Uranium Biogeochemistry in the Rhizosphere of a Contaminated Wetland.

The objective of this study was to determine if U sediment concentrations in a U-contaminated wetland located within the Savannah River Site, South Carolina, were greater in the rhizosphere than in the nonrhizosphere. U concentrations were as much as 1100% greater in the rhizosphere than in the nonrhizosphere fractions; however and importantly, not all paired samples followed this trend. Iron (but not C, N, or S) concentrations were significantly enriched in the rhizosphere. XAS analyses showed that in both sediment fractions, U existed as UO22+ coordinated with iron(III)-oxides and organic matter. A key difference between the two sediment fractions was that a larger proportion of U was adsorbed to Fe(III)-oxides, not organic matter, in the rhizosphere, where significantly greater total Fe concentrations and greater proportions of ferrihydrite and goethite existed. Based on 16S rRNA analyses, most bacterial sequences in both paired samples were heterotrophs, and population differences were consistent with the generally more oxidizing conditions in the rhizosphere. Finally, U was very strongly bound to the whole (unfractionated) sediments, with an average desorption Kd value (Usediment/Uaqueous) of 3972 ± 1370 (mg-U/kg)/(mg-U/L). Together, these results indicate that the rhizosphere can greatly enrich U especially in wetland areas, where roots promote the formation of reactive Fe(III)-oxides.

Transformation of hazardous sacred incense sticks ash waste into less toxic product by sequential approach prior to their disposal into the water bodies.

Incense sticks ash is one of the most unexplored by-products generated at religious places and houses obtained after the combustion of incense sticks. Every year, tonnes of incense sticks ash is produced at religious places in India which are disposed of into the rivers and water bodies. The presence of heavy metals and high content of alkali metals challenges a potential threat to the living organism after the disposal in the river. The leaching of heavy metals and alkali metals may lead to water pollution. Besides this, incense sticks also have a high amount of calcium, silica, alumina, and ferrous along with traces of rutile and other oxides either in crystalline or amorphous phases. The incense sticks ash, heavy metals, and alkali metals can be extracted by water, mineral acids, and alkali. Ferrous can be extracted by magnetic separation, while calcium by HCl, alumina by sulfuric acid treatment, and silica by strong hydroxides like NaOH. The recovery of such elements by using acids and bases will eliminate their toxic heavy metals at the same time recovering major value-added minerals from it. Here, in the present research work, the effect on the elemental composition, morphology, crystallinity, and size of incense sticks ash particles was observed by extracting ferrous, followed by extraction of calcium by HCl and alumina by H2SO4 at 90-95 °C for 90 min. The final residue was treated with 4 M NaOH, in order to extract leachable silica at 90 °C for 90 min along with continuous stirring. The transformation of various minerals phases and microstructures of incense sticks ash (ISA) and other residues during ferrous, extraction, calcium, and alumina and silica extraction was studied using Fourier transform infrared (FTIR), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). DLS was used for analyzing the size during the experiments while FTIR helped in the confirmation of the formation of new products during the treatments. From the various instrumental analyses, it was found that the toxic metals present in the initial incense sticks ash got eliminated. Besides this, the major alkali metals, i.e., Ca and Mg, got reduced during these successive treatments. Initially, there were mainly irregular shaped, micron-sized particles that were dominant in the incense sticks ash particles. Besides this, there were plenty of carbon particles left unburned during combustion. In the final residue, nanosized flowers shaped along with cuboidal micron-sized particles were dominant. present in If, such sequential techniques will be applied by the industries based on recycling of incense sticks ash, then not only the solid waste pollution will be reduced but also numerous value-added minerals like ferrous, silica, alumina calcium oxides and carbonates can be recovered from such waste. The value-added minerals could act as an economical and sustainable source of adsorbent for wastewater treatment in future.

Method of reference samples preparation for X-ray fluorescence analysis.

