荧假单胞杆菌化感作用的初步研究

1　引　　言化感作用 (Allelopathy)是指一种植物或微生物通过产生化学物质而对其它生物产生的直接或间接的刺激或抑制作用[7] .虽然有关高等植物之间化感作用的研究已有大量报道 ,但微生物对高等植物的化感作用研究报道却较少 ,尤其是细菌在生态系统中的化感作用往往被忽视[1] .荧光假单胞杆菌 (P .fluorescens)是定殖于植物根际的优势细菌种群 ,此类细菌以其分布广、适应能力强、繁殖速度快、易于人工培养等特点 ,成为最具生防潜力和应用价值的生防菌[5] .对陕西农田土壤有益微生物的筛选研究中发现 ,一株荧光假单胞杆菌培养液对番茄灰霉…     

外生菌根菌与森林树木的相互关系

生态系统的每个过程都伴随着各种微生物的活动,其中最重要的功能群之一是菌根真菌(菌根菌)。一般认为,菌根菌是自然界多数植物生存最基本的组成部分,陆地上约90％以上的高等植物都具有菌根菌。这些菌类的菌丝体与植物根系结合形成菌根,使植物生长成为可能,使不同种类植物的根系联在一起。根据菌根菌入侵植物根系的方式及菌根的形态特征,菌根可分为外生菌根、内生菌根和内外生菌根3组共7种类型。外生菌根主要出现在松科、桦木科、壳斗科等树种的森林生态系统中,在根系表面形成菌丝鞘,部分菌丝进入根系皮层细胞间隙形成哈氏网表面。菌根菌剂在森林经营中得到广泛地应用。外生菌根菌对森林树木的作用可归纳为：1)促进造林或育苗成活与生长;2)提高森林生态系统中植物的多样性、稳定性和生产力;3)对森林生态系统的综合效应,主要表现在增加植物一土壤联结,改善土壤结构,促进土壤微生物,增强植物器官的功能;4)抗拮植物根部病害病原菌等。树木与菌根菌相互关系研究主要包括：1)菌根共生的机理;2)菌根菌在退化森林生态系统恢复与改造中的作用;3)菌根菌的分布格局与森林生态系统服务功能的关系;4)菌根菌对森林生态系统的综合效应,如菌根菌与森林植物群落结构、物种多样性以及森林系统稳定性和生产力的研究。     

施用农用化学品及生防制剂对土壤线虫群落动态影响的研究

1　引　　言在农业生态系统中 ,农业管理 (如化肥、农药等农用化学品的施用等 )对土壤线虫群落组成及多样性产生了显著影响[2～ 4,7] .线虫是农田土壤中的生物因子 ,对植物的生长可以产生直接或间接的影响 .植物寄生线虫对植物的影响主要包括 3种方式 :1)通过在植物的根部取食 ,直接影响植物的营养状况 ,造成植物营养不良 ;2 )通过其口针的穿刺过程 ,传播植物病毒 ,引起植物病毒病 ;3)通过线虫取食植物根部造成的伤口 ,引起与其它植物病原物的复合侵染 .非植物寄生线虫多数是自由生活的线虫 ,在有人为影响的农田中主要是腐生线虫参与土壤中…     

增强的UV—B辐射对麦田生态系统Mg和Zn累积和循环的影响

近 2 0多年以来 ,ＵＶ Ｂ辐射增加对植物个体的影响受到了广泛的关注 ,而对植物群体和生态系统的影响仍然知道的很少[2 ] 。仅见ＵＶ Ｂ辐射对副极地石南灌丛和沙丘草地生态系统物种结构、生长、物候和叶分解等方面有报道[3,4 ] 。ＵＶ Ｂ辐射影响植物Ｍｇ和Ｚｎ吸收和运转[5～ 7] ,但对营养累积和物质循环的影响了解甚少[3] 。因此 ,大田条件下 ,植物群体和生态系统水平的营养累积和物质循环对ＵＶ Ｂ辐射的响应与反馈的研究 ,对于真实评估ＵＶ Ｂ辐射对生态系统的影响是必不可少的[2 ] 。ＵＶ Ｂ辐射对春小麦生长、生理、群体结构、植物营…     

蚯蚓对土壤-植物系统生态修复作用研究进展

土壤-植物系统是生物圈的基本结构单元,土壤与植物之间存在密切的相互反馈。土壤退化导致植物面临各种非生物胁迫,植物的生理代谢遭到干扰,养分获取受到抑制。蚯蚓被称为“生态系统的工程师”。蚯蚓能够通过调控土壤物理-化学-生物学特性,改良退化土壤(盐碱土、重金属和有机污染物污染土壤),缓解植物所受胁迫,增加土壤养分有效性,促进植物生长,并通过自身分泌的信号物质提高植物的抗逆性。蚯蚓对土壤-植物系统的生态修复作用,对于改善植物生长环境、维持土壤生态系统健康和稳定具有重要意义。     

