Effects of different catalysts on steam gasification ofbiomass char at low temperature

生物质气化技术是将低品位的生物质能转换成高品位能源的有效途径。该文以稻壳和麦秸半焦为试验对象,进行了低温下生物质半焦的水蒸气气化试验,研究了浸渍法制备的碱金属催化剂和气化温度对生物质半焦气化行为的影响。结果显示,对于稻壳半焦气化而言,相同负载量的K基催化剂的催化效果明显优于Na基催化剂,相比非催化时稻壳半焦的碳转化率分别提高了18.2%和13.5%,差异明显。增加K2CO3负载量有利于半焦气化反应的进行,但负载量不宜超过30%。不同的煅烧温度,催化剂的活性组分存在形式有较大差别,负载量为30%的K基催化剂在800℃煅烧后具有最佳的催化效果。相同条件下,麦秸半焦的气体产率和碳转化率均较高,在700℃下添加该催化剂时分别达到130.0 mol/kg和95.9%,相比非催化时分别提高了57.0%和34.1%。随着温度的降低,气体产率和碳转化率均明显下降,该文催化条件下的半焦气化温度不宜低于700℃。研究结果可为生物质低温气化高效催化剂的选择提供理论依据。     

生物质焦油模型化合物的催化转化（简报）

生物质热解焦油对气化装置及气体运输装置都有极大危害,该文以脂肪烃类化合物正庚烷与环己烷作为焦油的模型化合物,在微型固定床反应器上采用商用Z417镍基催化剂研究了温度、S/C（水蒸气与焦油模型化合物中碳的摩尔比）和试验停留时间对正庚烷与环己烷催化转化率的影响。结果表明,在600～800℃范围内正庚烷与环己烷的转化率随温度的升高而提高,750℃时正庚烷转化率可达到95%,环己烷转化率达到88.7%左右。水蒸气量对于正庚烷和环己烷的转化率有一定的影响,并且可以促进气体产物成分调整与缓解催化剂表面积碳;延长停留时间增加了反应物与催化剂的接触时间,因此正庚烷和环己烷的转化率随停留时间增加而升高。试验结果表明,在水蒸气参与反应条件下,Z417镍基催化剂对生物质焦油模型化合物正庚烷与环己烷的催化效果良好。     

生物质炭负载镍钙催化剂催化裂解/重整生物质热解气研究

为有效去除生物质热解焦油、提高气体产物品质,该研究提出了采用生物质炭（Biochar,BC）负载镍钙催化剂催化裂解/重整生物质热解气定向转化合成气（H2+CO）的研究思路,通过对焦油转化率、合成气产率以及催化剂稳定性的研究,揭示催化剂对生物质热解气催化裂解/重整的影响规律。结果表明,钙的添加降低了镍的晶粒尺寸,有利于碳纳米管的生成。与单一金属催化剂相比,生物质炭负载镍钙催化剂具有较高的焦油裂解/重整活性,在温度为700 ℃条件下、镍和钙负载量分别为0.02 mol和0.01 mol时,焦油转化率以及合成气产率分别为91.8%及607.6 mL/g（H2/CO=1.05）,显示了优异的低温焦油裂解/重整活性,并在480 min内仍可保持较高的催化活性,反应后,催化剂积碳量仅为3.6 mmol/g,同时无明显团聚现象发生,展现出良好的抗积碳和抗烧结性能。     

