Effects Of Phosphate Or Organic Matter Applications On Arsenic Uptake By And Translocation In Isatis Indigotica

Based on National Quality Standard about Chinese herbal medicine, there was a serious problem about heavy metals accumulation in Chinese Herbal Medicines (CHMs) and even exceeding the standard in recent years. Heavy metals accumulated in CHMs through the food chain will cause a threat to human health. Isatis indigotica (Chinese name: Ban Langen) is a kind of traditional Chinese medicinal materials, which the root and shoot can be medicines. In addition, the previous results from our group showed that the pattern of As concentrations in roots and shoots of Isatis indigotica (As concentration in the shoots of Isatis indigotica more than that in roots of Isatis indigotica) was different from general plants (As concentration in the roots of Isatis indigotica more than that in shoots of Isatis indigotica). Based on this result, a survey in two regions (Anguo and Yu County) of Hebei Province, traditional cultivated areas, was conducted to explore As distribution in the roots and shoots of Isatis indigotica in natural condition. Moreover, a serial of experiments were conducted to investigate the effects of phosphate (P) or organic matter (OM) applications on arsenic uptake by and translocation in Isatis indigotica. The resules showed as follows:Anguo City and Yu Xian in Hebei Province were main planting area of Isatis indigotica. The average concentrations of As,Cd,Hg,Pb and Cu in soils from Isatis indigotica cultivated regions of Anguo City were 10.06,0.15,0.07,18.11,18.09 mg/kg, the average concentrations of As,Cd,Hg,Pb and Cu in roots of Isatis indigotica were 0.35,0.12,0.04,0.82,5.57 mg/kg,the average concentrations of As,Cd,Hg,Pb and Cu in shoots of Isatis indigotica were 0.32,0.16,0.04,1.42,6.19 mg/kg,respectively. The average concentrations of As,Cd,Hg,Pb and Cu in soils from Isatis indigotica cultivated regions of Yu Xian were 12.82,0.12,0.10,14.43,14.62 mg/kg,the average concentrations of As,Cd,Hg,Pb and Cu in roots of Isatis indigotica were 0.34,0.05,0.02,0.71,0.98 mg/kg,the average concentrations of As,Cd,Hg,Pb and Cu in shoots of Isatis indigotica were 0.37,0.14,0.04,0.98,4.94 mg/kg,respectively. Based on National Soil Environmental Quality Standard of Grade I, the As,Cd,Hg,Pb and Cu pollution indexes of Anguo City and Yu Xian were lower than 1. The concentrations of five heavy metals in Anguo City and Yu Xian of roots and shoots of Isatis indigotica could match with green standards of medicinal plants and preparations for foreign trade and economy (WM/T2-2004). However, the average levels of As and Hg in roots and shoots of Isatis indigotica from Anguo and Yu County were higher than the limitation in FDA.As concentration of the nutrient solution were 5,10,20μmol/L, based on these As concentration of P level of 400μmol/L, As concentration in shoots and roots of Isatis indigotica were significantly lower than P level of 5μmol/L. As concentration in shoots and roots of Isatis indigotica of P level of 5μmol/L were lower than P level of 5μmol/L in As concentration of 5μmol/L, the range of reducing was higher than others, the range of As concentration in roots of Isatis indigotica was from 14.12 mg/kg to 1.44 mg/kg, matching with green standards of medicinal plants and preparations for foreign trade and economy (WM/T2-2004). In the solution culture conditions, phosphorus significantly inhibited the As uptake and translocation.In the natural soil, different P levels did not influence As accumulation in the roots of Isatis indigotica, but reduced As translocation from roots to shoots. Moreover, application of 200 mg/kg significantly decreased As concentrations in shoots. At the arsenic-contaminated soil, P application had no effect on As levels in the shoots, but the level of 100 mg/kg reduced the accumulation of arsenic in the roots of Isatis indigotica significantly. However, higher level of P application (200 mg/kg) increased As concentrations in the root of Isatis indigotica; In the natural soil, OM10 reduced the arsenic accumulation in the roots and shoots of Isatis indigotica and the specific arsenic uptake significantly, and did not influence arsenic translocation in plant. In As-contaminated soil, OM5 decreased arsenic accumulation in the roots and shoots of Isatis indigotica and the specific uptake of arsenic, but increased arsenic transport from root to shoot in Isatis indigotica. When the level of organic matter increased up to 10 g/kg,the root-As level and the specific uptake of arsenic were higher than those of other treatments. Therefore, 200 mg/kg and 10 g/kg organic matter were suitable to decrease As accumulation in Isatis indigotica growing in natural soil, but 100 mg/kg and 5 g/kg organic matter were better to reduce arsenic concentrations in this herb medicine growing in As-contaminated soil.