Μg Cd Research Articles

Cadmium in Market Pork Kidneys: A Study on Cadmium Bioavailability and the Health Effects Based on Mouse Models.

Edible offal of farmed animals can accumulate cadmium (Cd). However, no studies have investigated Cd bioavailability and its health effects. Here, based on mouse models, market pork kidney samples exhibited high Cd relative bioavailability of 74.5 ± 11.2% (n = 26), close to 83.8 ± 7.80% in Cd-rice (n = 5). This was mainly due to high vitamin D3 content in pork kidney, causing 1.7-2.3-fold up-regulated expression of duodenal Ca transporter genes in mice fed pork kidney compared to mice fed Cd-rice, favoring Cd intestinal absorption via Ca transporters. However, although pork kidney was high in Cd bioavailability, subchronic low-dose (5% in diet) consumption of two pork kidney samples having 0.48 and 0.97 μg Cd g-1 dw over 35 d did not lead to significant Cd accumulation in the tissue of mice fed Cd-free rice but instead remarkably decreased Cd accumulation in the tissue of mice fed Cd-rice (0.48 μg Cd g-1) by ∼50% and increased abundance of gut probiotics (Faecalibaculum and Lactobacillus). Overall, this study contributed to our understanding of the bioavailability and health effects associated with Cd in edible offal, providing mechanistic insights into pork kidney consumption safety based on Cd bioavailability.

A novel process for recovering Cd from the biomass of the hyperaccumulator Celosia argentea Linn

Safe disposal of harvested metal-rich biomass is challenging for phytoextraction. This study designed and optimized a novel process for recovering cadmium (Cd) from the harvested biomass of the hyperaccumulator plant Celosia argentea Linn. The biomass was pyrolyzed at an optimum temperature of 350 ℃, where weight was lost by 59.7 %, and Cd (85.1 %) remained in the pyrolysis residue. X-ray diffraction analysis showed that the Cd in the residue mainly existed as Cd2(OH)3Cl and CdMn2O4. The pyrolysis residue was leached with H2SO4 at pH 0.5, and the highest Cd leaching ratio (91.1 %) was achieved. Manganese powder replaced over 91.3 % of the Cd in the leachate at room temperature for 2 h, yielding sponge Cd with a purity of 82.2 %. Approximately 190 mg of sponge Cd was recovered from 1 kg of biomass containing 269 mg·kg−1 Cd, with a total Cd recovery ratio of 70.7 %. These results indicate that the production of Cd sponges from Cd-rich biomass is feasible. This process, which mainly includes pyrolysis, leaching, and replacement, provides a potential method for safely disposing and utilizing Cd-rich biomass.

Determination of arsenic and cadmium uptake by rice from topsoil

AbstractTopsoil is the main sink of various pollutants and the direct source of heavy metal uptake by crops. In a 2‐year field experiment conducted in central China from 2016 to 2017, the significant role of topsoil in pollutant absorption, in particular the arsenic (As) and cadmium (Cd) uptake in rice was examined quantitatively. Two soil treatments, removing half of the topsoil (TR) and a control (CK), were applied alongside two rice varieties ‐ Huanghuazhan (HHZ, indica inbred) and Yangliangyou6 (YLY6, indica hybrid). On average, TR reduced the As and Cd concentrations in grain by 10.0% and 56.2%, respectively. The reduction was linked to lower pollutant concentrations in soil above the hardpan and rice straw. TR also decreased shoot As and Cd accumulation by 30.7% and 67.8% at maturity, with topsoil at 12–15 cm depth contributing an average of 2372 μg As m−2 (30.1%) and 138 μg Cd m−2 (66.1%) to total uptake of As and Cd, respectively. Contribution of topsoil to total As uptake remained consistent across growing stages, while for Cd, topsoil contributed 24.8% before heading and 81.2% after. Moreover, varietal differences were observed, with TR significantly reducing grain As and Cd concentrations of YLY6 but no difference in HHZ. This study quantifies topsoil's impact on As and Cd uptake in rice, and underscores genotypic variations in their response to topsoil removal.

Systematic evaluation of methods for iron-impregnation of biochar and effects on arsenic in flooded soils.

