江苏省一次典型沙尘污染过程分析

2021年4月16日至4月18日江苏省经历了一次受沙尘影响的重污染过程.本次过程沙源地为蒙古国中南部及中国内蒙古中西部地区,在蒙古气旋后部西北大风影响下,沙尘气团自西北向东南影响了中国多个省市和地区.江苏省自16日起逐渐受到沙尘过程影响,苏北城市ρ(PM10)从凌晨开始迅速升高,浓度最高达569μg/m3,空气质量达严重污染级别.17日,受蒙古气旋后部冷高压带来的偏北风影响,沙尘气团位置明显南移,多数沿江城市PM10开始上升,空气质量达中度污染级别.至17日夜间,本次影响江苏省的沙尘过程基本结束.沙尘影响期间,江苏各市不仅ρ(PM10)浓度快速上升,同时ρ(PM2.5)/ρ(PM10)比值也明显下降,由受沙尘影响前的介于0.60～0.75之间迅速降至介于0.15～0.23之间.     

磁性纳米Fe3O4@C对SBR脱氮除磷性能及其微生物种群组成的影响

为探究磁性纳米Fe₃O₄@C对序批式活性污泥反应器（SBR）污水处理系统脱氮除磷性能的影响,建立了2个相同的SBR（编号分别为0号和1号）,其中,0号反应器未投加任何磁性材料（对照组）,1号反应器中投加0.5 g·L^-1的Fe₃O₄@C（实验组）,并采用高通量测序和实时定量PCR（qPCR）技术对2个反应器内生物种群结构及关键脱氮除磷功能菌群进行分析.结果表明：①Fe₃O₄@C对SBR除污性能有显著影响,其中,1号反应器化学需氧量（COD）的去除性能得到增强,24 d后去除率稳定在90%左右;0号和1号反应器总氮（TN）平均去除率分别为35.83%和52.18%;从第43 d起,1号反应器除磷性能明显高于0号反应器,运行70 d后,0号和1号反应器对总磷（TP）的平均去除率分别为47.52%和56.33%.②添加Fe₃O₄@C材料后,反应器内变形菌门（Proteobacteria）的相对丰度从23.91%增加至32.14%,优势脱氮菌门Planctomycetes、Nitrospirae的相对丰度分别从2.66%、0.46%增加至5.16%、2.23%.③添加Fe₃O₄@C后,SBR内细菌总数明显增多,16S基因拷贝数从1.77×10⁷ copies·g^-1增长到4.21×10⁷ copies·g^-1;各功能菌数量也有大幅度增长,除磷功能基因PAO增加了3.4倍,脱氮功能基因nirS、Nitrospira、Nitrobacter、AOB分别增长了2.3、2.4、4.7和572倍.研究表明,磁性纳米Fe₃O₄@C能有效促进SBR脱氮除磷性能,可为SBR工艺的优化改进提供理论支撑.     

海拉尔盆地地下水铀的分布特征及富集规律

通过采集海拉尔盆地地表水样品12件,地下水样品67件,运用Durov图、等值线图和铀形态计算理论,结合数理统计方法,分析研究区域地下水铀的分布特征和赋存形态,结果表明:海拉尔盆地赫尔洪德凹陷地区主要为HCO₃-Ca·Na型,蹉岗隆起、乌尔逊凹陷和贝尔凹陷地区主要为Cl-Na型和HCO₃-Na型,巴彦山隆起地区主要为HCO₃-Na型,红旗牧场和新宝力格凹陷主要为Cl-Na型.研究区域铀的分布范围为17~425μg/L,平均值为80μg/L,标准偏差为70μg/L,引发了区域地源性地下水铀污染问题.地下水中以UO₂(CO₃)₃^4-和UO₂(CO₃)₂^2-的主要形式存在,与Eh表现的氧化还原环境具有一致性,其中呼伦贝尔湖东南部属于地下水铀成矿有利区域.潜在铀成矿范围属于重碳酸铀酰占优势的HCO₃型含铀地下水,铀酰碳酸盐复合物应占主导地位,铀的溶解与HCO₃^-的增加有关,地下水中的铀存在参与碳酸盐岩和硫酸盐岩的混合溶滤作用的可能性,UO₂(CO₃)₃^4-、UO₂(CO₃)₂^2-、U₄O₉和沥青铀矿等处于饱和状态,总Fe和(Ca²⁺+Mg²⁺)浓度较低,各种水化学指标对铀富集具有指示意义,因此可将其视为潜在铀源的参考依据.     

