Characteristics of Total Carbon and Total Organic Carbon Using Elemental Analyzer in Hyung-Do Intertidal Zone Sediments

Quantitative understanding of total carbon, total inorganic carbon and total organic carbon contained in ocean sediments is a basic data for interpretation of oceanic sediment environments. Elemental analyzer(EA) is frequently used for the analysis of carbon contents in inland soils and ocean sediments. Carbon and nitrogen contents of the soil reference material analyzed by an EA were 2.30% and 0.21% with standard deviations of 0.02 and 0.01, respectively. Relative standard deviations were 0.01 and 0.06, respectively, representing a high precision. Regression analysis of TOC and TC analysis results for the samples with TOC of less than 2.0% for the site in Hyung-Do showed a linear relationship with a slope of 0.9743( R2 =0.99 0.9989, n=38), and the results of a relationship regression analysis between total organic carbon contents less than 0.5% and average grain size except for two samples showed a linear relationship with a slope of 0.0444( R2 =0.69 0.6937 n=36). TOC contents of surface sediments were in the ranges of 0.10~1.67%(Average 0.26±0.37 ) with TOC values of 1.67% at S02 sampling site, 1.13% at S07 sampling site, and less than 1.00% at remaining sites. In the case of PC 01 core sediments, TOC showed the highest value of 0.20% near 70 cm. In the case of PC 02 core sediments, the highest value of 0.24% was indicated near 60 cm. The analysis method of organic carbon obtained from Hyung-Do Intertidal zone sediment sample results may be considered applicable to an organic carbon analysis for ocean sediments and useful for organic carbon analysis experiments of ocean sediments with a reduction in time required for the analysis and a high precision coupled with a high accuracy. 해양 퇴적물내 함유된 총탄소(total carbon; TC), 총무기탄소(total inorganic carbon; TIC)와 총유기탄소(total organic carbon; TOC)의 정량적 이해는 해양 저서 퇴적 환경 해석을 위한 기본 자료이다. 원소분석기(elemental analyzer; EA)는 내륙 토양 및 해양 퇴적물의 탄소성분 분석에 많이 이용되고 있다. 원소분석기로 분석한 표준시료샘플(soil reference material; SRM)의 탄소 및 질소함량은 평균 2.30%와 0.21%이었으며, 표준편차(standard deviation)는 각각 0.02, 0.01이었다, 상대표준편차(relative standard deviation; RSD)는 각각 0.01, 0.06으로 높은 정밀도를 나타내었다. 형도 부지의 총유기탄소(TOC) 2.0% 이하 샘플에 대해 총유기탄소(TOC)와 총탄소(TC) 분석치의 회귀분석은 기울기가 0.9743인 직선형 관계( R2 =0.99 0.9989, n=38)를 보였으며, 2개 샘플을 제외한 총유기탄소 0.5% 이하의 총유기탄소량 및 평균입도의 관계 회귀분석 결과는 기울기가 0.0444인 직선형 관계( R2 =0.69 0.6937 n=36)를 나타내었다. 형도 표층퇴적물의 총유기탄소(TOC) 함량은 0.10~1.67%(평균 0.26±0.37 ) 범위로 S02 정점에서 1.67%, S07 정점에서 1.31%이고 나머지 점점은 1.00% 이하의 총유기탄소(TOC) 함량을 나타냈다. 주상퇴적물 PC 01 정점의 경우 70 cm 부근에서 총유기탄소(TOC)가 가장 높은 0.20%을 보였고, 주상퇴적물 PC 02 정점의 경우 60 cm 부근에서 가장 높은 0.24%를 나타내었다. 따라서 형도 샘플의 총유기탄소(TOC) 0.5% 이상 함유 샘플에 대해서는 탄산염 같은 무기탄소량이 높은 퇴적물 분석시 오차가 발생할수 있지만, 이와 같은 결과로부터 얻어진 유기탄소분석 방법은 해양 퇴적물의 유기탄소분석에 적용 될 수 있다. 그리고 원소분석기(EA) 정밀도 및 정확도로 해양 퇴적물 표층 및 주상 퇴적물 유기탄소분석 분석 실험에 유용 할 것으로 사료된다.22Nkc

