Zinc Enrichment Research Articles

Strategy on rapid selection of woody species for phytoremediation in soils contaminated with copper, lead and zinc in Shanghai

The use of woody species for the remediation of heavy metal-contaminated soils is an environmentally friendly and economically viable strategy. This study investigates the phytoextraction abilities of 15 woody species for copper, lead and zinc in contaminated soil. The results indicated that all species showed phytoextraction ability, with metal concentrations varying from 5.59 to 27.45 mg·kg−1 for Cu, 2.79 to 16.75 mg·kg−1 for Pb and 22.13 to 185.72 mg·kg−1 for Zn in the stem tissues depending on the species. Pterocarya stenoptera, Paulownia fortunei and Salix matsudana were identified as the top performers in terms of overall phytoextraction capacity. Notably, their capacity to transport zinc exceeded that of copper and lead. The enrichment of copper, lead and zinc in the soil showed a synergistic effect in the presence of heavy metal. The distribution of heavy metals within plant tissues was affected by water content and the inherent toxicity of metals. The study highlights that the accumulation of tree biomass and water content in the stem play a significant role in determining the amount of heavy metals phytoextracted. This insight offers a quick method for the rapid selection of woody species for phytoremediation in urban soils contaminated with heavy metals.

Geochemical and Documentary Topography of a Medieval Silver Valley: Detection of Workshops and Identification of Their Function

ABSTRACTThis paper presents the interdisciplinary investigation (archaeology, geochemistry, history) of a medieval silver and lead production site located in southern France, in the Minier valley (Occitanie, Aveyron, Le‐Viala‐du‐Tarn). In order to identify the production sites, in situ geochemical surveys were carried out using a portable X‐ray fluorescence spectrometer and differential GPS, guided on the analysis of medieval archival sources. The cartographic representation of the metal concentrations in the surface horizons shows significant enrichment of zinc and lead in the vicinity of the mines. This first type of enrichment makes it possible to highlight the activities of separation of sphalerite and silver‐bearing galena. The galena thus isolated on the hillsides is then transported to the vicinity of watercourses, where it is crushed, washed, and smelted. These secondary activities result in a last type of enrichment in which only lead is found in large quantities. The cross‐referencing of the information made it possible to overcome the challenges related to the location of the mineral processing workshops, which were often invisible on the surface. The medieval workshops have been located and a function suggested, outlining the first trends in the spatial and social division of labour and providing a solid corpus for future archaeological excavations. Finally, this study highlights the persistence of significant metal contamination in the soils of a rural valley and encourages the consideration of former mining areas when examining the environmental impact of metal production.

Steel mill solid waste transformation: Optimizing converter sludge recycling through RHF technology

Current methods for treating converter sludge include reintroducing it into the sintering or pelletizing process. However, this method leads to the enrichment of zinc in the blast furnace, which affects the stability of the production operation. To solve this problem, a direct reduction process utilizing multi-solid waste collaborative rotary hearth furnace (RHF) has been implemented in steel plants to recover and safely dispose of valuable components in waste. The laboratory results show that the dezincization rate of the metallized pellets is 99.12 % and the metallization rate is 80.51 % under the premise of reducing 50 °C by calcination at 1200 °C for 15 min in the nitrogen atmosphere. In the industrial test conducted in RHF production line of Shagang from March 2022 to August 2023, the temperature in the high temperature zone was reduced by 50 °C, and the time in the high temperature zone was controlled to 15 min. The industrial test results showed that the residual zinc content in the metallized pellets was 0.63 %, and the metallization rate was about 75.12 %. These particles can be used as feedstock or coolant in the steelmaking process. The average grade of by-product zinc oxide coarse powder can reach 65.88 %, which can be further processed into zinc products with remarkable economic benefit. Through RHF integrated management of converter sludge and other solid waste in steel mills, metallized pellets and high-value products can be produced, which can effectively reduce solid waste in steel enterprises and improve resource utilization.