秸秆覆盖免耕土壤细菌和真菌生物量与活性的研究

土壤微生物生物量在土壤生态系统中具有非常重要的作用。大量的试验研究表明 ,土壤微生物生物量是植物营养元素的一个重要的源与库 ,生物量对土壤养分的调控作用 ,已经成为土壤培肥、耕作制度改革和作物栽培实践中的重要理论依据之一。自从Jenkinson提出了测定土壤微生物量的原理和概念以来 ,Jenkinson和 Powlson提出了测定微生物生物量的方法[16] ,Van De Werf和 Verstraete提出了土壤微生物生物量可以分为全微生物量和活动微生物量[10 ] ,Anderson和 Domsch提出了生物量与生物活性中细菌与真菌的比例为 2 2 /78% [8]。虽然生物量的研…     

内蒙古草原放牧恢复过程地衣生物量分布及其影响因素的研究

1　引　　言在干旱半干旱草原生态系统中,地衣是植物群落中的一个重要组成部分.地衣是真菌和具有光合功能的藻类的共生体,共生光合生物通过光合作用为自身和共生真菌提供碳水化合物,共生真菌为共生光合生物提供物理保护、水和矿物元素[9] .地衣芽枝可通过截获风蚀物质而增加土壤表面粗糙度,有利于积蓄降水和养分[1] ,地衣的共生真菌菌丝可以通过分泌粘质物而改善土壤团粒结构[3 ] .另外,地衣还可有效地分解矿物元素,同时还有较强的固氮功能[9,17] ,地衣不仅影响土壤的理化性状而且对维管植物也有潜在的影响.因此,地衣在草原生态系统中可促进…     

湿地松混交林地土壤养分、微生物和酶活性的研究

1　引　　言土壤养分、微生物和酶是森林生态系统的重要组成成分 .土壤养分含量对林木生长有重要影响 .土壤微生物参与土壤的物质循环和能量转化[16] ,而土壤酶参与土壤的许多重要的生物化学过程和物质循环[18] ,二者一起推动着土壤的代谢过程 ,影响着林木生长 .长期以来 ,有关森林土壤养分、微生物和酶的研究受到广泛重视[4 ,6～ 2 0 ] .黎蒴栲 (Ｃａｓ ｔａｎｏｐｓｉｓｆｉｓｓａ)、红荷 (Ｓｃｈｉｍａｗａｌｌｉｃｈｉｉ)和湿地松 (Ｐｉｎｕｓｅｌ ｌｉｏｔｔｉｉ)是我国南方重要的用材树种 ,但是关于黎蒴栲×湿地松及红荷×湿地松混交…     

黄土丘陵区沙棘抗旱性的分析

近年来随着干旱发生频率的增加,研究植物的抗旱性已成为十分重要的任务,许多学者对此曾作过工作,蒋瑾[1]认为,旱生植物的蒸腾强度小,且变化稳定;刘家琼[2]发现,旱生植物在相同的环境条件下水势越低,吸水力越强,抗旱能力越强;山仑[3]研究结果表明在适度干旱的情况下,水分亏缺在一定程度上有利于植物生长;汤章成[4]研究发现,植物对逆境的抵抗是多方面的,是整体性的.     

植物对土壤微生物多样性的影响研究进展

土壤微生物作为土壤中较为主要的组成部分,在一定程度上反映了微生物构成的要素,同时对植物正常的生长以及发育具有重要的作用。植物与土壤微生物之间存在着多种多样的联系,植物类型、植物多样性、植物的基因组成、植物根系的发展以及植物不同的生长状况都对土壤微生物有着重要影响。本文从土壤微生物多样性出发,针对植物对土壤微生物多样性的影响进行了研究,希望进一步促进土壤微生物的发展以及生态系统的稳定。     

重金属对土壤中小麦种子发芽与根伸长抑制的生态毒性

测定了4种土壤（红壤、草甸棕壤、暗棕壤和栗钙土）条件下,Cu,Zn,Pb和Cd单一污染对小麦种子发芽与根伸长抑制主及其复合污染效应（暗棕壤条件下）。结果表明,同一浓度下,重金属对小麦根伸长抑制率均明显大于对种子发芽抑制率,植物根对金属污染的生态毒性比种子发芽敏感,土壤有机质和土壤N含量与Cu,Zn,Pb和Cd污染对小麦根伸长抑制率显著负相关（R^2OR=0.91,R^2K-N=0.92),土壤PH和阳离子交换量与Cu,Zn,Pb和Cd污染对小麦根伸长抑制率的相关性不显著（R^2PH=0.62,R^2CEC=0.60),在单一污染对小麦根伸长为刺激作用浓度（较低浓度）或为抑制作用浓度下（较高浓度）,复合污染均表现为协同作用。^     

