竹炭固定化微生物对土壤中阿特拉津的降解研究

采用环境友好材料竹炭为主要载体,壳聚糖和海藻酸钠为辅助载体,固定从污泥中分离出的阿特拉津降解菌株,研究不同固定材料对降解菌生长的影响,以及固定化微生物对土壤中阿特拉津的降解效果.结果表明,竹炭对阿特拉津降解菌具有较强的吸附固定能力,且竹炭粒径越小,固定化效果越好.利用壳聚糖和海藻酸钠交联并加固阿特拉津降解菌,增大了固定化空间,显著增加了降解菌的生物量,并提高了阿特拉津的降解效率.1％壳聚糖+5％海藻酸钠+竹炭+降解菌颗粒对阿特拉津降解菌的固定化效果最佳,施用该微生物固定化颗粒28天后,砂姜黑土及红壤中阿特拉津残留率分别为48.07％和47.23％.     

Arthrobacter sp. AG1菌株降解土壤中阿特拉津研究

在阿特拉津浓度为50mg/kg干土的黄棕壤、潮土和红壤接种1.5×106CFU/g干土的降解菌Arthrobacter sp. AG1,10天后土壤中的阿特拉津分别降解至1.5、6.6和10mg/kg干土。阿特拉津的降解速率受到土壤性质的影响,但AG1仍能在不满足其生长繁殖要求的pH值的土壤中有效降解酸性土壤中阿特拉津;土壤中水分含量对降解效果影响较大,>20%时降解效果较好;土壤低含水量和低pH值会导致AG1降解阿特拉津的活力下降。不同的接种量对降解效果有一定影响,但105～107CFU/g干土接种量的AG1都能有效发挥降解作用。AG1降解完土壤中的阿特拉津后,在土壤含水量分别为5%和15%的情况下能长期保持降解活性,对60天后第2次施入黄棕壤和潮土中的50mg/kg阿特拉津4天时降解效率在65%以上。     

阿特拉津在土表的光解行为动力学研究

研究了阿特拉津在土壤表面的光解行为的动力学,并研究了各种因素对光解的影响。实验表明,土壤粒度、湿度、pH值、有机质、腐殖酸和表面活性剂都影响阿特拉津在土壤中的降解。在太阳光辐射下,阿特拉津在土壤表面降解速率常数为0. 08~0. 17d-1,光解深度为0. 3mm以内,半衰期为4~8d。     

节杆菌AD26的分离鉴定及其与假单胞菌ADP对阿特拉津的联合降解

用富集培养法,从农药厂的工业废水中分离到高效降解除草剂阿特拉津的AD26菌株,通过16SrRNA基因序列分析,该菌株被鉴定为节杆菌（Arthrobacter sp.）。降解基因的PCR分析表明,AD26含有阿特拉津降解基因trzN和atzBC,它能以阿特拉津为唯一氮源、蔗糖或柠檬酸钠为碳源生长,将阿特拉津降解成氰尿酸,降解速度快但降解不完全。假单胞菌（Pseudomonas sp.）ADP是Wackett实验室分离的阿特拉津降解菌株,含有阿特拉津降解基因atzABCDEF,能以阿特拉津为唯一氮源、柠檬酸钠为碳源（不能以蔗糖为碳源）生长,将阿特拉津降解成NH3和CO2,降解完全但降解速度慢。在阿特拉津浓度为200mg·L^-1的无机盐培养基中进行的AD26和ADP混合培养表明,它们对阿特拉津的降解发生了互补和增强作用,两个菌株能在以阿特拉津为唯一氮源、蔗糖为碳源的培养基中生长,而且生长和降解速率都好于单个菌株,培养72h后阿特拉津去除率达到99.9%,其中76.7%的阿特拉津被降解成NH3和CO2。这表明由节杆菌AD26和假单胞菌ADP组成的混合菌株在阿特拉津废水处理和污染土壤的生物修复中有很好的应用潜力。     

阿特拉津在土表的紫外光降解行为研究

本文研究了阿特拉津在土壤表面的紫外光光解的动力学,并研究了各种因素对光解的影响。实验表明,土壤粒度、湿度、pH值、有机质、腐殖酸和表面活性剂都影响阿特拉津在土壤中的降解。在紫外光辐射下,阿特拉津在土壤表面降解速率常数为(0.09~0.17)/min,光解深度为0.1~0.3mm,半衰期为4~8min。     

