Phytoremediation potential of kenaf--Bridgeton Westlake Landfills

MOhemp Energy is exploring the Legal to grow Kenaf Plant for the Westlake and Bridgeton Landfills Natural Remediation Project.  

Here is information from a past study:

Phytoremediation potential of kenaf (Hibiscus cannabinus L.) grown in different soil textures and cadmium concentrations

This study investigated effect of soil textures and cadmium (Cd) concentrations on the growth, fibre yields and Cd absorption of kenaf. 

Screen-house experiment was conducted in the University of Agriculture, Abeokuta (UNAAB), Ogun State, Nigeria. Top soils were collected from Murtala Victoria Botanical Garden, Epe, Lagos State, Nigeria and UNAAB Teaching and Research Farm. 

Highlights Kenaf Phytoremediation Study that is posted on the Google Cloud at this link.

• Ten-litre plastic pots were filled with 10 kg soil. Experimental design was a 2 × 5 factorial in RCBD replicated three times.
• Two soil textures and five levels of Cd concentration (as Cadmium nitrate): 0, 1.5, 3.0, 4.5 and 6.0 mgCd/kg soil. Growth and yield parameters were collected. 
• Cd content of plants and soils were determined using AAS and analyzed using descriptive statistics, ANOVA and correlation. UNAAB soil had pH of 6.3 with sandy loam texture while Epe soil had pH and texture of 5.3 and sand respectively. 
• Control had significantly (P<0.05) higher plant height, stem girth, bast and core yields while 6.0 mg/kg had the least in the two soils. 
• The more the concentration of Cd applied, the higher was the absorption by kenaf in the two soils. 
• Kenaf planted in Epe soil had better absorption than UNAAB soil. 
• There was significant (p < 0.01) positive correlation between Cd applied and Cd absorbed by kenaf. 
• Key words: Phytoremediation by kenaf, soil textures, cadmium concentrations. 
• Remediation by conventional technologies is very expensive and it has been estimated that the cost of conventional remediating heavy metal-contaminated sites in the USA alone would exceed $7 billion (Salt et al., 1995)

The best type of soil for kenaf production is a well-drained sandy loam soil; sand soil is not recommended for kenaf production as plant growing in such soil bloom rather early, without attaining sufficient height; consequently low yields are obtained from such soil (Dempsey, 1975). The higher the concentration of Cd applied, the more was the Cd absorption by kenaf in UNAAB and Epe soils (Table 3). In the two soils, kenaf planted in 6.0 mgCd/kg soil had significantly (p <0.05) highest Cd absorption followed by kenaf planted in 4.5 mgCd/kg soil, 30 mgCd/kg soil, 1.5 mgCd/kgsoil and control respectively. This might probably be due to the amount of metal in the soil. ZhenGuo et al. (2002) and Arthur et al. (2003) reported that phytoextraction and uptake of heavy metal is enhanced by its availability and concentration in the soil. Comparing the Cd absorption of kenaf planted in UNAAB and Epe soils, the kenaf in Epe soil had better absorption than the one in UNAAB soil at every concentration level. With reference to 6.0 mgCd/kg soil, kenaf planted in UNAAB soil absorbed more than the one planted in Epe soil by 2.2%. However, bioavailability index has been used to demonstrate the ability of plants to accumulate heavy metals (Rotkittikhun et al., 2006). Epe soil also had higher bioavailability index than UNAAB soil at every concentration level (Table 3). The difference in pH (UNAAB soil 6.3 and Epe soil 5.3) and soils textures might responsible for better absorption of kenaf in Epe soil. Arthur et al. (2003) similarly observed that mobility and bioavailability of metals for plant uptake is enhanced at lower soil pH. Cd levels of UNAAB and Epe soils after harvesting decreased compared to the applied concentrations before planting (Table 4). The higher the concentration of Cd applied to the soils before planting, the more was the content in the soil after harvesting with 6.0 mgCd/kg soil had significantly (p < 0.05) highest level of Cd followed by 4.5 mgCd/kg soil, 3.0 mgCd/kg soil, 1.5 mgCd/kg soil and control respectively in the two soils. Pearson correlation analysis established that Cd concentration applied was positively correlated with Cd absorbed by kenaf (r = 0.99, p < 0.01 in UNAAB soil; r = 1.00, p < 0.01 in Epe soil) and with residual Cd in the soils after harvesting (r = 0.99, p < 0.01 in UNAAB soil; r = 0.96, p < 0.01 in Epe soil). CONCLUSIONS AND RECOMMENDATIONS Growth and yield parameters of kenaf reduced with increased in cadmium concentrations. Ability of kenaf to absorb cadmium varied with soil texture, soil pH, and concentration of cadmium in the soil. Further research could also be carried out on other varieties of kenaf at much higher concentrations of cadmium and at varying soil pH.