• Economic and Environmental Geology
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• v.42 no.5
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• pp.413-426
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• 2009

The study was conducted to investigate the effects of indigenous bacteria on geochemical behavior of toxic heavy metals in contaminated paddy soil near an abandoned mine. The effects of sulfate amendment to stimulate microbial sulfate reduction on heavy metal behaviors were also investigated. Batch-type experiments were performed with lactate or glucose as a carbon source to activate indigenous bacteria in the soil under anaerobic condition for 100 days. Sulfate (250 mg/L) was artificially injected at 60 days after the onset of the experiments. In the case of glucose supply, solution pH increased from 4.8 to 7.6 while pH was maintained at 7~8 in the lactate solution. The initial low pH in the case of glucose supply likely resulted in the enhanced extraction of Fe and most heavy metals at the initial experimental period. Lactate supply exerted no significant difference on the amounts of dissolved Zn, Pb, Ni and Cu between microbial and abiotic control slurries; however, lower Zn, Pb and Ni and higher Cu concentrations were observed in the microbial slurries than in the controls when glucose supplied. Sulfate amendment led to dramatic decrease in dissolved Cr and maintenance of dissolved As, both of which had gradually increased over time till the sulfate injection. Black precipitates formed in solution after sulfate amendment, and violarite($Fe^{+2}{Ni^{+3}}_2S_4$) was found with XRD analysis in the microbial precipitates. Conceivably the mineral might be formed after Fe(III) reduction and microbial sulfate reduction with coprecipitation of heavy metal. The results suggested that heavy metals which can be readily extracted from contaminated paddy soils may be stabilized in soil formation by microbial sulfate reduction.

• Economic and Environmental Geology
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• v.50 no.3
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• pp.215-224
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• 2017

Arsenic (As) is known to be the most toxic element and frequently detected in groundwater environment. Inorganic As exists as arsenite [As(III)] and arsenate [As(V)] in reduced and oxidized environments, respectively. It has been reported that the toxicity of arsenite is much higher than that of arsenate and furthermore arsenite shows relatively higher mobility in aqueous environments. For this reason, there have been numerous researches on the process for oxidation of arsenite to arsenate to reduce the toxicity of arsenic. In particular, photooxidation has been considered to be simple, economical, and efficient to attain such goal. This study was conducted to evaluate the applicability of naturally-occurring goethite as a photocatalyst to substitute for $TiO_2$ which has been mostly used in the photooxidation processes so far. In addition, the effects of several factors on the overall performance of arsenite photocatalytic oxidation process were evaluated. The results show that the efficiency of the process was affected by total concentration of dissolved cations rather than by the kind of those cations and also the relatively higher pH conditions seemed to be more favorable to the process. In the case of coexistence of arsenite and arsenate, the removal tendency by adsorption onto goethite appeared to be different between arsenite and arsenate due to their different affinities with goethite, but any effect on the photocatalytic oxidation of arsenite was not observed. In terms of effect of humic acid on the process, it is likely that the higher concentration of humic acid reduced the overall performance of the arsenite photocatalytic oxidation as a result of competing interaction of activated oxygen species, such as hydroxyl and superoxide radicals, with arsenite and humic acid. In addition, it is revealed that the injection of oxygen gas improved the process because oxygen contributes to arsenite oxidation as an electron acceptor. Based on the results of the study, consequently, the photocatalytic oxidation of aqueous arsenite using goethite seems to be greatly feasible with the optimization of process.

• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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• pp.77-92
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• 2014

Fermented foods have often been implicated as causative agents in poisoning due to toxic levels of biogenic amines. Cheese, a milk-based fermented food, is the product most likely to contain potentially harmful levels of biogenic amines, such as tyramine, histamine, putrescine, and so on. Recently, the risk awareness of a dietary uptake of high loads of biogenic amines has increased. Hence, we here review the published literature on several factors known to affect the biosynthesis of biogenic amines and their accumulation in milk-based foods. Furthermore, with regard to risk analysis, we discuss the control of factors related to the synthesis and accumulation of biogenic amines as a means to reduce their incidence in milk-based products, and thus to increase food safety.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.310-315
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• 2011

BACKGROUND: Heavy-metal pollution represents an important environmental problem due to the toxic effects of metals, and their accumulation throughout the food chain leads to serious ecological and health problems. METHODS AND RESULTS: Optimum conditions in continuous-flow stirred tank reactor (CSTR) and packedbed column contactor (PBCC) using brown seaweed biosorbent were investigated. Under optimum conditions from both lab-scale biosorbent systems, removal efficiency of copper (Cu) in a large-scale PBCC system was investigated. Removal capacity of Cu using brown seaweed biosorbent in a lab-scale CSTR system was higher than that in a lab-scale PBCC system. On the other hand, over 48 L/day of flow rate in Cu solution, removal efficiency of Cu in a lab-scale PBCC system was higher than that in a lab-scale CSTR system. Optimum flow rate of Cu was 24 L/day, optimum Cu solution concentration was 100 mg/L. Removal capacity of Cu at different stages was higher in the order of double column biosorption system > single column biosorption system. Under different heavy metals, removal capacities of heavy metal were higher in the order of Pb > Cr > Ni > Mn ${\geq}$ Cu ${\geq}$ Cd ${\fallingdotseq}$ Zn ${\geq}$ Co. Removal capacity of Cu was 138 L in a large-scale PBCC system. Removal capacity of Cu a large-scale PBCC system was similar with in a lab-scale PBCC system. CONCLUSION(s): Therefore, PBCC system using brown seaweed biosorbent was suitable for treating heavy metal wastewater.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.316-322
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• 2011

BACKGROUND: Pesticides concentration was monitored in 50 agricultural lakes, and ecological risk for aquatic organism was assessed using risk quotient (RQ) and probabilistic methods. METHODS AND RESULTS: Pesticides concentrations detected in 50 agricultural lakes during peak season (June and September) were in the range of $0.17{\sim}0.99{\mu}g/L$. The RQ for algae and the other species was estimated to be 0.25 and below 0.01, indicating medium risk and no risk. Oxadiazon predominantly contributed to RQ value of 99% for algae, fishes, and amphibians. In terms of hazardous concentration at 5% of species ($HC_5$), ecological risk quotients (ERQ) for oxadiazon ranged from 0.18~0.33, showing a medium risk level. Overall, the concentrations of pesticides were much lower than $HC_5$), value. Probability of combined ecological risk for pesticides ranged from 1.82% to 2.41%. CONCLUSION(s): Combined ecological risk probability did not exceed the acceptable level of 5%, indicating no ecological risk for selected aquatic species. This study suggests that regular ecological risk assessment (ERA) will be required to protect and manage an agricultural lake. Not only ERA at screening level by comparing exposure with toxic effects for aquatic species also advanced ERA technique considering species in indigenous to Korea, chronic toxicity, pulse dose, fate, and environmental factors should be required.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.60-65
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• 2008

Current soil remediation principles for toxic metals have some limitations even though they vary with different technologies. An alternative technology that transforms hazardous substances into nonhazardous ones would be environmentally beneficial. Objective of this research was to assess optimum conditions for Cr(VI) reduction in soils as influenced by ZVI(Zero-Valent Iron), organic matter and moisture content. The reduction ratio of Cr(VI) was increased from 37 to 40% as organic matter content increased from 1.07 to 1.75%. In addition, Cr(VI) concentration was reduced as soil moisture content increased, but the direct effect of soil moisture content on Cr(VI) reduction was less than 5% of the Cr(VI) reduction ratio. However, combined treatment of ZVI(5%), organic matter(1.75%) and soil moisture(30%) effectively reduced the initial Cr(VI) to over 95% within 5 days and nearly 100% after 30 days by increasing oxidation of ZVI and concurrent reduction of Cr(VI) to Cr(III). The overall results demonstrated that ZVI was effective in remediating Cr(VI) contaminated soils, and the efficiency was synergistic with the combined treatments of soil moisture and organic matter.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.799-810
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• 2004

