Bed Samples Research Articles

Agronomic potential of biosolids for a sustainable sanitation management in Brazil: Nutrient recycling, pathogens and micropollutants

The agricultural recycling of biosolids is a sustainable option and part of a circular economy. Some countries still face difficulties in expanding cleaner production. Studies pointing out the agronomic potential of biosolids and the level of pollutants might encourage the development of more efficient public policies within the scope of the water-energy-food nexus concept. The purpose of this paper was to evaluate the agronomic potential of biosolids in nutrient recycling, and its chemical, pathogen, and micropollutant characteristics, regarding meeting the Brazilian and international legal requirements. Drying bed samples were analyzed for nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, as well as the demand for these macronutrients in eucalyptus, soy, orange, and tomato crops. The pathogens present and their limits established by the Conama Resolution 498/20 (Brazil), Norm 503 (United States), and Directive 86/278 (European Union) were analyzed. The same reference basis was adopted to evaluate inorganic contaminants (metals), with the addition of the Normative Instruction 7 (Brazil). For emerging organic pollutants (EOPs) the Conama Resolution 375/06 (Brazil) and EU Directive 2007 were used. Results evidenced that biosolids had the agronomic potential to meet the nutritional needs of the analyzed crops, especially for phosphorus, and they conformed to legal determinants for agricultural recycling. Based on the levels of Escherichia coli, biosolids were categorized as Class B. Inorganic contaminants were all within limits established by the Conama 498 Resolution and the Norm 503, although regarding Directive 86 there was an excess of zinc. Finally, results of EOPs were below minimum detectable limits, according to limits established by the Conama 375 Resolution, which is an old resolution, although it presents values for EOPs and EU Directive 2007. Consequently, the agricultural recycling potential of biosolids was evident, mainly because of the phosphorus recovery. It requires less landfill and transport and reincorporates nutrients into the production chain, which reduces the exploitation of natural reserves.

Experimental analysis of scour under circular pier

AbstractFor economical design, scour around the bridge piers is required to be controlled. In the present study, an attempt has been made to minimize scour depth by placing a triangular prism on the downstream side of a circular pier (35 mm dia) with one of its noses facing the direction of flow and other facing opposite to the direction of flow. Three different bed samples collected from Ghaggar, Patialki-Rao and the Kotla super-passage have been placed in a rectangular flume. Discharge values were varied from 0.0015 to 0.0186 m3/sec. Results are compared for observed scour-depth for upstream (U/S) and downstream (D/S) piers with and without protection. Arrangement with a triangular prism of 2.5 times the diameter of the circular pier in the upstream direction of the flow is very effective in reducing scour depth. Further, it is possible to reduce the scour depth with an average efficiency of 65% for Ghaggar, 56% for Patialaki-Rao and 64% for the Kotla super-passage with respect to the circular pier. The comparison of observed values of scour-depth with computed values of Lacey's scour-depth was underestimated with a maximum of ±70%. Hence, a new site-specific relationship between scour depth, discharge intensity and silt factor has been proposed. Validation of the new proposed relationship with observed data is in a good agreement ±20%.

Construction of an innovative adsorbent bed configuration in the adsorption chiller part 2. experimental research of coated bed samples

Enhancement of heat transfer conditions in the adsorption bed volume is one of the crucial tasks of improving adsorption chiller energy efficiency. The promising method is a modification of the heat exchanger boundary layer with thermally conductive glue. It ensures removing gaseous spaces, which strongly limit heat transfer from water to sorbent bed and in the opposite direction. Previously defined guidelines to build novel coated construction of adsorption beds published in Part 1 of this paper were applied to prepare coated bed samples and conduct experimental research. The thermal properties of the sorbent samples were examined with the laser flash method. Silica gel was used as a sorbent and two different kinds of epoxy resins were applied. Moreover, the scanning electron microscope (SEM) was employed to study the specific surface of the coated samples. The carried out analyses allowed to validate the selection criterion of coated bed components and indicate the sample with the best thermal properties. The maximum thermal conductivity of the coated layer was 0.533 W/(m·K) and it was obtained for a sample of silica gel with granulation of 710–800 μm with ER2 epoxy.

