1970—2018年中国甲烷排放量时空分布特征及行业排放源分析

在100年时间尺度上,甲烷(CH₄)气体的全球增温潜势是CO₂的25倍,研究CH₄排放的时空特征及排放源组成结构对于国家"双碳目标"的实现具有重要价值.本文基于全球大气研究排放数据库(EDGAR)中的数据集,刻画了中国CH₄排放的时空分布特征,利用空间自相关和热点分析方法,揭示了CH₄排放的空间集聚效应,并基于不同的行业部门排放数据对CH₄的排放源进行分析.研究表明:1970—2018年CH₄排放的热点区主要分布在我国的华东、华北以及华南地区,有逐渐向西北地区延伸的趋势;年CH₄排放量平均值达8.33 t·a^-1·km^-2,变化曲线总体上呈现平缓上升—急速上升—稳定排放三个阶段;从各行政区的排放量来看,上海一直处于最高,全市排放量十年间平均值不低于25 t·km^-2;能源活动和工业生产的CH₄排放量贡献突出,尤其是交通运输和煤炭开采近些年排放占比逐渐攀升.     

藻型湖泊溶解有机碳特征及其对甲烷排放的影响

湖泊碳通量研究已成为全球碳循环研究的前沿和热点问题.本研究以太湖藻型湖区(西北湖区、梅梁湾、贡湖湾、西南湖区和湖心)为研究对象,基于为期一年的连续野外观测,旨在揭示富营养化湖泊DOC变化特征及其对CH₄排放的影响.结果表明,太湖藻型湖区DOC质量浓度均值为4.15 mg/L,且具有显著的空间变化.受外源输送和内部蓝藻增殖影响,西北湖区和梅梁湾DOC质量浓度较高,且其DOC时间变化与流域降雨量紧密相关,尤以西北湖区最为明显(R²=0.67,P<0.01).但在受外源输送影响较小的湖心区域,其DOC的时间变化主要受蓝藻生物量驱动(R²=0.60,P<0.01).太湖藻型湖区CH₄排放均值为0.083 mmol·m^-2·d^-1,不同湖区CH₄排放量差异明显.藻型湖区较高的蓝藻生物量显著提高了CH₄的排放量,且DOC含量是蓝藻影响CH₄产生和排放的主要因子.总体上,太湖藻型湖区DOC的累积致使其是CH₄排放的热点区域,但DOC对CH₄产生和排放的影响受湖泊内部因子和外部因子的综合调控,其潜在的控制机制还需要进一步探讨.     

海南岛甲烷浓度与关键气候因子的季节性关联特征

甲烷(CH₄)作为联合国气候报告着重强调防控的第二大温室气体,其季节性变化及与关键气候因子的关联特征对全球气候变化相关研究至关重要.本研究基于GHGSat甲烷浓度产品,解析以海南岛陆地为典型热带研究区的甲烷浓度季节性变化特征,同时厘定了海南岛甲烷浓度时空分布对关键气候因子等的敏感性,并基于增强回归树(Boosted Regression Trees,BRT)分析了非生物因子如气候和地形对甲烷浓度分布的贡献度,结果表明:1)海南岛甲烷浓度在时间上具有显著的季节性变化特征,即在4—8月呈显著下降趋势,在9—12月呈显著上升趋势,而甲烷浓度的空间分布也具有明显的区域差异性,即海岸线附近甲烷浓度较高,而甲烷浓度低值分布多集中于中部地区;2)甲烷浓度与关键气候因子的线性回归模型结果显示气温与甲烷浓度呈弱正相关,而降雨与甲烷浓度存在弱负相关关系;3) BRT模拟结果显示,三种非生物因子海拔、降雨和气温对甲烷浓度分布的贡献度分别71.95％、20.52％、5.66％.本研究可为解析关键气候因子对甲烷排放的贡献度提供科学依据.     

