Characteristics Of Humic Substances Research Articles

Characterization of soil organic carbon at profile scale in two forest soils under pine and holm oak

Context It is essential to promote soil carbon sequestration as a means to mitigate climate change. Thus, it is fundamental to know the distribution of C in the soil at profile scale, the characteristics of humic substances as indicators of soil organic matter (SOM) turnover and their relationship with other soil properties. Aims Two forest ecosystems under pine and holm oak developed under a Meso-Mediterranean climate in Spain were used to characterize SOM through the complete sequence of layers of the soil profile. Methods General soil analysis, infrared spectroscopic analysis and soil color measurements were conducted for the characterization. Key results Humus form under oak was found to be Mull mesotrophic–Mull acid while humus under pine Moder oligotrophic. The infrared spectrum determined that oxidation of the humic acids was more complete in the deeper horizons. Relationships between intensities of the main spectral bands in both soils followed similar maximum and minimum sequence values. The total humic extract (THE) color measured by reflection was found inversely related to the THE color measured by transmission. In the same way, the color spectrum between 350 and 800 nm in the THE showed an inverse relation between hue/brightness and absorbance values. Conclusions Infrared analysis and color measurements provided evidence of a different level of stabilization of humic substances from each soil, and between the different horizons. Large spatial variability in soil organic carbon quantity and quality was observed. Implications Better understanding of carbon sequestration behavior in different soil ecosystems in its crucial role within the global carbon cycle

Partial ozonation enhanced the content and aromatization of humic substances in activated sludge through chemical and microbial effects

Influences of partial ozonation on characteristics of humic substances (HS) in activated sludge (AS) was systematically investigated. It was firstly found that partial ozonation not only reduced sludge production, but also increased content and aromatization of HS in AS. The total extractable carbon of HS (TEC) in AS subjected to partial ozonation (i.e., an increasing O3 dosage, from 25 to 125 mg O3/g VS) considerably increased, from 138.7 ± 2.4 mg/L (SBR-25) to 151.6 ± 2.7 mg/L (SBR-125), which were 1.01–1.10 times the TEC of the control (SBR-0). In which the organic carbon of fulvic acids (FAC) and humic acids (HAC) increased from 30.9 ± 4.8 and 106.3 ± 4.6 mg/L (SBR-0) to 34.7 ± 1.3 and 116.9 ± 1.4 mg/L (SBR-125), respectively. SUVA254 values of both FA and HA in SBR-25∼SBR-125 were greater than their values in SBR-0. Mechanisms were clarified from chemical and microbial perspectives. During O3 treatment, organic nitrogenous substances and aliphatic compounds in HA were more mineralized and fused by O3; FA were more formed from soluble proteins and polysaccharides than mineralized. Consequently, HA content in AS was reduced with enhanced aromaticity, while FA content was increased with maintained aromaticity after O3 treatment. Then, after the ozonated AS was returned to SBR systems, the enhanced microorganism-led formation of HA in SBR from more accessible FA played a dominating role in the final increased TEC. Enhanced relative abundance (RA) of genera Lactococcus and Thauera after partial ozonation was possibly responsible for the increased RA of K00615 (tktA) and K00873 (pyk), promoting production of intermediates including phosphoenolpyruvate and erythrose-4-phosphate (initial metabolites for shikimate pathway) from glucose, enhancing HA formation related with shikimate pathway, and finally increasing the content and aromatization of HS. The results could guide researchers on improving sludge management by decreasing sludge production yield and enhancing sludge utilization potential through partial ozonation during wastewater treatment.

Humic Substances Derived From Biomass Waste During Aerobic Composting and Hydrothermal Treatment: A Review

Humic substances (HSs) occupy 80% of organic matter in soil and have been widely applied for soil remediation agents, potential battery materials, and adsorbents. Since the HS extraction rate is very low by microbial degradation in nature, artificial humification processes such as aerobic composting (AC) and hydrothermal treatment (HT) have attracted a great deal of attention as the most important strategies in HS production. This article aims to provide a state-of-the-art review on the development of conversion of biomass waste into HSs based on AC and HT for the first time in terms of mechanisms, characteristics of HSs’ molecular structure, and influencing factors. In addition, some differences based on the aforementioned information between AC and HT are reviewed and discussed in the conversion of biomass waste into HSs in a pioneering way. For biomass waste conversion, a feasible strategy on effective humification processes by combining AC with HT is proposed.

