Sequential Extraction Technique Research Articles

Valorizing Lycii fructus waste residue into polysaccharide-rich extracts: Extraction methodologies, physicochemical characterization, in vitro activities and economic feasibility

The high polysaccharide content of Lycii fructus agri-food waste should be reclaimed for value liberation from both environmental and economic perspectives. In this study, waste from L. fructus pigment products was valorized on a bench scale by upcycling into active polysaccharide-rich extracts. The methodological feasibility of polysaccharide recovery from L. fructus waste was evaluated using sequential extraction techniques. Three fractions LFP-30, LFP-100, and LFP-121, were obtained under stepwise increases in temperature and pressure. Highly heterogeneous xyloglucan (XG)-pectin macromolecules composed of linear homogalacturonan (HG) and alternating intra-RG-I-linkers, with topological neutral branches and XG participation, were predominant among the L. fructus polysaccharides (LFPs). Antioxidant activities in LFPs were unaffected by waste resources and severe extraction methodology conditions. Additionally, the direct investment potential of polysaccharide recovery was evaluated for full-scale implementation. This study demonstrated the necessity and feasibility of extracting bioactive polysaccharides with potential applications from L. fructus waste, and provided a sustainable strategy for transforming L. fructus waste disposal problems into value-added products using cost-effective methodologies.

Comprehensive evaluation of the distribution, transport and ecological risk of heavy metals in intra-urban river sediments using high-resolution techniques

Determining the distribution trends, transport mechanisms, and ecological risks of heavy metals (HMs) in urban river sediments is essential for the government to conduct appropriate remediation work. In this study, we collected sediment cores from the Yayao Waterway in Foshan City, China. The vertical distribution profiles of dissolved and labile Fe, Mn, Cd, Zn, Cu, Cr, Ni, Pb, As, and Co in the sediments were obtained using the thin-film diffusive gradient (DGT) and high-resolution peeper (HR-Peeper) techniques. In addition, the transport rates, contamination levels, and ecological concerns of the HMs were evaluated using the European Community Bureau of Reference (BCR) sequential extraction technique, the DGT-induced sediment fluxes (DIFS) model, and multiple contamination evaluation metrics. The results showed that most of the DGT-labile HMs were associated with Fe/Mn (hydrogen) oxides, and in particular, Zn, Ni, and Cr showed a significant negative correlation with Fe/Mn (p < 0.001). Additionally, Cd had the highest bioavailability (89.17%), and its net diffusive flux at the sediment–water interface (SWI) was positive, which indicated a high release risk from the sediment. However, the R-value of Cd based on the DGT-induced sediment fluxes (DIFS) operation was extremely low, suggesting that although Cd had the biggest supply pool of releases, its release rate was slow. The majority of sampling sites had significantly higher total HM contents in the surface sediments than the background values. The HM contamination in the sediments originated from human activities, primarily from industrial enterprises and with a large contribution from both agricultural and domestic sources. The most polluted HM with the highest ecological danger was Cd, followed by Cu, Zn, Ni, and As when the results of the four pollution evaluation indicators were combined. Consequently, the risk of contamination by HMs in inner-city river sediments should receive more attention.

Trace metal speciation trends in Mazowe dam, Zimbabwe, a typical sub-tropical dam ecosystem impacted by gold mining and agriculture.

The present study aimed to assess trace metal speciation trends in the water and sediments of Mazowe Dam, a typical sub-tropical dam ecosystem impacted by gold mining and agriculture in Zimbabwe. The elements studied include Al, As, Cd, Co, Cr, Cu, Hg, Fe, Mn, Ni, Pb, and Zn. Elemental speciation in the water column was determined using Visual MINTEQ version 3.1 geochemical computer modelling, while speciation in the sediment phase was determined using sequential extraction techniques. For each element, the data obtained were subjected to extensive correlation analysis to identify intra- and inter-metal species interactions in the water column and the sediment phase, as well as across the water-sediment interface. Possible mechanisms to account for the observed species interactions are proposed. In the water column, Co was predicted to have the highest number of chemical species (9), Cd and Zn (8), Mn and Fe (7), Ni (6), Pb (5), Al and Cu (3), Cr, Hg, and As have the least (2). In the sediment, Al, As, Co, Cr, Cu, Fe, Ni and Fe mainly exist in the residual fraction, while Zn and Mn concentrations in fractions vary per sampling site, with no fraction that is dominant across the sampling sites. Equilibrium exchange reactions across the water-sediment interface were observed e.g., for Cd species /FA2Cd (aq) and Co species /FACo+2G (aq), and /FA2Co (aq). This study is valuable in highlighting trace metal speciation in a tropical dam ecosystem in Africa and adds to the growing knowledge about the behaviour of trace metals in aquatic ecosystems in the region and globally.

