Bottom Samples Research Articles

ASSESSMENT OF ANTHROPIC SOURCES THROUGH PB ISOTOPES IN SÃO DOMINGOS BASIN, RIO DE JANEIRO, BRAZIL

Sediments from Sao Domingos Basin were analyzed for Pb isotope composition aiming to characterize the contamination by metals, in an area of tomato production with intense use of pesticide. Located in the city of Sao Jose de Uba, Rio de Janeiro State, Brazil, an important tomato producer, that basin is an environmental laboratory due to the crop activity. This work aims to trace the anthropic activity in the basin using Pb isotope composition and comparing the results with other similar works. Sampling was carried out using stream 23 bottom sediments samples. The 200 mesh (0.075 mm) fraction was leached (using HNO 3 ) and residues were dissolved by HF. Samples were analyzed by two different mass spectrometer methods: leaching in ICP-MS, and leaching and residue in TIMS. For TIMS analysis, Pb was separated by ion exchange columns. The results define Pb/Pb isotope signature groups interpreted as different sources of Pb. The samples analyses yielded different Pb compositions, probably resulting from active pollutants which were transported by the rivers and provided by mixed sources. The 206 Pb/ 207 Pb ratios, applied in environmental studies, are used to trace pollution sources in this work. The results of ICP-MS and TIMS show 206 Pb/ 207 Pb values from 1.093 to 1.333 from leaching and 1.143 to 1.490 from residues. Each method has results that can be separated in two groups. The values from the first group are associated with gasoline and geogenic (Ribeira Belt Neoproterozoic rocks) sources and have the highest Pb concentration. The values of the second group may be interpreted as sewage and unidentified source, probably related to the pesticide used in the tomato crops, and have the lowest Pb concentration. Hence, gasoline and natural source are the main metal contributions. Both methods show similar values and complete each other; however, TIMS shows better precision than ICP-MS.

Strength activity and microstructure of blended ultra-fine coal bottom ash-cement mortar

Replacing Portland cement with reutilized coal combustion products can have substantial benefits to the environment as well as infrastructure. In this study, a sub-bituminous coal bottom ash is re-utilized as a cement replacement. The bottom ash was pulverized using a high energy vibratory ball mill at two different milling times to achieve a particle fineness approximately two and three-times finer, respectively, than type I cement. The workability and final setting time were found to increase by 21% and 14%, respectively, and the highest strength activity was observed to be 120% at 90days. After normalization for particle fineness, age, and binder replacement using a general linear regression model, the data suggested the bottom ash blended cement mortar had 6.8% less strength activity than a comparative fly ash blended cement mortar. Blended bottom ash-cement paste samples were observed to have densely packed CSH product composed of relatively lower Ca/Si ratio (1.37) compared to that of fly ash blended cement paste (1.43) and the control (2.27). The CH content was also observed to be significantly lower in the bottom ash blended cement paste (19.1%) when compared against the control (27.2%) and fly ash blended paste (23.3%). Within the range of experimental conditions considered here, the results suggest that a coal bottom ash can be pulverized with a high energy ball mill to produce a re-utilizable pozzolan that, depending on the powder fineness, can significantly increase the strength activity, improve the microstructure of cement mortar, and increase the cement replacement tolerances without significant reduction to compressive strength activity.

Taxonomy, Distribution and Evolution of Trisopterine Gadidae by Means of Otoliths and Other Characteristics

