Residual Fraction Research Articles

Thermally Conductive Shape-Stabilized Phase Change Materials Enabled by Paraffin Wax and Nanoporous Structural Expanded Graphite

Paraffin wax (PW) has significant potential for spacecraft thermal management, but low thermal conductivity and leakage issues make it no longer sufficient for the requirements of evolving spacecraft thermal control systems. Although free-state expanded graphite (EG) as a thermal conductivity enhancer can ameliorate the above problems, it remains challenging to achieve higher thermal conductivity (K) (>8 W/(m·K)) at filler contents below 10 wt.% and to mitigate the leakage problem. Two preparations of thermally conductive shape-stabilized PW/EG composites, using the pressure-induced method and prefabricated skeleton method, were designed in this paper. The expanded graphite formed a nanoscale porous structure by different methods, which enhanced the capillary action between the graphite flake layers, improved the adsorption and encapsulation of EG, and alleviated the leakage problem. The thermal conductivity and the latent heat of the phase-change materials (PCM) prepared by the two methods mentioned above are 9.99 W/(m·K), 10.70 W/(m·K) and 240.06 J/g, 231.67 J/g, respectively, at EG loading by 10 wt.%, and the residual mass fraction was greater than 99% after 50 cycles of high and low temperature. In addition, due to the excellent thermal management capability of PW/EG, the operating temperature of electronic components can be stably maintained at 68–71 °C for about 15 min and the peak temperature can be reduced by at least 23 °C when the heating power of the electronic components is 10 w. These provide novel and cost-effective methods to further improve the management capability of spacecraft thermal control systems.

Environmental and human health risk assessment of potentially toxic elements in rehabilitating iron mine lands in the Brazilian Amazon.

Waste pile substrates from Fe mining may carry potentially toxic elements (PTE). Rehabilitation efforts must maintain soil vegetation cover effectively, avoiding the dispersion of particulate matter and reducing the risk to the environment and human health. Therefore, this study aims to evaluate the pseudo-total and extractable contents, perform chemical fractionation, and assess the bioaccessibility and risk of PTE in waste piles of Fe mining in the Eastern Amazon. Soils were sampled from waste piles in different stages of environmental rehabilitation and from non-rehabilitated and native forest areas. The waste materials exhibit mean pseudo-total concentrations of Zn, Ni, Cr, and Cu that exceed the Brazilian soil quality threshold. However, they do not surpass reference values for human health safety. In addition, these elements are predominantly associated with the residual fraction, suggesting low availability. Among the 11 PTE evaluated, only Al, Cu, Fe, Mn, and Zn presented concentrations that were bioaccessible to the gastrointestinal tract. At the same time, Al, Fe, and Mn showed lung bioaccessibility. Soil properties limiting PTE extractability and bioaccessibility include pH and base saturation. Considering only elements above threshold levels, no environmental risk was observed, and the human health risk was considered insignificant for adult oral and inhalation exposure routes. Finally, the results show that high pseudo-total PTE contents in the analyzed Fe waste piles do not necessarily indicate high risks. However, substrate properties should be monitored over time to better understand their potential impacts and the main factors influencing their bioavailability.

Exploring the impact of fulvic acid and humic acid on heavy metal availability to alfalfa in molybdenum contaminated soil

