Bioavailability Of Zn Research Articles

Effects of dietary zinc oxide nanoparticles supplementation on broiler growth performance, zinc retention, liver health status, and gastrointestinal microbial load

BackgroundZinc (Zn) is an essential trace element for poultry health and biological functions. Inorganic Zn, like Zn oxide and Zn sulfate, was commonly used in poultry feed due to its low cost. However, the bioavailability of inorganic Zn is low, leading to a high level of Zn being added to the feed and resulting in other issues. Zinc oxide nanoparticles (ZnO NPs) have emerged as a promising alternative to their bulkier counterparts, but concerns about their safety persist. Therefore, this study aimed to evaluate the potential benefits and toxicity of dietary ZnO NPs as a feed supplement and antibacterial agent in broiler chickens. Methods180 broiler chicks (Cobb500) were randomly allocated to five dietary treatment groups (36 birds/group). The experimental treatment groups were as follows: (G1) basal diet supplemented with 100 mg kg−1 ZnO (control group), (G2-G5) basal diet supplemented with 10, 40, 70, and 100 mg kg−1 ZnO NPs. The effects of dietary ZnO NPs at different inclusion levels were studied by measuring growth performance (FI, BWG, and FCR), Zn retention, liver enzyme activity, lymphoid organ weight, and gastrointestinal microbial load. ResultsThe results showed that dietary ZnO and different levels of ZnO NPs inclusion had no effect on broiler growth performance (p > 0.05). The birds fed dietary ZnO NPs retained significantly more Zn than the control group (p < 0.05), lowering feces Zn excretion. The supplementation of ZnO NPs did not reduce lymphoid organs weight; in fact, a notable increase in weight was observed in groups supplemented with higher levels of ZnO NPs when compared to the control group. Furthermore, no significant increase in liver weight (p > 0.05) or enzymatic activities (AST and ALT) were observed in birds fed ZnO NPs, indicating no liver damage occurred. ZnO NPs at 100 mg kg−1 in the diet showed antibacterial effects, reducing Enterococcus spp. and E. coli count significantly, without affecting commensal bacteria (lactic acid bacteria) count. ConclusionThe inclusion of ZnO NPs to broiler chicken feed as a Zn source had no negative effects on growth or health. Additionally, it increased Zn absorption and bioavailability, reduced Zn excretion, and exhibited potential antibacterial activity against tested pathogens.

Nutrients, the Bioavailability of Micronutrients and Antinutrient Composition of African Yam Bean Tubers

Despite the huge nutritional and nutraceutical benefits associated with the consumption of African yam bean (AYB) seeds, AYB tubers are still underutilized in Nigeria, they are left to rot in farmers’ fields. To create awareness about their nutrient density and provide information on the bioavailability of micronutrients in the tubers of AYB accessions, raw tubers of TSs 9, TSs 60 and TSs 93 were analyzed using standard laboratory procedures. The AYB tubers had the following composition on a fresh weight basis: crude protein (7.55-8.27%), carbohydrate (9.36-11.12%), crude fat (0.18-0.22%), crude fibre (0.33-0.750%), crude ash (0.44-0.59%), and moisture (79.76-80.82%). The fresh tubers were rich in minerals: potassium (532.88-557.80 mg/100 g), calcium (205.75-467.50 mg/100 g), magnesium (124.75-168.50 mg/100 g), iron (15.71-27.30 mg/100 g), zinc (8.57-14.80 mg/100 g), and manganese (0.68-1.98 mg/100 g). The phytate: Zn and the phytate: Fe molar ratios indicated the bioavailability of Fe and Zn in the raw AYB tubers. The results of this study indicate that AYB tubers are good sources of protein, energy and bioavailable Fe and Zn and should be utilized for human diets and livestock feed. With good processing, AYB tubers could contribute to food and nutrition security. There is a need for research on food products developed from AYB tubers to enhance their utilization and large-scale production in Nigeria.&nbsp

Zinc-solubilizing Pseudomonas strains improve zinc nutrition of maize plants grown in sand amended with tire waste powder

