三种杂草不同时期镉质量分数研究

Contents of cadmium in of three weeds in different growing stages

通过在沈阳张士镉污染区按每月8日、23日左右(中国北方24节气日)采集生物量较大的芦苇Phragmites australis、稗草Echinochtoa crusgalli和藜Chenopodium进行Cd质量分数和Cd质量分数最大的时期研究。结果表明:芦苇根Cd质量分数在6月8日(芒种)达到最大值(80.63 mg.kg-1),茎叶Cd质量分数在9月8日(白露)达到最大值(39.40 mg.kg-1);藜根9月8日(白露)Cd质量分数为22.65 mg.kg-1,茎叶10月24日(霜降)Cd质量分数为12.23 mg.kg-1,都是生长时期的最大值;稗草根Cd质量分数10月8日(寒露)达到最大值(182.59 mg.kg-1),茎叶Cd质量分数在9月23日(秋分)达到最大值(37.67 mg.kg-1)。芦苇、藜和稗草根及茎叶中的Cd质量分数一般均在秋季达最大值,而且这个时期杂草的生物量也比较大,因此秋季是最佳的杂草收割季节。另外,稗草比芦苇、藜能更有效地带出土壤中的Cd。

Absorption and accumulation of Cd in different growth periods by 3 weeds that grows in the Cd-contaminated area at Zhangshi Irrigation in Shenyang were studied with sampled around the 8^th and 23^ra at every month （in term of Solar Terms in China）. It could takeoff more Cd from soil if weeds were harvested in the highest concentration period. The results shown that the Cd concentration in root of Phragmites reached the max on the 8^th of June （Grain in Ear）, was 80.63 mg.kg^-1, in shoot on the 8^th of September （White Dew） was 39.40 mg.kg^-1. The Cd concentration in root of Chenopodium on the 8^th of September （White Dew） was 22.65 mg.kg^-1, in shoot on the 24^th of October （Frost＇ s Descent） descends was 12.23 mg.kg^-1, they were the highest in root and shoot at growth period, respectively. The Cd concentration in root of Echinochtoa crusgalli on the 8^th of October （Cold Dew） reached the max, was 182.59 mg.kg^-1, in shoot on the 23^ra of September （the Autumnal Equinox） was 37.67 mg.kg^-1. To sum up, the Cd concentration in root and shoot of Phragmites, Chenopodium and Echinochtoa crusgalli reached the max in autumn commonly. At this period biomass of weeds also reached the max. Consequently, autumn was the best season to harvest weeds. In addition, Echinochtoa crusgalli was more effectively than Phragmites and Chenopodium.