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51.
Geotechnical evaluation of slope and ground failures during the 8 October 2005 Muzaffarabad earthquake, Pakistan 总被引:4,自引:0,他引:4
A large devastating earthquake with a magnitude of 7.6 struck in Kashmir on Oct. 8, 2005. The largest city influenced by the
earthquake was Muzaffarabad. Balakot town was the nearest settlement to the epicenter, and it was the most heavily damaged.
The earthquake caused extensive damage to housing and structures founded on loose deposits or weathered/sheared rock masses.
Furthermore, extensive slope failures occurred along Neelum and Jhelum valleys, which obstructed both river flow and roadways.
In this article, failures of natural and cut slopes as well as other ground failures induced by the earthquake and their geotechnical
evaluation are presented, and their implications on civil infrastructures and site selection for reconstruction and rehabilitation
are discussed. It is suggested that if housing and constructions on soil slopes containing boulders as observed in Balakot
and Muzaffarabad are allowed, there should be a safety zone between the slope crest and allowable construction boundary. 相似文献
52.
Tributyltin oxide (TBTO) has been used worldwide in marine antifouling paints as a biocide for some time. However, it produced toxic effects, especially in marine water/sediment ecosystems. Consequently, its use in antifouling paints has been prohibited in many countries. In this study, the toxicity of alternative and/or new antifouling biocides compared with TBTO is assessed by a biological method. The effects of these chemicals on marine species have not been well studied. This paper assesses, comparatively, the effects of eight biocides on sea urchin eggs and embryos. The chemicals assessed were TBTO, Irgarol 1051, M1 (the persistent degradation product of Irgarol), Diuron, zinc pyrithione, 'KH101', 'Sea-Nine 211', and copper pyrithione. For these chemicals, toxicity appears to be in the order zinc pyrithione > Sea-Nine 211 > KH101 > copper pyrithione > TBTO > Diuron approximately = Irgarol 1051 > M1. Here, we show that zinc pyrithione, Sea-Nine 211, KH101, and copper pyrithione are much more toxic to sea urchins than TBTO or the other chemicals. 相似文献
53.
Minoru Fujii Shinichiro Murashige Yuka Ohnishi Atushi Yuzawa Hitoshi Miyasaka Yoshimi Suzuki Hiroshi Komiyama 《Journal of Oceanography》2002,58(3):438-443
Decomposition experiments were conducted on cultured phytoplankton (Skeletonema costatum) in seawater containing decomposer and consumer of size less than 500 μm. We determined the decomposition rates of bulk particulate
organic matter (POM), the ratio of labile to semi-refractory fractions in the POM, and the POM carbon/ nitrogen (C/N) ratio
during decomposition. To identify the kinetic mechanisms involved in the reactions of different order (e.g., first- and second-order),
we studied the sensitivity of reaction rates to the initial concentration of POM, ranging from 2.4 to 71 mg-C L−1. The results showed that decomposition consists of two first-order reactions: decomposition of labile and of semi-refractory
particulate organic carbon (POC). The decomposition rate constants found for labile (0.13 day−1 at 20°C), and semi-refractory POC (0.008 day−1 at 20°C), and the carbon weight ratio of semi-refractory POC (13% at 20°C), were insensitive to the initial organic matter
concentration. The time-dependence of the C/N ratio was also independent of this initial concentration. The decomposition
rate constants and the content of semi-refractory POC did not change, regardless of the absence or presence of 25–500 μm organisms
in natural seawater.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
54.
Zhanghua?WangEmail author Zhongyuan?Chen Kazumaro?Okamura Jianhua?Gao Kaiqin?Xu Hiroshi?Koshikawa Masataka?Watanabe 《Geo-Marine Letters》2004,24(4):252-258
A hydrographic-sedimentological investigation was conducted in May 2001, aimed at assessing dynamic sedimentation patterns near and off the Changjiang River mouth, East China Sea. Current speed/direction, suspended sediment concentration (SSC), and turbidity were measured at eight nearshore and offshore sites, spanning a distance of ca. 150 km. The results identified a high-speed current ranging from 0.9 to 1.6 m/s at lower low water in the front of the turbidity maximum zone. This anomalous current, lasting about 4 h, was the fastest recorded over two semi-diurnal tidal cycles. Simultaneous measurements showed a high SSC (0.5 g/l) and high turbidity (>230 ppm) near the seafloor. This phenomenon would help explain periodic enhancement of sediment resuspension in the area, and an associated southward transport route from the Changjiang River mouth. 相似文献
55.
