Formation Of Humic Acids Research Articles

Roles of oxygen and Mn (IV) oxide in abiotic formation of humic substances by oxidative polymerization of polyphenol and amino acid

Abstract The metal oxide-facilitated transformation of polyphenols and amino acids to humic substances (HS) is an essential process in soil and compost maturing processes. The objective of this research was to examine the specific roles of MnO2 and O2 in the formation of HS by oxidative polymerization of catechin (a polyphenol) and glycine (an amino acid). The results demonstrated that large amounts of fulvic acid (FA) and humic acid (HA) only formed in the presence of O2, while the presence of both O2 and MnO2 significantly enhanced HA formation, demonstrating their synergistic effects. The size of HA only increased in the presence of MnO2, but MnO2 without O2 was unable to convert FA to HA. Two-dimensional correlation spectroscopy results suggested that the sequence of the formation of HA functional groups was: C–OH in carboxylic acids >C–O in phenolic-OH > amide II and aromatic C–C > amide and carboxylate C=O > COO− >NH > hydrogen bond. Finally, XPS spectra of the MnO2 before and after the reaction showed that the Mn(IV) content decreased from >99% to 89.98% and 80.89% while the Mn(III) content increased from

Novel use of calcareous algae as a plant biostimulant

This work is based on the hypothesis that the depositions of the calcareous alga Lithothamnium sp. at the bottom of the ocean contain bioactive humic substances which may promote plant growth. To achieve this, micronized Lithothamnium sp. powder was investigated in terms of the degree of humification using a colorimetric approach; the bioactivity in comparison with that of auxin IAA (3-indole acetic acid) using a bioassay with Vigna radiata and the effect of foliar sprays on organically grown tomatoes. Humification and formation of humic acid were identified to a high degree in micronized Lithothamnium sp., which was highly bioactive showing auxin hormone-like activity. When applied as foliar sprays, rooting, growth, and yield were improved and concentrations of amino acids, sugars, and protein of tomato plants increased. Thus, the results presented a novel use for Lithothamnium sp., whereby the calcareous algae depositions provided a highly active humic acid for use as a plant biostimulant.

Identifying the action ways of function materials in catalyzing organic waste transformation into humus during chicken manure composting

The aim of this study is to detect the action properties of functional materials (FM) in transforming waste into resource products with high humus content. FM (MnO2 and reducing sugar) were added in different periods of chicken manure composting. During composting, concentration of humic acids (HA) as aromatic fraction of humus, was increased by FM. The promotive effects of adding FM in later period was the most obvious. While adding FM in the beginning period could accelerate organic matter degradation, but it did not promote HA formation. Meanwhile, the microbial diversity was higher in groups by adding FM in the beginning and thermophilic periods. Therefore, it was speculated that FM might improve HA formation by promoting the abiotic polymerization of precursors. Eventually, structural equation model showed that FM was beneficial to abiotic pathway of HA formation. But the formation efficiency was reduced by interfering with biotic pathway.

Hyperthermophilic composting of sewage sludge accelerates humic acid formation: Elemental and spectroscopic evidence

Application of thermophilic composting (TC) is limited due to poor efficiency and long composting period. Hyperthermophilic composting (HTC) could effectively overcome this defect. Here, the transformation of humic acid (HA) in both HTC and TC was characterized and compared to investigate the roles of HTC toward accelerating the formation of HA. In HTC, the highest temperature was 96.6 °C, and the hyperthermophilic and thermophilic phases exceed 18 days. The degree of polymerization (DP) in HTC increased to 1.27 on day 27, while it only increased to 1.15 at the end of TC. The elemental composition of the HA in HTC showed higher O atomic content (36.3%) and lower C/N atomic ratio (6.5) compared with TC. These changes indicated that HTC could significantly accelerate oxidized and polycondensed reactions for HA formation, which resulted in the shortening of composting period to 27 days. The maximum fluorescence intensity (Fmax) of humic-like components were achieved faster in HTC (Fmax = 1649.9) than in TC (Fmax = 1316.9), implying that HTC promoted the polycondensation of small molecular components to form HA with larger molecular weight and higher degree of aromatization. Two-dimensional FTIR correlation spectroscopy (2D-FTIR-COS) analysis demonstrated that HTC prevented the HA precursor from condensing before it was deeply oxidized, and increased the content of small molecules rich in carboxyl moieties. Based on the evolution of the molecular structure of HA, the level of oxidation of HA precursors was a key factor to determine the degree of polymerization and the degree of HA humification.

