钛元素对水培大白菜生长的促进作用

文章选用凡尔赛营养液作为基础培养液,分别加入一种含钛植物生长促进剂和TiCl4溶液,以早熟五号大白菜为试验对象,基础培养液作为对照,考察钛元素对大白菜生长的影响及与其他营养元素之间的关系。结果表明:施加含有相同含钛量的植物生长促进剂与TiCl4溶液的大白菜中单株大白菜鲜重增幅分别为35.4%和23.1%;可溶性糖含量增幅为162.5%及118.8%;大白菜中硝酸盐含量的降低幅度分别为15.2%和13.8%;亚硝酸盐含量的降低幅度分别为36.4%和33.8%。同时,还测量了其他相关指标如株高、叶面积、叶绿素含量等。添加TiCl4的培养液与对照相比,在各项指标中都表现出优势,与添加植物生长促进剂的培养液相比,叶绿素、硝酸盐等指标相差不明显。     

首钢烧结厂PM_(10)治理技术与经济分析

通过对首钢烧结厂的污染结点、污染物特性、污染物控制技术措施和技术规范进行分析,提出了烧结厂PM10控制方案,对烧结厂采用高效除尘设备的PM10削减量及改造费用进行了估算,确定了烧结厂PM10治理技术方案排序,为钢铁企业烧结厂治理颗粒污染物的同时选择最为经济实用的除尘器类型提供理论依据.     

首钢烧结厂PM10治理技术与经济分析

通过对首钢烧结厂的污染结点、污染物特性、污染物控制技术措施和技术规范进行分析,提出了烧结厂PM₁₀控制方案,对烧结厂采用高效除尘设备的PM₁₀削减量及改造费用进行了估算,确定了烧结厂PM₁₀治理技术方案排序,为钢铁企业烧结厂治理颗粒污染物的同时选择最为经济实用的除尘器类型提供理论依据。     

Formation of secondary inorganic aerosols by power plant emissions exhausted through cooling towers in Saxony

Background, aim, and scope  The fraction of ambient PM₁₀ that is due to the formation of secondary inorganic particulate sulfate and nitrate from the emissions of two large, brown-coal-fired power stations in Saxony (East Germany) is examined. The power stations are equipped with natural-draft cooling towers. The flue gases are directly piped into the cooling towers, thereby receiving an additionally intensified uplift. The exhausted gas-steam mixture contains the gases CO, CO₂, NO, NO₂, and SO₂, the directly emitted primary particles, and additionally, an excess of ‘free’ sulfate ions in water solution, which, after the desulfurization steps, remain non-neutralized by cations. The precursor gases NO₂ and SO₂ are capable of forming nitric and sulfuric acid by several pathways. The acids can be neutralized by ammonia and generate secondary particulate matter by heterogeneous condensation on preexisting particles. Materials and methods  The simulations are performed by a nested and multi-scale application of the online-coupled model system LM-MUSCAT. The Local Model (LM; recently renamed as COSMO) of the German Weather Service performs the meteorological processes, while the Multi-scale Atmospheric Transport Model (MUSCAT) includes the transport, the gas phase chemistry, as well as the aerosol chemistry (thermodynamic ammonium–sulfate–nitrate–water system). The highest horizontal resolution in the inner region of Saxony is 0.7 km. One summer and one winter episode, each realizing 5 weeks of the year 2002, are simulated twice, with the cooling tower emissions switched on and off, respectively. This procedure serves to identify the direct and indirect influences of the single plumes on the formation and distribution of the secondary inorganic aerosols. Results and conclusions  Surface traces of the individual tower plumes can be located and distinguished, especially in the well-mixed boundary layer in daytime. At night, the plumes are decoupled from the surface. In no case does the resulting contribution of the cooling tower emissions to PM₁₀ significantly exceed 15 μgm⁻³ at the surface. These extreme values are obtained in narrow plumes on intensive summer conditions, whereas different situations with lower turbulence (night, winter) remain below this value. About 90% of the PM₁₀ concentrations in the plumes are secondarily formed sulfate, mainly ammonium sulfate, and about 10% originate from the primarily emitted particles. Under the assumptions made, ammonium nitrate plays a rather marginal role. Recommendations and perspectives  The analyzed results depend on the specific emission data of power plants with flue gas emissions piped through the cooling towers. The emitted fraction of ‘free’ sulfate ions remaining in excess after the desulfurization steps plays an important role at the formation of secondary aerosols and therefore has to be measured carefully.     

Is tree growth reduction related to direct foliar injuries or soil chemistry modifications?