Interphase migration and enrichment of lead and zinc during copper slag depletion

An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established. The occurrence of various components in copper slag was predicted using sulfur−oxygen potential calculations and confirmed through high-temperature experiments. The recovery rate of copper can reach 90.13% under the optimal conditions of 1200 °C, an iron to silicon mass ratio of 1.0, 3 wt.% ferrous sulfide, and a duration of 45 min. Lead (54.07 wt.%) and zinc (17.42 wt.%) are found in the flue dust as lead sulfate, lead sulfide, and zinc oxide, while copper matte contains lead (14.44 wt.%) and zinc sulfide (1.29 wt.%). The remaining lead and zinc are encapsulated as oxides within the fayalite phase.

Gut Microbiota Modulation by Selenium and Zinc Enrichment Postbiotic on Dysbiosis Associated with Hypertension.

Targeting gut dysbiosis to treat chronic diseases or to alleviate the symptoms is a new direction for medical adjuvant therapies. Recently, postbiotics have received considerable attention as they are non-viable probiotic preparations that confer various health benefits to the host without the safety problems associated with using live microbial cells. The aim of the study is to obtain selenium (Se) and zinc (Zn) enriched Saccharomyces boulardii postbiotic biomass and to analyze its modulation effect because these minerals play an important role in reducing gut dysbiosis linked to cardiovascular (CV) diseases. The effect of the S. boulardii and Se/Zn enriched yeast postbiotics on CV microbial fingerprint was studied in vitro using the gastrointestinal system (GIS 1) and analyzed by microbiological, chemical, and qPCR methods. There was a 2.2 log CFU/mL increase in the total bacterial load after SeZn postbiotic treatment and in the qPCR counts of Firmicutes phyla for both treatments. Beneficial taxa, Bifidobacterium spp. and Lactobacillus spp., as well as Bacteroidesspp. were up to 1.5 log higher after mineral- enriched postbiotic application, while the acetic acid level increased. These preliminary studies highlight the therapeutic potential of using Se/Zn enriched yeast postbiotics as adjuvants for clinical treatments of CV diseases.

Foliar Spraying with ZnSO4 or ZnO of Vitis vinifera cv. Syrah Increases the Synthesis of Photoassimilates and Favors Winemaking.

Zinc enrichment of edible food products, through the soil and/or foliar application of fertilizers, is a strategy that can increase the contents of some nutrients, namely Zn. In this context, a workflow for agronomic enrichment with zinc was carried out on irrigated Vitis vinifera cv. Syrah, aiming to evaluate the mobilization of photoassimilates to the winegrapes and the consequences of this for winemaking. During three productive cycles, foliar applications were performed with ZnSO4 or ZnO, at concentrations ranging between 150 and 1350 g.ha-1. The normal vegetation index as well as some photosynthetic parameters indicated that the threshold of Zn toxicity was not reached; it is even worth noting that with ZnSO4, a significant increase in several cases was observed in net photosynthesis (Pn). At harvest, Zn biofortification reached a 1.2 to 2.3-fold increase with ZnSO4 and ZnO, respectively (being significant relative to the control, in two consecutive years, with ZnO at a concentration of 1350 g.ha-1). Total soluble sugars revealed higher values with grapes submitted to ZnSO4 and ZnO foliar applications, which can be advantageous for winemaking. It was concluded that foliar spraying was efficient with ZnO and ZnSO4, showing potential benefits for wine quality without evidencing negative impacts.