Characterisation of humic acids in fen peat

Fens store significant amounts of organic matter and thus are of high importance from the perspective of the organic carbon biogeochemical cycle. Fen peat comprises moderately to highly decomposed higher plant remains with relatively high mineral matter content. Humic acids form the major part of fen peat organic matter; they are also the most refractory and recalcitrant natural substances to degradation, and thus they contain essential information regarding mire and peat development over large periods of time as well as the organic carbon biogeochemical cycle. Moreover, humic substances in fen peat are a prospective resource for applications in agriculture and other sectors. The aim of this study was to comparatively study properties of humic acids isolated from fen peat of varied botanical compositions and origins and to compare the impact of the precursor biological material on properties of the humification process and the resulting humic acids. The formation of humic acids of varied origins shows similarities; however, at the same time, differences can be found in the further development of humic acids, depending on the environment in which they are present.

Restraint of enzymolysis and photolysis of organic phosphorus and pyrophosphate using synthetic zeolite with humic acid and lanthanum

Although phosphorus (P)-removing materials have been widely used to immobilize orthophosphate in aquatic ecosystems, the immobilization of organic phosphorus (OP) and pyrophosphate (PP) remains unclear. In this study, a unique OP/PP-immobilizing synthetic zeolite loaded with humic acid (HA) and La(OH)3 nanorod composite (ZHLA) is synthesized, and OP/PP-immobilization is examined by means of enzymolysis and photolysis. The results indicate that OP and PP could not be photodegraded into PO43− under natural conditions. Although OP could be degraded into PO43− by enhanced Fenton’s reagent, La3+ and HA could protect OP and PP from degradation. As a result of the colloidal coagulation and photocatalysis of La(OH)3, the activity of phosphatase could be reduced. The PP and phytate become resistant to enzymolysis through the formation of stable HA–La–PP/phytate or La–PP/phytate chelates. However, labile monoester phosphate could not form stable chelates resisting to enzymolysis. This labile monoester phosphate is hydrolyzed into PO43− and thereafter immobilized by ZHLA, which is the main pathway to achieve permanent immobilization. Most release-sensitive P fractions are transferred to the stable P fraction after ZHLA application. The ZHLA is demonstrated to be an economical and effective P-immobilization material and has high potential as a commercial sediment-capping product for eutrophication control.

POSSIBILITIES OF PURIFICATION OF HEAVY METALS CONTAMINATION IN SOILS


 
 
 Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals.
 
 

Pertumbuhan Dan Kandungan Vitamin C Tanaman Kangkung Darat (Ipomoea reptans Poir) Pada Media Zeolit Dengan Penambahan Asam Humat

Kangkung darat (Ipomoea reptans Poir) merupakan sayuran yang paling digemari oleh masyarakat selain memiliki kandungan gizi yang baik dan salah satu sumber vitamin C selain buah-buahan. Vitamin C merupakan antioksidan yang dibutuhkan oleh tubuh manusia untuk menjaga daya tahan tubuh dari efek buruk radikal bebas. Pemberian bahan organik berupa asam humat yang memiliki struktur molekul kompleks dengan berat molekul tinggi dan mengandung gugus aktif dapat meningkatkan pertumbuhan dan produktivitas tanaman. Untuk meningkatkan keterediaan unsur hara diperlukan bahan pembawa (carrier) berupa zeolit. Zeolit merupakan mineral silikat yang memiliki kapasitas tukar kation (KTK) yang sangat tinggi (bervariasi antara 80-180 meq/100g). Pemberian bahan humat dengan carrier zeolit diharapkan dapat meningkatkan produksi tanaman pangan seperti tanaman jagung. Penelitian ini bertujuan untuk mengetahui pengaruh asam humat dengan media tanam zeolit terhadap pertumbuhan dan kandungan vitamin C pada tanaman kangkung darat dan untuk menentukan konsentrasi asam humat yang paling berpengaruh terhadap pertumbuhan dan kandungan vitamin C pada tanaman kangkung darat. Penelitian dilaksanakan di Laboratorium Fisiologi Tumbuhan dan Greenhouse, Fakultas Biologi Universitas Jenderal Soedirman, Purwokerto dengan menggunakan metode eksperimental. Penelitian ini dilaksanakan dari Januari 2019 hingga Maret 2019 dengan menggunakan rancangan percobaan yaitu Rancangan Acak Lengkap (RAL). Parameter yang diamati pada penelitian ini adalah jumlah daun, berat basah tanaman, berat kering tanaman, dan kandungan vitamin C. Data dianalisis dengan analisis ragam pada taraf kepercayaan 95% dan 99%, dan dilanjutkan dengan analisis BNT pada taraf kepercayaan 95%. Hasil penelitian menunjukkan bahwa pemberian asam humat dengan konsentrasi 4 g.kg-1 pada media tanam zeolit dapat meningkatkan pertumbuhan tanaman kangkung darat, dan pemberian asam humat pada media tanam zeolit tidak dapat meningkatkan kandungan vitamin C kangkung darat.