There is a need for innovative strategies to decrease the mobility of metal(loids) including arsenic (As) and cadmium (Cd) in agricultural soils, including rice paddies, so as to minimize dietary exposure to these toxic elements. Iron (Fe)-modified biochars (FBCs) are used to immobilize As and Cd in soil-water systems, but there is a lack of clarity on optimal methods for preparing FBCs because there are only limited studies that directly compare BCs impregnated with Fe under different conditions. There is also a lack of information on the long-term performance of FBCs in flooded soil environments, where reductive dissolution of Fe (oxy)hydroxide phases loaded onto biochar surfaces may decrease the effectiveness of FBCs. This study uses material characterization methods including FTIR, SEM-EDX, BET, and adsorption isotherm experiments to investigate the effects of Fe-impregnation methods (pH, pyrolysis sequence, and sonication) on the morphology and mineralogy of Fe loaded onto the biochar surface, and to FBC adsorbent properties for arsenate (As(V)), arsenite (As(III)), and Cd. Acidic impregnation conditions favored the adsorption of As(III) onto amorphous Fe phases that were evenly distributed on the biochar surface, including within the biochar pore structure. The combination of sonication with acidic Fe-impregnation conditions led to the best adsorption capacities for As(V) and As(III) (4830 and 11,166 μg As g-1 biochar, respectively). Alkaline Fe-impregnation conditions led to the highest Cd adsorption capacity of 3054 μg Cd g-1 biochar, but had poor effectiveness as an As adsorbent. Amending soil with 5% (w/w) of an acid-impregnated and sonicated FBC was more effective than an alkaline-impregnated FBC or ferrihydrite in decreasing porewater As concentrations. The acid-impregnated FBC also had greater longevity, decreasing As by 54% and 56% in two flooded phases, probably due to the greater stability of Fe(III) within the biochar pore structure that may have a direct chemical bond to the biochar surface. This study demonstrates that FBCs can be designed with selectivity towards different As species or Cd and that they can maintain their effectiveness under anaerobic soil conditions. This is the first study to systematically test how impregnation conditions affect the stability of FBCs in soils under multiple drying-rewetting cycles.

Trichoderma Inoculation Alleviates Cd and Pb-Induced Toxicity and Improves Growth and Physiology of Vigna radiata (L.).

Heavy metals (HMs) pose a serious threat to agricultural productivity. Therefore, there is a need to find sustainable approaches to combat HM stressors in agriculture. In this study, we isolated Trichoderma sp. TF-13 from metal-polluted rhizospheric soil, which has the ability to resist 1600 and 1200 μg mL-1 cadmium (Cd) and lead (Pb), respectively. Owing to its remarkable metal tolerance, this fungal strain was applied for bioremediation of HMs in Vigna radiata (L.). Strain TF-13 produced siderophore, salicylic acid (SA; 43.4 μg mL-1) and 2,3-DHBA (21.0 μg mL-1), indole-3-acetic acid, ammonia, and ACC deaminase under HM stressed conditions. Increasing concentrations of tested HM ions caused severe reduction in overall growth of plants; however, Trichoderma sp. TF-13 inoculation significantly (p ≤ 0.05) increased the growth and physiological traits of HM-treated V. radiata. Interestingly, Trichoderma sp. TF-13 improved germination rate (10%), root length (26%), root biomass (32%), and vigor index (12%) of V. radiata grown under 25 μg Cd kg-1 soil. Additionally, Trichoderma inoculation showed a significant (p ≤ 0.05) increase in total chlorophyll, chl a, chl b, carotenoid content, root nitrogen (N), and root phosphorus (P) of 100 μg Cd kg-1 soil-treated plants over uninoculated treatment. Furthermore, enzymatic and nonenzymatic antioxidant activities of Trichoderma inoculated in metal-treated plants were improved. For instance, strain TF-13 increased proline (37%), lipid peroxidation (56%), catalase (35%), peroxidase (42%), superoxide dismutase (27%), and glutathione reductase (39%) activities in 100 μg Pb kg-1 soil-treated plants. The uptake of Pb and Cd in root/shoot tissues was decreased by 34/39 and 47/38% in fungal-inoculated and 25 μg kg-1 soil-treated plants. Thus, this study demonstrates that stabilizing metal mobility in the rhizosphere through Trichoderma inoculation significantly reduced the detrimental effects of Cd and Pb toxicity in V. radiata and also enhanced development under HM stress conditions.

