Acid-soluble Compounds Research Articles

New Breakfast Cereal Developed with Sprouted Whole Ryegrass Flour: Evaluation of Technological and Nutritional Parameters.

Ryegrass is one such cereal that has been underutilized in human nutrition despite its high nutritional and functional value due to the presence of phytochemicals and dietary fibers. Exploiting ryegrass for human consumption is an exciting option, especially for countries that do not produce wheat, as it is easily adaptable and overgrows, making it economically viable. This study evaluated the nutritional content of γ-aminobutyric acid and bioactive compounds (total soluble phenolic compounds) and the physicochemical and technological properties of partially substituting maize flour (MF) with sprouted whole ryegrass flour (SR) in developing extrusion-cooked breakfast cereals. A completely randomized design with substitutions ranging from 0 to 20% of MF with SR was employed as the experimental strategy (p < 0.05). Partial incorporation of SR increased the content of γ-aminobutyric acid and total soluble phenolic compounds. Using sprouted grains can adversely affect the technological quality of extruded foods, mainly due to the activation of the amylolytic enzymes. Still, ryegrass, with its high dietary fiber and low lipid content, mitigates these negative effects. Consequently, breakfast cereals containing 4 and 8% SR exhibited better physicochemical properties when compared to SR12, SR16, SR20, and USR10, presenting reduced hardness and increased crispness, and were similar to SR0. These results are promising for ryegrass and suggest that combining the age-old sprouting process with extrusion can enhance the nutritional quality and bioactive compound content of cereal-based breakfast products while maintaining some technological parameters, especially crispiness, expansion index, water solubility index, and firmness, which are considered satisfactory.

Factors determining rhodium solubilization efficiency in molten K2CO3–K2O–B2O3–Al2O3 medium

Dilute-acid-soluble, complex rhodium oxides were generated in a molten K2CO3–K2O–B2O3–Al2O3 medium, and factors affecting their generation efficiency were investigated. Surface observation revealed that planar-shaped materials (the insoluble rhodium compounds) were covered by fine particles (the acid-soluble rhodium compounds) in the heat-treated rhodium. The fine particles contained Rh, K, Al, B, Ca, Si, and O. In contrast, the main components of the insoluble rhodium compounds were Rh, K, Al, Si, and O. Therefore, an efficient reaction of B and Ca with rhodium is an essential factor in solubilizing rhodium. The oxidation state of rhodium in the acid-soluble compounds was higher than that of the insoluble rhodium compounds, implying that efficient rhodium oxidation is another factor for rhodium solubilization. When air was supplied while synthesizing the rhodium compounds to enhance the oxidizing condition, rhodium extraction from the obtained heat-treated products increased to 74%.

Geochemical partition of chemical elements in Kastanozems and Solonetz in a local catchment within a semiarid landscape of SW Russia

The vertical and lateral migrations of chemical elements (ChEs) under semiarid conditions were studied in a soil catena within the uppermost local catchment (2 ha) in the NE part of the Ergeni Upland (the NW Kalmykia, SW Russia). The data were interpreted using the key soil properties typically influencing the mobilisation and accumulation capacity of ChEs: pH, electrical conductivity and soil organic and inorganic carbon content as well as clay, silt and sand fractions. The patterns of the vertical distributions of ChEs were similar in all soils (Kastanozems and Solonetz) irrespective of their topographic location, but the depth of translocation was larger in the gully bottom. The content of mobile fractions of Ca, Mn and, to a lesser extent, P was higher than a residual fraction, which means that these elements have the highest potential mobility in soils (considering the sum of the three mobile fractions: weakly bound acid-soluble, bound with complexes and (hydr)oxides of Fe and Mn). In Kastanozems and Solonetz, weakly bound acid-soluble forms of the readily soluble ChEs (B, Ca, K, Na and Sr), and acid-soluble compounds (of Cd, Fe, K, Na and P) as well as both acid-soluble compounds and complexes for biogenic heavy metals (Co, Cu and Mn) are the major actors of geochemical migration. In the gully catchment, spatial differentiation is governed by the availability of water and the presence of readily soluble compounds of B, Cl, Li, Na and S. Within the topsoil of Kastanozems and Solonetz, the mobility of ChEs decreases in the following order: Mn, Ca > Pb, Co, Cu > V, Ba, Zn > Fe, Al > K, Cr > Si and Ti. In Kastanozems and Solonetz, mobile B, Ca, K, Na, Sr and, to a lesser extent, Mg (in the whole soil profiles) as well as Ba, Be, Mo and S (in subsoil and parent materials) are weakly bound by carbonate and exchangeable compounds. Mobile Co, Cu and Mn are held by soil organic and inorganic complexes. Mobile Cd and Fe occurred mostly within compounds extracted by 1 M nitric acid. The content of elements differed from the parent materials more strongly in the topsoil of Kastanozems due to the accumulation of substances at the biogeochemical barrier in the A-horizon and in the subsoil of Solonetz due to the accumulation of substances at the sorption barrier in the natric horizon. The ‘Solonetz at microhighs–Kastanozems at microdepressions’ is a translocation-solutional microcatena due to the migration of the most mobile chemicals in the soil solution in spring (downward movement) and the dry season (upward movement). Furthermore, the 'Kastanozems at the interfluve–Kastanozems at the gully bottom' is a leaching catena due to the downward movement of less mobile chemicals with melted snow and meteoric water.

