Source Of Calcium Carbonate Research Articles

Benchmark soils on alluvial, fluvial and fluvio-glacial formations of the upper-Segre valley .

The upper reaches of the Segre river, flowing through the Pyrenees, offers a variety of geomorphic surfaces that allow us to study soil chronosequences. The objective of this work is to widen the knowledge about the main characteristics and formation processes of some benchmark soils developed on fluvio-glacial, alluvial-fan and terrace materials of Pleistocene and Holocene age related to the Segre river, either siliceous or carbonatic. This knowledge will allow us to identify soil forming processes, commonly found in Mediterranean environments such as carbonate redistribution, clay formation and mobilization and rubefaction, all as functions of parent material and age. Five profiles, ranging from the Lower Pleistocene to the Holocene were classified according to Soil Taxonomy/WRB. The Montferrer profile (Calcic Palexeralf /Calcic Cutanic Luvisol (Chromic) is a deep, partly decarbonated soil, with calcium carbonate accumulation in depth covering glacial features. The Torre del Remei profile (Typic Paleustalf /Cutanic Luvisol) developed on silicic moraines and shows an extreme clay formation and illuviation. The Alp (Typic Haplustalf /Cutanic Luvisol) and Tartera (Petric Calciustept /Petric Calcisol) soils are developed on alluvial fans with calcium carbonate sources. The former is partly decarbonated, whilst the latter is rubefacted on top and shows speleothem-like carbonate pendants with superposition of clay illuviation. The youngest profile, Abellerols, (Typic Calciustept /Typic Calcisol) shows only a partial decarbonation and calcite accumulation at depth. The results show that soil development is determined by the age of the surface and the source of calcite, either in the parent rock or brought by subsurface flow: clay illuviation is extreme in absence of it. Special morphologies of carbonate pendants are indicators of environmental conditions. The coexistence of clay coatings and secondary calcite can be explained by recarbonatation or by spatial differentiation of soil environments in the profile. One of the implications of this research is the inconsistence of using soil development indices based on morphological indicators when soils are formed on different parent materials and are subjected to different geomorphic dynamics.

Enhancement of biodiesel synthesis over highly active CaO derived from natural white bivalve clam shell

White bivalve clam shell (WBCS), a good source of calcium carbonate collected from sea shore was subjected to calcination–hydration–dehydration treatment to obtain CaO with high activity. The performance of the newly obtained CaO from the calcination–hydration–dehydration treatment of WBCS and commercial CaO was tested for their catalytic activity via transesterification of waste frying oil (WFO). The results showed that the methyl ester conversion for the commercial CaO was 67.57% whereas it was 94.25% for the CaO obtained from calcination–hydration–dehydration treatment of WBCS at a 7wt.% catalyst (based on oil weight), methanol to oil ratio of 12:1, reaction temperature of 65°C and reaction time of 1h.

Microwave irradiation of nanohydroxyapatite from chicken eggshells and duck eggshells.

Due to similarity in composition to the mineral component of bones and human hard tissues, hydroxyapatite with chemical formula Ca10(PO4)6(OH)2 has been widely used in medical field. Both chicken and duck eggshells are mainly composed of calcium carbonate. An attempt has been made to fabricate nanohydroxyapatite (nHA) by chicken (CES) and duck eggshells (DES) as calcium carbonate source (CaCO3). CES and DES were reacted with diammonium hydrogen [(NH4)2HPO4] solution and subjected to microwave heating at 15 mins. Under the effect of microwave irradiation, nHA was produced directly in the solution and involved in crystallographic transformation. Sample characterization was done using by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM).

