霾不同发展阶段下污染气体和水溶性离子变化特征分析

为探讨霾不同阶段下大气污染物的变化特征,使用MARGA观测了2018年11月18日～12月7日长三角地区一次区域霾过程中前体污染气体(NH_3、HNO_3、SO_2)和8种水溶性离子浓度.结合环保数据(PM_(2.5)、NO_2、CO、O_3)和气象数据,分析此次区域霾过程的成因、大气污染物的日变化特征以及在霾不同阶段下大气污染物的分布特征.结果表明,此次霾过程中长三角地区主要受到高压脊控制,天气形势稳定,有利于大气污染物累积.霾天时PM_(2.5)、NO_2、NO_3-、SO_24-、NH_4+、Cl-和Na+的浓度分别为(118. 91±39. 23)、(61. 62±26. 34)、(45. 64±16. 01)、(18. 80±8. 02)、(20. 82±7. 16)、(3. 02±2. 25)和(0. 23±0. 22)μg·m-3,分别是干净天的2. 73、1. 63、2. 64、1. 94、2. 50、2. 05和2. 56倍;霾天CO的浓度为(1. 34±0. 39)mg·m-3,是干净天的1. 86倍.不同大气污染物的日变化特征不同.霾不同阶段下大气污染物的分布特征不同.SO_2的浓度在霾发生阶段最高; PM_(2.5)、NO_2、NH_3、CO和SNA的浓度在霾发展阶段最高; O_3、Cl-、Na+和K+的浓度在霾消散阶段最高.SNA在霾不同阶段下对PM_(2.5)的相对贡献可达94%～96%,且在发展阶段的增速最大,增速排序为NO_3- NH_4+ SO_24-. SNA在干净天、发生阶段和发展阶段以NH_4NO_3为主,在消散阶段(NH_4)2SO4为主.此次霾过程主要由NO_3-增长导致,NO_3-在霾发生、发展和消散阶段对PM_(2.5)的相对贡献分别为51. 06%、51. 85%和48. 22%,主要通过气相均相反应生成.     

Efficient adsorption of Mn(Ⅱ) by layered double hydroxides intercalated with diethylenetriaminepentaacetic acid and the mechanistic study

In this study, greatly enhanced Mn(II) adsorption was achieved by as-synthesized diethylenetriaminepentaacetate acid intercalated Mg/Al layered double hydroxides(LDHsDTPA). The adsorption capacity of LDHs-DTPA was 83.5 mg/g, which is much higher than that of LDHs-EDTA(44.4 mg/g), LDHs-Oxalate(21.6 mg/g) and LDHs(28.8 mg/g). The adsorption data of aqueous Mn(II) using LDHs-DTPA could be well described by the pseudosecond order kinetics and Langmuir isotherm model. Thermodynamics study results also showed that the adsorption process of Mn(II) by LDHs-DTPA was exothermic as indicated by the negative ΔH value. Furthermore, based on the structural, morphological and thermostable features, as well as FT-IR and XPS characterizations of LDHs-DTPA and the pristine LDHs, the adsorption mechanism of Mn(II) was proposed. The carboxyl groups of DTPA were proposed to be the main binding sites for Mn(II), and the hydroxyl groups of LDHs also played a minor role in the adsorption process. Among the three common regeneration reagents, 0.1 mol/L Na_2CO_3 was the best for reusing LDHs-DTPA in Mn(II)adsorption. Besides, the Mn(II) adsorption performance could be hindered in the presence of typical inorganic ions, especially cations. Further specific modifications of LDHs-DTPA are suggested to get more selective adsorption of Mn(II) in practical applications.     

纳米银和银离子对土壤中硝化微生物及其氨氧化速率的影响

为研究纳米银对土壤硝化微生物及其氮转化的影响,采用土壤培养方式,对不同剂量纳米银(10、50、100 mg·kg~(-1))和银离子(1、5、10 mg·kg~(-1))暴露下黄棕壤和水稻土硝化细菌数量、土壤酶活性、amoA基因丰度、NH_4~+-N与NO_3~--N含量变化以及土壤潜在氨氧化速率进行研究.结果表明,纳米银和银离子暴露后,2种土壤亚硝酸细菌和硝酸细菌数量显著减少;土壤酶活性受到抑制,对脲酶的影响大于过氧化氢酶;土壤氨氧化细菌(AOB)和氨氧化古菌(AOA)的amoA基因丰度均降低,对AOB基因丰度的影响大于AOA.在2种土壤中外源添加(NH_4)_2SO_4时,随着纳米银和银离子暴露剂量增加,土壤NH_4~+-N含量累积,NO_3~--N含量减少,氨氧化速率降低,铵态氮向硝态氮的转化受阻.综上所述,纳米银和银离子对土壤硝化微生物产生毒害作用并影响铵态氮转化,且影响程度与土壤理化性质有关.     

