杀灭菊酯对亚热带果园红壤脲酶活性的生态毒理效应

通过模拟方法,系统研究杀灭菊酯对亚热带果园红壤脲酶活性的影响。结果表明:杀灭菊酯对土壤脲酶活性表现出先激活后抑制趋势,处理前3 d土壤脲酶活性升高,处理3 d后土壤脲酶活性受到抑制,7 d后低于对照水平;激活、抑制程度与处理浓度呈正相关。底物(尿素)浓度饱和前,土壤脲酶活性随尿素浓度增加而升高。模型U=β0 β1×C能较好拟合土壤脲酶活性(U)和尿素浓度(C)、杀灭菊酯浓度(C)之间关系,揭示出土壤酶促反应过程存在吸附-解吸的机制,证实不同肥力土壤脲酶活性受杀灭菊酯影响差异较大,高肥力土壤对土壤脲酶活性具有一定的缓冲作用,受杀灭菊酯影响较小。     

苯醚甲环唑对温室土壤微生物及土壤酶活性的影响

为了解温室环境下杀菌剂苯醚甲环唑对土壤微生物生态环境的影响,在温室大棚中研究了0.5,2.5,5.0mg/kg 3个浓度苯醚甲环唑对土壤微生物数量和土壤酶的毒性效应。结果表明,温室环境中苯醚甲环唑对土壤细菌和放线菌数量影响较小,仅2.5,5.0mg/kg苯醚甲环唑对土壤细菌和放线菌数量有短暂的抑制或刺激作用,苯醚甲环唑对土壤真菌数量表现为显著的抑制作用,且持续较长,呈现出毒害效应;苯醚甲环唑对温室土壤中性磷酸酶活性表现出低浓度刺激、高浓度抑制的作用,对土壤脲酶活性表现出强烈的抑制作用,对蔗糖酶活性表现出刺激作用,对土壤纤维素酶活性表现出刺激-抑制-恢复对照水平的效应。随着时间的延长,4种土壤酶活性逐渐恢复,到第28d时都趋于对照组水平。该研究结果可为棚室环境下苯醚甲环唑对土壤微生物的安全性评价及科学使用提供科学依据。     

阿维菌素对蔬菜地土壤微生物及土壤酶的生态毒理效应

研究了阿维菌素对蔬菜地土壤微生物和土壤酶的生态毒理效应.实验结果表明,阿维菌素在低浓度时（1～10 mg kg^-1）对土壤脲酶活性和脱氢酶活性有轻微的激活作用,而对土壤微生物呼吸强度没有明显的影响;在高浓度时（50～100 mg kg^-1）对土壤微生物呼吸强度、脲酶活性以及脱氢酶活性均有明显抑制作用;不同浓度阿维菌素在不同程度上均会造成土壤微生物生物量的减少和过氧化氢酶活性被强烈激活.     

新农药哌虫啶在三种典型土壤中的吸附与淋溶研究

采用实验室模拟方法研究了烟碱类新农药哌虫啶在土壤生态系统中的降解动态及其对土壤微生物的影响.结果表明,哌虫啶的降解过程符合一级反应动力学方程,浓度为1、5和10 mg kg-1的哌虫啶在土壤中的降解半衰期为11.28 ~7.30 d.哌虫啶对土壤微生物的毒性作用与浓度正相关.施药后哌虫啶对土壤中细菌和放线菌的数量具有激活作用,3 d后,哌虫啶开始抑制土壤中细菌和放线菌的数量,施药后5 d内,哌虫啶促进了真菌的生长繁殖,10 d后表现为抑制真菌数量,有先促进后抑制细菌、真菌和放线菌的趋势.哌虫啶施入土壤后对土壤酶活性具有一定的影响,土壤碱性磷酸酶较酸性磷酸酶更敏感,哌虫啶具有抑制酸性磷酸酶和碱性磷酸酶的作用,这种抑制作用一直延续至试验的第20天;施药处理组对脲酶活性均有显著的抑制作用,并且浓度越大,抑制作用越强烈;哌虫啶对土壤脱氢酶具有显著的激活作用,哌虫啶对土壤过氧化氢酶影响作用较弱.总之哌虫啶在土壤中降解半衰期较短,属于易降解农药,10 mg kg-1浓度的哌虫啶对土壤微生物具有一定的毒性作用.     