Humic substances, such as Fulvic acid (FA) and humic acid (HA), are widely used for the remediation of heavy metal-contaminated soils due to their ability to enhance metal mobility and facilitate plant uptake. In this study, we conducted a pot experiment with alfalfa to investigate the effects of FA and HA amendments on the mobility of molybdenum (Mo) in the soil, its uptake by alfalfa plants, and subsequent changes in the microbial community. The results demonstrated that both FA and HA influence Mo accumulation in the soil and plants. Specifically, HA treatment increased Mo concentrations in alfalfa shoots and roots by 1.08–1.19 times and 1.19–2.43 times, respectively, compared to the control. In contrast, FA enhanced Mo concentrations in alfalfa roots (1.05–1.58 times) but reduced Mo levels in the shoots (0.78–0.85 times). Furthermore, the addition of FA and HA altered the chemical speciation of Mo in the soil, promoting the conversion of reducible and oxidizable fraction to more exchangeable and residual fraction. As a result, the proportion of non-residual Mo fractions (exchangeable, reducible, and oxidizable) decreased from 87.48% to 80.30-87.35%, while residual fractions increased from 12.52% to 12.65–19.70%. Additionally, the structure of the soil bacterial community was primarily influenced by changes in soil properties such as cation exchange capacity, available phosphorus, and ammonium nitrogen levels. This finding highlight the potential of FA and HA to enhance Mo availability, uptake, and translocation in alfalfa, suggesting that their application could be an effective strategy for phytoremediation of Mo-contaminated soils, particularly when alfalfa is used as a hyperaccumulator.

Toward Global Sediment Management: Lessons Learned From a Multidimensional Risk Assessment

ABSTRACTSediment from the Serbian Great Bačka Canal (GBC), which has long been classified as toxic waste due to high pollutant concentrations, exemplifies the sediment management challenges in Europe, where regulations vary by country. Serbian legislation primarily focuses on total metal concentrations relative to prescribed limits. Our study addresses this limitation by using an integrated approach to assess sediment pollution's detrimental effects at the ecosystem level. This approach is particularly relevant for the GBC, an environmental hotspot historically impacted by severe pollution from untreated industrial wastewater and population growth. Although previous research on the GBC has predominantly focused on chemical analyses, often overlooking broader environmental and health impacts, our study aims to evaluate whether ecotoxicological tests provide a more comprehensive assessment of sediment quality compared to traditional methods. Although only copper concentrations surpassed national limits, multiple metals and polycyclic aromatic hydrocarbons (PAHs) exceeded international sediment quality guidelines (SQGs). Sequential extraction revealed that 50% of copper was immobilized in the residual fraction, and ecotoxicological tests with Myriophyllum aquaticum indicated potential toxicity. Human health risk assessments showed a low risk of carcinogenic effects from PAHs, but a higher risk associated with zinc and copper. These findings highlight the urgent need for pollution reduction and ecological restoration in the GBC and similar river systems.

Molybdenum, lead and zinc mobility potential in agricultural environments: a case study of the Kočani field, North Macedonia

The research focuses on the assessment of potential toxic elements (PTEs) contamination of the soils of the Kočani field (North Macedonia) due to the surrounding past and current polymetallic mining activities. The Zletovska River drains the untreated wastewater from the Pb-Zn mine in the Zletovo-Kratovo region and is unfortunately used to irrigate the surrounding rice fields. Elevated levels of molybdenum (Mo) and especially lead (Pb) and zinc (Zn) were found in the soil samples from the rice fields near the Zletovska River (in the western part of the Kočani field), which are well above the limit and critical emission values for PTEs content in soils. In addition, Mo was consistently bound to water soluble, exchangeable and oxidizable fractions in all samples, while reducible and residual fractions were predominated by Pb and Zn. According to the sum of the water-soluble and exchangeable fractions, the mobility and environmental bioavailability potential of the investigated PTEs in the soil-plant system decreased in the following order: Mo > Pb > Zn. It is therefore very important to emphasize that when assessing the environmental impact of PTEs on the respective surroundings, not only the commonly considered trace and minor PTEs (such as Pb and Zn) that occur in geological materials should be taken into account, but also in lower contents (such as Mo). The translocation of PTEs within the ecosystem does not depend on their total content in the primary geological materials, but on their individual mobility and binding capacity.

