Absorption Of Cr Research Articles

Biochar solutions: Slow and fast pyrolysis effects on chromium stress in rapeseed roots

Chromium (Cr) contamination in agricultural soils, largely due to industrial activities, poses a significant threat to plant growth and productivity. This study examines the effects of Cr stress at concentrations of 100 and 200 mg of K2Cr2O7 per kg soil on rapeseed (Brassica napus) roots and evaluates the mitigating potential of biochar. Biochar, produced through both slow and fast pyrolysis and applied at 30 g per kg soil, was investigated for its ability to neutralize Cr toxicity. Our findings indicate that Cr stress significantly decreased the growth and physiological functions of rapeseed roots. However, biochar application improved soil pH, cation exchange capacity, and the uptake of essential nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium. Additionally, biochar enhanced the production of osmotic regulators like glycine betaine and soluble proteins, as well as indole acetic acid, promoting better root growth and water uptake under Cr stress. Notably, biochar reduced Cr availability and absorption in rapeseed roots, leading to lower levels of stress-related hormones such as abscisic acid, salicylic acid, and jasmonic acid. Among the biochars tested, slow pyrolysis biochar was more effective than fast pyrolysis biochar in mitigating Cr toxicity. These results highlight the potential of slow pyrolysis biochar as a sustainable strategy to alleviate Cr pollution and enhance plant resilience in contaminated soils.

Hexavalent chromium uptake in rice (Oryza sativa L.) mediated by sulfate and phosphate transporters OsSultr1;2 and OsPht1;1

Chromium (Cr) soil contamination is a critical global environmental concern, with hexavalent chromium (Cr[VI]) being especially perilous due to its high mobility, bioavailability, and phytotoxicity. This poses a significant threat to the cultivation of crops, particularly rice, where the mechanisms of Cr(VI) absorption remain largely unexplored. This study uncovered a competitive interaction between Cr(VI) and essential nutrients—sulfate and phosphate during the uptake process. Notably, deficiencies in sulfate and phosphate were associated with a marked increase in Cr(VI) accumulation in rice, reaching up to 76.5 % and 77.7 %, respectively. Employing q-PCR, this study identified significant up-regulation of the sulfate transporter gene, OsSultr1;2, and the phosphate transporter gene, OsPht1;1, in response to Cr(VI) stress. Genetic knockout studies have confirmed the crucial role of OsSultr1;2 in Cr(VI) uptake, with its deletion leading to a 36.1 % to 69.6 % decrease in Cr uptake by rice roots. Similarly, the knockout of OsPht1;1 resulted in an 18.1 % to 25.7 % decrease in root Cr accumulation. These findings highlight the key role of the sulfate transporter OsSultr1;2 in Cr(VI) uptake, with phosphate transporters also contributing significantly to the process. These insights are valuable for developing rice varieties with reduced Cr(VI) accumulation, ensuring the safety of rice grain production.

Phosphorus and selenium compounding mitigates Cr stress in peanut seedlings by enhancing growth homeostasis and antioxidant properties.

Peanut is an economically important crop, but it is susceptible to Cr contamination. In this study, we used peanut as experimental material to investigate the effects of exogenous P, Se interacting with Cr on the nutrient growth and antioxidant system of peanut seedlings by simulating Cr (0μM, 50μM, and 100μM) stress environment. The results showed that exogenous P, Se supply could mitigate irreversible damage to peanut seedlings by altering the distribution of Cr in roots and aboveground, changing root conformation, and repairing damaged cells to promote growth. When the Cr concentration is 100μM, it exhibits the highest toxicity. Compared to the control group P and Se (0 MM), the treatment with simultaneous addition of P + Se (0.5 + 6.0) resulted in a significant increase in root length and root tip number by 248.7% and 127.4%, respectively. Additionally, there was a 46.9% increase in chlorophyll content, a 190.2% increase in total surface area of the seedlings, and a respective increase of 149.1% and 180.3% in soluble protein content in the shoot and roots. In addition, by restricting the absorption of Cr and reducing the synthesis of superoxide dismutase SOD (Superoxide dismutase), CAT (Catalase), POD (Peroxidase), and MDA (Malonaldehyde), it effectively alleviates the oxidative stress on the antioxidant system. Therefore, the exogenous addition of P (0.5 MM) and Se (6.0 MM) prevented the optimal concentration of chromium toxicity to peanuts. Our research provides strong evidence that the exogenous combination of P and Se reduces the risk of peanut poisoning by Cr, while also exploring the optimal concentration of exogenous P and Se under laboratory conditions, providing a basis for further field experiments.