INFLUENCE OF GROWING CONDITIONS AND PRIMARY PROCESSING OF TECHNICAL HEMP ON ITS POLYMER COMPOSITION

The article proposes a methodology for experimental monitoring of a set of parameters of the chemical state of a biopolymer system of technical cannabis. Using sequential extraction techniques, the content of alpha-cellulose, pectin substances, hemicelluloses, acid insoluble lignin and other related compounds, including heavy metal ions, extraction substances, silicon oxide, in bast, bonfire and undirected hemp obtained from technical hemp trusts grown in Ivanovo Region, was determined. The influence of the soil factor on the biosynthesis of polymers and related substances of the bast and woody parts of the stem and on the destruction of plant tissues of hemp in the conditions of meadow vegetation has been traced. It has been established that the composition of hemp raw materials is influenced not only by the genetic nature of the plant, but also by the natural conditions of its cultivation and the peculiarities of the action of soil microflora in the processes of primary processing of the stem.

Biogeochemical mechanisms of iron (Fe) and manganese (Mn) in groundwater and soil profiles in the Zhongning section of the Weining Plain (northwest China)

High levels of Iron (Fe) and manganese (Mn) in soils may contribute to secondary contamination of groundwater. However, there is limited understanding of the cycling mechanisms of Fe and Mn in groundwater and soil. This study aimed to investigate the biogeochemical processes constituting the Fe and Mn cycle by combining hydrochemistry, sequential extraction and microbiological techniques. The results indicated a similar vertical distribution pattern of Fe and Mn, with lower levels of the effective form (EFC-Fe/Mn) observed at the oxygenated surface, increasing near the groundwater table and decreasing below it. Generally, there was a tendency for accumulation above the water table, with Mn exhibiting a higher release potential compared to Fe. Iron‑manganese oxides (Ox-Fe/Mn) dominated the effective forms, with Fe and Mn in the soil entering groundwater through the reduction dissolution of Ox-Fe/Mn and the oxidative degradation of organic matter or sulfide (OM-Fe/Mn). Correlation analysis revealed that Fe and Mn tend to accumulate in media with fine particles and high organic carbon (TOC) contents. 16S rRNA sequencing analysis disclosed significant variation in the abundance of microorganisms associated with Fe and Mn transformations among unsaturated zone soils, saturated zone media and groundwater, with Fe/Mn content exerting an influence on microbial communities. Furthermore, functional bacterial identification results from the FAPROTAX database show a higher abundance of iron-oxidizing bacteria (9.3 %) in groundwater, while iron and manganese-reducing bacteria are scarce in both groundwater and soil environments. Finally, a conceptual model of Fe and Mn cycling was constructed, elucidating the biogeochemical processes in groundwater and soil environments. This study provides a new perspective for a deeper understanding of the environmental fate of Fe and Mn, which is crucial for mitigating Fe and Mn pollution in groundwater.

Geochemical fractionation, bioavailability, and ascertaining ecological risk of phosphorus in surface and core sediments of mangroves, western coast of India.

