Search Results (212)

Nickel (Ni) and copper (Cu) are essential soil micronutrients that are beneficial for plant growth and development when applied at the right levels to deficient soils. However, they can also be of concern if excessive application leads to accumulation in soil, causing soil fertility problems that can compromise food production as well as result in human exposure to these metals if they enter the food chain. The application of Ni and Cu salts can strongly influence the nitrogen (N) cycle as they can stimulate soil microbiological activity that leads to N losses to the atmosphere. A laboratory incubation was conducted to study the effect of these metal salts on gaseous N emissions. Copper sulphate (CuSO₄) and nickel sulphate (NiSO₄) were applied at rates below soil toxicity (3.0 kg Ni/ha and 7.5 kg Cu/ha), together with ¹⁵N-labelled-urea (rate 100 kg N/ha) and under two soil water-filled pore space (WFPS) conditions: continuous anaerobic (75% WFPS) versus aerobic (50% WFPS) followed by an anaerobic (75% WFPS) cycle. Results showed no significant effect of the Ni application on nitric oxide (NO) emissions at the low rates applied. However, there was an indication of a meaningful (p = 0.051) production of this gas under aerobic soil conditions. No N₂ emissions were observed from any treatment (only expected to occur under anaerobic conditions) during the 43 days of the incubation, which could suggest that, as for Ni, the selected Cu application rate may not clearly stimulate the complete denitrification process to produce N₂. It is possible that the expected increase in N₂ emissions or larger NO emissions were counteracted by the low amount of soil-extractable Cu and Ni available after application because of binding processes with the clay fraction (48% clay) and the acid nature of the Cambisol used in the incubation. Further research into the effect of metal applications to contrasting soil types, with varied application rates and repeated application events, and under differing soil moisture conditions on N emissions is required. Furthermore, experiments should also be conducted at finer scales to elucidate the specific effect of these metal application rates on the biochemical processes responsible for the N gases produced. Full article

Flonicamid is a systemic pyridinecarboxamide insecticide used to control sap-sucking pests in agricultural crops. An ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method was developed for the simultaneous determination of flonicamid and its metabolites, N-(4-trifluoromethylnicotinoyl)glycine (TFNG), 4-(trifluoromethyl)nicotinamide (TFNA-AM), and 4-(trifluoromethyl)nicotinic acid (TFNA) in rice plants, brown rice, rice husks, paddy soil, and paddy water. Method validation showed average recoveries of 73–115% with relative standard deviations of 1.1–9.9% across different matrices at three fortification levels. Field and laboratory experiments were conducted to characterize the dissipation, degradation, and transformation of flonicamid in the paddy ecosystem, and the dietary risk was assessed. Field dissipation followed first-order kinetics, with half-lives of 5.8, 2.9, and 7.1 days in rice plants, paddy soil, and paddy water, respectively. Under laboratory conditions, degradation proceeded markedly faster under aerobic than anaerobic conditions, with half-lives of 0.8–7.1 and 4.7–17.8 days in five typical Chinese soils, respectively. Six transformation products were identified by UHPLC–Q-TOF/MS coupled with UNIFI software (v1.9.4.0), including a novel product (M210) reported for the first time. At pre-harvest intervals of 7–21 days, terminal residues of flonicamid in brown rice were all below the Chinese maximum residue limit (MRL) of 0.1 mg/kg. Dietary risk assessment revealed that the acceptable daily intake percentages (%ADI) for 12 population subgroups ranged from 0.128% to 1.031% based on the parent compound, and from 0.404% to 3.808% under the EU residue definition. All values were far below 100%. These results indicate that flonicamid, when applied according to Good Agricultural Practice (GAP), poses a negligible dietary risk to consumers. Full article

This study aims to identify microbial strain resources capable of degrading diflufenican and elucidate their degradation characteristics, with the goal of mitigating the phytotoxicity hazards associated with the prolonged use of this persistent herbicide. A degradation strain was isolated, purified, and screened from wheat field soils that had been subjected to diflufenican treatment using an enrichment culture method. The taxonomic classification of the strain was determined through a comprehensive analysis of its morphology, physiology, biochemistry, as well as its 16S rRNA gene sequence. The results demonstrated that the screened bacterial strain 88-1 could utilize diflufenican as its metabolic carbon source and was identified as Enterobacter hormaechei, a facultative anaerobe. The degradation efficiency of strain 88-1 on diflufenican was closely associated with cultivation time, the initial concentration of the herbicide, temperature, pH, and inoculation amount of the strain. Additionally, the degradation rate exhibits a positive correlation with the biomass of the strain. Under optimal conditions (40 mg/L diflufenican, 30 °C, pH 8.0, 10% inoculum), the highest observed degradation efficiency and viable cell density over the 120 h incubation period were 55.11% and 8.05 × 10⁶ CFU/mL, respectively. Furthermore, rapid biotransformation commenced within 24 h, yielding a cascade of metabolites, with 2-(3-(trifluoromethyl)phenoxy)pyridine-3-carboxamide identified as the primary metabolite. These findings suggest that strain 88-1 holds promise for the bioremediation of soils contaminated with diflufenican. Full article

