An Assessment of Organic Carbon Fractions in Paddy and Associated Non-paddy Soils of Upper Brahmaputra Valley of Assam

An investigation was carried out to study the soil organic carbon fractions in paddy and associated non-paddy soils of Assam, India. Three districts viz. Sivasagar, Jorhat and Golaghat in the Brahmaputra valley of Assam were selected for this study. Soil samples were collected from six profiles, three each from mono-cropped paddy and associated non-paddy areas were collected. Horizon -wise, soil samples were analyzed for organic carbon fractions. Organic carbon, Humus C, Humin C, Humic acid C and Fulvic acid C were all analyzed from the samples. Organic carbon content in soil varied from 0.90 -7.90g kgâ»Â¹. Surface horizons of paddy soils contained lower amounts of humus C (0.255-0.330 per cent) and fulvic acid C (CFA) (0.135 â€“ 0.180 per cent) and higher amounts of humin carbon (0.210 -0.475 per cent) and humic acid C (CHA) (0.120-0.150 per cent) as compared to that of non-paddy soils (0.300-0.435 and 0.195-0.300, 0.180-0.490 and 0.105-0.135 per cent respectively). It was concluded that the ratio of (CHA+CFA)/CTOC indicated less humification on the surface horizons of paddy soils. This is a direct result of prolonged submergence which led to humic acid carbon becoming less oxidized or humified.

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Application of Inductively Coupled Plasma Spectrometric Techniques and Multivariate Statistical Analysis in the Hydrogeochemical Profiling of Caves—Case Study Cloșani, Romania

Molecules ◽

10.3390/molecules26226788 ◽

2021 ◽

Vol 26 (22) ◽

pp. 6788

Author(s):

Anamaria Iulia Torok ◽

Erika Andrea Levei ◽

Silviu Constantin ◽

Oana Teodora Moldovan ◽

Marin Senila ◽

...

Keyword(s):

Statistical Analysis ◽

Organic Carbon ◽

Multivariate Statistical Analysis ◽

Principal Component ◽

Soil Samples ◽

Multivariate Statistical ◽

Carbon Fractions ◽

Silty Soil ◽

Water Characteristics ◽

Organic Carbon Fractions

The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3− and NH4+) were also considered. The ANOVA—principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3− water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3− (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis.

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