基于热解-重整-燃烧解耦三床气化系统的生物质催化制富氢气体

生物质催化气化是将生物质转换成富氢气体的有效途径。该研究提出了一种由热解反应器、重整反应器和提升管燃烧器三部分构成的解耦三床生物质气化(decoupled triple bed gasification,DTBG)工艺。在实验室规模的DTBG气化反应装置上,以水蒸气为气化剂,以橄榄石为原位焦油裂解催化床料,进行了生物质水蒸气催化气化试验,考察了生物质种类、重整器温度、生物质进料速率对气化效果的影响规律,并且对气化副产物焦油的特性进行了分析。试验结果表明,生物质原料的挥发分对气化产物分布的影响很大,原料挥发分含量越高,气体产率越高,碳转化率越高,气体中的H2和CO体积分数越大、CO2体积分数越低。当重整器温度由750升高到850℃时,气体产率从0.91增加到1.08 m3/kg,焦油质量浓度从19.1降低到7.3 g/m3,同时气体品质大幅度提升。随着生物质进料速率的增加,产气中H2体积分数大幅度增加,CO2体积分数大幅度降低,但是焦油质量浓度基本不变。当重整器温度为800℃,白松木屑进料速率为220 g/h时,H2和CO体积分数分别达到了42.2%和14.6%,产气中焦油质量浓度为10.1 g/m3。气化焦油的主要成分为多环芳烃,其中萘含量最高。当重整器温度从700℃升高到850℃时,焦油中单环化合物几乎全部分解,3~4环多环芳烃化合物逐步降低,萘的相对含量从54.7%升高到75.6%。该研究结果可为大规模气化装置的设计、运行以及优化提供理论指导。     

膨润土褐铁矿改性白云石催化松木棒气化工艺优化

针对白云石催化剂在生物质催化气化过程中易碎、易产生积碳失活问题,为提高其催化活性、抗积碳和再生性能,采用固定床下吸式气化炉试验系统,以Fe-Dol-Ben(膨润土/褐铁矿改性白云石)为催化剂,松木屑废料经成型为棒状颗粒为原料,进行高温水蒸气催化气化试验。研究气化温度(700～1000℃)、铁含量(质量分数为5%～20%)以及催化剂使用次数(1～4)等因素对松木棒催化气化性能及催化剂表面积碳影响。试验结果表明,水蒸气和松木棒的质量比(气料比)为1,催化剂的铁质量分数为15%,气化温度为900℃时气化气中氢气的体积分数达到最大值58.38%,Fe-Dol-Ben催化剂积碳量随气化温度升高逐渐减小,试验区间内1 000℃时达到最小值,较700℃减少了80%。气化气中氢气的体积分数随铁含量增加呈先增加后降低的趋势,积碳量呈先降低后增加,在铁质量分数为15%催化效果较好。Fe-Dol-Ben催化剂较相同条件下分别用膨润土及改性前白云石催化时积碳量分别减少了80.6%和53.6%。对催化剂进行再生再利用试验表明,使用后的Fe-Dol-Ben催化剂进行700℃煅烧再生后,其晶相与催化前基本相同,将其多次再生循环利用,随着使用次数的增加气化气中氢气的体积分数逐渐降低,催化剂的积碳量逐渐增大,使用4次并用于催化气化时氢气的体积分数仍接近50%,保持较好催化效果。综合气化效果、积碳量及经济性因素,Fe-Dol-Ben铁质量分数为15%,气化温度选取900℃为较理想工况。该研究可为改性白云石Fe-Dol-Ben催化剂的研制及生物质高温水蒸汽催化气化技术提供参考。     

膨润土/褐铁矿改性白云石催化剂改善松木蒸汽富氢气化性能

采用蒸汽气化,以松木燃料棒为试验对象,分析气化气及焦油组分变化,研究改性白云石(膨润土为载体,白云石为活性组分,并负载少量褐铁矿)催化性能随温度升高的变化规律。试验表明:750℃时,在改性白云石催化条件下,H_2的体积分数为45.77%±0.23%,相较无催化和白云石催化条件下的富氢作用,气化所需温度下降100℃;富氢程度在较低温度下明显,但随温度升高而消弱;改性白云石不仅促使烃端链上碳碳长链断链,产生氢自由基,进而形成H_2,同时促进芳香环开环反应,脱羧基及脱羟基反应,使得裂解后的焦油更易转化为小分子气体;催化剂中活性中心Fe~(3+)随温度高逐渐减少,使得改性白云石的质量增加在900℃降低至最小值,但相比白云石,改性白云石催化剂在气化前后的色泽和形态变化较轻,反映其表面积碳及机械强度得到优化。项目研究可为生物质蒸汽催化气化及廉价高效改性白云石的应用提供参考。     

