• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.296-303
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• 2010

Chromium as a constituent of rocks occurs naturally in the environment in varying concentrations. However, the human activity has changed the geochemical cycle of chromium in the environment and has caused the chromium accumulation in soils. Korean soils revealed a wide range of chromium contents depending on parent material and land use. The total chromium contents of volcanic ash soils in Jeju, which were determined using $HNO_3$ + $HClO_4$ + HF, ranged from 434 to 1,164 mg $kg^{-1}$. The 'ecological' total chromium contents extracted using conc. HCl + conc. $HNO_3$ (aqua regia) in the same soils varied in a lower range of 50-189 mg $kg^{-1}$ (averaged percentage of aqua regia contents in $HNO_3$ + $HClO_4$ + HF contents: 14.9%). Serpentine soils in Andong showed a 'ecological' total chromium content of 309 mg $kg^{-1}$ and against it granitic soils in Andong only 20 mg $kg^{-1}$. In uncontaminated forest soils of Korea, the 'ecological' total chromium contents varied from 4.89 to 106 mg $kg^{-1}$ and the soluble chromium contents determined using 0.1 M HCl ranged from 0.01 to 0.64 mg $kg^{-1}$ (averaged percentage of 0.1 M HCl contents in aqua regia contents: 0.4%). Arable lands contained more soluble chromium than reported in forest soils (averaged soluble chromium: 0.36 and 0.09 mg $kg^{-1}$, respectively). In particular, the soluble chromium contents in greenhouse, orchard and upland soils were higher than in contaminated soils near mine and industrial site (maximum contents: greenhouse 15.3 mg $kg^{-1}$; upland 12.1 mg $kg^{-1}$; orchard 8.29 mg $kg^{-1}$; mine site 4.76 mg $kg^{-1}$; industrial site 2.80 mg $kg^{-1}$). On the basis of these results a accumulation of chromium in some specific arable lands can be assumed, probably by long-continued applications of fertilizers or soil amendments containing chromium. In Korean Enforcement Decree of the Soil Environment Conservation Act soil standards for total chromium do not exist yet.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.692-698
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• 2005

Two experiments were conducted to examine the effect of graded levels of dietary chromium and leucine, and different fat sources on performance and body composition of broiler chickens. The results showed that chromium picolinate at 0.5 ppm significantly (p<0.05) lowered the carcass fat level. Gut weight and carcass water content were increased as a result of chromium treatment. Body weight, plucked weight, carcass weight, abdominal fat pad weight, breast yield and feed efficiency were unaffected by chromium treatment. Leucine did not interact with chromium to effect lean growth. Dietary leucine above the recommended maintenance level (1.2% of diet) markedly (p<0.001) reduced the breast muscle yield. The addition of fish oil to broiler diets reduced (p<0.05) the abdominal fat pad weights compared to birds on linseed diets. Fish oil is believed to improve lean growth through the effects of long chain polyunsaturated fatty acids in lowering the very low-density lipoprotein levels and triglyceride in the blood, in the meantime increasing glucose uptake into the muscle tissue in blood and by minimizing the negative impact of the immune system on protein breakdown. The amount of fat in the diet (2% or 4%) did not affect body composition.

• Journal of Forest and Environmental Science
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• v.26 no.3
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• pp.171-179
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• 2010

Effect of chromium (Cr) stress on antioxidant enzyme activities and malondialdehyde (MDA) content were investigated in leaves and roots of mangrove (italic (L.) Druce) seedlings. Cr toxicity effects were also assessed on young seedlings. The seedlings were grown in green house condition for three months in nutrient solution with 0, 0.5, 1, 1.5, 2, 2.5, and 3 mg $L^{-1}$ $CrCl_3$. This study showed that Cr led to the change of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and activities at different concentrations. The activity of antioxidant enzymes in leaves of K. candel seedlings indicates that enzymes engaged in antioxidant defense in certain level especially in low concentration of Cr treatments. The activities of SOD and POD were activated by Cr in the root level, while CAT activity was inhibited. CAT activity decreased in response to high concentrations of Cr. In the present study indicated that SOD in root was active in scavenging the superoxide produced by Cr. Both in roots and leaves, an increase in malondialdehyde (MDA) content was observed with increase in metal concentration and exposure periods. Our finding indicated that the high concentration of excessive Cr supply may interfere with several metabolic processes of seedlings, causing toxicity to plants as exhibited by chlorosis, necrosis, photosynthetic impairing and finally, plant death.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.235-235
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• 2017

