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Testing the Aluminium Toxicity Hypothesis: A Field Manipulation Experiment in Mature Spruce Forest in Norway 总被引:1,自引:0,他引:1
Helene A. De Wit Jan Mulder Per H. Nygaard Dan Aamlid 《Water, air, and soil pollution》2001,130(1-4):995-1000
Aluminium (Al) has been considered to be a central element for risk evaluation of forest damage due to acidification. It has been hypothesized that Al reduces root growth, nutrient uptake and forest vitality. However, forest monitoring studies fail to show correlations between soil acidification and forest health. In general, no direct relation between Al concentration and forest health has been established. Here, Al concentrations in soil solution were manipulated by weekly additions of dilute AlCl3 to levels that are believed to be unfavorable for plant growth. Four treatments (in triplicate), including a reference and three Al addition levels, were established. Effects of enhanced Al concentrations on fine root growth, nutrient uptake and crown condition in a mature Norway spruce forest in Norway were tested (1996–1999). After three years of manipulation, crown condition, tree growth and fine root growth were not affected by potentially toxic Al concentrations. However, the Mg content in current year's needles decreased at the highest Al addition treatment. The Mg/Al ratio of fine roots of the same treatment had declined too, which suggests that Al blocked Mg uptake at the root surface. The manipulation will be continued for two more years. 相似文献
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A soil contaminated with polycyclic aromatic hydrocarbons, petroleum hydrocarbons and chlorophenols was bioremediated in field box plots. Three different bioremediation treatments (tillage and irrigation alone (box plot 2) or in addition to amendment with nitrogen and phosphorus (box plots 3 and 4) and additional organic amendment composed ofagricultural crop residues (box plot 4)) were comparedusing chemical analysis for target contaminants andsix toxicity tests (seed germination, earthwormsurvival, SOS Chromotest, Toxi-Chromotest, solid-phaseMicrotox® andred blood cell (RBC) haemolysisassay). Degradation was enhanced, and toxicity wasgenerally the most reduced, in box plots 3 and 4. Although chemical analysis indicated that the twoamendment protocols were equally effective, soiltoxicity was generally the most reduced in box plot 4. The earthworm survival and seed germination assayswere the most reliable and relevant toxicity tests. Difficulties arising with the other tests includedinsensitivity to changes in soil contaminant levels,inconsistency and interference by soil particles andother soil constituents. Because of the lack ofagreement between toxicity tests, these resultssupport the use of a battery of toxicity tests inconjunction with chemical analysis, when assessing theefficacy of bioremediation. 相似文献
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Helle Sørensen Nina Cedergreen Jens C. Streibig 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(4):562-577
We suggest a simple isobole analysis for binary mixture toxicity experiments. The analysis is based on estimated logarithmic
effect concentrations and their corresponding standard errors. The suggested model allows for synergism/antagonism and incorporates
within-mixture variation as well as between-mixture variation in a random effects model. The likelihood ratio test for the
hypothesis of concentration addition (CA) is examined, in particular its small sample properties. We study two datasets on
the joint effect of acifluorfen versus diquat and glyphosate versus mechlorprop, respectively, on the growth of the aquatic
macrophyte Lemna minor. 相似文献
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Kassandra Fronczyk Athanasios Kottas 《Journal of Agricultural, Biological & Environmental Statistics》2017,22(4):585-601
