Doses Of Zn Research Articles

Zinc amendment as an effective tool in the management of cadmium toxicity: a case study with Amaranthus cruentus L

The unmanaged waste disposal, coupled with the increased industrialization and urbanization, has aggravated the problem of heavy metal contamination in the environment, especially in the agricultural soils. In view of this, the present study was planned to evaluate the effectiveness of zinc (Zn) in the amelioration of cadmium (Cd) toxicity in plants, thereby sustaining the crop productivity in near future. The experiment was performed in two parts. The first part focused on calculating the EC50 (half-effective concentration) of Cd, for which the potted experimental plants (Amaranthus cruentus L.) were treated with different doses of Cd (10, 20, 30, 40, and 50 mgL−1). In the second part, the EC50 Cd dose was combined with different Zn doses (100, 200, 300, 400, and 500 mgL−1) and the effect of Zn supplementation on Cd exposed plants was studied by evaluating the response of different biochemical, physiological and yield parameters. The EC50 Cd dose was calculated to be 26.5 mgL−1. Plant yield increased significantly with reduced Zn dosages. Biochemical parameters improved more than physiological parameters after Zn treatment in Cd-stressed plants. At higher Zn doses, its toxic effects exacerbate Cd toxicity. The study indicates that Zn partially decreases Cd toxicity in Amaranthus plants. The results suggest that 300 mgL−1 Zn dose was sufficient to bring about maximum recorded mitigation of Cd toxicity. However, since the synergistic effects of high doses of Zn with Cd cannot be ruled out, the selection of the applied Zn dose should be carefully selected.

Comparative analysis of cyto-genotoxicity of zinc using the comet assay and chromosomal abnormality test.

In this study, the toxicity of the trace element zinc (Zn) in Allium cepa L. test material was examined. Toxicity was investigated in terms of physiological, cytogenetic, biochemical, and anatomical aspects. Germination percentage, root length, weight gain, mitotic index (MI), micronucleus (MN) frequency, chromosomal abnormalities (CAs), malondialdehyde (MDA), proline and chlorophyll levels, superoxide dismutase (SOD) and catalase (CAT) enzyme activities, and meristematic cell damage were used as indicators of toxicity. Additionally, the comet test was used to measure the degree of DNA damage. Four groups of A. cepa bulbs-one for control and three for applications-were created. While the bulbs in the treatment groups were germinated with Zn at concentrations of 35, 70, and 140mg/L, the bulbs in the control group were germinated with tap water. Germination was carried out at room temperature for 72h and 144h. When the allotted time was over, the root tips and leaf samples were collected and prepared for spectrophotometric measurements and macroscopic-microscopic examinations. Consequently, Zn treatment led to significant reductions in physiological indicators such as weight gain, root length, and germination percentage. Zn exposure caused genotoxicity by decreasing the MI ratios and increasing the frequency of MN and CAs (p < 0.05). Zn promoted various types of CAs in root tip cells. The most observed of CAs was the sticky chromosome. Depending on the dose, Zn was found to cause an increase in tail lengths in comet analyses, which led to DNA damage. Exposure to Zn led to a significant decrease in chlorophyll levels and an increase in MDA and proline levels. It also promoted significant increases in SOD and CAT enzyme activities up to 70mg/L dose and statistically significant decreases at 140mg/L dose. Additionally, Zn exposure caused different types of anatomical damage. The most severe ones are epidermis and cortex cell damage. Besides, it was found that the Zn dose directly relates to all of the increases and decreases in physiological, cytogenetic, biochemical, and anatomical parameters that were seen as a result of Zn exposure. As a result, it has been determined that the Zn element, which is absolutely necessary in trace amounts for the continuation of the metabolic activities of the organisms, can cause toxicity if it reaches excessive levels.

Two Doses of Zn Induced Different Microbiota Profiles and Dietary Zinc Supplementation Affects the Intestinal Microbial Profile, Intestinal Microarchitecture and Immune Response in Pigeons.

