南宁市大气颗粒物TSP、PM10、PM2.5污染水平研究

2002年在南宁市的5个典型城市功能区内,共采集了125个大气样品(按季节分别采集),初步调查了大气中颗粒物TSP、PM10、PM2.5的污染状况。结果表明,南宁市TSP、PM10、PM2.5的污染很严重,超标率分别为67．5％、82．5％、92．5％,对人体健康危害更大的PM2．5占到了PM10的63．5％左右。重污染区PM2.5的浓度超过轻污染区近一倍。     

包头市城市污水水质指标的统计学分析

以包头市污水处理厂2015年全年进水实测数据为基础,应用统计学方法分析了包头市城市污水中6个水质指标(COD、BOD5、SS、氨氮、TN和TP)的概率分布、变化规律和相关关系。结果表明,包头市污水处理厂进水中,除COD呈正态分布外其他5个水质指标均服从偏态分布,COD、BOD5、SS、氨氮、TN和TP全年中间值分别为428.00、288.00、155.00、67.35、89.85、9.57mg/L,各水质指标均随季节变化明显。COD和BOD5、COD和SS、BOD5和SS、氨氮和TN间存在较明显的一元线性关系。进水BOD5/COD(质量比)平均值高于0.45,BOD5/COD0.45的累积分布概率为96.6%,说明包头市城市污水可生化性较好。BOD5/TN(质量比)平均值为3.32,BOD5/TN4.00的累积分布概率为59.7%,说明有污水反硝化碳源不足的现象存在。进水BOD5/TP(质量比)平均值为31,且全年BOD5/TP20的累积分布概率为93.0%,满足生物除磷要求。     

地表水BOD_5的快速预测预报

地表水 BOD5的测试需 5 d时间 ,分析周期较长。建立了BOD5与 CODMn、BOD5与 DO之间的直线回归方程 ,通过测定地表水的 CODMn和 DO可分别对地表水的 BOD5实现快速预测预报。现场使用溶解氧测定仪检测 DO,可立即预报地表水的 BOD5     

工业废水中锑的分光光度测定——用5—Br—PADAP作显色剂

测定微量锑多用罗丹明B、孔雀绿、邻苯二酚紫、溴邻苯三酚红作显色剂,亦有报导用2-(3.5-二溴-吡啶偶氮)-5-二乙氨基酚(简称为3.5-二Br-PADAP)分光光度测定锑的。我们对罗丹明B、邻苯二酚紫、溴邻苯三酚红、2-(5-溴-吡啶偶氮)-5-二乙氨基酚(简称5-Br-PADAP)作比较试验表明,5-Br-PADAP测定锑具有较高的灵敏度与选择性,色泽稳定,重现性良好。本文报告用5-Br-PADAP作显色剂,研究在水-丙酮介质中测定锑(Ⅲ)     

宠物食品加工废水处理工程实例

介绍了水解 接触氧化 气浮工艺在宠物食品加工废水中的应用。实践表明 ,在进水CODCr、BOD5和SS分别为 2 5 0 0mg/L、1 6 0 0mg/L和 2 5 0mg/L的情况下 ,出水的CODCr、BOD5和SS分别为 70mg/L、1 5mg/L和 4 0mg/L ,达到了《污水综合排放标准》(GB8978 96 )一级标准。经过 1年半的运行表明 ,该工艺具有运行稳定性好、处理效率高、操作管理方便的优点。     