Synergistic Effects of Unmodified Tea Leaves and Tea Biochar Application on Remediation of Cr-Contaminated Soil

Hexavalent chromium (Cr(VI)) contamination in soil presents significant risks due to its high toxicity to both the environment and human health. Renewable, low-cost natural materials offer promising solutions for Cr(VI) reduction and soil remediation. However, the effects of unmodified tea leaves and tea-derived biochar on chromium-contaminated soils remain inadequately understood. In this study, tea tree pruning waste was converted into biochar at various temperatures, and the impacts of both unmodified tea leaves and tea biochar on soil Cr(VI) content, chromium fractionation, and soil biochemical properties were assessed using a soil incubation experiment. The results showed that the combined treatment of tea and tea biochar produced at 500 °C reduced Cr(VI) content by up to 49.30% compared to the control. Chromium fractionation analysis revealed a significant increase in the residual chromium fraction, accounting for 32.97% of total chromium, substantially reducing its bioavailability and mobility. Soil properties were markedly improved, with notable increases in pH (14.89%), cation exchange capacity (CEC; up to 100.24%), and organic matter content (up to 167.12%) under the combined treatments. Correlation analysis confirmed that Cr(VI) content reductions were positively correlated with increases in pH, nutrient retention, and enzyme activities, highlighting their role in chromium stabilization. This study underscores the synergistic potential of unmodified tea leaves and tea biochar as an innovative, eco-friendly strategy for Cr(VI) remediation, enhancing both soil quality and heavy metal stabilization.

Comparative mineralogical characterization of REEs ore samples from the Mushgai Khudag and Lugiin Gol deposits, Mongolia

Mongolia, situated in the Central Asian orogenic belt, is characterized by geology that is highly conducive to the abundance of mineral resources, including significant rare earth elements (REEs) reserves. However, limited knowledge of the mineralogy of its deposits has hindered the development of efficient REEs extraction methods. This study presents a detailed investigation of the mineralogical characteristics of Mongolian ores and analyzes their compositions, mineral associations, liberation, and REEs concentrations via advanced analytical techniques, including the TESCAN Integrated Mineral Analyzer (TIMA). Additionally, the BCR sequential extraction method was employed to determine the binding and leaching properties of REEs. Our results revealed that the two ore samples were predominantly rich in light rare earth elements (LREEs), with REE-bearing minerals closely associated with gangue minerals such as calcite, albite, and quartz, leading to poor liberation. The extraction data indicated that >85 % of the REEs in the Mushgai Khudag deposit were retained in the residual fraction, whereas in the Lugiin Gol deposit, the majority of the REEs were associated with the reducible fraction. These findings underscore the challenges associated with extracting REEs from Mongolian deposits, which demand stringent conditions for effective recovery. This research contributes valuable insights into the complex mineralogy of Mongolian REEs deposits, offering a foundation for future advancements in REE extraction technologies.

Integrating environmental, ecological and human health risk assessments for heavy metals in tropical ultramafic soils

Ultramafic soils are a natural source of metals such as Ni, Co and Cr that can pose ecosystem and human risks. Here, we assessed the environmental, ecological, and human health (carcinogenic and non-carcinogenic) risks from exposure to ultramafic soils through an integrated approach using petrographic and soil mineralogical assessments together with total, available, bioaccessible, and soil fractions analyses of Ni, Co and Cr in ultramafic soils from Brazil. The metal concentrations were similar or up to 5-fold higher for Ni than other studies worldwide in ultramafic soils. Soil sequential extraction showed Co and Ni predominantly bound to Fe and Mn oxides, while Cr was mostly in residual fractions. Medium environmental risks were found for Ni (RAC = 13.0), but no environmental risks were associated with Co and Cr in soils. Ecological risks were high (PERI = 522.8) and significantly high (PERI = 1759.9). Low metal bioaccessibility led to acceptable carcinogenic and non-carcinogenic risks for all routes of human exposure to soil, but consuming vegetables grown in these soils posed unacceptable cancer risks (> 10−3). Our results reinforce the need to monitor ultramafic areas regarding the mobility and availability of metals in the soil to ensure food safety and human health.

