Title of Thesis
Phytoremediation of Tannery Effluents and
Associated Contaminated Soil of Kasur District
Department of Botany / University of the Punjab,
|Number of Pages|
|Keywords (Extracted from title, table of contents and
abstract of thesis)|
Effluents, Associated, Contaminated, Soil, Kasur, District, Lemna, Eichorrnia, Spinacea oleracea
Four hydrophytes namely. Eichorrnia crassipes, Lemna minor, Azolla pinnata. and Pistia stratiotes were evaluated for their tolerance towards different levels of contamination and their potential for phytoremediation. Lemna minor was found relatively more tolerant among the four selected plant species and flourished well in tannery effluent concentrations upto 25% strength. Rest of the three species could not tolerate even 25% level of contamination and decay after few days of effluent treatment. The experiment was repeated for Eichorrnia crassipes and Lemna minor with lower concentrations of tannery effluents. Lemna minor was found to be the best tolerant in the low concentration of effluents(less than 20%). Eichorrnia could survive only for a few days and gradually decayed even in lower concentrations.
This study has demonstrated promising potential for Cr and Na phytoextraction by Lemna minor. Plant removed approximately upto 100% Cr and 80% Na respectively when grown in diluted tannery effluents. However, Eichorrnia could not survive in the effluents well but did reduce the metal content from tannery effluents. It was concluded that using these plants tannery effluents can be considerably cleaned when their concentrations are less than 20%.
Seven crop plants species of different agronomic importance, size and dry matter production namely, Brassica campestris var. Toria A, Brassica juncea var. Khanpur rays, Triticum aestivum var. V93BT022. Sorghum bicolor var. 1S.2002, Trifolium alexandrianum var. Pushed Bcrseem, Helianthus annuus var. FH 298 and Spinacea oleracea var. Desi Palak were tested for their tolerance towards tannery effluent contamination of soil and potential for Na and Cr uptake from contaminated soil in the presence and absence of EDTA as a chelating agent. All the selected species of plants could tolerate the level of applied contamination. Spinacea oleracea was found to be the best tolerant followed by Brassica spp.
Twelve naturally growing wild plant species namely Panicum antidotale. Cynodon dactylon, Heliotropium echwaldii. Alternanthera sessilis. Trianthema portulacastrum Chenopodium morale, Rumex dentate, Echinochloa colonum, Suaeda fruticosa, Kochia indica, Calatropis procera. and Dichanthium annulatum were collected from the contaminated sites and were analyzed to estimate their metal uptake ability and biomass production. Suaeda fruticosa was found to be the best among the tested wild plants for greater biomass production and metal uptake as well. Suaeda
fruticosa was further tested in experiments with industrially contaminated soil along with EDTA applications.
All of the tested plants extracted Na and Cr from contaminated soil. The order of First four plants according to their co-efficient of extraction was Spinacea oleracea > Brassica juncea >Brassica campestris> Suaeda fruticosa. These plants are recommended to be grown at the tested contaminated sites with a hope to reduce the contamination upto a considerable extent but after a long time effort.
The EDTA treatment greatly increased the solubility of heavy metals in both industrially contaminated and artificially contaminated agricultural soil with tannery effluents, but this did not result in a large increase in metal concentrations in the plants. High concentrations of available metals in soil pore water after EDTA treatment could pose an environmental risk in the form of ground water contamination.