Phosphorus (P), a crucial macronutrient, is essential in the maintenance of ecosystem productivity and the biogeochemical processes of other biogenic substances found in marine settings. The aim of the present study is to quantify the different geochemical fractions, bioavailability, and ecological risk of phosphorus in surface and core sediment of mangroves, Gulf of Kachchh (GoK). To better understand the P dynamics, sequential chemical extraction techniques were used to study sediment P pool distribution such as exchangeable P; Fe-bound P; authigenic P; detrital P; and organic P. The total sedimentary P ranged from 539.51 to 7217.24mg/kg in pre-monsoon and 487.04 to 7180.26mg/kg in post-monsoon, and was primarily composed of inorganic P. Authigenic P and Fe-bound P were the dominant fractions of P in surface and core sediments, exhibiting a significant long-term P reservoir. Sources such as riverine inputs, industrial and sewage discharge, aquaculture farms, and seaport operations all have an impact on the P dynamics in GoK. Furthermore, organic matter, pH, ORP, and diagenetic processes in sedimentary environment have influenced P retention and release. FeBD:Fe-P ratio indicates the presence of Fe matrices, having strong adsorption potential for P, with the availability of a surplus of Fe(III) (oxy)hydroxides serving as a significant P pool, governing the P dynamics. The P enrichment index (PEI) showed that sediments were highly impacted by anthropogenic P and could cause a high ecological risk. Bioavailable phosphorus (BAP) suggests the availability of an ample amount of bioavailable P fractions (average of 49.70% post-monsoon and 44.64% post-monsoon) in surface sediments. Sites 3, 13, 14, 20, 21, and 26 exhibited considerably higher BAP. Core 1 comprised significantly higher BAP (60.52%). Thus, sediments of GoK could act as a source of P to the overlying water if released from sediments.

Ecological implications of boron and sulfur in sediments from a lake in the Nile Delta: Remote sensing, fractionation and ecotoxicity

PurposeThe study aimed to provide an overview of the behavior, fate and ecotoxicity of boron and sulfur in the sediments of Lake Burullus, Egypt, after the degradation of the lake area.Materials and methodsChanges in the studied lake area due to human activities were estimated using Erdas Imagine v14 and ArcGIS. Sequential and non-sequential extraction techniques for boron and sulfur fractionation in sediments were evaluated.Results and discussionA remote-sensing tracking investigation revealed a decrease in area of about 19.4%. Boron geochemical fractions had the order of residual (BF5, 61.48 ± 3.84%) > bound oxide (BF3, 15.47 ± 9.64%) > specifically adsorbed (BF2, 13.34 ± 9.85%) > bound organic (BF4, 9.85 ± 12.40%) > water-soluble and exchangeable (BF1, 2.2 ± 2.66%). Sulfur gave the order of the fractions as residual (SF5, 70.52 ± 16.92%) > phosphate extractable (SF2, 15.47 ± 9.34%) > bound organic (SF4, 7.20 ± 5.35%) > CaCl2 -extractable (SF3, 9.85 ± 12.40%) > water-soluble sulfur (SF1, 1.34 ± 1.52%). A worst-case scenario involving boron and sulfur toxicity values was studied using mixture risk characterization ratios (RCRmix) based on the predicted no effect concentration (PNEC) and sum of toxic units (STU).ConclusionsThe RCRmix and STU of boron showed high long-term risks to aquatic organisms, while sulfur showed high short-term risks. Invertebrates were the most sensitive species to boron and sulfur. This study sheds light on the ecological impact of boron and sulfur in Lake Burullus sediments, highlighting potential risks to aquatic organisms. Further research could focus on developing mitigation strategies to address these concerns.Graphical

Ecological effects of soil physicochemical properties and copper speciation on the microbial properties associated with land use management in cacao production

Soil microbial functioning heavily influenced by heavy metals, is critical to soil health. We investigated the response of soil microbial properties to Cu speciation and soil physicochemical properties at two depths (0–15 and 15–30 cm) in the natural field (NAF), conventional- (CCM), and organic cacao management (OCM) in Ghana. A sequential extraction technique was used to quantify Cu into labile, potentially stable, and stable speciation. Soil physicochemical properties, microbial biomass, basal respiration, enzyme activity, and microbial counts were measured. Microbial- and metabolic quotients (qCO2) were calculated. Cu speciation and microbial properties were largely influenced by land management vis-à-vis soil depth. Except for basal respiration and qCO2 which were dominant at CCM, the other microbial properties increased in NAF > OCM > CCM. CCM had the maximum labile Cu while NAF had the least. Potentially stable and stable Cu were dominant at OCM. Labile Cu negatively affected soil microbial properties except for basal respiration and qCO2, which had a positive effect. However, when labile Cu co-varied with potentially stable and stable Cu or soil organic carbon (SOC), it positively affected microbial properties. The relationship between soil microbial and physicochemical properties was stronger than Cu speciation. The negative effect of labile Cu on microbial biomass, microbial count, and enzyme activity was masked by pH, clay, and SOC. Overall, Cu speciation and soil physicochemical parameters jointly altered microbial properties which varied with the land management systems. This study provides novel insight into the microbial properties in cacao soils associated with land management systems.

