Natural Degradation Processes Research Articles

Bioremediation of Petroleum Hydrocarbons in Seawater: Prospects of Using Lyophilized Native Hydrocarbon-Degrading Bacteria.

This work aimed to develop a bioremediation product of lyophilized native bacteria to respond to marine oil spills. Three oil-degrading bacterial strains (two strains of Rhodococcus erythropolis and one Pseudomonas sp.), isolated from the NW Portuguese coast, were selected for lyophilization after biomass growth optimization (tested with alternative carbon sources). Results indicated that the bacterial strains remained viable after the lyophilization process, without losing their biodegradation potential. The biomass/petroleum ratio was optimized, and the bioremediation efficiency of the lyophilized bacterial consortium was tested in microcosms with natural seawater and petroleum. An acceleration of the natural oil degradation process was observed, with an increased abundance of oil-degraders after 24 h, an emulsion of the oil/water layer after 7 days, and an increased removal of total petroleum hydrocarbons (47%) after 15 days. This study provides an insight into the formulation and optimization of lyophilized bacterial agents for application in autochthonous oil bioremediation.

Plastic-Degrading Potential across the Global Microbiome Correlates with Recent Pollution Trends.

ABSTRACTBiodegradation is a plausible route toward sustainable management of the millions of tons of plastic waste that have accumulated in terrestrial and marine environments. However, the global diversity of plastic-degrading enzymes remains poorly understood. Taking advantage of global environmental DNA sampling projects, here we constructed hidden Markov models from experimentally verified enzymes and mined ocean and soil metagenomes to assess the global potential of microorganisms to degrade plastics. By controlling for false positives using gut microbiome data, we compiled a catalogue of over 30,000 nonredundant enzyme homologues with the potential to degrade 10 different plastic types. While differences between the ocean and soil microbiomes likely reflect the base compositions of these environments, we find that ocean enzyme abundance increases with depth as a response to plastic pollution and not merely taxonomic composition. By obtaining further pollution measurements, we observed that the abundance of the uncovered enzymes in both ocean and soil habitats significantly correlates with marine and country-specific plastic pollution trends. Our study thus uncovers the earth microbiome's potential to degrade plastics, providing evidence of a measurable effect of plastic pollution on the global microbial ecology as well as a useful resource for further applied research.

Monitored Natural Attenuation to Manage PFAS Impacts to Groundwater: Scientific Basis

AbstractSites impacted by per‐ and polyfluoroalkyl substances (PFAS) pose significant challenges to investigation and remediation, including very low cleanup objectives, limited information on natural PFAS degradation processes in the subsurface, and the apparent mobility and persistence of PFAS. Consequently, monitored natural attenuation (MNA) may be considered less applicable to PFAS compared to biodegradable classes of chemicals such as petroleum hydrocarbons and chlorinated solvents that can completely biodegrade to innocuous end products. However, MNA has proven effective for certain non‐degrading metals, metalloids, and radionuclides (e.g., chromium, arsenic, and uranium). To assess the applicability of MNA to PFAS, this paper reviews the fate and transport properties of PFAS in conjunction with the various physiochemical factors that control the subsurface movement of chemicals. This analysis demonstrates that two important retention processes: (1) chemical retention in the form of PFAS precursors, and (2) geochemical retention in the form of sorption and matrix diffusion to mitigate the movement and potential impacts of PFAS in groundwater that may form the scientific basis for applying MNA to PFAS contamination. This paper describes the scientific and regulatory basis for using MNA to manage PFAS‐impacted groundwater.

Forest Wood through the Eyes of a Cultural Conservator

If prehistoric and historical time were placed into the time span of the existence of our universe, then the act of archaeology could be defined as the act of digging up what was only buried yesterday. So, conservation is about preserving a moment that has just become past time, yet significant. It is a moment of human creativity and ingenuity. It is not strange that forest wood has become the material to convey such moments. Forest wood is a living, everlasting source growing without human intervention, within reach, easy to use and shape thinking both great and small. It does not have to be a wooden ship; it can be a mere piece of charcoal. For it is what surrounded humans in the past which archaeologists seek and use to weave human history, and what conservators bring back to context by reviving it. This work presents forest wood as an artefact and its preservation challenges as such. It touches on its natural degradation processes through burial, compromised properties and eventual conservation. Both dry and waterlogged wood are included. The overarching aim of this paper is to pay tribute, preserve and inspire the long-standing, open dialog and fruitful collaboration between cultural conservators and forest and wood scientists.

