直接进样-高效液相色谱-串联质谱分析水中微囊藻毒素

建立了直接进样-高效液相色谱-串联四极杆质谱分析环境水样中微囊藻毒素-LR的分析方法。方法使用C18反相柱为分离柱,柱温40℃,流速0.7 mL/min,乙腈和甲酸水溶液(0.1%)作流动相,采用梯度洗脱,保留时间4.13 min。串联质谱采用多反应监测模式,使用ESI(+)源电离水样。在上述条件下,水样过粒径为0.45μm的滤头后可直接进样,进样体积25μL时检出限可达0.04μg/L,在0.10~200μg/L范围内线性良好(R=0.999 8);样品加标回收率为96.6%~106%,相对标准偏差为1.3%~5.6%。同时方法应用到实际环境水样分析中也具有令人满意的结果。该方法灵敏度高,快速简单,适用于环境水样中MC-LR的分析。     

Elemental Analysis of Water and Sediments by External Beam Pixe Part 3: Axios (Vardar) River, Greece

The Axios (Vardar) River originates from the south west part of Yugoslavia, transverses Greece, and discharges into the Thermaikos bay in the north Aegean Sea.

The proton induced X-ray emission (PIXE) method with external beam was used for the elemental analysis of water and sediment samples, while measurements of water temperature, dissolved oxygen content, conductivity, pH, and the water flow were made in situ. Water samples were also analysed for total phosphates, nitrates, chlorophyll, and BOD. The data collected for a 16-month period indicate that the Axios River is polluted as far as the metal content is concerned; its primary productivity is low and it is slightly enriched during its course into the Greek territory.     

南水北调西线工程对解决受水区生态环境问题的意义

南水北调西线工程是一项跨流域的大型调水工程，对解决我国西北、华北部分地区严重干旱缺水，促进黄河上中游地区的资源开发和经济持续快速发展，及其生态环境的改善具有重大意义。本文着重分析了调水工程对受水区生态环境的有利影响，指出调水工程将增加受水区的河川径流量，改善水环境；提高植被覆盖率，遏制并治理水土流失和土地沙漠化；减少自然灾害，改善农业生态环境和当地居民的生存环境。     

Modelling the response of tree growth to temperature and CO2 elevation as related to the fertility and current temperature sum of a site

A methodology for simulating climate change impacts on tree growth was introduced into a statistical growth and yield model in relation to variations in site fertility and location implemented with current temperature sum. This was based on a procedure in which the relative enhancement in stem volume growth was calculated from short-term runs of a physiological simulation model for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth.) stands. These simulations were made for a set of stands with species-specific variations in stand characteristics, location and fertility type first in current climatic conditions and then in different combinations of CO₂ and temperature elevations. Based on these simulations, the relative enhancement of volume growth induced by the climate change (relative scenario effect, RSEv) was calculated and modelled in relation to: (i) CO₂ and temperature elevation, stand density and the competition status of the tree in its stand, and (ii) variations in site fertility type and current temperature sum of a stand. Finally, these transfer functions for RSEv were applied to adapt the stem volume growth in the statistical growth and yield model to reflect the response to climate change.     

Eco-environmental benefit assessment of China''''s South-North Water Transfer Scheme——the middle route project

IntroductionInordertoalleviateseverewatershortagesinnorthChina ,ChinesecentralgovernmenthavestartedtoimplementtheSouth NorthWaterTransferScheme(SNWT) ,whichwilltransferwaterfromYangtzeRiverbasininthesouthtoHuang Huai Hai(YellowRiver ,HuaiheRiverandHaiheRi…     

Dynamic temperature model for proton exchange membrane fuel cell using online variations in load current and ambient temperature

This paper presents a dynamic temperature model for a proton exchange membrane fuel cell (PEMFC) system. The proposed model overcomes the complexity of conventional models using first-order expressions consisting of load current and ambient temperature. The proposed model also incorporates a PEMFC cooling system, which depends upon the temperature difference between events. A dynamic algorithm is developed to detect load changing events and calculate instantaneous PEMFC temperature variations. The parameters of the model are extracted by employing the lightning search algorithm (LSA). The temperature characteristics of the NEXA 1.2 kW PEMFC system are experimentally studied to validate model performance. The results show that the proposed model output and the temperature data obtained from experiments for linear and abrupt changes in PEMFC load current are in agreement. The root-mean-square error between the model output and experimental results is less than 0.9. Moreover, the proposed model outperforms the conventional models and provides advantages such as simplicity and adaptability for low and high sampling data rates of input variables, namely, load current and ambient temperature. The model is not only helpful for simulations but also suitable for dynamic real-time controllers and emulators.     

