Multidimensional fluorescence studies of the phenolic content of dissolved organic carbon in humic substances

Indicators suggest that the amount of dissolved organic carbon (DOC) in natural waters may be increasing. Climate change has been proposed as a potential contributor to the trend, and under such a mechanism, the phenolic content of DOC may also be increasing. This study explores the assessment of the phenolic character of DOC using multidimensional fluorescence spectroscopy as a more convenient alternative to traditional wet chemistry methods. Parallel factor analysis (PARAFAC) is applied to fluorescence excitation emission matrices (EEMs) of humic samples to analyze inherent phenolic content. The PARAFAC results are correlated with phenol concentrations derived from the Folin-Ciocalteau reagent-based method. The reagent-based method reveals that the phenolic content of five International Humic Substance Society (IHSS) samples varies from approximately 5.2 to 22 ppm Tannic Acid Equivalents (TAE). A four-component PARAFAC fit is applied to the EEMs of the IHSS sample dataset and it is determined by PARAFAC score correlations with phenol concentrations from the reagent-based method that components C2, C3, and C4 have the highest probability of containing phenolic groups. The results show the potential for PARAFAC analysis of multidimensional fluorescence data for monitoring the phenolic content of DOC.     

Monitoring of eutrophication by microbial uptake kinetics of dissolved organic matter in waters

The monitoring of eutrophication can be performed by measuring the turnover times of amino acids in watermasses using the Wright-Hobbie uptake kinetics approach.The substrate specificity of amino acids varies greater with turnover times than with sampling location in watermasses with a certain water type. Thus a specific substrate among the essential amino acids should be selected to use for measuring the turnover time, in order to monitor precisely the state of trophic excitation within the steady-state oscillation in a certain aquatic system. On the other hand, either singular or plural substrates among the essential amino acids can be used for measuring the turnover time for the identification of a watermass, relevant to eutrophication.     

The development of a chemical 'fingerprint' to characterise dissolved organic matter in natural waters

A suite of twelve assays has been used to 'fingerprint' dissolved organic matter (DOM). The assays were applied directly to filtered natural water samples. Temperature, pH and conductivity accounted for the environmental conditions on-site. Bulk carbon characteristics were assayed by measuring UV absorbance at 200 and 240 nm, colour in grade Hazen, DOC (dissolved organic carbon), fluorescence (excitation 370 nm, emission 450 nm) and the complexation of phenol itself. Measuring hydroxybenzenes ('monophenolics'), polyhydroxybenzenes ('polyphenolics') and total phenolics with the Gibbs, Prussian Blue and Folin-Ciocalteau assays, respectively, determined the phenolics pool. The methodology was tested on six freshwater sites in North Wales chosen to provide differences in vegetation, land-use and water chemistry and sampled once during each season. A novel approach for the presentation of the data has been developed that combines all range normalised assay results for each site and each season within one polar plot, hence the term 'fingerprint'. The data was also analysed using principal component factor analysis. Assays characterised as determining the chemical properties of DOM contributed to Factor 1 and explained 59% of the variation in the data. Assays apparently determined by the water matrix, contributed to Factor 2 and explained 20% of the variation within the data. The factor scores obtained for each site showed more variation for assays relating to the chemical properties of DOM than to the surrounding water matrix. The methodology was found to detect chemical changes within DOM for each site throughout the year and different responses for different sites.     

Treatment of microbiologically polluted aquaculture waters by a novel photochemical technique of potentially low environmental impact

