caa a22 4500 477110266 CHVBK 20180405111606.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00012058 doi (NATIONALLICENCE)springer-10.1007/BF00012058 Determination of bioavailable cadmium in paddy fields by chelating resin membrane embedded in soils [Elektronische Daten] [Dar-Yuan Lee, Po-Hsing Chiang, Kun-Huang Houng] Diffusion is an important mechanism in determining the bioavailability of heavy metals in cropland soils because it controls the rate of movement of heavy metal ions in soil solution to the root surface. Methods currently used for estimating the bioavailability do not take this process into account. In this study a chelating resin membrane was embedded in saturated soils for determining bioavailability of cadmium in situ. Nine Taiwanese soils, including five major agricultural soils which were treated with various levels of Cd and four heavy metal contaminated soils, were used in this study. One piece of Ca-Chelex resin membrane (4 cm × 4 cm) was embedded horizontally in saturated soil pastes and recovered after a fixed time interval. From the amounts of Cd accumulated on the resin membrane, the Cd bioavailability index (C2D) was calculated, where C is the labile Cd concentration and D is the effective diffusion coefficient. This index provides an integrated measure of Cd ion diffusion, sorption-desorption rates, and solution concentration. The results showed that the index was approximately constant and did not vary with the length of time embedded in soil (from 24 to 96 hrs). The index decreased as soil pH increased. When soils were flooded for 7, 15, and 30 days respectively before the resin membrane was embedded in soil for 1 day, the resulting index decreased as the length of flooding time increased. This suggests that the bioavailability index reflects the dynamic change of Cd bioavailability in saturated soils. The indices were then correlated with total uptake of Cd by rice seedlings. The Cd bioavailability index correlated significantly with plant uptake of Cd (p < 0.1%) for all the flooding time period treatments. The above results indicated that the embedded chelating resin membrane method is suitable for determining bioavailable Cd of saturated soils across a wide range of soil properties and Cd concentrations. In addition, the method is nondestructive, and therefore, feasible for in situ determination of the bioavailable Cd of paddy soils. Kluwer Academic Publishers, 1996 contaminated soils nationallicence heavy metal nationallicence ion exchange resin nationallicence plant uptake nationallicence rice paddy nationallicence Lee Dar-Yuan Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C. aut Chiang Po-Hsing Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C. aut Houng Kun-Huang Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C. aut Plant and Soil Kluwer Academic Publishers; http://www.wkap.nl 181/2(1996-04-01), 233-239 0032-079X 181:2<233 1996 181 11104 https://doi.org/10.1007/BF00012058 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00012058 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lee Dar-Yuan Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Chiang Po-Hsing Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Houng Kun-Huang Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; http://www.wkap.nl 181/2(1996-04-01), 233-239 0032-079X 181:2<233 1996 181 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer