Root uptake of lead by Norway spruce grown on Pb spiked soils

The root uptake of lead (Pb) by trees and the transfer of Pb by leaf litter deposition to the forest floor were investigated through a pot experiment with Norway spruce. Natural Pb and radio isotopic lead (²¹⁰Pb) were determined in needles and twigs and in the pot soil spiked with ²¹⁰Pb. Calculations of the specific activity in plant material and in the supporting pot soil showed that less than 2% of the Pb content of needles and twigs originates from root uptake and approximately 98% are deposited from the atmosphere. Atmospheric Pb has declined by a factor of 7 from 1980 to 2007 but is still a major pathway of Pb to vegetation and topsoils. The conclusion from the experiment is that the internal circulation of Pb through root uptake, translocation and litterfall, gives an insignificant input of Pb to the forest floor compared to atmospheric deposition.     

Atmospheric heavy metal deposition accumulated in rural forest soils of southern Scandinavia

Thirty-three years of measurements of atmospheric heavy metal (HM) deposition (bulk precipitation) in Denmark combined with European emission inventories form the basis for calculating a 50-year accumulated atmospheric input to a remote forest plantation on the island of Laesoe. Soil samples taken in two depths, 0-10cm and 10-20cm, at eight forest sites at the island were used to determine the increase in HM content in the eolian deposited top soils of the plantation. Concentrations of lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), vanadium (V), nickel (Ni) and arsenic (As) were determined in atmospheric deposition and in soils. The accumulated atmospheric deposition is of the same magnitude as the increase of these metals in the top soil.     

Ozone uptake by an evergreen forest canopy: temporal variation and possible mechanisms

Patterns of ozone concentration ([O(3)]), O(3) deposition velocity (v(d)) and O(3) flux (F(c)) over an evergreen forest canopy are shown in relation to measuring method, physiological activity of the trees, and time of year. The gradient and eddy correlation methods were compared and showed similar diel v(d) patterns. Daytime F(c) was correlated with CO(2) and water vapour fluxes, while no correlation between [O(3)] in the range 10-70 ppb (nl l(-1)) and F(c) was seen in this study. F(c) was primarily driven by stomatal conductance, reactions with surfaces, particles and gases, and not by [O(3)]. On a monthly basis, [O(3)] was always highest in the afternoon while v(d) was typically higher in the morning, resulting in an equal F(c) over the day. Night-time F(c) was more than half of the daytime O(3) flux. The data reveal the importance of emissions of nitric oxide and terpenes as O(3) removal factors in evergreen forest dominated by Norway spruce.     

Comparisons of Measured and Modelled Ozone Deposition to Forests in Northern Europe

The performance of a new dry deposition module, developedfor the European-scale mapping and modelling of ozone flux to vegetation, was tested against micrometeorological ozone and water vapour flux measurements. The measurement data are for twoconiferous (Scots pine in Finland, Norway spruce in Denmark) and one deciduous forest (mountain birch in Finland). On average, themodel performs well for the Scots pine forest, if local inputdata are used. The daytime deposition rates are somewhat over-predicted at the Danish site, especially in the afternoon. The mountain birch data indicate that the generic parameterisationof stomatal responses is not very representative of this northernspecies. The module was also tested by using modelled meteorological data that constitute the input for a photochemical transport model.