PARENT SESSION
4H Ecological risk assessment for the marine environment
9:00 AM to 7:00 PM, Wednesday, 09 May 2001

(W/EH085) Monitoring toxicity in four wastewater discharges in Bay of Cadiz.

Rodríguez, Rocío¹, Garrido, Carmen¹, Sales, Diego¹, Alonso, Quiroga¹, ¹

ABSTRACT- From November of 1999 is carrying out the study of the toxicity of four wastewater discharges (two from sewage treatment plants (STPs), and another two from industrial polygon) that they pour so much to the Bay of Cadiz like to the coast Atlantic, classified both according to the Order of 14 of February of 1997 that classify the waters coasts Andalusian, like Limited Zone and Normal Zone respectively. Sequential dilutions of the test effluents were utilized in algal assays to estimate effluent toxicity al 100 % effluent concentration. The toxicity estimated was espressed as M/L Cu equivalents. Water samples were collected at the end or the pipe for four wastewaters emptying into Bay of Cadiz. There were four visits to each site over the sampling season. Chemical analyses requested from the Laboratory included general water chemistry (i.e., pH, total suspended solids, dissolved organic carbon, etc.),nutrients, metals and organic toxicants. Algal assays were perfomed on wastewater filteres through a 0,22 m millipore with Chlorella fusca, a unicellular green alga, was used as the test organism. There was two dilution series one from the test effluent water and the other from the Cu reference solution and a Cu reference curve was constructed from the Cu dilution series, correlating Cu concentration with % algal growth. Among the four discharges tested, it expect the industrial wastewater was the most toxic at about 100 times the sensitive level (the concentration above which delicate algal and invertebrate species would not survive).

Key words: wastewater, algal bioassay, discharges, Chlorella fusca