Determination of Cd,Cr, Cu,Pb and Zn from various water samples with use of FAAS techniques after the solid phase extraction on rice bran

A facile and novel method has been developed for the determination of cadmium, chromium, copper, lead, and zinc from various water samples using FAAS. In the present investigation, a syringe was loaded with sorbent (rice bran) for the separation and enrichment of cadmium, chromium, copper, lead, and zinc, prior to their analysis by flame atomic absorption spectrometry which was described to substitute the batch and column techniques. The syringe was loaded with 2.0 g of sorbent in order to retain the analyte elements. Six milliliter of sample solution (pH 8.0 ± 0.2) was drawn into the syringe in 15 s and discharged over a period of 15 s. Then, 2.0 M HCl eluent was drawn into the syringe and ejected back to desorb the analyte elements. At the optimum conditions, the percentage recoveries of Cd, Cr, Cu, Pb, and Zn was in the range of 95.5–99.4% with SD of 0.10%. The elements could be concentrated by drawing and discharging several portions of sample successively. The detailed study of various interferences made the confirmation of the method highly selective. The risk of contamination is less than that with the column technique. The method was successfully applied for the determination of Cd, Cr, Cu, Pb, and Zn in spiked and natural water samples. The results obtained are in good agreement with the reported methods at the 95% confidence level.     

Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos

The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography–Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.     

GC × GC--A New Analytical Tool For Environmental Forensics

Comprehensive two-dimensional gas chromatography, GC 2 GC, is a new analytical tool with a tremendous capability to separate and identify organic compounds in complex environmental samples. GC 2 GC uses two different chromatography columns coupled serially by a modulator to produce a volatility by polarity separation and distribute compound peaks across a two-dimensional retention time plane. The two-dimensional separation produces an order of magnitude more resolved peaks than traditional GC methods. The grouping or ordering of the peaks in the GC 2 GC chromatogram facilitates the identification of unknown compounds and the comparison of complex environmental samples. When a mass spectrometer detector is used, each resolved GC 2 GC peak yields a single-component, interference-free mass spectrum that leads to accurate matching with mass spectral libraries. GC 2 GC examination of marine sediment extracts identified a wide variety of chemical contaminants including polychlorinated biphenyls, p -nonylphenol isomers, polycyclic aromatic hydrocarbons, benzotriazoles, and the alkane, cycloalkane, alkylbenzene, alkylnaphthalene, and biomarker fractions of petroleum. The two-dimensional GC 2 GC chromatogram image permits rapid screening of the sediment extracts for these and other unknown contaminants.     

The derivation of radionuclide transfer parameters for and dose-rates to an adult ringed seal (Phoca hispida) in an Arctic environment

Radionuclide transfer parameters and dose-rates for an adult ringed seal from Svalbard have been determined based on empirical and estimated tissue activity concentrations and detailed dietary and habitat information. Whole-body equivalent concentration factors determined for anthropogenic radionuclides ranged from 10(1) ((90)Sr) to 10(2) ((137)Cs, (238)Pu and (239,240)Pu), while natural radionuclides ranged from 10(2) ((210)Pb) to 10(4) ((210)Po). Employing a dietary composition of 40% fish, 40% zooplankton and 20% benthic invertebrates, a whole-body biological half-life of 29 days was derived for (137)Cs. A total dose-rate of approximately 0.19microGyh(-1) (1.7mGya(-1)) was derived for an adult ringed seal; this dose-rate is virtually entirely attributable to the internal components of (210)Po and (40)K. The dose-rates associated with the presence of anthropogenically derived radionuclides in the present assessment fall many orders of magnitude below the dose-rates at which any biological effects would be expected.