Leachate Analysis Research Articles

Ecotoxicological Impact of Cigarette Butts on Coastal Ecosystems: The Case of Marbella Beach, Chile

Cigarette butts (CBs) are a major source of persistent pollution in coastal ecosystems, introducing harmful chemicals and microplastics into the environment. This study assesses the ecotoxicological impact of CB leachates on Marbella Beach, Chile, by analyzing the metal contamination and its phytotoxic effects on Lactuca sativa and Lolium perenne. Three scenarios were evaluated: CBs alone, CBs mixed with sand, and sand alone. Leachate analysis revealed significant concentrations of iron and zinc, with higher toxicity observed in scenarios involving CBs. Ecotoxicological assays demonstrated that cigarette butt leachates severely inhibited seed germination and plant growth, particularly in Lactuca sativa, which showed greater sensitivity compared to that of Lolium perenne. The results underscore the partial mitigating role of sand, although it was insufficient to prevent the toxic effects of CBs. The persistence of cellulose acetate in the environment and the continued release of hazardous chemicals highlight the ecological risks posed by cigarette butt pollution. These findings emphasize the need for improved waste management strategies and the development of biodegradable cigarette filters to reduce environmental contamination in coastal areas.

Evaluation of geotechnical, mineralogical and environmental properties of clayey soil stabilized with different industrial by-products: A comparative study

The utilisation of soil stabilization techniques employing binders like lime or cement enables the use of soils that are classified as disposable, thereby reducing the need for landfills and the consumption of natural resources. However, the production of lime and cement results in significant CO2 emissions. Therefore, the application of industrial by-products (IBP) for stabilizing expansive soils presents an opportunity to minimise the use of traditional binders. This study investigates the geotechnical, mechanical, mineralogical, and environmental properties of four IBP (biomass bottom ash, biomass fly ash, steel slag, and mixed recycled aggregate) combined with a silica-based nanomaterial for road layer applications. The technical feasibility of the use of IBP was demonstrated, especially in combination with nanomaterials, allowing a 66 % reduction in the percentage of added lime, obtaining significant improvements with minimal plasticity and swelling index and bearing capacity CBR values higher than 25 %, applying BBA, BFA and SS. An environmental assessment of leachate analysis was performance, showing an immobilization of heavy metals that makes the application of IBP feasible. In addition, a life cycle analysis study showed the environmental benefits of applying IBP, such as a 50 % reduction in CO2 emissions due to the reduction of lime, resulting from the use of these materials, thus promoting more sustainable economic models.

Metal Analysis of Leachate from the Organic Fraction of Urban Solid Waste (MSW) from the Municipality of Belém/PA

In this study, the analysis of metals in the solubilized extract of the organic fraction of Urban Solid Waste (MSW) from the municipality of Belém do Pará was carried out. The waste used in this research was collected in residential areas, through door-to-door collection, with the points and neighborhoods served in the municipality of Belém determined by the sectorization of these locations, with family income as the main parameter. The MSW was collected and transported to the segregation area. Gravimetric analysis of MSW was carried out and the selected organic and paper fractions were subjected to drying, crushing and sieving pre-treatment. Next, the solubilized extract of the organic fraction of MSW was obtained following the method set out in NBR nº 10.006/2004 of the Brazilian Association of Technical Standards. The values obtained were compared with CONAMA Resolutions n° 357/2005, 396/2008 and 430/2011, in addition to being compared with results of bibliographical research. The results indicated that these wastes do not comply with environmental and health regulations. Although a highly significant association was found between chromium and boron through Pearson’s correlation, the remaining strong correlations between other elements did not reach statistical significance. Furthermore, a similarity was observed in the solubilization conditions of these wastes with those found in landfill leachate.

