Enhanced photobiological H2 production by the addition of carbon monoxide and hydrogen cyanide in two unicellular N2-fixing cyanobacterial strains isolated from Korean coasts

Photobiological H₂ from marine cyanobacterial strains is widely accepted to be an ideal clean and renewable energy source. Using the two Korean N₂-fixing unicellular cyanobacterial strains (Cyanothece sp. KNU CB MAL-031 and Cyanothece sp. KNU CB MAL-058) and the Synechococcus sp. Miami strain BG043511 we performed flask-scale experiments to measure the effect of CO and HCN addition on photobiological H₂ production. For the test, 1, 5, 10 and 30% v/v of CO in the N₂ atmosphere was applied. Enhancement of H₂ production was remarkable at 1–5% concentration range of CO addition. At CO concentrations over 5% no further cost-effective enhancement of H₂ production was detectable, which suggests to us that 1–5% CO addition should be adopted for practical photobiological H₂ production by the cyanobacterial strains. Maximum enhancement of the photobiological H₂ production by CO additions was 2–6 times over the control flasks without CO. When 3 ppm of HCN was injected into the cell suspension of BG043511, the enhancement of hydrogen production was 50–60% of that under 5% CO. Present result implies the possible recycling of waste CO and HCN for the enhancement of the photobiological H₂ production using marine cyanobacterial strains.     

Germination rate of Phyllospadix japonicus seeds relative to storage methods and periods

To determine the optimal storage method and longest possible storage period of Phyllospadix japonicus seeds, we examined post-storage germination rates using different storage methods and periods for P. japonicus seeds harvested in Korean coastal waters. P. japonicus seeds are classified as recalcitrant seeds with an average moisture content of 45.4%. Germination rates of P. japonicus seeds stored in seawater at 4 °C, seawater at room temperature with air supply, and an aquarium with continuous seawater circulation ranged from 35.0% to 43.5%, whereas seeds stored in seawater at 30°C, a refrigerator at ?20°C, and a desiccator at room temperature did not germinate. Seeds stored at 4°C maintained germination rates of 72.5～73.0% until 30 days of storage, but showed rapidly decreasing germination rates after 60 days and no germination after 180 days. Since few studies have investigated seed storage of P. japonicus, these results will serve as useful data for seed-based P. japonicus habitat restoration.     

A projection of extreme climate events in the 21st century over east Asia using the community climate system model 3

A series of coupled atmosphere-ocean-land global climate model (GCM) simulations using the National Center for Atmospheric Research (NCAR) Community Climate System Model 3 (CCSM3) has been performed for the period 1870–2099 at a T85 horizontal resolution following the GCM experimental design suggested in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). First, a hindcast was performed using the atmospheric concentrations of three greenhouse gases (CO₂, CH₄, N₂O) specified annually and globally on the basis of observations for the period 1870–1999. The hindcast results were compared with observations to evaluate the GCM’s reliability in future climate simulations. Second, climate projections for a 100-year period (2000–2099) were made using six scenarios of the atmospheric concentrations of the three greenhouse gases according to the A1FI, A1T, A1B, A2, B1, and B2 emission profiles of the Special Report on Emissions Scenarios. The present CCSM simulations are found to be consistent with IPCC’s AR4 results in the temporal and spatial distributions for both the present-day and future periods. The GCM results were used to examine the changes in extreme temperatures and precipitation in East Asia and Korea. The extreme temperatures were categorized into warm and cold events: the former includes tropical nights, warm days, and heat waves during summer (June–July–August) and the latter includes frost days, cold days, and cold surges during winter (December–January–February). Focusing on Korea, the results predict more frequent heat waves in response to future emissions: the projected percentage changes between the present day and the late 2090s range from 294% to 583% depending on the emission scenario. The projected global warming is predicted to decrease the frequency of cold extreme events; however, the projected changes in cold surge frequency are not statistically significant. Whereas the number of cold surges in the A1FI emission profile decreases from the present-day value by up to 24%, the decrease in the B1 scenario is less than 1%. The frequency and intensity of extreme precipitation events year-round were examined. Both the frequency and the intensity of these events are predicted to increase in the region around Korea. The present results will be helpful for establishing an adaptation strategy for possible climate change nationwide, especially extreme climate events, associated with global warming.     

Biomarker responses in pelagic and benthic fish over 1 year following the Hebei Spirit oil spill (Taean, Korea)

After the Hebei Spirit oil spill incident (7th December, 2007) in the west coast of Korea, contamination of biliary PAH metabolite and hepatic biomarkers in a pelagic and a benthic fish was monitored for 1 year. Concentrations of 16 PAHs and alkylated PAHs in fish muscle were highest (22.0 ng/g d.w. for 16 PAHs and 284 ng/g d.w. for alkylated PAHs) at 5 days after the spill and then decreased rapidly to background levels at 11 months after the spill. Fish from the oiled site had elevated biliary PAH metabolite concentrations immediately after the spill; these declined steadily in both species, but were still above reference site concentrations 2 months after the spill. Oiled-site fish showed hepatic CYP 1A induction whose trend closely followed those of biliary PAH metabolite concentrations, implying continuous exposure to PAHs. Brain acetylcholinesterase activity was not related to oil exposure.     