Participation of cadmium (ll) and copper (ll) ions in intermolecular forces of humic acids in solutions

Using membrane ultrafiltration and size exclusion chromatography (SEC), the effect of Cd (II) and Cu (II) ions on the molecular weight distribution of humic acids (HA) in solution was investigated. It was shown that Cu (II) ions, unlike Cd (II), can take part in the formation of supramolecular HA associates (> 10 kDa).

Driving effects of minerals on humic acid formation during chicken manure composting: Emphasis on the carrier role of bacterial community

This work was aimed to determine the effects of different minerals on humic acid (HA) formation. Minerals can stimulate the formation of complex compounds, however, whether they can promote the conversion of complex compounds to HA has not been verified. Four treatments were setup from chicken manure mixed with rice hull and then added biochar (BC), montmorillonite (MMT) and biochar combined with montmorillonite (BC-MMT) for composting, while the control check (CK) was composted without minerals. The results showed that HA concentration was increased by 28.09%, 40.79%, 45.39% and 38.96% during CK, BC, BC-MMT and MMT composting. However, the bacterial community was the main reason for affecting HA concentration. Network analysis showed that obligate and facultative core microbes drove HA formation, and these driving effects were affected by minerals. Therefore, the core bacterial community promoted HA formation, which provided an insightful method to improve HA production.

Molecular and elemental composition of humic acids isolated from selected soils of the Russian Arctic

Humic substances, isolated from selected soils of the Russian Arctic, were investigated in terms of molecular composition and stabilization rate. The degree of polar soil organic matter stabilization was assessed with the use of modern instrumental spectroscopy methods. The analysis of humic acid (HAs) preparations showed that aliphatic fragments prevail in the organic matter isolated in polar soils. The predominance of aliphatic fragments was revealed in HAs from soils located in the coastal zone, which could be caused by regular refreshment of organic matter during sin-lithogenic process and processes of hydrogenation in HAs. Breaking of the C-C bonds and formation of chains with a high hydrogen content, which leads to the formation of aliphatic fragments in HAs, were noted. Data on the calculated atomic ratios of the elements in HAs are given and graphs show the main regularities in the formation of HAs and their properties. The integrated indicators of the molecular composition of humic acids of soils of the Russian Arctic are presented. The paper contains 4 Tables, 4 Figures and 44 References.

Effects of exogenous protein-like precursors on humification process during lignocellulose-like biomass composting: Amino acids as the key linker to promote humification process

The aim of this study is to assess the effectiveness of protein-like precursors addition on promoting humification process during lignocellulose-like biomass composting through adding amino acids to compost. The humification indexes of R1 and R2 was significantly higher than that of CK (P < 0.05). The decreasing ratio of Maillard precursor concentration of R2 and R1 was higher than CK. Amino acids addition affected the bacteria community and environmental factors during composting. Variance partitioning analysis showed that humification process was strengthened with environmental factors, bacteria community, Maillard precursors. Structural equation model (SEM) analysis showed that amino acids had substantial impact on promoting humic acid (HA) formation. The combined application of protein-like wastes and lignocellulose-like wastes was suggested to improve carbon sequestration. This study lays a foundation for economically and effectively managing different types of straws by composting.