土壤重金属污染对蚯蚓的急性毒性效应研究

测定了草甸棕壤条件下 ,Cu、Zn、Pb、Cd单一 /复合污染对蚯蚓的急性致死及亚致死效应 .结果表明 ,Cu、Pb浓度与蚯蚓死亡率显著相关 (α=0 .0 5 ,RCu=0 .86 ,RPb=0 .87) ,Cu浓度与生长抑制率显著相关 (α=0 .0 5 ,RCu=0 .84) ,其他供试重金属浓度与蚯蚓死亡率和生长抑制率相关性不显著 .蚯蚓个体对重金属毒性的耐受程度差别较大 .其毒性阈值 (引起个体蚯蚓死亡浓度 )分别为 :Cu 30 0mg·kg-1,Zn 130 0mg·kg-1,Pb 170 0mg·kg-1,Cd 30 0mg·kg-1.LC50 分别为 :Cu 40 0～ 45 0mg·kg-1,Zn15 0 0～ 190 0mg·kg-1,Pb2 35 0～ 2 40 0mg·kg-1,Cd 90 0mg·kg-1.在Cu、Zn、Pb、Cd单一污染引起 >10 %蚯蚓死亡的浓度下 ,复合污染导致 10 0 %蚯蚓死亡 ,表明复合污染极强的协同效应 .     

重金属复合污染对小麦种子根活力的影响

应用二次回归旋转设计法,以小麦种子为材料,研究了水培条件下重金属复合污染对其根生长及活力的影响;借助回归分析建立了相应的数学模型,分析了Cu、Zn、Cd和Pb4种重金属对根活力的毒性、两两重金属问的联合作用以及各重金属的边际毒性效应．结果表明重金属对根活力的影响顺序为Pb＞Cu＞Cd＞Zn;Cu与Cd、Cu与Zn、Zn与Cd以及Cd与Pb元素间的互作效应显著;在0-20mg.L^-1浓度范围内,Cu和zn两元素在最小浓度时的边际效应值最大,Cd和Pb两元素的边际效应最大值却出现在最高浓度处．     

Accumulation and translocation of heavy metals in the canola (Brassica napus L.)—soil system in Yangtze River Delta, China

Aims and methods

Concentrations of heavy metals such as Cd, As, Hg, Pb, Cr, Cu, Zn and Ni in different tissues (seeds, roots and shoots) of the mature canola (Brassica napus L.) plants and in the associated rhizosphere soils from Yangtze River Delta (YRD) region of China, were determined to evaluate the heavy metals’ pollution in the soils and the canola seeds, and to discuss their accumulation and translocation characteristics in canola plants. At the same time, the phytoextraction potential of the canola plant for the above heavy metals was theoretically calculated and discussed on the basis of above measured data.

Results

The results showed that the concentration ranges of Cd, As, Hg, Pb, Cr, Cu, Zn and Ni in the rhizosphere soils were 0.115–0.481, 3.40–20.5, 0.069–0.682, 9.92–27.4, 46.8–86.6, 17.7–253.3, 65.2–511.7 and 16.0–37.8?mg?kg^?1, respectively. The concentrations of Cu, Zn and Hg at some sampling sites exceeded the 2nd grade threshods of Chinese national environmental quality standard for soils. The potential ecological risk of heavy metals in the canola rhizosphere soils decreased in the order of Zhejiang > Shanghai > Jiangsu provinces. The concentration ranges of above heavy metals in the canola seeds were 0.032–0.067, 0.002–0.005, 0.001–0.005, 0.053–0.165, 0.191–0.855, 3.01–13.20, 34.82–96.95 and 0.343–2.86?mg?kg^?1, respectively, with Cu and Zn at some sampling sites exceeding the permissible concentrations in foods of China. Heavy metals’ concentrations in canola seeds didn’t increase with their increasing concentrations in the rhizosphere soils. The bioconcentration factors (BCFs) of most heavy metals in the canola seeds decreased with their increasing concentrations in the associated rhizosphere soils. The average BCFs of heavy metals decreased in the order of Zn (0.488)>Cd (0.241)>Cu (0.145)>Ni (0.038)>Hg (0.021)>Pb (0.005)=Cr (0.005)>As (0.000) in the canola seeds, Cd (1.550)>Cu (0.595)>Zn (0.422)>Hg (0.138)>Ni (0.085)>Pb (0.080)>As (0.035)>Cr (0.031) in the roots, and Cd (0.846)>Zn (0.242)>Cu (0.205)>Hg (0.159)>Ni (0.031)>Pb (0.025)>As (0.012)>Cr (0.007) in the shoots, respectively. The accumulation capacity for most of the above heavy metals in the mature canola tissues was root > shoot > seed, with the exceptions of seed > root > shoot for Zn and shoot > root > seed for Hg. Except Hg from root to shoot and Zn from root to seed, translocation factors (TFs) of above heavy metals were lower than 1.0.

