Yong Ho Lee

Disinfection of wheat grains contaminated with Penicillium oxalicum spores by a supercritical carbon dioxide-water cosolvent system.

Spores of the plant pathogenic fungus Penicillium oxalicum inoculated onto wheat grains were inactivated using supercritical carbon dioxide (SC-CO(2)). After the SC-CO(2) treatment at various conditions of temperature, time and amount of water cosolvent, the colony forming units (CFU) of fungal spores on wheat grains and the germination yields of wheat grains were determined. Among these SC-CO(2) treatment parameters, the inactivation of P. oxalicum spores was found to be significantly increased by adding water cosolvent. The optimal conditions determined by ridge analysis of response surface methodology were 233 μL water, 44°C, and 11 min, which resulted in a 6.41 log(10) CFU reduction of P. oxalicum. However, the germination yields of wheat grains significantly decreased when water cosolvent of 150 or 300 μL was added to the grains contained in the 100 mL SC-CO(2) treatment vessel.

Herbal Flora and Succession of Stream Under Management Conditions After its Restoration - Case Study of Yangjaecheon in Seoul -

This study was conducted to examine the change of flora and plant species diversity between 2005 and 2010 in Yangjaecheon (stream) which was divided among three different types of vegetation management method; ecological vegetation management (weeding vines and invasive plants; EVM), plant cultivation (PC) and uncared for vegetation (UC). There were total 478 taxa, composed by 429 spontaneous taxa and 49 cultivated taxa in 2005 and total 424 taxa composed by 318 spontaneous taxa and 106 cultivated taxa in 2010. In spontaneous plants, 201 taxa were distributed over total area, 197 taxa were distributed in only EVM area, 10 taxa in only PC area and 59 taxa in only UC area. Also, the most dominant family (AsteraceaePoaceae) and number of rare taxa (reduced) and wide distributed taxa (increased) was changed from 2005 to 2010. The rate of perennial taxa was found to be increased in only EVM area. In conclusion, EVM is thought to be a more efficient method for plant species diversity of restored stream.

Analysis of Weed Vegetation in Vicinity of Abandoned Mines

Field study to find appropriate species for phytoremediation and phytomonitoring with higher plants was carried out at four abandoned metalliferous mines. In order to know the tolerant degree of plant resources collected at heavy metal polluted sites, soil and plants were sampled at same sites and metal concentrations were determined. Most serious heavy metal polluted in the sites was As that showed range from 29.1 to 1372.2 mg in investigated area. The dominant species were Oenothera biennis, Commelina communis, Persicaria senticosa, Conyza annuus, Artemisia princeps, and Erigeron canadensis. These species were predominant species that were proliferated in any survey area. Compared with other sites, vegetational characteristics of Dal-Seong, a mine site abandoned early in 1973, showed higher diversity index and lower dominance index. Distributions of weed species according to life cycle indicated that the proportions of perennial plants were lowered in every investigated site. Although the polluted areas were distant from each other, similarity indices among these vegetation were relatively similar. These results means the vegetations of abandoned mine areas were beginning stage of vegetational succession, and the vegetations were adversely affected by disturbance with heavy-metals and lack of water in soil.