Effective Dye Degradation Using Sol-Gel Synthesized Titania Nanostructures

Background: The organic effluents from industry remain one of the reasons for water contamination. By the natural degradation process, it is difficult to remove this; hence finding an effective solution for this is inevitable. TiO2-based materials have received enormous attention in the area of semiconductor photocatalysis, particularly for the degradation of organic dyes. This work emphasizes on the degradation of two industrial dyes methylene blue and rhodamine blue by visible light irradiation of TiO2 based nanoparticles. Methods: In the present study, pristine and La3+ and Ce3+ doped nanotitania were synthesized by the sol-gel method. The samples under investigation were characterized using X-ray diffraction, Transmission electron microscopy to study the variation of crystallite size and UV-Visible absorption spectroscopy. Results: The increase in crystallite size for the pristine samples calcined at various temperatures confirms the effect of calcination temperature. Also, the doping reduced the size of the synthesized nanotitania. Visible light extended absorption spectra have been observed for the calcined samples and Ce3+ doped nanotitania. The La3+ doped sample showed a blue shift in the absorption confirming quantum confinement. The photocatalytic activity in the context of degradation of certain industrial dyes such as methylene blue and rhodamine blue has been investigated for the samples. Conclusion: The studies found that nanotitania consisting of mixed anatase-rutile phase exhibits higher degradation efficiency than that of pure anatase or rutile samples. Besides, photocatalytic dye degradation has been significantly improved for Ce3+ doped nanotitania compared to the pristine sample.

Belief reliability analysis of competing for failure systems with bi-uncertain variables

In this paper, an uncertain competing failure degradation model is proposed, in which the natural degradation process is described by an uncertain process, the time interval of shocks arrival and the size of the shocks have independent and nonidentical uncertainty distributions, respectively. The parameters in the distributions are uncertain variables. The belief reliability function and the mean time to failure of the system under three different shock models are studied according to uncertainty theory, and Micro-Electro-Mechanical System as an example is used to explain the developed models.

Combining Chemical and Biological Oxidation for Sustainable Treatment of Chloronitrobenzene in Anoxic Groundwater

AbstractChloronitrobenzenes (CNBs) are important chemical intermediates that are resistant to natural degradation processes in anoxic environments. When receptors are threatened by CNB‐contaminated groundwater, advanced oxidation processes (AOPs) offer a rapid response to protect human health and the environment. While AOPs are effective for the transformation of persistent organic contaminants, driving chemical oxidation reactions to complete mineralization is often not energy‐ and cost‐efficient due to the formation of recalcitrant intermediates or competition by natural organic matter. In this study, we applied an electrochemical AOP to elucidate the degradation pathways and kinetics of CNB under varying treatment conditions and times. Nontargeted mass spectrometry revealed multiple ring hydroxylation and ring opening products such as dicarboxylic acids that became increasingly harder to chemically oxidize as treatment time progressed. To determine the universal biodegradability of the generated intermediates under anoxic conditions, AOP‐treated water samples collected at different stages of electrochemical oxidation were exposed to a microbial culture derived from generic rhizosphere soil. All ring opening products were completely biodegraded anaerobically within 28 days of microcosm incubation. While multiple oxygenated ring intermediates were substantially removed, CNB was stable in the absence of oxygen. Our findings demonstrate that the combination of limited and targeted chemical oxidation with subsequent biodegradation of incomplete oxidation products is a more sustainable approach than the exclusive application of AOPs for the treatment of groundwater contaminated with CNBs and likely other aromatic compounds.