Bacterial Load of the Teat Apex Skin and Associated Factors at Herd Level

Simple SummaryBacterial load on the teat apex of dairy cows that causes intramammary infections is to a large extent due to environmental impacts. The aim of our study was to describe factors at herd level that are associated with bacterial load of environmental mastitis pathogens on the teat end’s skin. On visits to 31 dairy farms over a one-year period, farm conditions were documented, and environmental bacterial loads were examined. We found seasonal fluctuations and direct correlations between the temperature–humidity index (THI) in the barn and the bacterial load at the teat end. Significantly more environmental mastitis pathogens were found in herds with a high percentage of normal and slightly rough teat ends. The time since the last fresh bedding was added to the cubicles, as well as the frequency in which cubicles were cleaned, also affect the pathogen load on the teat skin. Pre-cleaning teats before milking as well as post-dipping after milking showed a decreasing effect of teat-skin bacterial load at the herd level.In order to reduce antimicrobial treatment and prevent environmental mastitis, the aim of the present study was to investigate associations between herd level factors and microbial load on teat ends with environmental mastitis pathogens. Quarterly farm visits of 31 dairy farms over a one-year period were used for statistical analysis. During each farm visit, teat-skin swabs, bedding and air samples were taken and management practices and herd parameters were documented. Total mesophilic bacteria, esculin-positive streptococci and coliform bacteria were examined in the laboratory procedures from teat skin and environmental samples. Esculin-positive streptococci and coliform bacteria on teat ends increased with high temperature–humidity indices (THI) in the barn during the spring and summer. Significantly more coliform bacteria on teat ends were found in herds with an increased percentage of normal or slightly rough teat ends. Cleaning cubicles more frequently, pre-cleaning teats before milking as well as post-dipping them after milking had a decreasing effect of teat-skin load with total mesophilic and coliform bacteria at the herd level. To conclude, teat-skin bacterial load with environmental pathogens is subject to fluctuations and can be influenced by aspects of farm hygiene.

Environmental DNA is effective in detecting the federally threatened Louisiana Pinesnake (Pituophis ruthveni)

AbstractSuccessful conservation of rare, threatened, or endangered (RTE) species is dependent upon rapid and accurate assessment of their distribution and abundance. However, assessments are challenging as RTE species typically exist as numerically small populations in often fragmented habitats and can possess complex natural histories. Environmental DNA (eDNA) analysis may provide a rapid, cost‐effective means of assessing RTE species presence/absence in viable habitat patches. We evaluated the efficacy of eDNA surveillance for the Louisiana Pinesnake (Pituophis ruthveni), an elusive, semi‐fossorial, nonvenomous colubroid snake endemic to Louisiana and Texas, USA, that has dramatically declined in both distribution and abundance. We developed two quantitative polymerase chain reaction (qPCR) assays that target the mitochondrial cytochrome c oxidase subunit I (COI) and mitochondrially encoded ATP synthase membrane subunit 6 (ATP6) genes. We validated each assay in silico, in vitro, and in situ, and investigated the influence of eDNA extraction method and genetic marker on assay performance. Both assays were highly sensitive and successfully detected the Louisiana Pinesnake under artificial and field conditions, including bedding samples collected from captive snake enclosures (100%), soil samples from Louisiana Pinesnake release sites (100%), and soil samples from sites where Louisiana Pinesnakes were documented via radio telemetry (45%). Although differences between genetic markers were negligible, assay performance was strongly influenced by eDNA extraction method. Informed by our results, we discuss methodological and environmental factors influencing Louisiana Pinesnake eDNA detection and quantification, broader implications for management and conservation of the Louisiana Pinesnake and other terrestrial reptiles and provide recommendations for future research. We suggest that eDNA surveys can more effectively assess Louisiana Pinesnake occupancy than conventional sampling, highlighting the need for comprehensive eDNA monitoring initiatives to better identify suitable habitat that will promote persistence of this imperiled species going forward.

