Work division of floral scent compounds in mediating pollinator behaviours

Floral scents are known as an olfactory signal for attracting pollinators, but why the flowers pollinated by highly specialised pollinators emit scents consisting of mixtures of many compounds and dominated by one or a few compounds is still poorly understood. We supposed that each (especially characteristic) chemical in floral scents may play a specific role in mediating pollinator behaviours and tested this supposition in a fig-fig wasp mutualism. Ficus curtipes is obligately pollinated by an undescribed Eupristina species. In the scent of F. curtipes receptive figs, over 50 compounds have been identified, and the scent is dominated by two compounds, 6-methyl-5-hepten-2-ol (OL) and 6-methyl-5-hepten-2-one (NE). We therefore tested the roles of the two major chemicals in mediating the pollinator behaviours. Our results show that OL and NE, respectively, act as a long-distance attractant and a fig-entry behaviour stimulant to the obligate pollinator wasp. Namely, OL attracts the wasps to the figs and NE guides the wasps into the figs. This finding on the work division of floral scent compounds partially explains the maintenance mechanism of the fig-fig wasp mutualism and the significance of the chemical diversity of floral scent in plant–pollinator interactions, especially in specialised pollination systems.     

Multiannual trend of microcystin production in the toxic cyanobacterium Planktothrix rubescens in Lake Garda (Italy)

Massive developments (blooms) of cyanobacteria represent a major concern in many natural and artificial waterbodies, because of the high levels of toxins that can be released into water. Microcystins, potent hepatotoxins, represent the most frequent toxins produced by cyanobacteria. The determination of the microcystins’ profile in waterbodies is important for determining the real toxic potential. We have investigated the evolution of the microcystins’ profile of Lake Garda (Italy) from both a qualitative and a quantitative point of view over a period of five years. We have also analysed possible correlations between toxin profile and selected environmental parameters. We found that a demethylated microcystin variant (RRdm) was always dominant but showing a cyclic trend, alternating periods in which it represented the only variant, and periods in which other variants were present (LRdm, HtyrRdm, RR, and LR). These changes are probably due to changes in chemotypes composition inside the resident Planktothrix rubescens population and do not seem to be exclusively linked to the considered environmental variables. Total microcystin concentrations were always low (in the ng?L^?1 scale), and showed typical peaks in the metalimnetic layer during summer–autumn time of each year.     

Experimental study on advantages of foam–sol in coal dust control

In China, more than 2.65 million coal mine workers are exposed to coal dust. Every year, new pneumoconiosis cases amount to 25,000, among which 6000 cases die of this disease. The figure is twice the death toll in production safety accidents. Occupational diseases seriously endanger life and health of coal mine workers, and restrict the healthy growth of the coal industry.The paper presented a study of foam–sol-based coal dust control. This was an experimental study of characteristics of foam–sol-based coal dust control, which features dust capture, suppression, and isolation. Comparative wettability experiments were carried out to determine contact angles of water, aqueous foam, and foam–sol solution. A new foam–sol generating system with a conical diffuser outlet was proposed.The experiment results clearly showed that the foam–sol features dust capture, suppression, and isolation. The wettability of the aqueous foam solution was better than the foam–sol solution, but the foam–sol technology had the better ability to capture the airborne dust, suppress the static dust and enclose the dust source, due to the excellent surface viscosity, strong cohesiveness and less volatile property. The paper concluded that the foam–sol could greatly improve the dust control efficiency and did not have main deficiencies that the aqueous foam technology had.     

城市污水中人类星状病毒的检测及变化规律

人类星状病毒是典型的水媒病毒,可引起腹泻等疾病. 为了明确污水中人类星状病毒的分布及去除规律,利用常规PCR和定量PCR方法对西安市3个污水处理厂的进水和出水进行了为期1 a的监测;采用特异性引物,确立了人类星状病毒在环境水体中的定性PCR和荧光定量PCR的检测方法. 结果表明,人类星状病毒在进水和未消毒二级出水中呈较高的阳性率,分别为91.5%和36.6%. 经过核苷酸测序鉴定,人类星状病毒的主要血清型为HAst V-1和HAst V-4. 人类星状病毒在进水和未消毒二级出水中的平均浓度分别为1.47×104和1.03×103 copies/mL,污水处理厂对人类星状病毒的去除率为93.15%. 污水处理厂进水中人类星状病毒浓度呈季节性变化,春季和冬季较高,夏季和秋季较低,这一分布规律与该地区历年人类星状病毒的流行规律相似.      

土壤有机碳储量估算的影响因素和不确定性

土壤作为陆地生态系统最大的碳库和碳循环过程的关键环节,其源、汇的变化直接影响全球碳平衡,因此,土壤有机碳储量估算成为生态领域的重要研究内容之一。通过比较不同研究者在不同研究尺度上报道的有机碳储量的研究结果,发现这些研究结果较不一致。分析认为导致土壤有机碳储量评估结果存在较大差异的原因,主要是来自于采样过程中人类干扰以及气候变化等环境要素的波动,特别是研究者所采取的不同估算方法和背景资料。从环境要素（外因）和估算方法（内因）两个角度出发,提出了土壤有机碳储量的研究意义,阐述了造成土壤有机碳储量估算的不确定性和目前研究中存在的问题,并在此基础上,对其未来研究方向和重点进行了展望。     

