The distributions,composition and their determining factors of polycyclic aromatic hydro-carbons in emergent macrophytes in Small Baiyangdian Lake

The contents of 16 priority polycyclic aromatic hydrocarbons(PAHs) in the seven tissues of three species emergent macrophytes from five sampling sites in Small Baiyangdian Lake nearby Duancun Village were measured by GC-MS.The PAHs distribution, composition,and their determining factors were analyzed.The following results were obtained;(1) the total dry-weight contents of 16 priority PAHs(PAH_(16)) ranges from 82.5 to 448.6ng/g(dw),with the average contents of 448.6ng/g(dw) in lotus leaves,129.3 ng/g(dw) in lotus stems,292.6ng/g(dw) in cattail leaves,166.8ng/g(dw) in cattail stem,82.5ng/g(dw) in cattail roots,141.5ng/g(dw) in reed leaves and 90.0 ng/g(dw) in reed roots.This shows that highest contents are in leaves,followed by stems and roots.The significant positive relations among the contents of PAHs congeners in seven macrophytes tissues are observed, implying the very similar PAHs distribution patterns among seven tissues.(2)Of 16 priority PAHs,lower molecular weight PAHs are dominant with the percentages varying from 66.2%(in lotus leaves) to 89%(in cattail stems),while the percentages of moderate and higher molecular weight PAHs range from 10.2%(in cattail stems) to 32.6%(in lotus leaves) and from 0.6% (in cattail leaves) to 3.7%(in reed roots).Six PAH congeners including phenanthrene(Phe),fluoranthene(Fla),naphthalene (Nap),fluorine(Flo),pyrene(Pyr) and chrysene(Chr) are dominant components with average percentages of 35.3%, 15.5%,12.1%,11.7%,9.2%and 5.2%,standing for 89%of total 16 priority PAHs(PAH_(16)).3) PAHs contents in emergent macrophytes are observed to be significant positive relations with their lipid percentages,and to be significant negative relations with the octanol-water partition coefficient(K_(ow)) and octanol-air partition coefficient(K_(oa))of PAH congeners.