Changes of humic substances characteristics from forested to cultivated soils in Ethiopia

Spaccini, Riccardo; Mbagwu, J.S.C.; Conte, Pellegrino; Piccolo, A.

doi:10.1016/j.geoderma.2005.04.015

Cited by 116 publications

(82 citation statements)

References 41 publications

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“…Generally, alkyl C and aromatic C represented the recalcitrant and hydrophobic fractions, whereas O-alkyl C was a relatively easily decomposable and hydrophilic fraction in HA (Ussiri and Johnson 2003;Spaccini et al 2006). The larger values of the alkyl C/O-alkyl C, aliphatic C/aromatic C, and hydrophobic C/hydrophilic C ratios indicated that HA were more decomposed, aliphatic, and hydrophobic (Zhang et al 2011).…”

Section: Soil Ha Compositionmentioning

confidence: 96%

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Cao

Yong

et al. 2016

J. Mt. Sci.

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Alpine grassland soils on Qinghai-Tibet Plateau store approximately 33.5 Pg of organic carbon (C) at 0-0.75 m depth and play an important role in the global carbon cycle. We investigated soil organic C (SOC), water-soluble organic C (WSOC), easily oxidizable organic C (EOC), humic C fractions, aggregate-associated C, aggregate stability, and humic acid (HA) composition along an east-west transect across Qinghai-Tibet Plateau, and explored their spatial patterns and controlling factors. The contents of SOC, WSOC, EOC, humic C fractions and aggregate-associated C, the proportions of macroaggregates (2-0.25) and micro-aggregates (0.25-0.053 mm), and the aggregate stability indices all increased in the order alpine desert < alpine steppe < alpine meadow. The alkyl C, O-alkyl C, and aliphatic C/aromatic C ratio of HA increased as alpine desert < alpine meadow < alpine steppe, and the trends were reverse for the aromatic C and HB/HI ratio. Mean annual precipitation and aboveground biomass were significantly correlated with the contents of SOC and its fractions, the proportions of macro-and microaggregates, and the aggregate stability indices along this transect. Among all these C fractions, SOC content and aggregate stability were more closely associated with humic C and silt and clay sized C in comparison with WSOC, EOC, and macro-and microaggregate C. The results suggested that alpine meadow soils containing higher SOC exhibited high soil aggregation and aggregate stability. Mean annual precipitation should be the main climate factor controlling the spatial patterns of SOC, soil aggregation, and aggregate stability in this region. The resistant and stable C fractions rather than labile C fractions are the major determinant of SOC stocks and aggregate stability. Keywords

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Section: Soil Ha Compositionmentioning

confidence: 96%

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Cao

Yong

et al. 2016

J. Mt. Sci.

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“…While the PHA exhibits higher C contents, higher C/H ratio and lower ratio of (N + O)/C, indicating higher aromaticity [31]. The hydrophobic index (HB/HI) [32] of the two dissolved HAs is greatly different. The PHA has lower HB/HI than the SHA (Table 1).…”

Section: Physico-chemical Properties Of Hasmentioning

confidence: 98%

Sorption of atrazine onto humic acids (HAs) coated nanoparticles

Yan

et al. 2009

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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a b s t r a c tWith the development of nanotechnologies, a large number of nano-materials with novel properties are being released into the environment. However, little is known about their fate, transport, toxicity and interactions with organic matters in aqueous environment. In this study, nano-SiO 2 or kaolinite, coated with soil humic acid (SHA) and peat humic acid (PHA), were used as sorbents. The original and HA-coated nanoparticles were characterized for particle size, TEM and electrophoretic mobility. Sequential ultrafiltration (UF) was used to characterize the molecular size fractionations of dissolved HAs. Sorption data of atrazine (AT) under various solution concentration, ionic strength and pH were well fitted with Freundlich model. Sorption amount of AT on HA-coated nanoparticles was significantly lower than that on original particles. The sorption maximum appeared at I = 0.001 mol/l (NaNO 3 ), pH 3. Size of nanoparticle aggregates, conformation of HA and specific surface area were factors affecting the sorption process. The compressed conformation of HA was more favorable for HA sorption than expanded one. Size of aggregation was not a determinant factor for the sorption process, while the specific surface areas of nano-sorbent was an important one. Results indicated that HA plays an important role in the transport and toxicity of nanoparticles and AT in aqueous environment.

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“…12 After the extraction of humic and fulvic acids by means of alkaline solution, mixed solutions are used, such as NaOH + Urea, DMSO + H 2 SO 4 , DMSO + HCl and Acetone + HCl, and thereby different intra-aggregate organic bonds are broken stepwise. [13][14][15] To date, most of the studies on the impact of exotic species plantation on SOM, comprising Brazilian regions, have focused mainly on its stocks or have emphasized Eucalyptus plantations. In a recent study investigating the impact of Pinus introduction on SOM of a Leptosol located in South Brazil, an increase in the chemical recalcitrance and carboxylic groups in the SOM structure was observed in addition to a decrease in C stocks, after 30 years of plantation.…”

Section: Introductionmentioning

confidence: 99%

Distribution of chemical compartments of soil organic matter and c stocks of a cambisol from south Brazil as affected by Pinus afforestation

Almeida¹,

Dick²,

Bertotto³

et al. 2012

Quím. Nova

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Distribution and stocks of soil organic matter (SOM) compartments after Pinus monoculture introduction in a native pasture area of a Cambisol, Santa Catarina, Brazil, were investigated. Pinus introduction increased soil acidity, content of exchangeable Al+3 and diminished soil nutrients. Nevertheless, soil C stock increased in all humic fractions of the 0-5 cm layer after Pinus afforestation. In the subsurface, the vegetation change only promoted SOM redistribution from the NaOH-extractable humic substances to a less hydrophobic humin fraction. Under Pinus, soil organo-mineral interactions were relevant up to a 15 cm depth, while in pasture environment, this mechanism occurred mainly in the surface layer

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Changes of humic substances characteristics from forested to cultivated soils in Ethiopia

Cited by 116 publications

References 41 publications

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Sorption of atrazine onto humic acids (HAs) coated nanoparticles

Distribution of chemical compartments of soil organic matter and c stocks of a cambisol from south Brazil as affected by Pinus afforestation

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