3种植物对红壤中镉的富集特性研究

重金属超富集植物是重金属污染土壤植物修复的基础,研究了3种重金属富集植物羽叶鬼针草、美洲商陆和紫叶芥菜对重金属Cd的吸收积累规律,为植物修复Cd污染的农田和生态环境建设提供科学依据。采用盆栽方法,在不同浓度（0、20、35、50、65、80mg·kg^-1）Cd处理下,分别测定3种植物地上部与根部Cd的含量,计算了地上部Cd迁移量、根系耐性指数、富集系数,研究了土壤中Cd添加量与植物富集Cd量的相关性。结果表明,随着土壤中Cd离子浓度的升高,3种植物地上部和根系中的Cd含量也在增加,相关系数都大于0．99;综合地上部与根部Cd含量,地上部Cd迁移量,根系耐性指数和富集系数,3种植物对Cd的富集能力的相对顺序为：羽叶鬼针草〉美洲商陆〉紫叶芥菜。羽叶鬼针草、美洲商陆种植在Cd处理浓度为65mg·kg^-1的土壤中和紫叶芥菜种植在Cd处理浓度为80mg·kg^-1的土壤中栽培时,3种植物地上部与根部的Cd含量均超过了100mg·kg^-1,达到了Cd超富集量的标准。羽叶鬼针草、美洲商陆和紫叶芥菜对Cd有很强的耐受性和富集性,可以作为先锋植物去修复被Cd污染的土壤。     

重金属污染土壤的植物修复研究Ⅰ.金属富集植物Brassica juncea对铜、锌、镉、铅污染的响应

用来修复污染土壤的理想植物应具有高的生物量并能忍耐和积累污染物.印度芥菜(Brassica juncea)能富集多种重金属且生物量较大.本文研究了Zn、Cd、Cu、Pb 4种重金属对印度芥菜生长的影响,特别是重金属对印度芥菜地上部生物量的影响.结果表明,在含Cu 250 mg/kg、Pb 500mg/kg或Zn 500mg/kg的污染土壤上,印度芥菜能够忍耐,正常生长.印度芥菜在含Cd 200 mg/kg的土壤上发生镉毒而出现失绿黄化症状,Cd与中等浓度的Zn、Cu、Pb共存时毒害更为严重.这种植物适合Cu、Zn、Pb中等污染土壤的修复.     

铁改性生物炭促进土壤砷形态转化抑制植物砷吸收

通过盆栽试验研究了不同砷污染水平(10、20、40和80 mg/kg)下,添加不同量(10、20和40 g/kg)改性前后的生物炭对土壤砷形态及植物吸收砷规律的影响。该文以棉花秸秆生物炭及改性生物炭(棉花秸秆生物炭与Fe Cl3?6H2O按质量比为20∶1)为试材,小白菜为供试植物。结果表明:生物炭(10~40 g/kg)和改性生物炭(10 g/kg)能促进小白菜的生长,在添加量分别为20和10 g/kg时生物量最大,其最大值分别为8.26和6.68 g/盆,改性生物炭在添加量为10 g/kg时高于对照组和等量未改性生物炭处理组。在砷质量分数为10和20 mg/kg的基础上,添加生物炭(10~40 g/kg)后,土壤中砷主要以残渣态形式存在;水溶态砷分别增加了0.22%~3.36%和0.96%~3.70%;改性生物炭添加对土壤砷质量分数为10 mg/kg时水溶态砷无明显影响,土壤砷质量分数为20 mg/kg时,添加改性生物炭(10~40 g/kg)后水溶态砷减少了0.12%~0.58%。在高浓度(40和80 mg/kg)砷土壤中,水溶态砷含量随着土壤中砷含量的增加而增大;添加生物炭(10~40 g/kg)后,土壤中水溶态砷分别增加了0.21%~1.56%和2.11%~8.94%,但砷主要以铝形砷形式存在,残渣态砷次之。各处理组小白菜可食部分和根部砷质量分数在添加10~40 g/kg生物炭后的变化规律不尽相同,等量的改性生物炭添加后,可食部分由18.28 mg/kg显著降低至2.66 mg/kg(P0.05),根部从133.99 mg/kg显著降低至20.21 mg/kg(P0.05)。改性生物炭与未改性生物炭相比,改性生物炭能降低土壤中水溶态砷的含量及对小白菜吸收砷有显著的抑制作用。因此,该研究可为改性生物炭在含砷土壤的修复应用中提供数据支撑与理论基础。     

