Higher Carbon Levels Research Articles

Status and Properties of Soils under Some Woody Species of Degraded Glacis in Northern Burkina Faso

Land degradation is a threat to biodiversity and has negative impacts on agricultural communities by aggravating food insecurity. The objective of this study was to examine the responses of native woody species and soil variables to different levels of glacis degradation in the Sahelian zone of Burkina Faso. Field investigations were performed according to the degradation gradient outlined in the Braun-Blanquet method. Soil samples were collected and analyzed in the laboratory. The results indicate that the diversity and diametric structure of woody species are functions of the glacis degradation stage. A total of eight (08) woody species were recorded on the glacis (7 species in non-degraded glacis, 7 species in moderately-degraded glacis and only 1 species in degraded glacis). Acacia raddiana is the only local woody species present in all three glacis degradation stages. It is recommended to rehabilitate degraded glacis in the Sahel in response to desertification. The high levels of sand, nitrogen (N) and carbon (C) characterize the non-degraded and moderately-degraded glacis, whereas the high levels of silt, clay, bulk density, pH-H20 and pH-Kcl indicate degraded glacis. This study can inform the future rehabilitation and management of Sahelian glacis.

High Magnesium Calcite and Dolomite composition carbonate in Amphiroa (Lithophyllaceae, Corallinales, Rhodophyta): further documentation of elevated Mg in Corallinales with climate change implications.

Species of the calcified, articulate coralline Amphiroa are key components of many shallow marine ecosystems. Understanding their mineral composition is important as their susceptibility to dissolution, due to ocean acidification, may vary with mineral composition. We studied the distribution of Mg-calcite, very high magnesium calcite (VHMC), and dolomite within Amphiroa species to elucidate their mineral properties and susceptibility to dissolution. Results revealed that the asymmetrical X-ray diffraction (XRD) pattern typical of Amphiroa globally represents high levels of VHMC and dolomite composition carbonate. The dolomite seems most likely to be disordered, but higher resolution XRD is required for confirmation. The calcified long sides of medullary cells have predominantly VHMC/dolomite and the corners have bands of VHMC/dolomite. Epithallial cell walls are low Mg-calcite, and cortical cells are low Mg-calcite with bands of VHMC. VHMC/dolomite is more stable than Mg-calcite, and this may provide a competitive advantage for Amphiroa species as seawater pH declines. Further work is required to determine the metabolic controls on VHMC/dolomite mineral formation.

Unraveling membrane fouling in anoxic/oxic membrane bioreactors treating anaerobically digested piggery wastewater

Anaerobically digested piggery wastewater (ADPW) draws increasing attention due to the high nitrogen and carbon level. In this study, four parallel lab-scale anoxic-oxic membrane bioreactors were applied to treat ADPW with the hydraulic retention time (HRT) of 75, 60, 45 and 30 h, respectively. Reactor performance and membrane fouling mechanisms also have been systematically evaluated. The results demonstrated a decline in chemical oxygen demand and total nitrogen biodegradation (from 65.8 ± 2.5% and 62.2 ± 5.5% to 38.6 ± 3.6% and 26.2 ± 5.7%, respectively) and a rise in membrane resistance (from 37.34 × 1012 m−1 to 51.69 × 1012 m−1) as the HRT decreased. The decline of HRT didn’t affect the functional group types of cake layer extracellular polymeric substances (EPS) and tightly bound EPS (TB-EPS) of activated sludge, but led to the increased concentrations of protein (PN) and polysaccharide (PS) in loosely bound EPS (LB-EPS) and soluble microbial products (SMP) of activated sludge and a decreased PN/PS ratio in SMP. These changes in SMP and EPS accelerated the formation of cake layer and aggravated the membrane fouling. Proteobacteria and Bacteroidetes were the predominant phyla on membrane surface. The abundant Proteobacteria in the reactor with longer HRTs was beneficial to mitigate membrane fouling while the relative abundance of Bacteroidetes remained stable in all reactors. The enrichment of Thauera was the primary reason for membrane fouling at genus level in the reactors. This study provides scientific insights on the practical application of membrane bioreactors in terms of membrane fouling control.

