如何提高分光光度分析的准确度

分光光度测定中,从采样、预处理、溶液配制与稀释、回归方程制作、数据计算等各个环节,都要考虑有效数字的位数是否满足要求,其对分析结果准确度有举足轻重的影响;最大吸收波长的扫描、溶液稀释方式、仪器空白值的扣除等操作环节对分析结果也会产生重要影响。     

Parental care of replacement clutches in common terns (Sterna hirundo)

In long-lived seabirds with low annual reproductive output, the renesting decision after breeding failure is critical, and the parents have to weigh benefits of replacement clutches against possible future reproductive costs. In this study, we investigated factors influencing renesting decisions in common terns (Sterna hirundo) and compared aspects of breeding biology and body mass between two breeding attempts by the same pairs in each of 4 years of heavy losses due to predation. Renesting birds were characterized by early laying dates and by a high age. Among early breeders, high egg mass reduced the probability of renesting. A long relaying interval coincided with low mass of replacement eggs in one year, and short intervals with high egg mass in another. Further, egg mass decreased and relaying intervals increased the later the predation events occurred. Evidence of high levels of parental care of replacement clutches came from body mass data: female mass increase prior to egg laying was higher in the second attempt than in the first, whereas male mass was lower during the second courtship period than during the first. Male mass also affected relaying intervals and mass of replacement eggs. We conclude that common terns expend high levels of parental care of replacement clutches. Intrinsic factors related to individual quality (age, body condition) seemed most important for renesting decisions and for the degree of parental care, but foraging conditions seemed to have modifying effects. Received: 13 August 1999 / Received in revised form: 5 February 2000 / Accepted: 13 March 2000     

电动力学技术去除剩余污泥中铜、锌条件优化

电动力学去除剩余污泥中重金属受到多种因素的影响,其中电解电压、电极面积、电极材料等都有较大的影响,很有必要进行条件优化研究。针对存在的问题,系统的研究了电解电压、电极面积、电极材料对电动力学修复过程的影响。研究表明,影响污泥中重金属Cu和Zn去除率的因素大小顺序为:电压电极面积电极材料;采用等于或低于氢析出电压进行电动力学修复时,更有利于提高污泥中重金属去除率;增大电极面积,提高了电流强度,有利于污泥中重金属的转化、迁移,从而提高污泥中重金属去除率;研究表明,采用低于氢析出电压和惰性电极可以有效避免电极被腐蚀。     

Metolachlor persistence in laboratory and field soils under Indian tropical conditions

Abstract

Metolachlor [2‐chloro‐N‐(2‐methoxy‐1‐methylethyl)‐2'‐ethyl‐6'‐methyl acetanilide] dissipation under both field and laboratory conditions were studied during summer season in an Indian soil. Metolachlor was found to have moderate persistence with a half‐life of 27 days in field. The herbicide got leached down to 15–30 cm soil layer and residues were found up to harvest day of the sunflower crop in both 0–15 cm and 15–30 cm soil layers. Metolachlor was found to be more persistent in laboratory studies conducted for 190 days. The rate of degradation was faster in soil under flooded partial anaerobic conditions as compared to aerobic soil with a half‐life of 44.3 days. In aerobic soil, metolachlor was very stable with only 49% dissipation in 130 days. Residues remained in both the soils up to the end of the experimental period of 190 days.     

热解条件对废旧电路板真空热解油的成分的影响

采用GC/MS检测,研究最终温度(400、500和600℃)和升温速率(5、10和15℃/min)对废旧电路板真空热解油的成分的影响。研究表明,最终温度过高(600℃)、升温速率较小(5℃/min)或较大(15℃/min)都不利于热解油的形成,反而增大不凝气的产量。升高最终温度会增强较低碳数物质的热解效果,产生更多的不凝气;但同时也会限制较高碳数物质的热解,出现较多的环化、聚合反应生成结构复杂的物质。升温速率较高(15℃/min),会产生大量不饱和物质,其在后续发生环化、聚合等反应,生成更多的C14~C18,C6~C9含量则大幅下降。从热解油产量和GC/MS检测结果看,升温速率为10℃/min、最终温度为500℃和恒温1 h,热解充分,热解油C6~C9含量高,有较高的综合利用价值。     

深水环境试验技术综述

系统总结了深水环境模拟试验装备的发展历程以及国内外发展状况,介绍了深水环境模拟的2个关键技术——压力和温度环境模拟技术、测试技术与结构状态评估方法.对深水环境模拟试验技术的工程应用进行了归纳和总结,对深水环境模拟试验技术的改进方向和发展趋势进行了展望.     

