Search Results (127)

Humic substances, which include humic acid and fulvic acid, are natural biopolymers formed from the decomposition of organic matter. There is growing interest in them because of their diverse potential in the biomedical field. Their complex structures, rich in various functional groups, provide antioxidant, anti-inflammatory, antimicrobial, antiviral, and immunomodulatory properties. Recent studies demonstrate that humic substances can scavenge reactive oxygen species, modulate cytokine production, inhibit viral fusion, promote wound healing, and enhance gut microbiota balance. Humic acid and fulvic acid also exhibit anticancer activity by inducing apoptosis in tumor cells, while protecting healthy tissues from oxidative stress. Furthermore, their chelating capacity underlies detoxifying activity and heavy metal binding effects. Despite promising research, variability in composition and potential cytotoxicity under certain conditions emphasize the need for standardized extraction methods and rigorous preclinical evaluation. This review offers a comprehensive overview of the biological effects of humic substances, exploring the mechanisms behind their actions and their potential biomedical applications. It highlights both the benefits and the limitations associated with their use in drug delivery systems. Full article

Long-term cultivation practices, in which mineral fertilizers are the only amendments made to crop-supporting soils, are giving rise to the degradation of soil structures in the world’s most fertile soils. This leads to erosion and to the loss of productivity and may well become a greater threat than that of global warming. Humic substances (structurally related compounds), and humin (which no longer falls within the modern definitions of humic substances), are major transformation or humification components of organic matter entering the soil, with varying resistance to biological degradation, and properties vastly contributing to soil fertility. There is considerable discussion on the macromolecular structures arising from associations or supramolecular structuring of some components of humic substances. The compositions, structures, shapes, sizes, and surface properties of these molecular components determine their intra- and inter-molecular associations, their interactions with the soil particles, and particularly with the soil inorganic colloids. Such interactions play a vital role in soil aggregates’ formation, which is important for soil health and productivity. In this work, an outline is given of modern methods for the isolation of broadly defined soil organic components, of what is known of their origins (plant or microbial), compositions, sizes and shapes, of how they interact to promote soil structure and productivity, and how the materials composing the hydrophobic fraction form strong associations with the inorganic colloids. A better understanding should be sought of how these interactions and associations take place giving rise to the structured systems that are characteristic of fertile soils. Full article

The EU’s Circular Economy Action Plan promotes the use of organic waste as fertilizer, thus allowing the recycling of nutrients in the agricultural system. Research on the agronomic reuse of composted substrates previously employed for mushroom cultivation remains limited, despite their rich content of plant residues and fungal biomass, which could be repurposed as soil amendments under suitable conditions. This study evaluated the agronomic potential of spent mushroom substrates from Agaricus bisporus and Pleurotus ostreatus, including recomposted A. bisporus residues. A range of analytical procedures was employed to assess their suitability for soil improvement and the formation of humic-like substances, including physical, chemical, microbiological, phytotoxicity, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses. The spent Pleurotus substrate exhibited low nutrient content (1.1% N, negligible P, 0.9% K), but high water retention (820 kg water Mg⁻¹) and 48% organic carbon (OC), indicating its potential as a soil amendment or seedling substrate. In contrast, spent and composted Agaricus substrates showed moderate nutrient content (1.8–2.7% N; 0.8–0.7% P and 1.3–1.8% K), appropriate C/N ratios (10–15), and sufficient OC levels (24–30%), supporting their use as fertilizers. However, elevated salinity levels (18–23 dS m⁻¹) may restrict their application for salt-sensitive crops. No significant phytotoxic effects on seed germination were observed, and microbiological analyses confirmed the absence of Salmonella spp. in the three substrates. Py-GC/MS revealed a humic acid-like fraction comprising altered lignin structures enriched with lipid and nitrogen compounds. Overall, the studied materials demonstrate promising agronomic value and the capacity to contribute to long-term soil carbon storage. Full article