Anatomy and genesis of the world’s largest carbonate-hosted Zn-Pb deposit: New insights from ore characteristics, Zn-Pb-C-O isotopes, and trace element constraints of the Huoshaoyun deposit, Karakorum Range, Xinjiang

The Huoshaoyun deposit in the Karakorum area of NW China is the world’s largest zinc-lead carbonate ore deposit. Here we investigate the genesis of the mineralization based on multiproxy investigations. The deposit contains zinc-lead carbonate and sulfide minerals, with smithsonite (Smt), cerussite (Cer), and sulfides accounting for 85%, 10%, and 5% of the total lead and zinc resources, respectively. Three ore-forming stages, involving Smt, Cer, and sulfides ores were summarized. The Smt mineralization is characterized by veined, massive, and stratified Smt forming horizontal sedimentary layered ore and vertical feeder veins similar to the SEDEX-type deposits. The sulfide and Cer veins display typical hydrothermal characteristics and are superimposed on the massive Smt ores. The Smt ores show high Li, Be, Cr, Y, Ba, Nd, Yb, and Zr contents, whereas the Cer veins have extremely high Sr contents (up to 3814–9174 ppm) and low Zr contents (less than 0.01 ppm). Galena and sphalerite show higher Cd concentrations compared to Smt and Cer ores.The Smt ores differ with different spatial locations, with Smt ores formed at the vent have δ66Zn values of +0.15‰ to +0.21‰, the massive Smt formed close to the vent show a value of +0.13‰, and those formed away from the vent show a value of 0.05‰, all values being close to 0. The sulfides have δ66Zn values of −0.09‰ to +0.04‰. The C-O isotopes of Smt ores are similar to both altered and unaltered host limestone, suggesting that the limestone was a potential source for carbon and oxygen. Quartz with veined Smt shows magmatic signatures with δ18OVSMOW of +1.14‰ to +2.23‰, high Pb (115–401 ppm) and Zn concentrations (390–997 ppm), whereas quartz associated with sulfide has meteoric fluid signature with the lowest δ18OVSMOW (−14‰ to −10.7‰), low Pb (11.6–49.0 ppm) and Zn (18.1–72.8 ppm) concentrations. The temperature of equilibration computed based on oxygen isotope fractionation between Smt and coeval quartz indicate a dual source with that of quartz derived from an aqueous fluid, whereas the source for Smt might involve CO2 or HCO3−.We trace multiple metallogenic stages for this deposit including exhalation, hydrothermal deposition, and fault-controlled sulfide vein formation. The largest orebody (III-1) preserves a 16 Mt reserve of Zn and was formed by crust-mantle interaction at ca. 195 Ma in the early development of the Linjitang post-arc rift system. Fluid convection, zinc enrichment driven by granitic magma, volcanic activity, and karst alteration induced by acid rain in a lagoonal environment promoted ore enrichment.

Pedipalp anatomy of the Australian black rock scorpion, Urodacus manicatus, with implications for functional morphology

Pedipalps – chelate ‘pincers’ as the second pair of prosomal appendages – are a striking feature of scorpions and are employed in varied biological functions. Despite the distinctive morphology and ecological importance of these appendages, their anatomy remains underexplored. To rectify this, we examined the pedipalps of the Australian black rock scorpion, Urodacus manicatus, using a multifaceted approach consisting of microcomputed tomography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and live pinch force measurements. In doing so, we document the following aspects of the pedipalps: (1) the musculature in three dimensions; (2) the cuticular microstructure, focusing on the chelae (tibial and tarsal podomeres); (3) the elemental construction of the chelae teeth; and (4) the chelae pinch force. We recognise 25 muscle groups in U. manicatus pedipalps, substantially more than previously documented in scorpions. The cuticular microstructure – endo-, meso-, and exocuticle – of U. manicatus pedipalps is shown to be similar to other scorpions and that mesocuticle reinforces the chelae for predation and burrowing. Elemental mapping of the chelae teeth highlights enrichment in calcium, chlorine, nickel, phosphorus, potassium, sodium, vanadium, and zinc, with a marked lack of carbon. These elements reinforce the teeth, increasing robustness to better enable prey capture and incapacitation. Finally, the pinch force data demonstrate that U. manicatus can exert high pinch forces (4.1 N), further highlighting the application of chelae in subduing prey, as opposed to holding prey for envenomation. We demonstrate that U. manicatus has an array of adaptions for functioning as a sit-and-wait predator that primarily uses highly reinforced chelae to process prey.