Migration and morphological transformation of Mn2+ and its effect on microbial community in the A2O process

Manganese ion (Mn2+) was generated from metallurgical, steel making and chemical industries. It could affect microbial activity and community structure after entering sewage treatment plant. The effect of Mn2+ on the pollutant removal, metal distribution patterns and composition of microbial communities were investigated in a an anaerobic/anoxic/oxic (A2O) process. The results showed that when Mn2+ concentration was 5 mg/L, the efficiencies for the removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) attained remarkable levels of 96%, 93%, and 99%, respectively. In the sludge, the distribution pattern of Mn2+ concentration was tightly bound extracellular polymeric substances (TB-EPS) > supernatant > loosely bound EPS (LB-EPS) > soluble microbial products (SMP). Mn2+ was found to enrich and accumulate in the microorganism cells. In addition, Mn2+ was mainly found in residual fractions and reducible fractions of pellet that manganese was present. The pellet was discovered to contain a substantial quantity of manganese, which was present in various oxidation states, including Mn4+, Mn3+ and Mn2+. The escalating levels of Mn2+ led to a reduction in the richness and diversity of microbial communities inhabiting various regions of the A2O reactor. Nonetheless, the uniformity experienced only subtle alterations. Proteobacteria and Bacteroidetes emerged as the leading phyla within the microbial ecosystem, experiencing a steady rise in their respective proportions. The dominant bacterial groups, Azospira and Dechromonas, experienced an incremental increase in their relative prevalence, which played a constructive role in the process of pollutant removal.

Efficient recovery of heavy metals and selenium from wastewater using granular sludge: The crucial role of glutathione (GSH)

Microbial technology offers an effective method for treating heavy metals and selenium (Se) in wastewater, yet the recovery of these valuable elements is often overlooked. This study introduces a glutathione (GSH)-enhanced granular sludge technology for the removal and recovery of heavy metals and Se from wastewater. Using the new technology, the removal rates of copper (Cu), cadmium (Cd), and Se from wastewater reached 99.4–99.99%, while the recovery rates reached 73.2–87.9%. Both long-term reactor operation and short-term stimulation experiments indicated that GSH substantially increased the residual fraction of Cu, Cd, and Se in the sludge. This residual fraction was identified as metal selenides (MSe), composed of Cu1.08Se (75.4 ± 1.8%) and CdSe (15.4 ± 1.0%). The increased abundance and significant upregulation of GSH-related genes, including gshA, gshB, and gor, as well as the indispensable roles of GSH, glutathione reductase (GorA), and NADPH in the in vitro synthesis of MSe, demonstrated that the GSH-mediated Painter-type reaction was the primary pathway for MSe synthesis in the sludge. The biosynthesized MSe was efficiently extracted and recovered from the final sludge, and the extract showed high catalytic activity in pollutant degradation. Given the widespread presence of GSH in diverse microorganisms, the GSH-mediated mechanism for MSe synthesis is likely to occur in various environments contaminated with heavy metals and Se.

ANTI-INFLAMMATORY ACTIVITY OF ETHANOLIC EXTRACT OF TARO LEAVES (Colocasia esculenta (L.) Schott) AND ITS FRACTIONS IN RATS USING EGG WHITE-INDUCED MODEL

Taro plant (Colocasia esculenta (L.) Schott) is empirically known to have anti-inflammatory activity. Taro leaves contain secondary metabolites such as alkaloids, saponins, tannins, flavonoids, and polyphenols. This study aimed to prove the anti-inflammatory effectiveness of ethanol extract of taro leaves (EETL), ethyl acetate fraction (EAFTL), and residual fraction (RFTL) in rats induced by 1% egg white solution, and to identify the chemical compound groups contained in EETL and its fractions. Thirty-two rats were divided into eight groups, namely group I as a negative control (CMC-Na 0.5%), group II as a positive control (Diclofenac sodium 4.5 mg/kgBW), groups III-IV were administered EETL 100 and 200 mg/kgBW, groups V-VI were administered EAFTL 100 and 200 mg/kgBW, and groups VII-VIII were administered RFTL 100 and 200 mg/kgBW. The animal models were induced with 0.1 mL of 1% egg white solution subplantar 1 hour after oral treatment. The volume of rat leg edema was measured every 1 hour for six consecutive hours. This research shows that EETL 100 mg/kgBW and RFTL doses of 100 and 200 mg/kgBW have an anti-inflammatory effect with a percent inhibitory power of >50%. Phytochemical screening showed that EETL contains alkaloids, saponins, tannins, and phenolics. EAFTL contains tannins and phenolics, whereas RFTL contains saponins, tannins, and phenolics. Keywords: Taro leaves, antiinflammatory, egg white solution, fractionation

