Papers by Keyword: Accumulation

Abstract: The results of hand calculation of boric acid accumulation in the core in a new generation WWER-TOI reactor in case of LOCA are presented. Variants of reducing the H₃BO₃ concentration in the HA-3 system down to 1, 2, 4 and 8 g/kg are considered. The mass of boric acid deposits on the core internals depending on the value of boric acid concentration in the HA-3 system is determined. The obtained results allow concluding that the accumulation and crystallization of boric acid in the core is possible.

Abstract: The paper is aimed at storing heat with gravel. During testing, we used various kinds of recycled aggregates, were studied their characteristics and suitability for ground heat storage. The most important feature is the specific heat capacity which was measured through own construction of the calorimeter. The construction of the calorimeter and measured results are summarized in this paper.

Abstract: Tobacco (Nicotiana tabacum L.) is able to accumulate cadmium in leaves and reduction of cadmium content can reduce health hazards to smokers. In the present study, the influence of silicon on the growth, yield and the content and distribution of cadmium (Cd) in flue-cured tobacco plants in the presence of cadmium was investigated by pot experiment. The results showed that Cd reduced the growth of both shoots and roots. Application of Si significantly increased the dry weight of roots and shoots in flue-cured tobacco grown in Cd contaminated soils, but not the largest leaf area. Si reduced the Cd concentration and accumulation in the root, stem and leaf of flue-cured tobacco compared with Cd alone. Si restricted the transport of Cd from roots to shoots. These results demonstrate that 1 and 2 g/kg Si could enhance Cd tolerance in flue-cured tobacco and decrease of Cd accumulation in plant and Cd translocation to shoots.

Abstract: Water management affects the bioavailability of cadmium (Cd) in the soil and hence their accumulation in rice and grain yields. A pot experiment was carried out to investigate the effects of different water managements (flooding, intermittent irrigation and aerobic) on rice yield and cadmium accumulation in rice plants growing on cadmium contaminated soil. The results showed that compared to the flooding and aerobic treatment, the intermittent irrigation increased grain yield by 7.55-29.58%, which contributed to the increase of seed setting rate and panicle number. Compared with the intermittent irrigation, aerobic treatment significantly increased Cd contents in roots, straw and grains, while flooding reduced the Cd contents in rice. Compared with flooding, both aerobic and intermittent irrigation enhanced Cd distribution in the root and reduced it in the straw and grain. With increasing irrigation from aerobic to flooded conditions, the soil available Cd concentrations decreased significantly. The patterns of soil pH change were just opposite to those of soil available Cd. Thus, intermittent irrigation could increase rice yield and also reduce Cd in the grain.

Abstract: Under cyclic load, the major shortcoming–ratcheting is produced in Wolffersdorff hypoplastic constitutive model. For eliminating ratcheting, Wolffersdorff hypoplastic model is ameliorated based on intergranular strain tensor. The added parameters in ameliorated model are determined by optimization method. Under cyclic load of triaxial consolidation undrained condition, the mechanics features of sand are described by the ameliorated Wolffersdorff hypoplastic constitutive model. Preliminary result shows that with increasing times of cyclic load excess pore water pressure is increased gradually and effective stress is reduced gradually. When effective is reduced to zero, the liquefaction happens. So in many projects, excess pore water pressure must dissipate by means of some measures. The sand liquefaction under the dynamic load is avoided.

Abstract: The trial of the earthworm-assisted phytoremediation of Cr in contaminated yellow soil was made to study the performance of earthworm in Cr accumulation of Vetiver Grass (vetiveria Zizanioides VG). Two groups were designed, adding earth worm (marked EM) and not adding earth worm (marked NEW).The result showed Vetiveria Zizanioides can absorb great amounts of chromium in soil, the decline rate of Cr was up to 75% and 78% respectively in EM and NEM at 60th day. Both root and shoot can accumulate Cr from soil. As the concentration of Cr gradually increased within 0-80mg/kg,the accumulation activity of two groups presented first increase and then decrease and reached maximum 644.31mg/kg, 943.14 mg/kg in root when the Cr concentration was 80 mg/kg. It began to decrease when the Cr concentration was above 120mg/kg.Vetiveria Zizanioides's accumulation ability differs in root and shoot. It presented root>shoot. With a comparative analysis, EM has higher accumulation and resistance of Cr at any designed treatments. In the analysis of relation between plants and soils, it was found that there was significant correlation in Cr contents between plants and soils (P<0.05). Furthermore, there was extremely significant correlation (P<0.01) between root and shoot in EM. There was a high retention rate of Vetiveria Zizanioides root to Cr. Retention rate of any treatments were all greater than 83% except 120mg/kg in EM. Plants kept much higher concentrations of Cr in roots than in their respective shoots. The biggest value was up to 96.23%. There was no obvious difference between EM and NEM in retention rate. Earthworm-assisted phytoremediation has high efficiency in Cr contaminated soil. It’s an idea method to Cr contaminated soil.