Exploring freeze-injury mechanism through ion-specific analysis of leachate from reversibly versus irreversibly injured spinach (Spinacia oleracea L.) leaves

The present study analyzed four cations (K+, Ca2+, Mg2+, Fe2+) in leachate from freeze-injured spinach (Spinacia oleracea L. ‘Reflect’) leaves exposed for four freezing-durations (FDs) (0.5, 3.0, 5.5, 10.5 h) at −4.8 °C. Comparison of electrolyte leakage from right-after-thaw with that after 6-d recovery revealed that injury at 0.5 or 3 h FDs was recoverable but irreversible at 5.5 or 10.5 h FDs. Data suggests leakage of K+, the most abundant cation in leachate, can serve as a proxy for total electrolyte-leakage in determining plant freezing-tolerance and an ionic marker discerning moderate vs. severe injury. Quantitative correspondence between Ca2+- and K+-leakage supports earlier proposition that leaked K+ induces loss of membrane-Ca2+, which, in turn, promotes further K+-leakage due to weakened membrane. Reduced/undetectable Fe2+ in leachate at longer FDs suggests activation of Fenton reaction converting soluble Fe2+ into insoluble Fe3+. Enhanced Mg2+-leakage at greater freeze-injury suggests structural/functional impairment of chlorophyll/chloroplast complex.

Advanced understanding of the natural forces accelerating aging and release of black microplastics (tire wear particles) based on mechanism and toxicity analysis

Currently, tire wear particles (TWPs), a typical type of black microplastics (MPs), are frequently overlooked as the major source of MPs in aquatic environments. TWPs are widely distributed and exhibit complex environmental behaviors. However, how natural forces affect the aging and release behavior of TWPs at the nano(micro)scale remains inadequately explored. This study systematically investigated the aging behavior and mechanism of TWPs under the action of simulated natural light and high-temperature in both dry and wet environments, as well as the effect of aging treatment on the released leachate. The findings demonstrated that aging treatment significantly altered the physicochemical properties of TWPs, including chain scission and surface oxidation, and facilitated the release of heavy metals and organic additives in the meantime. In particular, the leaching concentration of Zn exhibited a positive linear relationship with exposure time. In the thermal-aging process, the oxidation of TWPs was primarily caused by superoxide anion (O2•−). During the photo-aging exposure, TWPs exhibited heightened electron-donating capacity, resulting in the formation of more O2•− and singlet oxygen (1O2) to attack TWPs. Moreover, the analysis of leachate produced under light and high-temperature conditions suggested that heavy metals exerted low ecological risks in water. Nonetheless, the photo-aging process enhanced the toxicity of released leachate to L929 cells, which could be attributed to highly toxic additive transformation products (such as HMMM-411 and 6PPD-Q) and more heavy metals. These findings shed light on the fate of TWPs and the ecological risks posed by aged TWPs in aquatic environments.

Assessment of the environmental impacts of utilizing coal ashes and OPC for soil stabilization applications: Leachate analysis in response to rainfall interaction

The construction industry is a leading sector for coal ashes utilization, including in cement manufacturing and soil stabilization applications. In soil stabilization, coal ashes, alongside Ordinary Portland Cement (OPC), are the most commonly used materials. However, the environmental impact of coal ashes, particularly the leaching of heavy metals from stabilized soil when exposed to rainfall, remains underexplored. There is a notable gap in assessing the environmental impacts of this utilization, particularly when the stabilized soil interacts with rainfall in real-world scenarios. Therefore, this study aimed to contribute to filling this gap. Accordingly, in this study, peat soil was stabilized by using fly ash, bottom ash, and OPC. The characterization of soil mixture materials, including physicochemical and engineering properties, was established and studied first. Following the environmental impact, simulations were conducted using a column to study soil leachate under different conditions and seasons (dry and wet) in response to its interaction with rainfall. The leachate was analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the concentrations of heavy metals, including copper (Cu), aluminum (Al), manganese (Mn), iron (Fe), and zinc (Zn). Additionally, Ion Chromatography (IC) was employed to determine the concentrations of major anions, including fluoride (F⁻), chloride (Cl⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and sulfate (SO₄²⁻). The findings revealed the complex interaction of the chemical stabilization processes and environmental factors with the leaching behavior of heavy metals and anions, highlighting the significant impact of stabilization on leaching patterns. To conclude, this study provides a valuable contribution to understanding the environmental and engineering implications of utilizing coal ashes in soil stabilization.

