Addition Of Nitrates Research Articles

Efficient PAHs removal and CO2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L−1 d−1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg−1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Bimetallic Ba(II)-Cr(III) and trimetallic Ba(II)-Ln(III)-Cr(III) (Ln(III) = Gd, Tb, Dy, Ho, Er, Yb, Y) coordination polymers formed by Cr(III)-containing building blocks with cyclopropane-1,1-dicarboxylate anions

The reaction of chromium(III) nitrate with Ba(cpdc) (H2cpdc = cyclopropane-1,1-dicarboxylic acid) in a ratio of 1:3 yielded a 1D coordination polymer {[Ba2Cr2(OH)2(cpdc)4(H2O)8]·5H2O}n (1) formed by binuclear units [Cr2(OH)2(cpdc)4]4− and a 3D polymer [Ba2Cr(cpdc)3(NO3)(H2O)6]n (2) constructed from tris-chelate blocks [Cr(cpdc)3]3−. The addition of rare-earth metal nitrates (Cr:Ln = 1:2) in this reaction led to the formation of a series of trimetallic 3D coordination polymers {[Ba3Ln2Cr4(cpdc)12(H2O)24]·8H2O}n (3Ln, Ln = Gd, Tb, Dy, Ho, Er, Yb, Y), in whose structures tris-chelate fragments [Cr(cpdc)3]3− are bound in layers by Ln3+ ions and, further, in a framework due to the coordination of Ba2+ ions. The crystal structures of 1, 2, and 3Gd were determined by single-crystal X-ray diffraction (XRD), and isostructurality of all the compounds in the series 3Ln was proved by powder X-ray diffraction (PXRD). DC-magnetic susceptibility measurements revealed weak ferromagnetic exchange interactions between Cr3+ ions in compound 1 (J = +0.74 cm−1). According to ac-magnetic susceptibility measurements, complexes 3Er and 3Y exhibit field-induced slow relaxation of magnetization. According to the data of simultaneous thermal analysis (STA) and differential scanning calorimetry (DSC) performed under Ar atmosphere, dehydration of the compounds obtained takes place in one (for 1 and 3Gd) or three stages (for 2). The initial temperature of the organic part degradation process decreases when moving from compound 1 containing dimerized bis-chelate fragments [Cr2(OH)2(cpdc)4]4− (330 °C) to compounds 2 (276 °C) and 3Gd (261 °C) based on tris-chelate units [Cr(cpdc)3]3−.

Impact of Nitrate on the Removal of Pollutants from Water in Reducing Gas-Based Membrane Biofilm Reactors: A Review.

The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO4-), perchlorate (ClO4-)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO3-), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO3- inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR.

Anal fissures: An update on treatment options.

Anal fissure (AF) is the second most common anorectal complaint in healthcare settings. The presentation might be acute or chronic, characterised by severe pain with defaecation that persists for one to two hours. Non-surgical and surgical interventions are available based on the severity and persistence of the fissure. The aim of this article is to review the pathophysiology, clinical presentation andmanagement of AF under current guidelines. The aetiology of AF is unclear, although it is commonly associated with local trauma or associated chronic conditions. Acute AF is first treated with conservative therapy, including dietary fibre and sitz baths. Addition of topical nitrates, topical calcium channel blockers or botulinum toxin injection is indicated with failure of conservative treatment or at medical discretion. Surgical options are considered if AF persists despite treatment. Most present as hypertonic, but special consideration is needed for hypotonic or secondary presentations.

