BIOGEOCHEMICAL ANALYSIS OF ELEMENTAL UPTAKE IN BLACKBERRY PLANTS (RUBUS ARGUTUS) GROWING IN AN ACID MINE DRAINAGE CHANNEL

Acid mine drainage (AMD), measuring about pH 3.5 with elevated concentrations of Fe, Al and other trace elements, discharges from the abandoned Green Valley coal mine site in western Indiana, USA. In 1994, the site was reclaimed into a low relief mound and seeded with vegetation. Numerous drainage channels lined with carbonate rip-rap were constructed across the site, and AMD now flows in several of the channels. Recently, blackberry plants (Rubus argutus) started growing in the rip-rap adjacent to flowing AMD. This study examines elemental concentration in leaves, stems, and berries of plants collected from the mine site and from a city park, the latter for establishing background levels. Samples were analyzed using a hand held x-ray fluorescent spectrometer to determine if plants at the mine site sequestered higher concentrations of elements from the AMD compared to plants growing in a park environment. Analytical results showed detectable concentrations of K, Ca, S, Mn, Mo, Fe, Sr, Rb, Zn, Cu, and Sc in plant material for both areas. Concentrations of Ba, Cs, Te, Sb, Cd, Ag, Pb, Th, Se, Hg, Au, W, Ni, Co, Cr, V, and As, were below detection limits. A comparison of analytical results between AMD plants and those from the park showed the following: AMD berries are higher in all detectable elements compared to uncontaminated berries, except for Sr; leaves of AMD plants were higher in all detectable elements, except for K, Mo, and Sr, compared to uncontaminated leaves; and no definitive differences were observed for stem material collected from the two sites. Concentrations of Sr were consistently higher in the stems, leaves, and berries of the park plants compared to their counterparts in the AMD environment. The stems of park plants also stored higher concentrations of the analyzed elements compared to their leaves and berries. Overall, the data show that Rubus argutus growing next to contaminated water is more susceptible to element uptake compared to plants growing in an uncontaminated system. Storage of elevated concentrations of some elements by plants may have important ramifications for animals consuming parts of these plants because the elements are subject to food-chain amplification to possibly toxic levels.