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  1. Fulltext The function of microbial enzymes in breaking down soil contaminated with pesticides: a review
    Chia XK, Hadibarata T, Kristanti RA, Jusoh MNH, Tan IS, Foo HCY
    Bioprocess Biosyst Eng, 2024 May;47(5):597-620.
    PMID: 38456898 DOI: 10.1007/s00449-024-02978-6
    The use of pesticides and the subsequent accumulation of residues in the soil has become a worldwide problem. Organochlorine (OC) pesticides have spread widely in the environment and caused contamination from past agricultural activities. This article reviews the bioremediation of pesticide compounds in soil using microbial enzymes, including the enzymatic degradation pathway and the recent development of enzyme-mediated bioremediation. Enzyme-mediated bioremediation is divided into phase I and phase II, where the former increases the solubility of pesticide compounds through oxidation-reduction and hydrolysis reactions, while the latter transforms toxic pollutants into less toxic or nontoxic products through conjugation reactions. The identified enzymes that can degrade OC insecticides include dehalogenases, phenol hydroxylase, and laccases. Recent developments to improve enzyme-mediated bioremediation include immobilization, encapsulation, and protein engineering, which ensure its stability, recyclability, handling and storage, and better control of the reaction.
    Matched MeSH terms: Soil/chemistry; Soil Microbiology*
  2. Peat soil bulk density important for estimation of peatland fire emissions
    Wijedasa LS
    Glob Chang Biol, 2016 09;22(9):2959.
    PMID: 27195773 DOI: 10.1111/gcb.13364
    Matched MeSH terms: Soil*
  3. Relationship between shear strength and soil water characteristic curve of an unsaturated granitic residual soil
    Huat, Bujang B.K, Faisal Ali, Hashim, S.
    Pertanika Journal of Science & Technology, 2007;15(2):113-120.
    MyJurnal
    The three shear strength parameters that are required to define a failure envelope of an unsaturated soil are c' (apparent cohesion),
    Matched MeSH terms: Soil
  4. Soil Geobacteraceae are the key predictors of neurotoxic methylmercury bioaccumulation in rice
    Zhong H, Tang W, Li Z, Sonne C, Lam SS, Zhang X, et al.
    Nat Food, 2024 Apr;5(4):301-311.
    PMID: 38605129 DOI: 10.1038/s43016-024-00954-7
    Contamination of rice by the potent neurotoxin methylmercury (MeHg) originates from microbe-mediated Hg methylation in soils. However, the high diversity of Hg methylating microorganisms in soils hinders the prediction of MeHg formation and challenges the mitigation of MeHg bioaccumulation via regulating soil microbiomes. Here we explored the roles of various cropland microbial communities in MeHg formation in the potentials leading to MeHg accumulation in rice and reveal that Geobacteraceae are the key predictors of MeHg bioaccumulation in paddy soil systems. We characterized Hg methylating microorganisms from 67 cropland ecosystems across 3,600 latitudinal kilometres. The simulations of a rice-paddy biogeochemical model show that MeHg accumulation in rice is 1.3-1.7-fold more sensitive to changes in the relative abundance of Geobacteraceae compared to Hg input, which is recognized as the primary parameter in controlling MeHg exposure. These findings open up a window to predict MeHg formation and accumulation in human food webs, enabling more efficient mitigation of risks to human health through regulations of key soil microbiomes.
    Matched MeSH terms: Soil/chemistry; Soil Microbiology*
  5. Aluminium removal and recovery from wastewater and soil using isolated indigenous bacteria
    Purwanti IF, Kurniawan SB, Ismail N', Imron MF, Abdullah SRS
    J Environ Manage, 2019 Nov 01;249:109412.
