Phosphine (PH 3 ) was monitored in the Taihu Lake in China by a GC/NPD method, coupled with cryo-trapping enrichment technology. Results showed that PH 3 was universally detected in sediments, lake water and atmosphere of the Taihu Lake area. Total phosphorus (TP s ) and fractions of different phosphorus species in lake sediments were separately measured as dissolved phosphate (DP), phosphorus bound to aluminum (Al-P), iron (Fe-P) and calcium (Ca-P), occluded phosphorus (OP), and organic phosphorus (Org-P) by sequential chemical extraction. High PH 3 levels were correlated with high TP s values in sediments and with eutrophication at different sites. In addition, a positive linear correlation equation was obtained between the concentrations of PH 3 in lake sediments and of the phosphorus fractions. The resulting multiple linear regression equation is PH 3 = À165 + 63.3 DP + 0.736 Al-P + 2.33 Ca-P + 2.29 Org-P. The flux of PH 3 across the sediment-water interface was estimated from sediment core incubation in May and October 2002. The annual average sediment-water flux of PH 3 was estimated at ca. 0.0138±0.005 pg dm À2 h À1 , the average yearly emission value of PH 3 from Taihu Lake sediments to water was calculated to be 28.3±10.2 g year À1 , which causes a water PH 3 concentration of up to 0.178±0.064 pmol dm À3 . The real importance of PH 3 could be higher, because PH 3 could be consumed in the oxic sediment-water boundary layer and in the water column. Spatial and temporal distributions of total phosphorus (TP w ) and chlorophyll a (Chl-a) in the water column of Taihu Lake were measured over the study period. Higher water PH 3 has also been found where the TP w content was high. Similarly, high Chl-a was consistent with higher water PH 3 . Positive relationships between PH 3 and TP w (average R 2 = 0.47±0.26) and Chl-a (average R 2 = 0.23±0.31) were observed in Taihu Lake water.