Recycling steel slag as fertiliser proxy in agriculture is good circular economy but disrupts plant microbial symbioses in the soil.

Modern agriculture depends on synthetic fertilisers to ensure food security but their manufacture and use accounts for ~5 % of the global greenhouse gas emissions. Achieving climate change targets therefore requires alternatives, that while maintaining crop productivity, reduce emissions across the lifecycle of fertiliser utilisation. Steel slag, a nutrient-rich by-product of steel manufacture, offers a viable alternative. Being substantially cheaper than fertilisers, it is economically attractive for farmers, particularly in low-middle income countries of the Global South. However, slag application in agriculture poses risk of pollutant transfer to the human food chain and disruption of key plant-microbe symbioses like the arbuscular mycorrhizal fungi (AMF). Here, using barley as a model crop, we tested the suitability of slag as a fertiliser proxy. Mycorrhizal and non-mycorrhizal barley were grown in soils ameliorated with slag in concentrations of 0, 2, 5 and 10 t ha-1. We analysed slag-mycorrhiza interaction and their combined effects on crop yield and risks to human nourishment. Slag increased grain yield by respective 32 and 21 % in mycorrhizal and non-mycorrhizal barley. Grain concentration of metal pollutants in mycorrhizal and non-mycorrhizal barley fertilised with slag were within the WHO recommended limits. But slag reduced mycorrhizal colonisation in barley roots and extraradical hyphal spread in the soil. The consequent decline in symbiont function lowered AMF-mediated plant nutrient uptake and increased mineral losses in leachates. AMF are keystone species of the soil microbiome. Loss of AMF function presents long-term ecological consequences for agriculture and necessitates a careful evaluation of slag application to soil.

Investigation of the emission and leaching behavior of characteristic heavy metals in sintered bricks prepared from oil-based drill cutting residues.

Oil-based drill cutting residues (OBDCR) are hazardous waste generated by the thermal desorption of oil-based drill cuttings. Recently, the utilization of OBDCR as building materials has attracted extensive attention, but the environmental risks during preparation and long-term usage remained unclear. In this study, OBDCR with a 40 % (wt./wt.) mixing ratio was used to prepare sintered bricks, and the emission and leaching behaviors of Ba, Mn, Zn, Ni, Cr, and Pb were investigated. The results indicated that the addition of OBDCR in bricks showed insignificant increase in the emission of Ba, Mn, Zn, Ni, and Cr, whereas the emission of Pb slight decreased from 10.5 to 8.6 µg/m3. The volatilization rates of these heavy metals were considerably low, with Ni showed the highest volatilization rate of only 1.45 % in OBDCR bricks. Moreover, the leaching behavior of Ba, Mn, Zn, Ni, Cr, and Pb in bricks were studied. The results indicated that surface wash-off was the main controlling leaching mechanism of Ba and Cr, whereas the leaching of Mn, Zn, Ni, and Pb was controlled by diffusion. The Elovich and second-order kinetic equation were identified as the leaching models for Mn, Zn, Pb, and Ni. The life-time leaching predictions of OBDCR bricks indicated that the leaching of Ni and Mn after 10 and 20 years of leaching were 0.1529, 0.257, 0.1530, and 0.274 mg/L, respectively, exceeding the relevant standards. Therefore, the leaching risks of Ni and Mn should be emphasized when using OBDCR bricks with a 40 % OBDCR mixing ratio.

Leaching and geochemical modeling of asbestos-cement waste and mine asbestos.

