Leachability of phenanthrene from soil under acid rain and its relationship with dissolved organic matter

Acid rain is a serious environmental problem in the world. Soil columns were leached with simulated acid rain (SAR) at pH ranging from 2.5 to 5.6. The impact of SAR on the release of phenanthrene from red soil and its correlation with dissolved organic carbon (DOC) in eluates were investigated. The results showed that the leaching loss of phenanthrene was affected by both the leaching volume and acidity of SAR. When the leaching volume was less than 500 mm, the phenanthrene concentration in eluates decreased rapidly with increasing leaching volume, indicating a high rate of leaching loss at the beginning of leaching; then with continuous leaching, the phenanthrene concentration decreased slightly and reached zero when the leaching volume reached 875 mm. The lower pH of SAR was, the higher release rate of phenanthrene was. The change of DOC in eluates was similar to that of the phenanthrene concentration. The phenanthrene concentration had a significantly positive correlation with DOC in all eluates (the squared correlation coefficient R 2 varied between 0.952 and 0.997). Three-dimensional fluorescence analysis revealed that phenanthrene was associated with humic acid and fulvic acid, and was released with dissolved organic matters leached by SAR.