氟啶虫胺腈在棉花和土壤中的检测方法与残留动态研究

研究和建立了氟啶虫胺腈在土壤、棉籽和棉叶中的高效液相色谱检测方法,并在天津和杭州两地开展了氟啶虫胺腈在棉花中的田间残留试验研究。样品采用乙腈提取,正己烷萃取,氟罗里硅土柱层析净化,正己烷/丙酮(体积比6∶4)混合液洗脱,减压浓缩至干,甲醇定容,高效液相色谱配可变波长紫外检测器进行检测。当分别在空白土壤、棉籽和棉叶样品中添加浓度为0.05~2.5mg·kg-1的氟啶虫胺腈标准品时,其平均添加回收率在76.81%~94.43%之间,相对标准偏差(RSD)在0.54%~7.20%之间;氟啶虫胺腈的最小检出量为1 ng,在所有样品中的最低检出浓度均为0.05mg·kg-1。田间残留试验结果表明,氟啶虫胺腈在土壤和棉叶中的消解规律符合一级动力学模型Ct=C0e-kt,消解半衰期分别为1.36~5.10 d和6.13~9.37d。最终残留试验结果表明,在棉花田手动喷雾施用50%氟啶虫胺腈水分散粒剂,按推荐剂量和1.5倍推荐剂量施药,兑水喷雾处理2~3次,每次施药间隔7 d,在距最后1次施药7、14 d和21d时,氟啶虫胺腈在棉籽和土壤中的残留量均小于方法最低检出浓度0.05mg·kg-1。     

不同形态氮素对种植大豆土壤中微生物数量及酶活性的影响

采用框栽试验方法,研究6种不同形态氮素[生物固氮(N0)、硝态氮(N1)、铵态氮(N2)、氨基酸态氮(N3)、蛋白态氮(N4)和酰胺态氮(N5)]对种植大豆土壤中微生物数量及土壤酶活性动态变化的影响。结果表明:各大豆生育期内真菌、细菌、放线菌数量和土壤脲酶、蔗糖酶活性对不同形态氮素的反应不同;三大菌群在组成上以细菌数量占绝对优势,数量上均在花期时达到峰值,即均随着大豆生育期的推进呈单峰曲线变化;花期不同形态氮处理下的土壤微生物总数量有差异,具体表现为N5N3N2N1N4N0。土壤多样性指数的变化趋势随着生育期的推进呈缓慢下降趋势,与土壤微生物数量的变化趋势不一致,因此,评价土壤生物多样性指数应将两者结合起来。土壤脲酶和蔗糖酶活性随着生育期的推进亦为单峰曲线变化趋势,但脲酶与蔗糖酶活性的变化趋势不同,其高峰期出现在鼓粒期。     

不同温度生物炭对油茶林红壤呼吸作用和酶活性的影响研究

烧制生物炭是油茶饼粕再利用的一项新措施。以福建油茶林红壤和不同温度(300℃和600℃)烧制的油茶饼粕生物炭为研究对象,在连续120 d微宇宙培养实验基础上,对不同时间土壤样品进行分析,研究生物炭对土壤呼吸作用和酶活性的动态影响。结果表明:施用300℃生物炭显著提高了土壤呼吸速率、脲酶、转化酶和酸性磷酸酶活性,且促进作用主要表现在培养的前30 d,而在整个120 d培养阶段,600℃生物炭对土壤呼吸速率和酶活性均无显著影响。冗余分析表明,土壤有机质和可溶性碳含量是影响红壤微生物呼吸作用和酶活性的最重要因素。综上,生物炭能够提高土壤微生物活性,提高土壤矿质养分有效性。本研究可为油茶饼粕生物炭在改良油茶林土壤方面的应用提供依据。     

