Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%-98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.

Insights into Heavy Metals Leakage in Chelator-Induced Phytoextraction of Pb- and Tl-Contaminated Soil

Chelators including DTPA (diethylene triamine pentaacetic acid) and oxalic acid were selected for inducing phytoextraction of heavy metals (HMs) from Pb-, Tl-, and Pb-Tl- contaminated soil, in which heavy metals leakage was highly remarkable. Results showed that compared with the control group without chelating agent under planting conditions, the extraction efficiency (i.e., uptake coefficient) of Pb, Tl increased by 86%, 43% from Pb-Tl- contaminated soil in the presence of oxalic acid, and there was no significant change in heavy metal leakage under rainfall conditions. It was the best phytoremediation scheme in this work. Under rainfall conditions, the HMs concentration in the leachate showed a linear decreasing trend. Acid rain promoted the leakage of heavy metals, and the average leached amount of Tl increased by 1.47 times under acid rain conditions. However, for Pb, DTPA was the main influencing factor, followed by acid rain.

Recovery of Li(Ni0.33Mn0.33Co0.33)O₂ from Lithium-Ion Battery Cathodes: Aspects of Degradation

Nickel⁻manganese⁻cobalt oxides, with LiNi_0.33Mn_0.33Co_0.33O₂ (NMC) as the most prominent compound, are state-of-the-art cathode materials for lithium-ion batteries in electric vehicles. The growing market for electro mobility has led to a growing global demand for Li, Co, Ni, and Mn, making spent lithium-ion batteries a valuable secondary resource. Going forward, energy- and resource-inefficient pyrometallurgical and hydrometallurgical recycling strategies must be avoided. We presented an approach to recover NMC particles from spent lithium-ion battery cathodes while preserving their chemical and morphological properties, with a minimal use of chemicals. The key task was the separation of the cathode coating layer consisting of NMC, an organic binder, and carbon black, from the Al substrate foil. This can be performed in water under strong agitation to support the slow detachment process. However, the contact of the NMC cathode with water leads to a release of Li⁺ ions and a fast increase in the pH. Unwanted side reactions may occur as the Al substrate foil starts to dissolve and Al(OH)₃ precipitates on the NMC. These side reactions are avoided using pH-adjusted solutions with sufficiently high buffer capacities to separate the coating layer from the Al substrate, without precipitations and without degradation of the NMC particles.

Irrigation-induced salinity affects olive oil quality and health-promoting properties

BACKGROUND

Olive oil, a functional food, is increasingly produced from trees irrigated with water containing high concentrations of salts. We studied the effects of irrigation-induced salinity on quality and health-related compounds in olive oil. Trees (cv Barnea) were grown in lysimeters with continuous control and monitoring of root-zone salinity. Salinity in the root zone was altered by changing irrigation solution salinity or by changing the extent of leaching. Extracted oil was analyzed for quality parameters including free fatty acid content, polyphenol, tocopherol, sterol and carotenoid levels, fatty acid (FA) profile, and antioxidative capacity.

RESULTS

While not all parameters changed, fruit water percentage and fruit oil content significantly decreased with increasing exposure to salt. As salinity increased, there was a desirable rise in measured polyphenol and tocopherol levels and a contrasting undesirable reduction in a number of important compounds, including 16:1 and 18:3 FA.

CONCLUSION

The possible negative effects on olive oil quality due to FA-related parameters should concern producers dependent on, or considering, irrigation with high-salinity water sources. A number of important quality parameters were differentially influenced by the method of inducing the root zone salinity, suggesting that additional environmental variables leading to oxidative responses were affected by the treatments. © 2018 Society of Chemical Industry.

