基于河岸带地球化学特征的河水-地下水交互边界识别——以广州市流溪河为例

河水-地下水交互作用对河流水质净化、流域水生态健康和河岸土地合理规划具有重要意义.本文以广州市流溪河为研究对象,实时监测河水和河岸带地下水基本理化指标并采集水样和土样进行水体主离子、氮形态、金属离子浓度、氘(δD)氧(δ~(18)O)同位素和土壤渗透系数(K)测试分析.结果表明:监测期间以河水侧向补给地下水为主,对地下水水位的影响范围在距河岸10 m内;距河岸1 m处地下水溶解氧(DO)浓度、电导率(EC)和氧化还原电位(ORP)变化明显,变异系数(n=7)分别为30.9%、42.0%和44.4%.河水和河岸带地下水水化学类型均为HCO_3-Ca型,受碳酸盐岩风化控制.河水入渗补给地下水初期,河岸带含水层向还原环境转化(ORP平均下降92.25 mV),非饱和带Mn氧化物发生还原性溶解,地下水中Mn~(2+)浓度逐渐增加并达最大值(0.52 mg·L~(-1));基于δD、δ~(18)O和Cl~-浓度的混合模型估算的河水对距河岸5 m处地下水的贡献率分别为10.4%、11.6%和11.5%,表明监测断面河水-地下水交互边界约在距河岸5 m处.     

钛基改性DSA电极氧化法去除水中全氟化合物

为了提高金属氧化物电极(DSA电极)的稳定性及催化活性,实现全氟化合物(PFCs)的高效降解,分别以溶胶涂覆法和电沉积法制备了改性DSA(Ti/SnO_2-ZnO)电极,并用于全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)的电化学降解过程研究.实验分别考察了电流密度、溶液初始pH、 PFOA与PFOS初始浓度对PFCs降解效果的影响.结果表明:两种方法制备的改性DSA电极表面均匀负载了SnO_2-ZnO复合涂层.在二维电极体系中,极板面积约为65.0 cm~2,电流密度为20.0 mA·cm~(-2),极板间距为15.0 mm,电解质为1.30 g·L~(-1)次氯酸钠溶液以及电解时间为150 min时,溶胶涂覆法和电沉积法所制备的Ti/SnO_2-ZnO电极对初始浓度为100 mg·L~(-1)的PFOA和PFOS分别在pH为3.50和6.50时去除效果最佳,分别达到了90.6%、94.6%和91.0%、93.7%;循环使用电极3次,其降解过程均符合准一级反应动力学,且电沉积法制备的电极效果优于溶胶涂敷法,表现出对PFCs类污染物稳定、高效的去除能力.     

南京地区一次臭氧污染过程的行业排放贡献研究

采用WRF-CHEM模式对南京地区春季一次臭氧(O_3)污染过程进行了模拟及行业排放贡献分析.此次O_3污染过程发生在2015年5月22—26日,南京地区一直处于地面高压控制的晴好天气之下,并于25日达到O_3污染的峰值.模拟与观测的一致性指数IOA达到0.89,表征本次O_3污染过程的模拟与观测结果的一致性较高.通过5类排放源(工业源、农业源、居住源、交通源、生物源)的敏感性试验,探究各行业排放源中O_3前体物对近地面O_3浓度的相对贡献.结果表明工业源在白天为持续正贡献,且在午后16:00时达到峰值,而交通源、居住源和农业源的贡献随气温的升高在白天由负贡献转为正贡献,并在18:00时左右达到峰值.在夜晚,O_3则主要通过交通源排放的大量NO进行滴定消耗.在高O_3浓度(≥200μg·m~(-3))时,各人为排放源均为正贡献,工业源的贡献最大,达到50μg·m~(-3),在低O_3浓度(200μg·m~(-3))时,交通源、居住源和农业源呈负贡献.生物源在人为排放源主导的南京城区O_3污染过程中的贡献几乎为零.考虑到O_3生成机制的复杂性,对于南京地区,减少工业源排放是控制O_3污染的关键.     