Soil Contamination by Metals/Metalloids around an Industrial Region and Associated Human Health Risk Assessment

Industrial, agricultural, transportation, and waste management activities cause soil contamination by metals/metalloids. Soil contamination is an essential global concern since it poses a significant risk to human health. Particularly in areas near heavy industry, people are more prone to exposure. This study aims to determine current metal/metalloid contamination levels in soil from Aliağa industrial region and assess associated health risks. Five surface soil samples were collected from the region, representing residential, agricultural areas, and downwind of possible sources. Pollution indices were calculated to determine the metal(loid)s with anthropogenic inputs, and a human health risk assessment was conducted. As a result, significant to extreme enrichment of arsenic (As), moderate to significant enrichment of zinc (Zn) and manganese (Mn), and very high enrichment of lead (Pb) and cadmium (Cd) were observed in soil samples. Possible sources of contamination were iron and steel facilities with electric arc furnaces and oil combustion. Non-carcinogenic risk assessment revealed acceptable risks of exposure to Aliağa soils, while exposure scenarios had a great impact on estimated risks. Arsenic, chromium (Cr), and Pb appeared to be significant contributors to non-carcinogenic risk. Carcinogenic risks associated with exposure to As, Pb, Cr, cobalt (Co), and Cd in soils were evaluated to be at an acceptable level. This study only considered soil exposure pathways; hence, a comprehensive risk assessment is deemed necessary not to underestimate the risk of living around an industrial region. Nevertheless, the study provided crucial information for the current hot spots for metal(loid)s in the region and human exposure level.

Variability in zinc:phosphorous and zinc:silicon ratios and zinc isotope fractionation in Southern Ocean diatoms: Observations from laboratory and field experiments

We studied the impact of iron limitation on zinc uptake and the zinc isotope (δ66Zn) composition for Southern Ocean phytoplankton. We undertook laboratory culture and field incubation experiments, and linked these to in situ depth profiles of dissolved (dZn) and particulate (pZn) zinc collected from three sites in the Southern Ocean. For the laboratory experiments, diatom growth rates, cellular zinc accumulation, and δ66Zn all responded to changes in iron and zinc bioavailability. A significant increase in the cellular quota for zinc (expressed as zinc:phosphorous (Zn:P)) occurred upon iron limitation and zinc enrichment. At the same time, δ66Zn for organic tissues became isotopically light under high zinc and low iron concentrations. The opposite occurred for frustule δ66Zn values. Here δ66Znfrustule-organic for cultured phytoplankton became isotopically heavier under high zinc and low iron concentrations. For senescing and dead cells, Zn:P declined and δ66Zn increased, indicating a loss of isotopically light zinc from organic matter. For field incubation experiments, δ66Znfrustule was isotopically heavier than seawater, except for added zinc treatments. The percentage of zinc associated with frustule material for laboratory and field incubations encompassed a wide range with values between 1 and 57%. Depth profiles of δ66Zn for dZn and pZn varied, with dZn being isotopically lighter than pZn in low dZn concentration subantarctic waters, whereas the opposite occurred in polar waters where dZn was isotopically heavier than pZn at higher dZn concentrations. Our results show that iron and zinc availability regulates the zinc content of phytoplankton and the δ66Zn composition of the Southern Ocean, which is propagated to other parts of the world ocean.

Foliar Spraying of ZnO Nanoparticles Enhanced the Yield, Quality, and Zinc Enrichment of Rice Grains.

