Jwa-Kyung Sung

Effects of pyrolysis temperature on soybean stover- and peanut shell-derived biochar properties and TCE adsorption in water

Conversion of crop residues into biochars (BCs) via pyrolysis is beneficial to environment compared to their direct combustion in agricultural field. Biochars developed from soybean stover at 300 and 700 °C (S-BC300 and S-BC700, respectively) and peanut shells at 300 and 700 °C (P-BC300 and P-BC700, respectively) were used for the removal of trichloroethylene (TCE) from water. Batch adsorption experiments showed that the TCE adsorption was strongly dependent on the BCs properties. Linear relationships were obtained between sorption parameters (K(M) and S(M)) and molar elemental ratios as well as surface area of the BCs. The high adsorption capacity of BCs produced at 700 °C was attributed to their high aromaticity and low polarity. The efficacy of S-BC700 and P-BC700 for removing TCE from water was comparable to that of activated carbon (AC). Pyrolysis temperature influencing the BC properties was a critical factor to assess the removal efficiency of TCE from water.

Monitoring of selected veterinary antibiotics in environmental compartments near a composting facility in Gangwon Province, Korea.

Many studies have been recently reported that veterinary antibiotics released into the environment have a detrimental effect on humans such as the occurrence of antibiotic-resistant bacteria. However, only limited information is available regarding to the release of antibiotics in environmental compartments in Korea. Objectives of this study were to evaluate the concentrations of antibiotics in water, sediment, and soil adjacent to a composting facility in Korea and to determine the dilution effects of antibiotics when released into the environment. Seven antibiotics of chlortetracycline, oxytetracycline, tetracycline, sulfamethazine, sulfamethoxazole, sulfathiazole, and tylosin were evaluated by high-performance liquid chromatography–tandem mass spectrometry following pretreatment using solid-phase extraction to clean the samples. Results showed that the highest concentration of each antibiotic in both aqueous and solid samples was detected from a site adjacent to the composting facility. We also found that the studied water, sediment, and soil samples are contaminated by veterinary antibiotics throughout comparison with studies from other countries. However, relatively lower concentrations of each antibiotic were observed from the rice paddy soil located at the bottom of the water stream. Further research is necessary to continuously monitor the antibiotics release into ecosystems, thereby developing an environmental risk assessment.

Metabolomic profiling from leaves and roots of tomato (Solanum lycopersicum L.) plants grown under nitrogen, phosphorus or potassium-deficient condition.

Specific metabolic network responses to mineral deficiencies are not well-defined. Here, we conducted a detailed broad-scale identification of metabolic responses of tomato leaves and roots to N, P or K deficiency. Tomato plants were grown hydroponically under optimal (5mM N, 0.5mM P, or 5mM K) and deficient (0.5mM N, 0.05mM P, or 0.5mM K) conditions and metabolites were measured by LC-MS and GC-MS. Based on these results, deficiency of any of these three minerals affected energy production and amino acid metabolism. N deficiency generally led to decreased amino acids and organic acids, and increased soluble sugars. P deficiency resulted in increased amino acids and organic acids in roots, and decreased soluble sugars. K deficiency caused accumulation of soluble sugars and amino acids in roots, and decreased organic acids and amino acids in leaves. Notable metabolic pathway alterations included; (1) increased levels of α-ketoglutarate and raffinose family oligosaccharides in N, P or K-deficient tomato roots, and (2) increased putrescine in K-deficient roots. These findings provide new knowledge of metabolic changes in response to mineral deficiencies.

Natural and synthesised iron-rich amendments for As and Pb immobilisation in agricultural soil

The immobilisation of heavy metals in contaminated soils is a promising alternative to conventional remediation techniques. Very few studies have focused on the use of iron-rich nanomaterials and natural materials for the adsorption of toxic metals in soils. Synthesised iron-rich nanomaterials (Fe and Zr–Fe oxides) and natural iron-rich materials (natural red earth; NRE) were used to immobilise As and Pb in contaminated agricultural soil. Total concentrations of As and Pb in the initial soil (as control) were 170.76 and 1945.11 mg kg−1, respectively. Amendments were applied into the soil at 1, 2.5 and 5% (w/w) in triplicate and incubated for 150 days. Except for the NRE-amended soil, soil pH decreased from 5.6 to 4.9 with increasing application rates of Fe and Zr–Fe oxides. With addition of Fe and Zr–Fe oxides at 5%, the ammonium acetate (NHO4Ac)-extractable Pb was greatly decreased by 83 and 65% compared with NRE addition (43%). All subjected amendments also led to a decrease in NHO4Ac-extractable As in the soils, indicating the high capacity of As immobilisation. Soil amended with NRE showed a lower ratio of cy19:0 to 18:1ω7c, indicating decreased microbial stress. The toxicity characteristic leaching procedure produced results similar to the NHO4Ac extraction for As and Pb. The NRE addition is recommended for immobilising heavy metals and maintaining biological soil properties.