Total Volatile Organic Compounds (Benzene, Toluene, Ethylbenzene, and Xylene) Surface Sediments from Barrier Islands in the Nakdong River Estuary, South Korea

The total volatile organic compound (TVOC) concentrations and distribution were determined for 18 surface sediment samples collected in and around three islands in the Nakdong River estuary, in the southeastern Korean Peninsula on May 2015. There are four primary volatile organic compounds: benzene, toluene, ethylbenzene, and xylene. The emissions of TVOCs from sediments were measured using a thermal desorption system-gas chromatograph-mass selective detector (TDS-GC-MSD) for 30 min at 25°C in the National Center for Inter-University Research Facilities, South Korea. The thermal extractor (Gerstel, Germany) was equipped with an adjustable oven (temperature 20&#8211 350°C) to heat a glass tube containing the sample. The TVOC ranged from 2.6 to 64.9 ng/g-dry wt (average, 13.2 ± 13.8 ng/g-dry wt), with benzene 0.6 to 0.8 ng/g-dry wt (average, 0.7 ± 0.1 ng/g-dry wt), toluene 0.4 to 1.3 ng/g-dry wt (average, 0.9 ± 0.3 ng/g-dry wt), and xylene 0.0 to 0.8 ng/g-dry wt (average, 0.2 ± 0.2 ng/g-dry wt). For most of the sampling stations, no evidence of ethylbenzene was found. The TVOC was highest for a Sinjado Island station, at 64.9 ng/g-dry wt. This area corresponds to backbarrier fringe marsh sediments sorted by location and terrain. Although the TVOC levels in many sediments were below the detection limits, this method can be used to estimate their behavior in marine environments. TVOCs in sediments are a major probl There are four primary volatile organic compounds: benzene, toluene, ethylbenzene, and xylene. The emissions of TVOCs from sediments were measured using a thermal desorption system-gas chromatograph-mass selective detector (TDS-GC-MSD) for 30 min at 25°C in the National Center for Inter-University Research Facilities, South Korea. The thermal extractor (Gerstel, Germany) was equipped with an adjustable oven (temperature 20&#8211 350°C) to heat a glass tube containing the sample. The TVOC ranged from 2.6 to 64.9 ng/g-dry wt (average, 13.2 ± 13.8 ng/g-dry wt), with benzene 0.6 to 0.8 ng/g-dry wt (average, 0.7 ± 0.1 ng/g-dry wt), toluene 0.4 to 1.3 ng/g-dry wt (average, 0.9 ± 0.3 ng/g-dry wt), and xylene 0.0 to 0.8 ng/g-dry wt (average, 0.2 ± 0.2 ng/g-dry wt). For most of the sampling stations, no evidence of ethylbenzene was found. The TVOC was highest for a Sinjado Island station, at 64.9 ng/g-dry wt. This area corresponds to backbarrier fringe marsh sediments sorted by location and terrain. Although the TVOC levels in many sediments were below the detection limits, this method can be used to estimate their behavior in marine environments. TVOCs in sediments are a major probl1

Evaluation of Methane (CH4) Gas Emissions and Sink Sources According to the Mean Size of Sediment in the Tidal Flat at Taean, Midwest Korea