In a greater study of the recent fossil Gadidae, the object of this paper is to better define the trisopterine species and their relationships. The taxonomy of the four recent species usually included in the genus Trisopterus is further elaborated by means of published and new data on their otoliths, by published data on general external features and meristics of the fishes, and their genetics. Fossil otoliths, from the beginning of the Oligocene up to the present, reveal much of their evolution and throw more light on their relationships. Several succeeding and partly overlapping lineages representing different genera are recognized during this time interval. The genus Neocolliolus Gaemers, 1976, for Trisopterus esmarkii (Nilsson, 1855), is more firmly based. A new genus, Allotrisopterus, is introduced for Trisopterus minutus (Linnaeus, 1758). The similarity with Trisopterus capelanus (Lacepède, 1800) is an example of convergent evolution. The tribe Trisopterini Endo (2002) should only contain Trisopterus, Allotrisopterus and Neocolliolus as recent genera. Correct identification of otoliths from fisheries research and from sea bottom samples extends the knowledge of the present day geographical distribution of T. capelanus and T. luscus (Linnaeus, 1758). T. capelanus is also living along the Atlantic coast of Portugal and at least up to and including the Ría de Arosa, Galicia, Spain. There it can easily be mistaken for A. minutus that is also living there. Otoliths of T. luscus have been identified from the Evvoïkós Channel between Euboia and the mainland of Greece, thus it must live also in the Aegean Sea. Otoliths prove to be a powerful tool in taxonomy, biogeography and evolution of teleosts.

Human health and environmental assessments of small-scale and artisanal mining activities in the Gold City of Ijeshaland, Southwestern Nigeria

BackgroundThis study assessed the health and environmental impacts of artisanal gold mining in Ijesha-land, Osun State, Southwestern Nigeria. Fifty-four environmental samples were collected between 2011 and 2012 and analyzed for major, trace and rare earth elements using standard procedures. Samples were collected from surface water (rivers and streams), groundwater, bottom sediments, fish (Tilapia) and aquatic plants (ferns). Data collected were analysed for simple descriptive and inferential statistics using Statistical Package for Social Sciences (SPSS) for Windows (16.0). Human health risk assessment of noncarcinogenic adverse effects of elements in water and fish samples was determined.ResultsHigher concentrations of most major and trace elements were found in groundwater than surface water, while rare earth elements (REEs) were more concentrated in groundwater than surface water. Bottom sediment samples showed highest concentrations of Ti, Cs and Eu for major, trace and rare earth elements, respectively. The major and trace elements were most concentrated in the fish guts. The sum of REEs was observed highest in the fish guts (31.83 ± 35.90 µg kg−1), followed by muscle (18.70 ± 19.37 µg kg−1), while the lowest ΣREEs was measured in the gills (15.78 ± 22.45 µg kg−1). The human health risk assessment revealed low hazard quotient and hazard index values less than 1.0 for trace and rare earth elements in environmental samples.ConclusionsThe data obtained in this study showed that, the artisanal gold mining activities in the study area may contribute to long term environmental and human health risk.

Distribution of macrozoobenthic taxa - potential indicators of vulnerable marine ecosystems in the western part of Bering Sea. 1. Anadyr Bay area