Relationship between Dislocation Density and Antibacterial Activity of Cryo-Rolled and Cold-Rolled Copper

In the present work, cold rolling and cryo-rolling were performed on 99% commercially pure copper substrates. Both cold and cryo-rolling processes caused severe plastic deformation that led to an increase in dislocation density by 14× and 28× respectively, as compared to the pristine material. Increases in average tensile strengths, by 75% (488 MPa) and 150% (698 MPa), were observed in the two rolled materials as the result of the enhancement in dislocation density. In addition to strength, enhanced antibacterial property of cryo-rolled copper was observed in comparison to cold rolled and pristine copper. Initial adhesion and subsequent proliferation of bio-film forming Gram-positive bacteria Staphylococcus aureus was reduced by 66% and 100% respectively for cryo-rolled copper. Approximately 55% protein leakage, as well as ethidium bromide (EtBr) uptake, were observed confirming rupture of cell membrane of S. aureus. Inductively coupled plasma-mass spectroscopy reveals higher leaching of elemental copper in nutrient broth media from the cryo-rolled copper. Detailed investigations showed that increased dislocation led to leaching of copper ions that caused damage to the bacterial cell wall and consequently killing of bacterial cells. Cryo-rolling enhanced both strength, as well as antibacterial activity, due to the presence of dislocations.

Sulfonated Poly(ether ether ketone) Doped with Ammonium Ionic Liquids and Nano-Silicon Dioxide for Polymer Electrolyte Membranes

Nano-silicon dioxide (SiO₂) was incorporated into the matrix of sulfonated poly(ether ether ketone) (SPEEK)/ammonium ionic liquid (AIL) membranes by solution casting, with the aim of reducing ionic liquid leaching and any consequent decrease in proton conductivity. Fourier transform infrared (FTIR) spectra results indicate incorporation of the SPEEK matrix with AIL and nano-SiO₂. Scanning electron microscopy (SEM) and X–ray diffraction (XRD) images revealed that incorporation of nano-SiO₂ make the ternary composite membranes more flexible. The maximum ion exchange capacity (IEC) value was 3.25 meq/g, and the net structure formed by the nano-SiO₂ not only retarded AIL leaching, but also increased the proton conductivity of the composite membranes. AIL leaching from the membranes was between 20% and 30%, which was lower than that of the SPEEK/AIL membrane. The maximum proton conductivity for the SPEEK/AIL/SiO₂ membranes reached 10.73 mS/cm at 393 K.

Bimetallic Fe-Cu Nanocomposites on Sand Particles for the Inactivation of Clinical Isolates and Point-of-Use Water Filtration

Bimetallic Fe-Cu nanocomposites with an average size of 26.4 ± 4.7 nm were prepared on the surface of fine sand particles by modified coprecipitation and the chemical reduction method and were applied as an in vitro broad spectrum antimicrobial agent and recyclable hand-held water filter to sieve bacteria and metals. The size of the nanocomposites could be further reduced to 11.8 ± 1.6 nm when prepared after ball milling the sand particles, keeping the antimicrobial property intact. The results showed that the chemical nature and morphology of the nanocomposites had a great effect on both Gram-positive and Gram-negative bacteria with a minimum inhibitory concentration of 10.6 μg/mL and 13.8 μg/mL of copper, whereas the minimum bactericidal concentration was found to be 15.9 μg/mL and 21.2 μg/mL. The nanocomposites exhibited antimicrobial activity against multidrug-resistant bacteria as well as fungus isolated from different human biological samples like blood, urine, pus, and wound swabs. The nanocomposites were also capable of filtering a wide range bacteria like Acinetobacter baumannii, Escherichia coli, Salmonella typhi, Bacteroides fragilis, Salmonella paratyphi, Shigella dysenteriae, and Enterococcus faecalis, which are predominantly responsible for waterborne diseases. Further, the nanocomposites were used for the removal of hazardous metals like nickel, zinc, and lead. Leaching of copper and iron from the nanocomposites was within the permissible limit as per Bureau of Indian Standards (BIS) for Drinking Water (IS-10500-2012, second revision) as well as the International Standards for Drinking Water.

