Effect of buffer strips and soil texture on runoff losses of flufenacet and isoxaflutole from maize fields

The influence of buffer strips and soil texture on runoff of flufenacet and isoxaflutole was studied for two years in Northern Italy. The efficacy of buffer strips was evaluated on six plots characterized by different soil textures; two plots had Riva soil (18.6% sand, 63.1% silt, 18.3% clay) while the remaining four plots had Tetto Frati (TF) soil (37.1% sand, 57% silt, 5.9% clay). Additionally, the width of the buffer strips, constituted of spontaneous vegetation grown after crop sowing, was also compared for their ability to abate runoff waters. Chemical residues in water following runoff events were investigated, as well as their dissipation in the soil. After the first runoff events, concentrations of herbicides in water samples collected from Riva plots were as much as four times lower in waters from TF plots. On average of two growing seasons, the field half-life of flufenacet in the upper soil layer (5 cm) ranged between 8.1 and 12.8 days in Riva soil, 8.5 and 9.3 days in TF soil. Isoxaflutole field half-life was less than 1 day. The buffer strip was very affective by the uniformity of the vegetative cover, particularly, at the beginning of the season. In TF plots, concentration differences were generally due to the presence or absence of the buffer strip, regardless of its width.     

Effects of probiotic bacteria on the bioaccessibility of aflatoxin B1 and ochratoxin A using an in vitro digestion model under fed conditions

In the present study, we aimed at determining the release of aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) from different food products in the gastro-intestinal tract in the absence and presence of probiotics, a possible adsorbent. The average bioaccessibility of AFB₁ and OTA without probiotics was about 90%, and 30%, respectively, depending on several factors, such as food product, contamination level, compound and type of contamination (spiked versus naturally contaminated). The six probiotic bacteria showed varying binding capacity to AFB₁ and OTA depending on the bacterial strain, toxin studied, type of food and contamination level. A reduction to a maximum of 37% and 73% as observed for the bioaccessibility of AFB₁ and OTA in the presence of probiotic bacteria, respectively. This is the first report on the effect of probiotic bacteria on reducing the fraction of mycotoxins available for absorption in the gastrointestinal tract from different food products.     

基于层次分析法的人工湿地减排绩效评估指标体系研究

绩效减排有助于发挥减排工程潜力,为水污染减排提供更大空间.结合人工湿地特点,以水污染物减排为主要目标,从减排治污、资源利用、经济和管理指标选择了12个评估指标,并基于层次分析法对各个评价因子的权重进行了确定和判断,构建了人工湿地减排绩效评估指标体系,评估人工湿地减排绩效.通过科学分析人工湿地的减排绩效,优化人工湿地规划、设计和管理水平.     

商业SCR烟气脱硝催化剂钙中毒研究

使用2种不同浓度的前驱体溶液(Ca(NO3)2和Ca(CH3COO)2溶液)浸渍新鲜商业SCR(selective catalytic reduction)烟气脱硝催化剂,并对浸渍中毒后催化剂的性能进行了研究。实验结果表明,物理中毒在本研究中占主导位置,化学中毒并不明显。采用离子色谱、氮气吸附-脱附分析、红外光谱分析、X射线衍射分析、扫面电镜分析等多种表征技术对中毒后催化剂进行了表征。结果表明,中毒后催化剂孔结构性质发生了变化,特别是Ca(CH3COO)2溶液浸渍催化剂,内部孔道堵塞较为严重。X射线衍射分析和扫描电镜分析也从另一方面说明了CaCO3的出现及积累导致催化剂脱硝效率降低。此外,催化剂红外光谱分析从表面活性位的角度说明了本研究催化剂化学中毒现象并不明显。     

