石墨炉原子吸收光谱法测定海水中的三丁基锡

本文采用石墨炉原子吸收光谱法（ＧＦＡＡＳ）测定海水甲苯抽提液中的三丁基锡。文中考察了１４种基体改进剂对灵敏度的影响，选出了能显著提高测定灵敏度的Ｃａ－Ｃｒ基体改进剂，以０．５／０．１ｍｇ／ｍｌ的浓度比例对８个实样进行了测定，其相对标准偏差（ＲＳＤ）为３％，其特征浓度为７ｐｇ，回收率在８８％￣１０４％之间，成功地应用于近海沉积物对三丁基锡吸附规律的研究。     

基于超高效液相色谱串联质谱法的番茄果实和土壤中氟吡菌胺残留测定

建立了番茄果实和土壤中氟吡菌胺残留的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。用乙腈水溶液提取样品中的氟毗菌胺,以C_(18)柱为分析柱、乙腈-甲酸水溶液为流动相,采用超高效液相色谱-串联质谱多反应监测、电喷雾正离子源、外标法定量。氟吡菌胺在0.05~1.00 mg/L范围内与峰面积呈良好的线性关系,线性方程为y=6964.10x-143.28,决定系数为0.996 8。向对照番茄果实、对照土壤中分别添加氟吡菌胺标样,使其添加量分别为0.10 mg/kg、0.40 mg/kg和2.00 mg/kg,平均回收率分别为92.43%~103.32%和92.75%~104.46%,相对标准偏差分别为3.8%~4.9%和3.4%~4.4%。番茄果实和土壤中氟吡菌胺的定量限分别为1.0μg/kg和1.7μg/kg,检出限分别为0.3μg/kg和0.5μg/kg。     

三级AO耦合工艺低温污水处理脱氮机理

采用分段进水三级AO耦合流离生化工艺处理低温废水,在温度为（10±1）℃条件下,控制HRT为8h,进水流量分配比为3：2：1,污泥回流比为50%,考察耦合工艺对低温污水中污染物的去除效果、反应器内污染物变化规律、各级氮去除规律及系统硝化反硝化性能.研究表明：耦合工艺COD及NH₄⁺-N去除效率均超过90%,TN及TP去除效率达到80%,反应器内生物膜污泥浓度在400~800mg/L之间,系统各级NH₄⁺-N去除率均超过80%,缺氧反硝化脱氮率及好氧同步硝化反硝化脱氮率分别为50.15%和26.05%.受底物浓度及功能菌群数量影响,系统第二级比硝化速率及比反硝化速率均最高.     

Volatile organic chloramines formation during ClO2 treatment

Volatile organic chloramines are reported as the disinfection byproducts during chlorination or chloramination.However,ClO_2,as an important alternative disinfectant for chlorine,was not considered to produce halogenated amines.In the present work,volatile organic chloramines including(CH_3)_2 NCl and CH_3 NCl_2 were found to be generated during the reaction of ClO_2 and the dye pollutants.(CH_3)_2 NCl was the dominant volatile DBP to result from ClO_2 treated all four dye pollutants including Methyl Orange,Methyl Red,Methylene Blue and Malachite Green,with molar yields ranging from 2.6% to 38.5% at a ClO_2 to precursor(ClO_2/P) molar ratio of 10.HOCl was identified and proved to be the reactive species for the formation of (CH_3)_2 NCl,which implied(CH_3)_2 NCl was transformed by a combined oxidation of ClO_2 and hypochlorous acid.(CH_3)_2 NCl concentrations in the ppb range were observed when real water samples were treated by ClO_2 in the presence of the dye pollutants.The results suggest that these azo dyes are one of the significant precursors for the formation of HOCl during ClO_2 treatment and that organic chloramines should be considered in ClO_2 disinfection chemistry and water treatment.     

