Abstract: According to the monthly monitoring data of eight water quality indicators at 20 sites from January 2014 to February 2017, we probed into the spatio-temporal variations and influential factors of water quality in streams of Minjiang River basin via multivariate statistical method and identified the sources of water pollutants. In temporal scale, the water quality in Minjiang River basin can be categorized in line with two time periods: T1 (April to December), during which the water quality is good with ammonia nitrogen as major pollutant overwhelmingly coming from agriculture;and T2 (January to March) when ammonia nitrogen and total phosphorus are dominant pollutants.In spatial scale, the water quality in Minjiang River basin can be classified according to three regions: the S1 region located in the downstream of Jianxi River, the Shaxi River, the Dazhang River and the main stream of Minjiang River where water quality is the worst with nutrients as main pollutants followed by oxygen consumption organics coming from the industrial wastewater, agricultural and livestock husbandry sewage, and sanitary sewage from cities of Fuzhou, Sanming, and Nanping;the S2 region which is located in the downstream of Shaxi River and the mid-upper reaches of Futun River featured by good self-purification ability and the best water quality with nutrients coming from non-point source pollution; and the S3 region which stands for the mid-upper reaches of Jianxi River and Futun River, with agricultural non-point source pollution as chief pollution source.

Key words: water quality analysis, spatio-temporal distribution, pollutants source identification, multivariate statistical method, Minjiang River watershed