Arsenic in Vegetable Crops of a Horticultural Center of the Southeast Pampean Plain

Abstract

Intensive crops involve the application of fertilizers providing the nutrients for their growth. The prolonged use of these agrochemicals, mainly phosphates, is strongly linked to the accumulation of metals and arsenic (As) in soils. Previous results demonstrated the presence of As in phosphate fertilizers (≈ 25 mg/kg) used in one of the most important of Buenos Aires province horticultural centers, located in nearly Mar del Plata city. Therefore, we hypothesize that the prolonged use of them could be contributing As to the soils, which can be assimilated by the crops. In this way, vegetable samples (edible parts) from conventional crops (with application of fertilizers) and agroecological crops (without chemical fertilization) were taken. Samples of tomato (Lycopersicum esculentum), lettuce (Lactuca sativa), spinach (Spinacia oleracea), bell pepper (Capsicum annuum), beetroot (Beta vulgaris), brucella cabbage (Brassica oleracea var. gemmifera), broccoli (Brassica oleracea), corn (Zea mays) and potato (Solanum tuberosum) were dried at 60°C and stored in the freezer. The quantification of total As was carried out by Atomic Absorption Spectrophotometry with a hydride generation. Data were expressed in mg/kg dry weight. The limit of detection was 0.005 mg/kg. The As concentrations in the analyzed samples ranged from < 0.005 to 0.181 mg/kg. The highest levels were observed in fertilized beetroot leaves (0.181) and lettuce (0.148) while the lowest were in potato (0.006) and corn (<0.005). The concentrations of agroecological tomato and lettuce were between > 0.005 - 0.011, while those fertilized varied between 0.020 - 0.148. In turn, the agroecological vegetables presented lower concentrations compared to the fertilized ones. These results revealed that fertilizationpractices influence As content in vegetables analyzed in the study area. Arsenic concentrations in all studied vegetables did not exceed the maximum limit allowed by the Argentine Food Code (1 mg/kg, fresh weight); thus, the vegetables grown in the study area are currently safe for consumption. However, the accumulation of As in crops must be monitored periodically until fertilization practices not be modified.