Alleviation of Salt Stress in Eggplant (Solanum melongena L.) by Plant-Growth-Promoting Rhizobacteria

This study was conducted to elucidate the effects of inoculation with plant-growth-promoting rhizobacteria (PGPR) on eggplant growth, yield, and mineral content under salt stress [0, 25, and 50 mM sodium chloride (NaCl)]. The PGPR strains Xanthobacter autotrophicus BM13, Enterobacter aerogenes BM10, and Bacillus brevis FK2 were isolated from the salt-affected maize and kidney bean fields. The increase in salinity decreased the growth and yield and increased the sodium (Na+) uptake of eggplant. However, inoculation with PGPR strains reduced the negative effects at each level of salinity tested. The E. aerogenes strain was capable of promoting eggplant growth and yield when compared to an uninoculated control. The B. brevis was the most effective strain for reducing the negative effects of salinity, and its effects occurred through increasing the potassium (K+)/Na+ ratio and K+-Na+ selectivity in the eggplant shoots. Inoculation of the eggplant seedlings with PGPR could alleviate the negative effects of salt stress.

Monoculture and Mixture Effects of Green Manure Crops on Soil Quality, Weed Suppression and Organic Red-pepper Production

Organic farming is rapidly expanding worldwide. Crop growth in organic systems greatly depends on the functions performed by soil microbes, and nutrient supply weed suppression by green manure crops input. Four red-pepper production systems were compared: 1) bare ground (conventional system); 2) hairy vetch monoculture; 3) rye monoculture; and 4) hairy vetch-rye mixture. Soil inorganic N reached the peak at 30 DAI and hairy vetch monoculture was the highest (192 mg kg -1 ) and soil total carbon was fluctuated sporadically during the experiment. Carbohydrate and phenolic compounds in soil kept significantly higher in green manure crops systems from 10 DBI to 30 DAI, however the level was the maximum at 10 DBI (carbohydrate) and 30 DAI (phenolic comounds). Incorporation of green manure crops residue enhanced soil microbial biomass C and N throughout the growing season except that MBN in rye was reduced after incorporation. Green manure crops systems suppressed weed occurrence and, in particular, it was prominent in rye monoculture. Mineral elements composition and production in red-pepper fruits were markedly decreased in green manure crops systems although hairy vetch monoculture has come close to bare ground (NPK-applied). Therefore, it was suggested that higher biomass production should be performed not only to improve soil quality and suppress weeds but to yield suitable red-pepper fruits in green manure crops-based organic farming.

Effect of Incorporation of Hairy Vetch and Rye Grown as Cover Crops on Weed Suppression Related with Phenolics and Nitrogen Contents of Soil

Abstract Characterization of the release of degradable components of cover crops is important for determining the quality of soil nutrients for the following crop and weed occurrence. We have examined the temporal changes in soil phenolic carbon (C) and nitrogen (N) after incorporation of cover crops (hairy vetch and rye) with different C to N ratio and their effects on subsequent weed occurrence in the. Cover crops, hairy vetch (Vicia villosa Roth. cv. Hungvillosa) and rye (Secale cereale L. cv. Winter-green), grown in a glass house for 60 days, were harvested and incorporated into soil at the rate of 35 and 25 ton ha-1, respectively. The contents of total phenolics (TP) in hairy vetch- and rye-incorporated soil increased from 45.5 to 21.3 μg g-1 DW and decreased from 17.7 to 37.0 μg g-1 DW, respectively, from 10 to 50 d after incorporation (DAI). Inorganic nitrogen (InN) was substantially released from hairy vetch residues, and it remained over four-fold greater than those in the control or rye-incorporated soil at 30 DAI. In the correlation analysis, the TP content of soil correlated negatively (r=-0.55, P<0.01) with total carbon (TC), but TP content of soil did not correlate with total nitrogen (TN) or inorganic nitrogen (InN) contents of soil. Occurrence of weed species was not significantly different among the treatments, whereas weed density was decreased by the incorporation of hairy vetch- or rye-residues. Weed dry weights observed at 50 DAI revealed that the growth of weeds on hairy vetch-incorporated soil was about ten- and four-fold greater than that on rye-incorporated and control soil, respectively. It is concluded that incorporation of hairy vetch did not suppress weed growth, but incorporation of rye significantly suppressed the emergence and growth of weed.