Characteristics of humic substance in lake sediments: The case of lakes in northeastern China

As an important part of lake ecosystems, sediments play a key role in the carbon cycle in lakes. Due to the complex sources of organic matter in sediments, the link between sequestration and transformation of humic substance is largely unknown. Therefore, it is essential to understand the characteristics of humic substance in lake sediments. In this study, the relationship between the characteristics of humic substance and environmental conditions was found in sediment samples from six typical lakes of northeast China. The structure of humic substance (HS), fulvic acid (FA) and humic acid (HA) tended to be simplified with decreasing lake depth. Pearson analysis indicated that characteristics of humic substances in deep lake sediments were dominantly determined by nutrient factors (e.g., NO3−-N, NO2−-N, NH4+-N) and physicochemical factors (e.g., pH, water temperature, dissolved oxygen), while the changes of HS in shallow lake sediments were dominantly determined by physicochemical factors (e.g., pH, water temperature, dissolved oxygen). Variation partitioning results also indicated that nutrient factors and physicochemical factors explained 64% and 24.2% of the variations of HS content in boreal deep lakes. In comparison, physicochemical factors explained most of the variation (35.6%) of HS composition, while nutrient factors only explained 3.4% of the variation in shallow lakes. Structural equation models further confirmed that complex components were transformed into simple components by nutrient and physicochemical factors with decreasing lake depth. This study suggests that changes in environmental conditions with lake depth may result in changes in the quality of HS in lake sediments.

Characteristics of humic substances from municipal sewage sludge: a case study

Characteristics of humic substances from municipal sewage sludge: a case study

Soil carbon characterization along the profile of two forest soils under Quercus pyrenaica

In light of concerns over climate change and increasing levels of CO2 in the atmosphere, it is of importance to investigate soil organic matter in Mediterranean forests at a profile scale. In-depth studies of the organic fraction are also of interest to improve understanding of carbon balance and to facilitate modelling of carbon fixation in forest soils. This research evaluates the relationships between diverse parameters such as colour, content, and form of soil organic matter (SOM). Two Quercus pyrenica ecosystems with soils classified as inceptisols with a xeric or dry moisture regime, and developed under a Mediterranean climate in Spain, were used to characterize SOM through the complete sequence of layers of the soil profile. The differentiating factor between the two ecosystems was slope gradient. Characterization was done using characteristics of humic substances (HS) as indicators of SOM turnover in inceptisols. Infrared analysis was used to further characterize the humic acids. As soil colour measurements are a tool for soil type classification and soil organic carbon prediction, the relation between HS colour measured by reflection and by transmission was determined in order to establish a relationship between measurement techniques. Infrared analysis and colour provided evidence of a different level of stabilization of HS from both soils, and between the different horizons. Oxidation of humic acids was found to be greater in deeper horizons than in the surface layers. An inverse relationship between HS colour measured by reflection and by transmission was revealed. Both soils showed a clear trend in which horizons presenting lower absorbance numbers showed higher figures of hue and value. A more marked accumulation of humified compounds was found in pedons, (the smallest unit or volume of soil that contains all the soil types), in the less steep slope. This might be explained in terms of the physiographic position affecting infiltration behavior and exposure to runoff.

Fouling characteristics of humic substances on tight polysulfone-based ultrafiltration membrane

Fouling characteristics of humic substances on tight ultrafiltration (UF) membrane have been investigated. The tight UF membrane was prepared by blending polysulfone (PSf) in N.N-dimethylacetamide (DMAc) with 25%wt of Polyethylene glycol (PEG400) and 4%wt of acetone. Fouling characteristic of the modified PSf membrane was observed during peat water filtration in different trans-membrane pressure (TMP). It was found that the acetone modified membrane provided 13% increase in TMP during five hours of peat water filtration, where a stable flux was reached within 150 minutes. Meanwhile, the increase of TMP from 10 psig to 30 psig resulted in a fouling resistance enhancement of 60%. Furthermore, based on the fouling analysis, fouling mechanism at the first phase of filtration was attributed to intermediate blocking while the second phase was cake formation.

