地膜覆盖对土壤微生物群落结构的影响

采用磷脂脂肪酸(PLFA)法测定了沈阳农业大学棕壤长期定位试验站地膜覆盖条件下土壤微生物磷脂脂肪酸图谱及群落结构。结果表明:在玉米苗期,长期施氮肥处理土壤覆膜后大部分脂肪酸含量都有所提高;施有机肥处理的土壤覆膜后脂肪酸的含量有降低的趋势;有机无机肥配合施用处理的土壤覆膜会增加真菌的含量,但却降低了其他脂肪酸的含量;在不施肥处理的土壤中,覆膜会使一些支链脂肪酸的含量降低。抽雄期,施有机肥的土壤覆膜后除单饱和脂肪酸含量有所下降外,其他脂肪酸都会提高;不施肥土壤覆膜处理双不饱和支链脂肪酸及放线菌标志性脂肪酸10Me18:0的含量会有所提高。成熟期,施氮肥的土壤覆膜处理大部分脂肪酸的含量降低;有机肥处理土壤中各种脂肪酸如:15∶0,a17∶0,i17∶0,i19∶0,18∶0,10Me18∶0含量覆膜高于裸地;有机无机配施处理土壤中17∶0,br17∶0,18∶0,18∶2w6,10Me18∶0含量覆膜处理高于裸地;对照土壤中i15∶0,16∶0,17∶0,a17∶0,18∶0,18∶2w6,19∶0含量覆膜高于裸地。另外,从脂肪酸的变化看出,覆膜处理土壤微生物群落整体结构发生了改变,没有表现出明显的种群优势。但是,尽管土壤的施肥处理不同,覆膜处理土壤微生物群落结构有一致化发展的趋势。     

不同海拔茶树根系土壤微生物群落多样性分析

从福建省泉州市安溪县不同海拔铁观音茶园采集了根系区域土壤, 利用磷脂脂肪酸(PLFAs)生物标记法研究了不同海拔茶园根系土壤微生物群落多样性。结果表明, 不同海拔茶树根系土壤共检测22个PLFAs, 不同的PLFAs在不同海拔茶树根系土壤分布差异明显, 可分为完全分布和不完全分布两种类型。高海拔(834 m)茶树根系土壤分布的PLFAs种类和数量都最多, 分布最高的前3个生物标记为16:0(指示细菌)、18:3ω6c(6,9,12)(指示真菌)、18:00(指示嗜热解氢杆菌)。对不同海拔茶树根系土壤特征微生物PLFAs分析表明, 代表细菌的16:0、代表真菌的18:3ω6c(6,9,12)和代表放线菌的10Me 16:0相对生物量在不同海拔茶树根系土壤中分布量不同, 细菌分布量最大, 其次是放线菌, 真菌分布量最小。微生物群落PLFAs标记聚类结果显示, 当欧氏距离为11.51时, 可将不同海拔茶园根系土壤的PLFAs生物标记分成3个大的类群, 类群I的PLFAs生物标记为完全分布且分布量中等, 类群Ⅱ的PLFAs生物标记为完全分布且分布量较高, 类群Ⅲ的PLFAs生物标记为不完全分布且分布量较低。分析多样性指数表明, Shannon-Wiener指数、Simpson指数和Pielou指数均是海拔834 m处最大, 海拔717 m处最低。     

污染土壤的微生物多样性研究

土壤微生物多样性是土壤微生物生态学的重要研究内容，目前已成为国际上生态学发展的崭新方向之一。土壤微生物多样性包括微生物群落功能多样性、结构多样性及分子遗传多样性，是指示土壤生态系统稳定性及其功能的重要传感器。本文基于分离培养以及生物标志分子方法。从不同生态层次上认识微生物多样性，较全面、系统地综合评述国内外污染土壤环境的微生物群落功能、结构及分子遗传多样性的研究进展，并针对新形势下土壤污染所面临的新问题，探讨了近期土壤微生物生态学过程研究的重要手段与科学问题。     