Long-term temporal trends (1992-2008) of imposex status associated with organotin contamination in the dogwhelk Nucella lapillus along the Icelandic coast

Using the dogwhelk Nucella lapillus as a biomonitor, we evaluated the organotin contamination along the Icelandic coast over nearly two decades. In 2008, adult dogwhelks collected from 30 locations were examined for imposex status. In 2009, tissue concentrations of six organotin species in dogwhelks from 16 of the 30 locations were analysed using gas chromatography-mass spectrometry. Tributyltin was the most predominant residue ranging from 2.07 to 70.38 μg kg(-1) dw, while triphenyltin was also detected at concentrations up to 22.79 μg kg(-1) dw. Higher total organotin concentrations and imposex indices were observed at locations near large harbours (Reykjavík and Hafnarfj?reur). By comparing the current imposex results with those of previous surveys (1992-2003), we found that recovery was slow near the large harbours, but more apparent near the smaller harbours. We also observed a notable increase in imposex at several northwest sites implying incessant input of organotins.     

Sea urchin development in a global change hotspot, potential for southerly migration of thermotolerant propagules

The distribution of the sea urchin Heliocidaris erythrogramma coincides with the southeast Australia global change hot spot where marine ecosystems are warming significantly due to changes in ocean circulation. To address questions on future vulnerabilities, the thermotolerance of the planktonic life phase of H. erythrogramma was investigated in the climate and regionally relevant setting of projected near-future (2100) ocean warming. Experimental treatments ranged from 18 to 26 °C, with 26 °C representing +3-4 °C above recent ambient sea-surface temperatures. Developmental success across all stages (gastrula, 24 h; larva, 72 h; juvenile, 120 h) decreased with increasing temperature. Development was tolerant to a +1-2 °C increase above ambient, but significant deleterious effects were evident at +3-4 °C. However, larvae that developed through the early bottleneck of normal development at 26 °C metamorphosed successfully. The inverse relationship between temperature and planktonic larval duration (PLD) was seen in a 25% decrease in the PLD of H. erythrogramma at 24 and 26^oC. Ocean warming may be advantageous to a subset of larvae through early settlement and reduction of the vulnerable planktonic period. This positive effect of temperature may help buffer the negative effects of ocean warming. In parallel studies with progeny derived from northern (Coffs Harbour) and southern (Sydney) H. erythrogramma, northern embryos had significantly higher thermotolerance. This provides the possibility that H. erythrogramma populations might keep up with a warming world through poleward migration of thermotolerant propagules, facilitated by the strong southward flow of the East Australian Current. It is uncertain whether H. erythrogramma populations at the northern range of this species, with no source of immigrants, will have the capacity to persist in a warm ocean. Due to its extensive latitudinal distribution, its potential developmental thermotolerance and independence of its lecithotrophic larvae from exogenous food and the need to make a functional skeleton, H. erythrogramma may be particularly robust to ocean change.     

Fragmentation and heating of streamers in orion

Long filamentary structures composed of chains of denser clumps fan out from the high mass star-forming KL core region in OMC-1. We present a high resolution VLA NH₃ study of the structure, kinematics, and temperature of the region over a large, multi-field scale. The region appears to contain multiple superimposed cloud components. Clumps along the filaments may be the result of instabilities and fragmentation; some show fast velocity gradients. Sheaths around the clumps along the filaments are heated. This is possibly the result of external radiation or of interaction with high velocity outflows from young stellar objects in OMC-1.     

Is the Parker Instability a Viable Mechanism for the Formation of Giant Molecular Clouds?

The stratified interstellar medium has been known to be subject to the Parker instability, and the instability has been considered as a plausible mechanism for the formation of giant molecular clouds (GMCs). By presenting our recent efforts to understand the instability through linear analyses and numerical simulations, we raise a negative point of view that the Parker instability alone could not form GMCs.     

Volcanic hazard assessment incorporating expert knowledge: Application to the yucca mountain region, Nevada, USA

Multiple-expert hazard/risk assessments have considerable precedent, particularly in the Yucca Mountain site characterization studies. A certain amount of expert knowledge is needed to interpret the geological data used in a probabilistic data analysis. As may be the situation in science, experts disagree on crucial points. Consequently, lack of consensus in some studies is a sure outcome. In this paper, we present a Bayesian approach to statistical modeling in volcanic hazard assessment for the Yucca Mountain site. Specifically, we show that the expert opinion on the site disruption parameterp is incorporated into the prior distribution, π(p), based on geological information that is available. Moreover, π(p) can combine all available geological information motivated by conflicting but realistic arguments (e.g., simulation, cluster analysis, structural control, ..., etc.). The incorporated uncertainties about the probability of repository disruptionp eventually will be averaged out by taking the expectation over π(p). We use the following priors in the analysis: (1) priors selected for mathematical convenience: Beta (r,s) for (r,s) = (2, 2), (3, 3), (5, 5), (2, 1),(2, 8), (8, 2), and (1, 1);and (2) three priors motivated by expert knowledge. Sensitivity analysis is performed for each prior distribution. Our study concludes that estimated values of hazard based on the priors selected for mathematical simplicity are uniformly higher than those obtained based on the priors motivated by expert knowledge. And, the model using the prior, Beta (8, 2), yields the highest hazard (=2.97 × 10^-2 . The minimum hazard is produced by the “three-expert prior” (i.e., values of p are equally likely for p = 10^-3, 10^-2,and 10^-1 . The estimate of the hazard is 1.39 × 10^-3, which is only about one order of magnitude smaller than the maximum value. The term, “hazard, ” is defined as the probability of at least one disruption of a repository at the Yucca Mountain site by basaltic volcanism for the next 10,000 years.