[Degradation of α-HCH in Soil Washing Solutions with nZVI and CaO2]

Nano zerovalent iron (nZVI) and CaO₂ were used to construct a heterogeneous Fenton-like system to degrade α-hexachlorocyclohexane (α-HCH) in soil solution, and the degradation efficiency and mechanism were investigated. The results showed that nZVI/CaO₂ can degrade α-HCH in an extensive pH range. When the dosage of nZVI and CaO₂ was 1 g·L^-1 and pH was 5, the degradation rate of α-HCH reached 93.23%. The degradation process of nZVI, CaO₂, and nZVI/CaO₂ treatments accorded with the first-order reaction kinetics model. The reaction rate constant of nZVI/CaO₂ was greater than the sum of individual treatments, showing that nZVI/CaO₂ has a synergistic effect on the degradation of α-HCH. Through quenching free radical experiments, the contribution rate of superoxide radicals was shown to be greater than that of hydroxyl radicals. Intermediates, including trichlorobenzene and chlorobenzene, were detected. The content of trichlorobenzene showed a sharp increase initially, and then decreased quickly. The chlorobenzene content was low and showed little change. The α-HCH in the soil washing solution was first reduced to trichlorobenzene, which was further reduced to chlorobenzene or mineralized into CO₂ and water directly.

Bioavailability and leaching of Cd and Pb from contaminated soil amended with different sizes of biochar

Biochars have been successfully used to reduce bioavailability and leaching of heavy metals in contaminated soils. The efficiency of biochar to immobilize heavy metals can be increased by reducing the particle size, which can increase the surface area and the cation exchange capacity (CEC). In this study, the empty fruit bunch biochar (EFBB) of oil palm was separated into two particle sizes, namely, fine (F-EFBB < 50 µm) and coarse (C-EFBB > 2 mm), to treat the contaminated soil with Cd and Pb. Results revealed that the addition of C-EFBB and F-EFBB increased the pH, electrical conductivity and CEC of the contaminated soil. The amounts of synthetic rainwater extractable and leachable Cd and Pb significantly decreased with the EFBB application. The lowest extractable and leachable Cd and Pb were observed from 1% F-EFBB-treated soil. The amount of extractable and leachable Cd and Pb decreased with increasing incubation times and leaching cycles. The application of F-EFBB to Cd and Pb-contaminated soil can immobilize the heavy metals more than that of C-EFBB. Therefore, the EFBB can be recommended for the remediation of heavy metal-contaminated soils, and a finer particle size can be applied at a lower application rate than the coarser biochar to achieve these goals.

Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy

Epoxies are often exposed to water due to rain and humid air environments. Epoxy yellows during its service time under these conditions, even when protected from UV radiation. The material’s color is not regained upon redrying, indicating irreversible aging mechanisms. Understanding what causes a discoloration is of importance for applications where the visual aspect of the material is significant. In this work, irreversible aging mechanisms and the cause of yellowing were identified. Experiments were performed using a combination of FT-NIR, ATR-FT-IR, EDX, HR-ICP-MS, pH measurements, optical microscopy, SEM, and DMTA. Such extensive material characterization and structured logic of investigation, provided the necessary evidence to investigate the long-term changes. No chain scission (hydrolysis or oxidation-induced) was present in the studied common DGEBA/HDDGE/IPDA/POPA epoxy, whilst it was found that thermo-oxidation and leaching occurred. Thermo-oxidation involved evolution of carbonyl groups in the polymeric carbon–carbon backbone, via nucleophilic radical attack and minor crosslinking of the HDDGE segments. Four probable reactive sites were identified, and respective reactions were proposed. Compounds involved in leaching were identified to be epichlorohydrin and inorganic impurities but were found to be unrelated to yellowing. Carbonyl formation in the epoxy backbone due to thermo-oxidation was the cause for the yellowing of the material.

[Characteristics of soil nitrate accumulation and leaching under different long-term nitrogen application rates in winter wheat and summer maize rotation system.]

