Formation Of Humic Acids Research Articles

Geochemistry and sedimentology of tropical mangrove sediments along the southwest coast of Sri Lanka: Fingerprints for development history of wetlands

Tropical wetlands are one of the major terrestrial carbon sinks during the Holocene. However, there is considerable uncertainty in the development history of tropical wetlands in different geographical regions. In this study, the main objective was to synthesize the formation history of mangrove wetlands along the southwest coast of Sri Lanka in terms of past sea-level records in the region. Sedimentological observations were determined using representative sediment cores at Telwatta. Geochemical characteristics of sediment cores were determined using δ13C and δ15N stable isotopes, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The chronology was obtained using accelerated mass spectrometry 14C data for fossil coral samples. Black color fine to medium-grained core sediments can be identified as H3/H4 levels of decomposition based on the modified Von Post classification. This study identified that organic-rich sediment accumulation was initiated over the basal/inland coral deposits, any time after middle Holocene sea-level highstands. In this study, paleo sea-level indicator (i.e., basal coral in present-day land area) suggests that sea-level was about 1–2 m higher than present during ca. 5500 Cal year B.P. Heavy rainfall on the southwestern slopes also promotes the preservation of organic-rich sediments with seasonal flooding. The temporal variations of organic matter and carbonate contents suggest that there are no clear facies variations in this sedimentary succession. XRD analysis identified clay minerals such as montmorillonite and illite, and it indicates the deposition of sediments from a near distance or in situ source materials due to reinforced physical erosion. Stable isotopic values (δ13C = –27.18‰ to –26.46‰ and δ15N = 6.64‰ to 8.01‰) reflect the mixing of freshwater sources (i.e., dissolved organic carbon and nitrate) to C3 terrestrial plants dominant sediments. The humification index based on FTIR results (aromatic C=C and asymmetric COO- group vibrations to polysaccharides (1630/1053 cm −1)) suggests a depleted level for decarboxylation below ∼30 cm. The ratio of carboxyl C=O and aromatic ester group vibrations to polysaccharides (1720/1053 cm −1) also shows similar variations with the humification index. Looking forward, the 1720/1053 cm −1 ratio can be proposed as a possible geochemical proxy for determining the degree of formation of humic acids in organic-rich sediments.

Identifying driving factors of humic acid formation during rice straw composting based on Fenton pretreatment with bacterial inoculation

The aims of this study were to identify the driving factors of humic acid (HA) during rice straw composting based on Fenton pretreatment with bacterial inoculation. Rice straw was pretreated by Fenton reactions and then inoculated during composting, which was set up CK (control), FeW (Fenton pretreatment) and FeWI (Fenton pretreatment + functional bacterial agents). Results indicated that Fenton pretreatment and inoculation of functional bacteria increased the concentration of HA components, which was due to that bacterial composition was changed and bacterial diversity was decreased. Moreover, Fenton pretreatment and inoculation of functional bacteria increased the bacterial amounts of shikimic acid metabolism genes and the correlation between HA components and shikimic acid metabolism genes. Therefore, the functional bacteria were core driving factors, and NH4--N, pH, cellulose and bacterial diversity as key environmental factors to promote the formation of HA components.

Specified Dosages of Biochar Application Not Impact Native Organic Carbon but Promote a Positive Effect on Native Humic Acid in Humicryepts Soil

Biochar is considered to have potential use in carbon (C) sequestration and has been widely used in soil amendment. Humic substances (HSs), assigned as the stable organic C, have obvious agronomic benefits. However, the response mechanisms of these carbonaceous substances to biochar are unclear in biochar-amended soils. In a two-year experiment, the δ13C technique was employed to trace the fate of the biochar-derived C in HSs and evaluate the effects of four treatments, including no biochar control (CK) and biochar addition at dosages of 6 t ha−1 (BC6), 12 t ha−1 (BC12), and 24 t ha−1 soil (BC24), on soil organic carbon (SOC) and HSs. Compared to CK, biochar application significantly improved total SOC contents and the C pool index, whereas the C labile index declined. Humic acid (HA) and humin were distinctly enhanced in bulk soil. Moreover, the aliphaticity was intensified in the chemical composition of HA. In particular, native HA contents substantially increased by 16.30–55.95%. Biochar-applied C of 4.08–6.43% was finitely involved in HA formation over the two years, which resulted in a genetic relationship between soil HA and biochar to some extent. The low dosages of biochar at 6 t ha−1, 12 t ha−1 and 24 t ha−1 did not obviously affect native SOC contents. Moreover, BC24 had less of an effect on HA formation compared to BC6 and BC12, but had the highest SOC. These results demonstrate that biochar application can improve SOC stocks, reduce C instability and promote HSs formation, and they suggest that determining and keeping an optimum dosage of biochar application can represent an effective strategy (i.e., not only sequestrate C, but also improve soil quality), which is beneficial to sustainability in the ecological environment and agriculture.