Chromium (Cr) toxicity is hazardous to the seed germination, growth, and development of plants. ${\gamma}$-Aminobutyric acid (GABA) is a non-protein amino acid and is involved in stress tolerance in plants. To investigate the effects of GABA in alleviating Cr toxicity, we treated eight-d-old mustard (Brassica juncea L.) seedlings with Cr (0.15 mM and 0.3 mM $K_2CrO_4$, 5 days) alone and in combination with GABA ($125{\mu}M$) in a semi-hydroponic medium. The roots and shoots of the seedlings accumulated Cr in a dose-dependent manner, which led to an increase in oxidative damage [lipid peroxidation; hydrogen peroxide ($H_2O_2$) content; superoxide ($O{_2}^{{\cdot}-}$) generation; lipoxygenase (LOX) activity], MG content, and disrupted antioxidant defense and glyoxalase systems. Chromium stress also reduced growth, leaf relative water content (RWC), and chlorophyll (chl) content but increased phytochelatin (PC) and proline (Pro) content. Furthermore, supplementing the Cr-treated seedlings with GABA reduced Cr uptake and upregulated the non-enzymatic antioxidants (ascorbate, AsA; glutathione, GSH) and the activities of the enzymatic antioxidants including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II), and finally reduced oxidative damage. Adding GABA also increased leaf RWC and chl content, decreased Pro and PC content, and restored plant growth. These findings shed light on the effect of GABA in improving the physiological mechanisms of mustard seedlings in response to Cr stress.

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.53-60
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• 2001

In this study, the heavy metals in tannery sludge were solidified by using cement and power plant fly ash. Solidification characteristics were discussed with the compressive strength and chromium leaching characteristics of solids. The compressive strength of cement mortar was increased by the amount of fly ash up to 24.3~33.8%, which was considered the results of pozzolanic reaction. When the content of fly ash was 20%, cement mortar showed the highest value $295kg/\textrm{cm}^2$ for 28 days curing. At early curing days, solidified chromium tannery sludge solids were showed lower compressive strength because of the retard on the hydration of cement, but the compressive strength was recovered to be more than $140kg/\textrm{cm}^2$ for 28 days curing regardless with the amounts of fly ash. Also, the results of leaching tests by KSM and TCLP method were showed that the solidified chromium sludge have leached out 0.3~2.2% and 11~17%, respectively.

• Journal of Welding and Joining
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• v.23 no.2
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• pp.75-80
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• 2005

The effect of chemical constituents of $(Cr,\;Fe)_7C_3$ carbide phase on its hardness in the chromium-carbide type Cr white iron hardfacing weld deposits has been investigated. In order to examine $(Cr,\;Fe)_7C_3$ carbide phase, a series of filler metals with varying chromium contents was used. The alloys were deposited once or twice on a mild steel plate using the self?shielding flux cored arc welding process. The hardness of $(Cr,\;Fe)_7C_3$ carbide phase was measured by the micro-Vickers hardness test. It was shown that hardness of $(Cr,\;Fe)_7C_3$ carbide phase increased with increasing Cr content in $(Cr,\;Fe)_7C_3$ carbide phase. This behavior of the hardness of $(Cr,\;Fe)_7C_3$ carbide phase was explained by the types of chemical bonds that hold atoms together in $(Cr,\;Fe)_7C_3$ carbide phase.

