A low-energy intensive electrochemical system for the eradication of Escherichia coli from ballast water: process development, disinfection chemistry, and kinetics modeling

The invasion of biological organisms via ballast water has created threats to the environment and human health. In this study, a cost-effective electrochemical disinfection reactor was developed to inactivate Escherichia coli, one of the IMO-regulated indicator microbes, in simulated ballast water. The complete inactivation of E. coli could be achieved within a very short time (150, 120, or 60 s) with an energy consumption as low as 0.0090, 0.0074 or 0.0035 kWh/m(3) for ballast water containing E. coli at concentrations of 10(8), 10(7) and 10(6) CFU/100 mL, respectively. Electrochemical chlorination was the major disinfection mechanism in chloride-abundant electrolytes, whereas oxidants such as ozone and free radicals contributed to 20% of the disinfection efficiency in chloride-free electrolytes. Moreover, a disinfection kinetics model was successfully developed to describe the inactivation of E. coli.     

Use of coprostanol as a specific allochthonous fecal indicator in surface sediment of the Lake of Neuchâtel

Coprostanol has been proven to be a good specific allochthonous fecal indicator in sedimentary surface samples of the lake of Neuchâtel (Switzerland). Its concentration is slightly affected in surface sediment by the microbial reduction of cholesterol to cholestanol and coprostanol.     

Echinoderms from Azores islands: An unexpected source of antibiotic resistant Enterococcus spp. and Escherichia coli isolates

The prevalence of antibiotic resistance and the implicated mechanisms of resistance were evaluated in Enterococcus spp. and Escherichia coli, isolated from a total of 250 faecal samples of echinoderms collected from Azorean waters (Portugal). A total of 144 enterococci (120 Enterococcus faecium, 14 E. hirae, 8 E. faecalis, 2 E. gallinarum) and 10 E. coli were recovered. High percentages of resistance in enterococci were found for erythromycin, ampicillin, tetracyclin and ciprofloxacin. The erm(A) or erm(B), tet(M) and/or tet(L), vat(D), aac(6′)-aph(2″) and aph(3′)-IIIa genes were found in isolates resistant to erythromycin, tetracycline, quinupristin/dalfopristin, high-level gentamicin and high-level kanamycin, respectively. Resistance in E. coli isolates was detected for streptomycin, amikacin, tetracycline and tobramycin. The aadA gene was found in streptomycin-resistant isolates and tet(A) + tet(B) genes in tetracycline-resistant isolates. The data recovered are essential to improve knowledge about the dissemination of resistant strains through marine ecosystems and the possible implications involved in transferring these resistances either to other animals or to humans.     

Evaluation of equivalence between different methods for enumeration of fecal indicator bacteria before and after adoption of the new Bathing Water Directive and risk assessment of pollution

The quality of bathing water is of considerable public importance due to the possibility of fecal contamination. In 2009, Croatia implemented the new European Bathing Water Directive (BWD, 2006/7/EC) establishing stricter microbiological standards for new parameters with new reference methods. This study aims to evaluate the equivalence of different methods according to the old and revised BWD and to provide the possibility of data comparison. Furthermore, the directive requires the establishment of the bathing water profile (BWP) for pollution risk assessment. The estimation of consistency of pollution risk assessment with obtained microbiological results was also performed.     

An electromagnetic modelling tool for the detection of hydrocarbons in the subsoil

Electromagnetic geophysical methods, such as ground-penetrating radar (GPR), have proved to be optimal tools for detecting and mapping near-surface contaminants. GPR has the capability of mapping the location of hydrocarbon pools on the basis of contrasts in the effective permittivity and conductivity of the subsoil. At radar frequencies (50 MHz to 1 GHz), hydrocarbons have a relative permittivity ranging from 2 to 30, compared with a permittivity for water of 80. Moreover, their conductivity ranges from zero to 10 mS/m, against values of 200 mS/m and more for salt water. These differences indicate that water/hydrocarbon interfaces in a porous medium are electromagnetically 'visible'. In order to quantify the hydrocarbon saturation we developed a model for the electromagnetic properties of a subsoil composed of sand and clay/silt, and partially saturated with air, water and hydrocarbon. A self-similar theory is used for the sandy component and a transversely isotropic constitutive equation for the shaly component, which is assumed to possess a laminated structure. The model is first verified with experimental data and then used to obtain the properties of soils partially saturated with methanol and aviation gasoline. Finally, a GPR forward-modelling method computes the radargrams of a typical hydrocarbon spill, illustrating the sensitivity of the technique to the type of pore-fluid. The model and the simulation algorithm provide an interpretation methodology to distinguish different pore-fluids and to quantify their degree of saturation.     