Growing environmental concerns over petroleum-based plastics have increased interest in sustainable and biodegradable alternatives such as polyhydroxybutyrate (PHB). PHB is a naturally produced biopolymer synthesized by microorganisms and is widely recognized for its biodegradability, biocompatibility, renewability, and thermoplastic properties. Despite these advantages, PHB use remains limited by brittleness, high crystallinity, low thermal stability, a narrow processing window, and high production costs. This review discusses the production, properties, biodegradation behavior, and applications of PHB, with a focus on strategies to improve its performance. Modification approaches, including copolymerization, polymer blending, filler reinforcement, plasticization, and hybrid composite formulation, are critically reviewed to evaluate their effects on the thermal, mechanical, and processing behavior of PHB-based materials. The review also highlights recent developments in additive manufacturing, particularly fused deposition modeling/fused filament fabrication (FDM/FFF) for the extrusion of biodegradable PHB composite filaments. In addition, the biodegradation of PHB under various environmental conditions, including soil, compost, freshwater, marine, aerobic, and anaerobic environments, are discussed. Current challenges, research gaps, commercialization barriers, and future opportunities related to sustainable feedstocks, advanced composites, additive manufacturing, and circular economy integration are addressed. Overall, PHB shows strong potential as a sustainable alternative for packaging, biomedical, agricultural, and three-dimensional (3D) printing applications. Full article

Conventional ureolytic microbial soil stabilization can generate ammonium-containing by-products and may show reduced treatment uniformity in deep soils where mass transport is limited. This study investigated the feasibility of using facultatively anaerobic yeast to stabilize loess under aerobic and anaerobic curing conditions. Specimens were prepared using a single-mixing method and cured for 3, 7, 14, and 28 days. Unconfined compression tests, unconsolidated–undrained triaxial tests, scanning electron microscopy, X-ray diffraction, and acid-washing analysis were conducted. Yeast treatment increased the unconfined compressive strength of loess to 99.8–109.9 kPa under aerobic curing and 89.1–95.7 kPa under anaerobic curing, compared with 81.3 kPa for untreated loess. Cohesion increased from 25.30 kPa to 27.24–33.14 kPa, whereas the internal friction angle remained within 37–39°. Microstructural observations revealed fibrous and film-like bonding materials between soil particles, while no obvious newly formed crystalline calcium carbonate was detected. The acid-washing results also indicated no evident net increase in calcium carbonate content. The strengthening effect was therefore attributed mainly to particle bonding associated with polymeric or extracellular-polymeric-substance-like products, rather than extensive calcium carbonate precipitation. These results demonstrate the potential of yeast as an environmentally friendly biological agent for loess stabilization. Full article

Storage of livestock effluents represents a major source of ammonia (NH₃) emissions into the atmosphere. Reducing ammonia volatilisation is essential to improve the efficiency of nutrient use, mitigate air pollution, and enhance the overall sustainability of livestock production systems aligned with the principles of the circular economy. Therefore, identifying efficient and sustainable mitigation strategies is crucial. Conventional floating covers are commonly used to reduce emissions; however, they present limitations in terms of management, durability, and cost. This study proposes a novel approach by comparing traditional floating cover materials like straw and light expanded clay with biochar as an innovative and sustainable mitigation strategy to reduce ammonia volatilisation from the liquid fraction of buffalo digestate obtained from an anaerobic digestion plant in southern Italy. All cover materials were applied at a uniform thickness of 2 cm under laboratory conditions using a dynamic chamber technique. Additionally, a cost analysis was performed considering the material purchase cost for an average storage tank of 700 m² and two hypothetical reduction efficiencies (50% and 70%). Results indicated that biochar was the most effective cover, achieving a 67% reduction in ammonia emissions compared with the uncovered control. Light expanded clay exhibited the lowest efficiency, likely due to its insufficient sealing capacity at the applied thickness. From an economic perspective, biochar becomes increasingly competitive when emission reduction efficiency is accounted for, owing to its favourable physical–chemical properties. The results highlight the potential of using biochar as a sustainable, circular strategy for mitigating atmospheric emissions and improving nitrogen conservation, while also creating opportunities for its subsequent reuse in agriculture as a soil amendment. Full article

