皂素生产废水处理方法比较研究

皂素生产废水为难处理高浓度酸性含硫有机废水,目前常用处理工艺为UASB+SBR,但该工艺运行效果较差。文章对UASB+SBR改进工艺进行了比较研究,结果表明:在UASB中加入适量铁屑和颗粒活性炭解除了SO42-的二次抑制,COD去除率比对照组UASB高2%～3%,出水水质COD一直稳定在1300mg/L左右,去除率在95%以上,出水无异味。UASB中污泥增长速率约为0.0686d-1,是仅加活性炭污泥增长速率(0.0197d-1)的3.48倍,可见加入铁屑后污泥增长速率改变明显。该改进UASB+SBR工艺的COD去除率高于对照组,出水COD维持在200mg/L以下,略带浅黄色(20倍左右),低于GB8978-1996《污水综合排放标准》原料药料二级排放标准值(300mg/L),SBR污泥增长速率为0.3083d-1,略高于对照组。     

电子商务能改善农业生产的环境负效应吗?-来自上海青浦的证据

电子商务在农村农业领域的快速发展带动了农民收入的增加,但是其作用路径和环境效应有待检验.以上海市青浦区为典型案例,利用264份新型农业经营主体的问卷调查数据,采用IV-ordered Probit模型和夏普利值分解法,研究了"电子商务+农业"模式的经济效应和环境效应.结果表明：电子商务的引入具有显著的农民增收效应,但主要以产量扩大型传导机制为主,反而加剧了农业生产的环境负效应.电子商务并非农民增收的关键因素,其贡献率仅为12%;发挥决定性作用的是新技术、新方法的应用带来的效率提升,以及生产规模扩大带来的规模经济效应,相应的夏普利分解贡献了达到31%和25%.这表明当前的"电子商务+农业"模式仍处于初级发展阶段,需要加强相应的规制和引导,实现从产量驱动阶段向质量驱动阶段转型.     

Market responses to hurricanes

This paper uses one of the strongest hurricanes to hit the US, Andrew in 1992, to define a quasi-random experiment that permits estimation of the responses of housing values to information about new hurricanes. Lee County, Florida did not experience damage from Andrew. The storm was a “near-miss.” We hypothesize that Andrew conveyed risk information to homeowners in the county. A difference-in-differences (DND) framework identifies the effect of this information on property values in areas likely to experience significant storm damage. The DND findings indicate at least a 19 percent decline in property values.     

The outcome of in-vitro contests between larvae of the endoparasitoid<Emphasis Type="Italic"> Venturia canescens</Emphasis> depends on both their relative and absolute ages

In a laboratory colony of the asexual solitary endoparasitoid Venturia canescens Grav. (Hymenoptera: Ichneumonidae), two genetically and phenotypically distinct lines (RP and RM) appear to coexist sympatrically, with the reproductive success of the RM-line being greater under con-specific superparasitism but lower under self superparasitism. To investigate the basis of the RM-lines advantage under con-specific superparasitism, we examined the outcome of inter-larval physical combat under in-vitro conditions. The results showed that the outcome depended on both the relative and absolute ages of the contestants, and that the competitive abilities of the two lines were not symmetric. In contests involving a larva and an egg, the unhatched wasp lost. In contests involving two larvae, at least one of which was newly hatched, the RP-larva tended to lose. Finally, if both larvae were at least 8–10 h post-hatching when the contest occurred, then the larger larva tended to lose, with the probability increasing with the difference in length between the two larvae. Thus, the higher reproductive success of the RM-line under competing superparasitism with the RP-line is due to a physiological difference between the newly hatched larvae of the two lines, which results in an advantage to the RM-larva independent of the order or time interval between ovipositions.Communicated by P. Heeb     

云南粳稻耐低磷特性的主基因加多基因遗传分析

磷高效水稻培育是提高土壤潜在磷利用效率的一种途径,通过对云南粳稻耐低磷特性的主基因加多基因遗传分析,可以明确耐低磷特性主基因的存在、对数及遗传效应的大小,为磷高效育种提供理论依据。本试验通过云南主栽粳稻品种合系35(Oryza sativa)与耐低磷极强早旱谷(Oryza sativa)配制P1、P2、F1、F2或F3世代,在云南省农科院进行低磷胁迫试验,对耐低磷鉴定和主基因加多基因联合遗传分析,结果表明:早旱谷的分蘖和株穗产量基因受两对主效基因 多基因相互配合遗传控制的,两对主基因间存在上位性效应,两主基因间效应差异较大。分蘖力F2主基因遗传率为58.82%~72.13%,F3主基因遗传率为45.88%~57.96%;株穗产量F2主基因遗传率60.94%~83.08%,F3主基因遗传率为62.20%~75.80%。因此育种中应当充分重视主基因的利用,利用主基因应以第一对主基因的加性效应为主,对后代耐低磷性状的选择宜从F2代开始,杂交的后期世代也要注意耐性的选择。     

芹菜赖氨酸加苏氨酸抗性细胞系的选择

用４ｍｍｏｌ－／Ｌ浓度的赖氨酸加苏氨酸作为选择压，经相同浓度液体和固体选择培养基连续选择，从未经诱变处理的芹菜胚性愈伤组织筛选出一个稳定的赖氨酸加苏氨酸抗性细胞系并得到再生植株。抗性细胞系再生植株整株的氨基酸含量比对照组植株高１０倍左右。但是地上部分氨基酸含量，抗性细胞系再生植株比对照植株有所降低。两种植株叶片的细胞色素氧化酶同工酶谱有明显差异，抗性细胞系再生植株有４条谱带，而对照植株只有两条谱带     

环境中新兴有机污染物得克隆的研究进展

得克隆(Dechlorane plus,DP),即双(六氯环戊二烯)环辛烷,是一种有机氯系脂肪族添加型阻燃剂,也是环境中一类新型的有机污染物。前期对环境中DP的研究主要集中在北美五大湖地区,近来我国和欧洲部分国家也开展了类似的研究。文章综述了DP各种环境介质中的浓度分布和同系物特征,并对需要重点开展的研究方向进行了展望。     

准组织化:“互联网+线上应急救援”的实践路径和现实困境*—以河南郑州“7·20”特大暴雨灾害事件为例

为响应我国应急管理现代化和信息化建设需要,采用参与式观察、网络民族志和深度访谈方法,从准组织化集体行动视角切入,对河南郑州“7·20”特大暴雨灾害事件中救援模式相对成熟的“互联网+线上应急救援”实践路径和现实困境进行探讨。研究结果表明:线上应急救援实践路径涵盖聚合、运转、高效、离散4个阶段,且以持续不断的行动流呈现,具有准组织化集体行动特征;同时,线上救援形式面临“合法性”不确定、救援质量不稳定、风险评估主观性和政府正式沟通渠道有限性等现实困境,研究结果可为我国应急管理信息化建设提供参考。     

Behaviour of endosulfan in cabbage (Brassica oleracea L.)

Residue levels of endosulfan were determined in cabbage heads after being sprayed with a formulation containing the insecticide and upon storage at room temperature (15–27°C) and in a refrigerator (2–5°C). The half-life was calculated to be 4.8 and 5.5 days. Peeling removed the residues by 92%. Similarly, washing and washing followed by cooking removed 72% and 97% residue in cabbage stored at room temperature. These treatments were slightly less effective for samples stored in a refrigerator. Household processes such as peeling, washing, and washing followed by cooking should be regular practice before the vegetables are used.