The study focuses on the development of a new procedure for the preparation of reference samples with a given concentration for X-ray fluorescence analysis by adding certain volume of analyzed elements solutions with a known concentration to certified reference rock materials and further fusion with borate fluxes. The presented method of preparing emitters allows not only to obtain samples with the required concentrations for the elements to be determined, but also to preserve the influence that other elements have on the analytical signal. A set of 12 certified reference samples of rocks was used to construct calibration dependencies. The preparation of multicomponent modified reference samples (MRS) was carried out on the basis of certified reference materials (CRM) included in the set for constructing calibration curves. The concentration dependences on the analytical signal were established for the main oxides (SiO2, TiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O, P2O5) and minor elements (Cr, Cu, Ba, Ni, Sr, V, Zr, and Zn) using an X-ray fluorescence spectrometer with wavelength dispersion. With the help of modified reference samples, the calibration curves were expanded and supplemented both for major oxides (P2O5, MnO) and for minor elements (Zn, Sr). Also, in the course of the research, a comparison was made of the homogeneity of the emitters obtained according to the MRS preparation procedure presented in the work and reference samples (RS) made of CRM prepared according to the standard method for rocks, and the composition of inclusions on the surface of the fused disks was determined.

Interactions of airborne graphene oxides with the sexual reproduction of a model plant: When production impurities matter.

The increasing use of graphene-related materials (GRMs) in everyday-life products raises concerns for their possible release into the environment and consequent impact on organisms. GRMs have widely varying effects on plants and, according to recent evidences, graphene oxide (GO) has the potential to interfere with the sexual reproduction owing to its acidic properties and production residues. Here, stigmas of the model plant Cucurbita pepo (summer squash) were subjected to simulated dry depositions of GO and GO purified from production residues (PGO). Stigmas were then hand-pollinated and GRM deposition was checked by ESEM and confocal microscopy. Analysis of stigma integrity, pH homeostasis and pollen-stigma interactions did not reveal negative effects. Fruit and seed production were not affected, but GO depositions of 22.1 ± 7.2 ng mm-2 affected the normal development of seeds, decreasing seed dimensions, seed germination and germination speed. The elemental analysis revealed that GO has significant quantities of production residues, such as strong acids and oxidants, while PGO has only traces, which justifies the differences observed in the effects caused by the two materials. Our results show that GO depositions of up to 11.1 ± 3.6 ng mm-2, which fall within the variation range of total dry particulate matter depositions reported in the literature, are safe for reproduction of C. pepo. This is the first "safety" limit ever recorded for depositions of "out-of-the-box" GO concerning the reproduction of a seed plant. If confirmed for wind-pollinated species, it might be considered for policymaking of GRMs emissions in the air.

Characteristics and distribution of phosphorus in surface sediments of a shallow lake.

Phosphorus (P) in sediments plays an important role in shallow lake ecosystems and has a major effect on the lake environment. The mobility and bioavailability of P primarily depend on the contents of different P forms, which in turn depend on the sedimentary environment. Here, sediment samples from Baiyangdian (BYD) lake were collected and measured by the Standards, Measurements, and Testing procedure and Phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR) to characterize different P forms and their relationships with sediment physicochemical properties. The P content in the sediments varied in different areas and had characteristics indicative of exogenous river input. Inorganic P (334-916 mg/kg) was the dominant form of P. The 31P NMR results demonstrated that orthophosphate monoesters (16-110 mg/kg), which may be a source of P when redox conditions change, was the dominant form of organic P (20-305 mg/kg). The distribution of P forms in each region varied greatly because of the effects of anthropogenic activities, and the regions affected by exogenous river input had a higher content of P and a higher risk of P release. Principal component analysis indicated that P bound to Fe, Al, and Mn oxides and hydroxides (NaOH-P) and organic P were mainly derived from industrial and agricultural pollution, respectively. Redundancy analysis indicated that increases in pH lead to the release of NaOH-P. Organic matter plays an important role in the organic P biogeochemical cycle, as it acts as a sink and source of organic P.

Integration of chemical fractionation, Mössbauer spectrometry, and magnetic methods for identification of Fe phases bonding heavy metals in street dust.

