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811.
依据2013年6、8、10、11月对莱州湾4个航次的调查资料,分析了该海域不同季节溶解无机氮(DIN)、活性磷酸盐(PO4-P)平面分布及季节变化特征。结果表明,2013年莱州湾DIN和PO4-P均呈现出较明显的季节差异。其中,夏季受陆源输入显著影响,DIN和PO4-P浓度最高,50%的站位DIN含量超四类海水水质标准;其次为秋季,45%的站位DIN含量超四类海水水质标准,而春季最低,31.25%的站位DIN含量超四类海水水质标准。4个月份PO4-P含量均满足一类海水水质标准。N/P比值总体处于较高水平,表明整个莱州湾海域处于磷限制潜在性富营养(ⅥP)水平。 相似文献
812.
为了解石油烃污染对水生生物生长、繁殖和发育的影响,采用实验生态学方法研究了润滑油对蒙古裸腹溞Moina mongolica的急性毒性和慢性毒性。结果表明:润滑油对蒙古裸腹溞的24 h LC50、48 h LC50、72 h LC50和96 h LC50分别为7.98 mg/L、5.81 mg/L、4.99 mg/L和3.04 mg/L,安全浓度为0.92 mg/L。润滑油浓度18 mg/L时,蒙古裸腹溞的存活时间最短、存活率最低,但在其他试验浓度下没有明显的变化规律,其种群增长参数也没有体现出明显的变化规律,说明润滑油对蒙古裸腹溞毒性相对较弱。 相似文献
813.
选择典型燃煤锅炉对其汞释放规律、形态分布特征进行了试验,并基于煤、石灰石、粗渣、细灰和烟气中的汞含量,给出了系统的汞平衡结果为104%~124%,可满足锅炉汞平衡要求。采用燃煤电厂汞形态浓度取样测试Ontario Hydro标准方法,给出了烟气中氧化汞、单质汞(Hg~0)的分布。结果表明:所测燃煤烟气汞浓度介于0.46~2.40μg/m~3之间,单质汞(Hg~0)占80%~90%。现有静电除尘器和脱硫设施对汞的排放有控制作用,使烟气总汞排放降低了90.3%~98.7%。 相似文献
814.
为了宏观量化民航客机起飞阶段的风险水平,提升飞机起飞的安全性,基于不确定性信息的模糊性和随机性,建立了基于二维云的蒙特卡洛仿真模型,有效增加飞机起飞阶段风险数据的样本量,通过与标准云的比较确定民航机队起飞阶段的风险特征.采集某航空公司B737-800机队351套QAR数据作为样本,通过对飞机起飞关键操作的分析,选取离地速度、抬头速率、离地仰角3个起飞关键参数作为风险评估指标,运用MATLAB编程处理QAR数据并对模型进行验证,得到3个机队起飞阶段的风险均值.通过风险收敛性分析得出二大队的起飞风险最高,这是因为在起飞阶段二大队的关键操作风险偏高.该方法可应用于航空公司对不同机队起飞阶段风险的动态管理.该仿真模型的样本数据分布更加稳定,解决了风险的随机性和模糊性,有利于航空公司实现飞机运行风险可视化,对飞行员关键操作的针对性训练具有一定的指导意义. 相似文献
815.
An indoor chamber facility is described for investigation of atmospheric aerosol chemistry. Two sets of α-pinene ozonolysis experiments were conducted in the presence of dry ammonium sulfate seed particle: ozone limited experiments and α-pinene limited experiments. The concentration of gas phase and particle phase species was monitored continuously by on-line instruments and recorded automatically by data sampling system. The evolution of size distribution was measured by a scanning mobility particle sizer ... 相似文献
816.
为探究渤海北部海上油气区及周边近岸海域典型芳香烃类化合物污染状况,2015年5月现场采集了32个站位的海水样品,针对7种苯系物(BTEX)和17种多环芳烃(PAHs)进行测定,并采用商值法和毒性当量法对污染物开展单一和联合生态风险评估。结果显示,研究海域海水中7种苯系物总含量范围为65.1~222.6 ng·L~(-1),以甲苯含量最高,表层含量略低于底层,油气区平均含量低于周边近岸,受到陆源污染输入的影响特征明显。表层海水中ΣPAHs含量范围为98.9~356.0 ng·L~(-1),平均值为184.5 ng·L~(-1),以低环芳烃占优势,总体处于中等水平,比值法判定该海域PAHs可能主要来源于石油及其加工产品。该海域海水中苯并(a)芘的风险商RQ值大于0.1,表现出低度风险,其余3种处于可接受水平。4种芳香烃类化合物联合生态风险等级为低度风险,对生态系统具有潜在的不利影响,但不同区域仍存在一定差异性,海上石油开采与陆源输入是影响该海域个别区域生态风险较高的重要因素。 相似文献
817.