多氯联苯污染土壤的微生物生态效应研究

以多氯联苯（Polychlorinated biphenyls,PCBs）自然污染的农田土壤为材料,分析土壤中微生物区系组成、生物量C、N、土壤基础呼吸以及微生物群落功能多样性的变化。研究结果表明,在以4-氯、5-氯同系物为主的PCBs污染土壤中,污染程度对土壤细菌、放线菌的数量影响不明显,而真菌的数量除与土壤污染程度有关,可能还受到土壤pH等性状的影响;土壤微生物C、N与土壤基础呼吸随污染程度的加剧呈下降趋势,但微生物C／N基本没有变化;Biolog分析显示,土壤微生物代谢剖面（AWCD）及Simpson指数在污染程度相差较大的两组土壤样品中差异均达到了显著性水平,表明PCBs污染引起了土壤微生物群落功能多样性下降,降低了微生物对不同单一碳源底物的利用能力。     

林下参根区土壤微生物群落结构的研究

为了解林下参的生长对土壤微生物群落结构的影响,采用磷脂脂肪酸(PLFA)法测定了5,10,15,20,25年生林下参根区土壤的微生物量的活性部分及群落结构的变化情况。结果表明:林下参根区土壤微生物群落均以i15:0,a15:0,18:1ω9t,16:0,16:1ω9c,18:1ω9c,br17:0,18:2ω6,i16:0,16:1ω9t的微生物为优势种群;林下参生长根区土壤微生物总量、细菌生物量、真菌生物量及放线菌生物量与对照相比均有提高,且15a以后提高的幅度更加明显;在菌群结构变化上,与对照相比20a及25a放线菌占有总生物量的比率有所提高,真菌占有比率有所下降。15年后的林下参土壤微生物结构朝着有利于人参生长的微环境方向发展,野山参在深山密林中健康生长几十年而不死亡可能与其土壤微生物群落结构有直接关系。     

重金属复合污染下土壤微生物群落功能多样性动力学特征

用碳素利用法对浙江省天台铅锌银尾矿区重金属复合污染土壤微生物群落功能多样性动力学特征进行了初步探讨。研究结果表明 ,矿区重金属复合污染降低了供试土壤的微生物群落代谢剖面 ,且群落代谢剖面值与培养时间之间呈非线性关系 ,其变化过程符合微生物种群生长动态模型 (S形 )。随着重金属复合污染程度的加剧 ,土壤微生物群落功能多样性动力学参数K和r值越低 ,参数s值所需的时间则越长。上述动力学参数与群落代谢剖面各自的主成分分析结果显示 ,微生物群落功能多样性的动力学参数K值和s值能够很好地区分矿区土壤重金属污染程度 ,并且其区分效果比微生物群落代谢剖面值好。土壤微生物群落功能多样性动力学特征的变化可以较好地显示矿区重金属复合污染土壤微生物群落对碳源利用模式的差异 ,反映矿区特定生境土壤微生物群落功能多样性的变化 ,在一定程度上揭示重金属胁迫下环境微生物种群作用机理。     

多氯联苯复合污染土壤的土著微生物修复强化措施研究

通过室内模拟试验,以不同C源、C/N比、水分及通透性为调控因子,对多氯联苯(PCBs)长期复合污染土壤的土著微生物强化修复进行了初步研究。结果表明,PCBs长期复合污染土壤中,在土壤水分含量为田间持水量的60%时,加入淀粉、葡萄糖和琥珀酸钠均在一定程度上增加了细菌和真菌数量,从而促进土壤中PCBs的土著微生物降解。不同种类的C源对PCBs污染土壤的土著微生物降解效果存在明显差异,且其降解效果与C源的施用剂量密切相关。当淀粉加入量为C1.0g/kg土时,土壤中PCBs的降解效果较好,而葡萄糖和琥珀酸钠加入量为C0.2g/kg土时,PCBs的降解效果明显。土壤C/N比为10:1的处理效果优于C/N比为25:1和40:1。土壤人为翻动有利于PCBs污染土壤中细菌和真菌的生长,提高土著微生物的代谢活性,从而促进土壤中PCBs的自然降解。这为进一步探讨加速土壤中PCBs降解的最适条件和研发POPs污染土壤的生物修复技术提供了科学依据。     