Genotoxic and Anti-Genotoxic Assessments of Fermented Houttuynia cordata Thunb. Leaf Ethanolic Extract and Its Anti-Cancer Effect in a Dual-Organ Carcinogenesis Model of Colon and Liver in Rats.

The incidence of multiple-organ cancers has recently increased due to simultaneous exposure to various environmental carcinogens. Houttuynia cordata Thunb. (H. cordata) is recognized for its many health benefits, including its anti-cancer properties. The fermentation of its leaves has been shown to significantly enhance the bioflavonoid content and its bioactivities. This study aimed to evaluate the effectiveness of fermented H.cordata leaf (FHCL) extracts against combined carcinogens and investigate the underlying mechanisms. The crude ethanolic extract of FHCL was partitioned to obtain hexane- (HEX), dichloromethane- (DCM), ethyl acetate- (ETAC), butanol- (nBA), and residue fractions. The crude ethanolic extract (200-250 μg/mL) and the DCM fraction (50 μg/mL) significantly reduced NO production in RAW264.7 macrophages. In addition, the crude extract and the DCM and ETAC fractions showed anti-genotoxicity against aflatoxin B1 and 2-amino-3,4-dimethylimidazo [4,5-f]quinoline (MeIQ) in Salmonella typhimurium assays (S9+). Despite demonstrating genotoxicity in the Salmonella mutation assay (with and without S9 activation), oral administration of the crude extract at 500 mg/kg of body weight (bw) for 40 days in rats did not induce micronucleated hepatocytes, indicating that the extract is non-genotoxic in vivo. Moreover, the crude extract significantly decreased Phase I but increased Phase II xenobiotic-metabolizing enzyme activities in the rats. Next, the anti-cancer effects of FHCL were evaluated in a dual-organ carcinogenesis model of the colon and liver in rats induced by 1,2-dimethylhydrazine (DMH) and diethylnitrosamine (DEN), respectively. The crude extract significantly reduced not only the number and size of glutathione S-transferase placental form positive foci in the liver (at doses of 100 and 500 mg/kg bw) but also the number of aberrant crypt foci in rat colons (at 500 mg/kg bw). Furthermore, FHCL significantly reduced the expression of proliferating cell nuclear antigen (PCNA) in the colon (at 100 and 500 mg/kg bw) and liver (at 500 mg/kg bw) of the treated rats. In conclusion, FHCL exhibits significant preventive properties against colon and liver cancers in this dual-organ carcinogenesis model. Its mechanisms of action may involve anti-inflammatory effects, the prevention of genotoxicity, the modulation of xenobiotic-metabolizing enzymes, and the inhibition of cancer cell proliferation. These findings support the use of FHCL as a natural supplement for preventing cancer.