BIOREMEDIATION OF SOILS CONTAMINATED WITH HEAVY METALS

Waste generated due to the growth of the modern industry is undergoing natural disposal in the environment for a long period of time. A special danger is caused by heavy metals that do not undergo biodegradation. Known purification methods of soils are not always effective and profitable. Correct selection of soil remediation methods contaminated with heavy metals ensures effective cleaning and restoration of soils. For this purpose, selecting representatives of various taxonomic groups of microorganisms binding heavy metals in the soil is carrying out. A complex method of purification of soils contaminated with have metals is being developed. Modified forms of humic acids were developed, geochemical barriers using local clays were created. Works to biostimulate local microorganisms required for bioremediation of soils contaminated with heavy metals are conducted. Remediation and increasing the fertility of soils contaminated with heavy metals are necessary for the prevention of further penetration of these metals into agricultural crops.

Protein-derived structures determines the redox capacity of humic acids formed during hyperthermophilic composting

Humic acid (HA) in compost has received widespread attention for its high redox activity, which can mediate the degradation of organic pollution and the passivation of heavy metals in the environment. Hyperthermophilic composting (HTC) can accelerate HA formation. However, few studies have examined whether and how the structures of different organics affect the formation of the HA and HA redox structure at the molecular level in HTC. Detailed molecular information and the redox capacity (electron transfer capacity, ETC) of HA in HTC and thermophilic composting (TC) were characterized using pyrolysis gas chromatography/mass spectrometry and the electrochemical method, respectively. HTC promoted the formation of redox structure, leading to the improvement of the ETC of HA. Aromatics and N-containing compounds were mainly derived from protein components, and the rate at which they were transferred into HA was accelerated in HTC, while the relative abundance of lipids decreased. Partial least squares regression and correlation analysis demonstrated that protein-derived compounds were the key factor determining the HA redox capacity. Finally, partial least squares path modeling suggested that the influence mechanism of protein-derived structures on HA redox capacity might differ in HTC and TC. HTC may promote the relative abundance of N-containing components into the C-skeleton and accelerate the accumulation of the aromatic products, thereby improve the HA redox capacity. These findings provided new insight into how the redox capacity of the HA in compost could be improved and how compost products could be prepared for use in environmental remediation.

An electric field immobilizes heavy metals through promoting combination with humic substances during composting

The aim of this study was to explore a novel method to immobilize heavy metals (HM) in composting through increasing the combination of these with humic substances. An electric-field assistant technique was applied to strengthen biomass biodegradation and assess the impact on the humification process and HM immobilization in composting. Results demonstrated that the application of an electric field enriched bacterial abundance and enhanced bacterial metabolism. Humic substance and humic acid (HA) contents in compost product were significantly increased by 19 and 69%, respectively. The HA-complexed Cu, Zn, As, Cd contents were increased by 34, 41, 29 and 135.1%, respectively, which was attributed to the promotion of HA formation since a positive correlation between HA and HA-complexed HM (R2 = 0.60–0.87) was established. The evidence presented here supports the future development of electric field implementation as an intrinsic bioremediation technique for HM immobilization.

