The researchers studied pollution in the Weihe River caused by non-point sources. They monitored water quality and flow at two sections near Xianyang and Lintong. They found that pollutants like COD, NH3-N, and TN were highest during flooding seasons. Non-point sources accounted for 20-30% of pollution in 2009, with point sources from Xianyang and Lintong contributing over 80%. However, point source pollution decreased in 2009 compared to 2006, showing progress in pollution control. Non-point sources still play a significant role in water pollution in the Weihe River.