The dynamics of methane (CH₄), nitrous oxide (N₂O) and carbon dioxide (CO₂) in groundwater have rarely been investigated. As dissolved gases they may be transported to distant sites and, hence, to the atmosphere. Crumps Cave (CC) is located on a perched aquifer in south-central Kentucky. Water was sampled at a waterfall within the cave located 15 m below the surface, at two adjacent surface wells 15 m and 50 m deep, providing samples from the epikarst and regional aquifer, respectively. Dissolved gases and geochemistry parameters were analyzed for seasonal changes across three years of weekly monitoring (2015–2017) using Kruskal–Wallis H tests and Bonferroni-corrected pairwise comparisons. Dissolved CO₂ concentrations are mainly controlled by percolation through the epikarst, influenced by soil respiration, and vary with rainfall and seasonal temperature fluctuations. CH₄ showed a site-dependent pattern: concentrations were significantly elevated in warm seasons at the shallow and deep wells, where anaerobic conditions and agriculturally derived organic matter promote methanogenesis; no seasonal variation was detected at the cave site, where oxic conditions limit CH₄ year-round. N₂O was significantly elevated in cold seasons at all three sites, driven by cold-season denitrification of agriculturally derived nitrates. N₂O did not differ between sites, indicating seasonal temperature-driven denitrification as the primary control rather than site hydrology, with cold-season denitrification of agriculturally derived nitrates from fertilizer application. Indirect gas emissions are characteristic of karst systems and may be transported or stored in aquifers through complex interactions of groundwater recharge, microbial activity, and seasonal land-use variability. Full article

Heavy metal-contaminated post-mining soils remain persistent sources of ecological degradation and contaminant dispersion. This study provides a quantitative field-based assessment of sorghum (Sorghum bicolor), maize (Zea mays) and soybean (Glycine max) cultivated on heavy metal-affected mining soil from the Jiu Valley, Romania, within a Living Lab platform. Soil properties, pseudo-total metal concentrations, multi-year biomass production, growth indicators, vegetation cover and aboveground plant metal concentrations were evaluated. The soils showed slightly acidic to near-neutral pH, low organic matter and multi-metal contamination, with Cr, Cu, Ni, Zn and Pb ranging from 82 to 146, 51 to 92, 41 to 79, 156 to 287 and 64 to 121 mg kg⁻¹, respectively. Total fresh biomass increased from 85 kg in the first cultivation year to 487 kg in the third cultivation year, with sorghum showing the highest final production (230 kg) and vegetation cover (55–86%). Aboveground Cr, Cu, Ni, Zn and Pb concentrations measured at species-specific levels of 6.21–8.06, 8.77–10.64, 7.48–12.92, 38.01–47.11 and 4.32–6.46 mg kg⁻¹ dry weight, respectively. Sorghum showed the highest preliminary phytomanagement suitability, mainly through stronger vegetation cover formation, higher fresh biomass production and lower visible stress under the investigated field conditions. Maize showed intermediate feasibility, whereas soybean appeared more sensitive to the degraded substrate. Biomass reuse should be considered only under controlled non-food pathways, such as pyrolysis or anaerobic digestion, and should only be considered after a dedicated assessment of dry biomass, conversion residues and metal fate. Full article

Tofu wastewater (TWW), characterized as a high-strength organic effluent with elevated chemical oxygen demand (COD) and low pH, presents significant environmental challenges, including eutrophication, soil degradation, and greenhouse gas emissions. Conventional disposal methods have proven inadequate in mitigating these risks; however, thermophilic anaerobic digestion (TAD) has emerged as a viable technology for bioenergy recovery. Nonetheless, TAD is impeded by rapid acidification, ammonia and hydrogen sulfide inhibition, and the accumulation of volatile fatty acids (VFAs). This review introduces nano-calcium-peroxide-modified biochar (nano-CaO₂/BC) as a multifunctional additive designed to establish an integrated framework for intervention, risk mitigation, and resource recovery. The proposed amendment synergistically combines the adsorptive and microbial-supportive properties of biochar with the controlled oxidative and alkaline characteristics of nano-CaO₂. Under thermophilic conditions, the slow hydrolysis of nano-CaO₂ generates transient microaerobic zones that enhance polymer hydrolysis, suppress ammonia (NH₃) and hydrogen sulfide (H₂S) formation, and facilitate the oxidation of inhibitory VFAs, concurrently releasing calcium hydroxide (Ca(OH)₂) for sustained pH buffering. Utilizing failure mode and effects analysis (FMEA) as a semi-quantitative assessment tool, the results indicate that the composite significantly reduces risk priority numbers associated with acidification, ammonia toxicity, and sulfide inhibition when compared with conventional TAD methods. The resultant digestates, which are enriched in nutrients and recalcitrant carbon, possess the potential to serve as valuable soil amendments, thereby contributing to a circular bioeconomy. A techno-economic assessment grounded in unit cost analysis suggests that positive net benefits may be realized through enhanced biogas recovery and the mitigation of environmental penalties. However, empirical validation at the pilot scale is essential to substantiate the projected performance. This review underscores critical knowledge gaps and proposes a systematic experimental framework aimed at translating the conceptual risk mitigation strategy into practical applications. Full article

