Improving the numerical stability of the MAGIC model

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍｏｄｅｌｏｆａｃｉｄｉｆｉｃａｔｉｏｎｏｆｇｒｏｕｎｄｗａｔｅｒｉｎｃａｔｃｈｍｅｎｔ(ＭＡＧＩＣ)ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｗｉｄｅｌｙｕｓｅｄｍｏｄｅｌｓｗｏｒｌｄｗｉｄｅｆｏｒｐｒｅｄｉｃｔｉｎｇｃａｔｃｈｍｅｎｔａｃｉｄｉｆｉｃａｔｉｏｎａｎｄｉｓｓｔｉｌｌｕｎｄｅｒｆｕｒｔｈｅｒｕｐｇｒａｄｉｎｇ(Ｃｏｓｂｙ,1985;Ｈｉｎｄｅｒｅｒ,1995;Ｃｏｓｂｙ,1995).Ｔｈｅｍｏｄｅｌ,ｈｏｗｅｖｅｒ,ｉｓｉｎｈｅｒｅｎｔｌｙａｓｓｏｃｉａｔｅｄｗｉｔｈｎｕｍｅｒｉｃａｌｉ…     

Field demonstration of in situ immobilization of soil Pb using P amendments

A long-term field-scale demonstration project on the feasibility of using P to immobilize Pb in a Pb-contaminated urban soil was conducted. Phosphate was applied at an average rate of 3040 mg P/kg soil based on a P/Pb molar ration of 4.0, with four treatments: T₀, no P application; T₁, H₃PO₄ only; T₂, 1/2 H₃PO₄+1/2 CaH₂PO₄; and T₃, 1/2 H₃PO₄+1/2 phosphate rock. Soil samples were collected and analyzed 220 days after the P applications. For all P treatments, toxicity characteristic leaching procedure (TCLP) extractable Pb levels in surface soils (0-10 cm) were reduced to below 5.0 mg Pb/l, with T₂ also effective in reducing the TCLP Pb level in subsurface soils (10-30 cm, <4.63 mg/l). Sequential extraction analysis indicates that P was effective in transforming soil Pb from non-residual fractions to a residual fraction. Such a transformation was mainly through dissolution of Pb associated with carbonate fraction and precipitation of pyromorphite-like minerals, which were confirmed using X-ray diffraction (XRD). Among these three treatments, T₃ was the most effective in reducing Pb mobility and minimizing P and Pb leaching in the soil. Our research clearly demonstrates that P amendments were effective in immobilizing Pb in contaminated soil.     

Soil landscape constraint mapping for coastal land use planning using geographic information system

The aim of the study was to delineate soil landscape constraints to various land uses for urban and regional planning in the coastal areas of New South Wales (NSW), Australia. Soil landscape units mapped at 1:100,000 or coarser were sub-divided into component facets using advanced terrain modelling techniques in a geographic information system (GIS). The output facet grids were further overlain and linked with relevant GIS layers and soil databases to derive soil landscape constraint ratings for various land use purposes such as residential development, cropping and grazing. The constraint ratings for a specific land use were calculated based on objective and rule-based assessments of soil and landscape features such as engineering hazards, intrinsic fertility, drainage and other parameters. A series of soil landscape constraint maps which portray specific land use capability have been produced for the NSW coast. The methodology developed in this study has been demonstrated to be efficient in delineating soil landscape constraints and there is over 90% agreement between the model outputs and the assessment by soil surveyors with local knowledge. The output maps show levels of unprecedented detail of soil and landscape constraint for the coast of NSW and can be readily interpreted by land use planners and land managers for sustainable land use decision making practices.     

Fractionation of Heavy Metals in Surface Sediments of Taihu Lake, East China

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H₂O₂/HNO₃(2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu and Pb in various extracts solutions were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained from the BCR three-step sequential extraction indicated relatively high mobility of Zn, Cu, Pb and Ni in the sediments while Cd and Cr were poorly mobile. Enrichment of heavy metals was found in the sediments collected in the northern parts of Taihu Lake. In the sediments collected in the southern and western sides of the Lake, heavy metal concentrations were relatively low. The relationship between total organic carbon (TOC) and heavy metals concentrations in the sediments is discussed.     