阿特拉津降解菌LY-2的分离鉴定及其对污染土壤的修复

除草剂阿特拉津(2-氯-4-乙胺基-6-异丙胺基-1,3,5-三嗪,2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine,Atrazine)在很多国家普遍使用,对自然环境和人类健康造成威胁。本研究利用富集法,从黑龙江省哈尔滨市巴彦县施用多年阿特拉津的玉米地表层土中,分离出高效降解阿特拉津的菌株LY-2。LY-2以阿特拉津为唯一氮源,初步鉴定属于肠杆菌属(Enterobacter sp.)。PCR检测结果表明,LY-2含有阿特拉津降解相关的基因—阿特拉津氯水解酶基因(atrazine chlorohydrolase gene,atzA)、羟基阿特拉津脱乙胺基水解酶基因(hydroxyatrazine N-ethylaminohydrolase gene,atzB)和N-异丙基氰尿酰氨异丙氨基水解酶基因(N-isopropylammelide isopropylaminohydrolase gene,atzC)。LY-2在48 h内对100 mg/L阿特拉津降解率为98.7%;适宜温度为25~35℃,适宜酸碱度为p H 6~9;外加氮源没有降低该菌株对阿特拉津的降解率。土壤修复实验结果显示,培养7 d后,LY-2菌株对阿特拉津污染土壤(100 mg/kg)的降解率高达86.7%,培养14 d后,降解率高达90.1%。LY-2菌株在相对较短的时间内表现出良好的修复效果,在修复阿特拉津污染的土壤方面具有潜在的应用价值。     

污染土壤中原位阿特拉津降解菌的分离和鉴定

为克服传统富集培养分离降解菌的局限性,直接将长期受阿特拉津污染的土壤稀释后,涂布于加有土壤浸出液和阿特拉津农药的平板,分别从两个采自不同地区的污染土壤中各分离了一株高效广谱降解菌AG1和ADG1：它们能以阿特拉津为唯一碳源、氮源和能源生长,能分别在44h和48 h内降解1 000mg L^-1的阿特拉津,降解率100%;它们还能以扑草净、西玛津等三嗪类除草剂为唯一氮源生长.16S rDNA核苷酸序列分析结果表明菌株AG1与ADG1都与节杆菌属（Arthrobacter）的细菌有高度同源性,结合两株菌的形态特征及生理生化特征,将它们鉴定为Arthrobacter spp..PCR扩增两株菌的降解基因,结果表明它们的降解基因都是trzN和atzBC的组合,这是国内首次报道具有该基因类型的阿特拉津降解菌.     

阿特拉津降解菌ADH-2的分离、鉴定及其特性研究

从长期施用阿特拉津的玉米地中采集土样,通过富集培养的方法分离出一株能以阿特拉津为唯一碳、氮源生长的细菌ADH-2,结合生理生化特陛及16SrRNA基因的相似性分析将其初步鉴定为节杆菌属（Arthrobacter sp．）。该菌在10h内对100mg·L-1阿特拉津的降解率为99．9％。外加氮源能促进菌株的生长,但对阿特拉津的降解有轻微的抑制作用。外加蔗糖和葡萄糖能显著促进菌株的生长,但对阿特拉津的降解表现出显著的抑制。而淀粉既能促进菌株的生长又能促进阿特拉津的降解。对其降解基因的初步研究显示,该菌含有trzN、atzB和atzC3个阿特拉津降解相关基因。通过与本实验室另外两株阿特拉津降解菌比较,菌株ADH-2具有更好的应用潜力。     

纳米粘土矿物对阿特拉津的吸附-解吸特性研究

采用批量平衡实验,研究了纳米粘土矿物与原粘土矿物对除草剂阿特拉津的吸附解吸特陛。结果表明,粘土矿物对阿特拉津的吸附-解吸均能用Freundlich方程很好地拟合。随着溶液中阿特拉津浓度的增加,粘土矿物对阿特拉津的吸附量增加;粘土矿物粒径越小,吸附量越大,纳米粘土矿物的吸附量显著大于原粘土矿物。粘土矿物对阿特拉津吸附量大小顺序为：纳米SiO2）纳米蒙脱石〉凹凸棒石〉蒙脱石〉SiO2。粘土矿物对阿特拉津的解吸表现出一定的滞后效应,即粘土矿物吸附的阿特拉津越多,解吸的越少。粘土矿物对阿特拉津的解吸率大小顺序为：SiO2〉凹凸棒石〉纳米蒙脱石〉纳米SiO2〉蒙脱石。     