Dynamics of in vitro rumen methane production after nitrate addition

ABSTRACT The present study aimed to assess the dynamics of rumen methane (CH4) production following the addition of NaNO3. This was done using an in vitro rumen fermentation system that ensures continuous gas and methane assessments. Four different levels of NaNO3 were used to get the final nitrate concentrations of 0.5, 1.0, 1.5, and 2.0 mg/ml of rumen fluid. For each dose, corresponding controls contained sodium chloride and urea were realised to ensure comparable levels of sodium and nitrogen. The addition of nitrates had slight effect on the intensity of fermentation because the total gas produced minus CH4 (total methane-free gas) only went down at the highest dose (2.0 mg/ml), and the final concentrations of SCFA were the same at all doses. The most evident effect was a modification of the SCFA profile (low concentrations of propionate and valerate, progressive increments of acetate, and decreases of butyrate) and a reduction in overall CH4 production. The CH4 yield for the 0.5 mg/ml dose was not different from control in the entire fermentation. Yield of the 1.0 mg/ml dose was significantly lower than the control group (p < 0.05) only within the initial 24-h period, and higher dosages (1.5 and 2.0 mg/ml) were lower during the entire fermentation (p < 0.01). Methane yields were well fitted with the Gompertz model, but only the highest level of nitrate inclusion had a significant impact on the majority of model parameters (p < 0.01). The linear regressions between CH4 yields (y) and the amounts of nitrates (x) at progressive fermentation durations (e.g. 6, 12, 24, and 48 h) produced equations with increasing absolute slopes (from −0.069 to −0.517 ml/mg of nitrate). Therefore, nitrate reduced rumen CH4 yield in a dose-dependent manner: the impact of low doses was primarily observed at the initial stages of fermentation, whereas high doses exhibited effectiveness throughout the entire fermentation process. In conclusion, in batch fermentation systems, the dose effect of nitrates on methane yield was time dependent.

Evidence of the mechanism underlying zinc protoporphyrin IX formation in nitrite/nitrate-free dry-cured Parma ham

A large amount of zinc protoporphyrin IX (ZnPP) is found in nitrite/nitrate-free dry-cured meat products, such as Parma ham, and is known to contribute to the favorable bright red color of the latter. ZnPP is a metalloporphyrin, in which zinc is coordinated, instead of iron, in the porphyrin ring. ZnPP proved to be more stable than heme, and its formation should be favored in dried meat products to improve color without the addition of nitrites or nitrates. Toward that, understanding the mechanisms of formation of ZnPP in nitrite/nitrate-free dry-cured ham would be important. In this lecture, I introduce some of our research group's findings regarding the endogenous and exogenous factors contributing to the formation and distribution of ZnPP in Parma ham and why ZnPP formation is suppressed in common cured meat products.

Effect of nitrate reduction and storage time on the antioxidative properties, biogenic amines and amino acid profile of dry fermented loins

SummaryThe aim of this work was to evaluate the effect of nitrate reduction and storage time on the content of amino acids and biogenic amines (BAs), total antioxidant capacity (TAC) and antioxidative properties of peptides isolated from dry fermented loins. The results showed that reducing the addition of nitrates increased the amount of BAs formed during storage of dry fermented loins. The lowest TAC value (tested by ABTS assay) was recorded for the sample with the highest nitrate addition (150 mg kg‐1) at beginning, while the highest value was noted for the sample without nitrate addition at 180 days of storage. The amino acid profile showed that dry fermented loin with the highest addition of nitrate was characterised by a significantly lower content of amino acids, which are precursors of key aroma compounds compared with loin samples with a lower amount of added sodium nitrate. The sum of ranking differences (SRD) indicated that loin sample with traditional addition of nitrate (150 mg kg‐1) after 120 days of storage was characterised by the lowest SRD result, which means that they are the closest to the assumed values, that is the lowest content of BAs, the highest antioxidant activity and amino acid patterns recommended by WHO/FAO/UNU Experts.

Microbiological and sensory evaluation of meat sausage using thyme (Thymus vulgaris, L.) essential oil and powdered beet juice (Beta vulgaris L., Early Wonder cultivar)

Essential oils have been studied to replace synthetic chemical preservatives, among these oils, the thyme essential oil stands out. However, in addition to promoting microbial control, synthetic chemical preservatives impart a characteristic color to inlaid products, a parameter not attained by the application of essential oils. This study aimed to evaluate the effect of the joint addition of thyme essential oil and powdered beet juice to meat sausage, for a partial or total reduction of the addition of nitrates and nitrites. The thyme essential oil showed a high inhibitory action against Staphylococcus aureus and Escherichia coli in the concentration of 9.17 mg/mL, and bactericidal effect in the concentrations of 9.17 mg/mL and 36.68 mg/mL respectively, in all tests applied in vitro. When applied to meat sausages, it showed an inhibitory effect against coagulase-positive Staphylococcus, reducing the microorganism count, and partial inhibition of aerobic mesophilic bacteria. No interference was observed in the multiplication of thermotolerant coliforms in the meat product. When evaluated sensorially, the sausage presented good general acceptability, with acceptance levels above 75%. The combined uses of thyme essential oil and powdered beet juice showed potential viability for use in substitution for nitrates and nitrites in meat sausages.