Soil organic carbon (SOC) responds rapidly to vegetation changes, and exploring SOC sequestration mechanisms under different vegetation types is critical for optimizing wetland carbon sink functions. This study investigated the abiotic and biotic mechanisms driving SOC stability across four typical vegetation types (reed marsh, woodland, farmland, and wasteland) in the 0–10 cm and 10–20 cm soil layers of Hengshui Lake wetland. Results showed that reed marshes exhibited the highest total organic carbon (TOC) and particulate organic carbon (POC), owing to anaerobic soil conditions and stable macroaggregate physical protection. Woodlands accumulated higher dissolved organic carbon (DOC) and microbial biomass carbon (MBC) via an efficient microbial carbon pump, despite weaker aggregate stability. In contrast, farmlands and wastelands presented intense labile organic carbon (LOC) turnover and enzymatic decomposition, accelerating SOC mineralization and carbon dissipation with poor carbon sequestration capacity. Proteobacteria and Acidobacteriota dominated bacterial communities, while Ascomycota prevailed in fungi. Soil water content (SWC) and bulk density (BD) were the core drivers of microbial community succession, and fungi were more sensitive to vegetation changes. Conclusively, distinct vegetation types shape divergent SOC sequestration pathways. This work provides a theoretical basis for wetland restoration and regional carbon sink enhancement. Full article

Fish-processing residues represent a significant environmental challenge due to their high moisture and nitrogen contents, which favor greenhouse gas (GHG) emissions during degradation. This study evaluated how different waste management strategies affect GHG emissions from fish waste, including conventional composting (Bulk), composting amended with biochar (BulkBioch), burial with soil (S), and burial with soil plus sawdust (BulkS). Daily emissions of CH₄, N₂O, and CO₂ were monitored, and cumulative emissions were modeled using generalized additive models. Composting treatments (Bulk and BulkBioch) released higher CO₂, suggesting greater microbial degradation, while burial treatments developed earlier anaerobic conditions with reduced decomposition efficiency. Bulk showed the highest cumulative CH₄ and CO₂ emissions, whereas N₂O fluxes were greater in burial methods, reaching 2.18 g N₂O kg⁻¹ TS in S. Biochar addition was associated with 15% and 10% lower CH₄ and N₂O emissions, respectively, and earlier stabilization of CH4 emissions. In global warming potential, BulkBioch presented the lowest climate impact (305 g CO₂-eq kg⁻¹ fish), followed by Bulk (338 g CO₂-eq kg⁻¹), whereas BulkS reached up to 599 g CO₂-eq kg⁻¹. The use of bulking agents in burial resulted in lower CH₄ buildup and greater nutrient retention. Overall, combining bulking agents and biochar may represent a promising strategy to mitigate GHG emissions while supporting nutrient conservation. Full article

Methane (CH₄) is the second most important greenhouse gas after carbon dioxide (CO₂), and its atmospheric concentration is on the rise. Soil CH₄ consumption (=absorption) capacity is declining due to reduced forests and green spaces, as well as other environmental factors and anaerobic stresses. Environmental and stand structure parameters were cross-referenced with publicly available international ecosystem databases, such as FLUXNET, ICOS, NEON, AmeriFlux, the TRY plant trait database and the Oak Ridge FACE site. Searches were conducted using keywords such as region, water level, and stand density. The data indicate that under high-CO₂ conditions, the increase of forest canopy density leads to increased litter accumulation on the forest floor and reduced sunlight penetration, creating anaerobic conditions. This can cause forests to shift from CH₄ consumption to CH₄ release. Based on these findings, we discussed methods to maintain and enhance the CH₄-absorbing capacity of forest soils. This can be achieved through management practices that improve environmental conditions and increase soil fauna’s activity, such as those associated with thinning operations in overmature forest stands across various regions. This ecological manipulation through thinning practices promotes ground-level temperature increases and the activities of soil fauna, as well as maintaining aerobic conditions near the soil surface. Full article