Potato (Solanum tuberosum L.) cultivars physiological, biochemical performance and yield parameters response to acid mine water irrigation and soil physiochemical properties

This paper aimed to analyse the potato cultivar’s response to physiological, biochemical performance, yield parameters and soil physiochemical properties when subjected to quicklime (un)treated acid mine drainage (AMD) irrigation. A randomized design experiment was conducted with five water treatment levels: TW1; TW2; TW3; TW4 to TW5 replicated four times. The results showed that the quicklime treatment increased the pH of the AMD water, reduced the concentration of EC, NO3−, SO42− and ameliorated heavy metals. However, unsafe levels of heavy metals above the maximum permissible (WHO/FAO) levels were found in Pb, Mg and Mo for water (TW4 and TW5), while As, Cd and Cr for soils (ST4 and ST5) respectively. For potato tubers (TT4 and TT5) concentrations of As, Cd, Cr, and Pb were above the maximum levels. Stomatal conductance, chlorophyll content and yield parameters responded positively by increasing significantly on TW4 and TW5 treatments, but negatively (reduced) towards TW2 and TW3 treatments. A higher bioaccumulation factor was obtained for Zn ˃ Cu ˃ Mg ˃ Pb ˃ Mn, which was an indication of the contamination status of soil, with Zn being more concentrated than other metals. The findings indicate that quicklime-treated AMD is usable for potato irrigation with regular monitoring of heavy metal levels and strict observation of water reuse protocols. The use of this large source of ameliorated (AMD) water will go a long way in improving food security in South Africa and/or in countries where agriculture production is around mining areas.

Alevli Atomik Absorpsiyon Spektroskopisi ile Manyetik Katı Faz Ekstraksiyonu Kullanılarak Cd(II) ve Pb(II) İyonlarının Tayini ve Türlendirilmesi

In this study, Pb(II) and Cd(II) ions were determined by Fe3O4@G2/Npht magnetic dendrimers using the solid-phase extraction (SPE) method by flame atomic absorption spectrophotometer (FAAS). The morphological and chemical properties of magnetic dendrimers were investigated using Fourier Transform Infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) techniques. The magnetic characteristics of the ferromagnetic features of the magnetic nanocomposites were validated by vibrating sample magnetometry (VSM). The heavy metal ion recovery was assessed via flame atomic adsorption spectroscopy (FAAS). To ascertain the ideal adsorption system conditions, the effects of various parameters, including pH, adsorbent dose, adsorbent time, eluent type and amount, etc., were examined. Optimum conditions for heavy metal recovery using Fe3O4@G2/Npht magnetic dendrimer were determined as pH 6.5, 1M HNO3 and 100 mg for Pb(II) and pH 7.5, 1 M HNO3 and 100 mg for Cd(II). The novel material of Fe3O4@G2/Npht magnetic dendrimer for separation and pre-concentration of Pb(II) and Cd(II) was used to natural water.

Preliminary investigation of the use of Silybum marianum (L.) Gaertn. as a Cd accumulator in contaminated Mediterranean soils: the relationships among cadmium (Cd) soil fractions and plant Cd content

The plant Silybum marianum (L.) Gaertn. has been used in a preliminary study to investigate its phytoremediation potential in moderately and heavily Cd-polluted Greek soils. For this purpose, a pot experiment was carried out using four soil treatments, two from agricultural and two from urban areas, contaminated with 3 and 30 mg of Cd per kg of soil. The modified Bureau of Community Reference (BCR) fractionation method was used to determine Cd levels in the soil fractions. The water-soluble, available-DTPA extractable, total and pseudo-total concentrations of Cd were also evaluated and attempts to find relationships between Cd soil fractions and Cd levels in the parts of the cultivated plants were made. Significant correlations among Cd soil fractions, Cd plant parts, and soil physicochemical parameters were obtained and discussed. High Cd translocation and accumulation rates were observed mainly in the root and the lower part of the stems, while in flowers and seeds no Cd was detected, leading to the conclusion that the high-value product contained in the seeds maintains its quality and is free of contaminants. The results are satisfactory indicating Silybum marianum (L.) Gaertn. as a promising plant for remediation practices in Cd-contaminated Mediterranean soils, promoting the principles of circular economy.

