Cd In Tissues Research Articles

Exposure of environmental trace elements in prostate cancer patients: A multiple metal analysis

Prostate cancer (PCa) is the second leading cause of cancer-related deaths among men. To elucidate the connection between trace elements (arsenic: As, cadmium: Cd, lead: Pb, chromium: Cr, and nickel: Ni) and the risk of PCa, we analyzed trace element levels in the serum, urine, and tissues of PCa patients, while also examining their smoking status. We correlated these levels with their smoking habits. Notably, levels of Cd (P ≤ 0.05) and As (P ≤ 0.01) were significantly higher in the tumor tissue than in adjacent tissues. No significant differences were observed in the levels of Pb, Cr and Ni. Additionally, urinary Cd levels in 70% and arsenic levels in 2.3% of the PCa cohort were markedly higher than the CDC-reported cutoff (Cd ≤ 0.185 μg/L & As ≤100 μg/L). None displayed elevated levels of urinary Pb, Cr, and Ni. Conversely, in serum samples, the concentration of arsenic exceeded the CDC-determined limit (As ≤1.0 μg/L) in 31.69% of PCa patients. However, only 7.04% of patients had higher serum Cd levels than the CDC standard values (Cd ≤ 0.315 μg/L), while all PCa patients exceeded the Cr CDC limit (Cr ≤ 0.16 μg/L) and the Ni CDC limit (Ni ≤ 0.2 μg/L). On the contrary, no significant differences were observed in serum Pb (Pb ≤ 35.0 μg/L). Our findings establish a positive link between Cd and arsenic tissue concentrations and the risk of PCa. Subsequent studies are essential to determine whether elevated trace element levels pose a risk for the development of prostate carcinogenesis. Interestingly, among the PCa cohort comprising smokers, notably higher Cd levels were observed only in tumor tissues (P ≤ 0.01) and urine (P ≤ 0.05) compared to other elements or in other specimens.

Salicylic Acid- and Potassium-Enhanced Resilience of Quinoa (Chenopodium quinoa Willd.) against Salinity and Cadmium Stress through Mitigating Ionic and Oxidative Stress.

Salinity and cadmium (Cd) contamination of soil are serious environmental issues threatening food security. This study investigated the role of salicylic acid (SA) and potassium (K) in enhancing the resilience of quinoa against the combined stress of salinity and Cd. Quinoa plants were grown under NaCl (0, 200 mM) and Cd (0, 100 µM) stress, with the addition of 0.1 mM SA and 10 mM K, separately or in combination. The joint stress of Cd and NaCl caused >50% decrease in plant growth, chlorophyll contents, and stomatal conductance compared to the control plants. The higher accumulation of Na and Cd reduced the uptake of K in quinoa tissues. The joint stress of salinity and Cd caused an 11-fold increase in hydrogen peroxide and 13-fold increase in thiobarbituric acid reactive substances contents, and caused a 61% decrease in membrane stability. An external supply of 0.1 mM SA and 10 mM K helped plants to better adapt to salinity and Cd stress with less of a reduction in plant biomass (shoot 19% and root 24%) and less accumulation of Na and Cd in plant tissues. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) were enhanced by 11-fold, 10-fold, 7.7-fold, and 7-fold, respectively, when SA and K were applied together to the plants subjected to the joint stress of Cd and salinity. Based on the values of the bioconcentration factor (>1), the translocation factor (<1), and the higher tolerance index, it was clear that Cd-contaminated, salty soils could be stabilized with quinoa under the combined supply of SA and K.

A comparative eco toxicological study of heavy metal concentrations in mussels collected in 2004 from the western and eastern coastal waters in the straits of Johore