The present study was conducted to investigate the potential of Zn-solubilizing Pseudomonas strains to release Zn from tire waste powder (TWP) in a liquid medium and soil. A pot experiment was also conducted to investigate the effects of TWP (as a Zn source) at four rates of 0, 9, 18 and 27 g TWP kg−1 soil and Pseudomonas strains (Ctrl: without bacterial inoculation, or inoculated with B1: A5, B2: K5, B3: A2, B4: A11 or B5: D12 strain) on growth and Zn nutrition of maize. Fourteen bacterial strains were grown in liquid Pikovskayas (PVK) medium supplemented with TWP, and ten superior Pseudomonas strains with high Zn solubilization activities were selected for the subsequent Zn kinetics study. In the TWP-treated soil, the concentrations of DTPA-extractable Zn were significantly higher in inoculated treatments than those in the control treatment in all incubation times. Individual application of Pseudomonas strains or TWP treatments significantly increased the shoot biomass of maize plants. Furthermore, the combined application of Pseudomonas strains and TWP led to higher shoot Zn concentration of plants as compared to the individual applications. The highest shoot Zn concentration was observed with the use of 18 g TWP kg−1 soil in treatment inoculated with B4 strain, which was 16.5-fold higher than that in the control. These findings indicate that co-application of effective Pseudomonas strains with TWP in soils can lead to higher Zn bioavailability for plants, i.e. indicating the potential of TWP as a slow-release Zn fertilizer for crops.

Biochar amendment of a metal contaminated soil partially immobilized Zn, Pb, and Cd and reduced ryegrass uptake

Soil heavy metals (HM) contamination threatens soil and water quality, which significantly affects humans and animals. This study focuses on the competitive immobilization of zinc (Zn), lead (Pb), and cadmium (Cd) in soils from a contaminated site using ryegrass (Lolium perenne) in a potting experiment amended with biochars. Increased rates of switchgrass- (SGB) and poultry litter-derived biochars (PLB) were applied before ryegrass cultivation. Soil HM phytoavailability and HM concentrations in plant shoots were determined. Multivariate regression models were used to evaluate the influence of several soil chemical attributes on the HM phytoavailability. The increased rates of both biochars reduced the Zn, Pb, and Cd availability (p &amp;lt; 0.001). Langmuir models showed that the maximum HM immobilization (IMAX) was 169.2 ± 29.5 mg kg–1 for Zn with SGB, and 20 ± 7.4 (Pb) and 1.08 mg kg–1 (Cd) with PLB. The extended Langmuir model (EL) showed competitive HM immobilization since there was a decrease in the IMAX of Zn (∼90 ± 28 mg kg–1 from SGB) and Cd (∼0.70 ± 0.21 mg kg–1). Negative values of Pb and Cd immobilization at low rates of SGB indicated an increase in those HM availabilities and preferential immobilization for Zn. The reduced Zn and Pb uptake in ryegrass shoots ranged from 70% to 98% and were optimum at rates of 0.50% ± 0.00%–0.60% ± 0.06% for both biochars, and 1.6% ± 0.4% of SGB for Cd. The stepwise multiple linear regression (SMLR) and partial least squares (PLS) revealed that pH and organic matter (OM) were the most responsible factors for reducing Zn bioavailability while OM was more impactful in decreasing Pb and Cd levels. This suggests that the preferential immobilization for Zn relies on its higher sensitivity to the pH increase. Also, the ubiquitous positive relationship among the metals studied shows that competitive immobilization is ceased at high rates of biochars application. Path analysis (PA) showed that pH and OM were the common contributors from both biochars to simultaneously affect Zn, Pb, and Cd availability regardless of the contrasting physicochemical properties of the two bioproducts. This work proved the potential of applying low rates of two contrasting feedstock-derived biochars to remediate the contaminants and safely grow ryegrass.

