Assessment of Heavy Metals Immobilization in Artificially Contaminated Soils Using Some Local Amendments

Abstract

<span>Three alluvial soil samples with different textures were artificially polluted with chloride solutions of Cd, Pb, Co and chromate solution for Cr. The aqua-regia extracted concentration ranges in the artificially polluted soils were 1134</span><span> </span><span>-</span><span> </span><span>1489 mg·kg^-¹ for Pb, 854</span><span> </span><span>-</span><span> </span><span>938 mg·kg^-¹ for Cr, 166</span><span> </span><span>-</span><span> </span><span>346 mg·kg^-¹ for Co and 44 </span><span>-</span><span> 54 mg·kg^-¹ for Cd. The aqua-regia extracted metals were the highest in the spiked clay soil due to its high adsorption capacity. Rock phosphate (PR), lime-</span><span>stone (LS) and Portland-cement (Cem) were mixed with the spiked soils at 1% and 2% rates (w/w) and incubated at 30 C for 2, 7, 14, 30, 60, 150 and 360 days. The extracted DTPA metals significantly decreased with different magnitudes with increasing the incubation period accompanied by increases in both pH and EC. The data showed that cement (Cem) treatment dropped the DTPA-Pb from @ 1000 to @ 400 mg·kg^-¹ in all the studied soils (60% decrease) in the first 2 months while it gradually decreased from 400 to 200 mg·kg^-¹ (20% decrease) in the next 10 months. Limestone (LS) and rock phosphate (PR) materials were relatively less effective in lowering DTPA-Pb after 12 months of incubation. The data showed also that cement (Cem) treatment was the most effective one in lowering DTPA-Cd by @ 60% as compared to the un-amended soils after 12 months of soil incubation. Extractable DTPA-Co and Cr showed consistent decreases with time down to nearly 50% of un-amended soils due to the effect of the added amendments after 12 months of incubation with superior reductions for the cement treatment in all the investigated soils. The statistical analysis confirmed that in all the studied metals and treatment, cement treatment (Cem) was significantly the most ef</span><span>fective in lowering the DTPA extracted metals as indicated from LSD test. It was found that up</span><span> </span><span>to 73% and 57% of the applied Pb and Cd, respectively, were fixed by only 1% cement. However, the present study showed that from the prac</span><span>tical and economic points of view, that 1% Cement was the best treatment to immobilize Pb and Cd from all the artifi</span><span>cially polluted soils.</span><span></span

Comparative effect of Organic Amendments on Heavy Metals Adsorption in Soils and their Chemical properties

“…Higher pH was observed in soils that received both amendments and heavy metals than soils that received only heavy metals as shown in Table 3. The results agree with the findings of [29], [30] who observed that application of farmyard manure caused an increase in soil pH and [17] who obtained significant effect of amendment on soil pH. Lead combined with poultry manure had the highest significant (P<0.05) effect on pH followed by zinc plus poultry manure that was significantly different (P<0.05) but not different from copper plus poultry manure and zinc mixed with cocoa pod.…”

“…The metal salts were thoroughly mixed with the soils to homogenize the distribution of the applied heavy metals and allowed to incubate for thirty days. Each soil was wetted daily with 80 ml of distilled water throughout the incubation period at room temperature to mimic natural field condition as stipulated by [17].…”

Chemical stabilisation of lead in shooting range soils with phosphate and magnesium oxide: Synchrotron investigation

“…A soluble form of phosphorus such as phosphoric acid or triple super phosphate which drives down the soil pH may be used to convert as much Pb as possible to pyromorphite. This may require the addition of excess P, which has potential negative consequences including mobilisation of Sb [19,71] and potential eutrophication [16,72].…”

Evaluation of the influence of mechanical activation on physical and chemical properties of municipal solid waste incineration sludge

“…Therefore, the compliance to the SQD requirements in these conditions indicated the adequacy of the leachates also for the column test, applied in the SQD. As performed in other studies (Abdel-Kader et al, 2013), the retention rate, indicating the rate of retained ions in the system after leaching test in the presence of PC, was calculated using the formula:…”