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991.
992.
Seasonal variation, source, and regional representativeness of the background aerosol from two remote sites in western China 总被引:1,自引:0,他引:1
Wenjun Qu Dan Wang Yaqiang Wang Lifang Sheng Gang Fu 《Environmental monitoring and assessment》2010,167(1-4):265-288
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?+?, Mg2?+?, and Cl??? at ZUZ. At AKD, ionic Ca2?+?, Mg2?+?, Na?+?, and Cl??? primarily originated from salinized soil. Furthermore, the WS Ca2?+? 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. 相似文献
993.
Effects of temperature parameters on thermal-optical analysis of organic and elemental carbon in aerosol 总被引:1,自引:0,他引:1
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. 相似文献
994.
Soil water, salt, and groundwater characteristics in shelterbelts with no irrigation for several years in an extremely arid area 总被引:2,自引:0,他引:2
Xinfeng Zhao Hailiang Xu Peng Zhang Jinyi Fu Yuan Bai 《Environmental monitoring and assessment》2013,185(12):10091-10100
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. 相似文献
995.
996.
Preparation and utilization of molecularly imprinted polymer for chlorsulfuron extraction from water, soil, and wheat plant 总被引:1,自引:0,他引:1
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. 相似文献
997.
传统给水处理厂氯消毒模型的开发与应用 总被引:1,自引:1,他引:0
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%. 相似文献
998.
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。 相似文献
999.
1000.
Xinhua Fu V. Benno Meyer-Rochow John Tyler Hirobumi Suzuki Raphael De Cock 《Chemoecology》2009,19(3):155-168
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. 相似文献