    PMID: 31445374 DOI: 10.1016/j.jenvman.2019.109412
    This paper elucidates the capability of isolated indigenous bacteria to remove aluminium from wastewater and soil. Two indigenous species of Brochothrix thermosphacta and Vibrio alginolyticus were isolated from an aluminium-contaminated site. These two species were used to treat aluminium-containing wastewater and contaminated soil using the bioaugmentation method. B. thermosphacta showed the highest aluminium removal of 57.87 ± 0.45% while V. alginolyticus can remove aluminium up to 59.72 ± 0.33% from wastewater. For aluminium-contaminated soil, B. thermosphacta and V. alginolyticus, showed a highest removal of only 4.58 ± 0.44% and 5.48 ± 0.58%, respectively. The bioaugmentation method is more suitable to be used to treat aluminium in wastewater compared to contaminated soil. The produced biomass separation after wastewater treatment was so much easier and applicable, compared to the produced biomass handling from contaminated soil treatment. A 48.55 ± 2.45% and 40.12 ± 4.55% of aluminium can be recovered from B. thermosphacta and V. alginolyticus biomass, respectively, with 100 mg/L initial aluminium concentration in wastewater.
    Matched MeSH terms: Soil; Soil Pollutants*
  6. Effect of walnut shell biochars on soil quality, crop yields, and weed dynamics in a 4-year field experiment
    Safaei Khorram M, Zhang G, Fatemi A, Kiefer R, Mahmood A, Jafarnia S, et al.
    Environ Sci Pollut Res Int, 2020 May;27(15):18510-18520.
    PMID: 32198685 DOI: 10.1007/s11356-020-08335-w
    The introduction of biochar has been extensively tested under short-term greenhouse or field studies mainly in sandy or acidic soils, while its effects on soil properties, crop plants, and weed species especially in neutral or alkaline soils are still not well understood. Therefore, this study focused on relatively long effects of two walnut shell biochars (5 t ha-1) on soil nutrient dynamics, two crop plants (wheat and lentil) growth and developments, and weed growth dynamics over 4 years (2014-2017). Applied biochar added once at the beginning of the experiment while planted crops were supplied with macro-nutrients and sprayed with pesticides according to conventional requirements of the region. Biochars improved soil properties by 10-23% during the first and second years while positive effects of biochars on weed growth were drastically higher (60-78% higher weed density) during the whole period of this study most likely due to increase in bioavailability of nutrient shortly after biochar amendment and indirect positive effects of biochars on soil physical properties as well. Consequently, biochar macro- and micro-nutrient will be utilized by weed plants with higher efficacy compared with crop plants.
    Matched MeSH terms: Soil; Soil Pollutants/analysis*
  7. Fulltext Frequency distribution of foliar nickel is bimodal in the ultramafic flora of Kinabalu Park (Sabah, Malaysia)
    van der Ent A, Echevarria G, Nkrumah PN, Erskine PD
    Ann Bot, 2020 10 30;126(6):1017-1027.
    PMID: 32597938 DOI: 10.1093/aob/mcaa119
    BACKGROUND AND AIMS: The aim of this study was to test the frequency distributions of foliar elements from a large dataset from Kinabalu Park (Sabah, Malaysia) for departure from unimodality, indicative of a distinct ecophysiological response associated with hyperaccumulation.

    METHODS: We collected foliar samples (n = 1533) comprising 90 families, 198 genera and 495 plant species from ultramafic soils, further foliar samples (n = 177) comprising 45 families, 80 genera and 120 species from non-ultramafic soils and corresponding soil samples (n = 393 from ultramafic soils and n = 66 from non-ultramafic soils) from Kinabalu Park (Sabah, Malaysia). The data were geographically (Kinabalu Park) and edaphically (ultramafic soils) constrained. The inclusion of a relatively high proportion (approx. 14 %) of samples from hyperaccumulator species [with foliar concentrations of aluminium and nickel (Ni) >1000 μg g-1, cobalt, copper, chromium and zinc >300 μg g-1 or manganese (Mn) >10 mg g-1] allowed for hypothesis testing.

