城市森林大气PM2.5中水溶性无机离子沉降特征

森林被誉为"地球之肺",在防霾治污方面有其独特不可替代的作用,不同树种沉降PM_2.5的功能有很大差别.本文选取代表性城市森林——奥林匹克森林公园为研究对象,设置垂直监测塔观测大气PM_2.5的浓度垂直分布,以考察不同季节城市森林对PM_2.5中各组分的影响.在冬季、春季和夏季各采集PM_2.5样品,分析并计算PM_2.5中Na⁺、NH₄⁺、K⁺、Mg2⁺、Ca2⁺、Cl^-、NO₃^-和SO₄^2-等典型水溶性无机离子的浓度.结果表明,PM_2.5中水溶性无机离子总浓度呈规律性变化特征:冬季((56.90±27.38)μg·m-3)>春季((46.69±12.24)μg·m^-3)>夏季((23.16±8.75)μg·m^-3).其中SO₄^2-和NO₃^-浓度和占PM_2.5主要水溶性无机离子总浓度的50%以上.3个季节中,除冬季外,在春季和夏季,8种离子有明显的垂直方向上的沉降,夏季的沉降速率高于春季,但是春季由于大气颗粒物浓度高,沉降通量高于夏季.NO₃^-和SO₄^2-垂直方向的沉降量在所有可溶性无机离子中最高.植被密度、叶面积指数、气象条件等因素对于PM_2.5的沉降特征有明显影响.     

安阳市夏季道路积尘水溶性离子污染特征及来源分析

为了解安阳市夏季道路积尘水溶性离子污染特征及来源，于2020年5月使用手持式便携吸尘器采集70个城市道路积尘样品，经离子色谱仪测定其中10种水溶性离子(F^-、Cl^-、NO₂^-、NO₃^-、SO₄^2-、K⁺、Na⁺、Ca²⁺、Mg²⁺、NH₄⁺)，用比值分析法和相关性分析法分析其污染特征，结合地理统计分析和正定矩阵模型判断其主要来源.结果表明，Ca²⁺、SO₄^2-、NO₃^-、Cl^-、K⁺在安阳市道路积尘水溶性离子中占比较大，其中Ca²⁺占比最高，SO₄^2-和NO_...     

2018年成都市PM2.5中水溶性无机离子污染特征及来源解析

为了探究成都市PM_2.5水溶性无机离子的污染特征与来源贡献,于2018年1月1日—12月31日利用高分辨率的MARGA对PM_2.5组分展开在线监测,结合同一点位的气态污染物、气象参数监测数据进行分析.结果表明,水溶性无机离子与PM_2.5具有相同的月变化趋势,水溶性无机离子月均浓度为10.35-39.60μg·m^-3,在PM_2.5中的占比为31%—51%,水溶性无机离子是PM_2.5的重要组成部分.NO₃^-在水溶性无机离子中月均占比以12月最高,8月最低,SO₄^2-刚好与之相反.大气长期处于富氨状态,二次离子主要以（NH₄）₂SO₄、NH₄NO₃、NH₄Cl的形式存在,SOR在冬季12月与夏季8月分别出现高值0.61与0.5,但NOR只在冬季出...     

宝鸡市秋季清洁和污染时段水溶性离子污染特征及来源解析

为探究宝鸡市秋季大气PM_2.5中水溶性离子的污染特征及来源,于2019年10月15日至11月14日分别对宝鸡市监测站、文理学院和陈仓区环保局的3个站点进行PM_2.5样品采集,通过离子色谱仪得到水溶性离子质量浓度,分析了3个站点水溶性离子在清洁时段和污染时段的变化特征及来源.结果表明,三站点PM_2.5的质量浓度陈仓区环保局>文理学院>宝鸡市监测站.清洁时段和污染时段PM_2.5平均质量浓度分别为40.0μg·m^-3和100.1μg·m^-3,水溶性离子平均质量浓度分别为（13.7±7.7）μg·m^-3和（57.8±15.0）μg·m^-3.污染时段NO₃-/SO₄2-值是清洁时段的1.6—1.8倍.污染越重,SNA（NO₃-、SO₄2-和NH₄⁺）质量浓度越大,占总水溶性离子和P...     

