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1.
Lallan Prasad Gupta Hodaka Kawahata Mio Ltakeuchi Hidekazu Ohta Yoshiro Ono 《Resource Geology》2006,56(2):191-196
Abstract. Oxidation and reduction processes can influence extent of leaching of elements from solid waste. Three samples of municipal solid waste combustion fly ash were subjected to oxidizing and reducing conditions in order to evaluate leaching of elements in the Milli-Q water and fly ash (liquid to solid ratio, 100) mixtures. Although the oxidizing and reducing conditions were applied for 6 hours only, elements like Cs, Li, Mg, Sb, Tl and V leached more under oxidizing condition than under reducing condition in the case of all three ash samples. Cadmium, Pb and Zn leached more from all samples under reducing condition than under oxidizing condition. Leaching of other elements like Al, Ba, Cr, Cu, Ni and Rb was inconsistent with oxidizing or reducing conditions and varied from sample to sample, suggesting that factors other than redox may be more important in controlling leaching of these elements. Strong acid neutralization capacity of the fly ash samples let the pH vary within a narrow range, and thus severely limited the extent of leaching during the course of the experiment. Lead and Zn were the most sensitive while K and Na were the least sensitive to changes in redox conditions. 相似文献
2.
Lallan Prasad Gupta Hodaka Kawahata Mio Takeuchi Hidekazu Ohta Yoshiro Ono 《Resource Geology》2005,55(4):357-372
Abstract. Municipal solid waste combustion leads to concentration of various metals in the solid residue (fly ash) remaining after combustion. These metals pose serious environmental hazard and require proper handling and monitoring in order to control their harmful effects. Leachability of some metals from fly ash was examined in fly ash and Milli-Q water mixture (liquid-to-solid ratio, 100) under various temperature and pH conditions in the laboratory. The leaching experiments conducted for 24 hours showed that pH was generally more important than temperature in controlling the amount of metals leached out of the fly ash. However, at a given pH, rise in temperature led to different degree of (usually one to two fold) enhanced or reduced leaching of metals. Owing to amphoteric nature of oxides of Al, Cr, Pb and Zn, these metals often yielded typical pattern of increase and decrease in their concentrations with change in pH. The extent of leaching of Cr and Pb in our experiments suggests that decrease of pH to acidic range in the case of Pb and to neutral to acidic range for Cr over a long period of storage of fly ash at solid waste dumping site may facilitate leaching of these metals from fly ash, leading to contamination of groundwater to the level that exceeds beyond the level permitted by the environmental laws. 相似文献
3.
Zhao-Jun?LiuEmail authorView authors OrcID profile Shoshiro?Minobe Yoshi?N.?Sasaki Mio?Terada 《Journal of Oceanography》2016,72(6):905-922
The future regional sea level (RSL) rise in the western North Pacific is investigated by dynamical downscaling with the Regional Ocean Modeling System (ROMS) with an eddy-permitting resolution based on three global climate models—MIROC-ESM, CSIRO-Mk3.6.0, and GFDL-CM3—under the highest greenhouse-gas emission scenario. The historical run is forced by the air-sea fluxes calculated from Coordinated Ocean Reference Experiment version 2 (COREv2) data. Three future runs—ROMS-MIROC, ROMS-CSIRO, and ROMS-GFDL—are forced with an atmospheric field constructed by adding the difference between the climate model parameters for the twenty-first and twentieth century to fields in the historical run. In all downscaling, the RSL rise along the eastern coast of Japan is generally half or less of the RSL rise maxima off the eastern coast. The projected regional (total) sea level rises along the Honshu coast during 2081–2100 relative to 1981–2000 are 19–25 (98–104), 6–15 (71–80), and 8–14 (80–86) cm in ROMS-MIROC, ROMS-CSIRO, and ROMS-GFDL, respectively. The discrepancies of the RSL rise along the Honshu coast between the climate models and downscaling are less than 10 cm. The RSL changes in the Kuroshio Extension (KE) region in all downscaling simulations are related to the changes of KE (northward shift or intensification) with climate change. 相似文献
4.