Evaluating the permeability properties of green bed in iron ore sintering using high resolution X-ray computed tomography and orthogonal array tests

This study reconstructed porous structure and numerically evaluated permeability properties over several green sinter bed samples by applying X-ray computed tomography (XCT) and orthogonal array tests together. Contributions of three factors including moisture, hydrated lime and magnetite concentrate on experimental Japanese Permeability Units value and XCT-simulated absolute permeability coefficient were analyzed and compared. Results portray that pore network model is helpful to extract the pore distribution and topology in green sinter bed, the observed increase in green bed permeability is attributed to the increase of pore radius, throat radius and throat length, rather than tortuosity. The optimum combination for improving green bed permeability is 7.8% moisture, 4% hydrated lime and 0% concentrate. Moisture and hydrated lime factors are the more effective parameters on bed permeability while concentrate factor is insignificant, since those binders have different mechanisms in determining the outcome granule size distribution and strength, resulting in various pore properties.

Carbonate mineral identification and quantification in sediment matrices using diffuse reflectance infrared Fourier transform spectroscopy

Carbonate minerals are a major reservoir in the global carbon cycle and a key player in the sequestration and emission of atmospheric CO2. In addition to the minerals’ frequent use in agriculture and construction, carbonate formation has been targeted for anthropogenic CO2 sequestration. Due to carbonate’s importance in geological and anthropogenic realms, research on carbonate characterization and quantification is of interest. Here, we demonstrate a method to identify and quantify calcite (CaCO3) and dolomite (CaMg(CO3)2) in sediment matrices using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Needing only a few minutes per sample, DRIFTS is a rapid technique that does not require hazardous chemicals and does not destroy samples during analysis. We selected the 2515 ± 9 cm−1 absorbance bands for quantification as they exhibited little interference from sediment matrix minerals and large peak areas relative to other bands. The DRIFTS technique was compared to the traditional acidification headspace analysis method on artificial mixtures of sediment and carbonate as well as natural lake bed and river bank samples from the Upper Sangamon River Basin in Illinois, USA. DRIFTS offers an additional advantage over acidification in that it permits carbonate mineral identification simultaneously with its quantification. Though DRIFTS estimates were higher, a good correlation was found between DRIFTS and acidification estimates for both lake sediments (R2 = 0.99) and bank samples (R2 = 0.92), indicating DRIFTS is a reliable method for carbonate quantification in sediment matrices.

Sediment Transport with Mixed Sand in Nonlinear Regular Waves

Ferreira, C.C.; Abreu, T.; Silva, P.A.; Bernabeu, A.; Romao, S., and Staudt, F., 2020. Sediment transport with mixed sand in nonlinear regular waves. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 408–411. Coconut Creek (Florida), ISSN 0749-0208.This work presents the results of an experiment carried out in the Large Wave Flume (Groser Wellenkanal, GWK) in Hannover, which enables full-scale wave experiments to be conducted above sand beds. The experiment consisted of a set of regular waves propagating over a 30 m long horizontal bed composed of a bimodal mixture of fine (F) and coarse (C) sands. Wave gauges placed along the test section and an ADV (Acoustic Doppler Velocimeter) placed above the wave bottom boundary layer allow characterizing the wave nonlinearity parameters (skewness and asymmetry). Fluorescent sand was inserted at the beginning of each experiment and subsequent bed samples allowed tracking its movement, differentiating between the coarse and fine sand fractions.This study presents the results obtained with a particular sediment mixture (75%F+25%C) for two regular trochoidal wave conditions with the same wave period, 7 s, but different wave heights, 1.0 and 1.5 m. The total net transport rates estimated from a practical sediment transport formula, which includes both effects of wave asymmetry and skewness, are comparable with those obtained with the fluorescent tracer.

