Headspace-SPME와 GC-MSD를 이용한 수중의 냄새 유발물질 분석 최적화 및 낙동강 수계에서의 검출 특성 = Optimization of Odorous Compounds Analysis in Water Using Headspace-SPME and GC-MSD, and Detection Characteristics in the Nakdong River Basin

국문 초록 (Abstract)

목적:본 연구에서는 headspace-SPME 전처리 장치와 GC-MSD를 이용하여 10종의 냄새 유발물질(dimethyl trisulfide (DMTS), 3-hexenylacetate (HA), 2-isopropyl-3-methoxypyrazine (IPMP), 2-methylbenzofuran (MBF), 2-isobutyl-3-methoxypyrazine (IBMP), β-cyclocitral (CC), trans-2-decenal (DCNL), 2-trans-4-trans-decadienal (DENL) 2,4,6-trichloroanisole (TCA) 및 β-ionone (ION))을 동시에 분석할 수 있는 간편하고 자동화된 분석 방법을 개발하여 낙동강 전 수계에서의 냄새 유발물질 분포 특성을 평가하였다.
방법:냄새 유발물질 10종에 대한 headspace-SPME 전처리 장치에서의 추출효율 최적화하기 위하여 SPME fiber 재질별, 추출 온도와 추출 시간, 탈착 온도와 탈착 시간 및 염석제의 최적 투입량을 평가하였다. 또한, 최적화된 headspace-SPME 전처리법을 이용하여 낙동강 수계의 본류 10지점과 지류 6개 지점에 대해 검출 농도를 조사하였다.
결과 및 토의:최적화된 headspace-SPME 전처리법을 이용하여 GC-MSD 분석 시, 냄새 유발물질 10종의 검출 한계와 정량 한계는 각각 2~10 ng/L 및 5~25 ng/L였고, 3-Hexenyl-acetate (HA)의 검출 한계 및 정량 한계가 가장 높았다. 낙동강 전 수계에서 냄새 유발물질 분포 특성을 평가한 결과, DMTS, CC, ION 3종만 검출되었고, 그 중 DMTS는 지류인 진천천에서 115.5 ng/L로 가장 높게 검출되었으며, 본류에서는 CC가 고령에서 30.6 ng/L로 가장 높은 농도로 검출되었다. 낙동강의 경우, 상류에는 냄새 유발물질에 대한 오염이 없었고, 하수처리장 방류수의 영향을 받는 중류에서 검출 농도가 상승한 후 하류로 갈수록 감소하는 경향을 나타내었다.
결론:냄새 유발물질은 수돗물에 ng/L 수준의 매우 낮은 농도로 존재하더라도 품질에 대한 불신을 초래할 수 있으므로, 갈수기를 포함한 조류 번성기에는 상수원에 대한 주기적인 모니터링이 필요하였다. 또한, 본 연구에서 평가된 10종 이외의 다양한 냄새 유발물질에 대해서도 향후 분석법 최적화 및 상수원에서의 분포 특성 등을 포함한 지속적인 연구가 필요한 것으로 평가되었다.

다국어 초록 (Multilingual Abstract)

Objectives:This study developed a simple and automated analytical method using headspace-SPME (solid phase microextraction) and GC (gas chromatography)-MSD (mass selective detector) to simultaneously analyze ten odorous compounds (dimethyl trisulfide (DMTS), 3-hexenylacetate (HA), 2-isopropyl-3-methoxypyrazine (IPMP), 2-methylbenzofuran (MBF), 2-isobutyl-3-methoxypyrazine (IBMP), β-cyclocitral (CC), trans-2-decenal (DCNL), 2-trans-4-trans-decadienal (DENL) 2,4,6-trichloroanisole (TCA) 및 β-ionone (ION)), evaluating their distribution characteristics throughout the Nakdong River basin.
Methods:To optimize the extraction efficiency of the headspace-SPME method for ten odorous compounds, we evaluated various SPME fiber materials, extraction temperatures, extraction times, desorption temperatures, desorption times and salt (NaCl) dosages. Additionally, using the optimized headspace-SPME, we investigated the detection concentrations at ten main stream sites and six tributary sites in the Nakdong River basin.
Results and Discussion:The most suitable SPME fiber material for the pretreatment of ten odorous compounds was CAR/PDMS/DVB. The optimal SPME extraction temperature and time were 75°C and 60 minutes, respectively, and the optimal desorption temperature and time at the GC injection port were 250°C and 3 minutes. Additionally, the optimal salt (NaCl) dosage for a 10mL water sample was 2g. Using the optimized headspace-SPME pretreatment method for GC-MSD analysis, the detection limits and quantification limits for the ten odorous compounds ranged from 2 to 10ng/L and 5 to 25ng/L, respectively, with HA exhibiting the highest detection and quantification limits. The evaluation of the distribution characteristics of odorous compounds throughout the Nakdong River basin revealed that only three compounds—DMTS, CC and ION—were detected. Among these, DMTS was found at the highest concentration of 115.5ng/L in the tributary Jincheon-cheon, while CC was detected at the highest concentration of 30.6ng/L in the main river at Goryeong. In the case of the Nakdong River basin, there was no contamination by odorous compounds in the upstream area. In the middle reach, influenced by effluent of wastewater treatment plants, the detection concentrations of three odorous compounds increased, but they showed a decreasing trend as they moved downstream.
Conclusion:Since odorous compounds can lead to distrust in water quality even at extremely low concentrations in the ng/L range in tap water, regular monitoring of water sources is necessary during algal bloom season, including the dry season. Furthermore, continuous research is needed on various odorous compounds beyond the 10 odorous compounds in this study, including the optimization of analytical methods and the detection characteristics in water sources.