Toxicity of ferric chloride sludge to aquatic organisms.

Iron-rich sludge from a drinking water treatment plant (DWTP) was investigated regarding its toxicity to aquatic organisms and physical and chemical composition. In addition, the water quality of the receiving stream near the DWTP was evaluated. Experiments were carried out in August 1998, February 1999 and May 1999.

Evaluation of cyanobacteria toxicity in tropical reservoirs using crude extracts bioassay with cladocerans.

During a cyanobacterial bloom in a eutrophic environment, particularly at the end when decomposition occurs, toxic compounds such as the cyanotoxins and the lipopolysaccharides can be released in high concentrations into the water column damaging aquatic organisms. In this work, the effects of this release of toxic compounds during a cyanobacterial bloom were investigated. The acute and chronic toxicity of cyanobacterial crude extracts from two natural blooms in the Barra Bonita and Ibitinga reservoirs (Middle Tietê River, São Paulo State, Brazil) and of a toxic strain cultured in the laboratory were tested.

Water quality assessment by ecotoxicological and limnological methods in water supplies, southeast Brazil.

The quality of the water supplied to Araraquara city (São Paulo State, Brazil) was analyzed at four points: two reservoirs from which water is pumped and the water incoming and exiting a drinking-water treatment plant. Physical and chemical analyses of water were performed, as well as acute and chronic toxicity tests of the water from all four points, using Ceriodaphnia silvestrii (Cladocera, Crustacea) as test-organism. The study was carried out monthly in the period between December 2000 and November 2001.

Evaluation of water treatment sludges toxicity using the Daphnia bioassay.

Alum and ferric chloride sludges from two water treatment plants (WTPs) were analyzed regarding their physicochemical characteristics and toxicity to Daphnia similis. Experiments were carried out in the dry and rainy seasons. Acute and chronic toxicity was measured using survival and reproduction as measurement endpoints.

Toxicity of a cyanobacteria bloom in Barra Bonita Reservoir (Middle Tietê River, São Paulo, Brazil).

In eutrophic waters during cyanobacterial bloom lysis, a blend of cyanobacterial toxins and other compounds are released into the water, affecting aquatic communities. This research investigated the effect of a simulated cyanobacterial lysis event. For this purpose, intact cells from a natural cyanobacterial bloom from Barra Bonita Reservoir (Tietê River basin, Brazil) were taken, and the cells were broken by repeated freeze/thaw cycles.