磷化铝对土壤微生物数量和酶活性的影响

为明确磷化铝对土壤微生物数量和酶活性的影响,采用室内培养的方法,研究了经0.1、1mg.g-1和10mg.g-13个浓度磷化铝熏蒸处理后,供试土壤中微生物数量和土壤酶活性的变化。结果表明,磷化铝处理土壤后,各个浓度的磷化铝对土壤细菌、真菌和放线菌数量具有抑制作用,浓度越高,抑制作用越强,但一段时间后低浓度（0.1mg.g-1）处理对土壤微生物数量的影响恢复至对照水平。磷化铝对土壤脲酶表现为抑制作用,并随浓度升高而增强;低浓度处理对土壤中的蔗糖酶活性抑制作用不明显,而高浓度（10mg.g-1）处理表现为强烈的抑制作用;各浓度处理初期对土壤过氧化氢酶表现为抑制或激活作用,但到第30d,恢复至对照水平。这说明,施入常规剂量的磷化铝对土壤微生物数量和土壤酶活性会产生一定的影响,在经过一定时间后均可恢复至对照水平。     

土霉素及镉污染对土壤呼吸及酶活性的影响

随着饲料工业以及畜禽养殖业的规模化发展,抗生素和重金属在土壤环境中同时存在的几率不断增大。为了分析抗生素和重金属对土壤微生物生态系统的影响,以土霉素(OTC)与镉(Cd)为污染物,采用室内培养法,研究了土霉素(OTC)与镉(Cd)单一处理及复合污染对土壤呼吸和酶活性的影响。结果表明,10mg/kg重金属镉单独污染对土壤微生物呼吸表现为先抑制后激活作用,且显著抑制了土壤蔗糖酶、脲酶、磷酸酶活性,对3种酶活性平均抑制率从大到小依次为:蔗糖酶磷酸酶脲酶;1mg/kg土霉素显著激活土壤微生物呼吸,50和200mg/kg土霉素对土壤微生物呼吸的影响呈现出先抑制后激活的规律。各处理浓度下的土霉素对蔗糖酶和脲酶活性均主要表现为抑制作用,对磷酸酶活性的影响呈现出一定的波动性;当土霉素的浓度为1和200mg/kg时,其与10mg/kg镉的复合污染对土壤微生物呼吸及3种酶活性的影响主要为拮抗作用,但当土霉素的浓度为50mg/kg时,与10mg/kg镉的复合污染对土壤微生物呼吸及3种酶活性的影响则主要为协同作用。微生物呼吸对土霉素与镉胁迫更为敏感,最高抑制率和激活率分别可达98.98%和300.82%,土壤酶活性受土霉素和镉污染的影响要弱于它们对土壤微生物呼吸的影响。     

氯嘧磺隆对土壤微生物数量,酶活性及呼吸强度的影响

氯嘧磺隆是一类高效广谱除草剂,研究其对土壤微生物的影响对其合理使用具有重要意义。通过室内瓶培养实验研究了不同浓度氯嘧磺隆对土壤呼吸强度、土壤微生物数量和土壤酶活性的影响。结果表明:氯嘧磺隆施入土壤2周后,可明显提高土壤呼吸强度,且浓度越大,提高效果越明显;氯嘧磺隆施入土壤1周后,不同浓度氯嘧磺隆处理均可提高土壤细菌和放线菌数量,45 d时表现出抑制作用,60 d可恢复到对照水平;氯嘧磺隆对土壤真菌数量表现为抑制作用,而后恢复到对照水平,45 d时田间施用量可抑制土壤真菌的增殖,但60 d可恢复到对照水平。土壤培养前1周,氯嘧磺对土壤过氧化氢酶、土壤转化酶、土壤脲酶活性均表现出不同程度的抑制作用,且浓度越大抑制作用越明显。之后三种酶表现出一定的激活作用,培养60 d可恢复到对照水平。以上试验结果可为合理施用氯嘧磺隆提供理论依据。     

4种典型抗生素对土壤微生物呼吸的影响

本研究通过室内直接吸收法测定了四环素、金霉素、诺氟沙星和恩诺沙星4种典型抗生素对土壤微生物呼吸作用的影响。结果表明,4种抗生素对土壤微生物呼吸的影响存在一定差异。四环素在整个处理过程中对土壤呼吸的影响以抑制作用为主;金霉素在处理第1d和7d均有激活作用,而且激活率最高可达到51.23%,但是在其他处理时间以抑制作用为主;诺氟沙星在整个处理过程中,浓度为0.2mg·kg-1和1mg·kg-1对土壤微生物呼吸都有一定的抑制作用,浓度为5、25、50mg·kg-1处理均为激活作用,激活作用随着处理浓度的增加而升高。恩诺沙星在整个处理过程中,所有处理对呼吸的影响变化趋势为先激活后抑制。总体来说,到处理第15d,所有抗生素处理的微生物呼吸作用基本恢复到对照水平,说明在本试验浓度处理下,微生物对这4种抗生素能够产生一定的适应性。     

