Effects of soil amendment with PCB-contaminated sediment on the growth of two cucurbit species

The aim of the study was to evaluate the influence of the application of increasing proportions (0%, 10%, 25%, 50%, 75%, and 100%) of an admixture of PCB-contaminated Hudson River sediment collected from the Upper Hudson River, near Waterford, Saratoga county (New York, USA) on soil properties, phytotoxicity, and biometric and physiological responses of cucumber (Cucumis sativus L. cv 'Wisconsin SMR 58') and zucchini (Cucurbita pepo L. cv 'Black Beauty') grown as potential phyto- and rhizoremediators. The experiment was performed for 4 weeks in a growth chamber under controlled conditions. Amendment of Hudson River sediment to soil led to a gradual increase in PCB content of the substratum from 13.7 mu g/kg (with 10% sediment) to 255 mu g/kg (with 100% sediment). Sediment amendment showed no phytotoxic effects during the initial stages, even Lepidium sativum root growth was stimulated; however, this positive response diminished following a 4-week growth period, with the greatest inhibition observed in unplanted soil and zucchini-planted soil. The stimulatory effect remained high for cucumber treatments. The sediment admixture also increased cucurbit fresh biomass as compared to control samples, especially at lower doses of sediment admixture, even though PCB content of the soil amended with sediment increased. Cucurbits' leaf surface area, in turn, demonstrated an increase for zucchini, however only for 50% and 75% sediment admixture, while cucumber showed no changes when lower doses were applied and decrease for 75% and 100% sediment admixture. Chlorophyll a + b decreased significantly in sediment-amended soils, with greater inhibition observed for cucumber than zucchini. Our results suggest that admixture of riverine sediment from relatively less-contaminated locations may be used as soil amendments under controlled conditions; however, further detailed investigation on the fate of pollutants is required, especially in terms of the bioaccumulation and biomagnification properties of PCBs, before contaminated sediment can be applied in an open environment.