Seasonal dynamics of lead content in sod-podzolic soil in dependence of mineral fertilizer application

Influence of prolonged use of increasing doses of mineral fertilizers (NPK by 0-30-60-90-120-150 kg of active matter/ha) on contents and dynamics of acid-soluble and mobile compounds of lead in an arable layer of the sod-podsolic soil was studied during the growing season of 2016. It has been established that prolonged application of fertilizers significantly increases the content of mobile forms of the element in the soil at application of NPK in dozes of 30 and 150 kg of active matter / ha as compared to the control (average values are 0.57, 0.51, and 0.33, respectively). However, even prolonged application of large doses of mineral fertilizers does not lead to a significant increase in lead content in the arable horizons of the soil. Acid-soluble lead compounds range from 2.46 (N0P0K0) to 5.33 mg/kg (N150P150K150); the content of mobile lead compounds from 0.08 to 1.31 mg/kg of soil, respectively, at maximum acceptable concentration of 6.0 mg/kg. The content of acid-soluble and mobile lead compounds in arable horizons of sod-podzolic soil had a reliable dynamics during the growing season on all variants of the experiment. An increase in the content and acid-soluble and mobile compounds is usually observed in the first half of the growing season (end of May - beginning of June), which is probably due to the active mobilization of lead from slow-moving compounds as a result of the activation of microbiological activity under a favorable hydrothermal regime. In the same period, the portion of mobile fractions of lead to acid-soluble fractions increases. Application of increasing doses of fertilizers (30, 60, 90, 120 and 150 kg/ha of active matter) does not always show a reliable increase in the content of the element in the corresponding variant, which is obviously due to the influence of unaccounted factors. A clearer content dynamics is characteristic of mobile lead compounds.

Fractionation of some natural radionuclides in Albic Retisol

In the present work, the fractionation of heavy natural radionuclides was investigated in Albic Retisol in the Moscow region of Russia. Fractionation was performed using the Pavlotskaya method. 238U and 232Тh were measured via inductively coupled plasma mass spectrometry and 226Ra was measured using an alpha-radiometer that considered the decay of Ra isotopes and accumulation of the resulting decay-related products. Results showed that the potential mobility of radionuclides during migration to adjacent environments and biological availability to plants follows the order 226Ra >238U > 232Тh. The depletion of 226Ra in the humus horizon A was manifested as a decrease in the 226Ra/238U activity ratio to below 1 in fraction F4.1 (associated with organic matter) and fraction F4.2 (acid-soluble compounds). The profile distribution of 226Ra and 238U in the residual fraction revealed the genetic relationship between these radionuclides. Mobile compounds of 238U and 232Th leached into the lower part of the profile where they became fixed, mainly as the components of fractions associated with organic matter and crystallized iron oxides. A similar profile distribution was found for 238U, 232Тh, and Fe in the acid-soluble fraction associated with crystallized iron oxides. The results obtained herein can form the basis for regulating the mobility and bioavailability of radionuclides to ameliorate their adverse effects on plants and soil ecosystems.