Sulfur dioxide removal by mesoporous silica KCC-1 modified with low-coverage metal nitrates

The removal of sulfur dioxide (SO2) from flue gas using fibrous mesoporous silica KCC-1 synthesized via microwave-assisted hydrothermal method was observed. The sorbent was modified by introducing nitrate salts of sodium (Na) and calcium (Ca) at 5 wt. % metal loading via incipient wet impregnation method. The SO2 breakthrough experiment was conducted in a vertical quartz-column reactor at atmospheric pressure and temperature of 323 K in the presence of 0.3 % SO2/N2. The SEM micrograph of KCC-1 exhibited a well-defined fibrous morphology consisting of colloidal spheres of 240–1160 nm in diameter. Addition of metal nitrates resulted in the reduction of surface area, total pore volume and minor breakage of the silica framework. The adsorption capacities of all samples were measured at C/C0 = 0.5, where the addition of sodium (Na5/KCC-1) and calcium (Ca5/KCC-1) enhanced the removal capacity by 1.88 and 2 times higher than the parent KCC-1 respectively. Even though sodium is expected to achieve better removal capacity due to its higher basicity and dispersion related to the lower crystallite size, its performance ultimately suffered from significant agglomeration of sodium oxide which created pore blockage, subsequently resulting in poor accessibility to the active sites.

Developing nitrate-nitrogen transport models using remotely-sensed geospatial data of soil moisture profiles and wet depositions

Nutrients loads in aquatic systems are dynamic and highly influenced by changing the land, soil, and atmospheric conditions. This study enhances water quality modeling by providing novel nitrate transport models using remotely-sensed geospatial data, allowing for dynamic predictions of nitrate loads in watersheds. One factor at a time, sensitivity analysis was employed in the classical nitrate transport model to incorporate the impacts of 1) nitrates in the soil moisture profiles 2) wet deposition of nitrates and 3) the synergistic effects of multiple atmospheric and soil effects on nitrate-nitrogen in catchments. The study found that the effects of soil moisture profiles were dominant than the wet deposition in the evaluation of nitrate-nitrogen in catchments. The addition of nitrates from soil moisture profile, wet deposition and both together effectively increased the annual average nitrates in the Fish River catchment from 0.180 kg/ha to 0.187 kg/ha, 0.396 kg/ha and 0.381 kg/ha respectively. Their additions consistently increased the nitrate loads from spring to winter seasons but exhibited different seasonal trends for soils such as silty sand and fine sand. The models developed in this study can be utilized in water quality assessment tools for effective dynamic predictions of nutrients loads into water bodies.

Nitrates and Nitrites in meat products

Nitrates and nitrites have been traditionally used as curing agents in the production of cured meat products. Beneficial effects of the addition of nitrates and nitrites to meat products are the improvement of quality characteristics as well as the microbiological safety. The nitrates and nitrites are mainly responsible for the development of the distinct flavor, the stability of the red color, as well as the protection against lipid oxidation in cured meat products. The nitrites show important bacteriostatic and bacteriocidal activity against several spoilage bacteria as well as foodborne pathogens found in meat products. The nitrites prevent the growth and toxin production by Clostridium botulinum. According to Commission Regulation (EU) No. 1129/2011, nitrates (sodium nitrate, E251; potassium nitrate, E252) and nitrites (potassium nitrite, E249; sodium nitrite, E250) are listed as permitted food additives. Nitrates are relatively non-toxic, but nitrites, and nitrites metabolic compounds such as nitric oxide and N-nitroso compounds, have raised concern over potential adverse health effects. Recently, the International Agency for Research on Cancer (IARC) concluded that ingested nitrates or nitrites are probable carcinogen to humans under conditions favoring the endogenous nitrosation. Legal limits for the addition of nitrates and nitrites have been set by several countries and EU [Commission Regulation (EU) No. 601/2014]. Several data from recent reviews conducted in several countries on the levels of nitrates and nitrites in cured meat products were summarized. In recent reviews, the residual levels of nitrites in cured meat samples have been constantly reduced and are in accordance with the legal limits set by most countries.

