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안정동위원소를 이용한 하천에서의 질소오염원 기여율 정량화: Bayesian 혼합모델의 적용
남태희,류희성,강태우,한영운,김지현,이경희,황순홍,김경현 한국물환경학회 2019 한국물환경학회지 Vol.35 No.6
The ‘Stable Isotope Analysis in R’ (SIAR), one of the Bayesian mixing models for stable isotopes, has been proven to be useful for source apportionment of nitrates in rivers. In this study, the contribution ratios of nitrate sources were quantified by using the SIAR based on nitrogen and oxygen stable isotope measurements in the Yeongsan River. From the measurements, it was found that the values of δ15N-NO3 and δ18O-NO3 ranged from -8.2‰ to +13.4‰ and from +2.2‰ to +9.8‰, respectively. We further analyzed the contribution ratios of the five nitrate sources by using the SIAR. From the modeling results, the main nitrate source was found to be soil N (29.3 %), followed by sewage (26.7 %), manure (19.6 %), chemical fertilizer (17.9 %) and precipitation (6.3 %). From the results, it was found that the anthropogenic sources, i.e., sewage, manure and chemical fertilizer contribute 64.2% of the total nitrate inflow from the watershed. Due to the significant correlation of δ15N-NO3 and lnNO3 - in this study, the fractionation factors reflecting the biogeochemical processes of stable isotope ratios could be directly obtained. This may make the contribution ratios obtained in this study more precise. The fractionation factors were identified as +3.64 ± 0.91‰ for δ15N-NO3 (p<0.01) and -5.67 ± 1.73 ‰ for δ18O-NO3(p<0.01), respectively, and were applied in using the SIAR. The study showed that the stable isotope method using the SIAR could be applied to quantitatively calculate the contribution ratios of nitrate sources in the Yeongsan River.
영산강수계 의료기원 방사성요오드(<sup>131</sup>I) 핵종의 분포 및 거동평가
강태우 ( Tae-woo Kang ),한영운 ( Young-un Han ),박원표 ( Won-pyo Park ),송광덕 ( Kwang-duck Song ),황순홍 ( Soon-hong Hwang ),강태구 ( Tae Gu Kang ),김경현 ( Kyung Hyun Kim ) 한국환경농학회 2018 한국환경농학회지 Vol.37 No.4
본 연구는 영산강 수계에 위치한 하수처리장 및 하천 중 인공방사성핵종 <sup>131</sup>I의 농도 분포와 하천에서 거동 평가로부터 기원을 확인하고자 수행하였다. 조사지점은 하천 중 본류 13개 및 지류 4개 지점과 하수처리장 2개 지점을 포함하여 총 19개 지점을 선정하였다. <sup>131</sup>I 방사능 분석은 고순도 게르마늄 검출기와 다중파고분석기로 구성된 감마분광계를 이용하여 계측하였다. 하수처리장 중 <sup>131</sup>I 핵종은 두 지점의 방류수에서 대부분 검출되었으나, 하천의 표층수는 2017년 상반기(MS4, MS10) 및 하반기(MS4, MS7)에만 각각 두 지점에서 검출되었다. 하수처리장 방류수 중 <sup>131</sup>I 농도는 각각 0.0870∼3.87 Bq/L 및 MDC 이하∼0.534 Bq/L, 검출된 하천 표층수는 0.0908∼0.174 Bq/L 범위였다. 하천에서 <sup>131</sup>I 거동 평가 결과, 본류 중에서 가장 상류와 지류의 하천 지점들에서는 검출되지 않았고, 반면 하수처리장과 이들의 영향을 받는 하류의 하천 지점들에서는 지속적으로 검출되었다. 하지만 하류 하천으로 갈수록 감소하다가 불검출 되어 하수처리장과 밀접한 관계가 있었다. 이상의 결과, 하천에서 검출되는 <sup>131</sup>I 핵종은 하수처리장에서 유래된 것으로 의료 기원임을 확인할 수 있었다. BACKGROUND: Recently, the use of <sup>131</sup>I for diagnosis and treatment of thyroid cancer has been increasing, and the radionuclide is continuously released into aquatic ecosystem. This study was carried out to investigate the <sup>131</sup>I concentrations in mainstreams, tributaries, and sewage wastewater treatment plants (SWTPs) of the Yeongsan River Basin and to identify their origins from the assessment of behaviors in the rivers. METHODS AND RESULTS: The water samples were collected from 19 sites including mainstreams (13), tributaries (4) and SWTPs (2). The <sup>131</sup>I concentration was measured using a gamma-ray spectrometry with a HPGe detector. The <sup>131</sup>I in SWTPs was detected mostly in the discharged effluent at the sampling sites. However, from the surface water of the rivers, <sup>131</sup>I was found only at two sites from each sampling period of the first (MS4 and MS10) and the second half (MS4 and MS7) of the year 2017. The concentrations of <sup>131</sup>I in the effluent discharged from SWTPs were in the range of 0.0870 to 3.87 Bq/L for SWTP1, and <MDC to 0.534 Bq/L for SWTP2. The concentrations of the isotope detected in surface water of the rivers were between 0.0908 to 0.174 Bq/L. The behavior assessment of <sup>131</sup>I in the river revealed that it was not detected in the upper streams of the mainstreams and tributaries, while continuous detection was found in the SWTPs and downstream sites affected by the effluent. However, the concentration of <sup>131</sup>I decreased downstream, eventually becoming undetectable. Such behavior was closely related to the behavior found in the SWTPs. CONCLUSION: These results indicated that medicallyderived <sup>131</sup>I was discharged to the river via sewage effluent at the SWTPs. It is necessary to evaluate the influence of aquatic ecosystems through continuous monitoring in the future.