Street dust is one of the most important carriers of heavy metals (HMs) originating from natural and anthropogenic sources. The main purpose of the work was to identify which of Fe-bearing phases bind HMs in street dust. Magnetic parameters of the Fe-bearing components, mainly magnetically strong iron oxides, are used to assess the level of HM pollution. Chemical sequential extraction combined with magnetic methods (magnetic susceptibility, magnetization, remanent magnetization) allowed determining the metal-bearing fractions and identifying the iron forms that are mostly associated with traffic-related HMs. The use of Mössbauer spectrometry (MS) supplemented by magnetic methods (thermomagnetic curves and psarameters of hysteresis loops) enabled precise identification and characterization of iron-containing minerals. The classification of HMs into five chemical fractions differing in mobility and bioaccessibility revealed that iron is most abundant (over 95%) in the residual fraction followed by the reducible fraction. HMs were present in reducible fraction in the following order: Pb>Zn>Mn>Cr>Ni>Fe>Cu, while they bound to the residual fraction in the following order: Fe>Ni>Cr>Mn>Pb>Cu>Zn. The signature of the anthropogenic origin of street dust is the presence of strongly nonstoichiometric and defected grains of magnetite and their porous surface. Magnetite also occurs as an admixture with maghemite, and with a significant proportion of hematite. A distinctive feature of street dust is the presence of metallic iron and iron carbides. Magnetic methods are efficient in the screening test to determine the level of HM pollution, while MS helps to identify the iron-bearing minerals through the detection of iron.

Dissipation pattern and conversion of pyrrolizidine alkaloids (PAs) and pyrrolizidine alkaloid N-oxides (PANOs) during tea manufacturing and brewing.

Pyrrolizidine alkaloids (PAs) and pyrrolizidine alkaloid N-oxides (PANOs) are toxic secondary metabolites in plants, and one kind of main exogenous pollutants of tea. Herein, the dissipation pattern and conversion behavior of PAs/PANOs were investigated during tea manufacturing and brewing using ultra high-performance liquid chromatography tandem mass spectrometry. Compared with PAs (processing factor (PF) = 0.73-1.15), PANOs had higher degradation rates (PF = 0.21-0.56) during tea manufacturing, and drying played the most important role in PANOs degradation. Moreover, PANOs were firstly discovered to be converted to corresponding PAs especially in the time-consuming (spreading of green tea manufacturing and withering of black tea manufacturing) and high-temperature tea processing (drying). Moreover, higher transfer rates of PANOs (≥75.84%) than that of PAs (≤56.53%) were observed during tea brewing. Due to higher toxicity of PAs than PANOs, these results are conducive to risk assessment and pollution control of PAs/PANOs in tea.

Magnetic particle monitoring on leaves in winter: a pilot study on a highly polluted location in the Po plain (Northern Italy).

Environmental monitoring in Northern Italy, one of the most polluted areas in Europe, is of paramount importance. Leaf monitoring throughout magnetic and scanning electron microscopy (SEM-EDS) analysis could be considered a good complementary analysis to sampling stations, but the lack of evergreen plants in the northern Italy towns may hinder magnetic leaf analysis in the winter season. Therefore, we tested three species of urban vegetation, which are evergreen and commonly found in urban environment, namely Hedera helix L., Parietaria officinalis L. and Rubus caesius L. Magnetic susceptibility, chosen as a simple parameter suitable for monitoring, was measured in seven stations, during the period 25 January 2019 to 8 March 2019 at a weekly step, in the cities of Torino and Parma in the same days. P. officinalis and R. caesius showed the best response, but also H. helix was suitable to detect highly polluted areas. In Torino, the magnetic susceptibility decreased in the last sampling, together with PM10, whereas in Parma it increased, likely for the beginning of the academic period in the University Campus. SEM-EDS analysis was done comparing leaves from the same plant sampled in February 2019, in highly polluted conditions, and in May 2020, after 2 months of very limited traffic, due to national lockdown. Silicate grains of natural minerals, sized between 10 and 20 µm, are present in both samples, whereas Fe oxides, about one micron size, possibly coming from car brake consumption, are prominent in the February 2019 sample. Magnetic susceptibility of leaves form the examined species looks promising to spot urban sites with high metal pollution.

A typical case study from smelter-contaminated soil: new insights into the environmental availability of heavy metals using an integrated mineralogy characterization.