Decomposition and fragmentation of conventional and biobased plastic wastes in simulated and real aquatic systems

AbstractPlastics play a crucial role in our daily lives. The challenge, however, is that they become waste and contribute to a global environmental problem, increasing concerns about pollution and the urgent need to protect the environment. The accumulation and fragmentation of plastic waste, especially micro- and nanoplastics in aquatic systems, poses a significant threat to ecosystems and human health. In this study, the decomposition and fragmentation processes of conventional and biobased plastic waste in simulated water bodies (waters with different pH values) and in real water systems (tap water and seawater) are investigated over a period of one and six months. Three types of plastic were examined: thermoplastic polyethylene terephthalate and thermoset melamine etherified resin in the form of nonwovens and biobased polylactic acid (PLA) in the form of foils. Such a comprehensive study involving these three types of plastics and the methodology for tracking degradation in water bodies has not been conducted before, which underlines the novelty of the present work. After aging of the plastics, both the solid fraction and the leachate in the liquid phase were carefully examined. The parameters studied include mass loss, structural changes and alterations in functional groups observed in the aged plastics. Post-exposure assessment of the fragmented pieces includes quantification of the microplastic, microscopic observations and confirmation of composition by in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. The leachate analysis includes pH, conductivity, turbidity, total carbon and microplastic size distribution. The results highlight the importance of plastic waste morphology and the minor degradation of biobased PLA and show that microfibers contribute to increased fragmentation in all aquatic systems and leave a significant ecological footprint. This study underlines the crucial importance of post-consumer plastic waste management and provides valuable insights into strategies for environmental protection. It also addresses the pressing issue of plastic pollution and provides evidence-based measures to mitigate its environmental impact. Graphical abstract

A Sustainable Recycling Approach to Regenerate Graphite from Industrially Sourced Failed Anodes

Recycling graphite from Li-ion battery (LIB) waste plays an important role in increasing the accessibility of graphite resources and sustainable recovery. This presentation describes our work to purify graphite from failed (i.e., out-of-specification) anodes in LIB manufacturing by focusing on the most common contaminant: copper, used as the current collector in LIB anodes.A new, three-step scalable and environmentally friendly approach was used to provide a cost-effective and sustainable method in industrial settings to recycle failed anodes during the early stages of battery manufacturing.The study aimed to understand the differences between new, battery-grade graphite and recycled graphite from anode production waste. In particular, focus was placed on the effect of metallic Cu residues on electrochemical performance. The efficiency of Cu removal from graphite was quantified by Microwave Plasma – Atomic Emission Spectroscopy (MP-AES) analysis of leachates. The following experimental parameters were studied to maximize Cu leaching efficiency: solid-to-liquid ratio, temperature, acid concentration, time and stirring speed.The surface morphology and elemental composition of leached and thermally treated purified graphite were analysed by Scanning Electron Microscopy – Energy Dispersive Spectroscopy (SEM-EDS) and Laser Induced Breakdown Spectroscopy (LIBS). The specific surface area and crystallographic parameters were measured by Braunauer–Emmett–Teller Analysis (BET) and X-Ray Diffraction (XRD), respectively. The electrochemical performance was evaluated by galvanostatic cycling with potential limitation versus Li+/Li. These five techniques were carried out on the solid residues after each stage of the regeneration procedure. The results were compared with battery-grade graphite to assess the effectiveness of our sustainable recycling approach to reuse graphite from failed anodes in LIBs.

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies.

Plastic contamination is one of the concerns of our age. With more than 150 million tons of plastic floating in the oceans, and a further 8 million tons arriving to the water each year, in recent times the scientific community has been studying the effects these plastics have on sea life both in the field and with experimental approaches. Laboratory based studies have been using both natural sea water and artificial sea water for testing various aspects of plastic contamination, including the study of chemicals leached from the plastic particles to the water. We set out to test this equivalence, looking at the leaching of heavy metals form plastic particles. We obtained leachates of polyvinyl chloride plastic pre-production nurdles both in natural and artificial sea water and determined the elements in excess from untreated water by Inductively coupled plasma - optical emission spectrometry. We then used these different leachates to assess developmental success in the tunicate Ciona intestinalis by treating fertilised eggs through their development to hatched larvae. Here we report that chemical analysis of polyvinyl chloride plastic pre-production pellet leachates shows a different composition in natural and artificial sea water. We find that the zinc leaching from the plastic particles is up to five times higher in natural seawater than in artificial seawater, and this can have an effect in the toxicological studies derived. Indeed, we observe different effects in the development of C. intestinalis when using leachates in natural or artificial sea water. We also observe that not all artificial sea waters are suitable for studying the development of the tunicate C. intestinalis. Our results show that, at least in this case, both types of water are not equivalent to produce plastic leachaetes and suggest that precaution should be taken when conclusions are derived from results obtained in artificial sea water.

