Simple assessment of wind erosion depending on the soil texture and threshold wind velocity in reclaimed tidal flat land

이교석,서일환,양재의,이상필,정현규,정덕영 충남대학교 농업과학연구소 2021 Korean Journal of Agricultural Science Vol.48 No.4

The objectives of this paper were to simply estimate soil loss levels as caused by wind in reclaimed tidal flat land (RTFL) and the threshold wind velocity in the RTFL. For this experiment, RTFL located at Haenam Bay was selected and a total of 150 soil samples were collected at the Ap horizon from the five soil series. The particle distribution curves, including the limit of the non-erodible particle size (D > 0.84 mm) for each Ap horizon soil, show that the proportions of non-erodible particle sizes that exceeded 0.84 mm were 4.3% (Taehan, TH), 8.9% (Geangpo, GP), 0.5% (Bokchun, BC), 1.6% (Poseung, PS) and 1.4% (Junbook, JB), indicating that the amount of non-erodible soil particles increased with an increase in the sand content. The average monthly, daily and instantaneous wind velocities were higher than the threshold friction velocity (TFV) calculated according to the dynamic velocity (Vd) by Bagnold, while the average monthly wind velocity was lower than those of the TFV suggested by the revised wind erosion equation (RWEQ) and wind erosion prediction system (WEPS). The susceptible proportions of erodible soil particles from the Ap horizon soil samples from each soil series could be significantly influenced by the proportion of sand particles between 0.025 and 0.5 mm (or 0.84 mm) in diameter regardless of the threshold wind velocity. Thus, further investigations are needed to estimate more precisely soil erosion in RTFL, which shows various soil characteristics, as these estimations of soil loss in the five soil series were obtained only when considering wind velocities and soil textures.

The Fate and Factors Determining Arsenic Mobility of Arsenic in Soil-A Review

이교석,심호영,이동성,정덕영 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.2

Arsenic which is found in several different chemical forms and oxidation states and causes acute and chronic adverse health effects is a toxic trace element widely distributed in soils and aquifers from both geologic and anthropogenic sources. Arsenic which has a mysterious ability to change color, behavior, reactivity, and toxicity has diverse chemical behavior in the natural environment. Arsenic which has stronger ability to readily change oxidation state than nitrogen and phosphorus due to a consequence of the electronic configuration of its valence orbitals with partially filled states capable of both electron donation and acceptance although the electronegativity of arsenic is greater than that of nitrogen and similar to that of phosphorus. Arsenate (V) is the thermodynamically stable form of As under aerobic condition and interacts strongly with solid matrix. However, it has been known that adsorption and oxidation reactions of arsenite (III) which is more soluble and mobile than As(V) in soils are two important factors affecting the fate and transport of arsenic in the environment. That is, the movement of As in soils and aquifers is highly dependent on the adsorption desorption reactions in the solid phase. This article, however, focuses primarily on understanding the fate and speciation of As in soils and what fate arsenic will have after it is incorporated into soils.

Mathematical Models of Competitive Adsorption of Inorganic Anions in Soils

이교석,이동성,이재봉,주리나,이명연,정덕영 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.6

Competition among anion species in solution for same sorption sites and soil surface can be of major significance in determining the effective mobility of any potentially adsorbing species. Major soil anion species include OH-, F-, Cl-, HCO3-, CO3-, NO3-, SO42-, and PO43-. And some micro nutrients such as boron and molybdenum exist as H2BO3- and MoO42-, as do some heavy metals such as chrome and arsenic as CrO42- and HAsO42-. Pesticides such as 2,4,5-T and 2,4-D also exist as anions. Many anion species are retained by more complex mechanisms than the simple electrostatic attractions involved in most cation adsorption reactions. In binary system composed of two anions, the adsorption of one anion is influenced by the other anion due to the competition for the available and limited binding sites in soil constituents. The specifically adsorbed anions may compete more effectively for sorption sites than that of nonspecifically adsorbed anion. In this study, we aim to evaluate the mathematical models to determine the magnitude of concentration variations in adsorption due to competitive interactions between anions introduced to a system in binary mixtures.

