Amount Of Cd Research Articles

Study on the soil pollution condition around the domestic wastewater

The rapid development in the population of the earth, the increase in the level of consumption of people leads to an increase in the amount of household waste from year to year, which, in turn, increases the negative impact on the environment of their collection and storage areas, that is, household waste landfills. From these studies, the state of contamination of the soil as scattered around the municipal landfill, the sources factors affecting the contamination were described. The main purpose of the conducted research is to determine the level of pollution of the soil under the influence of household waste. The researches were conducted in the soil scattered around the Tashkent municipal waste dump, located in the Ohangaron district were of the Tashkent province. The results showed that in the chemical pollution of irrigated typical gray soils, the domestic landfill is considered the main pollutant source, and the level of pollution decreases from the distance of 1.2 km from the landfill, and into according to the soil layers, it decreases uniformly from the top to the bottom, starting from the 70 cm layer.The soil scattered around the landfill is contaminated with organic pollutants, ash elements and heavy metals and other pollutants, including the total amount of Cd 3.1 times, As 4.39 times, Sb 2.46 times compared to the permissible limit share. , W 4.6 times and other heavy metals increased to different degrees.

HEAVY METAL CONCENTRATION IN SEDIMENT AND WATER OF RIVER NYAMINDI, KIRINYAGA COUNTY, KENYA

Toxic heavy metals get into humans through absorption, inhalation and ingestion. All heavy metals are toxic to animals and plants when present in excessive amounts. The adverse effects of heavy metals in mammals may manifest in disorders such as growth retardation, decrease in longevity, changes in reproductive cycles, chronic diseases and formation of tumours. River Nyamindi flows from Mt. Kenya Forest passing through rocks, soil, agricultural land, residential areas and urban centres. Geological factors and human activities may have made heavy metals get into the river water. Since the water is used for domestic purposes and irrigation, it was necessary to determine if heavy metal concentration in river Nyamindi has reached alarming levels. Water and sediment samples were collected along river Nyamindi during wet and dry season. The samples were digested appropriately and the concentration of eight heavy metals determined using ICP-MS. The mean amount of Cd, Cr, Ni, Pb, Zn, As, Mn and Se in sediment were 0.0882, 41.1219, 91.7718, 10.7445, 54.3880, 2.4561, 1753.5587 and 5.7648 mg/kg respectively during wet season and 0.0590, 39.1176, 559.0917, 0.3781,76.3715, 3.0114, 1714.4195 and 6.5488 mg/kg respectively during dry season. The mean concentration of the same metals in water was 0.00005, 0.0167, 0.1943, 0.0223, below detection limit (BDL), 0.0002, 0.1379 and BDL ppm respectively during wet season and 0.0009, 0.0005, 0.0148, 0.0184, BDL, 0.00003, 0.0080 and 0.00003 ppm respectively during dry season. The mean amount of Cr, Ni and Mn in sediment were found to be above WHO and US EPA permissible limits during both seasons. The mean concentration of Cr and Mn in water were above WHO and KEBS/WASREB permissible limits during wet season. However, during dry season, all the eight heavy metal concentrations in water were below WHO, KEBS/WASREB permissible limits. Therefore, as far as the eight heavy metals are concerned, water from river Nyamindi was not be potable during rainy season but was potable during dry season. However, further investigations should be carried out to determine other water parameters to confirm it’s suitability as potable water.

REDUCTION RATE OF SOME HEAVY METAL IN DIFFERENT CONCENTRATIONS USING Pseudomonas aeruginosa ISOLATED FROM TENNARY WASTEWATER EFFLEUNT