Asbestos-Containing Materials (ACMs) were widely used in the construction sector but, due to their harmful health effects, many countries have banned their use. ACMs are classified as hazardous and, in contact with water, produce potentially harmful leachates. The objective of this work was to determine the leaching behavior of 20 elements from two asbestos-cement materials and mine asbestos samples across the entire pH range and varying liquid-to-solid ratios (column tests). The pH-dependence tests showed consistent leaching patterns across the three materials. Geochemical speciation model (LeachXS) predictions were successful in most cases of the batch experiments and were improved by adjusting iron oxides concentration for some elements. Model predictions were successful for fewer elements in the column experiments. Depending on the pH, element release was controlled by respective solid phase dissolution, sorption onto iron oxides and substitution in ettringite. Some leaching concentrations exceeded the EU limits for granular non-hazardous waste landfills. Considering the strongly alkaline nature of monolithic asbestos-cement waste undergoing carbonation, we propose all three materials to be disposed of in non-hazardous waste landfills, according to EU legislation. A case study concluded that geochemical modeling of ACMs leaching is a useful tool in estimating element release under various environmental conditions.

Chromium cycle in Red Soil Critical Zone constrained by chromium isotopes.

Chromium (Cr) isotopic system has been used to trace Cr pollution in the modern surface environment and redox change in the paleoenvironment. However, the transformation mechanism of Cr in soil and the accompanied Cr isotopic fractionation have not been clarified clearly. Here we measured Cr isotopic compositions (δ53Cr) of two paddy field profiles from the Red Soil Critical Zone Observatory in South China. The δ53Cr values of the young paddy fields, which have been cultivated for about 20 years, range from -0.34 ‰ to -0.22 ‰. The old paddy fields have been cultivated for >100 years and have more positive Cr isotopic compositions than the young paddy fields, from -0.20 ‰ to -0.06 ‰. The results of three-step leaching experiments show that iron and manganese oxides are enriched in heavy Cr isotopes, while organic matters have much lower Cr isotopic compositions, likely resulting from back reduction of Cr(VI). Our results suggest that Cr isotopic fractionation during the oxidation of Cr(III) is not the only reason for the depletion of heavy isotopes during oxidative weathering, and the partial back-reduction of generated Cr(VI) by organic matter plays an important role in Cr isotopic fractionation during weathering. Comparison between the old and young paddy fields further indicates that cultivation can significantly affect the Cr cycle in red soils. Paddy fields could be a potential sink for the Cr(VI) contaminant, and soils with a long history of cultivation would be more susceptible.

Detecting Bisphenol A Leaching from Four Different Commercially Available Clear Aligner Sheets: An Ex Vivo Study.

AIM: The study aimed to detect and quantify bisphenol A (BPA) leaching in salivary samples of patients undergoing clear aligner therapy (CAT) using four different commercially available sheets. MATERIALS AND METHODOLOGY: Four different commercially available clear aligners namely Monoflex®, Erkodur®, Leone®, and Duran® were delivered to 20 volunteers who were grouped into (n = 5) group A, group B, group C, and group D, respectively. Salivary samples were collected immediately before aligner insertion (day 0) and at day 1, day 5, and day 7 after aligner wear. Comparisons were made between baseline (day 0) BPA levels and subsequent time points to assess the leaching kinetics of BPA from the clear aligners by liquid chromatography/mass spectrometry. RESULTS: The overall mean leaching of 0.74 ± 0.33 ppm at T1 (day 1) was observed among four groups of aligners, while no leaching was detected at T5 (day 5) and T7 (day 7). Among the four groups, the highest leaching of 1.24 ppm was detected from Duran at T1 followed by Monoflex (0.76 ppm), Erkodur (0.56 ppm), and Leone (0.43 ppm). CONCLUSION: It can be concluded that leaching only during the first 24 hours of aligner usage was dominant compared to other time intervals. Among the aligners considered, Duran was found to be the least safe followed by Monoflex, Erkodur, and Leone. CLINICAL SIGNIFICANCE: Since aligners are expanding in usage it is important to consider their biocompatibility. Even though the results indicate minimal leaching of BPA, it has a cumulative negative effect when patients undergo prolonged treatment with aligners. How to cite this article: Azhagudurai N, Rajendran R, Aishwarya K, et al. Detecting Bisphenol A Leaching from Four Different Commercially Available Clear Aligner Sheets: An Ex Vivo Study. J Contemp Dent Pract 2024;25(6):535-539.