亚铁离子生物氧化-还原法连续脱除硫化氢

为了降低工业废气中的硫化氢去除工艺成本和运行费用,对三价铁盐吸收与氧化亚铁硫杆菌对Fe²⁺的生物氧化联合作用脱除H₂S进行了研究。通过生物氧化塔中的固定化氧化亚铁硫杆菌细胞再生的Fe³⁺溶液,在H₂S还原吸收塔中脱除H₂S。通过单因素实验分别优化了生物氧化塔和H₂S吸收塔的运行参数,在生物氧化塔曝气量为150 L/h,停留时间为11 h,吸收液中Fe³⁺浓度为0.121~0.143 mol/L,吸收液流量为0.3 L/h,进气量为100 L/h条件下,进气中H₂S浓度分别为2.28和9.11 mg/L,系统连续运行至200 min时趋于相对稳定,当系统连续运行稳定时,H₂S的脱除率可分别达到95%和91%,脱除效果显著。     

加快废钢产业发展 促进钢铁资源循环利用

分析了废钢的应用现状及应用不足的原因,为加快废钢产业发展提出建议。提出为适应当今钢铁工业节能、降耗、环保等方面的发展要求,应大力发展废钢产业,加快废钢资源利用,促进钢铁资源循环利用,实现我国钢铁工业的可持续发展．     

铁铈钛复合氧化物催化剂的制备及其选择性催化还原NO的性能

采用共沉淀法制备了一种新型催化剂——铁铈钛复合氧化物催化剂,研究了Fe掺加量、体积空速以及H2O和SO2的加入对其选择性催化还原NO性能的影响;采用XRD和SEM等手段对催化剂的结构和形貌进行了表征。表征结果显示,Fe的掺加使催化剂表面的颗粒更均匀,提高了催化剂的分散度。实验结果表明：以Ce（NO3）3,Fe（NO3）3?9H2O,TiOSO4?2H2O为原料、按n（Ce）∶n（Fe）∶n（Ti）=0.2∶0.8∶1配比制得的Ce0.2Fe0.8TiOx为催化剂,在反应温度250 ℃、反应时间3 h、体积空速25 000 h-1的条件下,NO去除率为99.8%,N2选择性为100%;Fe的掺加显著提高了Ce0.2Fe0.8TiOx催化剂的抗H2O和SO2的能力。     

Fenton氧化对硝基苯酚过程中Fe2+/Fe3+的氧化还原机制

Fenton降解对硝基苯酚(PNP)过程中,Fe2+经历一个快速氧化后快速还原,最后在高浓度水平上保持稳定的变化过程。通过分析中间产物的变化过程,发现有机中间产物氢醌和苯醌构成一对氧化还原体系催化Fe3+向Fe2+的转化,本研究从Fe2+/3+转化机制的角度进一步明确了Fenton降解PNP的机理。     

红斑体虫的污泥减量效果

为了实现红斑顠体虫捕食污泥减量化,对不同条件下红斑顠体虫的污泥减量效果进行实验研究。实验结果表明:红斑顠体虫的污泥减量速率随初始MLSS及温度的增大而增大,初始MLSS越高,污泥减量速率越大。污泥减量速率随红斑顠体虫密度变化率的增大而逐渐增大,当红斑顠体虫的密度增长率出现下降时,污泥减量速率也呈下降趋势。采用间歇曝气(12 h曝气,12 h停曝)方式,红斑顠体虫的污泥减量速率会显著下降。在污泥好氧消化时,红斑顠体虫能捕食污泥中的有机碎片和细菌,达到污泥稳定化的指标要求。     

接种比对碱超声波耦合溶胞污泥水解酸化的影响

以城市污水生物处理过程中的剩余污泥减量化为研究背景,通过实验研究了经碱超声波耦合溶胞后的剩余污泥在不同接种比下水解酸化的效果,分析了污泥上清液中pH、SCOD、VFAs、NH4+-N和PO34--P等参数随时间的变化趋势。结果表明,溶胞污泥经过72 h的水解酸化反应,20%接种比下的水解酸化COD溶出率和VFAs增长率最高,分别为75.5%和177%。蛋白质水解程度为16.9%,也高于50%和70%两组接种比。此外,COD、NH4+-N和PO34--P等主要溶出物均在12 h后达到基本稳定状态。