菜-菌轮作模式下土壤微生物群落结构及多样性的变化

为明确菜-菌轮作模式对土壤微生物的影响,基于高通量测序技术,对4种轮作模式下的土壤微生物群落结构与多样性进行了研究,结果显示：不同轮作模式下土壤样品中真菌和细菌OUT总数分别是2298和15840条,相较于常规轮作模式A,菜-菌轮作模式B、C、D下真菌的OUT总数、ACE指数、Chao1指数、Shannon指数降低显著,Simpson指数增加明显,但细菌的各参数没有显著的差异;其土壤全氮、碱解氮、速效钾、有机质含量显著高于常规轮作模式A;真菌的优势群落是子囊菌门,相对丰度在66%以上,枝孢属、镰刀菌属两类致病菌群的丰度在菜-菌轮作模式B、C、D中降低明显;细菌的优势群落是变形菌门、放线菌门、绿弯菌门以及酸杆菌门,鞘氨醇单胞菌属、伯克霍尔德氏菌属丰度在菜-菌轮作模式B、C、D中显著提高;聚类分析表明菜-菌轮作模式C、D下微生物群落结构相似度最高,常规轮作模式A可划分为区别于菜-菌轮作模式B、C、D的单独类群。综上所述,菜-菌轮作可降低真菌群落丰度,改变土壤微生物群落的结构组成,同时提高土壤中有益菌群的丰度,降低有害菌群的丰度。     

不同林龄马尾松人工林土壤微生物群落结构和功能多样性演变

土壤微生物在森林生态系统中起着至关重要的作用,研究人工林演变中土壤微生物群落结构特征,对评价人工林土壤质量动态变化和维持土壤微生态平衡具有重要意义。以亚热带地区马尾松人工林为研究对象,采用磷脂脂肪酸(Phospholipid fatty acid,PLFA)和BIOLOG技术研究不同林龄(13 a,25 a,38 a和58 a)对土壤微生物群落结构和代谢功能多样性的影响。结果表明:不同林龄土壤微生物类群均以细菌为主,其次为真菌和放线菌,最后为原生动物;土壤微生物总PLFAs量、真菌数量和真菌/细菌均表现为13 a最高,38 a最低;土壤细菌、革兰氏阳性细菌(G+)、革兰氏阴性细菌(G–)和放线菌数量均25a最高。层次聚类和主成分分析(PCA)结果表明,林龄对土壤微生物群落结构产生显著影响,13 a和25 a林龄分别与38 a和58 a林龄的土壤微生物群落结构差异较大。冗余分析表明,有机碳、全氮和pH是土壤微生物群落结构的主要影响因素。不同林龄土壤平均颜色变化率(AWCD)和微生物功能多样性指数(香农指数、辛普森指数和McIntosh指数)总体表现为25 a>13 a>58 ...     

渡良濑游水地土壤微生物群落结构与功能研究

利用BIOLOG和磷脂脂肪酸(PLFA)技术,研究了受足尾铜矿废水影响下的日本西那须地区渡良濑游水地东、西两侧土壤生物学特性、微生物群落结构及功能变化.结果表明:东侧(对照区)土壤全铜含量为45.07mg/kg,有效态铜含量为0.42 mg/kg,同西侧相比,平均降低了19.32%和89.95%.土壤呼吸速率主要受土壤有效态铜、土壤有机质和C/N的影响,随土层深度增加,土壤微生物量氮和溶解性氮都迅速减小,东侧土壤具有较强的氮矿化能力,渡良濑游水地东、西两侧0-5 cm土层土壤的微生物群落生理代谢剖面在培养48 h后出现明显变化;土壤微生物群落的平均颜色变化值(AWCD)随培养时间的延长,趋于平缓增加.在48 h时培养后,西侧位点土壤的AWCD值与东侧相比,分别下降了40%,34%和16%;除B位点样品在20-40 cm土层深度的AWCD略高于其它3个位点外,其余样品的AWCD无明显差异.渡良濑游水地东侧土壤微生物对单一碳源底物的利用能力较高,土壤微生物群落利用碳源的功能多样性也较高.渡良濑游水地西侧区域C位点土壤的格兰仕阳性菌、格兰仕阴性菌、放线菌数量均显著高于东侧A位点,但渡良濑游水地东侧区域土壤3大类群微生物中细菌和放线菌比例更高.在渡良濑游水地自然恢复30多年后,东、西两侧土壤微生物群落结构与功能仍存在较明显的差异.     