The concentrations of Cu, Cd, Zn, Pb, Ni and Fe in the different soft tissues of Perna viridis from the west and east coast of The Straits of Johore (SOJ) were determined. Crystalline style (CS) recorded higher accumulation of Cu (west: 58.2 mg/kg dry weight; east: 56.0 mg/kg dry weight), Cd (west: 9.45 mg/kg dry weight; east: 3.93 mg/kg dry weight), Pb (west: 49.5 mg/kg dry weight; east: 7.07 mg/kg dry weight) and Ni (west: 40.0 mg/kg dry weight; east: 20.2 mg/kg dry weight) than those other soft tissues. Byssus meanwhile recorded high levels of Zn (west: 173 mg/kg dry weight; east: 193 mg/kg dry weight) and Fe (west: 3213 mg/kg dry weight; east: 1221 mg/kg dry weight). By comparing the accumulation of heavy metal concentrations in all the eight tissues, CS and byssus recorded the highest accumulation of heavy metals among all tissues, followed by other tissues namely foot, gill, gonad, mantel, muscle and remainder, which recorded relatively low level on heavy metal concentrations. Generally, the soft tissues recorded higher heavy metal concentrations on the east coast than on the west coast of the SOJ. This indicated a high bioavailability and contamination of the potentially toxic heavy metals on the east coast which was due to various human activities.

Exogenous chelating agents influence growth, physiological characteristics and cell ultrastructure of Robinia pseudoacacia seedlings under lead-cadmium stress.

Heavy metal pollution of soil, especially by lead (Pb) and cadmium (Cd), is a serious problem worldwide. The application of safe chelating agents, combined with the growing of tolerant trees, constitutes an approach for phytoremediation of heavy-metal-contaminated soil. This study aimed to determine whether the two safe chelators, tetrasodium glutamate diacetate (GLDA) and citric acid (CA), could improve the phytoremediation capacity of black locust (Robinia pseudoacacia L.) in a Pb-Cd-contaminated soil and to find the key factors affecting the biomass accumulation of stressed black locust. In Pb- and Cd-stressed black locust plants, medium- and high-concentration GLDA treatment inhibited the growth, chlorophyll synthesis and maximum photochemical efficiency (Fv/Fm), promoted the absorption of Pb and Cd ions and resulted in the shrinkage of chloroplasts and starch grains when compared with those in Pb- and Cd-stressed plants that were not treated with GLDA. The effects of CA on plant growth, ion absorption, chlorophyll content, chlorophyll fluorescence and organelle size were significantly weaker than those of GLDA. The effect of both agents on Cd absorption was greater than that on Pb absorption in all treatments. The levels of chlorophyll a and plant tissue Cd and rates of starch metabolism were identified as the key factors affecting plant biomass accumulation in GLDA and CA treatments. In the future, GLDA can be combined with functional bacteria and/or growth promoters to promote the growth of Pb- and Cd-stressed plants and to further improve the soil restoration efficiency following pollution by heavy metals. Application of CA combined with the growing of black locust plants has great potential for restoring the Cd-polluted soil. These findings also provide insights into the practical use of GLDA and CA in phytoremediation by R. pseudoacacia and the tolerant mechanisms of R. pseudoacacia to Pb-Cd-contaminated soil.

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.

Bioavailability and health risk assessment of Zn and Cd in edible tissues of two typical shellfish species using in vitro gastrointestinal digestion

Dynamic extraction of edible tissues of Jinjiang oyster (Crassostrea rivularis) and Flower clam (Paphia undulata) was conducted using a fully biomimetic digestion (in vitro) method. The impact of different cooking methods on the bioavailability of Zn and Cd in the edible shellfish tissues was analyzed, and the human health risk of Zn and Cd was evaluated. The results show that the gastric biomimetic extractions of Zn and Cd in unheated samples of C. rivularis and P. undulata were higher than those in the intestinal biomimetic extraction. The extraction patterns of cooked samples were consistent with those of raw samples. The bioavailability of Zn and Cd in cooked samples of C. rivularis was 94.9% and 82.5%, respectively, indicating increased Zn bioavailability but decreased Cd bioavailability compared to the raw samples. The bioavailability of Zn and Cd in cooked samples of P. undulata was 85.1% and 83.0%, respectively, both of which decreased compared to the raw samples. Consumption of C. rivularis can provide 21.0% to 34.2% of the daily required Zn intake, while consumption of P. undulata can provide 3.8% to 6.4%. The intake of Cd from both shellfish species is below the monthly tolerable intake recommended by FAO/WHO. Consuming cooked C. rivularis can increase the intake of Zn and decrease the intake of Cd.