生物质焦制备条件对甲苯裂解特性的影响

为了探索生物质焦比表面积和金属氧化物含量等物理化学特性对其催化活性的影响,该文通过生物质制焦条件（制焦温度、活化方式、原料种类等）的改变制备了不同的生物质焦样品,并在微波反应器上,对以生物质焦为催化剂的甲苯催化裂解特性进行了研究,结果表明制焦条件对甲苯转化率有重要影响。制焦温度的提高有助于生物质焦比表面积及孔容积的增加,可以提高生物质焦对甲苯的裂解转化率,制备温度为850℃的生物质焦对甲苯的裂解转化率可达99.9%。生物质焦在CO2或水蒸气气氛中的活化可以使生物质焦比表面积大幅度增加,对甲苯的裂解转化率得到提高。灰分对生物质焦的催化特性有重要影响,稻壳焦脱灰前后的对比研究表明,K2O、CaO含量越高,生物质焦的催化活性越强。     

成灰温度对三种生物质灰及其元素水溶性的影响

生物质灰及灰中化学元素的水溶特性是其是否能作为肥料应用的主要指标,成灰温度会影响这些特性。该文试验研究了成灰温度在400~800℃范围内,3种主要农业废弃物麦秸、玉米秸、稻壳的灰的水溶性和灰中各元素的水溶性。结果表明:1)麦秸灰、玉米秸灰的水溶性明显高于稻壳灰,三者水溶性都随成灰温度增高而显著降低,温度从400升高到800℃,水溶性分别从48%,35%和12%降至约12%,8%和0。2)灰中水溶元素主要有K,Cl和S,其中,K和Cl的水溶性随着成灰温度升高而降低,而S的水溶性几乎不受成灰温度的影响。     

微波辐照下活性炭载铁催化剂催化热解竹材特性研究

基于活性炭作为催化剂载体及其良好微波吸收性能的优势,该文提出了微波条件下活性炭载铁催化剂催化热解竹材的研究思路,通过对物料升温特性、热解产物特性的研究,揭示催化剂对竹材微波热解的影响规律,为生物质资源化利用提供科学参考。结果表明,活性炭载铁催化剂对竹材微波热解过程有一定影响。催化剂具有良好的微波吸收性能,能够提高竹材升温速率和最高热解温度,当活性组分负载量为7.49%时,最高热解温度高达699.8℃,与纯竹材相比增加了54.38%。活性炭及催化剂的添加提高了气体产率而降低生物油的产率,而且随着活性组分负载量的增加,液体产率逐渐降低,气体产率逐渐增加,热解得到的气体产率最大为69.11%。催化剂对环类化合物开环裂解生成直链类化合物以及合成气(H2+CO)的生成有一定催化作用,活性组分负载量的增加使得这种催化作用得到加强,当活性组分负载量为7.49%时,气体产物中合成气的产率及体积分数分别为17.5 mmol/g和77.24%。     

热解温度对生物质炭碳保留量及稳定性的影响

以核桃壳为生物质炭生产原料,研究热解温度(200~700℃)对生物质炭产率、元素组成、表面官能团分布及其稳定性的影响,以期探明生物质炭基本性质随热解温度变化的规律,为全面了解生物质炭固碳减排效果提供理论参考。结果表明,生物质炭的C含量随温度升高而增加,H和O元素含量却随温度升高而降低。此外,生物质炭的H/C和O/C随着温度增加而减少。生物质炭的产率及碳保留量随着温度的升高而降低。红外光谱分析结果表明,经过热解核桃壳原材料分子中所含的-C-O和O-CH3基团消失,随着热解温度升高,生物质炭中的烷烃基团-CH逐渐减少,芳香化程度逐渐升高。500℃制备生物质炭的K2Cr2O7和KMn O4氧化碳损失量均最低,分别为10.4%和1.66%。相关分析表明,生物质炭的产率、碳保留量及稳定性与热解温度之间均具有显著相关关系。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.