硫酰氟气体浓度衰减与仓房气密性相关性研究

为了解不同气密性仓房硫酰氟熏蒸过程中的浓度衰减规律,选取5个不同气密性储粮仓房,通过熏蒸过程中的硫酰氟浓度监测,分析和比较气体浓度衰减半衰期和仓房气密性的相关性.结果显示,当仓房气密性为143 s时,最长浓度半衰期为8.5 d;当仓房气密性为53、46 s时,最高浓度半衰期分别为2.7、4.6 d.无法检测出气密性的仓...     

硫酰氟气体在不同品种粮堆扩散规律比较研究

为了解硫酰氟在小麦、稻谷和大豆3种粮堆中的扩散和分布规律,通过6个实仓熏蒸的数据采集,对熏蒸气体在不同粮堆内的扩散速度、均匀性、以及衰减速度等参数进行比较分析.试验结果表明,硫酰氟气体在不同粮种中的扩散速度是大豆>稻谷>小麦;大豆粮堆最快在熏蒸后8 h后,可实现整仓气体均匀;平均气体浓度半衰期分别是大豆>小麦>稻谷;在...     

硫酰氟熏蒸在砖圆仓应用效果评价研究

为探索砖圆仓硫酰氟熏蒸杀虫和防护效果,分别在3个不同气密性仓房,分别采用整仓不环流熏蒸和环流熏蒸,以及采用不同的熏蒸药剂浓度,通过分析比较气体均匀性,浓度保持时间和杀虫防护效果进行评价.试验结果表明,硫酰氟气体可在4 h内自然扩散穿透10 m粮堆,并在24 h内达到整仓气体均匀.环流熏蒸由于环流管道老化造成药剂损失,气...     

硫酰氟气体在不同品种粮堆扩散规律比较研究（网络首发、推荐阅读）

为了解硫酰氟在小麦、稻谷和大豆3种粮堆中的扩散和分布规律,通过6个实仓熏蒸的数据采集,对熏蒸气体在不同粮堆内的扩散速度、均匀性、以及衰减速度等参数进行比较分析。试验结果表明,硫酰氟气体在不同粮种中的扩散速度是大豆>稻谷>小麦;大豆粮堆最快在熏蒸后8 h后,可实现整仓气体均匀;平均气体浓度半衰期分别是大豆>小麦>稻谷;在5.0~12.7 g/m3的熏蒸药剂浓度下实现6个月无虫期的防护效果。     

硫酰氟熏蒸在砖圆仓应用效果评价研究（网络首发、推荐阅读）

为探索砖圆仓硫酰氟熏蒸杀虫和防护效果,分别在3个不同气密性仓房,分别采用整仓不环流熏蒸和环流熏蒸,以及采用不同的熏蒸药剂浓度,通过分析比较气体均匀性,浓度保持时间和杀虫防护效果进行评价。试验结果表明,硫酰氟气体可在4 h内自然扩散穿透10 m粮堆,并在24 h内达到整仓气体均匀。环流熏蒸由于环流管道老化造成药剂损失,气体浓度保持时间短。5 g/m3的药剂浓度即可实现较好的快速杀灭4种主要储粮害虫的效果。     

小麦粉堆垛硫酰氟熏蒸及杀虫效果的实仓试验

研究了五面密闭方式密封的小麦粉堆垛以20 g/m3硫酰氟熏蒸工艺,分析了硫酰氟的熏蒸杀虫效果和渗透性。结果表明,硫酰氟熏蒸52 h完全可以杀死常见储粮害虫。试验中,以五面密闭方式薄膜密封的小麦粉堆垛气密性较差,硫酰氟浓度半数衰减时间HLT仅为1.6 h,此种密封方式不适合进行硫酰氟熏蒸。硫酰氟可以渗透到1.5 m深度的小麦粉中,熏蒸52 h可以杀灭小麦粉堆内0.6 m深度的害虫。此外,赤拟谷盗、锈赤扁谷盗、米象、锯谷盗对硫酰氟存在不同的耐受力。     

硫酰氟对臭氧衰减的影响及其尾气处理技术研究（网络首发、推荐阅读）

硫酰氟是一种潜在的磷化铝替代熏蒸剂,在其大规模使用前,其环境风险的评价及排放处理研究具有重要意义。研究硫酰氟对臭氧的破坏作用和硫酰氟尾气处理方法。向350 mg/m3臭氧实验箱中分别通入5、10、20 g/m3的硫酰氟,检测不同浓度硫酰氟条件下,臭氧衰减曲线。实验结果表明：当实验箱温度设定为25 ℃,无硫酰氟环境臭氧浓度半衰期为275.2 min,5、10、20 g/m3三个硫酰氟浓度环境臭氧半衰期分别为157.4、166.4、161.8 min。经统计分析,3个浓度硫酰氟存在环境下臭氧浓度衰减的3组半衰期数据没有显著性差异,硫酰氟对臭氧衰减动力学曲线和半衰期存在显著性影响。通过比较活性炭颗粒、中性氧化铝、氢氧化钙悬浊液和氢氧化钠溶液对硫酰氟降解消减的能力,确定了氢氧化钠溶液的处理方法。随着温度升高,处理半衰期缩短,20、25、30 ℃条件下,0.25 mol/L氢氧化钠溶液浓度对硫酰氟处理的半衰期为592.5、404.2、323.5 min。     

