Real Water Environment Research Articles

An integrated modeling approach for identifying cost-effective strategies in controlling water pollution of urban watersheds

In water pollution control of urban river basins, one major issue is to reduce water pollutants at the least costs. In this research, an integrated hydrodynamic-water quality simulation-based multi-response surface method was proposed to help optimize mitigation measures on water quality rehabilitation in Shiwuli River basin of Hefei City, China. Initially, multi-response surface method (MRSM) with two-levels and two responses, i.e., cost-effectiveness ratio (CER) and water quality standard-reaching rate (WQSR) were designed where the factors of interests include the point source reducing rate (i.e., Factor A), the non-point source reducing rate (i.e., Factor B) and water transfer (i.e., Factor C). Then a hydrodynamic-water quality model was developed to predict water quality effects of the proposed combined factors. At the same time, the cost functions were established to estimate economic costs of the combined factors. Lastly, the analysis of variance (ANOVA) and multiple regression analysis (MRA) were employed to help gain some new cognition in the statistically significant way. The obtained model revealed that Factor A and B were significant for both CER and WQSR. This means that in the study area, pollution source reduction is more important than water transfer. Though the optimal minimal CER was obtainable with 0.1493 (M$ per percentage) when the pointing source reducing rate is 77.9%, the non-point source reducing rate is 40% and the water transfer was controlled at a low level, respectively, with water quality standard-reaching rate 70.7%. It fails to achieve water quality objectives (WQSR ≥ 90.0%). Moreover, In order to meet water quality target, simultaneous optimization of two objective functions: minimal CER and maximal WQSR was achievable with the optimum value of 90% for WQSR and 0.1810 (M$ per percentage) for CER ,respectively, with the pointing source reducing rate (90.0%), the non-point source reducing rate (57.2%) and the water transfer at a low level. It provided an alternative simulation–optimization method for decision of water pollution control which had the advantages in reflecting the real water environment system and simplifying the algorithm compared to the conventional mathematical programming at the watershed scale.

Highly sensitive detection of trace Hg2+ via PdNPs/g-C3N4 nanosheet-modified electrodes using DPV

In this work, Pd nanoparticle (PdNP)-modified graphite carbon nitride (g-C3N4) porous nanosheets (PdNPs/g-C3N4) were synthesized via reduction by hydrazine hydrate. The morphology analysis of the PdNPs/g-C3N4 nanosheets indicated that PdNPs were uniformly distributed on the g-C3N4 surface. The PdNPs/g-C3N4 modified glassy carbon (GC) electrode (PdNPs/g-C3N4/GC) was used for the trace detection of Hg2+ by differential pulse voltammetry (DPV). Excellent sensitivity and selectivity toward the determination of trace Hg2+ were achieved, as well as excellent anti-interference, repeatability, and long term stability under similar optimal experimental conditions. The limit of detection (LOD) for Hg2+ was 0.009 µg/L, lower than WHO standard (1.0 µg/L) and previously reported values. Moreover, the PdNPs/g-C3N4/GC electrode was employed to detect Hg2+ ions in real water environments, including local tap, lake, and river water samples, aiming at manifesting the potential practical applications of the electrode. The outstanding electrochemical performance of the PdNPs/g-C3N4 GC electrode toward Hg2+ detection was mainly ascribed to the combined advantages of the large specific surface area of the nanosheets and improved electrical conductivity owing to the deposited PdNPs. The current study provides a green and feasible method for the detection of trace Hg2+ in real water environments.

