This study investigated the distributions of heavy metals (Cd, Cu, Hg, Ni, Pb, and Zn) in agricultural soils near coal-fired power plants in Taean and Seocheon, South Korea, considering wind direction and distance from the plants. Additionally, pollution assessment for these heavy metals was conducted using the geoaccumulation index (Igeo) and enrichment factor. Results showed that heavy metal concentrations in the studied soil samples were below Korean environmental criteria for agricultural soil (Cd: 4, Cu: 150, Hg: 4, Ni: 100, Pb: 200, and Zn: 300 mg/kg). However, a significant proportion of samples exceeded average levels found in uncontaminated soils. Spatial distribution analysis revealed higher concentrations of Cd and Pb southwest of the Taean plant, influenced by prevailing northeast winds. In Seocheon, soils within 4 km of the plant exhibited elevated levels of Cd and Ni, suggesting coal combustion as a potential contamination source. Pollution assessment indicated that Cd and Pb in soils near both thermal power plants were more enriched by artificial activity compared to agricultural soils in control areas. Sequential extraction results showed that heavy metals in soils within 4 km of the Seocheon plant had higher proportions of exchangeable to organic-associated forms than soils beyond 4 km, indicating a risk of high bioavailability near emission sources. This study highlights the significant impact of coal-fired power plant emissions on soil contamination, emphasizing the need for continuous monitoring and management. Environmental policies should consider wind patterns and proximity to emission sources to effectively mitigate contamination risks.

Bacteria that had evolved over multiple generations under different visible light wavelengths were evaluated for their growth characteristics, resistance to various pH levels, and copper toxicity. The microorganism was isolated from soil at Chonnam National University and identified as Paenibacillus hunanensis with a similarity of 99.2%. Microbial culturing over 31 generations was performed under red, green, and blue light wavelengths, and the biomass of the bacteria grown in each generation was measured. Additionally, the biomass of bacteria grown at pH 4, 7, and 9 and copper concentrations of 10, 100, and 1000 ppb were determined using bacteria from the 31st generation. The results showed that the bacteria grown under red light exhibited higher activity over time. Bacteria grown under red light showed higher biomass at pH 4 and 7. Owing to the differences in resistance to copper, bacteria grown under blue light and in the absence of light exhibited lower biomass.

To assess the effectiveness of stabilization techniques on the transfer of As and heavy metals in soil to rice plant, pot experiments were conducted using organic (biochar), inorganic (limestone-steel slag mixture), and microbiological (sulfate-reducing bacteria, SRB) stabilizers.The results showed that microbiological treatments, particularly when SRB and SO 4 2-were co-injected, achieved higher stabilization efficiencies for Pb, Cu, and Cd in soil solution by the end of the experiments (153 days).The transfer of Pb, Zn, Cu, and Cd to the rice stems, leaves, and husks was reduced across all stabilization treatments.Notably, in husks, the stabilization efficiencies of Pb, Zn, Cu, and Cd ranged from 30% to 65% for organic stabilizers and 23% to 69% for inorganic stabilizers, surpassing those achieved with microbiological stabilizers.This study highlighted the potential of SRB as an effective alternative or supplementary stabilizer to conventional options such as limestone, steel slag, and biochar in reducing the transfer of heavy metals to crops in paddy soils.

The increasing global demand for Mn necessitates cost-effective recovery methods applicable to low- and medium-grade ores. Reductive bioleaching has emerged as a promising technique for Mn extraction from low-grade ores. This study aimed to simultaneously bioleach both Cu and Mn from low-grade ore obtained from Boleo, Mexico, using Acidithiobacillus thiooxidans. Additionally, the influence of activated coffee charcoal on the leaching process was examined. The biotic samples exhibited significantly higher Cu (70.6–71.9

