Measurement of Cadmium Activities in Slightly Acidic to Alkaline Soils

El-Falaky, A. A.; Aboulroos, S. A.; Lindsay, W. L.

doi:10.2136/sssaj1991.03615995005500040013x

Cited by 22 publications

(16 citation statements)

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“…1 only for brevity. Similar relationships have been found for Cd (El‐Falaky et al, 1991) and Zn (Norvell et al, 1987; Singh et al, 1982) using the competitive chelation method. Figure 1 shows that the line of the mole fraction after 5 d shaking intersected the initial mole fraction line at a certain point that reflected neither gain nor loss of Pb (i.e., the equilibrium mole fraction).…”

Section: Resultssupporting

confidence: 77%

“…Gregson and Alloway (1984) found that the soil solutions from contaminated soils contained about 10 −6 M Pb. It is well known that Pb 2+ and Cd 2+ activities increase as soil pH decreases (Lindsay, 1979; Sauvé et al, 1997; Santillan‐Medrano and Jurinak, 1975; El‐Falaky et al, 1991; Japony and Young, 1994). The Pb 2+ activities in our soils as a function of soil pH (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Soil Solid‐Phase Controls Lead Activity in Soil Solution

et al. 2002

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Lead pollution of the environment is synonymous with civilization. It has no known biological function, and is naturally present in soil, but its presence in food crops is deemed undesirable. The concern regarding Pb is mostly due to chronic human and animal health effects, rather then phytotoxicity. However, not much is known about the chemistry and speciation of Pb in soils. We determined the activity of Pb2+, in near neutral and alkaline soils, representative of alluvial, desertic and calcareous soils of Egypt, using the competitive chelation method. Lead activity ranged from 10(-6.73) to 10(-4.83) M, and was negatively correlated with soil and soil solution pH (R2 = -0.92, P < 0.01 and R2 = -0.89, P < 0.01, respectively). It could be predicted in soil solution from the equation: log(Pb2+) = 9.9 - 2pH. A solubility diagram for the various Pb minerals found in soil was constructed using published thermodynamic data obtained from the literature, and our measured Pb2+ activities compared with this information. The measured Pb2+ activities were undersaturated with regard to the solubility of PbSiO3 in equilibrium with SiO2 (soil). However, they were supersaturated with regard to the solubilities of the Pb carbonate minerals PbCO3 (cerussite) and Pb3(CO3)2(OH)2 in equilibrium with atmospheric CO2 and hydroxide Pb(OH)2. They were also supersaturated with regard to the solubilities of the Pb phosphate minerals Pb3(PO4)2, Pb5(PO4)3OH, and Pb4O(PO4)2 in equilibrium with tricalcium phosphate and CaCO3. The activity of Pb2+ was not regulated by any mineral of known solubility in our soils, but possibly by a mixture of Pb carbonate and phosphate minerals.

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Soil Solid‐Phase Controls Lead Activity in Soil Solution

et al. 2002

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“…Figure 6 shows that the difference in Kd due to the presence of DOM progressively increases as the total Cd concentration decreases; the difference would be especially large at pH 6. El-Falaky et al (1991) found that the log Cd activity in a series of slightly acidic to alkaline soils (pH 6.5 to 8.2) was directly related to the soil pH and ranged from -6.6 to -10.3 with the largest activity at the lowest pH. Our results suggest that such a direct relationship may not be applicable in organic-rich soils.…”

Section: Field-based Partition Coefficients For Truce Elements 219mentioning

confidence: 57%

Field‐based partition coefficients for trace elements in soil solutions

Gooddy

Shand

Kinniburgh

et al. 1995

European J Soil Science

123

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A total of 48 elements was detected in the soil solutions centrifuged from two acid sandy (humusiron podzol) profiles from southern England. Concentrations ranged from mM for the major ions to n M for trace metals such as U and the rare earth elements. Field-based solid/solution partition coefficients, K d , were determined by calculating the ratio of the amount of an element extracted by 0.43 M HN03 or a neutral salt (0.01 M CaC12 or 0.1 M Ba(N03)2) to the concentration in the soil solution. These partition coefficients did not show the expected trend in selectivity. For example, Cd consistently had one of the highest Kd values, higher even than Cu. This was thought to be due in part to the nature of the Kd which reflects a balance between binding to the soil solids and to the dissolved organic carbon (DOC), which is present at relatively high concentrations (1 -20 mM) in the soil solutions. Because of the underlying functional similarity between metal binding by the solid and dissolved organic matter, the partition coefficient (and hence element mobility) will be relatively insensitive to changes in pH and metal-ion activity in the soil solution.