不同类型稻田亚硝酸型CH4厌氧氧化潜力的比较研究

甲烷(CH₄)厌氧氧化是稻田土壤中消减温室气体排放的重要过程.本试验选择内陆性南京稻田和滨海性上海崇明岛围垦稻田,比较研究稻田耕层(0~10 cm)和深层(50~60 cm)土壤中亚硝酸盐型CH₄厌氧氧化(n-DAMO)潜力的差异及其微生物驱动机制.结果表明,南京稻田耕层土壤的n-DAMO速率为3.51 nmol·g^-1·d^-1(以¹³CO₂计),显著高于围垦稻田耕层土壤(1.43 nmol·g^-1·d^-1).两种类型稻田耕层土壤的n-DAMO速率均显著高于深层土壤.南京稻田和围垦稻田M.oxyfera-like细菌的16S rRNA基因拷贝数分别为(2.31~4.82)×10⁷和(0.89~2.12)×10⁷ copies·g^-1,与亚硝酸盐型CH₄厌氧氧化速率显著正相关.相关性分析发现,土壤有机碳、总氮、无机态氮是稻田n-DAMO速率分异的重要原因.综上所述,内陆性稻田土壤n-DAMO氧化潜力较高,其主要由较高的土壤本底碳、氮水平和功能微生物丰度所致.     

美丽中国背景下云南省农业活动甲烷排放量计算与情景预测分析

运用CH4MOD模型和排放因子法对云南省农业活动CH₄排放量进行计算分析,并运用情景分析法对云南省农业活动CH₄排放量进行预测.研究结果表明:1)云南省2010—2019年农业源CH₄排放总量变化趋势为先波动上升再迅速减少最后趋于平稳,其中动物肠道发酵排放量贡献最大;2)云南省2010—2019年农业源CH₄单位农业增加值排放强度呈下降趋势,单位农地面积排放强度为波动状态;3)云南省2020—2029年不同情景下农业活动CH₄排放量预测均为上升趋势.由此从水稻种植和畜禽养殖两方面提出减排措施,以期实现"双碳"目标和美丽中国建设.     

SO2-4对块体纳米晶铜阳极极化行为的影响

为了揭示SO₂^-4对块体纳米晶铜耐蚀性能的影响规律,利用电化学方法,结合X射线衍射、能谱分析、扫描电镜等表面分析技术,研究了惰性气体沉积原位温压法制备的块体纳米晶铜在不同质量分数（0.3%、1.3%、2.3%、3.3%和4.3%）Na₂SO₄溶液中的阳极极化行为.结果表明,随着SO₂^-4的增多,纳米晶铜的致钝电流密度增大,而致钝电位降低.在0.3%的Na₂SO₄溶液中加入1%的NaCl,纳米晶铜阳极极化行为发生明显变化,Cl^-在纳米晶铜表面形成难溶于水的CuCl保护钝化膜,纳米晶铜致钝电流密度降低,活化-钝化过渡区电流密度下降速率显著减小.     

不同CO2浓度和施氮水平对麦田CO2净通量的影响

为研究不同CO₂浓度和施氮量对麦田CO₂净通量的影响,利用开顶式气室(OTC)组成的CO₂浓度自动调控平台模拟CO₂浓度升高环境.以冬小麦为试验材料,设置CK (对照,环境大气CO₂浓度)、C₁(CO₂浓度比CK增加120 μmol·mol^-1)和C₂(CO₂浓度比CK增加200 μmol·mol^-1)3个CO₂浓度水平;施氮量设置常规施氮量(N₁,25 g·m^-2)和低氮(N₂,15 g·m^-2)2个水平.采用静态箱-高精度气体分析仪观测麦田CO₂净通量.结果表明:各处理的麦田CO₂净通量变化特征一致,均呈先增大后减小的趋势,在拔节期和抽穗期达到峰值.N₁处理下,在整个生育期,CK、C₁和C₂处理的CO₂累积量分别为-105.8±12.6、-123.1±11.5和-120.2±4.1 kg·hm^-2.N₂处理下,在整个生育期,CK、C₁和C₂处理的CO₂累积量分别为-82.3±9.2、-95.4±7.6和-96.7±2.8 kg·hm^-2;拔节期C₂处理的CO₂累积量比CK显著增加了31.8%(P=0.024).C₁处理下,拔节期N₁处理的CO₂累积量显著高于N₂处理55.0%(P=0.009);C₂处理下,N₁处理的整个生育期CO₂累积量显著高于N₂处理23.6%(P=0.010).各处理CO₂净通量跟土壤湿度的相关关系均达到显著;N₁处理下,C₁和C₂处理的CO₂净通量跟光合有效辐射的相关关系达到显著,N₂处理下,CK和C₁处理的CO₂净通量跟光合有效辐射的相关关系达到显著;N₁处理下,C₁处理的CO₂净通量跟空气温度的相关关系达到显著,其余处理未达到显著.本研究表明:在小麦的拔节期和抽穗期,相比于CO₂浓度升高,施氮量对麦田CO₂净通量的影响更为显著;CO₂浓度升高与施氮量对麦田CO₂净通量的影响没有显著的交互作用.     