Industrial developments led to environmental pollution with toxic heavy metals which spreading all over the world. Heavy metal pollution, characterized by its heightened toxicity, resistance to biodegradation, and biological accumulation, has significantly jeopardized both human health and ecological stability. Microbial activities offer a potential avenue for immobilizing, removing, and detoxifying active heavy metal ions in the natural environment. This research aimed to study the ability of Pseudomonas aeruginosa in reducing the amount of Cd, Ni, Cr, Zn and Pb that found in tannery wastewater and to investigate its survivability in high concentrations of these metals. In this study Pseudomonas aeruginosa, was isolated from tannery effluents wastewater. Pseudomonas aeruginosa has been incubated in medium contained 50, 100, 300, 500 and 1000 ppm of Cd, Ni, Cr, Zn and Pb for 6, 12 and 24hrs at 37 °C. Results showed that Pseudomonas aeruginosa was able to cause a significant reduction of Cd, Ni, Cr, Zn and Pb at incubation time of 24 hours at concentration of 50, 100 and 300 ppm ,the reduction level for Ni were (96.5%, 96.2% and 96.4 %) respectively, Cd (76.4%, 82.1% and 83.8 % )respectively, Cr showed reduction rates of ( 97.7% , 99.4% and 99.1%) respectively, Pb ( 87.3% ,91.9% and 89.6%) respectively, and (82%, 87.6% and 80.1 %) respectively for Zn, Pseudomonas aeruginosa was not able to grow at concentration level of 500 and 1000 ppm for Cd, Ni, Cr, Zn and Pb. These results indicated that Pseudomonas aeruginosa is able to survive in tannery effluents wastewater containing high levels of Cd, Ni, Zn, Cr and Pb. Therefore, more research is recommended to study the ability of this species to remove Cd, Ni, Cr, Zn and Pb in different conditions.

Effective mitigation of Cadmium contamination in soil through Sawdust Biochar application

Cadmium (Cd) contamination in soil is a serious environmental concern, and this study examines the effectiveness of sawdust biochar in reducing Cd contamination over three months. The study explores different sawdust biochar application rates and their effects on the amount of extractable Cd in the soil. According to the study, sawdust biochar has a high potential for addressing Cd pollution. Importantly, over the duration of the investigation, extractable Cd concentrations gradually decreased as a result of the use of biochar. In particular, compared to lesser application rates of 2.5% and 1.25%, the highest biochar application rate (5%) resulted in a significant reduction in cumulative leachable Cd content. Additionally, compared to the control group, all biochar-amended soils showed considerably decreased cumulative leachable Cd levels. The leachate study demonstrated the time-dependent efficiency of biochar in lowering Cd concentrations, with Cd concentration declining from 14 mg/L in August 2023 to a meager 0.004 mg/L in October 2023. Diffusion within the porous structure of biochar was determined to be the main process underlying heavy metal adsorption. However, the observed decrease in the effectiveness of heavy metal removal with biochar may be explained by surface oxidation, which creates a greater number of accessible adsorption sites. Furthermore, the soil's capacity to absorb Cd2+ was greatly improved by the raised pH brought on by biochar application, further enhancing Cd removal. The study also showed the importance of pyrolysis temperature on biochar characteristics, with higher temperatures greatly improving Cd adsorption capability. This study's findings highlighted the significant potential of sawdust biochar as a powerful technique for reducing soil Cd pollution. These results highlighted the potential of biochar for Cd remediation and crucial role that pyrolysis temperature plays in determining biochar's characteristics and adsorption capacity.

Assessment of Fe, Ni, Zn, Cu, Cr, and Cd Migration in Soil Profiles Affected by Open Dump Leachate in Tanjero area

The properties of an open dump area are important to the application of the elements to the soils and their migrations through soil depth; therefore this study was investigated to evaluate the migration of elements in an open dump area. Soil samples were taken from three soil profiles, one of them was at an open dump site, and the second and third profiles were taken at different distances from the open dump site. In total eighteen soil sample were collected. Some soil physical and chemical properties were determined for each horizon. Total concentrations of Fe, Ni, Zn, Cu, Cr, and Cd were determined in each soil sample. The results indicated that the Fe had the highest value and the Cd had the lowest values in all soil samples. The orders of profiles for the total heavy (Ni, Cd, and Cr) metals were as follows: Profile1 > profile3 > profile 2. The order of profiles for the total heavy (Zn and Cu) metals was as follows: Profile 1 > profile 2 > profile 3. The mean value of total Ni ranged between 9.17 and 11.13, Cd between 0.29 and 0.37, Cr between 2.67 and 3.36, Zn between 6.90 and 17.23, and Cu between 4.90 and 12.52. The highest amount of total Ni, Cd, Cr, Zn, and Cu were observed in open dump area (profile 1) with the mean value (11.13, 0.37, 3.36, 17.23, and 12.52) respectively, compared to the profile 2 and 3. In general, the heavy metals did not show a specific pattern of distribution with depth in the three soil profiles, because there are many factors affecting migration of heavy metals in soil depth. In both profile 2 and 3, some of the heavy metals migrated in soil depth.