Scalable, acid-resistant polyaniline deposited amidoxime PAN nanofibers for efficient adsorption and detoxification of Cr(VI) wastewater

Chromium (Cr(VI)) metal ions used in industries pose a serious threat to the health of humanity due to the challenge of removal from wastewater and high biotoxicity. Herein, a novel stable and scalable amidoxime modified polyacrylonitrile/polyaniline (AOPAN/PANI) nanofibers membrane (NFM) was prepared via a combined facile electrospinning and interfacial polymerization strategy, and investigated Cr(VI) adsorption performances by batch experiments. The adsorption kinetics, influencing factors, and removal mechanism of Cr(VI) through the scalable AOPAN/PANI NFM was systematically analyzed. The results indicated that the scalable AOPAN/PANI NFM was successfully prepared, and exhibited excellent Cr(VI) absorption capacity (299.56 mg/g), moreover, the prepared NFM exhibits good acid-resistance(pH=2). The pseudo-second-order model conformed to the adsorption kinetics, and the results from batch experiments were matched by the Langmuir adsorption isothermal model. The adsorption of Cr(VI) by the scalable AOPAN/PANI-16 NFM is a non-spontaneous exothermic process. The adsorption mechanism includes electrostatic interaction of Cr(VI) and the scalable AOPAN/PANI NFM, and convert Cr(VI) into low toxicity Cr(III) and chelate. In addition, the scalable AOPAN/PANI nanofibers membrane has good reusable performance. More importantly, this work fully demonstrates the great technical advantages of the industrial application of preparing adsorbent by electrospinning, and provides a novel stable, simple and efficient treatment method for the detoxification treatment of Cr(VI) in acid wastewater.

Biosorption of chromium by live and dead cells of Bacillus nitratireducens isolated from textile effluent

Bacillus nitratireducens was isolated from textile effluent and showed high tolerance to chromium (Cr), reaching up to a 1000 mg/L MIC value. This research was aimed at utilizing biosorbents from live and dead cells of B. nitratireducens to remove Cr from an aqueous solution. A batch biosorption test was performed, and mechanisms analysis was approached by an adsorption-desorption test, SEM-EDS, and FTIR analysis. Cr removal by dead cells in 25, 50, and 100 mg/L of Cr were 58.99 ± 0.7%, 69.8 ± 0.2%, and 82.87 ± 0.11%, respectively, while that by live cells was 73.08 ± 1.9%, 80.27 ± 6.33%, and 86.17 ± 1.93%, respectively. Live cells showed significantly higher Cr removal and adsorption capacities as compared to dead cells. In all concentrations, absorption contributed more than adsorption to the Cr removal by both live and dead cells. Absorption of Cr was subjected to occur due to passive mechanisms in dead cells while involving some active mechanisms in live cells. SEM-EDS confirmed the detection of Cr on the cell surface, while FTIR revealed the shifting of some peaks after the biosorption test, suggesting interactions between Cr and functional groups. Further TEM analysis is suggested to be conducted as a future approach to reveal the inner structure of cells and confirm the involvement of absorption mechanisms.

Determination of Maximum Adsorption Capacity of Chitosan and Carboxymethyl Chitosan on the Absorption of Metal Ions Cr (VI) Based on the Langmuir Equation

Determination of Maximum Adsorption Capacity of Chitosan and Carboxymethyl Chitosan on the Absorption of Metal Ions Cr (VI) Based on the Langmuir Equation

Chromium(VI) removal from water using different bio-adsorbents: Comparison and scope in the treatment of local water bodies with economic analysis

Tannery industries are an important part of India’s economy. India has huge production and consumption of footwear in the world. Leather goods and footwear exports in India were set to reach $5.26 billion in 2022–23. These tannery industries require 40m3 of fresh water per ton of raw material.The water released by these industries are highly contaminated with Cr(VI). Apart from tannery industries,other industrial processes like electroplating, pigmentation also release chromium into the environment. Cr(VI) has adverse effects on humans health, animals and plants. Bio-absorbents exhibit good absorption capacity for Cr(VI). Five different bio-adsorbents have been used,which were collected from wastes.There is hardly any research that shows relation between percentage removal of chromium with respect to size of bio-adsorbents.This study is presented in the same direction. A stock solution was prepared in the laboratory that had similarity in chromium concentration with tannery effluent.Titration (quantitative analysis) was used.On comparison, it was found that pomegranate peel and water chestnut shell showed better Cr(VI) absorption capacity upto 97.83%. A schematic idea has been proposed for the removal of Cr(VI) from drinking water used in rural areas. Economic analysis of the use of these bio-absorbents has proven it to be a better option for Cr(VI)capture.

Enhancement of sweetpotato tolerance to chromium stress through melatonin and glutathione: Insights into photosynthetic efficiency, oxidative defense, and growth parameters

Melatonin (MT) and reduced glutathione (GSH) roles in mitigating chromium (Cr) toxicity in sweetpotato were explored. Plants, pre-treated with varying MT and GSH doses, were exposed to Cr (40 μM). Cr severely hampered growth by disrupting leaf photosynthesis, root system, and oxidative processes and increased Cr absorption. However, the exogenous application of 1 μM of MT and 2 mM of GSH substantially improved growth parameters by enhancing chlorophyll content, gas exchange (Pn, Tr, Gs, and Ci), and chlorophyll fluorescence (Fv/Fm, ETR, qP, and Y(II)). Furthermore, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide ion (O2•−), electrolyte leakage (EL), and Cr uptake by roots (21.6 and 27.3%) and its translocation to shoots were markedly reduced by MT and GSH application, protecting the cell membrane from oxidative damage of Cr-toxicity. Microscopic analysis demonstrated that MT and GSH maintained chloroplast structure and integrity of mesophyll cells; they also enhanced stomatal length, width, and density, strengthening the photosynthetic system and plant growth and biomass. MT and GSH improved osmo-protectants (proline and soluble sugars), gene expression, and enzymatic and non-enzymatic antioxidant activities, mitigating osmotic stress and strengthening plant defenses under Cr stress. Importantly, the efficiency of GSH pre-treatment in reducing Cr-toxicity surpassed that of MT. The findings indicate that MT and GSH alleviate Cr detrimental effects by enhancing photosynthetic organ stability, component accumulation, and resistance to oxidative stress. This study is a valuable resource for plants confronting Cr stress in contaminated soils, but further field validation and detailed molecular exploration are necessary.

Inoculation of chromium-tolerant bacterium LBA108 to enhance resistance in radish (Raphanus sativus L.) and combined remediation of chromium-contaminated soil.

