气相色谱-质谱法测定水中挥发性有机物的测量不确定度评定

根据测量不确定度评定与表示理论,采用气相色谱一质谱法测定水中挥发性有机物。以氯乙烯为例,通过计算和评定,得出当氯乙烯的测量结果为4．99μg／L时,取包含因子k=2（约95％置信概率）,扩展不确定度U=0．96μg／L。该不确定度评定方法在实际工作中具有较强的实用价值。     

水中总磷测量的不确定度评定

采用钼酸铵分光光度法测定水中总磷的含量,分析该法测量不确定度的来源,评定水中总磷的测量不确定度。     

水质铜测定的不确定度评定

根据火焰原子吸收分光光度法测定水中铜的含量，分析了测量不确定度的主要来源，即标准曲线不确定度、标准溶液不确定度、测量重复性不确定度。计算得到水中铜的测定结果的合成不确定度为0．098mg／L，扩展不确定度为0．196mg/L。     

水中氯化物测定的不确定度评定

根据硝酸银滴定法测定水中氯化物的含量，分析了该方法测量不确定度的来源，评定了水中氯化物的测量不确定度，在各不确定度中，以标准溶液配制与样品分析时滴定消耗的硝酸银体积引入的不确定度较大。     

平皿计数法测定细菌总数的不确定度评定

根据细菌总数的测定方法,分析了该方法测量不确定度的来源,评定了水中细菌总数的测量不确定度。     

重铬酸钾法测定水中COD的不确定度分析

建立了重铬酸钾法测定水中化学需氧量的相对合成标准不确定度的数学模式,应用一个较高浓度的实例,对B类不确定度的分量作了详尽的分析和计算,得出测量扩展不确定度的结果。     

纳氏试剂分光光度法测定水中氨氮的不确定度评定

通过纳氏试剂分光光度法测定水中氨氮的过程分析，对测定不确定度作出了评估，并得出产生测定不确定度的主要原因。     

水中放射性核素铯-137测量的不确定度评估

放射性核素利用化学载带、浓缩后进行测量,化学前处理步骤比较复杂,通过分析测量实验中的不确定度和分析计算公式中的有关参数,了解到分析水中放射性核素铯-137时,主要受到样品测量、仪器探测效率、样品化学回收率和样品取样体积等方面的不确定度因素的影响。     

江西省主要水系氟含量的监测

一、前言 氟存在于天然水中,生活用水氟含量高,经摄入后影响人体和动物,已有很多报道。 在天然水中测定氟,一般采用氟试剂或茜素锆比色法、离子选择电极法等,本工作采用氟离子选择电极707座标纸格氏(Gran's)作图法。 格氏作图法于七十年代从理论上探讨,国内也有人做研究工作,但实用于监测方面     

水中氟含量的快速测定——离子电极标准加入法

水中氟含量的测定,以前采用蒸馏比色法,费时费事.新近发展起来的氟离子选择电极具有测量简便、灵敏度高,选择性好以及容易实现连续自动测量等优点,已应用于各种水质分析.本文介绍采用氟离子电极作为指示电极,碘离子电极作为参比电极,用标准加入法快速测定天然水中氟含量的方法.测量一个样品只需要1-2分钟,在0.1     

Study of TiO2 anatase nano and microstructures with dominant {001} facets for NO oxidation

Introduction

TiO₂ anatase nanoplates and hollow microspheres were fabricated by a solvothermal?Chydrothermal method using titanium isopropoxide as a titanium precursor and hydrofluoric acid as a capping agent in order to enhance the formation of the {001} crystal facets of the anatase nanocrystals.

Methods

These different morphological structures of TiO₂ anatase can be achieved by only changing the solvent, keeping the amount of the precursor and of the capping agent identical during the solvothermal?Chydrothermal process.

Results and discussion

After calcination of the samples, the adsorbed fluoride atoms on the {001} crystal facets of the TiO₂ anatase nanocrystals were completely removed from their surface according to XPS analysis. The calcined TiO₂ anatase structures were higher crystallized and the specific surface area of the catalysts increased, enhancing their photocatalytic activity in comparison to the non-calcined TiO₂ anatase structures. All TiO₂ anatase samples with adsorbed as well as non-adsorbed fluoride atoms on their {001} crystal facets, exhibited a higher photonic efficiency than Degussa P25, which was used as a reference.

Conclusion

The fluoride free TiO₂ anatase nanoplates exhibited the best photocatalytic activity in oxidizing the NO gas to NO₂ and NO₃ ^?.     