Characterization of Humic Substance Extracted from Andisols, Spodosols, Peat, and Lignite

Soil and other materials with high C-organic content are potential natural sources of humic substances. Until now the differences in the characteristics of such humic substances that are extracted from different sources have not been widely studied. Thus, this study was aimed to characterize humic substances extracted from andisols, spodosols, peat, and lignite. The highest C-organic (48.8%) and N (7.6%) were obtained from peat and spodosols, respectively. The andisols humic substance produced the highest total acidity (6.52 cmol kg<sup>-1</sup>). Humic substance extracted from spodosols was a mostly aliphatic group and phenolate –OH, while that of andisols and lignite contained more aromatic group and phenolate –OH, whereas the humic substance from peat was a predominantly aliphatic group and –COOH. The surface morphology of the humic substances observed using SEM showed varying densities and shapes due to differences in their respective degree of decomposition and the formation process involved. There has been significant interest in investigating the different characteristics of the humic substance. The type humic substances are important to be known considering of their positive effects on soil fertility and plant growth and development.

Estimation of the Buffer Properties of Natural Waters with Account for the Acid–Base Characteristics of Humic Substances

The influence of the acid–base properties of humic substances in natural waters on the buffer capacity value is considered. An alternative way of calculation of the ANC parameter taking into account the dual nature of the humus organic of waters is proposed. Zonal aspects of the distribution of natural waters over ANC values are evaluated, and the features affecting these parameters are singled out.

The Influence of Humic Substances on the Sorption of Three Organic Contaminants with Different Structure and Polarity to Clay Minerals

The sorption of three organic contaminants with different structure and polarity including non-polar phenanthrene (PHEN), 1,2,4,5-tetrachlorobenzene (TeCB), and polar 1,2-dichlorobenzene (DCB) onto original kaolinite, smectite, vermiculite, and fulvic acid (FA)/humic acid (HA)–clay complexes were investigated, and possible sorption mechanisms were inferred from sorption isotherms and characteristics of humic substances (HS) and HS–mineral complexes. Results showed smectite and vermiculite had stronger sorption ability than kaolinite, and the adsorbed amount of DCB was much higher than that of PHEN and TeCB on each clay. Due to FA/HA-facilitated hydrophobic interaction, FA/HA–clay complexes except FA–vermiculite complex showed a stronger affinity for PHEN and TeCB than the original clays, particularly for HA–clay complexes. The non-linearity parameter values of n for all the Freundlich sorption isotherms of DCB were greater than 1, indicating that clays possessed some unique sites with strong affinity and capacity to sorb DCB from aqueous solutions. FA/HA did not significantly affect the sorption of polar DCB on clays, implying sorption of DCB on clays was probably due to polar interactions between the polar group of DCB and clays. Cation-π bonding between PHEN and iron cation was directly evidenced by X-ray photoelectron spectroscopy, and FA impeded the sorption of PHEN on vermiculite by occupation of iron cation sites. This study will benefit understanding behaviors of contaminants in the soil environments.

Effect of long-term drainage on the content and composition of humus in soddy-podzolic soils and their particle-size fractions

Changes in the quantitative and qualitative characteristics of humic substances in soddy-podzolic soils and their particle-size fractions in the course of long-term drainage have been studied under the conditions of pronounced microrelief and different intensities of agrotechnical impacts. The transformation features of humic substances during the periods of specific impacts have been characterized.

Sarykul paleosol in Southern Urals sediments (Russia)

Sarykul paleosols in the Southern Urals (Russia) with a stable position in geological sediments are considered. The Brunhes-Matuyama boundary was found in these paleosols and they were used as a source of information on the environment. Data were obtained during the study of the Sarykul paleosols in four sections located in the mountain part of the Southern Urals on the Miass River erosion-accumulation terrace and at the eastern edge on the trans-Uralian peneplain. Saykul paleosols have a relatively thick and compact humic horizon with a tongued lower boundary. The paleosols are dark grey with high TOC content that is not usual for the Early Pleistocene paleosols. The materials showed that Sarykul paleosols formed on different parent rocks may have various characteristics of the mineral part (texture, pH, magnetic susceptibility, carbonate content, ratio of exchangeable cations), while their humic substances characteristics (humic and fulvic acid ratio, humic acid characteristics of elemental composition and structure) are very similar. Climate conditions during Sarykul paleosol formation changed from relatively warm and humid to less warm and more humid. The study of Southern Urals Sarykul paleosols has shown that they can serve as a reliable marker of the final Early Pleistocene due to their specific characteristics, not analogous to the modern soils.