Ecotoxicological and Potential Health Risk Assess-ment in Dimna Canal, Interlinking Lentic and Lo-tic Ecosystem in Jamshedpur, India

Abstract: Heavy and Trace Elements (HTEs) pollution is a serious menace to the ecosystem. These elements are ubiquitous that can bioaccumulate and biomagnify in the food chain. This study aimed to assess the HTE pollution on different trophic level of an aquatic food chain of Dimna canal interlinking a lentic (Dimna Lake) and a lotic (Subarnarekha River) ecosystem. In this study, water, sediments, and biotic samples of molluscs (Limnaea stagnalis) and fish (Channa punctatus) were collected and analysed in an ICP-MS for six HTEs (Cu, Pb, Zn, As, CD and Cr). Then, the health risk to human through the consumption of L. stagnalis and C. Punctatus was calculated using the Target Hazard Quotient (THQ) and Hazard Index (HI). It is observed that the average level of Pb (12.96 µg/L) and Cd (3.83µg/L) in water is higher than the limit prescribed by WHO, 2004. In sediment, the average level of Zn (118.14 µg/g) and Cd (0.43 µg/g) is higher than the average shale value of the earth's crust. The higher value of Pb, Cd and Zn in the canal ecosystem may be due to the discharge of chemical, primer etc. from industries as well bricks industry. In mollusc (L. stagnalis), the average levels of HTEs are the highest in comparison to limits prescribed by FAO (1983) and account for 82.74 µg of Cu per g, 20.09 µg of Pb per g, 530.49 µg of Zn per g, and 0.86 µg of Cd per g. In edible fish (C.punctatus) parts, level of As (2.41 µg/g) and Cd (0.66 µg/g) are higher than the FAO limits. Mollusc, being the primary consumer of the aquatic food chain, accumulates more HTE than that of fish; hence mollusc can be used as a potential bioindicator. THQ values of metals due to consumption of mollusc and fish show that As contributes almost 50 % in HI. Also, among the population of two age groups (adult and children); children are found more susceptible to HTE exposure. Hence, regular monitoring and assessment are required for aquatic ecosystems for the safeguard of human health.

Investigating the growth characteristics, oxidative stress, and metal absorption of chickpea (Cicer arietinum L.) under cadmium stress and in silico features of HMAs proteins

Heavy metal contamination can have a strong effect on the morphological and physiological characteristics of plants. In the present study, Cicer arietinum L. (chickpea) was exposed to different concentrations of cadmium (control, 2, 4, 8 μg Cd g-1 perlite) and the effect on plant growth and antioxidant enzymes were evaluated. The observed morphological changes in chickpea plant included stunted growth, reduced root system development and plant color change. A significant increase in enzyme activity of peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase was observed at 4 μg Cd g-1 perlite, with a subsequent decrease when concentration was increased to 8 μg Cd g-1 perlite in the leaves of the plants. The highest cadmium levels were determined at a concentration of 8 μg Cd g-1 perlite. With the addition of 2 μg Cd g-1 perlite, manganese uptake in the aboveground part of the plant increased significantly, but then decrease at higher cadmium concentrations. In addition, zinc and copper levels decrease in the presence of cadmium. These results indicate that chickpea has a relatively high adsorption capacity for cadmium in aboveground tissues and special precautions should be taken when growing chickpea. In silico analysis led to the identification of 13 heavy metal ATPases (HMAs) in chickpea. These proteins contain 130 to 1032 amino acids with 3 to 18 exons. They are involved in the transfer of cadmium and zinc and help in heavy metal detoxification of plants. Bioinformatics studies have been conducted to better understand the mechanism by which the plant is able to combat heavy metal stress.