Cr(VI) has been a carcinogen for organisms and a hazard to human health throughout the food chain. To explore a cost-effective and efficient method for removing Cr(VI), a Cr-resistant strain named LBA108 was isolated from the soil of a molybdenum-lead mining area. It was identified as Microbacterium through biochemical tests and 16S rDNA sequence analysis. Following 48 hours of incubation in LB culture medium containing 60 mg L-1 Cr(VI), the LBA108 strain exhibited reduction and adsorption rates for Cr(VI) at 96.64% and 15.86%, respectively. The removal mechanism was subsequently confirmed through Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction analysis. In an experimental setup, radish seedlings were cultivated as test crops under varying levels of Cr stress (ranging from 0 to 7 mg L-1) in a hydroponic experiment. With the inoculation of the LBA108 strain, the fresh weight of radish seedlings increased by 2.05 times and plant length increased by 34.5% under 7 mg L-1 Cr stress. In addition, the plant produced more antioxidant enzymes/enhanced antioxidant enzyme activities such as superoxide dismutase and catalase to prevent oxidative stress. Under Cr stress (6 mg L-1), the accumulation of Cr in rhizomes of radish seedlings increased compared to the control group by 91.44%, while the absorption of Cr by leaves decreased by 52.10%. These findings suggest that the LBA108 strain possesses bioremediation capabilities as a microbial-phytoremediation option for Cr-contaminated soil.

Biosorption of hexavalent chromium by biochar prepared from the Ceratonia siliqua pod: Kinetic, equilibrium, and thermodynamics studies

Ceratonia siliqua pod biochar sample (CBC) was generated in this work from C. siliqua (carob pod waste) biomass (CBM) by slow pyrolysis for 5h at 400°C as an alternative low-cost biosorbent for the removal of Cr(VI). The biosorption parameters that were adjusted were the initial pH (2.0–10.0), temperature (30°C, 40°C, and 50°C), biosorbent dose (0.01–0.03 g/50 mL), initial Cr(VI) concentration (10–100 mg/L), and contact period (0–360 min). The interaction between the surface functional groups on the CBM and CBC and the Cr(VI) ions was found to be the primary mechanism for Cr(VI) sorption via surface complexation and electrostatic interactions, according to the investigation of the pH influence. The Langmuir isotherm was shown to be more well-fitting than the Freundlich and Dubinin-Radushkevich isotherms for the concentration range of 10 to 100 mg/L. The testing results indicated a sorption capacity of 90.909 mg/g of CBM and 131.579 mg/g of CBC. According to kinetic investigations, the absorption of Cr(VI) ions onto CBM and CBC was defined in pseudo-second order. The findings of thermodynamic investigations showed that the biosorption of Cr(VI) ions onto CBM and CBC was an exothermic, spontaneous process. These findings demonstrated that, even for high concentrations of Cr(VI) in industrial wastewater, CBM and CBC could be viable, affordable alternatives as adsorbents.

Cr(VI) absorption in Salvinia minima depends of seasonal development and nutrients availability rather than biomass accumulation

Abstract We analysed the capacity of Salvinia minima plants collected from different seasons to accumulate Cr(VI) in presence or absence of mineral nutrients. Plants were collected in August and November and they were grown in both water and Hoagland solution with and without Cr(VI). August plants showed development of new fronds, a low content of soluble sugars, and an increase in biomass. In November plants, a lower number of new fronds, a higher content of soluble sugars, and a lower increase in biomass were observed. November plants accumulated more Cr than those from August and the growth media showed an increase in DO. These results would indicate that a greater accumulation of biomass (August plants) does not necessarily lead to a greater Cr accumulation. Salvinia plants did not show demand for mineral nutrients except for phosphate and magnesium. Changes in the ion composition of growing media during the assay show possible differences in mineral requirement between higher and lower plants. Our results showed that Cr(VI) accumulation in S. minima plants depends on the development stage and the mineral nutrients composition of the growth medium.

Investigation of the Potential of Empty Fruit Bunch (EFB) and Pressmud for the Removal of Heavy Metals from Wastewater

