城市污泥和化肥对水稻土种植的通菜中邻苯二甲酸酯（PAEs）的影响

对水稻土施用城市污泥和化肥盆栽通菜,应用GC／MS联机检测技术对通菜中6种邻苯二甲酸酯化合物(PAEs)进行分析,探讨施肥对通菜中PAEs含量的影响,结果表明,各处理通菜中6种PAEs化合物的总含量(∑PAEs)在2．129～7.111mg·kg^-1之间,依次为广州污泥+化肥(7．111mg·kg^-1)>广州污泥(4．767mg·kg^-1)>佛山污泥(3;569mg·kg^-1)>佛山污泥+化肥(3．305mg·kg^-1)>化肥(2．638mg·kg^-1)>空白对照(2．129mg·kg^-1)。显示了施肥造成通菜中∑PAEs不同程度的提高,各处理通菜中的PAEs均以个别化合物为主,其中空白对照、化肥、佛山污泥和广州污泥处理的通菜中邻苯二甲酸丁基苄基酯(BBP)占∑PAEs的40％～81％。佛山污泥+化肥处理的通菜中邻苯二甲酸正二丁酯(DnBP)占∑PAEs的56％,而广州污泥+化肥处理的通菜中邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸正二辛酯(DnOP)和邻苯二甲酸(2-乙基己基)酯(DEHP)各占∑PAEs的30％左右,通菜中∑PAEs和多数化合物的含量不同程度地大于其在根系中的含量。     

山东省花生主产区土壤和花生籽粒中邻苯二甲酸酯的分布特征

在山东省四大花生主产区采集耕层土壤(0～20 cm)和花生籽粒,应用气相色谱测定样品中美国国家环保署(EPA)优先控制的6种邻苯二甲酸酯(PAEs)化合物的含量.结果表明: 山东省花生主产区土壤中6种PAEs化合物累计(∑PAEs)含量范围为0.34～2.81 mg·kg^-1,平均含量为1.22 mg·kg^-1;四大花生主产区土壤∑PAEs含量为：鲁中南山区＞鲁西平原＞胶东半岛＞鲁北平原;与美国土壤PAEs控制标准相比,山东省四大花生主产区土壤中的邻苯二甲酸正二丁酯(DBP)超标严重.花生籽粒中∑PAEs含量范围为0.17～0.66 mg·kg^-1,平均含量为0.34 mg·kg^-1,低于美国和欧洲的建议指标,健康风险很小.邻苯二甲酸二(2-乙基己基)酯(DEHP)和DBP在土壤和花生籽粒中占∑PAEs的百分比、检出率均较高,是主要的污染物组分.覆膜种植模式下土壤和花生籽粒中的∑PAEs显著高于露地种植模式.花生籽粒和土壤中的∑PAEs、DBP及DEHP存在显著正相关性,Pearson相关系数分别为0.786、0.747和0.511.     

外源碘在森林土壤中的残留及对山野菜植物的施用效果

以培育富碘山野菜为目标,在东北森林暗棕壤上进行了5种山野菜施碘试验。碘肥种类为碘化钾(KI),施碘剂量为1．00、3．33、10．00、16．67和50．00mg·kg^-1。结果表明,土壤施碘是培育富碘山野菜的有效途径,从低施用量到高施用量,不同山野菜植物的含碘量可达对照的2～40倍,但外源碘在土壤中的当年残留率并不高,仅有40％～5％残留,并且随着施入量增加而迅速降低;植物对碘的积累也并非总是随着施入量的增加而增加,施碘量达到10．00mg·kg^-1时,大部分植物的碘积累量趋于稳定。从施碘条件下外源碘的土壤残留率、植物碘积累特征及施用成本等方面综合考虑,适宜的施碘量上限大约为10mg·kg^-1．土壤因素显著影响施碘效果,栽培地应选择土质细腻、肥沃的中上坡地段,砂砾质土壤和易形成水分潜流的下坡土壤都不利于肥料碘的保持和植物吸收。     