基于TEM-EDS对四川盆地大气单颗粒气溶胶的研究

为了解四川盆地大气中单颗粒气溶胶理化特征,分别在该区域典型城市（成都市）和背景地区（峨眉山）进行了大气单颗粒样品采集.基于带能谱的透射电子显微镜（TEM-EDS）对两地累计3923个单颗粒的化学组成、形貌特征及混合状态等进行了全面观测和分析,并对两地颗粒物差异性进行了对比分析.结果发现：两地气溶胶颗粒主要包括有机物、富硫、矿物、烟尘和飞灰/金属颗粒,除了以单独的外混形式存在外,大多数颗粒以两种及两种以上颗粒类型混合（即内混）形式存在.通过对成都市不同污染状况下单颗粒特征对比发现,"污染天"的内混颗粒占比高于"清洁天",分别为74.2%和68.6%;相比"清洁天","污染天"颗粒物粒径分布范围更广且峰值区间更大,表明污染过程中颗粒物的大气混合趋于更强.对比成都市与峨眉山分析结果得知,成都市以内混的有机物-硫颗粒为主导（占比为50.2%）,而峨眉山以外混的有机物颗粒为主导（占比为50.5%）;成都市含硫类颗粒物（如有机物-硫颗粒）贡献高于峨眉山,而峨眉山两种含碳类颗粒（如烟尘和有机物-烟尘颗粒）占比高于成都市;此外,成都市与峨眉山两地大气颗粒物粒径分布范围及峰值区间均存在一定差异,进一步体现了两地颗粒物来源和老化混合的差异.在峨眉山,与非降雨天相比,一些易溶于水的颗粒物（如含硫类颗粒）在降雨天占比明显降低,而源自当地燃烧过程、粒径较小且疏水性强的颗粒物（如烟尘和有机物-烟尘颗粒）占比相应升高.     

Comprehensive and high-resolution emission inventory of atmospheric pollutants for the northernmost cities agglomeration of Harbin-Changchun, China: Implications for local atmospheric environment management

Using a bottom-up estimation method, a comprehensive, high-resolution emission inventory of gaseous and particulate atmospheric pollutants for multiple anthropogenic sectors with typical local sources has been developed for the Harbin-Changchun city agglomeration (HCA). The annual emissions for CO, NOx, SO₂, NH₃, VOC_S, PM_2.5, PM₁₀, BC and OC during 2017 in the HCA were estimated to be 5.82 Tg, 0.70 Tg, 0.34 Tg, 0.75 Tg, 0.81Tg, 0.67 Tg, 1.59 Tg, 0.12 Tg and 0.26 Tg, respectively. For PM₁₀ and SO₂, the emissions from industry processes were the dominant contributors representing 54.7% and 49.5%, respectively, of the total emissions, while 95.3% and 44.5% of the total NH₃ and NOx emissions, respectively, were from or associated with agricultural activities and transportation. Spatiotemporal distributions showed that most emissions (except NH₃) occurred in November to March and were concentrated in the central cities of Changchun and Harbin and the surrounding cities. Open burning of straw made an important contribution to PM_2.5 in the central regions of the northeastern plain during autumn and spring, while domestic coal combustion for heating purposes was significant with respect to SO₂ and PM_2.5 emissions during autumn and winter. Furthermore, based on Principal Component Analysis and Multivariable Linear Regression model, air temperature, relative humidity, electricity and energy consumption, and the urban and rural population were optimized to be representative indicators for rapidly assessing the magnitude of regional atmospheric pollutants in the HCA. Such indicators and equations were demonstrated to be useful for local atmospheric environment management.     