Effect of magnetic field on a loosely packed, tightly packed and an over-tightly packed metal powder bed

The effect of alternating magnetic field on the pressure drop inside a fixed bed with different types of packing is experimentally investigated. The bed was packed with three different masses of iron(III)oxide powder as a loosely packed, tightly packed and an over tightly packed bed system. A Helmholtz coil was used to apply an AC magnetic field (60 Hz) and the pressure drop measurements were made for a range of flowrates between 29 SCFM to 25 SCFM at a small deceleration of 0.03 in/s2 (0.001 m/s2). The magnetic field was applied continuously throughout the time of pressure-drop measurements, and also was turned off before the measurements began to analyze the behavior of the bed. It was found that in a loosely packed bed system, the pressure drop decreased for all magnetic field orientations compared to the no magnetic field configuration, whereas in the tightly packed bed samples, the pressure drop values can be increased or decreased by altering the magnetic field orientation. In the tightly packed bed samples, the pressure drop values did not alter when the magnetic field was turned off during the flow and is only needed until the flow enters the bed.

Experimental study and modeling of biomass char gasification kinetics in a novel thermogravimetric flow reactor

This work pursues the validation of a new reactor for the evaluation of char gasification kinetics. This novel reactor allows continuous gas flow through the fixed bed sample and accurately monitoring the mass loss throughout the reaction. Accordingly, this thermogravimetric flow reactor has a great potential for the analysis of different thermochemical processes, such as pyrolysis and gasification of solid feedstocks. In this paper, the gasification of pine sawdust char was carried out and the effect carbon dioxide concentration (10 and 100 vol%) and temperature (800, 850 and 900 °C) have on char gasification kinetics was assessed. The experimental results were fitted to five different kinetic equations, i.e., homogeneous model (VM), shrinking core model (SCM), nth order model, random pore model (RPM) and modified random pore model (MRPM), and the best-fit parameters (frequency factor, activation energy, adjustable parameters and fitting error) were obtained for each model. The modified random pore model provides the best fit to the experimental data. The new thermogravimetric flow reactor allows obtaining rigorous kinetic results, which is clear evidence that the reactor is suitable for studying char gasification kinetics under CO2 atmosphere.

Epidemiology of Mastitis in Dairy Cattle with Special Reference to Some Associated Risk Factors

Mastitis is one of the most important health problems of dairy cattle as it causes physical, chemical and bacteriological changes in the produced milk, so the aim of this study is investigating the epidemiology of mastitis pathogens of dairy cattle and their associated risk factors. A total of 397 samples were gathered from mastitic cows and their surrounding environment including 127 milk samples from sub-clinically mastitic cows, 60 milk samples from clinically mastitic cows, 60 teat swabs, 50 milking machines swabs, 50 worker’s hand swabs and 50 bedding samples from different farms containing small and large dairy herds located in El Dakhalia and Menoufiya Governorate. These samples were examined bacteriologically and biochemically for isolation and biochemical identification of E. coli and S. aureus. Our results revealed that the prevalence of E.coli was 33.33% (11/33), 21.74% (20/92), 16.67% (4/24), 18.52% (5/27), 13.33% (2/15) and 13.33% (4/30) in milk samples from clinically mastitic cows, milk samples from subclinically mastitic cows, teat swabs, milking machines swabs, worker’s hand swabs and bedding samples, respectively, while the prevalence of Staphylococcus aureus was 23.08% (9/39), 17.43% (19/109), 11.9% (5/42), 10.53% (4/38), 17.07% (7/41) and 10.53% (4/38), in the same groups respectively. A significant relationship was found between of the number of these bacteria and cows age, herd size and hygienic condition of the farm. Moreover, PCR was done on 14 isolates of E. coli for detection of ESBL producing E. coli. The results of PCR revealed that the prevalence of blaTEM and blaSHV was 64.3% (9/14) and 92.9% (13/14), respectively, while none of the isolates carried blaCMY-2. We concluded that Staphylococcus aureus and E.coli are considered two main pathogens of mastitis and the prevalence of mastitis increases in old cattle, inadequate hygienic condition, lack of post milking teat dipping and absence of udder washing which are all predisposing risk factors of mastitis in the study area.