Zinc deficiency in rice can lead to reduced nutritional value and taste. This study investigates the potential of zinc oxide nanoparticles (ZnO NPs) as a foliar fertilizer during the jointing stage to improve rice yield, quality, and grain zinc enrichment. Over a two-year field experiment (2019-2020), six doses of ZnO NPs (ranging from 0 to 12 kg hm-2) were applied during the jointing stage (46 days after transplanting). The results revealed that foliar spraying of ZnO NPs increased the number of spikelets per spike and the thousand-grain weight by 7.4% to 9.2% and 4.2% to 7.1%, respectively, resulting in a substantial increase in rice yield. Furthermore, it led to a reduction in chalky white and chalky whiteness by 6.23% to 23.6% and 2.2% to 27.9%. ZnO NPs effectively boosted zinc content in rice grains while decreasing the phytic acid to zinc ratio, indicating improved zinc enrichment. Remarkably, protein and amylose content remained unaffected. These findings underscore the potential of ZnO NPs as a foliar fertilizer to enhance rice production, quality, and zinc enrichment. Further research can explore optimal application strategies and long-term effects for sustainable rice production.

Biofortification via foliar application of zinc in oat grains and the effects on nutritional quality and productivity indicators

Foods enriched with zinc can reduce the rates of many diseases and health expenses. Oat, as a nutraceutical food, represents a potential nutritional source by increasing the levels of zinc in the grains by biofortification. The objective of the study is zinc enrichment in oat grains and caryopses, with analysis of productivity indicators, industrial and chemical quality of the grains for technology validation. The experiment was carried out in 2017, 2018 and 2019, in Augusto Pestana, RS, Brazil. The experimental design was randomized blocks with eight replications and five levels of zinc doses (0, 500, 1000, 2000 and 4000 g ha-1) applied via foliar in the grain filling phase. There are almost no changes in oat panicle components due to the effect of biofortification doses by the compound with zinc, and no change in grain yield regardless of agricultural year. Indicators of industrial quality and organic composition of oat grains are not effectively affected by biofortification, ensuring the use of technology without compromising these variables. Considering caryopsis the edible product of oats, from 2000 g ha-1 of zinc sulfate, biofortification of the product is guarantee. Biofortification via foliar by the compound with zinc promotes a significant increase of zinc in oat grains and caryopsis, however, reducing the iron content in these structures

Wheat plant response to zinc enrichment: results from a big plot assay

One third of the global population suffers Zn deficiency, which directly affects their health and the health-bill of all world countries. In this study, the application of Zn sulphate at the latest developing stages (anthesis and milk-dough stages) of bread wheat in Mediterranean conditions were tested for grain and leaves enrichment capacity and antioxidant activities prompting. Variety effects were found to be significant to success in enriching leaves and grains with Zn. While Almansor and Roxo varieties increased more than 50% and close to 40% respectively their amount in grain Zn, no significant differences were found for Paiva variety with or without Zn treatment. Regarding the leaves, Zn amount increases of 110, 230 and 300 ppm of Zn were figured out in Almansor, Roxo and Paiva varieties respectively. Antioxidant compounds in leaves showed to be higher when zinc treatment was applied in Almansor variety. Quality traits of the grain wheat were barely affected by the increase of the Zn amount; Roxo variety grains increased the protein and the dry gluten concentration, while Almansor grains were heavier and Almansor flour showed higher tenacity. It can be concluded that Zn enrichment in wheat plants caused variation in both grain and leaves mineral profile, and antioxidants in leaves.
 Keywords: Antioxidants, Rainfed conditions, RXF, Winter cereals, Zinc

Zinc Oxide Nanoparticles Foliar Application Effectively Enhanced Zinc and Aroma Content in Rice (Oryza sativa L.) Grains

