Does Elevated Nitrogen and Sulfur Deposition Lead to Net Base Cation Losses in Northern New England Forest Soils?

建议#：DEB-9615199调查员(S)：费尔南德斯，鲁斯塔德，卡尔，诺顿研究所：缅因州大学这项研究的目的是继续处理和监测缅因州北部贝尔布鲁克的一项配对流域试验，重点是土壤盐基阳离子，特别是钙的变化。在遭受酸性氮沉积的土壤中，碱阳离子耗竭被公认为一个潜在的问题，但从良好控制的长期实验中获得的数据很少。自1989年秋季以来，贝尔布鲁克分水岭一直定期使用硫酸铵进行处理，据信正在接近氮饱和。自1993年以来，碱性阳离子和强酸性阴离子之间的关系发生了变化，因此随着铝流失的增加，土壤中不稳定的钙和镁可能会被耗尽。持续的监测将允许测试一系列关于温带森林土壤中阳离子滞留和淋溶的控制和机制的假说。

ABSTRACT PROPOSAL # : DEB-9615199 INVESTIGATOR(S) : FERNANDEZ, RUSTAD, KAHL, NORTON INSTITUTION: UNIVERSITY OF MAINE The aims of this research are to continue treatment and monitoring of a paired watershed experiment at Bear Brook in northern Maine, with an emphasis on changes in soil base cations, particularly calcium. Base cation depletion is well-recognised as a potential problem in soils that have been subjected to acidic N deposition but few data exist from well-controlled, long-term experiments. The Bear Brook watershed has been periodically treated with ammonium sulfate since the fall of 1989 and is believed to be approaching N saturation. Since 1993 the relationship between base cations and strong acid anions has changed, such that labile Ca and Mg may be depleted in the soils as Al losses increase. Continued monitoring will allow tests of a series of hypotheses about controls and mechanisms of cation retention and leaching in temperate forest soils.