污水生物脱氮过程中N_2O的释放途径和影响因素

为了更好地理解和掌握污水处理过程中N 2O的释放规律,结合近年来已经发表的研究结果,就传统的污水生物脱氮过程(全程硝化反硝化过程)和新型污水生物脱氮过程(同步硝化反硝化、短程硝化反硝化和厌氧氨氧化)中N2O的释放途径以及影响因素进行了综述。通过综述发现,硝化和反硝化过程均有可能导致N2O的释放,且硝化过程更易产生N2O;与传统的脱氮过程相比,同步硝化反硝化等新型脱氮过程产生N2O的概率更大;影响N2O释放的因素主要有DO浓度、NO-2浓度、进水氨氮负荷、SRT和COD/N等运行工况和细菌种类及其活性。最后,展望了该领域的研究方向。     

天津台网噪声影响下实际监测能力及优化布局

本文针对天津台网所有台站,抽取一天24个小时的波形资料,通过计算得到各台站的噪声水平。在台网监测能力计算中加入相应噪声水平,从而得到噪声影响下的台网的监测能力为天津市区ml1.0,东部沿海监测能力为ml2.0,北部山区监测能力为ml2.3。即是台网的实际运行、工作中的监测能力。     

含铬浸出渣调质解毒规律研究

为了研究含铬浸出渣的调质解毒机理,建立了CaO-MgO-FeO-Na2O-SiO2-Al2O3-Cr2O3七元渣系活度模型,基于共存理论的活度模型得出了铬渣中主要组分及复合氧化物在不同条件下的活度。所得的结果表明,铬渣中Cr2O3主要形成了Na2Cr2O4和CaCr2O4,这两种复合氧化物不稳定,在自然环境中分别会被氧化为水溶性的铬酸钠(Na2CrO4)和酸溶性的铬酸钙(CaCrO4),释放出具有强毒性的Cr(Ⅵ),是造成铬污染的主要原因。温度、碱度以及渣中FeO含量都能影响渣系组分的活度。在1700K下,将铬渣碱度调至1.14,并加入30%的FeO能够使Cr2O3的有效固定率提高至88.2%,基本实现了铬渣的解毒。     

Application of hinokitiol potassium salt for wood preservative

The decay of wood and other cellulosic materials by fungi cause significant economic loss. The widely used chromated copper arsenate was prohibited for the environmental impact and safety of arsenic and chromium. It was found that natural product hinokitiol (HK) had fungicidal and insecticidal activities, and its toxicity was bearable for the environment. We described the practical synthesis of HK-K salt. According to the GB/T18261-2000 and LY/T1283-1998, wood preservative performance of HK-K salt was tested. The results showed that the best inhibitory concentration of HK-K salt was 50 mg/L, for which the prevention effectiveness on mold is better, the killed value is between 0 and 1, and the corrosion-resistant for wood-rotting fungi is grade A.     

机动车氮氧化物污染现状与减排措施

汽车尾气对空气的污染越来越严重,影响人们的健康生活,破坏生态环境。机动车尾气中的氮氧化物是大气污染的主要污染物之一,采取有效措施减少机动车氮氧化物排放对于空气质量的改善具有重要意义。     

Biogenic volatile organic compound analyses by PTR-TOF-MS: Calibration,humidity effect and reduced electric field dependency

Green leaf volatiles (GLVs) emitted by plants after stress or damage induction are a major part of biogenic volatile organic compounds (BVOCs). Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) is a high-resolution and sensitive technique for in situ GLV analyses, while its performance is dramatically influenced by humidity, electric field, etc. In this study the influence of gas humidity and the effect of reduced field (E/N) were examined in addition to measuring calibration curves for the GLVs. Calibration curves measured for seven of the GLVs in dry air were linear, with sensitivities ranging from 5 to 10 ncps/ppbv (normalized counts per second/parts per billion by volume). The sensitivities for most GLV analyses were found to increase by between 20% and 35% when the humidity of the sample gas was raised from 0% to 70% relative humidity (RH) at 21°C, with the exception of (E)-2-hexenol. Product ion branching ratios were also affected by humidity, with the relative abundance of the protonated molecular ions and higher mass fragment ions increasing with humidity. The effect of reduced field (E/N) on the fragmentation of GLVs was examined in the drift tube of the PTR-TOF-MS. The structurally similar GLVs are acutely susceptible to fragmentation following ionization and the fragmentation patterns are highly dependent on E/N. Overall the measured fragmentation patterns contain sufficient information to permit at least partial separation and identification of the isomeric GLVs by looking at differences in their fragmentation patterns at high and low E/N.     

我国人口问题与可持续发展

人口因素在“人口、资源、环境、经济、社会”可持续发展系统中处于中心地位。本文从可持续发展角度，探讨了我国人口数量、质量、结构、分布等方面存在的问题，并对其优化方向作了简要分析。     

Cu Ni As Cr对萝卜出苗的影响

利用盆栽试验研究Ｃｕ、Ｎｉ、Ａｓ、Ｃｒ４个元素不同浓度对萝卜出苗的影响．结果表明，土壤含Ｃｕ５０ｍｇ／ｋｇ以上时，随着含Ｃｕ量的增加，出苗数随之减少．在酸性土壤上发生Ｃｕ和Ｎｉ危害时，可用提高土壤ｐＨ至中性的办法来消除．在中性土壤上，含Ｎｉ５０ｍｇ／ｋｇ以上对萝卜出苗有害．Ｃｕ、Ｎｉ复合污染比单一元素污染的危害大，且毒性Ｎｉ＞Ｃｕ．土壤Ｃｒ、Ａｓ含量越大，对萝卜出苗的危害也越大，并且毒性Ｃｒ（６＋）＞Ｃｒ（３＋）．