Release of contaminants from polymer surfaces under condition of organized fluid flows

The use of polymers for water storage or distribution is closely monitored, especially with regard to the possible contamination with substances coming from the material's surfaces. Different standards are practiced across countries according to type of applied materials and such test methods are prevalently based on constant temperature conditions. However, these polymers systems could be located in diverse environment which does not necessarily provide constant conditions. Experimental findings show that exposure of liquid inside polymeric materials to specific temperature gradients, and consequently to emerging organized flows, can result in an accelerated leaching of undesirable substances from the solid surface. In presented work model steady-state and organized flow conditions are used to compare release of contaminates from polyethylene by measuring of surface tension, UV–Vis spectroscopy, FTIR, scanning electron microscopy and elemental analysis of polymer surfaces and water leachates. The pilot study shows that convective flow generated via temperature gradient significantly affects contaminant release in comparison to a steady state and mixing flow conditions.

A Novel Technosol Formulation for Sustainable Landfill Top Covers Using Non-Hazardous Wastes

This study explores the potential of non-hazardous wastes for crafting an engineered soil-like material (Technosol) suitable for landfill capping applications. Three distinct materials—waste foundry sand (WFS), washing aggregate sludge (WAS), and composted biosolids (CBS)—were strategically combined to develop this innovative Technosol. The formulation process involved a comprehensive analysis of their physical–chemical properties, mineral composition, leachate quality, and a series of geotechnical assessments to ensure compliance with landfill top cover construction standards. The blend 90WFS/10WAS showed optimal geotechnical properties for constructing a protective layer, including maximum dry density (1.77 g cm−3), void ratio (0.4), CBR index (23.2), cohesive strength (40 kPa), internal friction (ϕ = 30°), and permeability coefficient (k = 1.48 × 10−6 cm s−1). Further enhancement was achieved by adding 10% CBS, resulting in the development of a functional organo-mineral topsoil horizon (81WFS/9WAS/10CBS). Importantly, leachate analysis confirmed the negligible environmental footprint of this Technosol. Moreover, a pot-based experiment with Brassica juncea planting validated its capacity to support plant growth and establish a vegetative cover on the landfill surface.

Ecotoxicological assessment, oxidative response, and enzyme activity disorder of the rotifer Brachionus asplanchnoidis exposed to a toxic cocktail of spent lithium-ion battery leachate

Spent lithium-ion batteries (LIBs) have emerged as a major source of waste due to their low recovery rate. The physical disposal of spent LIBs can lead to the leaching of their contents into the surrounding environment. While it is widely agreed that hazardous substances such as nickel and cobalt in the leachate can pose a threat to the environment and human health, the overall composition and toxicity of LIB leachate remain unclear. In this study, a chemical analysis of leachate from spent LIBs was conducted to identify its primary constituents. The ecotoxicological parameters of the model organism, rotifer Brachionus asplanchnoidis, were assessed to elucidate the toxicity of the LIB leachate. Subsequent experiments elucidated the impacts of the LIB leachate and its representative components on the malondialdehyde (MDA) level, antioxidant capacity, and enzyme activity of B. asplanchnoidis. The results indicate that both the LIB leachate and its components are harmful to individual rotifers due to the adverse effects of stress-induced disturbances in biochemical indicators, posing a threat to population development. The intensified poisoning phenomenon under combined stress suggests the presence of complex synergistic effects among the components of LIB leachate. Due to the likely environmental and biological hazards, LIBs should be strictly managed after disposal. Additionally, more economical and eco-friendly recycling and treatment technologies need to be developed and commercialized.