Environmental disappearance of acetochlor and its bioavailability to weed: A general prototype for reduced herbicide application instruction

The consecutive application of herbicide acetochlor has resulted in the widespread drug resistance of weeds and the high risks to environment and human health. To assess environmental behaviors and minimal dosage of acetochlor application in the realistic soil, we systematically investigated the acetochlor adsorption/desorption, mobility, leaching, degradation, weed bioavailability and lethal dosage of acetochlor in three soil types including Nanjing (NJ), Yancheng (YC) and Yingtan (YT). Under the same conditions (60% moisture and darkness), acetochlor had a half-life of disappearance 3 days in NJ, 4.9 days in YC and 25.7 days in YT soils. The HRLC-Q-TOF-MS/MS analyses identified ten metabolites and eight conjugates generated through dealkylation, hydroxylation, thiol conjugation and glycosylation pathways. The acetochlor adsorption to soils ranked in the order of YT > YC > NJ and was committed to the Freundlich model. By examining the effects of soil moisture, microbial activity, illumination/darkness, etc. on acetochlor degradation in soils, we showed that the chemical metabolisms could undergo multiple processes through soil microbial degradation, hydrolysis or photolysis-mediated mechanisms. The longitudinal migration assay revealed that acetochlor leaching ability in the three soils was YT > YC > NJ, which was negatively associated with the order of adsorption behavior. Four kinds of weed were grown in the acetochlor-contaminated NJ soil. The lethal concentrations for the weed plantlets were 0.16–0.3 mg/kg, much lower than the dosage of realistic field application. Overall, our work provided novel insights into the mechanism for acetochlor behaviors in soils, the natural degradation process in the environment, and the lethal concentration to the tested weed plants.

Modeling the natural degradation kinetics of conducting polypyrrole for service failure prediction in NaOH aqueous media

The degradation of electrochemical activity is the inevitable and noticeable issue in the widespread applications of conducting polypyrrole (PPy), which involves chemical and electrochemical reactions in PPy natural degradation processes. Based on thorough insights into PPy degradation behavior, this work develops a method of theoretical derivation for the natural degradation kinetics model of PPy, which is verified in NaOH aqueous electrolytes and could be further generalized in other media. The kinetics model derives the rate equations of the chemical and electrochemical processes (vc and ve) in PPy degradation. The relationships of the electroactivity degradation rate constant (kdeg) and rate constants of the chemical and electrochemical processes (kc and ke) as well as reaction orders of PPyn+ and OH− are established through theoretical deduction. The effects of doping anions in PPy, film thickness, and electrolyte temperature on the degradation kinetics are investigated through theoretical considerations and experimental findings. The degradation level and service failure time of PPy can be effectively predicted using the kinetics model. Establishing the degradation kinetics model would signal the new perspective and depth in comprehensive studies of PPy degradation, finally facilitating the optimization of performance management in PPy practical applications.

Ultrashort Peptides-A Glimpse into the Structural Modifications and Their Applications as Biomaterials.

Because of their commanding properties, ultrashort and short peptides are gaining significance as viable candidates for molecular self-assembly, which is a naturally inspired approach for developing supramolecular structures and can be used to design various strategies of significance in the field of biomaterials. Self-assembly of biomolecules like proteins, lipids, and nucleic acids is observed in living organisms, various biological-process-based examples like amyloid-β plaque formation, lipid bilayer assembly, and the complementary binding of the nucleotide bases of nucleic acids involve self-assembly. Among all biomolecules, peptide-based self-assembly has the advantage of the availability of the source, peptides can be easily synthesized or obtained from the natural degradation process and can be engineered to modulate their action, making them an area of immense interest for research. Multiple modification options provide a wide area for the engineering of amino acid sequences. Understanding of the amino acid residues with their existing properties and modified properties is very helpful for further improvements. Computational approaches like molecular dynamics simulations provide atomistic-level insight into the self-assembly process, by which newer physical-chemical modifications can be planned. Virtual screening of the peptides on the basis of their properties and probability for the desired activity are helpful as well. Engineered and programmed peptides have been reported for various applications like drug delivery and target specific formulations. A combined approach of computational and experimental studies is helpful to understand and optimize the self-assembly process and mechanism at the atomic level. These self-assembled ultrashort peptides have been used in a wide range of applications from hydrogels to drug delivery agents, biosensors, emulsifiers, and so on.