Spatiotemporal variations of ambient air pollutants and meteorological influences over typical urban agglomerations in China during the COVID-19 lockdown

To investigate the air quality change during the COVID-19 pandemic, we analyzed spatiotemporal variations of six criteria pollutants in nine typical urban agglomerations in China using ground-based data and examined meteorological influences through correlation analysis and backward trajectory analysis under different responses. Concentrations of PM_2.5, PM₁₀, NO₂, SO₂ and CO in urban agglomerations respectively decreased by 18%–45% (30%–62%), 17%–53% (22%–39%), 47%-64% (14%–41%), 9%–34% (0%–53%) and 16%-52% (23%–56%) during Lockdown (Post-lockdown) period relative to Pre-lockdown period. PM_2.5 pollution events occurred during Lockdown in Beijing-Tianjin-Hebe (BTH) and Middle and South Liaoning (MSL), and daily O₃ concentration rose to grade Ⅱ standard in Post-lockdown period. Distinct from the nationwide slump of NO₂ during Lockdown period, a rebound (～40%) in Post-lockdown period was observed in Cheng-Yu (CY), Yangtze River Middle-Reach (YRMR), Yangtze River Delta (YRD) and Pearl River Delta (PRD). With slightly higher wind speed compared with 2019, the reduction of PM_2.5 (51%–62%) in Post-lockdown period is more than 2019 (15%–46%) in HC (Harbin-Changchun), MSL, BTH, CP (Central Plain) and SP (Shandong-Peninsula), suggesting lockdown measures are effective to PM_2.5 alleviation. Although O₃ concentrations generally increased during the lockdown, its increment rate declined compared with 2019 under similar sunlight duration and temperature. Additionally, unlike HC, MSL and BTH, which suffered from additional (> 30%) air masses from surrounding areas after the lockdown, the polluted air masses reaching YRD and PRD mostly originated from the long-distance transport, highlighting the importance of joint regional governance.     

Effective adsorption of quadrivalent cerium by synthesized laurylsulfonate green rust in a central composite design

The layered laurylsulfonate intercalated green rust (lauryl-S GR) was synthesized to evaluate the influence of synthesis parameters and aqueous conditions on the adsorption of Ce^IV. The maximum adsorption capacity of 305.58 mg/g by lauryl-S GR was predictably obtained. The pseudo-first-order kinetic model was appropriate in fitting the whole uptake process in a weak acid environment. Three isotherm models including Langmuir, Freundlich, and Tempkin were all reliable in depicting the isotherm adsorption process. The maximum monolayer adsorption capacity of lauryl-S GR towards Ce^IV was 315.46 mg/g. Ce species including CeO and Ce₂O₃ besides CeO₂ were matched in the XPS distribution, directly indicating the reduction reaction brought by Fe^II in the GR occurred to hydrated Ce^IV ions during the adsorption. Nano-sized Ce particles attached to the lauryl-S GRs after the adsorption experiments were observed in the morphological characterization. Flocculated materials were formed on the surface of the lauryl-S GR at a pH of 7, which further reduced the active sites and disrupted the continuous uptake of Ce^IV to the lauryl-S GR. This study expands the application of GRs and supplies an ideal iron-based material for the construction of the affiliated recovery pathway to the traditional separation of Ce.     

Chemical characteristics, oxidative potential, and sources of PM2.5 in wintertime in Lahore and Peshawar, Pakistan

The chemical characteristics, oxidative potential, and sources of PM_2.5 were analyzed at the urban sites of Lahore and Peshawar, Pakistan in February 2019. Carbonaceous species, water soluble ions, and metal elements were measured to investigate the chemical composition and sources of PM_2.5. The dithiothreitol (DTT) consumption rate was measured to evaluate the oxidative potential of PM_2.5. Both cities showed a high exposure risk of PM_2.5 regarding its oxidative potential (DTT_v). Carbonaceous and some of the elemental species of PM_2.5 correlated well with DTT_v in both Lahore and Peshawar. Besides, the DTT_v of PM_2.5 in Lahore showed significant positive correlation with most of the measured water soluble ions, however, ions were DTT-inactive in Peshawar. Due to the higher proportions of carbonaceous species and metal elements, Peshawar showed higher mass-normalized DTT activity of PM_2.5 compared to Lahore although the average PM_2.5 concentration in Peshawar was lower. The high concentrations of toxic metals also posed serious non-carcinogenic and carcinogenic risks to the residents of both cities. Principle component analysis coupled with multiple linear regression was applied to investigate different source contributions to PM_2.5 and its oxidative potential. Mixed sources of traffic and road dust resuspension and coal combustion, direct vehicle emission, and biomass burning and formation of secondary aerosol were identified as the major sources of PM_2.5 in both cities. The findings of this study provide important data for evaluation of the potential health risks of PM_2.5 and for formulation of efficient control strategies in major cities of Pakistan.     

