Geosciences Journal
Vol. 7, No. 4, p. 289−292, December 2003
Gallionella Ferruginea in ochreous precipitates from acid mine drainage in Donghae coal mine area, Korea
ABSTRACT: The morphology of Gallionella ferruginea and other microorganisms in the ochreous precipitates in acid mine drainage (AMD) were investigated using a scanning electron microscope (SEM) equipped with energy dispersive spectrometry (EDS). Min- eralogy of the precipitate containing the microorganism was char- acterized by X-ray diffraction analysis. The Gallionella ferruginea having twisted structure are found from precipitate samples on the stream bottom in AMD. Other microorganisms, characterized by coccus, bacillus, rod or cylindrical forms, are also observed in the precipitates. The ochreous preciptate was appeared reddish brown color (Munsell color 3.5YR hues) and consisted mainly of ferrihydrite with minor goethite.
Key words: Gallionella ferruginea, microorganisms, ochreous pre- cipitates, acid mine drainage, ferrihydrite
1. INTRODUCTION
The Donghae coal mine (longitude E128°56', latitude N37°06') located in the middle eastern part of the Korean peninsula had been actively mined from early 1960s to early 1990s. The mine was closed early 1990s due to eco- nomic and industrial reasons by Coal Industry Promotion Board. The altitude of the waste dump is approximately 1,000 m above sea level. Several hundred square meters of the surface are covered with waste rocks.
AMD results from the oxidation of sulfide minerals in coal or other mining waste is extremely acidic and enriched in iron, aluminum, sulfate and heavy metals such as lead, mercury, cadmium and manganese (Chapman et al., 1983;
Herr and Gray, 1995). The production of AMD from metal and coal mining operations typically results in the precip- itation of iron oxyhydroxides within implicated stream channels (Chapmen et al., 1983; Ferris et al., 1989; Bowell and Bruce, 1995). The genesis of precipitates in AMD has been ascribed to either microbial or chemical processes (Robbins et al., 1996). Iron precipitating bacteria such as Gallionella, Leptothrix, and Siderocapsa, require lower pH and Eh than for abiotic precipitation (Hanert 1992; Mouchet 1992). The Fe precipitating bacterium was found to affect the Fe oxidation/
precipitation process in which the precipitated Fe oxide was determined to be ferrihydrite (Fortin et al., 1996).
Gallionella ferruginea is a bean-shaped iron-oxidizing bacterium that produces a twisted stalk, often heavily incrusted with precipitated iron. It was first described by Ehrenberg in 1836 and has been placed among the iron bac- teria. The iron bacterium Gallionella ferruginea has been described from a variety of different habitats, including freshwater ferruginous mineral springs, shallow brackish waters, hydrothermal shallow water and also from the AMD environments (Hanert, 1992; Kim, 2002; Kim et al, 2002).
The AMD produced from the Donghae coal mine and the leachate through waste dumps enters directly into the local streams. The dissolved species may precipitate in the stream bottom under control of the chemical conditions of the streams. Many filament or rod-shaped structures were found in the precipitates.
The purposes of this study are to characterize the miner- alogical and morphological features of ochreous precipi- tates contained Gallionera ferruginea and other organisms.
In addition, the water chemistry for the formation of ochre- ous precipitate has been studied.
2. MATERIALS AND METHODS 2.1. Sampling
Each water sample was filtered through Whatman 0.45 µm membrane filters to remove particulate matter and stored in a 125 mL bottle. The water samples were acidified by high- purity nitric acid for metal concentrations. Ochreous sedi- ments were sieved in laboratory using a 63
µm plastic sieveto remove large detrital materials, concentrated by gravity settling and dried at room temperature.
2.2. Instrumental Analyses
Temperature, pH, electrical conductivity (EC) and redox potential (Eh) were measured at the sampling sites in the field. Metal concentrations were analyzed by Perkins-Elmer Optima 3000XL inductively coupled plasma emission spec- trometry (ICP-AES). Anions were analyzed by Dionex 4000i ion chromatograph (IC).