Effect of Soil Texture, Nanoparticle Size, and Incubation Period on the Dissolution of ZnO Nanoparticles

Zinc is an essential plant and human nutrient and its primary source is Zn-rich food consumption. The only way to enrich plants with Zn is through the application of Zn fertilizers including various chemical and organic sources of ZnO nanoparticles (NPs). The Zn bioavailability from ZnO NPs must be considered for their recommendation as a fertilizer, and very little is known about the efficacy of such fertilizers in the Hungarian soil environment. In the present investigation, we prepared ZnO NPs of different sizes and applied them in two distinct textures of soils (sandy loam (SL) and silty clay (SC)) in an incubation experiment. The prepared ZnO NPs were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). ZnO NPs were applied in both soil types at 500 mg L−1 in the form of a suspension, and ZnSO4 was applied in the form of a solution. The soils were incubated for 7 and 14 days. Column leaching was performed to analyze the dissolved Zn. Retained Zn in the soil matrix was extracted using 0.05 M EDTA. The results showed that approximately 21–23% and 10–13% higher Zn was observed in the pore water of SL and SC soils, respectively, when spiked with small-sized NPs compared to large-sized NPs, while 14–26% higher dissolved Zn was observed in SL soil compared to SC soil. It is concluded that the size of NPs and the soil texture are the main factors that play important roles in deciding the fate of NPs under an alkaline soil environment.

Sol-Gel Immobilized Optical Microalgal Biosensor for Monitoring Cd, Cu and Zn Bioavailability in Freshwater.

While analytical measurements provide the quantitative estimation of the total amount of metals present in a sample, they do not reflect the truly bioavailable fraction of metal which reflects the adverse biological effect. Hence the development of monitoring tools for detecting bioavailable toxic metals has become a priority in environmental monitoring activities. An optical whole-cell biosensor was constructed using the microalga Scenedesmus subspicatus MM1 immobilizing in inorganic silica hydrogels using the sol-gel technique to detect bioavailable Cadmium (Cd2+), Copper (Cu2+) and Zinc (Zn+) in freshwater. Conditions for optimum biosensor performance have been established regarding effective pH range, cell density, exposure time, and storage stability. The optimum response for the biosensor was dependent on the pH of the matrix, cell concentration and exposure time were derived. The biosensor was operational for four weeks. The limit of detection for the algal biosensor was determined as 9.0 × 10-1, 9.1 × 10-1, and 8.8 × 10-1mg/L for Cd, Cu and Zn, respectively. Whole-cell cell biosensor will be highly useful since it comprises a single microalgal species able to detect the bioavailable content of Cd2+, Cu2+, and Zn2+ in freshwater.

Geochemical fractionation, bioavailability, ecological and human health risk assessment of metals in topsoils of an emerging industrial cluster near New Delhi.

Urban spaces have become sink for metal-rich waste, particularly in unorganized industrial clusters and metro-cities. Geochemical distribution of metals in different forms and their mobility and bioavailability in topsoils of Bhiwadi Industrial Cluster (BIC) near New Delhi are studies following m-BCR-SEP. Contamination factor (Cf), risk assessment code (RAC), ecological risk assessment (Er), and carcinogenic and non-carcinogenic health risk (HRA) were calculated to assess health and environmental risks. Residual fraction (F4) contained considerable amounts of Cd (57.2%), Cr (81.5%), Fe (86.1%), Mn (62.5%), Ni (58.3%), and V (71.4%). Pb was present in reducible fraction (F2; 52.8%), whereas Cu was distributed in F2 (33.3%) and F4 (31.6%). Zn showed equal distribution in acid exchangeable (F1; 33.9%) and oxidizable fraction (F3; 32.5%). High Cf was observed for Zn (0.9-20.9), Cu (0.46-17) and Pb (0.2-9.9). RAC indicated high risk of Cd, Cu, Mn, Ni, and Zn due to their high mobility and toxicity. High potential bioavailability of Cu, Pb, and Zn (> 65%) was found in samples collected near to metal casting, electroplating, and automobile part manufacturing industries. Considerable to extremely high ecological risk was observed for Cd, low to high risk for Cu, low risk to moderate risk for Cr, Mn, Ni, Zn, and Pb. All topsoil samples were in low to very high-risk range for metals. Ingestion was major pathway of metals followed by dermal and inhalation. Children were more prone to non-carcinogenic risks (hazardous index: 3.6). Topsoils had high carcinogenic risk to exposed population for Cd, Cr, Ni, and Pb.

