Impacts of the Nakhodka heavy-oil spill on an intertidal ecosystem: an approach to impact evaluation using geographical information system

A major heavy-oil spill from the Russian tanker Nakhodka occurred in the Sea of Japan on 2 January 1997. We investigated the impacts of this spill on a rocky intertidal ecosystem along the southern coast of the Sea of Japan. We selected Imago-Ura Cove as our study site to observe temporal changes along the oiled shore, because minimal cleaning effort was made in this area. Field surveys were conducted every autumn and spring from 1997 to 2000. We measured coverage by macroalgae in 1 x 1-m(2) quadrats and counted the animals in 5 x 5-m(2) quadrats along the intertidal zone. Changes in the ecosystem caused by the oil spill were analyzed by applying a geographical information system (GIS) to the Sea of Japan for the first time. The GIS showed that following the accident there were heavily oiled areas in sheltered regions, but these decreased over the three years. It also showed that coverage by macroalgae and the number of animals increased, although some species of algae with microscopic sporophyte generations, and some populations of perennial shellfish, remained stable or decreased during the study period. GIS was able to trace temporal changes in intertidal communities resulting from the impacts of heavy oil on flora and fauna at a spatial scale of 10-100 m. GIS is thus a practical tool for visualizing, analyzing, and monitoring changes in an ecosystem polluted by oil, taking into account topographic differences along the coastline.     

Topographically trapped waves over the continental shelf and slope

General characteristics of topographically trapped subinertia waves are discussed from the viewpoint of an eigenvalue problem and ray theory. Special attention is paid to the slope parameterS(x) (=(dh/dx)/h, wherex denotes the coordinate perpendicular to the shoreline, increasing seaward, andh(x) is the depth) which is a measure of the strength of the restoring force of the waves. Three cases for theS distribution are considered, in whichS is assumed to be positive at the coast and to tend to zero far from the coast. The first is whereS(x) decreases monotonically towards the open ocean. It is found in this case that waves are trapped near the coast. The second is whereS(x) does not decrease monotonically, but has a maximum. It is concluded that this case may contain two types of waves, i.e., those trapped near the coast and those trapped near the maximum, and the dispersion curves corresponding to different types may nearly intersect, namely, result in “kissing”. The third is whereS(x) has a negative region (corresponding to the presence of a trench). It is found in this case that an infinite sequence of waves is trapped in the negativeS region which propagate with the coast to their left (right) in the northern (southern) hemisphere besides the waves trapped near the coast. The topography in the second case corresponds to a typical continental shelf and a typical continental slope. It is shown by model calculation that trapped waves are present over the continental slope as well as over the continental shelf. Almost the same results are obtained for superinertia waves ifS is replaced by 1/h which is a measure of the restoring force of superinertia waves.     

Sm and Gd isotopic shifts of Apollo 16 and 17 drill stem samples and their implications for regolith history

The isotopic compositions of Sm and Gd in lunar regolith samples from the Apollo 16 and 17 deep drill stems showed clear isotopic shifts in ¹⁵⁰Sm /¹⁴⁹Sm (ε = +124 to +191 for A-16, and +37 to +111 for A-17) and ¹⁵⁸Gd/¹⁵⁷Gd (ε = +107 to +169 for A-16, and +31 to +84 for A-17) corresponding to neutron fluences of (5.68-9.03) × 10¹⁶ n cm⁻² for A-16 and (1.85-5.04) × 10¹⁶ n cm⁻² for A-17. The depth profiles of neutron fluences suggest that the regoliths at both sites were due to incomplete mixing of three different slabs which experienced individual two-stage irradiation before and after deposition of the upper slabs. The variations in REE compositions provide chemical evidence for incompletely vertical mixing of regoliths especially at upper layers of the two sites. The thermal neutron energy index estimated from the combination of Sm and Gd isotopic shifts, defined as ε_Sm/ε_Gd, shows a small variation (0.61-0.64) in the A-16 core except for the surface layer. On the other hand, a large variation in ε_Sm/ε_Gd = 0.67 to 0.83 in the A-17 core may result from complicated history such as two-stage irradiation and incomplete mixing during the gardening processes. Isotopic enrichments of ¹⁵²Gd and ¹⁵⁴Gd correlated with Eu/Gd elemental abundances and neutron fluences were also observed in almost all of 15 samples, showing evidence of neutron-capture from ¹⁵¹Eu and ¹⁵³Eu, respectively.     