Simultaneous removal of Methylene blue and Cadmium from aqueous solution by a novel sulfonated material: Characterization, mechanism and application

Remediation of water bodies contaminated by organic or inorganic pollution has attracted widespread attention, only a few research focused on the remediation of organic-inorganic combined water pollution. In this study, a novel sulfonated material (HMFA), modified from coal fly ash (CFA) through alkali fusion and hydrothermal methods, was synthesized for the simultaneous removal of Methylene blue (MB) and Cadmium (Cd(II)) from wastewater, achieving the waste-control-waste strategy. Characterization results showed that functional groups such as hydroxyl and sulfonic acid groups are favorable for adsorption. The environmental factors exerted influence on the adsorption, with the presence of competing ions producing the most significant inhibitory effect. Under optimal conditions, the adsorption amounts of MB and Cd(II) were 116.69 and 93.53 mg g-1 in single system and 100.23 and 85.49 mg g-1 in binary system, respectively. The results of model fitting showed that the removal of MB and Cd(II) by HMFA in single system was consistent with pseudo-second-order kinetic model and Langmuir model. Apart from electrostatic attraction, the primary adsorption mechanisms on HMFA include hydrogen bonding for MB, as well as ion exchange and complexation for Cd(II), quantitative calculations have been carried out. HMFA remained favorable recyclability, and had higher selectivity on MB in natural water bodies. In conclusion, as a low-cost and efficient adsorbent material, HMFA has great potential for dye and heavy metal pollution control, which can provide more reference and theoretical support for solid waste resource utilization and dye/heavy metal removal in wastewater.

Study on the migration behaviour of heavy metals at the improved mine soil-plant rhizosphere interface

ABSTRACT With the increasing shortage of land resources and the aggravation of soil pollution in mining areas, the remediation of soil in abandoned mining areas has gradually attracted people's attention. The remediation of heavy metal contaminated soil in mining areas is the key to reduce the harm of heavy metals to the environment and human health. In this study, municipal sludge and phytoremediation technology were combined to investigate the migration and transformation of heavy metals at the soil-plant interface in improved mining areas through indoor pot experiments. The results showed that heavy metals in non-rhizosphere soil entered the rhizosphere environment with the growth of plants, leading to the increase of heavy metal content in rhizosphere soil. The cumulative amounts of Cu, Zn, Pb and Cd were 1299.32, 832.10, 347.89 and 71.34 mg/kg, respectively. The content of oxidized Cu and Zn decreased with increasing planting days, while the oxidized Pb and Cd showed an increasing trend. Under acidic conditions, H+ is easy to compete with heavy metal ions for exchangeable positions in the clay mineral layer, so that the reducible heavy metals are easy to be converted into exchangeable states. In this paper, the effects of various factors on the distribution of heavy metals were discussed by adjusting soil pH, adding humic acid and root exudates, so as to analyse the migration and transformation mechanism of heavy metals at the soil-plant interface, and provide a reliable theoretical basis for soil remediation in mining areas.

Combined Effects of Microbial Inoculation and Activated Carbon/Biochar on the Accumulation and Transfer of Nutrients and Potentially Toxic Metals in Maize Plants Grown on a Contaminated Soil

