Ju-Yong Kim

Metal contamination of soils and dusts in Seoul metropolitan city, Korea

To investigate the dispersion patterns and the characteristics of heavy metal contamination due to urbanisation and industrialisation, soils and dusts collected from the Seoul area were analysed for Cu, Pb, Zn and Cd. The metal concentrations in most soils and dusts are higher than the world averages. The pollution index ((Σ Metal concentrations in soils/Permissible level for metal)÷(Number of metals)) of soils and dusts is > 1 in most of the Seoul area, a result that concurs with the industrialisation and urbanisation index of the Seoul area. The soils are contaminated with Cu, Zn, Cd and particularly Pb. This suggests that the contamination of the soils in the Seoul area are mainly caused by vehicular emissions. The pollution index of soil is the highest in the Kuro area where Cu and Zn contamination in soils are due to the indigenous brass and bronze factories. From the discriminant analysis, the Seoul area may be partitioned into control, traffic and industrialized areas by the metal concentrations in the order of Zn > Cu > Pb.

ASSESSMENT OF As AND HEAVY METAL CONTAMINATION IN THE VICINITY OF DUCKUM Au-Ag MINE, KOREA

In order to assess the potential of As and heavy metal contamination derived from past mining activity and to estimate the human bioavailability quotients for As and heavy metals. Tailings, soils and crop samples were collected and analysed for As, Cd, Cu, Pb and Zn. The mean concentrations of As, Cd, Cu, Pb and Zn in the tailings were 68.5, 7.8, 99, 3,754 and 733 µg g−1, respectively. Maximum Pb concentration in tailings was up to 90 times higher than its tolerable level. The concentrations of these metals were highest in the soils from the dressing plant area, and decreased in the order: farmland soil to paddy soil. In particular, some of the soils from the dressing plant area contained more than 1% of Pb and Zn. The pollution index ranged from 0.19 to 1.93 in paddy soils, and from 1.47 to 3.60 in farmland soils. The average concentrations of heavy metals in crops collected from farmland were higher than those in rice stalks or rice grains, and higher than the internationally accepted limits for vegetables. Element concentrations extracted from farmland soils within the simulated human stomach for 1 h are 9.4 mg kg−1 As, 3.8 mg kg−1 Cd, 37 mg kg−1 Cu, 250 mg kg−1 Pb and 301 mg kg−1 Zn. In particular, the extracted concentrations of Cd, Pb and Zn are in excess of the tolerable levels. The results of the simple bioavailability extraction test (SBET) indicate that regular ingestion (by inhalation and from dirty hands) of soils by the local population could pose a potential health threat due to long-term toxic element exposure.

Abdominal amyloidosis: spectrum of radiological findings.

Amyloidosis is a disease characterized by the deposition of fibrillar protein amyloid of beta-structure in organs or tissues. It is usually classified as either a primary disease or secondary to a co-existent condition, such as rheumatoid arthritis, tuberculosis, or neoplasm (particularly multiple myeloma or renal cell carcinoma). Amyloid protein deposition can be seen in a variety of organs though it occurs with higher frequency in the gastrointestinal tract, kidney, and heart. Amyloidosis can have a wide spectrum of manifestations in nearly every abdominal organ. Some of these, for example, multiple cystic submucosal masses of the stomach, amyloidosis of the gallbladder, and dirty soft tissue infiltration of the subcutaneous fat, have not yet been covered in the radiological literature. The combination of various imaging techniques and the identification of characteristic computed tomography (CT) hepatic features may help in the differentiation of amyloidosis from other infiltrative diseases; however, confirmative diagnosis can usually only be achieved by tissue biopsy.