    KEY RESULTS: Frequency distribution graphs for most elements [calcium (Ca), magnesium (Mg) and phosphorus (P)] were unimodal, although some were skewed left (Mg and Mn). The Ni frequency distribution was bimodal and the separation point for the two modes was between 250 and 850 μg g-1.

    CONCLUSIONS: Accounting for statistical probability, the established empirical threshold value (>1000 μg g-1) remains appropriate. The two discrete modes for Ni indicate ecophysiologically distinct behaviour in plants growing in similar soils. This response is in contrast to Mn, which forms the tail of a continuous (approximately log-normal) distribution, suggestive of an extension of normal physiological processes.

    Matched MeSH terms: Soil; Soil Pollutants*
  8. Current Trends on the Effects of Metal-Based Nanoparticles on Microbial Ecology
    Rawat J, Kumar V, Ahlawat P, Tripathi LK, Tomar R, Kumar R, et al.
    Appl Biochem Biotechnol, 2023 Oct;195(10):6168-6182.
    PMID: 36847986 DOI: 10.1007/s12010-023-04386-0
    The growing field of nanotechnology and its many applications have led to the irregular release of nanoparticles (NPs), with unintended effects on the environment and continued contamination of water bodies. Metallic NPs are used more frequently in extreme environmental conditions due to their higher efficiency, which attracts more attention in various applications. Due to improper pre-treatment of biosolids, inefficient wastewater treatment practices, and other unregulated agricultural practices continue to contaminate the environment. In particular, the uncontrolled use of NPs in various industrial applications has led to damage to the microbial flora and caused irreplaceable damage to animals and plants. This study focuses on the effect of different doses, types, and compositions of NP on the ecosystem. The review also mentions the impact of various metallic NPs on microbial ecology, their interactions with microorganisms, ecotoxicity studies, and dosage evaluation of the NPs, mainly focused on the review article. However, further research is still needed to understand the complexity of interactions between NPs and microbes in soil and aquatic ecosystems.
    Matched MeSH terms: Soil; Soil Pollutants*
  9. Fulltext Autochthonous bioaugmentation accelerates phenanthrene degradation in acclimated soil
    Gu H, Yan J, Liu Y, Yu X, Feng Y, Yang X, et al.
    Environ Res, 2023 May 01;224:115543.
    PMID: 36822540 DOI: 10.1016/j.envres.2023.115543
    Bioaugmentation helps to obtain a microbiome capable of remediating polycyclic aromatic hydrocarbons (PAHs). In this study, acclimation of microorganisms to soil supplemented with phenanthrene (PHE) led to enrichment with PAH-degraders, including those in Actinobacteriota and in the genera Streptomyces, Rhodococcus, Nocardioides, Sphingomonas, and Mycobacterium. Aqueous (28 °C, pH 6.5) and soil cultures inoculated with PHE-acclimated soil showed a high PHE (ca. 50 mg L-1) degradation efficiency. The PHE degradation kinetics in aqueous and soil incubations fitted to the Gompertz equation and the first-order kinetic equation, respectively. Indigenous microorganisms adapted to PHE in their environment, and this increased their capacity to degrade PHE. The effect of co-contaminants and pathway intermediates on PHE degradation showed that the degradation of PHE improved in the presence of diesel while being hindered by lubricant oil, catechol, salicylic and phthalic acid. Our findings provide theoretical and practical support for bioremediationof PAHs in the environment.
    Matched MeSH terms: Soil/chemistry; Soil Microbiology
  10. Evaluating the toxicity of polyurethane during marine clay stabilisation
    Saleh S, Ahmad K, Mohd Yunus NZ, Hezmi MA
    Environ Sci Pollut Res Int, 2020 Jun;27(17):21252-21259.
