Heavy Metal Pollution Assessment of Vegetables in Pudong Zone of Shanghai

Vegetable security is important to our life, and it is absolutely necessary to set up city outskirt biogeocenose system. With industry and agriculture development, atmosphere, water and soil are getting more polluted. So vegetable is polluted in some degree. We measured and analyzed contents of heavy metals in vegetables in 4 gardening fields and 2 sewage sludge regions in Pudong zone of Shanghai city and then evaluated single pollution index by national vegetable environmental quality standards. The results of all single pollution index values in 4 gardening fields were less than 1, which indicated no pollution and the vegetables in gardening fields meeting environmental requirement. The enrichment of heavy metals in vegetables differed with their different physiological characteristics, growth time and sensitive degrees to contamination. The results showed that green-leaves absorbed more Cr, Cd, Hg and As than other vegetables. Heavy metal contents for same kind vegetable that planted in different areas also differed greatly, which mainly related to heavy metal contents of soil and irrigation water of planting area. Generally, the higher heavy metal contents in soil and irrigation water, the more accumulation of heavy metal contents in vegetables. Heavy metal contents in gardening field vegetable were significantly different from that in sewage irrigated area vegetable. Single pollution indexes of Cu, Zn, Pb and As were less than 1 in nine vegetable samples collected from sewage irrigation regions, while, indexes of Cd and Cr in both of them were more than 1, suggesting 100% were polluted, and among these, one was seriously polluted resulted from the application of Huangpu river sewage sludge. So it was necessary to carry out irrigation water standard strictly and forbid blindness irrigation to prevent soil and vegetable pollution.