Present status and changes of the phytoplankton community after invasion of Neosalanx taihuensis since 1982 in a deep oligotrophic plateau lake, Lake Fuxian in the subtropical China

Phytoplankton assemblages in the subtrophical oligotrophic Lake Fuxian, the second deepest lake in China, were investigated monthly from September 2002 to August 2003. A total of 113 species belonging to seven phyla were identified, among them, a filamentous green alga, Mougeotia sp., dominated almost throughout the study period and comprised most of the total phytoplankton biomass.Mougeotia sp. has made a substantial development during the past decades: it was absent in 1957, only occasionally present in 1983,increased substantially in 1993, and became predominant in 2002--2003. It is likely that natural invasion of the Taihu Lake noodlefish (Neosalanx taihuensis) has led to a change of dominant herbivorous zooplankton from small to large calanoid, which has increased grazing pressure on small edible algae, and thus has indirectly favored the development of the inedible filamentous Mougeotia sp.     

室内空气中甲醛和苯系物检测与净化

通过对哈尔滨市装饰装修竣工一年内的60户室内空气污染物检测分析,结果表明:室内空气甲醛超标64.1%,苯超标54.1%,甲苯超标35.6%,二甲苯超标30.6%.采用臭氧法,光催化氧化法和药剂法三种方法对室内空气污染物甲醛和苯进行净化效果实验研究,评价其净化效果,比较了三种方法的优劣.     

甲烷高温自燃诱导过程实验与数值模拟研究

甲烷的转化在化工产业中具有举足轻重的地位与战略意义,近年来涌现的氧化偶联制烯烃等多种新型化工工艺涉及高温条件的甲烷-纯氧等体系的混合与反应过程,明确甲烷高温自燃诱导与爆炸规律是实现工艺安全设计与运行的前提,然而相关研究与基础数据仍较为欠缺。通过利用基于快速压缩装置的高温高压燃爆测试系统开展甲烷-纯氧等典型混合体系的自燃诱导过程研究,同时基于GRI-Mech 3.0机理的数值模拟方法进行了数值模拟研究。实验结果与数值模拟结果吻合较好,随着温度/压力的增加及氧气含量的下降,混合体系自燃诱导时间均缩短;燃料气中加入乙烷或氢气则会大幅缩短自燃诱导过程。对于多个工艺过程中涉及的低氧含量体系率先开展了研究,得到了不同当量比及温度条件下的典型体系自燃诱导时间,同时考察了惰性气的加入对于自燃诱导过程的延长作用。研究结果有助于深入理解甲烷自燃诱导机理,同时指导高温条件的甲烷转化工艺的本质安全化设计与爆炸防控。     

利用PCR-DGGE技术分析生物陶粒硝化反应器中微生物群落动态

为了揭示生物陶粒硝化反应器中活性污泥的微生物种群多样性,从运行不同时期的反应器中提取活性污泥,利用PCR-DGGE技术初步分析了生物陶粒反应器细菌的种群演替情况.结果表明,随着进水COD值的逐阶段降低,氨氮去除率逐步提高到64.38%.群落结构和优势种群的数量具有时序动态性,微生物多样性与废水的处理效果出现协同变化的特征.测序结果表明,生物陶粒反应器中运行第21天的优势种群除了自养细菌,还有异养细菌存在.其中自养细菌为Nitrosospira.sp和Nitrobacter.sp,异养细菌为Bacillus.sp、Pseudomonas.sp和Pseudochrobactrum.sp.     

镧、铈对厌氧颗粒污泥产甲烷的Hormesis效应及其动力学研究

间歇培养条件下研究了单一稀土元素镧(La3 )和铈(Ce3 )在不同浓度水平下对厌氧颗粒污泥活性及其动力学行为的影响.结果表明,La3 和Ce3 对厌氧颗粒污泥比产甲烷活性有促进作用的浓度范围均为0.01～0.1 mg·L-1,促进作用浓度峰值均为0.05mg·L-1,最大促进百分比分别为10.35%和20.79%;La3 和Ce3 对SMA(比甲烷活性)的半抑制浓度分别为5mg·L-1和1000mg·L-1,La3 较易对污泥产生抑制作用.米-门方程可以用来描述厌氧消化过程中甲烷发酵阶段的动力学行为,稀土元素La3 和Ce3 投加至反应系统后,提高了甲烷发酵过程的动力学常数Vmax和半饱和常数Ks.     