不同强化调控措施对多氯联苯污染土壤的修复效应

通过微宇宙试验,以添加碳源、翻耕、覆膜为调控因子,研究生物强化措施对多氯联苯污染土壤的修复效果,并对修复前后土壤微生物数量以及功能多样性进行研究。结果表明,土壤翻耕处理是最有效的修复措施,修复效率达到29.3%;添加淀粉与覆膜处理,效果相近,并且均显著高于对照。添加淀粉和翻耕均显著增加了土壤中细菌、真菌和放线菌的数量,但降低了土壤微生物功能多样性。而覆膜处理则使土壤微生物数量及其活性和多样性均下降。可见,不同的调控措施不仅能够强化土壤中多氯联苯的降解,同时也会影响到土著微生物群落结构及其活性和功能。     

Influence of polychlorinated biphenyls on microbial biomass and its activity in grassland soil

Microbial biomass content, soil respiration and biomass specific respiration rate were measured in two parts of an area polluted by a municipal waste incinerator [polychlorinated biphenyls (PCBs) from combustion processes]. The soils in the studied parts differed significantly only in their levels of PCBs. The concentration of PCBs found in a control plot (4.4 ng g^-1 soil) can be regarded as a background value while the polluted plot contained an increased amount of PCBs (14.0 ng g^-1 soil). A significantly lower microbial biomass (decreased by 23%, based on the chloroform-fumigation extraction technique) and a lower specific respiration rate (decreased by 14%) were observed in the polluted plot in comparison with the control plot at the end of experimental period (1992–1994). Furthermore, a lower ability of microorganisms in the polluted plot to convert available C_org into new biomass was found in laboratory incubations with glucose-amended samples.     

Concentration and distribution of polychlorinated biphenyls in soils of Moscow

The concentration of polychlorinated biphenyls (PCB) in the soils of Moscow has been determined by gas chromatography and high-resolution mass spectrometry (GC-HRMS). The total concentrations of 19 indicator and dioxin-like congeners, as well as PCBs in surface soils, are 2.85–60.62 μg/kg (the most contaminated sample was 4591.99 μg/kg). The average value, excluding the most contaminated sample, is 14.44 μg/kg, which is characteristic of residential areas of industrialized countries. This indicator varies insubstantially depending on the functional zone of the city. The toxicity equivalent of 12 dioxin-like PCBs in soils is 1.92 ng I-TEQ/kg on average and varies in a range from 0.15 to 334.12 ng I-TEQ/kg. The fraction of PCBs in the total toxicity of dioxins and dioxin-like compounds in soil varieties is 16.7–85.4%.     

The profile of congeners of polychlorinated biphenyls in soils of Moscow

The profiles of 19 indicative and dioxin-like congeners of polychlorinated biphenyls (PCBs) in the surface soils of distinct types of land use in Moscow are investigated. The penta- and hexachlorobiphenyls (46.7 and 31.6%, respectively) contribute significantly to the PCB spectrum. They used to make up the bulk of coolants and insulating fluids for electrical equipment, especially transformers. Among the congeners, the indicative PCB-101, -110, -138, and -153 and dioxin-like congeners PCB-105 and -118 dominate. They possess extremely high persistence and capability of bioaccumulation and exert harmful toxic influence, which should be taken into account when estimating an urban ecosystem??s ecotoxicological state.     