Following recent tendencies in fisheries policy to ensure both sustainability of ecosystems and conservation of economically sustainable fisheries, protection of vulnerable resources with low direct economic value comes to the focus of fisheries management on ecosystem principles. One of the problems of modern fishing is a negative impact of bottom trawling because of destruction of benthic organisms vulnerable to mechanical impacts. This by-effect of fishing could affect negatively on functioning of bottom biocenoses, reproduction of exploited species, and decrease generally productivity of vulnerable marine ecosystems (VME). Potential VME indicators are determined for the area of the Anadyr Bay in the Bering Sea on the base of results of 4 benthic surveys using bottom sampler (1985, 2005) and bottom trawl (2008, 2012), as the most common species in some macrozoobenthic groups of epifauna. They are Gersemia rubiformis for soft corals, Myxilla incrustans , Halichondria panicea , Semisuberites cribrosa for sponges, Halocynthia aurantium , Boltenia ovifera for sea squirts, Cystisella saccata , Flustra foliacea for bryozoans, Chirona evermanni for barnacles, and Gorgonocephalus eucnemis for brittle stars. Their distribution is mapped. According to their life history and feeding habits, these species-indicators are divided onto two groups: immobile sestonophages (alcyonarians, sponges, ascidians, bryozoans, cirripedians) and mobile filtrators (brittle stars). The first group prevails on hard and mixed grounds mainly along southwestern and northeastern coasts of the Anadyr Bay at the depths of 80-90 m (sponges and bryozoans - to 250 m in the Navarin Canyon) with relatively warm water, active hydrodynamics and high biological productivity. The second group represented by G. eucnemis dominates on soft sediments in the central part of the Anadyr Bay with the depths of 50-270 m occupied by the cold water pool. Quantitative distribution of brittle star, on the one hand, and barnacles with sea squirts, on the other hand, is alternative to each other. On the contrary, barnacles, sponges and sea squirts have similar distribution of the biomass, being complementary species. Distribution patterns of all species-indicators are stable for many decades. However, biomass of some these species has changed in the southern Anadyr Bay between the similar surveys conducted in the 2008 and 2012: the mean biomass of barnacle Ch. evermanni and sea squirt H. aurantium had decreased in 6.5 and 3.7 times, respectively, whereas the mean biomass of sponges, brittle star G. eucnemis and sea squirt B. ovifera did not change. Bottom trawl fishery is not active in the northwestern Bering Sea, moreover, the habitats of immobile sestonophages with hard grounds are avoided by bottom trawlers being dangerous for fishing gears, so the observed decreasing of two species abundance is presumably caused by natural reasons or is a random error of the mosaic-distributed stocks assessment with insufficiently dense sampling grid.

Polychaete worms (Annelida) collected in Golfo Dulce, during the Victor Hensen Costa Rica expedition (1993/1994).

A total of forty seven species of benthic polychaetes belonging to twenty five families have been identified from bottom samples taken in Golfo Dulce, Costa Rica, by the RV Victor Hensen. Only those stations collected in waters less than 100 m depth contained polychaetes. The major feeding type of these polychaete species was surface deposit feeding with slightly fewer species recognized as carnivores. Comparison of the species identified from the RV Victor Hensen material with those of the RV. T.V. Thompson material collected in 1969 reveals very few that are common to the two studies, indicating that the polychaetes of Golfo Dulce are probably quite diverse and poorly known. An estimated total of eighty five species of polychaetes have been identified from Golfo Dulce in the two studies.

Changing status of three notothenioid fish at the South Shetland Islands (1983–2016) after impacts of the 1970–80s commercial fishery

Owing to commercial fishing during the late 1970s/early 1980s, targeted notothenioid species had become depleted around the South Shetland Islands. Herein we report subsequent changes in the prevalence of three species, Notothenia rossii, Gobionotothen gibberifrons and Notothenia coriiceps in Potter Cove, King George Islands/Isla 25 de Mayo, in a 33-year effort to monitor recovery. N. rossii and G. gibberifrons had been severely impacted by industrial fishing but in offshore waters N. coriiceps had never been commercially fished; however, all three species exhibit similar nearshore habitats and life history. We examined composition in trammel net catches during 2012–2016, augmenting a time series started in 1983. Our inshore results were consistent with those from offshore bottom trawl sampling in 2007 and 2012 around the South Shetland Islands: (1) continued increase in the abundance of N. rossii; (2) further decline in G. gibberifrons recruitment evidenced by low proportions of juvenile fish; and (3) a high abundance of N. coriiceps. Reasons for lack of recovery in G. gibberifrons remain obscure but seemingly relate to the dramatically changing ecosystem of the region due in part to climate as well as recovery among previously depleted upper trophic level species. Our results are also consistent with trends reported in seabirds that feed on juveniles of these notothenioids: decrease in the areas commercially fished. Under the regulation of CCAMLR, commercial fishing for finfish in the South Shetland Islands region (FAO Subarea 48.1) remains prohibited since 1991; results indicate that it cannot be reinstated.

