Organic complexing agents may affect the mobility of radionuclides at low- and intermediate-level radioactive waste repositories. Especially, isosaccharinic acid (ISA) is the main cellulose degradation product under high pH conditions in cement pore water. ISA can combine with radionuclides and form stable complexes that adversely influence adsorption in the concrete phase, resulting in radionuclides to leach to the near- and far-fields of repositories. This study focuses on investigating the sorption of ISA onto engineered barriers such as concrete, thereby studying adsorption isotherms of ISA on concrete and comparing various isotherm models with the experimental data. The adsorption experiment was conducted in three background solutions, groundwater (adjusted to pH 13 using NaOH), State 1 (artificial cement pore water, pH 13.3), and State 2 (artificial cement pore water, pH 12.5), in a batch system at a temperature of 20°C. Concrete was characterized using BET, Zeta-potential analyzer, XRD, XRF, and SEM-EDS. ISA concentrations were detected using HPLC. The experimental data were best fitted to one-site Langmuir isotherm; On the other hand, either two-site isotherm or Freundlich isotherm couldn’t give reasonable fitting to the experimental data. The observed ISA sorption behavior on concrete is crucial for the disposal of radioactive waste because it can significantly lower the concentration of ISA in the pore water. Although one-site Langmuir isotherm might effectively represent the sorption behavior of ISA on concrete, the underlying mechanism is still unknown, and further investigation should be done in the near future.

Engineered barriers (concrete and grout) in Low- and Intermediate-Level Waste (L/ILW) disposal facilities tend to degrade by groundwater or rainfall water over a long period of time. During the degradation process, radionuclides stored in the disposal facility might be released into the pore water, which can pass through the natural rock barriers (granite and sedimentary rock) and may reach the near-field and far-field. In this transportation, radionuclide might be sorbed onto the engineered and natural rock barriers. In addition, the organic complexing agent such as ethylenediaminetetraacetic acid (EDTA) and α-isosaccharinic acid (ISA), is also present in pore water, which may affect the sorption and mobility of radionuclide. In this study, the sorption and mobility of 90Sr under different conditions such as two pHs (7 and 13), different initial concentrations of organic complexing agents (from 10-5 M to 10-2 M), and solutions (groundwater, pore water, and rainfall water) were investigated in a batch system. The groundwater was collected at the L/ILW disposal facility located at Gyeongju in South Korea. The pore water and rainfall water were artificially made in the laboratory. The concrete, grout, granite, and sedimentary rock samples were collected from the same study sites from where the groundwater was collected. The rock samples were crushed to 53-150 micrometers and were characterized by XRD, XRF, SEM-EDS, BET, and zeta potential analyzer. 90Sr concentration was determined using liquid scintillation counting. The sorption of 90Sr was described by distribution coefficients (Kd) and sorption reduction factor (SRF). In the case of EDTA, the Kd values of 90Sr remained constant from 10-5 M to 10-3 M and tended to decrease at 10-2 M, while in case of ISA the Kd values decreased steadily as the concentration of ISA was increased from 10-5 M to 10-3 M; However, a sudden reduction in the Kd values were observed above 10-2 M. In comparison to EDTA, ISA gave a higher SRF of 90Sr. Therefore, from the above results, it can be concluded that the presence of ISA has a greater effect on the sorption and mobility of radionuclide in the solutions than EDTA, and the radionuclide may reach near- and far-field of the L/ILW disposal facility.

