Trace metal uptake by the grass Melinis repens from roadside soils and sediments, tropical Australia

Pratt, C., and Lottermoser, B.G. (2007) Trace metal uptake by the grass Melinis repens from roadside soils and sediments, tropical Australia. Environmental Geology, 52 (8). pp. 1651-1662.

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This study reports on trace metal uptake by the grass species Melinis repens, growing in roadside soils and sediments in tropical northeastern Australia. Median total Cu, Pb, Ni and Zn concentrations were significantly (P < 0.05) higher in road edge soils (Cu = 61.1 mg/kg, Pb = 97.3 mg/kg, Ni = 28.6 mg/kg, Zn = 729 mg/kg) than in background soils collected away from roads (Cu = 5.8 mg/kg, Pb = 11.2 mg/kg, Ni = 3.7 mg/kg, Zn = 21 mg/kg). Significantly (P < 0.05) elevated Zn values were recorded in the stems of the M. repens specimens growing on roadside soils (231.6 mg/kg dry weight of tissue) compared with those of grasses growing on background soils (40.8 mg/kg dry weight of tissue). Moreover, median Cu, Ni and Zn values in the roots of roadside grasses (Cu = 29.1 mg/kg, Ni = 2.73 mg/kg, Zn = 169 mg/kg) were significantly (P < 0.05) higher than their respective levels in the roots of background M. repens samples (Cu = 5.98 mg/kg, Ni = 0.70 mg/kg, Zn = 22 mg/kg). A greenhouse experiment showed that Cu and Zn in road sediments are labile and are available for uptake by M. repens. The studied roadside soils and sediments were leached with a diethylenetriaminepentaacetic acid–CaCl2–triethanolamine–HCl extraction solution, which proved to be a rudimentary indicator of Zn availability and uptake to the root tissue of M. repens. The results demonstrate that trace metals in roadside grasses have the potential to be directed up the foodchain as grasses are consumed by herbivores. In addition, bioavailable metal contaminants hosted by road sediments have the capacity to impact on ecosystems downstream of roads because these sediments are mobilised by road runoff waters from road surfaces into adjoining catchments.

Item ID: 2877
Item Type: Article (Research - C1)
ISSN: 1432-0495
Keywords: traffic; metals/alloys; bioavailability; Melinis repens; Australia; metals
Date Deposited: 08 May 2009 03:36
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040306 Mineralogy and Crystallography @ 50%
04 EARTH SCIENCES > 0402 Geochemistry > 040299 Geochemistry not elsewhere classified @ 50%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960999 Land and Water Management of Environments not elsewhere classified @ 100%
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