两种除草剂对稻田土壤微生物数量和酶活性的影响

[目的]探究常用除草剂及其浓度对稻田土壤微生物数量及酶活性的影响,为评价除草剂对水田土壤生态效应提供参考依据。[方法]通过开展大田试验,设置了华星草克和丁草胺两种除草剂及其高、中、低3种浓度进行试验。[结果](1)中、低浓度丁草胺和华星草克对土壤微生物数量影响较小,即使在短期内会产生细微的抑制作用,但恢复较快;(2)高浓度处理对土壤微生物数量影响较为明显,但随除草剂施入时间的延长,抑制作用在21d基本恢复至对照水平;(3)两种除草剂处理对土壤脲酶、蔗糖酶均产生了一定的抑制作用,这种抑制作用随浓度升高而增强,但随着药效的降解,抑制作用逐渐消失,酶活性恢复至对照水平;(4)两种除草剂对土壤过氧化氢酶的影响与其他两种酶不同,具有一定的刺激作用。[结论]两种除草剂对稻田土壤微生物数量和酶活性的影响因不同的施药浓度以及施药后作用时间的推移而异,不高于中等浓度处理对其影响较小,且短期内易恢复至正常水平。因此,适量的除草剂对水田土壤生态系统是相对安全的。     

68%代森锰锌对土壤微生物种群及呼吸作用的影响

通过实验室培养试验研究了0、0.5、2.5、5.0 mg kg-1的68%代森锰锌对土壤微生物种群动态变化和土壤呼吸强度的影响。结果表明,低浓度(0.5 mg kg-1)的代森猛锌可促进土壤细菌、真菌和放线菌的增殖,土壤呼吸作用增强;高浓度的代森锰锌则抑制细菌、真菌和放线菌的增殖,土壤呼吸作用也受到一定程度的抑制,浓度愈高,抑制作用愈强;但随着培养时间的推移,土壤中农药的量不断减少,各浓度处理的土壤微生物量及呼吸作用都趋于与对照组相一致。而且根据危害系数法的分级方法计算,代森锰锌属于无实际毒害的农药。     

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。     

Tebuconazole application decreases soil microbial biomass and activity

A short-term mesocosm experiment was conducted to ascertain the impact of tebuconazole on soil microbial communities. Tebuconazole was applied to soil samples with no previous pesticide history at three rates: 5, 50 and 500 mg kg⁻¹ DW soil. Soil sampling was carried out after 0, 7, 30, 60 and 90 days of incubation to determine tebuconazole concentration and microbial properties with potential as bioindicators of soil health [i.e., basal respiration, substrate-induced respiration, microbial biomass C, enzyme activities (urease, arylsulfatase, β-glucosidase, alkaline phosphatase, dehydrogenase), nitrification rate, and functional community profiling]. Tebuconazole degradation was accurately described by a bi-exponential model (degradation half-lives varied from 9 to 263 days depending on the concentration tested). Basal respiration, substrate-induced respiration, microbial biomass C and enzyme activities were inhibited by tebuconazole. Nitrification rate was also inhibited but only during the first 30 days. Different functional community profiles were observed depending on the tebuconazole concentration used. It was concluded that tebuconazole application decreases soil microbial biomass and activity.     

Changes in soil biological activities under reduced soil pH during Thlaspi caerulescens phytoextraction

Phytoextraction of soil Cd and Zn may require reduction in soil pH in order to achieve high metal uptake. Reducing the pH of high metal soil, however, could negatively affect soil ecosystem function and health. The objectives of this study were to characterize the quantitative causal relationship between pH and soil biological activities in two Zn and Cd contaminated soils and to investigate the relationship between metals and soil biological activities under low pH. Soils were adjusted to five or six different pH levels by sulfur addition, followed by salt leaching. Thlaspi caerulescens was grown for 6 months, and both the rhizosphere and non-rhizosphere soil biological activities were tested after harvest. Reducing pH significantly lowered soil alkaline phosphatase activity, arylsulphatase activity, nitrification potential, and respiration. However, acid phosphatase activity was increased with decreasing pH. The relationship between soil biological activities and pH was well characterized by linear or quadratic regression models with R² values ranging from 0.57 to 0.99. In general, the three enzyme activities, nitrification potential, and the ratio of alkaline phosphatase to acid phosphatase activity were very sensitive indicators of soil pH status while soil respiration was not sensitive to pH change. The rhizosphere soil had higher biological activities than non-rhizosphere soil. The negative effects observed in the non-rhizosphere soil were alleviated by the rhizosphere influence. However, rhizosphere soil after 6 months phytoextraction showed lower nitrification potential than non-rhizosphere soil, probably due to substrate limitation in our study.     

