The use of biomimetic tools for water quality monitoring: passive samplers versus sentinel organisms

To evaluate the performance of artificial and biological integrative sampling strategies, dissolved concentrations of polychlorinated biphenyl (PCBs) and metals (Cu and Mn) were measured with passive sampler devices (PSD) enclosing hydrophobic and chelating phases, and Asiatic clams were transplanted to a polluted area in the Rio de la Plata. Water concentrations based on PSD were compared with spot water samples collected at 0, 15, 32, and 63 days of exposition. PCBs and metals displayed linear accumulation kinetics both in PSDs and bivalves, but with different slopes. PCBs slopes were 2-27 times higher in bivalves (0.3-7.9 vs. 0.1-2.6 ng g^-1 d^-1 in PSDs) reflecting active filtration and uptake from particles, colloids, and dissolved phase, whereas metal slopes were 2.5-11 times lower in bivalves (0.04-0.18 vs. 0.10-2.00 μg g^-1 d^-1 in PSDs) suggesting metal bioregulation. Truly dissolved PCB concentrations from PSD (4.0-6.9 ng.l^-1) represented average 13±4 % of PCB concentrations from filtered spot water samples reflecting the operational discrimination of the PSD diffusion membrane on competing dissolved and colloidal organic phases. In contrast, PSD dissolved Cu concentrations (2.3-8.2 μg l^-1) were equivalent to the spot water values (3.2-3.8 μg l^-1) suggesting that Cu speciation was adequately integrated by passive sampling. On the other hand, PSD-dissolved Mn concentrations (49±38 μg l^-1) were higher (p<0.05) than those from spot water samples (7±11μg l^-1) possibly due to phase changes of Mn distribution related to variable redox conditions in the water. Results evidenced that the PSDs are efficient accumulators of metals and organic compounds from the truly dissolved fraction.