国家历史文化名城地区农业与水文地质的关系

国家历史文化名城地区记录了华夏农耕文明更多的生活经验,论文以这些城市地区为研究对象,通过在全国尺度选取典型群体110 个国家历史文化名城地区为样本,并定义农业水文地质适宜度指标,对各类水文地质与农业活动的空间关系进行了量化。从研究结果来看：各富水程度的松散岩类孔隙含水岩组是农业适宜性较强的水文地质类型;碳酸盐岩类含水岩组的农业适宜性也较强;而岩浆岩类含水岩组以及变质岩类含水岩组等则是农业适宜性较弱的水文地质类型,其中松散岩类孔隙含水岩组的农业水文地质适宜度是岩浆岩类含水岩组以及变质岩类含水岩组的2~3 倍。     

基于灰色系统理论的煤矿人因事故关键因素分析

通过对煤矿人因失误事故致因因素进行分析,统计出相关的关键影响因素,运用灰色系统关联理论,根据国家安监局近十年煤矿事故统计数据,对煤矿人因失误事故影响类型进行了分析。以煤矿事故发生起数和事故死亡人数作为参考指标,计算和分析行为失误致因、个人违章、组织管理失误等十项主要与煤矿人因事故相关的灰色关联度,进而推算出这些因素的灰色关联序,确定出导致煤矿人因失误事故的关键因素,最终得到煤矿人因事故与关键影响因素之间的定量化分析结果。采用灰色关联理论对煤矿人因失误影响因素进行分析,能够很好地说明人因失误与各关键影响因素之间的权重关系,对煤矿人因事故主致因机理有更加深刻的理解,为煤矿事故的预防和控制提供重要的参考依据。     

基于事故/事件的民机人因防错设计关键因素研究

针对民机人因防错设计对飞行安全的影响,从世界民航安全事故/事件数据库中筛选出92起典型的人为因素事故案例,采用基元事件分析法进行深度分析,提炼出民机人因防错设计需要考虑的重要设计因素,并建立重要设计因素集。基于系统工程学的“人机环”模型,结合国内外飞机设计相关标准,建立民机人因防错设计重要因素指标体系。运用模糊层次分析法对因素指标进行权重计算,确立影响飞行安全的14项人因防错设计关键因素,并针对这些关键因素提出民机人因防错设计通用要求,以期为民机人因防错设计满足初始适航要求提供参考。     

老化土壤中As的人体可给性控制因素及健康风险

采用UBM(unified bioaccessibility model)模拟胃肠消化的方法测试了来自湖南省、广西壮族自治区和大连市的13个不同理化参数污染土壤中As的人体可给性,分析了考虑As人体可给性对风险评估结果的影响. 结果表明:①供试土壤样品模拟胃提取阶段As的人体可给性因子为3.9%~49.5%,平均值为19.6%;模拟肠提取阶段的人体可给性因子为1.2%~10.8%,平均值为6.0%,前者是后者的1.2~9.1倍. ②影响供试土壤样品胃提取阶段As人体可给性浓度的最显著性因素是w(TAs)(R2=0.94,P<0.01,n=13),其次为w(TP)(R2=0.82,P<0.01,n=13)和w(TMn)(R2=0.79,P<0.01,n=13);影响肠提取阶段As人体可给性浓度的显著因素依次为土壤w(TAs)(R2=0.83,P<0.01,n=13)、w(TP)(R2=0.80,P<0.01,n=13)、胃提取阶段As的人体可给性浓度(R2=0.76,P<0.01,n=13)、pH(R2=0.74,P<0.01,n=13)、w(TMn)(R2=0.65,P<0.02,n=13)以及w(TOM)(TOM为有机质)(R2=0.59,P<0.04,n=13). ③基于土壤w(TAs)和w(黏粒)构建的模型能较好地预测As在胃提取阶段的人体可给性浓度,预测值与实测值的R2达到0.97,ME(平均误差)、RMSE(均方根误差)、r_p2(可决系数)分别为0.02、0.17、0.95;仅基于土壤w(TAs)构建的模型能较好地预测As在肠提取阶段的人体可给性浓度,R2达到0.90,ME、RMSE、r_p2分别为-0.03、0.26、0.80. ④以供试土壤样品中w(TAs)为暴露浓度计算的健康风险分别是考虑As在胃及肠提取阶段人体可给性因子的2.0~15.0和7.3~81.0倍. 可见,基于土壤w(TAs)所制定的风险管理对策可能过于保守.      

基于用地规划的大型污染场地健康风险评估

以某焦化类大型污染场地苯污染土壤为例,针对S1(单一用地)、S2(多种用地)、S3(考虑建筑设计)3种暴露情景,分析不同情景下场地土壤中苯污染的暴露途径并进行健康风险评估. S1情景下的苯致癌风险为9.2×10-5. 在S2情景下,规划的5个分区中仅E区(居住用地)苯的致癌风险(4.3×10-4)高于可接受水平(1.0×10-6), 考虑到各功能区累积致癌风险,则E区高污染可导致其他4个功能区〔A区(商业用地)、B区(城市绿地)、C区(居住用地)、D区(商业用地)〕的累积致癌风险(分别为6.5×10-6、2.2×10-6、7.3×10-6、2.2×10-5)均高于可接受水平,表明单一用地会低估污染物聚集区的风险. 在S3情景下,A、B、C区土壤中苯的致癌风险(分别为1.2×10-7、2.7×10-7、2.5×10-7)均未超过可接受致癌风险水平;D区由于污染土壤被完全清除,不存在健康风险;E区开发后由剩余土壤产生的苯致癌风险为2.7×10-5,D区受E区影响产生的累积致癌风险(1.5×10-6)高于可接受水平. 进一步分析表明,场地的用地规划与建筑设计等因素将影响风险评估中关键参数(包括污染源浓度、水文地质参数、暴露参数、受体参数等)的取值,从而影响风险评估结果;此外,各功能区之间的风险影响也不容忽视. 对于大型污染场地,结合用地规划进行暴露情景分析与风险评估更为科学合理.