High Concentrations Of Cd Research Articles

Genetic response analysis of Beauveria bassiana Z1 under high concentration Cd(II) stress

Cadmium (Cd(II)) has carcinogenic and teratogenic toxicity, which can be accumulated in the human body through the food chain, endangering human health and life. In this study, a highly Cd(II)-tolerant fungus named Beauveria bassiana Z1 was studied, and its Cd(Ⅱ) removal efficiency was 71.2% when the Cd(II) concentration was 10 mM. Through bioanalysis and experimental verification of the transcriptome data, it was found that cadmium entered the cells through calcium ion channels, and then complexed with intracellular glutathione (GSH) and stored in vacuoles or excluded extracellular by ABC transporters. Cytochrome P450 was significantly upregulated in many pathways and actively participated in detoxification related reactions. The addition of cytochrome inhibitor taxifolin reduced the removal efficiency of Cd(II) by 45%. In the analysis, it demonstrated that ACOX1 gene and OPR gene of jasmonic acid (JA) synthesis pathway were significantly up-regulated, and were correlated with bZIP family transcription factors cpc-1_0 and pa p1_0. The results showed that exogenous JA could improve the removal efficiency of Cd(II) by strain Z1.

Whole blood cadmium levels and depressive symptoms in Chinese young adults: A prospective cohort study combing metabolomics

ObjectivesTo investigate the association between Cd exposure and depressive symptoms in Chinese young adults. And to investigate the potential metabolic changes associated with high blood Cd concentrations. MethodsWe conducted a cohort study in 2019 and 2021. Blood Cd and depressive symptoms were collected during baseline and follow-up. The nine-item Patient Health Questionnaire (PHQ-9) scores were used to assess depressive symptoms. We used the generalized linear mixed model to estimate the association between blood Cd levels and depressive symptoms. A metabolomic and lipidomic analysis based on liquid chromatography-mass spectrometry was conducted on a total of 679 blood samples. The metabolomic data were analyzed using variance analysis and linear mixed effects models. ResultsBlood Cd concentrations were significantly associated with increased severity of depression symptoms [odds ratio (OR) 2.07, 95% confidence interval (CI) 1.04–4.11]. Metabolomics analysis found 93 metabolites with significant statistical differences between the lowest blood Cd level group and the highest Cd level group. Among the 93 differential metabolites, 17 were enriched in 7 differential metabolic pathways. ConclusionsBlood Cd was associated with increased severity of depression symptoms in Chinese young adults. Cd exposure may affect depressive symptoms by inducing oxidative stress, inflammation, and disrupting amino acid metabolism.

Variability in cadmium stress tolerance among four maize genotypes: Impacts on plant physiology, root morphology, and chloroplast microstructure

Cadmium (Cd) is detrimental to both plants and humans. Maize (Zea mays L.) genotypes exhibit variations in Cd accumulations. This study examined variations in Cd accumulation and tolerance among four maize genotypes with contrasting root morphology. The four maize genotypes were cultivated in a semi-hydroponic system with three Cd concentrations (0, 10, 20 μmol L−1). The effects of Cd on plant growth and physiology were assessed 39 days after transplanting. Results showed that root characteristics were positively correlated with root Cd accumulation and the bioconcentration factor under Cd20 treatment. Genotypes Shengrui999 and Zhengdan958 exhibited higher total Cd content than Xundan29 and Zhongke11 under Cd20 conditions. Cd toxicity led to membrane degradation of chloroplast mesophyll cells, loosening and swelling of grana lamella, and reduced starch reserves. The greater tolerance of Shengrui999 and Zhengdan958 was contributed to factors such as root biomass, shallower root depth, higher Cd content, accumulation of osmolyte such as soluble protein, antioxidant activities such as catalase (CAT), and the presence of phytohormone gibberellic acid. The study establishes a link between root morphology, Cd accumulation, and tolerance in maize plants, as demonstrated by the higher Cd accumulation and shallower root system in Cd-tolerant genotypes. This research provides a foundation for breeding maize cultivars better suited for adaptation to moderate Cd-contaminated environments.