This study aims to evaluate eco-innovative solutions in the fertilizer industry that allow for waste valorization in the context of a resource-efficient circular economy. A comprehensive reuse strategy was developed for low-rank peat and post-cultivation horticultural mineral wool, involving the extraction of valuable humic substances from peat and residual nutrients from used mineral wool, followed by the use of both post-extraction residues to produce organic–mineral substrates. The resulting products/semifinished products were characterized in terms of their composition and properties, which met the requirements necessary to obtain the admission of this type of product to the market in accordance with the Regulation of the Minister for Agriculture and Rural Development of 18 June 2008 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws No 119, item 765). Elemental analysis, FTIR spectroscopy, and solid-state CP-MAS ¹³C NMR spectroscopy suggest that post-extraction peat has a relatively condensed structure with a high C content (47.4%) and a reduced O/C atomic ratio and is rich in alkyl-like matter (63.2%) but devoid of some functional groups in favor of extracted fulvic acids. Therefore, it remains a valuable organic biowaste, which, in combination with post-extraction waste mineral wool in a ratio of 60:40 and possibly the addition of mineral nutrients, allows us to obtain a completely new substrate with a bulk density of 264 g/m³, a salinity of 7.8 g/dm³ and a pH of 5.3, with an appropriate content of heavy metals and with no impurities, meeting the requirements of this type of product. A liquid fertilizer based on an extract containing previously recovered nutrients also meets the criteria in terms of quality and content of impurities and can potentially be used as a fertilizing product suitable for agricultural crops. This study demonstrates a feasible pathway for transforming specific waste streams into valuable agricultural inputs, contributing to environmental protection and sustainable production. The production of a new liquid fertilizer using nutrients recovered from post-cultivation mineral wool and the preparation of an organic–mineral substrate using post-extraction solid residue is a rational strategy for recycling hard-to-biodegrade end-of-life products. Full article

Agriculture is one of the most important sectors of the global economy, but it increasingly faces sustainability challenges in meeting rising food demands. The intensive use of mineral fertilizers not only improves yields, but also causes negative environmental impacts such as increasing greenhouse gas emissions, water eutrophication, and soil degradation. To develop more sustainable solutions, the focus is on organic fertilizers, which are produced using waste and biostimulants such as amino acids. The aim of this study was to develop and characterize liquid nitrogen–calcium–magnesium fertilizers produced by decomposing dolomite with nitric acid followed by further processing and to enrich them with a powdered amino acid concentrate Naturamin-WSP and liquid extracts from digestate, a by-product of biogas production. Nutrient-rich extracts were obtained using water and potassium hydroxide solutions, with the latter proving more effective by yielding a higher organic carbon content (4495 ± 0.52 mg/L) and humic substances, which can improve soil structure. The produced fertilizers demonstrated favourable physical properties, including appropriate viscosity and density, as well as low crystallization temperatures (eutectic points from –3 to –34 °C), which are essential for storage and application in cold climates. These properties were achieved by adjusting the content of nitrogenous compounds and bioactive extracts. The results of the study show that liquid fertilizers enriched with organic matter can be an effective and more environmentally friendly alternative to mineral fertilizers, contributing to the development of the circular economy and sustainable agriculture. Full article

This article presents a review of several non-exclusive pathways for the sequestration of soil organic carbon, which can be classified into two large classical groups: the modification of plant and microbial macromolecules and the abiotic and microbial neoformation of humic substances. Classical studies have established a causal relationship between aromatic structures and the stability of soil humus (traditional hypotheses regarding lignin and aromatic microbial metabolites as primary precursors for soil organic matter). However, further evidence has emerged that underscores the significance of humification mechanisms based solely on aliphatics. The precursors may be carbohydrates, which may be transformed by the effects of fire or catalytic dehydration reactions in soil. Furthermore, humic-type structures may be formed through the condensation of unsaturated fatty acids or the alteration of aliphatic biomacromolecules, such as cutins, suberins, and non-hydrolysable plant polyesters. In addition to the intrinsic value of understanding the potential for carbon sequestration in diverse soil types, biogeochemical models of the carbon cycle necessitate the assessment of the total quantity, nature, provenance, and resilience of the sequestered organic matter. This emphasises the necessity of applying specific techniques to gain insights into their molecular structures. The application of appropriate analytical techniques to soil organic matter, including sequential chemolysis or thermal degradation combined with isotopic analysis and high-resolution mass spectrometry, derivative spectroscopy (visible and infrared), or ¹³C magnetic resonance after selective degradation, enables the simultaneous assessment of the concurrent biophysicochemical stabilisation mechanisms of C in soils. Full article

