Mobility of cadmium and lead in soils derived from limestone

 Ariel B. Bolledo1 and Beatriz C. Jadina2

 

1Science Research Assistant, Philippine Higher Education Research Network, Visayas State University (abolledo_ph@outlook.com)

2Associate Professor, Department of Agronomy and Soil Science, Visayas State University (bettyjadina@gmail.com)

 

ABSTRACT

Soil accumulation of heavy metals coming from industrial and municipal wastes poses contamination risk to groundwater resources. A leaching experiment was conducted to determine the mobility and retention of cadmium (Cd) and lead (Pb) in soils derived from limestone and to relate the properties of such soils to the mobility and retention of cadmium (Cd) and lead (Pb). A 2 x 5 factorial leaching experiment consisting of two heavy metals, cadmium (Cd) and lead (Pb), and five different Cd and Pb concentrations (0, 50, 150, 250, 350 mg l) was conducted. Solutions containing Cd(NO3)2·4H20 and Pb(NO3)2 were used as sources of Cd and Pb respectively. The leaching experiment was conducted for 60 hours. Results showed that the electrical conductivity (EC) and pH of the leachates were high at the first 12-h of leaching which decreased as the leaching process was continued. The different concentrations of Cd and Pb did not significantly affect the EC and pH of the leachates. Most of the recovered concentrations of Cd and Pb in the leachates from all the treated soil columns were below the detection limit. In terms of mobility, Pb was found to be more mobile than Cd. However, the concentrations recovered for both Cd and Pb were very low (0.0035 – 1.77 mg l) which implies high sorption of the heavy metals. Hence, mobility of Cd and Pb was not evident in soils derived from limestone. Fractionation analysis of Cd and Pb in soil revealed the dominance of carbonate-bound fractions which supports the observation of heavy metal immobility. High cation exchange capacity and high calcium carbonate content were the soil properties related to mobility of the heavy metals.

Coco char and Poultry litter char effects on Attenuation of Amoeba in a Saturated Sandy Soil

   amoebaAriel B. Bolledo*, 2012 *(abolledo_ph@outlook.com)

 

ABSTRACT

The use of biochar has been shown to affect the transport of pathogenic microorganisms. A transport experiment was conducted to determine the effect of biochar application in soil contaminated with amoeba in relation to its transport in sandy soil and to evaluate the effect of coco char and poultry litter char to the attenuation of amoeba.Poultry litter char and charred coconut shells were used as two different sources of biochar and were incorporated at 10 % (w/w) soil-biochar mixture in a polyvinyl chloride (PVC) column (15 cm height and 2.5 cm diameter). There were three treatments and three replicates. One treatment is applied with coco char and the other was with poultry litter char. Control treatment was with no biochar application. Two hundred fifty amoebas were used in the transport experiment and were leached for 15 minutes. Results showed that 30 % of the total amoeba was leached in the saturated column without biochar compared to the less 8-14 % of the total amoeba in the biochar amended columns. Coco char is more effective in attenuating amoeba with 6% advantage over the poultry litter char. Spatial distribution of amoeba in the soil column showed that the number of amoeba accumulated in shallower depths (2-6 cm) in biochar amended columns compared to columns without biochar. Amoeba in coco char amended column accumulated in 2-4 cm only compared to poultry litter char at 4-6 cm. It is shown that incorporation of biochar effectively attenuated the transport of amoeba in a saturated sandy soil. This is where coco char is superior to poultry litter char in terms of attenuation capacity.

keywords: attenuation, amoeba, sandy soil, coco char, poultry char