重金属污染土壤的植物修复研究Ⅰ.金属富集植物Brassica juncea对铜、锌、镉、铅污染的响应

用来修复污染土壤的理想植物应具有高的生物量并能忍耐和积累污染物。印度芥菜(Brassica juncea)能富集多种重金属且生物量较大。本文研究了Zn、Cd、Cu、Pb 4种重金属对印度芥菜生长的影响,特别是重金属对印度芥菜地上部生物量的影响。结果表明,在含Cu 250 mg/kg、Pb 500mg/kg或Zn 500mg/kg的污染土壤上,印度芥菜能够忍耐,正常生长。印度芥菜在含Cd 200 mg/kg的土壤上发生镉毒而出现失绿黄化症状,Cd与中等浓度的Zn、Cu、Pb共存时毒害更为严重。这种植物适合Cu、Zn、Pb中等污染土壤的修复。     

印度芥菜对土壤Cd,Pb的吸收富集效应及修复潜力研究

通过盆栽试验对比研究了印度芥菜(Brassica juncea)和油菜对复合污染土壤Cd,Pb的吸收富集效应及修复效率.初步探讨印度芥菜品种Wild Garden Pungent Mix净化重金属污染土壤的应用潜力.结果表明:Cd,Pb复合污染条件下,与油菜相比,印度芥菜对重金属Cd,Pb的抗耐性较强,地上部生物量较大,是同处理油菜的1.1～2.0倍.印度芥菜和油菜对重金属Cd,Pb的吸收富集表现出较为一致的特点,并且对土壤中重金属的吸收能力顺序均为Cd＞Pb,对土壤中Cd的吸收达到了100 mg/kg以上.表现出了超富集植物的特性.但相比之下,印度芥菜对土壤中Cd,Pb的吸收富集能力强于油菜.同时通过多元回归分析表明,两种植物对Cd,Pb的吸收不存在复合效应.本研究中,印度芥菜对Cd的净化率为0.35%～9.22%,是同处理下油菜的2.1～3.5倍;印度芥菜对Pb的净化率只有0.015%～0.356%,虽然是同处理下油菜的1.4～5.5倍,但远小于对Cd的净化率.研究表明,该品种印度芥菜具备应用于修复Cd污染土壤的潜力.     

耐受性植物油葵和棉花对镉的富集特征研究

耐受性植物可以作为重金属污染土壤修复的理想植物,探明其富集规律更是阐明其土壤修复机理和修复技术关键。采用潮褐土盆栽法,外源添加镉为1,5,15,30mg/kg,研究油葵和棉花对镉的耐受性和富集特征、吸镉量及其籽实镉含量的安全性。结果表明:(1)随外源添加镉量增加,油葵和棉花的耐受指数呈下降趋势。(2)Cd≤5mg/kg,对于油葵的干重产生促进作用,Cd≥15mg/kg,对油葵的干重产生抑制作用,外源添加镉对棉花的干重产生抑制作用。(3)油葵地上部最大吸镉量为每株601.95μg,棉花地上部最大吸镉量为每株74.83μg。(4)油葵和棉花的转运系数随外源添加镉呈现先升高后降低的趋势;在镉低浓度时,2种植物的富集系数大于1。(5)为保证油葵和棉花籽实符合食品国家安全标准,种植油葵的土壤中重金属镉的含量应低于1.11mg/kg,种植棉花的土壤中重金属镉的含量应低于3.48mg/kg。研究结果为重金属污染土壤的植物修复技术及阐明其耐受性植物修复机理提供了重要科学依据。     

重金属污染土壤的植物修复研究Ⅲ.金属富集植物Brassica juncea对锌镉的吸收和积累

采用温室盆栽试验研究了印度芥菜对土壤中锌镉污染的忍耐、积累能力 ,以检验这种植物修复Zn、Cd污染土壤的可能性及其潜力。在加入Zn 5 0 0和 1 0 0 0mgkg- 1 的土壤中 ,印度芥菜生长 66天后 ,叶片中积累Zn的平均浓度分别达 2 80和 662mgkg- 1 ,地上部带走的Zn分别为每盆 2 1 95和 341 2 μg。在加入Cd 2 0 0mgkg- 1 的土壤中生长的印度芥菜 ,叶片中积累Cd浓度为 1 61mgkg- 1 ,地上部带走的Cd为每盆 381 μg。和普通植物相比 ,印度芥菜更能将Zn和Cd从根运输到地上部。Zn 5 0 0mgkg- 1 处理的土壤在种植印度芥菜后其NH4NO3提取的Zn显著高于不种植物的处理 ;土壤添加Cd 2 0 0mgkg- 1 的处理NH4NO3提取的Cd也显著高于不种植物的处理 ,可能的原因是植物根分泌出特殊的分泌物 ,专一性地螯合溶解根系附近的难溶态Zn和Cd,从而提高土壤溶液中的浓度。印度芥菜对Zn、Cd有较强的忍耐和富集能力 ,是Zn、Cd污染土壤修复有潜力的植物。     