Sorptional Equilibrium of Gas-Bearing Coal in Sealed Vessels: Thermal Processes

Thermodynamic processes in a closed volume filled with gas-bearing Zh coal are investigated. Experiments are conducted with bed samples in a sealed vessel, which is equipped with a pressure sensor and four temperature sensors. The temperature variation in the vessel is found to be oscillatory. This may be attributed to heat transfer between layers with different granulometric composition and also to the structure of the coal particles.

Properties of Coal of Moderate Metamorphic Development

The physicochemical properties of Kuznetsk Basin coal are studied. The following distinctive features are confirmed for coal of moderate metamorphic development: minimum strength and gas-dynamic potential; and maximum risk of cracking and explosion, as well as maximum instability of the coal–methane system. For bed samples of different rank, we find that the petrographic characteristics of coal of metamorphic stages III–V include critical regions.

Lack of Standardization in the Processing and Reporting of Post-Neoadjuvant Breast Cancer Specimens.

The use of neoadjuvant therapy in the management of early-stage invasive breast cancer is increasing. Residual Cancer Burden and other similar tools use pathologic characteristics of post-neoadjuvant therapy breast tumors to determine long-term outcome. However, there are no standardized guidelines for the pathologic evaluation of these specimens in the routine clinical setting. To assess current practices among Canadian pathologists and pathology assistants with regard to the processing and reporting of post-neoadjuvant therapy breast specimens. An electronic survey was distributed to pathologists and pathology assistants across Canada. Sixty-three responses were obtained. A total of 48% (15 of 31) of surveyed pathologists reported familiarity with the Residual Cancer Burden tool. A total of 40% (25 of 63) of respondents reported a lack of routine use of specimen photography, and 35% (22 of 63) reported a lack of routine use of grossing diagrams. There was significant variation with respect to tumor bed sampling; the most common method was to submit 1 block per centimeter of tumor (20 of 63; 32%). There was also significant variation in the method of measuring residual tumor; the most common method was to measure the largest cross-section of residual tumor (16 of 32; 50%). There is a need for standardization of the evaluation of post-neoadjuvant therapy breast specimens in the routine clinical setting in Canada. We recommend the routine use of specimen mapping, submitting the largest cross section of tumor bed in toto, reporting tumor size as per American Joint Committee on Cancer and Residual Cancer Burden guidelines, and routinely including measurements of residual tumor cellularity and in situ disease in the final pathology report as per Residual Cancer Burden guidelines.

Bacterial concentrations in bedding and their association with dairy cow hygiene and milk quality