The damage caused by Cd toxicity to photosynthesis, cellular ultrastructure, antioxidant metabolism, and gene expression in young cacao plants are mitigated by high Mn doses in soil.

Manganese (Mn) is one of the essential mineral micronutrients most demanded by cacao. Cadmium (Cd) is highly toxic to plants and other living beings. There are indications that Mn can interact with Cd and mitigate its toxicity. The objective of this study was to evaluate the action of Mn on the toxic effect of Cd in young plants of the CCN 51 cacao genotype, subjected to different doses of Mn, Cd, and Mn+Cd in soil, through physiological, biochemical, molecular, and micromorphological and ultrastructural changes. High soil Mn doses favored the maintenance and performance of adequate photosynthetic processes in cacao. However, high doses of Cd and Mn+Cd in soil promoted damage to photosynthesis, alterations in oxidative metabolism, and the uptake, transport, and accumulation of Cd in roots and leaves. In addition, high Cd concentrations in roots and leaf tissues caused irreversible damage to the cell ultrastructure, compromising cell function and leading to programmed cell death. However, there was a mitigation of Cd toxicity when cacao was grown in soils with low Cd doses and in the presence of Mn. Thus, damage to the root and leaf tissues of cacao caused by Cd uptake from contaminated soils can be attenuated or mitigated by the presence of high Mn doses in soil.

Assessing stress responses in potherb mustard (Brassica juncea var. multiceps) exposed to a synergy of microplastics and cadmium: Insights from physiology, oxidative damage, and metabolomics

Both microplastics (MPs) and cadmium (Cd) are common contaminants in farmland systems, is crucial for assessing their risks for human health and environment, and little research has focused on stress responses mechanisms of crops exposed to the combined pollution. The present study investigated the impact of polyethylene (PE) and polypropylene (PP) microplastics (MPs), in combination with Cd, on the physiological and metabolomic changes as well as rhizosphere soil of potherb mustard. Elevated levels of PEMPs and PPMPs were found to impede nutrient uptake in plants while promoting premature flowering, and the concomitant effect is lower crop yields. The substantial improvement in Cd bioavailability facilitated by MPs in rhizosphere soil, especially in high concentrations of MPs, then elevated bioavailability of Cd contributed to promoted Cd accumulation in plants, with distinct effects depending on the type and concentration of MPs. The presence of MPs Combined exposure to high concentrations of MPs and Cd resulted in alterations in plant physiology and metabolomics, including decreased biomass and photosynthetic parameters, elevated levels of reactive oxygen species primarily H2O2, increased antioxidant enzyme activities, and modifications in metabolite profiles. Overall, our study assessed the potential impact on food security (the availability of cadmium to plant) and crops stress responses regarding the contamination of MPs and Cd, providing new insights for future risk assessment in agriculture.

Heavy metals in wetlands of southwestern India: from sediments through invertebrates to migratory shorebirds

Heavy metal pollution in Indian wetlands is rising due to industrial, agricultural and urban development activities. Shorebirds occupy upper trophic levels and are therefore especially vulnerable to heavy metal pollution. We evaluated the concentration of heavy metals (zinc, copper, cobalt, chromium, lead and cadmium) in 22 common species of migrant shorebirds (220 shorebird dropping samples) with diverse foraging behaviors, in their different prey (55 prey samples) and in the sediments (90 sediment samples) in different habitat types (mudflats, mangroves and sand beaches) between 2019 and 2021. Further, we analyzed a total of 10 biofilm samples from mudflats and mangroves. We detected relatively low concentrations of heavy metals in the sediments (Zn concentration range: 9.11–40.91 mg/kg; Cu: 5.74–21.38 mg/kg; Co: 2.00–4.04 mg/kg; Cr: 4.05–41.03 mg/kg; Pb: 1.02–7.19 mg/kg; Cd: 0.56–4.35 mg/kg). However, we measured relatively high concentrations of heavy metals in invertebrate prey species (Zn concentration range: 84.72–224.74 mg/kg; Cu: 26.63–170.36 mg/kg; Co: 13.98–14.42 mg/kg; Cr: 14.78–98.16 mg/kg; Pb: 18.95–157.29 mg/kg; Cd: 9.33–60.56 mg/kg). In addition, we found high concentrations of heavy metals in shorebird droppings (Zn concentration range: 41.33–58.8 mg/kg; Cu: 31.42–52.11 mg/kg; Co: 36.34–55.68 mg/kg; Cr: 52.3–68.21 mg/kg; Pb: 25.94–43.13 mg/kg; Cd: 5.53–16.4 mg/kg). It is evident that concentration of heavy metals increased successively moving from sediment to prey to shorebird species, likely through trophic transfer. The biofilm samples contained very high concentrations of Cr, Pb and Cd (22.64, 28.09 and 18.46 mg/kg respectively) which could be harmful to biofilm grazing shorebirds. Since bioaccumulation of heavy metals entail risks in living species, we suggest that increasing concentrations may detrimentally affect physiological processes in invertebrates and shorebirds. There is an urgent need to identify the sources of pollution and to reduce the discharge of heavy metals and other pollutants into coastal and inland wetlands.