表面活性剂对分枝杆菌KR2菌株降解菲的影响

采用同位素示踪方法,从表面活性剂的浓度、离子类型和直链长度三方面研究了表面活性剂对分枝杆菌KR2菌株降解菲的影响。结果表明,表面活性剂的存在不能促进KR2菌对菲的降解;高浓度表面活性剂(≥20mg·L^-1)的存在,使菲的降解出现延迟期,非离子表面活性剂Tween80在低浓度时(≤10mg·L^-1)可以优先作为营养基质被分枝杆菌KR2菌株利用,表面活性剂的离子类型对菲降解的抑制作用的顺序为阳离子表面活性剂TDTMA>阴离子表面活性剂LAS>非离子表面活性剂Tween80,表面活性剂的直链长度对菲降解的影响为直链越短,对微生物的毒性越大,菲降解得越不完全。     

氮磷钾肥对有柄石韦生理及绿原酸合成积累的影响

为探讨氮磷钾3种养分对有柄石韦生理及有效成分绿原酸合成积累的影响,该研究以有柄石韦组培苗为材料,分别用低养分(不施肥:N₀,P₀,K₀)、正常施肥(N:0.20 g·kg^-1,P:0.15 g·kg^-1,K:0.15 g·kg^-1)和高养分(N₁:0.40 g·kg^-1,P₁:0.30 g·kg^-1,K₁:0.30 g·kg^-1)3个浓度梯度,设置7个处理分别为NPK、N₀PK、N₁PK、NP₀K、NP₁K、NPK₀、NPK₁,测定不同处理下有柄石韦的抗性生理指标、绿原酸(CGA)含量及其合成关键酶活性。结果表明:(1)氮磷钾肥对有柄石韦的抗性生理有显著的影响,超氧化物歧化酶(SOD)在高氮和低钾处理中活性显著增加,而3种养分的低浓度和高浓度处理均会导致过氧化氢酶(CAT)活性显著上升。(2)不同养分水平氮、磷和钾对有柄石韦CGA含量存在显著影响,正常施肥的CGA含量最高,达到12.92 mg·g^-1; 高钾施肥的CGA含量最低,为7.79 mg·g^-1; 钾肥对CGA含量影响最显著。(3)CGA合成关键酶活性在不同施肥处理中差异显著,CGA含量与奎宁酸羟基肉桂酰转移酶(HQT)和4-香豆酰辅酶A连接酶(4CL)活性呈显著正相关,与莽草酸羟基肉酰转移酶(HCT)活性显著负相关,HQT、4CL和HCT是导致CGA含量差异的关键因素。该研究结果为有柄石韦药材的人工栽培提供了理论依据。     

甘肃中东部地区9种薹草属植物分布区群落特征和土壤养分状况

为探究薹草属(Carex L.)植物在不同植被类型中的分布状况,该研究对甘肃中东部地区9种薹草属(Carex L.)植物分布区的群落特征进行调查,并对土壤养分状况进行比较分析,以揭示野生薹草群落物种多样性和分布特征与土壤环境因子间的关系。结果表明：(1) 9种薹草群落物种多样性差异性较大,Shannon-Wiener多样性指数(H)、Simpson优势度指数(D_si)均以青绿薹草群落最高,亚柄薹草最低;Patrick丰富度指数(R)以异穗薹草群落最高,细叶薹草群落最低;Pielou均匀度指数(J_sw)以凹脉薹草群落最高,亚柄薹草最低。(2) 9种野生薹草属植物适宜生长的土壤pH呈中性或弱碱性,且有机质、氮素、钾素含量较丰富,磷含量偏低;土壤有机质、pH、全氮、全磷、全钾、碱解氮、速效磷、速效钾含量的平均值分别为41.07 g·kg^-1、8.35、1.16 g·kg^-1、0.65 g·kg^-1、5.60 g·kg^-1、47.94 mg·kg^-1、5.82 mg·kg^-1和100.60 mg·kg^-1。(3) 9种薹草属植物群落物种多样性与全氮、全磷、全钾、碱解氮、有机质、降雨量和海拔呈正相关关系,而与土壤pH、速效磷、速效钾呈负相关关系,且降雨量、土壤pH、速效磷和有机质对9种野生薹草属植物群落物种多样性影响较大。     

内蒙古不同类型草地土壤氮矿化及其温度敏感性

土壤氮矿化(Nitrogen mineralization)是土壤氮循环的重要环节,对土壤氮素供应以及植物生产力的维持具有十分重要的意义。沿中国东北草地样带(Northeastern China Transect, NECT)分别在典型草地、过渡草地及荒漠草地设置了3个实验样地,利用不同温度(5、10、15、20 ℃和25 ℃)和不同水分(30%、60%和90%土壤饱和含水量,Saturated soil moisture, SSM)的室内培养途径,探讨了不同类型草地的土壤氮矿化速率、土壤氮矿化的温度敏感性(Q₁₀)及其主要影响因素。实验结果表明:从典型草地至荒漠草地,土壤全碳、全氮、全磷、微生物生物量碳氮含量均表现为逐渐下降的趋势;类似地,土壤净氮矿化速率、硝化速率也逐渐降低。在20 ℃和60% SSM时,土壤净氮矿化速率表现为典型草地 (0.715 mg N kg^-1 d^-1) > 过渡草地 (0.507 mg N kg^-1 d^-1) > 荒漠草地 (0.134 mg N kg^-1 d^-1);相反,温度敏感性却逐渐升高,温度敏感性与基质质量指数呈负相关。草地类型和水分对于土壤净氮矿化速率、硝化速率具有显著影响,且二者间具有显著的交互效应。包含温度和水分的双因素模型可很好地拟合土壤氮矿化速率的变化趋势(P < 0.0001),二者可共同解释土壤硝化速率92%-96%的变异。土壤氮矿化沿着草地演替呈现出很好的空间格局、并与温度和水分具有密切关系,为解释内蒙古草地空间分布格局提供了理论基础。     

施氮肥和钙肥对烤烟根系形态、生理代谢及产量的影响

为了解氮肥和钙肥对烤烟(Nicotiana tabacum)生长的影响,对成熟期烤烟的根系形态、生理代谢指标和产量进行了研究。结果表明,与施0.12 g kg^-1氮相比,施0.20 g kg^-1氮的烤烟根系最长侧根长、根系体积、根干重、叶干重和可溶性蛋白质含量均极显著升高,MDA含量极显著下降,SOD活性显著下降,但对侧根数、CAT活性和O₂^·的影响均不显著。施钙0.40 g kg^-1,根系体积、侧根数、CAT和SOD活性以及可溶性蛋白质含量均比对照提高,MDA含量和O₂^·则降低;施钙1.00 g kg^-1,最长侧根长、根干重和叶干重均提高。氮×钙互作对烤烟的最长侧根长、根系体积、根干重、叶干重和生理代谢指标的影响均极显著,但对侧根数的影响不显著。因此,施0.20 g kg^-1氮和0.40 g kg^-1钙能最大限度地改善烤烟根系形态、生理状况及提高产量。     

苯并（a）芘对大弹涂鱼肝细胞超微结构的影响

在实验生态条件下,研究不同浓度苯并(a)芘(BaP)暴露下大弹涂鱼肝脏细胞超微结构的变化。结果表明,暴露于低浓度(0．5mg·L^-1)BaP 7d,大弹涂鱼肝脏细胞内的细胞器受到不同程度的损伤,其中线粒体和内质网是受BaP暴露影响最明显的细胞器,细胞核也受到不同程度的影响,细胞质中脂滴也增加;而暴露于高浓度(5mg·L^-1)BaP 2h,不仅是线粒体和内质网,几乎所有细胞器都受到严重影响,细胞器严重退化,细胞结构遭到严重破坏。研究结果证实,BaP可对大弹涂鱼肝细胞内多种细胞器造成损伤,并且BaP浓度越高,损伤程度越严重。     

山东寿光设施菜地土壤砷含量及形态

通过典型区域采样调查,系统探讨了山东寿光市设施菜地中砷的含量及其形态特征.结果表明: 设施菜地表层(0～20 cm)和亚表层(20～40 cm)土壤中总砷含量分别为8.27、7.93 mg·kg^-1,是对照土壤的1.19和1.23倍,易溶性砷(AE-As)含量分别为0.13、0.06 mg·kg^-1,是对照土壤的1.63和3.00倍; 土壤中的砷主要以残渣态砷(O-As)存在,其含量占总砷的63.0%以上,其他形态砷含量依次为铁型砷(Fe-As)>钙型砷(Ca-As)>铝型砷(Al-As)>AE-As; 随着种植年限的延长,土壤中AE-As含量显著增加,Al-As含量也有不同程度提高,种植15 a设施菜地表层和亚表层土壤中的AE-As含量分别比对照提高了75.0%和150.0%,Al-As含量分别提高了51.6%和190.4%,而Fe-As和Ca-As含量则均有不同程度的下降.     