Conclusions

The concentrations, BCFs and TFs of above heavy metals in the canola tissues indicated that the investigated canola plants did not meet the criteria of hyperaccumulators for the above heavy metals. The phytoextracton potential of the studied canola plants for the above heavy metals from the polluted soils was very limited. It would take 920, 3,170 and 3,762?years (assuming two crops per year) to reduce the initial soil Zn, Cu and Hg concentrations, respectively, from the most polluted soil concentrations to the 2nd grade thresholds of Chinese national environmental quality standard for soils.     

Eco-service enhancement in peri-urban area of coal mining city of Huaibei in East China

After 50 years of coal mining, Huaibei Mine, located at 50 km southeast of Xuzhou City in East China, has grown to a middle-size city of 600,000 people from a small village of 2000 farmers. The Zhahe Valley, with 400 km² of a built-up area and more than 100 km² of subsided peri-urban wetland at the city center, is surrounded by eight exhausted old mines and communities. In cooperation with the local city government, an ecological landuse change assessment and eco-city planning project has been carried out with a focus on the assessment, restoration and enhancement of the wetland as an eco-service to the community. The assessment includes relationships to Green House Gas emissions and heat island effects, as well as measures for a livable, workable, affordable and sustainable human settlement development through industrial transition, landscape design and capacity building. This paper will briefly introduce the main ecological approaches and results of the assessment, including measures such as changing the car-dominated transportation network to a rail-dominated network, transforming the coal-oriented high-carbon industry to a service-oriented low-carbon industry, the C-shape urban form to an O-shape with a green–blue core at the center, and the fragmentized collapsed land to integrative eco-service land.     

Heavy metal accumulation in iron plaque and growth of rice plants upon exposure to single and combined contamination by copper, cadmium and lead

A pot experiment was conducted to evaluate the bioaccumulation of heavy metals and growth response of rice plants after exposure to single and combined contamination by Cu, Cd and Pb. The results showed that the biomass production was not significantly affected by either single or combined treatment of Cu, Cd and Pb. Adding Cu (Cd, or Pb) separately all increased concentrations of the respective element in root and shoot (p < 0.001). In the combined contamination, Pb promoted both root and shoot absorption of Cu and Cd (p < 0.001), and Cu affected Cd and Pb absorption in the root, but Pb concentrations in both root and shoot were not affected by Cd application. The formation of iron plaques varied obviously with soil types. Heavy metal accumulation in iron plaques was induced by the three elements (p < 0.001). Furthermore, the three heavy metals exhibited an interactive relationship as measured by the Cu, Cd, Pb and Fe concentrations in root surface iron plaques. The iron plaques partially inhibited transfer of Pb to root and shoot, but no such effect was observed for Cu and Cd. This research indicates that the interaction among different heavy metal elements is very complex. It is very important to have a clear understanding on the associated mechanism and the consequential impact on plant growth.     

Heavy metal accumulation in iron plaque and growth of rice plants upon exposure to single and combined contamination by copper, cadmium and lead

A pot experiment was conducted to evaluate the bioaccumulation of heavy metals and growth response of rice plants after exposure to single and combined contamination by Cu, Cd and Pb. The results showed that the biomass production was not significantly affected by either single or combined treatment of Cu, Cd and Pb. Adding Cu (Cd, or Pb) separately all increased concentrations of the respective element in root and shoot (p < 0.001). In the combined contamination, Pb promoted both root and shoot absorption of Cu and Cd (p < 0.001), and Cu affected Cd and Pb absorption in the root, but Pb concentrations in both root and shoot were not affected by Cd application. The formation of iron plaques varied obviously with soil types. Heavy metal accumulation in iron plaques was induced by the three elements (p < 0.001). Furthermore, the three heavy metals exhibited an interactive relationship as measured by the Cu, Cd, Pb and Fe concentrations in root surface iron plaques. The iron plaques partially inhibited transfer of Pb to root and shoot, but no such effect was observed for Cu and Cd. This research indicates that the interaction among different heavy metal elements is very complex. It is very important to have a clear understanding on the associated mechanism and the consequential impact on plant growth.     