珠穆朗玛峰北坡土壤过氧化氢酶与蔗糖酶活性研究

土壤酶主要源于土壤微生物代谢过程,以及土壤动物、植物根系分泌及残体分解[1,2],土壤酶活性反映土壤生物活性和土壤生化反应强度[3]。土壤酶活性与土壤物理特征(土壤水分、土壤温度、土壤空气、土壤团聚体)、有机质、pH、土壤微生物及土壤类型等关系密切[4]。环境因子如温度和湿度的变化、酸雨和臭氧等污染对土壤酶活性的影响也很大[5,6],因而土壤酶活性也可作为监测环境变化和污染对土壤质量影响的生物活性指标。此外,由于土壤酶活性与土壤碳、氮循环密切相关[7],因此土壤酶活性的研究常常还与全球气候变化相联系。目前土壤酶研究多集中…     

苯噻草胺对水田土壤呼吸强度和酶活性的影响

研究了除草剂苯噻草胺对水稻田土壤呼吸强度和酶活性的影响。表明苯噻草胺使用后初期刺激土壤呼吸作用但随后产生轻微抑制 ,能激活脱氢酶的活性 ,但抑制过氧化氢酶活性随后产生一定的刺激作用。苯噻草胺强烈抑制脲酶活性 ,轻微抑制蛋白酶活性 ,但对磷酸酶具有刺激作用 ,而且随苯噻草胺施用浓度的增加而刺激作用增强。苯噻草胺比上一代除草剂丁草胺所造成的对水稻田土壤呼吸强度和酶活性的影响小     

碘甲磺隆钠盐对土壤中过氧化氢酶活性及呼吸作用的影响

通过模拟实验研究了除草剂碘甲磺隆钠盐对土壤中过氧化氢酶活性和土壤呼吸作用的影响。结果表明,在施用量超过田间推荐用量7倍的浓度范围内,碘甲磺隆钠盐对土壤中过氧化氢酶活性的影响不明显;当其浓度为1mg/kg时,在不同培养时间下,碘甲磺隆钠盐施用后对土壤过氧化氢酶活性的影响呈现出轻微的抑制-激活-恢复的过程;在不同土壤类型中,碘甲磺隆钠盐对土壤过氧化氢酶的抑制性随土壤有机质的增加、pH值的降低而加强;碘甲磺隆钠盐对土壤呼吸作用有一定的影响,浓度愈大,土壤呼吸强度初期抑制愈强,随着时间的推移,逐步由抑制转为一定程度的刺激作用,到12天后施药土壤与对照组土壤的呼吸强度基本上趋于一致。实验结果表明,碘甲磺隆钠盐对土壤微生物影响较小,属于低毒或无实际危害的农药。     

连年翻压紫云英对早稻田土壤性质及酶活性动态的影响

依托7年定位试验,研究翻压紫云英对土壤pH值、有机质、碱解氮、有效磷、速效钾及蔗糖酶、脲酶、酸性磷酸酶活性动态的影响。试验设对照(不施化肥、不翻压紫云英)、化肥、紫云英+化肥3个处理。在紫云英翻压后2、4、8、16、32 d及早稻拔节期、孕穗期、收获期取样。结果表明,翻压紫云英对土壤性质和酶活性动态影响显著,土壤有机质、碱解氮、有效磷、速效钾动态变化与紫云英养分释放规律基本一致,而蔗糖酶、脲酶、酸性磷酸酶又与土壤有机质、碱解氮、有效磷等养分的动态基本一致。与化肥处理相比,紫云英+化肥显著提高了土壤pH值;在基础土壤有机质、碱解氮较高条件下,紫云英+化肥对蔗糖酶、碱解氮、脲酶等影响不显著,但在基础土壤有效磷、速效钾较低条件下,紫云英+化肥显著提升了有效磷、酸性磷酸酶活性及速效钾含量。因此,紫云英培肥土壤明显受土壤基础养分限制。     

