Mud Content Research Articles

Benthic microbial biogeographic trends in the North Sea are shaped by an interplay of environmental drivers and bottom trawling effort

Microbial composition and diversity in marine sediments are shaped by environmental, biological, and anthropogenic processes operating at different scales. However, our understanding of benthic microbial biogeography remains limited. Here, we used 16S rDNA amplicon sequencing to characterize benthic microbiota in the North Sea from the top centimeter of 339 sediment samples. We utilized spatially explicit statistical models, to disentangle the effects of the different predictors, including bottom trawling intensity, a prevalent industrial fishing practice which heavily impacts benthic ecosystems. Fitted models demonstrate how the geographic interplay of different environmental and anthropogenic drivers shapes the diversity, structure and potential metabolism of benthic microbial communities. Sediment properties were the primary determinants, with diversity increasing with sediment permeability but also with mud content, highlighting different underlying processes. Additionally, diversity and structure varied with total organic matter content, temperature, bottom shear stress and bottom trawling. Changes in diversity associated with bottom trawling intensity were accompanied by shifts in predicted energy metabolism. Specifically, with increasing trawling intensity, we observed a transition toward more aerobic heterotrophic and less denitrifying predicted metabolism. Our findings provide first insights into benthic microbial biogeographic patterns on a large spatial scale and illustrate how anthropogenic activity such as bottom trawling may influence the distribution and abundances of microbes and potential metabolism at macroecological scales.

Mechanical and thermal behaviour of stir cast sillimanite/red mud/LM25 Al‐alloy metal matrix composite

AbstractThis paper investigates the mechanical and thermal characterization of hybrid metal matrix composites of sillimanite/red mud/LM25 aluminium alloy produced by stir casting process. The weight percentage of red mud and sillimanite are taken 5 %, 10 % and 15 % in the ratio of 1 : 1. Energy dispersive spectroscopy confirmed that both reinforcements are present in the base alloy. The aluminium‐metal matrix composites exhibit symmetrical distribution of red mud and sillimanite particles when observed through microscopic images, with minimal agglomeration. A detailed analysis is performed on the composites to determine the effects of sillimanite and red mud content on its tensile strength, thermal conductivity and hardness. Experimental results show that the accumulation of reinforcing material enhances the ultimate tensile strength and hardness at the expense of percentage elongation and thermal conductivity.

Abundance, biomass and species richness of macrozoobenthos along an intertidal elevation gradient.

Ecology aims to comprehend species distribution and its interaction with environmental factors, from global to local scales. While global environmental changes affect marine biodiversity, understanding the drivers at smaller scales remains crucial. Tidal flats can be found on most of the world's coastlines and are particularly vulnerable to anthropogenic disturbances. They are important transient ecosystems between terrestrial and marine ecosystems, and their biodiversity provides important ecosystem services. Owing to this unique, terrestrial-marine transition, strong environmental gradients of elevation, sediment composition and food availability prevail. Here, we investigated which regional and local environmental factors drive the spatio-temporal dynamics of macrozoobenthos communities on back-barrier tidal flats in the East Frisian Wadden Sea. On the regional level, we found that species composition changed significantly from west to east on the East Frisian islands and that total abundance and species richness decreased from west to east. On the local abiotic level, we found that macrozoobenthos biomass decreased with higher elevation towards the salt marsh and that the total abundance of organisms in the sediment significantly increased with increasing mud content, while biodiversity and biomass were not changing significantly. In contrast to expectations, increasing Chl a availability as a measure of primary productivity did not result in changes in abundance, biomass or biodiversity, but extremely high total organic carbon (TOC) content was associated with a decrease in biomass and biodiversity. In conclusion, we found regional and local relationships that are similar to those observed in previous studies on macrozoobenthos in the Wadden Sea. Macrozoobenthos biomass, abundance and biodiversity are interrelated in a complex way with the physical, abiotic and biotic processes in and above the sediment.