疫情常态化管控下济南市春节前后PM2.5中二次组分变化特征

为研究新冠肺炎疫情常态化管控下,济南市春节前后PM_2.5中二次组分的变化特征、气粒分配规律及其影响因素,本文对2021年2月1-27日春节前、春节期间和春节后的3个时段济南市区在线监测的水溶性离子、碳组分及气态前体物质量浓度小时数据进行分析.结果表明,2021年疫情常态化管控下济南市春节前后二次组分浓度与2020年同比均明显下降,ρ(NO₃^-)、ρ(SO₄^2-)、ρ(NH₄⁺)和ρ(SOA)分别下降53.09%、58.32%、51.17%和61.84%,其中二次无机组分(NO₃^-、SO₄^2-、NH₄⁺之和)和SOA在PM_2.5中的占比分别为54.07%和8.20%,春节期间PM_2.5及二次组分在10—18时浓度较低,与春节期间白天人为活动相对减少,机动车、建筑工...     

川南四座城市PM2.5化学组分污染特征及其源解析

为探究川南地区大气气溶胶中化学组分与来源特征,于2015年9月—2016年8月在四川盆地南部4个典型代表城市(泸州、内江、宜宾、自贡)采集了226个PM_2.5样品,对PM_2.5的质量浓度和主要化学组分(水溶性离子和碳质组分)进行测定,并利用颗粒物源解析受体模型对PM_2.5来源进行解析.结果表明:川南地区PM_2.5日均浓度为46.4—68.0μg·m^-3,均高于国家环境空气质量标准年均PM_2.5限值(35.0μg·m^-3).OC、EC和水溶性二次离子(SO₄^2-、NO₃-和NH₄+)分别占PM_2.5质量的15.7%—22.8%、4.2%—6.4%和28.6%—55.8%.PM_2.5及其主要化学组分浓度有显著的季节变化,即冬季浓度显著高于其他季节,夏季浓度最低.泸州除夏季外,其他季节SO₄2-、NO₃-同源性较好;其他城市在冬季,SO₄2-、NO₃-同源性较好.NH₄+主要存在形式为NH₄NO₃、(NH₄)2SO₄、NH₄HSO₄.OC、EC来源复杂,主要为机动车源、煤燃烧源和生物质燃烧源.川南地区PM_2.5的来源主要受8种因子影响,按总体贡献排序依次为:二次硫酸盐、生物质燃烧、工业源、二次硝酸盐、机动车源、煤燃烧、道路尘埃和建筑尘埃.此外,相比较而言,机动车源贡献在泸州市较凸显,煤燃烧源贡献在宜宾市较凸显.     

南疆咸水结冰与融化过程中盐分及离子的变化

咸水淡化是缓解淡水资源紧张,减轻水体污染的有效途径.本试验分析了南疆农田排水不同冷冻温度下,结冰与融化过程中矿化度及离子浓度的分布规律;探讨了基于多级冷冻与重力脱盐条件下,盐分及Cl^-、 SO₄^2-、K⁺、Na⁺的迁移规律成因.试验结果表明,冰融水矿化度与离子浓度随冷冻温度的降低而上升;不同温度处理下,各级冰融水矿化度与离子浓度相较于初始水样（F₀）均显著降低（P<0.05）,冰晶逐级冷冻过程中,冰融水矿化度与离子浓度逐渐升高;各离子进入冰晶的迁移速率存在差异,离子结冰比率拟合线斜率呈K⁺> Cl^->Na⁺>SO₄^2-的分布规律.冰晶逐级融化过程中,冰融水矿化度、Cl^-、K⁺、Na⁺浓度呈现先快速下降、后缓慢下降、最终趋于平稳的变化趋势;SO₄     

MBR处理不同浓度高硫酸盐有机废水效能比较

针对食品加工过程中产生的高SO₄^2-有机物废水,采用MBR工艺对其进行处理研究,分别考察了1.6%和2.6%SO₄^2-浓度下反应器容积负荷和污染物去除情况.经过110天的运行时间发现,进水SO₄^2-浓度为1.6%的系统能获得更高的容积负荷和污染物去除效率,其最大容积负荷为1.0 kg·(m³·d)^-1COD,COD去除率为97.7%;而另一方面较高的无机盐环境进水SO₄^2-浓度为2.6%SO₄^2-系统下,获得的最大容积负荷仅为0.5 kg·(m³·d)^-1(按COD算),COD去除率为96.4%.在2.6%SO₄^2-浓度下,微生物受到的抑制更强,有机物降解效果低于1.6%SO₄^2-的系统.此外,氨...     

