Determination of Petroleum Aromatic Hydrocarbons in Seawater Using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography/Mass Spectrometry

The headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry procedure has been developed for the simultaneous determination of petroleum aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene isomers (BTEX) and polycyclic aromatic hydrocarbons (PAHs) in seawater. The advantages of SPME compared to traditional methods of sample preparation are ease of operation, re-use of fiber, portable system, minimal contamination and loss of the sample during transport and storage. SPME fiber, extraction time, temperature, stirring speed, and GC desorption time were key extraction parameters considered in this study. When applied to artificially contaminated seawater like water accommodated fraction, our optimized HS-SPME-GC/MS showed comparable performances with other conventional methods. The proposed protocol can be an attractive alternative to analysis of BTEX and PAHs in seawater after oil spill.1

Determination of Petroleum Aromatic Hydrocarbons in Seawater Using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography/Mass Spectrometry

해수 내 유류계 방향족탄화수소인 BTEX(benzene, toluene, ethylbenzene, xylene)와 다환방향족탄화수소(polycyclic aromatic hydrocarbons: PAHs)를 동시에 분석할 수 있는 기술 개발을 위해 GC/MS에서 고체상미량추출법(solid phase microextraction: SPME)을 이용하여 최적의 분석기법을 정립하였다. SPME 기법은 전통의 분석 방법과 비교할 때 조작이 간단하고, 파이버를 재사용할 수 있고, 휴대하기 쉽고, 시료의 운반이나 저장하는 동안 오염을 최소화 할 수 있는 장점이 있다. 최적의 SPME 조건을 정립하기 위해 여러 변수 즉, SPME 수착제, 흡착 시간, 흡착 온도, 교반 속도, GC 탈착 시간들을 확인하였다. 다양한 SPME 수착제( 100μm PDMS, 75μm CAR/PDMS, 65μm PDMS/DVB)를 이용하여 BTEX와 PAHs(분자량 78부터 202까지)를 동시에 분석한 결과 65μm PDMS/DVB를 최적의 수착제로 선정하였다. 최적의 수착제로 65μm PDMS/DVB 선정한 다음 순차적으로 다른 변수들을 확인하였다. 그 결과 BTEX와 PAHs 동시 분석하기 위한 최적의 SPMD 조건은 흡착시간 60분, 흡착온도 50∘C , 교반속도 750 rpm, GC 탈착시간 3분으로 결정되었다. 최적화한 HS-SPME-GC/MS 분석법을 이용하여 인공오염해수 내 유류계 방향족탄화수소 분석 결과 이전 연구 방법과 유사하였다. HP-SPME-GC/MS 분석법은 기존에 유기용매를 사용한 방법이 가졌던 단점과 제한점을 보완할 수 있으며, 해수 내 유류에 의한 BTEX 및 PAHs 분석에 효율적으로 적용할 수 있다. The headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry procedure has been developed for the simultaneous determination of petroleum aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene isomers (BTEX) and polycyclic aromatic hydrocarbons (PAHs) in seawater. The advantages of SPME compared to traditional methods of sample preparation are ease of operation, reuse of fiber, portable system, minimal contamination and loss of the sample during transport and storage. SPME fiber, extraction time, temperature, stirring speed, and GC desorption time were key extraction parameters considered in this study. Among three kinds of SPME fibers, i.e., PDMS ( 100μm ), CAR/PDMS ( 75μm ), and PDMS/DVB ( 65μm ), a 65μm PDMS/DVB fiber showed the most optimal extraction efficiencies covering molecular weight ranging from 78 to 202. Other extraction parameters were set up using 65μm PDMS/DVB. The final optimized extraction conditions were extraction time (60 min), extraction temperature (50), stirring speed (750 rpm) and GC desorption time (3 min). When applied to artificially contaminated seawater like water accommodated fraction, our optimized HS-SPME-GC/MS showed comparable performances with other conventional method. The proposed protocol can be an attractive alternative to analysis of BTEX and PAHs in seawater.22Nkc