To investigate the effect of changes in microbial communities on arsenic release in soil, experiments were conducted on arsenic- contaminated soils (F1, G7, and G10). The experiments involved three groups of the experimental sets; BAC: sterilized soil + Bacillus fungorum, , IND: indigenous bacteria, and MIX: indigenous bacteria + B. fungorum, , and incubated them for seven weeks using lactate as a carbon source under anaerobic conditions. The experimental results showed that higher concentrations of arsenic were released from the IND and MIX soils, where indigenous bacterial communities existed, compared to BAC. Significantly higher levels of arsenic were released from the G10 soil, which showed higher pH, compared to the F1 and G7 soils. In the G10 soil, unlike other soils, the proportion of As(III) among the released arsenic was also low. These results may be attributed to differences in microbial community composition that vary depending on the soil. By the seventh week, the diversity of microbial species in the IND and MIX soils had significantly decreased, with dominant orders such as Eubacteriales and Bacillales thriving. Bacteroidales in the seventh week of the MIX in the F1 soil, Rummeliibacillus in the seventh week of the IND and MIX of the G7 soil, and Enterobacterales in the IND and MIX of the G10 soil were dominant. At present, it is not known which mechanisms of microbial community changes affect the geochemical behavior of arsenic; however, these results indicate that microbiome in the soil may function as one of the factors regulating arsenic release.

This study aimed to isolate and characterize indigenous bacteria from cadmium-contaminated soil around a coal-fired power plant in Korea for their potential use in biosorption. The 16S ribosomal RNA analysis identified Enterobacter ludwigii G17-1 in the soil, exhibiting a remarkably high minimum inhibitory concentration (2,500 mg/L) for cadmium. The efficiency of cadmium biosorption was investigated under different pH levels (6-9), temperatures (15-40degree celsius), and initial cadmium concentrations (25-100 mg/L), using both live and dead G17-1. The live G17-1 strain exhibited a maximum biosorption efficiency of 50% for 25 mg/L cadmium at 24 hours, while the highest efficiency achieved with dead G17-1 was 48% at 1 hour. The biosorption capacity decreased as the initial cadmium concentration increased. These findings suggest that the isolated bacterium, E. ludwigii G17-1, holds potential for the bioremediation of cadmium-contaminated water and wastewater.

Heavy metal stabilization in soil was investigated using sulfate-reducing bacteria (SRB). Samples were collected from three agricultural soils near abandoned mines, and a nine-week batch experiment was performed following the classification of soils as ① non-sterile soil with SO42- (SO4), ② sterile soil with SRB (SRBo), and ③ non-sterile soil with SRB and SO42- (SS). Heavy metals were extracted using 0.1 N HCl or Mehlich, and the stabilization efficiency was evaluated by comparing the results to the control. Pb, Zn, Cu, and Cd (4–55%) had higher stabilization efficiency than the control in Mehlich extraction, while Pb (2–41%) had higher stabilization efficiency than the control in 0.1 N HCl extraction. The SS samples demonstrated a high stabilization efficiency (17–55%), whereas the SRBo samples (2–37%) showed a low efficiency. Dissolved As decreased in the supernatant of the SO4 and SS samples, especially in the high-As soil. These results indicate that incorporating SRB and SO42- into soil contaminated with heavy metals can effectively decrease the mobility of As and heavy metals.

An indigenous Cd-resistant bacterium, G17-2, was isolated from Cd-contaminated soil and characterized for its potential application to Cd biosorption. Phylogenetic analysis using 16S rRNA sequences revealed that G17-2 was affiliated to Pseudescherichia vulneris. When grown in yeast extract-peptone-dextrose medium, G17-2 showed the optimal growth at 30 °C and pH 7. Efficiency of Cd biosorption was investigated using live and dead G17-2 biomass at different initial Cd concentrations (25–100 mg/L), temperatures (15–40 °C), and pH (5–9). Under optimal growth conditions, the live G17-2 removed Cd with a maximum of 33.5 mg/g and showed 71.3