立地条件对麻栎人工林碳储量的影响

在江淮山地丘陵区,通过样地调查,研究了坡向和w对麻栎（Quercusacutisima）人工林系统碳密度及其空间分布的影响。结果表明：阴坡（SHS）树木碳密度显著高于阳坡（sus）（P〈0．05）,Wt镕i《1低的立地（sus）树木碳密度显著高于w、高的（suss）（P〈0．05）。3种立地条件下麻栎各器官碳密度分配均为：干碳密度〉根碳密度〉枝碳密度〉叶碳密度。SUS和SHS林木分配较多的碳同化物供给树干生长,SUSS林木分配较多的碳同化物供给根系和枝的生长。凋落物碳密度在SUS和SHS之间没有显著差异（P〉0．05）,而SUSS则显著低于SUS和SHS（JPl〈0．05）。整个剖面（0～50cm）土壤有机碳密度SHS显著高于SUS和SUSS（P〈O．05）,SUS和SUSS之间没有显著差异（P〉0．05）。麻栎人工林系统总碳密度大小为SHS（146．9t·hm^2。）〉SUS（116．9t·hm^-2）〉SUSS（102．6t·hm^-2）,SHS显著高于其他2种立地条件（P〈0．05）,SUS与SUSS之间没有显著差异（P〉0．05）。3种立地条件下均为土壤碳密度〉树木碳密度〉凋落物碳密度,凋落物碳密度占林分总碳密度的比例仅为2．1％～3．6％。SUS和SHS土壤碳密度占林分总碳密度的比例低于SUSS,而树木碳密度占林分总碳密度比例则相反。由此可见,在江淮山丘区,w较低的阴坡（SHS）最有利于麻栎人工林碳储量的累积,相对于w、较高的立地（suss）,较低的Wf±镕6砾1（sus）更有利于树木碳储量的增加。     

氯化钠和二氧化硅对过硫酸铵热稳定性的影响

采用绝热加速量热仪（ARC）对分析纯过硫酸铵、含10%氯化钠杂质的过硫酸铵以及含10%二氧化硅杂质的过硫酸铵进行热分析实验,得到了实验过程中温度、温升速率和压力等数据,计算了3组样品的反应动力学参数,引入热惰性因子对实验数据进行修正,得到了3组样品在严格绝热条件下的热危险性参数,分析了3组样品的反应过程和热危险性。通过Semenov理论计算了3组样品的自加速分解温度（SADT）。结果表明,过硫酸铵加入氯化钠或二氧化硅杂质后,热危险性增大,自加速分解温度降低,更容易发生反应且反应更剧烈。     

2009年8~9月成都市颗粒物污染及其与气象条件的关系

对成都市3个不同点位PM2.5和PM10进行了为期30d的连续观测,研究了大气颗粒物浓度的时空分布特征,及其与气象条件的关系.研究表明,观测期间成都市大气颗粒物PM2.5和PM10质量浓度日均值分别为66,94μg/m3,两者浓度变化范围较大,但变化趋势相同.从空间分布来看,大气颗粒物浓度均是熊猫基地>草堂寺>丽都花园,即下风向污染状况最严重,商业繁华地段次之,生活居住区最好;从时间分布来看,大气颗粒物污染最严重出现在9月17~19日,9月5~9日2个时间段,不利的气象因素和污染物的累积是造成该时间段大气颗粒物污染加重的主要原因.PM2.5与PM10质量浓度的相关性为0.93,PM2.5对PM10的贡献较大,两者质量浓度的比值达0.69.气温对大气颗粒物浓度变化没有显著影响;降水以及风速对颗粒物浓度影响较大,主要是对颗粒物的湿清除和促进扩散作用;在一定相对湿度范围内,高湿度条件容易造成大气颗粒物的较重污染.能见度与大气颗粒物浓度呈明显负相关性,且与PM2.5的相关系数大于与PM10的相关系数.     

江苏省一次重霾污染天气的特征和机理分析

利用PM10, SO2,O3,NH3, NOx,CO等6种大气成分浓度数据、常规气象观测数据和天气图资料,结合HYSPLIT4后向轨迹模式,对2008年10月28~30日发生在江苏省的一次大面积重霾污染天气的特征和成因进行了综合分析.结果表明,此次重霾污染天气过程观测到的PM10, NOx,CO最大地面浓度分别达到0.553, 0.170, 2.738mg/m3,水平能见度达到1km以下.其中城市中CO和NOx浓度较郊区高,而SO2和O3则较低.该污染事件与大范围秋收秸秆集中燃烧,造成大量污染物排放有密切关系.平稳的高空环流形势、暖平流、地面高压场分布为重霾污染天气的发生、发展提供了有利的气象条件,地面表现为稳定的大气层结、静小风和低湿环境,非常不利于污染物的扩散.后向轨迹计算分析表明,造成此次重霾污染天气的气团主要来自河南中东部、苏北和安徽等重要产粮地区,长距离输送对区域霾污染产生重要影响.