기후위기 대응을 위한 해수면 태양광 반사율 향상 기술 동향:Marine Foaming을 중심으로

기후변화에 관한 정부 간 협의체(IPCC)의 제6차 평가보고서(2021년8월)에서는 현재(2011~2020년) 지구 평균온도는 산업화 이전보다 1.09℃ 상승하였고, 현 수준의 온실가스 배출량을 유지한다면 2021~2040년 중 1.5℃를 넘어 지구온난화가 가속화될 것으로 예상하였다. 각 국은 파리협정에서 합의한 1.5℃ 이내 제한 목표를 달성하기 위해 다양한 온실감축 대책을 제출하였다. 그러나 이러한 온실가스를 줄이는 노력이 효과를 발휘하지 못하거나 감축 목표를 이행하더라도 점점 빨라지는 온난화 속도를 따라가지 못하는 상황에서 단시간에 지구 온도를 낮추는 방법으로 이산화탄소 제거(Carbon Dioxide Removal, CRD)와 태양복사관리(Solar Radiation Management, SRM)와 같은 지구공학기술이 주요 연구 분야로 거론되고 있다. SRM은 태양복사에너지의 반사율을 높여 지구의 온도를 낮추는 방법으로 6가지 방법이 제시되고 있다. 이 중 해양에서 적용 가능한 지구공학기술의 하나는 Marine Foaming(MF)으로 해수면에 햇빛을 반사하는 물질을 살포하거나 흰색 미세기포를 형성해 태양광 반사율을 조절하는 것이다. 이 기술은 강한 바람에 의해 깨진 파도의 백파 또는 해안에서 파도가 부서질 때 흰 거품이 수면에 비해 밝은 빛을 보여 반사율이 더 높아지는 것에서 아이디어를 얻었다. MF기법은 흰 거품 또는 미세기포를 안정적이고 오래도록 지속시키거나 인공첨가제를 사용하여 넓게 분산시키는 것을 목표로 한다. 흰 거품을 오랫동안 유지시키기 위해서는 두 가지 접근 방식이 있다. 첫번째는 선박의 항적에 따라 생성된 반류(wake)의 거품을 다량의 흰색 미세기포로 생성하는 기술이다. 반류의 거품을 10배 밝게 하고 10일 동안 지속시킬 수 있다면, 해양의 5.5%를 덮고 지구 온도를 2069년까지 0.5℃ 낮출 것으로 예상하였으며, 30만대의 선박을 대상으로 반류의 지속 시간을 1440배 이상 증가하였을 때 복사강제력은 전 지구적으로 –0.9±0.6 Wm-2로 모델결과 추정하였다. 두 번째는 첨가제를 이용하여 미세기포를 안정화시켜 오래도록 넓게 퍼지게 하는 기술이 검토되고 있다. 한편, MF 기술은 해양 생물 다양성과 생산성에 부정적인 영향을 초래할 수 있고, 해양 산성화 및 기상변화를 야기할 우려가 있다. 본 발표에서는 최근의 연구동향을 소개하고, 향후 연구방향에 대해 논의하고자 한다.2

Atmospheric concentration of petroleum derived polycyclic aromatic hydrocarbons after the Hebei Spirit oil spill

The Hebei Spirit oil spill in December 7th, 2007 was the biggest oil spill in Korea. Approximately 10,900 tons of crude oil (mixtures of Kuwait Export Crude, Iranian Heavy Crude, and UAE Upper Zakum Crude) were spilled along the Taean coast (west coast of South Korea). Thirty percents of total mass of crude oil, mostly volatile hydrocarbons were evaporated at the initial stage of spill. Harner type passive air samplers (PAS) consisting of polyurethane foam were deployed at two spill sites (Gaemok-port and Mallipo) and one reference site (Mageum-ri) for one year after the spill on monthly basis. EPA priority PAHs and alkylated PAHs were measured. Concentrations of 15 PAHs at spill sites were similar to those reported at reference site. On the other hand, concentrations of alkylated PAHs measured at spill sites were significantly higher than that of a reference site right after the spill. In particular, the concentrations and profiles of alkylated phenanthrenes and dibenzothiophenes exhibited strong influence of petroleum derived PAHs inputs. One of oil fingerprinting index, PAHs double ratio using alkylated phenanthrenes and dibenzothiophenes identified petrogenic input source and further implicated environmental fate of volatile fractions of spilled oil. (west coast of South Korea). Thirty percents of total mass of crude oil, mostly volatile hydrocarbons were evaporated at the initial stage of spill. Harner type passive air samplers (PAS) consisting of polyurethane foam were deployed at two spill sites (Gaemok-port and Mallipo) and one reference site (Mageum-ri) for one year after the spill on monthly basis. EPA priority PAHs and alkylated PAHs were measured. Concentrations of 15 PAHs at spill sites were similar to those reported at reference site. On the other hand, concentrations of alkylated PAHs measured at spill sites were significantly higher than that of a reference site right after the spill. In particular, the concentrations and profiles of alkylated phenanthrenes and dibenzothiophenes exhibited strong influence of petroleum derived PAHs inputs. One of oil fingerprinting index, PAHs double ratio using alkylated phenanthrenes and dibenzothiophenes identified petrogenic input source and further implicated environmental fate of volatile fractions of spilled oil.1

