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531.
为探讨内陆山区城市湖北省十堰市冬季PM2.5污染特征及来源构成,于2016年1月12日—2月4日在4个采样点位同步采集PM2.5样品,分析了无机元素、水溶性离子、有机碳和元素碳的质量浓度.并采集了十堰市主城区城市扬尘、裸露山体尘、建筑水泥尘、燃煤源、机动车尾气、工业源及餐饮油烟源等7类污染源,初步建立十堰市本地的污染源成分谱库,利用统计学方法研究冬季PM2.5的污染特征,并采用CMB受体模型及“二重源解析技术”分析其来源构成.结果表明:冬季采样期间,十堰市ρ(PM2.5)平均值达到110.65 μg/m3,超过GB 3095—2012《环境空气质量标准》二级标准24 h浓度限值,并且随空气RH(相对湿度)增加污染加重.城区3个采样点PM2.5化学组成及特征的空间差异不明显.PM2.5中ρ(TC)最高,其次是ρ(NO3-)和ρ(SO42-),与二次反应、机动车尾气、煤燃烧等密切相关.ρ(NO3-)/ρ(SO42-)为1.22,说明机动车尾气的影响较大.二次粒子、燃煤源和机动车尾气是十堰市城区冬季大气PM2.5的主要来源,贡献率分别为51.2%、10.9%和10.1%.研究显示,十堰市城区冬季ρ(PM2.5)超过GB 3095—2012二级标准,PM2.5的污染控制应以二次粒子、燃煤和机动车为主,采取多源控制原则. 相似文献
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Xiaoyang Yang Chunmei Geng Xuesong Sun Wen Yang Xinhua Wang Jianhua Chen 《环境科学学报(英文版)》2016,28(2):28-34
Polycyclic aromatic hydrocarbons(PAHs) are carcinogenic or mutagenic and are important toxic pollutants in the flue gas of boilers. Two industrial grade biomass boilers were selected to investigate the characteristics of particulate-bound PAHs: one biomass boiler retro-fitted from an oil boiler(BB1) and one specially designed(BB2) biomass boiler. One coal-fired boiler was also selected for comparison. By using a dilution tunnel system, particulate samples from boilers were collected and 10 PAH species were analyzed by gas chromatography–mass spectrometry(GC–MS). The total emission factors(EFs) of PAHs ranged from 0.0064 to0.0380 mg/kg, with an average of 0.0225 mg/kg, for the biomass boiler emission samples. The total PAH EFs for the tested coal-fired boiler were 1.8 times lower than the average value of the biomass boilers. The PAH diagnostic ratios for wood pellets and straw pellets were similar.The ratio of indeno(1,2,3-cd)pyrene/[indeno(1,2,3-cd)pyrene + benzo(g,h,i)perylene] for the two biomass boilers was lower than those of the reference data for other burning devices, which can probably be used as an indicator to distinguish the emission of biomass boilers from that of industrial coal-fired boilers and residential stoves. The toxic potential of the emission from wood pellet burning was higher than that from straw pellet burning, however both of them were much lower than residential stove exhausts. 相似文献
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Yan Zhang Lujun Chen Renhua Sun Tianjiao Dai Jinping Tian Wei Zheng Donghui Wen 《环境科学学报(英文版)》2016,28(6):57-68
Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; Marine_Group_Ⅰ and Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,Marine_Group_Ⅰ; and might be the primary driving force for the seasonal variation of the microbial community. 相似文献
534.
为更好地了解分析沉积物孔隙结构特征,本文通过CT技术及相关软件,对巢湖沉积物孔隙结构进行了三维重建,展现了巢湖沉积物真实的三维孔隙结构,并以此为基础定量计算了孔隙度、孔隙连通性、曲率等沉积物孔隙结构参数.结果表明,巢湖表层沉积物孔隙度变化范围为0.28~0.75;曲率在2.83~9.31内变化,且在不同方向上表现出明显的差异性,Z方向上的较高曲率阻碍了孔隙水中的污染物扩散.沉积柱在垂直方向上,总体上随深度的增加,孔隙度减小,但在某些深度存在异常,可能是因为底栖动物活动或沉积条件变化. 相似文献
535.
EPA PMF5.0在浦东新区降水源解析中的使用研究 总被引:1,自引:0,他引:1
使用EPA PMF5.0模型,以浦东新区降水源解析为例,按照使用前监测数据和不确定度数据收集、模型运行前数据判读、基本模型运行前最佳因子数确定以及模型旋转前后因子贡献比变化,对降水中多种阳离子和阴离子分别进行讨论,在离子贡献汇总中得到其主要贡献的阴阳离子。 EPA PMF5.0方法的使用,为大气降水在污染源治理和管理等领域提供了新的研究思路,同时也对基层监测站开展源解析具有参考作用。 相似文献
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To evaluate the natural history and outcome of cases of fetal ovarian cyst under conservative prenatal treatment. A retrospective cohort study included patients diagnosed with fetal ovarian cysts was conducted between January 2008 to December 2016. Data including clinical data, sonographic feature and postnatal outcomes were obtained. One hundred and two cases were included for statistical analysis. The rate of spontaneous resolution was significantly higher among cases with simple than complex cysts (70/92 or 76.1% vs 2/10 or 20%, P < .01) and for cysts <4 cm than cysts ≥4 cm (50/56 or 89.3% vs 22/46 or 47.8%, P < .01). Ovarian torsion was confirmed in 5/102 (4.9%) cases; neither prenatal characteristics of cysts (complex: 2/10 or 20% vs simple: 3/92 or 3.3%, P = .07), nor their size ( ≥ 40 mm: 4/46 or 8.7% vs < 40 mm: 1/56 or 1.8%, P = .17) was predictive for ovarian torsion. 25/102 (24.5%) of cysts change in size or sonographic characteristics prenatally. Half of the complex cysts at the last prenatal scan are not ovarian in origin. 98/102 neonates (96.1%) were able to preserve both ovaries. Spontaneous resolution of ovarian cysts is predicted by cyst size and characteristics, whereas likelihood of torsion cannot be predicted. 相似文献
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