pH、接种量及固形物含量对氧化亚铁硫杆菌LX5煤炭生物脱硫的影响

高硫煤燃烧释放SO2污染环境。采用摇瓶实验,以FeS2驯化的嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)LX5为供试菌株,研究了pH、接种量及煤粉数量对菌株LX5进行生物脱硫的影响。实验结果表明,在15 d的反应周期中反应液的起始pH为2.0、2.5、3.0和4.0时,菌株LX5的脱硫效率分别为43.1%、73.3%、61.9%和37.3%;将菌株LX5的接种量控制为5%、10%及15%时,其脱硫效率分别为44.2%、68.1%及72.2%;将煤粉含量调整为5%、10%及15%时,LX5的脱硫效率分别为73.1%、72.2%及56.3%。摇瓶实验确定的最合适的生物脱硫条件是:培养液起始pH为2.5,LX5接种量为培养液体积的10%,煤粉加入量为培养液质量的10%。在5 L序批式反应器进行煤炭生物脱硫的启动实验,研究表明,反应15 d后煤炭脱硫率达到69.2%,而煤中黄铁矿硫的脱硫率可达78%。     

Vis/Co-TiO_2/KHSO_5体系Fenton-光催化协同降解苯酚

通过溶胶-凝胶法制备了同时具有可见光(Vis)光催化和Fenton催化双重活性的Co-TiO2催化剂。通过对比Vis/Co-TiO2/KHSO5、Co-TiO2/KHSO5和Vis/Co-TiO23种体系对苯酚的降解效果,Vis/Co-TiO2/KHSO5表现出明显的Fenton-光催化协同作用。进一步研究pH值、KHSO5与苯酚摩尔比(nKHSO5∶nC6H6O)和Co-TiO2投加量(mCo-TiO2)对Fenton-光催化协同降解苯酚效果的影响。结果表明,pH=6.9、nKHSO5∶nC6H6O=10∶1、mCo-TiO2=1.0 g/L时,降解率达100%。最后,结合XRD、XPS和UV-DRS等手段和催化活性实验数据分析了Vis/Co-TiO2/KHSO5体系的催化机理。     

四氧化三铁活化过硫酸盐降解活性黑5

采用水热合成法制备出了具有较高催化活性的催化剂四氧化三铁(Fe_3O_4),并利用Fe_3O_4活化过硫酸盐降解活性黑5,考察了初始pH、Fe_3O_4投加量、活性黑5初始浓度和过硫酸盐投加量对活性黑5降解效果的影响。结果表明,Fe_3O_4活化过硫酸盐降解活性黑5的最佳条件为初始pH 6、活性黑5初始质量浓度50mg/L、过硫酸盐投加量6mmol/L、Fe_3O_4投加量2.0g/L。在最佳条件下,反应180min,活性黑5的降解率达到80.2%,Fe_3O_4反复使用5次后,活性黑5的降解率仍能达到77%以上。活性黑5的降解途径为:偶氮键打开产生苯环中间产物和萘环中间产物,萘环中间产物逐步转化为邻苯二甲酸酐→邻苯二甲酸→苯甲酸;苯环中间产物逐步转化为对氨基苯磺酸→硝基苯和对氨基苯酚,对氨基苯酚转化为对苯二酚;最终被彻底氧化降解成CO_2、H_2O等无毒小分子物质。活性黑5在降解过程中对植物的毒性先升高后降低。     

硝基修饰的超高交联树脂对酚类化合物的吸附研究

对超高交联聚苯乙烯树脂进行硝基修饰,制得硝基修饰超高交联聚苯乙烯树脂JN-5(简称JN-5).JN-5树脂具有比表面积高、亲水性强等优点.对酚类化合物在水溶液中进行静态吸附研究,平衡吸附试验数据和吸附热力学计算结果都表明,JN-5对4种酚类化合物(对甲基苯酚、苯酚、对氯苯酚、对硝基苯酚)的吸附性能优于大孔吸附树脂XAD-4.这主要得益于JN-5的高比表面积和丰富的微孔结构.动态小柱吸附试验中,在流速4.77mL/h、303K的条件下,JN-5对苯酚的穿透吸附量为2.43mmol/g,总吸附量为3.26mmol/g,吸附后的树脂能用8%(质量分数)的NaOH溶液完全洗脱.     