Designing ordered composites with confined Co–N/C layers for efficient pollutant degradation: Structure-dependent performance and PMS activation mechanism

Abstract Rational design of ordered catalytic composites with high performance and facile preparation method for environmental remediation still remains a tremendous challenge. For this vision, ordered composites with confined cobalt intercalated N/C layers (Co–N/C) were successfully prepared via carbonizing a mixture of cobalt species, histidine (His) and zirconium-containing SBA-15 (ZS) utilizing a simple non-solvent method. Taking the confinement effect and inherent hydrophilic groups (Si–OH) of mesoporous silica as the foothold, the strong Co2+/N or Co2+/O coordination (Co2+(–COO- or –NH2)2 and Co2+(–O-)2) and silica/His or His/His adhesive/cohesive interactions endowed the Co-based catalyst with optimal interfacial properties, cycling stability and magnetic separability for degradation of several pollutants (phenol, antibiotics and dyes). The degradation efficiency of Co@NC-ZS-700 for bisphenol A was superior to Co-ZS-700, NC-ZS-700 and Co@NC-SBA-700 due to the flaky structure with confined Co–N/C layers, which could achieve 95.0% within 20 min. In addition, the catalyst could still degrade more than 84.4% bisphenol A after five consecutive reactions. Based on the characterization analysis, tested active species (SO4•–, •OH and 1O2) and degradation products, double-process activation mechanism and degradation pathways were plausibly proposed (radical and non-radical processes). Additionally, various influencing factors, including carbonization temperature, amount of cobalt species, peroxymonosulfate (PMS)/catalyst dosage, pH value, coexisting ions and real water environment, were also systematically studied. This work might pave a feasible way for contaminant treatment utilizing ordered mesoporous silica composites with diffusion promoted channels involved under aqueous systems.

A water-soluble colorimetric and fluorescent probe for rapidly sensing of ClO− in organisms

A simple colorimetric and fluorescent probe bearing coumarin and p-toluenesulfonyl hydrazide moieties was developed, which was capable of displaying excellent selectivity for hypochlorite. The distinct absorption spectral shift (49 nm) was induced by ClO−-triggered oxidative hydrolysis of CN double bonds in aqueous solution, which was accompanied by the optical variation from yellow to colorless. Besides, this probe solution underwent a dramatic intensification (162-fold) of the fluorescence signaling at 444 nm via the addition of ClO− (3 equiv.) within a short time. More importantly, the results achieved by fluorescence spectra revealed an excellent linear relation of probe 1 for ClO− with excellent sensitivity (9.1 nM). Further, the good recoveries and cellular experiments verified the prospective functions of this probe in real water environment and SW 480 cells.

Rapid preparation of adsorbent based on mussel inspired chemistry and simultaneous removal of heavy metal ions in water

In order to solve the problem of coexistence pollution of heavy metal ions in real water environment, a polydopamine (PDA) modified polypropylene non-woven adsorbent was rapidly prepared by one-step method based on mussel-inspired chemistry. The mussel inspired chemical reaction was accelerated by combining oxidants with diamine. The interaction between coexisting metal ions severely inhibits the removal of adsorbents with single active site, a multifunctional non-woven absorbent (PP/PDA/ASA) was synthesized through introducing salicylic acid groups at the end of PDA to increase the type of adsorption sites and address the issue of low removal efficiency caused by competitive effects in multicomponent system. The synthesized adsorbent was characterized by SEM, FTIR spectroscopy and XPS techniques. Meanwhile, the adsorption capacity of Cu(II), Cd(II) and Pb(II) on PP/PDA/ASA was systematically studied in single and multi-target systems under various conditions. The findings indicated that the PP/PDA/ASA could remove 90% of Cu(II) and Pb(II), and 80% of Cd(II) from 5 mg/L of Cu(II)/Cd(II)/Pb(II) mixed solution at the sorbent:solution mass ratio of 1:1000. Noticeably, the adsorption capacity and rate of the metal ions in the multi-component system were reduced, indicating the strong competitive adsorption in the multi-component system. XPS analysis showed that various functional groups (amino, hydroxyl and carboxyl groups) on the surface of PP/PDA/ASA were involved in the adsorption of heavy metal ions. The adsorption mechanism included coordination and ion exchange between metal ions and functional groups, while the adsorption mechanisms of Cu(II), Cd(II) and Pb(II) were different.

