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Research article - Peer-reviewed, 2019

Can silver and other heavy metal concentrations in leaves be used in order to identify tree root intrusion into sewage systems and storm-water drains?

Fransson, Ann-Mari


There is a growing awareness of the value of trees for climate adaptation, human health, and biodiversity in urban spaces, and methods for identifying and calculating the benefits of trees have been developed. However, tree roots frequently intrude into sewer pipes and storm-water drains, causing costly damage. Identifying the individual trees that cause damage would be helpful but has proved difficult. There is a need for non-destructive identification of root intruding trees, in order to evaluate the cost and benefits of individual trees. The concentrations of eight heavy metals (silver, gold, cadmium, lead, palladium, rubidium, antimony, and zinc) and of potassium were evaluated in 19 pairs of trees/shrubs in Malmö, southern Sweden. It was found that the concentrations of silver were approximately 28% higher in leaves from trees whose roots had entered sewers than in control trees. Trees whose roots intruded storm-water drains had slightly higher leaf potassium levels, while the concentrations of other elements did not differ from those in control trees. Thus, it may be possible to use the silver concentration in tree leaves to identify individuals with roots intruding into sewer systems. However, considerable differences were found between species, so further tests are required before the method can be adopted in practice.


leaf concentration; metal uptake; broadleaved trees; urban trees; root growth

Published in

Arboricultural Journal
2019, Volume: 41, number: 4, pages: 212-225

    UKÄ Subject classification

    Environmental Sciences

    Publication identifier


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