Study of the morphological changes of copper and zinc during pig manure composting with addition of biochar and a microbial agent

Intensive and unregulated use of feed additives in China has led to high levels of heavy metals such as copper and zinc in fertilizers, considerable quantities of which find their way into the environment. Studies have shown that composting could significantly decrease the bioavailability of heavy metals. This study was to investigate the effects of addition of biochar and a microbial agent on the morphological changes in copper and zinc during composting. Results show that treatment T8 successfully immobilized 70.36% of copper as a result of biochar addition. Treatment T3 successfully immobilized 40.76% of zinc; transformation of zinc to a higher stable state was found to be closely related to the formation of fulvic and humic acids. Results of fluorescence spectrum analysis also corroborate that the conversion of copper and zinc to forms with higher stability was associated with the formation of fulvic and humic acid-like substances.

Influence of Ligneous Bulking Agents on the Complexation of Heavy Metals to Humic Substances Formed in Pig Manure Composting.

In order to investigate the influence of different lignin sources on humic substance formation during composting, this study selected two lignin sources, including wood sawdust and maize straw, to be co-composted with pig manure. Humic substances (HS) were characterized based on their fluorescence characteristics and complexing behaviors with heavy metals. The results showed that lignin sources, especially wood sawdust, were more conducive in promoting the formation of humic acids (HAs) than inorganic matter. The fluorescence excitation-emission matrix spectra also proved the positive effects of lignin on the formation of HAs during the humification process. The binding capacities of HAs isolated from mature composts for Cu and Cd followed the order of WS-90 > MS-90 > I-90, indicating that organic bulking agents are superior at increasing the complexing capacity of HAs. This finding suggests that the co-composting of pig manure with ligneous bulking agents is more advantageous at reducing the environmental risk of heavy metals.

Effect of Novel Pretreatment of Steam Explosion Associated with Ammonium Sulfite Process on Enzymatic Hydrolysis of Corn Straw.

Effective pretreatment process to improve enzymatic saccharification and decrease inhibitors generation is a key operation involved in the lignocellulosic bioconversion. The pretreatment of steam explosion associated with ammonium sulfite (SEAS) process was carried out to investigate the effect on enzymatic hydrolysis and fermentation production as a combinatorial pretreatment. Results showed that after pretreatment (1.0MPa, 30min, 20%w/w ammonium sulfite added), the phenolic inhibitors derived from lignin significantly removed (37.8%), which transformed to chemical humic acid (humic acid and fulvic acid) mostly. Sugar conversion (glucan (77.8%) and xylan (73.3%)) and ethanol concentration (40.8g/L) of combinatorial pretreated samples were increased by 24.7% and 33.8%, respectively, compared with steam explosion (SE) pretreated samples. FT-IR and elemental analysis results indicated that the lignin structure changed and aromatization degree increased after SEAS pretreatment. In addition, the ratio of C/N decreased and compost maturity degree increased with the holding time. The effect on the growth of wheat seedlings of soluble fulvic acid solution from combinatorial pretreatment was investigated, where below 1% (w/w) concentration did contribute to growth. Therefore, one-step chemical pretreatment process could be provided for inhibitors removal, enzymatic saccharification increase, and chemical humic acid formation as well.

Humic acid formation during subcritical water extraction of food by-products using accelerated solvent extractor

In this study, the effect of extraction temperature (180 and 200°C), static extraction time (15, 30 and 45min) and sample amount (5 and 10g) on humic acid formation during subcritical water extraction of food by-products by accelerated solvent extractor was investigated. Subcritical water extraction was carried out with three food by-products as flaxseed meal, lemon peel and mandarin peel at constant pressure of 1500psi. The highest total humic acids were found as 71.73, 64.52 and 62.91% in the solid residue of flaxseed meal, mandarin peel and lemon peel after subcritical water extraction at 200°C and 15min, respectively. Besides, the highest free humic acids were determined as 60.62, 52.60 and 50.64% in the ;solid residue of flaxseed meal, mandarin peel and lemon peel after subcritical water extraction at 200°C and 15min, respectively. The study results suggested that accelerated solvent extractor has a great potential as green technology to produce humic acids during subcritical water extraction of food by-products.

