Trace element loads in the Great Lakes Basin: A reconnaissance

Water quality data for trace elements in the Great Lakes are relatively scarce, complicating the assessment of current trace element baselines and their distribution patterns. Here, we present concentration data for >40 major and trace elements in >100 samples from the Great Lakes connecting channels, surface waters, precipitation and select Canadian tributaries, to establish a high-level assessment of loading rates across the basin. Contrasting upstream-to-downstream trends were observed for the investigated trace elements, ranging from net-decreasing (>5-fold for e.g., Co, Tl, Y) to net-increasing surface water concentrations (>2-fold for e.g., Sb, U, As). Calculated loading rates reveal different, element-specific controls of runoff, connecting channel loads or precipitation on trace element occurrence. Lake-wide elemental mass-balances could be reasonably closed for conservative trace elements (e.g., Li, <53% residual) but not for others (e.g., rare earth elements with up to 5-fold discrepancies), reflective of general data scarcity and uncertainty in loading rates. In line with major water quality trends, spatial distribution patterns in Lakes Erie and Ontario display subtle near-shore to off-shore heterogeneity for a few trace elements (<1 order-of-magnitude for V or Se), but higher variability for trace elements with significant inputs derived from tributaries. This work provides important quantitative baseline data for trace elements in the Great Lakes that may help optimize surveillance and management strategies for the preservation of Great Lakes water quality.     

Olfactory responses of Stegobium paniceum to different Chinese medicinal plant materials and component analysis of volatiles

Stegobium paniceum (L.) (Coleoptera: Anobiidae) is among the major pests of stored products, causing great damage to stored Chinese medicinal plant materials (CMPMs) in China. Effective control strategies are urgently needed. The aim of this study was to explore the role of volatile organic compounds in the host preference of S. paniceum. First, the olfactory behavioral responses of S. paniceum adults to volatiles from four CMPMs (Panax notoginseng, Angelica sinensis, Gastrodia elata, and Peucedanum praeruptorum) were tested in Y-tube olfactometer experiments. Then, the volatile composition of these plant materials were analyzed by gas chromatography-mass spectrometry (GC-MS). S. paniceum showed significant preferences for volatiles from the four CMPMs, compared with clean air (CA). When S. paniceum was presented with choices among different CMPMs, it showed the strongest preference for P. notoginseng, followed by A. sinensis, then G. elata, and P. praeruptorum. GC-MS analysis identified 43, 34, 28 and 60 components in the volatile profiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. Falcarinol (14.4%), 3-n-butyl phthalide (78.7%), p-cresol (40.1%), and β-pinene (29.1%) were the most abundant components of the volatiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. The olfactory responses of S. paniceum to the four CMPMs demonstrated that host-related volatiles play an important role in the host-searching process by adult beetles. This information will be useful for the development of safe and effective trapping strategies for this pest.     

Changes in Benthic Invertebrate Communities of South Bay,Lake Huron Following Invasion by Zebra Mussels (Dreissena polymorpha), and Potential Effects on Lake Whitefish (Coregonus clupeaformis) Diet and Growth

In this study we evaluated changes in benthic invertebrate communities of South Bay, Lake Huron following the invasion of zebra mussels (Dreissena polymorpha) and considered the implications for diets and growth of whitefish (Coregonus clupeaformis), a commercially important fish in the Great Lakes. Of the ten benthic invertebrate groups identified prior to invasion (1980–81), only densities of Diporeia and Oligochaeta have changed since the appearance of the zebra mussel, and only Diporeia and Chironomidae changed in relative abundance. These changes are similar to those observed in other areas of the Great Lakes, with the exception of an increase in Oligochaeta density. Post-invasion (2002–03) shallow-water communities appear to be more homogeneous, dominated by zebra mussels and Isopoda, whereas deep-water sites are more heterogeneous due to the loss of Diporeia. Additional data on Diporeia density for several years between 1959 and 2004 indicated that current low densities are not typical of South Bay. Based on changes in the benthic communities and published literature on whitefish diets, we predict that unless whitefish are able to switch to Mysis as an alternative to Diporeia, post-invasion whitefish diets will only contain a maximum of 57 to 84% of their former energy content. These predictions are likely underestimates, as they do not take into account increased energy costs associated with reductions in total invertebrate density at historical foraging depths.     