We present a Bayesian nonparametric modeling approach to inference and risk assessment for developmental toxicity studies. The primary objective of these studies is to determine the relationship between the level of exposure to a toxic chemical and the probability of a physiological or biochemical response. We consider a general data setting involving clustered categorical responses on the number of prenatal deaths, the number of live pups, and the number of live malformed pups from each laboratory animal, as well as continuous outcomes (e.g., body weight) on each of the live pups. We utilize mixture modeling to provide flexibility in the functional form of both the multivariate response distribution and the various dose–response curves of interest. The nonparametric model is built from a structured mixture kernel and a dose-dependent Dirichlet process prior for the mixing distribution. The modeling framework enables general inference for the implied dose–response relationships and for dose-dependent correlations between the different endpoints, features which provide practical advances relative to traditional parametric models for developmental toxicology. We use data from a toxicity experiment that investigated the toxic effects of an organic solvent (diethylene glycol dimethyl ether) to demonstrate the range of inferences obtained from the nonparametric mixture model, including comparison with a parametric hierarchical model.Supplementary materials accompanying this paper appear on-line. 相似文献
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Daniel Ginting Spencer L. Arnold Nicholas S. Arnold Ronald S. Tubbs 《Journal of plant nutrition》2013,36(9):1441-1454
Quantification of soil greenhouse gas emissions requires considerable sampling to account for spatial and/or temporal variation. With manual sampling, additional personnel are often not available to sample multiple sites within a narrow time interval. The objectives were to construct an automatic gas sampler and to compare the accuracy and precision of automatic versus manual sampling. The automatic sampler was tested with carbon dioxide (CO2) fluxes that mimicked the range of CO2 fluxes during a typical corn-growing season in eastern Nebraska. Gas samples were drawn from the chamber at 0, 5, and 10 min manually and with the automatic sampler. The three samples drawn with the automatic sampler were transferred to pre-vacuumed vials after 1 h; thus the samples in syringe barrels stayed connected with the increasing CO2 concentration in the chamber. The automatic sampler sustains accuracy and precision in greenhouse gas sampling while improving time efficiency and reducing labor stress. 相似文献
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A phenomenological model is described for predicting evaporation from bare and freely drained soils with a deep water table. The model delineates three classical and one transitional drying stage as the drying front advances into the soil profile. Daily evaporation is estimated from the daily potential evaporation rate e0 and depth of the drying front, Z, reached at the start of the day. The approximating relations used for calculating soil evaporation rate as a function of advancing drying front under different drying stages are presented. Input parameters of the model are simple and easily measurable under field conditions viz. daily potential evaporation rate, wilting point and field capacity moisture contents. Predictions of the model were tested using published data for cumulative evaporation. Good agreement was obtained under widely varying evaporative conditions. The model is simple and practical and may be used even for remote areas where the detailed information on soil water retention and transmission characteristics is not available. 相似文献