Combinatorial effect of heat processing and phytic acid on mineral bioavailability in rice grain

Brown rice is superior to milled rice in terms of bioactive compounds and minerals but also has phytic acid (PA) that may reduce the bioavailability of minerals. Further, various household cooking methods of rice also change the starch matrix, affecting mineral availability. The effect of PA and heat processing methods on Fe and Zn bioavailability from milled rice grain was investigated. Rice with contrasting PA was analyzed for Fe and Zn bioavailability in milled and cooked rice. The genotype Khira, with the lowest PA (2.0 g kg−1), exhibited high Fe and Zn bioavailability, while Phalguni, with the highest PA (11.2 g kg−1), showed low Fe and Zn bioavailability. The PA had a significant negative correlation with Fe and Zn bioavailability. Among three common household cooking methods used (pressure cooking, microwave-assisted cooking and boiling), pressure cooking exerted more remarkable effects on mineral bioavailability than other two methods. Screening rice genotypes for low PA and high Fe, Zn bioavailability can solve the problem of micronutrient malnutrition in countries where people depend on rice as the main staple food. The selection of appropriate cooking methods is also helps to enhance mineral bioavailability.

Zinc concentration and bioavailability of Chinese steamed bread prepared from foliar zinc-biofortified wheat grain.

Increasing the concentration of zinc (Zn) in a widely consumed staple food, such as Chinese steamed bread (CSB), is a promising strategy for alleviating Zn malnutrition in humans. The aim of this study, which was based on a 2-year field experiment, was to evaluate the effectiveness of spraying Zn fertilizer combined with commonly applied (i) pesticides and/or (ii) KH2 PO4 (PK) to increase the concentration of Zn and its bioavailability in wheat grain and the CSB derived from it. All the foliar Zn applications (foliar Zn alone or combined with pesticides and PK) significantly increased the concentration of Zn in grain and derived CSB by 69.1% and 63.1%, respectively. Milling caused an 86-88% loss of Zn, while the process of producing CSB caused an 11-26% increase in the concentration of Zn. A net gain of 2.5-8.3 mg Zn kg-1 of CSB was achieved owing to foliar applications of Zn. The concentration of phytic acid (PA) decreased dramatically during milling (89-90%) and the production of CSB (69-72%). As a result, the Zn bioavailability was greater in the CSB than in grain. Foliar applications of Zn also increased the estimated Zn bioavailability of CSB to be as high as 5.5-7.8 mg, which is adequate for human nutrition. Enrichment with Zn had no adverse effects on the quality of CSB. The mixture of foliar Zn with pesticides and PK represents a useful approach to improve the bioavailable Zn of CSB without altering its quality. © 2023 Society of Chemical Industry.

Reactive sulfide dynamic models for predicting metal hazardous in sediments of two northern Egyptian Lakes

To track pollution status and bioavailability of Cu, Zn, Cd, Pb, and Ni, the current study's acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) models were compared to previous studies in Edku and Mariut lakes prior to 8 years. Sediment samples were collected in winter and summer 2019 from the two lakes. Metal pollution is higher in the winter than in the summer, according to SEM/AVS models. Metal toxicity is reported to have increased slightly in both lakes. According to risk quotients (RQSEM-PEL and RQSEM-TEL) the two lakes are moderately polluted. The results of the Fe/AVS ratio were in the range of 6.77 to 226.87 and 2.88 to 36.38 μmol/g for Edku and Mariut lakes, respectively. This indicated that [SEM]/[AVS] ratios overestimate the availability of metals. A positive correlation was reported between total organic matter and ∑SEM (r = 0.74 and 0.39 at p < 0.05) in Mariut and Edku lakes, respectively. Multiple-year SEM-AVS studies are recommended.

Spatial Distribution and Risk Assessment of Heavy Metals in Surface Sediments from the Middle and Upper Reaches of the Yangtze River

