Metal Retention Experiments for the Design of Soil‐Mix Technology Permeable Reactive Barriers     

Claudiane Ouellet‐Plamondon  Rod Lynch  Abir Al‐Tabbaa 《洁净——土壤、空气、水》2011,39(9):844-852

Soil‐mix technology is effective for the construction of permeable reactive barriers (PRBs) for in situ groundwater treatment. The objective of this study was to perform initial experiments for the design of soil‐mix technology PRBs according to (i) sorption isotherm, (ii) reaction kinetics and (iii) mass balance of the contaminants. The four tested reactive systems were: (i) a granular zeolite (clinoptilolite–GZ), (ii) a granular organoclay (GO), (iii) a 1:1‐mixture GZ and model sandy clayey soil and (iv) a 1:1:1‐mixture of GZ, GO and model soil. The laboratory experiments consisted of batch tests (volume 900 mL and sorbent mass 18 g) with a multimetal solution of Pb, Cu, Zn, Cd and Ni. For the adsorption experiment, the initial concentrations ranged from 0.01 to 0.5 mM (2.5 to 30 mg/L). The maximum metal retention was measured in a batch test (300 mg/L for each metal, volume 900 mL, sorbent mass 90–4.5 g). The reactive material efficiency order was found to be GZ > GZ‐soil mix > GZ‐soil‐GO mix > GO. Langmuir isotherms modelled the adsorption, even in presence of a mixed cations solution. Adsorption was energetically favourable and spontaneous in all cases. Metals were removed according to the second order reaction kinetics; GZ and the 1:1‐mix were very similar. The maximum retention capacity was 0.1–0.2 mmol/g for Pb in the presence of clinoptilolite; for Cu, Zn, Cd and Ni, it was below 0.05 mmol/g for the four reactive systems. Mixing granular zeolite, organoclay and model soil increased the chemisorption. Providing that GZ is reactive enough for the specific conditions, GZ can be mixed to obtain the required sorption. Granular clinoptilolite addition to soil is recommended for PRBs for metal contaminated groundwater.  相似文献   

Impact of mesoscale eddies on particulate organic carbon flux in the western subarctic North Pacific     

Dobashi  Ryo  Ueno  Hiromichi  Matsudera  Nozomi  Fujita  Isao  Fujiki  Tetsuichi  Honda  Makio C.  Harada  Naomi 《Journal of Oceanography》2022,78(1):1-14

The mechanism that controls particulate organic carbon (POC) flux in the deep sea differs depending on the season and sea. The POC produced in the western subarctic North Pacific are known to be transported to the deep sea efficiently, but the direct relationship between the POC flux and physical processes is still unclear. In this study, we evaluated the effect of mesoscale eddies on POC flux in the western subarctic North Pacific. The seasonal and interannual variabilities of POC flux were investigated using data from a time-series sediment trap deployed at 4810 m at station K2 (47°N, 160°E) from 2005 to 2018. POC flux was high during May–November, appearing to reflect spring and fall blooms at the ocean surface. POC flux also showed interannual variability, with twelve peaks that were mostly affected by enhanced bloom just before the peak. Nine peaks of the twelve peaks were affected by mesoscale eddies, which enhanced bloom around K2 by extending the area with a high chlorophyll-a concentration along the coastal region into the offshore region, suggesting that mesoscale eddies strongly impact the interannual variability of POC flux at K2.

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Effect of dust event timing on glacier runoff: sensitivity analysis for a Tibetan glacier     

Koji Fujita 《水文研究》2007,21(21):2892-2896

The impact of the timing of dust deposition on glacier runoff was evaluated using a glacier mass‐balance model with a newly improved scheme to track a dusted layer in a snow layer of a glacier. The lowering of surface albedo due to the dusted layer appearing leads to a drastic increase of glacier runoff even under the same meteorological conditions. Calculations of seasonal sensitivity, the relationship between dusted date and resulting runoff, have shown that dust deposition during a melting season might cause a drastic mass outflow from a glacier through changing the surface albedo during the melting season. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Quantitative evaluation of the performance of a permit auction system in reducing bycatch of sea turtles in the Hawaii Swordfish longline fishery     