Screening, Isolation and Hydrocarbon Degradation Characteristics of Yeasts from Mangrove Sediments of Kerala

The aim of the present work was to examine the hydrocarbon degradation potential of yeasts isolated from the mangrove sediments. Mangrove sediments around the world were considered to be heavily polluted with oil contaminants and the microbes dwelling in them were believed to be highly active in metabolizing and detoxifying the oil fractions. In the present study, 70 yeast isolates were screened for their lipolytic activity qualitatively and 35 of them which showed comparatively higher lipolysis were tested for their crude oil degradation ability. Screening of hydro-carbon utilizing isolates was performed on Bushnell Haas agar media overlaid with 1% crude oil and the appearance of colonies were considered a positive. Three isolates were selected based on this and were sequenced using ITS gene of the 18S region of the rDNA and identified to be Candida tropicalis. The extent of crude oil degradation was assessed by growing the isolates in basal medium supplemented with heavy crude oil as the carbon source for 21 days. The residual crude oil fractions were then analyzed using GC-MS to quantitatively measure the degradation potential of each isolate. Our results showed that the yeast strains under study could actively metabolize the crude oil including the higher chain fractions which make them efficient hydrocarbon degraders that can be used in the bioremediation processes.

Immobilization of Heavy Metals in Biochar Derived from Biosolids: Effect of Temperature and Carrier Gas

Slow pyrolysis was carried out in biosolids under three different temperatures (400, 500 and 600 °C) and two different carrier gases (CO2 and N2) on a fluidized bed reactor. The total concentration, chemical fractionation, and plant availability of the heavy metals in biochar were assessed by standard methods. The total concentration of Fe, Zn, Cu, Mn, Cr, Ni and Pb increased with the conversion of biosolids to biochar and with increasing pyrolysis temperature. The community’s Bureau of Reference (BCR) sequential extraction identified the migration of metals from toxic and bioavailable to potentially stable available or non-available forms at higher pyrolysis temperatures. Diethylenetriamine penta-acetic acid (DTPA)-extractable metals (Cu, Zn, Cd, Cu, Fe and Pb) were significantly lower in biochar compared to biosolids. By replacing N2 with CO2, the total metal concentration of heavy metals was significantly different for Mn, Ni, Cd, Pb and As. There were larger amounts of metals in the residual and oxidizable fractions compared to when N2 was used as a carrier gas. Consequently, the biochar produced at higher temperatures (500 and 600 °C) in the N2 environment exhibited lower potential ecological risks than in CO2 environments (69.94 and 52.16, respectively, compared to values from 75.95 to 151.38 for biochars prepared in N2). Overall, the results suggest that the higher temperature biochar can support obtaining environmentally safe biochar and can be effective in attenuating the ecological risks of biosolids.

Exogenous sodium nitroprusside exhibits multiple positive roles in alleviating cadmium toxicity in tobacco (Nicotiana tabacum L.)

As a donor of the gaseous signaling molecule nitric oxide (NO), sodium nitroprusside (SNP) has been shown to play a positive role in enhancing plant resistance to abiotic stress. However, its role in alleviating cadmium (Cd) toxicity in tobacco (Nicotiana tabacum L.) is not fully understood. This study found that Cd stress significantly inhibited tobacco growth. At the same time, 150 μM SNP was the most effective concentration in alleviating Cd toxicity in seedlings, restoring three stress tolerance indicators—MDA, H2O2, and proline—to control levels. Exogenous SNP mitigated Cd-induced oxidative stress by promoting the accumulation of non-enzymatic antioxidants (total phenolics and flavonoids) and activating key antioxidant enzymes (SOD, CAT, POD, APX, and GR) along with their gene expression. SNP also facilitated Cd accumulation in the root cell wall and prevented Cd translocation from roots to shoots. Additionally, SNP altered Cd's subcellular distribution, promoting its sequestration in vacuoles and cell walls, which may be related to the NO-mediated upregulation of the metallothionein gene NtMT2F and the phytochelatin gene NtPCS2. The addition of SNP significantly increased the proportion of Cd in less toxic chemical forms, with the residual Cd fraction in the Cd + SNP group reaching 7.30 %, higher than the 4.86 % in the Cd-only group. Furthermore, exogenous SNP counteracted Cd's inhibition of nitrate reductase (NR) activity, promoting endogenous NO production. This study systematically reveals the positive roles of exogenous SNP in mitigating Cd toxicity in tobacco, offering valuable insights for producing low-Cd tobacco.