Bioimaging of a fluorescence rhodamine-based probe for reversible detection of Hg (II) and its application in real water environment

Mercury is a typical serious pollutant certified by relevant authorities, it is harmful not only to biological health but also to the ecological environment and its superior detection approach remains challenging. About this research, a novel reversible fluorescent probe(RBST) based on 2-Thiopheneacetyl chloride and Rhodamine B was designed，synthesized and established to develop as a chemosensor. Its sensing behavior, especially for various common metal ions, was detected by UV–vis spectrum and fluorescence spectrum. RBST displayed a satisfactory sensitivity and selectivity fluorescent response towards Hg2+ in a solution of EtOH/H2O (2,1, v/v), giving a higher combining constant of 3.03 × 104 M−1 and a lower detection limit of 0.11 μM respectively. Fluorescence quenched presented a reversible behavior with a certain amount of S2− was added under the condition of containing Hg2+. Besides, the practicality of the probe in sensing Hg2+ in real water samples was further proved. Results of this study suggested that the fluorescent reversible probe excels in biological applications and can be applied in MCF-7 cells, zebrafish and soybean rhizome tissues to detect Hg2+.

Improving Electrochemical Pb2+ Detection Using a Vertically Aligned 2D MoS2 Nanofilm.

Recent advancements in MoS2 nanofilms have aided in the development for important water-related environmental applications. However, a MoS2 nanofilm-coated sensor has yet to have been applied for heavy metal detection in water-related environmental samples. In this study, a novel vertically aligned two-dimensional (2D) MoS2 (edge exposed) nanofilm was applied for in situ lead ion (Pb2+) detection. The developed sensor showed an excellent linear relationship toward Pb2+ between 0 and 20 ppb at -0.45 V vs Ag/AgCl using square wave anodic stripping voltammetry (SWASV) with the improved limit of detection (LOD) of 0.3 ppb in a tap water environment. The vertically aligned 2D MoS2 sensor exhibited improved detection sensitivity (2.8 folds greater than a previous metallic [Bi] composite electrode) with lower relative standard deviation for repetitive measurements (n = 11), indicating enhanced reproducibility for Pb2+ detection. The vertically aligned 2D MoS2 layers exhibited 2.6 times higher sensitivity than horizontally aligned 2D MoS2 (basal plane exposed). Density functional theory calculations demonstrated that adsorption energy of Pb on the MoS2 side edge was much higher (4.11 eV) than those on the basal plane (0.36 and 0.07 eV). In addition, the band gap center of vertical MoS2 was found to be higher than the Pb2+ → Pb reduction potential level and capable of reducing Pb2+. Overall, the newly developed vertically aligned 2D MoS2 sensor showed excellent performance for detecting Pb2+ in a real drinking water environment with good reliability.

Highly luminescent sensing for nitrofurans and tetracyclines in water based on zeolitic imidazolate framework-8 incorporated with dyes

Antibiotics are one of the emerging contaminants in water, which have a great impact on ecosystems and human health. It has been challenging to simultaneously realize low-cost, rapid, highly sensitive and selective detection of antibiotics with conventional methods. Here, we report luminescent chemosensors for detecting antibiotics in water, based on metal-organic framework (MOF), i.e., zeolitic imidazolate framework-8 (ZIF-8), loaded with rhodamine B (RhB) and fluorescein disodium salt (FSS) dyes. Compared with ZIF-8, the fluorescence signals of RhB@ZIF-8 and FSS@ZIF-8 were significantly improved and presented ultrahigh sensitivity to nitrofurans (NFAs) and tetracyclines (TCs) with fluorescence quenching and fluorescence enhancement in water, respectively. The unique structures and properties of RhB@ZIF-8 and FSS@ZIF-8 lead to outstanding sensitivities in antibiotic detection. For instance, the RhB@ZIF-8 sensor shows the lower limit of detection (LOD) of 0.26 μM to nitrofurantoin (NFT), 0.47 μM to nitrofurazone (NFZ), 0.11 μM to tetracycline (TC), and 0.14 μM to oxytetracycline (OTC); while the FSS@ZIF-8 sensor shows the LOD of 0.31 μM to NFT, 0.35 μM to NFZ, 0.17 μM to TC, and 0.16 μM to OTC. In addition, NFT and TC were also successfully detected by FSS@ZIF-8 in water from real water environment. The results indicate that dye@MOF-based luminescent composites are favorable for antibiotic detection, presenting great potentials in water quality monitoring.