Dietary intake of metals, metalloids, and persistent organic pollutants in Spanish pregnant women. ECLIPSES study

ObjectiveThis study aimed to describe dietary intake and important dietary sources to pollutants as well as to identify maternal socio-economic and lifestyle factors associated with high intake during pregnancy in women residing in a Mediterranean city with heavy industrial activity. MethodsDietary intake during pregnancy of As, InAs, Cd, MeHg, Pb, PCDD/Fs, DL-PCBs, and NDL-PCBs in 701 pregnant women participating in the longitudinal ECLIPSES study was calculated based on a 45-item food-frequency questionnaire and a database of pollutants in food of the Catalan Food Safety Agency. Details on socio-economic, lifestyle, and anthropometric variables were also collected. ResultsThe mean dietary intake of pollutants per day and the food group that contributed the most (%) was: 286.51 μg of As (71.27% from white fish), 4.14 μg of InAs (70.16% from cereals-tubers), 6.27 μg of Cd (47.51% from seafood), 5.00 μg of MeHg (52.88% from blue fish), 3.32 μg of Pb (30.15% from cereals-tubers), 9.93 pg of PCDD/Fs (from many food categories), 18.39 pg of DL-PCBs (59.74% from blue fish) and 181.00 ng of NDL-PCBs (44.58% from blue fish). Adjusted multivariate analysis revealed that older age was associated with high As intake, higher educational level was related to low InAs, Cd, and DL-PCBs intake, and alcohol use and smoking were linked with high Pb intake. ConclusionThe dietary intake of pollutants including As and DL-PCBs among pregnant women exceeds or almost reaches the EFSA safety threshold. These findings support the urgent need for local governments to pay special attention to this situation and develop specific prevention strategies for this vulnerable group.

The effects of winter cold acclimation on acute and chronic cadmium bioaccumulation and toxicity in the banded killifish (Fundulus diaphanus)

Temperate freshwater fishes can experience large seasonal temperature fluctuations that could affect their exposure and sensitivity to trace metals. Yet, temperature effects are overlooked in ecotoxicology studies, especially for cold temperatures typical of the winter. In the present study, the effects of long-term cold acclimation on Cd bioaccumulation and toxicity were investigated in a freshwater fish, the banded killifish (Fundulus diaphanus). Killifish were acclimated to 14 °C or gradually cooled (2 °C/week) to 4 °C and cold acclimated for 6 weeks. Then, both acclimation groups were exposed to environmentally realistic waterborne Cd concentrations (0, 0.5 or 5 µg Cd L−1) for a further 28 d at their respective acclimation temperatures. Tissue metal bioaccumulation, fish survival, condition, and markers of oxidative and ionoregulation stress, were measured after 0, 2, 5 and 28 days of Cd exposure. Cadmium tissue accumulation increased over the exposure duration and was typically lower in cold-acclimated fish. In agreement with this lower bioaccumulation, fewer Cd toxic effects were observed in cold-acclimated fish. There was little evidence of a difference in intrinsic Cd sensitivity between 4 °C- and 14 °C-acclimated fish, as Cd toxicity appeared to closely follow Cd bioaccumulation. Our study suggests that current environmental water quality guidelines would be protective in the winter for the abundant and ecologically-important banded killifish.

Effects of resource availability on the growth, Cd accumulation, and photosynthetic efficiency of three hyperaccumulator plant species

Plants that hyperaccumulate heavy metals such as cadmium (Cd) are important agents of phytoremediation. Availability of resources such as light, nutrients, and water can affect heavy metal accumulation by plants, but the responses of hyperaccumulators to different levels of resource availability remain little studied. To test such responses, three Cd hyperaccumulators, Solanum nigrum, Bidens pilosa, and Taraxacum mongolicum, were grown in Cd-contaminated soil; subjected to three levels of light, nutrient, or water availability; and measured for growth, Cd accumulation, and photosynthetic efficiency. All three species accumulated more total biomass and grew taller if given high than low water or light (each P < 0.001). Species accumulated four to eight times more Cd (190−309 versus 24−68 μg Cd g−1 mass) under high than low light. High water availability increased Cd accumulation by 89% in B. pilosa but decreased it by 31% and 40% in S. nigrum and B. pilosa, respectively. Effects of nutrients on both growth and accumulation varied between species; Cd accumulation by S. nigrum and T. mongolicum was respectively 14% and 54% lower at high than low nutrients, while it was 130% higher in B. pilosa. Light but not water or nutrient availability affected effective and maximum quantum yields and electron transport rate. Findings from this study suggest that low levels of light may constrain phytoremediation of Cd in soil and that testing species of Cd hyperaccumulators individually for responses to levels of water and nutrients will inform selection of species for phytoremediation.