Experimental design and multiple response optimization of batch leaching tests of volcanic ashes.

Volcanic eruptions can release large amounts of tephra, lava, and gases, drawing attention due to their magnitude, energy, and impact on life and the environment. Among the most documented and sometimes dramatic effects of volcanic ashes are those linked to the input of diverse elements in the environment, which are released as a consequence of ash weathering. Laboratory studies have been conducted to investigate and predict the environmental input of chemical elements from volcanic ashes. This research paper describes the optimization of batch leaching tests used to investigate the release of ions from ashes collected in the Andes Cordillera after the eruption of the Puyehue volcano in 2011. Chemometric multivariate strategies were employed to evaluate the influence of variables affecting the leaching of volcanic ash. The effects of the main variables, namely contact time, the acidity of the leaching agent, the solid/liquid ratio, the particle size, and the stirring speed, were studied in leaching tests. To determine the optimal conditions for selected metal determinations, we employ Darringer's desirability function, which allows for the simultaneous optimization of the selected responses (element concentrations during the leaching process). Multielemental analysis (Na, Mg, Al, Si, P, Cl, K, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Cd, Hg, Tl, and Pb) was quantified by ICP-MS (inductively coupled plasma-mass spectrometry) following adequate dilution of test leaching. These results established the optimal experimental conditions for leaching volcanic ash. The most significant variables were the solid/liquid ratio and the stirring speed, resulting in two groups of elements with an adequate global desirability function (D) value.

Water dispersible carbon nanomaterials reduced N, P, and K leaching potential in sandy soils: A column leaching study.

Carbon nanomaterials (CNMs) - amendments with carbon in nanoscale form -could potentially enhance fertilizer delivery efficiency in agriculture, but their interaction with soil properties and nutrient co-mobility, especially in coarse-textured soils, remain poorly understood. We conducted a column leaching study in repacked soil columns to compare the co-leaching of novel water-dispersible CNMs and soil nutrients across two levels of CNMs applications (200 & 400 mg kg-1), two fertilization rates (low:80 mg kg-1 of N, P and K and high: 200 mg N kg-1, 100 mg P kg-1, 200 mg K kg-1, applied as ammonium nitrate, potassium phosphate, and potassium nitrate) and two soils (Spodosol with pH = 5.1, Alfisol with pH = 6.5). We imposed 12 leaching events to each column, with each leaching event adding water equivalent to the soil-pore volume (250 mL), resulting in cumulative leaching of 3000 mL of water through each column. CNMs applications reduced cumulative leaching losses of NO3-N (Spodosol: 8-12 %, Alfisol: 9-19 %), NH4-N (Spodosol: 2-14 %, Alfisol: 9-14 %), P (Spodosol: 23-27 %, Alfisol: 23-36 %) and K (Spodosol: 17-23 %, Alfisol: 24-26 %) compared to fertilized columns without CNMs. CNMs increased soil pH by up to 0.3 units (Spodosol) or 0.5 units (Alfisol), while lowering electrical conductivity by 15-20 % at the high fertilization rate in both soils. Columns with water-dispersible CNMs accumulated 25-30 % more total C in the base sections of the Alfisol compared to the Spodosol, indicating faster downward movement through the soil profile. Overall, we demonstrated that CNMs have the potential to reduce nutrient leaching in coarse-textured soils, which could be particularly beneficial in high-input intensive agricultural systems.

Cement and zeolite stabilization/solidification of heavy metal-contaminated sediments: 841-Day leaching characteristics, mechanisms, and microstructure.