三氯生与镉单一及复合污染对土壤呼吸和酶活性的影响

为了解典型药品和个人护理品(PPCPs)——三氯生与镉复合污染的生态效应,采用室内培养实验和联合毒性预测模型,首次评价了三氯生与镉单一及复合污染对土壤呼吸及参与土壤碳氮循环的相关酶活性的生态毒性。结果表明:三氯生与镉单一及复合污染对土壤呼吸呈现激活—抑制—激活的生态效应;刺激了蛋白酶活性,激活率先降低后升高,56 d时达到最大。整个实验期间均抑制了蔗糖酶活性,镉(10.0 mg kg-1)单一污染培养14 d抑制率达到最大值(81%),三氯生单一胁迫呈现负的剂量效应关系,两者复合污染无显著的剂量效应关系。联合效应评价模型预测表明,相比三氯生或镉单一污染,两者的复合胁迫对土壤呼吸呈现随时间变化的拮抗—协同—加和效应,对土壤蛋白酶呈现协同—加和—协同的联合效应,而对土壤蔗糖酶活性则主要为协同效应。     

四川丘陵区典型边坡土壤酶活性的季节动态

针对川中丘陵区成渝铁路的典型岩石边坡,以临近自然边坡和农田边坡为对照,研究了3种典型边坡土壤脲酶和蔗糖酶活性的季节变化规律.结果表明,各个季节土壤脲酶和蔗糖酶活性在不同类型边坡间表现出一定的差异性,且各具特点.3种边坡土壤脲酶和蔗糖酶活性均表现出一定的季节变化规律.铁路边坡和农田边坡土壤脲酶活性均表现为1月最低,4月最高;自然边坡土壤脲酶活性则表现为7月最低,10月最高.铁路边坡和自然边坡土壤蔗糖酶活性表现为1月最低,4月和10月较高;农田边坡土壤蔗糖酶活性1月,4月和7月无明显变化,在10月出现显著上升.     

施氮和再生水灌溉对设施土壤酶活性的影响

为探讨再生水灌溉和氮肥施用对土壤酶活性的影响,采用田间小区试验,以清水不施氮肥和再生水不施氮肥为对照,研究了4种氮素水平下再生水灌溉对土壤脲酶活性、蔗糖酶活性、淀粉酶活性和过氧化氢酶活性的变化及生育期土壤矿质氮、全氮的盈亏状况。结果表明,再生水灌溉提高了土壤脲酶和淀粉酶活性,降低了土壤蔗糖酶和过氧化氢酶活性;不同施氮水平下,再生水灌溉土壤脲酶活性、高氮处理土壤蔗糖酶活性和淀粉酶活性、低氮处理过氧化氢酶活性和番茄收获后土壤全氮含量均低于清水灌溉处理;相同灌水水质下,再生水灌溉施肥处理对土壤蔗糖酶活性、过氧化氢酶活性起到促进作用,对脲酶和淀粉酶活性有抑制作用,清水灌溉施肥处理对土壤脲酶活性、蔗糖酶活性起到促进作用,对淀粉酶和过氧化氢活性有抑制作用;再生水灌溉土壤矿质氮变化量较清水灌溉显著提高,而再生水灌溉下施肥处理降低了土壤矿质氮变化量。因此,适量减氮并辅以再生水灌溉处理能够提高土壤供氮能力和自净能力,增强土壤解毒能力并提升土壤肥力,减少再生水的排放和氮肥用量;不同施氮水平再生水灌溉对土壤脲酶、蔗糖酶、淀粉酶和过氧化氢酶活性及土壤矿质氮含量、全氮含量影响存在极显著差异。     

熏蒸处理对土壤微生物及硝化作用的影响

在田间条件下用溴甲烷(68.1g/m2)、威百亩(7.5mL/m2)进行土壤熏蒸,调查两种药剂对土壤微生物及硝化作用的影响。结果表明:两种熏蒸剂对土壤放线菌无抑制作用,对细菌总量影响较小,但亚硝酸细菌受到强烈抑制,土壤的硝化作用受到明显影响;同时,土壤中真菌的数量及种类变化显著。熏蒸后9周,处理区土壤中的微生物基本恢复正常。     

Are the links between soil aggregate size class, soil organic matter and respiration rate artefacts of the fractionation procedure?

