Pilot study of temporal variations in lead bioaccessibility and chemical fractionation in some Chinese soils.
The effect of ageing, following the addition of approximately 400mgkg(-1) lead (Pb) as Pb(NO(3))(2), on Pb bioaccessibility was examined in five typical Chinese soils using a physiologically based extraction test. Sequential extraction was employed to identify the source fraction(s) of bioaccessible Pb in the soils. Pb bioaccessibility decreased exponentially to nearly steady levels in mildly acidic or alkali (pH 6.09-7.43) soils, for both gastric (69.91-71.75%) and small intestinal (7.53-9.63%) phases within the first 2-4 weeks and 1-2 months of incubation, respectively; however, it took only 1-2 weeks for strongly acidic ( approximately pH 4.5) soils to reach nearly steady levels of Pb bioaccessibility (73.01-74.46% and 10.30-10.98% in the gastric and small intestinal phases, respectively). In addition to the water-soluble and exchangeable fractions, the carbonate fraction of mildly acidic or alkali soils appeared to be a third main source of bioaccessible Pb in the small intestinal phase; however, bioaccessible Pb was likely to derive principally from Pb in the water-soluble and exchangeable fractions of strongly acidic soils. Bioaccessible Pb in the gastric phase appeared to derive from all the fractions in all five studied soils, even the residual fraction.
Tang
Xiang-Yu
XY
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, PR China. xiangyu.tang@yahoo.com
Cui
Yan-Shan
YS
Duan
Jing
J
Tang
Lily
L
D000538:Aluminum Silicates / Q000032:analysis; D001673:Biodegradation, Environmental; D001826:Body Fluids / Q000737:chemistry; D002681:China; D000077215:Clay; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000378:metabolism; D007854:Lead / Q000737:chemistry* / Q000302:isolation & purification; D010316:Particle Size; D010865:Pilot Projects; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000737:chemistry*; D013997:Time Factors
D000538:Aluminum Silicates; D012987:Soil; D012989:Soil Pollutants; D007854:Lead; D000077215:Clay