Comparison of bacterial counts (BCs) among common bedding types used for dairy cows, including straw, is needed. There is concern that the microbial content of organic bedding is elevated and presents risks for dairy cow udder health and milk quality. The objectives of this study were to investigate: (1) % DM and BCs (Streptococcus spp., all gram-negatives and specifically Klebsiella spp.) in different types of bedding sampled, and to investigate housing and farm management factors associated with % DM and BCs; (2) if bedding type was associated with hygiene of cow body parts (lower-legs, udder, upper-legs and flank) and housing and management factors associated with hygiene and (3) bedding types associated with higher BCs in cow milk at the farm level and bulk tank milk and management factors that were associated with highest BCs. Seventy farms (44 free-stall and 26 tie-stall) in Ontario, Canada were visited 3 times, 7 days apart from October 2014 to February 2015. At each visit, composite samples of unused and used bedding were collected for % DM determination and bacterial culture. Used bedding samples were collected from the back third of selected stalls. Data were analyzed using multivariable linear mixed models. Bedding classification for each farm were: new sand (n = 12), straw and other dry forage (n = 33), wood products (shavings, sawdust; n = 17) and recycled manure solids (RMSs)-compost, digestate (n = 8). In used bedding, across all bedding samples, sand was driest, compared to straw and wood, and RMS; higher % DM was associated with lower Streptococcus spp. count. Streptococcus spp. and all Gram-negative bacteria counts increased with increasing days since additional bedding was added. Gram-negative bacteria counts in used bedding varied with type: RMS = 16.3 ln colony-forming units (cfu)/mL, straw = 13.8 ln cfu/mL, new sand = 13.5 ln cfu/mL, and wood = 10.3 ln cfu/mL. Klebsiella spp. counts in used bedding were lower for wood products (5.9 ln cfu/mL) compared to all other bedding types. Mean cow SCC tended to be higher on farms with narrower stalls. Farms with mattress-based stalls had a higher prevalence of cows with dirty udders compared to those using a deep bedding system (often inorganic sand). Wider stalls were associated with lower bulk milk bacteria count. Lower % DM of used bedding was associated with higher bulk milk bacteria count. In conclusion, bedding management may have a profound impact on milk quality, bacterial concentrations in the bedding substrates, and cow hygiene.

Intra‐clinothem variability in sedimentary texture and process regime recorded down slope profiles

AbstractShelf‐margin clinothem successions can archive process interactions at the shelf to slope transition, and their architecture provides constraints on the interplay of factors that control basin‐margin evolution. However, detailed textural analysis and facies distributions from shelf to slope transitions remain poorly documented. This study uses quantitative grain‐size and sorting data from coeval shelf and slope deposits of a single clinothem that crops out along a 5 km long, dip‐parallel transect of the Eocene Sobrarbe Deltaic Complex (Ainsa Basin, south‐central Pyrenees, Spain). Systematic sampling of sandstone beds tied to measured sections has captured vertical and basinward changes in sedimentary texture and facies distributions at an intra‐clinothem scale. Two types of hyperpycnal flow‐related slope deposits, both rich in mica and terrestrial organic matter, are differentiated according to grain size, sorting and bed geometry: (i) sustained hyperpycnal flow deposits, which are physically linked to coarse channelized sediments in the shelf setting and which deposit sand down the complete slope profile; (ii) episodic hyperpycnal flow deposits, which are disconnected from, and incise into, shelf sands and which are associated with sediment bypass of the proximal slope and coarse‐grained sand deposition on the medial and distal slope. Both types of hyperpycnites are interbedded with relatively homogenous, organic‐free and mica‐free, well‐sorted, very fine‐grained sandstones, which are interpreted to be remobilized from wave‐dominated shelf environments; these wave‐dominated deposits are found only on the proximal and medial slope. Coarse‐grained sediment bypass into the deeper‐water slope settings is therefore dominated by episodic hyperpycnal flows, whilst sustained hyperpycnal flows and turbidity currents remobilizing wave‐dominated shelf deposits are responsible for the full range of grain sizes in the proximal and medial slope, thus facilitating clinoform progradation. This novel dataset highlights previously undocumented intra‐clinothem variability related to updip changes in the shelf process‐regime, which is therefore a key factor controlling downdip architecture and resulting sedimentary texture.

Gas Content of Kuznetsk Basin Bituminous Coal

The properties of bituminous Zh coal are studied. The change in gas content over time in sealed bed samples is determined. It is found that, for all size classes of coal, the pressure of the gas released from the coal stabilizes over 24 h; about half of the pressure increase occurs in the first 3 h. The gas content is greater in coal of the 5–10 mm class than in coal of the ≤3 mm class.