방사성물질 측정망 현황 및 하천·호소 내 인공방사성물질 (<sup>134</sup>Cs, <sup>137</sup>Cs, <sup>131</sup>I) 조사
김지유,정현지,안미정,홍정기,강태구,강태우,조윤해,한영운,설빛나,김완석,김경현,Kim, Jiyu,Jung, Hyun-ji,An, Mijeong,Hong, Jung-Ki,Kang, Taegu,Kang, Tae-Woo,Cho, Yoon-Hae,Han, Yeong-Un,Seol, Bitna,Kim, Wansuk,Kim, Kyunghyun 한국분석과학회 2015 분석과학 Vol.28 No.6
본 연구에서는「공공수역 방사성물질 측정망 운영 계획」에 따른 모니터링 수행 내용을 소개하였고, 하천 및 호소 60 개 지점을 대상으로 인공방사성물질(<sup>134</sup>Cs, <sup>137</sup>Cs, <sup>131</sup>I)의 농도를 조사하여 우리나라 지표수 내 방사성물질의 실태를 파악하고자 하였다. 채취된 시료는 마리넬리 비커를 이용한 감마분광 분석기법으로 분석하였다. <sup>134</sup>Cs와 <sup>137</sup>Cs은 모든 지점에서 MDA 미만으로 조사되었고, <sup>131</sup>I는 한 지점(0.533±0.058 Bq/L)을 제외한 모든 지점의 농도가 MDA 미만으로 나타났다. <sup>131</sup>I는 의료용으로 사용하는 물질로 환자의 배설물로 인해 하수처리장 인근 하천수에서 빈번하게 검출되는 물질로 알려져 있다. 따라서 <sup>131</sup>I가 검출된 원인을 파악하기 위해 하수처리장 방류지점을 포함한 <sup>131</sup>I가 검출된 상류수계 6개 지점을 추가 조사하였다. 조사결과, 하수처리장 처리수 방류지점에서부터 하류방향으로 <sup>131</sup>I가 지속적으로 검출되었으며, 농도는 0.257±0.034~0.799±0.051 Bq/L 범위로 조사되었다. 추가조사를 통해 하수처리장 방류수가 하천수의 <sup>131</sup>I 검출에 영향을 미치는 것으로 나타났다. A survey of the artificial radionuclides in rivers and lakes was conducted to investigate their levels in surface water. Water samples were collected at 60 points and analyzed by gamma-ray spectrometry with a measurement time of 10,000 seconds for <sup>134</sup>Cs, <sup>137</sup>Cs, and <sup>131</sup>I. The obained values were lower than MDA for all points, except one point for <sup>131</sup>I that was 0.533±0.058 Bq/L. <sup>131</sup>I is known as a radioactive material that occurs frequently in sewage treatment plants. Because it is often used for medical treatments and subject to spreading into the environment due to the excretion from the patients. For the point where <sup>131</sup>I was detected, we conducted additional investigation on the upstream river point and the effluent points of nearby sewage treatment plant to find the source of <sup>131</sup>I. <sup>131</sup>I was not detected at the upstream points of one of the upstream sewage treatment plants but found at the downstream points with the level being 0.257±0.034 to 0.799±0.051 Bq/L, proving the sewage treatment plant was the <sup>131</sup>Isource.