Análise do comportamento do par tribológico aço fundido alto C e alto Si contra o metal duro com e sem revestimento de TiN

Aços fundidos com altos teores de carbono (C) e silício (Si) com estrutura bainítica têm despertado o interesse em estudos e aplicações da indústria metal-mecânica, por combinar elevada resistência e alta ductilidade. Essas características são devido à formação de múltiplas fases na sua estrutura, que são ativadas após tratamento térmico de austêmpera. No processo de manufatura desses materiais, etapas de usinagem são implementadas com o material ainda no estado recozido, de modo a facilitar a sua usinabilidade. Aço fundido no estado recozido, têm sido estudados para avaliação da usinabilidade e comportamento tribológico, que auxiliam na seleção mais eficiente de materiais para ferramentas de corte. Sendo assim, este trabalho avaliou o comportamento ao desgaste do metal duro com e sem revestimento de nitreto de titânio (TiN) deslizando contra o aço fundido no estado recozido (270 ±3 HV). Os resultados de pino sobre disco (PSD) indicaram que o conjugado com revestimento apresentou os menores valores de coeficiente de atrito. Entretanto, verificou-se maiores valores de coeficiente de desgaste específico (K) para o conjugado com revestimento réplica. Esse fato foi atribuído ao um possível desplacamento do revestimento TiN. O trabalho contribuiu para o entendimento do comportamento tribológico e a identificação dos mecanismos de desgaste que ocasionaram danos na superfície dos materiais avaliados.

Holoplankton and meroplankton of three western Atlantic sedimentary basins

ABSTRACT Holoplankton and meroplankton were investigated in three different basins of the Brazilian Equatorial Margin, from January to May of 2015. The copepods Clausocalanus furcatus, Undinula vulgaris, Nannocalanus minor, Scolecithrix danae, and the larvacean Oikopleura longicauda were the most abundant and frequent organisms. Simultaneously, decapod and mollusk larvae, and larval fish, were the most abundant meroplankton. The decapod Anapagurus chiroacanthus was recorded in the western Atlantic for the first time. The highest richness and diversity occurred in the Foz do Amazonas Basin, while the Pará-Maranhão Basin had the highest abundance, associated with high levels of total organic carbon. There was a clear separation among the three basins in the occurrence of some species. Our study revealed significant variability in the holo- and meroplankton communities of the region. The significant differences in suspended solids explained the holo- and meroplankton distribution among basins, mainly in the sampling stations of the Foz do Amazonas Basin, which is related to the influence of the Amazon River plume in this region.

Failure Analysis of Metallic Orthopedic Implant for Total Knee Replacement

Fractures resulting from wear and fatigue process have been identified as the main causes of failure in biomaterials, especially in implants that act in place of bone or other hard tissue, as they are subject to conditions involving severe cyclic loadings. In biomaterialscase, the types of failures mentioned above must also be evaluated under the effect of degradation or corrosion, due to the direct contact with body fluids. The present research analyzed the fatigue induced by corrosion fracture of an orthopaedic implant for total knee replacementproduced with an austenitic ASTM F138 stainless steel. The morphology, compositions of the interfaces and subsequent corrosive pitting were characterized by stereoscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Stress concentration, inclusions and high carbon levels were the main reasons of failure.

Implications of carbonates and chlorides contamination in groundwater: Examples from textile tie and dye markets in some parts of Southwestern Nigeria

