纳氏试剂比色法测定氨氮的问题及修正

预蒸馏—纳氏试剂比色法测定污水中氨氮实验中,硼酸与氢氧化钠用量影响有色胶体的稳定和测定的灵敏度,本文研究了影响规律,发现氢氧化钠有增敏作用,提出工作曲线应使用经过校正的标准曲线,校正曲线绘制及水样分析时,采用溶液中Ｈ３ＢＯ３含量为０．４％、ＭａＯＨ含量为０．２ｍｏｌ／Ｌ显色溶液胶体稳定时间长达１２小时以上,线性范围扩展为０～９ｍｇ／ｉ,最低检出浓度为０．０１５ｍｇ／ｌ     

模拟黑水的生物处理

针对以糖蜜配制的半人工黑水生物处理时除磷效率下降和污泥膨胀的现象,利用序批式反应器(SBR)进行了实验分析,比较了以蔗糖和糖蜜为主要碳源时除磷效果的差异,并探讨了污泥膨胀发生的原因。研究表明,以糖蜜为主要碳源配制模拟黑水时的除磷效果比蔗糖为碳源时差,主要是由于GAOs的竞争性代谢所致。以糖蜜为碳源的条件下,污泥的胞外聚合物含量是正常活性污泥的一倍以上,导致污泥沉降性能变差;糖蜜碳源时的夏季高温条件下丝状菌大量生长也是导致污泥膨胀的重要原因。     

Influence of hydroxypropylcyclodextrins on the toxicity of mixtures

We studied the influence of hydroxypropylcyclodextrins (HPCDs) on the toxicity of some mixtures. Using the Photobacterium phosphoreum toxicity test, the joint toxicological effect for Mixture I (containing p-nitrobenzaldehyde and 1-nitronaphthalene) and Mixture II (containing p-nitrobenzaldehyde and malononitrile) were determined in water and in aqueous solutions of HPCDs. The results indicate that, although the toxicological joint effect for Mixture I (simple addition) differs from that of Mixture II (synergism), alpha- and beta-HPCD can significantly reduce the toxicity of the test compounds, whereas gamma-HPCD has only a slight effect. Explanations for these observations are given that invoke the molecular structure of the individual chemicals as well as the structures of HPCDs. This provides information to assist the application of HPCDs in remediation of environmental pollution.     

Role of surface functionality in the adsorption of anionic dyes on modified polymeric sorbents

While synthetic polymeric sorbents effectively treat dye wastewaters by adsorption, the underlying mechanisms remain to be understood. This work determined the adsorption of an anionic dye by three polymers differing significantly in surface functionality. Surface functional groups of polymers were indicated in FTIR spectra and quantified by the Boehm titration. In reference to the commercial sorbent XAD-4 with a low degree of functionality, the laboratory synthesized NG-8 had primarily acidic functional groups, whereas its aminated product MN-8 had mainly basic amino groups. Electrophoresis determined the points of zero charge of 4.18, 3.23, and 4.51 for XAD-4, NG-8, and MN-8, respectively. The adsorption of Reactive Black 5 dye (RB5) by all the sorbents on a unit surface area basis increased with decreasing pH. At the same low pH (4.40), the adsorption by NG-8 was similar to that by XAD-4, indicating little influence of protonated (neutral) surface functional groups. In contrast, the adsorption by NG-8 at pH 6.05 was 75% lower than that by XAD-4, resulting apparently from the strong electrostatic repulsion between RB5 and deprotonated (negative) groups. Amination substantially enhanced RB5 adsorption by eliminating acidic groups and creating a positive charge on the surface of MN-8. The adsorptive enhancement was also achieved in the presence of CaCl2, due presumably to the neutralization of negative surface charge by Ca2+ and the RB5-Ca2+ pairing. These results manifest the important role of surface functionality in the adsorption of dyes by synthetic polymers.     

五爪金龙凋落叶腐解物的化感潜力研究

采用莴苣种子为受体,测试了五爪金龙凋落叶早期腐解物的化感作用,并与其鲜叶及凋落叶的化感潜力进行了比较分析。结果如下:凋落叶40d的腐解物、鲜叶及凋落叶的水提取液均具有较强的化感潜力,并表现出低促高抑的浓度效应,在FW0.1g﹒mL-1高质量浓度下的综合化感抑制强度为凋落叶未能加土壤的腐解物>鲜叶>凋落叶加土壤的腐解物>凋落叶,而在FW0.005g﹒mL-1低质量浓度下的综合化感促进作用是凋落叶>鲜叶>凋落叶加土壤的腐解物>凋落叶未加土壤的腐解物。鲜叶的抑制强度较凋落叶的大,表明叶片在衰老过程中抑制作用减弱。凋落叶未加土壤仅在空气微生物作用下的腐解物抑制作用最强,促进作用最小,而加入土壤后在土壤微生物作用下的腐解物的抑制作用却有所减弱,抑制强度介于鲜叶和凋落叶的之间,促进作用却小于鲜叶和凋落叶,说明凋落叶腐解过程中微生物的参与对化感作用产生了复杂的影响。     

农村经济活动对云南野生稻居群的影响

云南野生稻包括普通野生稻(O.rufipogon Griff)、疣粒野生稻(O.meyeriana Baill)和药用野生稻(O.officinalis Wall),是属于全国仅存的几处宝贵基因资源库之一。野生稻具有许多优良特性及其相应的基因,在栽培稻育种和生物技术利用等方面具有巨大的潜力。文章在对云南野生稻居群长期调查或考察的基础上,分析了云南野生稻居群濒危的现状,认为热区经济开发、游牧、木材消耗、采集草药、外来种入侵和环境污染等农村经济活动是致濒的主要因素。阐明了选择合理的保护方法、加大普法和执法力度、完善保护体制与运行机制、调整种植结构是当前云南野生稻居群保护管理与经济协调发展的四项重点措施。     

粤北岩溶区的石漠化及其治理对策探讨

粤北岩溶石山地区分布有面积广泛的碳酸盐岩发育多种岩溶地貌。由于该地区的特殊地质、水文、气候等自然因子的影响，其岩溶生态环境脆弱，环境容量低，敏感度高，抗干扰能力弱。在不合理的人类活动和自然因素作用下，易引发出一系列的生态问题。岩溶生态环境开始恶化，植被走向逆向演替等，最后出现大面积的石山，发生石演化观象。     

污水处理设施建设与运营模式浅析

详细介绍了国外污水处理设施建设与运营的管理经验,分析了英国、美国、法国和荷兰等典型管理模式的特点,阐述了中国污水处理事业的发展历程,调研了目前国内并存的事业体制、企业化管理、委托运营、DBO（设计-建设-运营）、特许经营、股权转让、合资合作、完全私有化、用户和社区资助等模式并逐一进行分析,指出了中国污水处理设施建设与运营的发展方向,认为应尽量慎重考虑涉及产权的特许经营模式,着力推广DBO模式。     

民主：环境保护的政治基础

通过对全球100多个国家的环境指数比较研究发现,环境保护与民主水平之间的相关性存在统计学的显著性。民主水平无一例外地和5个不同环境评价指标之间的相关性具有明显的统计学显著性。这表明,民主水平的提高有助于促进环境治理、环境可持续发展,有利于降低人们对环境的破坏。为此,解决环境问题需要进行相应的政治体制改革,为环境可持续发展扫除政治方面的障碍。