The characteristics, distributions and sources of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl-PAHs (A-PAHs) as well as their ecological risk were explored in six mangrove wetlands across the Taiwan Strait, China. A-PAHs fingerprinting information, combined with PAHs diagnostic ratios and a positive matrix factorization model, were used to identify the sources of PAHs in the mangrove wetland surface sediment samples. The results showed that the total concentration of the 36 PAHs in the sediment samples varied from 186.2 to 2469.2 ngg(-1). Furthermore, the total concentration of PAHs would be underestimated about 37.1%-80.6% when only the concentrations of 16 priority PAHs were examined in the sediment samples. Coal combustion (32.7%) and petroleum combustion (24.6%) were identified as important contributing sources in the Yunxiao, Fugong, and Quanzhou mangrove wetlands, whereas the main source was mainly petroleum combustion (49.1%) in the Guandu, Zhuwei and Waziwei mangrove wetlands. In addition, the guidelines for assessing the ecological risk of individual A-PAHs need to be developed due to lack of criteria for most individual A-PAHs. (C) 2020 Elsevier Ltd. All rights reserved.

在股票市场中人是重要的参与者,人的行为将影响市场发展.本文从广义虚拟经济这一视角出发,着重关注投资者情绪变化对股市产生的影响.本文的实证研究表明,投资者情绪与股市泡沫互为格兰杰因果关系,投资者情绪在短期内对股市泡沫产生正向影响,投资者情绪的变动对股市泡沫产生的影响相对稳定.因此在广义虚拟经济时代,为促进股市平稳健康发展,需要稳定投资者情绪以及完善有关政策措施.

本文研究发现发行价格受到管制的公司会出于利益防御的动机强化IPO阶段的盈余管理,而且盈余管理的程度随着期望市盈率、大股东持股比例以及外部融资需求的提高而上升.从区别产权性质来看,上述关系仅存在于民营企业样本中,而在国有企业样本中并不明显.进一步研究发现,发行价格受限制的公司通过聘请声誉较低的承销商和会计师事务所为其盈余管理创造条件.本文的研究结论对于目前我国正在酝酿中的IPO注册制改革具有重要的启示.

出口贸易历来得到中国政府的支持与鼓励,而出口导向型企业的社会责任却未受到应有的关注.利用A股上市公司2010～2013年的数据,研究出口导向与企业社会责任的关系及其内在机制.实证结果表明:(1)出口导向负向影响企业社会责任绩效;(2)企业可见度在两者的关系中起部分中介作用;(3)企业所有制性质对出口导向与企业社会责任绩效的关系起调节作用.同时,企业社会责任对出口导向与企业财务绩效的关系起调节作用.

企业社会责任与企业财务绩效的关系备受关注却尚无定论.利益相关者与企业之间存在的信息不对称问题会影响两者的关系,并且企业可见度有助于降低利益相关者与企业之间的信息不对称.利用2010-2012年间沪深A股上市公司的数据,可分别采用水平模型和增量模型进行实证分析.分析结果表明:控制其他潜在的影响因素后,企业社会责任正向影响企业财务绩效;企业可见度越高,企业社会责任与财务绩效的关系越强;终端消费品行业的企业社会责任对财务绩效的影响更强.

将发光细菌毒性测试方法应用于典型多环芳烃生物降解过程的毒性评价,研究了菲和芘单独及混合状态下生物降解过程中的毒性变化.结果表明:溶解态的菲和芘在一定浓度范围内对发光细菌均具有毒性,菲和芘对发光细菌的10 min-EC50值分别为1.61×10-5 mol·L-1和231×10-6mol·L-1.单组分和混合组分的菲和芘经过微生物降解后,其毒性显著降低.混合组分生物降解体系中由于菲和芘分子之间的互相作用,使其对发光细菌的毒性效应与其单独存在时有差异.生物降解的各阶段,混合组分降解体系的毒性均大于单组分菲或芘降解体系的毒性,且在降解完全的后期,培养液的毒性有增加的趋势.这与菲和芘降解中间产物的积累变化有关.

利用激光诱导纳秒时间分辨荧光(Laser-induced nanosecond time-resolved fluorescence,LITRF)系统,建立了现场原位检测水体中的荧光溶解态有机物(Fluorescence Dissolved Organic Matter,FDOM)的方法,并将其用于近岸水域(九龙江)水样中FDOM的现场原位检测.通过与传统实验室荧光法检测结果比较,表明使用该系统可实现FDOM中类腐殖质和类蛋白质的同时现场原位检测.

Chinese firms are faced with a practical question: how to balance the conflict of interests between economic goals and social objectives to achieve a unification of the two goals.Through a multiple case study on four Chinese listed companies of household electric appliance with the method of content analysis,the research finds that business model is a key to moderating the conflict between corporate social responsibility and firm performance.A firm with a shared business model could make corporate social responsibility activities contribute to its performance improvement.However,a firm with a non-shared business model,corporate social responsibility may conflict with its performance.