Improper management of organic industrial wastes, such as empty fruit bunch (EFB) from the palm oil industry and pressmud, i.e., a by-product of the sugar refinery industry can lead to environmental problems. This study aims to investigate the potential of pressmud and EFB as adsorbent materials in wastewater pollution removal. The chemical analysis in this study revealed that the EFB sample contained 7.30% of SiO2, 2.11% of Fe2O3, 1.91% of MgO, 28.02% of CaO, 37.59% of K2O, 1.45% of P2O5, 14.51% of Cl, 4.39% of SO3, and 2.38% of other elements. Meanwhile, the pressmud sample contained 14.32% of SiO2, 1.39% of SO3, 81.71% of CaO, 1.03% of Fe2O3, and the remaining 1.56% of other compounds. The possible adsorption capacities of pressmud and EFB were determined using the Langmuir and Freundlich isotherms. The absorption of Cd, Cr, Cu, Fe, Mn, Ni, and Zn in these samples was analyzed using the Langmuir and Freundlich isotherm models. By comparing both models, the research revealed that the Langmuir model provided a more precise description of the adsorption process for the EFB and pressmud samples and was competently compared to the Freundlich model, as indicated by the highest R2 values. The results indicate the potential of EFB and pressmud as promising reactive materials for heavy metal adsorption, and this involves recognizing possibilities for repurposing these economical and sustainable waste materials.

The effect of different levels of vitamin C and chromium on growth performance, carcass characteristics, digestive organs, immunity, blood constituents, liver enzymes, cecal microflora, meat sensory taste and fatty acid profile of breast meat in broilers.

Antioxidants such as vitamin C (VC) and chromium (Cr), which effectively scavenge free radicals, may improve functional characteristics of the intestine and may reduce intestinal diseases. Cr absorption increases in the presence of VC. In poultry, VC is mainly derived from glucose; hence, Cr is an important component for glucose tolerance. We evaluated the synergistic effects of these two antioxidants together. This study aims to investigate two levels of VC and two levels of Cr and their interaction on growth performance, carcass characteristics, digestive organs, immunity, blood constituents, liver enzymes, cecal microflora, meat sensory taste and fatty acid profile of breast meat in broilers. Two levels of VC (250 and 500mg/kg dry matter [DM]) and two levels of Cr (700 and 1400μg/kg DM) were added to a basic diet for 42 days in five treatments. The 2 × 2 plus 1 (control group) factorial experiment was performed in a completely randomised design for 42 days using 360 one-day-old male chicks. Very low-density lipoprotein, high-density lipoprotein, low-density lipoprotein, total cholesterol and triglyceride level, liver enzymes, antibody titer against sheep red blood cells, fat content, odour, chewing ability, elasticity and oral sensation traits were affected by combination of VC and Cr. Combination of VC and Cr can increase unsaturated fatty acids and decrease saturated fatty acids, as well as improve cecal microbial flora, and may be useful as antioxidant compounds and non-antimicrobial stimulants for economic growth. The use of 250mg/kg of VC and 700μg/kg of Cr is recommended in broiler diets.

Determination of Cd, Co, Cr, Ni and Pb metals in lipsticks samples by Flame atomic absorption spectrophotometry (FAAS)

The study was conducted this work to analyze levels of toxic metals in lipsticks specifically sold in the Bhopal area. Acid digestion process was used to prepare the samples and to quantify the levels of heavy metals, including Cd, Co, Cr, Ni, and Pb Flame Atomic Absorption Spectrophotometry was used. Calibration curves were prepared with good linearity for accurate measurement of concentrations of these metals. All heavy metal observed were within the allowable limit. To assess the health risks, Average daily dose (ADD) and Hazard quotient (HQ) (Ingestion) for all the lipstick samples were calculated. Among these samples, three samples shows higher values among them one belonged to a branded category, while the remaining two were from the non-branded category. These particular Lipsticks samples exhibited higher HQ values (higher than 1), indicating a probable hazard linked of toxic-metals.