Objectives: To evaluate the impact of common mineral dyes in effluents from dyeing processes on the quality of groundwater at Itoku and Asero, Abeokuta in Nigeria. Methods: Thirty-two (32) samples were examined by determining the In-situ parameters: Total Dissolved Solids (TDS), Electrical Conductivity (Ec) and pH with the aid of a multi-parameter portable meter(model Testr-35); Chemical parameters were determined with Atomic Absorption Spectrometry (AAS)and Titration methods for both cations and anions. Collected samples were analyzed for heterotrophic bacteria load using standard method. Findings: Elevated Ec-1830 µS/cm and TDS-1020mg/l values at Odutola-8 exceeded the WHO permissible limit with bicarbonate, carbonate and chlorides presence, in the water sample. DO at Ifote-6.0, Asero-6.8, Ifote-7.1, Asero carwash-7.9 was greater than WHO standard, specifying water that can support aquatic life and micro-organisms. However, other areas had low dissolved oxygen below the specified permissible limit. The results of the physicochemical parameters including; Chloride and Carbonate levels in effluent and groundwater in most of the studied sites were higher than the World Health Organization (WHO) permissible limits. Dye effluents and well water samples displayed high microbial loads. Predominant bacteria isolated from the effluent and groundwater included Aspergillus spp. Pseudomonas aeruginosa and Bacillus subtilis. Polycyclic aromatic hydrocarbon (PAHs) observed indicated probable human carcinogens found where dye fabrication processes were high and effective. Novelty: Dye effluents have high bacterial and fungal loads. Similarity in the predominant bacteria isolated from effluent and groundwater from the hand-dug wells indicated that the effluent from the dyeing processes is negatively impacting the groundwater and this may pose a risk to public health. High levels of Carbonates, bicarbonates and chlorides in groundwater indicate contamination; making the water unfit for human and animal consumption. Keywords: Minerals; dyes; contamination; groundwater; carbonates; chlorides

Hydrothermal carbonization of sewage sludge coupled with anaerobic digestion: Integrated approach for sludge management and energy recycling

Sewage sludge management is a major operational task that challenges sustainability in municipal wastewater treatment plants. On the other hand, the high level of organic carbon in sewage sludge suggests its utilization potential for renewable energy applications. This study investigates hydrothermal carbonization (HTC) of anaerobic sludge at increasing temperatures (200, 250 and 300 °C) and retention times (30, 60 and 120 min), providing a wide spectrum of reaction severities (logR0 = 4.4–8.0). The goal of the study was to quantify the energy recovery from hydrothermal co-products (i.e., hydrochar and process water) for their use as a solid fuel and a feedstock for anaerobic digestion (AD), respectively. The hydrochar yield was quantified and its quality was evaluated for elemental composition, higher heating value and combustion behavior using thermogravimetric analysis. The hydrothermal process water was analyzed for its chemical oxygen demand and biochemical methane potential. The hydrochar yield was negatively affected by reaction severity with the highest value of 73% at logR0 of 4.4 and the lowest value of 49% at logR0 of 8.0. On the other hand, the hydrochar quality was found to be positively influenced by reaction severity, which enhanced the reduction of oxygen by decarboxylation processes. The biomethane yields were also affected by the reaction severity, with the highest potential value of 227 mL CH4 g COD−1 at the lowest severity and the lowest potential value of 28 mL CH4 g COD−1 at the highest severity. An overall energy balance suggests that mild reaction severities can serve as a suitable platform returning more than 70% of the energy from anaerobic sludge using the HTC-AD process integration.

Soil microbial community, enzyme activity, C and N stocks and soil aggregation as affected by land use and soil depth in a tropical climate region of Brazil.

The impact of agricultural land-use on soil microbial community composition and enzyme activity has not been extensively investigated in Ultisols. We investigated soil health parameters by analyzing phospholipid fatty acids (PLFAs), extracellular enzyme activity, C and N stocks, and soil structure. Four land uses were established in a tropical climate region of Brazil: native Cerrado (savanna), monoculture pasture [Urochloa brizantha (Hochst. Ex A. Rich.) R. Webster 'Marandu'], an integrated crop-livestock system (ICLS), and maize (Zea mays)-fallow in a no-tillage system. Soil microbial biomass was 40% higher in the native Cerrado than in the monoculture pasture, ICLS, and no-tillage maize. Soil organic carbon was positively correlated with microbial community composition (MB; gram-; AC; AMF; Fungi; F: B ratio) and enzyme activity (bG, AP, NAG). Large macroaggregates were positively correlated with bG, AP, and AMF. In summary, the native Cerrado had a higher level of carbon at the soil surface and greater soil structure with increased microbial biomass, gram+ bacteria, AMF, fungi, and F:B ratio in a tropical region of Brazil. However, bG and AP enzyme activities were lower in the ICLS and no-till maize at the soil surface (0-5cm) compared to the native Cerrado. The conversion of native Cerrado to agricultural systems shifted the soil microbial community composition, enzyme activity, C and N, and soil structure of this sandy soil of the Brazilian Cerrado.

