Impact of Biochar and Lime on Phytoavailability of Pb and Cd in a Contaminated Soil

R M Boro,N Gogoi,N Baruah

doi:10.4038/tar.v32i2.8460

Abstract

Current study was conducted to evaluate the efficiency of water hyacinth (Echhornia crassipes) biochar and lime to remediate cadmium (Cd) and lead (Pb) contaminated soils. A pot experiment was carried out treating soil with Cd and Pb (both separately and in combination) at the rates of 3, 6, 9 mg/kg and 250, 500, 750 mg/kg, respectively. Biochar and lime were applied separately to the metal spiked soils at the rate of 5.54 g/kg and 2.77 g/kg, respectively. After growing metal accumulator plant Eleusine indica for five months, metal contents were examined in plant biomass (composite sample prepared mixing equal amount of both root and shoot). Water hyacinth biochar had higher efficiency (up to 72%) to reduce phytoavailability of Pb compared to Cd for E. indica when applied in metal spiked soil. However, lime application restricted the availability of Cd to E. indica up to 38.8% compared to control. Documented greater microbial biomass carbon (MBC) and chlorophyll content under application of water hyacinth biochar than lime indicates its higher efficacy for growth of plants and microbes in Pb and Cd contaminated soil due to supply of nutrient in the soil. Therefore, the water hyacinth biochar and lime have potential to reduce bioavailability of Pb and Cd in contaminated soil.

Highlights

Heavy metals are noxious to the environment and possess pronounced threats to human and other organisms, create huge financial issues like removal costs and restoration problems (Chapman et al, 2013)
The soil amendments can aid in heavy metal remediation either through (i) metal immobilization that is reducing the bioavailability to plants, animals and humans or (ii) metal mobilization that is through increasing bioavailability to plants enhancing phytoremediation or phytoextraction
The present study aimed to evaluate the effect of water hyacinth biochar and lime on reducing phytoavailability of Cd and Pb in laboratory contaminated soil with single and mixture of two metals

Summary

INTRODUCTION

Heavy metals are noxious to the environment and possess pronounced threats to human and other organisms, create huge financial issues like removal costs and restoration problems (Chapman et al, 2013). In the present study Eleusine indica plant was employed to test phytoavailability of cadmium (Cd) and lead (Pb) under application of water hyacinth biochar and lime. Water hyacinth is a well-known baleful weed, produce huge biomass due to unstoppable colonization, which cannot be eliminated completely This can be utilized for producing biochar and compost to improve soil nutrient and may help in remediation of metal contamination. Many experiments demonstrated the capability of lime to reduce heavy metal uptake by plants (Hong et al, 2007; Kibria et al, 2011; Xiao et al, 2017) Under these contexts, the present study aimed to evaluate the effect of water hyacinth biochar and lime (calcium carbonate) on reducing phytoavailability of Cd and Pb in laboratory contaminated soil with single and mixture of two metals. The study hypothesised that the soil amendments will behave differently to the different metals and mixed metal contaminated soil

METHODOLOGY

RESULTS AND DISCUSSION

CONCLUSIONS