Phosphating of Calcium Carbonate for Obtaining Hydroxyapatite from the Ostrich Egg Shell

The Hydroxyapatite (HA), the major component of the inorganic portion of bones, may be obtained from different sources for use as biomaterial in the reconstruction of critical bone defects. Among these resources, the eggshell appears as a promising alternative since it is a waste material which may be reused as a source of calcium carbonate after adequate treatment, giving rise to mineral hydroxyapatite. After morphological and physicochemical adjustments allowing its standardization and utilization, hydroxyapatite (HA) may turn into a potentially useful biomaterial for different experimental purposes. This paper aims to present a viable method for obtaining a hydroxyapatite from Ostrich eggshell by wet precipitation process. This phosphating technique with emphasis on the issue of sustainable reuse of disposable materials allows the production of a synthetic crystalline material with characteristics similar to those of bone and tooth. The structural characterization was performed by X-Ray diffraction and scanning electron microscopy with field emission gun and energy dispersive X-ray in the Military Institute of Engineering.

Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean

Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21,000 km(2)) and has one of the largest marine CaCO3 deposits (producing 25 megatons of CaCO3 per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m(-2 )s(-1)), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 10(5) tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean.

Monetaria moneta as a novel β-nucleating agent for isotactic polypropylene

Abstract Calcium carbonate as a filler material provides some β-nucleation capacity for polypropylene in production of particle-reinforced composites. Its effectiveness in this regard mainly depends on the source of calcium carbonate, but the mechanism is not cleared yet. In this study, the prepared Monetaria moneta powder with the main component of calcium carbonate revealed high β-nucleation capacity for polypropylene, which was enhanced with increasing the filler loading with the maximum performance at 5 wt.%. Heat treatment of M. moneta indicated that β-nucleation capability was due to the nano-layer structure of aragonite crystal type in which the lattice parameter has the c -axis perpendicular to the layer and the length of c -axis applied to the dimensional lattice matches the β-phase of PP. The M. moneta powder was observed as a strong β-nucleating agent different from the conventional nucleating agents.

Biogenic Fish-gut Calcium Carbonate is a Stable Amorphous Phase in the Gilt-head Seabream, Sparus aurata

The main source of calcium carbonate (CaCO3) in the ocean comes from the shells of calcifying planktonic organisms, but substantial amounts of CaCO3 are also produced in fish intestines. The precipitation of CaCO3 assists fish in intestinal water absorption and aids in whole body Ca2+ homeostasis. Here we report that the product formed in the intestinal lumen of the gilt-head seabream, Sparus aurata, is an amorphous calcium carbonate (ACC) phase. With FTIR spectroscopy and SEM imaging, our study shows that the fish-derived carbonates from S. aurata are maintained as a stable amorphous phase throughout the intestinal tract. Moreover, intestinal deposits contained up to 54 mol% Mg2+, the highest concentration yet reported in biogenic ACC. Mg is most likely responsible for stabilizing this inherently unstable mineral. The fish carbonates also displayed initial rapid dissolution when exposed to seawater, exhibiting a significant increase in carbonate concentration.

Optimization of biodiesel production using waste mussel shell catalyst

Calcium oxide is an appropriate catalyst for biodiesel production. In this study, an inexpensive and environment-friendly catalyst was used. The waste mussel shell collected in of Persian Gulf coast is a source of calcium carbonate which changes to calcium oxide in calcinations temperatures higher than 950°C. Transesterification reaction was done in the presence of soybean oil, methanol and mussel shell catalyst in a temperature of 60°C. Using response surface methodology (RSM) the effects of different parameters (calcination temperature, catalyst concentration and molar ratio of methanol to oil) were studied. Each parameter was set at three levels labeled as low, medium and high, respectively (calcination temperature of 950, 1000, and 1050°C; catalyst concentration of 6, 9 and 12wt.%; methanol to oil ratios of 12:1, 18:1 and 24:1). The results of the optimization implies that the calcination temperature of 1050°C, catalyst concentration of 12wt.%, and methanol to oil ratio of 24:1 provide the maximum values of purity and yield in biodiesel production. The reusability of mussel shell catalyst was studied for five times and the result showed that the catalyst re-calcination in reusability step has negative effects on the yield of biodiesel production.

