AN EVALUATION OF THE USE OF INDIGENOUS BACTERIA AS A GROUNDWATER TRACER IN FRACTURED BEDROCK

The microbially mediated recovery of valuable metals contained in mining waste presents an economical alternative to conventional hydrometallurgical processes. In order to investigate the effect of bacterial adaptation and biological oxidation on bioleaching, the microbially mediated bioleaching of a pyrrhotite sample from mine waste, with indigenous bacteria existing in acid mine drainage, was studied. The indigenous bacteria were sub-cultured repeatedly for iron adaptation, and Acidithiobacillus ferrooxidans was identified as the dominant member of the microbial consortium. The point of zero charge (PZC) of pyrrhotite sampled from mine waste was determined as 3.0. The performance of bioleaching by contact and non-contact biological oxidation was compared by conducting bioleaching under different initial pH (pHini) conditions (2.8 and 3.2). Negatively charged bacteria could be attached onto the pyrrhotite, which has a positive surface charge at lower pHini (2.8) than the PZC (3.0). Bacteria attachment and corrosion pits on the surface of the pyrrhotite residues were observed at pHini of 2.8. Under bacteria-adapted conditions, the leaching concentration of Fe (44.2 mg/L) at pHini of 2.8 was 2.1 times greater than that (21.3 mg/L) at pHini of 3.2. Under non-adapted bacteria conditions, the extent of Fe leaching was not significantly different between the pHini of 2.8 and 3.2. This could be attributed to the fact that the adapted bacteria could more easily attach onto the pyrrhotite surfaces at pHini 2.8, allowing contact biological oxidation during the bioleaching experiments. We demonstrate here that the bioleaching of pyrrhotite could increase Fe recovery through bacterial adaptation and contact biological oxidation.

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Three-dimensional hydrostratigraphy and groundwater flow models in complex Quaternary deposits and weathered/fractured bedrock: evaluating increasing model complexity

Hydrogeology Journal ◽

10.1007/s10040-020-02299-4 ◽

2021 ◽

Author(s):

Susanne Charlotta Åberg ◽

Annika Katarina Åberg ◽

Kirsti Korkka-Niemi

Keyword(s):

Groundwater Flow ◽

Three Dimensional ◽

Model Complexity ◽

Quaternary Sediments ◽

Fractured Bedrock ◽

Flow Models ◽

Flow Modelling ◽

Crystalline Bedrock ◽

Discharge Patterns ◽

Geological Units

AbstractGreater complexity in three-dimensional (3D) model structures yields more plausible groundwater recharge/discharge patterns, especially in groundwater/surface-water interactions. The construction of a 3D hydrostratigraphic model prior to flow modelling is beneficial when the hydraulic conductivity of geological units varies considerably. A workflow for 3D hydrostratigraphic modelling with Leapfrog Geo and flow modelling with MODFLOW-NWT was developed. It was used to evaluate how the modelling results for groundwater flow and recharge/discharge patterns differ when using simple or more complex hydrostratigraphic models. The workflow was applied to a study site consisting of complex Quaternary sediments underlain by fractured and weathered crystalline bedrock. Increasing the hydrostratigraphic detail appeared to improve the fit between the observed and simulated water table, and created more plausible groundwater flow patterns. Interlayered zones of low and high conductivity disperse the recharge/discharge patterns, increasing the vertical flow component. Groundwater flow was predominantly horizontal in models in which Quaternary sediments and bedrock were simplified as one layer per unit. It appears to be important to define the interlayered low-conductivity units, which can limit groundwater infiltration and also affect groundwater discharge patterns. Explicit modelling with Leapfrog Geo was found to be effective but time-consuming in the generation of scattered and thin-layered strata.

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Inhibition effectivity of Halimeda macroloba seaweed extract against fish indigenous bacteria for safety fisheries product

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/782/4/042010 ◽

2021 ◽

Vol 782 (4) ◽

pp. 042010

Author(s):

A F Dewinta ◽

Y A Wahyudi ◽

R Y Pratama ◽

I E Susetya ◽

R F Siregar ◽

...

Keyword(s):

Seaweed Extract ◽

Indigenous Bacteria

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Typical gut indigenous bacteria in ICR mice fed a soy protein-based normal or low-protein diet

Current Research in Food Science ◽

10.1016/j.crfs.2021.04.001 ◽

2021 ◽

Vol 4 ◽

pp. 295-300

Author(s):

Saori Nakamura ◽

Takashi Kuda ◽

Yuko Midorikawa ◽

Hajime Takahashi ◽

Bon Kimura

Keyword(s):

Soy Protein ◽

Protein Diet ◽

Low Protein Diet ◽

Indigenous Bacteria ◽

Icr Mice ◽

Low Protein

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The bacteria in sapwood, wetwood, and heartwood of trembling aspen (Populus tremuloides)

Canadian Journal of Botany ◽

10.1139/b73-060 ◽

1973 ◽

Vol 51 (2) ◽

pp. 498-500 ◽

Cited By ~ 15

Author(s):

Donald M. Knutson

Keyword(s):

Populus Tremuloides ◽

Trembling Aspen ◽

Indigenous Bacteria ◽

Large Populations ◽

Xylem Tissue

Bacteria (Erwinia, Bacillus) were consistently isolated from all samples of aspen sapwood and heartwood. In wetwood zones (water-soaked xylem tissue) or discolored heartwood, large populations often occur. No organisms unique to wetwood were isolated. Wetwood probably is formed by nonmicrobial means and, once formed, merely supports large populations of indigenous bacteria.

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Differences in susceptibility of marine bacterial communities to metal pyrithiones, their degradation compounds and organotin antifouling biocides

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315418001169 ◽

2019 ◽

Vol 99 (5) ◽

pp. 1033-1039

Author(s):

Madoka Ohji ◽

Hiroya Harino ◽

William John Langston

Keyword(s):

Life History ◽

Degradation Product ◽

Bacterial Communities ◽

Degradation Products ◽

High Susceptibility ◽

Zinc Pyrithione ◽

Bacterial Colony ◽

Indigenous Bacteria ◽

Antifouling Biocides ◽

Colony Forming Units

AbstractThe susceptibility of marine bacterial communities to copper pyrithione (CuPT2), zinc pyrithione (ZnPT2) and their degradation product is described and toxicities of these relatively new antifouling biocides compared with those of their harmful organotin (OT) predecessors, tributyltin (TBT) and triphenyltin (TPT). These biocides were added to agar at concentrations of 0, 0.01, 0.1, 1 and 10 mg l−1and coastal seawater including indigenous bacteria added to each batch of agar solution. The number of bacterial colony forming units (CFU) was measured after 7 days culture. Relative CFU (as a percentage of control) was more than 80% at a concentration of 0.01 mg l−1of each compound, except for TBT. Relative CFU decreased as a function of dose of each biocide, although concentration-dependent changes in rate of CFU were relatively low during exposure to degradation products of CuPT2and ZnPT2, pyridineN-oxide (PO) and pyridine-2-sulphonic acid (PSA). Based on comparisons of EC50, TBT was the most bacterio-toxic of the tested compounds (0.2 mg l−1), marginally more so than CuPT2(0.3 mg l−1). Interestingly, EC50values of degradation products of CuPT2and ZnPT2, 2-mercaptopyridineN-oxide (HPT) and 2,2′-dithio-bispyridineN-oxide (PT2) were 0.8 and 0.5 mg l−1, respectively, lower than that of the parent chemical, ZnPT2(1.4 mg l−1). The EC50of PT2was also lower than that of TPT (0.7 mg l−1), implying higher toxicity. Given the overlapping toxicity ranges, these results suggest that marine bacterial communities experience comparably high susceptibility to metal PTs and OTs during their life history.

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