Chang-Oh Hong

Dynamics of Heavy Metals in Soil Amended with Oyster Shell Meal

A large amount of oyster-shell waste has been illegally disposed at oyster farm sites along the southern coast of Korea, which already created serious environmental problems. Therefore, the study was undertaken to increase the consumption of oyster shell meal as a soil amendment. The effects of oyster shell meal on dynamics of heavy metals and uptake of heavy metals by spring Chinese cabbage were evaluated in silt loam soil (in Gyeongsang National University, Jinju, Gyeongnam-do, Korea), where 0, 4, 8, 12 and 16 Mg oyster-shell meal fertilizer were added. Lime treatment (2 Mg ) was selected as a control. In the results of this study, cabbage yields were increased by increasing levels of oyster-shell meal fertilizer. With increasing levels of oyster-shell meal fertilizer, total heavy metals concentrations were not significant among treatments. However, 0.1N HCl extractable heavy metals concentration was significantly reduced due to increasing of soil pH. A lot of portion (ca. ) heavy metals fraction of all fractions was residual phase in soil after harvesting. The contents of Cu, Mo, Zn in cabbage were slightly increased by increasing levels of oyster shell meal fertilizer. However, there were no toxic symptoms of heavy metals during cultivation. Conclusively, it was estimated that oyster shell fertilizer could be a good amendment to increase productivity of crop and reduce uptake of heavy metals by crop and mobility of heavy metals in soil.

Effect of Organic Residue Incorporation on Salt Activity in Greenhouse Soil

In Korea, salt stress is one of the major problems limiting crop production and eco-environmental quality in greenhouse soil. The objective of this study was to evaluate the effectiveness of organic residues (Chinese milk vetch, maize stalk, rice straw, and rye straw) for reducing salt activity in greenhouse soil. Organic residues was incorporated with salt-accumulated soil (EC, 3.0 dS ) at the rate of 5% (wt ) and the changes of electrical conductivity (EC) was determined weekly for 8 weeks under incubation condition at . The EC, microbial biomass carbon (MBC), and water soluble ions in soil was strongly affected by C/N ratio of organic residues. After 8 weeks incubation, the concentration of water soluble , and was significantly decreased in organic residues having high C/N ratio (maize stalk, rice straw, and rye straw) incorporated soil compared to organic residues having lower C/N ratio (Chinese milk vetch) incorporated soil. The EC value in Chinese milk vetch incorporated soil was higher than control treatment. In contrast, maize stalk, rice straw, and rye straw amended soil was highly decreased the EC value compared to control and Chinese milk vetch applied soil after 4 weeks incubation. Our results indicated that incorporation of organic residues having high C/N ratio (>30) could reduce salt activity resulting from reducing concentration of water soluble ions.

Effect of Irrigation Water Salinization on Salt Accumulation of Plastic Film House Soil around Sumjin River Estuary

The causes of salt accumulation in soils of plastic film houses nearby Sumjin river estuary in Mokdo-ri(), Hadong, Gyeongnam, Korea were investigated in 2006. With chemical properties soils and water analyzed and fertilization status monitored, the study showed that mean salt concentration of soil was much higher at EC than the Korean average (EC ) in 2000s for plastic film houses soil with exchangeable Na and water-soluble Cl , and then might result to salt damage in sensitive crop plants. Salt concentration of ground water used as main irrigation water source contained very high EC with corresponding value of . Particularly, increase of EC value was directly proportional with the increased pumping of ground water used as a water-covering system in order to protect the temperature inside plastic film houses from the early winter season. High Na and Cl portion of ions in water might had contributed to the specific ion damage in the crops. Secondly, heavy inputs of chemicals and composts significantly increased the accumulated salts in soil. Conclusively, salt accumulation might had been accelerated by use of salted-groundwater irrigation and heavy fertilization rate. To minimize this problem, ensuring good quality of irrigation water is essential as well as reducing fertilization level.

Reversed Effects of Phosphate Fertilizer on Reducing Phytoavailability of Cadmium in Mine Tailing Affected Soil

To reduce effectively cadmium (Cd) phytoavailability by phosphate in mine tailing affected soil, fused and super phosphate (FSP), a main phosphate fertilizer in South Korea, was selected as phosphate source and then applied at the rates of 0, 78, 390, and 780 . FSP did not decrease Cd extractability and radish Cd uptake, but increased significantly. The effect of Cd supplement and soil negativity increase through FSP application was not significant. Soil pH decreased markedly with increasing FSP application, which increased significantly soil Cd extractability and radish Cd uptake. As a result, phosphate fertilizer for reducing Cd phtyoavailability in heavy metals contaminated soil should be carefully selected as alkaline type.

