上水源汚染에 따른 Trihalomethane 生成能에 관하여 : 漢江水와 都市下水川水를 中心으로

김교붕 延世大學校 1987 국내석사

위해성평가에 의한 유류오염토양의 정화목표치 산졍에 관한 연구

김교붕 서울시립대학교 일반대학원 2008 국내박사

The approach to development in risk-based screening level was considered in the total petroleum hydrocarbon, which is used when the world's several countries and institutions cleanup petroleum-contaminated soil. The purpose of this study was to complement, improve, and then present the approach to development in the risk-based evaluation and the cleanup goals through fractionation in hydrocarbon, which was suggested mainly by America's TPHCWG(Total Petroleum Criteria Working Group), in line with Korea's real situation. 1. TPH fractions were benchmarked for a method suggested by America's TPHCWG, and were largely divided into aliphatic and aromatic hydrocarbon group, which are clearly distinguished by the properties of fate and transport , and the risk level of human health in environment. Again, based on EC(equivalent carbon number) by each group, the aliphatic hydrocarbon group was subdivided into 7 including EC _(5)-EC _(6), >EC _(6)-EC _(8), >EC _(8)-EC _(10), >EC _(10)-EC _(12), >EC _(12)-EC _(16), >EC _(16)-EC _(21), and >EC _(21)-EC _(35). The aromatic hydrocarbon group was subdivided into 7 including benzene, toluene, >EC _(8)-EC _(10), >EC _(10)-EC _(12), >EC _(12)-EC _(16), >EC _(16)-EC _(21), and >EC _(21)-EC _(35). Thus, total 14 TPH fractions were established. 2. As a result of assigning the fate and transport properties by using correlation between EC and properties in individual chemicals into the TPH fraction, regarding solubility, the aromatic group is in the range of 6.6×10^(-3)~1.8×10^(3)㎎/ℓ, thereby being much higher than the range of 1.5×10^(-11)~3.6×10^(1)㎎/ℓ in the aliphatic group. So, the possibility of exposure from ground water was indicated to be higher. And, by hydrocarbon group, benzene was the highest. And, the larger carbon number led to showing the tendency of getting smaller. As for vapor pressure, the aliphatic group is a little higher than the aromatic group, thereby having been indicated to be higher in possibility of exposure by volatilization. 3. The toxicity criteria for hydrocarbon fractions was used literally a method, which had been presented as rationale at that time when TPHCWG assigned, and then was modified, supplemented, and then assigned as the recent toxicity data suggested by IRIS in America's EPA. By hydrocarbon group, the aromatic group was much lower than the aliphatic group, thereby having been indicated to be very strong in toxicity. The reference dose(RfD) in the fraction of >EC _(21)-EC _(35) for the aliphatic group, which was newly added in this study by hydrocarbon fraction, is 2.0㎎/㎏/day. And, the reference concentration(RfC) was not assigned because there is no probability of exposure by inhalation due to being very low in the vapor pressure of this fraction. Benzene of the aromatic group was assigned 0.004㎎/㎏/day for the reference dose, and 0.03㎎/㎥ for the reference concentration, respectively. The fraction, which was indicated to be relatively low in the toxicity criteria out of the aromatic group, includes >EC _(8)-EC _(10), >EC _(10)-EC _(12), >EC _(21)-EC _(35). All the fractions were assigned, respectively, 0.02㎎/㎏/day for reference dose and 0.2㎎/㎥ for reference concentration. 