Observation of chemical components of PM2.5 and secondary inorganic aerosol formation during haze and sandy haze days in Zhengzhou, China

Mineral dust particles play an important role in the formation of secondary inorganic aerosols, which largely contribute to haze pollution in China.During this study, a haze episode(haze days) and a typical haze process mixed with sandstorm(sandy haze days)were observed in Zhengzhou with a series of high-time-resolution monitoring instruments from November 22 to December 8, 2018.Concentrations of PM_(10) and crustal elements clearly increased in the sandy haze days.Concentrations of gaseous pollutants, metallic elements emitted from anthropogenic sources, nitrate, and ammonium during sandy haze days were slightly lower than those during the haze days but still obviously higher than those during the non-haze days.The sulfate concentrations, the sulfate fractions in PM_(2.5),and the sulfur oxidation ratios significantly increased in the sandy haze days.Heterogeneous reactions dominated the conversion of SO_2 during the haze and sandy haze days.Enhanced SO_2 conversion during the sandy haze days may be attributed to the high concentrations of transition metal ions from the sandstorm when the values of relative humidity(RH) were in 30%–70%, and high O_3 at certain time points.Gas-phase NO_2 oxidation reactions were the main pathways for nitrate formation.In the sandy haze days,higher nitrogen oxidation ratio(NOR) at daytime may be associated with higher RH and lower temperature than those in the haze days, which facilitate the gas-to-particle partitioning of nitrate; higher NOR values at night may be attributed to the higher O_3 concentrations, which promoted the formation of N_2O_5.     

Spatiotemporal characterization and regional contributions of O3 and NO2: An investigation of two years of monitoring data in Henan, China

To investigate the characteristics of ground level ozone(O_3) for Henan Province,the ambient air quality monitoring data of 2015 and 2016 were analyzed.The result showed that the 8 h-max-O_3 concentrations displayed a distinct seasonality,where the maximum and minimum values,averaging 140.41,54.19 μg/m~3,occurred in summer and winter,respectively.There is a significant correlation between meteorological factors and O_3 concentration.The Voronoi neighborhood averaging analysis indic ated that O_3,temperature,and ultraviolet radiation in Henan province were decreased from northwest to southeast,while relative humidity and precipitation displayed the opposite trend.Besides meteorological factors,the chemical processes play an essential role in ozone formation.Reactions of NO,NO_2 and O_3 form a closed system,and the partitioning point of the OX-component(O_3+NO_2) was at 40 and 80 μg/m~3 for nitrogen oxide(NO_x) in winter and summer,respectively,with NO_2 dominating at higher NO_x pollution and O_3 being the m ajor component at lower levels.The relationship between oxidant(OX=O_3+NO_2)and NOx concentrations were evaluated to understand the regional and local contribution of OX.It showed that high regional contribution occurred in the spring,whereas the highest local contribution lead to the summer peak of O_3 observed in Zhengzhou.This present study reveals important environment impacts from the photochemical process and the meteorological conditions in the region with better understanding on the O_3 characterization.     