The long-term effectiveness of stabilized/solidified sediments (S/S sediments) is increasingly attracting attention. This study investigated the long-term leaching characteristics and mechanisms of S/S sediment through an 841-day tank leaching test, considering the influence of cement content, curing time, and zeolite. The results indicate significant correlations among pH, heavy metals, TN, NH3-N, and COD. The specimens with 6 % cement cured for 30 days (C6(30)) demonstrated considerable heavy metal stabilization, with stabilization rates for Cr, Ni, Cu, Zn, As, and Pb reaching 99.81 %, 99.06 %, 98.93 %, 99.61 %, 97.58 %, and 99.97 %, respectively. Compared to C6(30), partial replacement of cement with 10 % zeolite (C5 + Z0.5(30)) not only more effectively stabilized heavy metals except As, but also reduced the release of COD and NH3-N by 4.23 % and 10.04 %, respectively. However, there was a risk of TN, NH3-N, and COD exceeding permissible limits during long-term leaching. Microscopic analysis results suggested that hydration products and low porosity contributed to stabilization of heavy metals. Leaching mechanisms was revealed that surface wash-off controls the leaching of Cr and Pb, while diffusion controls the leaching of Ni, Cu, Zn, As, COD, TN, and NH3-N. Considering stabilization performance, cost and carbon emissions, C5 + Z0.5(30) is an effective strategy for reducing long-term environmental risks of S/S sediments.

Thiosulfate leaching in carbonaceous gold-bearing ores in Ethiopia.

One of the main unit operations in metallurgical processing plant designs is gold leaching. The traditional cyanidation process was chosen and is currently in widespread use. However, the mining sector is looking for lixiviants other than cyanide. Cyanide's effects on the environment have made it difficult for humans and other biotic creatures to survive. There is now research to discover a substitute for this cyanide. It is currently argued that thiosulfate is a preferable substitute for cyanide. The effectiveness of thiosulfate as a leaching agent in carbonaceous gold-bearing ores in Ethiopia is discussed in this paper compared to cyanide. The study has looked into the advantages of employing thiosulfate over cyanide from a technical, and economic standpoint. The leaching effects of both lixiviants on carbonaceous gold-bearing ores extracted from MIDROC Legadembi Open Pit mine in Southern Ethiopia, Oromia region, were examined in a laboratory experiment. After 48 h of leaching, it was discovered that thiosulfate has a better and quicker recovery of 91.54% over 61.70% of cyanide recovery. Tables and graphs are used to demonstrate thiosulfate's technical advantage over cyanide. As a result, this paper provides evidence regarding the Legadembi gold mine in Ethiopia's amenability to thiosulfate leaching on carbonaceous gold-bearing ores. A further research perspective is also sought for thiosulfate leaching in other refractory ores.

Zwitterionic MOF-embedded alginate beads with polydopamine surface functionalization for efficient doxycycline removal: Optimization and mechanistic study.

The adsorptive removal of amphoteric antibiotics like doxycycline (DOX) is a difficult task because of the electrostatic repulsion between these amphoteric molecules and adsorbents. For this purpose, a zwitter adsorbent was fabricated by incorporating zwitter ZIF-67/MIL-88A binary MOF into the matrix of alginate (Alg); in addition, the surface of the beads was modified by polydopamine (PDA). The batch experiments implied the super-high adsorption efficacy of ZIF-67/MIL-88A@Alg@PDA toward DOX attained 384.61 ±â€¯5.08 mg/g at a neutral pH medium, 25 °C, and using 0.02 g. The isotherm analysis implied the physisorption of DOX onto ZIF-67/MIL-88A@Alg@PDA, while the kinetic analysis denoted the chemisorption of DOX. The results of XPS, Zeta potential, and Lab experiments identified the types of physical and chemical interactions between ZIF-67/MIL-88A@Alg@PDA and DOX. The durability of the ZIF-67/MIL-88A@Alg@PDA beads was inspected by the recycling test, clarifying that the DOX adsorption aptitude declined by 12.22 mg/g. In addition, the measured leaching concentrations of cobalt and iron from leaching test were 0.008 and 0.098 mg/L. The ionic strength of ZIF-67/MIL-88A@Alg@PDA, implying an enhancement in the DOX removal (%) from 83.51 to 93.50 % by raising the NaCl concentration from 0.2 to 1.0 mol/L. Therefore, our study could provide a simple procedure to overcome the electrostatic repulsion that retard the adsorption process of the amphoteric drugs onto charged adsorbents with positive or negative charges. Additionally, this procedure could also generate an electrostatic interaction between the zwitter adsorbents and the amphoteric drugs at specific pH media when they are in a zwitterionic nature.