Preparation and characterization of deacetylated cellulose acetate/thermoplastic polyurethane nanofiber membranes modified with graphene oxide for methylene blue and Cr (VI) adsorption

AbstractDeacetylated cellulose acetate/thermoplastic polyurethane@graphene oxide (DA/TPU@GO) nanofibrous membranes were prepared through the combination of electrospinning, deacetylation, and ultrasound‐assisted surface treatment techniques. The morphology, wettability, and mechanical properties of composite nanofiber membranes were studied via SEM, TEM, water contact angle measurements, and mechanical tests. Moreover, the adsorption capacity and mechanism of DA/TPU@GO nanofiber membranes for methylene blue and chromium (Cr (VI)) were analyzed. The introduction of active sites from GO led to a significant increase in the adsorption capacity of the DA/TPU@GO composite membranes compared with the DA/TPU composite nanofiber. The composite membrane featured adsorption capacities of 152.7 mg/g (25°C, pH 3) and 122.1 mg/g (25°C, pH 7) for Cr (VI) and methylene blue, respectively, which are higher than most other composite GO‐based adsorbents. The adsorption mechanism of the DA/TPU@GO composite membrane was consistent with the Langmuir isotherm and second‐order kinetic models. Therefore, the DA/TPU@GO composite nanofiber membrane served as an effective adsorbent with broad application prospects in the sewage treatment field owing to its excellent adsorption capacity.Highlights Nanofibers were prepared for the absorption of methylene blue (MB) and Cr (VI). Nanofibers exhibited adsorption capacities of 152.7 and 122.1 mg/g for Cr (VI) and MB. Adsorption mechanism follows Langmuir isotherm and second‐order kinetic models. Nanofibers have wide potential applications in sewage treatment.

Eu3+ Complex-Based Superhydrophobic Fluorescence Sensor for Cr(VI) Detection in Water.

Cr(VI) compounds are bioaccumulative and highly toxic pollutants, and there is a need for simple and fast detection methods to monitor their trace levels. In this work, we developed a Eu3+ complex-based fluorescence sensor to easily detect Cr(VI) in water droplets. Our sensor consists of a nanofibrous membrane electrospun with a blend of polyvinylidene fluoride (PVDF), silica particles, and Eu3+ complex. Upon modifying the membrane surface with fluoroalkyl chemistry, the sensor displayed superhydrophobicity. When a water droplet with Cr(VI) was placed on such a superhydrophobic fluorescence sensor, the overlapping absorption of Cr(VI) and Eu3+ complex facilitated the inner filter effect, allowing the selective detection of Cr(VI) down to 0.44 µM (i.e., 45.76 µg L-1). We proposed and designed of new inexpensive and fast sensor for the detection of Cr(VI).

Critical Evaluation of the Methods for the Characterization of the Degree of Sulfonation for Electron Beam Irradiated and Non-Irradiated Sulfonated Poly(ether ether ketone) Membranes.

Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several advantages such as low cost, thermal and radiation stability and controllable physicochemical and mechanical properties, which depend on the degree of sulfonation (DS). Commercial PEEK was homogenously sulfonated up to a DS of 60-90% and the membranes were prepared using a solvent casting method. Part of the samples were irradiated with a 10 MeV electron beam up to a 500 kGy dose to assess the ionizing radiation-induced effects. Both non-irradiated and irradiated membranes were characterized by Fourier Transformation infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H-NMR) spectroscopy, electrochemical impedance analysis and, for the first time for non-irradiated membranes, by spectrophotometric analysis with Cr(III). The above-mentioned methods for application for DS assessment were compared. The aim of this study is to compare different methods used for the determination of the DS of SPEEK membranes before and after high-dose irradiation. It was observed that irradiated membranes presented a higher value of DS. The appearance of different new signals in 1H-NMR and FT-IR spectra of irradiated membranes indicated that the effects of radiation induced changes in the structure of SPEEK materials. The good correlation of Cr(III) absorption and SPEEK DS up to 80% indicates that the spectrophotometric method is a comparable tool for the characterization of SPEEK membranes.