基于好氧甲烷氧化菌的反硝化效能及微生物群落研究

采用气体循环序批式生物膜反应器（gcSBBR）,构建反硝化型甲烷好氧氧化（AME-D）系统.考察了进水氮负荷的影响,发现氮负荷为0.075kg/（m³·d）时,硝酸盐氮去除率达到98.93%,其反硝化速率为74.25mg/（L·d）,系统的甲烷日平均消耗量为35.91%（初期为50%）;扫描电子显微镜（SEM）分析结果显示,系统中的微生物主要以短杆菌（12~18 μm）为主,并存在少量的丝状菌（长150~200μm）;16S rRNA高通量测序结果显示,该系统中的甲烷氧化菌为Methylocaldum、Methylomonas、Methylococcus和Methylococcaceae_unclassified,反硝化菌为Denitratisoma、Hydrogenophaga、Azoarcus、Thiobacillus和Rhodobacter,其中主要的功能微生物为Methylocaldum、Denitratisoma和Hydrogenophaga,系统对氮的去除是由好氧甲烷氧化菌与反硝化菌协同实现.此外,系统中存在大量以甲醇和甲基胺类物质为生长基质的Methylophilaceae_uncultured（30.4%）.     

基于热异常遥感的冀南城市群工业能耗及大气污染

选取冀南城市群为研究区,基于2012~2016年VⅡRS卫星数据热异常点产品,结合工业能源消耗量、工业废气排放量以及空气质量数据,利用统计分析和空间分析探讨热异常点辐射强度的变化规律及其与工业能源消耗、污染物排放之间的关系.结果表明,热异常点的辐射强度可以表征工业能源消耗量,并间接反映工业生产规模与污染排放水平.辐射强度越大,工业生产规模越大.辐射强度与工业SO₂排放量呈较高的正相关,与NO_x排放量呈中度线性相关.PM₁₀、SO₂及NO₂浓度与工业能源消耗和热异常点辐射强度灰色关联度均较高.工业生产活动产生的污染物中,颗粒物对大气污染的贡献最高,其次为SO₂.2012~2016年,邯郸、石家庄以及廊坊的工业生产空间分布呈逐年收缩聚集的趋势,保定和沧州的工业生产分别出现向南、向西迁移趋势.     

长江三角洲城市群工业污染时空演化及其驱动因素

基于2003~2015年长江三角洲（以下简称长三角）城市群26个城市工业废水和工业SO₂排放数据,采用标准差椭圆、地理集中指数、工业环境绩效指数、空间形态差异指数等方法从宏观和微观视角对长三角城市群工业污染时空演化进行分析,同时采用对数平均迪氏分解（LMDI）模型对其工业污染排放主要驱动因素进行分解.研究发现：2003~2015年工业废水和工业SO₂排放量分别下降了16.97%和28.79%,但占全国比重仍然较高,尤其是工业废水对生态环境胁迫较大.2种工业污染空间形态均呈现出北（偏西）-南（偏东）的空间分布形态,而2种工业污染重心移动轨迹并不一致,工业废水重心总体上朝向东（偏南）方向迁移了12.85km,而工业SO₂重心总体上朝向西（偏北）方向迁移了26.89km.此外,2种工业污染主要集中分布于长江沿岸城市且污染集中度指数由高到低大致呈半圈层状向周围递减.工业发展与工业污染空间形态演变具有一致性,工业废水重心和工业SO₂重心与工业发展重心距离均在逐渐缩小,而2种工业污染-环境绩效空间分布格局并不完全一致.驱动因素方面,环境规制引起的技术改善效应是工业污染排放量减少的主要原因,而由环境规制引起的产业结构效应对工业污染排放量的影响则取决于区域发展政策,经济发展效应是工业污染排放量增加的主要原因,人口规模效应对工业污染排放量的影响较小.     

Pilot-scale experiments on multilevel contact oxidation treatment of poultry farm wastewater using saran lock carriers under different operation model

A pilot-scale multilevel contact oxidation reactors system, coupled with saran lock carriers,was applied for the treatment of poultry farm wastewater. The removal efficiencies of CODcr, ammonia, and the total nitrogen as well as the elimination performance of CODcr and total nitrogen along the three-level contact oxidation tanks under six designed operational models were investigated. Based on the performance of the nitrogen removal of the saran lock carriers and the distribution of anoxic–aerobic interspace under the suitable operation model, the mechanism of nitrogen removal of the system was also explored. The results revealed that the intermittent aeration under parallel model is the most suitable operation model, while the removal efficiencies of CODcr, ammonia, and the total nitrogen were 86.86%, 84.04%, and 80.96%, respectively. The effluent concentration of CODcr,ammonia, and the total nitrogen were 55.6 mg/L, 8.3 mg/L, and 12.0 mg/L, which satisfy both the discharge standard of pollutants for livestock and poultry breeding industry(GB18596–2001) and the first grade of the integrated wastewater discharge standard(GB 8978–1996). Moreover, the mechanism for the nitrogen removal should be attributed to the plenty of anoxic–aerobic interspaces of the biofilm and the three-dimensional spiral structure of the saran lock carriers, where the oxygen-deficient distribution was suitable for the happening of the simultaneous nitrification and denitrification process. Therefore, the multilevel contact oxidation tanks system is an effective pathway for the treatment of the poultry farm wastewater on the strength of a suitable operation model and novel carriers.     