The hydrological regime of rivers significantly changes after dam impoundment, which in turn affects the particle composition and heavy metal fractions of the river sediments. From June to July 2019, the sediments from 26 sampling sections were collected along the main stream of the Yangtze River from Panzhihua City in the upper reaches of the Yangtze River to Hukou City in the middle reaches of the Yangtze River. The concentrations and fractions of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were measured using the BCR three-step extraction procedure. The pollution status and potential ecological risk of heavy metals in sediments were evaluated using the geo-accumulation index, the sediment quality guideline, and the risk assessment coding method (RAC). The results showed that the average particle size of sediments in the upper reaches of the Yangtze River (Jinsha River cascade reservoir section and the Three Gorges reservoir section) decreased from upstream to downstream, the total concentrations of As and Zn increased, and the variation trend in the middle reaches was not obvious. The content of clay particles was significantly positively correlated with the acid-soluble fraction concentrations of Cd and Ni. Cd was mainly in the residual fraction (59.26%) and acid-soluble fraction (24.67%). Large parts of Cr and Ni were residual fractions accounting for 92.41% and 83.41%, respectively. As, Co, Cu, Pb, and Zn were mainly in the residual fraction and the reducible fraction. The order of decrease for the pollution degree (Igeo) of As, Cd, Co, Cr, Ni, and Zn was the Jinsha River, the middle reaches of the Yangtze River, and the Three Gorges Reservoir. The decrease order of bioavailability (RAC) of Cd, Co, Cr, Cu, Ni, and Zn was the Three Gorges Reservoir, the Jinsha River, and the middle reaches of the Yangtze River. The bioavailability of As and Pb decreased in the order of the middle reaches of the Yangtze River, the Three Gorges, and the Jinsha River. According to the classification of the RAC, Cd in the Three Gorges Reservoir area exhibited a high risk with the RAC accounting for 48.44%. Cu, Ni, and Zn showed a low or medium risk.

Sustainable agricultural use of sewage sludge: impacts of high Zn concentration on on Folsomia candida, Enchytraeus crypticus, Lactuca sativa, and Phaseolus vulgaris.

Zinc (Zn) is an essential micronutrient for plants and an important component for maintaining soil quality. Commonly found in the soil due to anthropogenic activities, such as industrialization and application of organic waste as fertilizers, in high concentrations, Zn may induce soil toxicity, affecting important communities, such as edaphic fauna. Despite its high concentrations found in the environment, Zn bioavailability can be affected by the type of soil, organic matter content and pH. In this work, Zn had its toxicity evaluated in a natural tropical soil, sampled in São Paulo-Brazil, for two soil invertebrates (Folsomia candida, Enchytraeus crypticus) and two seeds (Lactuca sativa and Phaseolus vulgaris), through ecotoxicological tests. The invertebrate E. crypticus was exposed to Zn concentrations of 10.0 (T1); 100.0 (T2); 150.0 (T3); 200.0 (T4); 400.0 (T5) mg Zn kg-1 of dry soil, while F. candida, L. sativa and P. vulgaris were exposed to Zn concentrations of 100.0; 200.0; 400.0; 800.0 (t6); 1600.0 (t7); and 2000.0 (t8) mg Zn kg-1 of dry soil. The outcome evaluated were seed germination, for L. sativa and P. vulgaris, and reproduction, for F. candida and E. crypticus. The EC50 obtained for E. crypticus, F. candida, L. sativa, and P. vulgaris were 261.5, 1089.7, 898.5, and 954.5mg Zn kg-1 of dry soil, respectively, being E. crypticus the most sensitive organism, and only at the highest Zn's concentrations the organisms' reproduction and seeds' germination showed a statistically significant inhibitory effect (p < 0.05). Therefore, this work's results showed that Zn does not present significant toxicity for the tested soil organisms and seeds and that at 100mg Zn kg-1 of dry soil it can be beneficial to F. candida and E. crypticus' reproduction and L. sativa's germination. These results imply that the presence of Zn in low concentrations, both in soil and biofertilizers, such as sewage sludge, not only is not a concern, but it can even benefit certain crops and functions of edaphic organisms, which may contribute to the engagement of sustainable agricultural practices and the quest for food security.

Dietary supplementation of active dry yeast (Saccharomyces cerevisiae) to finishing bulls: effects on growth performance, blood hormones, fatty acid concentrations in the gastrointestinal tract and trace mineral elements utilisation