Effect of MnO2 on biotic and abiotic pathways of humic-like substance formation during composting of different raw materials

The humic-like substances (HLS) are proposed to be formed by biotic and abiotic pathways. The abiotic pathways were neglected in existed composting studies. The present study aims to accelerate the abiotic pathways, and to investigate how MnO2 drives the HLS transformation via changing the contribution of abiotic and biotic pathways during composting with different materials. Parallel factor analysis model (PARAFAC), hetero two-dimensional correlation spectra (hetero-2DCOS) and variance partitioning were used to identify the effects of MnO2 on the formation of humic acid (HA) and fluvic acid (FA) during composting of chicken manure (CM) and corn straw (CS). The addition of MnO2 could change the structures of HLS during CS and CM composting, mainly promoting the formation of complex components in HA and FA during CS composting, as well as the complex components of FA during CM composting. Meanwhile, the addition of MnO2 could reshape the microbial ecology, which enhanced the correlation between microbes and complex components formation during composting, especially in CM composting. Variance partitioning showed that both abiotic and biotic pathways were stimulated in conversion of HLS components after adding MnO2 during CS composting, especially for the abiotic pathways. During CM composting, the MnO2 promoted biotic effects on the conversion of HLS components. Above all, the addition of MnO2 could stimulate pathways of biotic, abiotic or both of them to improve the humification degree of HLS by changing microbial ecology, which could be a promising way for promoting the application value of composting products.

Soil organic matter alteration under biochar amendment: study in the incubation experiment on the Podzol soils of the Leningrad region (Russia)

Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM. The incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques. We found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself. The influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes.

Carbon input and the structural quality of soil organic matter as a function of agricultural management in a tropical climate region of Brazil

Carbon (C) stabilization and the quality of soil organic matter (SOM) in a tropical climate are key aspects regulating carbon dioxide emissions and maintaining the C cycle. Soil management influences the accumulation of C, regulating the balance between mineralization and/or the humification of SOM. This study aimed to quantify inputs of different chemical forms of C into soil and to evaluate the structural chemical characteristics of humified SOM. Four management systems were established: Forest (F), Pasture (P), Conventional tillage (T), and No-tillage (NT). Total organic carbon (TOC) and nitrogen (TN) by depth, chemical forms of organic matter input, and spectroscopic characterization of SOM in the form of humic acids (HA) were analyzed. The results obtaining by PCA-13C NMR show that the forest accumulated a high amount of C on the surface (surpassing 20 Mg ha−1), favoring the formation of aliphatic HA (CAlkyl-H,R; CAlkyl-O,N; CAlkyl-O). In the NT management that increases biomass in the soil (14 Mg ha−1), the mineralization process occurred to a greater extent, allowing HA to form with a predominance of aromatic structures (CArm-H,R and CArm-O,N). The PCA-FTIR analysis showed that the P system contributed to the formation of similar HA to those under F management. The T management system incorporated the least TOC and TN, with different HA types being formed in these soils than what was found in other managements. Thus, minimally managed and more stabilized systems in tropical climates form HA of structural and compositional similarity, regardless of the nature of C (C3 or C4). In contrast, soils subjected to agricultural uses that promote higher or lower C inputs, form HA that are structurally different from P and F. This study demonstrates the need for developing experiments for model building to elucidate the relationships among C input, management type, and the formation of humic substances.

Enhanced biotic contributions to the dechlorination of pentachlorophenol by humus respiration from different compostable environments

Humic-reducing microorganisms (HRMs) can utilize humic substances as electron shuttles to transform contaminants in different environments. Composts as organic agents contain large amount of humic acids (HA), and the formation of HA can support the growth of HRMs during composting. However, the effects of HRMs from different compostable environments on pentachlorophenol (PCP) dechlorination via corresponding composting-formed HA remain unknown. In this study, HA extracted from protein-, lignocellulose-, and lignin-rich composts, were examined in the corresponding HRM-mediated reductive dechlorination of PCP. Results showed that PCP could be dechlorinated by HRMs from different composts, and the highest rates were observed in HRMs derived from protein-rich composts. The addition of HA influenced the microbial degradation efficiency but did not change the PCP dechlorination pathway. HA extracted from lignocellulose- and lignin-rich composts could act as electron shuttles to enhance HRM-mediated reductive dechlorination of PCP. Nine HRMs that significantly influenced ortho-dechlorination and trichlorophenol transformation were selected on the basis of the relationships between key HRMs and intermediates. Consequently, understanding the relationships between key HRMs and environmental factors could give insight into mechanisms of microbially reductive transformation of PCP by composts in the chlorophenol-contaminated environments.