TY - JOUR
T1 - Uranium distribution and cycling in Scots pine (Pinus sylvestris L.) growing on a revegetated U-mining heap
AU - Thiry, Yves
AU - Van Hees, May
AU - Wannijn, Jean
AU - Van Bree, Peter
AU - Vandenhove, Hildegarde
AU - Rufyikiri, Gervais
AU - Schmidt, Peter
A2 - Vanmarcke, Hans
N1 - Score = 10
PY - 2005/4
Y1 - 2005/4
N2 - We determined the uranium distribution in soil and its allocation in compartments of 35-year-old Scots pine developed on a revegetated U-mining heap. The processes controlling the dynamics of U recycling were identified and further quantified in terms of annual fluxes. As pine developed, an acid humus layer emerged leading to weathering of the alkaline mining debris but this had little effect on U mobility in the soil profile. Increased U mobility mainly involved a translocation of U to metal-humus chelates in surface layers. The root compartment accounted for 99.3% of the U budget in tree, thus serving as an effective barrier which restricts U uptake. The current root uptake and transfer of U to upper parts of the tree amounted to about 3 g ha−1 y−1, i.e. less than 0.03% of the current NH4-exchangeable U pool in the soil (0–30 cm). Allocation and translocation pattern made it clear that a dominant fraction of the translocated U moves passively with the ascent xylem sap, most likely as a soluble complex, and steadily accumulates in the needles. Consequently, 97% of the U annual uptake is returned to the soil through litterfall. At the studied site, the risk of U dissemination due to biomass turnover or trunk harvest was low when considered in relation to the current “exemption level” for U.
AB - We determined the uranium distribution in soil and its allocation in compartments of 35-year-old Scots pine developed on a revegetated U-mining heap. The processes controlling the dynamics of U recycling were identified and further quantified in terms of annual fluxes. As pine developed, an acid humus layer emerged leading to weathering of the alkaline mining debris but this had little effect on U mobility in the soil profile. Increased U mobility mainly involved a translocation of U to metal-humus chelates in surface layers. The root compartment accounted for 99.3% of the U budget in tree, thus serving as an effective barrier which restricts U uptake. The current root uptake and transfer of U to upper parts of the tree amounted to about 3 g ha−1 y−1, i.e. less than 0.03% of the current NH4-exchangeable U pool in the soil (0–30 cm). Allocation and translocation pattern made it clear that a dominant fraction of the translocated U moves passively with the ascent xylem sap, most likely as a soluble complex, and steadily accumulates in the needles. Consequently, 97% of the U annual uptake is returned to the soil through litterfall. At the studied site, the risk of U dissemination due to biomass turnover or trunk harvest was low when considered in relation to the current “exemption level” for U.
KW - Biological cycling
KW - Phytostabilisation
KW - Mining sites
KW - Remediation
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/ezp_27151
U2 - 10.1016/j.jenvrad.2004.01.036
DO - 10.1016/j.jenvrad.2004.01.036
M3 - Article
SN - 0265-931X
VL - 81
SP - 201
EP - 219
JO - Journal of environmental radioactivity
JF - Journal of environmental radioactivity
IS - 2-3
ER -