Soil Physical and Hydraulic Properties over Terrace Adjacent Four Major Rivers

이교석,이재봉,이명윤,주리나,이동성,정덕영 한국토양비료학회 2016 한국토양비료학회지 Vol.49 No.3

The soil does not only serve as a medium for plant growth but also for engineering construction purposes. It is very weak in tension, very strong in compression and fails only by shearing. The behaviour of the soil under any form of loading and the interactions of the earth materials during and after any engineering construction work has a major influence on the success, economy and the safety of the work. Soils and their management have therefore become a broad social concern. A limitless variety of soil materials are encountered in both agronomy and engineering problems, varying from hard, dense, large pieces of rock through gravel, sand, silt and clay to organic deposits of soft compressible peat. All these materials may occur over a range of physical properties, such as water contents, texture, bulk density and strength of soils. Therefore, to deal properly with soils and soil materials in any case requires knowledge and understanding of these physical properties.The desired value of bulk density varies with the degree of stability required in construction. Bulk density is also used as an indicator of problems of root penetration,soil aeration and also water infiltration. This property is also used in foundation engineering problems. While not conforming to standard test procedures, this work attempts to add to the basic information on such important soil parameters as water content, bulk density.

Leaching of Arsenic in Soils Amended with Crushed Arsenopyrite Rock

이교석,심효영,이동성,양재의,정덕영 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.2

Arsenic and its compounds which is one of the most toxic elements that can be found naturally on earth insmall concentrations are used in the production of pesticides, herbicides, and insecticides. Most arsenic thatcannot be mobilized easily when it is immobile is also found in conjunction with sulfur in minerals such asarsenopyrite (AsFeS), realgar, orpiment and enargite. In this investigation we observed the leaching of arsenicin soils amended with several levels of gravel size of arsenopyrite collected from a road construction site. Soiland gravel size of arsenopyrite were characterized by chemical and mineralogical analyses. Results of XRFanalysis of arsenopyrite indicated that the proportion of arsenate was 0.075% (wt wt-1) while the maximumamount of arsenic in soil samples was 251.3 mg kg-1. Cumulative amounts of effluent collected from thebottom of the soil column for different mixing rate of the gravel were gradually increased where proportion ofthe gravel mixed was greater than 70% whereas the effluent was stabilized to the maximum afterapproximately 45 pore volumes of effluent or greater were collected. The arsenic in the effluent was recoveredfrom the soil columns in which the proportion of arsenopyrite gravel was 60% or greater. The total amount ofarsenic recovered as effluent was increased with increasing proportion of gravel in a soil, indicating that thearsenic in the effluent was closely related with gravel fraction of arsenopyrite.

Sampling-based Super Resolution U-net for Pattern Expression of Local Areas

이교석,갈원모,임명재,Lee, Kyo-Seok,Gal, Won-Mo,Lim, Myung-Jae The Institute of Internet 2022 한국인터넷방송통신학회 논문지 Vol.22 No.5

본 연구에서는 U-Net, 잔차 신경망, 서브 픽셀 컨볼루션을 기반으로 새로운 초해상도 신경망을 제안한다. U-Net의 최대 풀링으로 인해 세부적인 정보의 손실이 일어나는 것을 막기 위해 서브 픽셀 컨볼루션을 활용한 다운 샘플링 그리고 연결을 제안한다. 이는 필터 안의 최대 값만으로 새로운 피처맵을 만드는 최대 풀링과 다르게 필터 안의 모든 픽셀을 사용한다. 2×2 크기의 필터가 지나가면서 왼쪽 위, 오른쪽 위, 왼쪽 아래, 오른쪽 아래의 픽셀들로만 이루어진 피처맵을 만든다. 이를 통해 크기가 절반이 되고, 피처맵이 개수가 4배가 된다. 그리고 연산량을 줄이기 위해 두 가지 방법을 제안했다. 첫 번째는 U-Net의 업 컨볼루션 대신 연산량이 없고, 성능이 더 좋은 서브 픽셀 컨볼루션을 사용한다. 두 번째는 U-Net의 연결 층 대신 두 피처 맵을 더하는 층을 사용한다. 밴치 마크 데이터 세트로 실험한 결과 스케일 2의 set5 데이터를 제외하고 모든 스케일 및 벤치마크 데이터 세트에서 더 나은 PSNR 값을 보여주고, 국소부위의 패턴을 명확하게 표현할 수 있었다.