The applicability of a novel procedure for the disinfection of microbiologically polluted waters from fish-farming ponds, based on the combined action of visible light (including sunlight) and porphyrin-type photosensitising agents, has been investigated using (a) cell cultures of a Gram-positive bacterium (meticillin-resistant Staphylococcus aureus), a Gram-negative bacterium (Escherichia coli) and a fungal pathogen (Saprolegnia spp.); (b) pilot aquaculture plants involving either spontaneously or artificially Saprolegnia-infected rainbow trout (Oncorhynchus mykiss). The results obtained by using two cationic porphyrins, namely a tetra-substituted N-methyl-pyridyl-porphine (C1) and its analogue where one N-methyl group had been replaced by a N-tetradecyl chain (C14), and low intensity visible light irradiation showed an extensive (up to 6-7 log) decrease in the bacterial/fungal population after short incubation and irradiation times in the presence of micromolar photosensitiser concentrations. Moreover, C14 showed some toxic effect also in the absence of light. Extension of these studies to the pilot plants indicated that both C1 + light and C14 can prevent Saprolegnia infections or promote the cure of saprolegniasis in infected trout by treatments with submicromolar porphyrin doses. The procedure appears to be of low cost and to have a low environmental impact.     

Detection of petroleum hydrocarbons at low ppb levels using quartz resonator sensors and instrumentation of a smart environmental monitoring system

Petroleum hydrocarbon vapors at low ppb levels can be detected using a thickness shear mode resonator (TSMR) coated with a chemical-sensing overlayer, prepared by radiofrequency sputtering of porous sintered-polyethylene (PS-PE). The sensing capabilities of PS-PE sensors were profoundly affected by the sputtering methods; they were enhanced by the photo-excitation effect, and were reduced by carbonization and water treatment. The photo-assisted PS-PE sensor was extremely sensitive and could detect linear hydrocarbon (> C12) vapors below the ppb level. The time constant of the sorption curve, however, was large, indicating a slow sensing speed. Toward creating instrumentation for a smart environmental monitoring system, the TSMR sensors were arrayed on a circuit board equipped with a serial interface and signal processing chips of the oscillation drive and frequency counter. Co-sorption with water vapor at a relative humidity of about 10% has almost no effect on the sensing ability of PS-PE sensors for 1,2,4-trimethylbenzene. Conversely, it enhances the sensitivity of the TSMR sensor coated with a D-phenylalanine film. Upward shifts in the baseline are evident with elapsed time. However, a rigorous ten-cycle iteration test for 100 ppm toluene vapor demonstrated good reproducibility of the sensor's signals.     

毛细管柱气相色谱法测定空气中二硫化碳

利用毛细管柱对二硫化碳进行分离,火焰光度检测器(FPD)进行检测,建立了空气中二硫化碳的毛细管柱气相色谱测定法。该方法检出限为0.03 mg/m~3,空白样品加标回收率为91.3%~102.8%,精密度(RSD,n=7)为1.04%~3.91%,变异系数为1.00%~3.93%。实验结果表明,该方法准确可靠、灵敏度好、分析速度快、操作简便,适用于空气中二硫化碳的测定。     

Application of an environmental impact assessment methodology to a site discharging low levels of radioactivity to a freshwater environment in Norway

Significant shifts in opinion regarding environmental protection from ionising radiation have resulted in the development and availability of bespoke approaches for the assessment of impacts on wildlife from radioactive contaminants. The application of such assessment methodologies to actual situations, however, remains relatively limited. This paper describes the implementation of the ERICA Integrated Approach and associated tools within the context of routine discharges of radioactive materials to a freshwater environment. The article follows the implementation through its relevant stages and discusses strengths and weaknesses of the approach in relation to the case study. For current discharge levels, ¹³⁷Cs and ⁶⁰Co constitute the main dose contributors to the majority of reference organisms studied, although ²⁴¹Am and ³H are the main contributors for the phyto- and zooplankton categories. Patterns are observed depending on whether the reference organism is sediment-associated or not. At current discharge levels, none of the reference organisms exceeded or approached the selected screening level, and impacts on biota could be regarded as negligible.     