We aimed to explore the effects of two different doses of Zn on the fecal microbiota in pigeons and the correlation between these effects and intestinal immune status. Zn doses affected pigeon growth performance, and pigeons in the T60 (60 mg/kg Zn) and T90 (90 mg/kg Zn) groups exhibited higher villus height and crypt depth in duodenum and ileum compared to the control group, respectively. Supplementation with Zn increased the expression of the IL8, CD798, TJP and NKTR genes (p < 0.05), while enhancing serum immunoglobulin (Ig) G, IgM, and IgA concentrations compared to the control pigeons (p < 0.05). T60 treatment reduced relative Actinobacteriota abundance, while Lactobacillus spp. abundance was highest in the T90 group compared to the two other groups. The core functional genera significantly associated with immune indices in these pigeons were Rhodococcus erythropolis and Lactobacillus ponti. Our findings will help facilitate the application of dietary Zn intake in pig production.

Soil micronutrients (Zn and Fe) fractions and response of rice (Oryza Sativa) in different soil of Haryana under rice-wheat cropping system

The significance of zinc and iron in crop production, particularly in rice-wheat cropping systems, has been increasingly recognized. The present study aimed to determine the effect of different soil samples collected from the rice-wheat cropping system of Haryana with different soil texture on rice grain yield and micronutrient content using a greenhouse trial with four levels of Fe (0, 25, 50 mg kg−1 as soil and 0.5% foliar spray of FeSO4 at 45 DAS) and four levels of Zn (0, 5, 10 mg kg−1 as soil and 0.5% foliar spray of ZnSO4 at 35 DAS). This study discovered that rice grain yield showed a positive correlation with soil Zn and Fe concentrations in soil before sowing and a negative correlation with soil Fe and Zn concentrations in soil after crop harvesting. In most of the soils studied, foliar spray alone Fe @ 0.5% foliar (45 DAS) and Zn @ 0.5% foliar (35 DAS) improved Fe and Zn concentrations in rice significantly more than soil application of 25 mg Fe kg−1 and 5 mg Zn kg−1, respectively. The rice grain yield in clay soil was 14-42% higher than in sandy soil with different doses of Zn and Fe application. The order of preponderance of different Fe and Zn fractions were CA-Fe < OM-Fe < EX-Fe < FeMnOX-Fe < Res-Fe and Res-Zn > FeMnOX-Zn > OM-Zn > CA-Zn > Ex-Zn in the soils, respectively. Conclusively, concomitant consideration of grain yield and grain Zn and Fe concentrations of rice are the sustainable approach toward food targets achievement.

Viability and life cycle assessment of Fuller's Earth as a low-cost adsorbent for zinc removal from aqueous solutions: Operating parameters, removal mechanisms and environmental impacts

Zinc is a heavy metal that has several health risks and must be removed from wastewater effluents before discharge to water bodies or reuse. Fuller's earth is a sedimentary clay and characterized by its low cost and availability. In this research, Fuller's earth (FE) was investigated as an adsorbent for the Zinc (Zn) removal from aqueous solutions to understand its performance, the mechanism of removal, and the potential environmental impacts. Life cycle assessment (LCA) was conducted using ReCiPe 2016 midpoint method. Zn adsorption studies on FE were conducted at various pH (2.5–9), temperatures (10°C, 25°C, and 40°C), initial concentrations of Zn (25, - 150 mg/L) and adsorbent doses of (0.25–4 g/ 50 ml). The Zn removal efficiency reached 99% at pH = 9 at an initial Zn concentration = 100 mg/L and the adsorbent dose = 0.25 g/ 50 ml. The experimental data fit into the Temkin isotherm, while kinetics were best expressed by pseudo-second order. The controlling step of the adsorption process was the film diffusion according to Boyd model. Thermodynamic experiments showed that adsorption is endothermic with an accompanying rise in randomness in the system. The adsorption capacity was 3.56 mg/g. Images by SEM confirmed the occurrence of adsorption. The desorption was successful at different concentrations of HCl. LCA results showed that the maximum negative and positive environmental impacts were associated with mineral resource scarcity (7.5*10–5 kg Cu eq) and human non-carcinogenic toxicity (−0.821 kg 1,4-DCB), respectively.