Unsuitable habitat patches lead to severe underestimation of dynamics and gene flow in a zooplankton metapopulation

Migration and re-colonization enable organisms to persist in metapopulations. Re-colonization success may be limited by the number of arriving migrants or by patch quality. In a well-studied rock pool Daphnia metapopulation, it is frequently assumed that re-colonization is limited by the number of arriving migrants, and that all patches are equally suitable for colonization. This assumption strongly influences how observations about dynamics, epidemiology and population genetics for the entire metapopulation are interpreted. Here we test this assumption. In 627 rock pools, we found that high pH, high Ca(++) and high water conductivity were positively correlated with the presence of D. magna. The experimental release of D. magna into randomly chosen natural pools revealed the highest colonization success in pools with high pH. Next, we elevated pH and Ca(++) concentrations in natural pools by adding a system-specific natural source of calcium carbonate (either from crushed oyster shells or from eider duck droppings, which contain blue mussel shells). These treatments led to a rapid increase in pH and Ca(++) and strongly raised the likelihood that introduced D. magna would establish persistent populations. Therefore, we conclude that low pH and Ca(++) result in unsuitable colonization conditions in two-thirds of the untreated pools. A further experiment revealed that natural colonization rates were about five times higher in calcium-treated pools than in untreated pools. Finally, we observed that eider droppings are more frequently found in the catchment area of occupied pools, than they are in those of unoccupied pools, suggesting that the blue mussel shells contained in the eider droppings play an important role in making pools suitable for colonization and in enabling D. magna to persist. Thus, eider ducks are ecosystem engineers in this system. We recalculate typical metapopulation parameters to account for the unsuitable pools, resulting in a much more dynamic picture of this metapopulation than previously believed, with colonization rates and gene flow three to five times higher. These results have strong implications for metapopulation persistence, local and global genetic diversity, genetic rescue, gene flow and local adaptation. Our results emphasize that without verifying patch suitability, estimated rates of metapopulation dynamics can severely underestimate the true rates.

Investigation of Egg Shell Waste as an Enhancer in the Carburization of Mild Steel

This work has investigated the possibility of utilizing egg shell waste which is a rich source of calcium carbonate as an enhancer or energizer in the case hardening of mild steel using organic solid wastes like sugar cane, melon shells and aracaceae flower droppings as the carbon source. The mild steel specimens were inserted in carburizing boxes containing the carburizing material and carburized at a temperature of 920°C for 5 hours. They were then quenched in water, after which they were prepared for hardness test using Rockwell hardness tester, and for microscopic examination. The result showed that the carbonaceous organic waste used improved the case hardness of the steel. The result also showed that egg shell containing carburizing material produced higher case hardness on the steel than those carburizing materials without egg shell. Sugar cane waste produced a case hardness of 45.1HRC, with egg shell the case hardness became 45.5HRC. Melon shell waste produced a case hardness of 47.8HRC, and with egg shell the case hardness became 52.6 HRC. This hardness corresponded to an effective case depth of 0.65mm. Aracaceae flower wastes produced a case hardness of 56 HRC on the mild steel this corresponded to an effective case depth of 0.7mm, with egg shell the case hardness became 56.6 HRC with an effective case depth of 0.75mm. The calculated total case depth based on carburizing parameters was 1.34mm. The effect of egg shell waste as an enhancer in the carburization of mild steel has been established the result of the work has clearly shown that egg shell waste can be used in place of calcium carbonate to improve on the hardness value of mild steel during carburization. The success of this work has created another outlet for reducing the waste burden attributed to these solid wastes

Contemporary stromatolite formation in high intertidal rock pools, Giant's Causeway, Northern Ireland: preliminary observations.

ABSTRACT Cooper, J.A.G., Smith A.M., and Arnscheidt, J. 2013. Contemporary stromatolite formation in high intertidal rock pools, Giant's Causeway, Northern Ireland: preliminary observations. Contemporary stromatolites are known from a variety of settings ranging from Antarctic dry valleys to hypersaline tropical lagoons. Their formation requires a source of calcium carbonate, binding by cyanobacteria and the elimination of other competing organisms by extremes of environmental conditions. In this paper we report the contemporary development of stromatolites in intertidal rock pools at the Giant's Causeway, Northern Ireland. The rock pools are high in the tidal frame and located on the landward margin of wide rock platforms that dissipate all but the most energetic waves. They are only infrequently inundated by marine waters but are fed by groundwater that emerges from surrounding high cliffs. Adjacent storm-swash deposits provide a potential source of calcium carbonate. The stromatolites occur in two dist...