    PMID: 32266626 DOI: 10.1007/s11356-020-08549-y
    In civil engineering, many geotechnical and forensic projects employ polyurethane (PU) for ground improvement, and the results have shown to be effective in terms of time and cost savings. However, similar to many other chemical stabilisers, the use of PU for soil stabilisation may have environmental repercussions. Therefore, this paper utilised a toxicity characteristic leaching procedure (TCLP) to investigate the potential for ground contamination resulting from the application of PU for the stabilisation of marine clay. Furthermore, the hazardousness of PU during the stabilisation of marine clay was investigated by testing its reactivity, ignitability, corrosivity and physical properties. The results reveal that the quantity of heavy metals present in PU is far below the regulatory limits. The results further confirm that PU is odourless and non-corrosive and that it is non-cyanide and non-sulphide-bearing. However, PU is capable of igniting. Overall, the potential application of PU for ground improvement is promising due to its environmental friendliness.
    Matched MeSH terms: Soil; Soil Pollutants/analysis*
  11. The application of surfactant colloidal gas aphrons to remediate contaminated soil: A review
    Tao W, Mei C, Hamzah N
    J Contam Hydrol, 2020 May;231:103620.
    PMID: 32126294 DOI: 10.1016/j.jconhyd.2020.103620
    Surfactant solutions have been frequently studied for soil remediation. However, since they are expensive, massive consumption of surfactant solution can constrain their application. Surfactant microbubbles, or colloidal gas aphrons (CGAs), can serve as cost effective alternatives of surfactant solution because the use of CGAs reduce the amount of surfactant consumption. Moreover, CGAs can also improve the contact with the contaminated environment due to their unique surface properties, e.g. containing 40-70% of gas, small size, large interfacial areas, water-like flow properties and buoyant rise velocities. In this review paper, the properties and flow character of CGAs in soil matrix reviewed due to their relevance to soil remediation process. A comprehensive overview of the application of CGAs in flushing off organic pollutants and heavy metals, and carrying oxygen, bacteria and dissolved materials for soil remediation were provided. This paper also highlighted the limitation of CGAs application and important future research scopes.
    Matched MeSH terms: Soil; Soil Pollutants/analysis*
  12. A review of the impact of herbicides and insecticides on the microbial communities
    Jeyaseelan A, Murugesan K, Thayanithi S, Palanisamy SB
    Environ Res, 2024 Mar 15;245:118020.
    PMID: 38151149 DOI: 10.1016/j.envres.2023.118020
    Enhancing crop yield to accommodate the ever-increasing world population has become critical, and diminishing arable land has pressured current agricultural practices. Intensive farming methods have been using more pesticides and insecticides (biocides), culminating in soil deposition, negatively impacting the microbiome. Hence, a deeper understanding of the interaction and impact of pesticides and insecticides on microbial communities is required for the scientific community. This review highlights the recent findings concerning the possible impacts of biocides on various soil microorganisms and their diversity. This review's bibliometric analysis emphasised the recent developments' statistics based on the Scopus document search. Pesticides and insecticides are reported to degrade microbes' structure, cellular processes, and distinct biochemical reactions at cellular and biochemical levels. Several biocides disrupt the relationship between plants and their microbial symbionts, hindering beneficial biological activities that are widely discussed. Most microbial target sites of or receptors are biomolecules, and biocides bind with the receptor through a ligand-based mechanism. The biomarker action mechanism in response to biocides relies on activating the receptor site by specific biochemical interactions. The production of electrophilic or nucleophilic species, free radicals, and redox-reactive agents are the significant factors of biocide's metabolic reaction. Most studies considered for the review reported the negative impact of biocides on the soil microbial community; hence, technological development is required regarding eco-friendly pesticide and insecticide, which has less or no impact on the soil microbial community.
    Matched MeSH terms: Soil/chemistry; Soil Microbiology
  13. Tradeoffs among yield, cadmium bioavailability, nitrous oxide emission and bacterial community stability: Effects of iron-modified woody peat and nitrification inhibitors on soil-vegetable systems
    Cao X, Hu X, Efrizal E, Hayati I, Yang J, Tan C, et al.
    J Environ Manage, 2024 Dec;372:123379.
