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481.
Winfried Schröder Marcel Holy Roland Pesch Harry Harmens Ilia Ilyin Eiliv Steinnes Renate Alber Yuliya Aleksiayenak Oleg Blum Mahmut Coşkun Maria Dam Ludwig De Temmerman Marina Frolova Marina Frontasyeva Laura Gonzalez Miqueo Krystyna Grodzińska Zvonka Jeran Szymon Korzekwa Miodrag Krmar Eero Kubin Kestutis Kvietkus Sébastien Leblond Siiri Liiv Sigurður Magnússon Blanka Maňkovská Juha Piispanen Åke Rühling Jesus Santamaria Zdravko Spiric Ivan Suchara Lotti Thöni Viktor Urumov Lilyana Yurukova Harald G. Zechmeister 《Journal of Soils and Sediments》2010,10(8):1572-1584
Purpose
This study aimed at investigating correlations between heavy metal concentrations in mosses and modelled deposition values as well as other site-specific and regional characteristics to determine which factors primarily affect cadmium, lead and mercury concentrations in mosses. The resulting relationships could potentially be used to enhance the spatial resolution of heavy metal deposition maps across Europe.Materials and methods
Modelled heavy metal deposition data and data on the concentration of heavy metals in naturally growing mosses were integrated into a geographic information system and analysed by means of bivariate rank correlation analysis and multivariate decision trees. Modelled deposition data were validated annually with deposition measurements at up to 63 EMEP measurement stations within the European Monitoring and Evaluation Programme (EMEP), and mosses were collected at up to 7,000 sites at 5-year intervals between 1990 and 2005.Results and discussion
Moderate to high correlations were found between cadmium and lead concentrations in mosses and modelled atmospheric deposition of these metals: Spearman rank correlation coefficients were between 0.62 and 0.67, and 0.67 and 0.73 for cadmium and lead, respectively (p?<?0.001). Multivariate decision tree analyses showed that cadmium and lead concentrations in mosses were primarily determined by the atmospheric deposition of these metals, followed by emissions of the metals. Low to very low correlations were observed between mercury concentrations in mosses and modelled atmospheric deposition of mercury. According to the multivariate analyses, spatial variations of the mercury concentration in mosses was primarily associated with the sampled moss species and not with the modelled deposition, but regional differences in the atmospheric chemistry of mercury and corresponding interactions with the moss may also be involved.Conclusions
At least for cadmium and lead, concentrations in mosses are a valuable tool in determining and mapping the spatial variation in atmospheric deposition across Europe at a high spatial resolution. For mercury, more studies are needed to elucidate interactions of different chemical species with the moss. 相似文献482.
Gert Poulsen Claus Holten Roland von Bothmer 《Genetic Resources and Crop Evolution》2007,54(5):1105-1115
Dead seeds of a fodder beet cultivar ‘Elvetham’ stored under ambient conditions since 1880 were compared to a homonymous sample
preserved in an on-farm situation in Denmark. DNA was isolated from single seeds and successfully applied to Amplified Fragment
Length Polymorphism (AFLP) analysis of the accessions. Six primer pairs were used to determine the similarity between the
two accessions based on 112 polymorphic bands. Furthermore, similarity among seven cultivars of fodder beets representing
the main types used in Scandinavia at the end of the 19th century was determined. This analysis was based on 152 polymorphic
bands. Differentiation among the seven cultivars was determined to a mean G
ST value of 0.438, while G
ST between the two ‘Elvetham’ accessions was 0.266. A principal coordinate analysis based on jaccards similarity index illustrates
that the two ‘Elvetham’ accessions are different from each other. The differentiation is higher than the value found between
two separate ‘Eckerndorfer’ accessions. The results indicate that the cultivated accession has changed. Additionally, the
value of applying old dead seed material for documentation in gene banks is demonstrated.
During the analysis it was found that DNA isolated from seeds and leaves behaved differently in the AFLP process, however,
the two fractions assigned to their common accession. 相似文献
483.
The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. The objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant R. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulation structure in each watershed as R. muscosa from expanding populations in fish-removal lakes dispersed to adjacent habitats. At all three fish-removal lakes, R. muscosa population densities increased significantly following the removal of predatory fish. The magnitude of these increases was significantly greater than that observed over the same time period in R. muscosa populations inhabiting control lakes that remained in their natural fishless condition. Following these population increases, R. muscosa dispersed to adjacent suitable (but unoccupied) sites, moving between 200 and 900 m along streams or across dry land. Together, these results suggest that large-scale removal of introduced fish could result in at least partial reversal of the decline of R. muscosa. Continued monitoring of R. muscosa at the fish-removal sites will be necessary to determine whether the positive effects of fish eradication are sustained over the long-term, especially in light of the increasingly important role played by an emerging infectious disease (chytridiomycosis, caused by Batrachochytrium dendrobatidis) in influencing R. muscosa populations. 相似文献
484.