Many studies have been conducted to accurately predict the correlations between As and heavy metals content in contaminated soil and cultivated crops; however, due to the low correlation between the two, few clear results were obtained to date. This study aimed tocreate statistical models that predict the As content transferred from soil to polished rice, considering the physicochemical propertiesof the soil, as well as the total content and the single-extracted content of As in the soil. Predictive models were derived throughregression analysis while sequentially classifying soil samples according to pH, soluble As content by single extraction, and organicmatter content of the soil. The correlation coefficients between the As content in 80 polished rice and total As content and Mehlichsoluble As content in the soil were low, 0.533 and 0.493, respectively. However, the models derived after sequential classification of the soil by pH, a ratio of total As content to Mehlich soluble As content, and organic matter content greatly increased the predictivepower; (1) 0.963 for 13 soils with a pH higher than 6.5, (2) 0.849 for 15 soils with pH lower than 6.5 and a high ratio of As-Tot/As-Mehlich, (3) 0.935 for 30 soils with pH lower than 6.5, a high ratio of As-Tot/As-Mehlich, and organic matter content lower than 8.5%. The suggested prediction model of As transfer from soil to polished rice derived by soil classification may serve as a statistically significant methodology in establishing a rice cultivation standard for arsenic-contaminated soil.

최근 국내 고준위 방사성폐기물 심층처분을 위하여 지질학적 및 암반공학적 접근을 통한 지질환경 및 암반 특성 평가 파악 연구가 활발히 수행되고 있다. 그러나 방사성 핵종의 반감기가 길어 처분 후 상당히 오랜 기간 생물권으로부터 격리되어야 함을 고려할 때, 처분 이후 장기 운영과정에서 반드시 고려해야 할 사항은 처분용기 부식 등에 따른 핵종의 유출이다. 공학적 방벽을 통과한 핵종이 생물권을 오염시킬 위험성을 감소시키기 위해서는 지구화학적 및 지구미생물학적 고려가 반드시 수반되어야 한다. 이 논문에서는 지중 환경에서 우라늄의 지구화학적 거동에 미치는 미생물학적 영향에 관하여 미생물학적 환원 및 흡착의 이론, 최신 연구 현황, 심층처분이 실행되었을 경우 현장에 적용할 수 있는 기술 가능성 등에 대해 정리하였다. 부지 선정 및 처분장 설치 단계에 핵종의 지구화학적 거동에 미치는 지구미생물학적 영향이 함께 고려되면 처분장의 장기적 안정성이 보다 완전하게 확보될 수 있을 것이라 기대한다.

A dataset of chemical composition of groundwater in Korea including that in vein-type gold mines was compiled through literature review.Groundwaters were grouped, according to location, into 'adit groundwater' in the immediate vicinity of gold veins, 'surrounding groundwater' spatially separated from the veins in gold mines, 'normal groundwater' from non-mineralized granitic rocks, and 'deep groundwater' from a depth of 500 m or deeper.ANOVA indicated that adit groundwater showed statistically higher values of TDS, Ca, and SO 4 than the other groups.High SO 4 in the adit groundwater is likely due to sulfide minerals, and high Ca may be attributed to the occurrence of calcite as a fracture-filling mineral in the mines.Classification functions derived from discriminant analysis could distinguish between adit, surrounding, and normal groundwaters with a hit ratio > 92%.The classification functions may serve as an indicator for the exploration of unknown vein-type gold deposits through chemical analysis of the groundwater.

The effects of the physicochemical properties of soil such as soil pH, cation exchange capacity, and organic matter content on single extraction of Cd, Cr, Cu, Ni, Pb, and Zn using CaCl 2 , HOAc, HNO 3 , and DTPA were statistically investigated for 69 agricultural soils in Korea.Correlation analysis and multiple regression analysis were applied for soil samples which were grouped on the basis of average values of the physicochemical properties of the soil.Diluted HNO 3 extracted higher concentrations of Cr, Cu, Ni, and Pb when compared with the other extractants, however, similar amounts of Cd and Zn were extracted by HOAc with HNO 3 .The results of correlation analysis indicated that DTPA extraction showed a high correlation with other single and pseudo-total extraction methods, and the physicochemical properties of soil influenced the concentrations of heavy metals leached by the single extraction methods.In the case of Zn, high correlations between pseudo-total and the studied single extraction methods were observed.As a result of regression analysis, it was found that the physicochemical properties of the soil could explain up to 74% of variances of the single extraction results.These results indicate that the physicochemical properties of the soil can have a direct influence on the concentrations of heavy metals extracted by the single extraction methods.