This study was conducted to investigate the effects of dietary supplementation of active dry yeast (Saccharomyces cerevisiae) on growth performance, circulating ghrelin, fatty acid concentrations in the gastrointestinal tract, and trace mineral elements utilisation of finishing bulls. Twenty Yanbian cattle (bulls) [body weight (BW) 485 ± 38 kg] were randomly divided into two groups (control and treatment groups) and participated in a 100-day finishing trial. The control group (CON) was fed a basal diet (total mixed ration, TMR). The treatment group (active dry yeast, ADY) was fed a basal diet supplemented with ADY (Levucell SC, Saccharomyces cerevisiae CNCM I-1077, viable count ≥8.0 × 109 CFU/g, 1.0 g/bull/day). ADY supplementation significantly increased the dry matter intake (DMI) of bulls (p < .05); significantly increased the concentration of ghrelin O-acyl transferase (GOAT) (p < .05), significantly decreased the concentration of corticotropin-releasing hormone (CRH) (p < .05), tended to increase the concentration of acyl ghrelin (AG) (p = .053) in serum; significantly increased the content of C12:0 in duodenal digesta, the apparent digestibility of Zn, the concentrations Zn and Cu in serum and the deposition of Cu in the liver (p < .05), significantly decreased the deposition of Fe in muscle in finishing bulls (p < .05). In conclusion, ADY supplementation improved DMI of finishing bulls may be related to the change of AG, and a potential mechanism for the change of AG by ADY supplementation is via its effects on the metabolism of C12:0, Zn, and Cu in finishing bulls. HIGHLIGHTS Active dry yeast (ADY) supplementation increased the dry matter intake (DMI) and tended to increase the concentration of acyl ghrelin (AG) in the serum of finishing bulls. ADY supplementation increased the content of C12:0 in duodenal digesta and improved the bioavailability of Zn and Cu of finishing bulls. A potential mechanism for the change of AG by ADY supplementation is via its effects on the metabolism of C12:0, Zn, and Cu in finishing bulls.

Development of an in Vitro Digestion System to Study the Bioavailability and Bioreactivity of Zinc Sulfate and Zn-Bioplex in Fish Using the RTgutGC Cell Line

Here, we report the development of a novel in vitro digestion system that mimics the digestive process in fish and uses the RTgutGC cell line, a model of the rainbow trout (Oncorhynchus mykiss) intestine, to study the bioavailability, bioreactivity, and toxicity of Zn added as an inorganic (ZnSO4) and organic zinc compound (Zn-Bioplex). Our results showed that, before digestion, Zn-Bioplex was more bioavailable than ZnSO4. However, after in vitro digestion, ZnSO4 and Zn-Bioplex accumulated and were transported equally across the RTgutGC cell epithelium. However, Zn-Bioplex was shown to be less bioreactive than ZnSO4, suggesting that peptide complexation might reduce the intracellular release of zinc as shown by a reduced induction of metallothionein and ZnT1 mRNA levels. This novel method shows promise as a standardized in vitro fish digestion model to study the interactions occurring at the lumen of the intestine and the bioavailability and toxicity of digested compounds in the fish gut.

Effect of biochar addition on copper and zinc passivation pathways mediated by humification and microbial community evolution during pig manure composting

The mobility and bioavailability of Cu and Zn are the main threats associated with the land application of pig manure (PM) compost products. This study investigated the impacts of biochar (BC) concentration on passivation of Cu and Zn associated with the compost maturity. The results indicated that 15% and 10% BC favoured the passivation of Cu and Zn, respectively. BC promoted passivation of Cu by accelerating HA production and optimized the abundance of Firmicutes. BC promoted the passivation of Zn by increasing the high temperature peak and the corresponding pH (8–8.5). A higher level (15% and 20%) of BC altered the dominant bacterial phylum from Firmicutes to Proteobacteria. 20% BC inhibited the passivation of Cu and Zn by reducing the highest temperature and lowering the alkalinity of substrate. These results offer new insights into understanding how the addition of BC could reduce the risk of hazardous products during PM composting.