Mineralogy was an important driver for the environmental release of heavy metals. Therefore, the present work was conducted by coupling mineral liberation analyzer (MLA) with complementary geochemical tests to evaluate the geochemical behaviors and their potential environmental risks of heavy metals in the smelter contaminated soil. MLA analysis showed that the soil contained 34.0% of quartz, 17.15% of biotite, 1.36% of metal sulfides, 19.48% of metal oxides, and 0.04% of gypsum. Moreover, As, Pb, and Zn were primarily hosted by arsenopyrite (29.29%), galena (88.41%), and limonite (24.15%), respectively. The integrated geochemical results indicated that among the studied metals, Cd, Cu, Mn, Pb, and Zn were found to be more bioavailable, bioaccessible, and mobile. Based on the combined mineralogical and geochemical results, the environmental release of smelter-driven elements such as Cd, Cu, Mn, Pb, and Zn were mainly controlled by the acidic dissolution of minerals with neutralizing potential, the reductive dissolution of Fe/Mn oxides, and the partial oxidation of metal sulfide minerals. The present study results have confirmed the great importance of mineralogy analysis and geochemical approaches to explain the contribution of smelting activities to soil pollution risks.

Longitudinal and Transverse Relaxivity Analysis of Native Ferritin and Magnetoferritin at 7 T MRI.

Magnetite mineralization in human tissue is associated with various pathological processes, especially neurodegenerative disorders. Ferritin's mineral core is believed to be a precursor of magnetite mineralization. Magnetoferritin (MF) was prepared with different iron loading factors (LFs) as a model system for pathological ferritin to analyze its MRI relaxivity properties compared to those of native ferritin (NF). The results revealed that MF differs statistically significantly from NF, with the same LF, for all studied relaxation parameters at 7 T: r1, r2, r2*, r2/r1, r2*/r1. Distinguishability of MF from NF may be useful in non-invasive MRI diagnosis of pathological processes associated with iron accumulation and magnetite mineralization (e.g., neurodegenerative disorders, cancer, and diseases of the heart, lung and liver). In addition, it was found that MF samples possess very strong correlation and MF's relaxivity is linearly dependent on the LF, and the transverse and longitudinal ratios r2/r1 and r2*/r1 possess complementary information. This is useful in eliminating false-positive hypointensive artefacts and diagnosis of the different stages of pathology. These findings could contribute to the exploitation of MRI techniques in the non-invasive diagnosis of iron-related pathological processes in human tissue.

Community structure of bacterioplankton and its relationship with environmental factors in the upper reaches of the Heihe River in Qinghai Plateau.

Planktonic microorganisms play a key role in the biogeochemical processes of the aquatic system, and they may be affected by many factors. High-throughput sequencing technology was used in this study to investigate and study the bacterioplankton community of water bodies in the upper reaches of the Heihe River Basin in Qinghai Plateau. Results showed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria are the predominant phyla in this river section, while the main genera are Thiomonas, Acidibacillus, Acidocella, Rhodanobacter, Acidithiobacter and Gallionella, which are autochthonous in the acid-mine drainage. Additionally, total nitrogen, total phosphorus, permanganate index and pH are significantly correlated with the bacterioplankton abundance and are the main limiting factors for the spatial distribution of the bacterioplankton. PICRUSt inferred that the mainstream microbial assemblages had a higher abundance of KOs belong to metabolism of terpenoids and polyketides, while the tributary had higher abundance of KOs belong to the immune system. The relationship between bacterioplankton community composition and environmental factors in the Heihe River basin was discussed for the first time in this study, which provides a theoretical basis for the healthy, orderly development of the water environment in the Heihe River Basin.

Spread of Jacobaea vulgaris and Occurrence of Pyrrolizidine Alkaloids in Regionally Produced Honeys from Northern Germany: Inter- and Intra-Site Variations and Risk Assessment for Special Consumer Groups.

Pyrrolizidine alkaloids (PA) and PA N-oxides (PANO) are secondary plant metabolites exhibiting genotoxic and carcinogenic properties. Apart from the roots and leaves, PA/PANO are particularly present in pollen and nectar. Therefore, the spread of Jacobaea vulgaris in certain regions of northern Germany has an impact on the safety of honey produced in that region. In this study, raw honey samples (n = 437) were collected from usually three individual beehives per site (n = 73) in the district of Ostholstein and analyzed for 25 PA/PANO. The results reveal mean levels of 8.4, 1.5, and 72.6 µg/kg and maximum levels of 111, 59.4, and 3313 µg/kg, depending on the season (summer 2015 and spring/summer 2016, respectively). As far as individual data are concerned, sites near areas with J. vulgaris growth did not necessarily result in high PA/PANO values. Furthermore, intra-site investigations revealed remarkable differences in PA/PANO levels of raw honey collected by different bee colonies at the same site. Consumption of these regionally produced honeys entails an increased exposure to PA/PANO, especially in children and high consumers. Margin of exposure values of <10,000 and an exceedance of the health-based guidance value highlight that regionally produced and marketed honey must be considered with care for a proper risk assessment and risk management.