Pollution of a water course impacted by acid mine drainage in the Imgok creek of the Gangreung coal field, Korea

Abstract The purposes of this study are to (i) determine the geochemical characteristics of Imgok creek impacted by acid mine drainage (AMD) generated from abandoned coal mines, (ii) to assess the pollution of heavy metals in the stream sediments and soils, and (iii) to identify the chemical form of Fe precipitates collected in the study area where there are 4 abandoned coal mines, which belong to the Grangreung coal field at the eastern part of Korea. AMD generated from mine adits and coal refuse piles shows low pH, and high concentrations of Fe, Al and SO 4 , especially in the Youngdong coal mine. In Imgok creek, pH values increased, and total dissolved solids (TDS) values decreased with distance. The concentrations of toxic heavy metals and major cations except Fe decreased by dilution, but the concentration of Fe decreased rapidly due to the formation of precipitates. The quality of groundwater samples did not exceed the Korean drinking-water standard. In the stream sediments, the concentrations of Fe are relatively high in the Youngdong tributary and Imgok creek, but the concentrations of heavy metals are similar to those of unpolluted sediments. Pollution indices of agricultural soils range from 0.28 to 0.47. Yellowish red Fe precipitates collected in the study area turned out to be amorphous or poorly crystallized minerals (determined by X-ray diffraction patterns and Fe ox /Fe tot ratios) and to contain chemically bonded SO 4 and OH [determined by infra-red (IR) spectral analysis]. With these, the mol ratios of Fe/S ranging from 4.6 to 6.1 determined by electron probe micro-analysis (EPMA) in precipitates strongly support the existence of schwertmannite.

Sources and Fate of As in the Environment

ABSTRACT Arsenic is present in a variety of environmental media including minerals, rocks, sedimentary deposits, soil, water and plants. It tends to be transported and exchanged among these environmental components. Arsenic can be released to the environment through human activities including mining exploitation, metal smelting, waste incineration, coal combustion and the use of pesticides, herbicides, crop desiccants, wood preservatives, and food additives for livestock containing arsenic compounds. Bioaccumulation of arsenic occurs in some aquatic organisms. The existence of a biological methylation/demethylation cycle for arsenic results in the presence of various forms of both organic and inorganic arsenic in the environment. Arsenic in water can undergo a complex series of transformations, including oxidation-reduction reactions, ligand exchange, precipitation and biotransformation. Acid mine drainages as well as mine tailings are of great concern due to their extremely high arsenic concentrations observed and reported.

Phytoremediation of soil contaminated with heavy metals using Brassica napus

In order to examine the feasibility of utilizing oil extracted from plant seed in the contaminated areas, the phytoremediation applicability of soils contaminated with heavy metals and its follow-up result in the production of biodiesel was investigated. Brassica napus was chosen as the main target plant because it is widely used for phytoremediation and is an advantage of biodiesel production. From the perspective of heavy metal concentrations in Brassica napus, plants grown in contaminated soil show significantly higher concentration than those in non-contaminated soil. From the results of sequential extraction analysis, it was also found that heavy metal concentrations in plant may be increased with the enhancement of phyto-available fraction of heavy metal in the soil. These results show the feasibility of oil production extracted from Brassica napus, which was grown in heavy metal-contaminated soil. The seed contains a low concentration of most kinds of heavy metals except Zn in soil, which is essential for seed growth. The results of oil analysis show that more than 50% of heavy metal remained in the residues. Therefore, the application of phytoremediation by Brassica napus is a feasible technique for the removal of heavy metals and its following biodiesel production as an energy source is acceptable.