冬瓜薏仁果酒工艺条件的研究

以优化冬瓜薏仁果酒的工艺条件为主要研究目标,经酵母筛选试验发现安琪水果酵母最适合冬瓜薏仁果酒的发酵,发酵周期为8 d,发酵温度为26 ℃;同时根据单因素试验和正交试验得到了冬瓜薏仁果酒最优工艺条件为初始糖度20%、初始pH值为3、酵母添加量4%、薏仁粉与冬瓜的质量比为1∶20。在此最佳条件下研制的冬瓜薏仁果酒酒精度为8.3%vol,感官评分为94.5分。     

三级净化塘生态修复技术用于处理农业种养废水

针对农业种养废水造成的面源污染问题,利用三级净化塘处理工艺对云南省大理州某农业生活与生产交汇区产生的农业废水进行了生态拦截与修复。实际运行结果表明,该工艺处理效果良好,运行稳定,对水体中总氮、总磷和COD的累计去除率分别达到96.76%、95.08%和83.90%,出水水质达到《地表水环境质量标准》(GB 3838—2002)的Ⅲ类标准。     

正交试验优化芒果果脯微波渗糖工艺

以凯特芒果为原料,芒果果脯总糖含量为评价指标,通过单因素试验和正交试验优化芒果果脯微波渗糖工艺条件,并分析黄原胶对芒果果脯质构特性的影响。结果表明,最佳微波渗糖条件为微波功率210 W、料液比1∶3（g∶mL）、黄原胶添加量0.3%、微波时间60 min、糖浓度40%,在该最佳工艺条件下,芒果果脯的总糖含量为46.24%。0.3%黄原胶的添加能显著降低果脯硬度和提高其咀嚼性（P＜0.05）,而对内聚性、弹性、胶黏性没有显著影响（P＞0.05）。     

硒在辣木-土壤中的迁移转运规律

目的 随着人们膳食营养健康意识的不断提高,富硒辣木作为一种多功能植物具有很高的附加值和巨大的发展潜力。方法 为了研究硒在辣木-土壤中的富集转运,以盆栽辣木为试验材料,以电感耦合等离子体质谱仪为检测手段,以基施和喷施为外源硒添加方式,研究了硒在辣木中的富集效果以及土壤、辣木中硒含量的相关性。结果 结果表明,辣木是较好的硒富集植物,喷施添加比基施添加对硒的富集作用明显,喷施处理后,辣木杆、根及土壤中硒含量比未添加分别增加了约10倍、6倍、1倍,基施处理后,辣木杆、根及土壤中硒含量比未添加分别增加了约2倍、2倍、3倍,与基施相比,喷施后硒的生物可利用性更高;硒添加后,在土壤-辣木系统中迁移转运,与从地下部分到地上部分的转运效率相比,从地上部分到地下部分的转运效率更高,且硒主要在杆中积累;随着添加量的增加,硒会逐渐迁移转运至根部和土壤中,并在土壤中积累;无论哪种添加方式,硒的富集效果均是：杆＞根＞土壤。结论 本试验的研究为生产中通过施硒肥的外源调控措施来改善植物中硒含量,为更合理的开发利用富硒产品提供了技术支撑。     

外源乙烯对马铃薯发芽的抑制作用

目的:研究外源乙烯在室温条件下对马铃薯发芽的抑制作用。方法:使用固体乙烯释放剂处理马铃薯,观察外源乙烯对马铃薯发芽时间和发芽指数的影响。结果:实验结果表明,乙烯有效推迟了马铃薯的起始发芽时间8～10d,而且乙烯浓度越高,效果越好;重复使用的效果更佳,可以降低发芽指数15%左右;浸蘸具有增效作用,降低发芽指数8%左右。结论:外源乙烯可对马铃薯的发芽起到一定的调控作用,但发芽进程无法完全抑制。     

金银花萃取物致香成分研究及其在烟草中的应用

为考察金银花萃取物在卷烟中应用,采用同时蒸馏法进行萃取,应用GC/MS定性定量分析化学成分,通过卷烟加香试验,结合感官评吸判定感官质量的变化情况。化学分析结果表明:金银花萃取物中共鉴定出挥发性成分31种,其中主要的致香成分有:芳樟醇(8.25%)、β-大马酮(5.20%)、橙花醇(4.82%)、β-紫罗兰酮(4.64%)、新植二烯(4.45%)、香叶醇(4.13%)等,以及大量的醇类、酸类等。评吸结果表明:金银花萃取物能改善卷烟烟香,使烟气甜润,细腻柔和,杂气、刺激性减小,余味干净,烟气通畅感增加,明显提高卷烟抽吸品质。     

食品和食品包装材料中全氟化合物(PFCs)的研究进展

全氟化合物(perfluorochemicals,PFCs)具有持久性、生物累积性,被列入新型持久性有机污染物,目前已成为环境与食品安全研究的热点领域。全氟化合物主要包括稳定态和离子态氟化物,被广泛应用于表面活性剂、食品包装、不粘锅涂层等与食品包装及加工相关的领域。本文对PFCs的理化性质、应用、毒性作用以及在食品中的污染水平进行了评述,重点探讨了其在食品中的分析测定方法,以期为我国开展食品领域内全氟化合物的风险评估及相关研究提供参考。