Cumulative impacts on seabed habitats: An indicator for assessments of good environmental status

The European seas are under anthropogenic pressures impacting the state of water quality, benthic habitats and species. The EU Marine Strategy Framework Directive (MSFD) requires the Member States to assess the impacts of pressures and make a programme of measures leading to good environmental status (GES) by 2020. This study presents a method for assessing the quantity and distribution of anthropogenic impacts on benthic habitats in the Baltic Sea by using spatial data of human pressures and benthic habitats. The southern sub-basins were more extensively impacted than the northern sub-basins. Over the entire sea area, deep sea habitats were more impacted than shallower infralittoral and circalittoral habitats. Sand and coarse sediments were the seabed types relatively most impacted in the Baltic Sea scale. A comparison against tentative thresholds for GES showed that in the sub-basin scale only one third of the habitat types was in GES.     

Application of a novel phytotoxicity assay for the detection of herbicides in Hervey Bay and the Great Sandy Straits

A novel phytotoxicity assay was incorporated into an environmental assessment of Hervey Bay and the Great Sandy Straits, to investigate the role of run-off associated herbicides in the deteriorated health of intertidal seagrass meadows. Dose response curves of common herbicides were performed and their toxicity equivalents elucidated to assist in analysis. The results of the assay were reproducible and corresponded strongly with results of chemical analyses. The incorporation of the assay into the assessment of surface waters added an important aspect to the study by allowing investigation of the toxicity of cumulative herbicide concentrations and yielding biologically relevant data. The highest herbicide concentration detected during the study was equivalent to 0.23 microg l(-1) diuron; a concentration known to inhibit photosynthetic efficiency of the assay biomaterial by approximately 3%.     

岩浆囊的地震学探测技术概述

在过去的２０年里，探测和勾画岩浆囊的科学有了长足的进步。多种地震技术，包括速度和衰减的层析成像，地震活动性映像，反射和折射，势场技术，如重力，大地测量和电磁观测，都提供了关于在几个火山下面的岩浆囊的大小，形状和物理状态的有用信息。本文对这些技术进行了讨论和综述。我国已在Ｐ波波速层析成像方面开展了一系列工作。特别是在云南地区已得到了该省及其邻近地区的三维速度图像。由于现有台网不够密集，获得的速度图像分辨较低。尽管如此，在腾冲地区从２０ｋｍ到４５０ｋｍ深度都有低速度结构的显示。要想系统地研究腾冲火山地区的火山构造和地震活动性，以及探测该地区的岩浆囊，必须在该地区布设较密集的地震观测台网。     

An operational method for the real-time monitoring of E. coli numbers in bathing waters

The aim of this study was to investigate the potential application of the beta-d-glucuronidase (GLUase) activity measurement for the routine detection and quantification of E. coli in marine bathing waters. GLUase activity was measured as the rate of hydrolysis of 4-methylumbelliferyl-beta-d-glucuronide. Culturable E. coli were quantified by the most probable number (MPN) microplate method. Both methods were applied to a large set of seawater samples. Significant correlation was found between the log of GLUase activity and the log of culturable E. coli. The mean coefficient of variation (CV) of the GLUase activity was less than 15% at concentrations around the current standards of International regulations whereas the CV of the microplate method was around 30%. When samples were stored at 4 degrees C and 20 degrees C, the mean CV of the GLUase activity remained below 15% up to 6 hours after sample collection whereas the range of variation of the microplate method varied between 10 and 50%. We concluded that the GLUase activity is an operational, reproducible, simple, very rapid and low cost method for the real-time enumeration of E. coli in bathing waters and should be preferred to the microplate method. The GLUase activity method should be routinely applied to the rapid enumeration of E. coli in recreational waters and recommendations for its application were suggested to water quality managers.     

