北京大气PM_(2.5)中铅的同位素测定和来源研究

用石英滤膜连续采集北京2003—02～2003—03的12个PM2．5样品，进行无机多元素、OC、EC和铅同位素丰度比的分析测定．对样品进行聚类分析，结合气象信息讨论了分组结果，描述了2003年春北京市的2个大气铅污染过程．2个污染过程均表现出铅含量高，^206Pb／^207Pb丰度比低的特点．Al、Ca、K等地壳元素的含量与Pb的含量负相关，表明土壤尘对铅的贡献不大．比较Pb、A5、Zn、Se和Al、Ca等地壳元素含量的相关性，2个铅污染过程是由有色冶金排放和燃煤排放共同主导的．而02—28～03-02的铅污染过程中，燃煤排放贡献增大，有色冶金排放贡献下降．结果表明，汽油无铅化以后，北京市春季大气颗粒物中的铅主要来源于有色冶金排放与燃煤排放。

中国北京和长岛大气颗粒物中铅的同位素丰度比测定(英文)

采用高分辨电感耦合等离子体质谱技术(HRICPMS)分析了48个不同季节大气气溶胶颗粒样品中铅同位素丰度(A)比值,为中国城市铅污染源研究提供数据。样品采自中国北京和山东长岛地区(2002～2003年期间不同季节)。A(206Pb/207Pb)和A(208Pb/207Pb)的10次测定精密度为0.05%～0.19%RSD。

Australasian microtektites across the Antarctic continent: Evidence from the Sør Rondane Mountain range (East Antarctica)

The~790 ka Australasian(micro)tektite strewn field is one of the most recent and best-known examples of impact ejecta emplacement as the result of a large-scale cratering event across a considerable part of Earth's surface(>10%in area).The Australasian strewn field is characterized by a tri-lobe pattern consisting of a large central distribution lobe,and two smaller side lobes extending to the west and east.Here,we report on the discovery of microtektite-like particles in sedimentary traps,containing abundant micrometeorite material,in the Sør Rondane Mountain(SRM)range of East Antarctica.The thirty-three glassy particles display a characteristic pale yellowcolor and are predominantly spherical in shape,except for a single dumbbell-shaped particle.The vitreous spherules range in size from220 to 570μm,with an average diameter of~370μm.This compares relatively well with the size distribution(75–778μm)of Australasian microtektites previously recovered from the TransantarcticMountains(TAM)and located ca.2500–3000 km fromthe SRM.In addition,the chemical composition of the SRM particles exhibits limited variation and is nearly identical to the‘normal-type’(i.e.,<6%MgO)TAM microtektites.The Sr and Nd isotope systematics for a single batch of SRM particles(n=26)strongly support their affiliation with TAMmicrotektites and the Australasian tektite strewn field in general.Furthermore,Sr isotope ratios and Nd model ages suggest that the target material of the SRM particles was composed of a plagioclase-or carbonate-rich lithology derived from a Paleo-or Mesoproterozoic crustal unit.The affiliation to the Australasian strewn field requires long-range transportation,with estimated great circle distances of ca.11,600 km from the hypothetical source crater,provided transportation occurred along the central distribution lobe.This is in agreement with the observations made for the Australasian microtektites recovered from Victoria Land(ca.11,000 km)and Larkman Nunatak(ca.12,000 km),which,on average,decrease in size and alkali concentrations(e.g.,Na and K)as their distance from the source crater increases.The values for the SRMparticles are intermediate to those of the Victoria Land and Larkman Nunatak microtektites for both parameters,thus supporting this observation.We therefore interpret the SRM particles as‘normal-type’Australasian microtektites,which significantly extend the central distribution lobe of the Australasian strewn field westward.Australasian microtektite distribution thus occurred on a continent-wide scale across Antarctica and allows for the identification of new,potential recovery sites on the Antarctic continent as well as the southeastern part of the Indian Ocean.Similar to volcanic ash layers,the~790 ka distal Australasian impact ejecta are thus a record of an instantaneous event that can be used for time-stratigraphic correlation across Antarctica.

