不同气团对嘉兴市大气污染物变化特征的影响

利用嘉兴2012年10月—2013年9月污染气体和PM2.5的连续观测资料,结合HYSPLIT_4轨迹模式计算得到的观测期间嘉兴不同季节的主导气团,分析了嘉兴市大气污染物的变化特征及不同季节下不同气团类型对该地污染物的影响.结果表明,嘉兴市CO、SO2、NO2和PM2.5日变化为双峰型分布,峰值位于07∶00—09∶00和16∶00—18∶00;O3呈单峰分布,峰值位于14∶00,这与人为活动和大气边界层变化密切相关.大气污染物具有显著的季节变化特征,SO2、CO和PM2.5冬季高(43.5,950.3,79.8μg·m-3),夏季低(21.5、522.4、38.0μg·m-3);NO2在春季最高(49.9μg·m-3),夏季最低(30.4μg·m-3);O3夏季最高(88.9μg·m-3),冬季最低(17.2μg·m-3).影响嘉兴的主导气团的来源和路径存在显著季节变化,不同气团对大气污染物的分布影响较大,局地气团下SO2的浓度显著降低;大陆气团下污染物浓度普遍偏高,SO2、CO、NO2和PM2.5分别是海洋性气团的1.6—3.0、1.5—1.6、1.6—2.0和1.5—2.3倍;海洋性气团下污染物浓度普遍较低;混合性气团对应的污染物水平介于海洋性气团和大陆气团之间.     

草街水库蓄水后嘉陵江浮游植物群落特征及水质评价

为了解草街水库蓄水后嘉陵江的水环境变化情况,对嘉陵江浮游植物群落结构及水质状况进行了研究.研究期间共检出浮游植物145种,隶属8门74属,其中硅藻门种类数最多,23属57种,其次为绿藻门,28属53种.浮游植物平均细胞密度1.82×105cell·L-1,细胞密度居于前3位的分别为硅藻门、甲藻门、隐藻门,所占总密度比例分别为39.2%、29.9%、24.5%,春季细胞密度显著高于其他季节(P0.05).优势度分析显示,优势种主要为颗粒沟链藻(Aulacoseria granulata)、变异直链藻(Melosira varians)、倪氏拟多甲藻(Peridiniopsis niei)、具尾逗隐藻(Komma caudate)、啮蚀隐藻(Cryptomonas erosa)等.聚类分析结果表明,草街水库蓄水后对浮游植物的影响作用已初步显现.嘉陵江草街水库区在纵向上已初步形成不同特征的生态区域,各区域浮游植物群落结构存在差异,同时,草街水库大坝上、下游间浮游植物和水体特征也产生了差异.嘉陵江浮游植物的Shannon-Wiener多样性指数、Margalef丰富度指数和Pielous均匀度指数分别介于2.06~3.55、0.76~1.90、0.50~0.78,表明嘉陵江水体处于轻-中度污染状态.根据浮游植物群落结构评价显示,研究期间的嘉陵江水体营养水平为中营养类型.     

磷限制下光照和温度对水华鱼腥藻生长动力学的影响

磷、光照和温度是淡水水体藻类生长的关键环境因素,但磷限制下光照、温度交互对藻类生长动力学的影响鲜有报道.以水华鱼腥藻(Anabaena flosaquae)为研究对象,通过机制实验与模拟分析,发现光照条件恒定,磷限制下水华鱼腥藻的最适生长温度为20℃;温度条件恒定,磷限制下水华鱼腥藻的最适生长光照度为3 000 lx;但光照度过高,超过水华鱼腥藻光饱和点会抑制鱼腥藻的生长,生物积累量显著减少.通过拟合模型可知光热交互作用下水华鱼腥藻最适温度、光照度分别为21.03℃±1.55℃、2 675.12 lx±262.93 lx,该参数值接近春末夏初水体实际的光热条件.模型将为进一步预测水华鱼腥藻水华提供重要基础.     

扬子东南缘中生代构造体制转换研究——以江西相山火山盆地为例

江西相山火山盆地位于中国东南部晚中生代火山-侵入杂岩带的最西端,具有明显的东西向构造域与北东向构造域叠加特征,其在扬子东南缘(浙赣段)中生代构造体制转换研究中具有重要意义。通过测定流纹英安岩和边缘相碎斑熔岩锆石LA-ICP-MS U-Pb年龄,研究其岩石地球化学、地质构造特征,认为相山火山盆地东西向构造与北东向构造的强烈转换时间为133.87±0.76 Ma至132.01±0.7 Ma之间,可代表扬子东南缘(浙赣段)中生代构造体制强烈转换时期。     

