Semivolatile organic compounds in surface microlayer and subsurface water of Dianshan Lake, Shanghai, China: implications for accumulation and interrelationship.

Semivolatile organic compounds (SVOCs) in surface microlayer (SML) and subsurface water (SSW) from Dianshan Lake were studied to investigate their occurrence, distributions, as well as enrichment and potential sources. A sample was concentrated by solid-phase micro-extraction (SPME). Identification and quantification were carried out by gas chromatography coupled to mass spectrometry (GC-MS). Total SVOCs concentrations ranged from 25.93 to 47.49 μg/L in SSW and 38.19 to 77.23 μg/L in SML. The phthalic acid esters (PAE) concentrations in both SSW and SML are the highest of the total SVOC. The enrichment factors (EFs) of total SVOCs ranged from 0.80 to 2.98, while the highest EF was found in benzyl phthalate and dibutyl phthalate, compounds of PAEs (4.06). The EFs values calculated in this study were consistent with the EFs reported for other water ecosystems. Compared with other place, the EF of PAHs were in the normal level (0.88-2.37). The results of correlation analysis, principal component analysis (PCA) suggested that at least three sources, i.e., agricultural residual pesticides, industrial sewage and miscellaneous sources, were responsible for the presence of SVOCs in Dianshan Lake examined, accounting for 94.16% of the total variance in the dataset. Environmental risk assessment revealed that a majority of SVOCs posed relatively low risks (the values of risk quotient were less than 0.1), while naphthalene, acenaphthene, 2,4-dinitrotoluene, and dibutyl phthalat exhibited moderate risks (values of risk quotient were more than 0.1 but less than 1fore) to aquatic organisms.