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51.
2006~2010年珠三角地区SO2特征分析 总被引:3,自引:2,他引:1
对广州番禺大气成分站2006~2010年期间的SO2资料进行了分析,讨论了珠江三角洲(珠三角)地区地面SO2体积分数的年、季节、月、日变化特征和概率的分布特征.珠三角地区地面SO2变化特征的分析结果表明,2010年地面SO2体积分数的总体水平相对近年来有一定下降,高浓度事件发生频率降低;冬、春季SO2各项统计值要高于夏、秋季,干季明显高于湿季,可能与大气边界层高度和太阳辐射等因素的季节性变化相关;SO2干湿季的日变化趋势相仿,日最高峰时间相同,只是湿季达次高峰和最低点的时间比干季要提前1 h,这可能与季节性的大气边界层高度和辐射强度变化,以及日照时间长度有关;SO2体积分数的概率分布特征比较复杂,各月谱型分布各有不同,可能与季节性因素的变化规律相关. 相似文献
52.
TiO2/膨润土复合材料对Hg2+的吸附性能研究 总被引:1,自引:1,他引:0
利用纳米TiO_2对膨润土进行复合改性,制备TiO_2/膨润土复合材料.采用电镜扫描、X-射线衍射表征改性前后膨润土的结构和形貌.通过室内模拟实验,以膨润土为对照,研究不同添加量、pH、吸附时间及初始Hg~(2+)浓度等条件下,TiO_2/膨润土复合材料对Hg~(2+)的吸附特性与性能,同时通过正交试验,探究TiO_2/膨润土复合材料吸附Hg~(2+)的最优条件.结果表明,改性后的膨润土颗粒明显变小,且颗粒疏松多空孔,层间距增大.相比于膨润土,TiO_2/膨润土复合材料吸附性能得到极大提高.TiO_2/膨润土复合材料对Hg~(2+)的吸附率均随着添加量、pH、吸附时间的增大而增大,添加量为1.5 g·L~(-1)、pH为7.0、吸附时间为120 min时,吸附率达98.0%以上.但TiO_2/膨润土复合材料对Hg~(2+)的吸附率随着初始Hg~(2+)浓度的增大而减小.通过4种动力学模型拟合发现,吸附过程符合假二级动力学方程,吸附以化学吸附为主.吸附等温线更符合Langmuir等温方程,属于典型的单分子层吸附,最大吸附量为20.66 mg·g-1.吸附Hg~(2+)的最优实验条件:添加量为2.0 g·L~(-1),pH为8.0,初始Hg~(2+)浓度为45 mg·L~(-1),吸附时间为16 h,此时吸附率99.9%,平衡浓度为0.034 mg·L~(-1). 相似文献
53.
Zhenyan Zhang Xiaoji Fan W.J.G.M. Peijnenburg Meng Zhang Liwei Sun Yujia Zhai Qi Yu Juan Wu Tao Lu Haifeng Qian 《环境科学学报(英文版)》2021,33(1):1-9
Freshwater cyanobacterial blooms have drawn public attention because they threaten the safety of water resources and human health worldwide. Heavy cyanobacterial blooms outbreak in Lake Taihu in summer annually and vanish in other months. To find out the factors impacting the cyanobacterial blooms, the present study measured the physicochemical parameters of water and investigated the composition of microbial community using the 16S rRNA gene and internal transcribed spacer amplicon sequencing in the months with or without bloom. The most interesting finding is that two major cyanobacteria, Planktothrix and Microcystis, dramatically alternated during a cyanobacterial bloom in 2016, which is less mentioned in previous studies. When the temperature of the water began increasing in July, Planktothrix appeared first and showed as a superior competitor for M. aeruginosa in NO3?-rich conditions. Microcystis became the dominant genus when the water temperature increased further in August. Laboratory experiments confirmed the influence of temperature and the total dissolved nitrogen (TDN) form on the growth of Planktothrix and Microcystis in a co-culture system. Besides, species interactions between cyanobacteria and non-cyanobacterial microorganisms, especially the prokaryotes, also played a key role in the alteration of Planktothrix and Microcystis. The present study exhibited the alteration of two dominant cyanobacteria in the different bloom periods caused by the temperature, TDN forms as well as the species interactions. These results helped the better understanding of cyanobacterial blooms and the factors which contribute to them. 相似文献
54.