Leachate analysis of trace metals from e-waste disposed of in landfills and open dumps

Waste electrical and electronic equipment (WEEE, or e-waste) has been largely generated worldwide, but the estimated proportion of WEEE that undergoes the correct disposal is very low. The objective of this study was to evaluate e-waste trace metals in the leachate from disposal of WEEE in soil, using different analytical approaches to determine how these methods may interfere in the results. Different forms of WEEE and MSW landfilling and open dumping were simulated in column reactors to analyse the resultant leachates. Analyses of heavy metals in the leachates were performed in two ways: via inductively coupled plasma-mass-spectrometry with acid digestion of samples, following American Standard 3015A, and via inductively coupled plasma-optical emission spectrometry without acid digestion (US Environmental Protection Agency - USEPA, 2007). Metal concentrations found in the landfill and dumping simulations were similar, but a higher concentration of metals was found in samples with e-waste content, and those undergoing acid digestion prior to ICP analyses. Exceptions were Ba e Zn with a higher concentration without digestion, what may indicate the appearance of matrix effect. Concentrations of Pb, Cu and Mn in the leachates indicate possible interference with MSW. Additionally, it was evident that the timescale of observation influenced the results.

Measuring the Fate and Natural Attenuation Potential of a Viscous Marine Fuel on an Artificial Beach Mesocosm

Shoreline oiling poses a risk to coastal ecosystems and resources. Understanding the natural attenuation potential and impact of different sediment types is important for choosing appropriate intervention strategies and priority areas following a spill. Simulated IFO-40 oil spills on artificial beach mesocosms were carried out using different sediment types: sandy beach and sandy tidal flat, under low energy tidal cycles over a 5-day period. Chemical and biological analysis of leachate and sediment was conducted to understand the movement of oil through these mesocosms. Rapid oil movement from the oil slick to the surface sediment layer was observed in the sandy beach enclosures, while slower oil movement was observed in the sandy tidal flat enclosures. Increased hydrocarbon dissolution was observed in the sandy beach enclosures, marked by higher concentrations of low molecular weight n-Alkanes (C12 − 15) and naphthalenes (C0 − 3) in sandy beach leachate compared to sandy tidal flat samples. Despite the increase in hydrocarbons, there were no major shifts in microbial communities observed in the leachate and sediment compartments for either sediment type. Both prokaryote and microeukaryote communities differed between the two sediment types, with little overlap between dominant sequences. Our results indicate that limited oil penetration occurs within sandy tidal flat shorelines resulting in oil accumulation suggesting that sorbent or vacuuming could be used as emergency response to minimize the environmental and ecological impacts of spilled oil.

Evaluation of hydraulic conductivity and self-healing potential of punctured geosynthetic clay liner

ABSTRACT An experimental study was conducted on the modified geosynthetic clay liner (GCL) specimen by replacing encapsulated Sodium Bentonite (Na-B) with different percentages of locally available black cotton soil (BCS). The specimens with punctured hole sizes of 4, 8, and 12 mm in diameter were tested for hydraulic conductivity and self-healing capacity assessed by improved triaxial apparatus. The flowing permeant was prepared with the heavy metals: iron, zinc, nickel, and total chromium based on the results of the chemical analysis of leachate collected from the municipal solid waste site (MSW). The experiment results were observed at 24, 48 and 72 hours. The results were analysed to identify the best specimen mix (Na-B and BCS) regarding the lowest hydraulic conductivity and highest self-healing potential. The results demonstrated that BCS can be utilized in modified GCL as an impermeable barrier for leachate percolation at the MSW dump site.

Effect of liming on polycyclic aromatic hydrocarbons leaching from hydrocarbon-contaminated tectogenic industriosol

