Sudokwon landfill in Korea is one of the biggest sanitary landfills in the world and has one of the longest leachate channels in the world. However, the vegetation coverage of the landfill channel is less than 20% (mostly reed) and so the channel might have lost most of its purpose for remediation and revegetation. Therefore, the water depth from 1m to 4m by distance from edge of the channel has been investigated to find out possible habitat areas for plants (33 sites). And 5 native macrophytes, Phragmites australis (reed), Typha angustifolia (narrow leaf cattail – cattail), Phacelurus latifolius, Scirpus tabernaemontani and Zizania latifolia were selected for candidates of planting species for the channel. Rhyzomes of these species were planted in pots filled with sands (10 replicates) and grown in water tanks filled with 100% leachate. Growth, biomass, photosynthesis, nutrient and heavy metal contents of the plants were researched. In following year, Phragmites australis and Typha angustifolia were grown in leachate tank with two leachate depths (10cm and 40cm). Also both species were grown in 4 different fresh water depths (0, 10, 40, 70) for further detailed research by water depth. Ecological and physiological parameters were investigated.
Results/Conclusions
The water depth of the leachate channel by 2m distance from edge was mostly over 70cm. This explains why the vegetation coverage of the channel was low, because maximum water depth of reed (dominant species of the channel) was less than 57cm in leachate channel and other wetlands in Sudokwon landfill. However, cattail species were able to grow over 86cm in other wetlands in the landfill and showed highest biomass and heavy metal uptake in tank experiment. Considering eco-physiological performance and commonness, reed and cattail were selected for further research. In deeper leachate tank, cattail showed much better growth, biomass and heavy metal contents than reed. And in fresh water experiment, reeds could not survive in 70cm depth but cattails have survived. And as water gets deeper, the gap between photosynthetic performance and nutrient contents of two species became more distant. Therefore, cattail species would be better selection, especially for deep areas of the leachate channel. Considering diversity and commonness (reed is the most common macrophyte), transplanting reeds in shallow areas and transplanting cattails in deeper areas would be reasonable method to increase vegetation coverage for leachate channel system restoration and for remediation ability of the channel.