본 연구는 한국 서해안 갯벌 중 충청남도 태안(황도, 신두리 및 소근리) 지역의 다양한 입도(Fork 분류법) 크기를 가진 표층 퇴적물에서 닫힌챔버법(enclosure chamber technique method)을 이용하여 메탄(CH4) 가스 방출원(+, sources, positive) 또는 흡수원(-, sinks, negative)의 양(플럭스)을 계산을 위해 현장 실험을 진행한 기초연구 논문이다. 닫힌챔버 내에서 채취된 대기 샘플 중 메탄(CH4)의 농도는 6시간 이내에 기체크로마토그래피(gas chromatograph GC-6890, USA) 및 지구 온실 가스용 분석기기(global environment gas EG analyzer GS-23, Japan)를 이용하여 분석하였다. 메탄(CH4)의 방출원 또는 흡수원의 양을 계산하기 위해 단순 선형 회귀분석을 이용하여 시간에 따른 각 기체의 농도변화인 1차 함수 기울기 값을 수식에 대입하여 계산하였다. 또한 주변 환경 특성을 참고하기 위해 퇴적물 함수율, 온도, 총유기탄소, 챔버내 온도 및 퇴적상도 측정 및 분석 하였다. 메탄(CH4) 가스 방출 및 흡수원의 측정된 계산 값은 태안 황도(silty Sand; zS), 신두리(Sand; S) 및 소근리(slightly gravelly Sand; (g)S) 지역 갯벌에서 각각 –0.17(흡수원) - 0.23(방출원) mg∙m-2∙hr-1, -0.18(흡수원) - 0.45(방출원) mg∙m-2∙hr-1, 0.06(방출원) - 0.60(방출원) mg∙m-2∙hr-1 특성을 보였다. 이들 데이터의 평균입도와 메탄(CH4) 플럭스의 상관계수(R2)는 +0.38(상관계수는 약한 양의 선형관계(n=6))이었다. 본 연구에서는 상대적으로 입자가 조립하고 표층퇴적물의 온도가 낮을 때 메탄(CH4)이 방출되는 특성을 보였다. 일반적으로 해양퇴적물의 특성상 세립하면 총유기탄소의 함량이 늘어나서 메탄(CH4) 플럭스(방출량 및 흡수량)가 커지는 것으로 판단되기 쉽지만 본 연구에서는 총유기탄소의 함량과 메탄(CH4) 플럭스 관계에서는 큰 차이를 보이지 않았다. 추가적으로 온실기체 수지(budget)에 기여 판단을 위한 갯벌 지역의 메탄(CH4) 가스 자연방출원(natural biogenic sources) 자료 축적과 빈약한 국내 갯벌 자료 수준의 향상 위한 반복적인 실험, 추가 방출인자(emission factor), 생물학적 생물 서식굴(borrow hole) 통제, 계절별 데이터 구축 및 해양 조석활동 연관 방출 및 흡수원 도출 등을 통한 불확실성(uncertainties) 감소 노력이 필요하다고 판단된다. The emissions and sink sources of methane (CH4) gas were measured in intertidal flat sediments at Hwang-do, Sindu-ri, and Sogeun-ri, Taean-gun, on the mid-western seashore of Korea using an enclosure chamber technique method. The concentrations of CH4 gas in the air samples collected in the chamber were measured using gas chromatography with an global environment gas analyzer EG analyzer, model GS-23 (Japan) and Agilent 6890 (USA), within 6 hours of collection, and the other gases were measured in real time using a multi-gas monitor. The gas sources (emissions (+, positive) and sinks (–, negative)) were flux calculated from a simple linear regression analysis of the changes in the concentrations over time. Additional parameters measured at the study site included the water content, temperature, total organic carbon, average mean size of sediments and the temperature of the inner chamber. The ranges of CH4 gas emissions and sink sources during the experimental period were –0.17 (sink) – 0.23 (source) mg∙m-2∙hr-1 for Hwang-do (silty Sand; zS), –0.18 (sink) – 0.45 (source) mg∙m-2∙hr-1 for Sindu-ri (Sand; S) and +0.06 (source) –0.60 (source) mg∙m-2∙hr-1 for Sogeun-ri (slightly gravelly Sand; (g)S). The relationship between the mean sediment size and CH4 emissions and sink sources exhibited a weak positive correlation linear relationship (n=6, R2=0.38). Various parameters affected the CH4 gas emissions and sink source data in the tidal-flat, such as the amount of sunshine, water content, temperature of the sediment/air (in the chamber), tidal cycle, and sea level. Therefore, additional experiments and analyses will be required in various environmental conditions. It is necessary to accumulate natural biogenic source data on CH4 gas in tidal flats to determine its contribution to the district carbon budget and to perform repetitive experiments, evaluate emission factors, control for borrow holes, measure seasonal data, and examine tidal activity-related emissions and sink sources to improve the domestic tidal flat data. We believe that efforts to reduce uncertainty are needed.22Nkc