广东省典型区域农业土壤中邻苯二甲酸酯含量的分布特征

采用气相色谱方法,对广东省典型区域农业表层土壤(0～20cm)样品中的6种邻苯二甲酸酯(PAEs)进行了测定.结果表明:6种PAEs化合物的总含量(∑PAEs)为nd(未检出)～25.99mg.kg-1,其中92.8%的样品分布在≤1mg.kg-1的范围;各种土地利用类型中∑PAEs的顺序依次为水田>香蕉地>菜地>甘蔗地>果园地;不同地区土壤中∑PAEs的顺序依次为东莞市>汕头市>佛山市顺德区>湛江市>中山市>珠海市>惠州市.邻苯二甲酸二(2-乙基已基)酯(DEHP)的检出率最高(85.1%),邻苯二甲酸二正丁酯(DnBP)含量最高(nd～17.51mg.kg-1).与美国土壤PAEs控制标准相比,除邻苯二甲酸二正辛酯(DnOP)外,其余5种PAEs化合物均有不同程度的超标,其中DnBP、邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二乙酯(DEP)3种化合物超标率较高.广东省典型区域农业土壤受到不同程度的PAEs污染.     

Phthalic Acid Esters in Soils from Vegetable Greenhouses in Shandong Peninsula,East China

Soils at depths of 0 cm to 10 cm, 10 cm to 20 cm, and 20 cm to 40 cm from 37 vegetable greenhouses in Shandong Peninsula, East China, were collected, and 16 phthalic acid esters (PAEs) were detected using gas chromatography-mass spectrometry (GC-MS). All 16 PAEs could be detected in soils from vegetable greenhouses. The total of 16 PAEs (Σ₁₆PAEs) ranged from 1.939 mg/kg to 35.442 mg/kg, with an average of 6.748 mg/kg. Among four areas, including Qingdao, Weihai, Weifang, and Yantai, the average and maximum concentrations of Σ₁₆PAEs in soils at depths of 0 cm to 10 cm appeared in Weifang, which has a long history of vegetable production and is famous for extensive greenhouse cultivation. Despite the different concentrations of Σ₁₆PAEs, the PAE compositions were comparable. Among the 16 PAEs, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), di-n-butyl phthalate (DnBP), and diisobutyl phthalate (DiBP) were the most abundant. Compared with the results on agricultural soils in China, soils that are being used or were used for vegetable greenhouses had higher PAE concentrations. Among PAEs, dimethyl phthalate (DMP), diethyl phthalate (DEP) and DnBP exceeded soil allowable concentrations (in US) in more than 90% of the samples, and DnOP in more than 20%. Shandong Peninsula has the highest PAE contents, which suggests that this area is severely contaminated by PAEs.     

地膜使用年限对遵义市烟田土壤和烟叶邻苯二甲酸酯累积的影响

研究地膜使用年限对土壤和烟叶邻苯二甲酸酯(PAEs)积累的影响,以明确地膜持续使用条件下PAEs的土壤污染分布特征及在烟叶中的富集状况.在遵义市连阡村和沙湾村采集了不同覆膜年限的烟田土壤及相应的烟叶,采用气相色谱仪质谱联用技术(GC-MS),对土壤-烟叶中6种优先控制PAEs含量进行了测定.结果表明: 所有土壤和烟叶样品中6种邻苯二甲酸酯化合物累计(∑PAEs)分别为(2.66±0.60)和(3.58±0.64) mg·kg^-1,其中,邻苯二甲酸二(2-乙基己)酯(DEHP)含量最高,邻苯二甲酸正二丁酯(DBP)次之,二者之和分别占土壤和烟叶∑PAEs的92.7%和88.9%.DEHP、DBP、邻苯二甲酸二乙酯(DEP)和邻苯二甲酸丁基苄基酯(BBP)检出率均为100.0%,邻苯二甲酸二甲酯(DMP)的检出率略低,邻苯二甲酸正二辛酯(DnOP)检出率最低.随着地膜使用年限的增加,土壤和烟叶中PAEs含量显著增加,且在地膜使用的前1~ 8年增加更为明显,后期趋于平缓.土壤和烟叶中的PAEs含量与覆膜年限呈显著正相关关系,覆膜年限的增加会显著促进土壤和烟叶中PAEs的积累.烟叶与土壤之间∑PAEs的累积量相关性不显著.     