Bottom morphology in the Song Hau distributary channel, Mekong River Delta, Vietnam

Field studies in the Song Hau distributary of the Mekong Delta in Vietnam conducted at high (Sept.-Oct 2014) and low (March 2015) Mekong River discharge are utilized to examine channel bottom morphology and links with sediment transport in the system. Multibeam bathymetric mapping surveys over the entire channel complex in the lower 80km of the distributary channel, and over 12- to 24-h tidal periods at six transect locations in the reach are used to characterize bottom type and change on seasonal and tidal timescales, supplemented by bottom sampling. The results of this study indicate that the largest proportion of channel floor (up to 80% of the total area) is composed of substratum outcrops of relict sediment units deposited during the progradation of the delta in the last 3.5ka. These take the form of outcrops that are either (1) steep-sided, tabular channel floor, (2) steep-sided sidewall, or (3) relatively flat channel floor. Flatter outcrops of channel floor substratum are identified by the presence of sedimentary furrows (<0.5m deep) incised into the channel bottom that are exposed at high discharge and oriented along channel and laterally continuous for kilometers. These furrows are persistent in location and extent across tidal cycles and appear to be incised into relict units, sometimes with a thin surficial layer of modern sediment observable in bottom grabs. The extent of substratum exposure, greater than that observed previously in low tidal energy systems like the Mississippi River, may relate both to a relatively low sand supply from the catchment, and/or to an efficient transfer of both sand and mud through this tidally energetic channel. Sand bottom areas forming dunes, comprise about 19% of the channel floor over the study area and are generally less than a few meters thick except on bar extensions of mid-channel islands. Both sandy and substratum areas are mantled by soft muds 0.25–1m thick during low discharge in the estuarine section of the study area. This mud mantling appears to be a key control on bottom sourcing of sand to suspension. An understanding of channel bottom morphology, particularly mobility and erodibility of sediments, is valuable for setting up morphodynamic models of channel evolution that can be used to test system response to anthropogenic alterations in the catchment and rising sea levels.

Determination of total phosphorus content in bottom sediment samples using inductively coupled plasma optical emission spectrometry

This paper describes the methodology of inductively coupled plasma optical emission spectrometry for determining the total phosphorus content in bottom sediment samples. Homogenized samples subjected to a microwave-assisted aqua regia digestion, and next analyzed for total phosphorus content using the inductively coupled plasma optical emission spectrometer. The method was optimized and its validation parameters were determined. Assessing the selectivity of the method, found the spectral interferences of other elements (especially copper) on P can be partially eliminated by using the optimal operating conditions. The method exhibited excellent linearity (r&gt;0.999) in the entire measurement range (25-5000 mg Pkg-1) and very good recovery (99%). It was also characterized by high repeatability (relative standard deviation of 1%) and reproducibility (reproducibility standard deviation of 10%). The relative expanded uncertainty of the method was estimated at 21.2%.

Subsea uplifts origin of the rugozerskaya bay and the great Salma channel (Kandalaksha bay)

Lots of shallow Rugozerskaya firth (Kandalaksha Bay of the White Sea) were studied on the basis of integrated explorationsincluding continuous seismic profiling, side scan sonar (SSS), bottom sampling and diver inspection. As a result a number of regularities in the geological structure of the region was identified, in particular - the origi of certain bottom forms and coast terrain was revealled.

Effect of storage stability on chemical and rheological properties of polymer-modified asphalt binders for road pavement construction

Polymer modified asphalt binders (PMB) are being commonly used instead of neat binders when superior performance is needed during the road service life. The addition of polymer improves the binder’s properties at high, low and mid-range temperatures. However, the effectiveness of polymer modification in improving road performance depends on a chemical-structural modification in the binder’s composition to be effective and durable. The phase inversion phenomenon between asphalt components and the added polymer leads the binder to assimilate the polymer characteristics. PMBs can have stability problems and separation; in fact, polymers and bitumen components can lose most of the benefits from the modification due to separation during the storage phase. Common testing for storage stability assessment includes the cigar tuben test (EN 13399, 2010) which provides an indication of whether separation has occurred. To evaluate the effects of separation on performance-related properties of the binder, the present study analyzed the storage stability and separation phenomena of five PMBs by performing an advanced-rheological storage stability test, based on frequency sweep tests on samples taken from the top and bottom part of 3, 5 and 7-day stored cigar tuben specimens. Master curves were developed for newly mixed and several storage conditions and were compared to identify possible separation phenomena between top and bottom samples. Indices were also developed to quantify separation of samples. Results showed that storage stability problems commonly start at the third day of storage. Binders which were seriously affected by separation, seemed to incrementally lose their homogeneity (top and bottom part) between 3 and 7days. Other binders preserved their rheological characteristics during storage, maintaining equal values between the top and bottom samples. All stored binders were affected by an aging factor.