Organic complexing agents which are contained in the radioactive waste can form the complex with radionuclides and enhance the solubility of radionuclides. The mobility of radionuclides to the far-field from the repository will be increased by radionuclide-ligand complex formation. Therefore, the assessment of the radionuclides’ solubility should be performed in the presence of organic complexing agents. In this study, five radionuclides (cobalt, strontium, iodine, cesium, and uranium) and three organic complexing agents (ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and isosaccharinic acid (ISA)) were selected as model radionuclides and organic complexing agents, respectively. For simulating the in-situ condition, the groundwater near the repository was collected and applied in solubility experiments and the solubility was measured in various environmental conditions such as different pHs (7, 9, 11, and 13), temperatures (10°C, 20°C, and 40°C), and a range of organic complexing agent concentrations (10-5, 10-4, 10-3, and 10-2 M). In cases of cesium and iodine, they were very soluble in all conditions, and the effect on their solubilities was not observed. However, at high pHs, cobalt and strontium showed lower solubilities than at neutral pH and the solubility enhancement by the organic complexing agents was significant. Moreover, the effects of each organic ligand showed obvious differences and were in the order of EDTA > NTA > ISA. The solubility of uranium was increased with increasing the organic ligand concentration at lower pHs, but the organic complexing agents did not cause a remarkable difference at high pHs. According to these results, the presence of complexing agents could enhance the radionuclides’ solubility and increase the potential to release the radionuclides to the far-field from the repository. Solubility experiments of other major radionuclides in the repository are in progress.

본 연구는 공기주입 이중피복온실과 관행 이중피복온실의 생육환경과 단열성능을 비교하기 위하여 수 행하였다. 두 온실의 온도, 상대습도, 포차, 이산화탄소농도, 일사량, 딸기 생산량 및 난방연료소비량을 비교하 였다. 공기주입온실이 관행온실보다 야간에 상대습도가 더 높고 포차는 더 낮게 나타나 딸기의 생육에 좋지 않은 환경을 보여주었다. 이산화탄소농도는 공기주입온실이 관행온실보다 더 높게 나타났으며, 이는 공기주입 온실이 더 밀폐되어 있어 환기량이 적기 때문인 것으로 판단된다. 관행온실의 광투과율이 77%로 공기주입온실 의 72%보다 더 높아 관행온실의 광환경이 더 우수한 것으로 나타났다. 관행온실의 딸기 생산량이 더 높게 나 타났으며, 이는 관행온실의 생육환경이 공기주입온실보다 더 우수한 결과로 판단된다. 난방연료는 공기주입온 실에서 더 적게 소모되어 공기주입온실의 단열성능이 더 우수한 것으로 나타났다.

The objective of this study is to investigate the potential use of MSW incineration fly ash as an economic material for the removal of heavy metals (Pb, Mn, Fe, and Cu) from AMD. Batch adsorption experiment was conducted to examine the effects of pH, adsorbent dosage and contact time on metal ions removal in synthetic AMD using MSW incineration fly ash. Precipitation of calcium hydroxide and sodium hydroxide was used for comparison with MSW incineration fly ash by adjusting the pH (5 ~ 11) by coagulation method with 20 min reaction time. Comparing the application of Ca(OH)2 and Na(OH), fly ash proves more efficient which may be due to its porosity and chemical composition. The results from adsorption studies showed that maximum adsorption rate was achieved at 0.4g dose when various fly ash dosages were added to the solution with 60 min optimum time and removal efficiency of heavy metals was over 96%. The effectiveness of fly ash can be related to its high calcium (CaO 55%) content. Efficiency of heavy metals removal was directly linked to the amount of fly ash in the reaction mixture and to the final pH attained. pH plays a significant role in heavy metal uptake. The main removal mechanism was adsorption at the surface of the fly ash together with the precipitation and co- precipitation from the solution with chemicals. Therefore the use of MSW incineration fly ash for treatment of AMD would represent a new market opportunity for this waste product. It can also be useful for neutralizing AMD and possibly reduce its adverse effects to the environment with efficient removal of metal ions from AMD.