Foliar application of chitosan-putrescine nanoparticles (CTS-Put NPs) alleviates cadmium toxicity in grapevine (Vitis vinifera L.) cv. Sultana: modulation of antioxidant and photosynthetic status

BackgroundCadmium (Cd) stress displays critical damage to the plant growth and health. Uptake and accumulation of Cd in plant tissues cause detrimental effects on crop productivity and ultimately impose threats to human beings. For this reason, a quite number of attempts have been made to buffer the adverse effects or to reduce the uptake of Cd. Of those strategies, the application of functionalized nanoparticles has lately attracted increasing attention. Former reports clearly noted that putrescine (Put) displayed promising effects on alleviating different stress conditions like Cd and similarly chitosan (CTS), as well as its nano form, demonstrated parallel properties in this regard besides acting as a carrier for many loads with different applications in the agriculture industry. Herein, we, for the first time, assayed the potential effects of nano-conjugate form of Put and CTS (CTS-Put NP) on grapevine (Vitis vinifera L.) cv. Sultana suffering from Cd stress. We hypothesized that their nano conjugate combination (CTS-Put NPs) could potentially enhance Put proficiency, above all at lower doses under stress conditions via CTS as a carrier for Put. In this regard, Put (50 mg L− 1), CTS (0.5%), Put 50 mg L− 1 + CTS 0.5%” and CTS-Put NPs (0.1 and 0.5%) were applied on grapevines under Cd-stress conditions (0 and 10 mg kg− 1). The interactive effects of CTS-Put NP were investigated through a series of physiological and biochemical assays.ResultsThe findings of present study clearly revealed that CTS-Put NPs as optimal treatments alleviated adverse effects of Cd-stress condition by enhancing chlorophyll (chl) a, b, carotenoids, Fv/Fm, Y(II), proline, total phenolic compounds, anthocyanins, antioxidant enzymatic activities and decreasing Y (NO), leaf and root Cd content, EL, MDA and H2O2.ConclusionsIn conclusion, CTS-Put NPs could be applied as a stress protection treatment on plants under diverse heavy metal toxicity conditions to promote plant health, potentially highlighting new avenues for sustainable crop production in the agricultural sector under the threat of climate change.

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.

Effect of sludge amelioration on yield, accumulation and translocation of heavy metals in soybean grown in acid and alkaline soils.

A greenhouse pot experiment was conducted with seven different levels of sludge (0, 5, 10, 20, 40, 80, 160 g kg-1) to assess the potential impact of sludge application on soybean(Glycine max (L.) Merr.) productivity, metal accumulation and translocation, and physico-chemical changes in acid and alkaline soils. The outcomes revealed that the application of sludge @ 5.0 to 160 g kg-1 resulted in a significant (p < 0.05) increase in seed and straw yield in both acid and alkaline soils compared to control. All the assessed heavy metals in soybean were within permissible ranges and did not exceed the phytotoxic limit, except for Fe, Zn, and Cu in the roots from the application of sewage sludge. The values of bioaccumulation factor (BFroot/soil) and translocation factor i.e., TFstraw/root and TFseed/straw were < 1.0 for Ni, Pb and Cr. Overall, for all the sludge application doses the soil pH was observed to increase in the acid soil and decline in alkaline soil when compared to the control. All the investigated heavy metals (Fe, Mn, Zn, Cu, Ni, Cd, Pb, and Cr) in the different plant tissues (root, straw and seed) of soybean were correlated with the soil variables. The study finds that sludge can be a potential organic fertilizer and function as an eco-friendly technique for the recycling of nutrients in the soil while keeping a check on the heavy metals' availability to plants.

ZmHMA3, a Member of the Heavy-Metal-Transporting ATPase Family, Regulates Cd and Zn Tolerance in Maize.