Organic matter and organic carbon levels in sediments of Lake Maninjau, West Sumatra

The organic matter content of lake sediments provides a variety of indicators, or proxies that can be used to reconstruct paleoenvironments of lakes and their watersheds. Particularly, in this study it will provide information that is important to interpretations of both natural and human-induced changes in lake ecosystems. The abundance of organic matter in sediments is described from the total organic carbon (TOC) because it’s a primary parameter. Moreover, Algae is the main source of organic carbon in the eutrophic lake. Lake Maninjau that located in West Sumatra has been eutrophic due to increasing of lake water utilization for floating fish cages, in recent years Lake Maninjau has faced an algal bloom frequently. Four sediments core were collected in Lake Maninjau from the lowest (near coastal) and deepest part (30 cm long core in average). Total organic matter (TOM) was performed using Lost on Ignition method (LoI) in whole cores, while total organic carbon (TOC) was analyzed using combustion analyzer method in one core that was taken in the deepest part of Lake Maninjau. TOM in Lake Maninjau among the cores varied between 21 to 34% at the surface, then decreased slowly as a depth. The percentage of surface TOM in the near coastal is elevated to the deepest part (21% to 34%). The TOC content in the surface was 9%. According to the Mid-Atlantic Integrated Assessment (MAIA) Estuaries the TOC concentrations in the sediments was in the range of high organic carbon level (>3%). The high value of TOC level in the surface sediment was controlled by algal productivity.

The effect of natural materials used as sediment remediation on phosphorus and nitrogen control in a mesocosm

BackgroundAchieving nitrogen (N) and phosphorus (P) control in sediment remediation projects by adding natural materials is receiving increasing attention. In this study, different natural materials, including iron-rich clay minerals, calcite, kaoline, sugarcane bagasse and Phragmites detritus, were applied to test their effects on N and P in a mesocosm experiment.ResultsIron-rich clay minerals and Phragmites detritus had obvious advantages for P control; they resulted in almost undetectable levels of soluble reactive phosphorus (SRP) in the water column throughout the experiment. This finding can be explained by their strong P adsorption ability. The high level of available organic carbon in the sediment and water column after sugarcane bagasse addition provided enough electron donors for denitrification and dissimilatory nitrate reduction to ammonium (DNRA), which caused nitrate (NO3−-N) deficiency and ammonium (NH4+-N) accumulation in the water column. Additionally, this resulted in anaerobic conditions, further fuelling the release of P from iron-bound P induced by anoxia. Thus, the amount of sugarcane bagasse applied should be considered carefully in order to balance denitrification and DNRA as well as P releases. Calcite and Phragmites detritus are recommended as remediation materials for N removal based on their significant promotion of denitrification and limitation of DNRA, which resulted in low NO3−-N and NH4+-N levels. These results can be explained by the shifts in the functional microbial community composition and abundance after the addition of natural materials.ConclusionsIron-rich clay minerals and Phragmites detritus are promising sediment remediation materials for P immobilization due to their strong P adsorption ability. Taken together, the selection of sediment remediation materials should consider the N and P coupling relationship, to prevent NO3−-N removal from causing P leaching or NH4+-N accumulation.