A novel approach for fast and simple determination pyrrolizidine alkaloids in herbs by ultrasound-assisted dispersive solid phase extraction method coupled to liquid chromatography-tandem mass spectrometry.

Pyrrolizidine alkaloids (PAs) are secondary plant metabolites witch can contaminate food, especially herbs. Due to the fact that alkaloids have a strong adverse effect on human health, it is necessary to use sensitive and selective detection methods. In present study a modified method based on LC-MS/MS was developed and validated for the simultaneous determination of thirty pyrrolizidine alkaloids and their corresponding N-oxides (PANOs) in herbs samples. Sample extraction was based on ultrasound-assisted dispersive solid phase extraction and clean-up using graphene. Method validation showed that the proposed method hold good recoveries (61-128 %) for PAs/PANOs with RSD <15 %. Limits of quantification has been set at 1 µg kg-1 level for all targeted alkaloids. The optimized method yielded a small matrix effect (-20-20 %) for most PAs/PANOs. The uncertainty associated with the analytical method was not higher than 38 %. The method is operationally simple, time-saving, and can be applied to the analysis of real herb samples.

Distribution and Chemical Fate of [36Cl]Chlorine Dioxide Gas on Avocados, Eggs, Onions, and Sweet Potatoes.

Fate and distribution studies were conducted with [36Cl]-chlorine dioxide in avocados, eggs, onions, and sweet potatoes. Experiments utilized sealed, darkened chambers, 5 mg of 36ClO2 (g), and two-hour exposure periods. Total radioactive residues were quantitated in gas purges, tank rinses, reaction chambers, and on fractions specific to each food. Deposition of the radioactive residue was mostly a surface phenomenon; transfer of radioactivity into albumen occurred in egg, but radioactivity did not penetrate the onion tunic and only small amounts of activity were present in avocado flesh. Potato skin contained essentially all the potato radiochlorine. Regardless of the food product, nearly all radioactive residue was present in edible tissues as chloride ions; the chlorite ion was present only in egg-rinse water. Small amounts (10% or less) of radioactivity were present as chlorate ions, which would be a useful marker compound for chlorine dioxide sanitation.

Redox-dependent phosphorus burial and regeneration in an offshore sulfidic sediment core in North Yellow Sea, China.

Phosphorus (P) pollution can trigger severe marine eutrophication, which further leads to harmful algal blooms, and a deterioration of sea water quality. The P burial and regeneration in offshore sediments can directly affect the eutrophication levels of estuarine and coastal ecosystems. Although many researches on redox-dependent P burial and regeneration were studied, such process in the presence of silicate is still poorly understood, and the effects of pyrite formation on organic P (OP) burial and regeneration also remain unclear. In this study, a sulfidic sediment core was collected in the offshore of an estuary in the north Yellow Sea, China. Results indicated that indigenous biological input was found to be the primary source of organic matter in upper sediments. The regenerated P under reducing conditions was dominated by labile FeP and OP. The PO43- released from FeP and OP that could be captured by Al/Fe/Mn (oxyhydr) oxides in surface sediments and Ca minerals in deep sediments. CaP, AlP, unreactive Al/Fe-Si-P and some stable metal chelated OP were the main burial P fractions. Sulfate reduction and formation of insoluble metal sulfides including the pyrite promoted OP decomposition by anaerobic decomposition, removing metal ions from the "metal-OP" chelates and restoring the phosphatase activity.

Diagenesis of sulfur, iron and phosphorus in sediments of an urban bay impacted by multiple anthropogenic perturbations.