Interactions between maternal parity and feed additives drive the composition of pig gut microbiomes in the post-weaning period

BackgroundNursery pigs undergo stressors in the post-weaning period that result in production and welfare challenges. These challenges disproportionately impact the offspring of primiparous sows compared to those of multiparous counterparts. Little is known regarding potential interactions between parity and feed additives in the post-weaning period and their effects on nursery pig microbiomes. Therefore, the objective of this study was to investigate the effects of maternal parity on sow and offspring microbiomes and the influence of sow parity on pig fecal microbiome and performance in response to a prebiotic post-weaning. At weaning, piglets were allotted into three treatment groups: a standard nursery diet including pharmacological doses of Zn and Cu (Con), a group fed a commercial prebiotic only (Preb) based on an Aspergillus oryzae fermentation extract, and a group fed the same prebiotic plus Zn and Cu (Preb + ZnCu).ResultsAlthough there were no differences in vaginal microbiome composition between primiparous and multiparous sows, fecal microbiome composition was different (R2 = 0.02, P = 0.03). The fecal microbiomes of primiparous offspring displayed significantly higher bacterial diversity compared to multiparous offspring at d 0 and d 21 postweaning (P < 0.01), with differences in community composition observed at d 21 (R2 = 0.03, P = 0.04). When analyzing the effects of maternal parity within each treatment, only the Preb diet triggered significant microbiome distinctions between primiparous and multiparous offspring (d 21: R2 = 0.13, P = 0.01; d 42: R2 = 0.19, P = 0.001). Compositional differences in pig fecal microbiomes between treatments were observed only at d 21 (R2 = 0.12, P = 0.001). Pigs in the Con group gained significantly more weight throughout the nursery period when compared to those in the Preb + ZnCu group.ConclusionsNursery pig gut microbiome composition was influenced by supplementation with an Aspergillus oryzae fermentation extract, with varying effects on performance when combined with pharmacological levels of Zn and Cu or for offspring of different maternal parity groups. These results indicate that the development of nursery pig gut microbiomes is shaped by maternal parity and potential interactions with the effects of dietary feed additives.

Assessment of Zn and Cu in piglets' liver and kidney: impact in fecal Enterococcus spp.?

Zinc and copper have been used as growth promotors in alternative to antibiotics in pig's diet. The aim was the ascertainment of the Zn and Cu concentrations in piglets' liver and kidney and their impact in the reduced susceptibility to Zn, Cu, and antibiotics in enterococci, used as microbiota biomarker. Zn and Cu were determined in the livers and kidneys of 43 piglets slaughtered in Portugal, by flame atomic absorption spectrometry. Enterococci were isolated from feces for determining the identification of species (E. faecalis, E. faecium, and Enterococcus spp.); susceptibility to vancomycin, ciprofloxacin, linezolid, tigecycline, ampicillin, imipenem, and metals; and Cu tolerance genes. In piglets with Zn and Cu high or toxic levels, enterococci had reduced susceptibility to ions, reinforced by the presence of Cu tolerance genes and by resistance to antibiotics. The study relevance is to show the relationship between these metals' levels and decreased susceptibility to Cu, Zn, and antibiotics by enterococci. From the results, it could be supposed that the piglets were being fed with high doses of Zn and Cu which could select more resistant bacteria to both antibiotics and metals that could spread to environment and humans.

Upregulation of antioxidant enzymes contribute to the elevated tolerance of Juncus acutus offspring from metal contaminated environments

Long-term environmental exposure to metals e.g. zinc (Zn), may allow saltmarsh halophytes to develop metal tolerance to improve the chance of survival of their progeny in future metal-contaminated scenarios. Juncus acutus seeds were collected from mature parents (F0) inhabiting a legacy Zn-contaminated location (Cockle Creek) and an uncontaminated reference location (Swansea) of Lake Macquarie, NSW, Australia. Seeds (J. acutus) were exposed to Zn (0.00 mM (control), 0.01 mM (effective concentration, EC10) and 0.74 mM (EC50)) and resultant germinants (F1) were allowed to grow until 15 days. Seedling growth parameters i.e. biomass, root length and 1st leaf length, and seedling biochemical responses i.e. superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) antioxidant enzyme activity and lipid peroxidation products, malondialdehyde (MDA), were examined in order to assess if enzymes may be implicated in conferring tolerance to the offspring of metal-exposed parents. Control locations exhibited significantly greater declines in biomass and root length with Zn dose compared to seed from contaminated locations, suggesting F1 offspring from contaminated parents were conferred tolerance to Zn. Furthermore, significant upregulation of CAT and GPx enzymes were evident in the seedlings derived from parents of contaminated locations. These are the antioxidative enzymes responsible for minimizing metal-induced oxidative stress, and may, in part, be responsible for increasing seedling fitness and observed tolerance.