Determination of endogenous concentrations of nitrites and nitrates in different types of cheese in the United States: method development and validation using ion chromatography

ABSTRACTNitrites and nitrates can be present in dairy products from both endogenous and exogenous sources. In the European Union (EU), 150 mg kg–1 of nitrates are allowed to be added to the cheese milk during the manufacturing process. The CODEX General Standard for Food Additives has a maximum permitted level of 50 mg kg–1 residue in cheese, while in the United States (U.S.) nitrates are unapproved for use as food additives in cheese. In order to be able to investigate imported cheeses for nitrates intentionally added as preservatives and the endogenous concentrations of nitrates and nitrites present in cheeses in the U.S. marketplace, a method was developed and validated using ion chromatography with conductivity detection. A market sampling of cheese samples purchased in the Washington DC metro area was performed. In 64 samples of cheese, concentrations ranged from below the method detection limit (MDL) to 26 mg kg–1 for nitrates and no concentrations of nitrites were found in any of the cheese samples above the MDL of 0.1 mg kg–1. A majority of the samples (93%) had concentrations below 10 mg kg–1, which indicate the presence of endogenous nitrates. The samples with concentrations above 10 mg kg–1 were mainly processed cheese spread, which can contain additional ingredients often of plant-based origin. These ingredients are likely the cause of the elevated nitrate concentrations. The analysis of 12 additional cheese samples that are liable to the intentional addition of nitrates, 9 of which were imported, indicated that in this limited study, concentrations of nitrate in the U.S.-produced cheeses did not differ from those in imported samples.

Management of stable angina: A commentary on the European Society of Cardiology guidelines.

In 2013 the European Society of Cardiology (ESC) released new guidelines on the management of stable coronary artery disease. These guidelines update and replace the previous ESC guidelines on the management of stable angina pectoris, issued in 2006. There are several new aspects in the 2013 ESC guidelines compared with the 2006 version. This opinion paper provides an in-depth interpretation of the ESC guidelines with regard to these issues, to help physicians in making evidence-based therapeutic choices in their routine clinical practice. The first new element is the definition of stable coronary artery disease itself, which has now broadened from a 'simple' symptom, angina pectoris, to a more complex disease that can even be asymptomatic. In the first-line setting, the major changes in the new guidelines are the upgrading of calcium channel blockers, the distinction between dihydropyridines and non-dihydropyridine calcium channel blockers, and the presence of important statements regarding the combination of calcium channel blockers with beta-blockers. In the second-line setting, the 2013 ESC guidelines recommend the addition of long-acting nitrates, ivabradine, nicorandil or ranolazine to first-line agents. Trimetazidine may also be considered. However, no clear distinction is made among different second-line drugs, despite different quality of evidence in favour of these agents. For example, the use of ranolazine is supported by strong and recent evidence, while data supporting the use of the traditional agents appear relatively scanty.

Effect of anions on the oxidation of organic compounds with ultrasonically activated persulfate

The effect of anions typically present in natural and waste waters on the oxidation of the azo dye methyl orange with persulfate activated with high-frequency ultrasound was studied. At a chloride concentration of 1 mmol/L, the rate constant of substrate oxidation increased 1.5-fold, but further increase in the chloride content retarded the process. The addition of nitrates, carbonates, and hydrogen carbonates to the solution inhibited the process (NO3- < HCO3- ~ CO32-). These tendencies were in good agreement with the results obtained on a real water matrix of the natural surface water from Lake Baikal.

Exploration of Ammonia Production in Blue Green Algae By Bioelectrocatalytic Methods