ZnO nanoparticles as potential fertilizer and biostimulant for lettuce

Zn is an indispensable nutrient for crops that usually presents low bioavailability. Different techniques have been proposed to improve the bioavailability of Zn, including the use of nanofertilizers. The objective of the study was to evaluate the applications of drench (D) and foliar (F) ZnO nanoparticles (NZnO) compared to those of ionic Zn2+ (ZnSO4) in lettuce. The plants cv. Great Lakes 407 was produced in pots of 4 L with perlite-peat moss (1:1) under greenhouse conditions. The treatments consisted of NZnO applications that replaced the total Zn provided with a Steiner solution, as follows: Zn2+ (100%D) (control); Zn2+ (50%D+50%F); NZnO (100%D); NZnO (50%D+50%F); NZnO (75%D); NZnO (50%D); NZnO (75%F) and NZnO (50%F). Four applications of Zn were made with a frequency of 15 days. 75 days after transplant (DAP), the fresh and dry biomass, chlorophyll a, b, and β-carotene, phenolics, flavonoids, antioxidant capacity, vitamin C, glutathione, H2O2, total protein, and enzymatic activity of PAL, CAT, APX, and GPX were evaluated. The mineral concentrations (N, P, K, Ca, Mg, S, Cu, Fe, Mn, Mo, Zn, Ni, and Si) in the leaves and roots of plants were also determined. The results showed that, compared to Zn2+, NZnO promoted increases in biomass (14–52%), chlorophylls (32–69%), and antioxidant compounds such as phenolics, flavonoids, and vitamin C. The activity of enzymes like CAT and APX, as well as the foliar concentration of Ca, Mg, S, Fe, Mn, Zn, and Si increased with NZnO. A better response was found in the plants for most variables with foliar applications of NZnO equivalent to 50–75% of the total Zn2+ applied conventionally. These results demonstrate that total replacement of Zn2+ with NZnO is possible, promoting fertilizer efficiency and the nutraceutical quality of lettuce.

Source-soil-rice-human multi-objective optimization to minimize the cadmium intake risk to consumers of field planting rice

Cadmium (Cd) exposure risks to consumers of locally grown rice are often estimated without considering the sources and bioavailability of Cd. Here, we present the first comprehensive and quantitative analysis on the sources and transport of Cd in paddy ecosystems by combining a regional investigation in southern China, a positive matrix factorization algorithm, and a classification and regression tree approach. Results showed that local atmospheric emission regulations failed to mitigate Cd contamination as the Cd inputs from industrial effluent irrigation were largely overlooked. Leaching loss of soil Mn is an invisible threat to grain safety as Mn can exhibit a significant facilitation effect on rice Cd uptake under acidic pH. A probability-based toxicokinetic model is proposed to optimize the strategies for minimizing the Cd body burden through the source-soil-rice-human pathway. Urinary Cd exceeded its safety threshold in 61.7% of local female adults (6.14±4.42 µg g -1 creatinine) who consumed less rice grain but with a low Zn bioavailability. To protect 85% of local rice production from causing excessive Cd exposure risk, irrigation channel needs to be effectively cleaned up, and the pH and amorphous Mn content of rice soils need to be raised to 5.50 and 179 mg kg -1 , respectively. • Contamination sources should not be confused with the causative factors of Cd exposure risks. • Manganese exhibited significant facilitation effect with acidic pH on rice Cd uptake. • Urinary Cd from local adults can be better predicted with probability-based toxicokinetic model. • Optimum scenarios help protect 85% of rice production from causing excessive kidney burden.

Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence.

Previous research studies have confirmed that Zn and Cd are the most predominant heavy metals in the Baiyin district, Gansu province, China. Furthermore, the speciation of Zn and Cd is a key factor in controlling the mobility, bioavailability, and toxicity of metals in Zn/Cd co-contaminated soil. In this study, the speciation of Zn and Cd in different types of agricultural soils including the Yellow River irrigated soil (s3) and sewage irrigated soil (s1 and s2) was investigated and compared by a combination of sequential extraction, bulk X-ray absorption fine structure (XAFS), and micro-X-ray fluorescence (μ-XRF) techniques. The results of the speciation quantified by XAFS were in general agreement with those obtained by sequential extraction, and the combination of both approaches allowed a reliable description of Zn/Cd speciation in soil. The speciation of Zn in the s1 soil exposed around the smelter was similar to speciation of Zn in the sewage irrigated s2 soil. In both soils, Zn was predominantly present as Zn-Al LDH (31-36%), Zn adsorbed on calcite (37-47%), and primary minerals (14-18% sphalerite and 9% franklinite). In contrast, the proportions of organic Zn (23%) and Zn-Al LDH (53%) were significantly higher in the Yellow River irrigated s3 soil, while that of Zn-calcite (24%) was lower. This indicated that Zn in s3 was less mobile and bioavailable than that in s1 and s2 soils. The content of bioavailable Zn in s3 was much lower than the background value and Zn did not pose a threat to the Yellow River irrigated soil. In addition, Cd was strongly correlated with Zn content and exhibited a simpler speciation. Cd adsorbed on illite and calcite was found as the major species in both soil types, posing higher migration and toxicity to the environment. Our study reported the speciation and correlation of Zn/Cd in sierozem soil for the first time and provided a significant theoretical basis for remediation actions to minimize Zn/Cd risks.

