Sorption of Cadmium in Some Soil Amendments for In Situ Recovery of Contaminated Soils (original) (raw)
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Sorption of cadmium in some arable and forest soils
Journal of Radioanalytical and Nuclear Chemistry, 2000
The behavior of cadmium labeled with 109 Cd in different depth horizons of arable and forest soils were studied under static (batch) conditions in three interconnected processes, which consist of sorption, desorption and extraction. In the sorption, Cd 2+ was applied in the aqueous calcium nitrate solution. Both untreated soils and peroxide treated soils were used in order to remove organic matter from some of the soil samples used in parallel. The influence of the V/m ratio on the sorption coefficients was investigated in preliminary experiments with untreated soils. Contrary to the usually short-term sorption, a long-term sorption of cadmium was investigated in untreated and treated soil horizons, which lasted more than fortnight. Kinetic studies of sorption were carried out and cadmium concentration dependence in aqueous phase of the second order kinetic constants was observed. For evaluation of sorption and desorption processes Freundlich isotherms were used. It was found that the Freundlich adsorption intensity coefficient is more time dependent than the absorption capacity coefficient, and the sorption itself consists of rapid and slow processes according to the soil constituents. Desorption and extraction processes revealed the possibility of cadmium recovery from various soil horizons. Based on the obtained results two-or three-stage theory of cadmium retention in soils was proposed. Some new insight into the role of organic matter in the sorption/desorption process of cadmium is also presented.
Cadmium Sorption in Soils 25 Years After Amendment with Sewage Sludge
Soil Science, 2006
Long-term changes in the solubility and bioavailability of heavy metals in soils, accumulated as the result of waste application, cannot be predicted without knowledge of the nature of metal retention in these soils. To test the theory that Fe-and Al-rich mineral phases in sewage sludge-amended soils can act as long-term sinks for heavy metals, soils were sampled from two field sites, each with a similar history of multiyear application of either high-Fe, high-Al, or high-Ca sludge (¨25 years earlier) but with different textural characteristics. These soils were amended with Cd in the form of CdCl 2 in the laboratory to determine Cd solubility as a function of total added Cd over the range of 0 to 20 mg/kg. The slopes of these linear solubility functions, used to determine the strength of Cd sorption, revealed that the high-Fe and high-Al sludge amendments did not improve the soils' affinity for Cd at either site. The high-Al sludge treatment decreased the affinity for Cd in the more coarse-textured soil. The high-Ca sludge amendment, conversely, increased the affinity for Cd, probably a result of the higher soil pH that has persisted since the sludge application. The results suggest that sludge Fe and Al may not be effective in binding Cd in all soils of humidtemperate climates.
Cadmium sorption in biosolids amended soils: results from a field trial
Science of The Total Environment, 2004
The effect of biosolids amendment on cadmium sorption coefficient (K) was determined for soils in a biosolids d field trial. The sorptive properties of biosolids are thought to have a significant controlling effect upon the availabilityy uptake and mobility of potentially toxic metals. K values for the three biosolids were 10-30 times greater than those d for unamended soil. Elevated K values were still apparent 1 and 2 years after biosolids amendment (100 t ha) for y1 d two of the three biosolids. Chemical extractants (sodium hypochlorite and hydrofluoric acid, respectively) were used in an attempt to determine K values of isolated inorganic and organic fractions. For both biosolids amended soils d and unamended controls, Cd sorption appeared to be dominated by the inorganic fraction, potentially indicating the overriding importance of this fraction in controlling metal mobility. However, for the biosolids themselves, the sum of inorganic and organic fraction contributions to K accounted for less than half the K of the whole biosolids. This d d discrepancy was attributed to the loss of highly sorptive water soluble species in both chemical extractions.
Sorption and desorption of cadmium by different fractions of biosolids-amended soils
Journal of …, 2003
not require large additions of biosolids. The phase or phases responsible for this alteration has and continues To evaluate the importance of both the inorganic and organic to be in dispute. Beckett et al. (1979) postulated the fractions in biosolids on Cd chemistry, a series of Cd sorption and "time-bomb" hypothesis in which it is assumed that the desorption batch experiments (at pH 5.5) were conducted on different responsible phase is organic and as the organic material fractions of soils from a long-term field experimental site. The slope of the Cd sorption isotherm increased with rate of biosolids and was decomposes its complexing nature will be lost with a different for the different biosolids. Removal of organic carbon (OC)
Cadmium Sorption by Some Alkaline Soils of North-West India
The 2005 Annual Meeting, 2005
Cadmium adsorption on five alkaline soils of north-west India followed Langmuir equation. The analogues shape of Linear Langmuir plot in each soils at 298 and 313 0 K elucidate that temperature does not change the nature of reaction but influence the bonding energy constant and adsorption maxima for Cd ion. The magnitude of adsorption maxima enhanced with increase in CaCO 3 and organic content in soils. The positive and constant value of differential isosteric heat of adsorption (ΔH) on each soil between 298 and 313 o K elucidate that adsorption of Cd is an endothermic process which leads to precipitation of Cd rather than physical adsorption. However, the variation of ΔH within different soils might be due to variation in their physico-chemical characteristics. Solubility isotherm diagram revealed that CdCO 3 reaction product formed in equilibrated soil-Cd system used for adsorption study. It was concluded from Linear Langmuir plots, differential isosteric heat of adsorption ΔH and solubility isotherm studies that adsorption of Cd in alkaline soils occurred due to precipitation of CdCO 3 mineral.
