室内时变流场中多机器人源定位方法实验与数值验证

为了快速和准确定位室内时变流场中的污染源,提出了一种综合的多机器人源定位方法(URPSO),并综合利用机器人实验和数值实验来验证该方法的有效性.首先,在风扇左右周期性摆动的实验环境中,利用3台机器人开展了15组独立性实验,其中14组实验成功定位源,成功率达到93.3％,说明URPSO方法在室内时变流场中具有强鲁棒性.其...     

地下油罐泄漏区污染源的自动识别

地下油罐泄漏隐蔽性大,不易被及时发现,而且泄漏出的烃类化合物毒性强,对地下水会造成严重污染.为了对某一地下油罐污染源位置和强度进行准确识别,本研究结合现场调查结果,建立了该地下油罐泄漏区的石油污染物反应运移模型.在基本确定污染源泄漏区范围的前提下,进一步建立地下油罐泄漏区污染源的识别模型,并利用遗传算法对泄漏区污染源的位置和泄漏强度进行了自动识别,进而通过参数敏感性分析来评价和比较不同参数对污染物运移结果的影响.结果表明,运移模型中与地下水流场变化相关的特征参数（如开采量、水力坡度、渗透系数等）对污染物运移结果的影响相对比较明显.对于污染源来说,研究不同污染组分在含水层中的化学和生物化学变化显得尤为重要.     

基于U-D分解卡尔曼滤波地下水污染源溯源辨识

采用基于U-D分解的卡尔曼滤波与非线性规划优化模型相结合,溯源辨识出地下水污染源的个数、位置与释放强度.基于一个假想例子,建立地下水污染质数值模拟模型,运用灵敏度分析筛选出对模型影响较大的参数作为模型中的随机变量.然后,应用基于U-D分解的卡尔曼滤波辨识出污染源的个数与位置.在此基础上建立辨识污染源释放强度的优化模型,应用克里格插值法建立地下水污染质运移数值模拟模型的替代模型,代替模拟模型,作为约束条件嵌入优化模型中,运用遗传算法求解优化模型辨识出地下水污染源源强.结果表明：采用基于U-D分解的卡尔曼滤波方法能够保证滤波的稳定性,有效识别出污染源的个数和位置;非线性规划优化模型,可以辨识出污染源释放强度.在优化模型的求解过程中,应用克里格方法建立模拟模型的替代模型嵌入优化模型,能在保证一定精度的情况下,大幅度减少计算负荷和计算时间.     

污染源位置对气体污染物影响的数值模拟

在自然通风、置换通风和单侧送侧回式通风3种方式下,通过改变污染源位置,运用CFD软件模拟研究了办公室内苯污染物的浓度分布规律,比较得出最佳通风方式下的最合理污染源位置。结果表明,3种通风方式下污染源放置的最合理位置是点3;苯污染源处于位置3时,3种通风方式中自然通风各平面苯污染物平均浓度普遍相对最高,而单侧送侧回方式的相对最低,置换通风居于二者之间。最终确定单侧送侧回通风方式下污染源处于位置3时为最佳物理模型,在该模型下办公室内通风效果最好,能够有效地排出室内气体污染物。因此,不同污染源位置对办公室内空气品质的影响不同。     

基于SSA-BP与SSA的地下水污染源反演识别

应用基于SSA-BP神经网络替代模型的模拟-优化方法和SSA研究了地下水污染源位置及释放历史的反演识别问题。并在建立地下水水流模型时,应用Cholesky分解方法建立含水层渗透系数连续场,该方法相比于普通的参数分区方法更好地描述了水文地质参数的非均质性。结果表明:SSA-BP神经网络替代模型对模拟模型具有较高的逼近精度,其平均相对误差仅有3.21%。应用SSA求解优化模型,能够快速准确地识别出点污染源的位置及释放历史。SSA对污染源位置的反演识别相对误差在10%左右,对污染源源强的反演识别相对误差不超过4%。因此,本文所提出的方法是一种有效的地下水污染源识别方法,可为污染责任认定及污染修复方案的优化提供参考。     