The action difference of metabolic regulators on carbon conversion during different agricultural organic wastes composting

The purpose of this study is to explore the action characteristics of metabolic regulators like adenosine tri-phosphate (ATP) and malonic acid (MA) during rice straw (RS) and fruit and vegetable waste (FVW) composting. Results showed that due to the easy degradation difference, ATP and MA reduced CO2 emission in RS and FVW, respectively. Moreover, adding ATP and MA increased humic acids (HA) content in FVW more significantly (p < 0.05), especially for ATP. However, adding MA accelerated organic matter degradation during RS composting, which was basically consistent with CO2 emission, but it was not effective in promoting HA formation. Furthermore, the microbial community was reshaped by adding ATP and MA. Eventually, structural equation model further confirmed that adding metabolic regulators enhanced the biotic and abiotic pathways of HA formation, and the promotion effect of adding ATP was more obvious. The study has great practical significance for the dispose of agricultural waste.

Additives Improved Saprotrophic Fungi&amp;nbsp;For&amp;nbsp;Formation of Humic Acids in Chicken Manure and Corn Stover Mix Composting

Additives Improved Saprotrophic Fungi&amp;nbsp;For&amp;nbsp;Formation of Humic Acids in Chicken Manure and Corn Stover Mix Composting

Humus is a guarantor of the stability of agroecosystems

The paper studies the processes of transformation of the molecular structure of humic (HA) and fulvic acids (FA) of leached chernozem under the influence of fertilizers and meliorant. The research was carried out under the conditions of many years of stationary experiment of the Department of Agrochemistry, Soil Science and Agroecology of the FSBEI HE Voronezh SAU. Samples of leached low-humus thin heavy-loamy chernozem were analyzed. The isolated and purified preparations of HA and FA were studied on a SM2203 spectrofluorimeter in the ultraviolet and visible ranges. The paper also presents the results of determining the most important physical and chemical properties of soil variants using various fertilizer and meliorant systems. Limed variants have optimal indicators. Based on the analysis, it can be assumed that the FA molecules of the variant with a double dose of mineral fertilizers on the background of manure differ in a developed aliphatic part, have many auxochromic substituents. HA of the same variant are characterized by a high condensation of nuclear structures. The HA and FA molecules of the variant with the joint application of fertilizers and meliorant have a more complex structure of the nuclear and peripheral parts. According to the results of calculations of extinction coefficients, it was found that liming contributes to the accumulation of more mature forms of humic acids.

Biodegradation and Structural Modification of Humic Acids in a Compost Induced by Fertilization with Steelmaking Slag under Coastal Seawater, as Detected by TMAH-py-GC/MS, EEM and HPSEC Analyses.

The compost's humic acid (HA) content decreased when it was fertilized in coastal seawater with steelmaking slag, as confirmed. This study clarified the cause for this change by a detailed analysis of the structural changes in HAs based on the TMAH-py-GC/MS, HPSEC, and 3D-EEM spectra. An increase in the levels of pyrolysates of tannic acid with a low polymerization degree was attributed to the biodegradation of a high polymerized aromatic structure. Moreover, analyses of 3D-EEM, supported by HPSEC, indicated that approximately 20 kDa of the fluorescent matter was generated at the protein-like peaks (Ex/Em = 220/340 and 275/350 nm) in HAs derived from a mixture of compost with steelmaking slag. It would be caused due to the formation of HAs from the bacterial by-product by a catalytic reaction of the steelmaking slag. From these findings reported herein, we conclude that bio-degradation was a major reason for the decreased HA content, and the formation of HA from a part of the degradation products. This would be a reason for the structural modification of HA under the seawater condition.

Mechanisms of genuine humic acid evolution and its dynamic interaction with methane production in anaerobic digestion processes

Humic acid (HA), a byproduct formed during the biological conversion of organic matter into biogas in the anaerobic digestion (AD) process, contains complex structures and redox functions. However, the evolution mechanism of HA and its interaction with CH4 production during the AD process have not been fully explored, particularly with respect to various substrates and temperature conditions. In this study, we investigated the evolutionary dynamics of the structure and function of genuine HA that naturally formed in the AD processes of chicken manure and corn stover under mesophilic (37 °C) and thermophilic (55 °C) conditions. The results demonstrated that the HA evolution mechanisms in AD of chicken manure and corn stover have different pathways. The AD of core stover showed higher degree of aromaticity (41.2–66.7% and 45.3–68.4% for mesophilic and thermophilic respectively) and humification index (1.5–4.2 and 2.8–4.5 for mesophilic and thermophilic respectively) than those (28.3–45.3% and 30.2–54.5% of aromaticity and 0.6–1.2 and 1.3–3.7 of humification index) in AD of chicken manure. The results from HSQC NMR spectroscopy and 2D-COS-FTIR spectroscopy demonstrated an accelerating effect of the higher temperature on the evolution of HA through humification. Moreover, the concurrent decomposition and re-polymerization of HA during both AD processes, resulting in positive and negative effects on CH4 production in the fast and slow CH4 production stages, respectively. The dynamic interaction was due to variations in the electron transferring ability and structure of the formed HA. The results could not only advance our understanding of the mechanisms of HA evolution and its interaction with the performance of AD process, but also support further research toward improving AD performance by regulating HA formation and transformation.