Fractionation and Lability of Phosphorus Species in Cottonseed Meal-Derived Biochars as Influenced by Pyrolysis Temperature.

Defatted cottonseed meal (CSM), the residue of cottonseeds after oil extraction, is a major byproduct of the cotton industry. Converting CSM to biochar and utilizing the goods in agricultural and environmental applications may be a value-added, sustainable approach to recycling this byproduct. In this study, raw CSM was transformed into biochar via complete batch slow pyrolysis at 300, 350, 400, 450, 500, 550, and 600 °C. Thermochemical transformation of phosphorus (P) in CSM during pyrolysis was explored. Fractionation, lability, and potential bioavailability of total P (TP) in CSM-derived biochars were evaluated using sequential and batch chemical extraction techniques. The recovery of feed P in biochar was nearly 100% at ≤550 °C and was reduced to <88% at 600 °C. During pyrolysis, the organic P (OP) molecules predominant in CSM were transformed into inorganic P (IP) forms, first to polyphosphates and subsequently to orthophosphates as promoted by a higher pyrolysis temperature. Conversion to biochar greatly reduced the mobility, lability, and bioavailability of TP in CSM. The biochar TP consisted of 9.3-17.9% of readily labile (water-extractable) P, 10.3-24.1% of generally labile (sequentially NaHCO3-extractable) P, 0.5-2.8% of moderately labile (sequentially NaOH-extractable) P, 17.0-53.8% of low labile (sequentially HCl-extractable) P, and 17.8-47.5% of residual (unextractable) P. Mehlich-3 and 1 M HCl were effective batch extraction reagents for estimating the "readily to mid-term" available and the "overall" available P pools of CSM-derived biochars, respectively. The biochar generated at 450 °C exhibited the lowest proportions of readily labile P and residual P compounds, suggesting 450 °C as the optimal pyrolysis temperature to convert CSM to biochar with maximal P bioavailability and minimal runoff risk.

Extraction and characterization of bioactive compounds from brown seaweed (Undaria pinnatifida) sporophyll using two sequential green extraction techniques

This work aims to prepare the functional extracts from Undaria pinnatifida sporophyll using a consecutive green extraction methodology known as supercritical carbon dioxide (SC-CO2) along with subcritical water extraction (SWE). For the SC-CO2 extraction, a variable pressure from 20 to 30 MPa was applied at a constant temperature of 50 °C and compared with hexane extraction. The amount of fucoxanthin and beta-carotene was quantified from the extracted oils along with fatty acids. The yield of the fucoxanthin ranged from 12.38 ± 0.10 mg/g to 20.22 ± 0.14 mg/g and beta-carotene was 0.57 ± 0.01 mg/g to 0.99 mg/g of extracted oil. Arachidonic and eicosapentaenoic acid (EPA) considered as health-beneficial PUFAs were highly abundant in the U. pinnatifida sporophyll oils. A variable temperature range from 120 °C to 220 °C was used for SWE of de-oiled biomass. For comparison, hot water extraction, and ethanol extraction were used as controls. Physicochemical compositional parameters (total sugar, reducing sugar, protein, phenolic content, and flavonoid content), antioxidant activities, and antihypertensive and antibacterial activities of the hydrolysates were evaluated. The maximum content of total sugar, reducing sugar, total protein, phenolics, and flavonoids were 165.03 ± 0.40 mg glucose/g, 53.15 ± 0.50 mg glucose/g, 113.62 ± 0.66 mg BSA/g, 38.04 ± 0.18 mg PE/g, and 10.34 ± 0.24 mg PE/g, respectively, at SWE temperatures of 140 °C, 180 °C, 180 °C, and 200 °C. Antihypertensive activity exhibited its highest value at 180 °C. The antioxidant activity of ABTS+, DPPH, and antimicrobial activity was highest at 200 °C. Bioactive compounds and the functional properties of the extracts using SC-CO2 and SWE from U. pinnatifida sporophyll were revealed for the first time in the study. The authors believe the findings of this research will bring new insight to the scientists for the industrial application of U. pinnatifida sporophyll.

Physiological mechanism of action and partial separation of herbicide–active compounds from the Diaporthe sp. extract on Amaranthus tricolor L.