The search for an effective zinc fertilizer and its application method to effectively increase zinc content and enhance aroma in rice grains is a crucial objective. In this study, a 2-year field plot experiment was conducted to investigate the influence of ZnO NPs foliar spraying on rice quality, grain zinc and aroma content, along with exploring the physiological mechanisms underlying these effects. Our results demonstrated that the rice breakdown value and taste value of foliar spraying zinc oxide nanoparticles were improved by 31.0–41.7% and 8.2–13.0% compared with CK (control treatment involved spraying water), improving the tasting and steaming quality of rice. While Fe and Cu content in grains decreased for the application of zinc oxide nanoparticles, zinc oxide nanoparticles foliar spraying significantly increased the zinc content and accumulation of grains by 33.6–65.1% and 37.8–74.7%, respectively. Further analysis showed that the sprayed zinc oxide nanoparticles achieved effective enrichment of zinc in edible parts and increased the final bioavailability of Zn. In addition, foliar spraying of zinc oxide nanoparticles significantly increased activities of nitrate reductase and glutamine synthetase in leaves, which elevated nitrogen content in leaves and grains, and ultimately enhanced 2-acetyl-1-pyrroline (2-AP) content in grains at maturity by 6.1–21.4% compared to CK. Our findings indicated that zinc oxide nanoparticles can be practically applied as a foliar fertilizer at the gestation for quality improvement, zinc enrichment and aroma enhancement of rice grains.

Characterizing Zinc-Rich Chromite Cores and Uvarovite-Grossular Garnet Mantles from the Pikoo Property, Central Eastern Saskatchewan, Canada

Abstract Zinc-rich chromite, (Fe,Zn)Cr2O4, is an important repository for chromium (Cr) that has been observed sporadically worldwide. As another source for Cr, green uvarovite garnet, ideally Ca3Cr2(SiO4)3, is the rarest variety among anhydrous garnets. Here, we present a detailed petrographic, mineralogical, and geochemical characterization of 71 uvarovite garnets with zinc-bearing chromite cores recovered from the Pikoo Property (central eastern Saskatchewan), which also hosts recently discovered kimberlites proven to be diamondiferous. In this work, euhedral to anhedral unzoned chromite occurs as cores or irregular inclusions enclosed by uvarovite–grossular mantles. They contain moderate to high Cr (41.63–66.70 wt.% Cr2O3; Cr/(Cr+Al) = 0.64–0.99), Fe2+ (16.71–28.67 wt.% FeO), and Zn (1.64–15.52 wt.% ZnO) contents, accompanied by an appreciable amount of Mn (0.63–2.32 wt.% MnO). The chromite core with the highest Zn content gave the structural formula (Zn0.409Fe2+0.555Mg0.018Mn0.019)Σ1.00(Cr1.174Al0.674Fe3+0.152)Σ2.00O4, which corresponds to Zn-rich chromite with a minor proportion of other endmembers (e.g., hercynite, FeAl2O4). Zinc enrichment in chromite is most likely the result of metasomatic replacement of primary chromite involving the action of Zn-rich fluids. The Zn-rich chromite cores are commonly porous and demonstrate streaking in the 2D diffraction pattern that is attributable to non-uniform strain. The strain measurements suggest the involvement of fluid-present plastic deformation during metasomatic alteration. The garnets are compositionally zoned aggregates and commonly contain inclusions. Chemical formulae indicate that they are mainly members of the uvarovite–grossular series (up to 93% mol.% Uv) enriched in Ca (22.99–35.57 wt.% CaO) and Cr (up to 28.10 wt.% Cr2O3), but consistently depleted in Mg (mean = 0.10 wt.% MgO) and Ti (mean = 0.26 wt.% TiO2). Most garnet aggregates consist of uvarovite and grossular that exhibit a core-rim zoning pattern characterized by an increase in grossular proportion at the expense of the uvarovite component. Morphological characteristics, textural relations, and compositional trends suggest that uvarovite garnet formed through interaction of Zn-rich chromite with grossular. This mineral assemblage is not genetically related to the Pikoo kimberlite and represents an independent evolutionary event. The use of Zn-bearing chromite as a new kimberlite indicator mineral therefore should be carefully evaluated prior to exploration practices.