Effect of different control applications on Cuscuta campestris, and biochemical content of eggplant

The current study was undertaken to stimulate the physiological resistance and active compounds in eggplant to prevent the development of Cuscuta campestris (Dodder), to reduce its spread in field and also detection of selective herbicide to control it with minimum damage to eggplant fields in Iraq. A field experiment was conducted in Al-Qizuina, province of Najaf during the 2017 growing season to achieve the above aim. Treatments (herbicide and nutrients) were arranged within randomized complete block design (RCBD) with three replicates. The results showed significant differences among treatments when boric acid gave the greatest leaf content of carbohydrates, phosphorus, boron, total chlorophyll, and growth-promoting hormones (IAA and GA3) in eggplant, fruit content of ascorbic acid and total soluble compounds. However, the Na2SiO3 resulted in higher leaf content of silicon and salicylic acid while urea treatment gave greater nitrogen and protein in the crop. Similarly, treatments of calcium chloride (CaCl2) and K2SO4 were higher in calcium and potassium, respectively. The growth inhibitor hormones (ABA) were greater in the mechanical control treatment, while the total phenols were very high in the sulfosulfuron treatment. Based on the GC–MS analysis of herbicide residues, sulfosulfuron concentration was below the level of detection in the eggplants fruits confirming their safety for human consumption. Using sulfosulfuron with plant nutrients together can enhance resistance in eggplant against C. campestris.

Heavy Metals and Arsenic in Soils and Street Dust of the Southeastern Administrative District of Moscow: Long-Term Data

The soils and street dust of the Southeastern administrative district of Moscow were analyzed for chemical properties and the content of acid-soluble and mobile compounds of heavy metals (HMs) and arsenic over three time spans: the end of industrial (1995), transitional (2004 and 2012), and recent postindustrial (2017) periods of the city development. The acid–base properties of soils and street dust have not changed during this period. However, the content of exchangeable sodium has considerably increased (to 20-fold), as well as the contents of calcium and organic matter. The total HM and arsenic contents in soils and street dust tend to decrease because of a reduction in the number of industrial facilities and periodic replacement of lawn soils. Ag, Hg, Sb, Zn, and As have the highest clarkes of concentration in soils and Sb, Zn, Hg, Ag, Cu, Pb, Mo, As, Cd, Cr, and Ni, in street dust. The degree of extraction of the acid-soluble compounds of several HMs in soils and street dust is very high but it decreases from 1995 to 2017. The amount of mobile HM compounds has decreased. However, the share of soil and street dust samples with the Cu, Zn, and Pb mobile compounds exceeding the maximum permissible concentrations is still high.

Alumina and Silica Produced by Chlorination of Power Plant Fly Ash Treatment

We describe a process of chlorination of fly ash with either chlorine gas or calcium chloride, which successfully decomposes mullite and permits the extraction of a number of industrially useful, acid-soluble compounds. As a guide for determining optimal input molar ratios and temperatures, the Gibbs energies for three groups of reactions of major fly ash components between 973 K and 1473 K were calculated: (1) chlorination with chlorine gas; (2) chlorination with chlorine gas in the presence of coal; (3) chlorination with calcium chloride. Laboratory-scale measurements with fly ash from six coal combustion power plants in Kazakhstan show that chlorination with either calcium chloride or chlorine gas allows efficient extraction of alumina (α-Al2O3) and silica with both high yield and purity.

Studies on Hydrometallurgical Treatment of Oxydized Gold-Bearing Copper Ore

Inherent problems of oxidized gold-bearing copper ores processing and a comparison of hydrometallurgical methods, applied for such materials, are discussed in this article. Studies on sulfuric acid and cyanide leaching have been carried out, using the following sample of oxidized ore from one of the copper deposits (Kyrgyzstan), %: 15 Mg O, 45.6 SiO2, 0.1 S, 20 Ca O, 12.1 Fe2O3, 0.86 Cu, 1.78 Au, 9.61 Ag. Studies have been carried out. Agitation sulfuric acid leaching able to extract up to 29.9% of copper. At the same time, column sulfuric acid leaching able to extract up to 78.5% of total copper and 85.23% of copper presented by acid-soluble compounds. In case of precious metals, the agitation cyanide leaching is able to extract up to 97.6% of gold in 24 h. Increasing the grinding fineness up to 90% - 74 μm reduces cyanidation duration down to 12 h. The consumption of sodium cyanide is 4.8 kg/t of ore. At the same time, column cyanide allows to extract 73.5% Au and 81.9% Ag during 111 days, whereas 52.4% of gold is recovered in the first 10 days. Consumption of sodium cyanide is 5.45 kg/t. The most efficient ways for processing of such materials are proposed.