4. TPH fraction-specific RBSLs were each calculated by applying to model suggested by America's ASTM, targeting total 10 exposure pathways that originated from surface soil, subsurface soil, and ground water. As for TPH fraction-specific RBSLs, which were calculated by hydrocarbon group, the aromatic group was indicated to be quite lower in most cases than the results, which were calculated in the aliphatic group. This is reflecting a point that the aromatic group is much higher in solubility, thereby being easier for cross-media from soil to ground water, and accordingly, being high in possibility of exposure to human, and a point that toxicity is high, thereby being low in the toxicity criteria. Regarding TPH fraction-specific RBSLs, which were calculated by exposure pathway, first, they were indicated to be overall higher in direct exposure pathway of surface soil than other exposure pathways, thereby having been indicated to be low in the influential level that hazard will have. Second, in the exposure pathways from subsurface soil, they were the lowest in the exposure pathway by indoor inhalation of vapor from subsurface soil. In the exposure pathway by ingestion of ground water leaching from subsurface soil, the TPH fraction in the aromatic group was indicated to be much lower. And, the closer to the fraction with high EC led to getting rapidly higher due to getting lower in solubility. Third, in the exposure pathway from ground water, the aliphatic group was the lowest in the exposure pathway of indoor inhalation of vapor from ground water. And, the aromatic group was indicated to be the lowest in the exposure pathway by ingestion of ground water. As a result of comparing RBSLs developed by TPHCWG, the wholly similar results were indicated except a little difference, which were indicated due to the applied toxicity criteria, exposure parameters, input parameters, and default values. And, a problem in light of a calculating method was not shown. 5. TPH RBSLs were developed targeting 3 commercial petroleum fresh products such as gasoline, kerosene, and diesel. And, TPH RBSLs were confirmed to have been able to be finally developed after passing through the process that the total TPH concentrations are revised upward or downward and the calculation is repeated until the hazard index is achieved, by using TPH fraction-specific RBSLs and hydrocarbon concentration ratios of TPH fraction in its development process. The TPH RBSL was overall low in order of gasoline, kerosene, and diesel. In gasoline, the hazard contribution of benzene was indicated