    PMID: 39550941 DOI: 10.1016/j.jenvman.2024.123379
    Cadmium (Cd) pollution leads to soil degradation, decreases crop yield and affects human health through the food chain. Iron-modified woody peat (IMP) is an organic passivation material that significantly affects the migration of heavy metals in soil. Nitrification inhibitors are widely used to reduce greenhouse gas emissions. This study investigated the effects of the IMP and nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate on Cd content and form, crop yield, nitrous oxide (N2O) emission and bacterial communities in soil-lettuce systems. The simultaneous additions of IMP and DCD substantially reduced the soil available Cd content by 22.6 % and significantly promoted the lettuce yield by 42.9 %. Lettuce yield was significantly and negatively correlated with soil available Cd (correlation coefficient = -0.52). The simultaneous applications of IMP and nitrification inhibitors stimulated N2O emission risk by enhancing the soil NH4+-N contents and the relative abundances of Firmicutes, which could also decrease soil bacterial community stabilities. Therefore, tradeoffs among yield, Cd bioavailability, N2O emission and bacterial community stability should be comprehensively considered when evaluating the combined performances of IMP and nitrification inhibitors.
    Matched MeSH terms: Soil Microbiology; Soil Pollutants/metabolism
  14. Analysis of heavy metals as a key indicator to predict shallow slope failure
    Othman R, Hasni SI, Baharuddin ZM
    J Environ Biol, 2016 09;37(5 Spec No):1181-1185.
    PMID: 29989751
    Degradation or decline of soil quality that cause shallow slope failure may occur due to physical or chemical processes. It can be triggered off by natural phenomena, or induced by human activity through misuse of land resources, excessive development and urbanization leading to deforestation and erosion of covered soil masses causing serious threat to slopes. The extent of damage of the slopes can be minimized if a long-term early warning system is predicted in the landslide prone areas. The aim of the study was to characterize chemical properties of stable and unstable slope along selected highways of Malaysia which can be manipulated as indicator to forecast shallow slope failure. The elements in soil chemical properties contributed to each other as binding agents that affected the existing soil structure. It could make the soil structure strong or weak. Indicators that can be used to predict shallow slope failure were low content in iron, lead, aluminum, chromium, zinc, low content of organic carbon and CEC.
    Matched MeSH terms: Soil/chemistry; Soil Pollutants/chemistry*
  15. Biosorption of lead (Pb2+) by the vegetative and decay cells and spores of Bacillus coagulans R11 isolated from lead mine soil
    Xing SC, Chen JY, Lv N, Mi JD, Chen WL, Liang JB, et al.
    Chemosphere, 2018 Nov;211:804-816.
    PMID: 30099165 DOI: 10.1016/j.chemosphere.2018.08.005
    The lead (Pb2+) bioaccumulation capacities and mechanisms of three different physiological structures (vegetative cells, decay cells and spores) of B. coagulans R11 isolated from a lead mine were examined in this study. The results showed that the total Pb2+ removal capacity of vegetative cells (17.53 mg/g) was at its optimal and higher than those of the spores and decay cells at the initial lead concentration of 50 mg/L. However, when the initial lead concentration surpassed 50 mg/L, Pb2+ removal capacity of decay cells was more efficient. Zeta potential, Fourier transform infrared (FTIR) and functional group modification analyses demonstrated that the electrostatic attraction and chelating activity of the functional groups were the primary pathways involved in the extracellular accumulation of Pb2+ by the vegetative cells and spores. However, the primary Pb2+ binding pathway in the decay cells was hypothesized to be due to physical adsorption, which easily led to Pb2+ desorption. Based on these results, we conclude that the vegetative cell is the ideal lead sorbent. Therefore, it is important to inhibit the transformation of the vegetative cells into decay cells and spores, which can be achieved by culturing the bacteria under anaerobic conditions to prevent spore formation. Heat stimulation can effectively enhance spore germination to generate vegetative cells.
    Matched MeSH terms: Soil/chemistry*; Soil Pollutants/chemistry*
  16. Biochar for cadmium pollution mitigation and stress resistance in tobacco growth
    Ren T, Chen N, Wan Mahari WA, Xu C, Feng H, Ji X, et al.