Soil stabilization/solidification is commonly employed remediation method for contaminated soils. Until now, limited attention has been given to the application of quicklime in polycyclic aromatic hydrocarbons (PAHs) contaminated soil. We treated a tectogenic industriosol spiked with 50 mg kg−1 of four PAHs (12.5 mg kg−1 each of fluorene (FLU), phenanthrene (PHE), fluoranthene (FLT) and pyrene (PYR)) using three different liming agents at 1% (w:w): quicklime (CaO), hydrated lime (Ca(OH)2) and carbonate calcium (CaCO3). All treated samples were leached in water at a solid-liquid ratio of 10, with subsequent analysis of leached soil and leachates for PAHs content. Results revealed that the addition of liming agents led to a reduction in FLU and PHE concentrations in treated soil by 6.81 ± 2.47% and 28.88 ± 4.18%, respectively, compared to a not-treated sol. However, no significant impact was observed on the 4-cycles PAHs (FLT and PYR). The addition of liming agents also significantly decreased the amount of PAHs in the leachate, by 100% for FLU and PHE, and by 74.9 ± 17.5% and 72.3 ± 34.8%, for FLT and PYR, respectively, compared to not limed soil. Among the liming agents, quicklime was the most effective in reducing the amount of 4 cycles PAHs in the leachate. Various mechanisms, such as encapsulation, volatilization and oxidation could contribute to this observed reduction. Quicklime treatment at a concentration of 1% w:w in PAHs-contaminated soil emerges as a promising technique to effectively reduce PAHs concentration in soils and mitigate PAHs mobility through leaching. This study also sheds light on the possibility to limit CO2 emissions and resources exploitation to assure the remediation process, thereby enhancing its overall environmental sustainability.

Assessing leachate contamination and groundwater vulnerability in urban dumpsites: a case study of the Ipata Area, Ilorin, Nigeria

This study explores the extent of leachate contamination and groundwater vulnerability in urban dumpsites, with a specific focus on the Ipata area in Ilorin, Nigeria. The study employs a combination of 2D Electrical Resistivity Tomography (ERT), soil classification, and physicochemical analyses to investigate the percolation of leachate into groundwater and its potential environmental and health implications. The ERT data unveiled subsurface layers, highlighting the presence of decomposed topsoil down to approximately 1.2m. Beneath this layer, a low-resistivity zone (6.53 to 10.7 ?m) indicated the potential risk of leachate percolation into groundwater. Soil classification revealed a shallow topsoil layer with insufficient clay content to hinder leachate penetration, emphasizing the need for enhanced containment measures. Physicochemical analysis of leachate, well water, and soil displayed variations in key parameters such as pH, electrical conductivity, total dissolved solids, and anion concentrations. Leachate exhibited high pH and electrical conductivity, suggesting elevated total dissolved solids, while well water remained within acceptable pH limits for drinking water. Heavy metal concentrations exceeded permissible WHO limits in topsoil, leachate, and well water, with cadmium presenting a high ecological risk. The absence of persistent organic pollutants (POPs) in the samples indicates a current focus on heavy metals as a primary concern. In conclusion, this study underscores the urgent need for proactive pollution abatement measures in urban dumpsites like Ipata. Regular monitoring of surface and groundwater quality is essential to safeguard public health and the environment.

A novel portable microchip electrophoresis system for rapid on-site detection of soil nutrient ions

The conventional techniques for soil nutrient ion detection face challenges, including prolonged preparation periods and the necessity for distinct instruments tailored to each specific ion. To address these issues, we have engineered a cutting-edge soil nutrient ion detection apparatus: the Microchip Electrophoresis Soil Nutrient Ion Portable Detection System (ME-SNI-PDS). This system, leveraging microchip electrophoresis with a capacitively coupled contactless conductivity detector (ME-C4D), simplifies the detection process with user-friendly touchscreen controls. Our system is capable of simultaneous detection of key soil nutrient ions—ammonium (NH4 +), calcium (Ca2+), magnesium (Mg2+), potassium (K+), nitrate (NO3 −), and dihydrogen phosphate (H2PO4 −)—in a swift 180 s, facilitated by precise voltage regulation. We have refined the buffer solution, consisting of 20 mM 2-(N-morpholinyl)-ethanesulfonic acid and L-histidine, with the addition of 0.01 mM cetyltrimethylammonium bromide and 10 mM 18-crown-6, to ensure the complete resolution of soil nutrient ions. Following this, we established highly accurate peak height-to-concentration correlations for the six aforementioned ions, each with a coefficient of determination (R2) exceeding 0.99. The detection limits for these ions stand at a remarkably low concentration of 0.05 mM, translating to 0.9 mg l−1 for NH4 +, 2.0 mg l−1 for Ca2+, 1.2 mg l−1 for Mg2+, 1.96 mg l−1 for K+, 3.1 mg l−1 for NO3 −, and 4.85 mg l−1 for H2PO4 −. Subsequent soil leachate analysis via the ME-SNI-PDS has yielded ion content data that, upon comparison with results from continuous flow analyser (CFA) and inductively coupled plasma atomic emission spectrometry, confirm the system’s exceptional integration, compactness, portability, speed, and efficiency. The ME-SNI-PDS shows immense promise for application in precision agriculture and the prevention of surface soil pollution. It is poised to make a significant impact in the realm of crop fertilization and environmental stewardship.