Thirteen fungi that produce compounds with herbicidal activities were isolated, identified, and extracted under the assumption that the mechanism of action occurs during seed exposure to the extract. The extracts from all the fungal strains considerably decreased the growth parameters of Amaranthus tricolor L. The EC010 strain extracts showed the greatest effect. Through ITS region gene sequencing methods, the isolated EC010 was identified as a genus of Diaporthe. The results showed a significant (p < 0.05) inhibitory effect of 91.25% on germination and a decrease in shoot and root length by 91.28% and 95.30%, respectively. The mycelium of Diaporthe sp. was extracted using sequential extraction techniques for the partial separation of the herbicidal fraction. According to the bioassay activities, the EtOAc fraction showed the highest inhibitory activity. The osmotic stress of the A. tricolor seeds was studied. Although the extract increased the accumulation of proline and soluble protein, the treated seeds showed lower imbibition. While the activity of α-amylase was dramatically decreased after treatment. A cytogenetic assay in the treated Allium cepa L. root revealed a decrease in the mitotic index, an altered mitotic phase index, and a promotion of mitotic abnormalities. Accordingly, the Diaporthe sp. may serve as a potential herbicidal compound resource.

Elemental composition and speciation trends in Upper Mazowe River, a typical sub-tropical river ecosystem impacted by gold mining and agriculture in Zimbabwe

This study was carried on Upper Mazowe River in Zimbabwe which connects with Luenha River in Mozambique, which is a tributary of the Zambezi River. Zambezi River is the fourth longest river in Africa flowing into the Indian Ocean, which makes the study of regional and global interest. Heavy metal aqueous speciation has received relatively little attention compared to sediment speciation in the Upper Mazowe River, and yet heavy metal behaviour and fate in surface waters are greatly affected by the heavy metal chemical form in solution. The aim of the study was to determine the elemental composition and speciation of heavy metal(oid)s. This study focused on water and sediment speciation of Al, As, Cu, Hg, Mn, Fe, and Pb using Visual MINTEQ Version 3.1 computer modelling and sequential extraction techniques. Twenty-eight different water column elemental species, comprising 3, 2, 3, 1, 7, 7 and 5 species each, and 35 sediment phase elemental species, comprising 6, 6, 6, 2, 6, 5, and 4 species each for Al, As, Cu, Hg, Mn, Fe, and Pb respectively, were identified. Of note is the fact that Hg, mainly derived from artisanal gold mining activities, exists entirely as the fulvic acid complex, FA2Hg (aq), and As exists as H3AsO3 and H2AsO3− in the water phase. Exchange equilibrium reactions across the water-sediment interface were observed for Mn2+, Fe2+, Cu2+, and Pb2+. Reactions leading to the formation of the species were identified. Species interactions within the water column and sediment phase and species interrelationships with physicochemical parameters are discussed. H3AsO3 formation is predicted to be temperature sensitive and the aluminium hydroxide-fulvic acid complex /FA2(AlOH) (aq) is oxic favourable.

Seasonal variation regulate the endogenous phosphorus release in sediments of Shijiuhu Lake via water-level fluctuation

Freshwater lakes undergo substantial alterations of the phosphorus (P) cycle in the water-sediment ecosystem due to thermal change. The impact process of seasonal fluctuation on P cycling in sediments has been scarcely investigated. P forms in sediments from a freshwater lake in China were analyzed using sequential extraction technique. The vertical distribution of soluble reactive P (SRP), Fe2+, and S2− in the interstitial water was measured using diffusion gradient technique (DGT). Fick's Law and DIFS model were used to obtain the diffusion fluxes of SRP and the kinetic parameters in the water-sediment system. The results showed that total P (TP) concentrations in the solid sediments varied from 207.5, 266.6 and 130.3 mg/kg to 614.7, 1053.1, and 687.6 mg/kg in winter, spring, and summer, respectively. The concentrations of individual P forms in spring were higher than those in other seasons, with Fe-bound P (Fe–P) concentration being the highest across all seasons. Notably, significant variations of SRP concentrations were found in the interstitial water between sedimentary depths of approximately 2 cm and 6 cm, particularly in the summer. Furthermore, higher diffusion fluxes of SRP through the interface were found in summer. A stable anaerobic environment failed to develop in spring with high water level, preventing the desorption of solid Fe–P and diffusion of Fe2+ into the water due to the afflux and deposition of P-containing particulate into deeper sediment layers along with organic material. Under extreme high-temperature in summer, decreased rainfall and rising temperatures boosted the activity of aquatic organisms in the water, thereby reducing P fixation by sediments and leading to P release. This process increased the risk of P excess and potential eutrophication in the water. Generally, clarifying the resupplying processes of endogenous P in sediment systems experiencing seasonal variations is critical for eutrophication management of lakes.