Chemical‐treated sisal fiber reinforcement in red mud composites: Advancing mechanical strength and environmental sustainability

AbstractThe use of industrial waste red mud in polymer composites promotes environmental sustainability by mitigating the environmental impacts associated with landfill disposal. Previous research by the authors on red mud sisal fiber composites resulted in increased strength; it is expected that the strength can be increased further through fiber treatment. As a result, the current study sought to examine the effects of chemical‐treated sisal fiber reinforcement on the mechanical properties of red mud composites. Alkaline treatment and silane treatment were both used as chemical treatment methods. Red mud was added in three different weight percentages, and composites were built using the compression molding method and tested for hardness, tensile strength, flexural strength, and impact strength. The findings indicate that the strength of the composite increases with the incorporation of treated fibers, silane‐treated 30% red mud composites showed a maximum hardness of around 92 shore D. The tensile strength of the composites containing 20% red mud and treated with silane was the highest, reaching ca. 63 MPa. This significant increase in strength was attributed to the formation of strong interfacial bonding between the red mud, fiber, and matrix. Furthermore, the silane‐treated 20 wt% red mud composites have the highest flexural strength (ca. 244 MPa) and impact strength (ca. 26 J/m). However, increasing the red mud content above 20 wt% resulted in decreased tensile, flexural, and impact strength due to poor bond development, and red mud agglomeration. The findings of this study are beneficial for the design and development of composites based on red mud, as well as for promoting sustainable waste management practices.Highlights Red mud composites achieve superior mechanical strength. Chemical treatment enhances sisal fiber reinforcement. Sustainable waste management promoted through composite utilization. Strong interfacial bonding improves composite performance.

Study on the matching rules and control mechanisms between flocculants and slurry settlement characteristics

In order to realise efficient, economic, low carbon and environmentally friendly slurry disposal, floc sedimentation velocity (S f ), supernatant volume (V s ), water content of bottom mud (W b ), supernatant turbidity (N s ) and pH value were determined by slurry sedimentation tests, specific resistance tests, and water quality analysis. Orthogonal tests were performed to analyze the matching rule and control mechanism between flocculants and the slurry settlement characteristics. The results show that polyaluminum chloride (PAC) and polyferric chloride (PFC) had a low dose and a fast sedimentation rate. The sedimentation effect of 20 ionic degree cationic polyacrylamide (CPAM-20) in organic flocculant is the best. Although flocculants can shorten the sedimentation time, excessive flocculants can also weaken the slurry separation effect. The sedimentation efficiency of organic flocculants is higher than that of inorganic flocculants, but it is easy to form foam on the supernatant surface. For the composite flocculants, the sensitivity sequence of S f , V s and W b is PAC>CPAM-20>PFC. PAC plays a controlling role in the sedimentation effect of the slurry.

Fine-grained deep-water turbidite gas reservoirs in upper Bengal Fan

The Bengal Fan is a mud-rich, deep-water sediment system. A series of recently discovered biogenic gas reservoirs in the northeastern Bay of Bengal are fine-grained. The Pliocene gas discovered in the study area accumulated in the levee element of a deep-water channel complex identified by high-resolution three-dimensional (3D) seismic interpretation integrated with well logs and sidewall cores (SWC). The thickness and porosity of the levee gas reservoir are of good quality, but the permeability is relatively low owing to the high mud content. The discovery of the levee sandstone indicates various reservoirs in this mud-rich sediment system. Moreover, gas discovery implies that the gravity-flow sediment systems “link” the source rock in the study area. Gas reservoirs were discovered in Pliocene gravity-flow sediment systems, where the palaeo-climate experienced significant changes with a dramatic increase in total organic carbon (TOC) from the Miocene to the Pliocene. TOC-rich pelagic mudstones and deep-water gravity sediments act as source rocks for petroleum systems. Therefore, gravity-flow sediment systems have developed self-accumulating petroleum plays that exhibit enormous potential for exploration. Given the structural framework in the northeastern part of the Bay of Bengal, stratigraphic or structure-stratigraphic traps could have developed in the Pliocene deep-water sediment systems in the Bengal Fan.

Preparation of non-sintered building materials with a high content of red mud using magnesium oxychloride cement

With the increasing concern of environmental problems, the effective utilization of red mud is becoming more and more challenging. In this study, research on the combination of red mud and magnesium oxychloride cement was systematically carried out to prepare a non-sintered building material with a high content of red mud. Molar ratio of MgO/MgCl2, content of red mud and aggregate, modifiers exhibited significant impact on mechanical properties and water resistance of the building materials. The results demonstrated that the flexural strength, compressive strength, and softening coefficient of the test blocks reached 7.37 MPa, 35.7 MPa, and 0.91, respectively when the optimal condition was applied. Mechanism analysis showed that red mud particles interacted with the hydration products of MOC to form an amorphous gel, improving the degree of matrix compactness and effectively blocking the infiltration of external water, thus enhancing the mechanical strength and water resistance of the building materials. Finally, the cost analysis revealed that the construction materials developed in this study were significantly lower than the prices of those available on the market. These findings offer invaluable guidance for the utilization of red mud as building materials.