Ryo Sugimoto Akihide Kasai Toshihiro Miyajima Kouichi Fujita 《Journal of Oceanography》2008,64(1):39-48
Temporal changes in nitrogen isotopic composition (δ15N) of the NO3
− pool in the water column below the pycnocline in Ise Bay, Japan were investigated to evaluate the effect of nitrification
on the change in the δ15N in the water column. The δ15N of NO3
− in the lower layers varied from −8.5‰ in May to +8.4‰ in July in response to the development of seasonal hypoxia and conversion
from NH4
+ to NO3
−. The significantly 15N-depleted NO3
− in May most likely arose from nitrification in the water column. The calculated apparent isotopic discrimination for water
column nitrification (ɛnit = δ15Nsubstrate − δ15Nproduct) was 24.5‰, which lies within the range of previous laboratory-based estimates. Though prominent deficits of NO3
− from hypoxic bottom waters due to denitrification were revealed in July, the isotopic discrimination of denitrification in
the sediments was low (ɛdenit = ∼1‰). δ15NNO3 in the hypoxic lower layer mainly reflects the isotopic effect of water column nitrification, given that water column nitrification
is not directly linked with sedimentary denitrification and the effect of sedimentary denitrification on the change in δ15NNO3 is relatively small. 相似文献
5.
Sachiko Oguma Tsuneo Ono Akira Kusaka Hiromi Kasai Yasuhiro Kawasaki Tomonori Azumaya 《Journal of Oceanography》2008,64(4):525-539
In this study we used two stable isotopes, δ13C and δ18O, for water mass classification in the coastal region off eastern Hokkaido. δ13C* values, which were corrected for the biological effect, and δ
18O values up to 300 m depth suggested that the isotopic character of the onshore and offshore water in the southern Okhotsk
Sea, the Nemuro Strait and the western North Pacific could be explained by the mixing of three source waters: the Oyashio
water (OYW), Soya Warm Current water (SWCW) and East Sakhalin Current water (ESCW). In summer, δ
13C*-δ
18O plots indicated mixing between SWCW from the southern Okhotsk Sea and OYW in the Pacific coast of southeastern Hokkaido,
while temperature-salinity plots of the onshore water showed minimal difference from the offshore OYW. In winter, on the other
hand, the mixed water of ESCW and OYW (or SWCW) appeared in the Pacific coastal region, distributed as cold, low salinity
onshore water. Finally, we estimated mixing ratios of OYW, SWCW and ESCW in the coastal region of western North Pacific using
their mean values of δ
13C* and δ
18O as endmembers. These results suggest seasonal and yearly changes of water mass combination en route from the southern Okhotsk
Sea to the western North Pacific. 相似文献
6.
In order to examine the applicability of remotely-sensed ocean color for the estimation of phytoplankton biomass and primary
production in the Oyashio region, the western subarctic Pacific, vertical distributions of chlorophylla concentration and primary production were observed in April and May 1997. Spring bloom was observed in both April and May,
and the surface concentration of chlorophylla exceeded 40 mg m−3. The relationship between the standing stocks of chlorophylla within the layer from the sea surface to one optical depth (0–1/k layer) and the surface chlorophylla concentration is expressed as a Michaelis-Menten equation. The mean ratio of the standing stock of chlorophylla in the euphotic layer to that in the 0–1/k layer was 4.41, this ratio did not significantly differ from 4.61 which was obtained at homogeneous distribution of chlorophylla within the euphotic layer. These facts suggest that the distribution of chlorophylla could be assumed to be homogeneous in the euphotic layer during the spring bloom. Results of primary production measurements
by simulatedin situ method were compared with those by an algorithm with two variables; chlorphylla and non-spectral PAR. Daily primary production in the euphotic layer estimated by the algorithm varied in a range of 38–274%
of that estimated by incubation, although the primary productions by the algorithm agreed with those by the incubation at
a half of stations. Primary production within the euphotic layer calculated using simply the surface data was the same as
that estimated using vertical distribution of chlorophylla. These results show that the primary production in the euphotic layer may be estimated from the remote sensed measurements
during the spring bloom in the Oyashio region. 相似文献
7.
Although much is known about overall sediment delivery ratios for catchments as components of sediment production and sediment yield, little is known about the component of temporary sediment storage. Sediment delivery ratios focused on the influence of storm-related sediment storage are measured at Matakonekone and Oil Springs tributaries of the Waipaoa River basin, east coast of New Zealand. The terrace deposits of both tributaries show abundant evidence of storm-related sedimentation, especially sediment delivered from Cyclone Bola, a 50 year return rainfall event which occurred in 1988. The sediment delivery ratio is calculated by dividing the volume of sediment transported from a tributary to the main stream by the volume of sediment generated at erosion sites in the tributary catchment. Because the sediment delivery volume is unknown, it can be calculated as the difference between sediment generation volume and sediment storage volume in the channel reach of the tributary. The volume of sediment generated from erosion sites in each tributary catchment was calculated from measurements made on aerial photographs dating from 1960 (1:44 000) and 1988 (1:27 000). The volume of sediment stored in the tributary can be calculated from measurements of cross-sections located along the tributary channel, which are accompanied by terrace deposits dated by counting annual growth rings of trees on terrace surfaces. Sediment delivery ratios are 0·93 for both Matakonekone catchment and Oil Springs catchment. Results indicate that Oil Springs catchment has contributed more than twice the volume of sediment to the Waipaoa River than the Matakonekone catchment (2·75 × 106 m3 vs 1·22 × 106 m3). Although large volumes of sediment are initially deposited during floods, subsequent smaller flows scour away much of these deposits. The sediment scouring rate from storage is 1·25 × 104 m3 a−1 for Matakonekone stream and 0·83 × 104 m3 a−1 for Oil Springs stream. Matakonekone and Oil Springs channels respond to extreme storms by instantaneously aggrading, then gradually excavating the temporarily stored sediment. Results from Matakonekone and Oil Springs streams suggest a mechanism by which event recurrence interval can strongly influence the magnitude of a geomorphic change. Matakonekone stream with its higher stream power is expected to excavate sediment deposits more rapidly and allow more rapid re-establishment of storage capacity. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
8.