Studies on Nutritional Profile and Mineral Bioavailability of some Solanum Species Consumed as Fruits in Ekiti State, Nigeria

African eggplants are highly valued constituents of the Nigerian food. However, their nutritional potentials have not been fully tapped due to inadequate information on their nutritional and anti-nutritional qualities. This present study investigated the proximate, minerals, anti-nutrient contents as well as the estimation of mineral ratios and Mineral Safety Index of four selected edible solanum species namely, Solanum anguivi, S. gilo, S. menalogena and S. aethiopicum. The proximate contents (%) ranged from 4.19-5.46 (moisture content), 1.71-2.49 (crude fat), 4.57-5.45 (crude ash), 3.76-4.93 (crude protein), 5.20-6.30 (crude fiber) and 77.14-78.58 (carbohydrate). The solanum species were good sources of energy with total metabolizable energy of 1.458MJ-1.484MJ. The four solanum species contained high K, Ca, Mg, low Fe, Mn, Zn and Cu, while amount of Cd, Ni and Pb were very low. The mineral ratios of K/Na, Ca/Mg, Ca/K, Zn/Cu and [K/(Ca+Mg)] were below the minimum good ratios levels of 1.0, 4.17, 4.0, 8.0 and 2.2 respectively which are good for man. The anti-nutrient contents revealed low phytate, oxalate and cyanide levels. The calculated Phytate/Zn, Phytate/Ca and Oxalate/Ca were lower than the threshold levels and would support absorption and bioavailability of Zn and Ca in the samples while that of Phytate/Fe was above the critical value and this indicates unavailability of iron in these eggplant fruits. The mineral differences observed showed that S. menalogena and S. aethiopicum had greater minerals while the Mineral Safety Index results revealed that the body could not be overloaded with any of the minerals investigated. The eggplants are rich in fiber, ash, carbohydrate and minerals with moderate protein. The low level of the anti-nutrient is good and poses no deleterious effect when consumed. The eggplants have nutritional health benefits; hence, their consumption should be encouraged to address food insecurity in Nigeria

Soil properties influence the toxicity and availability of Zn from ZnO nanoparticles to earthworms

To develop models that support site-specific risk assessment for nanoparticles (NPs), a better understanding of how NP transformation processes, bioavailability and toxicity are influenced by soil properties is needed. In this study, the influence of differing soil properties on the bioavailability and toxicity of zinc oxide (ZnO) NPs and ionic Zn to the earthworm Eisenia fetida was investigated. Earthworms were exposed to ZnO_NPs and ionic Zn, between 100 and 4400 mg Zn/kg, in four different natural soils (organic matter content: 1.8–16.7%, soil pH: 5.4–8.3, representing sandy loam to calcareous soils). Survival and reproduction were assessed after 28 and 56 days, respectively. Zn concentrations in soil pore waters were measured while labile concentrations of Zn were measured using an in-situ dynamic speciation technique (diffusive gradient in thin films, DGT). Earthworm Zn tissue concentrations were also measured. Soil properties influenced earthworm reproduction between soil controls, with highest reproductive output in soils with pH values of 6–7. Toxicity was also influenced by soil properties, with EC50s based on total Zn in soil ranging from 694 to >2200 mg Zn/kg for ZnO_NP and 277–734 mg Zn/kg for ionic Zn. Soil pore water and DGT measurements showed good agreement in the relative amount of Zn extracted across the four soils. Earthworms exposed to ZnO_NPs survived higher Zn concentrations in the soils and had higher tissue concentrations compared with ionic Zn exposures, particularly in the high organic content calcareous soil. These higher tissue concentrations in ZnO_NP exposed earthworm could have consequences for the persistence and trophic mobility of Zn in terrestrial systems and need to be further investigated to elucidate if there any longer-term risks associated with sustained input of ZnO_NP to soil.