818.
Relationship between the extractable metals from soils and metals taken up by maize roots and shoots 总被引:11,自引:0,他引:11
Two extraction procedures, i.e. a single extraction procedure using low-molecular-weight-organic-acids (LMWOAs) as extractant and a sequential extraction procedure recommended by the European Community Bureau of Reference (BCR), were performed to extract metal fractions from wet rhizosphere soil. And the extracted soil solutions were further fractionated as colloidal and truly dissolved fractions. Heavy metals in maize roots were experimentally defined as metals adsorbed on cell wall and metals taken up by cross-membrane by washing with CaCl(2). The correlation coefficients between extractable metals from soil and taken up by maize roots and shoots were compared between two extraction methods, and a good correlation was obtained if LMWOAs were used. In contrast, the correlation coefficients were poor when the BCR method was used. 相似文献
819.
Refinery effluent-derived humic substances (HS) are important for developing refinery effluent reclamation techniques and studying the environmental chemistry of wastewater effluents. In this study, dissolved organic matter (DOM) from refinery effluent was concentrated using a portable reverse osmosis (RO) system. HS were isolated from RO retentates with XAD-8 resin. A variety of approaches such as specific UV absorbance at 254nm (SUV(254)), elemental analysis, size exclusion chromatography (SEC), solid-state cross polarization magic angle spinning (13)C nuclear magnetic resonance spectrometry ((13)C CPMAS NMR), Fourier transform infrared spectrometry (FTIR), and electrospray ionization/ion trap/mass spectrometry (ESI/ion trap/MS) were employed for characterization of HS. The portable RO system exhibited high yield and recovery of DOM for concentrating refinery effluent. The concentration of dissolved organic carbon (DOC) in the refinery effluent was 9.9mg/l, in which humic acids (HA) and fulvic acids (FA) accounted for 2.3% and 34.6%, respectively. Elemental and SUV(254) analyses indicated relative high amounts of aliphatic structures and low amounts of aromatic structures in refinery effluent-derived HS. Refinery effluent-derived HS displayed lower molecular weight than natural HS. The number-average molecular weight (M(n)) and the weight-average molecular weight (M(w)) of HA were 1069 and 2934, and those of FA were 679 and 1212 by SEC, respectively. By ESI/ion trap/MS, the M(n) and the M(w) of FA were 330 and 383. Four kinds of carbon structures (aliphatic, aromatic, heteroaliphatic, and carboxylic carbons) were found in refinery effluent-derived HS by (13)C NMR analysis. The quantitative results support the interpretation that these HS are rich in aliphatic carbons and poor in aromatic carbons. Proteinaceous materials were identified by FTIR analysis in refinery effluent-derived HS. 相似文献
820.
Uptake and distribution of rare earth elements in rice seeds cultured in fertilizer solution of rare earth elements 总被引:4,自引:0,他引:4
The uptake behavior of rare earth elements (REEs) under pot conditions using deionized water and a REE fertilizer solution as the culture media as well as the distribution of REEs in rice proteins were studied. The uptake of REEs in rice seeds increased dramatically after a lag period of approximately three days. Roots can accumulate a much higher content of REEs than germs and the resting seeds. The REE content in each water-soluble (albumin) and salt-soluble (globulin) component of the rice seeds accounted for 5-8% and 4-6% of the total REEs, respectively. However, there are less than 1.5% of the total REEs were found in the alcohol-soluble (prolamin) and acetic acid-soluble (glutelin) components. The high performance liquid chromatography (HPLC) in the gel permeation and the reserved-phase were used to monitor changes in the molecular weight distribution changes of the soluble proteins of rice seeds during germination after having been cultured in the same solution for seven days. No changes occurred in the prolamin, while a slight change occurred in the albumin, globulin and glutelin. Fractionation of the albumin of rice seeds cultured in a REE fertilizer solution on the Sephadex G-100 column indicated that REEs, especially Ce, La, Pr and Nd, were associated mainly with biological compounds of a molecular weight between 10,000 and 12,000. 相似文献