Application of a compact all solid-state laser system to the in situ detection of atmospheric OH,HO2, NO and IO by laser-induced fluorescence

A tuneable, high pulse-repetition-frequency, solid state Nd:YAG pumped titanium sapphire laser capable of generating radiation for the detection of OH, HO2, NO and IO radicals in the atmosphere by laser induced fluorescence (LIF) has been developed. The integration of the laser system operating at 308 nm into a field measurement apparatus for the simultaneous detection of hydroxyl and hydroperoxy radicals is described, with detection limits of 3.1 x 10(5) molecule cm(-3) (0.012 pptv in the boundary layer) and 2.6 x 10(6) molecule cm(-3) (0.09 pptv) achieved for OH and HO2 respectively (30 s signal integration, 30 s background integration, signal-to-noise ratio = 1). The system has been field tested and offers several advantages over copper vapour laser pumped dye laser systems for the detection of atmospheric OH and HO2 radicals by LIF, with benefits of greater tuning range and ease of use coupled with reduced power consumption, instrument footprint and warm-up time. NO has been detected in the atmosphere at approximately 1 ppbv by single photon LIF using the Alpha 2Sigma+ <-- Chi 2Pi1/2 (0,0) transition at 226 nm, with absolute concentrations in good agreement with simultaneous measurements made using a chemiluminescence analyser. With some improvements in performance, particularly with regard to laser power, the theoretical detection limit for NO is projected to be approximately 2 x 10(6) molecule cm(-3) (0.08 pptv). Whilst operating at 445 nm, the laser system has been used to readily detect the IO radical in the laboratory, and although it is difficult to project the sensitivity in the field, an estimate of the detection limit is < 1 x 10(5) molecule cm(-3) (< 0.004 pptv), well below previously measured atmospheric concentrations of IO.     

Monitoring of the ecotoxicological hazard potential by polar organic micropollutants in sewage treatment plants and surface waters using a mode-of-action based test battery

We propose and evaluate a mode-of-action based test battery of low-complexity and in-vitro bioassays that can be used as a routine monitoring tool for sewage treatment efficiency and water quality assessment. The test battery comprises five bioassays covering five different modes of toxic action. The bioluminescence inhibition test with Vibrio fischeri and a growth rate inhibition test with the green algae Pseudokirchneriella subcapitata are measures of non-specific integrative effects. A second endpoint in the algae test, the specific inhibition of the efficiency of photosynthesis, gives an account of the presence of herbicides. An enzymatic assay covers an important aspect of insecticidal activity, the inhibition of the acetylcholine esterase activity. Estrogenic effects are assessed with the yeast estrogen screen (YES) and genotoxicity with the umuC test. Three field studies, each lasting six to seven consecutive days, were undertaken at a sewage treatment plant (STP) in Switzerland. Samples were collected in summer and late autumn, under dry and rainy conditions. None of the bioassays gave positive results with raw water in whole effluent toxicity testing. Therefore, water samples from various sites during wastewater treatment and from surface water were enriched with solid-phase extraction. The focus was on non-volatile compounds of average to moderate hydrophobicity, a range that includes most pesticides, biocides and pharmaceuticals. Various polar solid phases were evaluated for their extraction efficiency, disturbance by matrix components and overall performance. We finally selected a mixture of a polymeric sorbent and a C18-sorbent, Lichrolut EN and RP-18 or, alternatively, Empore SDB-RPS disks. All bioassays gave clear and robust responses with the SPE extracts. With the bioassay data the treatment efficiency of the STP can be assessed with respect to different modes of toxic action and accordingly different groups of micropollutants. Furthermore, the data allowed for a comparison between the effluent and the receiving river. In all bioassays the primary effluent had a strong effect and this effect was reduced after passing the STP. Treatment efficiency was high (typically over 90%) but varied from bioassay to bioassay, which is expected because each bioassay detects different types of micropollutants and therefore we cannot expect a common answer.     

