模拟酸雨及氮沉降对马尾松林土壤细菌群落结构及其多样性的影响

通过分析酸雨和氮沉降对马尾松林土壤细菌群落结构及多样性的影响,探究马尾松林对环境胁迫的响应机制,为天目山国家自然保护区资源管理和保护提供理论参考依据.于2017～2021年在浙江省临安天目山国家级自然保护区设置4个酸雨和氮沉降模拟梯度[即pH 5.5和0 kg·(hm²·a)^-1,CK; pH 4.5和30 kg·(hm²·a)^-1,T1; pH 3.5和60 kg·(hm²·a)^-1,T2; pH 2.5和120 kg·(hm²·a)^-1,T3].使用Illumina MiSeq PE300二代高通量测序平台对4种处理土壤细菌16S rDNA进行测序,分析不同处理土壤细菌群落组成和结构的差异及其影响因素.结果表明,酸雨和氮沉降显著降低了马尾松林土壤细菌α多样性(P<0.05).马尾松林土壤由36个门类的菌群组成,酸杆菌门(Acidobacteria)、变形菌门(Proteobacteria)、放线菌门(A...     

模拟酸雨对次生林土壤呼吸及异养呼吸的影响

为研究模拟酸雨对次生林土壤呼吸及异养呼吸的影响,进行野外定位试验.设置裂区试验,分4个区组,每个区组中主区为不断根和挖沟断根小区,每个主区内设置对照(CK)、pH 4.0(A1)、pH 3.0(A2)、pH 2.0(A3)共4个模拟酸雨处理水平.观测不断根小区的土壤呼吸和断根小区的异养呼吸,同时观测土壤温度、土壤湿度.结果表明,在不断根小区,CK、A1、A2、A3处理的土壤呼吸均表现出明显的季节变异趋势;与不断根小区类似,断根小区的异养呼吸也具有明显的季节变异趋势.断根小区的异养呼吸明显低于不断根小区的土壤呼吸.CK、A1、A2、A3处理的年平均土壤呼吸速率分别为(2.47±0.31)、(2.52±0.22)、(2.38±0.17)、(2.43±0.22)μmol·(m~2·s)~(-1);断根小区CK、A1、A2、A3处理的年平均异养呼吸速率分别为(1.55±0.10)、(1.65±0.22)、(1.77±0.08)、(1.78±0.27)μmol·(m~2·s)~(-1).单因素方差分析表明,不断根小区不同模拟酸雨处理之间的土壤呼吸速率以及断根小区不同模拟酸雨处理的异养呼吸速率均无显著差异.回归分析表明,不断根小区的土壤呼吸与断根小区的异养呼吸之间存在极显著(P0.001)的正比例函数关系,模拟酸雨的添加降低了土壤呼吸与异养呼吸之比.土壤温度是决定不断根小区土壤呼吸和断根小区异养呼吸季节变异的最主要的因素,而土壤湿度对土壤呼吸和异养呼吸的季节变异无显著的影响.     

桂林市酸雨变化特征及来源分析

对桂林市2008~2011年共396个降水样品p H值统计表明,桂林市酸雨具有明显的季节性差异,夏季酸雨污染程度较低,冬春两季最为严重;对其中44个降水样品做离子分析,通过计算中和因子(NF)分析2008年酸雨程度低主要是NH_4~+和Ca~(2+)等碱性离子中和所致,相对酸度FA达到0.006,表明有99.4%酸性离子被中和;通过富集因子(EF)分析降水中主要离子来源,CI~-和Na~+主要为海洋来源,Ca~(2+)主要为地壳来源,K~+、SO_4~(2-)、NO_3~-主要为人为来源;最后通过Hysplit后向轨迹模拟分季节对2010年强酸雨水汽来源进行追踪,聚类,分析桂林市酸雨受区域输送的影响,确定致酸物质的3个主要源地:1东北向的江西、安徽、湖南、湖北等省份的工业集中、人口密集地区,来源于这些地区的气团春季占到19%,夏季26%,秋季19%,冬季由于盛行东北风,占到36%;2东南方向的广东省尤其珠三角地区,来源于西太平洋的气流经过此地到达桂林,春季占到19%,秋季占到33%,冬季占到36%;3西南向的南宁、柳州等本省城市,春季所有的强酸雨水汽气团都汇合到桂林的西南侧,经南宁、柳州抵达桂林,夏季直接受西南季风的控制,来自印度洋的水汽径直抵达桂林占到75%,秋季途经该地的西南向气流占到14%,冬季63%.     