An early warning indicator for monitoring infectious animal diseases and its application in the case of a sheep pox epidemic

We describe an early warning indicator for monitoring infectious diseases. The approach is illustrated with data from a major sheep pox epidemic, which occurred in the Evros prefecture of Greece, from August 2013 until the end of 2014. We present the epidemic data and identify factors affecting this major epidemic using a suitable methodological framework for the sequential analysis of such outbreaks. Environmental conditions and seasonality affect the spread of the epidemic: autumn seems to enhance disease occurrence and higher average temperatures facilitate disease spread. The on-line prediction of the disease potential is investigated through an early warning system that is based on the probability of the disease going extinct. The temporal stability of this indicator is extensively explored.     

An application of three-dimensional electrical resistivity imaging for the detection of an underground waste-water system

A 3D electrical resistivity imaging survey is presented in this paper. The objective was to investigate an underground wastewater system at the University of Malaya, Malaysia. Apparent resistivity data were collected along ten parallel lines using a Wenner-Schlumberger configuration; electrode cables were oriented in the x-direction with 3 m spacing. Roll-along measurements using a line spacing of 3 m were carried out covering a grid of 20 × 10 electrodes. All data sets were merged into a single data file in order to perform a 3D inversion. Two different 3D least squares algorithms, based on the robust inversion method and the smoothness-constrained technique, were used for the inversion of the apparent resistivity data. Both the horizontal and vertical extents of the anomalous zones found by inversion are displayed. The results indicate the superiority of the robust inversion method over the smoothness-constrained technique at this site. The results are in sufficient accordance with previously known information about the investigation area. The results show that 3D electrical resistivity imaging surveys, in combination with an appropriate 3D inversion method, can be highly useful for engineering and archaeological investigations as well as for environmental applications.     

微弱信号混沌检测临界阈值的Lyapunov指数算法

提供一种微弱信号混沌检测中临界阈值的判定方法,将Lyapunov特性指数作为混沌判据引入了微弱信号混沌检测领域,为混沌检测提供了一种量上的判据、并将这种算法与其它算法进行比较,仿真实验充分证明了该方法的有效性和优越性。     

Preliminary evidence for human fecal contamination in corals of the Florida Keys,USA

Corals and reef environments are under increased stress from anthropogenic activities, particularly those in the vicinity of heavily populated areas such as the Florida Keys. The potential adverse impacts of wastewater can affect both the environment and human health; however, because of the high decay rate of bacterial indicators in coral reef waters it has been difficult to document the presence of microbial contaminants and to assign risks in these environments. Here we show initial evidence that microorganisms associated with human feces are concentrated along the surface of coral heads relative to the overlying water column in the Florida Keys. Bacterial indicators (fecal coliform bacteria, enterococci or Clostridium perfringens) were detected in 66.7% of the coral surface microlayer (CSM) samples at levels between five and 1000 CFU/100 ml, but were found infrequently and at low numbers in the overlying water column ( < or = 2.5 CFU/100 ml). Similarly, enterovirus nucleic acid sequences, an indicator of human-specific waste, were detected in 93.3% of the CSM samples and only once in the water column by cell culture. Results show that coral mucus may accumulate enteric microorganisms in reef environments, and may indicate a risk to public and environmental health despite low indicator levels in the surrounding water.     

An inexpensive circuit design for the acoustic detection of oscillations in bedload transport in natural streams

A circuit design is reported which is demonstrated to be capable of receiving and recording the underwater sound of inter-particle collisions on natural stream beds during the process of bedload transport. Field trials were undertaken in a natural stream with sand-sized bedload particles. The results obtained, for a constant stream stage, give support to the idea of the occurrence of short period oscillations in the rate of bedload transport.     