Bacterial community structure analysis of sediment in the Sagami River, Japan using a rapid approach based on two-dimensional DNA gel electrophoresis mapping with selective primer pairs

A rapid approach based on two-dimensional DNA gel electrophroesis (2-DGE) mapping with selective primer pairs was employed to analyze bacterial community structure in sediments from upstream, midstream and downstream of Sagami River in Japan. The 2-DGE maps indicated that Alpha- and Delta-proteobacteria were major bacterial populations in the upstream and midstream sediments. Further bacterial community structure analysis showed that richness proportion of Alpha- and Delta-proteobacterial groups reflected a trend toward decreasing from the upstream to downstream sediments. The biomass proportion of bacterial populations in the midstream sediment showed a significantly difference from that in the other sediments, suggesting that there may be an environmental pressure on the midstream bacterial community. Lorenz curves, together with Gini coefficients were successfully applied to the 2-DGE mapping data for resolving evenness of bacterial populations, and showed that the plotted curve from high-resolution 2-DGE mapping became less linear and more an exponential function than that of the 1-DGE methods such as chain length analysis and denaturing gradient gel electrophoresis, suggesting that the 2-DGE mapping may achieve a more detailed evaluation of bacterial community. In conclusion, the 2-DGE mapping combined with the selective primer pairs enables bacterial community structure analysis in river sediment and thus it can also monitor sediment pollution based on the change of bacterial community structure.     

Simultaneous quantification of Bi(III) and U(VI) in environmental water samples with a complicated matrix containing organic compounds

Trace amounts of bismuth(III) and uranium(VI) can be simultaneously determined in a single scan by adsorptive cathodic stripping voltammetry in the presence of cupferron as a complexing agent. Optimal conditions were found to be: 0.1 mol?L^?1 acetate buffer (pH 5.3), 5?×?10^?5?mol?L^?1 cupferron, accumulation potential of ?0.25 V, and accumulation time of 30 s. The linear range of Bi(III) and U(VI) was observed over the concentration range from 2?×?10^?9 to 2?×?10^?7?mol?L^?1 and from 1?×?10^?8 to 5?×?10^?7?mol?L^?1, respectively. The influence of the main components of real water samples such as foreign ions and organic substances (surface active substances, humic substances) was precisely investigated. The method was applied to the simultaneous measurements of bismuth and uranium in natural water samples.     

Portable X-ray fluorescence in the characterisation of arsenic contamination associated with industrial buildings at a heritage arsenic works site near Redruth,Cornwall, UK

An investigation using in situ analysis by portable X-ray fluorescence (PXRF) has shown that contamination present on industrial buildings at a heritage arsenic works site near Redruth, Cornwall, UK results from the absorption of arsenic by porous and semi-porous building materials that were in contact with arsenic-rich flue gases. Results from a preliminary survey indicate that arsenic remains locked in these materials and is being gradually leached out by weathering processes. This weathering causes general contamination of the adjacent building surfaces averaging 1845 microg g(-1) arsenic, presumably caused by evaporation of leach solutions in contact with air at the surface of the building materials. More extensive crystalline deposits were found under arches protected from dissolution and further dispersion by rain water. These deposits appeared to comprise calcium sulfate (gypsum), associated with on average between 1.2 and 6.8% m/m As. In situ PXRF proved to be highly effective in locating sources of contamination at the site and in providing data that allowed a hypotheses for the origin of this contamination to be formulated and tested in the field.     

Development of an efficient and sensitive analytical method for the determination of copper at trace levels by slotted quartz tube atomic absorption spectrometry after vortex-assisted dispersive liquid-liquid microextraction in biota and water samples using a novel ligand

This study describes the determination of trace levels of copper by slotted quartz tube atomic absorption spectrometry after dispersive liquid-liquid microextraction. A ligand synthesized from the reaction of salicylaldehyde and 1-naphthylamine was used to form coordinate copper complex prior to extraction. All parameters that influence the output of complex formation, extraction, and instrumental measurement were optimized to enhance the absorbance signal of copper. Under the optimum conditions, about 104-fold enhancement in sensitivity was recorded over the conventional flame atomic absorption spectrometer, corresponding to a 0.51 ng/mL detection limit. The percent relative standard deviation calculated for the lowest concentration (4.8%) indicated high precision for the experimental procedure. Accuracy and applicability of the optimum method were determined by performing spiked recovery tests on urine, lake water, and mineral water samples. Satisfactory recovery results were obtained between 82.2 and 106.3% at four different concentrations. Matrix matching method was also performed to increase the accuracy of quantification, and the percent recovery calculated for 175 ng/mL was 105.14%.