This study was conducted to determine effects of spent composts of Se-enriched mushrooms (Se-SMC) as the dietary selenium source on carcass characteristics, plasma glutathione peroxidase(GSH-Px) activity and Se deposition in finishing Hanwoo steers. In combination with both Se-SMC and normal SMC, experimental treatment diets were formulated to contain 0.1, 0.3, 0.6 and 0.9 ppm of Se on a dry matter basis. A total of 20 finishing Hanwoo steers (average BW = 613 kg, average age = 20 to 24 mo) were allotted to treatments in four groups of five steers per pen for 12 wk preceding slaughter. While the experiment is employed, blood samples were taken to analyze Se concentration and GSH-Px activity, and muscle and liver samples were collected for analyses of Se contents in their tissues after slaughter. DMl and BW gain were not affected by dietary Se level and any toxic symptoms in treatments with a higher level of Se were not observed. No differences were noted for carcass characteristics. Se concentration in whole blood and plasma GSH-Px activity were linearly increased with the increasing level of dietary Se (P < 0.01). Se content in the hind leg for Se-SMC supplemented groups significantly increased (P < 0.05) upon dietary Se level, with 0.27, 0.37, 0.40 and 0.46 !1g1g dry, respectively. However, Se content in the loin was not affected by dietary Se levels. Se content in the liver was significantly increased(P < 0.05) as dietary Se increased, with 0.79, 1.40, 2.39 and 3.10 !1g1g dry, respectively. These results suggested that Se in the Se-SMC was highly bioavailable, and Se-SMC might be used not only as an inexpensive way of providing Se for ruminants but also as another way of producing Se-fortified beef.

• Journal of Veterinary Clinics
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• v.10 no.1
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• pp.111-130
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• 1993

Lead toxicity was evaluated in forty-five cats on a balanced diet, Treated with 0(control), 10, 100(low), 1, 000, 2, 000, and 4, 000(high) ppm of lead acetate orally on a body weight basis. The objectives were to establish toxic dosage level of leaf in cats, to characterize changes in behavior and clinical pathology, and to demonstrate what blood lead concentrations correlate with the known dosages of lead. Some high dose cats showed projectile vomiting, hyperactivity, and seizures. The growth rates did not appear to be altered in any of the dosed groups. Normal blood lead concentration in cats were lower than that of humans, dogs, and cattle. Blood lead concentrations of 3 to 20$\mu\textrm{g}$/100$m\ell$ could be termed a 'subclinical' range in the cat. Clinical lead toxicity in cats may have blood lead concentrations ranging 20 to 120$\mu\textrm{g}$/100$m\ell$. Zinc protoporphyrin concentrations were proportional to lead dosages and a significant ZPP elevation, greater than 50$\mu\textrm{g}$/100$m\ell$, may be indicative of clinical lead toxicity. The enzyme aminolevulinic acid dehydratase showed an inverss dose response relationship for all lead dosages and a significant ZPP elevation, greater than 50$\mu\textrm{g}$/100$m\ell$, may be indicative of clinical lead toxicity. The enzyme aminolevulinic acid dehydratase showed an inverse dose response relationship for all lead dosages and appears to be a good indicator of lead exposure in cats. Urinary aminolevuliruc acid concentrations generally increased with lead dosage, but individual values varied. Hair lead concentrations rose proportionately to lead dosages. Lead at least in high doses appears to inhibit chemotactic activity of polymorphonuclear cells and monocytes. No consistent dose response relationships were observed in hemoglobin, RBC, WBC, neutrophil, lymphocyte, monocyte, and eosinophil counts. There were no consistent dose related changes in total protein, plasma protein, BUN, and ALT values. Reticulocyte counts did not increase significantly in most lead dosage levels, and are probably of little value in diagnosing lead toxicity in cats. The fact that no significant changes were found in nerve conduction velocities may support that there was no segmental demyelination resulting from lead ingestion. The lethal dose in cats appear to range from 60 to 150mg/kg body weight. A reliable diagnosis of lead poisoning can be made utilizing blood lead, ZPP, and ALAD, and hair lead.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.507-513
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• 2004