室外空气污染对室内空气质量的影响研究

利用数值模拟方法,研究了单个建筑物外存在点污染源时室外空气污染对室内空气质量的影响.首先利用点污染源时单个建筑物周围污染物扩散的风洞实验验证了计算模型和方法的正确性,再利用自然通风的风洞实验,计算了不同污染源位置和建筑物进风口时的室内外速度场和污染物浓度场.结果表明:速度场的计算结果与风洞实验结果基本吻合,无量纲通风量的计算值略小于实验值;建筑物迎风面回流区上方的气流进入室内;当点污染源位于建筑物前的距离和建筑物高度之比约等于1时,污染源在地面处的室内污染物浓度要小于源在建筑物高度一半处的;建筑物进风口的挡风板对室内污染物浓度的影响不大;根据壁面上污染物浓度的分布来改变进风口位置,是减少室内空气受室外污染影响的有效方法.      

民用建筑室内颗粒物源释放研究综述

该文简要分析了室内颗粒物浓度的主要影响因素,归纳总结了室内颗粒源释放速率的主要计算方法,从颗粒物释放速率和粒径分布两方面详述了室内各类颗粒物源包括燃烧类、烹饪类、再悬浮类和其它类源的颗粒释放特征,同时分析了各类颗粒源释放率的影响因素。对民用建筑颗粒物污染源释放机理、规律特性的全面理解和把握,有助于从源头出发减少室内颗粒污染及人员暴露危害。     

基于Elman神经网络的流体管道泄漏点检测定位

目的通过Elman神经网络预测对泄漏点进行过检测定位。方法基于流体压力波的负压波法及反馈型Elman神经网络方法,开展水力输运管道的泄漏定位研究。利用Flowmaster仿真软件中的水力输运模型建立长度为1100 m的一维管路系统,针对此系统开展不同管路状态参数下的数值仿真计算。结果通过小波变换技术实现了数据降噪与奇异点捕捉,完成了泄漏点位置的估算。同时,借助反馈型Elman神经网络,开展了不同泄漏工况下的网络训练和预测,利用经过训练的神经网络对所选取的5组泄漏点完成了定位预测,最大测试误差为1.83%。结论通过Elman神经网络预测得到的结果与实际泄漏位置进行对比,验证了反馈型神经网络方法在管路泄漏智能定位问题中的准确性与有效性。     

建筑室内人员污染暴露量及其特征性分析

合理确定室内人员的污染暴露量是有效改善室内空气品质的重要前提。文章结合吸入率概念和人体呼吸模型给出了室内人员污染暴露量计算模型,并以二氧化碳指标和挥发性有机化合物指标为研究对象,分析了在不同通风模式、新风量大小和污染源强度下室内人员污染暴露量的特性。研究结果表明,置换通风条件下的人员污染暴露量要低于混合通风条件下的相应结果,且在置换通风条件下站姿的污染暴露量要高于坐姿的对应结果,而在混合通风条件下情况相反;同时,新风量增大可以降低人员污染暴露量,但其有效程度存在临界点,即存在最优的新风量大小;此外,人员污染暴露量会因污染源强度的提高而增大,但其随污染源强度变化的跟随性会由于通风模式的不同而存在显著差异。     

室内甲醛污染和分析

甲醛是室内环境的主要污染物.采用乙酰丙酮分光光度测定方法,通过对一幢五层新建的办公楼随机抽取六间房,每隔3个月分别进行了检测,结果表明室内温度变化对甲醛的释放有较大影响,甲醛的释放随时间逐渐减少.列举了脲醛树脂、酚酞树脂、胺基甲醛树脂等是造成室内甲醛污染的主要来源,甲醛对人体的危害极大,不同国际组织、国家对室内甲醛浓度制定了不同的最高限值.从控制污染源、控制室内条件、处理方法等方面将有效防治室内甲醛污染.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.