城市污泥中邻苯二甲酸酯(PAEs)的厌氧微生物降解

邻苯二甲酸酯(PAEs)是城市污泥中普遍存在的一类具有内分泌干扰性作用的有机污染物.研究污泥厌氧生物处理过程中PAEs的微生物降解对保障污泥农用的安全性十分必要.本文以污泥中两种主要的PAEs——邻苯二甲酸二丁酯(DBP)和邻苯二甲酸(2-乙基己)酯(DEHP)为研究对象,通过比较PAEs在污泥厌氧消化系统与发酵产氢系统中降解过程的差异及系统污泥特性的变化,分析不同污泥厌氧生物处理系统中影响PAEs降解的可能因素.结果表明: 在污泥厌氧发酵系统中,DBP在6 d内降解率达99.6%, DEHP在整个14 d的培养期间也降解了46.1%;在发酵产氢系统中,在14 d培养过程DBP的降解率仅为19.5%,DEHP则没有明显的降解.与厌氧消化系统相比,PAEs在发酵产氢系统中的降解受到明显抑制,这与发酵产氢过程中微生物量下降、革兰氏阳性菌/革兰氏阴性菌(G⁺/G^-)和真菌/细菌变小及挥发性脂肪酸(包括乙酸、丙酸及丁酸)浓度升高有关.     

Long-term survival of pathogenic and sanitation indicator bacteria in experimental biowaste composts

For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded Listeria monocytogenes, Salmonella enterica subsp. enterica serotype Enteritidis, and Escherichia coli. Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetables, and green waste, were composted in laboratory reactors with forced aeration. The physicochemical and microbiological parameters were monitored for 12 weeks during composting. The survival of bacteria over a 3-month period at 25 degrees C was assessed with samples collected after different experimental composting times. Strain survival was also monitored in mature sterilized composts. Nonsterile composts did not support pathogen growth, but survival of seeded pathogens was observed. Salmonella serovar Enteritidis survived in all composts, and longer survival (3 months) was observed in mature composts (8 and 12 weeks of composting). Mature biowaste composts may support long-term survival of Salmonella serovar Enteritidis during storage at room temperature. E. coli and L. monocytogenes survival was observed only in 4-week-old composts and never in older composts. Proper composting may prevent long-term survival of E. coli and L. monocytogenes. These results suggest that like composted sewage sludge or manure, domestic waste composts may support pathogen survival. Survival was not related to the physicochemical characteristics of the composts.     

Estimation of phosphorus bioavailability from composted organic wastes

Sewage sludge derived from municipal sewage treatment plants is an important source of macronutrients, micronutrients and organic matter. For this reason composting of sewage sludge, along with combustion and co-combustion, is a new management priority in Poland. In this study six composts of different origin and composition were evaluated in terms of their abundance in phosphorus, because it is an essential nutrient for all living organisms. Analyses were conducted on the samples at the initial and at the maturation phase of composting. The bioavailability of phosphorus was estimated on the basis of amounts of the nutrient in isolated fractions using the sequential extraction method. First of all quantitative changes of the total nutrient content and its amounts in separated fractions were dependent on the mixture composition. Irrespective of compost type, 34.5–75.0% of the total amounts of phosphorus were found in hardly available combinations (Fr. III), while available phosphorus forms (Fr. I) accounted for only 6.6–21.6%. As a result of composting together different organic wastes an increase was observed both in the total content and the amounts of this nutrient in separated fractions. This phenomenon was observed particularly in composts with smaller levels of sewage sludge (30–40%), characterised by rapid organic matter decomposition, which was indicated by higher bioavailable amounts of phosphorus. Under such conditions the content of P ranged between 3.68 and 7.4 g kg^?1. In comparison to the labile pool of P obtained for matured composts C5 and C6 (65 and 75% of sewage sludge in their composition) amounting to 2.45–3.0 g kg^?1 the above values were considerable. Bioavailable phosphorus contents potentially introduced to soil with composts doses calculated at 170 kg total N/ha/yr ranged from 69.8 to 80.2 kg for compost with the lowest share of sewage sludge and from 11.2 to 20.7 kg for compost with the highest share of sewage sludge.     