基于文献[1]提出的最大往返剪切作用面上的液化应力条件和粉煤灰的动三轴试验数据,运用回归分析方法拟合曲线及相关参数建立了粉煤灰的破坏应力条件,并应用F检验法对参数的回归效果进行了检验,检验结果表明参数的回归效果高度显著。得出的破坏应力条件表明初始剪应力与动剪应力的倒数间并不呈线性关系,而是二次多项式关系,这与张克绪所提出的应力条件存在着差异。因此,可初步认为张克绪的液化应力条件不能直接运用于粉煤灰。 相似文献
55.
In this study, the relationship between inhalable particulate (PM10), fine particulate (PM2.5), coarse particles (PM2.5 – 10) and meteorological parameters such as temperature, relative humidity, solar radiation, wind speed were statistically analyzed and modelled for urban area of Kolkata during winter months of 2003–2004. Ambient air quality was monitored with a sampling frequency of twenty-four hours at three monitoring sites located near traffic intersections and in an industrial area. The monitoring sites were located 3–5 m above ground near highly trafficked and congested areas. The 24 h average PM10 and PM2.5 samples were collected using Thermo-Andersen high volume samplers and exposed filter papers were extracted and analysed for benzene soluble organic fraction. The ratios between PM2.5 and PM10 were found to be in the range of 0.6 to 0.92 and the highest ratio was found in the most polluted urban site. Statistical analysis has shown a strong positive correlation between PM10 and PM2.5 and inverse correlation was observed between particulate matter (PM10 and PM2.5) and wind speed. Statistical analysis of air quality data shows that PM10 and PM2.5 are showing poor correlation with temperature, relative humidity and solar radiation. Regression equations for PM10 and PM2.5 and meteorological parameters were developed. The organic fraction of particulate matter soluble in benzene is an indication of poly aromatic hydrocarbon (PAH) concentration present in particulate matter. The relationship between the benzene soluble organic fraction (BSOF) of inhalable particulate (PM10) and fine particulate (PM2.5) were analysed for urban area of Kolkata. Significant positive correlation was observed between benzene soluble organic fraction of PM10 (BSM10) and benzene soluble organic fraction of PM2.5 (BSM2.5). Regression equations for BSM10 and BSM2.5 were developed. 相似文献
56.
This is the first comprehensive study of sources of variation in metal concentrations within the whole tissues of a shallow burrowing, filter-feeding intertidal clam, Austrovenus stutchburyi. Samples were collected from 12 sites in April, August, November and February in 1993–1994 in the vicinity of Otago Harbour and Peninsula, New Zealand. Total tissue trace metal concentrations (μg g−1 dry weight) were measured in individual animals for the essential metals : Mn, Cu, Zn, Ni and the non-essential Cr using trace-metal clean acid-digestion and ICP-OAES techniques. Average metal concentrations were 3–60 μg g−1 for Cu, 40–118 μg g−1 for Zn, 2–12 μg g−1 for Mn, 5–35 μg g−1 for Ni and 1–44 μg g−1 for Cr. These levels decreased with body weight and differed amongst sites except for Cr in February (mid-summer). Highest concentrations occurred at sites close to a city (Dunedin) and within the central harbour region although the Cu, Zn, Ni and Cr concentrations did not correlate with the environmental gradient or season. At one coastal site, samples of both the blue mussel Mytilus galloprovincialis and cockles gave similar trends in trace metal levels. These results suggest that the cockle could be a useful trace metal biomonitor within NZ estuaries. 相似文献
57.
