[Semen quality of the men from six districts in Chongqing]

To investigate the quality and spatial distribution features of semen and to evaluate the reproductive health of the males in the Chongqing section of the Three-Gorge Reservoir area.

We collected semen samples by masturbation after 2 -7 days of abstinence from the men in Nan'an, Shapingba, Zhongxian, Wanzhou, Yunyang and Wushan of Chongqing, which are geographically and demographically representative of the Three-Gorge Reservoir area. We analyzed the semen quality of all the samples and evaluated the reproductive health of the men.

The mean value of the five semen parameters of the male subjects from the six districts was within the normal range, including semen volume, sperm concentration, total sperm count, rapid progressive motile sperm, and total motile sperm. Those from Shapingba, Yunyang and Zhongxian exhibited abnormal sperm motility. According to the WHO criteria, normal value of all the semen parameters was found in less than 50% of the semen samples from the six districts, in 47% of those from Yunyang, and only 16% of those from Wanzhou. Spatial distribution maps of the semen parameters revealed significant spatial differences in seminal quality among the six districts, the highest in Yunyang, and the lowest in Wanzhou and Wushan that are located in the middle and lower reaches of the Three-Gorge Reservoir area.

The mean value of semen parameters was low in a large proportion of men in the Chongqing section of the Three-Gorge Reservoir area, with spatial differences along the Changjiang river.