• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.90-95
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• 1998

Soil residues of paraquat (1,1-dimethyl-4,4-dipyridinium dichloride) were determined in apple, pear, grape, and peach orchards for which 15 sites each were selected randomly from the corresponding large-scale production area throughout the country. Strong adsorption capacity measured using wheat bioassay (paraquat concentration required to reduce 50% root growth of wheat, SAC-WB) was also investigated on the orchard soils and the paraquat residue level was calculated against total SAC-WB values (SAC-WB value + paraquat residue). Average bound residue of paraquat on the 60 sites was 6.9 ppm, while paraquat residue in apple orchard reached 20.2 ppm which was the highest among the orchards and was almost double as compared with those in the other three orchards. Loosely bound residue of paraquat determined on the bound residue high top five soils occurred less than 0.5 ppm detection limit. Average SAC-WB value was 276.1 ppm and there were no any correlations between the SAC-WB value and clay content, organic matter content, and cation exchange capacity of the orchard soils. Paraquat residue level of the orchard soils against total SAC-WB recorded 2.43%.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.3
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• pp.66-74
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• 2001

The main purpose of this thesis is to select the appropriate plants for the ecological restoration of coastal land. The soil and vegetation environment survey of the beach where the halophytes live now was executed for the sake. Firstly, the soil survey was done by the physical and chemical survey of beach soil and dumped soil. The soil is mostly sandy loam and sandy clay loam which has silty much. The beach soil where the salt plants live has more organic matters in the content than dumped soil because of the influx of the dead halophytes, a pioneer plant to this area. Secondly the vegetation survey was executed by the halophytes survey in the beach area in order to select the appropriate plants for ecological restoration. The shows two different areas in the vegetation divided by the salt density of soil. Artemisia fukudo, Juncus haenkei, Carex pumila, Silene armeia, Polyponum aviculare etc live in the less salt density area and it doesnt show collected. Salicornia herbacea, Suaeda asparagoides, Aster tripolium, Limonium tetragonum, Suaeda maritima, Scirus fluvitilis, Phragmtes communis, Suaeda japonica, Zoysia sinica etc halophytes live in the more salt density area and there are a few advent plant but many collected. So the salt density of soil limits the vegetation. The selection of appropriate plants for the ecological restoration programs was designed with 3 different standards considering the salt density of soil in the dumped soil area. The plan selection guidelines of thick salt density due to the salt density of soil, and economical efficiency and maintenance because the area is large. The guidelines of middle salt density area were made considering economical efficiency and maintenance because there are salt as well, and it is effective for the scenery if they have normal ecology but their leaves have good color and the flowers are beautiful. However I suggest beautiful flowery plants for the neutral plan area because this area is the entry point of the airport so the view is very important.

• Journal of Wetlands Research
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• v.14 no.1
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• pp.139-146
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• 2012

Stream ecosystems carry out significant functions such as water purification, especially denitrification. However, rapid landuse change since industrialization has altered ecological functions of streams. In this study, we aimed to investigate denitrification rates and their determinant factors in streams with different landuse patterns, and how denitrification rates vary with microtopology within streams. Ten fifth streams of each landuse were selected, and each stream was divided into four microtopological sites within streams - riparian zone, subsoil, and both head and tail parts of sand bars. In situ denitrification rates and physicochemical properties of soil were examined. Denitrification rates of agricultural, urban, and forest streams were $289.62{\pm}70.69$, $157.01{\pm}37.06$, $31.38{\pm}18.65mg$ $N_2O-N\;m^{-2}\;d^{-1}$ respectively. There were no significant differences in denitrification rates depending on microtopology, but the rates in riparian zone were the highest, and the rates in the head parts of sandbars were lower than those of tail parts. The determinant factors for denitrification rates included water temperature, silt and clay contents of soil, inorganic nitrogen, and organic carbon, and these factors all showed positive correlations with denitrification rates. Through this study, we find that landuse pattern in watershed region affects denitrification rates that is one of considerable functions of streams. In addition, estimation of denitrification rates taking into account for microtopology would contribute to developing ecological management and restoration strategy of streams.

• The Korean Journal of Malacology
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• v.32 no.3
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• pp.149-155
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• 2016

To assess the effects of environmental factors on the sustainability of cultured ark shell Scapharca broughtonii production, we investigated the habitat characteristics of shellfish-farming bays (Gangjin Bay, Yeoja Bay, Keoje Bay and Deukryang Bay). We measured the physiochemical parameters (temperature, salinity, dissolved oxygen, nutrients, chemical oxygen demand and Chlorophyll a) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several shellfish-farming bays to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain sizes for Gangjin Bay, Yeoja Bay and Keoje Bay were similar, at the ratio of silt and clay in comparison with Deukryang bay of it. The C/N ratio was more than 5.9, reflecting the range arising from the mix of marine organisms and organic matter. The C/S ratio (more than 4.2) showed that the survey area had anoxic or sub-anoxic bottom conditions. The index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. We suggested that the growth of ark shell Scapharca broughtonii in the shellfish-farming bay was effected by the various environmental conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.2
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• pp.61-68
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• 1975

A laboratory study was conducted to determine the effect of nitrogen mineralization in accordance with addition of calcium silicate and wollastonite on the fresh soil condition. Results are summarized as follows. 1. Nitrogen mineralization due to application of silica materials was rapidly occured in Saweon sand soil than in Honam clay soil. Also wollastonite application more stimulated the nitrogen mineralization than calcium silicate. 2. Silica material application enhanced loss of applied nitrogen by denitrification due to accelerate the nitrification in Suweon sand soil. This tendency was more severe in calcium silicate applicated treatment than in wallasnonite applicated. 3. From these results, nitrogen should be applicated with organic matter to improve the supply of nitrogen nutrient to plant when silica materials were applied.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.316-323
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• 2019