New insight into the aggregation of graphene oxide in synthetic surface water: Carbonate nanoparticle formation on graphene oxide

Graphene oxide (GO), used in a wide variety of applications, is increasingly being introduced into aquatic environments; this situation calls for research on GO aggregation and sedimentation to regulate the environmental behaviors and risks. Many studies have investigated the aggregation and the mechanism of GO in water with a single background salt (monosalt system); however, this may not reflect real water environments where multiple salts coexist (multisalt system). A typical synthetic surface water (soft water) with representative multisalts was therefore used to study the aggregation and sedimentation of GO. The GO concentration-dependent aggregation (low concentration aggregation, high concentration stability) was observed in the soft water, and this concentration-dependent aggregation is opposite to the aggregation in monosalt systems (NaCl or CaCl2 solutions). The presence of GO sheets induced the formation of amorphous CaMg(CO3)2 nanoparticles on the GO surfaces in the soft water, and the formed nanoparticles promoted the aggregation and sedimentation of low concentrations of GO through bridging action. Neutral and alkaline conditions were favorable for the formation of CaMg(CO3)2 nanoparticles and the induced GO aggregation. These findings show a new mechanism of GO aggregation in environmentally relevant waters and help us to better evaluate the environmental fate of GO.

Bifunctional MoS2 coated melamine-formaldehyde sponges for efficient oil–water separation and water-soluble dye removal

Removal of pollutants from water is an important global challenge for energy conservation and environmental protection. Advanced macro-porous sorbent materials with three-dimensional wettability surfaces have been considered traditional candidates for wastewater treatment. Although the real water environment always co-exists with two pollution sources, the major functions of existing macro-porous materials are limited to either water-insoluble organics separation or water-soluble dyes removal. Bifunctional macro-porous materials for simultaneous oil–water separation and soluble elements removal are currently lacking. Here we report the novel MoS2-coated melamine-formaldehyde (MF@MoS2) sponges with different wettabilities, for example, superhydrophobicity and superhydrophilicity, exhibiting both high selectivity and excellent absorption capacities for a wide range of oils/organic solvents with different densities and water-soluble dyes. The functional MF@MoS2 sponges perform high absorption capacity for different organic solvents up to 66 and 157 times of its own weight respectively, while showing high discoloration efficiency of 98% methyl orange within 10min. For the first time, we report these functional macro-porous materials used for simultaneous cleaning of oil and soluble pollutants in water, which extended the potential of MoS2 for environmental application. Furthermore, a continuous and simultaneous removal of insoluble oils and soluble dyes in situ from water was achieved by simply applying external pumping on the functional macro-porous MF@MoS2 sponges.

Real-Time Video Transmission Over Different Underwater Wireless Optical Channels Using a Directly Modulated 520 nm Laser Diode

We experimentally demonstrate high-quality real-time video streaming over an underwater wireless optical communication (UWOC) link up to 5 m distance using phase-shift keying (PSK) modulation and quadrature amplitude modulation (QAM) schemes. The communication system uses software defined platforms connected to a commercial TO-9 packaged pigtailed 520 nm directly modulated laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter and an avalanche photodiode (APD) module as the receiver. To simulate various underwater channels, we perform laboratory experiments on clear, coastal, harbor I, and harbor II ocean water types. The measured bit error rates of the received video streams are 1.0 × 10-9 for QPSK, 4-QAM, and 8-QAM and 9.9 × 10-9 for 8-PSK. We further evaluate the quality of the received live video images using structural similarity and achieve values of about 0.9 for the first three water types, and about 0.7 for harbor II. To the best of our knowledge, these results present the highest quality video streaming ever achieved in UWOC systems that resemble communication channels in real ocean water environments.