Variation in essential mineral element and toxic trace element concentrations in the seeds of Sri Lankan rice varieties as affected by milling and soil fertility

Concentration of mineral elements in rice seeds may vary depending on the soil fertility status and seed polishing (milling). In order to test this, 54 rice varieties were grown in the fields used to cultivate rice either with or without applying fertilizers for over 40 years. Part of the seeds collected from those varieties was polished before using for element analyses using ICP-MS while the rest considered as unpolished seeds. When comparing unpolished rice seeds produced at fertilized and unfertilized sites, the concentrations of Mg, Ca, K, Mn, Co, Cu, As and Cd were decreased, and the concentrations of Na, Al, Fe, Zn, and Mo were unchanged from fertilized to unfertilized sites. When comparing unpolished and polished rice seeds produced at fertilized and unfertilized sites, seed Mg, K, Mn, Fe, Co and Zn concentrations were higher in unpolished seeds than those in polished seeds, and the concentrations of Na, Al, Mo, Cd, As and Pb were similar between polished and unpolished seeds. Estimated values revealed that rice contributed 4–15% of the daily requirement of Fe, Cu, Zn, and 50–60% Mo irrespective of the soil fertility and polishing. Seed concentrations of As, Pb and Cd were lower than the maximum allowable levels. However, rice consumption contributed to the daily intake of 4–8 µg as, 2–6.5 µg Cd, and 19–25 µg Pb. Improving soil fertility is required to enrich rice seeds with most of the micronutrients and the milling should be done with much care to minimize nutrient loss in human diet.

Phase partitioning of mercury, arsenic, selenium, and cadmium in Chlamydomonas reinhardtii and Arthrospira maxima microcosms

As the global human population increases, demand for protein will surpass our current production ability without an increase in land use or intensification. Microalgae cultivation offers a high yield of protein, and utilization of wastewater from municipal or agricultural sources in place of freshwater for microalgae aquaculture may increase the sustainability of this practice. However, wastewater from municipal and agricultural sources may contain contaminants, such as mercury (Hg), cadmium (Cd), selenium (Se), and arsenic (As). Association of these elements with algal biomass may present an exposure risk to product consumers, while volatilization may present an exposure hazard to industry workers. Thus, the partitioning of these elements should be evaluated before wastewater can be confidently used in an aquaculture setting. This study explored the potential for exposure associated with Arthrospira maxima and Chlamydomonas reinhardtii aquaculture in medium contaminated with 0.33 μg Hg L−1, 60 μg As L−1, 554 μg Se L−1, and 30 μg Cd L−1. Gaseous effluent from microalgae aquaculture was analyzed for Hg, As, Se, and Cd to quantify volatilization. A mass balance approach was used to describe the partitioning of elements between the biomass, medium, and gas phases at the end of exponential growth. Contaminants were recovered predominantly in medium and biomass, regardless of microalgae strain. In the case of Hg, 48 ± 2% was associated with A. maxima biomass and 55 ± 8% with C. reinhardtii when Hg was present as the only contaminant, but this increased to 85 ± 11% in C. reinhardtii biomass when As, Se, and Cd were also present. A small and highly variable abiotic volatilization of Hg was observed in the gas phase of both A. maxima and C. reinhardtii cultures. Evidence presented herein suggests that utilizing wastewater containing Hg, Cd, Se, and As for microalgae cultivation may present health hazards to consumers.

Metal-tolerant and siderophore producing Pseudomonas fluorescence and Trichoderma spp. improved the growth, biochemical features and yield attributes of chickpea by lowering Cd uptake