Effect of polychlorinated biphenyls on the physical properties of soils

Model experiments were performed for studying the effect of different concentrations (2 and 20 mg/kg) of polychlorinated biphenyls (PCBs) on the physical properties of natural materials (samples from the A horizon of loamy gray forest soil, river sand, and mantle loam). It was found that PCBs affect the aggregation of micro-and macroparticles in samples from the A horizon of gray forest soil and loam and the reflective properties of sand. It was also found that the coefficient of filtration in the substrates studied varies under the effect of PCBs. The rate of the water rising in the loam samples in the presence of PCBs decreases by 5.9 times for particles <3 mm and remains constant for particles <0.25 mm; in the samples from the A horizon of gray forest soil, the rate of the water rising increases by a factor of 1.3–1.9 for particles of all sizes. The water-retaining capacity of loam and gray forest soil from the A horizon decreases in the presence of PCBs.     

多氯联苯同系物在水稻土中的吸附行为比较

土壤是事关农产品生产环境质量安全的重要环境介质,同时因持久性有毒污染物多氯联苯(polychlorinated biphenyls,PCBs)在世界范围内普遍检出而备受科学界与政府关注。Ren等首次在中国范围内调查了52个采样点处表层土壤中的PCBs浓度,在其所有采样点处的PCBs平均浓度为     

Changes in tolerance of soil microbial communities in Zn and Cd contaminated soils

Trace metals are present in the soil matrix in different forms, and this obscures the relationship between the amounts of metals, their biological availability and effects. Chemical methods have been devised to directly measure the biological available pools of trace metals, but such methods need to be validated against measured exposure of organisms in the soil. We studied acquired Zn- and Cd tolerance of the soil microbial community as a reporter of its exposure, and compared it with chemical determination of Zn and Cd in 10 soils differing in pH, organic matter content, texture, vegetation-/cultivation history and metal contamination. The tolerance was measured as LC₅₀ (i.e. the metal concentration which inhibits 50% of the activity) in suspensions of extracted soil bacteria, by measuring the incorporation rate of [³H] thymidine at different metal concentrations. Chemical determination of Cd and Zn in soils included total concentrations by aqua regia extractions (AR), and total concentrations in extracted pore water (PW). In addition was the ‘effective concentration’ (C_E) determined using the Diffusion Gradients in Thins films method (DGT). The LC₅₀ values correlated better with PW (r²=0.90 for Cd and r²=0.97 for Zn) and C_E (0.90 for Cd and 0.98 for Zn) compared to the correlation with AR (0.72 for Cd and 0.82 for Zn). After excluding a single extremely contaminated soil from the analysis, the correlation of LC₅₀ with AR was much poorer (r²=0.03 (ns) for Cd and r²=0.48 for Zn), whereas correlations remained significant for both PW (0.90 for Cd and 0.87 for Zn) and C_E (0.54 for Cd and 0.84 for Zn). In conclusion, PW fraction of Cd and Zn appear to be the best predictor of trace metal exposure of the soil microorganisms.     

Changes in soil microbial biomass and functional diversity with a nitrogen gradient in soil columns

Fertilization generates nutrient patches that may impact soil microbial activity. In this study, nitrogen patches were generated by adding ammonium sulfate or urea to soil columns (length 25 cm; internal diameter 7.2 cm). Changes in nitrogen transformation, soil microbial biomass, and microbial functional diversity with the nitrogen gradients were investigated to evaluate the response of microbial activity to chemical fertilizer nutrient patches. After applying of ammonium sulfate or urea, the added nitrogen migrated about 7 cm. Microbial biomass carbon (MBC) was lower in fertilized soil than in the control (CK) treatment at the same soil layers. MBC increased with soil depth while microbial biomass nitrogen (MBN) decreased. BIOLOG analysis indicated that the average well color development (AWCD) and functional diversity indices of the microbial communities were lower in the 1 cm and 2 cm soil layers after application of ammonium sulfate; the highest values were in the 3 cm soil layer. AWCD and Shannon indices from the 1 to 5 cm soil layers were higher than those from other soil layers under urea application. Both principal component analysis and carbon substrate utilization analysis showed significant separation of soil microbial communities among different soil layers under application of ammonium sulfate or urea. Microbial activity was substantially decreased when NH₄⁺-N concentration was higher than 528.5 mg kg⁻¹ (1–3 cm soil layer under ammonium sulfate application) or 536.8 mg kg⁻¹ (1 cm soil layer under urea application). These findings indicated that changes in soil microbial biomass and microbial functional diversity can occur with a nitrogen gradient. The extent of changes depends on the nitrogen concentration and the form of inorganic fertilizer.     