to be large. Diesel doesn't contain benzene, thus the TPH fractions between EC8 and EC16 mainly in the aromatic group were indicated to be big in the hazard contribution. As a result of comparing TPH RBSLs, which were developed by using TPHCWG method, the influence of >EC _(21)-EC _(35) fraction in the aliphatic group, which was newly added, upon development, was indicated to be almost nothing due to high toxicity criteria and low fate and transport. Also, except a case that was shown due to difference in toxicity criteria that had been applied to gasoline and benzene, the wholly similar result was indicated, thereby showing that there is applicability when developing TPH RBSLs in total petroleum hydrocarbon of the fresh petroleum product. As a result of developing TPH RBSLs with the approach, which was suggested in this study, to the contaminated soil with 3,400㎎/㎏ for diesel, 3,500㎎/㎏ for creosote oil, and 28,000㎎/㎏ for crude oil due to the recently oil-released accident, regardless of whether or not weather, the risk can be diversely quantified only with simply changing and analyzing some part of the existing test method. And, TPH RBSLs, which are the make-decision data on soil remediation, could be easily developed as follows by exposure pathway. In other words, TPH RBSLs, which were developed in the direct exposure pathway of surface soil, were in order of weathered diesel, weathered creosote oil, and weathered crude oil, with 16,000㎎/㎏, 11,000㎎/㎏, and 16,000㎎/㎏, respectively. The TPH concentrations in the weathered crude oil could be known to be uniquely exceeding the developed TPH RBSLs. And, the exposure pathways of indoor inhalation of vapor from subsurface soil were 2,900㎎/㎏, 1,800㎎/㎏, and 10,000㎎/㎏, respectively, thus all the three petroleum products exceeded TPH RBSL, which were developed each. However, in the weathered crude oil, soil saturation concentration was surpassed, thereby having been able to presume that there is no possibility of risk in this exposure pathway. In the exposure pathway of ingestion of ground water leaching from subsurface soil, they were, respectively, 6,400㎎/㎏, 5,400㎎/㎏, 35,000㎎/㎏, thus all the three petroleum products exceeded TPH RBSL, which were developed each. However, the weathered diesel and crude oil were exceeding Csat. In the exposure pathways of ingestion of ground water, they were indicated to be, respectively, 0.7㎎/ℓ, 0.8㎎/ℓ, 0.8㎎/ℓ. And, the hazard contributions in the TPH fractions of the aromatic group could be known to be much larger than the aliphatic group. Regarding the technical finding, which was suggested in this study as above, as for TPH in soil or ground water contaminated due to petroleum, first, it can be used as the development tool of risk-based screening level and site-specific target level. Second, it can be used as the cost-effective risk-based evaluation tool by very simplifying the modeling framework. Third, it can be applied usefully as basic data when trying to establish risk-based regulatory criteria and preliminary remediation goal in diverse environmental media. 