Indirect photodegradation of sulfathiazole and sulfamerazine: Influence of the CDOM components and seawater factors (salinity, pH, nitrate and bicarbonate)

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in the aquatic environment, and may cause potential harm to the environment and humans. Indirect photodegradation has been considered to be a promising natural degradation process for antibiotics in the environment. Chromophoric dissolved organic matter (CDOM) is an important participant in the indirect photodegradation of antibiotics. Indirect photodegradation of sulfathiazole (ST) and sulfamerazine (SM) were studied in the presence of CDOM and marine factors (salinity, pH, nitrate (NO3−) and bicarbonate (HCO3−)) to simulate photodegradation of these compounds in the coastal seawater environment. The main findings are as follows. First, the indirect photodegradation rates of ST and SM in the presence of CDOM were significantly increased and followed the pseudofirst order kinetics. Second, 1O2 played a critical role in the indirect photodegradation of ST and its contribution rate was 54.2%; 3CDOM⁎ performed similarly in the case of SM with a 58.0% contribution rate. Third, CDOM was divided into four fluorescent components by excitation-emission matrix spectroscopy and parallel factor analysis (EEMs-PARAFAC), including three exogenous components and an autochthonous component. The exogenous components with high molecular weight and higher number of aromatic groups played a decisive role in the indirect photodegradation of ST and SM due to their ability to generate higher levels of reactive intermediates (RIs). Finally, seawater factors (salinity, pH, NO3− and HCO3−) influenced the indirect photodegradation of ST and SM by influencing the steady-state concentrations of RIs. This report is the first study of indirect photodegradation of ST and SM from the perspective of the CDOM components and simulated coastal waters.

Assessment of Cytocompatibility and Anti-Inflammatory (Inter)Actions of Genipin-Crosslinked Chitosan Powders.

Chitosan is a polysaccharide commonly used, together with its derivatives, in the preparation of hydrogel formulations, scaffolds and films for tissue engineering applications. Chitosan can be used as such, but it is commonly stabilized by means of chemical crosslinkers. Genipin is one of the crosslinkers that has been considered that is a crystalline powder extracted from the fruit of Gardenia jasminoides and processed to obtain an aglycon compound. Genipin is gaining interest in biological applications because of its natural origin and anti-inflammatory actions. In this paper, the ability of chitosan-based materials crosslinked with genipin to exert anti-inflammation properties in applications such as bone regeneration was studied. Powders obtained from chitosan–genipin scaffolds have been tested in order to mimic the natural degradation processes occurring during biomaterials implantation in vivo. The results from osteoblast-like cells showed that specific combinations of chitosan and genipin stimulate high permissiveness towards cells, with higher performance than the pure chitosan. In parallel, evidences from monocyte-like cells showed that the crosslinker, genipin, seems to promote slowing of the monocyte-macrophage transition at morphological level. This suggests a sort of modularity of pro-inflammatory versus anti-inflammatory behavior of our chitosan-based biomaterials. Being both the cell types exposed to microscale powders, as an added value our results bring information on the cell–material interactions in the degradative dynamics of chitosan scaffold structures during the physiological resorption processes.

Reutilización de respiradores N95: estrategias de descontaminación aplicables en la pandemia de COVID 19 en Perú

El virus SARS-CoV-2 o virus del COVID-19, considerado como emergencia internacional de salud pública, fue declarada posteriormente como una pandemia. Debido a la alta propagación del virus del COVID-19 por medio de droplets, la demanda de los equipos de protección personal (EPP) para el personal de salud ha sido notable, en especial el de los respiradores. Por ende, se hace importante conocer los métodos de descontaminación considerados para su aplicación en nuestro medio; teniendo en cuenta el uso adecuado de medidas de asepsia y antisepsia, garantizando a su vez la integridad del respirador (correas, puente nasal y material de espuma nasal) y contando con el proceso natural de degradación. Los métodos adecuados de desinfección en respiradores descritos son: el uso de hornos esterilizadores (calor seco), autoclave (vapor), radiación ultravioleta (UV) y vaporizadores caseros (olla arrocera con vaporizador). Estos métodos deben ser empleados acordes a las necesidades del personal de salud.

