Distribution normality of pH and H<Superscript>+</Superscript> activity in soil

Soil pH, a log-transformed form of hydrogen ion (H⁺) activity, is often used for various statistics. However whether soil pH meets the requirement of distribution normality for statistical analyses is unknown. We studied the statistical suitability of both soil pH and H⁺ activity by examining their distribution normalities. Results show that the variability of H⁺ activity is higher and its distribution is skewer, which is significantly different from the normal and soil pH, regardless of soil conditions and analytical methods. Here we demonstrate that soil pH is more appropriate than the H⁺ activity for performing statistical analysis in terms of distribution normality.     

邻苯二甲酸二丁酯对大型蚤(Daphnia magna)的毒性作用研究

本研究选用大型蚤(Daphnia magna)作为实验生物,研究了邻苯二甲酸二丁酯(DBP)对其急性毒性作用和慢性毒性作用,同时还研究了环境因素(温度、硬度、腐殖酸)对DBP24h-EC(50)的影响.结果表明DBP对大型蚤的24h-EC_(50)为10.35mg·1~(-1),温度、硬度和腐殖酸对DBP24h-EC_(50)均有一定影响.DBP对大型蚤的捕食行为产生抑制,EC_(50)在 6—7mg·1~(-1)之间.慢性毒性实验结果表明DBP对大型蚤的生长繁殖产生一定影响,低浓度DBP对大型蚤生长繁殖有一定的刺激作用,高浓度DBP对大型蚤生长繁殖存在抑制作用,BDP的最大允许安全浓度为1—2mg·1~(-1).     

Effects of Population Size, Mating System, and Evolutionary Origin on Genetic Diversity in Spiranthes sinensis and S. hongkongensis

Hong Kong once supported more than 109 species of wild orchids, of which approximately 30% were endemic. Most of the local wild orchids have now become rare or endangered. I conducted a comparative study of genetic diversity in two closely related terrestrial orchids, an allotetraploid, Spiranthes hongkongensis , and its diploid progenitor, S. sinensis , to assess the effects of the population bottleneck associated with the origin of the polyploid and to investigate the relationships between number of breeding individuals, mating system, and level of isozyme variation in their populations. Nearly complete genetic uniformity was observed both within and among populations of S. hongkongensis . In contrast, S. sinensis had high levels of genetic variation for all of the genetic parameters examined. Regression analysis of population size and several components of genetic diversity in S. sinensis revealed that, among various measures of within-population variation, the proportion of polymorphic loci ( P ) and average number of alleles per locus ( A ) or per polymorphic locus ( A _p ) were the most sensitive to population size ( R ² = 0.942, p = 0.001; R ² = 0.932, p = 0.002; and R ² = 0.923, p = 0.002 respectively). The highly negative correlation ( r = −0.999, p < 0.01) between population size and the mean frequency of private alleles in pairwise population comparisons, p (1), indicated that population size may also be used to predict the extent of population differentiation caused by random genetic drift. Conservation of genetic diversity in S. sinensis could be maximized by protecting several of both large and small populations, whereas fewer populations may be needed to achieve this goal for S. hongkongensis.     

Degradation of 4-aminophenol by hydrogen peroxide oxidation using enzyme from Serratia marcescens as catalyst

This paper reports on the degradation of 4-aminophenol using hydrogen peroxide as oxidizer and the enzyme from Serratia marcescens AB 90027 as catalyst. The effecting factors during degradation and the degrading mechanism were studied. Also, the location of the enzyme in the cell, which could catalyze the degradation of 4-aminophenol, was analyzed. The results showed that to degrade 50 mL of 4-aminophenol whose concentration was 500 mg/L, the optimal conditions were: volume of H₂O₂ = 3 mL, temperature = 40–60°C and pH = 9–10. In the degradation process, 4-aminophenol was first converted to benzoquinone and NH₃, then organic acids including maleic acid, fumaleic acid, and oxalic acid were formed, and then finally CO₂ and H₂O were generated as final products. The enzyme that could catalyze the degradation of 4-aminophenol was mainly extracellular enzyme.     

广州市城市森林的空间特征与发展研究

应用城市林业的基本理论和ＧＩＳ技术，广州市城区森林的空间分布以两山（白云山、越秀山）两河（珠江、流溪河）为核心，辅之公共绿地和道路绿化，形成多功能、多类型的网络式结构。近郊森林建设好风暴旅游林以及环绕卫星城镇和重点工业镇的生态公益林。远郊森林保障了“菜蓝子”工程，促进森林旅游及其相关产业的发展。     

多目标优化方法在城市污水厂汇水区污染源总量控制规划中的应用

在城市污水处理厂汇水区实行污染源总量控制,应该避免与城市污水处理厂重复治理.针对这个问题,提出难降解有机物控制的多目标准则指标,建立了多目标优化模型.     

电石遇潮湿空气易燃危险性的评估方法及预防措施研究

针对电石遇潮湿空气释放乙炔的危险特性,以潮湿空气与电石粉尘及电石粉尘堆垛表面接触的方式,替代传统的遇湿易燃危险性测试方法,拟合得到了乙炔气体释放速率随潮湿空气相对湿度变化的方程式,提出了将乙炔气体浓度控制在低于发生火灾爆炸危险区域的潮湿空气相对湿度和稀释乙炔气体浓度的氮气保护进气流量(Q)计算公式。结果表明:电石遇潮湿空气释放乙炔气体的浓度受温度和相对湿度的影响,根据不同温度条件下潮湿空气中水汽的分压(Ps)和乙炔气体的密度(ρ乙炔),可计算得到一定气相空间内电石遇潮湿空气释放乙炔气体的浓度;潮湿空气的相对湿度可以有效表征乙炔气体的释放量,用于评估在一定气相空间内电石遇潮湿空气释放乙炔气体发生火灾爆炸的可能性。     

老秃顶子植物分带与中山地区植物特点

于2006年-2007年分春、夏、秋、冬4次对辽宁省老秃顶子国家级自然保护区内的植物分带进行了考察。结果表明：该区系成分复杂，有5个植被型组，包含有东亚-北美成分、北温带成分、温带亚洲成分、旧大陆温带成分等多个分布区类型，根据上述复杂情况，提出了具体的老秃顶子生态保护对策。     

大气污染预测预报研究

以排放到大气环境中的烟尘为例，进行大气污染预测预报，并利用保证率的概念表示预测的结果，为大气污染的预测预报工作提供了一种基本方法。     

溧阳两次中强震的灾情与相关异常

本文对1974年4月22日和1979年7月9日在江南水乡溧阳先后发生的两次中强地震的灾情进行回顾以及地方地震部门在抗震救灾中应发挥的作用进行总结,同时,对这两次中强震前的相关异常进行分析,这样可为我们今后的地震预报提供参考,也可为我们以后的抗震设防和抗震救灾提供借鉴。