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Extractability of Elements in Sugar Maple Xylem along a Gradient of Soil Acidity
Author(s) -
Bilodeau Gauthier Simon,
Houle Daniel,
Gag Christian,
Côté Benoît,
Messier Christian
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0203
Subject(s) - chemistry , sugar , water soluble , soil ph , soil water , environmental chemistry , maple , xylem , aqua regia , metal , botany , environmental science , soil science , organic chemistry , biology
Dendrochemistry has been used for the historical dating of pollution. Its reliability is questionable due primarily to the radial mobility of elements in sapwood. In the present study, the extractability of seven elements was characterized to assess their suitability for the monitoring of environmental conditions. Nine mature sugar maple trees ( Acer saccharum Marsh.), a wide‐ranging species in eastern North America that has suffered decline in past decades, were sampled in three Quebec watersheds along a soil acidity gradient. Five‐year groups of annual tree rings were treated by sequential chemical extractions using extractants of varying strength (deionized H 2 O, 0.05 M HCl, and concentrated HNO 3 ) to selectively solubilize the elements into three fractions (water‐soluble, acid‐soluble, and residual). Monovalent K; divalent Ba, Ca, Cd, Mg, Mn; and trivalent Al cations were found mostly in the water‐soluble, acid‐soluble, and residual fractions, respectively. Forms more likely to be mobile within the tree (water‐soluble and acid‐soluble) do not seem to be suitable for temporal monitoring because of potential lateral redistribution in sapwood rings. However, certain elements (Cd, Mn) were responsive to current soil acidity and could be used in spatial variation monitoring. Extractability of Al varied according to soil acidity; at less acidic sites, up to 90% of Al was contained in the residual form, whereas on very acidic soils, as much as 45% was found in the water‐soluble and acid‐soluble fractions. Sequential extractions can be useful for determining specific forms of metals as key indicators of soil acidification.