Heavy Metals Can Affect Plant Morphology and Limit Plant Growth and Photosynthesis Processes

Soil heavy metal pollution caused by human activities has become one of the most critical environmental issues with a global concern. Phytoremediation is widely used due to its low cost and environmental friendliness. However, the impact of heavy metals on plant growth remains unclear. This study investigated the effects on the growth and photosynthetic activity of Picris divaricata Vant. under different cadmium concentrations using a hydroponics cultivation system. The results showed that the growth and photosynthetic processes of P. divaricata exhibited a phenomenon of promotion in low Cd concentrations and inhibition in high Cd concentrations. Under a low to medium Cd concentration (≤25 μM), there was no Cd toxicity in terms of plant growth, but high concentrations of Cd inhibited plant growth. The Fe content of leaves gradually increased as the Cd concentration increased; it reached 201.8 mg kg−1 in 75 μM Cd. However, there was no significant difference in Mn between the 75 μM Cd treatment and the control (p > 0.05). The contents of carotenoid ranged between 3.06 and 3.26 mg/g across the different Cd treatments, showing no significant differences. The treatment with 5–75 μM Cd did not directly affect the photosynthesis of P. divaricata. Higher Cd concentrations reduced the stomatal density on the of P. divaricata leaves, resulting in stomatal and mesophyll conductance limitations, indirectly affecting P. divaricata photosynthesis. These research results provide a reference for evaluating and selecting heavy metal tolerant plants and provide environmentally friendly approaches to remediate heavy metal pollution.

Investigation of the relationship between heavy metals in the blood and depression in people with different body mass indices using the NHANES database: A cross-sectional study

BackgroundExposure to heavy metals considered a major risk factor for mental health. ObjectiveExamining how heavy metals in blood are associated with depression in individuals of various body mass indexes. MethodsA total sample of 15,560 individuals was screened, with 4355 participants finally enrolled to study. The PHQ-9 was used to assess participants' depressive symptoms. ResultsA logistic regression analysis was used to investigate the relationship between the levels of heavy metals in the blood and the depression. Serum cadmium levels were found to be associated with risk of depression, with an odds ratio of 2.247 (95 % CI: 1.584–3.244). However, no significant correlations were observed between depression and blood levels of lead, selenium, and manganese. Subgroup analysis was performed and found that higher Cd concentrations were associated with a greater risk of depression at the same BMI. With the same Cd concentration, the risk of depression was lowest when participants' BMI was ≥30 kg/m2 and increased with increasing BMI when participants' BMI was <30 kg/m2. LimitationsIt is not possible to analyze the effect of external exposure to Cd. ConclusionCd in blood may be positively correlated with depression in American adults, and the effect of this trend is different in people with different body mass indices. With the increase in BMI, the risk gradually rises. However, it is lowest among obese people.

