Polychlorinated biphenyls (PCBs) in vegetables and soils from the southeastern region of Bs. As. Province, Argentina

GONZALEZ, MARIANA; MIGLIORANZA, KARINA SILVIA BEATRIZ; GERPE, MARCELA SILVIA; MENONE, MIRTA LUJAN; AIZPÚN, JULIA ELENA; MORENO, VICTOR JORGE

Buenos Aires

Congreso; 6ta Reunión Anual SETAC Latina; 2003

SETAC Latina

In order to evaluate the occurrence and distribution of polychlorinated biphenyls (PCBs), samples of edible vegetables and soils were analysed. Two sites differing in proximity to industrial areas were chosen: Los Padres lake which is situated within a protected watershed, and Santa Paula, located in the vicinity of an industrial area. Moreover, two tillage practices were considered, organic and conventional. PCBs residues in lettuce (L. sativa), tomato (L. esculentum) and carrots (D. carrota) tissues (aerial and subterranean) and soil fractions (0-15 and 15-30 cm) were analysed by GC-ECD. The results showed that soils conventionally treated had higher levels in the vicinity of industrial areas (Santa Paula). By the other hand when soils from Los Padres watershed were compared those from organic farming showed the lowest PCB levels. Moreover, a PCB concentration enrichment with depth increasing was observed. Lower chlorinated congeners were the predominantly PCBs in conventional and organic soils. Lettuce and carrots had the highest  PCB concentration in the range of 83 - 240 ng/g dry weight. Moreover, leaves of organically cultivated lettuce had higher PCB residues than the same produce conventionally cultivated. Although PCB # 15 was the main congener in lettuce tissues from both farms, an enrichment in higher chlorinated PCBs was observed in the organic farm. Peel from tomato fruit and carrots roots showed lower PCB levels (ng/g dry weight) than flesh. Although differences in the homologue distribution was observed between tomato and carrots, the opposite was true for tissues within each produce. Tetra and hexa PCB homologues were mainly found in tomato fruit while di, tetra, and penta PCB homologues were predominantly present in root carrots. Conversely to the expected results, higher PCB pollution was found in vegetables grown far from the industrial area. These results could be due to differences in the farms environment. Thus, in Los Padres lake, farms are surrounded by a variety of vegetation which could act as a PCB trap avoiding the dilution of these pollutants in the atmosphere. While the farm in Santa Paula is located in a more open area where pollutants are probably more easily dissipated and thereby less available to vegetation. Moreover, differences in total PCBs concentration between soils from organic and conventional farms of the same site, could be explained by differences in tillage practices. Key words: polychlorinated biphenyls, vegetables, soils,