Effect of <i>Phanerochaete chrysosporium</i> on the Characteristics of Humic Substances during Composting of Agricultural Wastes

The effect of Phanerochaete chrysosporium (Pc) on the characteristics of humic substances (HS) was investigated during composting of agricultural wastes. The dynamic changes of HS, fulvic acid (FA), humic acid (HA) and the humification index (HI) were monitored during a 60-day composting. The results showed that the formation of FA was not obviously influenced, while HA formation was improved by the inoculum of Pc. During the composting process, HI increased from 0.28, 0.29 to 2.23 and 3.17 in the control and the treatment, respectively. This result indicated that Pc could significantly enhance the degree of HS aromatization (P<0.05). This research helps to know the contribution of Pc to the formation of HS during composting and provide some useful information for the development of efficient methods to increase the content of HS in the composting.

Three-dimensional (3-D) fluorescence spectroscopy analysis of the fluorescent dissolved organic matter released by the marine toxic dinoflagellate Alexandrium catenella exposed to metal stress by zinc or lead.

We investigated the effects of zinc or lead on growth and on exudation of fluorescent dissolved organic matter (FDOM) by the marine toxic dinoflagellate Alexandrium catenella (Whedon & Kofoid) Balech. The species was exposed to increasing free zinc (1.34 × 10(-7) M-3.98 × 10(-6) M) or lead (5.13 × 10(-9) M-1.82 × 10(-7) M) concentra-tions. Low metal levels ([Zn(2+) ] = 1.34 × 10(-7) M; [Pb(2+) ] = 5.13 × 10(-9) M) had no effect on cell growth. Toxic effects were observed from higher metal contamination ([Zn(2+) ] = 3.98 × 10(-6) M; [Pb(2+) ] = 6.54 × 10(-8) M), as a conversion of vegetative cells into cysts. Analysis of the released FDOM by three-dimensional (3-D) fluorescence spectroscopy was achieved, using the parallel factor analysis (PARAFAC). The PARAFAC modeling revealed four components associated with two contributions: one related to the biological activity; the other linked to the organic matter decomposition in the culture medium. The C1 component combined a tryptophan peak and characteristics of humic substances, whereas the C2 component was considered as a tryptophan protein fluorophore. The two others C3 and C4 components were associated with marine organic matter production. Relea-sed fluorescent substances were induced by low ([Zn(2+) ]= 1.34 × 10(-7) M; [Pb(2+) ] = 5.13 × 10(-9) M) and moderate ([Zn(2+) ] = 6.21 × 10(-7) M; [Pb(2+) ] = 2.64× 10(-9) M) metal concentrations, suggesting the activation of cellular mechanisms in response to metal stress, to exudate FDOM that could complex metal cations and reduce their toxicity toward A. catenella cells.

The role of the characteristics of humic substances in binding with benzo[h]quinoline

The binding constants (K(DOC)) of the mixture of benzo[h]quinoline and its protonated analog, benzo[h]quinolinium, to four types of humic substances obtained from the International Humic Substances Society were determined by the fluorescence quenching method. A simple mixing model was used to eliminate the fluorescent interference from the minor analog in the solution and to deduce K(mix), which represents the overall binding as the sum of that for the individual analogs. The characteristics of humic substances, especially their hydrophobicity and aromaticity, established by principal component analysis of structural and elemental compositions, were the main determinants of the binding affinity with both benzo[h]quinoline and benzo[h]quinolinium (K(BQ) and K (BQH+) across a range of pH values. The strongest overall affinity of benzo[h]quinoline for humic substances is observed near pH 4 and with more hydrophobic humic substances, which suggests possible choices in attempts at remediation of benzo[h]quinoline containing particles with humic substances.