济南市PM2.5中二次组分的时空变化特征及其影响因素

为分析济南市PM_2.5中二次组分的时空变化和影响因素,对济南市春季(2019年5月16—25日)、秋季(2019年10月15—24日)和冬季(2019年12月17—2020年1月16日)4个典型点位的PM_2.5样品进行连续采样,并测定了PM_2.5中水溶性离子、有机碳(OC)和元素碳(EC)的含量。结果表明:物流交通区的二次组分质量浓度最高(56.13μg·m^?3),钢铁工业区的二次组分浓度比城市市区高,但是二次组分占比较城市市区低,清洁对照点的浓度和占比最低;济南市4个功能区SO₄^2?和NO₃^?转化率均高于0.1,除清洁对照点外,城市市区、钢铁工业区和物流交通区的SO₄^2?转化率明显高于NO₃^?转化率;济南市春季、秋季和冬季的ρ(NO₃^?)/ρ(SO₄^2?)分别为0.67、2.57和1.98,春季PM_2.5浓度以固定源贡献为主,秋季和冬季以移动源贡献为主;运用ISORROPIA热力学模型分析了含水量和pH对二次组分生成的影响,含水量会随着污染增大而增大,酸度和含水量对二次无机组分的转化机理产生影响,酸度会抑制二次无机组分的生成,而含水量会促进二次组分的生成;后向轨迹聚类分析结果表明,占比最高的轨迹(29.2%)来自东北方向的滨州和东营,基于潜在源贡献因子(WPSCF)和浓度权重轨迹(WCWT)分析PM_2.5中二次组分质量浓度的潜在污染源区域,SO₄^2?的主要贡献源区在济南市区北部的济阳区和东北方向的滨州、东营等,NO₃^?和NH₄⁺的主要贡献源区在济南市区北方向的济阳区、东北方向的章丘区和南方向的莱芜区等。该研究结果可为中国北方城市细颗粒物进一步的治理和防控提供数据支撑和理论依据。     

氯酸盐屏蔽废水COD测定的消除策略及反应机制

向废水中投加氯酸盐,即所谓的“COD(化学需氧量)去除剂”,可降低COD检测值,呈现出水符合COD排放标准的假象.从本质上而言,氯酸盐的添加并未实际去除COD,而仅仅是作为氧化剂减少了在高温消解过程中重铬酸钾的消耗量,导致测定的COD数值偏小,因此氯酸盐只是起到了掩蔽作用.为消除氯酸盐对COD的掩蔽作用,提出了一种以亚硫酸盐为还原剂的预处理工艺:根据氯酸盐含量投加相应的亚硫酸氢钠进行去除,进而测定出真实的COD.结果表明,当[SO₃^2-]/[ClO₃^-]摩尔比为5—6、温度为60℃时,经过lh的反应可以有效的消除氯酸盐对COD测定的影响,此时SO₃^2-和ClO₃^-同步耗尽.基于ESR(电子自旋共振)分析,可知氯酸盐与亚硫酸盐首先通过单电子转移反应生成SO₃^·-,生成的SO₃·与溶解氧进一步发生反应生成SO₄^·-     

乌鲁木齐市米东区大气降水的化学特征及来源分析

为研究乌鲁木齐市米东区大气降水中的化学组分特征及来源,对2017-2019年降水中主要离子浓度及来源进行了分析.研究结果显示,米东区2017-2019年降水的雨量加权pH年均值为7.95,雨量加权平均电导率年均值为16.15 mS·m-1,雨量加权平均总离子浓度为72.75-95.89 μeq·L-1,年均浓度为81....     

辽宁西南典型城市冬季大气细颗粒物水溶性无机离子污染特征及来源解析

本研究于2018年12月3日-2019年1月1日在辽宁省西南典型城市葫芦岛市和朝阳市分别布设3个城区采样点,在区域传输点龙屯水库布设1个采样点,采集大气细颗粒物PM2.5样品(n=201).使用离子色谱检测样品中的Na+、Mg2+、Ca2+、K+、NH4+、SO42-、F-、Cl-和NO3-的质量浓度.观测期间PM2....     

