上海市郊蔬菜硝酸盐含量及评价

Nitrate in vegetable and its evaluation in suburb of Shanghai city

对上海市不同种类和不同种植方式下的蔬菜硝酸盐含量进行测定,以期了解上海市蔬菜的硝酸盐含量现状。结果表明,不同种类蔬菜硝酸盐含量(设为Y)由高到低依次为:Y(绿叶菜类)→Y(豆类)→Y(瓜类)→Y(茄果类)→Y(食用菌类);叶菜类的硝态氮含量较高,平均为463.95mg/kg;其次是豆类,平均值为141.91mg/kg;瓜类、茄果类、食用菌类蔬菜的硝态氮平均含量较低,分别为102.38mg/kg,38.81mg/kg,26.29mg/kg。耕作和种植制度均能影响硝酸盐在土体中的积累和迁移,由于管理方式不同,同一种蔬菜品种的NO3--N质量分数(设为y)由高到低依次为:y(大棚蔬菜)→y(露地蔬菜)→y(传统自留地蔬菜)。所有样品中叶菜类蔬菜的硝酸盐含量超过一级标准的占57.1%,污染指数最高的达3.50,污染较重;豆类、瓜类、茄果类、食用菌类样品中硝酸盐没有超过一级标准的,污染较轻。

Vegetable is a kind of plant that accumulated much nitrate easily. Nitrate content is an important index to evaluate vegeta-ble quality. Agricultural intensity is very high in Shanghai, applying too much fertilizer has affected farmland environment in some extent. Research results indicated that, there was the highest content of nitrate in greenery vegetable growing in green-houses with average value 463.95 mg/kg, followed by leguminous vegetable with 141.91 mg/kg, melon vegetable with 102.38 mg/kg, nightshade vegetable with 38.81 mg/kg, and the lowest content of nitrate was found in edible fungus vegetable whose average value was 26.29 mg/kg. Both cultivation and cropping system could affect nitrate accumulation and transference in soil. Because of different man-agement manner, there was more nitrate in vegetable growing in green-houses, followed by growing in opened air, and then by tradi-tional vegetable. Pollution in greenery vegetable was the most serious with 57.1 percent samples’ nitrate content exceeding level I of the standard, and the pollution index was up to 3.50. Nitrate in leguminous, melon and nightshade vegetable was below the level I, which indicated that these vegetable were slightly polluted.