This study was carried out to investigate sedimentary environment changes in Nakdong River sediments. For this purpose, sediments at six sites upstream of Gangjeong-Goryung Weir in the middle of the Nakdong River were collected before and after the rainy season. Particles size, IL, TOC, TN, TP, and SRP were analyzed for the sediment environment. The changes in the watershed environment before and after the rainy season (precipitation, discharge, and SS concentration) were investigated. After the rainy season, the amount of precipitation and discharge increased more than three times, and the average concentration of SS in the stream increased more than two times. Fine grained sediment and the concentrations of IL, TOC, TN, TP, SRP were increased after the rainy season. As a result of sediment contamination assessment, IL was 19~68% of the reference value, TN and TP were 21~76% and 21~58% of the reference value. The result showed strong correlation between particle size (Silt+Clay) and organic contents of sediment (IL, TOC, TN, TP and SRP). It is considered that the change of the river watershed environment (precipitation, discharge) is an important factor of the change of sedimentation environment.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.419-424
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• 2008

Objective of this study was to evaluate the adaptation and the soil conservation effect of improved wild vine in sloped upland of highland about 600m from sea level in Korea. A mainly producing district of the improved wild vine in Korea was distributed 230m to 540m from sea level, and its rainfall ranged 1,200 to 1,700 mm. The lowest temperature was from -19.6 to $-25.4^{\circ}C$. Their soil texture was from sandy loam to clay loam, where drainage class was well drained and the contents of soil organic matter and total nitrogen in the improved wild vine's cultivation area were higher than those of Chinese cabbage's cultivation area in the highland. According to improved wild vine's cultivation methods, the amounts of soil erosion were 25.5,4.1, and $1.8MT\;ha^{-1}$ in clean culture, part sod + mulching, and nature sod, respectively. Those were below 30 to $80MT\;ha^{-1}$ of sloped upland at highland in Korea. The result suggests that it is possible to cultivate the improved wild vine over wintering at 600m of highland above the sea level. We can substitute the improved wild vine for Chinese cabbage in the highland for soil conservation.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.115-126
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• 2017

There is an increasing concern over arsenic (As) contamination in rice. This study was conducted to develope a prediction model for As uptake by rice based on the physico-chemical properties of soil. Soil and brown rice samples were collected from 46 sites in paddy fields near three different areas of closed mines and industrial complexes. Total As concentration, soil pH, Al oxide, available phosphorus (avail-P), organic matter (OM) content, and clay content in the soil samples were determined. Also, 1.0 N HCl, 1.0 M $NH_4NO_3$, 0.01 M $Ca(NO_3)_2$, and Mehlich 3 extractable-As in the soils were measured as phytoavailable As concentration in soil. Total As concentration in brown rice samples was also determined. Relationships among As concentrations in brown rice, total As concentrations in soils, and selected soil properties were as follows: As concentration in brown rice was negatively correlated with soil pH value, where as it was positively correlated with Al oxide concentration, avail-P concentration, and OM content in soil. In addition, the concentration of As in brown rice was statistically correlated only with 1.0 N HCl-extractable As in soil. Also, using multiple stepwise regression analysis, a modelling equation was created to predict As concentration in brown rice as affected by selected soil properties including soil As concentration. Prediction of As uptake by rice was delineated by the model [As in brown rice = 0.352 + $0.00109^*$ HCl extractable As in soil + $0.00002^*$ Al oxide + $0.0097^*$ OM + $0.00061^*$ avail-P - $0.0332^*$ soil pH] ($R=0.714^{***}$). The concentrations of As in brown rice estimated by the modelling equation were statistically acceptable because normalized mean error (NME) and normalized root mean square error (NRMSE) values were -0.055 and 0.2229, respectively, when compared with measured As concentration in the plant.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.55-58
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• 2004

The objective of this study was to get information about water retention characteristics of horticultural substrates used in Korea determined by European standard method. Water retention curves were prepared at water volume (v/v, %) in relation to -10 cm, -50 cm, -100 cm water pressure head. Water retention curves showed different properties depending upon the type, the place of origin, particle size, and manufacturing processes of substrates. Peat and coir had easily available water content in the range of 30-40% and showed high water holding capacity, water buffering capacity, and aeration for plant growth. However, bark, sawdust and rice hull showed low water holding capacity about below 10%. The easily available water content of perlite and clay ball was low about 0.1-13.8%, whereas that of vermiculite and rockwool granulate was high about 25.9-52.0%. Understanding water retention characteristics of growing substrates is very important in cstablisliing optimum condition for plant growth. Further study on water retention curves for more substrates, mixture and growing media is needed.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.3
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• pp.234-238
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• 1989

This study was carried out to find out favorable soil conditions to give good quality of Scutellaria baicalensis George for Korean medicine. The samples were collected from the 7 fields of An-dong gun and Eui-sung gun. The plants were grown under soils of different physicochemical properties and the available constituents from their roots were analyzed by HPLC. The average N, P, K contents in roots was determined to be 0.28-1.26%, 0.17-0.46% and 1.00-1.49%, respectively. The baicalin contents of root was determined to be 11.41-14.76% (An-dong gun) and 13.67-16.31% (Eui-sung gun). The contents of N, P in root were negatively correlated with the contents of exchangeable cations (K, Ca, Mg), clay and organic matter in soil, whereas it was not significant with the contents of total nitrogen and available phosphorus of surface soils. The baicalin contents was positively correlated with the exchangeable potassium contents in soil, but negatively correlated with nitrogen and phosphorus contents in the root of Scutellaria baicalensis George.