    Environ Res, 2021 01;192:110273.
    PMID: 33002505 DOI: 10.1016/j.envres.2020.110273
    Pot experiments were conducted to investigate the influence of biochar addition and the mechanisms that alleviate Cd stress in the growth of tobacco plant. Cadmium showed an inhibitory effect on tobacco growth at different post-transplantation times, and this increased with the increase in soil Cd concentration. The growth index decreased by more than 10%, and the photosynthetic pigment and photosynthetic characteristics of the tobacco leaf were significantly reduced, and the antioxidant enzyme activity was enhanced. Application of biochar effectively alleviated the inhibitory effect of Cd on tobacco growth, and the alleviation effect of treatments is more significant to the plants with a higher Cd concentration. The contents of chlorophyll a, chlorophyll b, and carotenoids in the leaves of tobacco plants treated with biochar increased by 9.99%, 12.58%, and 10.32%, respectively, after 60 days of transplantation. The photosynthetic characteristics index of the net photosynthetic rate increased by 11.48%, stomatal conductance increased by 11.44%, and intercellular carbon dioxide concentration decreased to 0.92. Based on the treatments, during the growth period, the antioxidant enzyme activities of tobacco leaves comprising catalase, peroxidase, superoxide dismutase, and malondialdehyde increased by 7.62%, 10.41%, 10.58%, and 12.57%, respectively, after the application of biochar. Our results show that biochar containing functional groups can effectively reduce the effect of Cd stress by intensifying the adsorption or passivation of Cd in the soil, thereby, significantly reducing the Cd content in plant leaves, and providing a theoretical basis and method to alleviate soil Cd pollution and effect soil remediation.
    Matched MeSH terms: Soil
  17. Fulltext Diversity of isoprene-degrading bacteria in phyllosphere and soil communities from a high isoprene-emitting environment: a Malaysian oil palm plantation
    Carrión O, Gibson L, Elias DMO, McNamara NP, van Alen TA, Op den Camp HJM, et al.
    Microbiome, 2020 06 03;8(1):81.
    PMID: 32493439 DOI: 10.1186/s40168-020-00860-7
    BACKGROUND: Isoprene is the most abundantly produced biogenic volatile organic compound (BVOC) on Earth, with annual global emissions almost equal to those of methane. Despite its importance in atmospheric chemistry and climate, little is known about the biological degradation of isoprene in the environment. The largest source of isoprene is terrestrial plants, and oil palms, the cultivation of which is expanding rapidly, are among the highest isoprene-producing trees.

    RESULTS: DNA stable isotope probing (DNA-SIP) to study the microbial isoprene-degrading community associated with oil palm trees revealed novel genera of isoprene-utilising bacteria including Novosphingobium, Pelomonas, Rhodoblastus, Sphingomonas and Zoogloea in both oil palm soils and on leaves. Amplicon sequencing of isoA genes, which encode the α-subunit of the isoprene monooxygenase (IsoMO), a key enzyme in isoprene metabolism, confirmed that oil palm trees harbour a novel diversity of isoA sequences. In addition, metagenome-assembled genomes (MAGs) were reconstructed from oil palm soil and leaf metagenomes and putative isoprene degradation genes were identified. Analysis of unenriched metagenomes showed that isoA-containing bacteria are more abundant in soils than in the oil palm phyllosphere.

    CONCLUSION: This study greatly expands the known diversity of bacteria that can metabolise isoprene and contributes to a better understanding of the biological degradation of this important but neglected climate-active gas. Video abstract.

    Matched MeSH terms: Soil*; Soil Microbiology*
  18. Sustainable utilization of biowaste compost for renewable energy and soil amendments
    Chia WY, Chew KW, Le CF, Lam SS, Chee CSC, Ooi MSL, et al.
    Environ Pollut, 2020 Dec;267:115662.
