However, tropical forest productivity declines when annual rainfall exceeds 2500 mm, likely due to nutrient-leaching limiting plant growth [ 71].
In case of compliance leach test, the results are compared with leaching limit values defined in the Portuguese legislation for waste acceptable at landfills for inert waste.
The cement binder reacted with sulfate released from the AAC waste to form ettringite. Sulfate release was in line with ettringite solubility control and below leaching limits defined by Dutch environmental legislation.
Comparison with leaching limit values for granular waste (mg/kg): inert <0.003; non-hazardous <0.05 and hazardous > 0. 0..
The highest exceeding of leaching limit value for inert waste was registered for the tailings of Sartas (Zn, Cu, Ni, F-, SO42-) and Cutii (Zn, Cu, SO42-) impoundments (Figure 2).
Comparison of the leachable fraction of metals and ions in tailings at a solid-to-water ratio of 1 10 (Table 3) with the leaching limit values for inert waste [35] (Table 6) shows that the requirements are fulfilled only for the Gura Rosiei and Sesei impoundments, while the other tailings cannot be considered of no contamination risk.
Nutrients availability in soil is greatly affected by low pH, coarse texture, soils and by leaching thereby limiting base cations such as Ca+, Mg+and K+.
In addition, acid leaching had limited application due to its highly corrosive nature, besides this process required high cost, acid resistant equipment, and air-tight processing to protect the work environment.
The effect of leaching on the limiting oxygen index (LOI) levels of samples with BbFRs was also investigated.
The ecological role of the studied soils resulting from accumulation of inorganic amorphous Fe, which takes part in anion sorption, thus limiting leaching, was also emphasized.
To better understanding the mechanism of the leaching reaction, the rate limiting step of the process was determined under the optimum conditions and it revealed that diffusion through product layer is the rate controlling step.