Calorimetric studies on the energy metabolism of an infaunal bivalve,Abra tenuis,under normoxia,hypoxia and anoxia

Direct calorimetry was employed to measure the energy metabolism of infaunal bivalves, Abra tenuis, collected from a tidal lagoon in the Fleet, southern England, in June 1989, at various oxygen partial pressures. A significant anaerobic component (i.e., 20% of total metabolic rate) was detected under normoxia, presumably brought about by the intermittent ventilatory activity of this bivalve under these conditions. Under hypoxia (2.3 to 10 kPa, or 11 to 48% of full air saturation), however, the energy metabolism was maintained fully aerobic; the measured heat equivalent of oxygen uptake was not significantly different from the theoretical ranges for fully aerobic catabolism. Under anoxia, the rate of heat dissipation was reduced to 5–6% of the normoxic rate of heat dissipation. This conserves energy expenditure and would thus increase resistance of A. tenuis to anoxia or emersion. Physiological compensation by A. tenuis under conditions of declining oxygen tension involved a marked increase in ventilation rate. Comparison between fed and starved individuals indicated that costly physiological processes, such as digestion, absorption and growth declined at 10 and 5 kPa and were arrested at P_{O 2} (oxygen partial pressure) levels below 2.3 kPa. The present study provides evidence that there are no major differences between the metabolic responses of epifaunal suspension-feeding (eg. Mytilus edulis) and infaunal deposit-feeding (eg. A. tenuis) bivalves when exposed to environmental hypoxic stress.     

An ecosystem-based understanding and analysis for SENCE toward sustainable development

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｓｅａｒｃｈｅｒｓｈａｖｅｂｅｅｎｐａｙｉｎｇｍｏｒｅａｎｄｍｏｒｅａｔｔｅｎｔｉｏｎｓｔｏｅｃｏｓｙｓｔｅｍｔｏｓｕｐｐｏｒｔｔｈｅｒｅｓｅａｒｃｈｏｆｓｕｓｔａｉｎａｂｌｅｄｅｖｅｌｏｐｍｅｎｔ.Ｃｈｉｎｅｓｅｓｃｈｏｌａｒｓｆａｖｏｒｔｏｅｘｐａｎｄｔｈｅｓｃｏｐｅｏｆｅｃｏｓｙｓｔｅｍｆｒｏｍｉｔｓｎａｔｕｒａｌｎｅｓｓｔｏｉｔｓｓｏｃｉａｌｉｔｙ ,ｆｒｏｍｌｏｃａｌｔｏｇｌｏｂａｌ,ｆｒｏｍｍａｔｅｒｉａｌｔｏａｂｓｔｒａｃｔ,ｅｔｃ .Ｉｎｆａｃｔ,ｔｈｅａｔｔ…     

Changes of soil microbiological properties caused by land use changing from rice-wheat rotation to vegetable cultivation

A survey was done recently in Jiaxing city of Zhejiang Province in the Yangtze River Delta to compare the differences of soil microbiological properties among paddy soils with different land use including continuous open-field vegetable cultivation (OFVC), plastic-greenhouse vegetable cultivation (PGVC) and traditional rice-wheat rotation (RWR). The soil types included are percolating, permeable and waterlogged paddy soils. The results indicate that the microbial flora was markedly changed as the land use changed for all the three soil types. In continuous vegetable cultivation soils, especially in PGVC soils, the bacteria amounts decreased dramatically, but the fungal and actinomyce amounts increased as compared with RWR soils. The dehydrogenase activities decreased significantly in vegetable soils, especially in PGVC soils as compared with RWR soils. The microbial biomass C and the total phospholipid contents (TPL) in vegetable cultivation soil greatly decreased as compared with RWR soils. Biolog analysis indicated that the kinds of carbon sources that could be metabolized by native microbes in PGVC soils greatly decreased as compared with OFVC soils and RWR soils, revealing that microbial diversity had decreased since land use change. The activities of some soil enzymes including urease, invertase and phosphase were all lower in OFVC soils than those in RWR soils, and those in PGVC soils were the lowest. The degradation of microbiological activities in continuous vegetable cultivation soils, especially in PGVC soils, as compared with RWR soils might have been caused by soil acidification and accumulation of salts due to overuse of both organic and inorganic fertilizers in vegetable cultivation.     