Chemical fractionations and mobilization potentials for some trace metals in reef sediments and corals of Qeshm Island, the Persian Gulf

The bioavailability of trace metals in coral skeletons and sediment samples from Larak and Qeshm Islands in the Persian Gulf was investigated using the sequential extraction technique (SET), bioaccumulation measurement and risk assessment indices. The fractionation results and risk assessment indices indicated that Pb at the Qeshm Station and Cd and Zn at both Stations could have adverse biological effects due to high bioavailability. The bioaccumulation rate of metals in different reef species and at different Stations was not significant. The studied coral reefs showed a high tendency for Pb adsorption, so they could be an efficient bioindicator of Pb contamination. Statistical analysis showed that Pb and Zn were mainly from anthropogenic contamination sources, while the other metals were primarily of natural origin. The results indicated that further studies are needed to make a realistic assessment of the discharge of trace metals to the Persian Gulf.

Skrining Fitokimia Hasil Ekstraksi Bertingkat Daun Jengkol (Archidendron jiringa) dan Aplikasinya Sebagai Zat Antijamur

Phytochemical screening and antifungal activity test of jengkol leaf (Archidendron jiringa) extract have been carried out. The purpose of this research is determine secondary metabolite content and antifungal activities of jengkol leaf extract. Extraction of jengkol leaf was conducted with sequential extraction technique with various solvent such as hexane, ethyl acetate and methanol respectively. FTIR characterization of jengkol leaf extract show the presence of O-H, C-H C-O and C=O groups. Based on phytochemical sceening test, jengkol leaf extract contains phenolic, flavonoid, tannin, sterol, and alkaloid compound. Antifungal test was investigated on Candida albicans by disc diffusion methods. Jengkol leaf extract that was obtained from methanol extraction show inhibiton zone to Candida albicans of (1,42 ± 0,16) mm, while extraction with ethyl acetate and hexane aren’t show inhibition zone. Antifungal test result showed that jengkol leaf extract has potential as antifungal agent

Effect of iron cyclic transformation on the natural purification of antimony in contaminated reservoirs of mines

To further understand the purification mechanism of antimony (Sb) in reservoirs, samples of stratified water and bottom interface sediment were collected in this study. The cross-flow ultrafiltration technique was used to separate the truly dissolved (<1 kDa) and colloidal (1 kDa–0.45 μm) phases of water, and two modified sequential extraction techniques were used to determine the Sb and Fe mineral forms in sediment, respectively. The results showed that the total Sb concentration could decrease from 142.2 μg/L in surface water to 98.6 μg/L at 16 m; this was contributed to by the removal of truly dissolved Sb. In comparison to particulate Sb (>0.45 μm), the formation of colloidal Sb played a greater role in the purification process. There was a positive correlation between Sb and Fe in the colloidal phase (r = 0.45, P < 0.05). The generation of colloidal Fe could be promoted by higher temperatures, pH values, DO, and DOC in the upper layer (0–5 m). However, the complexation of DOC with colloidal Fe inhibited the adsorption of truly dissolved Sb. After entering the sediment, the secondary release of Sb could not increase the Sb concentration in the lower layer obviously, while the supplementation of Fe(III) could further enhance Sb natural purification.

Optimization of the Two‐ and Three‐Dimensional Characterization of Rare Earth‐Traced Deoxidation Products

Tracing by means of the light rare earths (REs), particularly La and Ce, is a state‐of‐the‐art method used to track deoxidation products during the steelmaking process. Traced heterogeneous multiphase inclusions are analyzed using scanning electron microscopy with energy‐dispersive spectroscopy (SEM/EDS) to perform a 2D characterization. The sequential chemical extraction technique is implemented for a 3D investigation to determine traced particles’ actual sizes and shapes. The automated SEM/EDS measurement must be optimized since RE oxides appear brighter in the backscattered electron images due to their high atomic numbers. Therefore, two grayscales are implemented for the detection of RE‐containing multiphase inclusions. Within this technique, individual RE‐traced heterogeneous nonmetallic inclusions (NMIs) are counted as separate particles. Thus, the measured NMIs must be recombined, which is achieved using a self‐developed MATLAB tool. The extracted particles are also analyzed by automated and manual SEM/EDS measurements to determine the 3D morphologies and sizes of traced NMIs.

