Abstract: Aiming at the increasing worsening of non-point source pollution and the great change of land use pattern in Taihu Lake watershed, this paper studied the spatiotemporal variation of non-point source pollution in an area of the watershed based on source-sink landscape change. The test area was located in the 3 km buffer zone of Dati west bank of Taihu Lake, and 10 main channels in Yixing City connected with Taihu Lake were selected as the sampling plots. The source-sink location-weighted landscape contrast index (LCI) of these channels was calculated based on source-sink landscape theory, in addition to water sample collection and water quality analysis. Temporally, the LCI of 8 of the 10 channels had an obvious decrease in 2010, as compared with that in 2004. Correspondingly, a main indicator of water quality, NH+4-N content, was decreased by 41.0%. The other parameters had no significant change. Spatially, the LCI was mainly affected by landscape pattern, and positively correlated with the comprehensive water quality identification index. Our results implied that the spatial change of the landscape pattern in the channels connected with Taihu Lake could obviously affect water quality. In sum, the LCI was closely correlated with the water quality indicators NH+4-N and total N, the variation trend of the LCI was in accordance with that of the water quality, and the source-sink LCI could better reflect the generation and translocation of non-point source pollution.

Key words: Populus euphratica population, point pattern, spatial distribution, lower reaches of Heihe River.