scholarly journals Chemical Characteristics of Humic Substances in Nature

2021 ◽  
Author(s):  
Claudio Fernando Mahler ◽  
Nicoly Dal Santo Svierzoski ◽  
Cassiano Augusto Rolim Bernardino

Humic substances are the main constituents of natural organic matter, found in both aquatic and terrestrial environments. Humic substances are a complex, dispersed, and heterogeneous mixture of various organic compounds synthesized from organic matter residues, decomposed by microorganisms. Most scientists indicate that humic substances are as a supramolecular association of small heterogeneous molecules stabilized by weak intermolecular bonds. When these substances are presented in water intended for drinking or industrial use, it can have a significant impact on the treatability of this water and on the success of chemical disinfection processes, due to possible formation of organic compounds harmful to human health. Moreover, the humic substances can be used of several ways such as fertilizer to help in the development of plants, to improve soil erosion and to removal of organic compounds and metals from soils and waters. In addition, humic substances suggest an important role in mitigating areas degraded by the phytoremediation technique. The purpose of chapter is to provide an overview of humic substances and to discuss their concepts, chemical characteristics, ecological effects and technological applications for soils and aquatic systems.


2012 ◽  
Vol 25 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Juliana Vanir De Souza Carvalho ◽  
Eduardo De Sá Mendonça ◽  
Newton La Scala ◽  
César Reis ◽  
Efrain Lázaro Reis ◽  
...  

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.





2018 ◽  
Vol 44 ◽  
pp. 00099
Author(s):  
Dominika Łomińska-Płatek ◽  
Anna M. Anielak

As is well known without organic matter, there would be no life. Organic compounds perform very important functions in the whole ecosystem as: structural, storage, transport, catalyse reactions, immune and regulatory functions. One of the most important for both living and non-living organic matter is their role in the biogeochemical cycles of carbon, phosphorus, nitrogen and others elements. The major form of organic matter are humic substances (HS) which are a mixture of high molecular weight organic compounds with variable composition. Humic substances can be divided into: humic acids (HA), fulvic acids (FA) and humins (Hu). In the presented research FA were studied. They were extracted from the effluent in the process of ion exchange in a hydrophobic ion exchanger and then they were examined by qualitative analysis to determine the elemental composition of acids and the degree of contamination with heavy metals and other substances. The main aim was to balance and assess the amount of FA in the primary and secondary effluent. The studies have shown that concentration of FA in raw wastewater (primary effluent) was bigger than in the treated wastewater (secondary effluent). Based on the research, it can be stated that selected WWTP discharges less FA compared to the input pollution load.



2019 ◽  
Vol 46 (1) ◽  
pp. 43-50
Author(s):  
O. Yu. Drozdova ◽  
S. M. Ilina ◽  
N. A. Anokhina ◽  
Yu. A. Zavgorodnyaya ◽  
V. V. Demin ◽  
...  

In this study, compositions of organic matter were investigated in the conjugate series of natural waters, including that from soil water, wetlands, streams, and lakes. In determinations of compositions of aliphatic and benzoic acids and humic substances, humic substances comprised the bulk of dissolved organic carbon, with 28% in lake waters and 57% in waters of wetlands and a weighted average molecular mass of 1 kDa. Aliphatic and benzoic acids comprised ≤ 2% of the total carbon content of water-soluble organic compounds. Transformations of dissolved organic matter occurred in a series of surveyed waters. Specifically, compositions and specific characteristics are dynamic, and increases in the fraction with a molecular weight of < 1 kDa were associated with photo- and bio-degradation of macromolecular organic compounds.



Author(s):  
Chuan-Wang Yang ◽  
Li Yuan ◽  
Hong-Zhi Zhou ◽  
Xin Zhang ◽  
Guo-Ping Sheng

Natural organic matter (NOM) can adsorb onto engineered nanoparticles (ENPs) and form NOM-corona on ENPs-solution interface, thus affecting the performance and ecotoxicity of ENPs in aquatic systems. Nevertheless, the formation...



Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.



2021 ◽  
Vol 10 (5) ◽  
pp. 348
Author(s):  
Zhenbo Du ◽  
Bingbo Gao ◽  
Cong Ou ◽  
Zhenrong Du ◽  
Jianyu Yang ◽  
...  

Black soil is fertile, abundant with organic matter (OM) and is exceptional for farming. The black soil zone in northeast China is the third-largest black soil zone globally and produces a quarter of China’s commodity grain. However, the soil organic matter (SOM) in this zone is declining, and the quality of cultivated land is falling off rapidly due to overexploitation and unsustainable management practices. To help develop an integrated protection strategy for black soil, this study aimed to identify the primary factors contributing to SOM degradation. The geographic detector, which can detect both linear and nonlinear relationships and the interactions based on spatial heterogeneous patterns, was used to quantitatively analyze the natural and anthropogenic factors affecting SOM concentration in northeast China. In descending order, the nine factors affecting SOM are temperature, gross domestic product (GDP), elevation, population, soil type, precipitation, soil erosion, land use, and geomorphology. The influence of all factors is significant, and the interaction of any two factors enhances their impact. The SOM concentration decreases with increased temperature, population, soil erosion, elevation and terrain undulation. SOM rises with increased precipitation, initially decreases with increasing GDP but then increases, and varies by soil type and land use. Conclusions about detailed impacts are presented in this paper. For example, wind erosion has a more significant effect than water erosion, and irrigated land has a lower SOM content than dry land. Based on the study results, protection measures, including conservation tillage, farmland shelterbelts, cross-slope ridges, terraces, and rainfed farming are recommended. The conversion of high-quality farmland to non-farm uses should be prohibited.



Author(s):  
A.M. Tadini ◽  
L. Martin‐Neto ◽  
A.I. Goranov ◽  
D.M.B.P. Milori ◽  
A.C.C. Bernardi ◽  
...  


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