Establishment and evaluation of anthropogenic black and organic carbon emissions over Central Plain, China

The Central China represented by Henan Province is one of the most haze-polluted regions in China with high levels of black carbon (BC) and organic carbon (OC) emissions. In this study, a 2016-based BC and OC emission inventory of Henan Province was developed based on detailed activity data and latest emission factors from different sources involving particulate matter. The total annual emissions of BC and OC were estimated to be 117.6 kt and 162.8 kt, respectively. Industrial process (44.2%) and industrial combustion (17.0%) were the top two contributors for BC emission, whereas OC emission was mainly from biomass burning (36.8%). Typical industrial cities were the major contributors to BC emission, by contrast, relatively higher OC emission was concentrated on agricultural cities in the southeast of Henan Province. The OC/BC ratios of industrial cities were generally lower than those of southeastern agricultural cities. The monthly variations presented that the highest BC and OC emissions were concentrated in January and June, respectively. Overall, in this study, the quantitative uncertainty ranges on the 95% confidence interval were approximately −30%–47% for BC and −38%–65% for OC. The emission inventory was also verified by qualitative comparison with other studies and indirect evaluation of OCpri/EC ratios, and the result was within a reasonable range. The ways of discussion and evaluation in this study can provide reference for other regions.

Evaluating soil and nutrients (C, N, and P) loss in Chinese Torreya plantations

Improper land-use changes may lead to a loss of soil resources and cause environmental pollution. Chinese Torreya plantation (hereafter CTP) is an important cash tree plantation for nuts production in the mountainous areas of subtropical China. The increasing development of CTPs, to increase seed production, can result in the complete erasure of local natural vegetation.In this study, the vulnerability to soil erosion, loss of soil organic carbon (SOC) and nutrients in CTPs due to land-use change were evaluated. The results indicated that the rates of diffusive soil erosion in the young CTPs with extreme precipitation were about six-fold higher than with the natural vegetation. At sites with a similar slope, there was no significant difference in soil erosion levels between the young and old CTPs. The old CTPs did not hold significantly higher levels of SOC and soil total nitrogen (STN) in their topsoil when compared with the young CTPs. The natural mixed broadleaved subtropical forests lost about 35% of their SOC and 25% of their STN after they were converted into CTPs, but the CTPs had higher soil total phosphorus. The C: N ratios at the different sites were close to 11:1, but the N: P ratios were diverse. There were high levels of organic carbon, nitrogen and phosphorus in stream water. Adequate coverage of natural vegetation within or around the CTPs should be maintained to decrease soil erosion and nutrient loss. Suggestions to develop CTPs while protecting the environment are discussed. Overall, it was determined that aspects of the current management practices and strategies for developing CTPs should be changed to decrease soil erosion and nutrient loss.

Shale as a Source of Organic Carbon in Floodplain Sediments of a Mountainous Watershed

AbstractShales contain high levels of organic carbon (OC) and represent a large fraction of the Earth's reduced carbon stocks. While recent evidence suggests that shale‐derived OC may be actively cycled in riverine systems, this process is poorly understood and not currently considered in global C models. Through the use of sediment density fractionations, extractions, radiocarbon measurements, and chemical characterization, we provide information on the abundance, chemistry, and mobility of shale‐derived OC in floodplain sediments of a shale‐rich mountainous watershed. The heavy fraction of the sediment, representing mineral‐associated OC, is the largest (84 ± 6% of TOC) and oldest (Δ14C values −224 to −853‰) OC pool. Evidence of shale‐derived OC is observed in all sediment C pools (i.e., occluded light fraction, water‐soluble, and pyrophosphate‐extractable) except the free light fraction, which is entirely modern. Relatively consistent chemistry was observed across samples for extracted and density‐separated OC, despite wide ranges of Δ14C values. Carbon spectroscopy revealed that floodplain sediments had a higher degree of functionalized aromatic groups and lower carbonate content compared to shale collected nearby, consistent with chemical alteration and mixing with other C sources in the floodplain. We estimate that approximately 23–34% of sediment OC is derived from shale, with implications for other shale‐derived elements (e.g., N). This study demonstrates the important contribution of shale‐OC, particularly in environments with low litter inputs. The large impact of radiocarbon‐dead shale‐OC, which has a thermally altered chemical structure distinct from plant litter, on Δ14C values and reactivity of sediment‐OC must be considered.