The pollution of heavy metals is extremely serious in China, including zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd). Heavy-metal-transporting ATPase (HMA) belongs to a subfamily of the P-ATPase family, which absorbs and transports Zn, Cu, Pb, and Cd in plants. Here, we describe a ZmHMA-encoding HMA family protein that positively regulates Cd and Zn tolerance. The real-time fluorescence quantification (RT-PCR) results revealed that ZmHMA3 had a high expression in B73, and the expression of ZmHMA3 was sensitive to Cd in yeast cells, which was related to Cd accumulation in yeast. Additionally, the Arabidopsis thaliana homologous mutants of AtHMA2 showed Cd sensitivity compared with WT. The overexpressing ZmHMA3 plants showed higher tolerance under Cd and Zn stresses than the wild type. The overexpression of ZmHMA3 led to higher Cd and Zn accumulation in tissues based on the subcellular distribution analysis. We propose that ZmHMA3 improves maize tolerance to Cd and Zn stresses by absorbing and transporting Cd and Zn ions. This study elucidates the gene function of the ZmHMA3 response to Cd and Zn stress and provides a reference for improving the characteristics of heavy metals enrichment in existing maize varieties and the plant remediation technology of heavy-metal-contaminated soil.

Current Situation and Causes Analysis of Cadmium Pollution in the Kakehashi River Basin.

Cadmium (Cd) pollution is a public environmental problem worthy of attention. Long-term exposure to Cd may have adverse effects on human health. Our previous study showed that urinary concentration of Cd (U-Cd) in the residents decreased when Cd-polluted paddy soil was removed. However, from 2008 to 2014, the concentration of U-Cd increased. At the same time, the concentration of urinary β2-microglobulin (β2-MG), which is considered to be an early sign of cadmium-induced renal dysfunction, increased continuously. To find the cause of elevated urinary cadmium (U-Cd) in residents of cadmium-contaminated areas, we measured the concentration of cadmium in the blood (B-Cd) of 29 elderly residents (15 female and 14 male) and edible rice (R-Cd), and correlations between R-Cd, B-Cd, and U-Cd were analyzed in the formerly cadmium-polluted areas (the Kakehashi River basin). In 2016, we collected blood, urine, and rice samples from each participant. The analysis showed a significant correlation between age and B-Cd, U-Cd, and β2-MG. However, there was no significant correlation between R-Cd and U-Cd, B-Cd, or β2-MG concentrations. Although we found a slightly higher level of Cd in rice and urine than reported in 2008, we cannot be sure that it indicates an increased Cd contamination in the Kakehashi River basin because larger studies are required for such a conclusion. The increased urinary Cd concentrations in this area may be because Cd in tissues and organs returns to blood and urine as participants age, which leads to an increasing trend.

Natural enrichment of Cd and Tl in the bark of trees from a rural watershed devoid of point sources of metal contamination

To help understand the bioaccumulation of Cd and Tl in beaver tissue, we examined the enrichment of these metals in vegetation available to the animals. Bark was collected from 40 species of trees and shrubs, along with a complete soil weathering profile, within a small watershed devoid of trace metal contamination. Weathering resulted in a 5x enrichment of Cd in the soils relative to the underlying sediments, and a 6x Tl depletion: while Cd was lost from calcite and accumulates in the organic matter and oxyhydroxide fractions, Tl occurred only in the residual fraction. Soil processes alone, however, cannot explain the anomalous concentrations and enrichments of Cd in willow and poplar which contain up to 8.5 mg/kg Cd. The concentrations of Cd and Tl in the dissolved fraction (<0.45 μm) of the Wye River are similar (1.2 ± 0.4 and 1.6 ± 0.1 ng/L, respectively), and are taken to estimate their bioavailability in soil solutions. Normalizing the Cd/metal ratios in bark to the corresponding ratios in water yields the Stream Enrichment Factor: this novel approach shows that all plant species are enriched in Cd relative to Ni; 33 relative to Cu, 13 relative to Zn, and 7 relative to Mn. Thus, many plants preferentially accumulate Cd, especially willow and poplar, over these essential micronutrients. Clearly, the enrichment of Cd over Tl in bark is not a reflection of differences in bioavailability, but rather on the preferential uptake of Cd by the plants. The profound natural bioaccumulation of Cd in the bark of willow and poplar, the two favourite foods of the beaver, has ramifications for the use of these aquatic mammals as biomonitors of environmental contamination, as well as for the direct and indirect consumption of bark for traditional food and medicine.