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“…Stability diagrams are used as a convenient technique for illustrating how the solubility of metal compounds varies with soil pH and with metal concentration (or activity). The diagrams also allow some prediction of which solid phase regulates metal activity in the soil solution (El-Falaky et. al., 1991, El-Gendi, 1994, El-Gendi et al, 2017.…”

Section: Introductionmentioning

confidence: 99%

Predicted Speciation and Mineral Solid Phases of some Heavy Metals in Sludge - amended Soil

El-Desoky¹,

Khalafalla²

2018

Journal of Soil Sciences and Agricultural Engineering

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Speciation of heavy metals exerts important controls on chemical behavior, solubility, toxicity, adsorption and even physical properties of solutions (Ure and Davidson 2002). In the present study, speciation and mineral-solid phase of Cd, Ni, and Pb in solution of soil prolonged irrigated with sewage effluent were predicted using GEOCHEM model (Sposito and Mattigod (1980) and constructed stability diagrams (Sposito ,1989 andLindsay ,1979).The present data indicate that total contents of all tested metals have increased dramatically as a result of sludge amending, particularly, for Cd. In virgin soil solution, the results of speciation indicated that, free species M 2+ was the prevalent form (60.35%) followed by carbonate species MCO 3 aq (20.12%), MSO 4 (5.93%), MHCO 3 + (5.56%), MOH + (4.21%) and MCL + (4.21%), while in sludge -soil solution the sequence was; M-DOC (41.92%), followed by MHPO 4 species (26.74%), M 2+ ( 20.07%) , MHCO3 + (4.22%), MSO 4 aq (3.49%) and MCO 3 aq (2.02%). It is clear from the results that amending soil with sludge decreases active portion (M +2 ) contribution to total speciation of the tested metals. In virgin soil, the majority of both Cd and Ni was (M +2 ) species. It amounted (79.03%) and (83.8%) , respectively . While MCO 3 aq was the prominent for pb (55.86%). In sludgesoil, Pb was almost exclusively in organically complexed forms (88.54%), while the majority species of Ni was M +2 (38.56%) and for Cd, CdHPO 4aq (58.72%). The data also showed that in sludge-soil the activities (Ml -1 ) of both Pb and Ni decreased by 26% and 72%, respectively, compared to their corresponding values in virgin soil. Meanwhile, the activity of Cd increased. These findings suggesting that amending soil with sludge probably inhibit activities of some metals, while promote activity of others. The data showed that the values of activities of Cd in virgin soil was closed to the solubility of CdCO 3 (log CO 2 =-2.52) and CdSO 4 -2Cd (OH) 2 at (log So 4 =-2) , while in sludge soil ,the value of Cd +2 was under saturated with respect the constructed Cd-minerals. This suggested that other possible solid phase of cadmium may be controlling its activity in that soil .Also , the data suggested that activity of Ni +2 in virgin soil is governed by Ni 3 (PO 4 ) 2 in equilibrium by gypsite. While in sludge-soil, value of Ni +2 was controlled by Ni 3 (PO 4 ) 2 in equilibrium with Caphosphate mineral at (log CO 2 = -4.52). Also, the results indicated that Pb 3 (CO 3 ) 2 (OH) 2 was the possible solid phase which may be controlled the activity of Pb +2 , in both virgin and sludge soil.

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Measurement of Cadmium Activities in Slightly Acidic to Alkaline Soils

Cited by 22 publications

References 0 publications

Soil Solid‐Phase Controls Lead Activity in Soil Solution

Soil Solid‐Phase Controls Lead Activity in Soil Solution

Field‐based partition coefficients for trace elements in soil solutions

Predicted Speciation and Mineral Solid Phases of some Heavy Metals in Sludge - amended Soil

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