Characterizing the effect of heavy metal contamination on marine mussels using metabolomics

Marine mussels (Mytilus) are widely used as bioindicators to measure pollution in marine environments. In this study, (1)H NMR spectroscopy and multivariate statistical analyses were used to differentiate mussel groups from a heavy metal-polluted area (Onsan Bay) and a clean area (Dokdo area). Principal component analysis and orthogonal projection to latent structure-discriminant analysis revealed significant separation between extracts of mussels from Onsan Bay and from the Dokdo area. Organic osmolytes (betaine and taurine) and free amino acids (alanine, arginine, glutamine, phenylalanine, and threonine) were more highly accumulated in Onsan Bay mussels compared with Dokdo mussels. These results demonstrate that NMR-based metabolomics can be used as an efficient method for characterizing heavy metal contamination derived from polluted area compared to clean area and to identify metabolites related to environments that are contaminated with heavy metals.     

Destabilization of Aqueous Colloidal C60 Nanoparticles in the Presence of Various Organic Matter

The extractable fraction of aqueous colloidal C₆₀ nanoparticles (nC₆₀) was quantified using a liquid–liquid extraction method in the presence of five types of dissolved organic matter (DOM): Aldrich humic acid (AHA), Suwannee River fulvic acid (SFA), sodium dodecyl sulfate (SDS) micelle, liposomes composed of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC), and bovine serum albumin (BSA). The changes in toluene extractable fraction highly depended on the type and dose of DOM. Whereas an environmentally relevant concentration of AHA, 2–20 mg L^?1, was sufficient to reduce the nC₆₀ fraction easily destabilized, much higher dose of fulvic acid was needed to result in the similar degree of stabilization. A big contrast between two types of self‐organized DOM, SDS micelle and POPC liposomes, was observed. Although SDS micelle significantly decreased the toluene extractable fraction of nC₆₀ at the dose greater than its critical micelle concentration, no apparent decrease in toluene extractable fraction was found in the presence of POPC liposomes up to 3000 mg L^?1. The toluene extractable fraction of nC₆₀ in the presence of BSA rapidly decreases at lower doses then gradually decreased at higher doses. An equilibrium complexation model was proposed to quantitatively describe the decrease in the extractability of nC₆₀ in the presence of DOM. The observed decrease in the extractability of nC₆₀ was well explained by the model and the complexation of nC₆₀ with DOM was thought to occur close to 1:1 molar ratio except for BSA. The association constants of nC₆₀ with DOM were in the order of BSA, AHA, SFA, and SDS micelle, showing the differences in the affinity to nC₆₀.     

Applying conservation easement policy to river spaces to mitigate natural hazards in South Korea

Natural Hazards - The purpose of the study was to evaluate the feasibility and efficiency of conservation easements as an alternative to existing policy for mitigating natural hazards by surveying...     

Scale‐dependent controls upon the fluvial export of large wood from river catchments

The annual fluvial export of large wood (LW) was monitored by local reservoir management offices in Japan. LW export per unit watershed area was relatively high in small watersheds, peaked in intermediate watersheds, and decreased in large watersheds. To explain these variations, we surveyed the amount of LW with respect to channel morphology in 78 segments (26 segments in each size class) in the Nukabira River, northern Japan. We examined the differences in LW dynamics, including its recruitment, transport, storage, and fragmentation and decay along the spectrum of watershed sizes. We found that a large proportion of LW produced by forest dynamics and hillslope processes was retained because of the narrower valley floors and lower stream power in small watersheds. The retained LW pieces may eventually be exported during debris flows. In intermediate watersheds, the volume of LW derived from hillslopes decreased substantially with reductions in the proportion of channel length bordered by hillslope margins, which potentially deliver large quantities of LW. Because these channels have lower wood piece length to channel width ratios and higher stream power, LW pieces can be transported downstream. During transport, LW pieces are further fragmented and can be more easily transported. Therefore, the fluvial export of LW is maximized in intermediate watersheds. Rivers in large watersheds, where the recruitment of LW is limited by the decreasing hillslope margins, cannot transport LW pieces because of their low stream power, and thus LW pieces accumulate at various storage sites. Although these stored LW pieces can be refloated and transported by subsequent flood events, they may also become trapped by obstacles such as logjams and standing trees on floodplains and in secondary channels, remaining there for decades and eventually decaying into fine organic particles. Thus, the fluvial export of LW pieces is low in large watersheds. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison of ionospheric equivalent slab thickness with bottomside digisonde profile over Wuhan

A comparison of the diurnal and seasonal variations in the ionospheric equivalent slab thickness (τ) and bottomside slab thickness (B0) is presented based on the observation during high solar activities at a mid-latitude station—Wuhan (114.4°E, 30.6°N). The investigated data include foF2, hmF2, B0, B1, and TEC, and are derived from the measured ionogram and GPS receiver over Wuhan from April 1999 to March 2000. The results show that τ and B0 are highly/weakly correlated during the day/night, respectively. Furthermore, a comprehensive discussion of the relation between τ, B0, and hmF2 for geomagnetic storm events is provided in this paper.     