Aflatoxins are produced mainly by Aspergillus flavus and Aspergillus parasiticus that grow in improperly stored cereals. Aflatoxin B1 ($AFB_1$) is a potent hepatocarcinogen in a variety of experimental animals including human beings. In spite of a high attention to the hepatocarcinogenecity of $AFB_1$, the relative toxicity of aflatoxins ($AFB_2$ and $AFG_1$) is not fully clarified. Sprague-Dawley male rats were orally administered with $AFB_1$, $AFB_2$, and $AFG_1$ at the dose of 250 ${\mu}g/kg$ (additionally including a dose of $1250{\mu}g/kg $ for $AFB_1$) body weight. Animals were then killed at 12, 24 or 48 hrs following aflatoxin exposure. Subsequently the immunohistochemical examination of p53, cytochrome p450 1A1 (CYP450 1A1), and glutathione-S-transferase placental form (GST-P) were performed. The level of the 8-OxodG in the liver was determined. Expressions of CYP450 1A1 and p53 were high in the liver of rats through 48 hrs after treatment of $AFB_1$ at the single dose of $250{\mu}g/kg $. This pattern was more clear as increasing doses. The treatment of $AFB_2$ and $AFG_1$ did not affect the expression of CYP450 1A1 but it caused weak expression of p53. The activity of GST were not found in the liver of rats treated with aflatoxins. The formation of 8-OxodG by $AFB_1$ increased in a dose-dependent manner up to 24 hrs after a single treatment of $AFB_1$ thereafter decreased to the level of control. The treatment of $AFB_2$ and $AFG_1$ did not affect the levels of 8-OxodG in the liver of rats with increasing time. These results in the present study indicate that $AFB_1$ among aflatoxins with low comparable levels is the most toxic as determined by early biomarkers such as CYP450 1A1, p53, GST-P, and 8-OxodG.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.5 no.2
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• pp.174-180
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• 2002

Purpose: Ursodeoxycholic acid (UDCA) is known to decrease hepatic injury by promoting the biliary secretion of retained toxic endogenous bile acids in hepatobiliary diseases complicated by total parenteral nutrition (TPN). However, most studies have focused on treatment for complications after TPN. We investigated the preventive role of early administration of UDCA in TPN-induced hepatobiliary complications by a randomized, double-blind, placebo-controlled trial. Methods: Between May 2000 and May 2002, thirteen patients, who were given TPN more than 10 days in the hospital, were assigned randomly to two groups. One was the case group (7 patients) who were given UDCA simultaneously with TPN regimen, and the other, the control group (6 patients) who were given placebo. Their age ranged from 1 day to 13 years. They were affected with diseases impossible for enteral nutrition, such as prematurity, cerebral palsy, chronic diarrhea, anorexia nervosa, pancreatitis, and cyclic vomiting. The duration of TPN ranged from 10 to 70 days. Hematologic parameters including liver function test were measured at regular intervals, and the duration, composition, administration rate, total calorie of TPN were recorded. The serum levels of total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase were compared between groups after cessation of the study. Results: The autoregressive coefficient of the control group was 0.4419 (p=0.0651) in bilirubin, -0.0431 (p=0.7923) in AST, 0.2398 (p=0.2416) in ALT, and 0.2459 (p=0.1922) in alkaline phosphatase by mixed procedure model when the parameters were referred to the case group. Conclusion: The serum level of total bilirubin did not increase in comparison with that of the control group, but statistically insignificant, when both TPN and UDCA were administered simultaneously from the beginning.