The impact of managed aquifer recharge on the fate and transport of pesticides in agricultural soils.

Groundwater aquifers worldwide experience unsustainable depletion, compounded by population growth, economic development, and climate forcing. Managed aquifer recharge provides one tool to alleviate flood risk and replenish groundwater. However, concerns grow that intentional flooding of farmland for groundwater recharge, a practice known as Ag-MAR, may increase the leaching of pesticides and other chemicals into groundwater. This study employs a physically based unsaturated flow model to determine the fate and transport of residues of four pesticide in three vadose zone profiles characterized by differing fractions of sand (41 %, 61 %, and 84 %) in California's Central Valley. Here, we show that the complex heterogeneity of alternating coarse and fine-grain hydrogeologic units controls the transit times of pesticides and their adsorption and degradation rates. Unsaturated zones that contain a higher fraction of sand are more prone to support preferential flow, higher recharge rates (+8 %), and faster (42 %) water flow and pesticide transport, more flooding-induced pesticide leaching (about 22 %), as well as more salt leaching correlating with increased risks of groundwater contamination. Interestingly, considering preferential flow predicted higher degradation and retention rates despite shorter travel times, attributed to the trapping of pesticides in immobile zones where they degrade more effectively. The findings underscore the importance of considering soil texture and structure in Ag-MAR practices to minimize environmental risks while enhancing groundwater recharge. The study also highlights that selecting less mobile pesticides can reduce leaching risks in sandy areas.

Synergy between Fenton reagent and solid waste-based solidifying agents during the solidification/stabilization of lead(II) and arsenic(III) contaminated soils.

Due to the different physicochemical properties of lead (Pb) and arsenic (As), coupled remediation processes of contaminated soils containing Pb and As have always been a technical challenge. In the present study, a novel solidifying agent (BER) was synthesized using alkaline oxygen furnace slag (BOFS), modified electrolytic manganese residue (EMR) and red mud (RM). The solidifying agent was synergistically used with Fenton reagent for solidifying/stabilizing Pb- and As-contaminated soils. The experimental results indicated that the low stability of Ca-As(III) complexes, which serve as the primary fixation mechanism for As in BER-solidified soil, led to inadequate stabilization of As by BER. As a result, the leaching concentration of As in the BER-solidified soil reached 2.61 mg/L. The incorporation of Fenton reagent had minimal effect on the strength of the solidified soil and Pb stabilization, but it substantially improved As stabilization. The immobilization efficiency of the BER-Fenton for lead and arsenic reached 99% and 98%, respectively. The strength of solidified/stabilized soil using BER-Fenton was close to that of cement-based solidified/stabilized soil. Microscopic analysis showed that the incorporation of Fenton reagent increased the content of goethite and ettringite, which effectively filled the soil pores and enhanced the adsorption of Pb and As. The use of BER and Fenton reagent increased the content of As(V) to 88%, which promoted the complexation between As and Fe(III)/Mn(IV). This study provides a novel method for efficient remediation of heavy metal-contaminated sites, as well as a useful reference for ensuring the safe reuse of hazardous wastes.

Cocrystal engineering for sustained release of dicamba: Mitigating secondary drift and reducing leaching.