Revitalisation of contaminated brownfield sites is essential for sustainable development, particularly near sensitive ecological areas like Natura 2000 sites. The lagoon in Slovenia’s Regional Park Šturmovci, an artificial wastewater convergence point created during hydroelectric construction, is a highly relevant example. This study integrates geochemical, mineralogical and isotopic analyses to identify sources and controlling mechanisms of contaminant distribution in lagoon sediments and assess their transfer to nearby agricultural soils during flooding events. Results indicate anaerobic conditions, with depth-related shifts in phosphorus, sulphur and redox-sensitive elements, such as rare earth elements (REE), arsenic (As), barium (Ba), cobalt (Co), chromium (Cr), lead (Pb) and vanadium (V), as well as fluctuations in pyrite-rich laminated layers, suggesting potential flood-driven remobilisation of trace elements. Lagoon sediments are highly contaminated with As (73 mg kg⁻¹), Ba (247 mg kg⁻¹), Pb (97 mg kg⁻¹) and Zn (1118 mg kg⁻¹), with elevated concentrations also observed in agricultural soil, all exceeding respective limit values of 20, 160, 85 and 200 mg kg⁻¹. Pollutant concentrations were highest near wastewater inflows and decreased with distance, with nitrogen isotopic patterns indicating partial nitrification and surface ammonium accumulation, reflecting intensive agricultural inputs in the area. High enrichment factor (EF > 20) and geoaccumulation index (I_geo > 3) values, in particular for As, Cd and Zn, indicated severe contamination and highlighted the urgent need for effective remediation strategies, including immobilisation using biochar or cement-based binders, as well as phytoremediation approaches. Full article

The recurrent influx of pelagic Sargassum spp. along Caribbean coastlines poses a significant environmental challenge while offering potential as a resource-recovery agricultural input. However, agricultural reuse of Sargassum biomass raises concerns regarding salinity and trace-metal distribution within the soil–plant–food continuum. This study evaluated the short-term elemental response to a Sargassum-Based Liquid Biofertilizer (SBLB) produced via controlled anaerobic fermentation, using tomato (Solanum lycopersicum L.) grown under greenhouse conditions. Raw biomass, fermented biofertilizer, irrigation water, soils, vegetative tissues, and fruits were chemically characterized. Elemental concentrations were quantified by ICP–OES and ICP-MS and treatment effects were analyzed using one-way and two-way ANOVA (p < 0.05). Anaerobic fermentation resulted in lower measured concentrations of sodium, arsenic, and selected trace elements in the liquid fraction relative to raw biomass. SBLB application increased soil macronutrient availability (N, P, K, Ca, Mg), while soil trace-metal concentrations remained within international reference ranges during the experimental period. Metals of concern (As, Cd, Pb, Ni, Cr) showed no detectable short-term enrichment in soils, vegetative tissues, or fruits relative to controls. In tomato fruits, arsenic, cadmium, and lead were below the limit of quantification across all treatments. Within the experimental timeframe, SBLB application was not associated with detectable trace-element accumulation in the soil–plant system. Long-term field studies and detailed soil physicochemical characterization are required to evaluate cumulative effects under repeated applications. Full article

European peatlands have been extensively drained for agriculture, resulting in substantial carbon losses and widespread soil degradation. Peatland restoration is therefore a global priority, with rewetting recognised as a key strategy for mitigating greenhouse gas emissions and climate change. This review synthesizes current knowledge on soil transformations following the rewetting of agriculturally drained peatlands in Europe. We describe major degradation processes induced by drainage, including land subsidence, organic matter oxidation, and microbial community shifts from anaerobic to aerobic conditions. We then examine key rewetting approaches—ditch blocking, controlled flooding, and paludiculture—and their intended restoration outcomes. Rewetting fundamentally alters soil physical, chemical, and biological properties by raising and stabilizing water tables, restoring anoxic conditions, and modifying nutrient cycling and microbial processes. Findings indicate long-term stabilization of organic carbon in peat soils under anaerobic conditions, but also reveal trade-offs between reduced CO₂ emissions and increased CH₄ and N₂O fluxes. Vegetation–soil interactions strongly influence recovery trajectories, and paludiculture offers potential to align agricultural land use with climate mitigation objectives. Finally, we evaluate current research methodologies and identify major knowledge gaps, including limited long-term data and insufficient integration of hydrological, chemical, and biological processes. We highlight priorities for future research to support evidence-based rewetting strategies that deliver climate benefits while maintaining ecological and economic sustainability in European peatlands. Full article