ОСОБЕННОСТИ НАКОПЛЕНИЯ И РАСПРЕДЕЛЕНИЯ СВИНЦА В СИСТЕМЕ ВОДА - ДОННЫЕ ОТЛОЖЕНИЯ В УСТЬЕВОЙ ОБЛАСТИ РЕКИ БАЧ ДАНГ (ВЬЕТНАМ)

Research was held in the estuary of the river Bach Dang (Dongbay community, Rakhtay district, Hai Phong, Vietnam) in June, 2012 - May, 2013. Concentration of lead was studied in water, suspended solids and bottom sediment. Clam beach (natural breeding environment of Meretrix lyrata ) was inspected regularly, every month. Water samples were taken 6 times from the bottom layer 10 cm down the bottom, once per 3 hours in each of 12 investigated zones. Bottom sediment samples were taken at the depth 2 cm. The findings show that lead accumulates mainly in suspended solids (23.3 mg/kg) and in bottom sediment (14.31 mg/kg), in water it is in small quantities (0.003 mg/kg). Analysis of bottom sediment samples taken in different places showed that they have even leadcontent, lead is distributed uniformly, localization of contaminations is not found. The results obtained can be assumed as the basis for investigating lead accumulation and its excretion by clam Meretrix lyrata organisms in the natural habitat.

Surfactants in Klodnica River (Katowice, Poland). Part I. Linear Alkylbenzene Sulphonates (LAS)

Abstract Surfactants are a group of compounds with specific physico-chemical properties and therefore they are used in many spheres of human activity. Surface-active substances undergo various physico-chemical transformations, what enables their migration between different elements of the environment and may lead to its pollution. Selected anionic surfactants were determined in samples of water from the Klodnica river (25 samples) and bottom sediments (25 samples). In most samples the presence of anionic analytes was confirmed. The determined concentration levels were in the range of up to 0.2105±0.0023 mg/dm3 or 0.207±0.010 μg/kg (surface water and bottom sediment samples, respectively). Comparing the concentrations of certain analytes found in liquid and solid environmental samples, it can be noticed that the surfactants containing a shorter alkyl chain in a molecule were present in higher concentrations in liquid samples (hydrophobicity increasing with the increasing length of the chain) and the other way round.

Trihalomethanes formation in marine environment in front of Nuweibaa desalination plant as a result of effluents loaded by chlorine residual

Trihalomethanes have been identified as the most important disinfection byproducts resulted from using chlorine in desalination plants. Nuweibaa desalination plant was chosen to study their effluents impacts on the marine environment in front of the plant in the coastal area of Gulf of Aqaba. Surface and bottom Water Samples were collected from nine locations in the outfall area of this desalination plant during spring and autumn 2014, and analyzed for water temperature, pH value, Salinity, Dissolved Oxygen, Biological oxygen demand, Oxidizible organic matter, Total, fixed and volatile suspended matter, residual chlorine (free and combined) and trihalomethanes. High total chlorine dosage discharged from the desalination plant achieved high levels of trihalomethanes in the receiving seawater of the outfall area. It has been estimated that about 14524.65671kg of BOD, 74123.4kg of OOM, 166896.4375kg of total suspended solids, 623.634kg of free chlorine, 469.21kg of combined chlorine, 206.64kg of chloroform and 76.48kg of bromoform are discharged annually from this plant into the Gulf of Aqaba affecting the marine ecosystems. The results of THMs showed that the two main forms of THMs formed in the receiving seawater were chloroform and bromoform and ranged between (5.09–156.59), (2.82–566.06)μg/L respectively. High pH and High combined chlorine concentrations favored the formation of high concentrations of chloroform.