Our aim was to see how variations in aggregate fractionation procedures influence the chemical and biological properties of different sized soil aggregates. Soil was fractionated using two different physical procedures: (1) slaking to simulate a major wetting stress in the field or (2) shaking to simulate mechanical disruption by tillage followed by wet sieving. In the slaked treatment, macro-aggregates (<250 μm dia) contained about 17% more soil organic C and had about 30% faster rates of respiration. This was in contrast to the shaken treatment where micro-aggregates (<250 μm dia) contained about 12% more soil organic C and had about 14% faster rates of respiration. The biological and chemical properties of different sized aggregates were used to describe two different models. These were the aggregate heirarchy model and one based on maximum biological activity at soil surfaces. Our results suggest that the chemical and biological properties of aggregates depend on the fractionation procedure. On this basis we suggest that the observed relationships between aggregate size and other properties, for example biological activity, must be interpreted in terms of the disruptive mechanisms used to fractionate aggregated soil. Our results suggest that the aggregate hypothesis has serious weaknesses: the aggregates measured being largely an artefact of the chosen method of separation. We therefore suggest that future work should also consider biological activities at soil pore surfaces. It is at the surface of these channels that parameters such as oxygen supply, plant roots, root exudates and fresh organic matter inputs first interact with the soil. Biological processes in this region are therefore likely to be more important than those occurring in the bulk soil.     

Relationships between soil respiration and soil moisture

The interaction of soil microbes with their physical environment affects their abilities to respire, grow and divide. One of these environmental factors is the amount of moisture in the soil. The work we published almost 25 years ago showed that microbial respiration was linearly related to soil-water content and log-linearly related to water potential. The paper arose out of collaboration between two young researchers from different areas of soil science, physics and microbiology. The project was driven by not only our curiosity but also the freedom to operate without the constraints common to the current system of science management. The citation history shows three peaks, 1989, 1999 and from 2002 to the present day. Interestingly, the annual citation rate is as high as it has ever been. The initial peak is due to the application of the work to studies on microbial processes. The second peak is associated with the rise of simulation modelling and the third with the relevance of the findings to climate change research. In this article, our paper is re-evaluated in the light of subsequent studies that allow the principle of separation of variables to be tested. This re-evaluation lends further credence to the linear relationship proposed between soil respiration and water content. A scaled relationship for respiration and water content is presented. Lastly, further research is suggested and more recent work on the physics of gas transport discussed briefly.     

4种农药对枇杷园土壤磷酸酶活性及微生物呼吸的影响

应用室内培养方法研究了甲基托布津、代森锰锌、杀灭菊酯、阿维菌素4种农药对枇杷园土壤磷酸酶活性及微生物呼吸的影响,并对4种农药进行了安全性评价。结果表明,经杀菌剂甲基托布津和代森锰锌处理的土壤,磷酸酶活性受到明显抑制,且抑制效果未见恢复。经杀灭菊酯和阿维菌素处理的土壤,磷酸酶活性变化呈现"抑制-恢复-激活"趋势;抑制作用随农药浓度的升高而增强;但7d后磷酸酶活性受到了一定程度的激活,35d达到最高值;高浓度杀灭菊酯和低浓度阿维菌素显示出较强的激活作用。农药对土壤微生物呼吸作用的影响初期表现为轻微激活,5d后出现抑制作用,12d后基本恢复正常,接近对照水平。通过安全性评价可知,供试4种农药对土壤微生物的危害较小,为无毒害或无实际危害的农药。     

腾格里沙漠植被重建对土壤呼吸的影响

植被重建是防止和控制沙漠化的有效措施之一。为探讨腾格里沙漠植被重建对土壤呼吸的影响,利用Li-6400-09土壤呼吸室于2007年观测了1989年建立的植被重建区和流沙区土壤呼吸差异,并采用根系隔离法区分了植被重建区的土壤基础呼吸和根际呼吸。结果表明,植被重建18a显著影响了该区土壤CO2的释放过程,总土壤呼吸速率由流沙区的CO20.107±0.008μmolm-2s-1显著增加到植被区CO20.483±0.033μmolm-2s-1,而且出现了较为明显的季节波动。植被重建不但导致根际呼吸速率增加,而且影响了土壤基础呼吸速率。此外,植被重建区灌木的缀块状分布格局和养分的空间异质性导致了土壤呼吸的空间差异。     