Impact of hydrochar in stabilization/solidification of heavy metal-contaminated soil with Portland cement.

Stabilization/Solidification (S/S) using Portland cement is a common soil remediation technique for heavy metal-contaminated sites. However, due to the hindrance of cement hydration by heavy metals (HMs) and the high CO2 emissions from cement production, efforts have been made to reduce cement consumption. Supplementary cementitious materials (SCMs) present an efficient alternative for this purpose. This study investigates the impact of hydrochar and modified hydrochar as SCMs for remediating soils contaminated with Zn, Pb, and Cd. Forty treated soil samples were evaluated using unconfined compressive strength (UCS), pH, Toxicity characteristic leaching procedure (TCLP), and sequential extraction procedure (SEP) tests, and statistical analysis was conducted to assess the effects of binder content, hydrochar dosage, and hydrochar type. Results show that substituting cement with hydrochar or modified hydrochar reduces UCS by 10-40%, with hydrochar having a greater negative impact than modified hydrochar. pH values ranged from 6.98 to 12.64, facilitating HMs precipitation. In heavily contaminated samples, hydrochar or modified hydrochars significantly decreased the Zn, Pb, and Cd TCLP values by 55%, 63%, and 50%, respectively. In moderately contaminated samples, the reduction was slight for Zn and Pb, with no significant change for Cd. SEP test results indicated that hydrochar or modified hydrochar in cement improves the transformation of the acid-soluble fraction to the residual fraction of Zn and Pb, but not for Cd-contaminated soil samples. Overall, these findings suggest that incorporating hydrochar or modified hydrochar as SCMs in cement contributes to reducing cement usage and CO2 emissions while enhancing the stabilization efficiency of certain heavy metals in contaminated soils.

Integrated Assessment of Metal Contamination of Soils, Sediments, and Runoff Water in a Dry Riverbed from a Mining Area Under Torrential Rain Events

Dry riverbeds can transport mining waste during torrential rain events, disseminating pollutants from mining areas to natural ecosystems. This study evaluates the impact of these mine wastes on soils, sediments, and runoff/pore water in the La Carrasquilla dry riverbed (southeastern Spain). An integrated approach utilizing geochemical and mineralogical techniques was employed, analyzing water, soil, and sediment samples from both the headwater and mouth of the riverbed. Soil profiles and pore water were collected at 30 cm, 60 cm, and 90 cm deep, alongside sediment and runoff water samples. The assessment of metal(loid) contamination focused on arsenic, cadmium, chromium, copper, iron, nickel, manganese, zinc, and lead, utilizing sequential extraction to evaluate metal partitioning across soil phases. Various pollution indices, including the contamination factor (Cf), pollution load index (PLI), potential ecological risk index (RI), and metal(loid) evaluation index (MEI), were employed to classify contamination levels. The highest level of contamination was reported in the headwater, which suggested anthropogenic activities linked to the presence of mining residues as the major source of metal(loid)s. However, an active deposition of As, Cd, Cu, Fe, Mn, and Zn was reported in the topsoil at the mouth. In the headwater, a quartz and muscovite-rich zone exhibited the highest Cf for Pb (1022), primarily bound to the soil residual fraction (62.8%). At the headwater and mouth, pore water showed higher concentrations of sulfate, Ca, Na, Cl, Mg, and Mn and higher salinity than acceptable limits for drinking water or irrigation established by the World Health Organization. Runoff-water metal concentrations surpassed established guidelines, with MEI values indicating significant contamination by cadmium (36.1) and manganese (19.0). These findings highlight the considerable ecological risk of Pb and underscore the need for targeted remediation strategies to mitigate environmental impacts in the Mar Menor coastal lagoon.