TOF-SIMS and AFM analysis of pH effect on the interfacial films on η-phase in aqueous salt solutions

The pH effect on the surface and interfacial films on η-phase (MgZn2) in aqueous solutions under acidic, neutral, and alkaline conditions has been evaluated using time of flight-secondary ion spectroscopy (TOF-SIMS), Atomic force microscopy (AFM) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX). TOF-SIMS depth profile plots reveal that under an acidic environment (pH2) deep corrosion penetration occurs with a dispersion of corrosion products which claims a considerable depth matrix cross-section. Under near neutral environments (pH 6), the corrosion film is seen to be stratified into two layers of different compositions, while in a slightly alkaline environment (pH 10) the film appears not to be distinctly differentiated, whereas in a very alkaline environment (pH 13) a compact film rich in hydroxides develops. TOF-SIMs surface and depth profile maps were consistent with the depth profile plots. SEM and AFM images reveal that the surface roughness increased in with a decrease in pH value from the acidic to the alkaline environments. EDX elemental composition analysis also indicated a severe drop in the zinc content of the film in the alkaline environment. Largely, metallic zinc enrichment occurs following the initial magnesium dissolution whose stability is greatly affected by the near-surface pH of the bulk solution, thus, giving rise to different film structures.

Zinc enrichment and isotopic fractionation in a marine habitat of the c. 2.1 Ga Francevillian Group: A signature of zinc utilization by eukaryotes?

Constraining the timing of eukaryogenesis and the divergence of eukaryotic clades is a major challenge in evolutionary biology. Here, we present trace metal concentration and zinc isotope data for c. 2.1 billion-year-old Francevillian Group pyritized structures, previously described as putative remnants of the first colonial multicellular organisms, and their host black shales. Relative to the host rocks, pyritized structures are strongly enriched in zinc, cobalt and nickel, by at least one order of magnitude, with markedly lighter zinc isotope compositions. A metabolic demand for high concentrations of aqueous zinc, cobalt, and nickel combined with preferential uptake of lighter zinc isotopes may indicate metalloenzyme utilization by eukaryotes in marine habitats c. 2.1 billion years ago. Once confirmed, this would provide a critical calibration point for eukaryogenesis, suggesting that this major evolutionary innovation may have happened contemporaneously with elevated atmospheric oxygen levels during the latter part of the Great Oxidation Event, some 400 million years earlier than is currently widely accepted.

Effect of Leaf Surface Regulation of Zinc Fertilizer on Absorption of Cadmium, Plumbum and Zinc in Rice (Oryza sativa L.)

The accumulation of heavy metals in rice is bound to affect human health and safety. In order to ensure food security, this study explores the effect of leaf surface regulation of zinc (Zn) fertilizer on the safety of rice in cadmium (Cd)-plumbum (Pb) polluted farmland. Through field experiments, the leaf surface control treatment of zinc fertilizer was set up, and the effects of leaf surface control of zinc fertilizer on rice yield, Cd and Pb concentration in different parts and zinc, nitrogen, phosphorus and potassium concentration in brown rice were studied in the growing period of rice. The results showed as follows: (1) Spraying twice or more in the growth stage of rice could increase the yield by 6.77–7.29% compared with the blank, which was significantly higher than that of single spraying in a certain growth stage. (2) After spraying zinc fertilizer on the leaf surface, Cd and Pb concentration in brown rice decreased by 29.52–56.01% and 11.10–28.34%, respectively, compared with CK. Two or more times of spraying can make Cd concentration in brown rice meet the Chinese standard GB 2762-2022, and one time of spraying can make Pb concentration in brown rice meet the standard. (3) Leaf surface control of zinc fertilizer could reduce the Cd enrichment ability of rice plant parts, and the Cd enrichment coefficient of brown rice was significantly reduced by 28.18–55.02%. Leaf surface control of zinc fertilizer can reduce Cd and Pb concentration in brown rice by reducing the transport ability of heavy metal Cd and Pb in rice roots to straw and then to brown rice. (4) The zinc concentration in brown rice was 18.16–20.68 mg·kg−1, which was 18.21–34.64% higher than that in CK, and the zinc enrichment effect was the most significant after spraying three times. Meanwhile, the nitrogen, phosphorus and potassium concentration in brown rice also increased with the increase of spraying times. By comprehensive analysis, the leaf surface control of zinc fertilizer can reduce the Cd and Pb concentration in rice, and the Cd and Pb concentration in brown rice can meet the Chinese standard GB 2762-2022 by spraying twice. At the same time, it can improve the concentration of zinc, nitrogen, phosphorus and potassium in brown rice, is feasible and has high economic benefits.