To further achieve the field detection of PAHs in actual leaf samples, it is important to develop novel methods for in situ determination of polycyclic aromatic hydrocarbons (PAHs) in plant leaves. Normally, phenanthrene (Phe) is adsorbed onto the leaf surfaces of three kinds of mangrove species, named Kandelia obovata (Ko), Bruguiera gymnorhiza (Bg) and Aegiceras corniculatum (Ac). A set of laser-induced nanosecond time-resolved fluorescence (LITRF) system was utilized for the in situ quantitative detection of the absorbed phenanthrene (Phe) Experimental results showed that the linear dynamic ranges for the in situ determination of the Phe adsorbed onto the leaf surfaces of Ko, Bg and Ac were 2–1400 ng/spot, 1–1000 ng/spot and 4–2000 ng/spot, with the detection limits of 0.20, 0.14 and 0.42 ng/spot, respectively. The relative standard deviations were less than 6.0% (n = 9). The experimental recoveries for the Ko, Bg, and Ac were 89.6%–108.1%, 78.2%–92.4% and 93.2%–112.9%, respectively. Satisfactory results were obtained for the in situ determination of the Phe adsorbed onto the surfaces of the lab-exposure mangrove leaf samples contaminated by the Phe. The sensitivity of the established method was much higher than that of the previously established fiber optical fluorimetry, and the linear dynamic range got improved. The LITRF method marked a significant step towards to realizing the field detection of PAHs adsorbed onto the mangrove leaves.

The development and application of laser induced nano-second time-resolved fluorescence(LITRF) system was introduced.Compared with other methods for in situ detecting of PAHs in environment,the corresponding advantages of the LITRF were reviewed.In addition,the applications and prospects of the LITRF to be used for in situ detection of PAHs in environment were described based on the experimental results obtained in the laboratory.

A Turner 10-AU field fluorometer was improved to solve problems of the study on simultaneously determination of dissolved organic matter absorption and fluorescent properties in natural water samples.The sample cell and cell holder of the fluorometer were modified with a mirror to develop a new absorption measurement kit,and attenuator plates and photomultiplier voltage were used to control the intensity of absorption light.The absorption measurements of potassium dichromate and potassium permanganate solution were realized by the improved fluorometer.The Sensitivities of the improved fluorometer were about 1 and 0.5 times higher than that of Cary 100 UV-Vis spectrophotometer,with the RSD were 3.93%、2.12%(n=7),respectively.Satisfactory results were both obtained for the absorption spectra measurement and the fluorescent determination of humic acid in water,detection limit was 0.306mg/L and 0.0104mg/L respectively.It was proved by experimental results that the improved fluorometer was successfully used to determine dissolved organic matter in water with simpler procedure and satisfactory results.

The spectral absorption properties of chromophoric dissolved organic matter (CDOM) and their distributions in two Chinese estuaries, the Yangtze River Estuary and the Jiulong River Estuary, were studied during August 2003 (wet season) and during different seasons between 2003−2005, respectively. The CDOM concentrations (a355) of fresh end members in the Jiulong River Estuary varied seasonally, while its quality remained relatively stable. However, the a355 of the marine end members exhibited less variability. Application of a conservative mixing model indicated that CDOM behaved conservatively in the Yangtze River Estuary. No photobleaching removal was observed at high salinity region of this estuary. Although CDOM showed conservative behavior for many cruises in the Jiulong River Estuary, there was evidence for removal in the low salinity regions during some cruises. Laboratory mixing experiments and a salt addition experiment suggested that particle sorption of CDOM maybe the possible reason for the removal. These results showed that absorption properties of CDOM can be used as a tool to observe the quantitative and qualitative dynamics of DOM during estuarine mixing.

Advance in the analytical methods of marine chemistry in the last decade in China was reviewed including the development of modern analytical methods for nutrients,carbon dioxide in seawater,trace organic materials,chemical tracer and isotopes.Some deficiency in this field was proposed.56 references in the field were cited and some prospects were delivered.

The fluorescent dissolved organic matter (FDOM) is the fluorescent component of marine chromophoric dissolved organic matter (CDOM). It has significant influence on the remote sensing, photochemistry, phytoplankton productivity and the ecosystem structure of the surface ocean. Three kinds of spectrofluorimetries for seawater FDOM were summarized and compared, with specific emphasis on three-dimensional excitation/emission matrix spectra (EEMs). The fluorescent characteristics, distribution, variation, source and transformation of the two main components of FDOM——humic-like and protein-like substances——were systematically discussed. Then, scientific questions were raised for further research, such as photochemical reaction of CDOM and its ecological effects, role of bacteria in production and transformation of CDOM, relationship between CDOM and colloidal organic carbon, and interpretation of EEMs signals.