Agronomic biofortification of zinc in tomato

Zinc (Zn) deficiency is a major public health issue worldwide. The biofortification of Zn in popular vegetables could be a promising way to address this burning issue. To enrich tomatoes with bioavailable Zinc through agronomic biofortification. Seven tomato varieties were examined to identify the best one for Zn biofortification based on fruit Zn concentrations. Then six levels of Zn viz., 0, 2, 3, 4, 5, and 6 kg ha−1 were applied to screen out the best Zn dose for maximum biofortification. Finally, the identified Zn dose was applied using six strategies viz., 100% seedling priming, 50% soil + 50% foliar spray at seedling stage, 50% seedling priming + 50% foliar spray, 100% foliar spray at seedling stage, 100% foliar spray at flowering stage and 100% foliar spray at the fruiting stage to recognize the best application strategy. These three experiments were executed following a completely randomized design with three replications. In screening, BARI Tomato-14 showed the lowest Zn concentration compared to all other varieties. The application of 5 kg Zn ha−1 showed the highest Zn concentration in tomato with better yield and quality. Finally, 5 kg Zn ha−1 as 50% soil application + 50% foliar spray showed the maximum biofortification of Zn in BARI Tomato-14 with the highest growth, yield and quality. Therefore, application of 5 kg Zn ha−1 as 50% soil and 50% foliar spray on BARI tomato-14 could be a potential option to mitigate Zn deficiency.

Changes in the cellulolytic activity and microbial respiration of soils of different types under conditions of contamination with heavy metals

It has been experimentally established that when soils are polluted with heavy metals, the boundary concentrations of metals above which signs of ecotoxicity are detected are different for the microbial community. Inhibition of respiration of the studied soils was observed at lower doses of Pb, Zn and Cd than enzymatic cellulase activity. Cd compounds and polyelement contamination conditions are the most toxic for microorganisms. Concentrations of heavy metals have been identified that can have a significant negative impact on the soil microbial community at different levels of contamination of sod-podzolic, gray forest, leached chernozem and chestnut soils. In descending order of resistance to TM, the studied soils can be arranged in the following row: leached chernozem (Luvic Chernozem) grey forest (Eutric Retisol (Ochric)) chestnut (Haplic Kastanozem) ≥ sod-podzolic (Eutric Albic Retisol (Ochric)).

Effect of split application of NPK along with basal dose of Zn and B on yield of sapota [Manilkara achras (Mill.) Forsberg] and soil properties

Effect of split application of NPK along with basal dose of Zn and B on yield of sapota [Manilkara achras (Mill.) Forsberg] and soil properties

Optimizing the Zn, Mn, and Fe mineral dose as tank mix foliar application for improvement of fruit yield, quality, and uptake of nutrients in the kinnow mandarin

Kinnow production is hampered due to the lack of micronutrient applications such as zinc (Zn), iron (Fe), and manganese (Mn), which play a significant role in the metabolic activities of the plant, affecting yield and quality. The farmers of the region use mineral micronutrient fertilizers, but it leads to phytotoxicity due to unoptimized fertilizer application dose. In the present investigation, an attempt has been made to optimize the Zn, Mn, and Fe minerals dose as tank mix foliar application for improvement of fruit yield, quality, and uptake of nutrients. The twelve combinations of different doses of zinc sulphate, manganese sulphate, and ferrous sulphate fertilizers replicated three times were tested at kinnow orchards established at Krishi Vigyan Kendra, Bathinda, Punjab, India. The data revealed that the fruit drop was significantly low in the treatment F12 (43.4%) (tank mix spray of 0.3% ZnSO4 + 0.2% MnSO4 + 0.1% FeSO4 ) compared to control treatment. The fruit yield per tree was significantly higher in the treatment F12 compared to untreated control. The juice percentage was also recorded higher in treatment F12 as compared to control, and the juice percentage improved by 2.6%. The leaf nutrient analysis also revealed translocation of higher amount of nutrient from leaf to fruit under optimized supply of micronutrient. Thus, the application of tank mix spray of 0.3% ZnSO4 + 0.2% MnSO4 + 0.1% FeSO4 may be used for better fruit yield and quality.

Effect of Zinc Oxide and Copper Sulfate on Antibiotic Resistance Plasmid Transfer in Escherichia coli.