Development of an atomistic model of cement-incorporated nano-red mud material

The complexity of the hydration process of cementitious materials makes developing universal models that predict their mechanical behavior challenging. The current study used a novel molecular modeling method to develop a bottom-up model of the cement paste that incorporated different contents of the nano-red mud (nRM). A molecular dynamics (MD) simulation and dreiding force field were employed to build the ingredient-based models using the cement clinker phases and nRM oxides. Different cement-nRM mixtures were prepared and macroscopically tested under compression and flexure. In addition, a detailed microstructural analysis using XRD, SEM, EDS, and Raman was carried out on the prepared of nRM. The experimental results were used to validate the results of the developed molecular models. The simulation results demonstrated the capability of the atomistic models for predicting the strength and stiffness of the cement-nRM composites accurately. In addition, the developed hydrated cement model was found with the line of C–S–H-mineral structure (called tobermorite 11 Å). The molecular characterization, in terms of the radial distribution function and fractional free volume, also provided useful information on the local structures of the models. The molecular models of cement-nRM can be further used to predict the durability properties as well as gain deep insights into the mechanical performance of blended mixtures.

Distribution, contamination assessment, and sources of heavy metals in surface sediments from the south of the North Yellow Sea, China

This paper reports the contents of six heavy metals and particle sizes in the surface sediments of 120 sampling stations in the southern North Yellow Sea to reveal heavy metal distribution characteristics, contamination assessment, and sources. Cu and Cr enrichments were mainly found in coastal areas with high mud content (silt and clay). However, Zn, Cd, Pb, and Hg were enriched in Weihai Bay and Dongpu Bay, which have denser populations, estuaries, and shipyards. The geoaccumulation index and principal component analysis showed that Cu and Cr contamination was low, and the sources were mainly natural processes. In addition, Zn and Cd pollution in the nearshore area was moderate, and its provenance was natural processes and human activity. However, most areas exhibited Pb and Hg contamination due to waterborne traffic and industries, including shipbuilding and gold mining.

Palaeogeographical development of two merging delta systems (Eocene Shahejie Formation) in the Bohai Bay Basin, E China and implications for hydrocarbon exploration

Two deltas developed simultaneously during the Eocene on the eastern side of a large lake that existed in the Dongying Sub-basin, which forms part of the Bohai Bay Basin in eastern China. The rivers that built the deltas had different catchment areas, which resulted in sediments with different permeability and porosity, due to differences in sorting and mud content. Both deltas prograded, and mass flows that originated frequently on their fronts formed lobes that expanded laterally. This eventually led to merging of both deltas, a feature that has rarely been described from ancient deposits thus far. Core analysis and seismic reflection data show that the merging of the two deltas took place in nine phases, determined by phases of slower progradation or even temporary retrogradation in between. The alternation of sediments from both deltas and their eventual mixing makes the architecture of the merged deltas much more complex than that of ‘classical’ single deltas. This affects the predictability of the spatial distribution of possible reservoir characteristics significantly, but detailed core analysis shows that the best hydrocarbon reservoirs consist of sand bodies formed in distributary channels on the delta plains, and of sandy turbidites formed in the deep-lacustrine environment in front of the merged deltas.

Physically-Data Driven Approach for Predicting Formation Leakage Pressure: A Dual-Drive Method

Formation leak-off pressure, which sets the upper limit of the safe drilling fluid density window, is crucial for preventing wellbore accidents and ensuring safe and efficient drilling operations. The paper thoroughly examines models of drilling physics alongside artificial intelligence techniques. The study introduces a dual-driven method for predicting reservoir pore pressure by integrating long short-term memory (LSTM) and backpropagation (BP) neural networks, where the core component is the LSTM-BP neural network model. The input data for the LSTM-BP model include wellbore diameter, formation density, sonic time, natural gamma, mud content, and pore pressure. The study demonstrates the practical application of the method using two vertical wells in Block M, employing the M-1 well for training and the M-2 well for validation. Two distinct input layer configurations are devised for the LSTM-BP model to evaluate the influence of formation density on prediction accuracy. Notably, Scheme 2 omits formation density as a variable in contrast to Scheme 1. The study’s results indicate that, for input layer configurations corresponding to Scenario 1 and Scenario 2, the LSTM-BP model exhibits relative error ranges of (−2.467%, 2.510%) and (−6.141%, 5.201%) on the test set, respectively. In Scenario 1, the model achieves mean squared error (MSE), mean absolute error (MAE), and R-squared (R2) values of 0.000229935, 0.011198329, and 0.92178272, respectively, on the test set. Conversely, for Scenario 2, the model demonstrates a substantial escalation of 992.393% and 240.674% in MSE and MAE, respectively, compared to Scenario 1; however, R2 diminishes by 66.920%. Utilizing the trained LSTM-BP model, predictions for formation lost pressure in Well M-2 reveal linear correlation coefficients of 0.8173 and 0.6451 corresponding to Scenario 1 and Scenario 2, respectively. These findings imply that the predictions from the Scenario 1 model demonstrate stronger alignment with results derived from formulaic calculations. These observations remain consistent for both the BP neural network algorithm and the random forest algorithm. The aforementioned research results not only highlight the elevated predictive precision of the LSTM-BP model for intelligent prediction of formation lost pressure, a product of this study, thereby furnishing valuable data points to enhance the security of drilling operations in Block M, but also underscore the necessity of deliberating both physical relevance and data correlation during the selection of input layer variables.