ABSTRACT This study was conducted in a greenhouse pot experiment to assess the effects of biochar (BC) or activated carbon (AC) alone or in combination with arbuscular mycorrhizal fungus (AMF) Glomus mosseae or acid-producing bacteria (BA) Bacillus polymyxa on plant growth, EDTA-extractable Cd and Pb, and contents of heavy metals (Cd and Pb) and nutrients (Ca, Mg, K, and P) in maize (Zea mays L.) grown on sewage wastewater contaminated soil. The results showed that most treatments with BC, AC, or its co-application with microbial inoculation led significantly to greater nutrient uptake and promoted growth of maize than non-treated plants. Additionally, the soil additives used decreased the amounts of EDTA-extractable Cd (by 28.7%-100%) and Pb (by 22.8%-94.3%). The applied treatments caused significant decreases in Cd concentrations and the bioconcentration factor (BCF) of Zea mays. The highest shoot Cd reduction was observed for AC (53%), followed by AC+BA (36.9%) > AMF (34.5%) > AC+AMF (28.5) > BA (28.3%) > BC+BA (26.1%) > BC (22.7%). However, more Cd was accumulated in the roots of plants treated with AMF by 63.7% with a lower value of translocation factor (TF) compared to control soil. In contrast, the treatments increased the levels of Pb in the maize plants, and BC coupled with AMF showed the greatest Pb accumulation. It could be concluded that the investigated additives can be applied as immobilizing agents for Cd in the soil but maize plants as phytoextractants for both metals in sewage-contaminated soil are not feasible, as indicated by insufficient phytoextraction efficiency.

Exogenous Xyloglucan Oligosaccharides Alleviate Cadmium Toxicity in Boehmeria nivea by Increasing the Cadmium Fixation Capacity of Cell Walls

Xyloglucan is an important component of hemicellulose, and xyloglucan oligosaccharides (Xh), which are metabolized by xyloglucan, play an important role in plant growth and development. However, the regulatory effects of the external application of Xh under cadmium (Cd) stress have not been determined. In this study, we evaluated the mechanism by which Xh contributes to resistance to Cd stress in ramie, a candidate plant species for toxic ion removal. The external application of Xh effectively attenuated the effects of Cd on ramie growth and photosynthetic pigments. Cd stress can also inhibit the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX), resulting in a significant increase in the extent of membrane lipid peroxidation. After the external application of Xh, antioxidant enzyme activity was up-regulated, and damage to membranes in plants was reduced. In addition, the external application of Xh increased Cd retention in roots, thereby significantly decreasing Cd content in shoots. The external application of Xh also regulated the subcellular distribution of Cd and increased the Cd content of the cell wall. In particular, a root cell wall analysis revealed that Cd+Xh treatment significantly increased the hemicellulose content in the cell wall and the amount of Cd retained. In summary, the external application of Xh alleviates Cd toxicity in ramie by increasing the hemicellulose content and the Cd fixation ability of the cell wall and by reducing membrane lipid peroxidation via antioxidant enzymes.

Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Here, a pot experiment was designed to evaluate the phytoremediation potential of ryegrass (Lolium perennne L.) for Pb- and Cd-polluted soils under various drought levels in the presence of farmyard manure (FYM). Three levels of Pb (0, 300, and 600 mg kg−1), Cd (0, 100, and 200 mg kg−1), and drought (field capacity 100, 50, and 30%) as well as two levels of FYM (0 and 1%) were used in this experiment. Results from this study showed a significant decrease (up to 84%) in the overall growth and physiology of ryegrass. A substantial increase in antioxidants (SOD, CAT, and POD) was observed under HMs and drought stress. By the application of FYM, antioxidant activities were significantly reduced. The ryegrass accumulated higher amounts of Pb (up to 150 mg kg−1 in shoots and 193 mg kg−1 in roots) and Cd (up to 71 mg kg−1 in shoots and 92 mg kg−1 in roots) in plant tissues; however, an FYM addition significantly reduced the accumulation of both metals. Furthermore, the results of this research indicated that ryegrass has a promising ability to phytoremediate Pb and Cd, and the addition of FYM may be helpful in enhancing metal stabilization and plant growth despite water constraints.

Understanding the suitable alloying conditions for highly efficient Cu- and Mn-doped Zn1-xCdxS/ZnS core-shell quantum dots