Comet assay for the detection of genotoxicity in blood cells of flounder (Paralichthys olivaceus) exposed to sediments and polycyclic aromatic hydrocarbons

To investigate the genotoxic effect of marine sediments on aquatic organism, sediment samples were collected from 13 sites along the coast of Gwangyang Bay (Korea). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments were determined and the relationship between exposure of flounder blood cells to sediment extracts and DNA single-strand breakage in the blood cells was examined using the comet assay. Levels of DNA damage were proportionally increased by exposure concentration and the highest sediment-associated DNA damage was observed at the station showing the highest PAHs contamination. DNA damage in blood cells exposed to five types of PAHs (benzo[a]pyrene, fluoranthene, anthracene, pyrene and phenanthrene) and in flounder (Paralichthys olivaceus) exposed to benzo[a]pyrene (BaP) for 0, 2 and 4 days were assessed by measuring comet tail length. The tail lengths of five PAHs-exposed groups at 50 and 100 ppb were significantly different from the non-exposed group, and the genotoxic effect of BaP correlated with both concentration and duration of exposure. Throughout the study, significant differences in DNA breakage were recorded between cells exposed to sediment extracts or PAHs and non-exposed control. This study demonstrated the comet assay as a successful tool in monitoring contamination of marine sediments and assessing genotoxicity of PAHs in marine organisms, either in vitro or in vivo.     

Strain and kinematic vorticity analysis: An indicator for sinistral transpressional strain-partitioning along the Lancangjiang shear zone,western Yunnan,China

This work deals with the preliminary relationship between strain path and strain partitioning pattern in a sinistral transpressional zone,Lancangjiang shear zone,located to the southeast of Tibet.Various ductile rocks provide an opportunity to investigate quantitative finite strain(Rs),kinematic vorticity values(Wm),and proportions of simple and pure shear components.The mean kinematic vorticity values(Wm) were evaluated based on three methods,such as Rs-θ,prophyroclast hyperbolic distribution method(PHD),a...     

A new indicator of elastic spectral shape for the reliable selection of ground motion records

How to select a limited number of ground motion records (GMRs) is an important challenge for the non‐linear analysis of structures. Since epsilon (ε_Sa) is an indicator of spectral shape, which has a significant correlation with the non‐linear response of a structure, the selection of GMRs based on the hazard‐related target ε_Sa is a reasonable approach. In this paper, an alternative indicator of spectral shape is proposed, which results in a more reliable prediction of the non‐linear response for the structures with the natural period of 0.25 to 3.0 s. This new parameter, named eta (η), is a linear combination of ε_Sa and the peak ground velocity epsilon (ε_PGV). It is shown that η, as a non‐linear response predictor, is remarkably more efficient than the well‐known and convenient parameter ε_Sa. The influence of η‐filtration in the collapse analysis of an eight‐story reinforced concrete structure with special moment‐resisting frames was studied. Statistical analysis of the results confirmed that the difference between ε‐filtration and η‐filtration can be very significant at some hazard levels. In the case of this structure, the resulting annual frequency of collapse was found to be lower in the case of η‐based record selection, in comparison with the ε‐based record‐selection approach. Copyright © 2011 John Wiley & Sons, Ltd.     

Clostridium perfringens as a potential indicator for the presence of sewage solids in marine sediments

Marine sediment cores collected from several depths of water and distances from a California sewage outfall were tested to see if sediments influenced by sewage solids were a reservoir of enteric pathogens, and if concentrations of indicator bacteria were related to the presence of sewage solids. Vertical distributions of microorganisms in marine sediments were determined; there was a decrease of indicator bacteria with increasing sediment depth. Aeromonas was randomly isolated, but none of the enteric bacterial pathogens or viruses were detected. While classic indicator bacteria were of little value in predicting the presence of pathogens, or relative amounts of sewage solids, Clostridium perfringens may be a suitable indicator. Clostridium perfringens concentrations were not related to the presence of pathogens in sediments.