Characterization of calcium carbonates used in wet flue gas desulphurization processes

Abstract This paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements.

Application of eggshell waste for the immobilization of cadmium and lead in a contaminated soil

Liming materials have been used to immobilize heavy metals in contaminated soils. However, no studies have evaluated the use of eggshell waste as a source of calcium carbonate (CaCO₃) to immobilize both cadmium (Cd) and lead (Pb) in soils. This study was conducted to evaluate the effectiveness of eggshell waste on the immobilization of Cd and Pb and to determine the metal availability following various single extraction techniques. Incubation experiments were conducted by mixing 0-5% powdered eggshell waste and curing the soil (1,246 mg Pb kg⁻¹ soil and 17 mg Cd kg⁻¹ soil) for 30 days. Five extractants, 0.01 M calcium chloride (CaCl₂), 1 M CaCl₂, 0.1 M hydrochloric acid (HCl), 0.43 M acetic acid (CH₃COOH), and 0.05 M ethylendiaminetetraacetic acid (EDTA), were used to determine the extractability of Cd and Pb following treatments with CaCO₃ and eggshell waste. Generally, the extractability of Cd and Pb in the soils decreased in response to treatments with CaCO₃ and eggshell waste, regardless of extractant. Using CaCl₂ extraction, the lowest Cd concentration was achieved upon both CaCO₃ and eggshell waste treatments, while the lowest Pb concentration was observed using HCl extraction. The highest amount of immobilized Cd and Pb was extracted by CH₃COOH or EDTA in soils treated with CaCO₃ and eggshell waste, indicating that remobilization of Cd and Pb may occur under acidic conditions. Based on the findings obtained, eggshell waste can be used as an alternative to CaCO₃ for the immobilization of heavy metals in soils.

Coccolithophore bloom detection in the north east Atlantic using SeaWiFS: Algorithm description, application and sensitivity analysis

Coccolithophores are the largest source of calcium carbonate in the oceans and are considered to play an important role in oceanic carbon cycles. Current methods to detect the presence of coccolithophore blooms from Earth observation data often produce high numbers of false positives in shelf seas and coastal zones due to the spectral similarity between coccolithophores and other suspended particulates. Current methods are therefore unable to characterise the bloom events in shelf seas and coastal zones, despite the importance of these phytoplankton in the global carbon cycle. A novel approach to detect the presence of coccolithophore blooms from Earth observation data is presented. The method builds upon previous optical work and uses a statistical framework to combine spectral, spatial and temporal information to produce maps of coccolithophore bloom extent. Validation and verification results for an area of the north east Atlantic are presented using an in situ database ( N = 432) and all available SeaWiFS data for 2003 and 2004. Verification results show that the approach produces a temporal seasonal signal consistent with biological studies of these phytoplankton. Validation using the in situ coccolithophore cell count database shows a high correct recognition rate of 80% and a low false-positive rate of 0.14 (in comparison to 63% and 0.34 respectively for the established, purely spectral approach). To guide its broader use, a full sensitivity analysis for the algorithm parameters is presented.

Composição dos estromatólitos estratiformes da lagoa Salgada, Rio de Janeiro, Brasil

Lagoa Salgada is situated in the north coast of State of Rio de Janeiro, between the districts of Campos dos Goitacazes and São João da Barra, some 41º00'30" W and 21º54'10"S. In the margins of the lagoon the presence of recent stromatolitic constructions was verified. The stromatolite may be defined as lithifying biosedimentary structure, growing through of sediment blade trapping by the carbonate precipitation as result of microbian organism activity. The aim of this study was to characterize the cyanobacteria assemblage in stratiform stromatolites found on the floor of lagoa Salgada. Within the stratiform stromatolites 21 species of cyanobacteria were found, Microcoleus chthonoplastes (Thuret) Gomont 1892 and Lyngbya aestuarii (Liebman) Gomont 1892 are frequent in these stromatolites. The presence of calcite was observed in the stratiform stromatolites. The filamentous cyanobacteria are responsible for the union and imprisonment of sediment to form the layers in the stromatolites. The skeleton remains of mollusks, foraminifers and ostracod found in the area, work as a source of calcium carbonate and of sediment to structure the stromatolites