Doping of alloyed colloidal quantum dots (QDs) has garnered significant attention for providing tunable and Stokes-shifted emission. By alloying the host semiconductor nanocrystals (NCs), their band gap can be tuned. With the specific addition of dopant ions, these NCs can emit tunable emissions within the visible spectrum. However, while doped and alloyed quantum dots (QDs) have shown promise for tunable emissions, their emission qualities have not been consistent across the spectrum. Here, we report the synthesis of high-quality Cu- and Mn-doped ZnxCd1-xS (x = 0–1) alloyed QDs by a colloidal non-injection method. In this study, we examined the effect of different dopant ions on the optical properties of similar alloyed nanocrystals. The deposition of a ZnS shell on these doped QDs significantly improves their quantum yield (QY), increasing it from 7.0 % to 50.0 % for Cu-doped QDs and from 30.0 % to 80.0 % for Mn-doped QDs. The Cu-doped QDs exhibit tunable emission from green to red across the visible spectrum by varying the Zn/Cd ratio, whereas the Mn-doped QDs show a fixed orange emission. Interestingly, the Cu-doped alloyed QDs show a contrasting trend in quantum yield (QY) compared to those of Mn-doped QDs when the amount of Cd in ZnCdS alloyed QDs is systematically changed. As the amount of Cd increases in the ZnCdS alloyed QDs, the Cu-doped QDs show both an increase in average lifetime and an increase in QY. In contrast, for the Mn-doped QDs, the decay lifetime values remain fairly constant for different amounts of Cd in the ZnCdS alloyed QDs, but the QY decreases as the amount of Cd increases. The results of this study may facilitate the design of optimal alloying combinations for Cu/Mn-doped QDs in optoelectronic applications.

Characteristics of Cadmium Concentration and Transport of Pueraria thornsonii in Farmland with Different Cadmium Pollution Degrees

This study aimed to elucidate the cadmium (Cd) concentration and transport characteristics of Pueraria thornsonii in farmland with different Cd pollution degrees, so as to provide a reference basis for phytoremediation of Cd-contaminated farmland. The multi-point experiments in farmland with different Cd pollution degrees[ω(Cd) 0.32-38.08 mg·kg-1] were conducted, and the biomass (dry weight), Cd content, accumulation, concentration, and transport of Cd in P. thornsonii tissues under the main growing period were assessed. According to the results, for P. thornsonii, the tuber dry weight ranged from 5.04 to 11.98 t·hm-2, biomass ranged from 13.21 to 29.07 t·hm-2, and Cd accumulation ranged from 15.74 to 106.03 g·hm-2in the study area. The pattern of Cd uptake by P. thornsonii showed that the main vine>leaf>lateral branches>basal part of sti>tuber. The Cd content in P. thornsonii tissues considerably increased with soil Cd content (P<0.05), whereas the biomass decreased significantly (P<0.05). The Cd concentration and transport factor of aboveground parts in P. thornsonii showed a trend of initially falling, then increasing and decreasing again, whereas the Cd enrichment and transport coefficient of tubers gradually decreased. Correlation analysis revealed that the amount of Cd in the soil was a major predictor of Cd accumulation in P. thornsonii. Under light to moderate Cd contamination, the commercial portion of P. thornsonii (arrowroot)[ω(Cd) 0.03-0.22 mg·kg-1] was less than the standard limit for medicinal plants (≤ 0.30 mg·kg-1). In P. thornsonii from moderately contaminated areas, the Cd concentration and transport factor of aboveground parts were 2.43-7.97 and 3.02-9.81, respectively. This indicates that P. thornsonii is a prospective plant ideal for remediating Cd-contaminated soil because of its high capacity to transfer and enrich Cd.

Differences in Cadmium Uptake and Accumulation in Seedlings of Wheat Varieties with Low- and High-Grain Cadmium Accumulation under Different Drought Stresses.

Cadmium (Cd) and drought, as abiotic stresses, have long been significant challenges for crop growth and agricultural production. However, there have been relatively few studies conducted on the effects of drought stress on Cd uptake, especially regarding the differences in Cd uptake characterization in varieties with varying Cd accumulation under different drought stress. To investigate the effects of drought conditions on Cd uptake by wheat in different genotypes under specific background levels of Cd pollution, we validated the differences in root absorption characteristics of low- (YM) and high-grain Cd accumulating wheat genotypes (XM) using non-invasive micro-test technology, and we conducted a hydroponic experiment on the Cd addition and different drought levels in a climate-controlled chamber. The biomass, root morphology, Cd uptake, and accumulation were determined under Cd (100 µmol L-1) and different drought levels of 0% (0 MPa), 5% (-0.100 Mpa), 10% (-0.200 Mpa), and 15% (-0.388 Mpa) simulated by polyethylene glycol (PEG-6000). We found that the simultaneous exposure to Cd and drought had a suppressive effect on the total root lengths, root surface areas, and root volumes of XM and YM, albeit with distinct patterns of variation. As the concentration of PEG-6000 increased, the Cd concentrations and the amount of Cd accumulated in the roots and shoots of XM and YM decreased. Specifically, the Cd concentration in the roots exhibited a reduction ranging from 12.51% to 66.90%, while the Cd concentration in the shoots experienced an even greater decrease of 50.46% to 80.57%. The PEG-6000 concentration was significantly negatively correlated (p < 0.001) with Cd concentration of roots and shoots and Cd accumulation in roots, shoots, and the whole plants and significantly negatively correlated (p < 0.05) with the total length, surface area, and volume of roots. This study confirms that drought stress (5% PEG-6000) can decrease the uptake and accumulation of Cd in wheat seedlings without significant inhibition of biomass, and the change of root morphology (root length) and the decrease of Cd concentration in roots may be the main direct pathways for achieving these effects under drought stress. This research provides a new perspective and idea for water management in Cd-contaminated farmland.