Impacts of land cover changes on desertification in northern Nigeria and implications on the Lake Chad Basin

Desertification is an issue of environmental concern in Nigeria, particularly the northern part of the country. This study examines land cover changes related to the process of desertification in the states along the northern boundary of Nigeria (Sokoto, Zamfara, Katsina, Jigawa, Yobe, and Borno) and the implications on the Lake Chad Basin. A time series of Landsat imagery at a spatial resolution of 30 m was used over the period from 1984 to 2016. The imageries were subjected to maximum likelihood classification for the purpose of extracting the land cover and analysing the change. Also, the areal extent of vegetation cover within the 32-year period was calculated annually. Using Pearson's correlation analysis, the relationship between the vegetation cover and rainfall was assessed as well as temperature and population density. Results show that 45,945.08 km2 of vegetation cover was lost within the study area including the Lake Chad area between 1984 and 2016. The annual rate of change varied across the different feature classes; the built-up area had the highest rate of increase of 13.68% and 2.65%, from 1984 to 2000 and 2000–2016 respectively. Bare-land increased at the rate of 0.96% and 0.28% from 1984 to 2000 and 2000–2016 respectively while vegetation had the highest rate of decrease of 2.18% and 2.02% from 1984 to 2000 and 2000–2016 respectively. A pattern of vegetation loss was observed as a large expanse of vegetation cover was lost across the north-west and the north-east regions including the Lake Chad area. It was also shown that the magnitude of vegetation cover correlated negatively with temperature and population density but with no significant correlation with the rainfall. The study recommends that the Federal Government should ensure the full implementation of the Great Green Wall project which is aimed at mitigating the rapid sprawl of natural land degradation processes and desertification in the northern boundary states.

Modeling the interdependency between natural degradation process and random shocks

In this paper, an interdependent structure between the natural degradation process and random shock process is proposed and incorporated into the competing failure model. Interdependent means that shocks are assumed to have an impact on the natural degradation process, additionally, the natural degradation process can also influence random shocks. Therefore, the interdependent structure includes two-fold: a) the impact of random shocks on the natural degradation process, represented by the cumulative damage adding up to the natural degradation process and expressed by a compound Poisson distribution, which is commonly used by other researchers; b) the influence of natural degradation process toward random shocks (both the magnitude and damage of shocks), reflected by the natural-degradation-state varying thresholds used for categorizing shocks into safety zone, damage zone and fatal zone according to their magnitudes, and the natural-degradation-state varying cumulative damage of shocks in damage zone, which are considered for the first time. A closed-form reliability function is derived under the linear natural-degradation-state varying thresholds. Two illustrative examples are presented to demonstrate this approach, and results show that the developed interdependent relationship model can obtain a more practical estimation of the reliability.

Polyethylene Biodegradation Potentials of Pseudomonas aeruginosa and Micrococcus sp. Isolated from Waste Dumps and Farmlands in Nsukka, Enugu State, Nigeria

Background: Low Density Polyethylene (LDPE) are plastic materials extensively used in packaging, constituting recalcitrant environmental pollutants that defy natural degradation processes.
 Aim: This study isolated bacteria from a Nigerian environment and assessed their potential for LDPE biodegradation.
 Methods: Using standard procedures, Bacteria were isolated from polythene samples collected from farmlands and waste dump sites in Nsukka metropolis. Mineral salt medium (MSM) was prepared, with LPDE as sole carbon source, and used for isolation. Optical density (OD600 nm) was used to study bacterial growth on LDPE as sole carbon source as proof of biodegradation. Both organisms demonstrated steady growth on LDPE over time.
 Results: Pseudomonas aeruginosa and Micrococcus sp. were identified based on morphological and biochemical characteristics. Ability to grow on LDPE as a sole carbon source was studied as evidence of polyethylene biodegradation. Organisms were inoculated into MSM and incubated at 37°C and 50°C for 15 days. Maximum growth was recorded after 15 days of incubation for both organisms. P. aeruginosa and Micrococcus sp. showed steady growth at 37°C as well as 50 ⁰C. Micrococcus sp. recorded highest growth; 0.324 nm and 0.312 nm at 37°C and 50°C respectively, after 15 days. Similarly, P. aeruginosa recorded highest growth of 0.40 nm and 0.258 nm for 37°C and 50°C respectively. LDPE degradation increased with increase in time.
 Conclusion: This study demonstrates the enormous polyethylene-degrading potentials of P. aeruginosa and Micrococcus sp. isolated from Nsukka, Nigeria.

