Journal
ENVIRONMENTAL POLLUTION
Volume 223, Issue -, Pages 497-506Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2017.01.051
Keywords
Heavy metals; Photosynthesis; Populus deltoides; Populus tremuloides
Categories
Funding
- startup funds of Rutgers University Newark
- Department of Energy [DE-SC0007041]
- U.S. Department of Energy (DOE) [DE-SC0007041] Funding Source: U.S. Department of Energy (DOE)
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Phytoremediation, a technique used to reclaim heavy metal-contaminated soils, requires an under-standing of plant physiological responses to heavy metals. However, the majority of studies documenting heavy metal impact on plant functioning have been performed in laboratory or greenhouse settings. We predicted that increased soil heavy metal concentrations reduce photosynthesis and biomass production in trees growing in metal contaminated soil in a naturally re-vegetated urban brownfield. Leaf gas exchange, leaf carbon and nitrogen concentration, and tree biomass were recorded and compared for Populus deltoides and Populus tremuloides growing in an urban brownfield. The CO2 compensation point (CCP) differed significantly between soil metal concentrations and species, with P. deltoides displaying a greater CCP and P. tremuloides displaying a lower CCP as soil metal concentration increased, despite no changes in dark respiration for either species. In terms of biomass, only total branch weight (TBW) and leaf area (LA) differed significantly between soil metal concentrations, though the difference was largely attributable to variation in diameter at breast height (DBH). Furthermore, TBW and LA values for P. deltoides did not decrease with increasing soil metal concentration. Soil metal concentration, thus, had minimal effect on the relationship between tree age and DBH, and no effect on relationships of tree age and height or LA, respectively. Significant differences between soil metal concentrations and species were found for delta N-15 (isotopic nitrogen ratio) while leaf nitrogen content (% N) also differed significantly between species. Long-term water use efficiency derived from carbon isotope analysis (iWUE(isotope)) differed significantly between trees grown on different soil metal concentrations and a significant species-metal concentration interaction was detected indicating that the two study species responded differentially to the soil metal concentrations. Specifically, P. tremuloides enhanced while P. deltoides reduced long-term iWUE(isotope) as soil metal concentration increased, further emphasizing the importance of species and possible genotype selection for phytoremediation. (C) 2017 Elsevier Ltd. All rights reserved.
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