Piriformospora indica colonization enhances remediation of cadmium and chromium co-contaminated soils by king grass through plant growth promotion and rhizosphere microecological regulation

Poor plant growth and low pollutant bioavailability in contaminated soils limit phytoremediation efficiency. Pot experiments were conducted to investigate the effects and mechanisms of Piriformospora indica inoculation on the phytoremediation of Cd–Cr co-contaminated soils from farmland using king grass. P. indica colonization increased plant biomass by 20.4–24.6% and enhanced Cd/Cr accumulation in root, stem and leave tissues. Root vascular cylinder and cortex were the major structures for Cd/Cr transportation in plants. The amounts of Cd and Cr extracted by king grass considerably increased in the presence of P. indica (by 31.5–88.9% and 22.4–38.4%, respectively), as did the removal efficiency of both metals from soils (by 13.2–32.2% and 23.2–33.5%, respectively). Cd/Cr phytoextraction was closely related to the contents of alkanes, lipids and acids in root exudates. Following inoculation, the respiration of microbial sulfur compounds was promoted in soils at low and medium pollution levels, whereas nitrogen fixation and nitrification were reduced at high pollution level. This study demonstrates that P. indica inoculation enhances the phytoremediation efficiency of king grass for Cd–Cr co-contaminated soils through multiple regulation of plant growth, rhizosphere environment, root exudation and soil microbial function.

The multi-media environmental behavior of heavy metals around tailings under the influence of precipitation

Precipitation can lead to significant leaching of heavy metals from abandoned tailings，resulting in a decline in the quality of the surrounding environment. This study aimed to simulate and quantify the migration patterns and fate of heavy metals in tailings caused by precipitation in various environmental media (tailings, air, water, soil, and sediments) using leaching tests, source apportionment, and a fugacity model. Results revealed that the average contents of Cd, Cu, As, Pb, Zn, and Cr in the un-weathered tailings were 3.43, 495.56, 160.70, 138.94, 536.57, and 69.52 mg/kg, respectively. The ecological risk factors in the tailings as well as in sediments and soils, were in the following order: Cd >Cu >As >Pb >Zn >Cr. A fugacity model based on the mass-balance methods was established, achieving a good agreement between simulation and measured values. The total amounts of Cd, Cu, As, Pb, and Zn leached from abandoned tailings over the 30-year evaluation period were estimated to be 1.09, 62.44, 0.16, 0.94, and 102.12 t, respectively. Soil and sediments are important reservoirs for heavy metals. The sum of the As, Cd, Cu, Pb, and Zn storage capacities in the soil and sediment accounted for 77.28%, 75.63%, 73.94%, 69.39%, and 57.80% of the total storage capacity, respectively. This study could provide the means for the establishment of a targeted pollution control plan, a guide for restoration projects, and will aid in controlling pollution risk and improving the surrounding environment.

