氮、磷浓度对伪鱼腥藻生长及光合生理的影响

以伪鱼腥藻(Pseudanabaena sp.)为研究对象,研究了不同氮、磷浓度对伪鱼腥藻生长、叶绿素荧光参数(F_v/F_m、α、rETR_max、I_K)及类胡萝卜素与叶绿素a比值等的影响,并应用Monod和Droop方程考察氮、磷营养盐对伪鱼腥藻生长动力学的影响,分别计算得到伪鱼腥藻对总磷的半饱和常数K_sP,细胞内磷份额Q₀与对总氮的半饱和常数K_sN。结果表明:氮、磷浓度对伪鱼腥藻的生长影响极显著(P<0.01),在氮浓度为0～230.4 mg/L内,伪鱼腥藻的生物量与氮浓度呈正相关,磷浓度>1.28 mg/L会抑制伪鱼腥藻生长。氮浓度对各叶绿素荧光参数有显著影响(P<0.05),磷浓度对F_v/F_m、I_K有显著影响(P<0.05),而对rETR_max、α影响不显著(P>0.05...     

高职高专教育环境下的大学语文课程研究

在高职高专教育环境下,大学语文课程的日益边缘化已经成为不争的事实。大学语文重不重要这一问题,原则性的答案和事实上的回答截然对立。2004年3月,内地及港澳台学者在“大学语文教学研讨会”上达成共识,他们认为:“只要不把大学办成技校,只要大学还是大学,大学语文的作用就不容忽视。”因而,现在的主要问题不是论证大学语文多么重要,而是要研究教学效果的达成。本文将通过对大学语文课程的性质定位、教学内容、教学方法和考核方式进行分析和研究,进而论证大学语文对高职学生素质和能力培养的积极意义。     

节能减排,政府先行

伴随着经济高速增长而来的环境危机和资源短缺,节能减排已成为席卷全球的新浪潮。新兴国家,诸如印度、中国和巴西等如此,即便是像挪威、卢森堡、德国等这样的发达国家同样也紧锣密鼓,力求在这轮低碳经济的竞争中占据有利地形。     

钙盐沉淀法处理集成电路工业含氟废水影响因素研究

研究了钙盐的投加量、pH值以及反应后的静置时间等因素在常温下对氢氧化钙和氯化钙两种钙盐用于处理某集成电路工业含氟废水的影响。结果表明,氢氧化钙在处理该废水过程中优于氯化钙;当达到理论投加量的200%时,pH=8.0左右,静置60m in后,处理初始氟浓度为500mg/L的集成电路工业废水,其出水可以达到污水排放一级标准。     

Ethnicity,housing and personal factors as determinants of VOC exposures

Previous studies investigating effects of personal, demographic, housing and other factors on exposures to volatile organic compounds (VOC) have focused on mean or median exposures, and generally not the high exposures that are of great interest. This paper identifies determinants of personal VOC exposures on a quantile-specific basis using a nationally representative sample. The NHANES 1999–2000 VOC dataset was merged with personal, demographic, housing, smoking and occupation variables. Bivariate analyses tested for differences in geometric means and quantiles across levels of potential exposure determinants. Multivariate sample-weighted ordinary least-squares (OLS) and quantile regression (QR) models were then used to adjust for covariates. We identify a number of exposure determinants, most of which varied by exposure quantile. The most striking finding was the much higher exposures experienced by Hispanics and Blacks for aromatic VOCs (BTEX: benzene, toluene, ethylbenzene and xylenes), methyl tert-butyl ether (MTBE), and 1,4-dichlorobenzene (DCB). Exposure to gasoline, paints or glues, and having a machine-related occupation also were associated with extremely high BTEX and MTBE exposures. Additional determinants included the presence of attached garages and open windows, which affected exposures of BTEX (especially at lower quantiles) and MTBE (especially at higher quantiles). Smoking also increased BTEX exposures. DCB was associated with air freshener use, and PERC with dry-cleaned clothing. After adjusting for demographic, personal and housing factors, age and gender were not significant predictors of exposure. The use of QR in conjunction with OLS yields a more complete picture of exposure determinants, and identifies subpopulations and heterogeneous exposure groups in which some individuals experience very elevated exposures and which are not well represented by changes in the mean. The high exposures of Hispanics and Blacks are perplexing and disturbing, and they warrant further investigation.     