玉米秸秆生物炭对褐土微生物功能多样性及 细菌群落的影响

生物炭施入土壤被认为是一种有效的固碳减排措施,可增加土壤有机碳及矿质养分含量,提高土壤的持水能力及保肥能力。为探明其施入土壤后对土壤微生物活性及多样性的影响,本文在盆栽试验条件下,采用Biolog与高通量测序相结合的方法,研究了CK(不施生物炭)和施用5 g·kg~(-1)、10 g·kg~(-1)、30 g·kg~(-1)、60 g·kg~(-1)玉米秸秆生物炭对土壤微生物碳源利用能力(AWCD)、功能多样性指数以及土壤细菌的丰度和多样性的影响。结果表明,随着生物炭施用量的增加,表征土壤微生物活性的AWCD值呈下降趋势,表现为:5 g·kg~(-1)处理≈CK10 g·kg~(-1)处理30 g·kg~(-1)处理60 g·kg~(-1)处理,其中CK和5 g·kg~(-1)处理间差异不显著(P0.05),而10 g·kg~(-1)、30 g·kg~(-1)和60 g·kg~(-1)处理在整个培养期间的AWCD值显著低于CK处理(P0.05);土壤微生物群落代谢功能多样性指数(H′)、碳源利用丰富度指数(S)均随生物炭施用量的增加而呈下降趋势,但均匀度指数(E)表现出相反趋势,5g·kg~(-1)、10 g·kg~(-1)、30 g·kg~(-1)、60 g·kg~(-1)各处理的H′较CK处理分别增加0.16%、-0.88%、-3.14%、-11.09%,S分别增加-2.82%、-11.27%、-18.31%、-47.89%,E分别增加1.14%、3.00%、3.73%和13.76%。主成分分析表明,与CK处理比较,5 g·kg~(-1)处理对土壤微生物群落碳源利用方式没有显著影响(P0.05),而10 g·kg~(-1)、30 g·kg~(-1)和60g·kg~(-1)处理对土壤微生物群落碳源利用方式影响显著(P0.05)。随着生物炭施用量的增加,土壤细菌OTU数目及丰富度指数(Chao1)呈增加趋势,5 g·kg~(-1)处理与CK处理差异不显著,而10 g·kg~(-1)、30 g·kg~(-1)、60 g·kg~(-1)处理的OTU数目较CK处理分别增加1.09%、5.26%、24.42%,Chao1分别增加5.73%、10.21%、37.68%。土壤中施用生物炭后土壤细菌变形菌门(Proteobacteria)的丰度在CK处理和5 g·kg~(-1)处理间差异不显著(P0.05),而10g·kg~(-1)、30 g·kg~(-1)、60 g·kg~(-1)处理较CK处理分别增加32.3%、21.1%、16.7%,拟杆菌门(Bacteroidetes)的丰度随着生物炭施用量的增加各处理较CK处理分别减少22.1%、55.3%、66.8%、50.5%。生物炭施入土壤后降低了土壤可培养微生物的活性,减少或改变了土壤微生物碳源利用的种类,使土壤原有微生物群落组分发生改变,生物炭也影响了土壤细菌各菌群在土壤中的丰度,使其分布的均匀性降低。为了不影响微生物群落结构和功能,石灰性褐土上生物炭一次还田量不能超过5 g·kg~(-1)(干土)。