The significance of heterophasic ion exchange in active biomonitoring of heavy metal pollution of surface waters

We have carried out studies to examine the possibility of using biosorbents: the epigeic mosses Pleurozium schreberi (Willd. ex Brid.) Mitt., and the epiphytic lichens Hypogymnia physodes (L.) Nyl. in active biomonitoring of heavy metal pollution of surface waters. The dried sea algae Palmaria palmata (L.) Weber & Mohr were used as the third biosorbent. The studies were conducted in the waters of the Turawa Reservoir, a dam reservoir with a significant level of eutrophication in south-western Poland. Incremental concentrations of Mn, Ni, Zn, Cu, Cd, and Pb were determined in the exposed samples. It was shown that a 2-h exposure period increases the concentration of some metals in the exposed samples, even by as much as several hundred percent. High increments of nickel concentrations in the algae Palmaria palmata (mean: 0.0040 mg/g, with the initial concentration of c0 < 0.0016 in the algae) were noted, with negligible increments in concentrations of this metal in mosses and lichens. In contrast, mosses and lichens accumulated relatively high amounts of Cd (mean: 0.0033 mg/g, c0 = 0.00043 mg/g) and Pb (mean: 0.0243 mg/g, c0 = 0.0103 mg/g), respectively.

Element and Water-Soluble Vitamins Profile of Rhus coriaria L. (Sumac) Grown in Different Regions.

In this study, the amounts of some elements and water-soluble vitamins in Rhus coriaria L. (Sumac) samples grown in different regions were analyzed by ICP-OES and HPLC, respectively. The maximum amount of Na, K, Mg, and P was determined in the sumac samples of Kadana, Sheladize, Maraş, and Derishke regions, respectively. The richest regions in terms of trace elements such as Zn, Cu, Fe, Se, Mn, Cr, Mo, Ni, and B were Charput, Derishke, Ranya, Charput, Ranya, Derishke, Elazığ, Derishke, and Kadana, respectively. The highest amount of As, Cd, Pb, and Hg in sumac samples were determined in Kadana, Kadana, Trawanish, and Charput regions, respectively, while the lowest amounts were determined in Maraş, Sheladize, Elazig, and Trawanish regions sumac samples. Since target hazard coefficient (THQ) and total target hazard coefficient (TTHQ) values calculated for minor, toxic and heavy metals investigated in sumac samples are well below one; therefore, they do not pose a health risk. From the result obtained, sumac is a good food additive spice in terms of water-soluble vitamins except ascorbic acid. The amounts of ascorbic acid, thiamine, riboflavin, nicotine amide, nicotinic acid, pantothenic acid, pyridoxine, folic acid, and cyanocobalamin in sumac samples varied between 78.90-36.57, 173.57-61.11, 518.4-182.3, 314.0-105.6, 1292.1-788.7, 779.2-301.7, 385.8-133.4, 826.2-473.1, and 192.6-73.9 µg/g dw, respectively. Differences in the amount of elements and water-soluble vitamins among sumac samples from different regions may be due to geographical and ecological reasons.

Geochemical features of sulfides of the Aktash magnetite-polymetallic deposit, Western Karamazar, Tajikistan (LA-ICP-MS data)

The distribution of trace elements in sulfdes from various ores of the Aktash magnetite-polymetallic deposit (Tajikistan) is studied using LA-ICP-MS method. Sulfdes partly replace banded magnetite ores. Each sulfde type exhibits specifc geochemical features. Galena from sulfde-magnetite ores contains the higher amount of elements of «high-temperature» association (Bi, Ag, Cu) than galena from pyroxene-sphalerite ores, which, in addition to Ag and Bi, also contains higher amount of elements of «medium-temperature» association (Se, Te, and Sb). Sphalerite from sulfde-magnetite and chlorite-pyrrhotite ores contains higher Fe, Cd and Mn amount than sphalerite from pyroxene-sphalerite ores, which is characterized by elevated Co and As contents. Pyrite is depleted in trace elements except for As, the content of which is maximum compared to other sulfdes. The Ag, Se, Bi, Zn, Cd and Ni contents of chalcopyrite from chlorite-pyrrhotite ores are higher than in chalcopyrite from sulfde-magnetite and pyroxene-sphalerite ores. Chalcopyrite from pyroxene-sphalerite ores is characterized by elevated Pb, As, Ge, Te and Sb contents. Relatively high Co, Ni and Se contents are determined in pyrrhotite. In addition to Fe, Cu, Zn, Pb and Au, which form minerals in all types of ores, we suggest by-product extraction of following elements from complex sulfde-magnetite, chlorite-pyrrhotite and pyroxene-sphalerite ores (the Bi, Ag, Se and Te contents of galena and Cd content of sphalerite are shown in brackets): Bi (19520–24650 ppm), Ag (7907–9650 ppm), Se (397–606 ppm) and Te (276– 436 ppm) from galena concentrate and Cd (8525–27670 ppm) from sphalerite concentrate.