温度环境试验及其标准综述(四)温度试验技术

<正>1温度试验设备和辅助仪器1.1对温度试验箱的要求温度试验设备包括高温箱、低温箱、高低温箱、温度冲击箱和快速温度变化箱。虽然都是用来产生温度条件,不同的温度试验项目对温度试验设备的要求有所不同。对试验箱的结构和参数要求也略有区别(见表1)但不管什么试验箱,它们都应能产生并保持试验方法标准中所规定的试验条件,并在规定的容差范围,以确保试验结果的重现性。1.2对辅助设备和仪器的要求     

Monitoring nitrogen deposition in typical forest ecosystems along a large transect in China

The nitrogen (N) deposition fluxes were investigated in eight typical forest ecosystems along the North–South Transect of Eastern China (NSTEC; based on the ChinaFLUX network) by ion-exchange resin (IER) columns from May 2008 to April 2009. Our results demonstrated that the method of IER columns was both labor cost saving and reliable for measuring dissolved inorganic nitrogen (DIN) deposition at the remote forest stations. The deposition of DIN in the throughfall ranged from 1.3 to 29.5 kg N ha^?1 a^?1, increasing from north to south along NSTEC. The relatively high average ratio of ammonium to nitrate in deposition (1.83) indicated that the N deposition along the NSTEC in China mostly originated in farming and animal husbandry rather than in industry and vehicle activities. For seasonal variability, the DIN deposition showed a single peak in the growing season in the northern part of NSTEC, while, in the southern part, it exhibited double-peaks in the early spring and the mid-summer, respectively. On the annual scale, the DIN deposition variations of the eight sites could be mainly explained by precipitation and the distances from forest stations to provincial capital cities.     

12种杀菌剂制剂对半闭弯尾姬蜂的急性毒性及安全性评价

采用试管药膜法测定了12种杀菌剂制剂对半闭弯尾姬蜂成蜂的急性接触毒性,结合安全性系数评价了供试药剂对半闭弯尾姬蜂的安全性。急性毒性测定结果表明,氟硅唑和啶菌噁唑对半闭弯尾姬蜂成蜂的接触毒性最高,LC50值分别为220.022和223.115 mg·L-1;其次为多抗霉素、丙森锌和戊唑醇,LC50值分别为436.496、472.358和638.638 mg·L-1;其余7种杀菌剂制剂嘧霉胺、啶酰菌胺、苯醚甲环唑、多菌灵、嘧菌酯、嘧菌环胺和异菌脲对半闭弯尾姬蜂成蜂的触杀毒性都较低,LC50值均大于1 000 mg·L-1。安全性评价结果表明,丙森锌和啶菌噁唑对半闭弯尾姬蜂成蜂具有高风险性,安全系数分别为0.16和0.42;嘧霉胺、多抗霉素、氟硅唑和戊唑醇为中等风险性,安全系数分别为1.43、1.56、2.20和3.23;其余6种杀菌剂制剂啶酰菌胺、苯醚甲环唑、多菌灵、嘧菌酯、嘧菌环胺和异菌脲对半闭弯尾姬蜂表现为低风险性,安全系数均大于5。结果显示:甾醇脱甲基抑制剂氟硅唑、戊唑醇和啶菌噁唑以及苯胺基嘧啶类杀菌剂嘧霉胺、有机硫杀菌剂丙森锌和抗菌素多抗霉素对半闭弯尾姬蜂成蜂具有急性毒性风险,在有害生物综合治理中应谨慎使用,特别是啶菌噁唑和丙森锌,以免对半闭弯尾姬蜂造成不良影响和危害。     

The impacts of Robinia pseudoacacia litter cover and roots on soil erosion in the Loess Plateau,China

The impacts of vegetation on soil erosion are closely associated with the combined effects of above- and below-ground components. In this study, we explore the effects and contributions of Robinia pseudoacacia litter cover and roots on soil erosion. Experiment sites under natural conditions with vegetation cover, plant roots and bare ground plots were investigated for overland flow discharges of 0.5, 1.0 and 2.0?L?s^?1 and slope gradients of 8.7%, 17.6%, 26.8%, 36.4% and 46.6%. Results indicate that litter cover and roots have a significant impact on sediment reduction; soil loss was reduced by about 57% and plant roots had a greater impact on the reduction of soil erosion than litter cover. The combination of litter cover and plant roots had a significant effect on decreasing K_r, increasing τ_c and consequently strengthening soil resistance capacity to erosion. When plants and roots existed on the slopes, K_r decreased by 81% and 66%, and τ_c increased by 319% and 246%, respectively, in comparison with bare slopes. These results illustrate the importance of high-forest in controlling soil erosion by quantifying the specific contributions of litter cover and plant roots in erosion reduction in the Loess Plateau.     

新标准下环境空气质量监控网络完善实践 ——以珠三角地区佛山市为例

介绍珠三角及佛山市新标准监测网络结构,从拓宽网络有效覆盖范围、提升网络对污染研究的支撑能力、以及巩固数据实时发布工作基础等多角度分析了网络完善需求,提出了下一阶段网络建设的重点措施建议,并介绍了佛山市目前计划进行的网络完善工作。