蚯蚓对污染土壤中黑麦草和印度芥菜吸收累积锌的影响

以长江冲积物形成的高沙土为供试土壤,分别加入4个浓度的Zn(100、200、300、400 mg/kg)以模拟Zn污染土壤,设置了接种蚯蚓(Pheretima sp.)处理与不加蚯蚓的对照处理,并种植黑麦草和印度芥菜,以研究蚯蚓活动对不同植物吸收、累积Zn的影响.结果表明:除低浓度Zn处理外(Zn≤100 mg/kg),蚯蚓活动明显增加了污染土壤的DTPA提取态Zn含量,进而促进植物对Zn的吸收.蚯蚓活动同时提高了印度芥菜和黑麦草地上部和地下部生物量及植株体Zn浓度,促进了植物对土壤Zn的吸收.加入蚯蚓后印度芥菜和黑麦草中Zn总累积量较无蚯蚓对照分别提高了57.8%～131.6%、51.4%～150.5%.两种植物相比,印度芥菜植株Zn浓度明显高于黑麦草,但由于印度芥菜生物量低,不论是否接种蚯蚓,其Zn累积量均低于黑麦草(未加Zn处理除外).黑麦草生长条件要求不高、可多次刈割,因而具有很大的修复中、轻度Zn污染土壤的潜力.     

蚯蚓对印度芥菜修复Zn、Pb污染土壤的影响

以褐土为供试土壤,分别加入不同浓度梯度Zn2+(0,100,200,400 mg kg^-1)或Pb2+(0,200,400,800 mg kg^-1)模拟土壤污染,设置添加蚯蚓与不添加蚯蚓处理,通过盆栽实验,研究蚯蚓对印度芥菜生长量和重金属吸收量的影响,旨在探讨蚯蚓在植物-土壤系统中影响重金属迁移转化的作用机理,为蚯蚓在植物修复技术的实践与完善提供理论参考。结果表明:(1)在Zn、Pb污染土壤中,蚯蚓生长率分别降低3%～24%、6%～29%;(2)蚯蚓活动可以降低土壤的pH,显著增加土壤中Zn的有效态含量;(3)蚯蚓活动显著增加了印度芥菜地上部生物量(22.6%～88.6%鲜重,31.3%～122%干重)和印度芥菜地上部Zn的浓度及Zn和Pb的吸收量。印度芥菜地上部重金属浓度和吸收量与土壤中DTPA提取态含量呈极显著正相关(P <0.01),与土壤pH呈负相关。(4)蚯蚓对重金属的活化和对植物生长的促进是解决植物修复瓶颈问题的有效手段。     

接种微生物对土壤中Cd、Pb、Zn生物有效性的影响

针对提高植物修复土壤重金属污染的效果,以印度芥菜作为重金属富集植物,通过盆栽试验研究了巨大芽胞杆菌和胶质芽胞杆菌的混合微生物制剂(A处理)和黑曲霉发酵液(B处理)对植物修复Cd、Pb、Zn污染土壤的作用效果。结果表明:巨大芽胞杆菌和胶质芽胞杆菌的混合微生物制剂,不仅可以促进富集植物的生长,使其印度芥菜的生物量提高24.73%,并且可促进土壤Cd、Pb、Zn的活化,使土壤Cd、Pb、Zn有效态含量分别提高15.02%、7.65%和2.23%,增强富集植物对土壤的Cd、Pb、Zn富集吸收,使印度芥菜对土壤Cd、Pb、Zn的提取量分别提高52%、121%和23%,显著提高其植物修复效果。从对植物生理生化指标的影响来看,A处理对植株的伤害程度要低于B处理,它是一种有助于植物修复Cd、Pb、Zn污染土壤的微生物制剂,在植物修复领域有较高的利用价值。然而,黑曲霉混合发酵液不适于促进植物修复应用。     

Formation of 2-alkyl-(2H)-thiapyrans and 2-alkylthiophenes in cooked beef and lamb