Soil zinc dynamics over time on applied organics, bacterial inoculant and zinc fertilizers in calcareous soil of southern India

Bioavailability of zinc was impacted by soil properties, externally applied sources, time, and various fractions of zinc. An experiment was conducted to investigate the bioavailable and other zinc fractions in calcareous soil and the efficiency of organic and inorganic sources on bioavailability with the presence and absence of zinc solubilizing bacteria (ZSB). The sequential extraction procedure followed at every interval of the incubation period for all forms of zinc was studied. Externally added inorganic sources significantly affected all fractions of zinc compared to untreated soils. Among them, ZnSO4 influences all forms of zinc, mainly Ws+Ex (water soluble+exchangeable) and carbonate-bound zinc, whereas Zn-EDTA maintains a high status of bioavailable zinc throughout the experimental period. On the 60th day of incubation, Zn-EDTA and ZnSO4 applied to soil maintained bioavailable zinc content of 3.71 and 2.94 times higher than that of control. Irrespective of sources, the available zinc of Zn fertilizers applied to soils was reduced with an increase in incubation days. Organic and microbial addition effects solely or combined increase the soil zinc content significantly in both fertilized and unfertilized soils. Among two different organic sources, the zinc solubility performance of farmyard manure was higher than that of vermicompost. In untreated soil, residual and carbonate-bound fractions contribute a major portion towards total zinc based on quantity. The bioavailable fraction mainly the Ws+Ex and organically bound fractions were markedly influenced in all treatments.

Ecological Risk of Heavy Metals in an Eco-Industrial Park in China

ABSTRACT To ascertain whether rapid industrialization has affected the accumulation of heavy metals (HMs) in Suzhou Industrial Park (SIP), China, the occurrence and ecological risk of HMs, including Cu, Zn, Pb, Cr, Cd, Ni, As and Hg in sediments were analyzed. The results indicated that total concentrations of HMs (mg kg−1) were in the descending sequence of Zn (235.28) > Cr (95.71) > Cu (78.91) > Ni (55.51) > Pb (23.96) > As (22.12) > Cd (0.38) > Hg (0.14). The concentrations of HMs, except for Ni and Cd, were found to be below the probable effect level (PEL). Correlation analysis (CA) and principal component analysis (PCA) showed that HMs in SIP mainly originated from anthropogenic activities. HMs were mainly in residual fractions (55.5 ~ 95.1%), and the exchangeable fractions of Zn and Cd were relatively high. The risk assessment results indicated that Hg and Cd significantly contributed to ecological risks, whereas Cr and Pb made relatively minor contributions. Our findings indicated that intense anthropogenic activities promote HMs accumulations in streams in SIP during rapid industrialization.

Unravelling the environmental drivers determining the residual fraction of soybean seed

AbstractThere are three main components of soybean (Glycine max (L.) Merr.) seeds: protein, oil, and residual. The residual fraction includes soluble and insoluble carbohydrates, lignin, and minerals. Among soluble carbohydrates, the presence of raffinose family of oligosaccharides (RFOs) has poor nutritional value (i.e., raffinose and stachyose), and the inability of monogastric animals to digest them limits the potential use of soybean meal for food and feed applications. Our objective was to understand how different environmental conditions impact soybean seed quality, particularly the concentration of the residual fraction and its components. Nine commercial genotypes from three maturity groups were sown on early and late dates. The concentration of insoluble carbohydrates + lignin was positively associated with seed weight (r = 0.67) and negatively associated with the mean temperature during the seed‐filling period (R5–R7; r = −0.61). Within soluble carbohydrates, RFOs were negatively influenced by the mean temperature at the beginning of the seed‐filling period (R5–R6; r = −0.37), while sucrose concentration showed the opposite effect (r = 0.43). In contrast, precipitation exhibited a positive correlation with RFOs, whereas sucrose displayed a negative correlation (r = 0.38 and r = −0.42). This study showed that the decrease in protein concentration was related to the increase in the residual fraction of the seeds, and higher temperatures during seed‐filling period impacted the residual composition of the seeds, specifically by reducing RFO concentration.