Morphology, composition, and sources of individual aerosol particles at a regional background site of the YRD, China

Aerosol samples were collected at Lin'an, a background site of Yangtze River Delta(YRD).Morphology, size, composition, and mixing state of individual aerosol particles were characterized by transmission electron microscopy(TEM) coupled with energy dispersive X-ray spectroscopy(EDS), and the soluble ions of PM_(1.0) were studied by aerosol mass spectrometer(AMS). The daily average AMS mass concentrations of sulfate, nitrate, and ammonium were about 5.8, 8.6, and 5.6 μg/m~3, respectively. Individual aerosol particles were classified into seven types: S-rich, K-rich, organic matter(OM), soot, fly ash, metal, and mineral. S-rich particles were dominant in all size bins, and 51%(by number) of S-rich particles were internally mixed with other particles. The fraction of organic coating particles was 13.7% in morning, 25.2% in afternoon, and 11% in evening, suggesting that the strong photochemical process during afternoon produced more secondary organic aerosols(SOA) on the surface of inorganic particles. Fly ash and metal particles were abundant during the day, suggesting the influence of emissions from coal-fired power plants and steel plants. The results indicate that the intense industrial emissions in the YRD significantly transported to the background areas. PM_(2.5) concentration may be lower in background air than in urban air but complex mixing state of aerosol particles indicates that the long-range transported particles substantially influenced the background air quality.     

Temporal variability of visibility and its parameterizations in Ningbo, China

Simultaneous and continuous measurements of visibility, meteorological parameters and air pollutants were carried out at a suburban site in Ningbo from June 1, 2013 to May 31,2015. The characteristics of visibility and their relationships with air pollutants and meteorological factors were investigated using multiple statistical methods. Daily visibility ranged from 0.6 to 34.1 km, with a mean value of 11.8 km. During the 2-year experiment,43.4% of daily visibility was found to be less than 10.0 km and only 9.2% was greater than 20.0 km. Visibility was lower in winter with a frequency of 53.4% in the range of 0.0–5.0 km.Annual visibility had an obvious diurnal variation, with the lowest and highest visibility being 7.5 km at approximately 06:00 local time and 15.6 km at approximately 14:00 local time, respectively. Multiple correspondence analysis(MCA) indicated that the different ranges of visibility were significantly affected by different levels of pollutants and meteorological conditions. Based on the analyses, visibility was found to be an exponential function of PM_(2.5) concentrations within a certain range of relative humidity. Thus, nonlinear models combining multiple linear regressions with exponential regression were subsequently developed using the data collected from June 2014 to May 2015, and the data from June 2013 to May 2014 was used to evaluate the performance of the model. It was demonstrated that the derived models can quantitatively describe the relationships between visibility, air quality and meteorological parameters in Ningbo.     

Visible-light-driven photocatalytic inactivation of bacteriophage f2 by Cu-TiO2 nanofibers in the presence of humic acid

Pathogenic viruses in drinking water are great threats to public health. Visible-light-driven photocatalysis is a promising technology for virus inactivation. However, the existing photocatalytic antiviral research studies have mostly been carried out in single-component systems, neglecting the effect of natural organic matter, which exists widely in actual water bodies. In this paper, electrospun Cu-TiO₂ nanofibers were prepared as photocatalysts, and their photocatalytic antiviral performance in the presence of humic acid (HA) was comprehensively studied for the first time. The properties of the reaction mixture were measured during the reaction. In addition, the safety, reliability and stability of photocatalytic disinfection in the mixed system were evaluated. The results showed that the virus removal efficiency decreased with the increase of the HA concentration. The type of reaction solution, such as PBS buffer solution or water, did not affect the removal efficiency noticeably. Under acidic conditions, the electrostatic forces between photocatalysts and viruses were strengthened, leading to higher virus removal efficiency. As the reaction time went on, the pH value in the solution increased first and then tended to be stable, the conductivity remained stable, and the dissolved oxygen increased first and then decreased. The safety test showed that the concentration of Cu ions released into the solution was lower than specified by the international standards. No photoreactivation was observed, and the addition of HA significantly reduced the reutilization efficiency of the photocatalysts.