催化剂Cu/HZSM-5的硅铝比对催化分解N2O的影响

为系统研究Cu/HZSM-5硅铝比对其各类性能的影响,采用等体积浸渍法与离子交换法,以硅铝比为27、50、117的HZSM-5为载体,制备负载型N_2O催化分解催化剂Cu/HZSM-5和Cu/ZSM-5,催化剂的活性组分为CuO。通过催化剂反应活性评价、X射线荧光光谱分析、X射线衍射分析结果,对2种方法制备催化剂活性的差异进行了分析。利用比表面积孔径分析仪(BET)、X射线衍射分析(XRD)、场发射扫描电镜(SEM)、X射线荧光光谱分析(XRF)、氢气程序升温还原分析(H_2-TPR)、氨气程序升温脱附分析(NH_3-TPD)等表征手段对催化剂物化性质等进行分析,得到载体HZSM-5的硅铝比差异对催化剂特征结构、比表面积、特征形貌、酸性位数量、可还原性能的影响规律。等体积浸渍法制备的催化剂活性评价结果表明,硅铝比为27的Cu_8/HZSM-5催化剂活性最好,完全催化分解N_2O的温度在400℃左右。水热稳定性实验结果以及寿命实验结果表明,硅铝比为27的Cu_8/HZSM-5具有良好的水热稳性,3种硅铝比的Cu_8/HZSM-5催化剂均具备良好的热稳定性。Cu/HZSM-5的活性评价以及各种表征结果显示,在一定范围内,硅铝比越低,催化剂活性越好。     

A comparison of statistical methods for deriving freshwater quality criteria for the protection of aquatic organisms

Species sensitivity distributions (SSDs) are increasingly used in both ecological risk assessment and derivation of water quality criteria. However, there has been debate about the choice of an appropriate approach for derivation of water quality criteria based on SSDs because the various methods can generate different values. The objective of this study was to compare the differences among various methods. Data sets of acute toxicities of 12 substances to aquatic organisms, representing a range of classes with different modes of action, were studied. Nine typical statistical approaches, including parametric and nonparametric methods, were used to construct SSDs for 12 chemicals. Water quality criteria, expressed as hazardous concentration for 5 % of species (HC₅), were derived by use of several approaches. All approaches produced comparable results, and the data generated by the different approaches were significantly correlated. Variability among estimates of HC₅ of all inclusive species decreased with increasing sample size, and variability was similar among the statistical methods applied. Of the statistical methods selected, the bootstrap method represented the best-fitting model for all chemicals, while log-triangle and Weibull were the best models among the parametric methods evaluated. The bootstrap method was the primary choice to derive water quality criteria when data points are sufficient (more than 20). If the available data are few, all other methods should be constructed, and that which best describes the distribution of the data was selected.     

城市固体废物好氧生物反应器填埋方式的实验研究

MSW(城市固体废物)生物反应器型填埋是一种较新颖的方法。在系统分析现有填埋方法优缺点的基础上,对其加以改进,将强制通风好氧和渗滤液循环2种方式有机地结合在一起,构建了MSW好氧生物反应器。考察了NH3、CH4、CO2、pH和温度等因素,并监测分析了渗滤液中的COD、BOD5、Zn2+、NH4+和NO3-等指标,旨在研究其中垃圾的降解及渗滤液中COD、BOD5、Zn2+、NH4+和NO3-的去除情况,探讨该生物反应器对垃圾和渗滤液相关参数的作用机理。结果表明,该反应器对渗滤液中COD、BOD5、NO3-的去除率分别达到96.34%、94.58%和99.9%,对其中的Zn2+也有较好的脱除效果。     

Retention time profiling of all 136 tetra- through octa- chlorinated dibenzo-p-dioxins and dibenzofurans on a variety of Si-Arylene gas chromatographic stationary phases