Greenhouse investigation on the phytoremediation potential of pioneer tree Pinus halepensis Mill. in abandoned mine site

Tailings and mine dumps are often pollutant sources that pose serious environmental threats to surrounding areas. The use of pioneer vascular plants to extract or stabilize metals is considered among the more effective mine tailing reclamation techniques. The study aimed at evaluating the phytoremediation potential of Pinus halepensis in abandoned mine-tailing (SW-Sardinia, Italy). Plant ability to tolerate high Zn, Pb, and Cd concentration and their accumulation in roots and aerial parts were assessed at greenhouse conditions. Experiments were performed on 45 seedlings planted in different substrates (mine-tailings, mine-tailings compost-amended, and reference) and on 15 seedlings grown spontaneously in the contaminated mine site investigated with their own substrates. The phytostabilization potential of plant was evaluated through biological accumulation and translocation indexes together with plant survival and biometric parameters. The outcomes showed the adaptability of P. halepensis to grow and survive in contaminated substrates. Compost addition did not improve plant survival and growth, however, it enhanced total carbon and nitrogen contents of soil, restricted metal bioavailability, and accumulation in plant aerial parts. These findings highlight that P. halepensis may be considered for phytostabilization given the great potential to limit Zn, Pb, and Cd toxicity in plant tissues by applying compost amendment in metal contaminated mine sites.

Cadmium affects the growth, antioxidant capacity, chlorophyll content, and homeostasis of essential elements in soybean plants

Soybean (Glycine max L.), as an oil and protein crop, has attracted interest for its potential in the reclamation/restoration of barren and contaminated habitats due to its ability to tolerate adverse environments. To investigate the effects of the growth (biomass and plant height), chlorophyll content, antioxidative capacity (peroxidase and superoxide dismutase activities), and homeostasis of essential elements in soybean plants induced by cadmium (Cd), a pot experiment was performed. Soybean seeds were cultivated in six different levels of Cd-contaminated soil (0, 0.25, 0.50, 1.00, 2.50, 5.00, and 10.00 mg kg−1) for 27 days at 60 % humidity and 25–35 °C in a greenhouse with natural light. Soybean seedling growth was stimulated and inhibited at low (≤1.00 mg kg−1) and high (≥2.50 mg kg−1) Cd concentrations, respectively. Essential metal elements (Mg, Fe, and Zn) and chlorophyll contents of leaves were increased and decreased at low and high Cd concentrations, respectively. Exposure to high Cd concentrations interfered with the homeostasis of essential elements in soybean plants. High Cd concentrations reduced antioxidant capacity and chlorophyll content, which inhibited soybean growth. The Cd accumulation level (>100 mg kg−1) in soybean plant organs was unsafe for producing soybean products. However, soybean seedlings appear to tolerate moderate Cd contamination.

Cadmium contamination in cacao farms of Piura, North Peru: A comprehensive assessment of geogenic and anthropogenic sources and implications for future production

Cadmium (Cd) is a heavy metal that poses a threat to food safety via the ingestion of food products with Cd. The uptake of Cd by the cacao tree (Theobroma cacao) has gained attention after the European Union set limits for Cd in chocolate products, the main commodity produced from cacao beans. In this study, we analyzed levels of Cd in soils and plant tissues across five cacao farms in the Piura region of Peru to identify the origins of Cd accumulation, and the natural and human factors controlling its concentration. Our results show that Cd levels varied in the order: leaves (1.25 mg kg−1) > beans (0.78 mg kg−1) > soils at 5 cm (0.68 mg kg−1) > soils at 20 cm (0.6 mg kg−1). Our findings suggest that the higher concentration of Cd in plant tissues and surface soils can be explained by readily available Cd from fertilizers and a litter layer being absorbed, cycled, and accumulated by the plant. Moreover, even when fertilizers are within regulatory limits, their continuous application, combined with the biocycling of Cd, may lead to high Cd concentrations in beans and leaves. Conversely, farms on alluvial soils and more stable topographic positions display higher soil and plant Cd concentrations. Likewise, farms located at lower altitudes, with higher contributing areas are more likely to receive Cd transported through sediments and water in the river network. Our results also suggest that variations in the underlying geology and soil mineralogy may be a source of potentially Cd bearing sediments. Overall, this study indicates that the high levels of Cd in plants in the study area are the result of a combined mechanism involving plant bioaccumulation and high Cd in fertilizers for the most part, with a minor contribution from potential Cd bearing minerals in sediments of alluvial soils.