The effects of copper on microbial activity and the degradation of atrazine and indoxacarb in a New Zealand soil

Copper is present in a range of fungicides as well as in some animal manures and biosolids that are applied to agricultural soils as fertilisers. Elevated and increasing levels of copper in agricultural soils are of worldwide concern. Copper is toxic to soil microorganisms and has been reported to reduce the ability of soil microorganisms to degrade pesticides. A glasshouse study was undertaken to determine if copper inhibited the degradation of atrazine and indoxacarb in soil. A fine sandy loam agricultural soil was fortified with copper at five concentrations over a concentration range of 0–1000 mg/kg copper, then field-aged for 6 months prior to treatment with either indoxacarb or atrazine at a rate of 2 mg/kg. The soils were sampled twice at intervals based on published half-lives. The samples were analysed for a range of parameters including total and bioavailable copper, urease and phosphatase activity, ergosterol and either indoxacarb or atrazine and its degradation products. The soil microbial biomass and enzyme activities decreased with increasing copper concentration (p < 0.05). There were no significant differences in soil atrazine and indoxacarb concentrations between the copper levels. At sampling time two, the concentrations of hydroxyatrazine in treatments containing the three highest copper concentrations were significantly greater (p < 0.05) than for the control soil. Our results indicate that copper does not inhibit the first step of indoxacarb and atrazine degradation, but may affect degradation of secondary metabolites like hydroxyatrazine in soil.     

Microbial Populations and Enzyme Activities in Soil Treated with Pesticides

The effect of soil treatment with brominal (a herbicide) and theinsecticide selecron (the equivalent field rates and five-fold) on population counts of bacteria, actinomycetes and celluloyticfungi in soil was tested throughout 10 weeks incubation at28 °C. Also, tested their effect on four soil enzymes:cellulase, acid phosphatase, alkaline phosphatase andarylsulphatase. Bacterial and actinomycetes populations in soiltreated with the two pesticides were promoted at fieldapplication rates and inhibited at higher levels. The twopesticides significantly decreased the total number ofcellulolytic fungi and most fungal species after most incubationperiods either by one or the two used levels but the effect ofselecron was more pronounced.Cellulase activity in soil treated with brominal and selecronwas inhibited after most incubation periods. The effect of soiltreatment with the two pesticides on acid phosphatase waspromotive at field application rates after some incubationperiods but the enzyme activity was delayed at the higherapplication doses. Alkaline phosphatase activity in treated soilwas accelerated with both pesticides even at the higherapplication rates, suggesting a direct role of alkaline soil pHin increasing resistance of alkaline phosphatase to pesticides.The effect of soil treatment with pesticides on arylsulphataseactivity fluctuated between promotion and inhibition, butinhibition was predominant.     

Physical treatment and reinoculation of soil: Effects on microorganisms and enzyme activities

Three soils, sandy loam, clay loam, and muck were subjected to different physical treatments, reinoculated with fresh soil and the effect of these treatments on the numbers of microorganisms and soil enzyme activities was studied. Soils were subjected to air-drying, freeze-drying, freezing, dry ice-freezing, autoclaving and oven drying. The results indicated that the microbial populations increased with some of the physical treatments after 2 or 7 days incubation, while, some of the treatments decreased the populations. Air-drying the clay loam inhibited urease and phosphatase activities. None of the treatments inhibited dehydrogenase activity in either the clay loam or the muck. However, a stimulatory effect after 4 days was evident in the muck with heat treatments. Heat treatments inhibited phosphatase activity in all soils and urease activity throughout the experiment in loams, whereas after 14 days, there was a rapid recovery of urease activity in the muck soil. Autoclaving resulted in a pronounced increase in C₂H₂ reduction in the three types of soils. Heating appears to have an effect in an organic soil where the formation of 2,3,5-triphenyltetrazolium formazan (formazan) and C₂H₄ were significantly increased.     

