Abstract: Nitrate content is an important index to evaluate the quality of drinking water which affects human health directly.As to evaluate the nitrate contamination status of groundwater in rural areas of Shandong province,a large-scale investigation and water-sampling analysis on nitrate concentration in local groundwater from 16 cities was performed,and the main influence factors of nitrate contamination were studied.The results showed that the nitrate concentration of groundwater was affected obviously by sampling period,sampling area,and cultivation system.Lower nitrate concentration in groundwater after raining period was observed than that before raining period,as the concentration being 6.74mg·L-1and 14.12mg·L-1respectively.As to different cultivation systems,the highest nitrate concentration was observed in groundwater samples from open-field vegetable area followed by orchard area,protected vegetable area,and cereal,cotton and oil area,as the over-limit ration being 65.71%,60.71%,50.98% and 24.74% respectively.The nitrate contamination was also affected by sampling area significantly as the higher over-limit ratio was observed in Qingdao and Yantai than other cities,and the nitrate concentration in groundwater from Liaocheng,Dezhou,Binzhou,and Heze was found to be lower than 5mg·L-1.Of all the 516 water samples in Shandong province,the nitrate concentration was found to reach to 10.43mg·L-1and the over-limit ratio reach to 14.15%.

Key words: Groundwater, Groundwater, Nitrate, Sampling period, Sampling area, Cultivation system, Shandong province