Winter wheat and summer maize were the main crops in the North China Plain. While intensive farming system could generally achieve high yield, the perennial large amounts of nitrogen (N) fertilization application cause environmental problems including NO₃^--N accumulation and leaching at deep soil layer. Here, the effects of different N application rates on soil NO₃^--N accumulation and leaching in winter wheat-summer maize cropping system were investigated from 2010 to 2016 at Qingyuan County, Hebei Province, China. There were five treatments with N application rates at 0 (N₀), 100 (N₁₀₀), 180 (N₁₈₀), 255 (N₂₅₅) and 330 (N₃₃₀) kg·hm^-2. Results showed that crop yield and soil N status significantly varied among treatments for both wheat and maize after each harvest, respectively. Soil NO₃^--N were accumulated during winter wheat growing season and leached to deeper soil during summer maize growing season. Moreover, the soil NO₃^--N accumulation amount in the 90 to 180 cm soil profile decreased with the decreases of N inputs (N₃₃₀ > N₂₅₅ > N₁₈₀ > N₁₀₀ > N₀). Soil NO₃^--N could be leached to 990 cm soil depth. There were six NO₃^--N accumulation peaks in the soil profile, with the peaks presenting at deeper soil profile with higher N fertilization rate. The deepest peak appeared at 840 cm soil depth with the N application rate of 330 kg·hm^-2. From the distribution of NO₃^--N accumulation in the soil profile, only around 10% of total NO₃^--N was accumulated between 0-90 cm soil depth, while the rest accumulated below 90 cm, which could not be largely absorbed by plants. Therefore, NO₃^--N leaching during summer maize growing season was serious and it was greater with higher N fertilization rate which might lead to increased risk of underground water contamination. In terms of balanced crop yield and soil NO₃^--N accumulation, the rate of 180 kg·hm^-2 would be the optimum one in areas with similar cultivation and environmental conditions to the present study.

Scientific Opinion about the Guidance of the Chemical Regulation Directorate (UK) on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessments

The EFSA Panel on Plant Protection Products and their Residues reviewed the guidance on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessment. The inclusion of aged sorption is a higher tier in the groundwater leaching assessment. The Panel based its review on a test with three substances taken from a data set provided by the European Crop Protection Association. Particular points of attention were the quality of the data provided, the proposed fitting procedure of aged sorption experiments and the proposed method for combining results obtained from aged sorption studies and lower-tier studies on degradation and adsorption. Aged sorption was a relevant process in all cases studied. The test revealed that the guidance could generally be well applied and resulted in robust and plausible results. The Panel considers the guidance suitable for use in the groundwater leaching assessment after the recommendations in this Scientific Opinion have been implemented, with the exception of the use of field data to derive aged sorption parameters. The Panel noted that the draft guidance could only be used by experienced users because there is no software tool that fully supports the work flow in the guidance document. It is therefore recommended that a user-friendly software tool be developed. Aged sorption lowered the predicted concentration in groundwater. However, because aged sorption experiments may be conducted in different soils than lower-tier degradation and adsorption experiments, it cannot be guaranteed that the higher tier predicts lower concentrations than the lower tier, while lower tiers should be more conservative than higher tiers. To mitigate this problem, the Panel recommends using all available higher- and lower-tier data in the leaching assessment. The Panel further recommends that aged sorption parameters for metabolites be derived only from metabolite-dosed studies. The formation fraction can be derived from parent-dosed degradation studies, provided that the parent and metabolite are fitted with the best-fit model, which is the double first-order in parallel model in the case of aged sorption.

How Green is Your Plasticizer?

Plasticizers are additives that are used to impart flexibility to polymer blends and improve their processability. Plasticizers are typically not covalently bound to the polymers, allowing them to leach out over time, which results in human exposure and environmental contamination. Phthalates, in particular, have been the subject of increasing concern due to their established ubiquity in the environment and their suspected negative health effects, including endocrine disrupting and anti-androgenic effects. As there is mounting pressure to find safe replacement compounds, this review addresses the design and experimental elements that should be considered in order for a new or existing plasticizer to be considered green. Specifically, a multi-disciplinary and holistic approach should be taken which includes toxicity testing (both in vitro and in vivo), biodegradation testing (with attention to metabolites), as well as leaching studies. Special consideration should also be given to the design stages of producing a new molecule and the synthetic and scale-up processes should also be optimized. Only by taking a multi-faceted approach can a plasticizer be considered truly green.

