Metal distribution across different pools in the organic layer of a forest under acid deposition and its consequences for the metal dynamics

Abstract

Metal distribution across disfferent pools in the organic layer of a forest under acid deposition and its consequences for the metal dynamics Wessel, W.W.; Tietema, A. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Acid atmospheric deposition can cause losses of metal nutrients from the organic layer of a soil. The size of these losses depend on the sizes of the different pools in which the metals are present, as these pools differ in mobility. The metal pools in an organic soil layer of a Douglas fir forest in the Netherlands subjected to acid deposition were determined by means of extractions and percolations. Na was mainly dissolved and exchangeably adsorbed, K dissolved, exchangeably adsorbed and present in the soil microbial biomass, Ca exchangeably adsorbed and present in organic precipitates, Mg exchangeably adsorbed and present in the soil biomass, and Mn exchangeably adsorbed and present in inorganic precipitates. The main part of the metals was exchangeably adsorbed. The adsorption affinity increased in the order Na < K < Mg < Mn ~ Ca. The vertical distribution of the metals in the organic layer showed that all metals were continuously lost from the organic layer. The differences between the metals in retention and vertical distribution patterns were in agreement with their differences in deposition rate, pool distribution, and exchange affinity. Since the metals were mainly exchangeably adsorbed, and the acidifying cations dominated the atmospheric deposition, acid deposition and cation exchange must be processes that strongly affect the losses of metals from this organic soil layer.

Near Infrared Spectroscopy for Determination of Total and Exchangeable Cations in Geologically Heterogeneous Forest Soils

“…2,3 CEC, defined as a maximum number of adsorbed ions held per kg of dry soil, is an important parameter for estimating cation retention and losses from soils. 3 Of particular importance for soil processes are exchangeable base cations (Na, K, Ca, Mg), which are related to soil buffering capacity, 4,5 plant nutrition [6][7][8] and soil solution quality control. 9 Base saturation (the percentage of equivalent sum of base cations in CEC ) of soils determines the influence of exchange complex on soil solution chemistry and is an important parameter for estimating cation retention and losses from forest soils.…”

Microbial activity and leaching during initial oak leaf litter decomposition

“…2). This indicated that the water-soluble fraction of these elements in the litter forms a substantial part of the total amount in the litter (Wessel and Tietema 1994). Profound initial leaching of K has been found in many litterbag studies (Gosz et al 1973);Yavitt and Fahey 1986).…”

Nitrogen turnover in fresh Douglas fir litter directly after additions of moisture and inorganic nitrogen

“…Amounts of NH 4 + and/or NO 3 -added (Table 2) were calculated from the amounts of nitrogen added to the forest floor during a rain event (2.7 kg-N ha -1 ; Hansen et al 1994;Raat et al 2002), the molar ratio of NH 4 + :NO 3 -in throughfall (2.7:1; Draaijers et al 1998) and the total dry mass of the forest floor (3.2 kg m -2 ; Wessel and Tietema 1995). In this calculation we assumed that throughfall was distributed evenly over the top half of the forest floor.…”

“…Secondly, even in the WD incubations, about half of the NO 3 -net produced was transformed into N 2 O, denoting the relative importance of denitrification in exporting NO 3 -from the LF1 horizon. The contribution of both sinks to the total N balance of the Speuld forest, however, remains relatively small as dry mass of the LF horizon is only 12% of the total dry mass of the forest floor (Wessel and Tietema 1995). Rough estimates demonstrate that the maximum loss of NO 3 -via incorporation into DON or loss as N 2 O is about 1 kg-N ha -1 yr -1 for each NO 3 -sink, respectively, which is small compared to the 31 kg-N ha -1 yr -1 of NO 3 -that are leached from the soil at 90 cm depth.…”