Endophytic Fungus Talaromyces sp. MR1 Promotes the Growth and Cadmium Uptake of Arabidopsis thaliana L. Under Cadmium Stress.

Endophytes play essential roles in plant growth under metal(loid)s stress. An endophytic fungus strain MR1 was isolated from the roots of Miscanthus floridulus collected from a lead-zinc mining area (Huayuan, China), which could produce indole-3-acetic acid and have Cadmium (Cd) tolerance. Further 18S rRNA sequencing analysis showed that it was highly similar (99.83%) to Talaromyces pinophilus. In pot experiments, we explored the effects of strain MR1 on the growth and Cd uptake of a wide-type Arabidopsis thaliana under low (LC) and high (HC) Cd concentrations. The results showed that MR1 effectively increased the dry weight of aboveground and underground tissues by 25.95-107.21% in both LC and HC groups. Due to MR1 inoculation, the Cd content in the underground tissues was significantly (p < 0.05) decreased by 39.28% under low Cd concentration, while it was significantly (p < 0.05) increased by 28.28% under high Cd concentration. Besides, MR1 inoculations significantly (p < 0.05) increased the total content of removed Cd (17.080μg) and BCF (0.064) by 129.77% and 153.95% under high Cd concentration. Therefore, we speculated that MR1 might be selected as the effective microbial agent to increase crop yield and control Cd content in the crop in light Cd-contaminated soil. Besides, MR1 could potentially enhance the phytoremediation efficiency of extremely Cd-contaminated soil.

MAGNETIC WATER EFFECTS ON GROWTH AND SOME PHYSIOLOGICAL CHARACTERISTICS OF PAULOWNIA TOMENTOSA THUNB UNDER CADMIUM STRESS CONDITIONS

Paulownia (Paulownia tomentosa) is considered as one of the world's fastest-growing species of trees and most widely used for commercial. This research was done as a factorial experiment in Koya city, Erbil, Iraq during 2021-2022 to study the effects of magnetic water (MW) at (0, 500,1000, 1500 and 2000) gauss and cadmium chloride (Cd) at (0, 3.33, 6.66 and 10 mg Kg-1soil) on some growth, physiological and biochemical properties of this plant. Results demonstrate that MW had non-significant differ regarding the survived and the velocity of cutting outgrowth compare to using tap water, whereas Cd application increased the velocity of cutting outgrowth. At least one of MW powers increased significantly each of plant leaf-area, stem diameter, shoot and root fresh weight and dry matter content, as well as all Cd concentrations increased the plants leaves number, leaf-area, stem diameter. Cd had more effects on roots than plant shoots, where it has non-significant effects on shoot high or dry matter, whereas it increased each of shoot and root fresh weight significantly compared to the control treatment. Low power MW (500 and 1000) gauss performed better than high powers (1500 and 2000) gauss in increasing the content of photosynthesis pigments. Utilizing magnetic water greatly enhanced total carotenoids and chlorophyll a, b, regardless to device power. Chlorophyll (a and b) were both significantly reduced by high Cd concentrations; however it was significantly increased at low concentrations as compared to other treatments. High power MW decreased significantly peroxidase enzyme activity and proline content whereas it decreased the percent of total carbohydrate compared to other treatments. Cd application decreased each of peroxidase enzyme activity, percent of total carbohydrate content, increased ascorbic acid and proline significantly in comparing to the control.

Cold-acclimation effect on cadmium absorption and biosynthesis of polyphenolics, and free proline and photosynthetic pigments in Spirogyra aequinoctialis

Abstract Herein, a link has been established between cold acclimation and Cd uptake in Spirogyra aequinoctialis. The water samples supplemented with cadmium (0.1, 0.5, and 1.0 mg/L) were used for plant growth at two different temperatures. Cold-acclimated plants accumulated high concentrations (0.40 ± 0.02 µg/dry biomass) of Cd as compared to non-acclimated plants (0.30 ± 0.08 µg/dry biomass). The negative effects of Cd on the biomass, carotenoids, and chlorophyll contents in non-acclimated plants were more pronounced in non-acclimated plants as compared to the cold-acclimated plants. High concentrations of free proline and total phenolics in cold-acclimated plants were observed as compared to the non-acclimated plants. About 13 different phenolic compounds were identified using high-pressure liquid chromatography. Cold acclimation as well as the presence of Cd in water highly increased the concentrations of polyphenolics, while synergistic increase was recorded with the combination of cold acclimation and Cd treatments. The highest increase in the concentration of polyphenolics was recorded for syringic acid. Significant positive correlations of total phenolics were noted with dry biomass (R 2 = 0.51) and Cd accumulation (R 2 = 0.59) in plant tissues. Free proline concentration also showed positive correlations with dry biomass, Cd accumulation, and chlorophyll contents (R 2 = 0.80).

