Table 2.

Phenolic compounds exuded by the diatom P. tricornutum grown under different copper concentrations and exposure times.

Phenolic compound	Control	Cu(II) 0.31 µM	Cu(II) 0.79 µM	Cu(II) 1.57 µM
After Cu exposure periods of 12 days
GAL	4.57 ± 0.74	< LOQ	< LOQ	< LOQ
PCA	10.7 ± 2.8	< LOQ	2.33 ± 0.01	< LOQ
SYR	30.9 ± 1.9	1.92 ± 0.98	41.27 ± 0.79	107.32 ± 2.20
ECAT	20.9 ± 0.46	3.60 ± 0.40	19.77 ± 6.04	23.41 ± 7.85
RU	3.9 ± 0.7	22.30 ± 4.39	< LOQ	< LOQ
Sum	71.0 ± 6.6	27.81 ± 5.77	63.37 ± 6.84	130.72 ± 10.04
After Cu exposure periods of 18 days
PCA	< LOQ	< LOQ	< LOQ	15.07 ± 1.86
CAT	< LOQ	2.43 ± 0.41	< LOQ	< LOQ
VAN	1.31 ± 0.08	< LOQ	< LOQ	< LOQ
SYR	19.22 ± 0.39	15.81 ± 0.31	101.33 ± 3.43	335.08 ± 0.06
ECAT	10.12 ± 0.21	7.85 ± 0.99	106.77 ± 32.31	228.16 ± 11.74
RU	0.19 ± 0.01	1.53 ± 0.40	< LOQ	< LOQ
Sum	30.84 ± 0.69	27.62 ± 2.11	208.09 ± 35.75	578.31 ± 13.66

The results are expressed as attomol cell⁻¹ (means ± standard deviations of three measurements).