A new method for the estimation of total dissolved salts in saturation extracts of soils from electrical conductivity

Abstract

We have determined electrical conductivity (E,) and total dissolved salts (S ) in saturation extracts from 39 soil samples from the Baza basin (Province of Granada, south-east Spain). E, ranged from 2.8 to llOdS m-', and S from 2 to 4448 dm-3.The relationship between S and E, was not linear. When the saturation extracts were diluted with progressively larger quantities of distilled water and their electrical conductivity calculated (E,,) with the equationwhere Ed and E , are the conductivity of the diluted extract and the distilled water and f is the dilution factor, the relationship between S and E,, tended to become linear.The highest linear correlation coefficient relating S (mgdm-3) and E,, (dS m-') was reached when Ee, values were calculated for dilutions with a conductivity (Ed) between 0.1 and 0.3 dS rn-'(g,). The regression equation was S = 490 qc with r2 =0.999. This relationship can be used in all saturation extracts, regardless of the concentration and type of ions present.

Toxicity assessment using Lactuca sativa L. bioassay of the metal(loid)s As, Cu, Mn, Pb and Zn in soluble-in-water saturated soil extracts from an abandoned mining site

“…This may be due to dilution which diminishes the intensity of the interactions that take place in the saturation extract (ionicpairs formation, common-ion effect, etc. ), so according to Simón et al (1994) this parameter could be considered a better estimator of the true salinity of the samples.…”

“…Finally, S was calculated by multiplying the EC a obtained by the factor 490 according to Simón et al (1994). This expression can be used in all saturation extracts, regardless of the concentration and type of ions present.…”

“…. In order to obtain the best estimate of salinity (S) from EC (Simón et al 1994), aliquots of saturation extracts were diluted with progressively larger quantities of distilled water until the EC of the diluted extracts ranged between 0.1 and 0.3 dS m −1 . Then, adjusted electrical conductivities (EC a ) were estimated according to Eq.…”

Electrolytic Conductivity of Semiarid Soils (Southeastern Spain) in Relation to Ion Composition

“…Richards (1974) established a lineal relationship between EC and total dissolved salts (TDS), while other authors have demonstrated that a lineal correlation does not always exist between the EC and the corresponding ionic species Chang et al, 1983;Darab et al, 1980;Rhoades et al, 1989;Simo´n et al, 1994). The formation of ionic pairs, mainly Ca 2 þ , Mg 2 and SO 4 2 À ions (Alzubaidi & Webster, 1983;Timpson & Richardson, 1986), in highly saline solutions is the main cause of this anomaly, because ion mobility in the extract is decreased (Csillag et al, 1995;Darab et al, 1980;Marion & Babcock, 1976;Sposito, 1984).…”

Soil salinization in the agricultural lands of Rhodope District, northeastern Greece

“…Many authors have studied the possible relationship between ECe and the salt concentration of a soil, in an attempt to assess the validity of this parameter as an indicator of soil salinity. Richards (1974) established a linear relationship between EC and total dissolved salts, while other authors have demonstrated that a linear correlation does not always exist between the EC and the corresponding ionic species (Alvarez et al 1997;Chang et al 1983;Darab et al 1980;Rhoades et al 1989;Simon et al 1994). The formation of ionic pairs, mainly Ca 2+ , Mg 2+ , and SO 2− 4 ions (Timpson and Richardson 1986), in highly saline solutions is the main cause of this anomaly, because ion mobility in the extract is decreased (Darab et al 1980; Csillag et al 1995;Marion and Babcock 1976;Sposito 1984).…”