PVA降解混合菌系生长和产酶的营养条件分析

研究碳源、氮源以及不同金属离子对PVA降解混合菌系生长和产酶的影响。结果表明,混合菌系生长过程中无机氮源优于有机氮源;补充碳源可促进混合菌系的生长,但酶活比不添加时稍有降低。金属离子对酶活影响的正交实验表明Mg2＋浓度影响最大,其次是Fe2＋和K＋浓度,Ca2＋、Mn2＋、Zn2＋和Cu2＋浓度影响较小;最佳浓度分别为Mg2＋0.05 g/L、Fe2＋0.04 g/L、K＋2 g/L和Ca2＋0.05 g/L。     

室内空气中颗粒物污染特征研究

为获得室内空气颗粒物污染特征,2009年8月18～24日在某单位工作及生活区选取4个室内点和1个室外点进行颗粒物采样和成分分析.结果表明,室内粗颗粒(PM10)符合<室内空气质量标准>(GB/T 18883-2002),而细粒子(PM2.5)的浓度水平较高,表明室内PM2.5的污染较重;室内与室外PM2.5比值显示,P...     

Cobalt-induced oxidative stress in brain, liver and kidney of goldfish Carassius auratus

Cobalt is an essential element, but at high concentrations it is toxic. In addition to its well-known function as an integral part of cobalamin (vitamin B₁₂), cobalt has recently been shown to be a mimetic of hypoxia and a stimulator of the production of reactive oxygen species. The present study investigated the responses of goldfish, Carassius auratus, to 96 h exposure to 50, 100 or 150 mg L⁻¹ Co²⁺ in aquarium water (administered as CoCl₂). The concentrations of cobalt in aquaria did not change during fish exposure. Exposure to cobalt resulted in increased levels of lipid peroxides in brain (a 111% increase after exposure to 150 mg L⁻¹ Co²⁺) and liver (30-66% increases after exposure to 50-150 mg L⁻¹ Co²⁺), whereas the content of protein carbonyls rose only in kidney (by 112%) after exposure to 150 mg L⁻¹ cobalt. Low molecular mass thiols were depleted by 24-41% in brain in response to cobalt treatment. The activities of primary antioxidant enzymes, superoxide dismutase (SOD) and catalase, were substantially suppressed in brain and liver as a result of Co²⁺ exposure, whereas in kidney catalase activity was unchanged and SOD activity increased. The activities of glutathione-related enzymes, glutathione peroxidase and glutathione-S-transferase, did not change as a result of cobalt exposure, but glutathione reductase activity increased by ∼40% and ∼70% in brain and kidney, respectively. Taken together, these data show that exposure of fish to Co²⁺ ions results in the development of oxidative stress and the activation of defense systems in different goldfish tissues.     

酸性条件下剩余污泥中Ca2＋和Mg2＋溶出对磷回收的影响

为了在酸性条件下实现剩余污泥中磷的高效回收,对pH=3时剩余污泥水解酸化过程中氨氮、正磷酸盐和钙镁离子的溶出现象以及磷回收进行了研究分析。结果表明：当pH=3时,所溶出的氨氮、镁离子和钙离子与磷酸盐的摩尔比均大于1,能满足采用鸟粪石沉淀法或者羟磷灰石沉淀法回收磷的要求;但所溶出的钙镁离子的摩尔比大于1,会对鸟粪石沉淀法回收磷的顺利进行有较大影响;有无外加镁剂对磷回收率影响不大。采用改型后的镁型强酸性阳离子交换树脂进行离子交换可以得到较高纯度的鸟粪石沉淀产品,通过XRD检测其纯度为95％以上。     

集中空调系统积尘理化特征

利用现场采样与实验分析的方法,对集中空调系统内的积尘进行了粒径分布、水溶性碳物质及离子含量的分析,以评估集中空调系统内积尘对微生物滋生的影响.结果表明,集中空调系统除新风段外的6个采样段,积尘平均粒径介于6—20μm之间,新风段积尘平均粒径为41.30μm;沿送风方向,微粒的平均粒径减小,单位积尘量所含的水溶性离子和有...     

光照下铜离子对水中氢氧自由基生成量的影响

研究了水溶液中铜离子与抗坏血酸、柠檬酸盐及藻等配合体系在高压汞灯光照下产生氢氧自由基的情况,其中铜与抗坏血酸系统反应最强,高压汞灯光照增强了铜与抗坏血酸反应产生氢氧自由基的过程,高压汞灯光照时所产生的自由基量为不光照时的6～7倍。同时铜(或抗坏血酸)单一的水溶液在光照条件下也能产生氢氧自由基。铜离子与柠檬酸钠溶液混合在光照下能产生氢氧自由基;铜离子与藻液混合能加倍藻液中氢氧自由基的产生。     

安阳市大气PM2.5中水溶性离子季节特征及来源解析

为探究安阳市大气PM_2.5中水溶性离子的污染特征及其来源,于2018～2019年的典型月份在安阳市采集PM_2.5样品,使用离子色谱测试了9种水溶性离子(Na⁺、NH₄⁺、K⁺、Mg²⁺、Ca²⁺、F^-、Cl^-、NO₃^-和SO₄^2-).开展了PM_2.5和水溶性离子浓度水平的分析、阴阳离子平衡和氮氧化率(NOR)、硫氧化率(SOR)的计算、离子相关性和主成分分析等.结果表明,安阳市PM_2.5和水溶性离子年均浓度分别为(85.81±45.43)μg·m^-3和(48.21±30.04)μg·m^-3,各离子浓度高低顺序为NO₃^->SO₄...