Solubility, sorption and desorption of native and added cadmium in relation to properties of soils in New Zealand

Abstract

Summary Solution cadmium (Cd) concentrations and sorption and desorption of native and added Cd were studied in a range of New Zealand soils. The concentration of Cd in solution and the concentrations and patterns of native soil Cd desorbed and added Cd sorbed and desorbed varied greatly between the 29 soils studied. Correlation analysis revealed that pH was the most dominant soil variable affecting solution Cd concentration and sorption and desorption of native and added Cd in these soils. However, organic matter, cation exchange capacity (CEC) and total soil Cd were also found to be important. Multiple regression analysis showed that the log concentration of Cd in solution was strongly related to soil pH, organic matter and total Cd, which in combination explained 76% of the variation between soils. When data from the present study were combined into a single multiple regression with soil data from a previously published study, the equation generated could explain 81% of the variation in log Cd solution concentration. This reinforces the importance of pH, organic matter and total Cd in controlling solution Cd concentrations. Simple linear regression analysis could at best explain 53% of the total variation in Cd sorption or desorption for the soils studied. Multiple regression analysis showed that native Cd desorption was related to pH, organic matter and total Cd, which in combination explained 85% of the variation between soils. For sorption of Cd (from 2 μg Cd g–1 soil added), pH and organic matter in combination explained 75% of the variation between soils. However, for added Cd desorption (%), pH and CEC explained 77%. It is clear that the combined effects of a range of soil properties control the concentration of Cd in solution, and of sorption and desorption of Cd in soils. The fraction of potentially desorbable added Cd in soils could also be predicted from a soil’s Kd value. This could have value for assessing both the mobility of Cd in soil and its likely availability to plants.

Efeito do pH na adsorção e dessorção de cádmio em Latossolos brasileiros

“…A Cd %ads foi, em média, de 27, 35 e 55 %, para pH 4,5; 5,5; e 6,5, respectivamente. A importância do pH como fatorchave em controlar a adsorção de Cd tem sido demonstrada em vários trabalhos (Naidu et al, 1994;Gray et al, 1998Gray et al, , 1999Krishnamurti & Naidu, 2003). Os dados obtidos neste trabalho estão de acordo com relatos prévios da literatura, segundo os quais o aumento do pH do solo resulta em um aumento da capacidade adsortiva dos mesmos (Alloway, 1990;Kabata-Pendias & Pendias, 2001;Dias et al, 2001).…”

Biochar Types from Latrine Waste and Sewage Sludge Differ in Physico-Chemical Properties and Cadmium Adsorption

“…Step-wise regression analysis was used to identify the best fit model to explain Cd sorption data by removing certain variables based on the t-statistics for estimated coefficients (Gray et al, 1999).…”

Relationship between organic matter humification and bioavailability of sludge-borne copper and cadmium during long-term sludge amendment to soil

“…It is well-known that phenolic hydroxyl and carbonylic functional groups, which are responsible for the strong adsorption to Cd, are absent from sludge (Lee et al, 1996;Gray et al, 1999). Therefore, Cd mobility usually increases once sludge is amended to soil.…”