Abstract:

Nitrate contents of 73 samples of 19 species of vegetables from three categories collected from four farmers’
markets in Chongqing municipality were investigated. The contents of nitrate and nitrite in vegetables from 13 major
vegetable planting bases in Chongqing were analyzed and correlated with those of soil samples from these planting bases.
The results showed that significant differences in nitrate contents were observed among different vegetable species and
different parts of the same species, and the decreasing order was leaf vegetables (X = 1 619.73 mg/kg) ＞ solanaceous
vegetables (X = 1 327.67 mg/kg) ＞ allium vegetables (X = 1 078.39 mg/kg); and lettuce leaves (X = 1 567.91 mg/kg) ＞
lettuce stems (X = 1 871.62 mg/kg). The content of nitrate in all leaf vegetables exceeded level I standard, showing a pollution
index up to 9.09. About 81.3% of solanaceous vegetables and 87.5% of allium vegetables exceeded level I standard, and pollution
index was up to 8.85 and 6.56, respectively. Significant differences in nitrate nitrogen were found among different vegetable
species and among different parts of the same species from 13 vegetable planting bases, and the descending order was radish leaves
(X = 745.97 mg/kg) ＞ lettuce stems (X = 730.88 mg/kg) ＞ lettuce leaves（693.32 mg/kg) ＞ cabbages (X = 617.63 mg/kg) ＞
radish roots (X = 575.74 mg/kg). Significant differences in nitrate nitrogen were also observed in soils from the vegetable
bases, and the decreasing order was lettuce-growing soil (X = 75.24 mg/kg) ＞ cabbage-growing soil (X = 47.05 mg/kg) ＞
radish-growing soil (X = 33.42 mg/kg). Significant linear correlation of nitrate contents was found between vegetables and soils
(y = 407.872 + 4.769x). The contents of nitrite in vegetables and soils from 13 vegetable bases were low, without showing
significant differences. Moreover, no significant correlation of nitrite contents was found between vegetables and soils.

Key words: vegetables, NO3- -N, NO2--N, correlation