氧化木糖无色杆菌(Achromobacte rxylosoxidans)LAX2对Cu、Pb和Cd复合污染土壤的生物矿化修复研究

我国土壤重金属复合污染较为突出,是目前亟待解决的土壤环境问题之一.本文研究了一株氧化木糖无色杆菌LAX2对Cu、Pb和Cd共存体系的生物矿化作用及其复合污染土壤的矿化修复作用.结果表明,菌株LAX2的发酵液、无菌发酵液和菌体细胞对3种重金属的去除能力大小顺序均为Pb~(2+)Cd~(2+)Cu~(2+).X-射线衍射、扫描电镜、红外光谱和能谱分析表明,3种重金属共存时菌株LAX2发酵液可诱导形成PbCO_3和CdCO_3晶体,而Cu不能单独成矿,混合矿物晶体呈长杆状.菌株LAX2发酵液能够明显降低黑钙土和白浆土中Cu、Pb和Cd的有效态含量,矿化修复30 d后,黑钙土中Cu、Pb、Cd的有效态含量分别降低了48.0%、71.4%、62.8%,白浆土中Cu、Pb、Cd的有效态含量分别降低了42.0%、63.2%、53.6%;碳酸盐结合态和铁锰氧化物结合态含量明显增加,可交换态和有机物结合态含量明显降低.矿化修复后的土壤中重金属的浸出毒性随修复时间的增长而降低,黑钙土中Cu、Pb、Cd浸出量分别降低了90.3%、93.2%、92.8%,白浆土中Cu、Pb、Cd浸出量分别降低了82.5%、86.1%、84.3%.以上结果说明,菌株LAX2可通过碳酸盐矿化作用固定土壤中的复合重金属,且在相同条件下对黑钙土的修复效果好于白浆土.     

Distribution of polychlorinated naphthalenes (PCNs) in the whole blood of typical meat animals

The concentrations and distribution of polychlorinated naphthalenes(PCNs) in the whole blood of eight typical terrestrial meat animals(chicken, duck, rabbit, pig, cattle, sheep,horse and donkey) consumed daily in our life were investigated. The total concentrations(on a liquid volume basis) of PCNs were in a range from 305 to 987 pg/L. Donkey blood contained the highest PCN concentrations. Mono-CNs were the dominant homolog group,accounting for 38%–71% PCNs. Apart from the mono-CNs and tri-CNs homolog groups, two hepta-CNs(mean: 9.5%) contributed most, followed by tetra-CNs(mean: 6.5%). The congeners CN1, 5/7, 24/14, 27/30, 52/60, 66/67, and 73 were the most abundant congeners or congener groups. The highest toxicity equivalencies(TEQs) were observed in cattle blood(117.4 fg TEQ/L) then chicken blood(117.1 fg TEQ/L). CN73 contributed 65% to total TEQs,followed by CN70(20%) and CN66/67(14%). The dietary intakes of PCNs were also estimated.Chicken meat, which forms the second largest component of meat product consumption in China, contributed most to the total TEQs(61%), followed by beef(27%) and pork(5.9%). The consumption of chicken might pose the highest risk from exposure to PCNs than other types of meat to populations who prefer to eat chicken meat.     

Algal uptake of dissolved organic nitrogen in wastewater treatment plants

The algal uptake of dissolved organic nitrogen(DON) in the anaerobic–anoxic–oxic(A_2O)process was investigated in this study. Anaerobic, aerobic and effluent DON samples from two wastewater treatment plants(WWTPs) were separated into hydrophilic and hydrophobic fractions using a DAX-8 resin coupled with an anion exchange resin and a nanofiltration(NF)pretreatment. Hydrophilic DON accounted for 66.66%–88.74% of the entire DON for the two plants evaluated. After a 15-day incubation, 16.95%–91.75% DON was bioavailable for algal growth, and untreated samples exhibited higher DON bioavailability, with 52.83% DON average uptake rates, compared with the hydrophilic and hydrophobic fractions(45.53% and 44.40%, respectively) because the pretreatment caused the inorganic salt to be resistant to algae. Anaerobic untreated samples, hydrophilic fractions and hydrophobic fractions showed higher DON reduction rates and higher biomass accumulation compared with the other DON fractions due to the decomposition of resistant organics by anaerobic and anoxic bacteria.DON in aerobic and effluent samples of plant A was more bioavailable than that of plant B with usages of 27.49%–55.26% DON. DON bioavailability in the anaerobic–anoxic–oxic process decreased in the following order: anaerobic effluent aerobic. The DON contents were reduced after anaerobic treatment in the two plants. The EEM-PARAFAC model identified three DON components, including two humic acid-like substances and one protein-like substance in plant A and two protein-like substances and one humic acid-like substance in plant B.     

