重庆市蔬菜硝酸盐、亚硝酸盐含量及其与环境的关系

CONTENTS OF NITRATE AND NITRITE IN VEGETABLES AND THEIR RELATIONS TO THE ENVRONMENTAL FACTORS IN CHONGQING AREA

在重庆市的主要蔬菜中，硝酸盐含量依次为根菜类＞叶菜类＞葱蒜类＞瓜类＞豆类＞茄果类，前３类的硝酸盐含量超标，但各种蔬菜的亚硝酸盐含量一般较低，未超过卫生标准。就同一种蔬菜的不同样品而言，硝酸盐和亚硝酸盐含量的差异很大，说明品种或环境条件可显著影响其含量。重庆市多雾少光，冬春低温，土壤含氮量和钠高子含量较高，有效钾含量较低可能是导致蔬菜大量积累硝酸盐的环境因素。蔬菜不同器官硝酸盐和亚硝酸盐含量各异，根＞茎＞叶柄＞叶片。

The contents of nitrate in the vegetables growing in Chongqing area varied significantly with different categories of crop species, i.e., root vegetables>leaf Vegetables>scallions>gourds>legumes>egg plants.And they were higher than the hygienical criterion stipulated by FAO in the first three categories of vegetables.The lower concentrations of nitrite inthe vegetables,on the contrary,were observed than the hygienical criterion.The samples of an identical vegetable cultivar also varied greatly in nitrate and nitrite contents.It suggested that their contents were affected by both the cultivars and environments.There existed some environmental factors affecting nitrate accumulation in the vegetables in Chongquing area such as cloud caused by dense fog,low temperature in spring and winter,low available potassium and high nitrogen and sodiumin in the soils.Moreover,the concentrations of nitrate and nitrite in various vegetable tissues were found different,i.e.roots>stems>petioles>leaves.