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排序方式: 共有275条查询结果,搜索用时 281 毫秒
111.
Razinger J Dermastia M Koce JD Zrimec A 《Environmental pollution (Barking, Essex : 1987)》2008,153(3):687-694
The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500microM. High accumulation of cadmium was observed (12,320+/-2155microgg(-1) at 500microM CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1microM CdCl2 (137+/-13.2% of the control) and its reduction to only 47.4+/-4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. 相似文献
112.
Bello D Trasar-Cepeda C Leirós MC Gil-Sotres F 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):611-617
Soil response to contamination with 2,4,5-triclorophenol was studied to test the validity of the concept of Generic Reference Levels (GRL), the main criterion used to define soil contamination. Soil samples were artificially contaminated with doses between 0 and 5000 mg kg−1 of 2,4,5-triclorophenol, and analysed by various tests. Where possible, the response of soils to the contaminant was modelled by a sigmoidal dose-response curve in order to estimate the ED50 values. The tests provided different responses, but only microbial biomass-C and dehydrogenase and urease activities demonstrated soil deterioration in response to contamination. The results suggest that the diagnosis of soil contamination has been greatly simplified in the legislation by the provision of a single figure for each compound, and that the GRL concept could perhaps be substituted by measurement of ED50 values, which better reflect the alteration of a soil due to the presence of a xenobiotic substance. 相似文献
113.
铜对夏腊梅种子萌发及抗氧化酶活性的影响 总被引:1,自引:0,他引:1
采用室内水培试验,研究不同浓度的外源铜处理对夏腊梅(Sinocalycanthus chinensis)种子萌发、根伸长抑制率、呼吸强度、丙二醛及抗氧化酶系统的影响.结果表明,(1)铜浓度与夏腊梅根伸长抑制率呈显著正相关(P<0.01),但与萌发率相关性不显著.(2)铜处理对夏腊梅种子的过氧化物酶(POD EC1.11.1.7)具有激活效应,且随着铜浓度的增加激活效应逐渐增强.丙二醛(MDA)含量随铜浓度的增大先略降而后逐渐升高.对超氧化物歧化酶(SOD EC 1.15.1.1)和过氧化氢酶(CAT EC 1.11.1.6)存在胁迫初期低浓度下的激活效应,随着铜浓度的增加及胁迫时间的延长,表现为抑制效应,且随着铜浓度的增加抑制效应逐渐增强. 相似文献
114.
城市污泥与园林废弃物混合堆肥施用对林地土壤微生物量碳、氮及酶活性的影响 总被引:2,自引:0,他引:2
研究城市污泥和园林废弃物混合堆肥施用对土壤微生物量碳(SMBC)、微生物量氮(SMBN)及酶活性的影响,可为林地施用混合堆肥产品的安全及功效性评价提供科学依据.本研究采用大田试验,选取紫穗槐为研究对象,将污泥和园林废弃物以3种比例(GF(纯园林废弃物)、SGA(V(污泥)∶V(园林废弃物)=1∶3)、SGB(V(污泥)∶V(园林废弃物)=1∶1))进行混合堆肥,每种堆肥产品分别按0、5、10、50 kg·株-1(分别记作CK、T5、T10、T50)均匀施入样地.施肥1年后,于田间采样测定土壤生物活性指标及理化性质,采用主成分分析及单、双因素方差分析法研究混合堆肥产品施用后对土壤酶活性及微生物量碳、氮含量的影响.结果表明:施入GF、SGA和SGB时,SMBC和SMBN均在施用量50 kg·株-1时达到最大.随着施用量的增加,土壤酶指数(SEI)总体上呈现逐步递增的趋势,施入GF、SGA、SGB时,各个施肥梯度处理的土壤酶指数较CK分别增加93.33%~186.67%、14.58%~54.17%、119.05%~204.76%.通过主成分分析,依据各处理综合得分情况,不同堆肥产品总体上表现为:SGBGFSGA.施入GF、SGA和SGB,不同处理综合得分均为T50T10T5CK.说明施用堆肥产品能够提高土壤微生物量,增加土壤酶活性,改善土壤的生物环境. 相似文献
115.
116.
117.
白腐菌降解纤维素和木质素的研究进展 总被引:20,自引:0,他引:20
纤维素和木质素是潜在的可再生资源,近年来,利用微生物对它们进行降解已成为研究的热点。虽然纤维素较木质素易降解,但其被木质素包裹,故降解的关键问题就是木质素的降解。本文从木质纤维素的生物可降解性出发,重点讨论白腐菌降解木质素酶系及其作用机理。 相似文献
118.
分析了生物体内多溴联苯醚(PBDEs)和四溴双酚A(TBBPA)的来源和分布,综述了PBDEs和TBBPA在生物体内发生还原代谢和氧化代谢的研究进展,从体内原位代谢和体外模拟代谢2个方面探讨了PBDEs和TBBPA的生物代谢机制、代谢途径及代谢中可能涉及的代谢酶,指出今后应进一步深入开展PBDEs和TBBPA的生物积累和代谢产物的定量分析的研究。 相似文献
119.
Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying
organisms, and enzyme activities in a rice-oilseed rape cropping system 总被引:9,自引:0,他引:9
LI Hu LIANG Xinqiang CHEN Yingxu LIAN Yanfeng TIAN Guangming NI Wuzhong 《环境科学学报(英文版)》2008,20(2):149-155
DMPP (3,4-dimethylpyrazole phosphate) has been used to reduce nitrogen (N) loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N (NH4^+- N and NO3^--N) leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone (UA), urea + 1% DMPP (DP), and no fertilizer (CK), have been carded out. The results showed that DP enhanced the mean NH4^+-N concentrations by 19.1%-24.3%, but reduced the mean NO3^--N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO3^--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system. 相似文献
120.
IntroductionEcto mycorrhizalfungiareknowntoamelioratemetaltoxicitytotheassociatedhigherplants (Bradley ,1981;1982 ;Brown ,1985;Bucking ,1995) .Theimprovementofheavymetaltolerancebymycorrhizalinfectionisrelatedtoareductionofshoottissueconcentration ,couplewithanincrea… 相似文献