Acid mine drainage (AMD) has emerged as one of the greatest environmental threats facing mining industry owing to its characteristic low pH, high acidity and elevated concentrations of metals and sulphate content. This study evaluates the efficiency of fly ash as a low cost material to remove heavy metals (Cu, Fe, Mn and Pb) from AMD. The effects of varying contact time, dosage and pH on adsorption were investigated using synthetically prepared AMD. The experiments was conducted in series of batches for adsorption using a mechanical shaker with 50mL AMD at various dosages of fly ash (0.1 - 0.8g/L) and coagulation using a standard jar tester of 1000mL AMD with chemical coagulant dosages (0.5 - 10g/L). Tests were also conducted with 50mL AMD without fly to evaluate the treatment efficiency of fly ash to chemicals. All tests were performed in duplicate for consistency and accuracy. The chemical composition of fly ash was characterized by X-ray fluorescence (XRF) and the result shows the fly ash is rich in calcium (CaO 54.9%). Leaching test of the fly ash was conducted using KLST and TCLP method to compare the results and evaluate the behavior of leaching ash in replenishing acidic media at low pH such as acid mine drainage. pH plays a significant role in heavy metal uptake in this study with increased in pH value the removal rate increased. The optimum dosage for Adsorption was found to be 0.4g/L with 60 min optimum contact time and coagulation 6mg/L with reduced metal concentrations much less than regulation standards for Cu, Fe, Mn and Pb. From all tests conducted fly ash proves more efficient with over 96% removal even at low dosages. The effectiveness of the treatment process will depend on the quality of the fly ash and the AMD. Therefore the use of fly ash for treatment of mine wastewater would represent a new market opportunity for this waste product. Recycling of fly ash will conserve the natural raw materials and abridge the disposal cost. It will also create new revenues and business opportunities while protecting the environment. Most significantly, the two waste products acid mine drainage and fly Ash could be neutralized and when reacted together to produce much cleaner water broadly compared to post process water derived from Lime treated AMD and sulfates removal rates were in the range of 90% in both experiments. Fly ash is more economical, sustainable.

Endophytic Aspergillus Fumigatus sp. LH02, isolated from the roots of soybean and indentified through phylogenetic analysis of 18S rDNA sequence, was found stimulatory to the growth of Waito-C rice seedlings among 13 other endophytic strains screened. In growth hormone analysis, pure culture of fungal isolate produced three gibberellins viz GA4, GA9 and GA12. To know the role and effect on soybean in endophytic association (EA) and non-endophytic association (NEA) under salt stress (70 and 140mM), experiment was carried out at growth chamber using complete randomized block design. The results elaborated that the EA has significantly increased the shoot length, shoot and root fresh and dry weights, chlorophyll content, photosynthesis rate and leaf area of the plants with and without salt stress compared to control. Field emission scanning electron microscope analysis of root's surface showed that EA plants were extensively colnized by Aspergillus fumigatus LH02 under high salanity. In phytohormonal anlysis, ABA contents in EA and NEA were almost similar. Howere, when plants were exposed th salt stress, ABA levels were found significantly low in EA compared to NEA plant. In isoflavone content analysis, aglycones, malonyl, acetyl and glucosides isoflavones (total 11 compounds) were analyzed for each treatment through extensive HPLC andalysis. The quantities of isoflavone were found higher in EA plant's leaves with and without salt stress compared to NEA plant leaves. In conclusion, such endophytic association can be beneficial to explore ways to improve crop production under stressful conditions.

We carried out the effect of Si levels (0.5, 1.0 and 2.0 mM) on ethylene and salicylic acid (SA) of hydroponically grown rice plants, after 6h, 12h and 24h of Si application. All samples were analyzed after applying wound stress for 30 minutes. In 6 h treatments, 0.5 and 1.0 mM of Si decreased ethylene production by 7% and 9.9% respectively, while elevated level of Si (2 mM) insignificantly affected ethylene production under same conditions. However 0.5 and 1 mM of Si enhanced endogenous SA contents by 2.6% and 17.3% respectively, while 2 mM of Si decreased SA contents by 3% as compared to control. Samples analyzed after 12h of 0.5, 1 mM and 2 mM Si application showed reduction of 11%, 4% and 1.7% respectively, while SA contents increased by 4% and 9.5% in 0.5 and 1 mM Si treatments. Samples analyzed after 24 h of Si treatment showed that 0.5 and 1.0 mM of Si inhibited ethylene production by 12.6% and 18.2% respectively, while 2 mM Si increased ethylene production by 11.9% as compared to control. It was observed that the SA content of rice was almost similar to control in 0.5 mM Si applied treatments, while 1 mM and 2 mM of Si increased SA contents by 6.5% and 6.9% as compared to control. It was concluded that Si alleviates the effect of wounding stress in rice by regulating ethylene and SA production.