• Transactions of Materials Processing
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• v.6 no.2
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• pp.95-101
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• 1997

The thermal fatigue and wear properties of high speed steel roll which was recently developed were investigated by observing microstructure, by measuring mechanical and physical properties, by conducting thermal fatigue testing, and by measuring the amount of wear in actual mill. High speed steel roll had better thermal fatigue testing, and by measuring the amount of wear in actual mill. High speed steel roll had better thermal fatigue life than high chromium iron roll, which was due to lower carbide content, higher strength, and higher thermal conductivity. The amount of wear of high speed steel roll was nearly the same as that of high chromium iron roll in the first finishing stand, which was due to the oxide formation on the roll surface. However, in the third finishing stand, the wear resistance of high speed steel roll was 2~3 times as good as that of high chromium iron roll because the former had higher hardness at high temperature.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.455-460
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of PTFE on corrosion behavior of Cr-P plating, low carbon steel substrates are electroplated in Cr(III) baths without and with PTFE. Trivalent chromium carbon plating was electroplated from trivalent chromium sulfate-based baths with different PTFE dispersion contents. The study focused on the microstructure, PTFE content, roughness, and corrosion resistance of the Cr-P-PTFE composite plating. Scanning electron microscopy and atomic force microscopy images showed a smoother plating and a decrease in the surface roughness of the electrodeposited. The results demonstrate that PTFE eliminates the cracks within plating by reducing internal stress. Therefore, the corrosion resistance of Cr-P-PTFE composite platings were better than that of Cr-P alloy platings.

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.759-768
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• 2005

The study was designed to estimate the in vitro rumen by-pass rate of both chromium methionine chelate as an organic supplement and $ClCl_3$ as an inorganic supplement. Rumen by-pass rates of the supplements were evaluted by comparing ruminal metabolites in rumen fluid and Cr and methionine contents in the body of ruminal microorganism. For in vitro digestion examination, basic nutrients for ruminal microbes were supplied with 7g(DM) of feed, 2g of rice straw, and 2g of corn silage per each incubation jar. Three treatments including Control(no supplementation of Cr), T1(1000ppb supplementation of $ClCl_3$) and T2(chromium methionine chelate supplementation equivalent to 1000ppb of Cr content) were prepared with five replications per each treatment. pH of T2 was lower than that of Control and T1 regardless of incubation time. Ammonia content was higher in T2 than in Control and T1 during first 6 hours of incubation. However, the ammonia content in Control was remained low after 6 hours. Total volatile fatty acids(VFA) content in control was increased constantly as incubation time was extended. Therefore, VFA content in T1 and T2 were significantly lower (P<0.05) than those of Control. Dry matter recovery rate by ruminal microorganism was the lowest in T1, however ruminal microbial population was increased most efficiently in T2 during 12 hours of in vitro incubation. Cr concentrations in the body of ruminal microbes were not different(P>0.05) between Control and T2, but it was significantly high in T1(P<0.05). Contents of methionine and cystine in ruminal microbes also were not different between Control and T2(P>0.05), but it was relatively low in T1. Based on the above results, the chromium methionine chelate was believed to by-pass rumen and could remain intact until it reaches small intestine compared to inorganic chromium. This results implies that chromium methionine chelate could be more effective to function in the small intestine of ruminant animals.

• Journal of the Korean Dietetic Association
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• v.7 no.3
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• pp.258-266
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• 2001

The purpose of this study was to investigate the effect of dietary zinc on the carbohydrate metabolism and the serum content of magnesium and chromium in rats fed normal diet. Animals were divided into three groups by different dietary zinc levels which were low(15ppm), normal(30ppm) or high(60ppm). Serum glucose and Insulin concentrations were assessed by the glucose method and the radio immuno assay respectively. Serum zinc. magnesium and chromium contents were measured by Indectively Coupled Plasma(ICP). Results of the study were as follows : 1. Feed intake in a zinc deficiency group was significantly higher than that in other group, but the weight gain in high zinc diet group was significantly lower than in other groups. 2. There were no significant differences in liver, kidney and spleen weight. 3. Serum glucose, insulin and zinc concentrations were not significantly different among different dietary zinc groups, However serum magnesium and chromium concentrations were significantly decreased as the level of dietary zinc was increased.