Heavy metals such as zinc (Zn) and copper (Cu) may be associated with antibiotic resistance dissemination. Our aim was to investigate whether sub-lethal dosage of Zn and Cu may enhance plasmid transfer and subsequently resistance genes dissemination. Plasmid conjugation frequencies (PCF) were performed with Escherichia coli strains bearing IncL-blaOXA-48, IncA/C-blaCMY-2, IncI1-blaCTX-M-1, IncF-blaCTX-M-1, and IncX3-blaNDM-5 as donors. Mating-out assays were performed with sub-dosages of zinc oxide (ZnO) and Cu sulfate (CuSO4). Quantification of the SOS response-associated gene expression levels and of the production of reactive oxygen species were determined. Increased PCF was observed for IncL, IncA/C, and IncX3 when treated with ZnO. PCF was only increased for IncL when treated with CuSO4. The ROS production presented an overall positive correlation with PCF after treatment with ZnO for IncL, IncA/C, and IncX3. For CuSO4 treatment, the same was observed only for IncL. No increase was observed for expression of SOS response-associated genes under CuSO4 treatment, and under ZnO treatment, we observed an increase in SOS response-associated genes only for IncX3. Our data showed that sub-dosages of ZnO and CuSO4 could significantly enhance PCF in E. coli, with a more marked effect observed with IncL, IncA/C, and IncX3 scaffolds. Our study suggested that use of certain heavy metals is not the panacea for avoiding use of antibiotics in order to prevent the dissemination of antibiotic resistance.

Zinc Supplementation in Very Low Birth Weight Infants: A Randomized Controlled Trial.

Preterm infants have high zinc (Zn) requirements and are generally believed to be in a negative Zn balance in the early period of life. In this study, we aimed to investigate the effect of high-dose Zn supplementation in very low birth weight (VLBW: infants with birth weight < 1.5 kg) infants on feeding intolerance and development of mortality and/or morbidities including necrotizing enterocolitis (NEC) and late-onset sepsis (LOS). This is a prospective randomized trial. VLBW preterm infants with gestational age of <32 weeks were randomly allocated on the seventh day of life to receive extra amount of supplemental Zn along with the enteral feedings (9 + 3 mg), besides regular low-dose supplementation (3 mg), from enrollment until discharge. Outcome measures were feeding intolerance, NEC (stage ≥ 2), LOS, and mortality. A total of 195 infants (97 from study group and 98 from control group) were analyzed. A total of 46 (47.4%) infants in the study group and 64 (65.3%) infants in the control group ended up with feeding intolerance (p = 0.012). NEC was observed in 11 infants (11.2%) in the control group and only 1 infant (1%) in the study group (p = 0.003). There was a negative correlation between high-dose Zn supplementation and number of culture-proven LOS episodes (p = 0.041). This significance was also present for clinical sepsis, being higher in the control group (p = 0.029). No relationship between high-dose Zn supplementation and mortality and other morbidities (hemodynamically significant patent ductus arteriosus, bronchopulmonary dysplasia, retinopathy of prematurity, and severe intraventricular hemorrhage) was observed. Zn supplementation for VLBW infants is found to be effective to decrease feeding intolerance, NEC, and LOS episodes in this vulnerable population. Current data support the supplementation of VLBW infants with higher than regular dose of Zn. · Higher dose of Zn supplementation is shown to be a beneficial intervention in VLBW infants.. · Zn may decrease feeding intolerance, sepsis or NEC.. · Higher than regular dose of Zn seems to be safe..

Effect of Frequency and Rate of Zinc Application on Nodulation, Chlorophyll Content, Yield, and Quality of Soybean Grown in a Vertisol of Jabalpur, Madhya Pradesh, India