The distribution characteristics of total phosphorus and the five species of phosphorus in the sediments from the cage mariculture areas of Sandu Bay were investigated. The relationship between the distribution of species of phosphorus and aquaculture were discussed. The results showed that the contents of total phosphorus in the surface sediments ranges from 243.57×10~(-6) to 722.73×10~(-6), and that of inorganic phosphorus from 217.36×10~(-6) to 609.94 ×10~(-6), to be 66.8%--89.2% of total phosphorus. The contents of organic phosphorus from 26.20×10~(-6) to 113.92×10~(-6), to be 10.8%--33.2% of total phosphorus. The higher contents of total phosphorus and five forms of phosphorus appeared to be in the mariculture areas of Pseudosciaena Crocea, which are between Qinshang Island and Doumao Island, south of Sandu island and north coast of Jiaotou-Cheng'ao, while the lower contents appeared to be in the non-mariculture areas. It shows that the distribution of species of phosphorus were significantly effected by the mariculture activities.

A sensitive method for rapid determination of tryptophan contents in zooplankton samples by spectrofluorimetry was proposed.Seven zooplankton samples were collected from the Jiulong River Estuary of Xiamen Harbour at night by plankton net from March 2004 to May 2004.Each single species were picked out under microscope at the laboratory.They were immediately dried to constant weight at 60℃ for 48 h and were grinded into powder before analysis.1 mg of zooplankton sample was placed into the ampoule-bottle for hydrolysis.1 mL of solution of 5.5 mol/L NaOH containing 0.5% soluble starch was added as hydrolytic solution.Hydrolyzate was neutralized with 6mol/L after hydrolysis at 110℃ for 20 h.And then it was adjusted to pH=10.5 with the buffer KH_2PO_4-NaOH.The fluorescence intensity was determined at excitation/emission wavelength 225 nm/350 nm.The linear range of calibration graph was 0~0.07 mg/L.The detection limit was 2.5×10~(-3) mg/L.The recovery rate of sample addition experiments was 99.5%~109.3%.The contents of tryptophan in seven zooplankton samples were 8 750 mg·g~(-1)(Sagitta bedoti),7 070 mg·g~(-1)(Centropages tenuiremis),2 890 mg·g~(-1)(Corophium sinensis),4 960 mg·g~(-1)(Pseudeuphausia sinica),6 770 mg·g~(-1)(postlarva of Acetes japonicus),1 850 mg·g~(1)(zoea of Brachyura) and 5 510 mg·g~(-1)(megalopa of Brachyura),respectively.

This paper set up a procedure of fluorescence method to measure tryptophan in microalgae.NaOH containing 0.5% soluble starch was used as hydrolytic solution.The fluorescence intensity of tryptophan was determined with excitation wavelength 225 nm and emission wavelength 350 nm.The linear range of calibration graph was 0~0.07 mg/L.The detection limit was 0.003 mg/L. The recovery rate of sample was 90%~(100.1%.)

利用荧光光度计对2001-2003年期间九龙江口4个航次水样中有色溶解有机物(CDOM)的荧光光谱进行了测定,并对其荧光性质、荧光强度的分布与季节性变化特征及其河口行为进行了分析,同时与厦门岛周边海域进行了比较.结果表明,输入九龙江口的CDOM荧光强度季节变化明显,夏高(17.16 QSU)冬低(5.73 QSU).所有站位表层荧光强度明显高于底层,与河口区垂直分层一致.南支CDOM荧光强度随盐度的变化率高于北支,说明九龙江河水主要沿河口南岸入海.4个航次CDOM荧光强度都呈保守混合趋势,但观测到CDOM表观荧光效率随盐度增加而降低,暗示在低盐度区可能有胡敏酸的絮凝沉降.厦门周边海域CDOM荧光强度以西海域北部最高,西海域南部和同安湾次之,厦门东侧水道最低.各水域表层CDOM荧光强度与盐度均呈反相关关系,但不同水域回归曲线的斜率有差异,九龙江口、厦门西海域南部及厦门东侧水道三个海域具有同一相关趋势线,表明西海域南部和东侧水道主要受九龙江水输入控制,而西海域北部有不同的趋势线,这主要受污水输入的影响,由此很好地证实了CDOM的水团示踪作用.

A method for direct determination of soluble tryptophan in seawater was primarily established in this paper, and the experiments various on operationconditions of this method were investigated. The calibration curve for the relation between the fluorescent intensity and concentration of tryptophan showed a straight line in the concentration range of 0～0.070mg/dm~3. Under the optimizedconditions, the limit of detection was 7.6×10~(-4)mg/dm~3, the relative standard deviations were lower than 3.1% (n=6), and the recovery retes were 86%～120%. This method can be used directly for the determination of tryptophan in seawater.