Impact of biochar addition on three-dimensional structural changes in aggregates associated with humus during swine manure composting

Aerobic composting is widely used to recycle agricultural organic waste. From a micro perspective, the dynamic changes in the internal structure of compost aggregates during composting can reflect aeration conditions, which is worthy of further study to improve composting efficiency. This study set three composting treatments (swine manure: rice straw = 4:1 and 8:1, swine manure: rice straw: biochar = 8:1:1, wet mass ratio), to detect 3-D microstructures of compost aggregate with the involvement of humus and biochar during composting. The results showed that biochar addition to compost enhanced humic acid formation and humification degree, and it greatly decreased bulk density by 45.89% and increased free air space by 31.25% compared with the initial stage of the compost. Compost materials tended to become looser during composting, and biochar aided an increase in total porosity of compost aggregates by approximately 90% compared with other treatments, mainly attributed to decomposition effects. It is assumed that large aggregates break up with the assistance of biochar, and these small parts of the materials gradually stick together with the formation of humus colloids to develop final dense particles. Therefore, it can be concluded that when biochar is used as an additive, it can improve the physical structure with the involvement of humus during composting.

Influence of malonic acid and manganese dioxide on humic substance formation and inhibition of CO2 release during composting

The aim of thisstudy was to explore the effects of malonic acid (MA), manganese dioxide (MnO2), malonic acid combined with manganese dioxide (MA + MnO2) additionon reducing CO2 emission and promoting humic substance (HS) formation during composting. The result showed that the addition of MA and MnO2 were an efficient way to reduce CO2 emission. Meanwhile, the CO2 emissions in the MA + MnO2 treatment was 36.8% less than that of the CK, and the amount of humic acid (HA) produced in the MnO2 treatment was 38.7% higher than that of the CK. Structural equation models demonstrated that the addition of exogenoussubstance promoted the conversion of amino acids and reducing sugars to HA. The addition of exogenous substances was the main reason for influencing the concentration of HA. In general, this research provided theoretical supports for the addition of exogenous substances to promote HA formation during composting.

The impact of fertilisers and fungicides on seed germination and the initial phase of seedling growth in black alder Alnus glutinosa (Gaertn.)

Abstract To test the influence of selected fertilisers and fungicides on the germination of black alder seeds and the initial phase of seedling growth, we conducted a laboratory experiment outlined in this paper. Six treatments were applied on petri dishes each containing 30 seeds. The substrate for germination was sterile filter paper wetted with an aqueous solution of either one of two fungicides, two organic fertilisers, a mineral fertiliser or distilled water (control). Fungicides and fertilisers were applied according to the manufacturers' recommendations. In order to keep genetic variability to a minimum, seeds originated from a single tree in a seed stand located in the Chotyłów Forest District, eastern Poland. Germination and growth took place at a temperature of 23°C ± 2°C with a 14 h/10 h day/night cycle. Seeds began to germinate as early as the second day after sowing, except for the mineral fertiliser treatment, in which the first sprouting was observed on day 3. Seedling length was measured daily from the day of germination of a given seed through to day 15. Germination was found to proceed most rapidly in the control, while the largest increments in length and dry mass occurred in the control and fertiliser treatment with the so-called N1 fertiliser (solely comprising growth stimulators in the form of humic acids, chitosan and silicon). The most limited growth was observed under the influence of the F1 fungicide (active compound Thiram) as well as the organic fertiliser N2 (a mixture of mineral components and organic growth stimulators). Roots were found to develop most rapidly in the control and in the treatment with N1 (no mineral components). These are also the only two treatments in which the roots were longer than the stems after 15 days. Fertiliser N2 was found to have the most unfavourable influence on both, germination and the first phase of seedling development. The fact that selected fertilizers and fungicides affected black alder seeds and seedlings under laboratory conditions does not mean that they will have an impact under field conditions or on other forest tree species. Therefore, this type of research will need to be conducted individually for each forest tree species.