Determining Effect of Oyster Shell on Cadmium Extractability and Mechanism of Immobilization in Arable Soil

Abstract BACKGROUND: Oyster shell(OS) is alkaline with pH 9.8, porous, and has high concentration of CaCO 3 . It could be used as an alternative of lime fertilizer to immobilize cadmium(Cd) in heavy metal contaminated arable soil. Therefore, this study has been conducted to compare effects of calcium(Ca) materials [OS and Ca(OH) 2 ] on Cd extractability in contaminated soil and determined mechanisms of Cd immobilization with OS.METHODS AND RESULTS: Both Ca materials were added at the rates of 0, 0.1, 0.2, 0.4, and 0.8% (wt Ca wt-1) in Cd contaminated soil and the mixtures were incubated at 25℃ for 4 weeks. Both Ca materials increased pH and negative charge of soil with increasing Ca addition and decreased 1N NH 4 OAc extractable Cd concentration. 0.1 N HCl extractable Cd concentration markedly decreased with addition of OS. 1 N NH 4 OAc extractable Cd concentration was related with pH and net negative charge of soil, but not with 0.1 N HCl extractable Cd concentration. We assumed that Cd immobilization with Ca(OH)

Effect of Phosphate Fertilizer and Manure in Reducing Cadmium Phytoavailability in Radish-grown Soil

ACKGROUND: Cadmium (Cd) has long been recognized as one of most toxic elements. Application of organic amendments and phosphate fertilizers can decrease the bioavailability of heavy metals in contaminated soil. METHODS AND RESULTS: This study was conducted to evaluate effect of combined application of phosphate fertilizer and manure in reducing cadmium phytoavailability in heavy metal contaminated soil. Phosphate fertilizers [Fused and super phosphate (FSP) and (DPP)] and manure (M) were applied as single application (FSP, DPP, and M) to combined application (FSP+M and DPP+M) before radish seeding. decreased extractable Cd and plant Cd concentration, mainly due to increases in soil pH and negative charge. However, FSP increased extractable Cd and plant Cd concentration. Manure significantly increased soil pH and negative charge. Combined application of phosphate fertilizer and manure were much more effective in reducing Cd phytoavailability than a simple application of each component. Calculated solubility diagram indicated that Cd concentrations in the solution of soils amended with phosphate fertilizers and manure were undersaturated with respect to all potential Cd minerals [, , , and ]. Plant Cd concentration and extractable Cd were negatively related to soil pH and negative charge. CONCLUSION: Alleviation of Cd phytoavailability with phosphate fertilizer and manure can be attributed primarily to Cd immobilization due to the increase in soil pH and negative charge rather than Cd and phosphate precipitation. Therefore, combined application of alkaline phosphate materials and manure is effective for reducing Cd phytoavailability.

Determination of Cadmium and Zinc Contamination Source in Arable Soil in the Vicinity of a Zinc Smelting Factory

Agricultural area in the vicinity of the smelting factory in Kyeongbuk province, the third △△ largest zinc smelting factory in the world, was contaminated by high concentration of heavy metals. However, the heavy metals source was not yet directly traced and thus, resulted to a conflict between the factory and residents within its vicinity. In order to determine the level of heavy metal contamination in the arable lands located at the north eastern part of the factory, soils were sampled systematically. To find out the major reason for the occurrence of this problem, waters and aerosols were sampled with constant intervals to the upward and downward direction from the factory and were analyzed to find out the heavy metal concent- rations. Cadmium (Cd) and zinc (Zn) of the heavy metals were highly accumulated more than the Korean warning criteria (Cd 1.5, Zn 300 mg kg -1 ) with mean values 1.7 and 407 mg kg -1 , respectively, at the surface soils (0-20 cm), and heavy metal concentration significantly decreased with increasing soil depth. In addition, the concentration of both metals slightly decreased with increasing distance from the factory to the surface soils. Cadmium and Zn were detected in the upward stream water with low concentration and concentrations increased significantly in the downstream after passing across the factory. Aerosol samples also showed traces of Cd and Zn which could be attributed to the contamination of the water system and the surface soils. Conclusively, Cd and Zn emitted from the smelting factory moved with the aerosol in the atmosphere △△ and thus, contaminated the agricultural areas and the water system within its vicinity.