华南沿海城市PM2.5污染特征及来源解析

基于2017年12月25日至2018年1月16日1 h时间分辨率的在线监测数据,对华南沿海城市——阳江市的大气PM_2.5质量浓度、化学组分和来源进行了分析.结果表明,采样时段阳江市PM_2.5中主要化学组分为OM、NO^-₃、SO^2-₄、NH⁺₄和EC,质量浓度占比分别为32.75%、25.59%、16.41%、12.37%和4.82%.相比清洁过程,两次污染过程期间NO^-₃质量浓度均为清洁过程时段的6倍以上,增量明显高于其他组分,占比则均为清洁过程时段的2倍以上,分别占29.38%和30.81%.PMF解析结果表明,二次转化源是最主要的源,其分担率高达51.41%,其中NO_x二次转化源分担27.18%,是阳江市PM_2.5分担率最大的二次转化源.首要的一次排放源是机动车源(15.11%).污染过程期间NO_x二次转化源的分担率显著提升,从11.85%分别增至33.15%和36.96%,是阳江市大气PM_2.5污染形成的主要原因.本研究表明阳江市冬季PM_2.5污染特征已类似于大型和特大城市,即面临严峻的二次污染,应着重加强对硝酸盐的防治,同时注重机动车管控.     

N掺杂Co3O4纳米片的制备以及活化过一硫酸盐的性能研究

采用牺牲模板法合成N掺杂Co₃O₄纳米片（N-Co NS）,通过透射电子显微镜（TEM）、原子力显微镜（AFM）和光电子能谱（XPS）对制备材料的形貌结构、化学组成进行分析,并通过催化活化过一硫酸盐（PMS）降解水中双酚A （BPA）来探究催化剂的催化性能.实验结果表明与Co₃O₄纳米颗粒（Co NP）、Co₃O₄纳米片（Co NS）相比,N-Co NS表现出了较高的催化性能.在PMS浓度为2 mmol·L^-1、BPA初始质量浓度为50 mg·L^-1的反应条件下,N-Co NS在10 min内完全降解水中的BPA,表明N掺杂和二维纳米片结构有利于催化剂性能的提升.通过pH及离子影响实验证实N-Co NS在复杂水化学环境中仍具有较高的活性.此外结合自由基捕获实验和电子顺磁共振（EPR）测试证实反应体系中产生了高氧化活性的羟基自由基和硫酸根自由基.     

大气CO2浓度缓增对冬小麦土壤呼吸的影响

为研究大气CO₂浓度缓增对冬小麦（Triticum aestivum）土壤呼吸的影响，基于开顶式气室组成的CO₂浓度自动调控平台，在2017—2019年开展了两季冬小麦CO₂浓度缓增试验.每季试验在背景大气CO₂浓度基础上（CK，对照），均设置了CO₂浓度缓增处理（C₈₀和C₁₂₀，即从2016年起逐年增加40 μmol·mol^-1，至2017—2018年和2018—2019年冬小麦生长季CO₂浓度分别为CK+80 μmol·mol^-1和CK+120 μmol·mol^-1）.采用静态暗箱-气相色谱法测定土壤呼吸速率.结果表明：CO₂浓度缓增没有显著改变土壤呼吸的季节变化规律，但是会显著影响冬小麦旺盛生长期的土壤呼吸速率.在2018—2019年冬小麦抽穗-扬花期，C₁₂₀处理使土壤呼吸速率显著增加50.2％（P=0.008），且使得生长季土壤碳排放显著增加25.9％（P=0.044），而在2017—2018年冬小麦生长季，与CK相比，C₈₀处理对土壤呼吸没有显著影响.土壤呼吸与土壤温度呈指数正相关，与CK相比，CO₂浓度缓增降低了土壤呼吸对温度的敏感性.研究表明，CO₂浓度缓增120 μmol·mol^-1增加了冬小麦生长季土壤碳排放.     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi_0.45Co_0.10Mn_0.45O₂ was synthesized from Li₂CO₃ and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi_0.45Co_0.10Mn_0.45O₂, LiCoO₂ and LiMn₂O₄ were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi_0.45Co_0.10Mn_0.45O₂ has a layered structure with hexagonal lattice. The commercial LiCoO₂ has sphere-like appearance and smooth surfaces, while the LiMn₂O₄ and LiNi_0.45Co_0.10Mn_0.45O₂ consist of cornered and uneven particles. LiNi_0.45Co_0.10Mn_0.45O₂ has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of LiMn₂O₄ and LiCoO₂, respectively. LiCoO₂ and LiMn₂O₄ have higher discharge voltage and better rate-capability than LiNi_0.45Co_0.10Mn_0.45O₂. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries with LiMn₂O₄ or LiNi_0.45Co_0.10Mn_0.45O₂ cathodes show better safety performance under abusive conditions than those with LiCoO₂ cathodes. Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral Science Foundation of China     