박테리아인 Shewanella putrefaciens에 의한 V(V) 환원을 호기성 및 혐기성 조건에서 실험을 통하여 연구하였다. 전자공여체로는 젖산염을 공급하였다. 비생물학적 비교시료와 달리 S. putrefaciens를 접종한 시료에서는 두 조건에서 모두 시간이 경과하며 초기의 노란색이 점차 진한 초록색으로 변화하여 V(V)가 미생물학적으로 환원됨을 확인하였다. 미생물 시료에서는 침전물이 형성되었으며, XRD 분석 결과 이는 V(IV)를 함유한 광물인 것으로 나타났다. 또한 미생물 시료에서는 용액 내 총 용존 바나듐 함량이 시간에 따라 점차 감소하여, S. putrefaciens에 의해 용존 V(V)가 환원된 후 고체로 침전됨을 의미하였다. 이러한 결과는 바나듐 레독스 흐름전지 비용 중 많은 부분을 차지하는 V(IV) 전해질 제조에 미생물학적 V(V) 환원이 경제적으로 적용될 수 있는 가능성을 나타낸다.

The hyphae of Cladosporium sp. strain F1 (CFGR 2020-301-00084) were heavily encrusted with pre-synthesized uranium phosphate minerals under a wide range of pH conditions. SEM and TEM images showed that nanorods and nanoplates of uranium phosphate minerals at pH 4 and 5 and at pH 6, 7, and 8, respectively, were tightly adsorbed along the hyphae of Cladosporium sp. strain F1, while only a few uranium phosphate minerals were observed on the hyphae of Aspergillus niger VKMF 1119. Based on the physical mobility and chemical stability of uranium phosphate minerals under in situ oxidizing environmental conditions, the application of Cladosporium sp. strain F1 has potential as a novel strategy for the remediation of uranium contamination in sediments and aquifers under a wide range of pH conditions where larger amounts of phosphate are present in the environment.

Most studies on the bioleaching of heavy metals from contaminated soils using sulfur or iron-oxidizing bacteria have been conducted in laboratories under experimental conditions favorable for microbial activity. In this study, the applicability of bioleaching to field was investigated by examining various technical problems. Under the condition of a high solid-liquid ratio up to 1:3, the bioleaching showed a satisfactory efficiency. It resulted in high amounts of extracted heavy metals from fine soil particles under 200 mesh, and agitation of soil slurry led to an enhanced efficiency. For the preparation of a large volume of bacterial enrichment up to 1,000 L, a sequential increase of culture medium volume showed positive results, and subculture of bacteria in the final medium volume led to increase in bacterial activity. An input amount of Fe2+ less than 9 g/L also resulted in high bioleaching efficiency, thus a preliminary determination of appropriate Fe2+ amount may be required prior to field application.

Environmental geochemists have attempted to select proper soil extraction methods that deeply reflect the bioavailability, phytoavailability, and geochemical mobility of elements for the assessment of heavy metal contamination in soil. However, they are faced with complications during the process due to the complexity of heavy metal forms in soil and diversity in existing soil extraction methods. The present study summarizes the information on soil contaminated with heavy metals in Korea and current research trends on various single and sequential extraction techniques through a literature survey. This work is expected to serve as a fundamental reference for researchers to select an appropriate extraction method for evaluating bioavailability, phytoavailability, and geochemical mobility of heavy metals in soil.