A series of shake-table tests was conducted by inserting and replacing 4 different types of dampers, or by removing them in a full-scale 5-story steel frame building. The objective is to validate response-control technologies that are increasingly adopted for major Japanese buildings without being attested to-date by a major earthquake. Test results are briefly described, and good performance of the dampers and frame demonstrated. The concepts of the full-scale building tests and various contributions are discussed. The difficulty associated with full-scale dynamic testing is explained. 相似文献
9.
Keita W. Suzuki Akihide Kasai Kouji Nakayama Masaru Tanaka 《Journal of Oceanography》2012,68(3):453-471
The inner part of the Ariake Sea is one of the most productive estuarine systems in Japan. To examine potential food items for estuarine organisms, we conducted monthly observations of the dynamics of particulate organic matter along the macrotidal Chikugo River estuary in 2005 and 2006. In the neighboring macrotidal Midori and Kuma River estuaries, comparative observations were made. High turbidity and strong vertical mixing were observed only at low salinities (<10) in the Chikugo River estuary. In contrast, the Midori and Kuma River estuaries were characterized by less turbid and less mixed waters. Concentrations of particulate organic carbon often exceeded 5?mg?l?1 in or close to the estuarine turbidity maximum (ETM) of the Chikugo River estuary. However, such high concentrations were rarely observed in the other two estuaries. The observed differences could be attributable to different hydrodynamic processes related to the different lengths of tidal reaches: 23, 8, and 6?km in the Chikugo, Midori, and Kuma Rivers, respectively. In the Chikugo River estuary, spatiotemporal changes of chlorophyll a suggested that phytoplankton occurred abundantly up- and/or downstream from the ETM especially during the warm season. In contrast, pheophytin (i.e., plant detritus) always accumulated in or close to the ETM. Carbon stable isotope ratios and carbon to nitrogen ratios indicated that the plant detritus was derived from phytoplankton and terrestrial plants. The Chikugo River estuary has a high potential to support the production of estuarine organisms through abundant plant detritus in the well-developed ETM all the year round. 相似文献
10.
Transport of oceanic nitrate from the continental shelf to the coastal basin in relation to the path of the Kuroshio 总被引:1,自引:0,他引:1
Ryo Sugimoto Akihide Kasai Toshihiro Miyajima Kouichi Fujita 《Continental Shelf Research》2009,29(14):1678-1688
Hydrographic and biogeochemical observations were conducted along the longitudinal section from Ise Bay to the continental margin (southern coast of Japan) to investigate changes according to the Kuroshio path variations during the summer. The strength of the uplift of the cold deep water was influenced by the surface intrusion of the Kuroshio water to the shelf region. When the intrusion of the Kuroshio surface water to the shelf region was weak in 2006, the cold and NO3−-rich shelf water intruded into the bottom layer in the bay from the shelf. This bottom intrusion was intensified by the large river discharge. The nitrogen isotope ratio (δ15N) of NO3− (4–5‰) in the bottom bay water was same as that in the deeper NO3− over the shelf, indicating the supply of new nitrogen to the bay. The warm and NO3−-poor shelf water intruded into the middle layer via the mixing region at the bay mouth when the Kuroshio water distributed in the coastal areas off Ise Bay in 2005. The regenerated NO3− with isotopically light nitrogen (δ15N=−1‰) was supplied from the shelf to the bay. This NO3− is regenerated by the nitrification in the upper layer over the shelf. The contribution rate of regenerated NO3− over the shelf to the total NO3− in the subsurface chlorophyll maximum layer in the bay was estimated at 56% by a two-source mixing model coupled with the Rayleigh equation. 相似文献