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941.
942.
The reactions of gas-phase anthracene and suspended anthracene particles with O3 and O3-NO were conducted in a 200-L reaction chamber, respectively. The secondary organic aerosol (SOA) formations from gas-phase reactions of anthracene with O3 and O3-NO were observed. Meanwhile, the size distributions and mass concentrations of SOA were monitored with a scanning mobility particle sizer (SMPS) during the formation processes. The rapid exponential growths of SOA reveal that the atmospheric lifetimes of gas-phase anthracene towards O3 and O3-NO are less than 20.5 and 4.34 hr, respectively. The particulate oxidation products from homogeneous and heterogeneous reactions were analyzed with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). Gas chromatograph/mass spectrometer (GC/MS) analyses of oxidation products of anthracene were carried out for assigning the time-of-flight (TOF) mass spectra of products from homogeneous and heterogeneous reactions. Anthrone, anthraquinone, 9,10- dihydroxyanthracene, and 1,9,10-trihydroxyanthracene were the ozonation products of anthracene, while anthrone, anthraquinone, 9-nitroanthracene, and 1,8-dihydroxyanthraquinone were the main products of anthracene with O3-NO. 相似文献
943.
沼液经过充分发酵,其中富含多种作物所需的营养物质,因而宜作根外施肥,其效果优于化肥。在此基础上,筛选并复配PGPR根圈促生菌到沼液中,形成有机沼液生物肥。有机沼液生物肥是集营养、促生和生防为一体的多功能生物肥料。施用有机沼液生物肥辣椒果实维生素c含量达到了78.28mg/kg,比处理CK增加31%,可溶性糖含量提高32.4%。应用有机沼液生物肥番茄维生素c含量比对照增加46.6%,可溶性糖含量提高45%。施用有机沼液生物肥的黄瓜Vc含量比对照提高56.8%,可溶性糖含量提高84.2%。 相似文献
944.
Shiming Ding Di Xu Xiuling Bai Shuchun Yao Chengxin Fan Chaosheng Zhang 《环境科学学报(英文版)》2013,25(5):925-932
The understanding of organic phosphorus(P) dynamics in sediments requires information on their species at the molecular level,but such information in sediment profiles is scarce.A sediment profile was selected from a large eutrophic lake,Lake Taihu(China),and organic P species in the sediments were detected using solution phosphorus-31 nuclear magnetic resonance spectroscopy(31 P NMR) following extraction of the sediments with a mixture of 0.25 mol/L NaOH and 50 mmol/L EDTA(NaOH-EDTA) solution.The results showed that P in the NaOH-EDTA extracts was mainly composed of orthophosphate,orthophosphate monoesters,phospholipids,DNA,and pyrophosphate.Concentrations of the major organic P compound groups and pyrophosphate showed a decreasing trend with the increase of depth.Their half-life times varied from 3 to 27 years,following the order of orthophosphate monoesters > phospholipids DNA > pyrophosphate.Principal component analysis revealed that the detected organic P species had binding phases similar to those of humic acid-associated organic P(NaOH-NRP HA),a labile organic P pool that tends to transform to recalcitrant organic P pools as the early diagenetic processes proceed.This demonstrated that the depth attenuation of the organic P species could be partly attributed to their increasing immobilization by the sediment solids,while their degradation rates should be significantly lower than what were suggested in previous studies. 相似文献
945.
上海市含碳大气颗粒物的粒径分布 总被引:1,自引:4,他引:1
使用STAPLEX大流量六级采样器(<0.49μm、0.49~0.95μm、0.95~1.5μm、1.5~3.0μm、3.0~7.2μm和>7.2μm),结合DRI Model 2001热光碳分析仪(TOR),分析了2010年5月~2011年5月期间上海市嘉定区(市郊)、徐汇区(市区)的大气颗粒物样品中有机碳(OC)和元素碳(EC)的粒径分布.结果表明,不同粒径的OC和EC质量浓度均呈双峰分布,较高峰出现于<0.49μm粒径段,次高峰则出现于>3.0μm的两个粒径段.嘉定区(JD)和徐汇区(XH)PM3.0中OC的质量浓度分别为16.35μg.m-3和11.85μg.m-3,EC质量浓度分别为2.22μg.m-3和1.91μg.m-3,市郊大气颗粒物中碳组分质量浓度高于市区,说明市郊碳污染更为严重.在<1.5μm的粒径段,嘉定区OC与EC的同源性较好,表明其中大部分OC来自于燃烧源.两地区不同粒径OC/EC值与不同排放源特征值的对比,可以说明徐汇区更多受到机动车尾气排放和道路扬尘的影响.通过EC示踪法计算二次有机碳(SOC)质量浓度可知:上海市SOC质量浓度较高,PM3.0中达到6.76μg.m-3,占OC的质量分数为69%,粒径分布呈双峰分布,峰值位于0.49~0.95μm和3.0~7.2μm粒径段. 相似文献
946.
Mara C. Diguez Claudia P. Queimalios Sergio Ribeiro Guevar Mark Marvin-DiPasquale Carolina Soto Crdenas Mara A. Arribre 《环境科学学报(英文版)》2013,25(10):1980-1991
Ligands present in dissolved organic matter (DOM) form complexes with inorganic divalent mercury (Hg^2+) affecting its bioavailability in pelagic food webs. This investigation addresses the influence of a natural gradient of DOM present in Patagonian lakes on the bioaccumulation of Hg^2+ (the prevailing mercury species in the water column of these lakes) by the algae Cryptomonas erosa and the zooplankters Brachionus calyciflorus and Boeckella antiqua. Hg^2+ accumulation was studied through laboratory experiments using natural water of four oligotrophic Patagonian lakes amended with^197Hg^2+. The bioavailability of Hg^2+ was affected by the concentration and character of DOM. The entrance of Hg^2+ into pelagic food webs occurs mostly through passive and active accumulation. The incorporation of Hg^2+ by Cryptomonas, up to 27% of the Hg^2+ amended, was found to be rapid and dominated by passive adsorption, and was greatest when low molecular weight compounds with protein-like or small phenolic signatures prevailed in the DOM. Conversely, high molecular weight compounds with a humic or fulvic signature kept Hg^2+ in the dissolved phase, resulting in the lowest Hg^2+ accumulation in this algae. In Brachionus and Boeckella the direct incorporation of Hg from the aqueous phase was up to 3% of the Hg^2+ amended. The dietary incorporation of Hg^2+ by Boeckella exceeded the direct absorption of this metal in natural water, and was remarkably similar to the Hg^2+ adsorbed in their prey. Overall, DOM concentration and character affected the adsorption of Hg^2+ by algae through competitive binding, while the incorporation of Hg^2+ into the zooplankton was dominated by trophic or dietary transfer. 相似文献
947.
为研究太湖dAPS(dissolved acidic polysaccharides,溶解性酸性多糖)的时空变化,探讨湖泊水体中dAPS对有机碳的贡献和重要性,于2012年春、夏季调查了太湖北部不同湖区(竺山湾、梅梁湾、贡湖湾、湖心区)水体中ρ(dAPS),分析了其时空变化特征及其与ρ(Chla)之间的关系,并探讨了不同湖湾中dAPS对DOC(溶解性有机碳)的贡献率. 结果表明,太湖北部水体中ρ(dAPS)春、夏季变化范围为3.02~9.93mg/L,平均值为(6.10±1.59) mg/L. 夏季太湖北部各湖区之间ρ(dAPS)没有显著性差异,春季梅梁湾中ρ(dAPS)显著高于湖心区(P<0.05),其他湖区并没有显著性差异. 春、夏两季ρ(dAPS)的最低值均出现在湖心区. 除贡湖湾外,夏季太湖北部各湖区ρ(dAPS)与ρ(Chla)都存在显著线性正相关,而春季各湖区则无显著线性关系. 这说明春、夏季dAPS的受控因素不一样,夏季ρ(dAPS)受藻类影响较大. 夏季各湖区dAPS对DOC的贡献率以贡湖湾最高,平均值高达46.7%±7.7%,春季则以梅梁湾的贡献率较高,平均值为68.6%±5.9%,这意味着dAPS在太湖水体有机碳循环中起着重要的作用. 相似文献
948.
949.
研究砖红壤对F-的吸附反应尤其是随后Al3+的释放过程,有助于增进对土壤酸化过程及其环境影响的理解. 在初步揭示出F-吸附反应以及Al3+释放反应的动力学特征基础上,重点考察了pH和有机酸对上述反应的影响. 结果表明:土壤对F-的吸附反应十分迅速,2 min内吸附量即可达到24 h内总吸附量95%,而土壤中不同含铝矿物的溶解度差异使Al3+的释放过程在前15 min十分迅速,释放量可达24 h内总释放量的80%,随后则逐渐减缓. 降低反应体系pH可促进Al3+释放,但会使F-吸附量减少,这是因为伴随Al3+的释放,部分F-又可以AlF络合物的形态重新进入溶液,尽管在低pH条件下,土壤表面以带正电荷为主而有利于F-吸附. 草酸和抗坏血酸对土壤吸附F-均有抑制作用,但对F-溶出土壤Al3+有促进作用. 此外,草酸对土壤铁氧化物的选择性溶解作用,可使更多F-吸附在土壤铝氧化物位点,并导致Al3+释放量增加. 相似文献
950.
目的研究不同破损程度下军绿有机涂层的腐蚀行为,确定破损率对其防护性能变化的影响。方法通过人工制作不同的破损率,并利用电化学阻抗谱技术,研究不同破损程度下军绿有机涂层的电化学特征。结果根据不同破损程度下的军绿有机涂层的电化学特征,确定了涂层从完好到失效的四个阶段,初始完好阶段(破损率K≤0.0004%)、破损增大阶段(0.0016%K≤0.04%)、破损过大阶段(0.16%K≤1%)和失效阶段(4%K≤16%)。结论破损率K为0.04%的点是该涂层防护性能急转直下的转折点,因此破损率K大于0.04%时,应及时对车辆表面涂层进行修补和防护。 相似文献