2-Alkyl-(2H)-thiapyrans and 2-alkylthiophenes have been identified in the volatiles of cooked beef and lamb. The quantities of both groups of compounds were higher in the meat of animals fed lipid supplements high in n-3 polyunsaturated fatty acids. 2-Alkyl-(2H)-thiapyrans were formed when (E,E)-2,4-dienals (C(6)-C(11)) and hydrogen sulfide were heated at 140 degrees C for 30 min. This confirmed their proposed route of formation in cooked meat from lipid-derived aldehydes and hydrogen sulfide; the latter was produced from the degradation of cysteine, via the Maillard reaction. The mass spectra and NMR spectra of these thiapyrans are reported for the first time. Although 2-alkyl-(2H)-thiapyrans were found to have only low odor potency, the reactions by which they are formed may have important implications for meat flavor. These reactions may remove potent aroma compounds and their intermediates from meat, thus modifying the overall aroma profile.     

Antioxidative activity of green tea treated with radical initiator 2, 2'-azobis(2-amidinopropane) dihydrochloride

This study investigated the antioxidative activity of green tea extract, and a green tea tannin mixture and its components, under conditions of radical generation using the hydrophilic azo compound, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate peroxyl radicals at a constant and measurable rate in the cultured renal epithelial cell line, LLC-PK(1), which is susceptible to oxidative damage. Treatment with AAPH decreased cell viability and increased the formation of thiobarbituric acid-reactive substances. However, green tea extract, and the tannin mixture and its components, comprising (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg), (-)-epicatechin 3-O-gallate (ECg), (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC), and (+)-catechin (C), showed protective activity against AAPH-induced cellular damage. The tannin mixture and its components exhibited higher antioxidative activity than the green tea extract. Furthermore, EGCg and GCg had higher activity than EGC and GC, respectively. In particular, EGCg exerted the most significant cellular protective activity against AAPH. These results indicate that green tea tannin may inhibit cellular loss and lipid peroxidation resulting from the peroxyl radical generated by AAPH, and that the chemical structure of tannin is also involved in the activity, suggesting that the O-dihydroxy structure in the B ring and the galloyl groups are important determinants for radical scavenging and antioxidative potential.     

2BLZ-2型垄上镇压式精密播种机的研制与试验

2BLZ-2型垄上镇压式精密播种机，设计安装了组合式仿形传动轮，集仿形传动作用为一体。采用了组合内窝孔式玉米排种器，实现精密播种。设置了两组弹簧，以保证播深一致及实现镇压力可调。通过田间作业试验和技术性能分析，证明该机具有良好的工作质量和可靠的技术性能。     

植物C_2H_2型锌指蛋白的研究进展

锌指蛋白是转录因子的一种,对真核生物的生长发育及逆境胁迫的耐受能力都有着重要关系,而植物C2H2型锌指蛋白是研究较多、较为明确的一种锌指蛋白,该蛋白大部分锌指结构具有一段高度保守的氨基酸序列QALGGH,这是植物中独有的特征,且据报道该C2H2型锌指蛋白与逆境胁迫是相关的。本文主要综述了植物C2H2型锌指蛋白的分类、结构和功能,植物C2H2型锌指蛋白与DNA、RNA和蛋白质的相互作用,以及概述了与盐胁迫、低温胁迫、干旱胁迫、氧胁迫和光胁迫等逆境胁迫相关的植物C2H2型锌指蛋白,最后还对其进一步的深入研究进行了展望,这就为日后利用基因工程技术改良作物品质、提高作物的抗逆性提供了有利条件。     

Antifungal activity of 4-methyl-6-alkyl-2H-pyran-2-ones

A number of 4-methyl-6-alkyl-alpha-pyrones were synthesized and characterized on the basis of 1H NMR and mass spectroscopy. These compounds were tested in vitro against pathogenic fungi, namely, Sclerotium rolfsii Saccardo, Rhizoctonia bataticola (Taub.) Butler, Pythium aphanidermatum (Edson) Fitz., Macrophomina phaseolina (Tassi), Pythium debaryanum (Hesse), and Rhizoctonia solani Nees. Lower homologues were less effective, whereas compounds such as 4-methyl-6-butyl-alpha-pyrone, 4-methyl-6-pentyl-alpha-pyrone, 4-methyl-6-hexyl-alpha-pyrone, and 4-methyl-6-heptyl-alpha-pyrone were found effective against all of the test fungi. They inhibited mycelial growth by approximately 50% (ED50) at 15-50 microg/mL. 4-Methyl-6-hexyl-alpha-pyrone, which was found most effective, was tested against S. rolfsii in a greenhouse at 1, 5, and 10% concentrations. The 10% aqueous emulsion of 4-methyl-6-hexyl-alpha-pyrone suppressed disease development in tomato by 90-93% as compared with the untreated infested soil in the greenhouse after 35 days of treatment.     