This study evaluated birch and oak ash extracts as alternative extractants for isolating humic substances (HSs) from peat and lignite. The effects of ultrasound intensity, extraction time, and temperature were optimized using a Box–Behnken design and validated statistically. The highest HSs yields were obtained from peat with oak ash extract (pH 13.18), compared to birch ash extract (pH 12.09). Optimal process parameters varied by variant, falling within 309–391 mW∙cm⁻², 116–142 min, and 67–79 °C. HSs extracted under optimal conditions were fractionated into humic acids (HAs) and fulvic acids (FAs), and then analyzed by elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance Spectroscopy (CP/MAS ¹³C NMR). The main differences in HSs quality were influenced by raw material and fraction type. However, the use of birch ash extract consistently resulted in a higher proportion of carboxylic structures across all fractions. Overall, wood ash extract, especially from oak, offers a sustainable and effective alternative to conventional extractants, particularly for HSs isolation from lignite. Notably, HSs yield from lignite with oak ash extract (29.13%) was only slightly lower than that achieved with 0.5 M NaOH (31.02%), highlighting its practical potential in environmentally friendly extraction technologies. Full article

Since water contamination has become a serious concern, more effective environmental remediation methods are required. Chitosan (CHT)-based adsorbents have demonstrated high efficacy in removing pollutants due to their unique chemical and structural properties. However, their utilization remains limited by low environmental stability and the absence of effective adsorption sites. The functional moieties of CHT can be altered to improve its performance via graft modification and crosslinking. Compared to conventional hydrogel synthesis techniques, ionizing radiation-induced fabrication, using gamma or electron-beam irradiation, offers a promising platform for innovation across diverse fields. The prime focus of this review is on ionizing radiation developed CHT-based hydrogels to remove toxic heavy metals, dyes, organic contaminants, radionuclides, and humic substances. The fabrication strategy, adsorption mechanism, and factors affecting the adsorption capacity of CHT-based hydrogels are presented. This review aims to underscore the transformative potential of ionizing radiation-induced CHT hydrogels in environmental remediation by examining current research trends and identifying future prospects. Full article

The interactions between dissolved organic matter (DOM) and agrochemicals (e.g., neonicotinoid insecticides, NIs) govern the distribution, migration, and potential environmental risks of agrochemicals. However, the long-term effects of agricultural management on the DOM components and structure, as well as their further influences on the interactions between DOM and agrochemicals, remain unclear. Here, spectroscopic techniques, including Fourier transform infrared spectroscopy, two-dimensional correlation spectroscopy, and three-dimensional excitation–emission matrix fluorescence spectroscopy were employed to delve into the interaction mechanism between the DOM from citrus orchards with distinct cultivation ages (10, 30, and 50 years) and imidacloprid, which is a type of pesticide widely used in agricultural production. The findings revealed that the composition and structure of soil DOM significantly change with increasing cultivation age, characterized by an increase in humic substances and the emergence of new organic components, indicating complex biodegradation and chemical transformation processes of soil organic matter. Imidacloprid primarily interacts with fulvic acid-like fractions of DOM, and its binding affinity decreases with increasing cultivation age. Additionally, the interactions of protein-like fractions with imidacloprid occur after humic-like fractions, suggesting differential binding behaviors among DOM fractions. These results demonstrate that cultivation age significantly influences the composition and structural characteristics of soil DOM in citrus orchards, subsequently affecting its sorption capacity to imidacloprid. This study enhances the understanding of imidacloprid’s environmental behavior and provides theoretical support for the environmental risk management of neonicotinoid pesticides. Full article