Tillage intensity reduces the arbuscular mycorrhizal fungi attributes associated with Solanum lycopersicum, in the Tehuantepec Isthmus (Oaxaca), Mexico

Understanding the responses of arbuscular mycorrhizal fungi (AMF) attributes and soil properties to tillage intensity is useful for the management of agroecosystems, especially in tropical lands, which are under intense pressures for human activities. This study aimed to examine the AMF attributes such as spore-based species richness, spore density, and root mycorrhizal colonization in systems with different tillage practices (intensive, traditional, and conservation). The soil of the study systems were sandy loam, moderately alkaline, and showed low levels of inorganic nitrogen and available phosphorus. Conservation tillage displayed the lowest pH and the highest inorganic nitrogen, soil organic carbon, and soil organic matter levels. Traditional tillage showed the lowest available phosphorus concentrations and the highest electric conductivity levels. Conservation tillage system showed the highest AMF spore-based species richness, spore density, and root mycorrhizal colonization; in contrast to intensive tillage that showed the lowest values. Spore density was not affected by the tillage intensity. Spore density and root mycorrhizal colonization appeared to increase with low available phosphorus levels. Spore density seemed to decrease as the levels of soil organic carbon and sand increased; by the contrary, root mycorrhizal colonization appeared to increase with high soil organic carbon levels, and decreased as the levels of inorganic nitrogen increased. This study highlights the conservation tillage as a useful management tool for maintaining the AMF attributes and soil properties.

Martensitic wear resistant steels alloyed with titanium

The traditional approach to improving the abrasion wear resistance of martensitic steels is to increase their hardness via high carbon levels. However: (i) a higher hardness is usually accompanied by a lower toughness, negatively affecting the impact wear resistance, and (ii) increased carbon concentrations reduce weldability and complicate thermal cutting. This work explored microalloying with Ti as a method to simultaneously increase hardness and toughness via a concurrent precipitation of coarse TiMoVCN, fine TiC and fine Fe3C particles. Five plate steels containing <0.4C, <0.8Ti, Mn, Si, Cr, Mo and V (wt. %) were melted, cast, hot forged and heat treated to replicate an industrial processing technology. Dependences of mechanical properties on steel composition were studied using hardness, tensile, Charpy impact, pin-on-drum wear (two-body abrasion wear conditions) and impeller wear (two-body impact wear conditions) testing. Microstructure characterisation was carried out using optical and scanning electron microscopy. With an increase in Ti/C ratio: hardness and strength showed a dependence with a maximum; toughness a dependence with a minimum; and wear resistance (both abrasion and impact) a dependence with a maximum. The maximum wear resistance (at Ti/C = 0.314) did not correspond to either hardness (at Ti/C = 0.905) or toughness (at Ti/C = 0.018) maximum, but matched the highest tensile strength. The fracture development at the particle-matrix interface was found to govern the wear mechanism in the studied steels.

CHARACTERIZATION OF AQUATIC ORGANIC MATTER IN A NATURAL ENVIRONMENT IN NORTHEASTERN BRAZIL

The organic matter (OM) contained in a natural aquatic environment, located in a tropical region in Notheastern Brazil, was characterized using synchronous fluorescence spectroscopy and UV-Vis absorbance. The synchronous fluorescence spectra did not show qualitative differences for samples collected during dry and rainy seasons. They also revealed two peaks, one at 390 nm and other at 460 nm, associated with humic substances. The lack of peaks with significant fluorescence intensity at 270 - 300 nm and at 320 - 370 nm confirms it is an environment with natural OM. The A254/A436 ratios obtained during the dry and rainy seasons (13.55 to 14.97) indicate the presence of allochthonous OM of terrestrial origin, with high level of aromatic carbon associated with humic substances. The OM photodegradation by natural sunlight was more pronounced in the first five days, with a decrease of FImax from 23.6 to 55.4%. Also, titration with Cu(II) ions was used to determine the complexation ability of the two fluorescent sites, obtaining log K values of 4.26 and 4.27.