Zn, Cu, Ni, Cd, and Pb in the foot tissue of freshwater pearl mussels from Green Belt rivers of Fennoscandia

Margaritifera margaritifera is a critically threatened species in Europe. Metal pollution may be one of the reasons for its decline, but the influence of this factor remains insufficiently studied. Zn, Cu, Ni, Cd, and Pb were determined in the foot tissue of the freshwater pearl mussel Margaritifera margaritifera (bivalvia, margaritiferidae) from Green Belt rivers of Fennoscandia [the Murmansk region (Kola Peninsula) and Karelia (northern part)] and the accumulation of the metals was shown to be variable; however, their levels in the molluscs, being quite long-lived aquatic organisms, do not exceed the established standards of the Russian Federation. The recorded levels of the metals in the foot tissue of the Margaritifera margaritifera can be considered indicators of the background levels of geologic and anthropogenic metal concentrations in the environment influencing the distribution and development of this protected species in the lake-river systems of the Green Belt of Fennoscandia.

Relationship between different physiological processes of Tomato seedlings exposed to acid mine water Uncovered using correlation analysis

This study was conducted to assess the correlation between growth response, phytoaccumulation factor of different tissues, and elemental composition in tomato seedlings exposed to acid mine water (AMW). In pairwise correlation determinations values of plant height, stem diameter, seed germination indices (radicle length, final germination percentage (FGP), emergency rate index (ERI), vigour index (VI), germination percentage (G%) and germination rate index (GRI)) and the elemental compositions (Cd, Cr, Cu, Ni and Zn) in the different plant tissues, root (root accumulation factor = RAF), stem (stem translocation factor = STF) and leaves (leaf translocation factor = LTF) were selected for the relationship determinations. Pearson correlation coefficients were calculated and revealed the relationships between the paired parameters. The study concluded that the strongly correlated physiological parameters were jointly co-ordinated in tomato seedlings exposed to AMW.

Phosphorus and Silicon Fertilization with Improved Water Management as Potential Remedies for Growing Rice Seedlings in Heavy Metal and Metalloid Contaminated Soil

ABSTRACT Studies covering combined effects of agronomic management strategies and their interactions for safer rice production in multiple heavy metal [cadmium (Cd) and lead (Pb)] and metalloid [(arsenic (As)] contaminated soil are rare. Therefore, the effectiveness of phosphorus (P) or silicon (Si) addition together with soil water management (flooded or aerobic) in a soil contaminated with multiple heavy metals was tested in a pot experiment for 8 weeks. Growth of rice was retarded under flooding (27%) compared to aerobic conditions, and application of P led to recover the reduction in growth. Aerobic and flooded water managements could decrease 66% As and 84% Cd concentrations in rice tissues, respectively. Applications of P or Si could decrease only 22% As (only under flooded condition) and 24% Cd (only under aerobic condition) in rice tissues. Accumulation of Pb in rice was not observed. Aerobic soil lowered the concentrations of As, Cd and Pb in the soil solution when compared to flooding. Moreover, As and Pb concentrations in soil solution increased with time while that of Cd declined. Appropriate water management was the most efficient in reducing heavy metals and metalloids accumulation in rice seedlings while the effects of P or Si were marginal.

Effects of Straw Removal Measure on Soil Cd Bioavailability and Rice Cd Accumulation

A field experiment was conducted in a lightly Cd-contaminated rice field in Ningxiang City, Hunan Province, to study the effects of straw removal measures on the soil Cd bioavailability and rice Cd accumulation. The results showed that:① two consecutive seasons of straw removal measures (T1-T4 treatments) effectively increased soil pH by 0.04-0.58 units, reduced soil organic matter by 0.68%-25.87%, and reduced the Cd content of rhizosphere soil by 3.76%-12.78%. ② The proportions of Cd in the acid-extractable fraction and oxidizable fraction decreased, and the proportion of Cd in the residual fraction increased. Furthermore, straw removal measures significantly reduced the bioavailability of Cd in rhizosphere soil, and the Cd contents in TCLP, DTPA, and CaCl2 extracts all significantly decreased compared with those in CK. ③ The straw removal measure could significantly reduce the content of DOC and Cd in soil pore water; and the contents of Cd in soil pore water decreased by 4.54%-40.00% and 2.75%-67.34% under the straw removal measure (T1-T4) for two consecutive seasons, respectively, indicating that DOC was one of the key factors affecting the content of Cd in soil pore water. ④ Two consecutive straw removal measures (T1-T4) reduced the accumulation of Cd in different rice tissues, among which, under the treatment of all straw and root removal (T4), the Cd contents of brown rice in late rice planting in 2020 and early rice planting in 2021 decreased by 18.52% and 39.69%, respectively. Therefore, full or partial removal of straw in Cd-contaminated rice fields is a powerful measure to reduce the risk of exceeding Cd levels in brown rice.