Distribution and characteristics of landslides induced by the Iwate–Miyagi Nairiku Earthquake in 2008 in Tohoku District, Northeast Japan

The Iwate–Miyagi Nairiku Earthquake in 2008, whose seismic intensity was M. 7.2 in Japan Meteorological Agency (JMA) scale, induced innumerable landslides on the southern flank of Mt. Kurikoma volcano allocated along the Ou Backbone Range in Northeast Japan. Most landslides are detected in a hanging wall side of the seismic fault. Those landslides are classified into five types: deep-seated slide, debris slide, shallow debris slide, secondary shallow debris slide, and debris flow. Most common landslide types induced by the earthquake are shallow debris slides and subsequent debris flows. They are intensively distributed along steep gorges incising a volcanic skirt of Mt. Kurikoma, consisting of welded ignimbrite of the Pleistocene age. Debris flows are also distributed even along gentle river floors in the southern lower flank of the volcano. The area of densely distributed debris slides, shallow debris slides, and debris flows is concordant with that of severe seismic tremor. Thus, genetic processes of landslides induced by the Iwate–Miyagi Nairiku Earthquake in 2008 are attributed to multiple causative factors such as geology, topography, and seismic force.     

Dissolution of the primordial rare gases into the molten Earth's material

We have shown in a previous paper that, if the primordial solar nebula existed when the Earth was formed, the Earth was once surrounded by a dense and massive primordial atmosphere, whose temperature and pressure were about 4000 K and 900 atm, respectively, at the bottom. We suppose that this hydrogen-rich atmosphere escaped from the Earth after the solar nebula itself disappeared, both phenomena probably being due to the effect of strong solar wind and radiation.Using the results of our previous and new calculations on the structure of the primordial atmosphere, we have investigated the amount of dissolution of the rare gases, which were contained in the primordial atmosphere, into the molten Earth's material.The amount of the dissolved rare gases is found to be strongly dependent on the grain opacity of the atmosphere, i.e., on the amount of fine grains. However, their isotopic ratios and relative abundance are independent of the opacity and approximately equal to those in the primordial solar nebula, that is, to the present solar values. Especially, the dissolved neon is expected to have remained in the present mantle. Therefore, if a considerable amount of neon with nearly the solar isotopic ratio is discovered in present mantle material, this offers direct evidence for the proposition that the proto-Earth was once surrounded by the primordial atmosphere.     

Runoff and water budget of the Liudaogou Catchment at the wind–water erosion crisscross region on the Loess Plateau of China

The objectives of this study were to examine the runoff characteristics and to estimate water budget at the wind–water erosion crisscross region on the Loess Plateau of China. A small catchment known as Liudaogou that has representative meteorological and hydrological conditions of the wind–water erosion crisscross region was chosen as the study location. A numerical model for rainfall-runoff was developed and verified; rainfall-runoff calculation for 5 years (2005–2009) was performed. The observed data and numerical result of the surface runoff were used for evaluating runoff characteristics and estimating the annual water budget. Runoff rate was proportional to average intensity of rain. Even though rainfall duration was for few minutes, surface runoff was generated by intensity of more than 2.6 mm × 5 min^?1, when rainfall duration exceeded 10 h; surface runoff was generated by an intensity of 0.6 mm × 5 min^?1, while annual runoff rate was 10–15 %. The unit area of 1 km² was adopted as the index area for estimating annual water budget. Runoff, evapotranspiration, variation of water storage, and habitant water consumption accounted for 20.4, 75.6, 0, and 4 % of the total annual precipitation, respectively. Results of this study provide the basis for further research on hydrology, water resources, and sustainable water development and utilization at the wind–water erosion crisscross region on the northern Loess Plateau where annual water resources are relatively deficient.     