三峡库区典型农村型消落带沉积物风险评价与重金属来源解析

本研究以三峡库区核心区——忠县典型农村型消落带为对象,于2011年7月,采集大坝水位回落后消落带沉积物样品,分析重金属含量,评价沉积物潜在风险,解析三峡库区农村型消落带重金属来源,为库区流域面源污染物控制提供基础数据.结果表明,消落带沉积物中As、Cd、Co、Cr、Cu、Mn、Ni、Pb和Zn的变化范围分别为155~160 m:5.17~14.81、0.06~0.57、8.55~20.56、62.79~93.04、15.38~60.97、425.72~782.32、21.34~48.5、23.03~43.39、57.78~130.10 mg·kg-1;170~175 m:7.05~12.57、0.17~0.33、10.71~18.89、65.22~92.89、18.89~42.91、74.06~774.41、22.47~42.49、24.17~29.23、55.67~103.18 mg·kg-1.地累积指数(I geo)表明,155~160 m消落带沉积物重金属累积顺序为Cd>Co>Mn>As>Cu>Pb>Zn,170~175m消落带累积程度大小为Co>Mn>Cd>As.沉积物污染指数(SPI)说明,155~160 m消落带沉积物潜在风险高于170~175 m沉积物,忠县城区下游155~160 m消落带沉积物风险达到峰值.统计分析结果显示,155~160 m消落带重金属Cr、Cu、Pb和Zn主要来源于自然背景,As、Ni、Cd、Co和Mn则来源于上游来水;170~175 m消落带沉积物重金属Cr、Ni、Pb和Zn主要来自自然背景,Cd、As、Co、Mn和Cu则极有可能来源于农田面源和上游.     

Adapting importation policy to global commodity markets: implications of rice import allocation in Singapore

Structural changes in the global commodity markets have particularly serious implications to the food security of import-dependent countries. Adapting importation policy to that global change is essential given that many commodities are imported to fulfill domestic demand. Using Singapore as a case study, this paper examines rice (Oryza) import allocation for seeking adaptive measures, which have broad implications to import-dependent countries. Its quarterly trade data (between 1999 and 2008) have been analyzed using an almost ideal demand system (AIDS) model. Our findings in respect to expenditure elasticity reveal that Singapore will continue its importation from its current range of suppliers, and add new import sources, fulfilling its national diversification strategy. New sources that located in different regions will also strengthen Singapore’s regional diversification strategy. Both national and regional diversification strategies enable any country to tap into associative import sources when unfavorable events deplete supply from a normally preferred supplier. In addition, the results in respect to own-price elasticity suggest that Thailand is Singapore’s primary preferred source while other exporters are secondary suppliers. Supported by the outputs of cross-price elasticity, secondary sources are substitutable. Within a diversified import portfolio, their competitive relationship gives an import-dependent country a strategic position to hedge against price manipulation and escalation, and to substitute expensive suppliers with cheaper alternatives. For these reasons, an import diversification policy is recommended both as an adaptive measure in response to the global change in commodity markets and, at the same time, as a mean for sustaining food security in import-dependent countries.     

厌氧颗粒污泥对Cu~(2+)的吸附性能研究

以厌氧颗粒污泥为生物吸附剂,研究了Cu2+吸附过程的动力学和热力学、污泥投加量和pH值对吸附效果的影响。结果表明:厌氧颗粒污泥对Cu2+的吸附过程为吸热、熵增的自发过程,可用伪二级反应动力学模型和Langmuir、Freundlich等温方程进行拟合;溶液温度为35℃、pH值为5时吸附效果最好。     

Toxic effects of perfluorononanoic acid on the development of Zebrafish (Danio rerio) embryos

Perfluorononanoic acid(PFNA) is a nine-carbon perfluoroalkyl acid widely used in industrial and domestic products. It is a persistent organic pollutant found in the environment as well as in the tissues of humans and wildlife. There is a concern that this chemical might be a developmental toxicant and teratogen in various ecosystems. In the present study,the toxic effects of PFNA were evaluated in zebrafish(Danio rerio) embryos. One hour post-fertilization embryos were treated with 0, 25, 50, 100, 200, 300, 350, and 400 μmol/L PFNA for 96 hr in 6-well plates. Developmental phenotypes and hatching rates were observed and recorded. Nineteen genes related to oxidative stress and lipid metabolism were examined using Quantitative RT-PCR and confirmed by whole mount in situ hybridization(WISH). Results showed that PFNA delayed the development of zebrafish embryos, reduced the hatching rate, and caused ventricular edema and malformation of the spine. In addition, the amount of reactive oxygen species in the embryo bodies increased significantly after exposure to PFNA compared with that of the control group. The Quantitative RT-PCR and WISH experiments demonstrated that m RNA expression of the lfabp and ucp2 genes increased significantly while that of sod1 and mt-nd1 decreased significantly after PFNA exposure. The m RNA expression levels of gpx1 and mt-atp6 decreased significantly in the high concentration group. However, the m RNA expression levels of both ppara and pparg did not show any significant variation after exposure. These findings suggest that PFNA affected the development of zebrafish embryos at relatively low concentrations.     

An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration

The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb > Zn > Cr > Cu > Mn > Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO₄ and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl₂, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl₂, Pb(ClO₄)₂ and PbCl₂O₄.     

热重-质谱联用研究城市生活垃圾热解特性

采用热重-质谱(TG-MS)联用技术研究城市生活垃圾的热解特性以及Ca O的添加对垃圾热解过程和挥发分析出特性的影响。结果表明,城市生活垃圾在热解过程于低温区(240~385℃)的失重主要是由于垃圾样品中纤维素和半纤维素的分解以及部分塑料的低温分解,而发生在385~500℃间的第二失重峰主要是由于塑料和木质素组分的分解。添加Ca O有利于城市生活垃圾在低温区域的热解,并且能减少焦油组分的逸出,减弱CO2气体的逸出强度,促进CH4和CO气体的释放,但对C2H6气体的释放影响较小。