Cadmium immobilization during nitrate-reducing Fe(II) oxidation by Acidovorax sp. BoFeN1: Contribution of bacterial cells and secondary minerals

Microbially nitrate-reducing Fe(II) oxidation (NRFO) is widespread in anoxic environments at circumneutral pH, in which Fe(II) oxidation is considered to be mainly catalyzed by nitrite via chemodenitrification after microbial nitrate reduction. Cadmium (Cd) is toxic to organisms, and its availability is strongly affected by iron (oxyhydr)oxides and/or bacteria. However, it remains unclear how NRFO affects the fate of Cd with environmentally relevant concentrations, and the relative contributions of microbes and secondary minerals to Cd immobilization during NRFO. Here, Acidovorax sp. BoFeN1, a typical NRFO bacterium, was used to investigate the Cd immobilization during NRFO at pH 7.0 with 0.1, 0.5, and 1.0 mg/L Cd, respectively. Higher initial Cd concentration resulted in a higher amount of Cd immobilized in precipitates, but showed stronger inhibition on nitrate reduction, acetate metabolism, and cell growth. The presence of Cd barely influenced the Fe(II) oxidation during NRFO or chemodenitrification, but retarded the mineral transformation to secondary crystalline minerals, i.e., lepidocrocite and goethite. The extracellular polymeric substances deposited in the bacteria-mineral precipitates were rich in tyrosine-like and tryptophan-like proteins with negatively charged amino and carboxyl groups. The STEM-HAADF images with EDX mapping demonstrated that Cd was strongly co-localized with Fe on the cell surface and in the periplasm. Cadmium immobilization experiments with bacterial cells or during chemodenitrification indicated that the bacterial cells and secondary minerals formed during chemodenitrification are comparably important for Cd immobilization in the Cd0.1 treatment, while the secondary minerals played a predominant role in Cd immobilization in the Cd0.5 and Cd1.0 treatments. These results suggested that Cd was likely associated with the secondary iron minerals, which precipitated with the proteins on the cell surface and in the periplasm. Our findings provide a comprehensive understanding of the roles of Cd, bacterial cells, and secondary minerals formed via chemodenitrification, as well as their interactions during the complicated NRFO process at circumneutral pH.

Effects of high manganese-cultivated seedlings on cadmium uptake by various rice (Oryza sativa L.) genotypes

Cadmium (Cd) contamination in paddy soil threatens rice growth and food safety, enriching manganese (Mn) in rice seedlings is expected to reduce Cd uptake by rice. The effects of 250 μM Mn-treated seedlings on reducing Cd uptake of four rice genotypes (WYJ21, ZJY1578, HHZ, and HLYSM) planted in 0.61 mg kg−1 Cd-contaminated soil, were studied through the hydroponic and pot experiments. The results showed that the ZJY1578 seedling had the highest Mn level (459 μg plant–1), followed by WYJ21 (309 μg plant–1), and less Mn accumulated in the other genotypes. The relative expression of OsNramp5 (natural resistance-associated macrophage protein) was reduced by 42.7 % in ZJY1578 but increased by 23.3 % in HLYSM. The expressions of OsIRT1 (iron-regulated transporter-like protein) were reduced by 24.0–56.0 % in the four genotypes, with the highest reduction in ZJY1578. Consequently, a greater reduction of Cd occurred in ZJY1578 than that in the other genotypes, i.e., the root and shoot Cd at the tillering were reduced by 27.8 % and 48.5 %, respectively. At the mature stage, total Cd amount and distribution in the shoot and brown rice were also greatly reduced in ZJY1578, but the inhibitory effects were weakened compared to the tillering stage. This study found various responses of Cd uptake and transporters to Mn-treated seedlings among rice genotypes, thus resulting in various Cd reductions. In the future, the microscopic transport processes of Cd within rice should be explored to deeply explain the genotypic variation.