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71.
Hermann Sierp 《Die Naturwissenschaften》1930,18(15):323-329
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Summary. The among-leaves allocation of DIBOA, a hydroxamic acid associated with plant resistance, in the shoot of rye (Secale cereale) was evaluated over the vegetative development of the plant. The appropriateness of using the concentration of secondary
metabolites, DIBOA in this case, as the parameter to evaluate defense allocation in plants is discussed. Both biological and
statistical arguments are put forward to suggest that allocation of chemical defenses should refer to absolute content and
not to concentration. Results showed that leaf age was significantly linked to leaf concentration of DIBOA, young leaves having
higher concentrations. In contrast, leaf content of DIBOA, our proposed currency of allocation, was not significantly higher
in younger leaves. Furthermore, a regression analysis showed that the DIBOA content of leaves was better explained by the
leaf relative biomass (proportion of shoot biomass) than by leaf biomass itself. It is suggested that, rather than leaf age,
leaf relative biomass is the major factor determining DIBOA allocation in rye shoots. It is proposed that studies addressing
within-plant defense allocation should use chemical defense content as the currency, emphasizing the major factors driving
this process and its underlying mechanisms. Likewise, it is proposed that studies aiming at characterizing optimal patterns
of plant defense should use chemical defense concentration as the currency, and be accompanied by evaluations of the actual
resistance against herbivores of the plant parts analyzed, together with the effect on plant fitness.
Received 19 February 1999; accepted 28 April 1999. 相似文献
74.
Hermann H. Dieter 《Environmental management》1992,16(1):21-31
The limit value of 0.1 μg/liter for “substances used in plant treatment and pest control including their main toxic degradation
products” (PBSM) established in the German Drinking Water Regulations (Trinkwasserverordnung) serves comprehensively to protect
drinking water from unexpected toxicological risks and thus corresponds to theaxiom of concern (Besorgnisgrundsatz) contained in §11,2 of the Federal Communicable Disease Control Act (Bundesseuchengesetz), which is an
essential cornerstone of the Drinking Water Regulations. Furthermore, precautionary values that are specific to the particular
substance and near the valid limit can be found for about 10% of all registered active substances. The goal of the PBSM Recommendations
of the Federal Health Office (BGA) issued in July 1989 is to preserve and restore groundwater and drinking water through measures
to be taken by the causal party, while reducing consumer health risks to the greatest extent possible. The EC commission's
drawbacks on these recommendations and the imminent EC-wide directive for the uniform registration of pesticides being based
solely on Article 43 of the European Treaty would seriously endanger this goal. Therefore, a situation threatens in Europe
similar to that in the United States, where at least 18 active ingredients have been detected in groundwater in concentrations
of up to 1000 times the toxicologically established limits for drinking water.
This article appeared first in the German journal?ffentliches Gesundheitswesen 52(8–9); 372–379, 1990. We thank the editor (Georg Thieme Verlag, D-7000 Stuttgart) for the kind permission to publish this
slightly revised English version inEnvironmental Management. 相似文献
75.
Frank Melzner Jörn Thomsen Wolfgang Koeve Andreas Oschlies Magdalena A. Gutowska Hermann W. Bange Hans Peter Hansen Arne Körtzinger 《Marine Biology》2013,160(8):1875-1888
Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO2 and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO2 partial pressure (pCO2) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO2 values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO2 (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO2 values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO2 in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO2 during hypoxia will increase proportionally: we calculate maximum pCO2 values of ca. 4,500 μatm at a salinity of 20 (T = 10 °C) and ca. 3,400 μatm at a salinity of 35 (T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO2-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments (pCO2 and pO2) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO2-enriched zones. The magnitude of expected changes in pCO2 in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought. 相似文献
76.
77.
Effects of solution conditions on the precipitation of phosphate for recovery. A thermodynamic evaluation 总被引:16,自引:0,他引:16
To understand the effects of solution conditions on the precipitation of calcium phosphates from wastewater for recovery, a computer programme PHREEQC was employed to calculate the speciation and saturation-index (SI) with respect to hydroxyapatite of a chemically defined precipitation system, which contains phosphate of 1–200 mg P/l, with Ca/P molar ratios of one to 10 times of the stoichiometric calcium to phosphorus molar ratio of hydroxyapatite, at a pH range of 7.0–11.0. The results show that the SI is respectively the logarithmic function of the phosphate concentration and the calcium concentration, increasing with the increase of either of them; the SI is a polynomial function of the solution pH value and increases with its increase, and the effect of solution pH value is due to its influence on base uptake of the precipitation reaction and the speciation of phosphate and calcium ions; the SI is also a logarithmic function of the solution ionic strength but decreases with its increase; at the temperature range of 5–30 °C the SI increases linearly with solution temperature and the effect of temperature is also due to its influence on the speciation of phosphate and calcium ions. 相似文献
78.
K. Bruce Jones Daniel T. Heggem Timothy G. Wade Anne C. Neale Donald W. Ebert Maliha S. Nash Megan H. Mehaffey Karl A. Hermann Anthony R. Selle Scott Augustine Iris A. Goodman Joel Pedersen David Bolgrien J. Max Viger Dean Chiang Cindy J. Lin Yehong Zhong Joan Baker Rick D. Van Remortel 《Environmental monitoring and assessment》2000,64(1):227-245
The Environmental Monitoring and Assessment Program (EMAP) is proposing an ambitious agenda to assess the status of streams and estuaries in a 12-State area of the western United States by the end of 2003. Additionally, EMAP is proposing to access landscape conditions as they relate to stream and estuary conditions across the west. The goal of this landscape project is to develop a landscape model that can be used to identify the relative risks of streams and estuaries to potential declines due to watershed-scale, landscape conditions across the west. To do so, requires an understanding of quantitative relationships between landscape composition and pattern metrics and parameters of stream and estuary conditions. This paper describes a strategic approach for evaluating the degree to which landscape composition and pattern influence stream and estuary condition, and the development and implementation of a spatially-distributed, landscape analysis approach. 相似文献
79.
Armin Hermann 《Die Naturwissenschaften》1988,75(5):219-224
80.