Jeong Jin Kim*
Soo Jin Kim
Sang Soo Lee } School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea
*Corresponding author: [email protected]
290 Jeong Jin Kim, Soo Jin Kim, and Sang Soo Lee
The mineral identification of the precipitates containing microorganism were made by X-ray powder diffraction (XRD). The XRD scans were conducted using a Rigaku Gei- gerflex RAD3-C, CoKα(λ=1.7890Å) radiation with automatic horizontal goniometer equipped with a scintillation counter and graphite monochromator. The precipitates were poorly crystal- line and thus, step scanned from 3 to 80
o2θ in step interval of 0.05
o2θ and with 1
οdivergence slit for 10 sec scanning time.
The morphological features of precipitates were studied using a JEOL-JSM-5200LV scanning electron microscope (SEM), equipped with a PV9880 STD energy dispersive X-ray spectrometer.
Bulk chemical compositions of precipitates were analyzed using a JSX-3200 energy dispersive X-ray fluorescence spectrometer (ED-XRF) at 30 kV and scanning time of 600 s.
3. RESULTS
3.1. Water Chemistry
Table 1 shows the field measurement data and chemical compositions of water samples. The temperatures of acid mine waters vary from 9.9−13.6
oC, and pHs from 5.30−
6.96 (mean 6.29). Further analyses revealed that the con- centrations of SO
42−in mine waters are between 108.6 and 237.3 mg/l, Mg between 14.8 and 23.8 mg/l, Si between 3.07 and 3.66, Ca between 72.9 and 82.3 mg/l, Mn between 0.7 and 1.8, and Fe between 1.1 and 17.8 mg/l.
3.2. Mineralogy of Precipitates
X-ray diffraction analysis shows that the ochreous pre- cipitate containing Gallionella ferruginea is composed mainly of ferrihydrite with small amounts of goethite (Fig.
1). The precipitates containing Gallionella in acid mine drainage usually referred to as a poorly ordered iron oxy- hydroysulfate such as schwertmannite (Kim et al., 2002).
X-ray diffraction patterns of ferrihydrite consists of six dif- fraction bands. In all the cases, the diffraction bands of fer- rihydrite are broad indicating that it is poorly crystallized but certainly not X-ray amorphous.
3.3. Chemistry of Precipitates
Table 2 shows bulk chemical compositions of ochreous precipitates containing Gallionella ferruginea. The chemi-
Table 1. Field measurement data and chemical compositions of water samples collected from the study areaSample Name
Field measurement data Chemical compositions (mg/L) Temp
(oC) pH EC (µS/cm) Eh
(mV) Cl− NO3− SO4−2
Na Mg Al Si K Ca Mn Fe Zn W0739 13.6 5.30 629 290 0.50 N.D 108.60 1.45 15.20 0.06 3.07 0.53 80.73 0.69 1.10 0.02 W0839 12.1 6.96 476 43 0.32 N.D 124.70 1.28 14.85 0.01 3.16 0.41 72.88 0.69 4.79 0.00 W0939 11.4 6.46 586 99 0.08 N.D 237.30 1.30 23.84 0.06 3.66 0.64 82.30 1.81 17.75 0.20 W1039 9.9 6.45 553 160 0.70 1.39 199.10 1.25 17.87 0.02 3.18 0.72 79.50 1.34 16.60 0.09 Fig. 1. X-ray diffraction patterns of ochreous precipitates con- tained Gallionella ferruginea and other microorganisms. Fh: fer- rihydrite, Gt: goethite.
Table 2. Bulk chemical analyses of reddish brown precipitate contained Gallionella ferruginea
Sample name Al2O3 SiO2 P2O5 CaO Fe2O3 SO3 H2O Total
S0739 1.25 0.67 0.01 0.67 78.82 0.58 16.86 98.84
S0839 0.45 1.77 0.19 1.26 76.59 0.66 18.89 99.80
S0939 0.63 1.11 0.01 0.77 74.89 0.63 20.12 98.16
S1039 1.12 0.51 0.02 0.06 78.37 2.49 17.23 99.79
Gallionella Ferruginea in ochreous precipitates 291
cal analysis of precipitates by ED-XRF shows 75
−81% Fe with small amounts of Al
2O
3(0.5−1.2%), SiO
2(1.5−1.7%) and CaO (0.1−1.3%) by weight.