Bioaccumulation of heavy metals in commercially important marine species from Puducherry coast, Southeast India

Safety of aquatic products is one of the important public health concerns globally, mainly in developing countries with culture and capture fisheries. In the present study, the bioaccumulation of heavy metals such as Cu, Zn, Cr, Pb, As and Cd in the muscle tissues of crustaceans, molluscs and finfishes collected from the Pondicherry (Puducherry) coast were determined using inductively coupled plasma mass spectrometry (ICP-MS). Among the analysed organisms, maximum concentration of Cu (26.1 ±0.83μg/g) was observed in Perna viridis, Zn (25.03 ±0.82μg/g) in Charybdis feriata, 1.33 ±0.04μg/g of Cr in Atule mate, 1.48 ±1.05μg/g of Pb in Sardinella fimbriata, 2.88±2.16μg/g of Cd in Nemipterus jopanicus and 0.72 ±0.15μg/ g of As in Decapterus russelii. Among the various marine organisms studied, the benthic species showed higher metal accumulation than the pelagic species. The heavy metal accumulation level differed significantly between the organisms. The elemental levels in analysed organisms are within the maximum acceptable levels proposed by various international standards and guidelines. Hazard index (HI) of all the analysed marine organisms showed distinctly lower values than threshold value as suggested by World Health Organization (WHO) and Food Safety and Standards Authority of India (FSSAI) for all the studied elements. Overall, the analysed marine organisms are considered safe for human consumption and export. This study provides the baseline data on heavy metal contamination in edible marine organisms from the Puducherry coast of India that will help in developing effective management plans and continuous monitoring of the coast.

Straw removal or non-removal affects cadmium (Cd) accumulation in soil–rice (Oryza sativa L.) system at different ambient air Cd levels

Despite the potential importance of the removal of contaminated straw for heavy metal output from agricultural soils, previous studies have primarily focused on the variation in the metal concentration without considering the impact input of heavy metals from atmospheric deposition. Here, rice was grown under field conditions, and, as a reference, in a deposition-free environment, and exposed to different ambient air Cd levels. Two consecutive years of pot experiments were conducted in two study areas (ZZ and LY) to examine the changes in soil physicochemical properties as well as Cd accumulation in the soil–rice (Oryza sativa L.) system in response to straw return or removal. The results showed that rice straw return enhanced the soil pH and organic matter (OM) content, but reduced the soil redox potential (Eh); and the variation in amplitude increased with number of cultivation years. After two years of cultivation, the concentrations of soil total Cd and extractable Cd in the straw-removal treatments reduced by 9.89–29.49% and 4.88–37.74%, respectively, whereas those in the straw-return treatments exhibited a slight decrease, or even an increase. This indicated that straw removal could effectively reduce the concentration and bioavailability of Cd in contaminated farmland, which was further confirmed by the results for accumulation of Cd in rice tissues. In addition, the contribution from atmospheric deposition was confirmed by the greater variation in Cd concentration in soils and rice tissues under deposition-free conditions. A major implication of our findings is that the adoption of reasonable straw-treatment measures and proper control over ambient air heavy metals can promote the remediation efficiency of Cd-contaminated fields.