Evaluation of Phosphorus Release Potential in Arable land with Different Landuse by Phosphorus Threshold

Heavy application of fertilizer and manure in excess from the optimum requirement for crop growth can increase phosphorus (P) accumulation and P release potential in soils. In this study, the relationship between soil test P and 0.01M extractable P was analysed to evaluate the P release potential of agricultural soils under different land-use. The paddy, upland, plastic film house(PFH) soils were sampled from Tongyoung and Changnyeong, and Daegok areas in Gyeongnam province, respectively. With respect to the P accumulation, available P contents in upland and PFH soils were 619 and 796 mg /kg, respectively indicating that different land-use types can greatly impact soil P accumulation. As soil available P was increased in the paddy soil, the content of 0.01M extractable P also linearly increased without change point. Comparatively, P threshold were detected at 520 mg /kg in both upland and PFH soils, indicating that P release potential were higher in these land-use systems. For reducing P release from agricultural soils, management of optimum P content is needed in soils possessing high P release potential. Further, the change point value, if it is to be used as an environmental indicator, requires more detailed investigation to cover a wide range of soil characteristics.

Effects of Fly Ash and Gypsum Mixture on Reducing Phosphorus Loss from Paddy Soil

Phosphorus transfer from agricultural soils to surface waters is an important environmental issue. Fly ash and phospho-gypsum which are industrial by-product were investigated as a means of reducing dissolved phosphorus in arable soil. To determine the optimum mixing ratio of fly ash(FA) and phospho-gypsum(PG) for reducing dissolved reactive P(DRP) in soil, various mixture ratio of FA and PG were mixed with two soil. The DRP content and pH in soils were analysed after 3 weeks incubation under flooding condition. Although DRP content in soils was significantly decreased by FA-PG mixture compared with control, there were no significant difference among the FA and PG mixture ratio of 75:25, 50:50, and 25:75. The mixture of 75% FA and 25% PG was selected for field test. A field experiment was carried out to evaluate the reducing DRP content in paddy soil to which 0(NPK), 20(FG 20), 40(FG 40), and 60(FG 60) Mg of the mixture were applied. The DRP content was reduced by 31% at the application rate of 60 Mg . In contrast to deceasing DRP, Ca-P content increased significantly with the mixture application rate. After rice harvesting, available , P, and exchangeable Ca content in soil increased significantly with application rate due to high content of Si, P, and Ca in the mixture. Mixtures of fly ash and gypsum should reduce P loss from paddy soil and increase soil fertility.

Cadmium and Zinc Uptake Characteristics of Corn Plant in Arable Soil Contaminated by Smelting Factory Source

The cadmium (Cd) and zinc (Zn) contamination of soils and cultivated crop plants by zinc smelting activities was studied. In the study area of the vicinity of zinc smelting factory in Korea, soils and corn plants were sampled at corn harvesting stage and analyzed Cd and Zn concentration as well as Cd and Zn fraction and chemical properties in soils. At 600 m radius of studied area, Cd and Zn were highly accumulated in the surface soils (0 - 20 cm) showed greater than the Korean warning criteria (Cd 1.5, Zn 300 mg ) with corresponding values 1.7 and 407 mg , respectively. The leaf part gave higher Cd concentration with the corresponding value of 9.5 mg as compared to the stem and grains pare (1.6 and 0.18 mg ), respectively. Higher Zn concentration was also obtained from the leaf part of the corn plant which gave the value of 1,733 mg . The stem and grain part gave corresponding values of 547 and 61 mg . The order of the mean Cd concentration in fractions is F3 (oxidizable fraction) > F2 (reducible fraction) > F4 (residual fraction) > F1 (exchangeable + acidic fraction). A highly positive correlation is observed between F2 and concentration of Cd and Zn in both plant pare, leaf and grain. Highly positive correlations are shown in the pH exchangeable Ca and Mg, and CEC when correlated with Cd and Zn bound to F4 fractions. To reduce Cd and Zn uptake by corn plant in an arable land heavily contaminated with Cd and Zn as affected by smelting factory, an efficient and effective soil management to increase soil pH and CEC is thus recommended.