大型面粉加工车间硫酰氟整体熏蒸杀虫效果评估

研究了我国华南地区广州岭南穗粮谷物股份有限公司一面粉加工车间B区、C区,长为108 m,宽为25 m,高为35.2 m,总体积为95 040 m3,有效熏蒸体积为53842 m3的空间,采用硫酰氟剂量为40 g/m3、密闭时间为48 h的整体性结构熏蒸。在不补充硫酰氟熏蒸剂的条件下,熏蒸过程浓度随时间变化的规律,建立了熏蒸剂的日损失率Ld和浓度半数衰减时间HLT,分析了各楼层硫酰氟浓度变化规律和熏蒸剂泄漏程度,评估了杀虫效果。熏蒸剂的日损失率符合模型：（e,自然常数;b,衰减常数）,浓度半数衰减时间HLT符合模型：熏蒸剂日损失率的变化随着衰减常数的增大而增大,浓度半数衰减时间HLT的变化随着衰减常数的增大而减小。单次熏蒸时衰减常数为固定值,熏蒸剂日损失率、浓度半数衰减时间HLT为恒定变化。经模型评估,6、7、8楼的日损失率Ld和半数衰减时间介于56.7 %~71.3 %和0.56~0.83 d。3、4楼区域损失率Ld和半数衰减时间介于85.0 %~92.6 %和0.27~0.37 d;除8楼硫酰氟熏蒸剂浓度半数衰减时间HLT超过15 h,其余楼层均未超过15 h。熏蒸后22 d,取样检测发现面粉加工车间设备和管道中均发现赤拟谷盗幼虫活虫。采用硫酰氟进行建筑物结构40 g/m3剂量、密闭时间48 h方式熏蒸,可将车间空间区域害虫各虫态以及管道和设备中成虫杀死,存在于设备和管道内的卵可能存活且发育成新幼虫或蛹。     

粮堆磷化氢浓度衰减阶段数学模型及验证研究

研究了压力半衰期为158 s的高大平房仓中磷化氢熏蒸后的浓度变化规律,建立了粮堆内磷化氢浓度和熏蒸时间的关系模型。经压力半衰期分别为105、96、69 s的三个高大平房仓磷化氢浓度变化的实仓验证,表明粮堆内磷化氢浓度衰减阶段的浓度呈指数下降趋势,磷化氢浓度衰减阶段浓度和时间符合指数模型C=ae~(-bt)(a0;b0)(其中C为磷化氢浓度,m L/m~3;t为熏蒸时间,d;e为自然指数;a、b为常数)。该模型可用于计算不同磷化氢浓度对应的熏蒸时间、不同熏蒸时间对应的磷化氢浓度、预测粮堆的补药时间等。结合气体发生阶段模型还可以计算磷化氢熏蒸最大浓度、最低熏蒸浓度下的有效熏蒸时间以及磷化氢浓度半数衰减时间HLT。     

不同施药方式硫酰氟熏蒸高大平房仓效果比较研究（网络首发、推荐阅读）

通过比较分析3种不同实仓施药方式硫酰氟熏蒸高大平房仓的穿透力、均匀性和杀虫效果,探索硫酰氟在实仓熏蒸的最佳工艺。结果表明,硫酰氟气体可在2.5 h内自然扩散穿透粮堆,24 h左右达到整仓基本均匀。环流熏蒸可以加速气体均匀,但此次实验环流过程中导致了一定药剂损失。在整仓熏蒸、膜下上行环流和膜下下行环流的3种熏蒸方式中,整仓熏蒸操作最为简便,可用于快速杀灭成虫;膜下上行环流方式,药剂损耗量较大;膜下下行环流,浓度均匀速度快,用药量较整仓小,药剂浓度保持时间长,杀虫效果好。     

高大平房仓不同熏蒸方式浓度分布研究

本研究通过膜下环流熏蒸、氮气气调、氮气与磷化氢混合熏蒸三种熏蒸方式,来分析在高大平方仓中这三种方式施药后,熏蒸气体的空间浓度分布情况。结果表明,覆膜环流熏蒸仓房底部磷化氢浓度在第3 d达到最大,较常规熏蒸快2～4 d。氮气和磷化氢混合熏蒸在环流6 h后各层粮堆内气体分布基本达到均匀,整个熏蒸过程中磷化氢最低浓度与最高浓度的比值范围为0.37～0.67,氮气浓度始终保持在83%～87%之间。混合熏蒸与膜下环流熏蒸相比,可以减少用药量10.8%;同时,解决了氮气气调对气密性要求严苛以及运营成本高的难题,供粮食仓储企业在实际熏蒸杀虫工作中参考。     

