Heavy Metal Analysis and Evaluation of Geotechnical Plant System of Dendrobii Officinalis Caulis in Typical Karst Area / 中国实验方剂学杂志

ABSTRACT

Objective:To systematically evaluate the safety of heavy metals in Dendrobii Officinalis Caulis and its rhizosphere soil and bedrock in epiphytic culture imitated wild rock fissure. The distribution characteristics of heavy metals in carbonate-black limestone-Dendrobii Officinalis Caulis system in the study area were analyzed. Method:Samples of biennial Dendrobii Officinalis Caulis， black calcareous soil and carbonate rocks were collected from fracture-epiphytic culture in karst area of Guizhou province. The contents of Cu， Pb， As， Cd in Dendrobii Officinalis Caulis， and Cu， Pb， As， Cd， Cr in soil and bedrock were determined by inductively coupled plasma-mass spectrometry （ICP-MS）. The detection conditions were as follows：plasma power of 1 550 W， feedback power of 2 W， sampling depth of 9 mm， atomization chamber temperature at 2 ℃， analysis mode of full quantitative， and double charge of <1.5%. Hg content in Dendrobii Officinalis Caulis was determined by atomic fluorescence spectrometry， and Hg content in soil and bedrock was determined by mercury analyzer. SPSS 26.0 software was used to analyze the test data. Result:The contents of Cu， Pb， As， Cd and Hg in Dendrobii Officinalis Caulis were all within the safety threshold. The contents of Pb， As， Cd， Hg and Cr in black calcareous soil were higher than the corresponding background values of Chinese soil （<italic>P</italic><0.05， <italic>P</italic><0.01）， Cd in black calcareous soil was slightly polluted， while Cr， Cu， As， Pb and Hg were clean. The contents of Cu， As， Pb， Cd， Hg and Cr in carbonate rocks were significantly lower than those in black calcareous soil （<italic>P</italic><0.01）. The order of heavy metals in black calcareous soil affected by parent rock was Hg>Cd>Cu>As>Cr>Pb. The bioconcentration factor （BCF） of heavy metals in Dendrobii Officinalis Caulis was in the order of Cu>Cd>Pb=Hg>As， but the BCFs of these five heavy metals were all low （all <10%）. The contents of Cu， Pb， Cd and Hg in Dendrobii Officinalis Caulis increased slightly with the increase of heavy metal content in the rhizosphere soil， while the content of As decreased with the increase of As content in the rhizosphere soil. In addition to Cu content in Dendrobii Officinalis Caulis， the migration characteristics of Pb， As， Cd and Hg in the system of carbonate-black limestone-Dendrobii Officinalis Caulis showed consistency. Conclusion:The distribution characteristics of heavy metals in geotechnical plant system in the study area show obvious inheritance. The characteristics of high content， low activity and low pollution risk of heavy metals in black limestone soil and low BCF are the main factors affecting the safety threshold of five heavy metals in Dendrobii Officinalis Caulis.