Karyotype, nucleolus organiser regions and constitutive heterochromatin in Ostrea angasi (Molluscae: Bivalvia): evidence of taxonomic relationships within the Ostreidae

Chromosome preparations from gill tissue of the Australian flat oyster Ostrea angasi Sowerby were studied with conventional Giemsa staining, C-banding and silver staining techniques. A diploid complement of 2n = 20 was observed, consisting of five metacentric, three submetacentric and two subtelocentric pairs. Constitutive heterochromatin was distributed as large centromeric blocks in Chromosome Pairs 3, 6, 8, 9 and 10. The nucleolus organizer regions (NORs) were located terminally on long arms of Chromosome Pairs 9 and 10. This allowed the identification of homologous chromosomes in submetacentric and subtelocentric pairs. Intraspecific variability in NOR pattern as revealed by differences in the number of silver-stained NORs (Ag-NORs) per cell was found to be very common. Comparison of the patterns of karyotype, C-band and Ag-NORs between species of the larviparous oysters for which data have been published demonstrate that the chromosomal structure of the endemic Australian and New Zealand species O. angasi shows little similarity to the Southern Hemisphere oysters O. (Eostrea)puelchana Orbigny and Tiostrea chilensis (Philippi) and the Indo-West Pacific oyster O. denselamellosa, but very high resemblance to the European species O. edulis. Received: 12 August 1996 / Accepted: 16 September 1996     

Biogeographic partitioning and host specialization among foraminiferan dinoflagellate symbionts (<Emphasis Type="Italic">Symbiodinium</Emphasis>; Dinophyta)

Large discoidal soritid foraminiferans (Soritinae) are abundant in coral reef ecosystems. As with the many cnidarian invertebrates that inhabit these systems, they also depend on symbiotic dinoflagellates (Symbiodinium) for their growth and survival. Several particular Symbiodinium sub-genera or clades inhabit these soritids. One of these groups, referred to as clade C, dominates corals and their relatives throughout the tropical Indo-Pacific. In contrast, the distributions of Symbiodinium spp. from clades A, B, and C are more evenly apportioned across Caribbean invertebrate communities. To explore the possibility that a similar biogeographic break exists in the symbionts harbored by soritids, we surveyed the Symbiodinium spp. from the soritid genus Sorites, collected from the Pacific and Caribbean coasts of Panama as well as from Florida. Characterization of Symbiodinium obtained from foraminiferal and cnidarian samples was conducted using restriction fragment length polymorphism and phylogenetic analyses of the nuclear internal transcribed spacer region 2 (ITS 2) and a portion of the large subunit ribosomal DNA sequences. A distinctive biogeographic break between the kinds of symbionts found in Sorites from the East Pacific and Caribbean was clearly evident. Differences between cnidarian and foraminferan symbioses in each ocean may be explained by the subjection of Caribbean communities to severer environmental conditions during the early Quarternary. Caribbean Sorites spp. harbored symbionts described from clade F (specifically sub-clade Fr4) and clade H (formally referred to as Fr1), while Sorites spp. from the eastern Pacific were dominated by a single Symbiodinium haplotype in clade C. An ITS 2 phylogeny determined that most clade C types recovered from Indo-Pacific soritids form a monophyletic sub-lineage with other clade C symbionts typically found in Pacific corals from the genus Porites. The existence of multiple Symbiodinium lineages at various taxonomic levels associated specifically with soritids indicates that symbioses with these hosts are important in driving Symbiodinium spp. evolution.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by O. Kinne, Oldendorf/Luhe