title: Lead phytotoxicity in soils and nutrient solutions is related to lead induced phosphorus deficiency.
abstract: This study was set up to relate lead (Pb) bioavailability with its toxicity to plants in soils. Tomato and barley seedlings were grown in six different PbCl(2) spiked soils (pH: 4.7-7.4; eCEC: 4.2-41.7 cmol(c)/kg). Soils were leached and pH corrected after spiking to exclude confounding factors. Plant growth was halved at 1600-6500 mg Pb/kg soil for tomato and at 1900-8300 mg Pb/kg soil for barley. These soil Pb threshold were unrelated to soil pH, organic carbon, texture or eCEC and neither soil solution Pb nor Pb(2+) ion activity adequately explained Pb toxicity among soils. Shoot phosphorus (P) concentrations significantly decreased with increasing soil Pb concentrations. Tomato grown in hydroponics at either varying P supply or at increasing Pb (equal initial P) illustrated that shoot P explained growth response in both scenarios. The results suggest that Pb toxicity is partially related to Pb induced P deficiency, likely due to lead phosphate precipitation.
authors.affiliation: Laboratory for Soil and Water Management, K.U.Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium. Karlien.Cheyns@ees.kuleuven.be
authors.forename: Karlien
authors.initials: K
authors.lastname: Cheyns
authors.forename: Sofie
authors.initials: S
authors.lastname: Peeters
authors.forename: Dorien
authors.initials: D
authors.lastname: Delcourt
authors.forename: Erik
authors.initials: E
authors.lastname: Smolders
mesh_terms: D004784:Environmental Monitoring; D007854:Lead / Q000032:analysis / Q000633:toxicity*; D010758:Phosphorus / Q000172:deficiency* / Q000378:metabolism; D063245:Plant Development; D010944:Plants / Q000187:drug effects* / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus; D007854:Lead