• Journal of Radiation Protection and Research
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• v.28 no.4
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• pp.271-279
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• 2003

Soil blocks were taken into culture boxes from 12 paddy fields within 5 km radii of Yonggwang and Ulchin NPPs and $^{90}Sr$ was applied to the surface water at a pre-transplanting stage and $1{\sim}2$ days before the start of heading. Following the pre-transplanting application, transfer factors were investigated for $2{\sim}4$ years. In the year of application, transfer factors $(m^2\;kg^{-1}-dry)\;of\;^{90}Sr$ applied before transplanting, showing no regionally distinguishable trend, varied with soils by a factor of about 2 with averages of $2.6{\times}10^{-4}$ for hulled seeds and $1.3{\times}10^{-2}$ for straw Transfer factors of $^{90}Sr$ applied shortly before heading were about 2 times greater than those applied before transplanting. Transfer factors tended to decrease with increasing soil pH and exchangeable Ca. Generic values of $^{90}Sr$ transfer factors in the year of deposition were proposed for the Korean paddy fields. In the second year compared with the first year, the transfer factor decreased more in Ulchin soils, which were on the whole higher in sand content, than in Yonggwang soils. For Yonggwang soils as a whole, the annual decrease in transfer factor was well described by an exponential equation with a half-life of about 2.2 years.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.105-109
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• 2001

Poorly drained coarse textured paddy soils has harmful substances(e.g. $Fe^{2+}$, $H_2S$, organic acid etc.) due to reduction condition, and lower soil temperature during early stage of rice crop. The roots of the rice plant usually were distributed in the surface layer, and prone to lodged. To solve the problems, the study was carried out in the typical poorly drained, sandy loam textured paddy soils during 1997-1998. Coated urea and urea fertilizers were applied on the surface and whole layer mixed respectively. Yield of the surface fertilization of coated urea had increasing tendency but not significant. Advantages of this experiment was saving of about 30% of nitrogen fertilizer and top dressing labour, which would reduce possibility of water pollution.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.2
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• pp.101-110
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• 2018

There is an increasing concern over arsenic (As) contamination in rice since Codex Committee on Contaminants in Food (CCCF) discuss on maximum levels for As in rice in 2010. This study was conducted to reduce As concentration in rice by soil amendment treatments in paddy field soils contaminated by As. The selected four amendments were poultry manure, agri-lime, steel slag, and gypsum with the addition of 3% or 5% (w/w) on a dry basis. The As reduction effect could not be verified, as a result of the pot test by adding poultry manure to the paddy soil around the mine located in Yesan. Among the agri-lime treated rice cultivated pots, the As concentration increased up to 32.1%. On the other hand, the content of As in the sample pots treated with steel slag and gypsum decreased by 65.4% and 63.4%, respectively. On the basis of the results of these pot experiments, the field test was carried out in the As polluted rice field around the mine located in Yesan, and when the four amendments were treated, the As content in the brown rice reduced in all the amendment treatments compared with the control plot. The As reduction in brown rice of the amendment was confirmed to be higher efficiency by the order of gypsum > steel slag > poultry manure > agri-lime. As a result of pot experiments using paddy soil around the mine located in Seosan, As stabilization efficiency in rice and As reduction effect could not be determined by comparison to the control. From the rice cultivated from agri-lime treated pot, As concentration increased by 15.8% in rice. On the other hand, the As content of the pots treated with steel slag and gypsum decreased by 39.1% and 60.2%, respectively. In conclusion, distinguished As reducing effectiveness could be expected by soil amendment treatments for rice cultivation.