Caracterização da matéria orgânica do solo em fragmentos de mata atlântica e em plantios abandonados de eucalipto

A compreensão da dinâmica da matéria orgânica (MO) nos ecossistemas de Mata Atlântica é necessária para o manejo eficiente e conservação de vegetações nativas. A natureza química das substâncias húmicas (SHs) reflete os processos de gênese e uso do solo e pode ser usada como indicador da qualidade da MO. O objetivo deste estudo foi usar a qualidade da MO como sinalizador do ambiente edáfico em áreas de mata nativa, sobre Gleissolo Háplico Tb distrófico, argissólico e Cambissolo Háplico Tb distrófico, e em plantios abandonados de eucalipto de diferentes idades, sobre Argissolo Vermelho-Amarelo distrófico latossólico, localizados na Reserva Biológica União, RJ. Para isso, foram avaliadas as distribuições da MO humificada e os ácidos húmicos do solo por meio de métodos químicos e espectroscópicos, em duas profundidades do solo (0-0,10 e 0,10-0,20 m). Os solos da Reserva Biológica apresentaram fertilidade natural muito baixa, condição esta limitante para o processo de humificação. As SHs representaram, portanto, menos de 50 % do carbono prontamente oxidável, indicando que as substâncias não-húmicas compõem a maior parte da MO; portanto, a serrapilheira tem o papel central na nutrição das plantas e microrganismos. A distribuição relativa das frações que compõem a MO humificada não foi alterada pela cobertura vegetal nem pela classe de solo. Os ácidos húmicos apresentaram natureza química semelhante à normalmente encontrada para os ácidos fúlvicos, e tais características foram expressas no baixo conteúdo de C e nos elevados valores das razões H/C e O/C e da acidez, o que levou à formação de material humificado pouco condensado.A espectroscopia de infravermelho indicou o efeito do tipo de solo e da cobertura vegetal sobre a qualidade química dos ácidos húmicos. O material humificado isolado da Mata Atlântica apresentou maior intensidade de fluorescência, sugerindo maior labilidade e capacidade de ceder elétrons para reações químicas do solo.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Characteristics of Humic Substances in Earthworm Casts in Different Vegetation in Okinawa Island

Characteristics of Humic Substances in Earthworm Casts in Different Vegetation in Okinawa Island

Membrane Fouling in Pilot-Scale Membrane Bioreactors (MBRs) Treating Municipal Wastewater

The main obstacle for wider use of membrane bioreactors (MBRs) for wastewater treatment is membrane fouling (i.e., deterioration of membrane permeability),which increases operating costs. For more efficient control of membrane fouling in MBRs, an understanding of the mechanisms of membrane fouling is important. However, there is a lack of information on membrane fouling in MBRs, especially information on features of components that are responsible for the fouling. We conducted a pilot-scale experiment using real municipal wastewater with three identical MBRs under different operating conditions. The results obtained in this study suggested that the food-microorganisms ratio (F/M) and membrane filtration flux were the important operating parameters that significantly influenced membrane fouling in MBRs. Neither concentrations of dissolved organic matter in the reactors nor viscosity of mixed liquor, which have been thought to have influences on fouling in MBRs, showed clear relationships with membrane fouling in this study. Organic substances that had caused the membrane fouling were desorbed from fouled membranes of the MBRs at the termination of the operation and were subjected to Fourier transform infrared (FTIR) and 13C nuclear magnetic resonance (NMR) analyses. These analyses revealed that the nature of the membrane foulant changes depending on F/M. It was shown that high F/M would make the foulant more proteinaceous. Carbohydrates were dominant in membrane foulants in this study, while features of humic substances were not apparent.

Influence of alkaline extraction on the characteristics of humic substances in Brazilian soils

An investigation was made of the influence of alkaline extraction on the characteristics of humic substances extracted from Brazilian soil samples. Humic substances (HS) from seven different soils samples collected in Brazil were extracted using the procedure recommended by the International Humic Substances Society (IHSS). Soils, HS and humins were characterized by thermogravimetry and differential thermal analysis. About 8 mg of each material (soil, HS and humin) were placed in a platinum crucible and heated continuously from 20 to 750 °C at a heating rate of 10 °C min −1 in an atmosphere of synthetic air (100 ml min −1). A thermal analysis revealed a difference between the content and structural characteristics of organic matter present in HS and humin fractions in relation to their soils. The results indicated that alkaline extraction alters the characteristics of humic substances during the extraction process, underlining the importance of developing methodologies and analytical procedures that allow organic matter in soils to be studied without extracting it.