In the daphnia assay, lethal effects on D. magna were observed in the
leachates from undiluted soils S3, S2 and S5. Lethal effects observed in
leachates of soil 3 could be influenced by the low pH, 3.91. Daphnia is
very sensitive to pH and effects due to pH alone can occur for values outside
the rage 6.0–9.0 (OECD, 2004). However, pH adjustment was not
performed to avoid changes in As and metal bioavailability. Effects
from diluted samples of soils were not seen except in S2 at 12.5%
of soil concentration, where 100% mortality was observed. The toxicity
of this leachate corresponded to the high content of As (31.88 ±
0.07 mg L−1) measured in this sample. Again, the importance of