토양시료의 분쇄가 왕수분해법을 이용한 비소와 납의 전함량 분석 결과에 미치는 영향

The effect of soil grinding on total As and Pb concentrations determined by aqua regia method was examined. Among six field-collected, air-dried soil samples tested, soils A, B, C, and E were directly sieved through a 150-μm sieve without grinding and showed 2.18 to 3.03 times higher total As concentrations and 2.62 to 3.45 times higher total Pb concentrations than those of the soil samples prepared to allow all soil particles to pass through the 150-μm sieve by grinding. The reason can be ascribed to the fact that those soils contain fine particles (i.e., < 150 μm in diameter) only 4.6 to 6.8% of the total soil weights. On the other hand, for D and F soils, fine particles smaller than 150 μm accounted for 57 and 46%, respectively, so that the effect of grinding on As and Pb concentrations were relatively low (As: 1.15 and 1.23 times, Pb: 1.36 and 1.49 times, respectively). The result demonstrates that grinding prior to 150-μm sieving is necessary to ensure the homogeneity of soil samples and hence to obtain more accurate heavy metal concentrations in soils. This is especially true for soil samples with less fine soil particles and/or microaggregates (i.e., below 150 μm).