基于质子转移反应质谱(PTR-MS)对北方冬季大气氨的观测研究

氨是大气中广泛存在的碱性气体,已有的研究表明,氨能够参与包括硫酸/水体系的三元成核过程,进而促进新粒子的形成;同时,氨也是大气二次有机气溶胶（SOA）的重要前体物,对二次有机气溶胶的形成具有不可忽视的影响.了解大气中氨的污染情况,实现对大气中氨的高时间分辨率的在线观测,对于研究大气中氨的时空分布及来源解析,进而加深对气溶胶生成机理及气溶胶在大气辐射平衡与气候变化中作用的认识有重要意义.本研究使用一台自主搭建的质子转移反应质谱仪（PTR-MS）,以丙酮作为反应试剂,由电晕放电离子源产生质子化的丙酮反应试剂离子（（C₃H₆O）_nH⁺）（n=1,2）,与大气中的气态氨及其他碱性气体发生质子转移反应后进行质谱检测.丙酮（C₃H₆O）相较于水（H₂O）和乙醇（C₂H₅OH）,具有更高的质子亲和力（PA=194.1 kcal·mol^-1）,对PA较高的碱基化合物的选择性更好,可减少其他物质对四极杆质谱检测结果的影响.本研究在2017年11月9日—2018年1月10日和2018年11月12日—2019年1月2日华北地区气溶胶生成机理综合研究联合外场观测期间,将PTR-MS部署于山东省德州市平原县气象局观测场内,对大气中的氨气进行实时在线观测.结果表明,两次观测的气态氨平均值分别为（5.89±5.27）ppbv和（2.65±2.41）ppbv,均呈现出一个明显的日变化规律,即上午6：00—7：00出现峰值,随后逐渐下降,在下午大约15：00浓度达到最低值,随后上升.结合正交矩阵因子分解法（Positive Matrix Factorization,PMF）模型对当地近地面大气中氨气进行初步的来源分析,发现当地大气中氨气的来源主要是周边农村在冬季大量使用生物质燃料燃烧取暖造成的生活排放和当地交通源排放.两次冬季观测中当地农村取暖等生活排放分别占到66.0%和55.0%;交通排放在两次观测中分别占到27.0%和36.8%;农田土壤释放、畜牧养殖排放和工业排放等其他来源占比较低,分别是6.2%和7.5%;外部传输来源只占到很少一部分,分别是0.8%和0.7%.2018年的冬季观测相较于2017年,氨气浓度总体出现下降,主要来源还是以当地农村冬季生活和取暖燃烧排放为主,但通过相关政策管控,这一污染来源得到改善.     

Simultaneous Fe(III) reduction and ammonia oxidation process in Anammox sludge

In recent years, there have been a number of reports on the phenomenon in which ferric iron (Fe(III)) is reduced to ferrous iron [Fe(II)] in anaerobic environments, accompanied by simultaneous oxidation of ammonia to NO₂^-, NO₃^-, or N₂. However, studies on the relevant reaction characteristics and mechanisms are rare. Recently, in research on the effect of Fe(III) on the activity of Anammox sludge, excess ammonia oxidization has also been found. Hence, in the present study, Fe(III) was used to serve as the electron acceptor instead of NO₂^-, and the feasibility and characteristics of Anammox coupled to Fe(III) reduction (termed Feammox) were investigated. After 160days of cultivation, the conversion rate of ammonia in the reactor was above 80%, accompanied by the production of a large amount of NO₃^- and a small amount of NO₂^-. The total nitrogen removal rate was up to 71.8%. Furthermore, quantities of Fe(II) were detected in the sludge fluorescence in situ hybridization (FISH) and denaturated gradient gel electrophoresis (DGGE) analyses further revealed that in the sludge, some Anammox bacteria were retained, and some microbes were enriched during the acclimatization process. We thus deduced that in Anammox sludge, Fe(III) reduction takes place together with ammonia oxidation to NO₂^- and NO₃^- along with the Anammox process.     