Calcareous soil poses challenges for crop production due to the limited availability of micronutrients in insoluble forms. This study evaluated various organic and biological treatments for managing deficiencies in iron, zinc, and manganese in artichoke (Cynara scolymus L.) grown in calcareous soil over two seasons (2023 and 2024). A randomized complete block design (RCBD) was employed, with 24 plots (5 × 8 m² each) receiving the following five treatments: mineral fertilizer, humic substances, ALCRI-anti chlorosis, ALCRI-vermicompost, and ALCRI-bio-help. Each treatment was replicated three times. In the 2023 season, significant increases in micronutrient levels were observed following the application of the organic and biological treatments, particularly ALCRI-vermicompost and humic substances. Compared to the control group, the iron content (Fe²⁺) increased by 57.1%, reaching 715.6%. Zinc (Zn²⁺) rose by 66.1% to 686.4%, while manganese (Mn²⁺) and copper (Cu²⁺) increased by 56.9% to 685.2% and 44.9% to 673.4%, respectively. These positive trends continued into the 2024 season, with Fe²⁺ showing even greater gains of 103.4%, peaking at 824.0% in the plots treated with the ALCRI-vermicompost and humic substances. Zn²⁺ and Mn²⁺ displayed more modest increases of 36.9% and 58.0%, while Cu²⁺ exhibited a remarkable rise of 50.7%, reaching 861.2%, particularly for the ALCRI-anti chlorosis treatments. The results indicate that the application of vermicompost fertilizer, alone or in combination with humic substances, significantly enhanced the soil structure, as confirmed by the SEM examination, which revealed increased porosity and improved aggregation. These consistent improvements over two seasons strongly support the effectiveness of organic and biological treatments in enriching soil with essential micronutrients. Full article

Microplastics (MPs) are ubiquitous in aquatic environments, soils, and beach sediments, demonstrating a remarkable ability to adsorb dissolved organic matter (DOM). Although there are methods for extracting DOM from water, the approaches for directly extracting DOM from microplastics have not been thoroughly investigated, and the characterization of DOM adsorbed on microplastics is also insufficient. In this study, five different types of microplastic samples were collected from each of five environmental media (water and sediment), and finally 25 samples were obtained. This paper comparatively assessed the extraction efficiency of DOM from MPs with various solvents by using total organic carbon (TOC), culminating in the development of a sodium pyrophosphate-NaOH solution extraction method optimized for DOM. The morphology, material and environmental medium of microplastics were the three primary factors affecting the adsorption of DOM on microplastics, with the highest enrichment ratio of 1.4–1.8 times for extruded polyethylene microplastics (EPE-MPs) characterized by their porous structure in the flowing water environment. The molecular weight of DOM adsorbed on microplastics showed a multi-modal distribution pattern with great dissimilarities among the different environmental media. Gel permeation chromatography (GPC) indicated that the weight-average molecular weight (M_w) of DOM was 2750–4552 Da for river MPs, 2760–5402 Da for Qiantang River MPs, 1233–5228 Da for East China Sea MPs, 440–7302 Da for soil sediment MPs and 438–6178 Da for beach sediment MPs, respectively. Excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) identified that tyrosine-like substances with high excitation in region IV and low excitation in region I were predominantly adsorbed on MPs, followed by tryptophan-like substances with low excitation in region II and protein-like substances in region IV, while humic- and fulvic-like substances in regions V and III, respectively, exhibited the least adsorption affinity. The findings underscored the critical need to comprehensively consider the interactions between MPs and DOM and their environmental impacts in pollution control strategies. Full article

The efficient characterization of compost quality is essential for optimizing its application in agriculture and soil improvement. In this study, a correlation-based approach was employed to evaluate relationships between physicochemical properties, structural features, and reactivity indicators of compost extracts—fulvic acid-like (FA-L), humic acid-like (HA-L), and dissolved organic matter (DOM)—and their respective bulk composts. The goal was to identify key compost parameters that can serve as reliable predictors of humic substance composition and bioactivity, thereby reducing reliance on labor-intensive humic substance extractions. A comprehensive set of elemental, spectroscopic (UV-vis, ATR-FTIR, ¹H-NMR), and thermal (TGA-DSC) analyses were conducted to assess the composition and stability of the extracts. Strong correlations were found between compost oxidation state (C_oxi/C), cation exchange capacity (CEC), thermal stability, and the structural characteristics of humic substances-like (HS-L) fractions, suggesting that direct compost characterization can effectively predict humic substance reactivity and agronomic potential. The findings also align with a previously developed Compost Quality Index (CQI), reinforcing the functional role of humic substances in soil fertility and nutrient retention. By establishing a simplified yet robust compost assessment framework, this study advances the potential for efficient, cost-effective evaluation methodologies for compost quality. Full article