Industrialization and human urbanization have led to an increase in heavy metal (HM) pollution which often cause negative/toxic effect on agricultural crops. The soil-HMs cannot be degraded biologically however, microbe-mediated detoxification of toxic HMs into lesser toxic forms are reported. Considering the potentiality of HMs-tolerant soil microbes in metal detoxification, Pseudomonas fluorescence PGPR-7 and Trichoderma sp. T-4 were recovered from HM-affected areas. Under both normal and cadmium stress, the ability of both microorganisms to produce different plant hormones and biologically active enzymes was examined. Strains PGPR-7 and T-4 tolerated cadmium (Cd) an up-to 1800 and 2000 µg mL−1, respectively, and produced various plant growth regulating substances (IAA, siderophore, ACC deaminase ammonia and HCN) in Cd-stressed condition. The growth promoting and metal detoxifying ability of both strains were evaluated (either singly/combined) by applying them in chickpea (Cicer arietinum L.) plants endogenously contaminated with different Cd levels (0–400 µg kg−1 soils). The higher Cd concentration (400 µg kg−1 soils) negatively influenced the plant parameters which, however, improved following single/combined inoculation of P. fluorescence PGPR-7 and Trichoderma sp. T-4. Both microbial strains increased the growth of Cd-treated chickpeas however, their combined inoculation (PGPR-7 + T-4) caused the most positive effect. For instance, 25 µg Cd Kg−1 + PGPR-7 + T4 treatment caused maximum increase in germination percentage (10%), root dry biomass (71.4%) and vigour index (33%), chl-a (38%), chl-b (41%) and carotenoid content (52%). Furthermore, combined inoculation of P. fluorescence PGPR-7 and Trichoderma sp. T-4 maximally decreased the proline, MDA content, POD and CAT activities by 50%, 43% and 62%, respectively following their application in 25 µg Cd kg−1 soils-treated chickpea. Additionally, microbial strains lowered the plant uptake of Cd. For example, Cd-uptake in root tissues was decreased by 42 and 34% when 25 µg Cd Kg−1- treated chickpea plants were inoculated with P. fluorescence PGPR-7, Trichoderma sp. T-4 and co-inoculation (PGPR-7 + T4) of both strains, respectively. Therefore, from the current observation, it is suggested that dual inoculation of metal tolerant P. fluorescence and Trichoderma sp. may potentially be used in detoxification and reclamation of metal-contaminated soils.

Metabolic and Oxidative Changes in the Fern Adiantum raddianum upon Foliar Application of Metals

Cadmium (Cd) or nickel (Ni) were applied as a foliar spray (1 µM solution over one month) to mimic air pollution and to monitor metabolic responses and oxidative stress in the pteridophyte species. Exogenous metals did not affect the metal content of the soil and had relatively little effect on the essential elements in leaves or rhizomes. The amounts of Cd and Ni were similar in treated leaves (7.2 µg Cd or 5.3 µg Ni/g DW in mature leaves compared with 0.4 µg Cd or 1.2 µg Ni/g DW in the respective control leaves), but Ni was more abundant in rhizomes (56.6 µg Ni or 3.4 µg Cd/g DW), resulting in a higher Cd translocation and bioaccumulation factor. The theoretical calculation revealed that ca. 4% of Cd and 5.5% of Ni from the applied solution per plant/pot was absorbed. Excess Cd induced stronger ROS production followed by changes in SOD and CAT activities, whereas nitric oxide (NO) stimulation was less intense, as detected by confocal microscopy. The hadrocentric vascular bundles in the petioles also showed higher ROS and NO signals under metal excess. This may be a sign of increased ROS formation, and high correlations were observed. Proteins and amino acids were stimulated by Cd or Ni application in individual organs, whereas phenols and flavonols were almost unaffected. The data suggest that even low levels of exogenous metals induce an oxidative imbalance, although no visible damage is observed, and that the responses of ferns to metals are similar to those of seed plants or algae.

The Content of Cd and Pb in Herbs and Single-Component Spices Used in Polish Cuisine

Spices and herbs play an important role in the human diet, mostly due to the presence of essential oils and high antioxidant activity. Therefore, the toxicity of metals raises concerns about the safety of consumption of spices and herbs. This paper examines the content of Cd and Pb in fresh and dried herbs and single-component spices that are the most popular in Polish cuisine: 100 samples of nine kinds of dried herbs, 184 samples of 15 kinds of fresh herbs and 148 samples of 14 kinds of loose single-component spices. The level of Cd and Pb was determined using the GF AAS method. The safety of herbs and spices for consumption was estimated based on the percentage intake of Cd and Pb compared with the tolerable intake (% TWI, % BMDL), chronic daily intake (CDI), target hazard quotient (THQ), hazard index (HI) and comparisons of the results of chemical analyses with the maximum admissible levels of Cd and Pb in Poland and in the European Union. Calculated per fresh weight of the product, dried herbs on average contained 0.134 ± 0.168 mg of Cd and 0.548 ± 0.161 mg of Pb per kg−1, fresh herbs on average contained 0.004 ± 0.007 mg of Cd and 0.039 ± 0.033 mg of Pb per kg−1, and the mean content of Cd in spices was 0.017 ± 0.019 mg per kg−1 and 0.064 ± 0.050 mg of Pb. The % TWI, % BMDL, CDI, THQ and HI (Cd + Pb) for all the analysed products were lower than 1. The results do not imply a risk due to the supply of Cd and Pb with the diet to the human body, primarily due to the small intake of these products. However, it should be highlighted that the content of Cd in dried coriander and estragon and that of Pb in watercress, jiaogulan, celery, basil and dill exceeded the acceptable limit. Thus, their consumption for people from particularly sensitive groups such as babies, pregnant and breastfeeding women and people should be carefully limited.