Combining the multivariate statistics and dual stable isotopes methods for nitrogen source identification in coastal rivers of Hangzhou Bay,China

Coastal rivers contributed the majority of anthropogenic nitrogen (N) loads to coastal waters, often resulting in eutrophication and hypoxia zones. Accurate N source identification is critical for optimizing coastal river N pollution control strategies. Based on a 2-year seasonal record of dual stable isotopes (\({\updelta}^{15}\mathrm{N}-{\mathrm{NO}}_3^{\hbox{-} }\) and \({\updelta}^{18}\mathrm{O}-{\mathrm{NO}}_3^{\hbox{-} }\)) and water quality parameters, this study combined the dual stable isotope-based MixSIAR model and the absolute principal component score-multiple linear regression (APCS-MLR) model to elucidate N dynamics and sources in two coastal rivers of Hangzhou Bay. Water quality/trophic level indices indicated light-to-moderate eutrophication status for the studied rivers. Spatio-temporal variability of water quality was associated with seasonal agricultural, aquaculture, and domestic activities, as well as the seasonal precipitation pattern. The APCS-MLR model identified soil + domestic wastewater (69.5%) and aquaculture tailwater (22.2%) as the major nitrogen pollution sources. The dual stable isotope-based MixSIAR model identified soil N, aquaculture tailwater, domestic wastewater, and atmospheric deposition N contributions of 35.3 ±21.1%, 29.7 ±17.2%, 27.9 ±14.5%, and 7.2 ±11.4% to riverine \({\mathrm{NO}}_3^{\hbox{-} }\) in the Cao’e River (CER) and 34.4 ±21.3%, 29.5 ±17.2%, 27.4 ±14.7%, and 8.7 ±12.8% in the Jiantang River (JTR), respectively. The APCS-MLR model and the dual stable isotope-based MixSIAR model showed consistent results for riverine N source identification. Combining these two methods for riverine N source identifications effectively distinguished the mix-source components from the APCS-MLR method and alleviated the high cost of stable isotope analysis, thereby providing reliable N source apportionment results with low requirements for water quality sampling and isotope analysis costs. This study highlights the importance of soil N management and aquaculture tailwater treatment in coastal river N pollution control.

     

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。     

Influence of Type and Amount of Straw Cover on Weed Emergence

Abstract

This research was undertaken during 2003–2004 growing season to evaluate the {effects of type [forage sorghum “hybrid Cober Exp” (Sorghum bicolor × Sorghum} sudanense), forage millet (Pennisetum americanum “var. BN2”), finger millet {(Eleusine coracana), and St Lucia grass (Brachiaria brizantha)] and amount of} {straw cover (5.5 and 3.0 t ha}^?1) upon the emergence of Bidens pilosa, Chamaesyce {spp., Amaranthus spp., and Commelina benghalensis, under field conditions of the} {Brazilian Cerrado, in the region of Uberlândia—MG. The control consisted} {additional treatment lacking the straw cover. Emergence of weed depended on the} {type and amount of straw cover, as well as the weed species. The lowest number} {of B. pilosa seedlings was found in the presence of forage sorghum straw;} {Chamaesyce spp. in the lack of straw; Amaranthus spp. in the presence of higher} {amount of forage sorghum and forage millet, and lower amounts of forage millet} {and Finger Millet. All the types and amounts of straw reduced the emergency of} {C. benghalensis, except at the lowest level of St Lucia grass and the lack of straw.     

离子选择电极分析法测定标样中氟化物的不确定度评定

通过对离子选择电极法测定标样中氟化物的过程研究，分析了该方法测量不确定度的来源，给出了相对不确定度分量，得出测量扩展不确定度的结果。     

Trace metals, anions and polybromodiphenyl ethers in settled indoor dust and their association

Contaminants in settled indoor dust are potentially health hazardous to human. Thus, identification and quantification of toxic chemicals in settled indoor dust is of great concern. In this study, the levels of major anions ( $ \mathrm{C}{{\mathrm{l}}^{-}},\mathrm{N}{{\mathrm{O}}_2}^{-},\mathrm{B}{{\mathrm{r}}^{-}},\mathrm{N}{{\mathrm{O}}_3}^{-},\mathrm{P}{{\mathrm{O}}_4}^{3-}\,\mathrm{and}\,\mathrm{S}{{\mathrm{O}}_4}^{2- } $ ), trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, As and Pb) and polybromodiphenyl ethers (PBDEs) in settled office and home dust were determined and correlations between the contaminants investigated. Depending on the available materials in both microenvironments, the most possible sources were identified. The results showed that the settled office dusts (n?=?6 pooled samples from 85 offices) were more contaminated than home dusts (n?=?8 homes). For anions, $ \mathrm{S}{{\mathrm{O}}_4}^{2- } $ and Cl^– accounted for 87 and 97 % of the total office and home dust contaminants, respectively. For trace metals, Fe, Cu, Zn and Mn, accounted for 98 % of the contaminants in both office and home dust samples. Fe exhibited the highest percentage of 76.7 and 87.3 % in office and home dust samples, respectively. For PBDEs, the mean concentrations detected in office and home dust ranged between 5.8–86.3 and 1.5–20.6 ng?g^?1, respectively. The log-transformed correlation between the total concentrations of trace metals and major anions detected in offices and homes was positive for offices and negative for homes with a statistically significant values (r?=?0.73, p?<?0.01; r?= ?0.22, p?<?0.01, respectively). The daily exposure rates determined for the most hazardous such as As, Cd, Pb and PBDEs congeners, relative to the individual concentrations reported in the literature in settled indoor dust, were found very lower. Therefore, maybe it is possible to expect less potential health risk. Investigation of formation of coordination compounds between trace metals and PBDEs congeners is possible; however, this requires further study.     

Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis

Transport and degradation of de-icing chemical (containing propylene glycol, PG) in the vadose zone were studied with a lysimeter experiment and a model, in which transient water flow, kinetic degradation of PG and soil chemistry were combined. The lysimeter experiment indicated that aerobic as well as anaerobic degradation occurs in the vadose zone. Therefore, the model included both types of degradation, which was made possible by assuming advection-controlled (mobile) and diffusion-controlled (immobile) zones. In the mobile zone, oxygen can be transported by diffusion in the gas phase. The immobile zone is always water-saturated, and oxygen only diffuses slowly in the water phase. Therefore, the model is designed in a way that the redox potential can decrease when PG is degraded, and thus, anaerobic degradation can occur. In our model, manganese oxide (MnO₂, which is present in the soil) and NO \(_{3}^{-}\) (applied to enhance biodegradation) can be used as electron acceptors for anaerobic degradation. The application of NO \(_{3}^{-}\) does not result in a lower leaching of PG nor in a slower depletion of MnO₂. The thickness of the snowcover influences the leached fraction of PG, as with a high infiltration rate, transport is fast, there is less time for degradation and thus more PG will leach. The model showed that, in this soil, the effect of the water flow dominates over the effect of the degradation parameters on the leaching at a 1-m depth.     

The influence of hydroxyl volatile organic compounds on the oxidation of aqueous sulfur dioxide by oxygen

Although the effect of volatile organic compounds (VOCs) on the oxidation of dissolved sulfur dioxide by oxygen has been the subject of many investigations, this is the first study which examines the effect of a large number of precisely 16 hydroxy compounds. The kinetics both in the absence and the presence of VOCs was defined by rate laws (A and B): A $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_o={k}_o\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ B $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_i={k}_i\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ where R _o and k _o are the initial rate and first-order rate constant, respectively, in the absence of VOCs, R _i , and k _i are the initial rate and the first-order rate constant, respectively, in the presence of VOCs, and [S(IV)] is the concentration of dissolved sulfur dioxide, sulfur(IV). The nature of the dependence of k _i on the concentration of inhibitor, [Inh], was defined by Eq. (C). C $$ {k}_i={k}_0/\left(1+B\left[\mathrm{Inh}\right]\right) $$ where B is an empirical inhibition parameter. The values of B have been determined from the plots of 1/k _i versus [Inh]. Among aliphatic and aromatic hydroxy compounds studied, t-butyl alcohol and pinacol were without any inhibition effect due to the absence of secondary or tertiary hydrogen. The values of inhibition parameter, B, were related to k _inh , the rate constant for the reaction of SO₄ ^? radical with the inhibitor, by Eq. (D). D $$ B=\left(9\pm 2\right)\times 1{0}^{-4}\times {k}_{inh} $$ Equation (D) may be used to calculate the values of either of B or k _inh provided that the other is known. The extent of inhibition depends on the value of the composite term, B[Inh]. However, in accordance with Eq. (C), the extent of inhibition would be sizeable and measurable when B[Inh]?>?0.1 and oxidation of S(IV) would be almost completely stopped when B[Inh]?≥?10. B[Inh] value can be used as a guide whether the reaction step: SO₄ ^??+?organics? \( \overset{k_{inh}}{\to } \) ?SO₄ ^2??+?non-chain products: should be included in the multiphase models or not.     

放电等离子体与饲养酵母联合处理味精废水的初步研究

对采用放电等离子体与饲养酵母联合处理味精废水进行了初步研究。结果表明，放电等离子体预处理后废水的CODcr值普遍升高，但经假丝酵母联合处理后CODCr去除率增加了38．3％，效果明显优于仅采用饲养酵母法处理的味精废水，说明放电等离子体预处理可使味精废水中的有机大分子破坏成小分子，有利于生物降解，为味精废水治理提供了一条新的途径。实验初步研究了联合处理后的CODcr去除率与预处理电压、预处理电流、预处理次数的关系，结果表明存在相应的最优值。     

猪粪经蝇蛆生态处理后粪臭素和排污量的变化

观察家蝇幼虫 (蝇蛆 )生态处理猪粪后 ,猪粪中粪臭素和排污量的变化。以养猪场的猪粪为试验材料 ,经当地蝇蛆处理的猪粪作为处理组 ,未经蝇蛆处理的猪粪为对照组 ,测定两组猪粪样本中粪臭素 ( 3 -甲基吲哚 ,简称 3 -MI)、CODCr、BOD5和 NH3-N的质量浓度。经蝇蛆处理后每 kg猪粪中的 3 -MI、CODCr、BOD5和 NH3-N分别为 2 .76× 10 - 3、5 6.3 6、14 .84和 3 .41g;对照组中上述物质分别为 3 8.5 8× 10 - 3、12 3 .0 1、60 .0 7和 3 .64 g。经蝇蛆处理后的猪粪中的 3 -MI、CODCr和 BOD5分别减少了 92 .8%、5 4.2 %和75 .3 %;而 NH3-N的含量仅减少 6.3 %。蝇蛆生态处理猪粪可有效减少粪臭素和有机污染物 ,有利于改善环境