全国土壤侵蚀量估算及其在吸附态氮磷流失量匡算中的应用

应用土壤流失方程(USLE),根据我国土壤水力侵蚀分类分级标准,建立了大尺度区域土壤侵蚀量的估算模型;基于GIS技术平台,利用土壤普查数据,构建了全国表层土壤氮磷含量数据库,完成了2000年全国境内水土流失影响下吸附态氮磷的流失量估算.经数据合理性分析验证后得出以下结论:(1)全国因水土流失引发的吸附态氮素和磷素的流失总量分别达到104.22×104t和34.65×104t;(2)长江、珠江和黄河三大流域的吸附态氮、磷流失量之和分别占全国总量的83%和89%,单位面积(1km2)吸附态氮、磷的流失量分别介于6.0×10-4～0.53t和2.1×10-4～0.13t之间;(3)吸附态氮的重点流失区主要分布在长江中上游水土易蚀区、黄河中游沟壑区、西辽河上游区、珠江流域红水河、西江等上游区以及怒江、澜沧江下游区.     

MAGIC模型及其应用进展

介绍MAGIC模型及其在预测土壤和地表水酸化趋势及确定酸沉降临界负荷中的应用,提出了该模型的应用展望。     

电催化氧化技术处理硝基苯废水的试验研究

用实验室自制的活性炭粒子填充电极电催化氧化反应器对模拟硝基苯废水进行了降解处理。初步探讨电催化氧化反应的机理,考察了电流强度、反应时间、进水浓度等对硝基苯去除率的影响。用一元线性回归方程对不同初始浓度和电流强度降解后硝基苯的相对残余浓度对反应时间的相关性进行了分析,结果发现相关系数大于临界相关系数,硝基苯的降解符合表观一级反应动力学模型,求出了各反应条件下的一级速率常数。通过用spss软件分析,表明不同的初始浓度和电流强度下ln(C0/C)对时间的相关性显著。实验结果表明,在本实验条件下,硝基苯的去除率达到95%以上,能有效的催化降解硝基苯。     

听抄在大学英语教学中的意义

针对目前很多大学生英语综合能力尤其是听说水平偏低的现状，本文阐述了运用听抄来提高英语能力的方法。全文分四个部分：什么是听抄…在听录音的同时抄下录音文稿的过程；如何进行听抄……反复听，直到抄出为止；听抄的作用……对英语综合能力的提高有积极效果；及需注意的问题。     

Effects of acid,acid-ZVI/PMS,Fe(Ⅱ)/PMS and ZVI/PMS conditioning on the wastewater activated sludge(WAS)dewaterability and extracellular polymeric substances(EPS)

The effects of four conditioning approaches:Acid,Acid-zero-valent iron(ZVI)/peroxydisulfate(PMS),Fe(Ⅱ)/PMS and ZVI/PMS,on wastewater activated sludge(WAS) dewatering and organics distribution in supernatant and extracellular polymeric substances(EPS) layers were investigated.The highest reduction in bound water and the most WAS destruction was achieved by Acid-ZVI/PMS,and the optimum conditions were pH 3,ZVI dosage 0.15 g/g dry solid(DS),oxone dosage 0.07 g/g DS and reaction time 10.6 min with the reductions in capillary suction time(CST) and water content(Wc) as 19.67% and 8.49%,respectively.Four conditioning approaches could result in TOC increase in EPS layers and supernatant,and protein(PN) content in tightly bound EPS(TB-EPS).After conditioning,organics in EPS layers could migrate to supernatant.Polysaccharide(PS) was easier to migrate to supernatant than PN.In addition,Acid,Acid-ZVI/PMS or Fe(Ⅱ)/PMS conditioning promoted the release of some polysaccharides containing ring vibrations v P=O,v C-O-C,v C-O-P functional groups from TB-EPS.ESR spectra proved that both radicals of SO_4~-· and·OH contributed to dewatering and organics transformation and migration.CST value of WAS positively correlated with the ratios of PN/PS in LB-EPS and total EPS,while it negatively correlated with TOC,PN content and PS content in TB-EPS,as well as PS content in supernatant and LB-EPS.BWC negatively correlated to zeta potential and TOC value,PN content,and HA content in supernatant.