A comparison between the impact of sulfuryl fluoride and methyl bromide fumigations on stored-product insect populations in UK flour mills

The impact of sulfuryl fluoride and methyl bromide fumigations upon populations of flour beetles (Tribolium spp.) and of Mediterranean flour moth (Ephestia kuehniella), was evaluated in UK flour mills. Two mills were selected for fumigation with sulfuryl fluoride and two mills for fumigation with methyl bromide. Traps baited with aggregation pheromone lure and an oil-based food attractant were used to monitor populations of rust red flour beetle and confused flour beetle. For the monitoring of Mediterranean flour moth, sticky traps baited with a pheromone lure were used. Traps were placed inside the mill buildings within the areas selected for fumigation. Infestation levels of the insects were monitored for 1–2 weeks prior to fumigation and for a total of 12 weeks post-fumigation. From the calculated percentage reduction in insects trapped per day during the post-fumigation monitoring period it was clear that sulfuryl fluoride fumigations had good efficacy against infestations of Tribolium confusum and E. kuehniella, and compared very favourably with the efficacy of methyl bromide. The absence of T. castaneum in traps pre-fumigation meant that the efficacy of sulfuryl fluoride against this species could not be assessed in this investigation. Indian meal moth, Plodia interpunctella, was also detected in some mills but only post-fumigation.     

Pest control treatments with phosphine and controlled atmospheres in silo bags with different airtightness conditions

The silo bag technology has been extensively used in Argentina for storing grains (e.g. wheat, corn, barley, sunflower and soybean among others) since the mid-1990s. Silo bag are widely considered a hermetic storage system in which PH₃ fumigation is frequently implemented for pest control. However, there is insufficient information regarding the potential airtightness of silo bags and how it could affect the performance of fumigation and controlled atmosphere treatments. In this study, a pressure decay test (PDT) was implemented to characterize airtightness level of silo bags set up following various procedures. PH₃ fumigation treatments with different dosages and hermeticity levels were conducted, and fumigant concentration was monitored. Controlled atmosphere treatments with carbon dioxide were also implemented in silo bags with different hermeticity levels. Results showed that less than half of the bags tested in the field had a PDT indicated for fumigation (90 s), and that when a bag without thermo sealing was used for fumigation, this treatment failed. However, it was demonstrated that with simple and inexpensive practices silo bags can achieve high enough airtightness conditions to implement successful PH₃ fumigation (5 days above 200 ppm with a dosage of 1 g of PH₃/m³) and even controlled atmosphere treatments (more than 18 days with CO₂ concentration above 70%). This study shows that silo bags could be used as a cost competitive hermetic storage technology for performing controlled atmosphere treatments.     

Sulfuryl fluoride fumigation of red oak logs eradicates the oak wilt fungus

Preliminary field trials using red oak logs from trees dying from oak wilt disease were successful in eliminating the oak wilt fungus from sapwood after fumigation with sulfuryl fluoride for 72 h under tarp. These results support earlier laboratory data on the fungitoxicity of sulfuryl fluoride as a potential replacement for methyl bromide treatment of exported red oak veneer logs. However, not all other microorganisms were completely eradicated from oak sapwood at the treatment levels used in this trial.

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Gas leakage and distribution characteristics of methyl bromide and sulfuryl fluoride during fumigations in a pilot flour mill

The half-loss time (HLT) is used as an indicator to quantify gas leakage rates during methyl bromide (MB) and sulfuryl fluoride (SF) fumigations. Comparisons of HLTs between three MB and three SF fumigations were quantified in the Hal Ross pilot flour mill, Department of Grain Science and Industry, Kansas State University, USA. The sealing quality or gas tightness of the mill before each fumigation was verified by a pressurization test. Fumigant concentrations during the six fumigations were monitored continuously at 30 locations among the five mill floors during the 24 h fumigation period. A weather station on the mill roof monitored barometric pressure, wind speed and direction, temperature, and relative humidity. A data logger on each mill floor recorded temperature and relative humidity. The pressurization test showed that the relationship between airflow rate and building static pressure varied among the fumigations despite the same areas being sealed by two separate fumigation service providers due to environmental conditions not being identical among the fumigations. Concentration differences of both fumigants within the mill ranged from 2 to 7 g/m³. The observed HLTs for the MB and SF fumigations were in the range of 3.61 to 28.64 h and 9.97 to 31.65 h, respectively, and were inversely related only to wind speeds during fumigation and not any other environmental conditions recorded. In our study, the fumigant leakage rate was found to be predominantly a function of wind speed rather than inherent gas characteristics of MB and SF.