Abstract: The principle and mechanism of triphenylarsine (TPA) accumulation of arsenic hyper-accumulator-Pteris vittata L was investigated to remediate soil contaminated by abandoned arsenical chemical weapons in somewhere in Jilin Province, by means of soil and water culture in the greenhouse. Through analysis of changes in concentrations of total arsenic and TPA in Pteris vittata L. and in inorganic arsenic concentration of water culture solution, observation of apparent characteristics and determination of organic arsenic forms in Pteris vittata L., results show that Pteris vittata L. could accumulate TPA in soil when the concentration of TPA in soil is less than 150 mg/kg, and the concentration of arsenic in Pteris vittata L. increase initially and then decrease with TPA concentration increasing. When Pteris vittata L. had grown 3 months, the TPA concentration reaches its maximum, i.e. 316.85mg/kg (dry), while, the bioconcentration factor (BCF) decreases gradually. Although Pteris vittata L. still could accumulate TPA after TPA concentration reached more than 150 mg/kg, arsenic concentration in Pteris vittata L. significantly reduce due to stress effect of TPA.

Abstract: Based on the systematic fieldwork and the sampling of soil and corn, this paper studied the geochemical characteristic and the characteristic of total and available Ni in black soil and corn and the effects on them by the geochemical methods and SPSS software. The aim was to show the characteristic of Ni transformation and accumulation through soil-crop continuum and the influencing factors for food security. The results showed that total Ni in black soil of Jilin Province are above Jilin and national background level, the content of Ni is keeping the natural background in black soil in Jilin province. The influence of human activities in this district till now is comparatively less. The transformation degree of available Ni is relatively high. The degree of Ni accumulation in corn is low. The total Ni in soil have controlled effect on the available Ni, and the total Cu, Cr, Zn and the available Cr play a significant role in Ni transformation. The slight acid soil is better for Ni transformation and accumulation.

Abstract: Major objectives of this study are to evaluation the enrichment, accumulation, and potential ecological risk of zinc (Zn) in the surface sediments of southern Kaohsiung Harbor, Taiwan. Twelve sampling locations were installed of southern Kaohsiung Harbor to collect sediment samples for analyzing Zn. Results showed that the Zn concentrations varied from 731–946 mg/kg with an average of 323±525 mg/kg. The spatial distribution of Zn reveals that the Zn concentration is relatively high in the river mouth region, and gradually diminishes toward the harbor entrance region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of Zn pollution. Results from the enrichment factor and geo-accumulation index analyses imply that the sediments collected from the Salt River mouth can be characterized very severe degree enrichment and strong to very strong accumulation of Zn, respectively. Results of potential ecological risk index indicate that the sediment has low ecological potential risk.

Abstract: This research was conducted to understand the characteristics of arsenic (As) accumulation in Pteris vittata L. for remediation the soil contaminated by highly toxic As-chemicals. After Pteris vittata L. grown in different test soil for 3 months in the greenhouse, the determination result shown that the hyperaccumulator not only could accumulate large amounts inorganic arsenic and little organic arsenic, but also the majority of As was found in the fronds (over 90% of total As-content in the whole plants, average value, mg) .Furthermore, if the plants grown for different time in the same As-concentrations soil, the maximum As-concentrations (mg/kg) of pinnas, rachis and fronds all came forth at the end of the second month, but the maximum total As-content of fronds at the third month, so we could enhance the effects of remediation by harvested the fronds for per 3 months. The As-concentrations and the average total As-content of per plant and the As removal rate of the rhizosphere also could demonstrate the conclusion by comparing the harvested the plants per 3 months or not in 6 months.