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies

Background Plastic contamination is one of the concerns of our age. With more than 150 million tons of plastic floating in the oceans, and a further 8 million tons arriving to the water each year, in recent times the scientific community has been studying the effects these plastics have on sea life both in the field and with experimental approaches. Laboratory based studies have been using both natural sea water and artificial sea water for testing various aspects of plastic contamination, including the study of chemicals leached from the plastic particles to the water. Methods We obtained leachates of PVC plastic pre-production nurdles both in natural and artificial sea water, and determined the elements in excess from untreated water by Inductively coupled plasma – optical emission spectrometry. We then used these different leachates to assess developmental success in the tunicate Ciona intestinalis by treating fertilised eggs through their development to hatched larvae. Results Here we report that chemical analysis of PVC plastic pre-production pellet leachates shows a different composition in natural and artificial sea water. We find that the Zn leaching from the plastic particles is reduced up to five times in artificial sea water, and this can have an effect in the toxicological studies derived. Indeed, we observe different effects in the development of C. intestinalis when using leachates in natural or artificial sea water. We also observe that not all artificial sea waters are suitable for studying the development of the tunicarte C. intestinalis. Conclusions Our results show that, at least in this case, both types of water are not equivalent to produce plastic leachaetes and suggest that precaution should be taken when conclusions are derived from results obtained in artificial sea water.

Dissolved organic nitrogen is a key to improving the biological treatment potential of landfill leachate

Biological treatment is one of the most promising efficient, low-carbon and affordable approaches for the treatment of recalcitrantly degradable wastewater, such as landfill leachate. However, even the macroscopic molecular level analysis of dissolved organic matter (DOM) is limiting to the enhancement of biological treatment efficacy, and there is an urgent need for deeper exploration of DOM to gain insights into the key constraining substances. In the present study targeting at piercing leachate organic at molecular level, nitrogen-containing dissolved organic matter (DOMN) was identified to be the bottleneck that govern the biotreatment potential. The conclusion was made based on two series of experiments that compared the same anoxic-aerobic membrane bioreactor process (A process) operated stably at different regions, and compared with C process that coupling A process with a circulation aeration membrane bioreactor to improve aeration efficiency. The results confirmed that the relative abundance of DOMN was absolutely dominant among the three categories of DOM in all biologically treated samples, contributing to 60.36 %–65.81 % in removed-DOM, 60.33 %–70.95 % in refractory-DOM and 63.14 %–71.36 % in derived-DOM. Specifically, the high latitude A process had much lower DOMN removal rate than the low latitude A process (p < 0.05) and much higher refractory and derivatization rates than the low latitude A process (p < 0.05). DOM had similar results. No statistically significant differences were observed in the proportion of the three categories of DOM (DOMN), the elements composition, and the subcategory composition of the C process compared to the A process, in which the DOM (DOMN) derivation rate of NEC1-C (31.92 % and 33.41 %) was much higher than that of NEC1-A (20.88 % and 22.19 %). However, the AIwa and AImodwa of the derived-DOM (DOMN) were significantly higher in the C process than in the A process, which implied that excessive aeration did not enhance the biological treatment potential of the A process, but instead led to the proliferation of microorganisms and the secretion of extracellular polymer substances, which resulted in the derivation of more complex compounds. The results of the correlation analysis indicated that there were some regional differences in the molecular information of DOMN driven by climate temperature. In addition, it was worth mentioning that the nominal oxidation state of carbon (NOSCwa) of derived-DOMN in different regions of A process was noticeably higher than the corresponding DOM (p < 0.0001), implying that the derived-DOMN were still highly biodegradable, in other words, there was still great room for improving the biological treatment potential of landfill leachate. The present study provided a deeper insight and analysis of landfill leachate at the molecular level (DOMN) through multiple practical engineering cases, with a view to providing a theoretical basis for efficient optimization of biological treatment.