土壤改良剂对冷浸田土壤特性和水稻群体质量的影响

以南方典型冷浸田为研究对象, 在明沟排水的基础上, 通过田间定位试验, 以不施土壤改良剂为对照, 研究了施用不同土壤改良剂(自研的脱硫灰改良剂、生物活性炭, 市售的土壤改良剂石灰、硅钙肥、腐植酸)对冷浸田氧化还原电位、土壤呼吸强度、土壤微生物数量、水稻群体构建及产量构成因素的影响。结果表明, 施用改良剂能够改善土壤理化性状, 提升土壤速效养分和pH,但除脱硫灰处理外, 其他改良剂处理对土壤Eh未产生显著影响。施用不同土壤改良剂在水稻各生育期均能有效增强土壤微生物呼吸强度和放线菌数量, 并且放线菌数量达到差异性显著水平(P<0.05), 生物活性炭处理下土壤呼吸强度和放线菌数量分别较对照增加67.6%和127.6%。各土壤改良剂处理与CK相比较均有助于提高叶片SPAD、茎蘖数、水稻干物质积累量、成穗数、穗粒数、产量结实率和根系伤流速率。其中以脱硫灰和生物活性炭处理改良效果最佳, 抽穗后29 d时,根系伤流速率较CK分别提高45.4%和39.1%, 叶片SPAD分别增加27.4%和22.5%; 成熟期水稻成穗数较对照提高12.1%和10.7%,干物质积累量增加68.8%和50.5%,产量分别增加12.8%和10.3%。综上所述, 土壤改良剂可有效改善冷浸田土壤特性及水稻群体质量, 脱硫灰和生物活性炭处理的改良效果最明显, 增产幅度最大。     

Effects of mechanical energy inputs on soil respiration at the aggregate and field scales

Cultivation machinery applies large amounts of mechanical energy to the soil and often brings about a decrease in soil organic carbon (SOC). New experiments on the effects of mechanical energy inputs on soil respiration are reported and the results discussed. In the laboratory, a specific energy, K, of 150 J kg⁻¹, similar to that experienced during typical cultivation operations, was applied to soil aggregates using a falling weight. Respiration (carbon dioxide, CO₂ emission) of the samples was then measured by an electrical conductimetric method. Basal respiration (when K=0) measured on Chromic Luvisol aggregates, was found to increase with increasing SOC, from 1.88 μg CO₂ g⁻¹ h⁻¹ for a permanent fallow soil (SOC=11 g kg⁻¹) to 8.25 μg CO₂ g⁻¹ h⁻¹ for a permanent grassland soil (SOC=32 g kg⁻¹). Basal respiration of a Calcic Cambisol, more than doubled (2.0–5.2 μg CO₂ g⁻¹ h⁻¹) with increasing gravimetric soil water contents. Mechanical energy inputs caused an initial burst of increased respiration, which lasted up to 4 h. Over the following 4–24 h period, arable soils with lower SOC contents, (11–21 g kg⁻¹), respiration rates dropped back to a level, approximately 1.14 times higher than the basal value. However, grassland soils with higher SOC contents (28–32 g kg⁻¹), increases in this longer-term respiration rate following 150 J kg⁻¹ of energy, were negligible. A field experiment, in which CO₂ was measured by infra-red absorption, also showed that tillage stimulated increased levels of soil respiration for periods ranging from 12 h to more than one week. The highest respiration rates, 80 mg CO₂ m⁻² h⁻¹ were associated with high energy, powered tillage on clay soils. On the same soil, low energy draught tillage resulted in a respiration rate of approximately half this value. The results of these experiments are discussed in relation to equilibrium levels of soil organic matter. The application of known quantities of mechanical energy to soil aggregates under laboratory conditions, in order to simulate the effect of different cultivation practices, when combined with the subsequent measurement of soil respiration, can provide useful indication of the likely consequences of soil management on SOC.     

