三维荧光技术在水环境监测中的应用研究进展

介绍了三维荧光技术的测定原理、测定结果的表征方法和数据解析方法（峰值拾取法、荧光区域积分法和平行因子分析法）。讨论了三维荧光典型荧光峰与BOD₅、COD和TOC等水质指标的相关性,证明了三维荧光技术在水环境监测中的应用能力。综述了三维荧光技术在生活污水、工业废水和雨水等水环境监测中应用的研究进展,展望了其发展前景。     

关于冷原子荧光测汞法灵敏度和稳定性影响因素的探讨

本文从六个方面对影响冷原子荧光测汞灵敏度和稳定性的因素进行了探讨,同时提出了相应的改进措施,以便更好地应用冷原子荧光测汞法。     

Can machines recognise stress in plants?

In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry.     

In situ Measurement of Daphnia longispina Grazing on Algae and Bacteria in a High Mountain Lake (Lake Paione Superiore,Northern Italy) using Fluorescently Labeled Cells

Grazing impact of Daphnia longispina on phytoplankton and bacteria in Lake Paione Superiore (Northern Italy) was evaluated using fluorescently labeled cells in short-term in situ experiments. Structure and size distribution of Daphnia were studied weekly from its appearance in July to its decline in September. Relative importance of algae and bacteria in the diet varied over time, as did consequently the relative impact of Daphnia on the phytoplankton and bacteria populations. Biomass of bacteria in the diet of Daphnia varied from 1 to 42%, and was highest at the beginning of population development when young individuals dominated. The percent biomass of algae in the diet increased with population development, ranging from 58 to 99%. Daphnia population consumed per hour 0.04–1.8% of bacteria and 0.3–17.6% of phytoplankton abundances.     

Growth and photosynthesis responses of Phaeodactylum tricornutum to dissolved organic matter from salt marsh plant and sediment

The effects of allochthonous dissolved organic matter (DOM) on the growth and photosynthesis of Phaeodactylum tricornutum were investigated. P. tricornutum incubated in f/2 medium was exposed to DOM additives, which were extracted from the plant and sediment samples of a salt marsh in North Branch of the Yangtze estuary, China. During 12 days incubation, the chlorophyll fluorescence parameters of P. tricornutum were measured by a Phyto-PAM phytoplankton analyzer. Spectral properties of DOM in algae filtrates were also observed. The concentrations of chlorophyll a, active chlorophyll a, and the maximum quantum yield of photosystem II significantly decreased after four days of incubation, suggesting that the growth and photosynthetic e ciency of P. tricornutum were inhibited. After adding sediment-DOM extract, both a250/a365 (the ratio of the absorption coe cients at 250 and 365 nm) and S values (spectral slope coe cients) of algae filtrates declined in the first two days, which demonstrated a loss of low molecular weight DOM. Parallel factor analysis of fluorescence spectra of DOM in algae filtrates revealed that DOM could be classified into two humic-like and two protein-like components. The fluorescence intensity of tyrosine-like component originating from algae increased significantly during incubation. This study supports the hypothesis that allochthonous DOM derived from salt marsh plant and sediment have a strong influence on the adjacent aquatic ecosystems.     

Seasonal variability in CDOM absorption and fluorescence properties in the Barataria Basin, Louisiana, USA

Absorption and fluorescence properties of chromophoric dissolved organic matter(CDOM) along a 124 km transect in the Barataria Basin,a large estuary located in Louisiana,USA,were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from(3.25 ± 0.56) to(20.76 ± 2.43) m-1 for the three month high flow period whereas it varied from(1.48 ± 1.08) to(25.45 ± 7.03) m-1 for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runofl in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak,lowest the T-peak,and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.     

四种金属离子对CHBr_3和小牛胸腺DNA间结合作用的影响

采用紫外光谱和荧光光谱法研究了CHBr3与离体小牛胸腺DNA(ctDNA)间的相互作用,以及Cu2+、Co2+、Cd2+、Mg2+4种金属离子单独或共存时对CHBr3与ctDNA结合的影响.结果表明:4种金属离子与CHBr3、ctDNA均能发生基态络合反应,络合物的生成导致体系的紫外吸收峰强度和形状改变,使ctDNA-溴化乙锭体系的荧光发生了不同程度的猝灭;向CHBr3-ctDNA-溴化乙锭体系中分别或同时加入4种金属离子后,Cu2+、Co2+、Cd2+可减弱两者之间的结合,减弱顺序为Cu2+Co2+Cd2+,Mg2+可加强两者之间的结合,4种金属离子同时加入后出现不同于4种金属离子单独加入时的中间类型.据此推断,CHBr3可能主要是通过嵌插作用与ctDNA碱基结合,金属离子对CHBr3与ctDNA结合的影响主要取决于金属离子与DNA的碱基和磷酸基团间结合的相对亲和比.     

微波消解-原子荧光法测定茶叶中的微量汞和砷

建立微波消解-原子荧光法测定茶叶中的微量汞和砷的方法,汞浓度在0μg/L-5．0000μg/L范围内与荧光强度呈线性关系,线性方程y=966．1232x,相关系数r=0．9992,汞的检出限为0．026μg/L;砷浓度在0μg/L-10．00μg/L范围内与荧光强度呈线性关系,线性方程为y=62．1511x,相关系数r=0．9993,砷的检出限为0．087μg/L。样品6次测定结果,汞的相对标准偏差为9．66％,加标回收率为96．4％～101．3％;砷的相对标准偏差为1．45％。加标回收率为91．4％～105．1％。环境标准样品测定结果与标准值相吻合。所测样品中汞、砷含量均在国标限值范围之内。该法简便快捷,灵敏度高,测定结果准确可靠。     

淡水藻类对辛基酚的吸附行为研究

选取辛基酚(4-OP)作为目标物,研究了水中2种常见淡水藻(小球藻和鱼腥藻)对辛基酚的吸附.结果表明,2种藻对辛基酚的吸附量都很大,且吸附迅速.小球藻在混合后的5 min内即吸附了4-OP初始浓度(2 mg/L)的20%,鱼腥藻在混合后的5 min内即吸附了4-OP初始浓度(2 mg/L)的46%.吸附在1 h即达到平衡.模型拟合结果表明,辛基酚在藻表面的吸附符合Langmuir吸附等温式.水溶液pH值的变化对吸附的影响很大,降低pH值有利于2种藻对辛基酚的吸附,pH值对小球藻吸附辛基酚的影响比对鱼腥藻大.用荧光光谱法研究了藻与辛基酚的相互作用,结果表明,藻的加入可使辛基酚荧光强度降低,随着藻浓度的升高,藻/辛基酚体系荧光强度不变,荧光光谱向红端移动,根据此结果推测藻/有机污染物体系能更好地利用太阳光中的近紫外光线,从而促进有机污染物光降解.     

Effect of substrate COD/N ratio on performance and microbial community structure of a membrane aerated biofilm reactor

Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the e ect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification e ciency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization (FISH), Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.