Air Permeability of the Litter Layer in Broadleaf Forests

Fuel on the ground, such as leaves, twigs and decomposing matter, accumulate over time and account for a large percentage of the total fuel load in forests. In fire events, material on the ground is often referred to as a fuel bed. The air permeability of a fuel bed is a critical factor that influences fire behaviour because it controls the amount of air or oxygen available for combustion within the fuel bed. The aim of this study is to provide a better understanding of the air permeability of the fuel beds in forests. The air permeability for different fuel beds were determined using experimental and theoretical methods. The pressure drop across the fuel bed samples were experimentally measured using a verified permeability testing rig. The air permeability was then calculated using Darcy's Law or the Forchheimer equation from the pressure drop measurements, depending on the Reynolds number. The particles in the fuel beds were characterised in terms of particle size and shape. Based on the particle characterisation, the air permeability of the fuel beds was also calculated using the Kozeny-Carman equation. The results show that the experimental method is preferred when determining the air permeability for natural forest fuel beds due to the variability in the size and shape of the particles. The effect of Reynolds number on effective permeability was aslo investigated, and it was found that the transition from Darcian to non- Darcian flow occur at different Reynolds numbers for different fuel particles. For example, the transition occurs at 5 and 15 for gum bark and decomposing matter, respectively. The significance of this study is that it increases the ability to predict the air permeability of fuel beds in forests, which is essential for modelling wildland fire behaviours involving in porous fuel beds. All the samples were dried at 105 OC to remove moisture in the samples.

Prevalence and GeneticDiversity of Bacillus cereus Isolated from Raw Milk and Cattle Farm Environments.

Bacillus cereus not only has adverse effects on the nutrition and shelf life of dairy products but also seriously endanger people's health. This studywasconductedto reveal the prevalence and geneticdiversity of B. cereus strains isolated from raw milk and cattle farm environments. A total 56 of B. cereus strains were detected from 300 environmental samples (soil, water, fodder, air, milk pails, milking machines, cowsheds, bedding, excrement, cow surfaces, udders, overalls, soles, and staff hand samples) and 50 raw milk samples, and divided into 18 sequence types (STs) using multilocus sequence typing method. These STs included ST27, ST61, ST92, ST142, ST168, ST208, ST378, ST427, ST766, ST 857, ST1098, ST1140, ST1194, ST1236, ST1336, ST1339, ST1341, and ST1348, among them, ST857 (7/56, 12.5%) was the dominant ST, and were detected from air, cowsheds, bedding, excrement, and raw milk samples. Our findings could reveal the distribution and genetic diversity of B. cereus strains in raw milk and cattle farm environments, and provide a theoretical basis for controlling the potential harm of this pathogenic bacteria in dairy products.

Humans reshape wetlands: Unveiling the last 100 years of morphological changes of the Mara Wetland, Tanzania.

The Lower Mara River and Wetland, Tanzania, is an important ecosystem and unique water resource for a vast semi-arid area. The river, an affluent of Lake Victoria, and the wetland are experiencing morphological and vegetation changes resulting in channel avulsions and wetland expansion. This study analyses the changes over the last 100 years and investigates natural and anthropogenic behaviors to explain the increase of the Mara Wetland area. We collated historical topographic maps and satellite images. We conducted two field surveys in low and high flow condition with an unmanned aerial vehicle, a sonar and an ADCP. We mapped selected areas as well as the bed topography in some stretches of the river, measured discharges, and collected river bed and suspended sediment samples. The analysis of the sediments shows that the wetland system, dominated by papyrus sp., is very efficient in trapping sediment, releasing clear water to the Lake Victoria. The historical reconstruction using topographic maps, satellite images and a multivariable analysis including hydrology and land cover, shows that 4 major avulsions occurred in the last 70 years due to a combination of natural behaviors, hydrological fluctuations and anthropogenic factors such as basin deforestation, farming and grazing along the river banks and in the wetland. Each avulsion led to substantial expansion of the wetland. Combined, they increased the wetland area by a factor of 3.6. Describing the Lower Mara River dynamic behavior, this work provides relevant information for sustainable future water and sediment management in order to preserve wetland habitats and natural resources.