• Economic and Environmental Geology
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• v.26 no.4
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• pp.465-472
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• 1993

The heavy metal contents are more abundant in stream waters, paddy soils and rice plants in the vicinity of abandoned mines compared to the surrounding areas in the Kyungpook province. However, these contents tend to decrease with distance from mines, and show some variation under different geological and geochemical environments. The Sin-stream waters have high contents of Cu=4.9 ppm, Pb=0.1 ppm, Zn=3.5 ppm and other heavy metals (Ni, Co, Cd) at Dalsung abandoned mine and low contents of Cu=0.4 ppm, Pb=0.1 ppm, Zn=0.1 ppm and other metals= 0.002 ppm in the surrounding area. The high contents decrease in the downstream in the area of calcareous sedimentary rocks. The paddy soils have high contents of approximately Cu=51 ppm, Pb=83 ppm, Zn=211 ppm, and Cd=11.3 ppm in the vicinity of Gunwi abandoned mine but low contents of Cu=4.5 ppm, Pb=2.9 ppm, Zn=60 ppm and Cd=0.4 ppm in the surrounding area. The Dadeog abandoned mine also shows similar trends to Gunwi mine. The contents of heavy metals of rice plants are high in the roots but trends to decrease through stem+leaf and become low in brown rices.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1455-1471
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• 2009

In order to investigate on the effect of stabilization methods for rice paddies contaminated by heavy metals, a series of lab-scale model test was carried out by applying the characteristics of submerged Paddy soil. To perform the lab-scale model test, columns were made by acrylic with the dimension of diameter=10cm, thickness=0.5cm and were filled with soils which was contaminated were mixed with stabilization agents(lime stone 5% and steel refining slag 5% respectively). To manipulate the reduction condition, soils in the columns were submerged with distilled water. And then soil water and subsurface water in each column were sampled in the regular term and analysed the various physical and chemical properties.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.464-472
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• 2014

The Codex Committee of Contaminants in Food (CCCF) has been discussing a new standard for arsenic (As) in rice since 2010 and a code of practice for the prevention and reduction of As contamination in rice since 2013. Therefore, our current studies focus on setting a maximum level of As in rice and paddy soil by considering bioavailability in the remediation of As contaminated soils. This study aimed to select an appropriate single chemical extractant for evaluating the mobility of As in paddy soil and the bioavailability of As to rice. Nine different extractants, such as deionized water, 0.01 M $Ca(NO_3)_2$, 0.1 M HCl, 0.2 M $C_6H_8O_7$, 0.43 M $HNO_3$, 0.43 M $CH_3COOH$, 0.5 M $KH_2PO_4$, 1 M HCl, and 1 M $NH_4NO_3$ were used in this study. Total As content in soil was also determined after aqua regia digestion. The As extractability of the was in the order of: Aqua regia > 1 M HCl > 0.5 M $KH_2PO_4$ > 0.43 M $HNO_3$ > 0.2 M $C_6H_8O_7$ > 0.1 M HCl > 0.43 M $CH_3COOH$ > deionized water > 1 M $NH_4NO_3$ > 0.01 M $Ca(NO_3)_2$. Correlation between soil extractants and As content in rice was in the order of : deionized water > 0.01 M $Ca(NO_3)_2$ > 0.43 M $CH_3COOH$ > 0.1 M HCl > 0.5 M $KH_2PO_4$ > 1 M $NH_4NO_3$ > 0.2 M $C_6H_8O_7$ > 0.43 M $HNO_3$ > 1M HCl > Aqua regia. BCF (bioconcentration factor) according to extractants was in the order of : 0.01M $Ca(NO_3)_2$ > 1 M $NH_4NO_3$ > deionized water > 0.43 M $CH_3COOH$ > 0.1 M HCl > 0.43 M $HNO_3$ > 0.2 M $C_6H_8O_7$ > 0.5 M $KH_2PO_4$ > 1 M HCl > Aqua regia. Therefore, 0.01 M $Ca(NO_3)_2$ ($r=0.78^{**}$) was proven to have the greatest potential for predicting As bioavailability in soil with higher correlation between As in rice and the extractant.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1108-1113
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• 2012