Solid-phase speciation and porewater chemistry measured by the diffusive gradients in thin films (DGT) technique were used to understand the diagenesis of sulfur (S), iron (Fe), and phosphorus (P) in sediments of Jiaozhou Bay (China), which has been impacted by multiple anthropogenic perturbations. Despite water eutrophication, sediments of the bay are low in organic carbon and sulfide, but high in unsulfidized Fe(II). Dissimilatory iron reduction (DIR) prevails in sediments of the bay, and there is no evidence for responses of S and Fe diagenesis to the water eutrophication, which is largely attributable to unique depositional and diagenetic regimes in association with multiple anthropogenic perturbations. Good coupling of porewater Fe2+ and P in the porewaters suggests that P mobilization is driven mainly by DIR. Low Fe2+/P ratios in porewaters imply that oxidative regeneration of Fe oxides within the upper sediments is incapable of efficiently scavenging upward diffusing P.

Agricultural lime disturbs natural strontium isotope variations: Implications for provenance and migration studies.

The application of 87Sr/86Sr in prehistoric mobility studies requires accurate strontium reference maps. These are often based from present-day surface waters. However, the use of agricultural lime in low to noncalcareous soils can substantially change the 87Sr/86Sr compositions of surface waters. Water unaffected by agriculture in western Denmark has an average 87Sr/86Sr ratio of 0.7124 as compared to an average of 0.7097 in water from nearby farmland. The 87Sr/86Sr ratio obtained from samples over 1.5 km along a stream, which originates in a forest and flows through lime-treated farmland, decreased from 0.7131 to 0.7099. Thus, 87Sr/86Sr-based mobility and provenance studies in regions with low to noncalcareous soils should be reassessed. For example, reinterpreting the iconic Bronze Age women at Egtved and Skrydstrup using values unaffected by agricultural lime indicates that it is most plausible that these individuals originated close to their burial sites and not far abroad as previously suggested.

Introducing the Alba® Primary Packaging Platform. Part 2: Inorganic Extractables Evaluation.

Sensitivity of drugs to one or more elements of the primary packaging is a serious concern for the pharmaceutical industry. Biologics in particular are highly sensitive, leading to a higher risk of incompatibility and stability test failure as worst-case scenario.This potential incompatibility-and the consequent formulation instability due to the interactions between the drug and the primary container surface-may have multiple causes: the intrinsic nature of the container surface, leachables coming from the materials used, substances coming from the production process, or silicone oil droplets or other particles.The Alba primary packaging platform was designed to have the same interface between the drug and the glass container surface on the different primary packaging containers in order to minimize the emergence of instabilities at later stages of formulation development. Alba containers are internally treated with an innovative cross-linked coating based on silicone oil lubricant, and the additional rubber components have been selected to minimize the possible differences between the container typologies.This paper shows in great detail the reduction of the inorganic extractables released and the comparability of the performances of the different containers obtained using Alba technology.The improvement has been demonstrated by stressing the containers with different extract solutions; Alba-coated containers show a strong reduction of inorganic extractables and of corrosion degree compared to spray-on siliconized and bulk products. The containers included in the Alba platform present comparable results, and this represents a strong advantage during the drug formulation development by facilitating the transition from one container to another.LAY ABSTRACT: The sensitivity of drugs to one or more elements of the primary packaging is a serious concern for the pharmaceutical industry. Biologics in particular are highly sensitive, leading to a higher risk of incompatibility and stability test failure worst-case scenario.This potential incompatibility-and the consequent formulation instability due to the interactions between the drug and the primary container surface-may have multiple causes: the intrinsic nature of the container surface, leachables coming from the materials used, substances coming from the production process, or silicone oil droplets or other particles.The Alba primary packaging platform was designed to minimize these problems associated with the interaction between the drug and its primary packaging. This paper shows in great detail and with robust data the inorganic extractables release reduction and the delamination risk mitigation obtained using the Alba technology.

Effects of Acid Mine Drainage on Calcareous Soil Characteristics and Lolium perenne L. Germination.

