Water Quality of Urban Streams: The Allium cepa Seeds/Seedlings Test as a Tool for Surface Water Monitoring

Table 2

Mean and standard deviation of chromosomal aberrations (CA), micronuclei (MN), and mitotic index (MI) observed in meristematic cells of A. cepa exposed to water samples of Lajeado, Preto, and Pedras Streams.

Samples		MI	MN	CA
Controls	NC	16.36 ± 3.95%	0.4 ± 1.26	13.0 ± 6.75
	PC	11.44 ± 2.76%	2.8 ± 3.01	45.0 ± 15.81
Lajeado; stream	S1u	14.54 ± 3.56%	0.2 ± 0.63	32.0 ±
	S1d	14.48 ± 1.80%	1.0 ± 1.41	58.0 ±
Preto; stream	S2u	14.42 ± 1.27%	0.2 ± 0.63	26.0 ± 17.76
	S2d	14.74 ± 3.39%	0.6 ± 0.97	37.0 ± 18.89
Pedras; stream	S3u	17.36 ± 2.64%	0.2 ± 0.63	33.0 ± 21.11
	S3d	13.32 ± 3.10%^a	2.0 ± 2.67^b	48.0 ± 33.27

MI: mitotic index expressed in % of dividing cells; MN: micronucleus in 1000 cells; and CA: chromosomal aberration in 1000 dividing cells. PC: 3 mg L⁻¹ CuSO₄.  Statistically significant results () compared to NC; ^astatistically significant difference between S3u and S3d comparing MI values (); ^bstatistically significant difference between S3u and S3d comparing MN values (); and ^csignificant difference between S1u and S1d comparing CA values ().