The changes of soil organic carbon (SOC) content in paddy soils (sandy loam) were assessed from data of the 59 years fertilization plots in which the continuous rice cropping experiment started in 1954. The treatments were no fertilization(no fert.), NPK fertilization (N, NPK), NPK plus rice straw compost (NPK+C), and NPK plus rice straw compost, silicate fertilizer and lime (NPK+CLS). After 41 years, SOC content in NPK+C and NPK+CLS treatment in surface soils (0~15 cm) reached at the highest, followed by maintaining a plateau level for 8 years. After 51 years, they showed a tendency to decrease. Peak concentrations of soil organic carbon were $20.1g\;kg^{-1}$ in NPK+CLS, $19.1g\;kg^{-1}$ in NPK+C, $13.3g\;kg^{-1}$ in NPK, $11.9g\;kg^{-1}$ in N, and $11.6g\;kg^{-1}$ in control. Dissolved organic carbon(DOC) contents in surface soil solution were about 2.3 times higher in NPK+C than that in NPK+CLS. Therefore, SOC in subsurface soil(15~30 cm) was greater in NPK+C than the other treatments. These results indicate that continuous application of rice straw compost and silicate fertilizer affected significantly on the level of SOC in surface soils, subsurface soils, and soil solutions. Thus, the combined applications of NPK fertilizers with organic compost and silicate as a soil amendment are recommended as the best fertilization practice for soil carbon accumulation, environment conservation, and enhancement of soil fertility status in the continuous rice cropping system.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.10-17
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• 1994

To investigate differences with the polluted sources on Cu contents in soils and paddy rices under water pollutions, soils with the distance, the surface(0-15㎝ depth) and subsurface(15-30㎝ depth) in 1982 and 1990, and rice plants at the soil sampling sites in 1990 were separately sample at Mangyeong River area under the influence of municipal and industrial waste water from Jeonju city. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with mixture of $HNO_3$ and $HClO_4$ for analyzing Cu, Cd, Zn, Pb by atomic absorption spectrophotometry. Cu contents in soils ranged from 5.20 to 71.70 mg $kg^{-1}$. Average Cu level in 1990 was higher than that in 1982. Variation of Cu content with the distances from the source of waste water in 1990 was more regularly decreased than that in 1982. A significant correlation was observed between Cu contents in leaf sheath of rice plant and Cu, Zn and Pb contents in soils. Cu contents in soil was correlated with Zn and Pb in soil at area affected by waste water, regardless of years and soil depths. Cu contents in brown rice ranged from 0.4 to 10 mg $kg^{-1}$, and it was the lowest in parts of rice plant, and Cu content in panicle axis was 2.3 times higher than that in brown rice.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.417-425
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• 2013

This study investigated the runoff from rice paddy located on reclaimed fine sandy loam soil to provide data for the development of policies to protect water quality of estuaries. Total N (TN), Total P (TP) concentrations and runoff loads at outlet were monitored from 2006 to 2008. Soil phosphate adsorptivity was measured and compared with typical paddy soil in watersheds. TP concentration of the paddy water and TP runoff loads were much greater than those of typical paddy field in watershed because phosphate adsoptivity in reclaimed paddy field of fine sandy loam appeared to be a third of those of typical paddy soils by relatively low soil OM and high sand content of the reclaimed soil. Thus, nutrient runoff, particularly phosphate from the reclaimed paddy field needs to be managed more thoroughly to protect estuarine water quality.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.174-177
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• 2004

Differential interferometric phases from JERS-1 L­band data sets show spatial variation of path-length ranging from a few mm to several cm. The variation may be caused by changes in soil moisture contents, i.e. variation of penetration depth and the swelling of soils. Although the amount of total effect caused by soil moisture is not measurable, it is clear that the soil moisture according to precipitation is another factor to be considered in DInSAR analysis. We also discuss DInSAR characteristics in a rice paddy according to irrigation conditions, and discrimination of hydrological features such as stream channels and watershed boundaries by applying DInSAR technique.