A highly stable electrochemiluminescence sensing system of cadmium sulfide nanowires/graphene hybrid for supersensitive detection of pentachlorophenol

A highly stable and effective electrochemiluminescence (ECL) sensing system of cadmium sulfide nanowires/reduced graphene oxide (CdS NWS/rGO) hybrid is presented for supersensitive detection of pentachlorophenol (PCP). CdS nanowire is for the first time exploited in ECL sensing. The rGO served as both ECL signal amplifier and immobilization platform, can perfectly enhance the ECL intensity and stability of the sensing system. With S2O82− as coreactant, the ECL signal can be significantly quenched by the addition of PCP. The established ECL sensing system presents a wider linear range from 1.0×10−14 to 1.0×10−8M and a much low detection limit of 2×10−15M under the optimum test conditions (e.g., pH 7.0 and 100mM S2O82−). Furthermore, the ECL sensing system displays a good selectivity for PCP detection. The practicability of the ECL sensing system in real water sample shows that this system could be promisingly applied in the analytical detection of PCP in real water environments.

A review of the toxicity of nanoparticles to <italic>Daphnia magna</italic>

With the wide production and usage of nanoparticles, nanotoxicity has received worldwide researches. As a model organism, Daphnia magna has been extensively used in the nanotoxicity studies. In this review, we overviewed research advance in the toxicity of nanoparticles to Daphnia magna , including acute toxicity, chronic toxicity, bioaccumulation, and the underlying mechanisms. Nanoparticles have dose-responsive acute toxicity to Daphnia manga and their toxicity is related to types of nanoparticles and culture media. Smaller nanoparticles generally have higher toxicity to Daphnia manga , presumably due to their easier transport through cell membranes. Due to polar functional groups and organic macromolecules are able to change surface properties of nanoparticles, most studies suggest that the acute toxicity of nanoparticles might be weakened by surface modification. High concentrations of nanoparticles can suppress the growth and reproduction of Daphnia manga . Bioaccumulation studies showed that nanoparticles could accumulate in Daphnia magna via water, feeding food, and absorbing through the skin. Since the concentration of nanoparticles, exposure time and cultivation media adopted in the studies varied greatly, the body burden and bioconcentration factor of nanoparticles were largely different, which makes it hard to compare accumulation capacity of Daphnia manga to different nanoparticles. At high exposure concentrations, accumulation amount of nanoparticles by Daphnia manga could reach µg/mg level. Although the toxicity mechanisms of nanoparticles to Daphnia manga have not been fully understood, below points are generally used to explain the toxicity: nanoparticle specific toxic, the release of toxic metal ions, and forming toxic complexes with other compounds. Nanoparticles and the release of metal ions can adhere and aggregate onto surfaces of Daphnia manga , causing the physical damage, membrane permeability changes, and cell function loss. They can also promote the production of the reactive oxygen species (ROS) and free radical, leading to lipid peroxidation, protein carbonylation and DNA damage. In addition, some nanoparticles themselves are not toxic, but can form complexes with toxic substance. At the end of text, we proposed several future research needs. First, compared with the experimental cultivation media, the physical and chemical properties of natural waters are obviously different, likely to cause big difference in the toxicity results. Therefore, realistic toxicity in natural waters needs to be studied. Second, the exposure concentrations of nanoparticles in chronic experiments are much higher than that in the real water environment, and the exposure time is also not long enough compared with practical condition. Lower concentrations and longer exposure time of nanoparticles are of great significance. Third, there is no unified approach in bioaccumulation experiments, making it difficult to compare and analyze the results from different labs. A standard test method established for the bioaccumulation test is thus required. Moreover, nanoparticles can remain in Daphnia magna and transfer to their offspring and other organisms though food chains. Hence, it is necessary to study the transformation, chronic toxicity, intergenerational transfer, and migration though food chains of nanoparticles. Lastly, up to date, toxicity mechanisms of nanoparticles to Daphnia manga have yet to reach a consensus. Nanoparticle characteristics, the growth status of Daphnia magna , culture medium compositions, toxicity experimental method, and many other factors might influence the judgment of the toxicity mechanisms. In order to better understand the toxic effects caused by nanoparticles, more researches are supposed to be done to find the impacts of these factors on the toxicity mechanisms.

