北京市农田回用再生水中无机阴离子的 分布规律研究

目的建立离子色谱法测定北京市农田回用再生水水体中F~-、NO_3~-、NO_2~-、Cl~-、SO_4~(2-)和PO_4~(3-)6种无机阴离子的分析方法。方法分别采集北京某再生水厂出水口、再生水灌溉渠、农田灌溉点的36份水样,经Dionex OnGuard Ⅱ Ag/H银离子交换柱处理后,采用离子色谱法测定,色谱柱为Dionex IonPac~(TM)AS11-HC,检测器为电导检测器。结果该方法能有效分离6种无机阴离子,且在0.016~10 mg/L浓度范围内线性关系良好(r~20.99),相对标准偏差在0.54%~3.65%之间。北京市农田回用再生水中检出了不同浓度水平的6种无机阴离子,其中Cl~-检出浓度最高,浓度范围为121~211 mg/L,不同位点的再生水中的浓度存在空间分布差异,NO_3~-和PO_4~(3-)在再生水出水口的浓度要高于再生水灌溉渠和农田灌溉点。结论本方法稳定性和分离效果好,准确率高,可适用于再生水中6种阴离子的监测。建议加强农田回用再生水的长期监测,并根据作物种类和土壤类型等制定更加严格的农田回用再生水水质标准。

Distribution rules of inorganic anions in reclaimed water for farmland irrigation in Beijing

Objective To establish a method for the determination of 6 kinds of inorganic anions including F-, NO3-, NO2-, Cl-, SO42- and PO43- in reclaimed water for farmland irrigation in Beijing by ion chromatography. Method Thirty-six reclaimed water samples from Beijing recycled water outlet, reclaimed water irrigation canal and irrigation point of Beijing were detected by ion chromatography after treatment with silver ion exchange column of Dionex OnGuard II Ag/H column. The column was Dionex IonPacTMAS11-HC and the detector was electrical conductivity detector. Results The established method could effectively separate 6 kinds of inorganic anions and had good linear relationship in the range of 0.016~10 mg/L (r2>0.99) with the relative standard deviations of 0.54%~3.65%. Six kinds of inorganic anions with different levels were detected in reclaimed water for farmland irrigation in Beijing, and a large amount of Cl-, the concentration range of which was 121~211 mg/L, was detected in it. The concentration of NO3- and PO43-of different sites was different in the spatial distribution, 2 kinds of anion concentration at reclaimed water outlet were higher than that of recycled water irrigation canal and farmland. Conclusion The method has good stability and separation effect, and the accuracy is high, which can be applied to the monitoring of 6 kinds of anions in reclaimed water. The proposals are given such as strengthening the long-term monitoring of reclaimed water for farmland irrigation, and developing more stringent standards for irrigation water quality according to crop types and soil types.