灌溉水质对土壤和夏玉米多氯联苯含量影响的试验研究

Effect of different irrigation water qualities on the contents of PCBs of soil and summer maize grain

为明确不同灌溉水质对土壤和夏玉米中多氯联苯PCBs含量的影响,2015年在北京市通州区永乐店镇北京市灌溉试验中心站布置了田间灌溉试验,设置了再生水灌溉、再生水和清水(地下水)交替灌溉和清水灌溉等3个处理,每个处理设置3个重复。采用气相色谱-质谱仪分析了土壤和夏玉米籽粒中7大类PCBs含量。研究结果表明采集的表层土壤和夏玉米籽粒仅四氯联苯含量高于实验检出限,一氯联苯、二氯联苯、三氯联苯、五氯联苯、六氯联苯和七氯联苯均未检测出。表层土壤PCBs含量为ND(未检出)至0.06μg/kg,各处理间没有显著差异;土壤PCBs含量远低于加拿大农业土壤质量指导值和荷兰土壤质量标准中的干预值,且其生态风险概率小于10%。供试5个品种夏玉米籽粒产量为1.03~5.92t/hm^2;与清水灌溉相比,再生水灌溉条件下夏玉米籽粒产量增加52%~116%。甜玉米2000除外,其他品种夏玉米再生水灌溉条件下籽粒产量显著高于清水灌溉。夏玉米籽粒PCBs含量为ND至1.74μg/kg,总体上同一品种不同灌溉水质条件下籽粒PCBs含量无显著差异。夏玉米籽粒PCBs含量低于美国卫生及公共服务部建议指标。

In order to find out the effect of reclaimed water irrigation on the concentration of polychlorinated biphenyls （PCBs） of topsoil and summer maize grain, a field experiment was carried out at the Yongledian Experimental Base, the Beijing Water Science and Technology Institute （39°20′ N; 114°20′ E; 12 m a.s.l.） in 2015. There were three treatments with three replicates, respectively, including reclaimed water irrigation,alternative irrigation, and irrigation with groundwater. Seven kinds of PCBs in topsoil samples and summer maize grain samples were detected by gas chromatography-mass spectrometry （GC-MS）. The results showed that only the concentrations of 4-PCB, which could be detected, were higher than the detection limit, whereas 1-PCB, 3-PCB, 5-PCB and 7-PCB couldn＇t be detected. The total concentrations of PCBs in topsoil ranged from ND （lower than the detection limits） to 0.06 μg/kg, and there was no significant difference for PCBs in soil among different treatments. According to soil quality guidelines in Canada and American researcher＂ risk assessment report, the concentrations of PCBs in soil in this study did not pose a threat to the surrounding ecological environment. The grain yield of summer maize ranged from 1.03 to 5.92 t/hm^2. The yield of summer maize irrigated with reclaimed water was increased by 52%-116% compared with those of groundwater irrigation treatments. The grain yields with reclaimed water irrigation were significantly higher than those with groundwater irrigation （except tianyumi 2000）. The concentrations of PCBs in summer maize grains were ND to 1.74 μg/kg. There was no significantly difference for PCBs content in summer maize grain for each variety among the three treatments. The concentrations of PCBs in summer maize grain in this study were lower than the corresponding reference limit proposed by the U.S. Department of Health and Human Services.