FACTORS CONTROLLING THE EQUILIBRIUM SEDIMENT COMPOSITION IN SAND-MUD TIDAL BASINS

Bed sediments in estuaries and tidal basins often consist of sand and mud, which can be deposited as uniform mixtures or as layers with varying mud content. Segregation between muddy and sandy areas is usually observed over large spatial scales (with sandy outer areas gradually fining in the landward direction), but also over small spatial scales. These small spatial scales are characterized by abrupt transitions of the sediment composition over relatively short distances. Understanding where sand and mud prevails is crucial to understand and predict coastal evolution and biological activity.

3D inversion modelling of gravity data for identification of subsurface structures in the mud volcano area of Sedati, Sidoarjo

Many mud volcanoes are found in Central Java and East Java in the north, but research on mud volcanoes is still limited. This research focuses on the Sedati mud volcano area, Sidoarjo with a research area of 500x400 meters. Measurement of gravity method data with 88 points spaced 50 meters to determine the value of rock density and subsurface structure of Sedati mud volcano area. From the data that has been obtained, data processing is carried out to obtain a map of the distribution of regional and residual gravity anomaly values. From the anomaly data, 3D inversion was carried out to obtain a map of the subsurface structure. The 3D gravity inversion modelling results show that there is high density rock block which is interpreted as a basin that holds the reservoir from the mud volcano. Near the surface and around the mudflow in the study area, the distribution of low density is caused by the presence of mud content. There is a possibility that there is a fault zone with a west-east direction from the study area. The results of the 3D gravity model incision show that the weak zone in the study area is a zone of accumulation of mud which has a density value of 1.8 g/cm3 at a depth of 20 meters to 500 meters.

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

The application of large amounts of red mud in the field of building materials is one of the main ways to reuse this material, but the high alkali content of red mud limits its application. In this paper, the washable alkali, removable alkali, and lattice alkali contents of Bayer red mud were studied, and the occurrence states of potassium and sodium in red mud were studied using XRD, IR, XPS, and NMR. On this basis, the removal mechanism for potassium and sodium in red mud was analyzed. The results showed that the Na in the red mud was mainly deposited in the shelf silicon voids of hydroxy sodalite (Na8(AlSiO4)6(OH)2(H2O)2) in the form of Si-O-Na or Al-O-Na. K is deposited in the shelf silico-oxygen void of potassium feldspar (KAlSi3O8) in the form of Si-O-K or Al-O-K. The washable Na and K contents of the mud were 13.7% and 4.47%; the alkali removal agent CaO removed 83.1% and 50.8% of Na and K in the red mud; and the lattice alkali Na and K contents were 3.20% and 44.8%, respectively. In the process of red mud dealkalization, Ca2+ ions can enter the internal voids of the hydroxyl sodalite and potassium feldspar silica skeleton and then replace Al3+ in the Si-O skeleton and Na+ and K+ in the skeleton voids. The replacement reaction changes the silica tetrahedron network structure, resulting in the disintegration of the frame-like silica tetrahedron in the hydroxyl sodalite and potassium feldspar, forming an isolated, island-like silica tetrahedron in hydrated garnet.