Total and methyl mercury in the water, sediment, and fishes of Vembanad, a tropical backwater system in India.

Mercury contamination in the water bodies of developing countries is a serious concern due to its toxicity, persistence, and bioaccumulation. Vembanad, a tropical backwater lake situated at the southwest coast of India, is the largest Ramsar site in southern India. The lake supports thousands of people directly and indirectly through its resources and ecosystem services. It is highly polluted with toxic pollutants such as heavy metals, as it receives effluent discharges from Kerala's major industrial zone. In the present study, water, pore water, sediment, and fish samples collected from Vembanad Lake were analysed for total mercury (THg) and methyl mercury (MHg) contents. The maximum concentrations of THg and MHg in surface water samples were31.8 and 0.21ng/L, respectively, and those in bottom water samples were 206 and 1.22ng/L, respectively. Maximum concentration of THg in surface sediment was observed during monsoon season (2850ng/g) followed by that in the pre-monsoon season (2730ng/g) and the post-monsoon season (2140ng/g). The highest sediment concentration of MHg (202.02ng/g) was obtained during monsoon season. The spatial variation in the mercury contamination clearly indicates that the industrial discharge into the Periyar River is a major reason for pollution in the lake. The mercury pollution was found to be much higher in Vembanad Lake than in other wetlands in India. The bioaccumulation was high in carnivorous fishes, followed by benthic carnivores. The THg limit in fish for human consumption (0.5mg/kg dry wt.) was exceeded for all fish species, except for Glossogobius guiris and Synaptura orientalis. The concentration of THg was five times higher in Megalops cyprinoides and four times higher in Gazza minuta. Significant variation was observed among species with different habits and habitats. Overall, risk assessment factors showed that the mercury levels in the edible fishes of Vembanad Lake can pose serious health impacts to the human population.

Time and frequency behaviour in TSR and PPT evaluation for flash thermography

Subsurface defects can be detected by flash thermography evaluating the temperature response at the surface. Many techniques have been developed in the past to localise defects and also to estimate their depth and size. Two of the most established methods are TSR and PPT, whereby TSR analyses the data in the time domain, and PPT evaluates the signal in the frequency domain. In order to get the data in the frequency domain, Fourier transformation, especially FFT is used to calculate the phase shift for the different frequencies. The usage of FFT assumes a periodic signal or a temporal signal limited in time. As this is not the case for the temperature signal after a short pulse heating, the transformation to the frequency domain generates some errors. Therefore parameters as e.g. sampling frequency or time duration of evaluation have to be selected carefully. Even if many publications have been already dealing with this topic, in this paper a new approach is attempted by comparing the temporal behaviour as it is handled by the TSR technique with the frequency behaviour calculated by PPT. The results are interpreted with the help of simulation and measurements for flat bottom hole samples are also presented.

A bottom water sampler for determining chemical gradients across the water-sediment interface

We developed an inexpensive bottom water sampler that can be operated from a small boat in order to obtain high resolution vertical profiles of dissolved oxygen (DO), chlorophyll, suspended particulate matter (SPM). These vertical profiles allow us to examine bottom resuspension processes and to estimate their benthic fluxes of nutrients across the sediment–water interface in shallow coastal waters. The sampler consists of a 2m long thick-walled transparent tube with 26 sampling ports at 8–10cm intervals. Each sampling interval contains a minimum of 300–370ml water samples. Test sampling was conducted twice during different tidal phases, and differences in bottom DO, ammonium and SPM were found to be significant between the two tests. Our results suggest that this bottom sampler is essential in order to study sediment-pelagic coupling processes by obtaining high resolution of various parameters in the 2m water column above the sediment.