Impact assessment of fly ash on ground water quality: An experimental study using batch leaching tests

The fly ash, generated at the coal-based thermal power plant, is always a cause of concern to environmentalists owing to its adverse impact on air, water and land. There exists a high environmental risk when it is disposed to the environment. Thus, two different type of fly ash samples (FA-1 and FA-2) have been considered in this study to examine the leaching potential of the elements magnesium, aluminium, silicon, calcium, titanium, vanadium, chromium, manganese, iron, nickel, cobalt, copper, zinc, arsenic, selenium, strontium, cadmium, barium and lead for different types of leachant. Toxicity characteristics leaching procedure and ASTM tests have been performed in the laboratory to simulate different natural leaching scenarios. Characterisation of samples have been done through X-ray diffraction and field emission gun scanning electron microscope. The effect of different liquid to solid ratios (i.e. 5, 10, 20 and 50) on the mobilisation of elements has been analysed. The results indicated that the maximum leaching of all elements occurred at a liquid to solid ratio of 5 except for arsenic, barium and silicon. The groundwater analysis has also been done to understand the actual effects of leachate. The elements presenting the highest leachability in the two fly ash samples under all tested conditions were magnesium, aluminium, silicon and calcium. It has been observed that calcium exhibits greater leaching effects than all other constituents. The study presented here has been found very useful for assessing contamination levels in groundwater owing to leaching effects of fly ash under different scenarios, which can be helpful to prevent spreading of the contaminants by efficient management of fly ash.

Magnesium Potassium Phosphate Compound for Immobilization of Radioactive Waste Containing Actinide and Rare Earth Elements

The problem of effective immobilization of liquid radioactive waste (LRW) is key to the successful development of nuclear energy. The possibility of using the magnesium potassium phosphate (MKP) compound for LRW immobilization on the example of nitric acid solutions containing actinides and rare earth elements (REE), including high level waste (HLW) surrogate solution, is considered in the research work. Under the study of phase composition and structure of the MKP compounds that is obtained by the XRD and SEM methods, it was established that the compounds are composed of crystalline phases&mdash;analogues of natural phosphate minerals (struvite, metaankoleite). The hydrolytic stability of the compounds was determined according to the semi-dynamic test GOST R 52126-2003. Low leaching rates of radionuclides from the compound are established, including a differential leaching rate of ²³⁹Pu and ²⁴¹Am&mdash;3.5 &times; 10^&minus;7 and 5.3 &times; 10^&minus;7 g/(cm²∙day). As a result of the research work, it was concluded that the MKP compound is promising for LRW immobilization and can become an alternative material combining the advantages of easy implementation of the technology, like cementation and the high physical and chemical stability corresponding to a glass-like compound.

[Effects of combined application of chemical fertilizer and organic manure on wheat yield and leaching of residual nitrate-N in dryland soil]

The effects of optimum nitrogen (N) fertilization rate with and without adding manure on wheat yield and leaching of residual nitrate-N in soil profile were examined in Weibei dryland, Shaanxi with a field experiment combined different N fertilization rates (0, 75, 150, 225, 300 kg N·hm^-2) and organic manure (0 and 30 t·hm^-2). The results showed that, compared to chemical N fertilizer, combined application of inorganic fertilizer and organic manure increased winter wheat yield by 14.7% when N fertilization rate was reduced by 27.1%. The highest yield was obtained when 150 kg·hm^-2 of N rate was combined with the manure (N₁₅₀+M). The combination of N fertilizer and manure promoted N uptake of wheat grain and increased N use efficiency by 20.2%. The highest N use efficiency was recorded in the N₁₅₀+M treatment. In addition, the lea-ching of residual nitrate-N during the wheat growing season and the leaching of nitrate-N during summer fallow were decreased. When N application rate was lower than 115 kg·hm^-2, N fertilizer combined with organic manure reduced the amount of nitrate-N leaching in summer fallow. We recommend the combined application of organic manure with about 150 kg·hm^-2 of N fertilizers in Weibei dryland to guarantee high winter wheat yield, N use efficiency, and reduce excessive residue of fertilizer N in the soil.