Response of ATP content, respiration rate and enzyme activities in an arable and a forest soil to nutrient additions

Glucose (C), glucose plus NO₃^- (C+N) or glucose plus NO₃^- plus PO₄^3- (C+N+P) were added to an arable and a forest soil at a single dose, or split into four equal doses over 4 consecutive days, and the response of several enzyme activities, ATP content and respiration rate were monitored for 11 days. ß-Glucosidase activity was reduced in the two soils during the first day by substrate addition. Thereafter, this enzyme activity varied only slightly in the arable soil with reference to the non-amended control, while it increased substantially in the beech forest when C+N and C+N+P were added. Casein-hydrolysing activity increased in the C treatment and decreased after C+N+P addition during the first 4 days in the two soils. After 11 days, protease activity was enhanced in the arable soil when C+N was applied in a split dose. Urease activity decreased during the first 4 h, particularly in the arable soil with the addition of C+N or C+N+P, applied in a single dose, and then continuously increased. Thus, urease responded to high nutrient availability, being firstly repressed or inhibited, and stimulated afterwards. Phosphatase activity was only slightly modified in the arable soil but substantially increased in the beech forest by C+N addition. The presence of P usually decreased phosphatase activity. Arylsulphatase activity was repressed after substrate addition, which was particularly evident in the arable soil. In the beech forest topsoil, C added alone increased this enzyme activity. Significant correlations between ATP content and enzyme activity were only observed for urease in the arable system treated with C+N and in the forest when C was applied in a split dose. The effect of C, C+N and C+N+P addition varied between the arable and the forest soil according to environmental conditions and microbial ecophysiology.     

Changes in nutrient content,enzymatic activities and microbial properties of lateritic soil due to application of different vermicomposts: a comparative study of ergosterol and chitin to determine fungal biomass in soil

In this experiment, vermicomposts, prepared from five different waste materials, were applied to acid lateritic soil under field conditions and soil samples were collected after 90 days to study the effect of vermicomposts on different chemical and biochemical. Results suggest that vermicompost prepared from paddy straw is most effective to improve nutrient content, enzymatic activities and microbial properties of lateritic soil. Vermicompost application significantly (P ≤ 0.05) increased the concentration of organic C, mineralizable N, available P and exchangeable K in soil. Amylase, protease, urease and acid phosphatase activities were also significantly (P ≤ 0.05) higher in vermicompost treated soils compared with the control. Both basal and substrate‐induced microbial respiration, microbial biomass C and N and fungal population in lateritic soil were increased due to vermicompost application. Ergosterol and chitin content were significantly (P ≤ 0.05) higher in vermicompost treated soils over the control. Application of vermicompost increased the proportion of fungal biomass in total soil microorganisms.     

The phytotoxicity and degradation of diesel hydrocarbons in soil

Hydrocarbon contamination in soils may be toxic to plants and soil microorganisms and act as a source of groundwater contamination. The objective of the study was to evaluate the fate of adding diesel in soil with no previous history of hydrocarbon contamination. Particular aspects examined were soil respiration, changes in microbial population, breakdown of diesel hydrocarbon and phytotoxicity to germination of ryegrass. Soil respiration was measured as evolved CO₂. Bacterial population was determined as Colony Forming Units (CFUs) in dilution plates, and fungal activity was measured as hyphal length. The fate of individual hydrocarbons was determined by GC‐MS after extraction with dichloromethane. When 0.64 % (w/w) of diesel was added to soil, the respiration response showed a lag phase of 2 days and maximum respiration occurred at day 7. The lag phase was 5 days and maximum respiration occurred at day 11 in soil after adding 1.6 %, 4.0 %, and 13.6 % of diesel (w/w). After the peak, respiration decreased up to 20 days, in each of the four levels of diesel addition to the soil. Thereafter, respiration becomes more or less constant but substantially greater than the control. Diesel addition up to 4.0 % (w/w) increased the bacterial population to 10 fold but fungal hyphal length did not increase. However, bacterial population did not increase after adding 13.6 % (w/w) of diesel and fungal hyphal length was significantly less than the control and other three levels of diesel. Removal of inhibition to germination of perennial ryegrass was linked to the decomposition of n‐C₁₀ and n‐C₁₁ hydrocarbons and took from 11 to 30 days depending on the levels of diesel added to the soil. Contamination with 13.6 % (w/w) of diesel inhibited the germination of perennial ryegrass until 24 weeks of incubation.     

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。