheat residue-covered (both standing and flat) no-till (NT) plot, and a reduced till (RT) plot where wheat residue was incorporated into the soil. Temperature difference between the soil surface and ambient air frequently exceeded 17 °C under RT and NT conditions, invalidating the isothermal assumption employed in the S–W module. The S–W module overestimated net radiation (Rn) by an average of 69 Wm−2 and underestimated the 3-cm soil temperature (Ts3) by 2.7 °C for the RT plot, attributed to consequences of the isothermal assumption. Both SHAW and PENFLUX modules overestimated midday Ts3 for RT conditions but underestimated Ts3 for NT conditions. Better performances of the SHAW and PENFLUX surface energy evaluations are to be expected as both approaches are more detailed and consider a more discretized domain than the S–W module. PENFLUX simulated net radiation slightly better than the SHAW module for both plots, while Ts3 was simulated the best by SHAW, with a mean bias error of +0.1 °C for NT and +2.7 °C for RT. Simulation results for soil water content in the surface 30 cm (θv30) were mixed. The NT conditions were simulated best by SHAW, with mean bias error for θv30 within 0.006 m3 m−3; RT conditions were simulated best by the PENFLUX module, which was within 0.010 m3 m−3. 相似文献
934.
Javier M. Gonzalez Douglas R. Smith Stan Livingston Elizabeth Warnemuende-Pappas Martha Zwonitzer 《Journal of Soils and Sediments》2016,16(7):1921-1932
Purpose
In a 6-year study, we investigated the effectiveness of blind inlets as a conservation practice in reducing pesticide losses compared to tile risers from two closed farmed depressional areas (potholes) in the US Midwest under a 4-year cropping rotation.Materials and methods
In two adjacent potholes within the same farm and having similar soils, a conventional tile riser and blind inlet were installed. Each draining practice could be operated independent of each other in order to drain and monitor each depression with either practice. Sampling events (runoff events) were collected from the potholes from 2008 to 2013 using autosamplers. The samples were analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine.Results and discussion
The results of this study demonstrated that the blind inlet reduced analyzed pesticide losses; however, the level of reduction was compound dependent: atrazine (57 %), 2,4-D (58 %), metolachlor (53 %), and glyphosate (11 %).Conclusions
Results from this study corroborate previous research findings that blind inlets are an effective conservation practice to reduce discharge and pollutants, including pesticides from farmed pothole surface runoff in the US Midwest.935.
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
936.
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
937.
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 (Znt, Pbt, Znex, Pbex) 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 (Corg), total N and S (Nt, St), Znt, Pbt, Znex, Pbex, basal respiration (BR), microbial biomass (Cmic) and Cmic-to-Corg 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 Znt + Pbt 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 Znt + Pbt 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 Corg-to-Nt ratio (r = 0.98). The models for Corg, Nt, and microbial properties were satisfactory but less accurate. NIRS failed to accurately predict St, Corg-to-St, Znt, Pbt, Znex, and Pbex. 相似文献
938.
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
939.
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
940.
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