Wastewater driven trace element transfer up the food chain in peri-urban agricultural lands of Lahore, Pakistan

In peri-urban agricultural lands of Lahore city, untreated wastewater from trans-boundary Hudiara drain is widely used for agriculture. The irrigated water may pose a hazard of trace element (TE) contamination in agricultural produce and consequently threat to human health. This study was designed to investigate the quality and transferability of TE contamination in water, soil, fodder and buffalo milk. Samples from the 4 assets and products were collected at upstream, midstream and downstream sites along Hudiara drain. Potentially toxic elements (Cd, Cu, Ni and Zn) were analyzed using standard methods. Physicochemical analysis of water, bioaccumulation factor (BAF) from soil to fodder and Pearson correlation of metal contamination in water, soil, fodder and milk were determined. TE contamination increased from upstream to downstream site. Highest Cd concentration in water, soil, fodder and milk was 0.29 mg/L (downstream), 1.10 mg/kg (midstream), 2.12 mg/kg (downstream) and 0.29 mg/L (downstream), respectively, which surpassed permissible limits for all the 4 mediums. Similar results were found with Cu, Ni and Zn which increased downstream and the concentrations higher than permissible limits in all mediums except soil. Significantly high Hazard Index (HI) values were recorded for irrigation wastewater (23.25–31.75), fodder (7.41–11.13), and milk (11.12–17.85), which were increasing down the stream of drain. All 4 metals have shown strong positive correlation among water, soil, fodder and milk, showing transferability risk up to food chain. Transfer of TE from soil to fodder was highest for Ni (BAF 8.44) and lowest for Zn (BAF 0.41) with the following ascending trend: Zn < Cd < Cu < Ni. The physicochemical parameters of drain water also did not meet the permissible limits for wastewater irrigation. Use of untreated water of Hudiara drain for agriculture in peri-urban areas of Lahore needs to be stopped until appropriate treatment and reuse.

Expression analysis of transcription factor (CBF/DREB) gene and biochemical response of Cannabis sativa to cadmium toxicity and foliar application of molybdenum

Plants respond to heavy metals stress by the activation of stress responsive genes to establish biochemical defense mechanisms against the stress. We have investigated the molecular and biochemical response of Cannabis sativa to cadmium (Cd) stress in the presence of molybdenum (Mo) foliar treatments. For this purpose, C. sativa plants were allowed to grow in pots containing Cd polluted soil, for two month duration. Aqueous solutions of ammonium molybdate pentahydrate (0.5, 1.0 and 2.0 ppm) were foliarly sprayed on the plants, at two weeks intervals. Various parameters were inter-correlated i.e., Plant biomass, Cd phyto-accumulation, transcript level/expression of CBF/DREB genes, concentrations of free proline, polyphenolics, and chlorophyll contents. Phenolic compounds were analyzed by High Performance Liquid Chromatography Diode Array Detector (HPLC-DAD) and Cd contents were analyzed by Atomic Absorption Spectrophotometer. Biomass and chlorophyll contents decreased while the concentrations of free proline and polyphenolics increased under Cd stress. Dry biomass of the all the plant parts (roots (1.87 ± 0.22 g), stem (3.28 ± 0.39 g) and leaves (3.54 ± 0.87 g) and free proline in roots (69.00 ± 8.28 µg/g) and leaves (40.56 ± 4.87 µg/g) were most significantly increased with foliar spray of 2.00 ppm Mo. Nineteen (19) different polyphenolic compounds were identified and quantified in leaves and most of them were highly increased in concentration under Cd stress. The highest concentration was noted in Caffeoyl tyramine (1111 µg/g) in plants treated with 2.00 ppm Mo. Transcript level of CBF/DREB genes in control plants were less as compared to Mo treated plants, where a high increase in transcript level of these genes were found. Expression of CBF /DREB genes showed significant positive correlations with Cd accumulation (R2= 0.751) and concentrations of free proline (R2 = 0.62) and polyphenolics (R2 = 0.65) in leaves. The results suggested that Mo increased the expression of CBF/DREB genes and subsequently the concentration of phenolic compounds and free proline to combat plant against the toxicity of high concentration of Cd on plants.