This study describes a novel approach to separate three soil carbon (C) sources by one tracer method (here 13C natural abundance). The approach uses the temporal dynamics of the CO2 efflux from a C3 grassland soil amended with added C3 or C4 slurry and/or C3 or C4 sugar to estimate contributions of three separate C sources (native soil, slurry, and sugar) to CO2 efflux. Soil with slurry and/or sugar was incubated under controlled conditions, and concentration and δ13C values of evolved CO2 were measured over a 2‐week period. The main assumption needed for separation of three C sources in CO2 efflux, i.e., identical decomposition of applied C3 and C4 sugars in soil, was investigated and proven. The relative contribution to the CO2 efflux was higher, but shorter with an increased (microbial) availability of the C source, i.e., sugar > slurry > SOM. The shortcomings and limitations as well as possible future applications of the suggested method are discussed. 相似文献
485.
Lorenz A Osman F Sun W Nandi S Steinacher R Whitby MC 《Science (New York, N.Y.)》2012,336(6088):1585-1588
The formation of healthy gametes depends on programmed DNA double-strand breaks (DSBs), which are each repaired as a crossover (CO) or non-crossover (NCO) from a homologous template. Although most of these DSBs are repaired without giving COs, little is known about the genetic requirements of NCO-specific recombination. We show that Fml1, the Fanconi anemia complementation group M (FANCM)-ortholog of Schizosaccharomyces pombe, directs the formation of NCOs during meiosis in competition with the Mus81-dependent pro-CO pathway. We also define the Rad51/Dmc1-mediator Swi5-Sfr1 as a major determinant in biasing the recombination process in favor of Mus81, to ensure the appropriate amount of COs to guide meiotic chromosome segregation. The conservation of these proteins from yeast to humans suggests that this interplay may be a general feature of meiotic recombination. 相似文献
486.
对奥地利Wallersee沉积物中铁、锰的分布特征进行了分析,说明Wallersee沉积物中铁的循环比锰微弱,铁氧化物的还原作用受到了溶解氧和锰氧化物的双重控制。输入沉积物中的铁大部分都保存于沉积物中。锰氧化物的还原虽然也受到溶解氧的制约,但其还原作用仍比较激烈,孔隙水中有特征的还原峰,只不过峰位下移,所以铁对环境的敏感程度比锰高,沉积物中的铁具有环境记录意义,而锰不具有环境记录意义。铁氧化物中无定形铁氧化物优先还原,晶体铁氧化物可以向无定形铁氧化物转化,参与各种反应。 相似文献
487.
J. Colby Torbett Roland K. Roberts James A. Larson Burton C. English 《Precision Agriculture》2007,8(3):127-137
Site-specific information technologies (IT) provide knowledge about the spatial variability within a field to improve the
efficiency of inputs through variable-rate (VR) applications. Identifying factors that influence farmers’ perceptions of the
importance of precision farming (PF) technologies in improving the efficiency of phosphorus (P) and potassium (K) fertilizer
applications can help to determine why different groups of farmers adopt PF. Knowing these factors can be useful in targeting
specific groups of farmers to adopt PF and increase fertilizer efficiency to meet crop needs and reduce P and K losses to
the environment. Data were obtained from a 2001 mail survey of cotton (Gossypium hirsutum L.) farmers in six southeastern states in the United States of America. Ordered logit analysis was used to evaluate the level
of importance to those who had adopted PF technologies placed on such technologies they had used to improve the efficiency
of P and K applications. Results showed that such farmers found soil sampling by management zone or on a grid, and on-the-go
sensing most important. Precision farmers who used mapping and remote sensing found PF technologies least important. Older
precision farmers who rented larger proportions of their land and used computers for farm management were more likely than
other precision farmers to place greater importance on PF technologies in improving the efficiency of P and K applications. 相似文献
488.
Given the considerable challenges to the rapid development of an effective vaccine against influenza, antiviral agents will play an important role as a first-line defense if a new pandemic occurs. The large-scale use of drugs for chemoprophylaxis and treatment will impose strong selection for the evolution of drug-resistant strains. The ensuing transmission of those strains could substantially limit the effectiveness of the drugs as a first-line defense. Summarizing recent data on the rate at which the treatment of influenza infection generates resistance de novo and on the transmission fitness of resistant virus, we discuss possible implications for the epidemiological spread of drug resistance in the context of an established population dynamic model. 相似文献