Baixada Santista's region is world famous for its high levels of pollution, which are related to industrial, port and urban activities. Around the industrial pole of Cobatao city, high nutrient concentrations are found such as nitrate > 90 mol l(-1) N NO3- and phosphate > 24 mol l(-1) PPO4-3 A clear gradient of dilution from the estuary's interior to its mouth is present along the natural channels, but does not reach low concentrations for all elements in the Santos Bay. Artificial urban drainage channels present accentuated differences of the nutrient concentrations inside and outside each lock. The inner channel waters, show low average values of salinity (1.33 PSU) and oxygen (similar to 2.0 ml l(-1)); pH under 8; high averages of nutrient concentrations (ammonium similar to 40 mol l(-1), nitrate similar to 42, phosphate similar to 2.96 mol l(-1), silicate similar to 119 mol l(-1)); high total and faecal coliform averages (3566 x 10(3)/100 and 1637 x 10(3)/100 ml, respectively), Outside of the channels, on the beaches, there were high nutrient concentrations at some points and accentuated total and faecal coliform averages (91 x 10(3)/100 and 28 x 10(3)/100 ml, respectively), The high TC and FC contents outside of the locks show the inefficiency of the actions to prevent pollution on the beaches, These facts represent risks to local biota and human health. (C) 2000 Elsevier Science Ltd. All rights reserved.