Calcite cement in Permian deep-water sandstones, Delaware Basin, west Texas: Origin, distribution, and effect on reservoir properties

Calcite cement is the dominant control on reservoir quality in turbidite sandstones of the Upper Permian Bell Canyon Formation, Delaware Basin. These well-sorted, very fine-grained arkoses were deposited in a basin-floor setting by channel-levee systems terminating in broad lobes. Calcite cement distribution in the East Ford and Geraldine Ford fields was mapped using core, log, and thin-section data. Calcite is concentrated in tightly cemented zones that are mostly less than 1 ft (0.3 m) thick. Areas that have high percentages of calcite-cemented sandstone (20%) occur along the margins of the sandstone bodies, in overbank and lobe deposits, where sandstone pinches out into siltstone. Areas that have the lowest percentage of calcite-cemented sandstone (10%) occur where the sandstone is thickest, in the channel facies. Isotopic composition of the calcite (13C = 1.8 to 3.0 [relative to the Peedee belemnite, PDB], 18O = 4.6 to 6.3 [PDB]) is consistent with the source of calcium carbonate being from dissolution of detrital carbonate rock fragments and marine skeletal debris. Because internal sources of calcite were apparently insufficient to account for the cement volume, cement components are interpreted as having been transported into the sandstones from organic-rich basinal siltstones and limestones. Feldspars buffered acidic formation waters near where they entered the sandstone, resulting in calcite concentrated near the sandstone margins. The calcite formed near maximum burial depths of 4800 ft (1.5 km) and temperatures of 104F (40C) from marine pore waters with 18O of approximately 0 (relative to standard mean ocean water). Most of the calcite-cemented zones are interpreted as being concretions that extend no more than a few meters laterally. Production data and geophysical log correlations suggest that some cemented zones are laterally continuous at least 1000 ft (300 m) and cause vertical reservoir compartmentalization. Laterally extensive calcite layers may be associated with the base of turbidite deposits.

The effect of increased dietary calcium on fecal fat excretion in overweight and obese adolescents

This study was designed to measure the effect of calcium supplementation from a dairy vs. calcium carbonate source on fecal fat excretion in overweight and obese adolescent boys and girls. Twenty girls (BMI 34+/−5 kg/m2) and fourteen boys (BMI 28 +/−5 kg/m2), aged 12–15 y, participated in two 3 week controlled feeding trials separated by a 3‐week washout period. Total dietary intakes during both sessions were eucaloric and macronutrient matched for energy needs. Intake included a basal diet containing 759 mg Ca/d plus frozen products based on soy protein with no added Ca (control) or the basal diet plus frozen products based on either dairy or soy protein containing added Ca (714 mg/d) in a cross‐over design. All urine and feces were collected during each session. Twenty‐four h diet and fecal samples were analyzed for Ca by inductively coupled plasma spectrophotometry. Crude fat of dried diet and feces was extracted using an automated Soxhlet type system. Fractional fecal fat was not influenced by increased Ca intake from dairy or CaCO3. However, pooled data indicated that fractional fecal fat excretion was positively related to fecal Ca excretion.Supported by NIH DK066108, National Dairy Council and test products were a gift from The Schwan Food Company.