Acid mine drainage (AMD) is a serious environmental problem resulting from extensive sulfide mining activities. There is a lack of more comprehensive and detailed studies on the effect of AMD on calcareous soil characteristics and seed germination. In this study, five calcareous soil samples, collected from Xiaoyi, Taigu, Xiangning, Hejin, and Xixian counties in Shanxi Province, China, were used to investigate the effects of acid AMD on soil characteristics and Lolium perenne L. germination through laboratory culture experiments. The results showed that the increase in the total soil calcium oxide and magnesium oxide (CaO + MgO) contents led to a rise in the amount of Fe2+ in AMD converted into Fe3+, and that major ions (H⁺, Fe, SO42-) in AMD were trapped in the soil. The total Cao + MgO contents in the soil collected from Hejin and Taigu counties were 14.23% and 6.42%, the pH of AMD-polluted soil decreased to 7.24 and 3.10, and 98.7% and 54.0% of the Fe2+, 99.9% and 58.6% of the total Fe, and 76.0% and 26.4% of the SO42-, respectively, were trapped in the soil when the AMD volume to soil mass ratio was 10 mL/g. The results for the soil from Taigu County showed that when the soil had an AMD volume to soil mass ratio of 10 mL/g, the organic matter, available phosphorus (available P), available potassium (available K), Cr, and Cd contents in soil decreased by 16.2%, 63.0%, 97.1%, 7.8%, and 73.2%, respectively; the total phosphorus (total P) and total potassium (total K) did not significantly change; whereas the available nitrogen (available N) and total nitrogen (total N) increased to 16.1 times and 1.76 times, respectively. Compared to the initial soil collected from Taigu County, the Lolium perenne L. germination rate decreased by 81.1%, and the cumulative amount of Cr in the Lolium perenne L. increased by 7.24 times in the AMD-polluted soil when the AMD volume to soil mass ratio was 6 mL/g. The soil conditions could not support Lolium perenne L. germination when the AMD volume to soil mass ratio was 10 mL/g. The outcomes of this study could have important implication in understanding the hydrological/geochemical-behaviour of major ions of AMD in calcareous soil. The findings also have great significance in predicting plant growth behavior in AMD-polluted calcareous soil.

Toxicity assessment of metal oxide nano-pollutants on tomato (Solanum lycopersicon): A study on growth dynamics and plant cell death.

The present study for the first time demonstrated the interactions of metal oxide (MO) nano-pollutants (CuO and Al2O3-NPs) with tissues and cellular DNA of tomato plants grown in soil sand: silt: clay (667:190:143) and Hoagland-hydroponic system and assessed the hazardous effects of NPs on cell physiology and biochemistry. Results of SEM equipped with EDX revealed attachment of variably shaped CuO-NPs (18 nm) and Al2O3-NPs (21 nm) on roots, and internalization followed by translocation in plants by ICP-MS and TEM. Significant variations in foliage surface area, chlorophyll, proteins, LPO, and antioxidant enzymes were recorded. Roots and shoots accumulated 225.8 ±â€¯8.9 and 70.5 ±â€¯4 µgAl g-1 DW, whereas Cu accumulation was 341.6 ±â€¯14.3 (roots) and 146.9 ±â€¯8.1 µg g-1 DW (shoots) which was significant (p ≤ 0.0005) as compared to control. The total soluble protein content in roots, shoots, and leaves collected from Al2O3-NPs treated plants increased by 120, 80, and 132%, respectively while in CuO-NPs treatments, the increase was 68 (roots), 36 (shoots), and 86% (leaves) over control. The level of antioxidant enzymes in plant tissues was significantly (p ≤ 0.05) higher at 2000 µg ml-1 of MONPs over control. A dose-dependent increase in reactive oxygen species (ROS), biphasic change of lower and higher fluorescence in mitochondria due to dissipation of mitochondrial membrane potential (ΔΨm) and membrane defects using propidium iodide were observed. Comparatively, CuO-NPs induced higher toxicity than Al2O3-NPs. Perceptible changes in proteins (amide-I & II), cellulose, glucose, galactose and other carbohydrates were observed under FT-IR. The binding studies with TmDNA showed fluorescence quenching of EtBr-TmDNA and acridine orange-TmDNA complex only by CuO-NPs with -ΔG and +ΔH and +ΔS values. However, Al2O3-NPs induced lesser change in TmDNA conformation. Conclusively, the results are novel in better demonstrating the mechanistic basis of nano-phyto-toxicity and are important which could be used to develop strategies for safe disposal of Al2O3-NPs and CuO-NPs.