Understanding of a Korean Standard for the Analysis of Hexavalent Chromium in Soils and Interpretation of their Results

A new Korean standard for the determination of Cr(VI) in soils has been officially published as ES 07408.1 in 2009. This analytical method is based on the hot alkaline digestion and colorimetric detection prescribed by U.S. EPA method 3060A and 7196A. The hot alkaline digestion accomplished using 0.28 M and 0.5 M NaOH solution (pH 13.4) at determines total Cr(VI) in soils extracting all forms of Cr(VI), including water-soluble, adsorbed, precipitated, and mineral-bound chromates. This aggressive alkaline digestion, however, proved to be problematic for certain soils which contain large amounts of soluble humic substances or active manganese oxides. Cr(III) could be oxidized to Cr(VI) by manganese oxides during the strong alkaline extraction, resulting in overestimation (positive error) of Cr(VI). In contrast, Cr(VI) reduction by dissolved humic matter or Fe(II) could occur during the neutralization and acidic colorimetric detection procedure, resulting in underestimation (negative error) of Cr(VI). Futhermore, dissolved humic matter hampered the colorimetric detection of Cr(VI) using UV/Vis spectrophotometer due to the strong coloration of the filtrate, resulting in overestimation (positive error) of Cr(VI). Without understanding the mechanisms of Cr(VI) and Cr(III) transformation during the analysis it could be difficult to operate the experiment in laboratory and to evaluate the Cr(VI) results. For this reason, in this paper we described the theoretical principles and limitations of Cr(VI) analysis and provided useful guidelines for laboratory work and Cr(VI) data analysis.

Synthesis of Nanoscale Zerovalent Iron Particle and Its Application to Cr(VI) Removal from Aqueous Solutions

Zerovalent iron (ZVI) is one of the most commonly used metallic reducing agents for the treatment of toxic contaminants in wastewater. Traditional ZVIs are less effective than nanoscale ZVI (nZVI) due to prolonged reaction time. However, the reactivity can be significantly increased by reducing the size of ZVI particles to nanoscale. In this study, nZVI particles were synthesized under laboratory condition and their efficiency in removing hexavalent chromium (Cr(VI)) from aqueous solutions were compared with commercially available ZVI particles. The results showed that the synthesized nZVI particles (SnZVI) reduced >99% of Cr(VI) at the application rate of 0.2% (w/v), while commercial nZVI (CnZVI) particles resulted in 59.6% removal of Cr(VI) at the same application rate. Scanning electron micro- graphs (SEM) and energy dispersive spectra (EDS) of the nZVI particles revealed the formation of Fe-Cr hydroxide complex after reaction. Overall, the SnZVI particles can be used in treating chromium contaminated wastewater.

The complete chloroplast genome sequence of Glycyrrhiza lepidota (Nutt.) Pursh - An American wild licorice

The wild species are considered as primary and secondary genepools for the world’s most important food crops. Here, we sequenced the complete chloroplast (cp) genome sequence of an American wild licorice, Glycyrrhiza lepidota for the first time to investigate their phylogenetic relationship among inverted-repeat-lacking clade (IRLC) legumes. The total length of the chloroplast genome is 127,939 bp, with 34.2% overall GC content. The chloroplast genome harbors 110 known genes, including 76 protein-coding genes, four ribosomal RNA genes, and 30 tRNA genes. Similar to other closely related plastomes, rpl22 and rps16 are absent. A total of 464 cp microsatellites (cpSSRs) were analyzed in the G. lepidota. The majority of the SSRs in this cp genome are penta-nucleotides (61.6%). Locally collinear blocks (LCBs) identified between the Glycyrrhiza glabra and G. lepidota cp genomes were showed that they were well conserved with respect to gene organization and order. Moreover, the phylogenetic analysis indicates that G. lepidota is closely related to its confamilial counterparts than to the other taxa of the IRLC legumes.