Diurnal variation of number concentration and size distribution of ultrafine particles in the urban atmosphere of Beijing in winter

Number concentration and distribution of airborne particles in the size range 5.6 to 560 um diameter were measured in Beijing for a 15-d period in winter 2005.Daily average number concentrations of nucleation mode(5.6-20 nm),Aitken mode(20-100 nm), and accumulation mode(100-560 nm)particles,and total particles were 17500,32000,4000,and 53500 cm~(-3),respectively.Average particle size distribution was monomodal with a mode diameter of about 40 um at night and bimodal with mode diameters of about 10 and about 40 nm during the daytime.New particle formation events,which were connected to diurnal variation of nucleation mode particles,were observed in more than half of the observation days.The events often started around 10:00-11:00 Chinese Standard Time (CST)and ended up after 3-4 h.Concentrations of Aitken and accumulation mode particles increased from midnight and reached their maxima at about 10:00 CST,and then decreased and became the lowest in the afternoon.Analysis of diurnal cycles in traffic volume and meteorological parameters revealed that the accumulation of the particles in Aitken and accumulation modes in the morning was influenced by formation of an inversion and increase in vehicle emission,and dispersion of such particles in the afternoon was associated with more effective vertical mixing and higher wind speed.     

蒸馏体积100ml测定水中氰化物探讨

实验表明，水中氰化物测定，蒸馏体积１００ｍｌ即能达到环境监测技术要求，与标准方法规定蒸馏体积２００ｍｌ相比，可提高工效、节约用电和节省试剂。     

Mineralogy of Atmospheric Suspended Dust in Three Indoor And One Outdoor Location in Oman

The aim of this work is to characterize the mineral phases present in the atmosphere at three locations in northern Oman. Samples of atmospheric particles were collected using a high volume sampler. Three indoor and one outdoor location were chosen in this investigation. Sampling locations included a residential house located nearby the cement plant, a residential house located nearby a refinery plant, and a residential house located at Al-Suwayq residential area. Indoor air was sampled from these three houses. Moreover, for the Al-Suwayq residential house, sampling was also taken outside the house for comparison. The dust samples were analysed for their microanalysis characterization and their mineral contents as well. The microanalysis enabled us to identify the metals present in the particles. Furthermore, the mineralogical analysis of the sample filters showed the presence of quartz as the principal phase inside the house of Al-Suwayq, whereas quartz, dolomite, and gypsum were common phases outside the house. In the residential house nearby the cement plant, it was found that calcite, quartz, dolomite and goethite were the principal phases whereas the particles collected from the house nearby the refinery composed primarily of dolomite and calcite. The airborne dust collected at the refinery and Al-Suwayq were probably sourced in the natural environment and mobilised by natural processes. However, at the cement factory the crushing and grinding of limestone during the industrial process has contributed significantly to the airborne dust load. Generally, the information obtained in this study will be invaluable as no data for the mineral content of atmospheric dust existed in the Oman.     

土壤中有效态重金属的化学试剂提取法研究进展

土壤重金属污染是国内外关注的热点问题，针对采用全量重金属评价土壤污染存在的问题，本文综述了近年来土壤有效态重金属的化学提取方法研究进展，比较分析了各种单一提取法和影响土壤重金属提取率的因素。在此基础上，评价了各类提取方法的特点及其在应用上的优势和局限，指出了筛选通用提取剂的原则和依据。结合实验初步提出以去离子水作为通用提取剂的可行性及尚需研究解决的问题。     

木薯和花生间作对Cd吸收及根区速效养分的影响

木薯（Manihot esculenta Crantz）是热带和亚热带广泛种植的大生物量能源植物,在污染土壤上具有较强的生物修复潜力,花生（Arachis hypogaea）对土壤Cd具有很强的富集能力.木薯与花生间作可充分利用光热水资源,具有良好的间作优势,是近年来我国南方红壤坡耕地生态种植模式.为了解木薯与花生间作对土壤Cd吸收及根区速效养分的影响,在重金属Cd污染的小区进行了木薯单作、花生单作、木薯与花生间作的比较试验.结果表明,木薯与花生间作的产量土地当量比（LER）大于1,土地利用率提高了87.0%.与木薯单作相比,间作下木薯茎和叶w（Cd）分别降低了12.24%和19.51%,二者呈显著性差异（P < 0.05）,花生籽粒w（Cd）降低了35.38%,与单作花生差异显著（P < 0.05）.与单作下木薯和花生相比,花生、木薯总富集系数分别降低了16.32%、12.45%,间作系统对每hm2土地上Cd的富集量分别提高了10.72%、113.76%;间作下花生根区土壤w（速效氮）、w（速效磷）分别提高了18.85%、20.36%,木薯根区土壤w（速效氮）提高了21.00%,与单作下花生和木薯相比均呈显著性差异（P < 0.05）.研究显示,木薯与花生间作可提高土壤根区速效养分含量,促进作物生长,在提高作物生物量、降低作物各部位单位Cd含量的同时,可提高间作系统对土壤Cd的富集量,这种间作方式对实现两种能源植物生态修复及经济效益的整合具有重要意义.      

黄土丘陵区典型植被枯落物坡面分布及混入土壤对土壤性状的影响

黄土丘陵区植被的恢复可能影响枯落物分布特征,进而对土壤性状产生影响。论文选取刺槐（Robinia pseudoacacia）人工林、柠条（Caragana intermedia）人工林、铁杆蒿（Artemisia gmelini）群落和白羊草（Bothriochloa ischaemum）群落4种典型植被样地,研究其枯落物坡面（坡长40~80 m）分布特征及自然条件混入土壤中对土壤理化性状的影响。结果表明：1）4种典型植被样地地表枯落物蓄积量（143.89~833.04 g/m²）、盖度（0.36~0.63）和厚度（0.77~2.03 cm）均表现为刺槐人工林>柠条人工林>铁杆蒿群落>白羊草群落;土壤中枯落物混入量（178.80~657.21 g/m²）和混入深度（1.33~2.29 cm）均表现为刺槐人工林>铁杆蒿群落>柠条人工林>白羊草群落;土壤中枯落物混入量占枯落物总蓄积量的比例（45.91%~74.02%）表现为铁杆蒿群落>柠条人工林>白羊草群落>刺槐人工林。2）4种典型植被样地地表枯落物蓄积量和土壤中枯落物混入量均为坡下高于坡上,受径流冲刷和泥沙分离—输移—沉积过程的影响,枯落物地表蓄积量和土壤混入量在坡中波动较大;随枯落物地表盖度的增加,地表枯落物蓄积量呈指数函数增加（P<0.01）,且随地表枯落物蓄积量的增加,土壤中枯落物混入量呈对数函数增加（P<0.01）。3）土壤容重、粘结力和水稳性团聚体几何平均直径（WAS-GMD）随土壤中枯落物混入量的增大而线性降低（P<0.01）,土壤有机碳和全氮含量在铁杆蒿群落和白羊草群落中均随土壤中枯落物混入量的增大而线性增加（P<0.05）。该研究将为评价黄土高原退耕还林还（草）工程生态成效、修正土壤侵蚀预报模型提供重要依据。     

冈底斯中段冷布岗日嘎尔琼沟MIS3以来冰川重建及其平衡线高程估算

冰川与全球气候变化、水资源保护等有着密切关系。根据前人测得的嘎尔琼沟冰碛物¹⁰Be暴露年龄,以及冰川塑性流动理论重建深海氧同位素3阶段（MIS3）以来12次冰进期古冰川表面高程和厚度分布,并分别运用积累区面积比率法（accumulation area ratio,AAR）和面积-高程平衡率法（area altitude balance ratio,AABR）重新估算各期冰川作用的平衡线高程（equilibrium-line altitude,ELA）。结果显示：（1）该冰川面积从MIS3时期的18 km²减少为现在的7.5 km²,小冰期（Little Ice Age,LIA）以来锐减;（2）冰川体积从MIS3时期的1.909 km³减少为现在的0.703 km³,缩减1.206 km³;（3）ELA自MIS3以来上升296 m或227 m,MIS2早期以来上升220 m或178 m,末次冰盛期（Last Glacial Maximum,LGM）以来上升206 m或169 m,早全新世以来上升169 m或144 m,新冰期以来上升113 m或108 m,LIA以来上升79 m或85 m。通过区域对比发现,从30 ka BP开始,青藏高原总体上趋向干旱化,嘎尔琼沟冰进规模逐次减小是对干旱化气候背景的响应。新冰期研究区冰川萎缩速度加快,可能与青藏高原季风在同时期的显著减弱有关。     

香港地区滑坡体积与前期降水关系分析

滑坡灾害发生的因子可以分为两种类型 ,即滑坡体所处的环境静态因子 ,如地形、地质等 ,和滑坡的诱发因子 ,如强降水、地震等。香港地处夏季多雨的热带地区 ,每年均有大量因暴雨导致的滑坡灾害出现。为分析滑坡大小与前期降水的关系 ,文中选择了 2 6 2个滑坡样例 ,对它们进行了多种周期前期降水的定量化研究 ,发现不同类型的滑坡出现与前期降水有不同的关联关系 :每种类型的滑坡中体积较大的滑坡与前期降水均有明显的关系 ;对多数体积较小的滑坡 ,滑坡体积与前期降水量并没有明显的正相关关系。