As a method for assessing metal pollution in coastal sediments, various pollution indices have been used but has been limited from their comprehensive categories on the assessment of metal pollution and inconsistency of ecological risk. To investigate the optimal pollution index for metal contamination in coastal area, PCA analysis was carried out for 13 indices, including newly proposed index PTI, estimated from 8 metal concentration of sediments from 9 coastal area including domestic special management area for environmental pollution. PC 1 explained 74.9 % in total variance with Igeo was the first item including PTI, PELQ, PLI, TRI, STd and CSI, while PC 2 did 20.1 % with MPI, RI, PI, EF, mCd and Cf. Er and RI were not feasible at low ranged contamination because of high incidence of outlier from high toxicity coefficient of Hg (40) and Cd (30), as well as, PI, MPI, TRI, STd at high ranged contamination because of out of range from the highest categories. In the study, PTI, as an alternative index of STd, was applicable in potential toxicity and was proved optimal descriptive range for pollution category by PCA analysis with the highest correlated factors (0.964).
Toxicity of the sediment against 3 test organisms, Amphipod M. uenoi, Echinoids S. nudus and H. pulcherrimus, and Copepod T. japonicas was represented in order of As>Cu,>Hg for Amphiod, Cd>Cu>Hg for Echinoids, and Cd>Pb>Cu for Copepod. By the 2 steps data screening process, the sensitivity (SE) and 1-specificity (1-SP) was estimated and applied for ROC analysis to derive the optimal cutoff value as a low guideline for pollution indices. A high guideline was set as the highest PPV following floating percentile approach (FPA). The overall reliability (OR) in low guideline ranged 63.6-71.8 %, which met LAET guideline for protection of freshwater ecology. The suitability assessment of low guideline indicated that EF, mCd, MPI was reasonable but RI, TRI and STd need to adjusted as twice and Igeo, Cf, PI and PLI as 1.9-7.1 times as well. The high guideline, 65.6-72.3 % in OR met 2LAET guideline, for EF and mCd was within the reasonable range but others exceeded the range of their maximum range (MPI 3.2, Cf 16, PI 8.9, PLI 5.8 and STd 4.0 times).
The new approach for the sediment quality guideline for protection of marine ecosystem was proposed by following empirical approach and weight of evidence approach using 8 metals concentration (As, Cd, Cu, Hg, Ni, Pb and Zn) of the sediments from 294 sites on 8 coasts around Korea from May 2005 to May 2018. The highest overall reliability was achieved in PEL than AET, ERM. For the better improved reliability, data screening was necessary in both of geometric mean of nontoxic data and background data. The derived element dependent PEL indicated that the present domestic value is need to be adjusted as 75.5 into 91.8 mg/kg for AS, 2.72 into 3.30 mg/kg for Cd, 64.4 into 237 mg/kg for Cu-Li normalized, 0.62 into 0.81 mg/kg for Hg, 118 into 195 mg/kg for Pb and 157 into 503 mg/kg for Zn-Li normalized, while, 181 into 160 mg/kg for Cr and 80.5 into 73.3 mg/kg for Ni, respectively.
The integrated pollution index of each species for the protection of marine ecosystem in metal contaminated sediment was estimated using element dependent indices. The AUC ranged 0.621-0.732 with below 0.04 in standard error (p<0.005). The optimal cutoff value of each organism, selected the highest value among those of Youden index, Euclidean method and Index of union, was 0.35 for Amphipod, 0.46 for Echinoids, and 0.43 for Copepod, respectively. The integrated pollution index, 0.39, met the guideline of LAET in Washington, USA with 0.64 in PPV, 0.75 in NPV, and 0.71 in OR and proposed as mPELk-Q-low, whereas, the highest value of 0.90 in PPV did as mPELK-Q-high for new PEL in domestic guideline.
In the study, after comparison of 12 pollution indices, potential toxicity index (PTI) was proposed as new optimal pollution index in Chapter 2. In chapter 3, low and high guideline of 13 pollution indices including PTI was estimated for chemical and biological effect. From integration of metal elements and test organisms, in chapter 4, a modified SQG was proposed as domestic guideline for protection of marine ecosystem in Korea. This integrated guideline reasonably categorized the pollution levels based on the combination of concentration and exotoxicity regardless of rationality.