The application of oxidation processes, including advanced oxidation, in water treatment is one of the effective methods for eliminating risks associated with the presence of organic substances in water and those formed during chlorination. This article presents the impact of advanced oxidation in the UV + O₃ process on the content and structure of organic substances present in three natural waters with different levels of total organic carbon (TOC). The process was carried out using low-pressure and medium-pressure lamps with an irradiation time of 40 min and ozone doses of 1.5 gO₃/m³ and 5 gO₃/m³. Advanced oxidation, regardless of the type of lamp used or the ozone dose, had the greatest effect on the content of humic acids, which underwent both transformation and mineralization. The use of a low-pressure lamp resulted in an increase in the content of organic substances with the lowest molecular weight (<0.7 kDa), whereas the medium-pressure lamp led to an increase in substances with a molecular weight >1.3 kDa. Regardless of the ozone dose and the type of lamp used, the transformation of organic substances dominated over mineralization, whose efficiency reached a maximum of 44.9% and 38.4% for the low-pressure and medium-pressure lamps, respectively. The degree of organic substance transformation and the efficiency of their removal were directly proportional to the TOC content in the raw water. The use of a low-pressure UV lamp ensured higher process efficiency, which is also associated with lower energy costs. Full article

The paper reviews the patent descriptions of methods for obtaining humic substances and the procedures used in their industrial production. Selected humus substances, obtained using three different methods, were also examined. In the first one, humic substances were obtained due to the hydrolytic-oxidative decomposition of lignosulfonate. The second one consists of alkaline extraction from brown coal. According to the third, humus substances were extracted from digested sewage sludge. In the obtained humus substances, molecular composition, inorganic impurities, IR spectrum, gravimetric analysis, and the % shares of fulvic and humic acids were determined. The physico-chemical properties of the tested substances were also assessed. Based on the study’s results, the advantages and disadvantages of the obtained humus substances were determined, and methods for their modification to improve utility values were provided. Research on humic substances is a very important issue, especially concerning improving soil management and developing sustainable agricultural practices. They are key in improving soil structure and increasing its capacity to retain water and essential nutrients such as N, P, K, S, Ca, and Mg. In addition, humic substances are an important store of carbon in soils, which is important in the context of climate change. Full article

The environmental release of zinc oxide nanoparticles (ZnO-NPs) may have consequences for ecosystems. The behavior and environmental effects of ZnO-NPs could change due to their interactions with other existing substances. This research explored how the presence of coexisting organic pollutants (like tetrabromobisphenol-A (TBBPA)), electrolytes (such as NaCl and CaCl₂), natural organic materials (including humic acid (HA)), and bovine serum albumin (BSA) in simulated water affected the behavior of ZnO-NPs. Various characterization techniques were used to analyze the size, shape, purity, crystallinity, and surface charge of ZnO-NPs following interactions (after one day, one week, two weeks, and three weeks) at pH 7. The findings demonstrated changes in both the size and zeta potential of the ZnO-NPs in isolation and when TBBPA and electrolytes were included in the suspension. The size and surface charge exhibited different variations across fixed concentrations (5 mM) of various electrolytes. HA and BSA contributed to the dispersion of ZnO-NPs by affecting the zeta potential. These dispersion effects were also observed in the presence of TBBPA and salts, attributed to their substantial aliphatic carbon content and complex structures. Potential interaction forces that could explain the adsorption of TBBPA include cation bridging, hydrophobic interactions, hydrogen bonding, electrostatic interactions, and van der Waals forces. The co-occurrence of organic pollutants (TBBPA) and natural organic compounds (HA and BSA) can alter the surface properties and behavior of ZnO-NPs in natural and seawater, aiding in the understanding of the fate and impact of engineered nanoparticles (such as ZnO-NPs) in the environment. Full article