Comparison of nutrient management recommendations and soil health indicators in southern Idaho

AbstractAdvanced soil tests can improve the estimation of plant available nutrients to better match fertilizer additions with plant needs and, in some cases, provide a measure of soil health. In the present study, 334 samples from four separate studies were evaluated using the Soil Health Tool (SHT) vs. the standard regional (University of Idaho [UI] Guidelines) method for determining fertilizer application, assuming a crop of spring irrigated wheat. Recommended N applications using the SHT were ∼138 kg ha−1 greater than the UI recommendations. Nitrogen mineralization predicted using the SHT (47 kg ha−1) was similar to the N mineralization value used in the regional methodology (50 kg ha−1). The P fertilizer recommendations were similar between the two methodologies with the SHT recommending, on average 4.7 kg ha−1 less P than the regional method. The lower P recommendation are likely due to a lack of accounting for the effects of high calcium carbonate levels on the P availability from fertilizers in this region. The soil health score (SHS) was correlated with measures of soil C but was not positively correlated to crop yield. In some instances, increasing SHS were correlated with decreases in crop quality as the addition of manure increased soil C but also created issues such as high salt contents and release of late season N. With modification to more accurately represent irrigation conditions and including sampling to greater soil depths, the SHT may be tailored to better estimate soil nutrient status and provide better fertilizer recommendations for the region.

Production of Iron Nuggets from the Akpafu-Todzi Iron Ore and Artisanal Ferrous Slag using Post Consumer Thermosets (Waste Electrical Sockets) as Reductants

AbstractPost-consumer thermosets are difficult to recycle because, unlike thermoplastics, they cannot be remoulded to create other items as a result of the extensive cross-linkages in their structure. The increased production of thermoset blends and composites in recent years has greatly increased the amount of waste materials. However, higher levels of carbon and hydrogen present in thermosets make them a potential reductant in the iron extractive industries. In this research work, postconsumer thermoset was transformed into carbon resource through a charring process. The resulting carbonaceous material from the thermoset was used as reductant in the production of metallic iron from the Akpafu-Todzi iron ore and artisanal slag using the microwave technology through the composite pellet approach at varying firing times. Analyses by XRF, XRD and SEM/EDS showed that the Akpafu Todzi iron ore is comprised of the iron oxides hematite (Fe2O3) and wustite (Fe0.942O), while the artisanal slag was predominantly fayalite (Fe2SiO4). Complete reduction of the ore was attained after 120 min reduction but the maximum extent of reduction was 78.84% for the slag, demonstrating the potential of postconsumer thermosets to function effectively as a reductant in the iron extractive industry. Keywords: Reduction; Akpafu-Todzi Iron Ore; Post Consumer Thermosets; Waste Electrical Sockets

Fuzzy Object-Based Image Analysis Methods Using Sentinel-2A and Landsat-8 Data to Map and Characterize Soil Surface Residue

Soil degradation, defined as the lowering and loss of soil functions, is becoming a serious problem worldwide and threatens agricultural production and terrestrial ecosystems. The surface residue of crops is one of the most effective erosion control measures and it increases the soil moisture content. In some areas of the world, the management of soil surface residue (SSR) is crucial for increasing soil fertility, maintaining high soil carbon levels, and reducing the degradation of soil due to rain and wind erosion. Standard methods of measuring the residue cover are time and labor intensive, but remote sensing can support the monitoring of conservation tillage practices applied to large fields. We investigated the potential of per-pixel and object-based image analysis (OBIA) for detecting and estimating the coverage of SSRs after tillage and planting practices for agricultural research fields in Iran using tillage indices for Landsat-8 and novel indices for Sentinel-2A. For validation, SSR was measured in the field through line transects at the beginning of the agricultural season (prior to autumn crop planting). Per-pixel approaches for Landsat-8 satellite images using normalized difference tillage index (NDTI) and simple tillage index (STI) yielded coefficient of determination (R2) values of 0.727 and 0.722, respectively. We developed comparable novel indices for Sentinel-2A satellite data that yielded R2 values of 0.760 and 0.759 for NDTI and STI, respectively, which means that the Sentinel data better matched the ground truth data. We tested several OBIA methods and achieved very high overall accuracies of up to 0.948 for Sentinel-2A and 0.891 for Landsat-8 with a membership function method. The OBIA methods clearly outperformed per-pixel approaches in estimating SSR and bear the potential to substitute or complement ground-based techniques.