Assessment of the Use of Natural Materials for the Remediation of Cadmium Soil Contamination
PloS one, 2016
Rice plants accumulate cadmium (Cd2+) within the grain, increasing the danger of human exposure. Natural materials have been used in soil remediation, but few studies have examined the risks (based on the bioavailability of these metals to plants) of using these materials, so the practice remains controversial. In the present study, we evaluated the effectiveness of biochar produced from sugarcane bagasse, vermicompost (VC), vermicompost solid residue (VCR) and humin for remediation of Cd2+-contaminated soils. We characterized the interactions between these materials and Cd2+ and evaluated their capacity to alter Cd2+ availability to rice plants. Our results show that under the conditions in this study, biochar and humin were not effective for soil remediation. Although biochar had high Cd2+ retention, it was associated with high Cd2+ bioavailability and increased Cd2+ accumulation in rice plants. VC and VCR had high Cd2+ retention capacity as well as low Cd2+ availability to plants...
European Journal of Soil Science, 1999
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 mg 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 K d value. This could have value for assessing both the mobility of Cd in soil and its likely availability to plants.
Effect of organic matter on the distribution, extractability and uptake of cadmium in soils
Journal of Soil Science, 1993
Distribution and plant uptake of soil Cd as influenced by organic matter and soil type were investigated in a greenhouse experiment. Three soils (a sand, sandy loam and clay loam) were used. The rates of organic matter in its moist state added were 0,20,40, 80, 160 and 320 g kg-.' of the air-dried soil on mass basis. Ryegrass (Lolium mult$orum L.) was used as a test crop. Soil Cd was analysed by a sequential extraction technique and by extraction with I M NH,NO, and 0.005 M DTPA. The exchangeable fraction of Cd as determined by 1 M MgCI, in the sequential extraction procedure increased, whereas the Fe-Mn oxidebound fraction decreased, with increasing levels of organic matter addition in all three soils. The dry matter yields of ryegrass were not affected by the addition of organic matter, but the Cd concentrations in both cuts of ryegrass decreased with increasing amounts of organic matter added. The plant Cd was highly but negatively correlated to soil CEC. At any level of organic matter addition, the decrease in Cd concentration of ryegrass was in the order: sand > sandy loam >clay loam. I N T R O D U C T I O N Cadmium in soils can be associated with several distinct geochemical phases. The distribution of Cd among various chemical forms is of importance with respect to its solubility, mobility and bioavailability, and can be measured by a sequential extraction technique. A five-step sequential extraction scheme developed by Tessier et al. (1979) has been widely used for estimating the mobility and bioavailability of Cd in soils (Kheboian & Bauer, 1987). Under this scheme, selective extractants are used in sequence to determine the following forms of Cd in order of decreasing solubility: 'exchangeable', 'bound to carbonates', 'bound to Fe-Mn oxides', 'bound to organic matter', and 'residual'. Harrison et al. (1981) suggested that the mobility and bioavailability of heavy metals (Pb, Cd, Cu and Zn) decreased approximately in the order of the extraction sequence. The exchangeable fraction may be the most available to plants (Stover et al., 1976). Lake et al. (1984) and Sposito et al. (1982) reported that there was a very low concentration of soil Cd in the soluble and exchangeable forms. Riise et al. (1994) also found that only about 25% of the lo9Cd and stable Cd in soils was in the exchangeable fraction. In contrast, as much as 47 and 60% of the total Cd was found in the exchangeable fraction for salt-and sludge-amended soils, respectively (Bell et al., 1991). Hickey & Kittrick (1984) also reported that the largest amount (37%) of soil Cd was found in the exchangeable fraction. Mahler (1988) found that Cd, either native or sludge-derived, appeared mainly in the carbonate fraction.
Water
Batch-type experiments were used to study cadmium (Cd) and lead (Pb) sorption/desorption on forest soil, vineyard soil and pyritic material samples, on the by-products mussel shell, oak ash, pine bark and hemp waste, and on forest soil, vineyard soil and pyritic material amended with 48 t ha −1 of oak ash, mussel shell, and hemp waste. The main results were that the forest soil showed higher Cd and Pb retention than the vineyard soil and the pyritic material. Regarding the byproducts, sorption was in the following order: oak ash > mussel shell > hemp waste > pine bark, with desorption following an inverse sequence. The pH was the parameter that most influenced Cd and Pb sorption. Cd and Pb sorption curves showed better fitting to the Freundlich than to the Langmuir model, indicating the dominance of multilayer interactions. Oak ash and mussel shell were the amendments causing higher increase in Cd and Pb sorption on both soils and the pyritic material (close to 100% with the oak ash amendment), as well as more a pronounced decrease in desorption. These results could be used to favor an effective management of the by-products studied, which could retain Cd and Pb in soils and degraded areas, preventing water pollution.