Wat. Res. Vol. 35, No. 17, pp. 4175–4183, 2001 # 2001 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0043-1354/01/$-see front matter PII: S0043-1354(01)00136-1 BIOACCUMULATION OF PALLADIUM, PLATINUM AND RHODIUM FROM URBAN PARTICULATES AND SEDIMENTS BY THE FRESHWATER ISOPOD ASELLUS AQUATICUS MARIELLA MOLDOVAN 1 *, SE ´ BASTIEN RAUCH 2 , MILAGROS GO ´ MEZ 1 , M. ANTONIA PALACIOS 1 and GREGORY M. MORRISON 2 1 Departamento de Quimı´ca Analı´tica, Facultad de Ciencias Quimı´cas, Universidad Complutense de Madrid, 28040-Madrid, Spain and 2 Water Environment Transport, Chalmers University of Technology, SE-412 96 Go¨teborg, Sweden (First received 6 June 2000; accepted in revised form 20 February 2001) Abstract}The three-way catalytic converters introduced to oxidize and reduce gaseous automobile emissions represent a source of platinum group elements (PGEs), in particular platinum, palladium and rhodium, to the urban environment. Abrasion of automobile exhausts leads to an increase of the concentration of PGEs in environmental matrices such as vegetation, soil and water bodies. The bioaccumulation of Pd, Pt and Rh by the freshwater isopod Asellus aquaticus was studied in natural ecosystems and under laboratory conditions. Owing to the low concentration level (ngg À1 )ofPGEsinthe animals studied, analyses were performed with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS) and hafnium, copper, yttrium, rubidium, strontium and lead were monitored for spectral interference correction. Asellus aquaticus collected in an urban river showed a content (mean Æ s) of 155.4 Æ 73.4, 38.0 Æ 34.6, and 17.9 Æ 12.2ngg À1 (dry weight) for Pd, Pt and Rh, respectively. The exposure of Asellus aquaticus to PGE standard solutions for a period of 24h give bioaccumulation factors of Bf: 150, 85, and 7 for Pd, Pt and Rh, respectively. Exposure of Asellus aquaticus to environmental samples for different exposure periods demonstrated that PGE bioaccumulation is time dependent, and shows a higher accumulation for the materials with a higher PGE content. While all three elements have the same uptake rate for exposure to catalyst materials, for exposure to environmental materials they have a different uptake rate which can be attributed to transformations of the PGE species in the environment. # 2001 Elsevier Science Ltd. All rights reserved Key words}palladium, platinum, rhodium, Asellus aquaticus, bioaccumulation, ICP-MS INTRODUCTION Interest in the determination of palladium, platinum and rhodium (platinum group elements, PGEs) in environmental materials has increased since the introduction of automobile catalytic converters, which are designed for the removal of carbon monoxide, unburned hydrocarbons and nitrogen oxides from vehicle exhausts. One potential unde- sired side effect of the use of catalytic converters is the emission of PGEs through the exhaust fumes. This is mainly as fine particulate material that originates from the abrasion and deterioration of the surface of the catalyst. Pd, Pt and Rh in the catalyst dust are deposited along roadways, on adjacent vegetation and soil, and in water bodies either directly or through runoff (Wei and Morrison, 1994). Anthropogenic emissions of Pd, Pt and Rh, as well as other heavy metals, can accumulate in freshwater and estuarine sediments and their effect on aquatic life will depend on their biological availability. Aquatic macroinvertebrates form an integral part of the diet of freshwater fish and can be considered an important step in the food chain. Asellus aquaticus is a freshwater detritivore abundant in most Euro- pean freshwater systems (Hellawell, 1986). High densities of Asellus aquaticus can be found in waters with organic pollution, especially in the vicinity of sewage outfalls. They are also common in relatively clean waters in areas with high levels of naturally occurring organic matter (Murphy and Leaner, 1982). Asellids are relatively tolerant to episodes of oxygen deficiency and low pH, having an intermedi- ate sensitivity towards various substances, including metals (Økland, 1980). Asellus aquaticus is in contact with both sediments and the water phase. Platinum concentration in river water and pore water is at *Author to whom all correspondence should be addressed. Tel.: +34-913944368; fax: +34-913944329; e-mail: moldovan@eucmax.sim.ucm.es 4175