Heterogeneous reaction of SO2 on CaCO3 particles: Different impacts of NO2 and acetic acid on the sulfite and sulfate formation

Despite the heterogeneous reaction of sulfur dioxide (SO₂) on mineral dust particles significantly affects the atmospheric environment, the effect of acidic gases on the formation of sulfite and sulfate from this reaction is not particularly clear. In this work, using the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique, we employed a mineral dust particle model (CaCO₃) combined with NO₂ and acetic acid to investigate their effects on the heterogeneous reaction of SO₂ on CaCO₃ particles. It was found that water vapor can promote the formation of sulfite and simulated radiation can facilitate the oxidation of sulfite to sulfate. The addition of NO₂ or acetic acid to the reaction system altered the production of sulfate and sulfite accordingly. There was a synergistic effect between NO₂ and SO₂ that promoted the oxidation of sulfite to sulfate, and a competitive effect between acetic acid and SO₂ that inhibited the formation of sulfite. Moreover, light and water vapor can also affect the heterogeneous reaction of SO₂ with the coexistence of multiple gases. These findings improve our understanding of the effects of organic and inorganic gases and environmental factors on the formation of sulfite and sulfate in heterogeneous reactions.     

WIND DRIVEN RAIN DISTRIBUTIONS AROUND STREET CANOPIES1

ABSTRACT: Wind driven raindrop tracking is used to investigate the microscale redistribution of wind driven rainfalls in street canopies by combining a Eulerian wind flow model and a Lagrangian raindrop tracking model. The former conducts large eddy simulations of the turbulent flows in street canopies, and the latter performs raindrop trajectory calculations by releasing a large number of raindrops into the computational domain. The wind speed model is verified with available wind tunnel measurement. Twenty sets of simulations are carried out for various building configurations and driving rain angles. The simulated results show that the trajectories of smaller raindrops are more slanting and more influenced by the multibuilding perturbed flow field. Impingement of raindrops on the building envelope increases from bottom to top. The height of the front building is a significant factor affecting wind driven rain redistribution. Distinct nonuniform spatial rainfall distributions are found for scenarios with high building configurations and low driving rain angles. The simulated results are further integrated to assess the effect of real raindrop size distributions by weighing the volumetric fraction of a range of drop sizes. There is about 10 percent variation in spatial extent of street canopies. An overall 5 to 17.4 percent increase of the rainfall amount in the upwind zone is observed.     

上海宝山区酸雨特征分析

分析了连续七年(2004年-2010年)上海宝山区的降水的化学特征。从酸雨发生频率来看,2004年-2007年酸雨频率为:78.6%、75.9%、89.5%和94.6%,呈逐年加重的趋势,表明降水的酸性及酸化频率非常高,雨水酸化已非常严重。但从2008开始酸雨状况开始改善,酸雨频率开始降低,分别为:78.6%、41.1%和23.6%,同时其pH值开始高于全市平均水平;对降水中的各种阴阳离子进行数理统计分析:SO24-对降水的酸化起主要作用,但其作用在逐步减小,而NO3-和Cl-的作用呈上升的趋势;c(Cl-)/c(Na+)总体呈下降趋势,说明化工、有色金属冶金等工业生产废气中Cl2和HCl等污染物作用减少;因子分析反映了降水的来源成因机制,其结果与相关性分析一致。     

Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7

Fe(Ⅲ) immobilized fire clay (Fe-FC) was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7 (AV 7) under natural sunlight. The 26% ferric nitrate loaded fire clay was found to be most efficient. The experimental conditions such as solution pH, H₂O₂ concentration for efficient degradation of AV 7 have been determined. Unlike Fenton catalyst, Fe-FC is photoactive over a wide pH range of 3-7. This catalyst was found to be stable and reusable. The GC-MS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6-triol, 8-aminonaphthalene-1,2,3,6-tetrol, 2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/ 2-aminobenzene-1,4-diol as intermediates. The 26% ferric nitrate loaded fire clay was characterized by XRD, ICP-AES, BET surface area, FT-IR, SEM-EDS and UV-DRS studies.     

石灰石-石膏湿法脱硫“石膏雨”现象原因分析及治理措施

针对火力发电厂石灰石-石膏湿法烟气脱硫工艺出现的"石膏雨"现象,结合数值模拟和工程实践分析了"石膏雨"产生的主要原因,并同时提出了各项相应的治理措施。     

北京市湿沉降特征分析

通过分析北京市降水中水溶性离子组分的浓度,研究了2005～2009北京市降水酸化程度及水质变化特征.北京市5 a年均pH为5.19,总体变化趋势平稳.5 a间,降水中各离子组分含量均有下降趋势,北京市的环境质量逐步改善;NH 4^＋和NO 3^-在降水中所占比例明显增加,北京市降水受含N污染物排放的影响较大.季节变化显...     

东川地区酸雨污染特征及控制对策

对东川酸雨污染的水平、变化特征、污染趋势、酸雨组成权重、与气象的关联性进行分析研究。结果显示:东川地区存在不同程度的酸雨污染,冶炼厂硫排放是造成该区域酸雨的主要成因。提出东川区酸雨控制的主要对策措施。