Anaerobic reoxidation of Mn2+, Fe2+, S0 and S2– in submerged paddy soils

Anaerobic reoxidation of reduced products in paddy soils was investigated. Ferrous iron (Fe²⁺) and monosulfide ion (S^2–) added to the soil chemically reduced MnO₂ to Mn²⁺, and MnO₂ and Fe(OH)₃ to Mn²⁺ and Fe²⁺, respectively, where Fe²⁺ and S^2– were considered to be oxidized to Fe³⁺ and S⁰. Elemental sulfur was oxidized to sulfate by anaerobic incubation with NO₃ ^– MnO₂ and Fe(OH)₃. A new conceptual model for the reduction processes in submerged paddy soil including the reoxidation processes of reduced products, in which soil heterogeneity in paddy fields was taken into consideration, was proposed based on the results. Received: 20 October 1996     

NO和H2O2依赖Ca2+/CaM信号调控马铃薯花青素积累

以不同块茎颜色马铃薯品种陇薯8号、陇薯7号、LC310-2和山东彩肉为材料,研究外源NO、H2O2、NO+ H2O2处理对马铃薯块茎花青素合成及其信号物质Ca2+-ATPase和CaM的影响.结果表明:外源NO和H2O2处理后,4个基因型马铃薯薯皮和薯肉花青素积累,Ca2+-ATPase活性升高,CaM含量增加,其效果为NO+ H2O2＞H2O2＞NO＞水(CK),并且花青素的积累量与Ca2+-ATPase活性和CaM含量均呈正相关,其平均决定系数达0.9194和0.8859.说明NO和H2O2对马铃薯花青素合成具有一定的促进作用,而细胞Ca2 +/CaM信号发挥了NO和H2O2对马铃薯花青素合成诱导的信号调节.     

Simulated warming and low O2 promote N2O and N2 emissions in subtropical montane forest soil

Journal of Soils and Sediments - The montane subtropical forest soils contain huge nitrogen stocks, and climate warming might drive its volatilization due to the promotion of gaseous losses of...     

Synthesis and sensorial properties of 2-alkylalk-2-enals and 3-(acetylthio)-2-alkyl alkanals

Parallel synthesis was applied to prepare a series of 3-(acetylthio)-2-alkyl alkanals by Michael addition of thioacetic acid under alkaline conditions to alpha,beta-unsaturated 2-alkyl-substituted aldehydes, which were obtained by aldol condensation of the corresponding primary aldehydes as starting materials. The target compounds were characterized in terms of GC, MS, and NMR data. The sensory properties of the odorants, such as odor quality and odor detection threshold value, were determined with a trained panel. Structure-activity relationships are discussed, suggesting that the 1,3-oxygen-sulfur functionality, required for the "olfactophore" of tropical/vegetable notes, can further be extended to the acetylthio derivatives.     

分子氢对红萍固氮活性的支持作用(英文)

本工作研究了分子氢对不同生长条件下三种红萍:细绿萍(Azollsa filiculoides),卡洲萍(Azolla caroniana)和小叶萍(Azolla microphylla)的固氮活性的支持作用,结果表明,在5000—20000lx不同光照强度下,分子氢对红萍固氮活性均有支持作用,当光照强度为10000lx时,10％的分子H_2可使红萍的固氮活性增加30—80％,在5000lx弱光条件下,相同浓度分子氢使红萍固氮活性增加的幅度比10000lx光照时大。在相同的光照条件下,大叶萍的固氮活性较高,分子氢对其固氮活性的支持作用也较强,说明了在萍藻共生体系中,光能利用、固氮效率与分子氢利用效率呈正相关。同时,分子氢对于红萍固氮活性受尿素毒害所致的抑制也有减慢作用。在培养液中尿素浓度超过5ppm时,红萍的固氮活性受到抑制,当尿素浓度达到50ppm时,其固氮活性抑制率达50—60％,但20％的分子氢可使其固氮活性恢复到正常培养下的70％以上。在一定的尿素浓度范围内,红萍固氮活性受抑程度愈大,分子氢对其减慢的作用也愈强。