Water sampling techniques for continous monitoring of pesticides in water

Good ecological and chemical status of water represents the most important aim of the Water Framework Directive 2000/60/EC, which implies respect of water quality standards at the level of entire river basin (2008/105/EC and 2013/39/EC). This especially refers to the control of pesticide residues in surface waters. In order to achieve the set goals, a continuous monitoring program that should provide a comprehensive and interrelated overview of water status should be implemented. However, it demands the use of appropriate analysis techniques. Until now, the procedure for sampling and quantification of residual pesticide quantities in aquatic environment was based on the use of traditional sampling techniques that imply periodical collecting of individual samples. However, this type of sampling provides only a snapshot of the situation in regard to the presence of pollutants in water. As an alternative, the technique of passive sampling of pollutants in water, including pesticides has been introduced. Different samplers are available for pesticide sampling in surface water, depending on compounds. The technique itself is based on keeping a device in water over a longer period of time which varies from several days to several weeks, depending on the kind of compound. In this manner, the average concentrations of pollutants dissolved in water during a time period (time-weighted average concentrations, TWA) are obtained, which enables monitoring of trends in areal and seasonal variations. The use of these techniques also leads to an increase in sensitivity of analytical methods, considering that pre-concentration of analytes takes place within the sorption medium. However, the use of these techniques for determination of pesticide concentrations in real water environments requires calibration studies for the estimation of sampling rates (Rs). Rs is a volume of water per time, calculated as the product of overall mass transfer coefficient and area of the receiving phase exposed to the external environment, and it is substance specific.

Electrochemical Detection of Trace Arsenic(III) by Nanocomposite of Nanorod-Like α-MnO2Decorated with ∼5 nm Au Nanoparticles: Considering the Change of Arsenic Speciation

It has been reported that the majority of groundwater shows weak alkaline in which the As(III) species would be present as neutral H3AsO3 species and ionized H2AsO3- species. However, as most reported previously, electrochemical detection of As(III) has been operated under acidic conditions and the nonionic As(III) (H3AsO3) is the dominant species. Therefore, considering the change of As(III) speciation in different pH conditions, to develop a reliable method for the detection of As(III) in alkaline media might be more meaningful for practical applications. Here, combined the multilayer adsorption of nanorod-like α-MnO2 with the excellent electrocatalytic ability of ∼5 nm Au nanoparticles (AuNPs), an efficient and ultrahigh anti-interference electrochemical detection of As(III) with AuNPs/α-MnO2 nanocomposite in alkaline media (nearly real water environment) was developed. Notably, we have provided a thorough electrochemical analytical investigation to confirm the advantage of As(III) detection in alkaline media. The system was evaluated by a series of interference tests, and no obvious interference from commonly coexisting substances (referring to the groundwater, Togtoh region, Inner Mongolia, China) was observed in alkaline media. Furthermore, electrodes robust stability and excellent reproducibility were obtained. Under the optimized conditions, the limit of detection (3σ method) toward As(III) was 0.019 ppb, and the obtained sensitivity was 16.268 ± 0.242 μA ppb-1 cm-2. Finally, the proposed method has been successfully employed for detection of As(III) in a real water sample.

Experimental Research on Creep Laws of High-Water Material under Real Pressure Water Environment

High-water material is a kind of new inorganic nonmetal material which mainly used in coal mine goaf filling. In order to simulate the real stress conditions of this material in goaf filling, the creep tests of high-water material in real pressure water environment were conducted and the creep laws were also researched. The results showed that water environment was conductive to maintaining and developing the strength of high-water material, and pressure water environment can improve the carrying capacity and long-term strength of high-water material. The deformation of steady creep period decreased while water pressure increased. And strain increasing caused by axial compression was less than strain increasing caused by water pressure. The time needed from starting to steady creep period was longer when water pressure was bigger.

Synthesis of Polydopamine Functionalized Reduced Graphene Oxide-Palladium Nanocomposite for Laccase Based Biosensor.

