The nitrate concentration of domestic vegetables on Helsinki market in summer and autumn 1984

Nitrate concentration of some domestic vegetables at Helsinki district market was studied during the summer and autumn months of the year 1984.The species were cabbage (Brassica oleracea var capitata), Chinese cabbage (Brassica pekinensis), kohlrabi (Brassica oleracea var gongylodes), turnip (Brassica rapa), carrot (Daucus Carola subsp. sativas) and crisphead and butter head lettuce (Lactuca saliva var. capitata). The 395 samples were analysed with an ion specific electrode. There was a wide range of nitrate concentrations within each species. The mean concentrations mg nitrates/kg of fresh weight were the following: butter head lettuce 1835, Chinese cabbage 1057, kohlrabi 1008, crisphead lettuce 964, turnip 908, cabbage 607 and carrot 264. The nitrate concentration of butter head lettuce in the autumn was more than twice as high as that in the summer, and vice versa as to cabbage samples. The nitrate concentration of carrot samples in the summer was about 40 % higher than in the autumn.