Effects of Fertilizers and Conditioners on Chromium Uptake of Maize in Chromium-Polluted Farmland

Using agronomic measures to remediate heavy metal chromium (Cr) on farmland is the main measure to achieve the safe utilization of crops. This study was conducted under field trial conditions using locally formulated fertilizers (urea–ammonium phosphate–potassium chloride) as the control. Different fertilizer-type treatments such as ammonium sulfite, calcium magnesium phosphate, and diammonium phosphate were set up. Biochar and soil conditioner PX5B were chosen to compare the impacts of each to study the effects of different fertilizer types on maize yield, Cr content in each part, the bioconcentration factor, the translocation factor, and the available content of Cr in the soil. The results show that, compared with the formulated fertilizer, all treatments improved pH and soil organic matter and reduced the effective state of Cr content in the soil by 15.05% to 42.66%. The Cr content of maize grains under biochar and soil conditioner PX5B treatments were 0.80 mg·kg−1 and 0.88 mg·kg−1 with a 39.95% and 33.83% reduction, respectively, whereas the Cr content of maize grains under various fertilizer treatments was in the range of 0.82~1.32 mg·kg−1 with a 0.75%~38.19% reduction, respectively. Among the different fertilizer treatments, urea–calcium magnesium phosphate–potassium chloride, urea–diammonium phosphate–potassium chloride, ammonium sulfite–calcium magnesium phosphate–potassium chloride, and ammonium sulfite and urea–calcium magnesium phosphate–potassium chloride treatments reduced the Cr content of maize grains to within the range of the national food safety standard of China (1.0 mg·kg−1). The best reductions in the effective state Cr content of the soil and the Cr content of maize grains were achieved by ammonium sulfite–calcium magnesium phosphate–potassium chloride treatment, which was able to achieve similar reductions to the two conditioners. It also had a reduction effect on the Cr content of maize roots and straws, the aboveground bioconcentration factor (BCF), and the primary translocation factor (PTF). Therefore, the combination of ammonium sulfite and calcium magnesium phosphate is the best fertilizer combination to block the absorption of Cr by maize and has some implications for the fertilization of farmland under acidic soil conditions of Cr contamination.

Impact of Low Lithium Concentrations on the Fatty Acids and Elemental Composition of Salvinia natans.

The photosynthetic pigments, protein, macro and microelements concentrations, and fatty acids composition of Salvinia natans, a free-floating aquatic plant, were analyzed after exposure to Hoagland nutrient solution containing 1, 3, and 5 mg/L Li. The Li content of Salvinia natans grew exponentially with the Li concentration in the Hoagland nutrient solution. The exposure to Li did not induce significant changes in Na, Mg, K, Cu, and Zn content but enhanced the Ba, Cr, Mn, Ni and Mo absorption in Salvinia natans. The most abundant fatty acids determined in oils extracted from Salvinia natans were C16:0, C18:3(n6), C18:2(n6), and C18:3(n3). The photosynthetic pigments did not change significantly after exposure to Li. In contrast, chlorophyll and protein content decreased, whilst monounsaturated and polyunsaturated fatty acids content increased after the exposure to 1 mg/L Li. The results indicated that Salvinia natans exposed to low Li concentrations may be a good source of minerals, omega 6 and omega 3.

Assessment of physicochemical properties of suspended sediment in Yangtze river estuary

ABSTRACT The physicochemical properties of suspended sediment affect the adsorption of heavy metals. Based on scanning electron microscopy-energy dispersive X-ray spectrometry and Image Pro Plus, we detected the physicochemical properties of suspended sediment in Yangtze Estuary. The following results were observed: (1) The graphical diameter (GD), roundness (RO) and fractal dimension (FD) of suspended sediment all presented normal distribution. According to Kolmogorov-Smirnov (K-S) test, the RO of suspended sediment of the ShiDongkou station at sewage outlet was 1.31, which was significantly higher than that of other points. (2) According to the K-S test, there was no significant difference in elements among various points in the Yangtze River Estuary. (3) Compared to the chemical properties of suspended sediment, its physical characteristics had a greater impact on heavy metal absorption. The physical characteristics had the least impact on the Cu adsorption, while the chemical properties had the least impact on the Cr absorption. This study deepens the understanding of suspended sediment in the Yangtze Estuary and provides comprehensive data for the numerical simulation of suspended sediment dynamics.