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Toxicity of cadmium and its competition with mineral nutrients for uptake by plants: A review 总被引:2,自引:0,他引:2
Cadmium(Cd)is a toxic heavy metal occurring in the environment naturally and is also generated through various anthropogenic sources and acts as a pollutant.Human health is affected by Cd pollution in farmland soils because food is the main source of Cd intake in the non-smoking population.For crops,Cd toxicity may result from a disturbance in uptake and translocation of mineral nutrients and disturbance in plant metabolism,inhibiting plant growth and development.However,plants have Cd tolerance mechanisms,including restricted Cd uptake,decreased Cd root-to-shoot translocation,enhanced antioxidant enzyme activities,and increased production of phytochelatins.Furthermore,optimal supply of mineral nutrients is one of the strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain.The emerging molecular knowledge contributes to understanding Cd uptake,translocation,and remobilization in plants.In this review,Cd toxicity and tolerance mechanisms,agricultural practices to minimize Cd accumulation,Cd competition with essential elements(calcium,copper,iron,zinc,and manganese),and genes associated with Cd uptake are discussed in detail,especially regarding how these mineral nutrients and genes play a role in decreasing Cd uptake and accumulation in crop plants. 相似文献
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甘蔗基因组DNA简单和快速提取方法 总被引:9,自引:0,他引:9
目前国内外关于提取DNA的方法很多(Honeycutt et al.,1992;顾红雅和瞿礼嘉,1998),但因研究的对象和目的不同而有所差异。甘蔗含有大量的酚和多糖等有机物质,由于这些物质的干扰,按照常规提取植物组织总DNA的方法提取甘蔗基因组DNA,常常因产量小和纯度低而不能满足实验要求。本实验在前人研究的基础上(Honeycutt et al.,1992;顾红雅和瞿礼嘉,1998),对所用药品及技术进行改进,摸索出一套快速、简便且可获得高质量基因组DNA的改良方法。用此方法提取的DNA进行酶切、RAPD和Southem杂交分析,都取得了良好的效果。 相似文献
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一种简单有效的提取马铃薯块茎总RNA方法 总被引:1,自引:0,他引:1
对于块根、块茎和果实等富含淀粉、多糖的特殊材料,应用常规方法提取RNA,存在产量低、淀粉和多糖污染严重等问题(Logemann et al.,1987).本研究采用马铃薯块茎为材料,通过改进变性液和抑制多酚氧化等环节,建立了一个改良的RNA抽提方法,有效的解决了在马铃薯块茎总RNA抽提过程中多糖污染和酚氧化等问题.…… 相似文献
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Flour swelling tests have been widely used to assess the intercultivar differences in starch properties. This note describes a modified flour swelling test which uses ≈30 mg of flour. It avoids the use of a high-temperature water bath, and does not require a set of uniform and leak-proof tubes. The modified procedure offers a simpler and more rapid alternative to those previously reported, and provides a similar level of discrimination and precision. It is particularly suitable as a micro-scale early generation test for wheat flour swelling properties. 相似文献
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一种适于PCR扩增的植物基因组快速提取新方法 总被引:3,自引:0,他引:3
在传统的碱裂解法提取基因组的基础上建立了一种新的基因组提取方法,这种方法对传统碱裂解制备基因组的方法进行优化,并且调整了中和剂的用量,引入异丙醇沉淀步骤对基因组进行纯化.实验证明这种方法扩大了碱裂解法制备基因组的适用范围,可直接从植物种子中快速提取出用于PCR(polymerasechain reaction)模板的基因组,对于600 bp以下的目的基因的检测效果显著,可以发现待测组分含量大于1%的样品.整个基因组提取时间控制在21 min,大大缩短了基因组提取时间,并且避免了酚/仿等对人体有害药品的使用. 相似文献
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应用battery生物测试法,检测研究农药废水对秀丽隐杆线虫的生命周期、繁殖速率、生殖能力、头摆和身体弯曲频率等影响的生物毒性,及其引发生物毒性的主要有机污染物。结果表明,在已经达到国家废水排放标准[GB 8978—1996]情况下,处理出水对受试动物仍然存在致毒效应;线虫的世代周期对进水的毒性最为敏感,产卵数量对出水的毒性最为敏感;进水毒性主要来自易受酸性调节影响的有机污染物,出水毒性主要来自易受碱性调节影响的有机污染物。结果表明,该项生物测试的毒性参数,可用于指示存在于低CODCr废水中的生物毒性;所用的毒性鉴别评价(TIE)方法,可用于鉴别废水中引发致毒效应的关键污染物。废水中悬浮颗粒污染物的生物毒性至关重要,尚未研究,有待继续。 相似文献
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建立了包含"水"和"底泥"两相的水蚤毒性测试系统(水相为全人工培养液,"底泥"为OECD配方标准化人工土),并通过该系统测得毒死蜱(chlorpyrifos)、氟虫腈(fipronil)、氰戊菊酯(fenvalerate)、氟氯氰菊酯(cyfluthrin)、联苯菊酯(bifenthrin)对大型溞(Daphnia magna)的急性毒性(48 h-LC50)分别为9.01、88.1、0.142、0.097 6、0.050 4μg.L-1。对比水相的急性毒性测定结果发现,在有底泥的条件下,所测得的联苯菊酯、氟氯氰菊酯、毒死蜱的大型溞毒性低于水相的测定结果,而氰戊菊酯、氟虫腈的毒性则比水相中的测定结果要高。研究结果反映出药剂和受试生物在"水-底泥"系统内相互作用的复杂性和难以预见性,从而在为相关农药生态安全评价提供科学依据的同时,为在更接近实际暴露状态下开展评价试验提供了一种简便有效的方法。 相似文献