Leaching and sorption of neonicotinoid insecticides and fungicides from seed coatings

Seed coatings are a treatment used on a variety of crops to improve production and offer protection against pests and fungal outbreaks. The leaching of the active ingredients associated with the seed coatings and the sorption to soil was evaluated under laboratory conditions using commercially available corn and soybean seeds to study the fate and transport of these pesticides under controlled conditions. The active ingredients (AI) included one neonicotinoid insecticide (thiamethoxam) and five fungicides (azoxystrobin, fludioxonil, metalaxyl, sedaxane thiabendazole). An aqueous leaching experiment was conducted with treated corn and soybean seeds. Leaching potential was a function of solubility and seed type. The leaching of fludioxonil, was dependent on seed type with a shorter time to equilibrium on the corn compared to the soybean seeds. Sorption experiments with the treated seeds and a solution of the AIs were conducted using three different soil types. Sorption behavior was a function of soil organic matter as well as seed type. For most AIs, a negative relationship was observed between the aqueous concentration and the log Koc. Sorption to all soils tested was limited for the hydrophilic pesticides thiamethoxam and metalaxyl. However, partitioning for the more hydrophobic fungicides was dependent on both seed type and soil properties. The mobility of fludioxonil in the sorption experiment varied by seed type indicating that the adjuvants associated with the seed coating could potentially play a role in the environmental fate of fludioxonil. This is the first study to assess, under laboratory conditions, the fate of pesticides associated with seed coatings using commercially available treated seeds. This information can be used to understand how alterations in agricultural practices (e.g., increasing use of seed treatments) can impact the exposure (concentration and duration) and potential effects of these chemicals to aquatic and terrestrial organisms.

Sustainable recovery of valuable metals from spent lithium-ion batteries using DL-malic acid: Leaching and kinetics aspect

An eco-friendly and benign process has been investigated for the dissolution of Li, Co, Ni, and Mn from the cathode materials of spent LiNi_1/3Co_1/3Mn_1/3O₂ batteries, using DL-malic acid as the leaching agent in this study. The leaching efficiencies of Li, Co, Ni, and Mn can reach about 98.9%, 94.3%, 95.1%, and 96.4%, respectively, under the leaching conditions of DL-malic acid concentration of 1.2 M, hydrogen peroxide content of 1.5 vol.%, solid-to-liquid ratio of 40 g l^-1, leaching temperature of 80°C, and leaching time of 30 min. In addition, the leaching kinetic was investigated based on the shrinking model and the results reveal that the leaching reaction is controlled by chemical reactions within 10 min with activation energies (Ea) of 21.3 kJ·mol^-1, 30.4 kJ·mol^-1, 27.9 kJ·mol^-1, and 26.2 kJ·mol^-1 for Li, Co, Ni, and Mn, respectively. Diffusion process becomes the controlled step with a prolonged leaching time from 15 to 30 min, and the activation energies (Ea) are 20.2 kJ·mol^-1, 28.9 kJ·mol^-1, 26.3 kJ·mol^-1, and 25.0 kJ·mol^-1 for Li, Co, Ni, and Mn, respectively. This hydrometallurgical route was found to be effective and environmentally friendly for leaching metals from spent lithium batteries.

Modifying the Formulation of Abamectin To Promote Its Efficacy on Southern Root-Knot Nematode (Meloidogyne incognita) under Blending-of-Soil and Root-Irrigation Conditions

The southern root-knot nematode (RKN), Meloidogyne incognita, is the most disastrous and prevalent nematode threat to the production of crops, especially vegetables. In the current study, second-stage juveniles (J2) of M. incognita were collected from five regions near Tai'an, China. The toxicity of abamectin to these J2 had insignificant differences, with LC₅₀ values of approximately 2 mg/L. Two pesticide application approaches (i.e., blending-of-soil and root-irrigation) were adopted in pot experiments; blending-of-soil was more beneficial for promoting the efficacy of abamectin on the RKN of tomatoes. Abamectin microcapsule suspension exhibited superiority to emulsifiable concentrate (EC) at dosages of 5 and 10 mg active ingredient per plant integrating efficacy, root length, plant height, the fresh weight of roots, and the fresh weight of stems + leaves. Adsorption, leaching, and mobility of abamectin in the soil also verified bioactivity test results. Modifying the formulation of abamectin can promote its efficacy on RKN under different application approaches.