Spatial Distribution, Speciation, and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Dongjiang Lake, Hunan Province

To understand the heavy metal pollution status of Dongjiang Lake, the contents and species of heavy metals in the surface sediments were investigated during September 2021, and the heavy metal pollution level and potential ecological risk were evaluated. The results showed that Cd, Pb, As, Cu, Zn, Ni, and Cr contents were in the range of 0.40-34.1, 14.8-1688, 6.99-1155, 6.89-280, 26.2-1739, 6.29-55.4, and 23.3-44.8 mg·kg-1, respectively, with extremely uneven spatial distributions. The highest contents of Cd, Pb, As, Zn, Cu, and Ni were found in the site adjacent to Yaogangxian tungsten ore. The proportion of metal species with bioavailability was high, in which Cd in acid-soluble species was 46.7%-71.5% and Pb in reducible species was 46.8%-67.0%. The bioavailable species of Cu, Zn, Ni, and Cr were 35%-68%, 42%-72%, 26%-51%, and 6%-30%, respectively, although they primarily existed in residual species. According to the geo-accumulation index (Igeo), there was a moderate or extreme pollution status of Cd in all sites, moderate or extreme pollution status of Pb in 90% of sites, and moderate pollution status of As, Cu, and Zn in 30% of sites. The ecological risk factor (Eri) of Cd showed high potential ecological risk in all sites with significantly high potential ecological risk in 80% of sites. Moreover, As and Pb had significantly high potential ecological risk, and Cu had moderate potential ecological risk in S7, which was adjacent to Yaogangxian tungsten ore. There was a high total potential ecological risk in all sites and significantly high potential ecological risk in 50% of sites. Therefore, the surface sediments of Dongjiang Lake were under the combined pollution of Cd, Pb, As, Zn, and Cu with high bioavailability and high total potential ecological risk.

In Situ Trace Element and Sulfur Isotope Composition of Pyrite from the Beiwagou Pb-Zn Deposit, Liaodong Peninsula, Northeast China: Implications for Ore Genesis

The Beiwagou Pb-Zn deposit, located in the western part of the Liaodong Peninsula, is a carbonate-hosted stratiform deposit with a Pb + Zn reserve of 0.08 Mt @ 4.14% (Pb + Zn). The orebodies occur as conformable layers and lenses and are strictly controlled by strata (the Paleoproterozoic Gaojiayu and Dashiqiao Formations) and lithology (plagioclase amphibolite and dolomitic marble). Given that previous studies have focused only on the mineralization features and mineralogy of deposits, herein, we report in situ trace element analyses of pyrite using LA-ICP-MS, together with in situ sulfur isotopes of pyrite, to constrain the composition, substitution mechanisms, source of sulfur, and sulfate reduction pathways of pyrite in the Beiwagou deposit. Based on pyrite morphology, texture, and chemistry, four pyrite types were identified: subhedral, porous-to-massive pyrite (Py1) related to chalcopyrite; subhedral, porous crushed pyrite (Py2) associated with fine-grained sphalerite; rounded and porous pyrite (Py3) related to the Zn-rich part of the laminated ore; and anhedral, porous-to-massive pyrite (Py4) associated with pyrrhotite, arsenopyrite, sphalerite, and galena. Py1 is characterized by high As, Ag, Cd, In, Au, Cu, and Zn concentrations and low Te, Bi, and Mo concentrations, whereas Py2 has high concentrations of Co and Ni and low concentrations of other trace elements, such as Cu, Zn, Bi, and Te. Py3 is characterized by elevated As concentrations, low Co, Ni, In, W, Te, and Tl concentrations, and varying Pb concentrations, whereas Py4 has low Ag, Cd, In, Zn, Cu, and Mn concentrations and varying W, Co, Ni, Pb, Sb, and As concentrations. Significant correlations between some elements in each pyrite type suggest substitution mechanisms, such as (Zn2+ + Cu2+ + Mn2+ + Cd2+) ↔ 2Fe2+, Ag+ + (Sb)3+ ↔ 2Fe2+, and (Te+ + Ag+) + Sb3+ ↔ 2Fe2+, and the existence of a negative correlation between Co and Ni implies competition between both elements. The strongly positive δ34S values (12.11‰–23.54‰) are similar to that of seawater sulfates and likely result from thermochemical sulfate reduction (TSR). In conclusion, the Beiwagou Pb-Zn deposit is a typical SEDEX deposit and mineralization likely occurred during diagenesis.