Feng Tao Ning  Chao Zhang  Rod Fujita 《Marine Policy》2009

Many authors have suggested the use of a cap and trade auction system to help reduce bycatch—the incidental take of species by fishing gear targeting other species—of sea turtles in the Hawaii-based swordfish longline fishery. However, we know of no quantitative evaluations of the method. We present a simple mathematical model to serve as a framework to evaluate bycatch auction systems quantitatively. We conclude that cap and trade auction systems have the potential to reduce sea turtle bycatch by creating a financial incentive, while keeping permit costs down to 2–3% of total revenues. While stringent regulations aimed at conserving endangered sea turtles would still be essential, implementation of an auction for issuing transferable bycatch permits would likely enhance the economic efficiency of the fleet. Sea turtle mortality could be reduced further if a shrinking cap on total turtle mortality was introduced, taking advantage of the incentives for reducing turtle mortality that are introduced by the cap and trade auction system.  相似文献   

Unstructured grid generation using LiDAR data for urban flood inundation modelling     

Ryota Tsubaki  Ichiro Fujita 《水文研究》2010,24(11):1404-1420

Inundation disasters, caused by sudden water level rise or rapid flow, occur frequently in various parts of the world. Such catastrophes strike not only in thinly populated flood plains or farmland but also in highly populated villages or urban areas. Inundation of the populated areas causes severe damage to the economy, injury, and loss of life; therefore, a proper management scheme for the disaster has to be developed. To predict and manage such adversity, an understanding of the dynamic processes of inundation flow is necessary because risk estimation is performed based on inundation flow information. In this study, we developed a comprehensive method to conduct detailed inundation flow simulations for a populated area with quite complex topographical features using LiDAR (Light Detection and Ranging) data. Detailed geospatial information including the location and shape of each building was extracted from the LiDAR data and used for the grid generation. The developed approach can distinguish buildings from vegetation and treat them differently in the flow model. With this method, a fine unstructured grid can be generated representing the complicated urban land features precisely without exhausting labour for data preparation. The accuracy of the generated grid with different grid spacing and grid type is discussed and the optimal range of grid spacing for direct representation of urban topography is investigated. The developed method is applied to the estimation of inundation flows, which occurred in the basin of the Shin‐minato River. A detailed inundation flow structure is represented by the flow model, and the flow characteristics with respect to topographic features are discussed. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Effects of transport of pore water and material heterogeneity on strain localization of fluid‐saturated gradient‐dependent viscoplastic geomaterial     

Yosuke Higo  Fusao Oka  Mingjing Jiang  Yuji Fujita 《国际地质力学数值与分析法杂志》2005,29(5):495-523

The purpose of the present paper is to clarify the effects of permeability and initial heterogeneity on the strain localization of fluid‐saturated cohesive soil modelled by a strain gradient‐dependent poro‐viscoplastic constitutive model. The effects of permeability and gradient parameters on the growth rate of the fluctuation were obtained by a linear instability analysis. Deformation behaviour of clay specimens modelled as a viscoplastic model with a second order strain gradient during shear was numerically analysed by a soil–water coupled FEM under both globally undrained and partially drained conditions. It was found that the deformation pattern and the stress–strain curve greatly depend on the permeability, the drainage conditions and the initial non‐homogeneous properties. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

The carbohydrate‐to‐protein ratio as a biological indicator of water movement     

Rod L. Oliver  Jacco C. Kromkamp 《新西兰海洋与淡水研究杂志》2013,47(3):529-530

We investigated temporal (day‐to‐day and season) and spatial (reach) variability of drift with the aim of guiding sampling protocol for quantifying drift at the whole river or reach scale. Overall, we found aquatic drift density and biomass varied considerably seasonally (CV = 72.9, 88.1) and to a lesser extent spatially (CV = 31.3, 30.7) and from day‐to‐day (CV = 45.2, 39.4). Although spatial and day‐to‐day variation in drift density and biomass were similar, sampling logistics suggest spatial sampling would be more cost‐effective and less time consuming. Drift density and biomass estimated from top samplers was often higher than estimates from samplers near the streambed or mid‐water column. A reliable estimate of mean densities and biomass at a site may require only two samplers— a top sampler and either a middle or bottom sampler. In our study, we calculated that sampling at four sites over 1 or 4 days at one site would be required to obtain a 95% CI within 50% of the mean drift density. Eight sites over 1 or 10 days at one site would be required to achieve a 95% CI within 25% of the mean drift density.  相似文献   

Sympatric seagrass shrimp show similar structure and selection along the seashore: a comparison of two cryptic Phycomenes zostericola lineages     