Extraction and enrichment of zinc from chloride media using emulsion liquid membrane: Emulsion stability and demulsification via heating-ultrasonic method

Emulsion liquid membrane (ELM) is highly efficient in heavy metal ion separation from wastewater. However, substantial effort is required to overcome the instability in the process. Hence, this research demonstrates the stability of water-in-oil-in-water (W/O/W) emulsion and demulsification for zinc recovery from chloride media. Iron (III) oxide (Fe2O3) nanoparticles were used as a solid stabilizer in the formation of water-in-oil (W/O) emulsion. Several operating parameters affecting the stability of W/O/W emulsion by means of breakage/swelling and globule size diameter were studied, such as organic-to-internal phase (O/I) ratio, agitation speed, time, and treatment ratio. The most stable formulated W/O/W emulsion was used in the demulsification process using heating-ultrasonic method. The study was conducted by manipulating the temperature, frequency, and time. Meanwhile, experiments on the effect of modifier type, carrier, and stripping agent concentration were carried out for zinc recovery. The most stable W/O/W emulsion was obtained at 1.35:1O/I ratio, 300 rpm agitation speed, 3 min agitation time, and 1:5 treatment ratio. Complete demulsification was achieved at a temperature of 50 °C, 40 kHz frequency, and 210 min contact time. At the best condition of 3% (w/v) 1-octanol, 0.03 M carrier concentration (D2EHPA/Cyanex 302), and 1.375 M acidic thiourea, approximately 93.14% zinc was extracted, and 4.65 times enrichment was obtained in the recovery phase. Hence, it can be concluded that enhancing the stability of emulsion could potentially make ELM applicable in the industry.

Distribution, chemical speciation and human health risk assessment of metals in soil particle size fractions from an industrial area

The problem associated with metal contamination in the soil is intensified in the vicinity of industrial areas as they are more susceptible to discharges from medium to small scale industries. However, limited studies are available that consider soil size fractions along with their speciation due to multi metal contamination. This information is essential to apprehend their individual and competitive mobility, bioavailability and possible de-contamination strategies. In the present study, soil samples (n = 10) were collected from Ranipet industrial area, India and analysed for total metal concentrations (Al, Cd, Cr, Cu, Fe, Mn, Pb, and Zn). The ecological risk assessment indicated substantial anthropogenic enrichment of chromium along with moderate enrichment of copper, manganese and zinc. Further, the samples were fractionized into 300–150, 150–50, 50–22 and < 22 µm; the finer fraction concentrations were used to assess human health risks. The Hazard Index (HI) values reached 2.37 for children and 0.30 in adults from non-carcinogenic risk; indicated children are at higher risk. The soil exposure risk assessment study in three different scenarios were considered; results indicated possible non-carcinogenic risk to the non-residents working in study area. The Cancer risk (CR) values followed the order CR (ingestion) > CR (dermal contact) > CR (inhalation). The speciation study performed in bulk and size fractions indicated the bioavailable forms dominated residual fractions irrespective of sizes but varied with metals. This study can be considered as a framework for risk identification and assessment from multi metal contamination in industrial area having small and shallow waterbodies.