深圳市不同功能区土壤表层重金属污染及其综合生态风险评价

在综合考虑深圳市城市功能区分异特征的基础上,进行全市表层土壤系统采样,全面监测土壤表层8种重金属元素污染状况,分析不同重金属元素含量的统计学特征,探讨不同城市功能区对土壤表层重金属污染的影响,采用内梅罗指数和潜在生态危害指数评估不同重金属元素和不同城市功能区的生态风险水平,分别进行基于两种方法的全市重金属污染生态风险分区。结果表明: 1)深圳市土壤表层的Mn、Ni、Cr和Pb 4种元素受人为活动的影响程度较低,Cd、Zn、Cu和As 4类元素受人为活动影响较大。地表环境约束因素背景下的高强度城市化和工业化过程,是各种重金属污染区域分异和功能区分异的决定性因素。2)深圳市土壤重金属污染风险较高的重金属元素为Cd、Zn、Cu和Pb,特别是Pb污染问题尤为突出,必须加强管控工作。深圳市总体土壤表层重金属污染风险水平高于国内相关城市,需要引起足够重视。3)内梅罗指数法和潜在生态危害指数法的侧重点不同,在单一重金属元素风险判断、不同城市功能区生态风险的总体评价,以及市域土壤重金属污染生态风险分级评价方面结果差异较大,组合使用效果更好。     

胁迫时间与非毒性离子对重金属抑制拟南芥种子发芽及幼苗生长的影响

测定了Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺单一重金属胁迫对拟南芥种子发芽和幼苗生长的影响.结果表明,重金属对幼苗生长的毒性大于对种子发芽的毒性,以抑制种子发芽的IC₅₀为指标,4种重金属的毒性顺序为Hg²⁺＞Cd²⁺＞Pb²⁺/Cu²⁺,以幼苗生长为指标,则毒性顺序为:Cu²⁺＞Hg²⁺＞Cd²⁺/Pb²⁺,并随着胁迫时间延长,种子萌发率下降.此外,不同重金属在不同发芽时段对种子的毒性也不尽相同,Cd²⁺的毒性在种子吸水后的0～12 h大于12～24 h,而Hg²⁺毒性在12～24 h大于0～12 h,其中,种皮对减轻重金属毒性起着十分重要的作用.通过非毒性离子(Ca²⁺、Mg²⁺、K⁺、Na⁺)与重金属离子(Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺)交互作用对拟南芥种子发芽及幼苗生长效应的研究发现, mmol·L^-1的Ca²⁺、Mg²⁺、K⁺、Na⁺可以增强Hg²⁺对种子发芽的毒性,但对Cd²⁺的毒性却没有影响.对于幼苗来说,Ca²⁺、Mg²⁺、K⁺、Na⁺可以显著增强Hg²⁺的毒性,Ca²⁺可以缓解Cd²⁺的毒性,但却增加Cu²⁺的毒性,K⁺可以缓解Pb²⁺对幼苗的毒害作用.最后,本文对重金属的毒害机理进行了探讨.     

芜湖钢铁厂周边土壤及油菜籽中镉、铜、锌、铅含量和形态分布研究

研究了污染土壤、油菜籽中Cd、Cu、Zn、Pb含量、形态分布特征和重金属富集状况及可能存在的生物毒性.结果表明,土壤中Cd、Zn、Pb以铁锰氧化物结合态、Cu以残留态占5种形态最高比例,分别为31.1%、39.3%、53.79%、46.24%;Cd、Pb交换态比例较高,为23.47%、16.32%,Cu、Zn的交换态比例较小,为3.14%、0.54%;土壤中不同重金属与各重金属形态相关关系有差别,5种重金属形态转化为有效态重金属难易程度不同;油菜籽和油菜籽壳中不同重金属累积趋势有差异,Cu易在油菜籽壳中累积,Cd、Zn、Pb易在油菜籽中累积;油菜籽中不同重金属累积率不同,Cd累积率最高,为0.56.油菜籽中重金属累积率与土壤中重金属总量呈显著负相关关系(P＜0.05),土壤中重金属的形态、转化差异是此种负相关关系的主要原因;油菜籽中Cd、Cu、Pb以氯化钠态为主,分别为32.50%、22.94%、34.69%,Zn以EDTA态为主,为45.97%.油菜籽中重金属形态可能影响其毒性,但其毒性的人类膳食风险还需进一步研究证实.油菜籽中重金属形态与油菜中重金属总量相关性不好.