Stromberg JC Lite SJ Rychener TJ Levick LR Dixon MD Watts JM 《Environmental monitoring and assessment》2006,115(1-3):145-173
A portion of Arizona’s San Pedro River is managed as a National Riparian Conservation Area but is potentially affected by ground-water withdrawals beyond the conservation area borders. We applied an assessment model to the Conservation Area as a basis for monitoring long-term changes in riparian ecosystem condition resulting from changes in river water availability, and collected multi-year data on a subset of the most sensitive bioindicators. The assessment model is based on nine vegetation bioindicators that are sensitive to changes in surface water or ground water. Site index scores allow for placement into one of three condition classes, each reflecting particular ranges for site hydrology and vegetation structure. We collected the bioindicator data at 26 sites distributed among 14 reaches that had similar stream flow hydrology (spatial flow intermittency) and geomorphology (channel sinuosity, flood-plain width). Overall, 39% of the riparian corridor fell within condition class 3 (the wettest condition), 55% in condition class 2, and 6% in the driest condition class. Condition class 3 reaches have high cover of herbaceous wetland plants (e.g., Juncus and Schoenoplectus spp.) along the perennial stream channel and dense, multi-aged Populus-Salix woodlands in the flood plain, sustained by shallow ground water in the stream alluvium. In condition class 2, intermittent stream flows result in low cover of streamside wetland herbs, but Populus-Salix remain abundant in the flood plain. Perennial wetland plants are absent from condition class 1, reflecting highly intermittent stream flows; the flood plain is vegetated by Tamarixa small tree that tolerates the deep and fluctuating ground water levels that typify this reach type. Abundance of herbaceous wetland plants and growth rate of Salix gooddingii varied between years with different stream flow rates, indicating utility of these measures for tracking short-term responses to hydrologic change. Repeat measurement of all bioindicators will indicate long-term trends in hydro-vegetational condition. 相似文献
58.
Monitoring of ambient PM10 (particulate matter which passes through a size selective impactor inlet with a 50% efficiency cut-off at 10 μm aerodynamic diameter) has been done at residential (Kasba) and industrial (Cossipore) sites of an urban region of Kolkata during November 2003 to November 2004. These sites were selected depending on the dominant anthropogenic activities. Metal constituents of atmospheric PM10 deposited on glass fibre filter paper were estimated using Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Chromium (Cr), zinc (Zn), lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn) and iron (Fe) are the seven toxic trace metals quantified from the measured PM10 concentrations. The 24 h average concentrations of Cr, Zn, Pb, Cd, Ni, Mn and Fe from ninety PM10 particulate samples of Kolkata were found to be 6.9, 506.1, 79.1, 3.3, 7.4, 2.4 and 103.6 ng/m3, respectively. The 24 h average PM10 concentration exceeded national ambient air quality standard (NAAQS) as specified by central pollution control board, India at both residential (Kasba) and industrial (Cossipore) areas with mean concentration of 140.1 and 196.6 μg/m3, respectively. A simultaneous meteorology study was performed to assess the influence of air masses by wind speed, wind direction, rainfall, relative humidity and temperature. The measured toxic trace metals generally showed inverse relationship with wind speed, relative humidity and temperature. Factor analysis, a receptor modeling technique has been used for identification of the possible sources contributing to the PM10. Varimax rotated factor analysis identified four possible sources of measured trace metals comprising solid waste dumping, vehicular traffic with the influence of road dust, road dust and soil dust at residential site (Kasba), while vehicular traffic with the influence of soil dust, road dust, galvanizing and electroplating industry, and tanning industry at industrial site (Cossipore). 相似文献
59.
生物表面活性剂产生菌犁头霉菌(Absidia orchidis)的筛选及发酵条件优化 总被引:6,自引:0,他引:6
采用植物油为唯一碳源,设计选择培养基,从饭店下水道污泥中筛选出生物表面活性剂产生菌.结果分离到12株菌,其中一株能使发酵液的表面张力值从68 mN·m-1降低到34.5 mN·m-1,具有开发潜力,被选出作进一步的研究.该菌株经鉴定为犁头霉菌(Absidia orchidis).通过正交试验对犁头霉菌的培养条件进行优化,其优化培养条件为:植物油3.6 g·L-1,KH2PO412.1 g·L-1,Na2HPO45 g·L-1,(NH4)2SO4 1 g·L-1,NaNO32 g·L-1,酵母浸膏0.1 g·L-1,MgSO4·7H2O 0.15 g·L-1,NaCl 5 g·L-1,CaCl2 0.1 g·L-1,EDTA 1 g·L-1,KI 0.83μg·L-1,H3PO4 0.01μg·L-1,CoCl2·6H2O 0.048μg·L-1,MnSO4·H2O 0.312μg·L-1,Na2 MoO4·2H2O 0.048μg·L-1,ZnCl2 0.287μg·L-1,CuSO4·5H2O 0.125μg·L-1,初始pH值8,接种量6%.发酵70h时可获得生物表面活性剂的最大收获量,此时发酵液中生物表面活性剂的相对浓度达402倍. 相似文献
60.