The applicability of three different Silphenylene Silicone co-polymer (Si-Arylene) GC stationary phases (J&W Scientific DB-5ms, Varian VF-5ms, and VF-Xms) has been evaluated for the separation of all 136 tetra- through the octa- chlorinated dibenzo-p-dioxins (PCDD) and chlorinated dibenzofurans (PCDF) from closely eluting isomers using gas chromatography/high resolution mass spectrometry (GC/HRMS). Their relative performance data are compared to the “conventional” 5% diphenyl 95% dimethylpolysiloxane GC column (Supelco Equity-5) and to each other based on absolute retention times, visualized mass chromatograms, and the separation of 2,3,7,8-substituted isomers. VF-Xms GC column was able to demonstrate a better performance towards separation of 2,3,7,8-substituted PCDD/PCDF compared to other Si-Arylene GC columns tested, where only 2,3,4,7,8-PnCDF can not be resolved from 1,2,3,6,9-PnCDF and 2,3,4,6,7,8-/1,2,3,6,8,9-HxCDF and 1,2,3,7,8,9-/1,2,3,4,8,9-HxCDF can be at least partially resolved. These data suggest that the development of a single GC column for the separation of all 17 2,3,7,8-substituted dioxins and furans is feasible, which therefore could be used as a standard tool for the PCDD/PCDF methods globally including USEPA methods 1613b, 8290A, 8280B, European Standard Method EN 1948, Canadian methods DFPCB-E3418, EPS 1/RM/19, Japanese methods JIS K0311 and JIS K0312. Having one specific GC column to separate all 2,3,7,8-substituted PCDD/PCDF will significantly improve the data quality, comparability by the various methods and assessment techniques while simultaneously leading to a more cost and time efficient operation.     

Evaluation of PNEC values: extrapolation from Microtox, algae, daphnid, and fish data to HC5

In order to evaluate the risk to the environment from long term exposure of any discharged substance, toxicity thresholds are estimated, and particularly the Predicted No Effect Concentration (PNEC). This concentration can be estimated by the classic assessment factor approach or by statistical methods. These are more scientifically sound but they require several (at least 5-6) chronic ecotoxicity data, implying greater cost and time. New extrapolation methods derived from the statistical concept but requiring less data have been studied. Results show that methods based on chronic data are more reliable than methods based on acute data but the improvement is quite small. Considering the costs of chronic tests compared to acute tests, approaches based on acute data are an attractive alternative. A simple regression on the mean of the acute data gives the best results.     

HPLC-MSn and GC-MS methods to study sunlight and UV-lamp degradations of 1-amino-5-naphthalene sulfonate

HPLC-DAD, HPLC-MS/MS, GC-MS and spectrophotometric methods are employed to investigate the degradation process of sodium 1-amino-5-naphthalene sulfonate (1A5NS) aqueous solutions, when exposed to sunlight and UV-lamp (254 nm) irradiations. Experimental results show that both sunlight and 254 nm UV-lamp irradiations destroy the chemical and give rise to major degradation products, characterised by the same m/z ratios. Degradation times are lower for sunlight irradiation, for which a t(1/2) value of 137.4 min has been evaluated, in comparison with the value of t(1/2) of 26.8 min, observed for UV-lamp irradiation. The degradation pathway and the structures of the degradation products are proposed.     

城市污水厂水质相关性及分布状态的研究和应用

采用统计学及质量控制的一些基本理论及方法对污水处理厂的运行数据进行分析,得出城市污水处理厂BOD5、COD、SS、TN、TP等主要出水指标呈正态分布的规律;城市污水BOD5、COD、TN、TP等指标间存在显著线性相关性的结论.研究结论可用于污水处理厂制定经济合理的出水监测方案以及对污水处理厂运行可靠性等进行评估.     