Organochlorine contaminants in sediments and factors influencing their distribution in the natural marine protected area in the gulf of Mexico

The aim of this study was to determine the concentration of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in marine sediments of a natural marine protected area (NMPA), Veracruz Reef System (VRS), in the Gulf of Mexico (GoM). This NMPA represents one of the first coastal sites with port activity in Mexico, which causes a range of human activities that require adequate planning so as not to impact and destroy this marine protected area; In this sense, this work represents the first effort aimed at diagnosing the presence of organochlorine contaminants in reef sediments from the mainland, both from the adjacent port area and from more distant regions with dominant agricultural activities that ultimately affect this NMPA. Content of organic matter (OM), carbonates and grain-size composition were determined to investigate their influence on compounds distribution in the sediment through multivariate analysis. The potential risk represented by organochlorines concentrations was evaluated taking as reference Sediment Quality Guidelines (SQGs). Levels of ∑PCBs, ∑DDTs, ∑HCHs and ∑Cyclodienes ranged from 11.59 to 29.79, < 0.01 to 34.11, 22.10 to 102.80, and 17.21–104.45 ng g−1 dry weight (DW), respectively. The statistical analysis revealed that the content of mud and organic matter were the parameters that might influence PCBs distribution in the sediment while OCPs could be influenced by sand and carbonate. The theoretical risk assessment estimated with the results obtained showed that concentrations of lindane, endrin, dieldrin and p,p’-DDT could have an adverse effect on the reef benthic community and continued monitoring is required. The data obtained on the organochlorine contaminants (OCs) considered in this work will contribute to support the strategies proposed by the Mexican federal government entity to continue with the conservation and surveillance of this NMPA and thereby guarantee the least impact derived mainly from port and related agricultural activities.

Analysis Of Compressive Strength Of Foam Mortar With The Use Of Teratak Buluh Sand And Ringgit Sand

The core material in the manufacture of lightweight concrete (foam mortar) is influenced by the composition of the mixture of fine aggregate. The purpose of the study was to compare foam mortar with foaming agent using two types of fine aggregates from different sources, namely Teratak Buluh Sand, Kampar and Ringgit Sand, Indragiri Hulu. This study focuses on testing the properties of fine aggregate, flow value, bulk density and Unconfined Compression Strength (UCS) of foam mortar. The fine aggregate of Teratak Buluh has a mud content value of 0.50% while the ringgit sand silt content value is higher with a 1.92% mud content percentage value where the maximum silt content value is 3%. In this study, both types of aggregates had variations in the mixture of sand to cement, namely 18/82%; 16/84%; 15/85%; 14/86% and 12/88%. The flow value in a mixture of 14/86% Teratak Buluh Sand and a mixture of 12/88% ringgit sand has a flow value of 19.00 cm which is the highest value of the five variations. Teratak Buluh sand mixture of 14/86% has a higher value than the five variations, which is 781.67 Kg/m3 while ringgit sand has the highest density value of 758.12 Kg/m3 in a mixture of 12/88%. The value of Unconfined Compression Strength (UCS) using Teratak Buluh sand is superior when compared to the use of ringgit sand. The average value of the Unconfined Compression Strength (UCS) of lightweight foam mortar material from the use of mixed teratak buluh sand of 14/86% (1136.80 kPa) and 12/88% (1175.78 kPa) has the highest value which is close to the reference Unconfined Compression Strength (UCS) of the mixture. 15/85% (1253.73 kPa) while the mixture was 18/82%; 16/84% Teratak Buluh and 18/82%; 16/84%; 15/85%; 14/86%; 12/88% ringgit sand has the lowest f Unconfined Compression Strength (UCS) which does not meet the design Unconfined Compression Strength (UCS) of 1000 kPa and 800 kPa based on the SE-PUPR-46-SE-M-2015 specifications.

Analysis of The Effect of Variations in Mud Content on Stability and Flow Values in Asphalt Concrete Mixtures Layer Aus (AC-WC)

&#x0D; &#x0D; &#x0D; &#x0D; Aggregat mud affect the weakening of asphalt adhesion and bonds between aggregate grains which will cause damage more quickly before reaching the design age, one of which is the formation of holes in the road surface layer.The purpose of this study was to measure the effect of variations in silt content on the stability and flow values ​​of Asphalt-coated concrete mix (AC-WC). All tests were carried out using the Marshall test method and each test object became the basis for calculations to analyze the stability and flow values ​​of the AC-WC asphalt concrete mixture with variations in silt content of 0%, 5%, 10%, 15% and 20%. The optimal bitumen content used is 6.7%. Furthermore, marshall testing was carried out on variations in silt content in the aggregate to obtain stability and flow values, stability values ​​tended to decrease from 1048.64 kg to 798.96 kg, this affected the minimum stability value of ≥ 800 kg and flow values ​​tended to increase from 1.54 mm to 3.05 mm, but the discharge value still meets the required limit of ≥ 3 mm with a mud content of 13%. Based on the results of the ANOVA analysis obtained from the test, the stability value shows a significant decrease in the level of stability and the flow value shows an insignificant effect on the proportion of sludge.&#x0D; &#x0D; &#x0D; &#x0D;