The off-target effects of herbicides present significant challenges in agricultural practices, posing serious threats to both ecological systems and human health. Dicamba, one of the most widely used herbicides, is particularly problematic due to its high volatility and water solubility, which can lead to rapid environmental dispersal, non-target toxicity, and groundwater contamination. To mitigate these issues, we synthesized a novel cocrystal of dicamba and phenazine (DCB-PHE cocrystal) through a combination of theoretical prediction and mechanochemical screening. The DCB-PHE cocrystal was characterized using single-crystal and powder X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and thermal analysis. Compared to pure dicamba, the DCB-PHE cocrystal exhibited a substantial reduction in volatility by 59 % and a decrease in equilibrium solubility by up to 5.4 times across various temperatures (15 °C, 25 °C, 35 °C). Additionally, the dissolution rates were significantly lowered by over 94 %. Leaching experiments demonstrated that the DCB-PHE cocrystal reduced total leachate by 4.9 % and delayed percolation. In greenhouse trials, the DCB-PHE cocrystal caused less damage to exposed soy plants and enhanced herbicidal activity against target weeds, with fresh weight reduction of chicory and ryegrass by 32 % and 28 %, respectively, at the highest dosage. Furthermore, safety assays confirmed that the DCB-PHE cocrystal's safety profile was comparable to that of dicamba in terms of its impact on wheat, and it did not exhibit increased genotoxicity to broad beans. These findings suggest that the DCB-PHE cocrystal is a promising candidate for reducing the environmental impacts of dicamba while maintaining its herbicidal efficacy.

Coupling Electrochemical Leaching with Solvent Extraction for Recycling Spent Lithium-Ion Batteries.

We propose coupling electrochemical leaching with solvent extraction to separate and recover Li and Co from spent lithium-ion batteries (LIBs). Electrochemical leaching occurs in the aqueous electrolyte for converting solid LiCoO2 into soluble Li+ and Co2+, in which electrons act as reductants to reduce Co(III) to Co(II). Simultaneously, solvent extraction occurs at the interface of aqueous and organic phases to separate Co2+ and Li+. By capturing and utilizing the protons from P507, leaching yields for both Co and Li exceed ∼7 times than acid leaching without solvent extraction. The extraction efficiency of Co2+ reaches 86% at 60 °C, 3.5 V, while simultaneously retaining the majority of Li+ in the H2SO4 solution. The total leaching amount was improved because the organic phase provides protons to help the leaching of Co2+, and the continuous extraction process of Co(II) maintains the low Co2+ concentration in the aqueous solution. The synergistic interaction between electrochemical leaching and solvent extraction processes significantly reduces the consumption of chemicals, enhances the utilization efficiency of protons, and simplifies the recovery process. The leaching kinetics of Li and Co both conforms well to the residue layer diffusion control model and the activation energy (Ea) values of the leaching for Li and Co are 4.03 and 7.80 kJ/mol, respectively. Lastly, the economic and environmental assessment of this process also demonstrates the advantages of this method in reducing inputs, lowering environmental pollution, and enhancing economic benefits.

Analyzing the impacts of climate change on ecosystem services provided by apple orchards in Southeast France using a process-based model.

