Equation of state of gold and its application to the phase boundaries near 660 km depth in Earth’s mantle

The pressure-volume-temperature equation of state (EOS) of gold is fundamental to high-pressure science because of its widespread use as an internal pressure standard. In particular, the EOS of gold has been used in recent in situ multi-anvil press studies for determination of phase boundaries related to the 660-km seismic discontinuity. These studies show that the boundaries are lower by 2 GPa than expected from the depth of the 660-km discontinuity. Here we report a new P-V-T EOS of gold based on the inversion of quasi-hydrostatic compression and shock wave data using the Mie-Grüneisen relation and the Birch-Murnaghan-Debye equation. The previously poorly constrained pressure derivative of isothermal bulk modulus and the volume dependence of Grüneisen parameter (q=d lnγ/d ln V) are determined by including both phonon and electron effects implicitly: K′_0T=5.0±0.2 and q=1.0±0.1. This combined with other accurately measured parameters enables us to calculate pressure at a given volume and temperature. At 660-km depth conditions, this new EOS yields 1.0±0.2 GPa higher pressure than Anderson et al.’s EOS which has been used in the multi-anvil experiments. However, after the correction, there still exists a 1.5-GPa discrepancy between the post-spinel boundary measured by multi-anvil studies and the 660-km discontinuity. Other potential error sources, such as thermocouple emf dependence on pressure or systematic errors in spectroradiometry, should be investigated. Theoretical and experimental studies to better understand electronic and anharmonic effects in gold at high P-T are also needed.     

Geographical distribution and accumulation features of organochlorine residues in bivalves from coastal areas of South Korea

As a part of Mussel Watch Program in Korea, the contamination levels and accumulation features of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were assessed for 82 bivalve samples collected from 66 sites along the entire coast of Korea. The dry weight based ∑PCBs and ∑OCPs ranged from 4.4 ng g⁻¹ to 422.0 ng g⁻¹ (geometric MEAN=36.9 ng g⁻¹) and from 9.95 ng g⁻¹ to 131.37 (34.88) ng g⁻¹, respectively. PCB was predominant in Korean coast, followed by DDTs, HCHs, and Chlordanes. From the observed log normal distribution of PCB and each OCP, low- and high-levels were defined as geometric mean ±1 S.D., respectively. The levels at the sites near urban and/or industrial areas often exceeded the high-levels and the spatial distributions of ∑DDTs and ∑CHLs were correlated with that of ∑PCBs, indicating terrestrial input pathways. Even distribution of ∑HCHs suggested a possibility of atmospheric input pathway of HCHs. The observed isomer ratios of DDTs, HCHs, and CHLs indicated that aging has occurred.     

Assessment of tributyltin contamination in a shipyard area using a mussel transplantation approach

Mussels (Mytilus galloprovincialis) were transplanted to seven stations around a large shipyard for 126 days to evaluate tributyltin (TBT) contamination. Although the application of TBT-based paints to ships is totally banned in Korea, butyltin compounds were found to accumulate in mussels following transplantation. Concentrations of TBT and total butyltins in transplanted mussels near the shipyard were in the range of 40-350 ng Sn/g and 74-530 ng Sn/g on a dry weight basis, respectively. Obviously, low TBT concentrations (6.0-53 ng Sn/gdw) were determined in mussels at four stations outside the shipyard. A negative gradient of TBT concentrations and TBT portion to total butyltin concentrations were found in both the surface water and transplanted mussels according to distance from the shipyard. In addition, TBT concentrations in surface water and transplanted mussels showed significant correlation (r(2) = 0.71; p < 0.001). These results indicate that the shipyard still releases fresh TBT into surrounding waters even after TBT regulation in Korea, and mussel transplantation is useful in evaluating TBT contamination in shipyard area.     

The spatial distribution of surface <Emphasis Type="Italic">f</Emphasis>CO<Subscript>2</Subscript> in the Southwestern East Sea/Japan sea during summer 2005