Zinc (Zn) fertilizer is commonly used in nutrient intensively cultivated deficient soils of central, India. Zn is a structural components of plants. However, little is known, on optimum dose of Zn especially in a vertisol of Jabalpur district. This study was required to find out Zn dose for sustainable productivity and maintenance of soil fertility. The study comprised of three frequency levels, Zn application in 1st year only, Zn application in alternate year, and Zn application in every years and five rates of Zn, (0, 2.5, 5.0, 7.5, and 10.0 kg Zn ha-1) was applied in Kharif season. The result of analysis revealed that the highest symbiotic traits viz., nodule number of 36.78, fresh and dry weight (1.09 and 0.31 g plant-1) were found with application of 5 kg Zn ha-1 at 45 DAS at alternate year. The highest SPAD score of 44.98 and relative water content of 62.41 % was recorded with 5 kg Zn ha-1 at 60 DAS and found significant at alternate year. The Zn addition @ 5.0 kg ha⁻¹ through ZnSO4.7H2O to soybean in alternate year which increased by 1.28 to 1.53 (19.53 %) over only single year Zn addition. This was the best practice in a typic haplusterts as it resulted in an average production of 1.54 t ha-1 of seed yield ha⁻¹ over no zinc application (1.24 t ha-1) which increased by 24.19 %. The zinc application improved quality of seed in terms of oil and protein over control. So it was concluded that Zn application at alternate year and 5 kg Zn ha-1 for increasing yield and quality of soybean in a vertisol of Jabalpur district.

Exogenous Zinc Application and Generative Traits of Three Local Shallot Varieties

Increasing shallot (Allium ascalonicum L.) production can be done by application of botanical or true shallot seeds (TSS). Meanwhile, it is well understood that botanical seeds are difficult to produce due to shallots' low flowering capacity. This study aimed to evaluate the generative traits of three local shallot varieties affected by various doses of zinc (Zn). This study was structured using a split-plot design, where the main plots were varieties (Lokana, Rubaru, and Ambassador 3 Agrihorti). In addition, the sub-plot treatment, the dose of zinc (0, 0.5, 1, and 1.5 kg ha-1), was repeated three times. There is an effect of the main factor (variety) where Rubaru and Ambassador 3 Agrihorti show the fastest umbel emergence. In addition, our data show the interaction effects on the age of sheat breaking, flower blooming (DAP), morphology traits of generative organs, and leaf traits. In detail, Lokana with a Zn dose of 1.5 ha-1 shows the best results on the length and diameter of the umbel stalk; Rubaru with Zn 1 kg ha-1 on the age of broken sheath and chlorophyll index; and the Ambassador 3 Agrihorti with Zn 0.5 kg ha-1 on the number of flowers. On the one hand, it can be concluded that each variety responded differently to the dose of Zn. Concerning seed production, on the other hand, the Ambassador 3 Agrihorti with Zn 0.5 kg ha-1 has better potential to be developed for TSS, as seen from the number of flowers per umbel, a higher percentage of flowering plants and a relatively fast flowering time than other varieties.

The Effects of Foliar Salicylic Acid and Zinc Treatments on Proline, Carotenoid, and Chlorophyll Content and Anti-Oxidant Enzyme Activity in Galanthus elwesii Hook

Galanthus elwesii Hook. is an important plant species of the Amaryllidaceae family and is used for the medicinal purposes of its valuable bioactive compounds. The present study was conducted to investigate the effects of foliar salicylic acid (SA) and zinc (Zn) treatments on the proline, carotenoid, and chlorophyll content and the anti-oxidant enzyme activity in G. elwesii. The ascorbate peroxidase (APX) enzyme activity, catalase (CAT) enzyme activity, and protein contents were determined with ascorbate oxidation, hydrogen peroxide (H2O2), and Bradford experiments, respectively. The plants were treated with three different concentrations of SA (0.5, 1, and 2 mM) and Zn (40, 80, and 120 mM) and were compared with the control. Fresh leaves were harvested in the study. APX (3.99 ± 0.58 EU/mg protein) and CAT (154.64 ± 4.10 EU/mg protein) were obtained from Zn 80 and 120 mM treatments at the highest level, respectively. The proline, chlorophyll b, and carotenoid content increased 12.4, 1.54, and 3.95-fold, respectively, in 0.5 mM SA treatments, when matched with the control group. It was found that increasing doses of SA and Zn increased the content of malondialdehyde (MDA), but this was not at a significant level. The total chlorophyll content increased 2.27-fold in Zn 120 mM + SA 2 mM treatment and the chlorophyll content increased 2.41-fold in Zn 40 mM + SA 1 mM treatment.

