Determination of organic and inorganic carbon, δ¹³C, and nitrogen in soils containing carbonates after acid fumigation with HCl

Abstract

In carbonate-containing soils a reliable determination of organic C requires a method that effectively separates organic and inorganic C without altering the organic matter. This study was conducted to determine whether HCl vapor completely removes carbonates even in dolomiterich soils and to what extent a widely used acid-fumigation method has to be modified for humus-rich soils. Furthermore, it was tested whether HCl fumigation alters organic-C content. Since C and N parameters are often analyzed simultaneously we also tested the influence of acid-vapor treatment on N content and on d 13 C of soil organic matter. We applied fumigation with 37% HCl for 8 and 32 h using 9 carbonate-containing soil samples. Inorganic C ranged from 7 to 124 and organic C from 9 to 267 g kg -1 . The maximum contents of dolomite and calcite were 940 and 640 g kg -1 , respectively. A time of 8 h was enough to completely remove all carbonates. Neither the content nor the d 13 C of organic C were significantly affected by fumigation. In contrast, N contents were altered by acid treatment. Based on these results and on our experience in analyzing more than 1000 soil samples, a recommended procedure for acid fumigation of carbonate-containing soils with a wide range of organic-and inorganic-C contents was derived. Samples pretreated in this way can be analyzed reliably for their organic-C content and d 13 C. Furthermore, N and inorganic-C contents can be determined with a quality sufficient for many purposes.

Organic matter dynamics along a salinity gradient in Siberian steppe soils

“…2.4 Determination of organic carbon, δ 13 C, and total nitrogen Ball-milled < 2 mm fractions were measured for OC, TN, δ 13 C via dry combustion in an Elementar vario MICRO cube C/N Analyzer (Elementar Analysensysteme GmbH, Hanau, Germany) coupled to an IsoPrime IRMS (IsoPrime Ltd, Cheadle Hulme, UK) after removing inorganic C through fumigation with HCl and subsequent neutralization over NaOH pellets (modified from Walthert et al, 2010). The measured δ 13 C values were corrected by calculating response factors from standard compounds (CaCO 3 , cellulose, caffeine) and Figure 1.…”

Patterns of earthworm communities and species traits in relation to the perturbation gradient of a restored floodplain

“…gravels of various sizes; large > 5 cm, medium > 2 cm, small) of the uppermost 5 cm of soils were visually estimated in situ following the key of Baize and Jabiol (1995). For organic (OC), total carbon (C) and total nitrogen (N) measurements, three cores of 10 cm depth and 6 cm diameter were extracted at each sampling site, homogenised and sieved at 2 mm, and measured following the methods of Walthert et al (2010). The minimum flow rate required to flood each habitat was determined by Samaritani et al (2011) from inundation maps produced by digital terrain modelling based on river cross section measurements.…”

Modern comprehensive approach to monitor the morphodynamic evolution of a restored river corridor

“…The texture has been measured using the pipette method (Gee and Bauder, 1986). Organic carbon and total nitrogen have been measured in finely ground fine soils by using the method by Walthert et al (2010). Available phosphorus has been measured colorimetrically by following the approach of Kuo (1996).…”