We know that fruit production, especially in the Mediterranean, will need to adapt to climate change to ensure the sustainability of fruit tree-based agroecosystems. However, there is a lack of evidence on the long-term effects of this change on sustainability indicators. To fill this gap, we used a fruit tree model, QualiTree, to analyze the impacts ofclimate change on the ecosystem services provided by apple orchards in south-eastern France. To do this, a blooming model was parameterized to simulate blooming date on the basis of climate data, and QualiTree was supplemented with a model of nitrogen processes in the tree and a soil module describing resource input (irrigation, mineral and organic fertilization), transfer in the soil (water and nitrogen) and metabolic transformation-immobilization (mineralization, (de)nitrification). This type of extension makes it possible to simulate a wide array of ecosystem services, including C sequestration, nitrate leaching and nitrous oxide emissions. The model was compared with data from an apple orchard in southeastern France. The predicted daily mean and variability over time of fruit growth, composition and soil water content were consistent with observed data. QualiTree was then used to assess the potential impacts of climate change on the ecosystem services supplied by apple orchards. For this purpose, weather variables from 2020 to 2100 were generated for three contrasted greenhouse gas emission scenarios, and simulations were performed under two irrigation schemes (no restriction and restricted use of water). Model outputs indicated that, on average, marketable apple yields would increase until 2050 and then subsequently decrease. The fruit refractometric index, an indicator of fruit quality, was projected to sharply decrease with the intensity of climate change. Ecosystem services such as C sequestration by the orchard will decrease with climate change severity, mainly due to a higher mineralization of soil humus, whereas N2O emissions will increase with larger denitrification rates. Soil water availability, fertility, drainage and leaching were predicted to depend more on the irrigation strategy than on climate change severity. The new functions performed in QualiTree broadened its predictive capabilities and allowed for a better understanding of ecosystem service delivery in fruit orchards under varying climate conditions.

Effects of Paddy Rain-Flood Storage on Rice Growth Physiological Indices and Nitrogen Leaching under Organic Planting in Erhai Lake Basin.

In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments were set up: conventional flooding irrigation (CK) and controlled irrigation (C), with three replicates for each treatment. In 2023, aiming to enhance the utilization rate of rainwater resources and reduce the direct discharge of dry-farming tailwater from upstream into Erhai Lake. The paddy field was used as an ecological storage basin, and the water storage depth of the paddy field was increased compared to the depth of 2022. Combined with the deep storage of rainwater, the dry-farming tailwater was recharged into the paddy field to reduce the drainage. In 2023, two water treatments, flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD) were set up, and each treatment was set up with three replicates. The growth and physiological index of rice at various stages were observed. Nitrogen leaching of paddy field in surface water, soil water, and groundwater under different water treatments after tillering fertilizer were observed. The research results show that the combined application of organic and inorganic fertilizers under organic planting can provide more reasonable nutrient supply for rice, promote dry matter accumulation and other indices, and also reduce the concentration of NH4+-N in surface water. Compared with CK, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of C are increased by 4.8%, 4.1%, 20.9%, and 9.7%, respectively. Compared with CKCD, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of CCD are increased by 6.5%, 3.8%, 19.6%, and 21.9%, respectively. The yield in 2023 is 19% higher than that in 2022. Treatment C can increase the growth indicators and reduce the net photosynthetic rate to a certain extent, while CCD rain-flood storage can alleviate the inhibition of low irrigation lower limit on the net photosynthetic rate of rice. Both C and CCD can reduce nitrogen loss and irrigation amount in paddy fields. CCD can reduce the tailwater in the Gusheng area of the Erhai Lake Basin to Erhai Lake, and also can make full use of N, P, and other nutrients in the tailwater to promote the formation and development of rice. In conclusion, the paddy field rain-flood storage methodology in the Erhai Lake Basin can promote various growth and physiological indicators of rice, improve water resource utilization efficiency, reduce direct discharge of tailwater into Erhai Lake, and decrease the risk of agricultural non-point source pollution.

Reducing Phosphorus Loss in Short-Cycle Horticultural Production Using Activated Aluminum-Amended Substrates and Modified Fertigation Practices.

To support growth, short-cycle horticultural crops require readily available nutrients. However, this often leads to nutrient leaching. Implementing best management practices in production decisions like incorporating fertilizer retaining amendments to substrates or modifying fertilization programs can mitigate nutrient losses to the environment and associated costs. This study examined using an activated aluminum (AA) material as a substrate amendment to retain phosphorus (P) within containers while also assessing methods to reduce P fertilization in Tagetes production over a six-week production cycle. A commercial peat moss substrate (PL) pre-loaded with nutrients was amended with AA, enabling comparisons between substrates with and without AA. Enhanced fertilizer practices involved supplementing the initial nutrients by applying a weekly fertigation solution including nitrogen and potassium over the six weeks, but P for either 0, 2, 4, or 6 weeks. The incorporation of AA significantly reduced P leaching losses by 89.5-97.7%, compared to the PL substrates receiving P the entire six weeks. Regardless of substrate or fertilizer management, all Tagetes had equivalent sizes (growth index) and aboveground biomass. The results indicate that amending substrates with AA and/or reducing additional P inputs are effective strategies to minimize P leaching without compromising Tagetes quality.