我国典型陆地生态系统固碳重要区范围界定

全球变暖已成为当今最主要的全球性环境问题之一,建立固碳重要区也是应对全球气候变化的重要途径之一.根据我国陆地生态系统现状以及固碳相关的最新研究结果和政府文件,以森林、草地生态系统为主要研究对象,采用GIS空间叠置分析方法,界定我国典型陆地生态系统固碳重要区(注:涉及“全国”的各要素范围均未包含港澳台地区)的空间范围.研究结果:固碳重要区评价指标体系包括生态系统碳储量、碳汇和固碳潜力3个核心因子,界定过程包括界定范围选择、固碳高值区识别、固碳重要区范围确定和分区命名等步骤.在全国尺度界定了森林、草地两大类共计20个固碳重要区,总面积285.6×104 km2.其中,森林生态系统固碳重要区主要分布在我国东北部、西南部的深山区和东南部的山地丘陵,草地生态系统固碳重要区主要分布在内蒙古高原中东部、新疆西北部山地和青藏高原东南部.固碳重要区面积占全国国土总面积的29.8%,所提供的NPP(净初级生产力)量占全国NPP总量的40.7%,固碳能力是全国平均水平的1.37倍.固碳重要区范围界定结果符合“以较小面积获取较大服务”原则,适于作为我国实现碳减排目标的优先保护区域.      

基于PLFA法分析亚硝氮、硝氮和氨氮对厌氧微生物细菌群落的影响

利用磷脂脂肪酸(PLFA)技术研究了亚硝氮、硝氮和氨氮在不同浓度水平下对中温厌氧颗粒污泥中厌氧细菌群落结构的影响.结果表明,高浓度亚硝氮(360 mg·L-1,以N计)、硝氮(300 mg·L-1,以N计)和氨氮(3000 mg·L-1,以N计)使系统COD去除率分别下降至3.49%、10.85%和71.53%,并使污泥表面主要细菌由杆菌变为球状菌;亚硝氮和硝氮引起厌氧细菌和革兰氏阳性菌的含量下降,氨氮引起革兰氏阴性菌的含量下降;PLFA香农-威尔多样性指数随着亚硝氮和硝氮浓度的升高从1.12分别下降至0.96和1.03,氨氮对PLFA香农-威尔多样性指数无明显影响.     

加油站埋地油罐油气爆炸事故模拟试验

为探索加油站埋地油罐油气爆炸破坏效应,搭建埋地油罐燃爆试验平台,在油罐内布置压力传感器和温度传感器,在人孔井周围布置热流传感器,向罐内注入少量汽油,利用鼓吹方式使油气浓度达到爆炸极限,通过电火花点火模拟清罐、检修过程中的爆炸事故,掌握埋地油罐、人孔井及周围环境受爆炸影响的压力冲击波和热辐射数据。结果表明,加油站发生埋地油罐敞口爆炸时,爆炸会对罐壁产生峰值强度为100~400 k Pa的冲击波。爆炸形成的火焰和冲击波向人孔井口正上方释放,不会向四周扩散。     

SO2及PM10污染频次分析方法的探讨

以梅州为例,对城区小区域内3个站点的SO₂及PM₁₀浓度进行统计,分析SO₂及PM₁₀浓度变化的发生偏离正常水平的时间分布情况,为大气污染防治工作提出决策支持建议。     

多级孔板扰流泡沫发生器流场模拟分析

通过数值模拟方法,对内锥和多级孔板组合扰流结构下的泡沫发生器流场进行了模拟和分析。通过CFD流场模拟软件Fluent,以泡沫发生器的真实操作工况为边界条件进行建模,得到了气液两相掺混流场的结构和重要动力学参数,并进行了分析。发现扰流件的下游区域存在一个较稳定回流区,同时在多级孔板区域流场的湍动能及湍动能耗散率较高,对泡沫发生器中气液两相掺混有利。扰流件下游液相分布较为均匀,进一步验证了发泡器内部气液掺混效果较佳。通过流场模拟,验证了圆锥和四级孔板组合扰流结构对强化泡沫发生器内气液掺混的有效性。