Effects of Cadmium Toxicity on Chemical Contents and Leaf Yield of Three Sun-Cured Tobacco Varieties

ABSTRACT Tobacco plants grown in cadmium (Cd)-contaminated soils accumulate high concentration of Cd in leaves and the Cd in leaves can readily be transferred to the human body through smoking of cigarettes. This study was conducted to investigate the effects of four soil Cd concentrations (0, 5, 10, and 20 mg kg−1) on leaf Cd, zinc (Zn), and nitrogen (N) concentrations and nicotine, reducing sugar and phenolic compounds of sun-cured Canik 190/5, Xanthi 81, and Birlik 124 varieties grown in a semi-arid condition of Turkey. Increasing doses of Cd did not significantly decrease leaf yield of tobacco cultivars, while significant (p < .05) increase and decrease were recorded in leaf Cd and Zn concentrations, respectively. The highest leaf Cd concentration was accumulated in Birlik 124 (60.5 mg kg−1), and the lowest in Canik 190/5 (55.35 mg kg−1) variety. Nicotine concentration of Xanthi 81 and Birlik 124 cultivars in the highest Cd dose (Cd20) increased compared to the nicotine in control application, while nicotine concentration of Canik 190/5 cultivars decreased in Cd20 dose. The results revealed that all three tobacco varieties were able to accumulate Cd in their leaves under high soil Cd levels. The effects of Cd on N uptake and nicotine, reducing sugar and phenolic compounds were different among the tobacco varieties. The result may be associated with differences in responses of tobacco cultivars to soil Cd concentration.

Potential use of Rorippa sylvestris (L.) Besser. as a cadmium hyperaccumulator for phytoremediation

Rorippa sylvestris (L.) Besser. (yellow fieldcress) is a hyperaccumulator of cadmium (Cd) discovered recently. There are several studies in the topic of Cd tolerance capacity and detoxification mechanism of plants, but the detoxification mechanism of R. sylvestris is not clear. Root tiller seedlings of R. sylvestris were planted in the brown bottles filled with culture solution containing different levels of Cd (0, 10, 25, 50, 100, 200 μmol·L−1, respectively) for 8 days in order to make sure the physiological responses, Cd subcellular distribution and chemical forms under Cd stress. The results showed that the growth increased in lower Cd concentration and declined in higher Cd concentration. Physiological characteristics such as photosynthesis and MDA were not significantly affected compared with the control at Cd concentratetion ≤ 50 μmol·L−1. The content of soluble sugar and free proline increased with the increasing of Cd concentration for the purpose of reducing the Cd toxicity to plant. R. sylvestris had a strong capability of Cd accumulation in different Cd treatments. The concentration of Cd in plant tissues (root, stem, leaf) was in the order of root>stem>leaf. The Cd subcellular distribution in plant tissues of R. sylvestris was in the order of soluble fractions>cell wall>protoplast>mitochondria. Cd was mainly extracted by deionized water and 80% ethanol (60.91–69.76%), followed by sodium chloride (16.14–25.12%), which indicated that R. sylvestris achieved to enhance Cd tolerance capacity and detoxification mechanism through root retention and vacuolar compartmentalization.