In situ formation of oil-suspended particulate matter aggregate during flushing activities

After the collision of the Singapore-registered oil tanker, Wu Yi San into the oil terminal of Yeosu port, approximately 800 tons of oil mixture was released from the ruptured pipelines. Emergency oil spill responses were performed to recover and clean the spilled oil in a short period of time. However, considerable amounts of residual oils were found along a beach located 2 km from the accident site during a monitoring program a year after the spill. In an attempt to remediate the residual oil, the beach was subject to consecutive flushing: seawater under high pressure was repeatedly applied over residual oil-sediment mixtures. Resuspended residual oils were collected through snares and adsorption pads. During the flushing operation, large amounts of suspended particulate matters (SPM) were also resuspended, which promoted oil-SPM interactions, providing favorable conditions for formation of oil-SPM aggregate (OSA). In situ formation of OSA was identified by microscopic and chemical analysis. Large size multiple droplet type OSA was dominant. Mass balance of resuspended oil in various forms was estimated by laboratory OSA simulation using natural seawater and spilled oil. The percentage of surface oil slick, neutral buoyancy OSA, and negative buoyancy OSA were calculated as 52.2±10.7, 32.2±9.8, and 15.6±3.5%,respectively. The neutral buoyancy OSA remained stable for more than 3 months, which might be sufficienter and clean the spilled oil in a short period of time. However, considerable amounts of residual oils were found along a beach located 2 km from the accident site during a monitoring program a year after the spill. In an attempt to remediate the residual oil, the beach was subject to consecutive flushing: seawater under high pressure was repeatedly applied over residual oil-sediment mixtures. Resuspended residual oils were collected through snares and adsorption pads. During the flushing operation, large amounts of suspended particulate matters (SPM) were also resuspended, which promoted oil-SPM interactions, providing favorable conditions for formation of oil-SPM aggregate (OSA). In situ formation of OSA was identified by microscopic and chemical analysis. Large size multiple droplet type OSA was dominant. Mass balance of resuspended oil in various forms was estimated by laboratory OSA simulation using natural seawater and spilled oil. The percentage of surface oil slick, neutral buoyancy OSA, and negative buoyancy OSA were calculated as 52.2±10.7, 32.2±9.8, and 15.6±3.5%,respectively. The neutral buoyancy OSA remained stable for more than 3 months, which might be sufficient1

A methodology to improve the reliability of the design : Axiomatic Design with FMECA

This paper presents the synergetic use of the Axiomatic Design principles and FMECA (Failure mode, effects, and criticality analysis) for the reliability-critical system design. The hierarchical structures of the Axiomatic Design and The FMECA are reviewed and the possible synergetic use in the FR-DP assignment. The Proposed methodology is validated in the case study of the Mobile Harbor docking system design. Keywords Conceptual Design, Reliability, Axiomatic Design, FMECA, Mobile Harbo

