토양 및 지하수 환경기준의 연계 강화 방안

Abstract

The objective of this work was to propose detailed methodologies for improving coherence between soil and groundwater standards. To achieve this objective, firstly, we reviewed existing soil and groundwater quality standards (including cleanup standards) of other countries and investigated detailed methodologies for relating soil standards to groundwater ones. We found that most countries set up soil cleanup standards in order to protect groundwater. So, they are taking into account simultaneous soil and groundwater contamination phenomenon. Since the USA and Netherlands are adopting a risk-based approach, called Soil Screening Guidance (SSG), to improve coherence between soil and groundwater standards. This approach seems reasonable to apply for Korea therefore, we adopted this methodology. After revising values of important parameters with Korean soil and hydrogeologic characteristics data, we applied the SSG methodology to identify coherence between soil and groundwater standards. We found that current soil quality (cleanup) standards were not coherent with groundwater quality (cleanup) standards or drinking water standards. Through the sensitivity analysis for soil screening levels, we found that a nationwide dilution-attenuation factor (DAF) value, which can explain reasonably the contamination phenomena in Korea, should be determined to calculate more realistic soil quality standards. Especially, the soil related parameters (e.g., organic carbon content, bulk density, and volumetric water content) affected greatly the soil screening levels (SSLs) for organic contaminants (not inorganic contaminants), indicating that we need to characterize the nationwide soil related parameter values. Furthermore, through several numerical simulations, we found that the DAF equation proposed by the U.S. EPA may not be appropriate for hydrogeologic characteristics of Korea, possibly due to very thin surficial aquifer depth in Korea. We believe that the following researches should be pursued further in order to develop the SSG procedure appropriate to Korea. Firstly, nationwide-, regional-, and local-scale DAF values (or maps) need to be determined through comprehensive surveys for hydrogeologic characteristics. Secondly, since groundwater pumped from rock aquifer is usually used in Korea, the DAF equation appropriate to rock aquifer needs to be developed. Lastly, parameters related to Korean soils need to be newly investigated or complied from existing data. These data are very important for setting up soil standards, especially for organic contaminants.