乙草胺对土壤微生物数量和酶活性的影响

采用室内瓶培养试验,研究了乙草胺施用对土壤微生物数量及酶活性的影响。结果表明:乙草胺施用初期对土壤细菌和放线菌数量有明显刺激作用,但施用30d时高施用量处理(30mg·kg-1)呈明显抑制作用,之后各处理放线菌恢复到对照水平,而对细菌的抑制作用一直持续到60d;乙草胺对土壤真菌数量呈"抑制-恢复-刺激"的作用趋势。乙草胺施用初期对土壤脱氢酶产生一定刺激作用,45d后高施用量处理呈明显抑制作用,一直持续到60d;土壤过氧化氢酶对乙草胺不敏感,而转化酶和脲酶对乙草胺施入初期较敏感;低施用量处理对转化酶有抑制作用,高施用量处理对转化酶有刺激作用,各处理对脲酶都有抑制作用。     

不同施肥管理措施对土壤碳含量及基础呼吸的影响

连续7年试验研究了施用15t/hm2和7.5t/hm2有机肥(包括EM堆肥、EM鸡粪肥和传统堆肥)、化肥和对照处理对土壤碳含量与基础呼吸的影响,结果表明:随有机肥施用量的提高,土壤可溶性碳、总有机碳、微生物生物量碳和土壤的基础呼吸随之增加。施用化肥可一定程度提高土壤可溶性碳、总有机碳、微生物生物量碳和土壤的基础呼吸。不同施肥措施对土壤有机碳、微生物生物量碳和土壤基础呼吸的影响趋势为EM堆肥处理>传统堆肥处理>化肥处理>对照,施肥对土壤微生物代谢商的影响趋势为EM堆肥处理<传统堆肥处理<化肥处理<对照。土壤微生物生物量碳与可溶性碳、总有机碳及土壤基础呼吸之间呈极显著正相关。土壤微生物代谢商与土壤可溶性碳、总有机碳、微生物生物量碳及基础呼吸之间呈极显著负相关。     

Effects of soil frost on growth, composition and respiration of the soil microbial decomposer community

Most climate change scenarios predict that the variability of weather conditions will increase in coming decades. Hence, the frequency and intensity of freeze-thaw cycles in high-latitude regions are likely to increase, with concomitant effect on soil carbon biogeochemistry and associated microbial processes. To address this issue we sampled riparian soil from a Swedish boreal forest and applied treatments with variations in four factors related to soil freezing (temperature, treatment duration, soil water content and frequency of freeze-thaw cycles), at three levels in a laboratory experiment, using a Central Composite Face-centred (CCF) experimental design. We then measured bacterial (leucine incorporation) and fungal (acetate in ergosterol incorporation) growth, basal respiration, soil microbial phospholipid fatty acid (PLFA) composition, and concentration of dissolved organic carbon (DOC). Fungal growth was higher in soil exposed to freeze-thawing perturbations and freezing temperatures of −6 °C and −12 °C, than under more constant conditions (steady 0 °C). The opposite pattern was found for bacteria, resulting in an increasing fungal-to-bacterial growth ratio following more intensive winter conditions. Soil respiration increased with water content, decreased with treatment duration and appeared to mainly be driven by treatment-induced changes in the DOC concentration. There was a clear shift in the PLFA composition at 0 °C, compared with the two lower temperatures, with PLFA markers associated with fungi as well as a number of unsaturated PLFAs being relatively more common at 0 °C. Shifts in the PLFA pattern were consistent with those expected for phenotypic plasticity of the cell membrane to low temperatures. There were small declines in PLFA concentrations after freeze-thawing and with longer durations. However, the number of freeze-thaw events had no effect on the microbiological variables. The findings suggest that the higher frequency of freeze-thaw events predicted to follow the global warming will likely have a limited impact on soil microorganisms.