氧化-混凝法处理碱性高砷废水的实验研究

对碱性高砷废水的处理进行了研究 ,针对常规混凝法除砷的缺点提出了氧化 混凝工艺。结果表明 ,用氧化 混凝工艺除砷效果显著 ,废水经处理后砷含量低于 0 5mg/L ,符合国家排放标准。氧化 混凝除砷的最佳工艺条件为 :pH值为 6— 7,H2 O2 用量为 2 5 % ,氧化时间为 10min ,Fe2 (SO4) 3 用量为 2 5g/L ,PAM用量为 11 2 5mg/L。     

Environmental factors and spatiotemporal distribution characteristics of the global outbreaks of the highly pathogenic avian influenza H5N1

The spread of highly pathogenic avian influenza H5N1 has posed a major threat to global public health. Understanding the spatiotemporal outbreak characteristics and environmental factors of H5N1 outbreaks is of great significance for the establishment of effective prevention and control systems. The time and location of H5N1 outbreaks in poultry and wild birds officially confirmed by the World Organization for Animal Health from 2005 to 2019 were collected. Spatial autocorrelation analysis and multidistance spatial agglomeration analysis methods were used to analyze the global outbreak sites of H5N1. Combined with remote sensing data, the correlation between H5N1 outbreaks and environmental factors was analyzed using binary logistic regression methods. We analyzed the correlation between the H5N1 outbreak and environmental factors and finally made a risk prediction for the global H5N1 outbreaks. The results show that the peak of the H5N1 outbreaks occurs in winter and spring. H5N1 outbreaks exhibit aggregation, and a weak aggregation phenomenon is noted on the scale close to 5000 km. Water distance, road distance, railway distance, wind speed, leaf area index (LAI), and specific humidity were protective factors for the outbreak of H5N1, and the odds ratio (OR) were 0.985, 0.989, 0.995, 0.717, 0.832, and 0.935, respectively. Temperature was a risk factor with an OR of 1.073. The significance of these ORs was greater than 95%. The global risk prediction map was obtained. Given that the novel coronavirus (COVID-19) is spreading globally, the methods and results of this study can provide a reference for studying the spread of COVID-19.

     

Tipping Points in the Arctic: Eyeballing or Statistical Significance?

Arctic ecosystems have experienced and are projected to experience continued large increases in temperature and declines in sea ice cover. It has been hypothesized that small changes in ecosystem drivers can fundamentally alter ecosystem functioning, and that this might be particularly pronounced for Arctic ecosystems. We present a suite of simple statistical analyses to identify changes in the statistical properties of data, emphasizing that changes in the standard error should be considered in addition to changes in mean properties. The methods are exemplified using sea ice extent, and suggest that the loss rate of sea ice accelerated by factor of ~5 in 1996, as reported in other studies, but increases in random fluctuations, as an early warning signal, were observed already in 1990. We recommend to employ the proposed methods more systematically for analyzing tipping points to document effects of climate change in the Arctic.     

The Effect of Analytical Method on Indicated Atmospheric SO2 Concentration

Atmospheric samples collected in several American cities were analyzed for SO₂ concentration using various analytical methods. The methods were: (1) electroconductivity, (2) West-Gaeke, (3) West-Gaeke with membrane prefdter, (4) West-Gaeke with glass-fiber prefilter, (5) hydrogen peroxide, (6) hydrogen peroxide with membrane prefilter, and (7) hydrogen peroxide with glass-fiber prefilter. The relationships among SO₂ data produced by these methods were evaluated statistically. Where statistical differences among methods, at the 95% confidence level, were determined then relationships were further delineated. Factors considered in these comparisons were: (1) location, {2) time of day, (8) concentration range, (4) particulate concentration, and (5) humidity. Laboratory evaluations of these methods show that each method is subject to different interfering substances. Laboratory evaluations of these methods show that each method is subject to different interfering substances. The relationship among methods obtained in these studies will complement these data and perhaps provide for further laboratory and field evaluation of methods used to measure SO₂. The relationship among SO₂ data produced by these methods should be useful in relating atmospheric SO₂ concentration to its effects and to those involved in establishing ambient air quality standards.