Jodie A. Haig  Rod M. Connolly  Jane M. Hughes 《Marine Ecology》2013,34(1):30-42

Small crustaceans are diverse and abundant in seagrass habitats and provide many ecological services. Further information is needed about their long‐ and short‐term response to habitat fragmentation and loss. Shrimp specimens were sampled from coastal seagrasses: latitudes 9°–27° S (Torres Strait to Moreton Bay, Queensland, Australia) and longitudes 141°–153° E (Weipa to Moreton Bay, Queensland, Australia). The seagrass shrimp Phycomenes zostericola (Caridea: Decapoda) underwent phylogeographic analysis using mitochondrial and nuclear sequence data. Lineage relationships were investigated and two deeply divergent sympatric lineages of P. zostericola were discovered in northern samples. The two lineages display vastly different demographic histories in spite of similar overall phylogeographic patterns. The two lineages appear to be in secondary contact with each other, detailing independent histories of sea level change, long distance colonisation and habitat fragmentation. Their regional structure is evidence that the potential for dispersal is only realised under specific environmental conditions. Nuclear data, used to determine reproductive status between lineages, instead displayed a non‐random latitudinal geographic distribution suggesting directional selection, possibly in response to ocean temperatures. The differences between the two deeply divergent lineages highlight the importance of understanding variability among cryptic taxa and their response to habitat change.  相似文献   

Nursery Function Drives Temporal Patterns in Fish Assemblage Structure in Four Tropical Estuaries     

Marcus Sheaves  Ross Johnston  Ashlee Johnson  Ronald Baker  Rod M. Connolly 《Estuaries and Coasts》2013,36(5):893-905

Despite estuary-to-estuary differences in assemblage composition, fish faunas of tropical Indo-Pacific estuaries show parallel patterns of temporal change, suggesting a common set of ecological drivers. One potentially important driver is the interaction of different patterns of occupancy by functional groups that display different life-history patterns. However, most studies that have considered temporal change lack the detail needed to understand life-history utilisation. Most have focussed on changes in catch per unit effort (CPUE) or probability of encounter, with only one study going further and investigating changes in size structure and then only for a single estuary. One of the reasons for this lack of detail is the large volume of work needed to collect comprehensive data on size structures of species rich assemblages across multiple estuary systems over time. To overcome the logistical limitations on data collection, we used joint patterns of change in CPUE and mean biomass per fish (BPF) as proxies for changes in size structure. We investigated how different life-history strategies contributed to overall temporal patterns of assemblage change across four tropical Indo-Pacific estuaries. The three life-history strategies displayed characteristically different patterns in CPUE and BPF and the relationships between CPUE and BPF that reflect differences in the way that the three groups use estuaries. These different patterns interacted to produce complex assemblage patterns that are likely to be sensitive to location-specific differences in the mix of species from each group, providing at least part of the explanation for the site-specific fish assemblage structures that are characteristic of tropical estuarine fish fauna.  相似文献   

Microstructures of phosphatic porcelain from sintering to vitrification: Evidence from sherds excavated in Charleston,South Carolina     

J. Victor Owen  Robert Hunter  Rod Jellicoe  Martha Zierden 《Geoarchaeology》2011,26(2):292-313

Eight phosphatic porcelain sherds recovered from various historical sites in Charleston were analyzed by electron microprobe. Some sherds contain sulfur (2.3–3.1wt.% SO₃); others contain only traces of this component. The analytical data suggest that the sulfurous sherds are Bow porcelain (London, Bowcock period, ca. 1755–1769). The origin(s) of the low‐S samples remains unidentified; one compositionally resembles “gold‐anchor period” (phosphatic) Chelsea porcelain (London, ca. 1756–1769) but its decoration is inconsistent with known wares produced by this factory during that era. The degree of vitrification is highly variable, particularly among the SO₃‐poor samples. The melt phase is strongly enriched in incompatible elements (Ti, Fe, Na, K). The phosphate phase [calcined bone ash (hydroxyapatite)] in poorly vitrified samples hosts minute melt blebs, but remains porous. With increasing vitrification, these melt blebs increase in size and begin to coalesce, ultimately forming ameboid patches up to ∼10 μm in diameter. In the most vitrified samples, the coalesced melt “leaks” into the matrix, leaving behind a phosphate phase that lacks pores and melt and has a lower CaO/P₂O₅ ratio (=2.7, molecular proportions) than either hydroxyapatite (3.3) or β‐whitlockite (3.0). The two varieties of phosphate occur in some poorly vitrified samples, suggesting the recycling of high‐fired wasters (as “grog”) in their ceramic pastes. Melt compositions vary with contiguous mineralogy, accounting for their divergence from the ternary eutectic in the Ca₃(PO₄)₂‐CaAl₂Si₂O₈‐SiO₂ system. The resorption of phosphate by the matrix melt virtually precludes recognition of anorthite formed by the “non‐phosphate glass equation.” © 2011 Wiley Periodicals, Inc.  相似文献