    PMID: 33254731 DOI: 10.1016/j.envpol.2020.115662
    Acceleration of urbanization and industrialization has resulted in the drastic rise of waste generation with majority of them being biowaste. This constitutes a global challenge since conventional waste management methods (i.e., landfills) present environmental issues including greenhouse gases emissions, leachate formation and toxins release. A sustainable and effective approach to treat biowaste is through composting. Various aspects of composting such as compost quality, composting systems and compost pelletization are summarized in this paper. Common application of compost as fertilizer or soil amendment is presented with focus on the low adoption level of organic waste compost in reality. Rarely known, compost which is easily combustible can be utilized to generate electricity. With the analysis on critical approaches, this review aims to provide a comprehensive study on energy content of compost pellets, which has never been reviewed before. Environmental impacts and future prospects are also highlighted to provide further insights on application of this technology to close the loop of circular bioeconomy.
    Matched MeSH terms: Soil
  19. Assessing the impact of water infiltration on LNAPL mobilization in sand column using simplified image analysis method
    Alazaiza MYD, Ramli MH, Copty NK, Ling MC
    J Contam Hydrol, 2021 Mar;238:103769.
    PMID: 33465656 DOI: 10.1016/j.jconhyd.2021.103769
    Laboratory-scale column experiments were carried out to assess the influence of water infiltration on pooled light non-aqueous phase liquid (LNAPL) redistribution in porous media. A simplified image analysis method (SIAM) was used to evaluate the saturation distributions of the LNAPL and water in the entire domain under dynamic conditions. The experiments were conducted for high/low LNAPL volumes LNAPL volumes differentiated as low and high volumes. High resolution SIAM images of the soil column during LNAPL migration and water infiltration events were captured and analyzed. Results indicated that the capillary fringe is about 6-7 cm which was consistent with the capillary height derived from empirical equations. Moreover, SIAM provided an estimate of the field capacity (30%) of the sand. Once the LNAPL infiltration stage was started, the LNAPL was observed to rapidly migrate through the vadose zone. For the case of large LNAPL volume, the LNAPL penetrated further into capillary fringe zone. Analysis of SIAM images showed that the LNAPL redistribution was observed to vary significantly with the rate of infiltration. For higher water infiltration intensity, the injected water exerted a larger hydrodynamic force on the entrapped LNAPL forcing it move further downward into the capillary zone and the saturated zone. Overall, this study demonstrated that the SIAM technique is an accurate and cost-effective tool for the visualization of the time-dependent NAPL/water movement in laboratory-scale experiments and dynamic changes in fluid saturation in porous media.
    Matched MeSH terms: Soil
  20. Fulltext Diesel in Antarctica and a Bibliometric Study on Its Indigenous Microorganisms as Remediation Agent
    Wong RR, Lim ZS, Shaharuddin NA, Zulkharnain A, Gomez-Fuentes C, Ahmad SA
    Int J Environ Res Public Health, 2021 02 05;18(4).
    PMID: 33562609 DOI: 10.3390/ijerph18041512
    Diesel acts as a main energy source to complement human activities in Antarctica. However, the increased expedition in Antarctica has threatened the environment as well as its living organisms. While more efforts on the use of renewable energy are being done, most activities in Antarctica still depend heavily on the use of diesel. Diesel contaminants in their natural state are known to be persistent, complex and toxic. The low temperature in Antarctica worsens these issues, making pollutants more significantly toxic to their environment and indigenous organisms. A bibliometric analysis had demonstrated a gradual increase in the number of studies on the microbial hydrocarbon remediation in Antarctica over the year. It was also found that these studies were dominated by those that used bacteria as remediating agents, whereas very little focus was given on fungi and microalgae. This review presents a summary of the collective and past understanding to the current findings of Antarctic microbial enzymatic degradation of hydrocarbons as well as its genotypic adaptation to the extreme low temperature.
    Matched MeSH terms: Soil Microbiology*; Soil Pollutants*
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