Graphene based 2D nanomaterials have attracted increasing attention in biosensing application due to the outstanding physicochemical properties of graphene. In this work, palladium nanoparticles (Pd) loaded reduced graphene oxide (rGO) hybrid (rGO-Pd) was synthesized through a facile method. Laccase (Lac) was immobilized on rGO-Pd by utilizing the self-polymerization of dopamine, which generated polydopamine (PDA). The PDA-Lac-rGO-Pd nanocomposites were further modified on electrode surface to construct novel biosensing platform. The obtained electrochemical biosensor was applied in the detection of catechol, achieving excellent analytic results. Under the optimum condition, this biosensor possessed a linear range from 0.1 µM to 263 µM for catechol detection, the sensitivity reached 18.4 µA mM−1, and the detection limit was as low as 0.03 µM. In addition, the biosensor also showed good repeatability, reproducibility, anti-interference, and stability. Moreover, the novel Lac based biosensor was successfully used in the trace detection of catechol existing in real water environment.

Roles of 3,3',4',5-tetrachlorosalicylanilide in regulating extracellular electron transfer of Shewanella oneidensis MR-1.

Microbial extracellular electron transfer (EET) is critically involved in many pollutant conversion processes in both natural environment and engineered bioelectrochemical systems (BES), but typically with limited efficiency and poor controllability. In this study, we discover an important role of uncouplers in affecting the microbial energy metabolism and EET. Dose of lower-concentration 3,3′,4′,5-tetrachlorosalicylanilide (TCS) in the anolyte promoted the current generation and substrate degradation of an MFC inoculated with Shewanella oneidensis MR-1. However, higher TCS dosage caused obvious microbial inhibition. Our results suggest a previously unknown role of uncouplers in regulating the microbial EET. In addition, the underlying mechanisms of such processes are investigated. This work broadens our view about the EET behaviors of microorganisms in real water environment where uncouplers are usually present, and suggests a possible new approach to regulate microbial EET in BES.

유해물질 노출로 인한 분자.생화학적 바이오마커와 담수 어류에 대한 현장 적용성

As concerns regarding water pollution grow, the need increases for a fast and accurate assessment of ecological risk. In this context, many studies have been conducted to identify biomarkers which can sensitively indicate exposure to and effects of various contaminants in a water environment. However, the utility of most such biomarkers in the real water environment is not yet validated. In this paper, we conducted a thorough review of publications that were related to developing or evaluating molecular and biochemical biomarkers of freshwater fish in ecological risk assessment, and evaluated whether these biomarkers of interest could link to the effects on higher biological levels, such as histopathology and above. Biomarkers of interest included those associated with metabolism, oxidative stress, reproduction and endocrine disruption, genotoxicity, and defense against heavy metal exposure. We found that, when used alone, most molecular and biochemical biomarkers are not sufficient to understand the effects of toxic substances in higher biological levels, due to defense or acclimation mechanisms of organisms. Moreover, some biomarkers respond not only to hazardous substances but also to the changes in water quality and disease outbreak. Molecular and biochemical biomarkers may be most useful in understanding the potential biological effects of toxic compounds when used in parallel with relevant endpoints of higher biological levels.

Adaptive removal of a known interference and its scattered energy

In underwater passive processing, the nearby fast moving loud surface ships produce nonstationary interference field and limit most sonar performance. After 9/11, AIS (automatic identify system) is required for ships larger than 60's, providing ground truth of positions, speeds, and other ancillary information for the nearby surface ships. This study investigates adaptive removal of a known loud signal using the ground truth information and acoustic propagation modeling. In addition, scattered energy away from the loud signal is identified through a delay correlation processing and is also removed. In a segment of MAPEX2k experiment conducted by SACLANT Centre off the west coast of Italy on November 28, 2000, the research vessel ALLIANCE towed an array at 2 m/s passing by a moored controlled source. The controlled source transmitted a loud 1-s 150-500 Hz LFM sequence every 15 s. In this setting, the fixed controlled source generated a nonstationary interference field received on the towed array. With the knowledge of the array tow track and source position the performance of removing the known interference and its scattered energy in a real shallow water environment is examined.