Synthesis and evaluation of cationic flocculant P(DAC-PAPTAC-AM) for flocculation of coal chemical wastewater

In this study, a high-efficiency cationic flocculant, P(DAC-MAPTAC-AM), was successfully prepared using UV-induced polymerization technology. The monomer Acrylamide (AM): Acryloxyethyl Trimethyl ammonium chloride (DAC): methacrylamido propyl trimethyl ammonium chloride (MAPTAC) ratio, monomer concentration, photoinitiator concentration, urea content, and cationic monomer DAC:MAPTAC ratio, light time, and power of high-pressure mercury lamp were studied. The characteristic groups, characteristic diffraction peaks, and characteristic proton peaks of P(DAC-MAPTAC-AM) were confirmed by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), ¹H nuclear magnetic resonance spectrometer (¹H NMR), and scanning electron microscopy (SEM). The effects of dosage, pH value, and velocity gradient (G) value on the removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol by poly aluminum ferric chloride (PAFC), P(DAC-MAPTAC-AM), and PAFC/P(DAC-MAPTAC-AM) in the flocculation treatment of coal chemical wastewater were investigated. Results showed that the optimal conditions for the flocculation of coal chemical wastewater using P(DAC-MAPTAC-AM) alone are as follows: dosage of 8–12 mg/L, G value of 100–250 s ^? 1, and pH value of 4–8. The optimal dosage of PAFC is 90–150 mg/L with a pH of 2–12. The optimal dosage for PAFC/P(DAC-MAPTAC-AM) is as follows: PAFC dosage of 90–150 mg/L, P(DAC-MAPTAC-AM) dosage of 8–12 mg/L, and pH range of 2–6. When P(DAC-MAPTAC-AM) was used alone, the optimal removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol were 81.0%, 35.0%, 75.0%, and 80.3%, respectively. PAFC has good tolerance to wastewater pH and good pH buffering. Thus, the flocculation treatment of coal chemical wastewater using the PAFC/P(DAC-MAPTAC-AM) compound also exhibits excellent resistance and buffering capacity.     

Effects of chemical modification on physicochemical properties and adsorption behavior of sludge-based activated carbon

This study aimed to explore the adsorption performance of sludge-based activated carbon (SBC) towards dissolved organic matters (DOMs) removal from sewage, and investigated the modification effect of different types of chemicals on the structure of synthesized SBC. Waste activated sludge (WAS) was used as a carbon source, and HCl, HNO₃, and NaOH were used as different types of chemicals to modify the SBC. With the aid of chemical activation, the modified SBC showed higher adsorption performances on DOMs removal with maximum adsorption of 29.05 mg/g and second-order constant (k) of 0.1367 (L/mol/sec) due to the surface elution of ash and minerals by chemicals. The surface elemental composition of MSBC suggested that the content of C-C and C-O functional groups on the surface of modified sludge-based activated carbon (MSBC) played an important role on the adsorption capacities of MSBC towards DOMs removal in sewage. Additionally, the residual molecular weight of DOMs in sewage was investigated using a 3-dimension fluorescence excitation-emission matrix (3D-EEM) and high-performance size exclusion chromatography (HP-SEC). Results showed that the chemical modification significantly improved the adsorption capacity of MSBC on humic acids (HA) and aromatic proteins (APN), and both of NaOH-MSBC and HCl-MSBC were effective for a wide range of different AMW DOMs removal from sewage, while the HNO₃-MSBC exhibited poorly on AMW organics of 2,617 Da and 409 Da due to the reducing content of macropore. In brief, this study provides reference values for the impact of the chemicals of the activation stage before the SBCs application.