成都平原农区地下水中NO_3^--N含量变化规律研究

MONITORING NO_3^--N VARIATION OF GROUNDWATER IN AGRICULTURE REGION OF CHENGDU PLAIN

采用硝酸根电极法对成都平原温江县天府乡农区田间和水井的地下水NO-3 N含量进行了一年多的连续测定 ,探讨了该农区地下水中NO-3 N的变化规律和氮肥用量的影响。结果表明 :(1)田间地下水NO-3 N含量周年变化规律是冬春枯水季较高 ,且变幅较大 (0 3 6～ 2 62mgL- 1) ,平均值为 2 59mgL- 1;夏秋丰水季较低 ,且变幅较小 (0 84～ 5 48mgL- 1) ,平均值为 1 10mgL- 1。 (2 )前作麦季氮肥施用量 ,对稻季地下水中NO-3 N含量有明显影响 ,当前作施纯氮达 3 75kghm- 2 时 ,稻季地下水NO-3 N含量最高达 3 4 6mgL- 1,其平均值为 17 97mgL- 1,是施纯氮 150kghm- 2 平均值 1 3 0mgL- 1的 13 7倍。 (3 )井水中NO-3 N含量变化幅度为 0 14～ 16 53mgL- 1,3口井水平均值分别为 2 54、3 60、6 52mgL- 1,未超出我国生活饮用水卫生标准 ,但明显高于灌溉水NO-3 N含量的平均值 1 81mgL- 1。 (4)地下水位的高低与井水中NO-3

NO - 3 N content of groundwater in fields and wells at Tianfu village o f Chengdu plain was monitored by using NO - 3 N electrode method for more tha n one y ear. Results showed that: a. NO - 3 N concentration of groundwater in field s in wi nter and spring was higher than that in summer and autumn. The former ranged fr o m 0.36 to 2.62 mg L -1 with an average of 2.59 mg L -1 , and the co rresponding figu re for the latter was 0.84～5.48 mg L -1 and 1.10 mg L -1 , respecti vely. b. Rate o f applied N in wheat cropping season greatly affected NO - 3 N concentration of gr oundwater in the fields of subsequent rice cropping season. The NO - 3 N con centra tion of groundwater averaged 17.9 mg L -1 when N application rate was 375 kg hm -2 , and the average of NO - 3 N concentration was only 1.3 mg L -1 when 1 50 kg hm -2 w as applied. c. NO - 3 N in 3 wells was in the range of 0.14～16.5 mg L -1 with the mean value of 2.54, 3.60, and 6.52 mg L -1 , respectively, higher than th e average (1.81 mg L -1 ) of NO - 3 N concentration of irrigation water in the re gion. d. Level of groundwater was not correlated to NO - 3 N content of wells.