Ammonia is an important compound to many industries around the world. Most of the fertilizers used by crop growers have ammonia as an essential ingredient. It can also be useful as a fuel source, offering greater energy density per unit than hydrogen, and greater safety. Currently, the predominant method for producing ammonia on an industrial scale is by the Haber-Bosch process. This process uses steam evolution of methane to provide H2 gas, which is then combined with N2 gas over an iron catalyst to form NH3. This process requires large amounts of energy as well as high temperatures and pressures. In this report, an alternative method for ammonia production is explored. With Anabaena Variabilis, a photosynthetic cyanobacteria, on a carbon electrode, ammonia can be generated at ambient temperatures and pressures at little energy cost, a few tenths of a volt.1,2 A bioelectrocatalytic device has been constructed by immobilizing whole cell a. variabilis in a Nafion film modified with a trimethyl octadecyl ammonium bromide (TMODA) salt at an electrode surface.3 The ammonium salt enlarges the pore size of the Nafion structure while neutralizing the acidic environment of the polymer, and provides a hospitable matrix for the algae cells. The polymer modified electrode provides the driving force and reductive microenvironment to facilitate production of NH3 by nitrogenase and nitrate/nitrite reductase enzymes present in a. variabilis. Ammonia production by cyanobacteria was increased from basal levels of 2.8 ± 0.4 µM produced over a two week period, to 22 ± 8 µM produced in 20 minutes under mild voltage perturbation, a roughly 104 increase in rate. Control of ammonia producing structures (nitrogenase or nitrate/nitrite reductase) can be accomplished by growing the algae with and without fixed sources of nitrogen in the growth media. The addition of nitrates and nitrites to the electrolyte during voltammetric perturbation varies linearly with ammonia increased with substrate.

SEVERAL ASPECTS OF DILTIAZEM AND ORGANIC NITRATES USAGE IN VARIOUS SEVERITY STABLE ANGINA PATIENTS

Aim. To estimate the effectiveness of Diltiazem (Dlt) and its combination with nitrates in patients with ischemic heart disease (CHD) and arterial hypertension (AH) according to exercise tolerance by functional class (FC) of stable angina (StA).Material and methods. 30 CHD male patients at the age of 58,8±7,5 with StA II FC (n=11), III FC (n=19) and 1–2 stage AH were included into open randomized placebo-controlled study. Drug therapy: Dlt 90–180 mg bid, isosorbide 5-mononitrate 50 mg qd, trinitrolong 2 mg bid or tid. Effectiveness of the regular drug intake was controlled by repeated exercise tolerance tests (ETT) by treadmill with the value of threshold effort time (ThT). Total duration of treatment was 4 weeks.Results. At the beginning the ThT was 249,8±23,4 s for III FC and 368,6±14,4 s for II FC patients (p=0,0001). One dose of Dlt increased ThT in 5 hours to 387,3±37,5 s and 533,7±20,3 s in both groups, respectively (p=0,001), with the difference between groups being held. During regular Dlt intake the ThT in III FC angina patients reached 441,1±26,8 s, but in II FC patients in has not changed: 526,1±22,0 s. Additional nitrate intake to III FC group led to even more increase of ThT; in II FC patients there was no improvement. Combination therapy by Dlt and nitrates has not led to differences between III and II FC groups by achieved exercise tolerance. Hemodynamic parameters in both groups has not differ.Conclusion. For patients with III FC stable angina it is recommended to prescribe Dlt with nitrates because of additional effectiveness of combination that might be linked to the influence on cardiac hemodynamics and to improvement of myocardium metabolism. In II FC stable angina Dlt alone reaches its maximum antiischemic effect so the addition of nitrates is not helpful.

Response surface methodology as a decision-making tool for optimization of culture conditions of green microalgae Chlorella spp. for biodiesel production

We have evaluated process optimization and the interactive effects of a number of variables using a Box–Behnken design of response surface methodology (RSM). The process variables nitrate, phosphate, glucose and pH were optimized to enhance the cell growth rate, lipid accumulation and other biochemical parameters of Chlorella spp. The most significant increase in lipid production (dry cell weight basis) occurred at limited concentrations of nitrate and phosphate, 1 % glucose and pH 7.5. The addition of nitrates during the mid-lag and mid-exponential phases produced the maximum inhibitory effect on lipid accumulation and the presence of yeast extract led to a further enhancement of lipid accumulation. Of all the media tested, BG-11 was the best suited medium for algal biomass production and chlorophyll content. A significant increase in algal biomass was observed in BG-11 supplemented with bicarbonate and glucose (1 %). The maximum specific growth rate observed was on 9th day of culturing. Results of optimization of process variables through response surface methodology and optimization of various other conditions reflect cutting edge research directed towards increasing algal biomass and lipid content for biodiesel production using an efficient economical technological approach.