Study on Treatment of Salicylhydroxamic Acid Wastewater from Tungsten Molybdenum Mineral Processing

Salicylhydroxamic acid is an excellent collector of oxidizing ore, and it has an efficient collection performance for tungsten molybdenum ore. However, the utilization ratio of salicylhydroxamic acid is relatively low in the flotation process, and a large amount of flotation wastewater discharged might cause damage to the water environment. This study mainly compared the effects of natural sunlight degradation, ozonation, and Fenton oxidation processes on the treatment of salicylchydroxamic acid wastewater from W–Mo mineral processing. The results showed after 30 hours degradation by natural sunlight, the CODcr removal rate of wastewater was only 25.99%. When the initial pH was 8, the dosage of O3 was 1.3 mg/L and the reaction time was 60 minutes; O3 oxidation could remove 40.37% CODcr from wastewater, and the BOD5/CODcr value increased to higher than 0.3 after 15 min reaction. Under the Fenton oxidation conditions such as initial pH 3, H2O2 dosage 0.96 g/L, and the molar ratio of H2O2 to Fe2+ 2 : 1, 90.43% CODcr could be removed from flotation wastewater after 90 min reaction, and the BOD5/CODcr value was obviously improved. Fenton oxidation was a high efficient processing technology for salicylhydroxamic acid wastewater, and the effluent could meet the discharge and reuse emission standard requirements in China.

Oil Bioremediation in a Tropical Contaminated Soil Using a Reactor.

This research was implemented in the Colombian Amazon forest area; to assess the effect of Tween-80® surfactant in the degradation of the Total Petroleum Hydrocarbons (TPH) in bioremediation treatments under aerobic conditions in the laboratory and pilot-scale. One control treatment, Natural Attenuation (AT) and four biostimulation treatments with leonardite with four different dosages of Tween-80® were proposed. The efficacy of organic stimulators and nonionic surfactant in soil microbiota was studied at laboratory and pilot scales, the latter in a passive aeration reactor. The test that presented a better performance was carried out with a Convective Flow Reactor (CFR) at pilot-scale. The results showed that bioremediation strategies improved the natural degradation process; the best outcomes were obtained in a treatment that includes Leonardite and Tween-80® (1.5 g/L) with 52% TPH degradation in 80 days (d).Tween-80® produced an effect in TPH solubility, and increased the production of CO2 in distinctive bioremediation treatments in both periods. The kinetics of CO2 production showed that the system required a periodic addition of a co-substrate as well as an increase of soil microbiota through the addition of compost (pilot scale). In this stage more than 76% of contaminant was degraded in 60d.

Engineering of industrially important microorganisms for assimilation of cellulosic biomass: towards consolidated bioprocessing.

Conversion of cellulosic biomass (non-edible plant material) to products such as chemical feedstocks and liquid fuels is a major goal of industrial biotechnology and an essential component of plans to move from an economy based on fossil carbon to one based on renewable materials. Many microorganisms can effectively degrade cellulosic biomass, but attempts to engineer this ability into industrially useful strains have met with limited success, suggesting an incomplete understanding of the process. The recent discovery and continuing study of enzymes involved in oxidative depolymerisation, as well as more detailed study of natural cellulose degradation processes, may offer a way forward.

Quantification of Hyporheic Nitrate Removal at the Reach Scale: Exposure Times Versus Residence Times

AbstractThe rate of biogeochemical processing associated with natural degradation and transformation processes in the hyporheic zone (HZ) is one of the largest uncertainties in predicting nutrient fluxes. We present a lumped parameter model that can be used to quantify the mass loss for nitrate in the HZ operating at the scale of river reaches to the entire catchments. The model is based on using exposure times (ET) to account for the effective timescales of reactive transport in the HZ. Reach scale ET distributions are derived by removing the portion of hyporheic residence times (RT) associated with flow through the oxic zone. The model was used to quantify nitrate removal for two scenarios: (1) a 100 m generic river reach and (2) a small agricultural catchment in Brittany (France). For the field site, hyporheic RT were derived from measured in‐stream 222Rn activities and mass balance modeling. Simulations were carried out using different types of RT distributions (exponential, power law, and gamma‐type) for which ET were derived. Mass loss of nitrate in the HZ for the field site ranged from 0 to 0.45 kg day−1 depending on the RT distribution and the availability of oxygen in the streambed sediments. Simulations with power law ET distribution models only show very little removal of nitrate due to the heavy weighting toward shorter flow paths that are confined to the oxic sediments. Based on the simulation results, we suggest that using ET will likely lead to more realistic estimates for nutrient removal in river and stream networks.