Plugging Experiments on Different Packing Schemes during Hydrate Exploitation by Depressurization

Marine natural gas hydrate (NGH) can mainly be found in argillaceous fine-silt reservoirs, and is characterized by weak consolidation and low permeability. Sand production is likely to occur during the NGH production process, and fine-silt particles can easily plug the sand-control media. In view of this, experiments were conducted to assess the influence of the formation sand on the sand retention media in gravel-packed layers under gas–water mixed flow, and the plugging process was analyzed. The results show that following conclusions. (1) The quartz-sand- and ceramic-particle-packed layers show the same plugging trend, and an identical plugging law. The process can be divided into three stages: the beginning, intensified, and balanced stages of plugging. (2) The liquid discharge is a key factor influencing the plugging of gravel-packed layers during NGH exploitation by depressurization. As the discharge increases, plugging occurs in all quartz-sand packing schemes, while the ceramic-particle packing scheme still yields a high gas-flow rate. Therefore, quartz sand is not recommended as the packing medium during NGH exploitation, and the grain-size range of ceramic particles should be further optimized. (3) Due to the high mud content of NGH reservoirs, a mud cake is likely to form on the surface of the packing media, which intensifies the bridge plugging of the packed layer. These experiment results provide an important reference for the formulation and selection of sand-control schemes.

Influence of red mud on the engineering and microstructural properties of sustainable ultra-high performance concrete

This paper introduces a new application of industrial solid waste red mud to use as a cementitious material in the development of ultra-high performance concrete (UHPC) performances. In addition, utilization of red mud can reduce the environmental impact of red mud landfill. For gaining this aims, UHPC specimens were prepared with different contents of red mud and analyzed the effects of different RM contents on the fluidity, setting time, mechanical properties, durability, drying shrinkage and microstructure of the red mud-based UHPC. The results indicated that fluidity was reduced to 310 mm at 20% red mud level, but it still belongs to enormous fluidity, which is convenient for construction. In addition, it is worth noting that using red mud instead of cement can significantly shorten the setting time, providing a new method for applying the UHPC rapid-repairing process. Red mud-based UHPC mortar prepared with appropriate red mud instead of cement exhibits higher mechanical properties, better durability and reduced drying shrinkage of UHPC during curing. After curing for 28d, the highest compressive strength of UHPC samples containing 20% red mud was 129.5 MPa, the compressive strength of the UHPC samples' sulfate resistance was 136.6 MPa, and the drying shrinkage value was around 414 µm. Moreover, observed information from scanning electron microscopy (SEM) noted that red mud can fill the micro-cracks between particles of cementitious materials, make the structure more compact and form new hydrates. Finally, the two characteristics of low cost and energy consumption further promote the sustainable application of red mud-based UHPC. Therefore, replacing OPC with 20% RM is meaningful to produce a sustainable UHPC mixture and field applications.

Assessment of Sediment Quality Through Multiple Geochemical Proxies in a Heavily Industrialized Harbor Area in South America, Santos Estuarine Channel, São Paulo, Brazil

ABSTRACT The aim of the present study was to evaluate bottom sediments quality in 32 stations at Santos Estuarine Channel, home to one of the main international ports in South America, and to the Cubatão industrial complex, the most important petrochemical and metallurgical area in Brazil. Sediment quality was approached through contamination (mCd), ecological (PEI, SQG-Q, PLI) and geoaccumulation (Igeo) indices. Phosphorus Enrichment Index (PEI) revealed phosphorus enrichment, with potential risk to biota regarding eutrophication effects. Index of geoaccumulation (Igeo) revealed accumulation of Pb, Cu, Zn, Ni, Cr, Cd and As, all reaching class 6 of contamination, pointing to extreme contamination. Contamination index revealed null to moderate contamination for most stations. Pollution Load Index (PLI) revealed no contamination, and Sediment Quality Guideline (SQG-Q) pointed to moderate impact, suggesting risk to benthic biota. The mud content of the samples did not correlate with arsenic, phosphorus and trace metals. Organic matter seemed to be the main carrier of these elements in the system. Results revealed accumulation of trace metals and As in bottom sediments of Santos estuarine channel, which can be used to develop guidelines for monitoring these pollutants in anthropogenic activities along the harbor area.