Numerical simulation of low-flow channel evolution due to sediment augmentation

For the conservation and restoration of river environment,a sediment replenishment technique, which conveys a part of the sediments excavated and/or dredged from reservoirs to the river below dams is developed and has been implemented tentatively in several dams.Sediments placed as replenishment can be flushed out and transported downstream by floodwater or dam releases.The flushed sediments are expected to contribute to the control of degradation and the variation of the low-flow channel.However,this technique is in the development stage because there are many unknown factors.Therefore,systematic investigations are necessary for practical management of the technique.In this study,the effects of the location of replenishment sediment on sediment flushing and on control of degradation were investigated by means of flume experiments.A two-dimensional numerical model was also developed to further investigate the effects of sediment augmentation on river restoration.The numerical model treats bank erosion and sediment transport over fixed beds. The simulation results were verified against the experimental results.The flushing process of replenishment sediment was investigated first,and then its effect as a countermeasure for river bed degradation was analyzed.Results are summarized as follows:(1) Augmentation at upper riffles is effective for flushing of replenishment sediment and variation of low-flow channel.(2) Amelioration of degradation can be found in the cases of two types of placement.The amelioration effect of upper riffle placement was larger than that of lower riffle placement(3) Aggradation rate of the bed near the replenishment site in the fixed bed is large in the lower riffle placement compared with the upper riffle placement.(4) The numerical model was found to be generally successful as a predictive tool.     

真鲷脂蛋白脂肪酶基因顺式元件PPRE及在肝脏活体调控作用

从血液提取总DNA并构建基因组文库,克隆海水鱼真鲷(Pagrosomusmajor)脂蛋白脂肪酶(LPL)基因5′侧翼区序列,再通过竞争性聚合酶链式反应(PCR)方法,定量研究饲料中添加不同饱和度脂肪酸对其肝脏LPL基因mRNA表达水平的影响。结果表明,真鲷LPL基因5′侧翼区序列中存在顺式元件过氧化物酶体增殖物反应元件,其序列为TGAAGA TGACAT,与TATA(CATAA)盒序列相隔211bp;与喂饲料对照组比较,添加10%油酸可增加真鲷肝脏LPL基因表达水平,但差异并不显著(p>0.05)。用亚油酸或n 3高不饱和脂肪酸混合物取代添加油酸的一半(占饲料添加量的5%)后,导致真鲷肝脏LPL基因表达水平升高并出现显著性变化(p<0.05)。对真鲷肝脏LPL基因诱导表达随饲料中的脂肪酸不饱和度增加而增加,表明在活体条件下脂肪酸对真鲷肝脏LPL基因表达的诱导作用可能与脂肪酸的氧化代谢有关。n 3高不饱和脂肪酸通过过氧化物酶体增殖物激活受体诱导真鲷肝脏LPL基因表达,使真鲷食物脂质供应水平与其肝脏脂肪酸氧化代谢强度调控偶联起来,可能是真鲷对高脂食物(特别是富含n 3高不饱和脂肪酸食物)的一种适应。     

Comparison of downward surface solar radiation derived from GMS5/VISSR and of reanalysis products

A high-resolution downward surface solar radiation (DSSR) dataset has been produced using geostationary meteorological satellite measurements. Its validation with in situ observations shows that the daily satellite DSSRs are highly accurate. Comparing the satellite DSSRs with reanalysis DSSR datasets, the former has higher probability density in a low value range, and lower density in a high value range. Overestimations of the reanalysis DSSR are significant in the low range. Correlations between the reanalysis DSSRs and the satellite DSSR are relatively low in the tropics. It is suggested that the satellite DSSRs have good potential to capture cloud behavior in the tropics.