In the context of intense emissions causing atmospheric pollution, tree growth reductions could be related to soil chemistry modifications or direct foliar injuries. To verify these hypotheses, mineral soils were sampled in an area (Murdochville, Canada) where previous studies had demonstrated that tree growth was impacted by smelter emissions and that forest floor lead concentrations could be used as a proxy for atmospheric pollutant depositions. Samples were analysed for Al, Pb (concentrations and isotope ratios), basic cations (Ca, K, P, and Mg) and Zr. Mass balance calculations were performed on soil profiles to assess vertical migration of elements. Pb concentrations in litter diminished gradually with distance from the smelter. The Pb isotope ratios in these organic soil layers were close to those measured in the Murdochville ores. These patterns were not encountered in mineral soil layers. Pb isotope ratios in these layers were close to those measured in uncontaminated geological materials, and Pb concentrations and basic cation depletions were not related to the proximity of the smelter. Growth reduction was closely associated with litter Pb concentrations, which were used as a proxy for atmospheric deposition, but was not correlated with any elemental concentration or cation depletion measured in mineral soil layers. Our overall results suggest that trees responded mainly to direct atmospheric emissions, which caused foliar damage, rather than to soil chemistry modifications.     

Effects of wavelength and water quality on photodegradation of N-Nitrosodimethylamine (NDMA)

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that yields a cancer risk of 10⁻⁶ at concentrations as low as 0.7 ng L⁻¹. Tentative guideline values are set at 3 ng L⁻¹ in California, USA; 9 ng L⁻¹ in Ontario, Canada; 40 ng L⁻¹ nationwide in Canada; and 100 ng L⁻¹ by the World Health Organization. NDMA is a great concern in treating reclaimed water as well as drinking water. UV degradation can be considered effective degradation method. A 1-log reduction of NDMA is achieved by 1000 mJ cm⁻² of a 254-nm low pressure (LP) mercury UV lamp. However, a higher degradation efficiency than that provided by LP lamps is desired in practical treatment. In this study, the effects of wavelength and water quality were investigated to achieve higher degradation efficiency. The effects of wavelength were examined by comparing three UV lamps: a 222-nm Kr Cl Excimer UV lamp, a 254-nm LP mercury UV lamp, and a 230- to 270-nm filtered medium pressure (FMP) mercury UV lamp. The 222-nm lamp and FMP lamp achieved 4 times and 2.8 times higher degradation efficiency, respectively, than the conventional 254-nm LP lamp. Effects on water quality were also simulated by using absorption spectrum data of nitrate solutions and process water from a drinking-water treatment plant. In the simulation, the 222-nm lamp was affected by UV-absorbing compounds in the water, whereas the FMP lamp showed more stable degradation efficiency. Appropriate use of these three types of lamps could enhance the efficiency of degradation of NDMA.     

燃煤电厂PM_(2.5)减排技术与装备探讨

燃煤电厂在我国电力工业中占有很大的比重,其烟尘排放污染问题也尤其突出。大量燃煤烟尘的排放造成了严重的环境污染,特别是其中的细颗粒物PM2.5,能长期悬浮于大气中,对人类的健康造成了长期持续的危害,因此燃煤电厂PM2.5减排技术对于环境保护事业具有重要的意义和深远的影响,大力发展PM2.5减排技术与装备是电力行业大势所趋。     

污水深度处理中3种过滤法的技术性能研究

以城市污水回用为目的，研究了污水深度处理中的过滤技术，结果陶瓷－石英砂双层滤料的滤柱，在滤速为５．２ｍ／ｈ时，通过直接过滤即可将污水处理厂二级出水中的悬浮物几乎全部去除，且过滤周期可达６１．２－７２．１ｈ。     

垃圾堆酵对焚烧厂垃圾热值的影响

分析了垃圾焚烧厂的渗滤液；基于渗滤液的体积和ＣＯＤｃｒ值，估算焚烧厂垃圾堆酵对垃圾热影响以及焚烧厂垃圾的适宜堆酵时间，实验结果表明，上海生活垃圾渗滤液是生化性好的高浓度有机废液，堆酵５ｄ，其低位热值〉４６００ＫＪ／ｋｇ，可直接焚烧。     

南方冬季条件下根际促生菌与肥料配施对巨菌草迁移累积镉砷的影响

优良菌种是微生物肥料的基础,研究微生物肥料中低温适应型菌株在低温条件下的促生性,对于提高南方冬闲时植物修复重金属污染农田具有重要意义.通过形态观察及18S rRNA基因序列分析,对菌株进行了鉴定,在此基础上进行植物盆栽试验,分析了 3株不同根际促生菌单独施加及其与肥料(鸡粪+微量元素)配施对镉砷复合污染土壤中巨菌草迁移...