Improved phosphorus availability and reduced degree of phosphorus saturation by biochar-blended organic fertilizer addition to agricultural field soils

Phosphorus (P) availability and loss risk are linked to P species; however, their alternations in the soil amended with biochar-blended organic fertilizer is not well known, particularly under contrasting soil properties and land management. In this study, the variance of soil P species extracted by sequential chemical extraction (SCE) and 31P NMR techniques, as well as the degree of P saturation (DPS), were investigated throughout three paddy and three vegetable fields. These fields were amended with three different fertilizers at the same P application rate: chemical fertilizer (CF), organic fertilizer substitution (sheep manure/biogas slurry, SM/BS), and biochar-blended organic fertilizer substitution (BSM/BBS). Results showed that the BSM/BBS and SM increased the total P contents by 7.5% and 5.9% (TP) and available P contents by 30.1% and 19.2% (AP), but decreased the DPS values by 19.4% and 11.7%, compared to the CF treatment. Yet, the BS decreased the TP and AP contents but increased the DPS values across the experimental sites. In the BSM/BBS amended soils, high AP contents were due to the increased inorganic P (NaHCO3-Pi), while the increased organic P (monoester and DNA) induced low DPS values and reduced soil P loss risk. Our study highlights that biochar-blended organic fertilizer is an effective agronomic way for improving P availability and decreasing P loss risk via the alteration of soil P species.

SPATIAL AND TEMPORAL VARIATION OF IN-VITRO BIOACCESSIBILITY OF CHROMIUM IN PLAYGROUND SOILS OF ANCIENT BELL METAL INDUSTRIAL TOWN, KHAGRA, WEST BENGAL

Present study was designed to study the seasonal variation of Chromium (Cr) in playground soil of Khagra City located in West Bengal, India from 16 different playgrounds. Sequential extraction techniques had been carried out to evaluate the relative dispersal of Cr in exchangeable, carbonate, Fe-Mn oxide, and organic bound as well as residual fractions. The −1 Pseudo total concentration of Cr had its average value of 19.85±7.94 mg kg in pre-monsoon and −1 in case of post-monsoon an average of 115.17±192.17 mg kg . Sequential extraction was performed to evaluate the bioavailable fraction. Cr was mostly associated with residual phase (F5). Mean mobility factor (MF) for Cr in playground soil of Khagra was only 5.02 %. Geo-chemical indices such as Enrichment factor (EF), Geo-accumulation index (I ) and Contamination factor geo (CF), Ecological risk (ER) indicated very low pollution levels. Bioaccessible-Cr was most 2 2 significantly correlated (R ≥ 0.85) in pre-monsoon and (R ≥ 0.98) post-monsoon indicated, when the total amount of Cr is increased leading to increase in bioaccessible fraction.

Co-utilization of zinc contaminated soil and red mud for high-strength ceramsite: Preparation, zinc immobilization mechanism and environmental safety risks

In this research, high strength ceramsite was sintered by zinc contaminated soil and red mud. In addition, the influence of sintering temperature and red mud addition on ceramsite properties and Zn immobilization were investigated, and the Zn immobilization mechanisms were determined. The X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM-EDS), and BCR sequential extraction technique were used to determine the crystal phases, microstructures, and Zn immobilization. Under the optimum synthesis conditions (sintering temperature of 1150 °C and the red mud addition of 5%), the sintered ceramsite exhibited a Zn loss rate of 10.31%, Zn leaching concentration of 0.13 mg/L (performed by rotating vibration device), bulk density of 1052.6 kg/m3, 1 h water absorption of 1.06%, and cylindrical compressive strength of 27.06 MPa, implying that the ceramsite obtained under this conditions not only meets the Chinese National Standards and has no environmental risk. High temperature and the addition of red mud were beneficial to the immobilization of Zn in ceramsite. The main immobilization mechanism of Zn in ceramsite was the formation of ZnFexAl2−xO4 spinel and the encapsulation of glass phase. Thus, Zn can be immobilized effectively by ceramsite prepared from zinc contaminated soil and red mud at high temperature.