Impact of harbour, industry and sewage on the phosphorus geochemistry of a subtropical estuary in Brazil.
The distribution of different forms of phosphorus in surface sediment from 17 sites were investigated by SEDEX method. The sites were divided into three sectors: Santos Channel (SC - influenced by harbour, fertilizers plants and phosphogypsum mountains), São Vicente Channel (SVC- domestic waste) and Santos Bay (SB - sewage outfall). The average percentage of each P fraction of the surface sediments in this region followed the sequence P-Fe (38%)>P org (27%)>P exch (13%)>Detrital - P (12%)>Auth - P (10%). P total varied from 3.57 to 74.11 μmol g(-)(1) in both seasons. In SVC, P exch ranged from 13% to 27% and P org varied from 12% to 56%. These high percentages of P exch/P total (greater than 20%) may be related to low oxygen resulting from oxygen consumed by intensive organic matter decomposition as well as the salty water that leads to cation and anion flocculation. Also, the possibility of an influence related to the industrial source of P exch is not ruled out. No significant seasonal differences were found among sites, except for sewage outfall, with changing in the grain size and hence, the P geochemistry. During the summer in the sewage outfall station, Porg represented 37% of P total, which decreased to 13% in the winter. These results suggest that high percentages of organic phosphorus cannot be attributed only to autochthonous and allochthonous organic matter, but also to detergents and/or domestic waste. In contrast, spatial differences among sectors were observed, with the highest values of each fraction associated with sites near industrial and domestic waste activities.
Laboratory of Nutrients, Micronutrients and Trace Elements in the Oceans (LABNUT-IOUSP), Institute of Oceanography, University of São Paulo, Praça do Oceanográfico, 191, São Paulo, SP CEP 05508-120, Brazil. Electronic address: glauciaberbel@uol.com.br.
Glaucia B B
GB
Berbel
Laboratory of Instrumental Neutron Activation Analysis (INAA), Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP) Av. Professor Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil.
Deborah I T
DI
Favaro
Laboratory of Nutrients, