Seasonal variation, source, and regional representativeness of the background aerosol from two remote sites in western China

Using observations from two remote sites during July 2004 to March 2005, we show that at Akdala (AKD, 47° 06′ N, 87° 58′ E, 562 m asl) in northern Xinjiang Province, there were high wintertime loadings of organic carbon (OC), elemental carbon (EC), and water-soluble (WS) ${\rm SO}_{4}^{2-}$ , ${\rm NO}_{3}^{2-}$ , and ${\rm NH}_{4}^{+}$ , which is similar to the general pattern in most areas of China and East Asia. However, at Zhuzhang (ZUZ, 28° 00′ N, 99° 43′ E, 3,583 m asl) in northwestern Yunnan Province, the aerosol concentrations and compositions showed little seasonal variation except for a decreasing trend of OC from August to autumn–winter. Additionally, the OC variations dominated the seasonal variation of PM₁₀ (particles ≤10 μm diameter) level. Chemical characteristics combined with transport information suggested sea salt origin of ionic Na^?+?, Mg^2?+?, and Cl^??? at ZUZ. At AKD, ionic Ca^2?+?, Mg^2?+?, Na^?+?, and Cl^??? primarily originated from salinized soil. Furthermore, the WS Ca^2?+? contributions (5.4–6%) to the PM₁₀ mass during autumn, winter, and early spring reflected a constant dust component. The results of this study indicated that both sites were regionally representative. However, the representative regions and scales of these background sites may vary seasonally as the regional atmospheric transport patterns change. Seasonal variations in the background aerosol levels from these two areas need to be considered when evaluating the regional climate effects of the aerosols.     

Effects of temperature parameters on thermal-optical analysis of organic and elemental carbon in aerosol

Thermal-optical analysis (TOA) is a popular method to determine aerosol elemental carbon (EC) and organic carbon (OC) collected on quartz fiber filter. However, temperature protocol adopted in TOA has great effects on OC and EC results. The purpose of this study is to investigate and quantify the effects of maximum temperature (T(max)) and residence time (RT) for each step in helium stage on ECOC measurements. Fourteen typical source samples and 20 ambient samples were collected and six temperature programs were designed for this study. It was found that EC value decreases regularly as T(max ) ascends, i.e., EC results from T(max) of 650 degrees C, 750 degrees C and 850 degrees C are 0.89 +/- 0.06, 0.76 +/- 0.10, 0.62 +/- 0.13 times EC value from T( max) of 550 degrees C, respectively, and the magnitude of EC drop (EC(d), percent) is significantly correlated with OC abundance in total carbon (R(OC/TC)), expressed as EC(d) = 66.8R(OC/TC)-14.4 (r = 0.87); pyrolized OC(POC) values are also sensitive to T(max), but there are various trends for samples with different OC constituents. On average of the samples studied here, prolonged RT reduces EC values by only 3%, almost negligible compared to the effect of T(max), and reduces POC by 9%, much less than that by previous report.     

Soil water, salt, and groundwater characteristics in shelterbelts with no irrigation for several years in an extremely arid area

This paper is based on long-term monitoring data for soil water, salt content, and groundwater characteristics taken from shelterbelts where there has been no irrigation for at least 5 years. This study investigated the distribution characteristics of soil water and salt content in soils with different textures. The relationships between soil moisture, soil salinity, and groundwater level were analyzed using 3 years of monitoring data from a typical oasis located in an extremely arid area in northwest China. The results showed that (1) the variation trend in soil moisture with soil depth in the shelterbelts varied depending on soil texture. The soil moisture was lower in sandy and loamy shelterbelts and higher in clay shelterbelts. (2) Salinity was higher (about 3.0 mS cm^?1) in clay shelterbelts and lower (about 0.8 mS cm^?1) in sandy shelterbelts. (3) There was a negative correlation between soil moisture in the shelterbelts and groundwater level. Soil moisture decreased gradually as the depth of groundwater table declined. (4) There was a positive correlation between soil salinity in the shelterbelts and the depth of groundwater table. Salinity increased gradually as groundwater levels declined.     

Preparation and utilization of molecularly imprinted polymer for chlorsulfuron extraction from water, soil, and wheat plant

A molecularly imprinted polymer (MIP) was prepared using chlorsulfuron (CS), a herbicide as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, methanol and toluene as a porogen, and 2,2-azobisisobutyronitrile as an initiator. The binding behaviors of the template chlorsulfuron and its analog on MIP were evaluated by equilibrium adsorption experiments, which showed that the MIP particles had specific affinity for the template CS. Solid-phase extraction (SPE) with the chlorsulfuron molecularly imprinted polymer as an adsorbent was investigated. The optimum loading, washing, and eluting conditions for chlorsulfuron molecularly imprinted polymer solid-phase extraction (CS-MISPE) were established. The optimized CS-MISPE procedure was developed to enrich and clean up the chlorsulfuron residue in water, soils, and wheat plants. Concentrations of chlorsulfuron in the samples were analyzed by HPLC-UVD. The average recoveries of CS spiked standard at 0.05~0.2 mg L(-1) in water were 90.2~93.3%, with the relative standard deviation (RSD) being 2.0~3.9% (n=3). The average recoveries of 1.0 mL CS spiked standard at 0.1~0.5 mg L(-1) in 10 g soil were 91.1~94.7%, with the RSD being 3.1~5.6% (n=3). The average recoveries of 1.0 mL CS spiked standard at 0.1~0.5 mg L(-1) in 5 g wheat plant were 82.3~94.3%, with the RSD being 2.9~6.8% (n=3). Overall, our study provides a sensitive and cost-effective method for accurate determination of CS residues in water, soils, and plants.     

传统给水处理厂氯消毒模型的开发与应用

以建立给水处理过程的风险分析方法为目标,提出了适用于传统给水处理工艺的氯消毒概率机理模型.模型既考虑氯消毒过程中有机物、余氯、氨氮、溴离子之间化学反应,又考虑水厂混凝、沉淀和过滤工艺过程中的物理和生物作用.典型水厂的现场监测数据表明,该模型能够较好地模拟水厂中高锰酸盐指数、氨氮以及4种三卤甲烷的浓度概率分布.Monte Carlo模拟的结果表明,与我国城市供水水质标准相比,该水厂高锰酸盐指数和单种三卤甲烷的超标概率极低,但总三卤甲烷的超标概率略高,约为2.3%.     

曝气生物滤池处理医院污水的实验应用研究

采用曝气生物滤池与二氧化氯相结合的工艺处理医院污水。主要对曝气生物滤池去除COD、氨氮的效果进行了研究,并且在实际应用中证明了用这种相结合的处理方法具有一次投资小、运行费用低、年经济效益高等优点,有良好的技术经济性。     

如何防止运动性腹痛

参与您所喜爱并力所能及的运动时．如跑步、打球、练拳、游泳、登山、骑自行车等．它们能帮助人抵抗疾病．主要是运动能使体内产生“致热原”有关。人在运动时,由于肌肉活动加强,体内产生大量热量,并使体温升高．据测定．慢速长跑后腋下温度可升到37．5-38℃。这种热在运动结束后还会持续一段时间。正常情况下,人的体温为37℃。一旦病毒、病菌侵入人体引起感染．体内就会产生一种奇妙的物     

Structure and function of the eversible organs of several genera of larval firefly (Coleoptera: Lampyridae)

Larval defensive behaviour and eversible organ morphology were compared in the firefly species Luciola cruciata Motschulsky 1854, L. lateralis Motschulsky 1860, L. leii Fu et Ballantyne 2006, Lampyris noctiluca Linnaeus 1767, Pyrocoelia analis Fabricius 1801, P. pectoralis Oliver 1883, P. sp. and two Diaphanes species. In all cases the eversible organs are located on the pleural cuticle, dorsal to the spiracle, but there is considerable variation between species in their number, size and shape. In La. noctiluca they are confined to the abdomen, whereas in the other species they also occur on the meta- and mesothorax. In La. noctiluca and the Pyrocoelia species the organs are columnar in shape, contrasting with the forked organs of the Luciola and Diaphanes species. The eversible organs of the Luciola species, which are all aquatic, are remarkably larger (relative to body length) than those of the other, terrestrial species. On organ eversion the Luciola species emit an odour resembling pine oil, the Diaphanes species smell weakly of mint and L. noctiluca and the Pyrocoelia species produce no discernible scent, though ants are nonetheless repelled by contact with everted L. noctiluca organs. The organs of all the species studied support protuberances on their external surface, though these too vary in shape, size and ornamentation between species. In all species except L. noctiluca each protuberance is connected to a well-developed globular body via a long, thick stalk. Circular foveae are located in the centres of these globular bodies. The globular bodies consist of secretory cells characterized by the presence of numerous mitochondria and an extensive system of cisternae and tubular endoplasmic reticulum. Behavioural tests revealed that small larvae run away instead of becoming immobile and glowing, whereas large larvae start to glow when disturbed. The study shows that the eversible larval organs form an important part of a defensive arsenal in the Lampyridae.     

广州大气低分子量羰基化合物的季节变化

对广州市区荔湾和五山两个代表性采样点的低分子量羰基化合物(甲醛、乙醛、丙酮和丙醛)进行了季节变化研究.实验方法是应用羰基化合物和2,4-二硝基苯肼(DNPH)迅速反应生成衍生物,产物在高效液相色谱上检测.按冬、夏两季进行样品采集,每次连续采样4 d.研究发现丙酮质量浓度最高,其次是甲醛和乙醛.夏季的羰基化合物质量浓度值高于冬季的.除丙酮外,甲醛、乙醛、丙醛的质量浓度是荔湾采样点高于五山采样点.甲醛/乙醛、乙醛/丙醛质量浓度比值显示广州大气中羰基化合物主要与人为来源有关.羰基化合物之间的相关性冬季好于夏季,暗示羰基化合物冬季来源比夏季简单.羰基化合物的来源主要有汽车排放、大气光化学反应,还可能与植物排放、烟草烟气、实验室所用溶剂有关.     

干降尘中高分子有机质的组成及其来源

大气降尘作为地气交换的一种重要物质,一直受到研究学者的关注.传统研究较多的是无机元素和小分子有机物,对于占干降尘有机质中相当部分的高分子有机质研究很少,因此研究降尘原样中有机大分子的组成和来源有着重要意义.用裂解-气相色谱-质谱(pyrolysis-gas chromatography-mass spectrometry,Py-GC-MS)技术对分别代表市区和郊区的五山和大学城两个采样点冬夏两季样品中的高分子有机质的组成和来源进行探讨表明,有来源于多糖类的化合物、来源于木质素类的化合物、来源于蛋白质/氨基酸类的化合物、脂肪酸、正构烷烃/烯烃以及一些不能确定其来源的化合物,其中正构烷烃/烯烃和芳香化合物是干降尘中高分子有机质的主要裂解产物.研究同时表明其来源首先取决于采样点的环境,同时也会受到气候的影响.