Heavy metals in ordinary chernozems on slopes of different gradients and aspects

The impact of slope aspect and gradient on the contents and distribution of heavy metals (Mn, Cu, Zn, Co, Ni, Pb, and Cd) in the profiles of ordinary chernozem (Haplic Chernozems) was studied in Kursk oblast. Slope aspect was found to be a significant factor controlling the distribution of most of the bulk, mobile, and acid-soluble compounds of heavy metals, whereas the position on the slope (slope gradient) did not exert a significant influence on the distribution of elements. Bulk compounds of Co, Ni, Pb, and Cd showed the eluvial type of distribution in the soil profiles along with accumulation in the lower horizons. Distribution patterns of the mobile Cu, Co, Ni, Pb, and Cd were similar to those of the bulk ones. The latter phenomenon may be attributed to the high content of carbonates, an increased content of clay, and some alkalization of the soil solution in the lower horizons.

Nitrogen and phosphorus compounds in the aleurone grains of Iris pseudoacorus endosperm and Pisum sativum cotyledons

Aleurone grains from &lt;i&gt;Iris pseudoacorus&lt;/i&gt; endosperm and &lt;i&gt;Pisum sativum&lt;/i&gt; cotyledons were isolated partly according to Tombs's method (1967). Nitrogen compounds content was determined in them by Kjeldahl's micromethod, and in the particular fractions after Thiman and Laloraya (1960). Mainly protein N was detected in the aleurone grains, constituting 14.8 and 15.2 per cent of the dry mass of pea and Iris seeds, respectively. Moreover, phosphorus compounds were fractionated according to Holden and Pirie (1955). Analyses demonstrated the presence in aleurone grains of inorganic P, acid-soluble organophosphorus compounds, phospholipids and RNA.

Formulation and evaluation of gastroretentive floating drug delivery system of dipyridamole

A multiple-unit floating alginate bead drug delivery system with prolonged stomach retention time was developed in this study. The floating alginate beads were prepared by ionic cross-linking method, using CaCO3 as the gas-forming agent. Over 92% of the beads remained floating after 9 h. In order to prepare sustained-release dosage forms of dipyridamole, the solid dispersion technique was applied using a blend of Eudragit L100 and Eudragit RLPO. Afterwards, the solid dispersions of dipyridamole were incorporated into the floating alginate beads. The drug release was modified by changing the ratio of Eudragit RLPO and Eudragit L100 in the solid dispersions. The in vivo results showed that the relative bioavailability of alginate beads was enhanced by approximately 2.52-fold compared with that of the commercial tablet. Therefore, our study illustrated the potential use of floating alginate beads combined with the solid dispersion technique for the delivery of acid-soluble compounds, such as dipyridamole.

What is the composition of AIR? Pyrolysis-GC–MS characterization of acid-insoluble residue from fresh litter and organic horizons under boreal forests in southern Finland

High concentrations of the acid-insoluble residue (AIR, also known as “Klason lignin”) in decomposing litter are considered to indicate high resistance to decomposition; however, the chemical composition of AIR in different types of litter and soil organic matter is poorly understood. In the present study, we characterized samples of common litter (L) types in boreal forests (needle, coarse tree, and moss), as well as fragmented litter (F), and humus (H) layers in two south boreal forest sites using a combination of sequential fractionation and pyrolysis-GC–MS. The results showed that the unfractionated samples were composed of cellulose-derived carbohydrates, guaiacyl-type lignin and other polyphenolic compounds, and that there was little variation among samples. However, pyrolysis-GC–MS analyses of AIR demonstrated that the composition of the AIR fraction differed among the analyzed litter materials as well as between the layers in the soil organic horizon. In the F and H layers, the AIR fraction contained guaiacyl-type lignin and other polyphenolics, as well as lipophilic compounds, which were indicated by the pyrolysis product methyldehydroabietate and short-chain fatty acids. In the AIR fraction, only small amounts of carbohydrate-derived compounds were detected, confirming that the sequential fractionation method efficiently removes soluble polysaccharides. The AIR fraction was poorly soluble in all solvents. The results presented here confirm that the sequential fractionation method efficiently separates water-, chloroform-, and acid-soluble (72% H2SO4) compounds from acid-insoluble compounds (AIR). However, AIR was shown to be a mixture of polyphenolic (mainly lignin-derived) and lipophilic (including fatty acids and resin acid) structures, and may therefore be a poor indicator of lignin and phenolic compounds when investigating the F and H layers in the organic horizon.

