Accumulation of Co, Ni, Cu, Zn and Cd in Aboveground Organs of Chinese Winter Jujube from the Yellow River Delta, China

In the present study, winter jujube organs including fruit, fruiting leaf and foliage leaf, and associated soils in 14 typical orchards in Binzhou City, Shandong Province, China were collected and determined for the mass fractions of Co, Ni, Cu, Zn, and Cd. The mass fractions of Co, Ni, Cu, Zn, and Cd in plant tissues generally showed an order of Cu > Zn > Ni > Co > Cd as well as those in the soils decreased as Zn > Cu > Ni > Co > Cd. The values of single factor index and Nemerow pollution index suggested the jujube fruits were not polluted by heavy metals. Values of estimated daily intake for all the elements were far below their associated acceptable reference values, indicating no health risks would be caused by a single trace element. The results of targeted hazard quotient (THQ) of the metals in the fruits decreased as Cu > Ni > Zn > Cd accompanying total THQ (TTHQ) lower than 1 showing no hazard would be caused by those metals. Correlation analysis showed soil might not be the main source of heavy metals in winter jujube organs. Bioaccumulation factors (BAFs) for Co, Ni, Zn and Cd in fruits and leaves were far below 1 suggesting their low bioavailablities. The relatively great BAFs of Cu in the leaves might be due to the application of fertilizers and pesticides containing great amounts of Cu through soil and foliar spraying. To sum up, heavy metals tended not to be a major threat to winter jujube cultivation, and winter jujube had great edible safety.