Fugacity of CO₂ (fCO₂), temperature, salinity, nutrients, and chlorophyll-a were measured in the surface waters of southwestern East Sea/Japan Sea in July 2005. Surface waters were divided into three waters based on hydrographic characteristics: the water with moderate sea surface temperature (SST) and high sea surface salinity (SSS) located east of the front (East water); the water with high SST and moderate SSS located west of the front (West water); and the water with low SST and SSS located in the middle part of the study area (Middle water). High fCO₂ larger than 420 μatm were found in the West water. In the Middle water, CO₂ was undersaturated with respect to the atmosphere, with values between 246 and 380 μatm. Moderate fCO₂ values ranging from 370 to 420 μatm were observed in the East water. For the East and West waters, estimates of temperature dependency of fCO₂ (12.6 and 15.1 μatm °C⁻¹, respectively) were rather similar to a theoretical value, indicating that SST is likely to be a major factor controlling the surface fCO₂ distribution in these two regions. In the Middle water, however, the estimated temperature dependence was somewhat lower than the theoretical value, and relatively high concentrations of surface chlorophyll-a coincided with the low surface fCO₂, implying that biological uptake may considerably affect the fCO₂ distribution. The net sea-to-air CO₂ flux of the study area was estimated to be 0.30±4.81 mmol m⁻² day⁻¹ in summer, 2005.     

Effects of CO2-induced ocean acidification on the growth of the larval olive flounder Paralichthys olivaceus

It widely thought that ocean acidification processes that caused by atmospheric CO₂ increase and accordingly lower seawater pH conditions might cause serious harm to marine food webs in certain ecosystems in the near future. Little is known about how marine fishes respond to reduced pH conditions. We investigated the effects of CO₂ conditions on the growth of olive flounder (Paralichthys olivaceus) larvae. Newly hatched larvae were reared at three different levels of pCO₂ (574, 988 and 1297 µatm) in temperature-controlled (21 ± 0.5°C) water tanks for four weeks until metamorphosis. The experiment was repeated three times in May, June, and July 2011, and body lengths and weights were measured at the completion of each experiment. The results indicated that the body length and weight of flounder larvae significantly increased with increasing CO₂ concentrations (P < 0.05). A higher daily growth rate during the early larval stage (hatching to 14 days) was found among the larvae reared in low pCO₂ conditions, while a significantly lower growth rate was found among larvae in higher pCO₂ water conditions. On the other hand, in the late larval stage (18 days after hatching to metamorphosis), the daily growth rate of larvae was much higher in high CO₂ water. Bone density of larvae, however, decreased with increasing CO₂ concentration in the water

     

Sources of plastic marine debris on beaches of Korea: More from the ocean than the land

Reduction of marine debris requires knowledge of its sources. Sources of plastic marine debris found on six beaches of Korea were estimated. Samples larger than 25 mm were collected from 10 quadrats of 5 × 5 m for each beach in spring 2013. The total 752 items (12,255 g) of debris comprised fiber and fabric (415 items, 6,909 g), hard plastic (120 items, 4,316 g), styrofoam (93 items, 306 g), film (83 items, 464 g), foamed plastic other than styrofoam (21 items, 56 g), and other polymer (20 items, 204 g). With the probable sources allocated to each of 55 debris types, the source of 56% of all the collected debris appeared to be oceanbased and 44% was land-based. Priorities of policy measures to reduce marine debris should be different from regions to regions as the main sources of debris may differ.     

Impacts of marine debris on wild animals in the coastal area of Korea

Over the last decade, marine debris has become a major factor affecting the coastal ecosystem of Korea. This study compiled information regarding how marine debris impacts wildlife in Korea. Cases of marine debris impacting wildlife were collected from experts of various fields and from local participants through an open access website from February 2010 to March 2012. A total of 21 species were affected by marine debris: 18 species of birds, 2 species of mammals, and 1 species of crustacean. Five threatened or protected species were identified: black-faced spoonbill, finless porpoise, water deer, whooper swan, and greater painted snipe. Recreational fishing gears were the types of debris that most frequently impacted wildlife, especially birds. Black tailed gulls were the most vulnerable species to recreational fishing hooks and lines. Although it was preliminary, this study revealed that recreational fishing activities should be prioritized when managing marine debris in Korea.     

Geotechnogenesis problems

Geotechgjgensis is mineralogical geochemical transformation of minerals, rocks, and ores as consequence of impact on them in the process of performing geological-exploration and irrigation works, extracting and processing mineral resources, constructing transport, civil and military objects. These effects lead to discontinuity and moving different scale fragments ofuppor part of lithospere and conjugate hydro-and biosphere zones. Discontinuity predttermines the disturbance of matural systems dynamic equilibriu and acceleration of mftter transformation and migration processes. The final aim of studying geotechnogenesis minseralogy and geochemistry is the establishment of scientific foundations for developing ecological safety measures including also utilization fo geotechnogene deposits.