Bioaccumulation and retention of lead in the mussel Mytilus galloprovincialis following uptake from seawater

Bioaccumulation of lead in the mussel Mytilus galloprovincialis from Pb-210 -labeled bulk seawater (dissolved and particulate pathways combined) was ex amined over 21 days. The lead bioaccumulation factor (BAF) at equilibrium w as estimated to be 211 +/- 10 ml g(-1). This value was two orders of magnit ude lower than BAFs reported in the literature for other trace metals in th is bivalve indicating that lead is not efficiently accumulated by mussels f rom bulk seawater. The resultant lead distribution in mussels was 49 +/- 10 % in soft tissues and 46 +/- 16% in the shell suggesting similar uptake rat es (Bq day(-1)) in both compartments throughout the exposure. Total elimina tion for lead in mussels was adequately described by a short-term compartme nt with a biological half-life for loss of 1.4 +/- 0.3 days and a long-term compartment which released lead only very slowly (Tb-1/2 = 2.5 +/- 0.7 mon ths). No difference was noted for lead elimination rates in shell and in so ft parts. When experimentally exposed to lead under conditions representati ve of natural environmental lead levels in water, including both that in th e dissolved phase and in the food, the shell compartment was shown to conta in the major fraction of the total lead accumulated by mussels. Therefore m ussels may be considered as good bioindicators of lead contamination accumu lated from the dissolved rather than from the particulate source. Furthermo re, the relatively slow uptake and the long depuration half-life of lead wi ll limit the ability of mussels to accurately record short-term variations in lead concentrations in the surrounding waters, a fact which should be ta ken into consideration in order to define the appropriate sampling frequenc y for mussels used in biomonitoring programs involving lead. (C) 1998 Elsev ier Science B.V. All rights reserved.