Bacterial community structure and functional potential in the northeastern Chukchi Sea

We performed a molecular microbial ecological analysis in the northeastern Chukchi Sea in order to characterize bacterial community structure and genetic potential for biogeochemical cycling and oil biodegradation in a region targeted for oil and gas exploration (Burger lease area). Samples were collected from the surface, middle (20m), and bottom (2–3m above seafloor) of the water column during the open-water season of August and September 2012 at 17 different locations. We determined bacterial community structure with 16S rRNA genes sequencing and detected functional genes, including an array of oil biodegradation and biogeochemical cycling (carbon, nitrogen and phosphorus cycling) genes, using the GeoChip 5.0 microarray, and then correlated molecular data to contextual physical and biogeochemical factors. Bacterial community structure differed significantly by depth (surface water vs. bottom water) and between sampling dates (August vs. September). While the relative abundance of major functional gene categories did not differ with depth, the abundance of individual functional genes for carbon cycling, nitrogen cycling, organic contaminant remediation, phosphorus cycling, sulfur cycling, virulence, and viruses differed between surface and bottom seawater samples. Aerobic oil degradation genes and taxa known to include oil-degrading bacteria were found at all three depths. These findings support previous observations that two different water masses contribute to a stratified water column in the summer open-water season of the Burger lease area, but indicate that potential function is fairly similar with depth despite differences in temperature, water chemistry, bacterial community structure, and individual functional gene alleles.

Influence of environmental and anthropogenic factors at the bottom sediments in a Doce River tributary in Brazil

In developing countries, it is uncommon to find watersheds that have been the object of detailed environmental studies. It makes the assessment of the magnitude of environmental impacts and pollution of these sites difficult. This research demonstrated ways to understand the dynamics of river bottom sediments contamination, even for watersheds with a lack of environmental data. Based on geochemical affinity, we conducted a comprehensive study on the concentration of metals and metalloids. Then, we discussed the probable origin of the concentration of these elements at the bottom sediment along the Matipó River. The Matipó River is an important tributary of the Doce River, which stood out in international headlines because of the mining tailing dam disaster in Mariana, Minas Gerais, in 2015. The bottom sediment samples were taken in 25 stations located along the basin in different seasonal periods. The results showed that copper ([Formula: see text] = 464.7mg kg-1) and zinc ([Formula: see text] = 287.7mg kg-1) probably have natural origin, despite of the high concentrations. Lead ([Formula: see text] = 28.0mg kg-1), chromium ([Formula: see text] = 153.2mg kg-1), and nickel ([Formula: see text] = 41.8mg kg-1) also had high concentrations at some collecting stations, and this probably reflected the local natural conditions. The bedrock of the studying basin is dominantly composed of metabasalts and metatonalites interlayered with calcitic and dolomitic metalimestone. On the other hand, the concentration was worrisome in stations near human activities, possibly due to impacts caused by unsustainably agriculture and livestock.

Influence of the Main Process Parameters on the Physical and Mechanical Properties of the Bottom Ash Ceramics

Bottom ash has been presented as a major problem of disposal throughout the world, since it is produced from the process of coal combustion in thermal power plants. However, its physical and chemical properties make the bottom ash an adequate potential construction material in variety of applications.The aim of the study was to investigate the possibility of utilization of bottom ash for production of ceramics compacts and to analyse the influence of the main process parameters and their interaction on the physical and mechanical properties of the final product. Consolidation of the powders was conducted on two bottom ash samples with particle size (S) -0.250+0.125 mm and -0.500+0.250 mm, pressing pressure (P) of 100 and 150 MPa and sintering temperature (T) of 1100 and 1150 oC. The density (r) and bending strength (s) of the dense bottom ash compacts were the response function. The optimization was performed through implementation of main effect plots, Pareto charts and 3D surface method using “Statgraphics Centurion” software package. The obtained model equations of the density and bending strength dependence from the main process parameters are solid basic data for modeling the process of ceramic production.