Jorge Salgado Carl D. Sayer Stephen J. Brooks Thomas A. Davidson Beth Okamura 《Journal of Paleolimnology》2018,60(2):311-328
Aquatic biodiversity is commonly linked with environmental variation in lake networks, but less is known about how local factors may influence within-lake biological heterogeneity. Using a combined ecological and multi-proxy palaeoecological approach we investigated long-term changes in the pathways and processes that underlie eutrophication and water depth effects on lake macrophyte and invertebrate communities across three basins in a shallow lake—Castle Lough, Northern Ireland, UK. Contemporary data allow us to assess how macrophyte assemblages vary in composition and heterogeneity according to basin-specific factors (e.g. variation in water depth), while palaeoecological data (macrophytes and co-occurring invertebrates) enable us to infer basin-specific impacts and susceptibilities to nutrient-enrichment. Results indicate that variability in water depth promotes assemblage variation amongst the lake basins, stimulating within-lake macrophyte assemblage heterogeneity and hence higher lake biodiversity. The palaeo-data indicate that eutrophication has acted as a strong homogenising agent of macrophyte and invertebrate diversities and abundances over time at the whole-lake scale. This novel finding strongly suggests that, as eutrophication advances, the influence of water depth on community heterogeneity is gradually eroded and that ultimately a limited set of eutrophication-tolerant species will become homogeneously distributed across the entire lake. 相似文献
56.
Satoru Kojima Tamotsu Nozaki Hidehisa Nagata Ryota Tanahashi Ryoich Kondo Noriaki Okamura Kazuhiro Suzuki Akiko Ikeda Toshio Nakamura Tomoyuki Ohtani 《Environmental Earth Sciences》2014,71(6):2753-2763
Large-scale landslides along the Kubusu and Besso rivers in Toyama Prefecture are developed in the Miocene Iwaine Formation, which is composed of andesitic lava, tuff, and tuff breccia. In the middle member of this formation, the tuff is easily altered to montmorillonite-bearing rock, and subsequently plays an important role in the development of landslides events, which tend to be large-scale events, as the massive lava of the upper member forms a cap rock over the tuff. The Kiritani and Koinami basins, which are flat intermontane basins located along the Kubusu and Besso rivers, respectively, are interpreted as landslide-dammed lakes, later filled with sediment. Accelerator mass spectrometry 14C ages show that the landslides forming each dam occurred simultaneously, at approximately 2500 BP. These ages were measured from wood fragments embedded in the landslide material of Kiritani, and from an in situ stump drowned during the impoundment of Koinami. If the trigger of these landslides was an earthquake, it is most likely to have been the penultimate event along the Atotsugawa fault zone. 相似文献
57.
Three marine sediment cores from Osaka Bay were analyzed for 210Pb geochronology, heavy metal concentrations (Zn, Cu, and Pb) and stable lead isotope ratios (206Pb/207Pb) in order to reconstruct high-resolution heavy metal pollution history from 1900–2006. Anthropogenic metal accumulation in sediments peaked in 1970 in agreement with the high economic growth period in Japan. The comparison of temporal patterns of 206Pb/207Pb ratio with other areas of Japan suggested that the heavy metals, imported from several different countries during the periods of economic growth (1955 to 1973), are the main pollution source for the country. For the period 1970–2006, the sediment data reflect the result of stricter environmental regulations applied after the late 1960s. However, heavy metal concentrations in the surface sediments are still elevated to levels several times higher than the levels at the bottoms of the cores. Additionally, the lead isotope ratio does not show significant change after the 1980s. Secondary heavy metal pollution through the mixing of deeper polluted sediment appears to be the likely reason for the deterioration of present time submarine sediment environments. In conclusion, this study has demonstrated that it is difficult to recover over a period of several years the benthic quality of a bay, once it is heavily polluted. 相似文献
58.
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60.
Akira Nagano Kazuyuki Uehara Toshio Suga Yoshimi Kawai Hiroshi Ichikawa Meghan F. Cronin 《Journal of Oceanography》2014,70(4):389-403
Hydrographic data in the Kuroshio Extension (KE) region from 2008 to 2010 show large year-to-year variability in near-surface salinity, including a very large anomalous event in February 2010. During this event, the deep winter mixed layer in the southern KE region had higher salinity than had existed during the previous summer in September 2009. Our analysis shows that advection from the Philippine Sea along the western branch of the North Pacific subtropical gyre, taking approximately 9 months, resulted in this large salinity anomaly in February 2010 and contributes to the interannual salinity variability in the southern KE region. 相似文献