Kinetics and Mechanism of SiO2 Extraction from Acid-Leached Coal Gangue Residue by Alkaline Hydrothermal Treatment.

Acid-leached gangue residue is produced after the gangue extraction of metal ions; the main component is silicon, which can be used to extract silica. To ascertain the kinetics and mechanism of silica extraction from acid-leached coal gangue residue, this study explored the effects of the NaOH concentration, solid-to-liquid ratio, reaction temperature, and reaction time on the extraction process. The optimized conditions, determined through this investigation, involved a NaOH concentration of 4 mol/L, a reaction time of 4 h, a solid-to-liquid ratio of 1:4, and a reaction temperature of 180 °C, yielding a SiO2 extraction ratio of 90.16%. Additionally, the leaching kinetics of silica in a NaOH solution were examined using three kinetic equations from the "unreacted shrinking core model". The results revealed that the control type of the leaching process was the "mixing control", and the apparent activation energy was determined to be 52.36 kJ/mol.

Bisphenol-A Leaching from Polycarbonate 5-Gallon Water Bottles in the UAE: A Comprehensive Study.

Bisphenol A (BPA) is widely used around the world in the production of Polycarbonate (PC) plastics. Notably, the ubiquitous 5-gallon water bottles in the UAE are primarily made of PC plastic, making them a significant concern as bottled water is the region's main supply of drinking water. These bottles undergo temperature variations during storage and transportation, potentially leading to harmful BPA (Bisphenol A) leaching. This study analyzed 40 PC 5-gallon water bottles from two local brands A and B, with 20 bottles per brand, under two conditions: room temperature and outdoor sunlight exposure for a month. BPA levels were assessed at 0, 15, and 30 days, following ethical approval. Liquid-liquid extraction and ELISA assays were conducted, with comprehensive kit validation. The results revealed a significant increase in BPA concentration over time, particularly in bottles exposed to elevated temperatures (Day 30 outdoor-stored samples exhibited the highest concentration at 9.05 ± 2.30 µg/L). Brand B consistently exhibited higher BPA concentrations across different samples and environments. This study emphasizes the link between BPA content and storage time, highlighting the need for preventive measures to reduce BPA exposure. Individuals should be aware of potential health risks associated with prolonged storage in plastic containers and consider safer alternatives.

Simple preparation of nitenpyram-intercalated clay nanosheets with reduced leaching risk and improved safety to insect pollinators.

Neonicotinoids, highly toxic to insects, are among the world's most used insecticides. However, their harmful effects on pollinators like honeybees and potential to contaminate water bodies have drawn significant criticism. Herein, a nanopesticide, NTP@LDH, was developed by intercalating the model neonicotinoid insecticide nitenpyram (NTP) within layered double hydroxide (LDH) materials using a simple one-pot method. The NTP@LDH showed a nano-sized sheet structure, with an average particle size of 206.2 nm and a loading capacity of 14.6 %. The release rate of NTP@LDH under acidic conditions was higher than that under alkaline or neutral conditions. The photodegradation capacity and insecticidal activity of NTP were unaffected by intercalation in LDH. Importantly, NTP@LDH could significantly enhance the foliar adhesive properties of NTP, retard its leaching through the soil, and improve its safety for honeybees. Moreover, LDH was safe for crops and can improve their growth. This work provides a promising strategy with a simple procedure that could reduce leaching risks of neonicotinoids while concurrently enhancing their safety to pollinating creatures.