PHYTOREMEDIATION OF CADMIUM POLLUTANTS IN WASTEWATER BY USING CERATOPHYLLUM DEMERSUM L. AS AN AQUATIC MACROPHYTES

The current study carried out a test of phytoremediation for the removal of cadmium Cd pollutants, which is one of the most important heavy metal pollutants in the aquatic environment, by using the submerged Ceratophyllum demersum L., as one of the aquatic macrophytes which is commonly named coon tail or rigid hornwort, and evaluating its effectiveness in phytoremediation of cadmium Cd pollutants from different sources of wastewater under the current study which includes Cooling Electric Generators (CEG), Domestic Sewage Water (DSW), and Washing and Lubricating Cars (WLC). 15 random water samples were collected during February and March of 2021, with 3 replicates for each sample. C. demersum (9) plant samples were also randomly collected in 2021, with three replications. A sampling of plants included withdrawing the entire plant (roots-like, stems-like and leaves-like branchlets) with an amount of river water. It was found from the current study that the best values for Cd removal were observed during the fifteenth and twelfth days of the aquaculture durations which were represented by the lowest values of Cd concentrations as 7.9 ± 4.3 μg/L and 31.5±20.2 μg/L respectively, while the worst values for Cd removal were showed during the third and sixth days of the aquaculture durations which represented by the highest values of Cd concentrations as 86.9±40.8 μg/L and 38.6±19 μg/L respectively. The best significant abilities of C. demersum L.to reduce Cd levels were in aquaculture treated with (CEG) wastewater as about 97.9%, 94.1%, and 91.3 % during 15, 12, and 9 respectively days of aquaculture durations followed by removal percentages in aquaculture treated with (DSW) as 92% and 89.0% during 15 and 6 respectively days of aquaculture durations and (WLC) wastewater, as 85.3% in the fifteenth day of aquaculture durations. These results mean that C. demersum probably has contributed to high phytoremoval rates for Cd pollutants from its in vitro polluted aquaculture, especially in the late durations of aquaculture durations. It was also found that the highest accumulation levels for Cd were in the tissues of leaves-like, which were about 189.9±74.7 μg/g, followed by tissues of roots-like, as about 133.2±65.4 μg/g, while the lowest values were in the tissues of stems-like, as about 72.9±28.8 μg/g. The best significant cumulative adsorption percentage values for Cd in leaves-like tissues of C. demersum L. were ascending as about 81.1%, 80.3%, 78.7%, and 75.9% during 15, 12, 9, and 6 respectively days of aquaculture durations followed by percentage values for Cd adsorption percentage in roots-like as 74.7% and 73.5 % during 15 and 12 respectively days of aquaculture durations. The less significant cumulative adsorption percentage value for Cd in stems-like tissues of C. demersum L. was 11.8% followed by 32.5% in roots-like during the third day of the aquaculture duration. These results mean that cumulative tissue adsorption for Cd particularly tends to concentrate progressively more in leaves-like tissues than in the roots-like of C. demersum, and tends to be less concentrated in the stem-like internodes of these submerged aquatic plants.

Foliar zinc reduced Cd accumulation in grains by inhibiting Cd mobility in the xylem and increasing Cd retention ability in roots1

Cadmium (Cd) pollution endangers the safe utilization of paddy soils, and foliar zinc (Zn) can reduce the toxic effects of Cd. However, little is known about the effects of foliar Zn application on the transport and immobilization of Cd in key rice tissues and the physiological state of rice plants. A pot experiment was conducted to explore the effects of spraying 0.2% and 0.4% Zn (ZnSO4) during the early grain-filling stage on Cd transport in rice, photosynthesis, glutathione (GSH) levels, Cd concentrations in xylem sap, and the expression of Zn transporter genes. The results showed that grain Cd concentrations in the 0.2% Zn and 0.4% Zn treatments were 24% and 31% lower, respectively, than those of the control treatments at maturity. Compared with the control treatments, the 0.4% Zn treatment increased Cd by 60%, 69%, 23%, and 22% in husks, rachises, first internodes, and roots, respectively. Application of Zn reduced xylem Cd content by up to 26% and downregulated transporter genes (OSZIP12, OSZIP4, and OSZIP7a) in flag leaves. Foliar Zn increased Cd bioaccumulation in roots while decreasing Cd bioaccumulation in grains. Zn reduced GSH concentration in flag leaves and stems, inhibiting photosynthesis (intercellular CO2 concentration, transpiration rate). Taken together, foliar Zn can reduce the expression of Zn transporter genes and the mobility of Cd in the xylem, promoting the fixation of Cd in husks, rachises, first internodes, and roots, ultimately reducing Cd concentration in rice grains.