A Mesocosm Study on the Fate of Iranian Heavy Crude Oil in Water Column

We studied the environmental fate of the water-soluble fraction of Iranian Heavy crude oil using experimental 980 liters of in situ mesocosm bags (0.5 m in diameter and 5 m in depth) that mimic natural ecosystems. Mesocosm facilites composed of nine experimental bags (‘control’ x 3, ‘oil’ x 3, ‘oil+dispersant’ x 3). Mesocosm experiment was conducted from April 17 to July 2, 2009. The fate of artificially spilled crude oil in water column and the effect of dispersant application were monitored by measuring total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs) and their compositional changes with time. Much faster increase of oil concentration in water column was observed in dispersant treated oiled mesocosm (313 ppb/day) than in non-treated oiled one (3.47 ppb/day) within eight days after oil addition. Oil concentrations in water column remained relatively stable thereafter and the TPH levels in ‘oil+dispersant’ mesocosms were about two orders of magnitude higher than those in ‘oil’ mesocosm. TPH levels are relatively high according to water depth in order of surface (0.5 m) > middle (2.5 m) > bottom (4.5 m) within several folds. The difference decreased according to time. Depuration rates of oil were also 6 times higher at ‘oil+dispersant’ mesocosm compared to ‘oil’ group.1

대기 미세플라스틱 해양침적량 산정 불확도 개선을 위한 다중 플랫폼 관측 연구

대기는 강, 하수, 도시 유출과 더불어 육상에서 해양으로 미세플라스틱이 유입되는 주요 경로 중 하나이다. 대기를 통해 해양으로 유입되는 미세플라스틱의 침적량은 0.013-25 Mt/year 범위로 추정되며, 제한된 현장 관측 자료로 인해 침적량에 대한 불확도가 크다. 이를 개선하기 위해서는 고정 정점에서의 장기간 모니터링을 통한 시간적 변동과 이동 측정을 통한 공간적 변동을 동시에 고려할 필요가 있다. 본 연구에서는 고정 정점(울릉도)에서의 장기간 모니터링과 연구선(온누리호)을 활용한 이동 측정을 통해 동해에서의 대기 미세플라스틱의 유입량 및 오염 특성을 평가하였다. 2022년 11월부터 2023년 10월까지 울릉도에서의 대기 미세플라스틱 총침적률은 43-991 n/m2/day 범위에 평균 침적률은 209±281 n/m2/day였다. 건식 침적과 습식 침적의 평균 침적률은 각각 119±165 n/m2/day, 89±120 n/m2/day로 건식 침적이 더 높은 경향을 보였으나 통계적으로 유의미한 차이는 없었다. 검출된 미세플라스틱의 대부분은 파편형(67.2%)으로 20-100 μm(72.9%) 크기 범위에 속하며, 주요 폴리머 재질은 폴리프로필렌(32.4%), 폴리에스터(30.1%), 폴리에틸렌(15.3%) 순으로 확인되었다. 2023년 4월 3일부터 4월 15일까지 4개 경로에서의 이동 측정 결과, 연안 지역과 인접한 내측 경로에서의 침적률은 2,160±188 n/m2/day로, 외해 경로(566±22 n/m2/day, 414±195 n/m2/day, 207±49 n/m2/day)에 비해 최대 10배 높은 값을 나타냈다. 육지로부터 거리가 멀어질수록 가장 작은 크기 범위의 비섬유형 미세플라스틱(75.7%)과 섬유형 폴리에스터(82.4%)가 증가하는 경향을 보였다. 이는 육지가 대기 미세플라스틱의 주요 오염원이며, 크기가 작고 섬유 형태일수록 미세플라스틱의 장거리 이동성이 높음을 시사한다. 이러한 이동 측정 결과는 4월 고정 관측에서의 미세플라스틱 오염 특성과 유사하게 나타났다. 역궤적 분석을 통해 동해에서의 미세플라스틱은 인접한 해양과 더불어 중국 북동 지역, 한반도와 같이 먼 육지에서 유래되었음을 확인하였다. 이러한 결과들은 동해에서의 대기 미세플라스틱 해양 유입량 산정에 대한 불확도를 개선하는데 기여할 것으로 기대된다. [사사] 본 연구는 정부(해양수산부)의 재원으로 해양수산과학기술진흥원-'해양 미세플라스틱 유입·발생 및 환경거동 연구' 사업 지원을 받아 수행된 연구임(RS-2022-KS221604).2