Application of chemical fractionation methods for characterisation of biofuels, waste derived fuels and CFB co-combustion fly ashes

In the important efforts to decrease the net CO 2 emissions to the atmosphere, new, alternative fuels are being included in the fuel mixes used in utility boilers. However, these fuels have ash properties that are different from those of the traditionally used fuels and in some cases technical problems, such as ash fouling and corrosion occur due to this. Therefore, diagnostic and predictive methods are developed and used to avoid such problems. Determination of the chemical association forms of important elements, such as potassium and sodium, in the fuel by chemical fractionation is a method well defined for coal and biofuels, such as wood pellets, bark and forest residues. Chemical fractionation is a step by step leaching method extracting water soluble salts in the first step, ion exchangeable elements, such as organically associated sodium, calcium and magnesium in the second step and acid soluble compounds such as carbonates and sulfates in the third step. The solid residue fraction consists of silicates, oxides, sulfides and other minerals. The compound extracted in the two first steps is considered reactive in the combustion with a few exceptions. In this work, it has been applied to some waste fuels, i.e. sewage sludge, straw and refuse derived fuel (RDF), as well as to coal and wood. The present work also includes results from combustion tests in a fluidised bed boiler where three blends of the investigated fuels were used. The fractionation results for the fuel blends are weighted results of the fractionations of the pure fuels discussed above which are compared with fractionations of their corresponding fly ashes. The co-combustion strategy gave very good results in reducing ash problems. Possible chemical mechanisms involved are discussed in the article.

Comparison of antimicrobial activity in the epidermal mucus extracts of fish

The mucus layer on the surface of fish consists of several antimicrobial agents that provide a first line of defense against invading pathogens. To date, little is known about the antimicrobial properties of the mucus of Arctic char ( Salvelinus alpinus), brook trout ( S. fontinalis), koi carp ( Cyprinus carpio sub sp. koi), striped bass ( Morone saxatilis), haddock ( Melanogrammus aeglefinus) and hagfish ( Myxine glutinosa). The epidermal mucus samples from these fish were extracted with acidic, organic and aqueous solvents to identify potential antimicrobial agents including basic peptides, secondary metabolites, aqueous and acid soluble compounds. Initial screening of the mucus extracts against a susceptible strain of Salmonella enterica C610, showed a significant variation in antimicrobial activity among the fish species examined. The acidic mucus extracts of brook trout, haddock and hagfish exhibited bactericidal activity. The organic mucus extracts of brook trout, striped bass and koi carp showed bacteriostatic activity. There was no detectable activity in the aqueous mucus extracts. Further investigations of the activity of the acidic mucus extracts of brook trout, haddock and hagfish showed that these fish species had specific activity for fish and human pathogens, demonstrating the role of fish mucus in antimicrobial protection. In comparison to brook trout and haddock, the minimum bactericidal concentrations of hagfish acidic mucus extracts were found to be ∼ 1.5 to 3.0 times lower against fish pathogens and ∼ 1.6 to 6.6 folds lower for human pathogens. This preliminary information suggests that the mucus from these fish species may be a source of novel antimicrobial agents for fish and human health related applications.

Sulfidization of Acid-Soluble Barium Compounds with Sulfurous Petroleum Coke

The influence exerted by sulfur contained in petroleum coke on sulfidization of acid-soluble barium compounds formed in reductive calcination of recycled barium sulfate in sodium sulfide production was studied.

Inorganic Lead Toxicology

Lead is a health hazard for all humans. Especially children under the age of six are most at risk for lead poisoning. Lead toxicity causes hematological, gastrointestinal, and neurological dysfunction. Symptoms are usually noted with blood lead greater than 2 micromoles/L. Severe or prolonged exposure may also cause chronic nephropathy, hypertension, and reproductive impairment. Lead inhibits some enzymes, alters cellular calcium metabolism, stimulates synthesis of binding proteins in kidney, brain, and bone, and slows down nerve conduction. Acute lead poisoning is relatively infrequent and results from ingestion of acid soluble lead compounds or inhalation of lead vapors but chronic exposure to low levels of the metal is still a public health issue, especially among some minorities and socioeconomically disadvantaged groups. Lead has been used since prehistoric times, and has become widely distributed and mobilized in the environment. Exposure to and uptake of this non-essential element have consequently increased. Both occupational and environmental exposures to lead remain a serious problem in many developing and industrializing countries and a public health problem of global dimensions.