3.4. Gallionella Ferruginea
The common conditions for Gallionella ferruginea growth are a neutral or a slightly acidic pH, an Eh of 200−300 mV and O
2levels of 0.1
−1.0 mg/l together with considerable amounts of CO
2(Hanert, 1992). Gallionella favors pH range from 5 to 8, and produces the oxidation product like hydrous ferric oxyhydroxides (Langmuir, 1997). The stalks of Gal- lionells ferruginea are composed of small parallel twisted threads which are characteristic of the bacteria Gallionella ferruginea (Ghiorse and Ehrilich 1992).
The Gallionella ferruginea can be easily recognized by its long ribbon-like tail which is produced out of one side of its rod- or bean-shaped cell. Numerous morphologically distinct microorganisms are present in the precipitates. Fig- ure 2 show various forms and unique shape of Gallionella in ochreous precipitates. The pH conditions for Gallionella ferruginea growth in the study area are from 5.30 to 6.96.
EDS analyses of Gallionella species in the ochreous pre- cipitate show that the cell wall is encrusted with Fe together with minor Si, Ca, Al and S. It suggests that bac- teria are capable of promoting the absorption of elements or the crystallization of Fe, Si, Ca and Al from the stream waters.
3.5. Other Microorganisms
SEM photographs of ochreous precipitates show abun- dant bacterium-like cocci or spheres of about 0.2
−0.5
µm in diameter, and rods or cylindrical bacilli of about 5−10
µmin length (Fig. 3). There are well-developed bacterial cells in association with poorly crystalline ferrihydrite with small amount of goethite as evidenced by X-ray powder diffrac- tion pattern. The filaments covered with abundant spherical bacteria are observed in the precipitates. According to EDS analysis, there is little difference in chemical compositions between cocci and bacilli, and they are enriched in Fe and Si with small amounts of Ca, Al and S. The stream water from which these biogenic materials precipitated contains high concentration of Fe, Ca, Si, Al, and SO
4.
4. DISCUSSION
Acid mine water growing Gallionella ferroginea in the Donghae coal mine area shows that pH vary from 5.30−
6.96 (mean 6.29), SO
42−between 108.6 and 237.3 mg/l, Mg between 14.8 and 23.8 mg/l, Si between 3.07 and 3.66, Ca between 72.9 and 82.3 mg/l, and Fe between 1.1 and 17.8 mg/l.
The ochreous precipitates containing Gallionella ferrug- inea and other microorganisms are composed mainly of fer- rihydrite with a small amount of goethite.
The results of chemical analysis for ochreous precipitates
Fig. 2. SEM micrographs and EDS curves of various shape of Gallionella in ochreous precipitates.292 Jeong Jin Kim, Soo Jin Kim, and Sang Soo Lee
are shown 75−81% Fe and 16−25% H
2O with small amounts of Al
2O
3(0.5
−1.2%), SiO
2(1.5
−1.7%) and CaO (0.1
−1.3%) by weight.
The ochreous precipitate, composed mainly of ferrihydrite, shows abundant bacterium-like cocci or spheres of about 0.2−0.5
µm in diameter, and rods or cylindrical bacilli ofabout 5−10
µm in length. The spherules and rods are com-posed mainly of Fe with minor Si, Ca, Al and S. The stream water from which these biogenic materials precipitated con- tains high concentrations of Fe, Ca, Si, Al, and SO
4. Twisted stalks and other forms characteristic of Gallionella ferruginea are found from the precipitates. The cell surface of this bacterium contains a large amount of Fe with minor Si, Al, Ca and S. It suggests that bacteria are capable of pro- moting the absorption of elements or the crystallization of Fe, Si, Ca and Al from the stream waters.
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Manuscript received May 23, 2003 Manuscript accepted December 8, 2003