Durable Self-Cleaning Coatings for Architectural Surfaces by Incorporation of TiO₂ Nano-Particles into Hydroxyapatite Films

To prevent soiling of marble exposed outdoors, the use of TiO₂ nano-particles has been proposed in the literature by two main routes, both raising durability issues: (i) direct application to marble surface, with the risk of particle leaching by rainfall; (ii) particle incorporation into inorganic or organic coatings, with the risk of organic coating degradation catalyzed by TiO₂ photoactivity. Here, we investigated the combination of nano-TiO₂ and hydroxyapatite (HAP), previously developed for marble protection against dissolution in rain and mechanical consolidation. HAP-TiO₂ combination was investigated by two routes: (i) sequential application of HAP followed by nano-TiO₂ (“H+T”); (ii) simultaneous application by introducing nano-TiO₂ into the phosphate solution used to form HAP (“HT”). The self-cleaning ability was evaluated before and after prolonged exposure to simulated rain. “H+T” and “HT” coatings exhibited much better resistance to nano-TiO₂ leaching by rain, compared to TiO₂ alone. In “H+T” samples, TiO₂ nano-particles adhere better to HAP (having flower-like morphology and high specific surface area) than to marble. In “HT” samples, thanks to chemical bonds between nano-TiO₂ and HAP, the particles are firmly incorporated in the HAP coating, which protects them from leaching by rain, without diminishing their photoactivity and without being degraded by them.

Halloysite Tubes as Nanocontainers for Herbicide and Its Controlled Release in Biodegradable Poly(vinyl alcohol)/Starch Film

Commercial herbicide atrazine (AT) was first loaded into the lumen of halloysite nanotubes (HNTs) in the amount of 9 wt %, and then the AT-loaded HNTs (HNTs-AT) were further incorporated into poly(vinyl alcohol)/starch composites (PVA/ST, with the weight ratio of 80/20) to construct a dual drug delivery system. AT loaded in nanotubes displayed much slower release from PVA/ST film in water than free AT; for example, the total release amount of AT from PVA/ST film with loaded AT was only 61% after 96 h, while this value reached 97% in PVA/ST film with free AT. The release behavior of AT from PVA/ST film with HNTs-AT was first dominated by the mechanism of matrix erosion and then by the mechanism of Fickian diffusion. In addition, combining HNTs and PVA/ST blends together in the controlled release of herbicide also reduced its leaching through the soil layer, which would be useful for diminishing the environmental pollution caused by pesticide.

Study of the factors influencing the metals solubilisation from a mixture of waste batteries by response surface methodology

This paper presents an innovative process for the recovery of valuable metals from a mixture of spent batteries. Different types of batteries, including alkaline, zinc-carbon (Zn-C), nickel cadmium (Ni-Cd), nickel metal hydride (Ni-MH), lithium ion (Li-ion) and lithium metallic (Li-M) batteries, were mixed according to the proportion of the Canadian sales of batteries. A Box-Behnken design was applied to find the optimum leaching conditions allowing a maximum of valuable metal removals from a mixture of spent batteries in the presence of an inorganic acid and a reducing agent. The results highlighted the positive effect of sodium metabisulfite on the performance of metals removal, especially for Mn. The solid/liquid ratio and the concentration of H₂SO₄ were the main factors affecting the leaching behavior of valuable metals (Zn, Mn, Cd, Ni) present in spent batteries. Finally, the optimum leaching conditions were found as follows: one leaching step, solid/liquid ratio = 10.9%, [H₂SO₄] = 1.34 M, sodium metabisulfite (Na₂S₂O₅) = 0.45 g/g of battery powder and retention time = 45 min. Under such conditions, the removal yields achieved were 94% for Mn, 81% for Cd, 99% for Zn, 96% for Co and 68% for Ni.