Analysis of intracellular nucleoside triphosphate levels in normal and tumor cell lines by high-performance liquid chromatography

A reversed-phase ion-pair high-performance liquid chromatographic method for the direct and simultaneous determination of ribonucleoside triphosphates and their corresponding deoxyribonucleoside triphosphates in trichloroacetic acid cell extracts is presented. Using this system, high resolution of nine acid-soluble compounds, including ADP, CTP, dCTP, GTP, UTP, dGTP, dTTP, ATP and dATP in 16 normal or tumor cell lines, is obtained. The method is based on an extraction of nucleotides from cells with a solution of 6% trichloroacetic acid followed by neutralization with the addition of 5 M K 2CO 3 just prior to HPLC analysis. Chromatographic separations were performed using a Symmetry C 18 3.5 μm (150×4.6 mm) column (Waters) equipped with a NovaPak C 18 Sentry guard column with UV detection at 254 nm. The HPLC columns were kept at 27 °C. The mobile phase was delivered at a flow-rate of 1.0 ml/min, with the following stepwise gradient elution program: A–B (60:40) at 0 min→(40:60) at 30 min→(40:60) at 60 min. Solvent A contained 10 m M tetrabutylammonium hydroxide, 10 m M KH 2PO 4 and 0.25% MeOH, and was adjusted to pH 6.9 with 1 M HCl. Solvent B consisted of 5.6 m M tetrabutylammonium hydroxide, 50 m M KH 2PO 4 and 30% MeOH, and was neutralized to pH 7.0 with 1 M NaOH. The calibration curves ( r>0.99) of the components in cell extracts were established with their aqueous standards. The average within-day precision for the nine compounds was 0.9%, and the average day-to-day precision was 5.0%. The detection limits (pmol) of the nine reagents were 1.39 (ADP), 4.32 (CTP), 15.5 (dCTP), 2.38 (GTP), 4.42 (UTP), 9.45 (dGTP), 14.6 (dTTP), 2.44 (ATP) and 11.8 (dATP). The recovery of this method for the standards ranged from 82.4 to 120.5%. The results for the detection of nucleotide pools in 16 normal and tumor cell lines were presented. In conclusion, this simplified analytical method enables the simultaneous quantitation of NTP and dNTP in cell or tissue extracts and may represent a valuable tool for the detection of minute alterations of intracellular NTP/dNTP pools induced by anticancer/antiviral drugs and diseases.

Status of iron in alluvial soils from the wisla river valley, Poland

Iron is the essential element for plant growth. Although most soils contain adequate total Fe, amounts that are available to plants might be inadequate. Plant available Fe depends on factors such as Fe species in the soil and the ability of plant roots to make Fe compounds soluble. In this paper, forms and mobility of Fe in soils formed from Wisla river sediments were evaluated. The soils of studied area although rich in total Fe, contain insufficient concentration of labile Fe, a plant available fraction. Sequential extraction procedure was used for the speciation of Fe fractions. Data obtained show very low Fe concentration in fractions of plant available Fe such as soluble and exchangeable Fe (0.5–2.2 mg kg−1 soil). Most of the Fe was found in the Fe oxide (over 12% of the total) and residual, fixed in silicate structures, fractions (more than 80% of the total). Substantial amounts of Fe is associated with soil organic matter. Iron associated with manganese oxides and acid soluble Fe compounds are present in minor amounts.

Organic Matter in the Genesis of High-Island Atoll Peloidal Phosphorites: The Lagoonal Link

ABSTRACT In the debate over the origin of insular phosphorites, found in the top parts of more or less uplifted atolls, evidence is provided by both organic geochemistry (abundance and composition of humic compounds and lipidic biomarkers) and carbon-isotope geochemistry for the formation of phosphatic peloids, as well as phosphatized bioclasts, in environments containing mostly cyanobacterial and microbial organic matter. The composition of hydrocarbons and fatty acids suggests that this organic matter has been altered through bacterial processes. The abundance of humic compounds and the common presence of concentrically laminated structure of many peloids indicate that these particles formed during early diagenesis in a microbiologically active environment. Our data were obtained from (1) elemental analysis of bulk organic matter associated with atoll phosphorites as well as of their acid-soluble and humic compounds, (2) Rock-Eval pyrolysis of bulk organic matter and, (3) chromatographic analyses of hydrocarbons and fatty acids. The conclusion of this study is that, whatever the source of phosphorus (guano, supermarine reef organisms, marine waters, or possibly endo-upwelling), phosphatogenesis proceeded through growth of lagoonal cyanobacterial biomass, the phosphorus of which being partly recycled during subsequent diagenetic steps. If closed lagoons are indeed favorable for preservation of organic matter and, therefore, of phosphorus, a closed morphology is not a prerequisite for the course of such processes. Similar d13C values in apatite CO3 and in total dissolved organic carbon in recent microbial atoll deposits suggest that such deposits may be precursors to such peloidal insular phosphorites.