Resolving impact volatilization and condensation from target rock mixing and hydrothermal overprinting within the Chicxulub impact structure

This work presents isotopic data for the non-traditional isotope systems Fe,Cu,and Zn on a set of Chicxulub impactites and target lithologies with the aim of better documenting the dynamic processes taking place during hypervelocity impact events,as well as those affecting impact structures during the post-impact phase.The focus lies on material from the recent IODP-ICDP Expedition 364 Hole M0077A drill core obtained from the offshore Chicxulub peak ring.Two ejecta blanket samples from the UNAM 5 and 7 cores were used to compare the crater lithologies with those outside of the impact structure.The datasets of bulk Fe,Cu,and Zn isotope ratios are coupled with petrographic observations and bulk major and trace element compositions to disentangle equilibrium isotope fractionation effects from kinetic processes.The observed Fe and Cu isotopic signatures,with δ^(56/54)Fe ranging from0.95‰to 0.58‰and δ^(65/63)Cu from0.73‰to 0.14‰,mostly reflect felsic,mafic,and carbonate target lithology mixing and secondary sulfide mineral formation,the latter associated to the extensive and long-lived(>105 years)hydrothermal system within Chicxulub structure.On the other hand,the stable Zn isotope ratios provide evidence for volatility-governed isotopic fractionation.The heavier Zn isotopic compositions observed for the uppermost part of the impactite sequence and a metamorphic clast(δ^(66/64)Zn of up to 0.80‰and 0.87‰,respectively)relative to most basement lithologies and impact melt rock units indicate partial vaporization of Zn,comparable to what has been observed for Cretaceous-Paleogene boundary layer sediments around the world,as well as for tektites from various strewn fields.In contrast to previous work,our data indicate that an isotopically light Zn reservoir(δ^(66/64)Zn down to0.49‰),of which the existence has previously been suggested based on mass balance considerations,may reside within the upper impact melt rock(UIM)unit.This observation is restricted to a few UIM samples only and cannot be extended to other target or impact melt rock units.Light isotopic signatures of moderately volatile elements in tektites and microtektites have previously been linked to(back-)condensation under distinct kinetic regimes.Although some of the signatures observed may have been partially overprinted during post-impact processes,our bulk data confirm impact volatilization and condensation of Zn,which may be even more pronounced at the microscale,with variable degrees of mixing between isotopically distinct reservoirs,not only at proximal to distal ejecta sites,but also within the lithologies associated with the Chicxulub impact crater.

Electrochemically assisted production of biogenic palladium nanoparticles for the catalytic removal of micropollutants in wastewater treatment plants effluent

Biogenic palladium nanoparticles(bio-Pd NPs)are used for the reductive transformation and/or dehalogenation of persistent micropollutants.In this work,H2(electron donor)was produced in situ by an electrochemical cell,permitting steered production of differently sized bio-Pd NPs.The catalytic activity was first assessed by the degradation of methyl orange.The NPs showing the highest catalytic activity were selected for the removal of micropollutants from secondary treated municipal wastewater.The synthesis at different H2 flow rates(0.310 L/hr or 0.646 L/hr)influenced the bio-Pd NPs size.The NPs produced over 6 hr at a lowH2 flow rate had a larger size(D50=39.0 nm)than those produced in 3 hr at a high H2 flow rate(D50=23.2 nm).Removal of 92.1%and 44.3%of methyl orange was obtained after 30 min for the NPs with sizes of 39.0 nm and 23.2 nm,respectively.Bio-Pd NPs of 39.0 nm were used to treat micropollutants present in secondary treated municipal wastewater at concentrations ranging fromμg/L to ng/L.Effective removal of 8 compounds was observed:ibuprofen(69.5%)<sulfamethoxazole(80.6%)<naproxen(81.4%)<furosemide(89.7%)<citalopram(91.7%)<diclofenac(91.9%)<atorvastatin(>94.3%)<lorazepam(97.2%).Re-moval of fluorinated antibiotics occurred at>90%efficiency.Overall,these data indicate that the size,and thus the catalytic activity of the NPs can be steered and that the removal of challengingmicropollutants at environmentally relevant concentrations can be achieved through the use of bio-Pd NPs.