气相分子吸收光谱法测定垃圾填埋场渗滤液中的氨氮研究

垃圾填埋场渗滤液成分复杂,其氨氮的测定干扰物质多,测定难度大.气相分子吸收光谱法是一种较为新兴的方法,通过对气相分子吸收光谱法和传统纳氏试剂分光光度法系统的比较,研究气相分子吸收光谱法测定垃圾填埋场渗滤液中氨氮的分析方法.结果表明,气相分子吸收光谱法测定垃圾填埋场渗滤液中氨氮操作便捷、干扰小、精密度好,中浓度与高浓度废水测定结果能较好的与纳氏试剂光度法测定结果法吻合,超低浓度废水的测定结果低于纳氏试剂分光光度法.为监测工作者分析方法的选择提供依据.     

A case study of development and application of a streamlined control and response modeling system for PM2.5 attainment assessment in China

This article describes the development and application of a streamlined air control and response modeling system with a novel response surface modeling-linear coupled fitting method and a new module to provide streamlined model data for PM_(2.5) attainment assessment in China.This method is capable of significantly reducing the dimensions required to establish a response surface model,as well as capturing more realistic response of PM_(2.5) to emission changes with a limited number of model simulations.The newly developed module establishes a data link between the system and the Software for Model Attainment Test—Community Edition(SMAT-CE),and has the ability to rapidly provide model responses to emission control scenarios for SMAT-CE using a simple interface.The performance of this streamlined system is demonstrated through a case study of the Yangtze River Delta(YRD) in China.Our results show that this system is capable of reproducing the Community Multi-Scale Air Quality(CMAQ) model simulation results with maximum mean normalized error 3.5%.It is also demonstrated that primary emissions make a major contribution to ambient levels of PM_(2.5) in January and August(e.g.,more than50%contributed by primary emissions in Shanghai),and Shanghai needs to have regional emission control both locally and in its neighboring provinces to meet China's annual PM_(2.5)National Ambient Air Quality Standard.The streamlined system provides a real-time control/response assessment to identify the contributions of major emission sources to ambient PM_(2.5)(and potentially O_3 as well) and streamline air quality data for SMAT-CE to perform attainment assessments.     

Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic (+ 3 oxidation state) methyltransferase-knockout mice

Arsenic methyltransferase(As3mt) catalyzes the conversion of inorganic arsenic(i As) to its methylated metabolites, including toxic methylarsonite(MAs~Ⅲ) and dimethylarsinite(DMAs~Ⅲ). Knockout(KO) of As3 mt was shown to reduce the capacity to methylate i As in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type(WT) mice exposed to arsenite(iA s~Ⅲ) in drinking water. WT mice were exposed to50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or30 mg/L As. iA s~Ⅲaccounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iA s and methylated arsenicals: iA s~Ⅲ, MAs~Ⅲand DMAs~Ⅲ represented 55%‐68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAs~Ⅲ, were found in the intestine of WT, but not As3mt-KO mice,suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iA s methylation in adverse effects of iA s exposure.     

城际铁路地下段运营振动对上部埋地燃气管道的影响

以某城际铁路下穿埋地燃气管道工程为例,应用车辆-轨道耦合动力学理论建立了车辆-轨道垂向耦合动力学模型,计算了250 km/h行车速度下的钢轨扣件支点反力;利用ANSYS建立了包括轨道、隧道结构、土体和燃气管道的三维有限元模型,以钢轨扣件反力为输入荷载,分析了列车运营条件下燃气管道的振动响应特性,并分析了会车对燃气管道振动响应特性的影响。结果表明,当列车单向运营速度为250 km/h时,燃气管道的最大振动加速度为1.175×10~(-3)m/s~2。如果在管道下方会车,列车运行振动对埋地燃气管道的影响范围显著增大,振动位移幅值和加速度幅值增幅分别为85.2%和75.8%,最大位移为2.21×10-5m,最大振动加速度为2.12×10~(-3)m/s~2。根据预测计算结果判断,本工程列车单向运营引起的埋地燃气管道的振动烈度小于I度,会车时振动烈度略大于I度。