석유는 일단 토양이나 지하수로 유출되면 물리적,화학적 및 생물학적인 분배 과정을 거치면서 그 조성과 독성이 쉽게 변하기 때문에 위해성을 정확하게 평가 하기가 매우 어려우며,그 성분은 수 백여 종의 지방족 및 방향족 탄화수소로 이 루어져 있기 때문에 각각의 개별물질 모두를 위해성평가해서 최종 토양정화 목 표치를 설정하는 것은 거의 불가능하다.따라서 그 대안으로 유류를 지방족과 방 향족탄화수소로 분리하고,다시 유류성분의 물리적 특성을 감안하여 여러 구간으 로 세분하여 위해성평가를 하는 방법이 미국을 중심으로 대두되었으며,현재 각 국가들의 법률과 사회경제적인 문제를 반영시키는 다양한 위해성 평가기법들이 개발되어 제시되어 있다. 우리나라는 2004년에 토양정화를 위해성에 근거하여 시행할 수 있는 법률을 제정하였고,2006년에 구체적 수행방법에 대한 토양오염위해성평가지침을 마련하 였으나,현재까지 위해성평가에 의한 오염토양의 복원은 본격적으로 시행되지 않 고 있다.더욱 유류의 토양위해성평가 항목에 BTEX는 설정되어 있으나 총석유 계탄화수소(TPH)는 배제되어 있다. 본 연구는 세계 여러 국가나 기관에서 유류오염토양을 정화할 때 사용하는 석 유계탄화수소의 위해성에 근거한 일반적 정화목표치(RBSL)산정기법들을 고찰하 고,주로 미국의 TPHCWG(TotalPetroleum CriteriaWorking Group)가 제시한 탄화수소의 구간분획을 통한 위해성평가 및 정화목표치 산정방법을 국내 실정에 맞게 보완 및 개선하여 제시하고자 하였다. 탄화수소구간 분획은 주로 미국 TPHCWG가 제시한 방법을 토대로 환경에서 그 이동성과 인체 위해수준이 뚜렷이 구별되는 지방족과 방향족탄화수소그룹으 로 크게 분리하고,다시 각 그룹별로 등가환산탄소수(EC)를 기준으로 지방족그룹 은 EC _(5)-EC _(6), >EC _(6)-EC _(8), >EC _(8)-EC _(10) , >EC _(10)-EC _(12), >EC _(12)-EC _(16) >EC _(16)-EC _(21) 및 EC _(21)-EC _(35의) 7개 구간으로 분획하였으며,방향족그룹은 벤젠,톨루엔,>EC _(8)-EC _(10), EC _(10)-EC _(12),>EC _(12)-EC _(16),>EC _(16)-EC _(21) 및 >EC _(21)-EC _(35의) 7개 구간으로 분획하여 총 14개 탄화수소구간을 설정하였다. 선정한 탄화수소구간별로 등가환산탄소수와 개별성분 특성값 간의 상관관계식 을 사용하여 물리화학적 특성값을 부여했으며,TPHCWG가 배정할 당시에 이론 적 근거로 제시했던 방법을 그대로 사용해서 미국 EPA의 IRIS등에서 제시한 최 근 자료로 독성허용기준을 보완하여 배정하였다. 탄화수소구간별 고유 정화목표치는 인체노출인자와 입력변수 기본값을 선정해 서 미국 ASTM의 산정 모델에 적용하여 산출하는 방법을 제안하였으며,제시한 방법을 사용해서 표토,심토 및 지하수로부터 유래한 총 10개의 노출경로를 대상 으로 산출한 결과 방향족그룹이 용해도가 높기 때문에 토양에서 지하수로 이동 하기가 더 용이하고 인체에 노출될 가능성이 크다는 점과 독성이 높아서 독성허 용기준이 낮다는 점을 반영하여 지방족그룹에서 산정한 결과보다 대부분의 경우 상당히 낮은 것을 알 수 있었다.노출경로별로 산출한 결과는 표토의 직접노출 경로에서는 다른 경로보다 위해성이 미칠 영향정도가 적은 것으로 나타났으며, 심토로부터의 노출경로에서는 심토에서 실내공기로 휘발하는 증기흡입에 의한 노출경로에서 가장 낮았으며,심토에서 용출하는 지하수 섭취에 의한 노출경로에 서는 방향족그룹의 탄화수소구간이 훨씬 낮게 나타났고,등가환산탄소수가 높은 구간으로 갈수록 용해도가 낮아지기 때문에 급격하게 높아졌다. TPHCWG가 제시한 정화목표치와 비교한 결과,적용한 독성허용기준치와 인체노출인자 및 입 력변수 기본값 때문에 나타난 약간의 차이를 제외하고 전반적으로 유사한 결과 를 나타내었으며,산출 방법상 문제점은 나타나지 않았다. 가솔린,등유,경유 등 3종의 풍화되지 않은 상업용 유류를 대상으로 본 연구 에서 제시한 방법으로 일반적 정화목표치를 산정하였으며,그 과정에서 탄화수소 구간별 정화목표치와 탄화수소농도비율을 사용하여 목표 유해지수(HI)에 도달할 때 까지 반복 입력하는 오류 보정과정을 거치면 정화목표치를 최종 산정할 수 있었음을 확인하였으며,TPHCWG 방법을 사용하여 산정한 정화목표치와 비교한 결과,새롭게 추가한 지방족그룹의 >EC _(21)-EC _(35) 구간이 산정에 미치는 영향은 이 구간의 높은 독성허용기준과 낮은 이동성 때문에 거의 없는 것으로 나타났다.또 한 가솔린에서 벤젠에 대해 적용했던 독성허용기준의 차이로 인해서 나타난 경 우를 제외하고 전반적으로 유사한 결과를 나타내어 풍화되지 않은 유류의 석유 계탄화수소에 대해서 일반적 정화목표치를 산정할 때 활용 가능성이 높음을 보 여주고 있다. 최근 기름유출사고로 인해 경유,크레오소토유,원유로 오염된 토양에서 본 연 구에서 제시한 방법으로 석유계탄화수소의 일반적 정화목표치를 산정한 결과,유 종과 풍화여부에 관계없이 기존 시험방법의 일부를 간단하게 변경시켜 분석하는 것만으로도 위해성을 다양하게 정량화할 수 있고,토양복원에 대한 의사결정 자 료인 일반적 정화목표치를 손쉽게 산정할 수 있었다. 이와 같이 본 연구에서 제시한 방법의 용도는 유류로 오염된 토양이나 지하수 의 석유계탄화수소에 대하여 첫째,위해성에 근거한 일반적 정화목표치(RBSL)와 부지특이적 정화목표치(SSTL)의 산정도구로서 사용될 수 있으며,둘째,위해성평 가모델링 작업을 아주 단순화시켜 비용 효과적인 위해성평가도구로서 사용될 수 있고,셋째,다양한 환경매체에서 위해성에 근거한 규제 기준치와 사전정화목표 치를 설정하고자 할 때 기초자료로서 유용하게 활용될 수 있다.