球磨零价镁/石墨(ZVMg/C)降解水中三氯乙烯

利用机械球磨法制备了零价镁/石墨(ZVMg/C)材料,并将其用于水溶液中三氯乙烯(TCE)的降解。研究通过SEM、BET和XRD等分析手段解析了ZVMg/C的表面形态结构和成分组成;采用正交实验方法优化了ZVMg/C的制备参数,比较了石墨含量对材料性能的影响;并考察了ZVMg/C投加量、溶液初始pH和地下水中常见阴(Cl^-、SO₄^2-、HCO₃^-、NO₃^-)、阳(Fe³⁺、Cu²⁺)离子与ZVMg/C降解TCE的构效关系。研究结果表明,球磨转速和球磨时间是决定ZVMg/C还原能力的两个主要控制参数;ZVMg/C对TCE的降解主要发生在反应的前2 h内,当ZVMg/C投加量为0.2 mol·L^-1时,表面积归一化速率常数(KSA)达到最大为1.31×10^-1 L·h^-1·m^-2;溶液初始pH和常见阴离子对ZVMg/C降解TCE的影响相对较小;而溶液中的Fe³⁺或Cu²⁺能够被ZVMg/C原位还原成金属单质并与ZVMg组成双金属体系促进TCE的还原降解。     

Deciphering the effect of sodium dodecylbenzene sulfonate on up-flow anaerobic sludge blanket treatment of synthetic sulfate-containing wastewater

• UASB reactor can work efficiently with high COD/SO₄^2- ratios when SDBS exists. • Outcome of the competition between SRB and MPA was affected by SDBS. • Presence of SDBS makes methanogens with H₂/CO₂ as a substrate dominant. • Microbial diversity decreases in the presence of SDBS. In this study, the effects of organic sulfur on anaerobic biological processes were investigated by operating two up-flow anaerobic sludge blanket (UASB) reactors with sodium dodecylbenzene sulfonate (SDBS) as a representative of organic sulfur. The results indicated that the specific methanogenic activity (SMA) and chemical oxygen demand (COD) removal efficiency of R2 (with SDBS added) were higher than those of R1 (without SDBS) when the COD/SO₄²⁻ ratio was above 5.0. However, when the COD/SO₄²⁻ ratio was lower than 5.0, the sulfate reduction efficiency of R2 was higher than that of R1. These results and the observed SDBS transformation efficiency in anaerobic reactors indicate that low concentrations of SDBS accelerate methane production and the continuous accumulation of SDBS does not weaken the reduction of sulfate. Similarly, the calculated electron flux for a COD/SO₄²⁻ ratio of 1.0 indicates that the utilization intensity of electrons by sulfate-reducing bacteria (SRB) in R2 was 36.48% higher than that of SRB in R1 and exceeded that of methane-producing archaea (MPA) under identical working conditions. Moreover, the addition of SDBS in R2 made sulfidogenesis the dominant reaction at low COD/SO₄²⁻, and Methanobacterium and Methanobrevibacter with H₂/CO₂ as the substrate and Desulfomicrobium were the dominant MPA and SRB, respectively. However, methanogenesis was still the dominant reaction in R1, and Methanosaeta with acetic acid as the substrate and Desulfovibrio were the dominant MPA and SRB, respectively.     

Scrap Iron Filings assisted nitrate and phosphate removal in low C/N waters using mixed microbial culture

