Field application of electrokinetic remediation for multi-metal contaminated paddy soil using two-dimensional electrode configuration.

In this study, we evaluated the feasibility of in situ electrokinetic remediation for arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated soil, in a pilot-scale field application with two-dimensional electrode configurations. Square and hexagonal configurations with different electrode spacing, 1 m and 2 m, were investigated under a constant 100 V. A square configuration with electrode spacing of 2 m removed 61.5 % of As, 11.4 % of Cu, and 0.9 % of Pb, respectively, and a hexagonal configuration with the same spacing showed a higher removal efficiency in top (59 % of As, 0-0.5 m) and middle (53 % of As, 0.5-1.0 m) layers, but much lower removal efficiency in the bottom layer (1-1.5 m), which was thought to be due to groundwater flow through periodic rise and fall of tides. Fractionation analysis showed that As bound to Fe-Mn oxyhydroxide was the main form of As removed by the electrokinetic process. The two-dimensional configuration wasted less electrical energy by Joule heating, and required fewer electrode installations, compared to the one-dimensional electrode configuration.

Yeosuana aromativorans gen. nov., sp. nov., a mesophilic marine bacterium belonging to the family Flavobacteriaceae, isolated from estuarine sediment of the South Sea, Korea.

A marine bacterium, GW1-1T, capable of degrading benzo[a]pyrene (BaP), was isolated from estuarine sediments of the South Sea (the Korea Strait), Korea, after an enrichment culture maintained for 2 years in a medium supplemented with a mixture of BaP and pyrene. The strain formed yellowish-brown colonies on marine agar 2216. Cells were strictly aerobic, non-motile, Gram-negative rods and produced non-diffusible carotenoid pigments. Optimal growth occurred in the presence of 1 % (w/v) NaCl and at pH 7 and 33-36 degrees C. No growth occurred without supplementation with either CaCl2 or MgCl2, even in the presence of NaCl. Phylogenetic analysis based on the nearly complete sequence of the 16S rRNA gene revealed that the isolate formed a phyletic lineage with the genera Gelidibacter (93.9-94.7 % gene sequence similarity), Subsaximicrobium (93.3 %) and Subsaxibacter (93.9 %). The isolate also showed high sequence similarities to Gaetbulibacter saemankumensis (94.5 %), Algibacter lectus (94.2 %), members of the genus Bizionia (93.6-94.3 %) and Formosa algae (93.2 %), even though it belonged to a different phyletic line. The major respiratory quinones of the isolate were menaquinones MK-5 and MK-6. The DNA G+C content was 51.4 mol%. Dominant fatty acids were i-15 : 0, a-15 : 0, i-15 : 1omega10c and 16 : 1. On the basis of this polyphasic taxonomic evidence, strain GW1-1T is classified as a member of a novel genus and species in the family Flavobacteriaceae, for which the name Yeosuana aromativorans gen. nov., sp. nov. is proposed. The type strain of the type species is GW1-1T (=KCCM 42019T = JCM 12862T).

Novosphingobium pentaromativorans sp. nov., a high-molecular-mass polycyclic aromatic hydrocarbon-degrading bacterium isolated from estuarine sediment.

A Gram-negative, yellow-pigmented, halophilic bacterial strain US6-1T, which degrades high-molecular-mass polycyclic aromatic hydrocarbons of two to five rings, was isolated from muddy sediment of Ulsan Bay, Republic of Korea. The 16S rRNA gene of the isolate showed high sequence similarity to Novosphingobium subarcticum (96.23 %) and Sphingopyxis alaskensis (96.18 %); however, the isolate formed a distinct phyletic line within the genus Novosphingobium. DNA-DNA relatedness between US6-1T and the closest strain N. subarcticum revealed that strain US6-1T was independent from this species. Isolate US6-1T had ubiquinone 10 and a DNA G + C ratio of 61.1 mol%. Major fatty acids were octadecanoic acid (18 : 1omega7), hexadecanoic acid (16 : 1omega7) and 2-hydroxy-myristic acid (14 : 0 2-OH). On the basis of polyphasic taxonomic evidence, strain US6-1T is proposed to represent a novel species in the genus Novosphingobium for which the name Novosphingobium pentaromativorans sp. nov. is proposed. The type strain is US6-1T (= KCTC 10454T = JCM 12182T).