The remediation of soil contaminated with heavy metals is an ongoing environmental concern. Paddy soils contaminated with Cd and Zn were collected from around abandoned metals mines in Korea. Limestone and steel slag were mixed with the collected soil, as amendments for Cd and Zn immobilization. Sequential extraction, lettuce cultivation and five single extraction methods were carried out to assess the effects on Cd and Zn immobilization using amendments. The exchangeable fraction of Cd and Zn was decreased and Fe–Mn oxides fraction increased by stabilization using amendments. In addition, the accumulation of Cd and Zn in lettuce decreased in treated soil and indicated the Cd and Zn immobilization effect in soil by the amendments. The extractable Cd and Zn by CaCl2 and Mehlich-3 in the untreated soils were higher than that of treated soils, whereas Cd and Zn extraction by ethylenediaminetetraacetic acid (EDTA), diethylene tetramine penta-acetic acid (DTPA) and toxicity characteristic leaching procedure (TCLP) has a small or no difference between the untreated and treated soils. The extraction results by CaCl2 and Mehlich-3 methods present reasonable results for Cd and Zn immobilization in soil than EDTA, DTPA and TCLP methods. Therefore, the choice of appropriate extraction method is very important when there is the assessment of Cd and Zn immobilization efficiency.

The effects of indigenous microbial consortium on removal of As from As-contaminated soil using an Fe(III)-reducing bacterium Shewanella putrefaciens were investigated under circumneutral pH condition. Sequential extraction of As revealed that more than 30% of As was associated with Fe(III)-(oxy)hydroxides in the soil. Bioleaching experiments were conducted anaerobically with a supply of lactate as a carbon source. The highest As removal efficiency (57.5%) was obtained when S. putrefaciens and indigenous bacterial consortium coexisted in the soil. S. putrefaciens and indigenous bacteria solely removed 30.1% and 16.4% of As from the soil, respectively. The combination of S. putrefaciens and indigenous bacteria led to a higher amount of labile As after microbial dissolution of Fe(III)-(oxy)hydroxides. After microbial treatment, soil quality represented by pH and organic content appeared to be preserved. The results indicated that the ecological and physiological understanding of the indigenous microbiome might be important for the efficient application of bioleaching technology to remove As from contaminated soils.

The effects of microorganism, akaganeite nanoparticles, and a mixture of both on the mobility of dissolved As(V) were investigated through experiments using columns filled with glass beads or natural, As-contaminated soil. In the case of glass beads column, nanoparticles enhanced the concentration of dissolved As in the effluent (0.48 mg/L) when compared with a control (0.17 mg/L) after 7 days. In microbial (0.04 mg/L) and mixture columns (0.08 mg/L), dissolved As concentrations were lower than the control. However, injection of microbe into the column filled with natural soil led to highly enhanced extraction of As from the soil (1.39 mg/L), whereas no significant difference in the amount of dissolved As was observed between nanoparticles (0.28 mg/L) and control (0.18 mg/L) columns. The results indicated that the interaction of As(V) with microorganism and Fe-nanoparticles may be controlled by the kind of geological media, i.e., crystalline aquifer or soil, contaminated with As(V).

The quantity of heavy metals in 44 surface and subsurface agricultural soils was determined for the area around a coal-fired power plant located in Boryeong, Chungnam Province. Although the concentrations of Cu, Hg, Ni, Pb, and Zn were below the warning criteria regulated by the Korean Soil Conservation Act, Cd in 16 samples exceeded the criterion. Geoaccumulation index showed that contamination intensity of Cd was significantly high while those of the other heavy metals were low. Enrichment factor indicated that Cd was loaded to the soil from anthropogenic source(s). However, sequential extraction of the soil samples revealed that most heavy metals including Cd existed as barely extractable phases, which represented low bioavailability of the heavy metals. Our results indicated that Cd contamination which was clearly due to artificial factors in the vicinity of the coal-fired power plant is unlikely to cause the deterioration of nearby ecosystem.