Final results of Australasian Gastrointestinal Trials Group ARCTIC study: an audit of raltitrexed for patients with cardiac toxicity induced by fluoropyrimidines

Cardiac toxicity an uncommon but serious side-effect of some fluoropyrimides. Cardiac toxicity from raltitrexed is rarely reported. With this background, we initiated this study to investigate the incidence of cardiac events in patients who had switched to raltitrexed following cardiac toxicity from fluoropyrimidines (5-fluorouracil or capecitabine). Pharmacy records were used to identify patients receiving raltitrexed from January 2004 till March 2012. Medical records were then reviewed to confirm the use of raltitrexed after cardiac toxicity from 5-fluorouracil or capecitabine. The primary end point was the rate of further cardiac events after commencing raltitrexed. Forty-two patients were identified and the majority had colorectal cancer. Prior regimens included 5-fluorouracil ± leucovorin, capecitabine alone, FOLFOX, FOLFIRI, epirubicin/cisplatin/5-fluorouracil, and capecitabine/oxaliplatin. Seven patients (17%) had bolus 5-fluorouracil regimens, 26 patients (62%) had infusion 5-fluorouracil regimens, and 9 patients (21%) had capecitabine alone or in combination. Angina was the most common cardiac toxicity from 5-fluorouracil or capecitabine and usually occurred in the first or the second cycle. Four patients after their first cardiac event continued with the same 5-fluorouracil or capecitabine regimen with the addition of nitrates and calcium antagonists but still had further cardiac events. After changing to raltitrexed, either as a single agent or a continuing combination regimen, no patients experienced further cardiac toxicity. Raltitrexed is associated with no significant cardiac toxicity in patients who have experienced prior cardiac toxicity from 5-fluorouracil or capecitabine. Raltitrexed, alone or in combination with oxaliplatin or irinotecan, provides a safe option in terms of cardiac toxicity for such patients.

Étude in vitro de l’impact de sédiments artificiellement contaminés par l’anthracène : effets sur les bactéries indigènes et les nématodes libres marins

RésuméLa présente étude se propose d’évaluer, in vitro, l’impact de trois techniques de bioremédiation à savoir la biostimulation, la bioaugmentation et la combinaison de la biostimulation et de la bioaugmentation sur la microflore et la nématofaune après une contamination artificielle des sédiments lagunaires par l’anthracène. Cette contamination sédimentaire, tend à provoquer une réduction de la charge moyenne des bactéries hétérotrophes aérobies dans la colonne d’eau, à l’interface et dans le sédiment et en parallèle une diminution hautement significative des densités moyennes des nématodes dans tous les microcosmes contaminés par ce polluant. Après inoculation de la souche bactérienne Staphylococcus sp., l’augmentation de la charge bactérienne a été significative (p < 0,05) au niveau des trois compartiments dans les microcosmes contaminés par l’anthracène par rapport aux témoins. L’ajout des nitrates et des phosphates aux microcosmes contaminés a entraîné, par rapport aux témoins, une augmentation très significative des effectifs moyens de nématodes libres.AbstractThis study evaluates the in vitro impact of three bioremediation techniques: biostimulation, bioaugmentation, and a combination of biostimulation and bioaugmentation on microflora and nematofauna after an artificial contamination of lagoon sediments by anthracene. This sediment contamination tends to reduce the average load in aerobic heterotrophic bacteria in the water column, at the sediment interface and at the same time induces a highly significant decrease in the average densities of nematodes in all microcosms contaminated by this pollutant. After inoculation with the Staphylococcus sp. bacterial strain, the increase in bacterial load was significant (p < 0.05) in the three compartments of anthracene-contaminated microcosms with relation to the controls. The addition of nitrates and phosphates to the contaminated microcosms generated a highly significant increase in the average concentration of free-living nematodes with relation to the controls.

Anaerobic methane oxidation in soils and water ecosystems

The process of anaerobic methane oxidation has been studied for over 30 years on the example of bottom marine sediments and fresh water ecosystems. This paper presents a review of the results of these investigations. It is also demonstrated that this process can proceed not only in submerged but also in drained peat and automorphic sod-podzol soils. The latter soils continue to absorb methane after anaerobic conditions are created and an inhibitor of methane monooxygenase (acetylene) is introduced. Oxidated compounds (nitrates, sulphates) are stimulatory to gas absorption; deoxidated nitrogen compounds (ammonium chloride) do not produce significant changes. Incubation with the addition of nitrates and sulphates in an atmosphere of argon and methane results in an increase in the fraction and abundance of archaea in the soil. This is in agreement with the data obtained for aquatic inhabits.