Вплив різних систем удобрення на кількість і якісний склад гумусу дерново-підзолистого ґрунту

Goal. To establish regularities of changes of fractional group composition of humus of sod-podzolic soil under the influence of different fertilizer systems in the conditions of Western Polissia. Methods. Field, laboratory analytical, calculation. Results. On the background of liming in the organic fertilizer system, there is a positive trend to increase humic acids in the arable layer of the soil. The organo-mineral fertilizer system creates conditions for the accumulation of resistant to destruction compounds of soil organic matter. The type of humus changes from very fulvate to fulvate. The organo-mineral fertilizer system creates the most favorable conditions for the accumulation of humus in the arable soil layer (the humus content increased by 28.6% as compared to the control). The degree of mobility of the entire system of humic substances changes in the direction of increasing the organo-mineral fertilizer system and decreasing the mineral and organic fertilizer systems as compared to the control and the background of liming. Conclusions. During long-term agricultural use of sod-podzolic soil at grain-plowing crop rotation under the organo-mineral fertilizer system against the background of liming, the humus content in the arable layer increased to 1.53%, the degree of humification of organic matter changed from very high to high. With the introduction of fresh organic matter in the form of manure under organic and organo-mineral fertilizer systems. The content of mobile humic substances increased and the formation of humic acids intensified. The application of only mineral fertilizers increased the content of fulvic acids in soil organic matter.

Transformation in the Microbial Community and of Organic Substrate During Aerobic Fermentation of Manure

The results of a study of microbiological processes in controlled aerobic fermentation of litter dung was carried out. It was shown that the introduction of a microbial inoculum into the fermentable substrate allows to obtain an effective biofertilizer. It was found that in the process of transformation of organic matter a specific bacterial complex is formed, which significantly differs in quality composition from the microflora of the litter dung. The change in the composition of the microbial community affected the processes of humification and led to an increase in the proportion of humic acids by more than 3 times in comparison with initial substrate. Thus, along with the active processes of mineralization of organic matter, humification processes occur simultaneously, which is manifested in the formation and accumulation of humic acids. This allows us to justify the feasibility of the developed technology not only for the agro-industrial complex, but also for the microbiological processing of a wide range of organic waste into effective biofertilizers.

Reduction mechanism of Cd accumulation in rice grain by Chinese milk vetch residue: Insight into microbial community

Chinese milk vetch is an efficient approach to reduce Cd accumulation in rice, nevertheless, its reduction mechanism is not well understood. In this study, we investigated the rice grain Cd, soil properties and microbial community in a Cd-polluted paddy field amended with milk vetch residue (MV) or without (CK) during rice growth period. We found that milk vetch residue averagely decreased the Cd content in rice grain by 45%. Decrease of Cd in rice mainly attributed to the inhibition of Cd activation by milk vetch residue at heading stage probably by the formation of HA-Cd (Humic Acid) and CdS. Increased pH and organic matter (OM) promoted the reduction of available Cd. In addition, nonmetric multidimensional scaling (NMDS) analysis revealed that microbial community structure was significantly different between MV and CK treatment (r = 0.187, p = 0.002), and the core functions of differentially abundant genera were mainly associated with N-cycling, organic matter degradation and sulfate-reducing. The application of milk vetch residue increased the abundance of sulfate-reducing bacteria (SRB) by 8–112% during the rice growth period, which may involve in promoting the transformation of Cd to a more stably residual Cd (CdS). Canonical correspondence analysis (CCA) and mantel test analysis indicated that available K (p = 0.004) and available N (p = 0.005) were the key environmental factors of shaping the SRB. Altogether, changes in soil properties affected microbial structure and functional characteristics, especially the response of SRB in MV treatment would provide valuable insights into reducing the bioavailability of Cd in soil.