不同污泥龄厌氧氨氧化菌的脱氮效能及其动力学特性

为研究不同污泥龄(SRT)条件下厌氧氨氧化菌的脱氮效能和动力学特性,采用一组SBR反应器研究梯度降低污泥龄过程中系统的NO2--N去除负荷(Nr)和NO2--N污泥负荷(Ns),并对各阶段厌氧氨氧化过程动力学特性进行分析.结果表明,污泥龄由21 d梯度降低到12 d,Nr由0.590 kg/(m3·d)降低到0.493 kg/(m3·d),单位MLVSS Ns由0.178 kg/(kg·d)提升到0.297 kg/(kg·d),系统整体的脱氮性能有所下降,但单位质量的厌氧氨氧化菌脱氮效率显著提升;采用莫诺(Monod)模型可以较好地模拟不同污泥龄运行阶段厌氧氨氧化菌的动力学行为,动力学分析表明,随着污泥龄的降低,NO2--N的最大比降解速率vmax由0.406 d-1提高到0.826 d-1,半饱和常数Ks由23.3 mg/L增加到95.3 mg/L,梯度降低污泥龄能够筛选纯化生长速率较快的厌氧氨氧化菌菌种,提升NO2--N的最大比降解速率,但厌氧氨氧化菌对底物的亲和性会逐渐变差,稳定性降低.     

LiNi0.4Co0.2Mn0.4O2与LiMn2O4共混正极材料电化学性能

为开发具有优良循环性能和安全性能的大型锂离子电池的正极材料,将不同比例的LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4材料进行共混,研究了LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4共混以及共混比例(10∶0、8∶2、7∶3、6∶4、5∶5、0∶10)对锂离子电池的首次放电性能、循环性能和倍率性能以及交流阻抗和循环伏安曲线的影响,并采用扫描电镜对电极材料进行了表征.研究结果表明,共混比例会影响材料的电化学性能,8∶2,7∶3和6∶4配比的混合材料的体积比容量、循环性能和倍率性能要好于纯LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4材料.其中,8∶2配比的材料性能最好.     

Self-Propagating High-Temperature Reduetive Synthesis of TiB2-Al2O3 Composite Powders

TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.     

BaZr0.9Y0.1O2.95/Na2SO4 composite with enhanced protonic conductivity

Heterogeneous composite BaZr_0.1Y_0.9O_2.95/Na₂SO₄ was designed and fabricated with Y-doped BaZrO₃ as matrix and Na₂SO₄ as dispersant by conventional powder processing to improve the total conductivity of barium zirconate. The electrical conduction of the composite was studied by electrical and electrochemical methods. Microstructure of the heterogeneous composite was examined by SEM. The experimewtal results show that the protonic conductivity of Y-doped BaZrO₃ is greatly improved upon incorporating Na₂SO₄ in the material. Microstructure observation indicates that a multiphase structure with Na₂SO₄ disperses at the grain boundaries of BaZr_0.1Y_0.9O_2.95. Electromotive force (EMF) measurements under fuel cell conditions reveal that the total ionic transport number of the composite is more than 0.9 at 750 °C. Funded by the National natural Science Foundation of China(No. 50872090)     

Nanocomposite films of V<Subscript>2</Subscript>O<Subscript>5</Subscript>−MoO<Subscript>3</Subscript> xerogel with poly ethylene oxide intercalation