Novel Metal-Organic Framework (MOF) Based Composite Material for the Sequestration of U(VI) and Th(IV) Metal Ions from Aqueous Environment

The combination of magnetic nanoparticles and metal-organic frameworks (MOFs) has demonstrated their prospective for pollutant sequestration. In this work, a magnetic metal-organic framework nanocomposite (Fe₃O₄@AMCA-MIL53(Al) was prepared and used for the removal of U(VI) and Th(IV) metal ions from aqueous environment. Fe₃O₄@AMCA-MIL53(Al) nanocomposite was characterized by TGA, FTIR, SEM-EDX, XRD, HRTEM, BET, VSM (vibrating sample magnetometry), and XPS analyses. A batch technique was applied for the removal of the aforesaid metal ions using Fe₃O₄@AMCA-MIL53(Al) at different operating parameters. The isotherm and kinetic data were accurately described by the Langmuir and pseudo-second-order models. The adsorption capacity was calculated to be 227.3 and 285.7 mg/g for U(VI) and Th(IV), respectively, by fitting the equilibrium data to the Langmuir model. The kinetic studies demonstrated that the equilibrium time was 90 min for each metal ion. Various thermodynamic parameters were evaluated which indicated the endothermic and spontaneous nature of adsorption. The collected outcomes showed that Fe₃O₄@AMCA-MIL53(Al) was a good material for the exclusion of these metal ions from aqueous medium. The adsorbed metals were easily recovered by desorption in 0.01 M HCl. The excellent adsorption capacity and the response to the magnetic field made this novel material an auspicious candidate for environmental remediation technologies.

Vertical Leaching of Allelochemicals Affecting Their Bioactivity and the Microbial Community of Soil

Leaching of allelochemicals in soil is one of the fundamental processes that determines allelopathic activities but is often overlooked. In the present study, the vertical leaching of seven putative allelochemicals as well as one pesticide and one herbicide was investigated using polyvinyl chloride columns combined with a bioassay approach. The results indicated that the leachability of pretilachlor and imidacloprid were the best (Lf > 0.8), followed by vanillin and coumarin (Lf > 0.6). The leachability of daidzein, menthol, and m-tyrosine were medium (0.3 < Lf < 0.6). The lowest leachability has been observed on p-coumaric and p-hydroxybenzoic acids (Lf < 0.3). The chemicals were classified into three clusters according to the phospholipid fatty acid profile (i.e., vanillin in one cluster, coumarin and menthol in the second cluster, and the rest in the third cluster). Bioactivities of the chemicals changed dramatically. Germination of lettuce seeds was suppressed by imidacloprid and pretilachlor, and the suppression was concentration-dependent. The bioactivity of most of the allelochemicals were progressively decreased with the downward movement of chemicals. The results indicated that leaching mediated the microbial communities and the interactions of chemical-microorganism and modified the bioavailability of allelochemicals in soil.

[Effects of Organic Carbon Content on the Residue and Migration of Polycyclic Aromatic Hydrocarbons in Soil Profiles]

The effects of total organic carbon content (TOC) on the migration of polycyclic aromatic hydrocarbons (PAHs) in the soil were investigated. This study analyzed the vertical properties of the concentrations and distributions of PAHs and TOC at various soil profiles from functionally different environmental regions including nature reserves, ploughs, orchards, farmlands, metropolitan areas, and industrial parks. The vertical migration properties of PAHs in soils were examined by conducting leaching experiments in soil columns. The concentrations of PAHs varied from region to region and showed strong, positive correlations with TOC in the same region. Furthermore, based on the leaching experiments, the transport abilities of PAHs were significantly influenced by TOC, although they could all be transported to the deep layers by TOC in soil columns. The downward migration of PAHs decreased with the increase in TOC and vice versa. The properties of the composition and structure of PAHs also had an obvious influence on their residues and migration in soil profiles at the same TOC conditions. In addition, the transport of PAHs was related to the amount of leaching water, the leaching time, and the additional PAHs.