Determining hypocentral parameters for local earthquakes under ill conditions using genetic algorithm

We demonstrate that GA-MHYPO determines accurate hypocentral parameters for local earthquakes under ill conditions, such as limited number of stations (phase data), large azimuthal gap, and noisy data. The genetic algorithm (GA) in GA-MHYPO searches for the optimal 1-D velocity structure which provides the minimum traveltime differences between observed (true) and calculated P and S arrivals within prescribed ranges. GA-MHYPO is able to determine hypocentral parameters more accurately in many circumstances than conventional methods which rely on an a priori (and possibly incorrect) 1-D velocity model. In our synthetic tests, the accuracy of hypocentral parameters obtained by GA-MHYPO given ill conditions is improved by more than a factor of 20 for error-free data, and by a factor of five for data with errors, compared to that obtained by conventional methods such as HYPOINVERSE. In the case of error-free data, GA-MHYPO yields less than 0.1 km errors in focal depths and hypocenters without strong dependence on azimuthal coverage up to 45°. Errors are less than 1 km for data with errors of a 0.1-s standard deviation. To test the performance using real data, a well-recorded earthquake in the New Madrid seismic zone and earthquakes recorded under ill conditions in the High Himalaya are relocated by GA-MHYPO. The hypocentral parameters determined by GA-MHYPO under both good and ill conditions show similar computational results, which suggest that GA-MHYPO is robust and yields more reliable hypocentral parameters than standard methods under ill conditions for natural earthquakes.     

Effect of vehicle weight on natural frequencies of bridges measured from traffic-induced vibration

Recently, ambient vibration test (AVT) is widely used to estimate dynamic characteristics of large civil structures. Dynamic characteristics can be affected by various environmental factors such as humidity, intensity of wind, and temperature. Besides these environmental conditions, the mass of vehicles may change the measured values when traffic-induced vibration is used as a source of AVT for bridges. The effect of vehicle mass on dynamic characteristics is investigated through traffic-induced vibration tests on three bridges; (1) three-span suspension bridge (128m +404m + 128m), (2) five-span continuous steel box girder bridge (59m + 3@95m + 59m), (3) simply supported plate girder bridge (46m). Acceleration histories of each measurement location under normal traffic are recorded for 30 minutes at field. These recorded histories are divided into individual vibrations and are combined into two groups according to the level of vibration ; one by heavy vehicles such as trucks and buses and the other by light vehicles such as passenger cars. Separate processing of the two groups of signals shows that, for the middle and long-span bridges, the difference can be hardly detected, but, for the short span bridges whose mass is relatively small, the measured natural frequencies can change up to 5.4%. Supported by: the Ministry of Construction and Transportation, Korea Highway Corporation and Hyundai E&C Co. Ltd. under Project No. R&D/970003-2.     

Cloning and expression of alpha class glutathione S-transferase gene from the small hermaphroditic fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae)

In order to assess its potential as a biomarker of aquatic pollution, an alpha class glutathione S-transferase gene (GSTalpha gene) was cloned from the small hermaphroditic fish Rivulus marmoratus. The R. marmoratus GSTalpha gene spanned 1.3 kb, consisting of 6 exons encoding 221 amino acid residues. It showed high similarity to zebrafish GST. We named this R. marmoratus GSTalpha gene as rm-GSTalpha. The cDNA of the rm-GSTalpha gene was also investigated for its phylogeny, tissue-specific and chemical-induced expression. Rm-GSTalpha was subcloned into a 6 x His-tagged pCRT7 TOPO TA expression vector to produce the recombinant 6 x His-tagged rm-GST protein. This will be used in future to raise an rm-GSTalpha antibody for use in the study of phase II metabolism involved in detoxification. We also exposed R. marmoratus to 300 microg/l of 4-nonylphenol in water, and found approximately 4-fold induction of R. marmoratus GSTalpha mRNA in the treated animals. In this paper, we discuss the characteristics of the R. marmoratus GSTalpha gene as well as its potential use in relation to environmental pollution.     

Investigation of tropical Pacific upper-ocean variability using cyclostationary EOFs of assimilated data

Variability of the subsurface temperature, current, and heat content in the tropical Pacific Ocean has been extracted in association with the two dominant modes of the sea surface temperature anomaly (SSTA): the low-frequency mode and the biennial mode. In a recent paper, these two modes were identified as the major modes of El Niño-Southern Oscillation (ENSO). The low-frequency mode, which explains about 36% of the total SSTA variability, represents the dominant component of SSTA variability in the tropical Pacific, and is associated not with a fast physical evolution but with a slow stochastic undulation. The biennial mode, which is the second dominant component and explains about 12% of the total variability exhibits, on the other hand, a strong physical evolution. The space–time patterns of the subsurface variability were derived from an assimilated data set via a cyclostationary empirical orthogonal functions (CSEOF) analysis and the regression of the resulting principal component (PC) time series on the target PC time series of the surface modes. Extracted space–time patterns describe the detailed evolution of the physical changes in the upper ocean of the tropical Pacific that are associated with the corresponding surface modes. Specifically, they clearly show the surface and subsurface connection of the physical changes during ENSO events, and the role of equatorial waves in the manifestation of physical changes at the surface. The derived patterns of heat content, subsurface temperature, and zonal current anomalies realistically depict the detailed temporal changes of those variables and are consistent with our understanding of the physics in the tropical Pacific Ocean. The biennial mode appears to depict faithfully the phase progression of El Niño and La Niña. The propagation of equatorial Kelvin waves along the thermocline is clearly visible during El Niño and La Niña events in the cyclostationary representation of the physical modes in the tropical Pacific Ocean. Although the low-frequency mode explains three times more SSTA variability than the biennial mode, the former does not induce strong equatorial wave activity. This observation is significant considering that both El Niño or La Niña are often viewed simply in terms of a significant SST change in the tropical Pacific. The results of the present study indicate: (1) that the two ENSO modes represent significantly different physical evolutions; (2) that the amount of SST warming or cooling does not dictate the physical evolution of ENSO; and (3) that the two modes play essentially different dynamical roles including the generation of equatorial waves.Responsible Editor: John Wilkin