• Microbes enhance denitrification under varying DO concentrations and SIF dosages. • Abiotic nitrate reduction rates are proportional to SIF age and dosage. • Over 80% of the simultaneously loaded NO₃⁻-N and PO₄³⁻ is removed biologically. This study focuses on identifying the factors under which mixed microbial seeds assist bio-chemical denitrification when Scrap Iron Filings (SIF) are used as electron donors and adsorbents in low C/N ratio waters. Batch studies were conducted in abiotic and biotic reactors containing fresh and aged SIF under different dissolved oxygen concentrations with NO₃⁻-N and/or PO₄^3- influent(s) and their nitrate/phosphate removal and by-product formations were studied. Batch reactors were seeded with a homogenized mixed microbial inoculum procured from natural sludges which were enriched over 6 months under denitrifying conditions in the presence of SIF. Results indicated that when influent containing 40 mg/L of NO₃⁻-N was treated with 5 g SIF, 79.9% nitrate reduction was observed in 8 days abiotically and 100% removal was accomplished in 20 days when the reactor was seeded. Both abiotic and seeded reactors removed more than 92% PO₄³⁻ under high DO conditions in 12 days. Abiotic and biochemical removal of NO₃⁻-N and abiotic removal of PO₄³⁻ were higher under independent NO₃⁻-N/PO₄³⁻ loading, while 99% PO₄^3- was removed biochemically under combined NO₃⁻-N and PO₄³⁻ loading. This study furthers the understandings of nitrate and phosphate removal in Zero Valent Iron (ZVI) assisted mixed microbial systems to encourage the application of SIF-supported bio-chemical processes in the simultaneous removals of these pollutants.     

Unveiling the interaction mechanisms of key functional microorganisms in the partial denitrification-anammox process induced by COD

● The availability of PD-anammox was investigated with higher NO₃^––N concentration. ● NO₃^––N concentration affects NO₃^––N accumulation during denitrification. ● COD concentration is determinant for N removal pathways in PD-anammox process. ● The synergy/competition mechanisms between denitrifiers and anammox was explored. Partial denitrification-anammox (PD-anammox) is an innovative process to remove nitrate (NO₃^––N) and ammonia (NH₄⁺–N) simultaneously from wastewater. Stable operation of the PD-anammox process relies on the synergy and competition between anammox bacteria and denitrifiers. However, the mechanism of metabolic between the functional bacteria in the PD-anammox system remains unclear, especially in the treatment of high-strength wastewater. The kinetics of nitrite (NO₂^––N) accumulation during denitrification was investigated using the Michaelis-Menten equation, and it was found that low concentrations of NO₃^––N had a more significant effect on the accumulation of NO₂^––N during denitrification. Organic matter was a key factor to regulate the synergy of anammox and denitrification, and altered the nitrogen removal pathways. The competition for NO₂^––N caused by high COD concentration was a crucial factor that affecting the system stability. Illumina sequencing techniques demonstrated that excess organic matter promoted the relative abundance of the Denitratesoma genus and the nitrite reductase gene nirS, causing the denitrifying bacteria Denitratisoma to compete with Cadidatus Kuenenia for NO₂^––N, thereby affecting the stability of the system. Synergistic carbon and nitrogen removal between partial denitrifiers and anammox bacteria can be effectively achieved by controlling the COD and COD/NO₃^––N.     

硫氮沉降下西北荒漠煤矿区周边土壤性质的变化特点

近年来中国大部分区域大气硫、氮沉降速率趋于平稳甚至下降,但西北地区煤炭行业的快速发展使得硫、氮沉降速率加快.燃煤电厂作为酸前体物的主要排放源之一,在其周围开展硫、氮沉降效应研究,可为合理评价煤矿区大气污染物控制措施的实施效果提供数据支撑.该文以宁东能源化工基地3个燃煤电厂为采样点,研究了电厂周围土壤化学和生物学性质的变...     

Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes

To investigate the nitrogen transport and conversion inside activated sludge flocs, micro-profiles of O₂, NH₄⁺, NO₂^–, NO₃^–, and pH were measured under different operating conditions. The flocs were obtained from a laboratory-scale sequencing batch reactor. Nitrification, as observed from interfacial ammonium and nitrate fluxes, was higher at pH 8.5, than at pH 6.5 and 7.5. At pH 8.5, heterotrophic bacteria used less oxygen than nitrifying bacteria, whereas at lower pH heterotrophic activity dominated. When the ratio of C to N was decreased from 20 to 10, the ammonium uptake increased. When dissolved oxygen (DO) concentration in the bulk liquid was decreased from 4 to 2 mg·L^-1, nitrification decreased, and only 25% of the DO influx into the flocs was used for nitrification. This study indicated that nitrifying bacteria became more competitive at a higher DO concentration, a higher pH value (approximately 8.5) and a lower C/N.