Decrease in Lithothamnion sp. (Rhodophyta) primary production due to the deposition of a thin sediment layer

Coralline algae are important reef-builders which can form nodules, known as rhodoliths, occurring worldwide in beds sustaining a high biodiversity. Although considered a non-renewable resource, they are exploited as a source of calcium carbonate used mainly for agricultural purposes. In Brazil between 96,000 and 120,000 metric tonnes of rhodoliths are extracted per year. Besides the direct impact caused by removal on the coralline bed, the dredge process may also produce a plume of fine sediment, which can change the primary production of the remaining organisms. In this study, four treatments, with three replicates, were used to acquire Lithothamnion sp. net photosynthetic rates with and without a sediment layer using a Clark-type oxygen microelectrode and micromanipulator. The results demonstrated that, under controlled conditions, the addition of a thin sediment layer resulted in a 30% reduction of the irradiance, decreasing the Lithothamnion sp. net production in 70%. For this reason direct and indirect effects of mechanical exploitation of the rhodolith beds should be included in future studies that focus on environmental impacts of dredging activity, whether it is linked to the extraction of these algae.

Impact of increasing calcium intake with dairy vs. calcium carbonate on calcium retention in overweight adolescents

This study assessed the effect of calcium supplementation from dairy vs. calcium carbonate sources on calcium (Ca) retention in overweight and obese adolescent boys and girls. Twenty-three girls (BMI 33 ± 5 kg/m2) and seventeen boys (BMI 28 ± 5 kg/m2), aged 12–15 years, participated in two 3-week controlled feeding trials, separated by a 3-week washout period. Each subject consumed a controlled basal diet during both trials that provided their individualized energy need and 778 ± 147 mg Ca/day. Using a two period crossover design, subjects received no additional Ca in a soy-based product (Control) during one 3-week testing period and were randomized to receive an additional 675 mg Ca/day as dairy Ca (Dairy) or Ca carbonate (CC) in the other testing period. Ca intake and source of Ca were manipulated through a frozen product consumed twice each day. All urine and feces were collected during each 3-week period. Diet, fecal, and urine samples were each pooled for 24-hour periods and measured for Ca content by Inductively Coupled Plasma Spectrophotometry. Subjects retained (intake-feces-urine) more (p<0.0001) Ca when they consumed the higher Ca product (552 ± 213 mg Ca/day for the CC group and 578 ± 221 mg Ca/day for the Dairy group) compared to the lower Ca period (296 ± 169 mg Ca/day for Control). Thus, doubling Ca intake through either dairy or Ca carbonate supplementation led to a nearly two-fold increase in Ca retention. The proportion of intake retained (~38%) during pubertal growth in obese adolescents was not dependent on Ca intake, as observed in adults. Supported by NIH DK066108, National Dairy Council and test products were a gift from The Schwan Food Company.

Cianobactérias e outros componentes das esteiras microbianas lisas da lagoa Pitanguinha, Região dos Lagos, Rio de Janeiro, Brasil

CYANOBACTERIA AND OTHER COMPONENTS IN THE SMOOTH MICROBIAL MATS FROM PITANGUINHA LAGOON, LAGOS REGION, RIO DE JANEIRO, BRAZIL. Pitanguinha Laggon is part of a set of small hipersaline lagoons known as Lagos region, placed in the northern Rio de Janeiro littoral, near Araruama city. They are genetically related to the last Quaternary glacial events and the sea level changes. The microbial mats formed around their margins are being affected by the advance of urbanisation and by salting exploration and are now threatened. The climatic conditions, with a semi-arid climate and warm temperatures stimulate the high evaporation rate. Many kinds of algalic mats growing up in their bottoms, associated with bioclastics and the lithified substrate of the lagoon. The composition of the smooth microbial mats and the associated organic rests are analyzed in this work. The study was carried out monthly on five sampling stations. The mats are stratified and filamentous forms dominante in the upper layer. Thirty seven species of cyanobacteria were identified, being Lyngbya aestuarii Liebman ex Gomont (1892) the more frequent. Specimens of Synechococcaceae Komarek and Anagnostidis, 1995 are the most abundant. Shells of bivalves, gastropods, foraminifers and ostracods occur together as associated bioclasts and have a critical role in the structure of the mats, being the source of calcium carbonate resulting from the chemically and physical action of the cyanobacteria over their skeletal remains. It attests that the cyanobacteria are the primary producers, located at the basis of the microbial food web in the microbial mats.