Isolation of Thermus strains from hot composts (60 to 80 degrees C).

High numbers (10(7) to 10(10) cells per g [dry weight]) of heterotrophic, gram-negative, rod-shaped, non-sporeforming, aerobic, thermophilic bacteria related to the genus Thermus were isolated from thermogenic composts at temperatures between 65 and 82 degrees C. These bacteria were present in different types of wastes (garden and kitchen wastes and sewage sludge) and in all the industrial composting systems studied (open-air windows, boxes with automated turning and aeration, and closed bioreactors with aeration). Isolates grew fast on a rich complex medium at temperatures between 40 and 80 degrees C, with optimum growth between 65 and 75 degrees C. Nutritional characteristics, total protein profiles, DNA-DNA hybridization (except strain JT4), and restriction fragment length polymorphism profiles of the DNAs coding for the 16S rRNAs (16S rDNAs) showed that Thermus strains isolated from hot composts were closely related to Thermus thermophilus HB8. These newly isolated T. thermophilus strains have probably adapted to the conditions in the hot-compost ecosystem. Heterotrophic, ovalspore-forming, thermophilic bacilli were also isolated from hot composts, but none of the isolates was able to grow at temperatures above 70 degrees C. This is the first report of hot composts as habitats for a high number of thermophilic bacteria related to the genus Thermus. Our study suggests that Thermus strains play an important role in organic-matter degradation during the thermogenic phase (65 to 80 degrees C) of the composting process.     

Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions

Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microoganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade PAEs compared with those developing in a biogas reactor.Abbreviations BBP butylbenzyl phthalate - DEHP bis(2-ethylhexyl) phthalate - CoA coenzyme A - DBP dibutyl phthalate - DEP diethyl phthalate - DS dry solids - MBeP monobenzyl phthalate - MBuP monobutyl phthalate - MEP monoethyl phthalate - MSW municipal solid waste - PA phthalic acid - PAE(s) phthalic acid ester(s) - VFA volatile fatty acids     

Compost convective airflow under passive aeration

For composting, passive aeration can save energy costs while being just as efficient as forced or active aeration. Passive aeration requires the proper design of aeration ducts, and thus, the proper prediction of the convective airflow rates created by the temperature differential between the compost and the ambient air. To establish such relationship, the temperature and convective air flow regimes of composts were investigated using three bulking agents (wood shavings, hay and straw), each at three moisture contents (MC-60%, 65% and 70%) spanning the normal values. All bulking agent and aeration treatments were aerated in duplicate under passive and active regimes. Laboratory vessels of 105 L were used for all treatments. Passive aeration treatments produced temperatures above 57 degrees C, as did the treatments actively aerated at 4 mg of air s(-1) kg(-1) of initial dry compost material. Compost MC had an effect only on the peak compost temperature, occurring between day 2 and 6. After 6 days of composting, MC no longer had any effect on temperature regime because of the loss of moisture by each mixture. A relationship was established between the Grasholf number (Gr-ratio of buoyancy to viscous forces) and the convective airflow rates, to size the aeration ducts for passive aeration. In general, convective airflow rates ranged from 1.5 to 0.7 mg of dry air s(-1) kg(-1) of initial compost dry matter, from day 0 to day 20, respectively, and for all compost treatments. This airflow rate sizes the aeration ducts installed under compost piles for passive aeration. As compared to straw where airflow rate dropped over a given level of Gr, wood shavings and hay were found to be more effective as bulking agents, as their airflow rate increased constantly with Gr.