Institute of agricultural quality standards and testing,College of agriculture and animal husbandry,Tibet Autonomous Region,Lhasa
【目的】调查西藏四地市(山南市、日喀则市、林芝市、拉萨市)不同磨制方式生产的糌粑中重金属砷(As)、镉(Cd)、铬(Cr)、铅(Pb)、汞(Hg)含量,并开展污染情况全面分析评价,促使西藏各地市糌粑的质量安全水平能有所提高、为加强质量安全监管,提供可靠的数据支持。【方法】2021年从西藏四地市分别采集不同模式生产的糌粑样品101个,使用电感耦合等离子体质谱法对糌粑样品中5种重金属进行检测分析与质量安全评价。【结果】101个糌粑样品中,山南市糌粑样品中Pb的超标率为16.6%、污染贡献率3.85%,Cr的超标率为2.8%、污染贡献率2.78%,其它重金属含量均未超标；污染贡献率KAs为3.57%、KCd为100%、KHg为2.78%；日喀则市重金属均未超标,污染贡献率KAs为5.88%、KCd为0%、KCr为5.00%、KPb为25.00%、KHg为5.00%,林芝市除Pb超标率为8%,其它重金属均未超标,污染贡献率KAs为10.0%、KCd为0%、KCr为4.00%、KPb为8.33%、KHg为4.00%；拉萨市除Pb超标率为5%,其它重金属均未超标,污染贡献率KAs为8.33%、KCd为100%、KCr为5.00%、KPb为12.50%、KHg为5.00%；山南市糌粑中的重金属综合污染指数PCr=1.080,为轻度污染,PPb=2.863,为中度污染；日喀则市糌粑中的重金属综合污染指数PPb =0.778,为基本清洁；林芝市糌粑中的重金属综合污染指数PPb =3.076,为重度污染；除此之外的四地市中的重金属污染等级均是安全。按总的样品数,Pb的超标率最高为8.91%、Cr为0.99%,其它重金属均未超标；污染贡献率KCd为50.00%、KPb为2.00%、KAs为1.49%、KCr为0.99%、KHg为0.99%。按磨制方式,电磨糌粑中Cd作为主要重金属污染物,污染物贡献率高达50%；其他重金属污染贡献率KPb为4.35%、KAs为3.03%、KCr为2.33%、KHg为2.33%,重金属综合污染指数PCr=1.080,为轻度污染,PPb =3.111,为重度污染；水磨糌粑污染贡献率KAs为3.70%、KPb为2.94%、KHg为1.72%、KCr为1.72%、KCd为0%、,Pb作为主要的重金属污染物,其污染物贡献率高达3.70%。电磨糌粑中的重金属综合污染指数PAs =1.690,为轻度污染,PCr =5.650,PHg=22.956,均为重度污染；对糌粑样品进行单因素方差分析,结果显示,不同地市生产的糌粑中检出的重金属含量Hg存在显著差异,其余重金属差异均不显著。糌粑中各重金属相关性分析结果显示,重金属Cr的含量与重金属Cd含量呈显著正相关,Cd的含量与重金属Hg含量呈显著负相关(P＜0.01)。【结论】西藏四地市糌粑重金属Pb和Cd是主要污染物, Pb属重度污染,其它均属于安全。
[Objective] to investigate the contents of heavy metals arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb) and mercury (Hg) in Zanba produced by different grinding methods in four cities of Tibet (Shannan City, Shigatse City, Nyingchi city and Lhasa City), and carry out comprehensive analysis and evaluation of pollution, so as to improve the quality and safety level of Zanba in various cities of Tibet and strengthen quality and safety supervision, Provide reliable data support. [Methods] 101 Zanba samples produced in different modes were collected from four cities in Tibet in 2021. Five heavy metals in Zanba samples were detected, analyzed and evaluated by inductively coupled plasma mass spectrometry. [results] Among the 101 Zanba samples, the over standard rate of Pb in Zanba samples in Shannan city was 16.6%, the pollution contribution rate was 3.85%, the over standard rate of Cr was 2.8%, the pollution contribution rate was 2.78%, and the contents of other heavy metals did not exceed the standard; The pollution contribution rate KAs is 3.57%, KCd is 100% and KHg is 2.78%; The heavy metals in Shigatse did not exceed the standard, and the pollution contribution rate was KAs of 5.88%, KCd of 0%, KCr of 5.00%, KPb of 25.00%, and KHg of 5.00%. In Nyingchi City, except for Pb of 8%, other heavy metals did not exceed the standard, and the pollution contribution rate was KAs of 10.0%, KCdof 0%, KCr of 4.00%, KPb of 8.33%, and KHg of 4.00%; In Lhasa, except that the standard exceeding rate of P b is 5%, other heavy metals do not exceed the standard, and the pollution contribution rate KAs is 8.33%, KCd is 100%, KCr is 5.00%, KPb is 12.50% and KHg is 5.00%; The comprehensive pollution index of heavy metals in Zanba in Shannan city is PCr = 1.080, which is light pollution, Ppb = 2.863, which is medium pollution; The comprehensive pollution index of heavy metals in Zanba in Shigatse City isPpb = 0.778, which is basically clean; The comprehensive pollution index of heavy metals in Zanba in Nyingchi city isPpb = 3.076, which is heavy pollution; In addition, the heavy metal pollution levels in the four cities are safe. According to the total number of samples, the highest exceeding standard rate of Pb is 8.91%, Cr is 0.99%, and other heavy metals do not exceed the standard; The pollution contribution rate KCd is 50.00%, KPb is 2.00%, KAs is 1.49%, KCr is 0.99% and KHg is 0.99%. According to the grinding method, Cd in Zanba is the main heavy metal pollutant, and the pollutant contribution rate is as high as 50%; The contribution rate of other heavy metals is 4.35% for KPb, 3.03% for KAS, 2.33% for KCr and 2.33% for KHg. The comprehensive pollution index of heavy metals is PCr = 1.080, which is light pollution and Ppb = 3.111, which is heavy pollution; The pollution contribution rate of water mill Zanba is 3.70%, KPb is 2.94%, KHg is 1.72%, KCr is 1.72%, KCd is 0%, Pb is the main heavy metal pollutant, and its pollutant contribution rate is as high as 3.70%.The heavy metal comprehensive pollution index PAs = 1.690, which is light pollution, PCr = 5.650, PHg = 22.956, which are all heavy pollution; The results of one-way ANOVA of Zanba samples showed that there were significant differences in the content of Hg in Zanba produced in different cities, and there were no significant differences in other heavy metals. The results of correlation analysis of heavy metals in Zanba showed that the content of heavy metal Cr was significantly positively correlated with the content of heavy metal Cd, and the content of Cd was significantly negatively correlated with the content of heavy metal Hg (P < 0.01). [Conclusion] Pb and Cd are the main pollutants in Zanba in four cities of Tibet. Pb is seriously polluted, and others are safe.