Progress in Earthworm Ecotoxicology

Earthworms are regarded as one of the most suitable animals for testing the toxicity of chemicals in soils and have been adopted as standard organisms for ecotoxicological testing. In several guidelines concerning earthworm toxicity tests, Eisenia fetida/andrei (E. fetida/andrei) was chosen because it can be easily cultured in the laboratory and an extensive database on the effects of all classes of chemicals exists for this species. Acute and chronic toxicity tests have been used traditionally to assess the toxicity of contaminants, with mortality and changes in biomass, reproduction rates and behavioral responses representing endpoints. Moreover, the avoidance behavior test (AVT) using earthworm is under development and standardization, which records the ability of earthworms to choose or avoid a certain soil. Recent studies have shown that neutral red retention time (NRRT) has the potential for a rapid assessment of the toxic effects for earthworms of soils contaminated with heavy metals and metalloids. Toxicity is the apparent expression of the metal accumulation in earthworm body. The uptake, accumulation and elimination properties of metals by earthworm are the major part of toxicology, which is called toxicokinetics. Geochemical factors may have signifi cant effects on metal transport or bioavailability. Prediction models for metal accumulation and toxicity in soils are being developed based on metal bioavailability. In this study, methodologies and research trends in earthworm toxicity are reviewed for understanding metal bioavailability. Toxicity prediction models are introduced for terrestrial environment and several studies are referred to understand the role of geochemistry in toxicology.

Robust SOI process without footing for ultra high-performance microgyroscopes

A microgyroscope with flat bottom surfaces is fabricated by combining the SOI (silicon on insulator) method with the SBM (sacrificial bulk micromachining) process [1/spl sim/3]. Roughened bottom surfaces and loose silicon fragments are common problems in deep silicon RIE (Reactive Ion Etching) using SOI wafers. In this paper, the silicon fragments are removed and the roughened bottom surfaces are smoothed by the SBM process to achieve robust performance. A gyroscope is fabricated by the proposed method. The measured noise equivalent resolution is 0.0044/spl deg//sec, and the measured bandwidth is 12.8 Hz. The linearity of output is within 7.4% for /spl plusmn/50/spl deg//sec range.

Natural attenuation of arsenic in the wetland system around abandoned mining area

Mechanisms of natural attenuation of arsenic (As) by wetland plants may be classified by plant uptake and adsorption and/or co-precipitation by iron (oxy)hydroxide formed on the root surface of plants or in rhizosediment. A natural Cattail (Typha spp.) wetland impacted by tailings containing high levels of As from the Myungbong abandoned Au Mine, South Korea was selected, and the practical capability of this wetland to attenuate As was evaluated. The As concentrations in the plant tissues from the study wetland were several-fold higher than those from control wetland. SEM-EDX analyses demonstrated that iron plaques exist on the rhizome surface. Moreover, relatively high As contents bonded with hydrous iron oxides were found in the rhizosediments rather than in the bulk sediments. It was revealed through the leaching and sequential extraction analyses that As existed as more stable forms in the wetland sediment compared with adjacent paddy soil, which is also contaminated with As due to input of mine tailings. The As concentration ratios of extracted solution to sediment/soil represented that the wetland sediment showed significant lower values (10-fold) rather than the paddy soil with indicating high As stability. Also, As in the wetland sediment was predominantly bonded with residual phases on the basis of results from sequential extraction analysis. From these results, it is concluded that transformation of As contaminated agricultural field to wetland environment may be helpful for natural attenuation until active remediation action.

Adsorption properties of soil humic and fulvic acids by hematite

Abstract The adsorption isotherms and their size fractionations of soil humic and fulvic acids (HA and FA, respectively) were determined at pH 7, 9.2 and 11, where the surfaces of the hematite are positively, neutrally and negatively charged, respectively. The Mw, Mn and polydispersity in the solution after adsorption were measured in order to investigate the preferential adsorption trend of the HA and FA. The measured adsorption was consistent with the adsorption from Langmuir isotherm fitting. The adsorption of HA onto the hematite was more favorable than that of FA due to the preferential adsorption of high molecular weight fractions and the greater hydrophobicity. As the solution pH increased, the preferential adsorption for the high molecular weight fractions partially deviated with higher polydispersity. This indicates that the adsorption of the HA and FA onto hematite was affected by the molecular conformation, and the electrostatic repulsion between the HA and FA and the hematite lead to the kinetically sluggish adsorption. Further, it implies that the adsorption properties of soil organic matter may affect the adsorption of metal and metalloid onto the adsorbent like iron-oxide in the geochemical environments.