污染土壤中菲高效降解菌的筛选及其降解特性

运用恒温培养法研究了菲在不同土壤中的降解动态,结果表明未灭菌土壤中菲半衰期仅5.1d,而灭菌土壤中半衰期为前者4倍,可见土壤微生物发挥了重要作用;从试验土壤中分离到一株菲高效降解菌,经16SrDNA鉴定为产碱杆菌;优势菌最高可以耐受500mgL-1左右的菲,降解菲的最适温度25℃和pH为7,土壤接种优势菌后有助于加快菲的降解;从该优势菌中提取的粗酶液米氏常数为50.30nmolml-1,最大降解速率为171.33nmolmg-1min-1。     

Microbial activity and metabolic quotient of microbes in soils amended with biochar and contaminated with atrazine and paraquat

The study was conducted to determine how biochar as a soil amendment maintained the microbial community in pesticide contaminated soils. Alfisol (Adenta series – Typic Kandiustalf) and Vertisol (Akuse series – Typic Calciustert) were amended with biochar (0 t/ha biochar, 10 t/ha cocoa husk biochar (CHB), 10 t/ha rice husk biochar (RHB)) and pesticides (atrazine and paraquat at two rates each namely 0 kg/ha pesticide and 10 times the normal recommended rate of pesticide) were applied. The CHB-amended soils stimulated microbial activities such as ammonia and nitrate release more than the RHB-amended soils. Basal respiration was significantly higher in the atrazine polluted soils than in paraquat polluted soil. Significant interaction occurred between soil type and biochar and high microbial biomass carbon was recorded for vertisol amended with CHB. Metabolic quotient was lower in soils amended with biochar and polluted with atrazine than in the un-amended soil. The use of CHB in soil of high clay content (47.5%, i.e. the vertisol) was a more effective management tool in maintaining the microbial community in a pesticide-polluted environment than in soil of lower clay content (22.5%). Soils of high clay content amended with biochar can sustain the soil microbial community even in a disturbed environment.     

The kinetics of extraction of soil-applied metoxuron by methanol and its biological implications

The effect of three levels of moisture (saturation, field capacity, 50% field capacity) and two temperatures (10 and 27 °C) on the extraction of sil applied metoxuron by methanol was determined for an alfisol and a vertisol. Technical grade metoxuron applied at 20 μg g^?1 of soil, was extracted by shaking with methanol for 30 min and assayed spectrophotometrically after correcting for soil blanks. There was an initial steep fall in the extractable portion for about 40 to 60 days followed by a much slower decrease in all the cases upto 150 days. The time of 50% extractability of the added herbicide (t₅₀) was lower at 27 °C than at 10 °C, the difference being more marked for the alfisol. The effect of moisture which varied from 40 to 10% for vertisol and 30 to 7.5% for alfisol was not significant. The specific rate of decrease of extractable metoxuron was similar at both temperaturs for the vertisol, and was significantly lower for the alfisol at 10 °C. The observed pattern of the kinetics of methanol available metoxuron is interpeted in terms of an initial rapid partitioning of the herbicide into labile and nonlabile compartments followed by a probable slow release and degradation path. The specific reaction rates for the different steps have been estimated and correlated with other soil properties and their implication on the bioavailability of the herbicide by considering methanol extractability as a suitable index is discussed.     

福建省变性土特性的研究

在福建沿海低丘、台地玄武岩风化物上发育一种暗色粘质土壤,历史上归属于砖红壤性红壤。本研究证明,它明显区别于砖红壤性红壤,主要表现于：风化--淋溶作用和脱硅富铝化作用较弱,通体暗色,层次分异不明显,粘粒含量高,粘土矿物以蒙脱石占优势,有明显膨胀收缩性,干季出现一定深度的开裂,阳离子交换量大,盐基饱和度和pH值较高。据此,这种土壤有必要从砖红壤性红壤中划分出来。按美国土壤系统分类,本土壤定名为细质、蒙脱石型、高热、典型艳色湿润变性土。可以认为,变性土在我国也应作为一个独立的分类单元。     

微生物降解阿特拉津的研究进展

除草剂阿特拉津长期使用所造成环境污染问题的日益加重,受污染土壤、水体的生物降解、生态修复等诸多问题也受到人们的广泛关注,本文综述了降解阿特拉津的微生物类群、阿特拉津降解酶以及微生物对阿特拉津的作用方式和降解途径,并对其应用前景进行了展望。     

Solvent extraction characterization of bioavailability of atrazine residues in soils

Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. The objective of this study was to correlate atrazine residue bioavailability in aged soils, as determined by solvent extraction methods, to atrazine mineralization by an atrazine-degrading bacterium. Webster clay loam and Zimmerman fine sand soils were treated with UL-ring-labeled [14C]atrazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either not extracted, extracted with 0.01 M CaCl2, or extracted with 0.01 M CaCl2/aqueous methanol. Soils were then inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing the atrazine ring. This allowed for the evaluation of the bioavailability of aged atrazine residues without the contribution of atrazine desorption from soil. Results of these studies indicated that the amounts of atrazine residues in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were correlated to amounts of atrazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol extractable atrazine in aged soils may be used to estimate bioavailable residues, and this technique may be useful to determine the bioavailability of other compounds in soils, especially other triazine herbicides.     

Iron oxide and clay minerals and their relation to colours of red and yellow podzolic soils near Sydney,Australia

The iron oxide and clay minerals in some typical red and yellow podzolic soils from New South Wales have been investigated by X-ray diffraction and infra-red spectroscopy. The dominant iron oxide mineral is goethite containing about 13–14 mol % AlOOH, this being the mineral which gives the yellow soils their characteristic colour. The red soils also contain finely divided hematite which masks the colour of the goethite. Lepidocrocite was not detected in any of the soils examined. The dominant clay minerals are kaolinite and dioctahedral interstratified illite-smectite, the latter being more concentrated in the finer clay fractions, especially in soils developed on calcareous greywacke. In the red podzolic soil developed on Ashfield shale, illite-smectite is strongly interlayered with well-ordered aluminous material. Dickite occurs in this soil.     

Influences of kaolinite and montmorillonite on benzo[a]pyrene biodegradation by Paracoccus aminovorans HPD-2 and the underlying interface interaction mechanisms

Clay minerals play an important role in biogeochemical cycling. Here, kaolinite and montmorillonite, the two most abundant and widespread clay minerals with typical layered structures, were selected to investigate and compare their effects on the biodegradation of benzo[a]pyrene (BaP) by Paracoccus aminovorans HPD-2 and to investigate the underlying interface mechanisms. Overall, the BaP degradation efficiency was significantly higher 7 d after montmorillonite addition, reaching 68.9% (P < 0.05), when compared with that of the control without addition of clay minerals (CK, 61.4%); however, the addition of kaolinite significantly reduced the BaP degradation efficiency to 45.8%. This suggests that kaolinite inhibits BaP degradation by inhibiting the growth of strain HPD-2, or its strong hydrophobicity and readily agglomerates in the degradation system, resulting in a decrease in the bio-accessibility of BaP to strain HPD-2. Montmorillonite may buffer some unfavorable factors, and cells may be fixed on the surface of montmorillonite colloidal particles across energy barriers. Furthermore, the adsorption of BaP on montmorillonite may be weakened after swelling, reducing the effect on the bio-accessibility of BaP, thus promoting the biodegradation of BaP by strain HPD-2. The experimental results indicate that differential bacterial growth, BaP bio-accessibility, interface interaction, and the buffering effect may explain the differential effects of the different minerals on polycyclic aromatic hydrocarbon biodegradation. These observations improve our understanding of the mechanisms by which clay minerals, organic pollutants, and degrading bacteria interact during the biodegradation process and provide a theoretical basis for increasing the biodegradation of soil pollutants by native microorganisms under field conditions.     

不同施肥处理下旱地红壤中阿特拉津的环境归趋及其调控研究

红壤是广泛分布于我国南方地区的重要土壤类型,其低pH、低有机质含量的特征不利于微生物群落功能,可能影响有机污染物的降解。阿特拉津是常见的选择性内传导性除草剂,但目前对红壤中阿特拉津的转化规律及调控原理缺乏认识。本研究采集长期施用化肥或有机肥(猪粪)的旱地红壤,设置添加木质素和牡蛎壳粉等不同组合处理的微宇宙试验,采用同位素示踪、定量PCR、高通量测序等方法,研究施肥及土壤改良措施对红壤中阿特拉津矿化特征及降解微生物的调控作用。结果表明,在14周培养期间,旱地红壤对阿特拉津的矿化率低于0.33%。牡蛎壳粉有效提高红壤pH值、改变土壤细菌群落,大幅增加了阿特拉津的矿化,并导致atzC和trzN等降解功能基因的富集。木质素则显著增加了阿特拉津与土壤有机质的结合,但对污染物的矿化没有明显作用。本研究结果有助于阐明旱地红壤中阿特拉津的环境归趋,并为发展适用于红壤的污染物控制技术提供科学依据。