Stable isotopes reveal the formation diversity of humic substances derived from different cotton straw-based materials

Humic substances (HS) are essential in environment processes and carbon (C) sequestration in soils. In this study, organic materials such as cotton straw and its derived compost and biochar were added to the soil on a C-equivalent basis and incubated for 30 and 180 days in order to investigate the different forms of plant biomass derived C sequestration in HS. The C distribution in humic acid (HA), fulvic acid (FA), and humin (Hu) derived from organic materials was investigated using the 13C isotope method, while the catalase, sucrose, and β-glucosidase activities were also determined. The results showed that C3 distribution of Hu derived from straw, compost and biochar increased from 40.94% to 67.12%, 74.47% and 80.75%, respectively. In addition, the increase of C3 distribution of HA or FA derived from straw, compost and biochar were 4.69%, 10.09% and 1.49%, respectively. There were significantly positive correlations between catalase, sucrase and β-glucosidase activities and C3 derived HA and FA. The principal component analysis showed that catalase, sucrase and β-glucosidase were explained mainly by the first principal component indicating a significant correlation. These findings suggest that straw, compost and biochar are mainly sequestrated in Hu. Comparatively, the straw and compost are more likely to contribute to the formation of HA and FA in soil, but biochar favors the Hu, which helps in soil C sequestration. The formation of HA and FA derived from organic materials was supported by catalase, sucrase and β-glucosidase activities.

Photocatalytic Evaluation of Ag2CO3 for Ethylparaben Degradation in Different Water Matrices

The present study examines the photocatalytic properties of silver carbonate (Ag2CO3) for ethyl paraben (EP) degradation under simulated solar irradiation. Ag2CO3 was prepared according to a solution method and its physicochemical characteristics were studied by means of X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method, diffuse reflectance spectroscopy (DRS), and transmission electron microscopy (TEM). Complete EP (0.5 mg/L) removal was achieved after 120 min of irradiation with the use of 750 mg/L Ag2CO3 in ultrapure water (UPW), with EP degradation following pseudo-first-order kinetics. The effect of several experimental parameters was investigated; increasing catalyst concentration from 250 mg/L to 1000 mg/L led to an increase in EP removal, while increasing EP concentration from 0.25 mg/L to 1.00 mg/L slightly lowered kapp from 0.115 min−1 to 0.085 min−1. Experiments carried out with the use of UV or visible cut-off filters showed sufficient EP degradation under visible irradiation. A series of experiments were performed in real water matrices such as bottled water (BW) and wastewater (WW), manifesting Ag2CO3’s equally high photocatalytic activity for EP degradation. To interpret these results different concentrations of inorganic anions (bicarbonate 100–500 mg/L, chloride 100–500 mg/L) present in aqueous media, as well as 10 mg/L organic matter in the form of humic acid (HA), were added sequentially in UPW. Results showed accelerating effects on EP degradation for the lowest concentrations tested in all cases.

Effect of humic acid on the growth and yield of two maize (Zea mays L.) cultivars on andisol

One way to improve maize (Zea mays L.) production is through land extension using Andisol land. However, andisol soil has phosphate (P) fixation problem due to the high amorphous material. Hence, the use of organic material in the form of humic acid that has greater affinity to amorphous minerals is recommended to solve the problem. This research was conducted in February-May 2017 at Tri Dharma field of Faculty of Agriculture, Gadjah Mada University. The Andisol land used has a low available P category from Datar, West Java and Wonosobo, Central Java. This research was arranged in a Randomized Complete Block Design (RCBD), consisting of 2 factors. The first factor was maize cultivar (Bisi-2 and Pioneer-35). The second factor was the doses of humic acid, consisting of control treatment (without fertilizer and humic acid), NPK without humic acid, and NPK + humic acid at 5%, 10%, and 15%. The percentage of humic acid given, based on the amount of NPK 16:16:16 fertilizer, was 350 kg ha-1. Fertilization was applied 3 times 100 kg ha-1 on 1 WAP, 150 kg ha-1 at 3 WAP and 100 kg ha-1 at 7 WAP. The results is, humic acid treatment had the same effect with NPK fertilization treatment only and control on P available Andisol soil. Humic acid, also has the same effect with NPK fertilizer treatment in increasing the yield component of 100 seeds weight, dry weight of seeds, harvest index, length of cobs and productivity.