Geographical features and types and changes of agricultural land uses in North Korea

이교석,류진희,이동성,홍병덕,서일환,김성철,정덕영 충남대학교 농업과학연구소 2019 Korean Journal of Agricultural Science Vol.46 No.1

The aim of this study was to identify land resources because food production and supply in North Korea have been at risk due to variations in its seasonal climate. More than threefifths of the soils are locally derived from the weathering of granitic rocks or various kinds of schists developed from crystalline rocks. Well-developed reddish brown soils derived from limestone are found in the North Hwanghae province and in the southern part of the South Pyeongan province. Additionally, a narrow strip of similarly fertile land runs through the eastern seaboard of the Hamgyong and Kangwon Provinces. The loss of clay particles and organic matter are major causes of degradation in the soil physical and chemical properties in North Korea. 75% of the areas converted from forests became croplands, and 69% of the land converted to croplands came from forests. The net forest loss was quite small from the 1990s to the 2000s. However, deforestation in areas with a slightly lower elevation and gentler slope between 1997 and 2014 led to severe soil erosion resulting in a drastic change in the physical and chemical properties of the soil which influenced cropland stability and productivity. Therefore, the drastic changes in land cover as well as in the physical and chemical properties of the soil caused by various geographical features have seriously influenced the productivity of crops in North Korea.

Status and future perspective for soil contamination of arable land in China

이교석,이동성,홍병덕,서일환,임철순,정현규,정덕영 충남대학교 농업과학연구소 2019 Korean Journal of Agricultural Science Vol.46 No.4

China is currently facing great challenges in protecting its arable soil from contamination by heavy metals, especially Cd in paddy soil. China enacted the first soil environmental quality standards (SEQS) for ten pollutants in 1995, and the Ministry of Ecology and Environment released the results of the first nationwide soil survey in 2014. The soil survey showed that as much as 16% of China's soil and 19% of the agricultural soils were contaminated mainly with heavy metals and metalloids beyond the environmental quality limits. The exceeded rate of the contaminant limits in food crops was widespread in China, and the most severe regions were East and Southwest China. Heavy metals and metalloids accounted for 82.4% of the contaminants in soils while organic pollutants accounted for 17% of the contaminants in the soil. Among the heavy metals and metalloids exceeding the Ministry of Environmental Protection (MEP) limit, cadmium (Cd) was highest at 7.0%, followed by nickel (4.8%), arsenic (2.7%), cobalt (2.1%), mercury (1.6%) and lead (1.5%). However, all the average concentrations of the pollutants were lower than the recommended values for the contaminants except for Cd for three levels of pH (< 6.5, 6.5 - 7.5, and > 7.5). According to the Action Plan on Prevention and Control of Soil Pollution released by the State Council in 2016, 90% of contaminated farmland will be made safe by 2020 with an increase to 95% by 2030. Therefore, it is necessary to improve the soil quality to meet the environmental quality standard for soils and heavy metal standards for food safety.

Mineralogical Characteristics and Physico-Chemical Properties of a Newly Reclaimed Tidal Flat of Haenam Bay in the Southwestern Coast of Korea

이교석,류진희,이동성,홍병덕,서일환,임철순,정현규,정덕영 한국토양비료학회 2019 한국토양비료학회지 Vol.52 No.4

The aim of this investigation was to identify the soil physical and chemical properties and the mineralogies ofrecently reclaimed tidal flat land (RTFL) consisted of five different soil series within the investigation sitelocated in Youngsan-river Bay of Southwestern coast in Korea, that has to be only used as upland according tothe policy of designated absolute agricultural land. . The results show that the soil textures of the soil horizons are sandy loam and silt loam for all five soil series, with typical soil colors of yellow to pale yellow for Ap horizons containing higher clay content greater (> 18%) and greenish gray containing higher sand content (> 60%). The pHs of surface horizons for Bokchun (BC), Junbook (JB) and Poseung (PS) soil series are not only acidic (< 4.5) but also soil color is dark brown with reddish brown mottles. The X-ray diffraction (XRD) analyses represent the major minerals are illite, kaolinite and quartz for BC, JB and PS soil series while quartz and illite are major minerals for Taehan (TH) and Gwangpo (GP) soil series. Silicon and aluminum dominant in the Ap and Bg horizons are significantly higher in the soil series of BC, JB and PS than those in TH and GP. Also, we found that the kaolinite particles of varying sizes are arranged in face-to-face patterns along with the presence of spherical particles of quartz, especially in BC, JB and PS.

유비철석 유래 비소의 토양 내 흡착과 이동 특성

이교석(Kyo Suk Lee),정덕영(Doug Young Chung) 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.10