Poly ethylene oxide (PEO)_x−V₂O₅−V₂O₅−MoO₃ (x=0, 0.5, 1) films were prepared by the sol-gel method. The synthesis and structure of the films were investigated by XRD, TG-DTA, FTIR, etc. The results show that V₂O₅−MoO₃ xerogel has a layered structure and its interlayer space increased from 1.3181 nm at x=0 to 1. 7898 nm at x=1 after the nanocomposite films were dried, and PEO in the interlayer changes the interface structure by forming hydrogen bonds with V=0 bands. CV measurement indicates that the intercalation of PEO improves insertion/extration properties of Li⁺ ions in the interlayer. ZHENG Jin-xia: Born in 1976 Funded by the National Natural Science Foundation of China (No. 50172036) and Natural Science Foundation of Hubei Province(No. 2001ABB083)     

Effect of La doping on microstructure and ferroelectric properties of Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films prepared by sol-gel method

The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr （remanent polarization） value of Bi3.25La0.75Ti3O12 thin films is 18.6 μC/cm^2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.2eLa0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed.     

Preparation and characterization of Bi4Ti3O12 platelets by a novel low-temperature molten salt system

Bismuth titanate (Bi₄Ti₃O₁₂) platelets were prepared by molten salt method in a new salt system of CaC_l2-NaCl at 650–750 °C, using bismuth nitrate pentahydrate (Bi(NO₃)₃―H₂O) and titanium butoxide (Ti (OC₄H₉)₄) as raw materials. The synthesis temperature of Bi₄Ti₃O₁₂ platelets was decreased to 650 °C from 900–1100 °C. The phase compositions and crystalline morphology of Bi₄Ti₃O₁₂ platelets were investigated by XRD and SEM. The experimental results indicate that Bi₄Ti₃O₁₂ platelets containing tetragonal and orthorhombic phase with the size of 1–3 μm can be synthesized at 650 °C for 2 h, and the orthorhombic phase becomes the dominant phase at 750 °C for 5 h. The size and proportion of Bi₄Ti₃O₁₂ platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases to about ninety percent, and the platelets grow up to about 3–10 μm at 750 °C for 5 h from 1–2 μm at 650 °C for 2 h. This technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods.     

Molar heat capacities of La2Mo2O9 and La1.9Sr0.1MO209-δ

The molar heat capacities of La2Mo209 and La1.9Sr0.1MO209-δ were obtained using the differential scanning calorimetry （DSC） technique in a temperature range from 298 to 1473 K. The DSC curve of La2Mo209 showed an endothermal peak around 834 K corresponding to a first-order monoclinic-cubic phase transition, and the enthalpy change accompanying this phase transition is 5.99 kJ/mol. No evident endothermal peak existed in the DSC curve of La1.9Sr0.1MO209-δ, but a broad thermal anomaly existed in its heat capacity curve at around 832 K. In addition, the heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ began to decrease at 1196 and 1330 K, respectively. The non-transitional heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ were formulated using multiple regression analysis in two temperature ranges.     

Synthesis and characterization of (PEO)<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>−(V<Subscript>0.85</Subscript>Mo<Subscript>0.15</Subscript>)<Subscript>2</Subscript>O<Subscript>5</Subscript> nanocomposite films

(PEO) _x −(V_0.85Mo_0.15)₂O₅(x=0,0.5,1.0) nanocomposite films were prepared by a modified sol-gel method. The structure of the films was analyzed by XRD, and the DC electrical conductivity. Cyclic voltammogram and optical spectral transmittance were investigated. The results show that the (V_0.85Mo_0.15)₂O₅ xerogel has a layered structure and its interlayer space increased from 1.3181 nm at x=0 to 1.7897 nm at x=1.0. The introduction of MoO₃ improved the DC electrical conductivities of the films due to the generation of V₄₊ to maintain the electrical neutrality of the oxides. PEO intercalated in the interlayer of (V_0.85Mo_0.15)₂O₅ oxides has interaction with the oxides, enhancing the amount of Li⁺ ions inserted into the interlayer of the oxides. Moreover, the intercalation of PEO into the interlayer of (V_0.85Mo_0.15)₂O₅ oxides improved the cathodic electrochromic property in near ultraviolet region and anodic electrochromic property in visible range. JIANG Cong-sheng: Born in 1963 Supported by the Science Foundation of Hubei Province (Grant No. 2001ABB083)