Polymetallic (zinc and cadmium) hyperaccumulation in the Australian legume Crotalaria novae-hollandiae compared to Crotalaria cunninghamii

PurposeHyperaccumulators are plants with the ability to tolerate and accumulate high concentrations of potentially phytotoxic metals. The Australian legume Crotalaria novae-hollandiae accumulates remarkably high concentrations of zinc (Zn), cadmium (Cd) and copper (Cu) in its shoots when growing on metalliferous (Zn-Cd ‘calamine’) soils. This study aimed to investigate zinc-cadmium tolerance in C. novae-hollandiae and to compare it with the closely related, but non-metalliferous, C. cunninghamii.MethodsCrotalaria cunninghamii and C. novae-hollandiae were exposed to Zn (3–1000 μM) and Cd (0–60 μM) treatments in hydroponics culture. At the end of the experiment, harvested plants were segmented into roots, old and young stems, old and young leaves for elemental analysis with Inductively coupled plasma atomic emission spectroscopy (ICP-AES). Laboratory-based micro-X-ray fluorescence (μXRF) analysis was used to elucidate elemental distribution in a shoot and in leaflets.ResultsCrotalaria cunninghamii accumulated up to 1210 μg Zn g−1 and 47.6 μg Cd g−1 in its leaves, with a 75% reduction in biomass in the Zn treatment. Crotalaria novae-hollandiae accumulated up to 16,600 μg Zn g−1 and 1250 μg Cd g−1, with a 70% increase in biomass when exposed to Zn. The species both exhibited chlorosis and stunted growth in the Cd treatments, while only C. cunninghamii exhibited toxicity symptoms in Zn treatment.ConclusionsCrotalaria novae-hollandiae has limited tolerance for Cd and based on the accumulation and distribution of foliar Zn and Cd it is suspected that C. novae-hollandiae has different uptake and tolerance mechanisms when compared to other widely studied Zn-Cd hyperaccumulators (such as Noccaea caerulescens and Arabidopsis halleri).

Transcriptome analysis reveals decreased accumulation and toxicity of Cd in upland rice inoculated with arbuscular mycorrhizal fungi

There have been a few reports on the impacts of arbuscular mycorrhizal fungi (AMF) on the expression of genes associated with the uptake, transport and detoxification of Cd in upland rice, but there is no study on the impacts of AMF on the transcriptome of upland rice grown in Cd-contaminated soil. In the present work, a pot experiment was conducted to study the influences of the AMF-Glomus versiforme (Gv) on the Cd accumulation, photosynthesis, antioxidant enzymes and transcriptome in upland rice grown in soils supplemented with 10 μg Cd g−1 soil. Gv symbiosis evidently promoted the plant growth, P acquisition and photosynthetic characteristics in upland rice. In addition, 229 differentially expressed genes (DEGs) were identified in upland rice root inoculated with Gv, of which 149 DEGs were upregulated and 80 DEGs were downregulated. More importantly, one Cd transporter gene Nramp5 was significantly downregulated, thus reducing Cd absorption, transfer and accumulation in mycorrhizal upland rice. Moreover, four genes in the Gene Ontology (GO) term of cysteine biosynthesis and two metallothionein genes were upregulated, which could have decreased Cd phytotoxicity in upland rice inoculated with Gv. Meanwhile, one peroxidase gene, two genes in the GO term of peroxisome and one gene in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of carotenoid biosynthesis were significantly upregulated, and enhanced the activities of catalase (CAT) and peroxidase (POD) in Gv-inoculated upland rice. Our results of transcriptome analysis initially elucidated the molecular mechanism by which AMF decreased the accumulation and toxicity of Cd in upland rice.