An improved comprehensive model for assessing the heavy metals exposure towards waterbirds: A case report from Black-necked cranes (Grus nigricollis) in Caohai Wetland, China

Heavy metal contamination poses a significant environmental threat to wildlife on global scale, making accurate assessment of exposure risk crucial for conservation efforts, particularly for vulnerable species. Existing risk assessment models have been widely used, but their construction process lacks comprehensive considerations. In this study, we constructed an optimized health risk assessment model based on the well-established "Liu's model" and "ADI model", and applied the pollution allocation factor (AF) to accurately assess the risk of heavy metal exposure to wildlife. Our model was applied to assess exposure risk of heavy metal for the black-necked crane(Grus nigricollis), a flagship species in the alpine wetland ecosystem of Caohai Wetland. Soil, plant and black-necked crane fecal samples were collected from the Caohai Wetland and surrounding areas in Guizhou, China. We revealed varying degrees of As, Cd, Cr, Ni, Pb, and Zn contamination in soil and plants from different habitats, exceeding the background or plant limit values. This indicated that the black-necked crane and other waterbirds living in Caohai Wetland are suffering with the multi-elemental heavy metal contamination, especially in the gutterway and grassland. The exposure dose of As, Cd, Cr, Ni, Cu, and Zn toward black-necked cranes differed significantly in soil and plant pathways (P < 0.05). As, Cd, Cu, and Zn were mainly derived from plants consumption, while Cr and Ni originated from soil. Considering the contribution of soil and plant pathways to heavy metal exposure in black-necked cranes, the exposure doses of each elements calculated via food intake accounted for over half of the exposure calculated via feces (AF>0.5). The risk assessment model identified Cr and Pb were the highest risk elements for black-necked cranes, with exposure risk simulated through feces exceeding those through food. These findings suggested that current Liu's model may underestimate the effects of other pathways and medium. Therefore, we proposed a more comprehensive and accurate model for evaluating the exposure risk of black-necked cranes, incorporating AF to quantify the contribution of risk sources to black-necked cranes and understand their overall health risk. This model can serve as a useful tool for the conservation and habitat quality improvement of the black-necked cranes and other waterbirds.

The Content, Uptake and Bioaccumulation Factor of Copper and Nickel in Grass Depending on Zinc Application and Organic Fertilization

Different content of Zn in the soil and organic fertilization can affect micronutrient uptake by plants. A pot experiment was carried out to determine the impact of increasing Zn application rates, i.e., 200, 400 and 600 Zn mg·kg−1, in combination with bovine and chicken manures and mushroom substrate on Cu and Ni content, uptake and bioaccumulation factor in cocksfoot (Dactylis glomerata L.). Control objects without Zn and organic fertilizers and after application of only different Zn doses and only organic fertilizers were also tested. Application of Zn at 400 and 600 mg·kg−1 significantly decreased the content, uptake and value of bioaccumulation factor of Cu in the grass. Different Zn doses were not found to influence the content and bioaccumulation factor of Ni in cocksfoot, but application at 200 Zn mg·kg−1 increased Ni uptake. Chicken manure increased the content and bioaccumulation factor of Cu and Ni in the test plant, and all the organic fertilizers increased their uptake. Cocksfoot showed no tendency to excessive bioaccumulation of Cu and Ni.

Urinary essential and toxic metal mixtures, and type 2 diabetes mellitus: Telomere shortening as an intermediary factor?

The joint effect of metal mixtures on telomere function and type 2 diabetes mellitus (T2DM) is unclear. This large-scale cross-sectional study sought to assess the role of telomere length (TL) in the relationship between urinary essential and toxic metal mixtures, and T2DM in 7410 Chinese adults ≥ 60 years of age. Essential (Cr, Cu, Zn, Se) and non-essential metals (V, Al, Sb, Sn, Cd, Pb) in urine samples were quantified, while leukocyte TL was measured from blood samples. Restricted cubic splines regression showed nonlinear relationships between single metal and T2DM, and between TL and T2DM. Bayesian kernel machine regression and quantile-based g-computation showed that the overall status of urinary metals was positively associated with risk of developing T2DM, which was mainly explained by exposure to Pb, Cd, and Sb, excessive Se intake, and high excretion of Zn. Mediation analyses showed that shortened TL mediated 27.9% of the overall positive effect of metal exposure on T2DM, and this mediation was mainly explained by toxic metal exposure and excessive Se intake. Tobacco smoke exposure, extensive cooking at home, and black tea consumption were found to be important contributors of toxic metal exposures. Further studies are needed to explore the recommended Zn dosage for T2DM patients at different stages, which may ameliorate pancreatic senescence and glycemic progression.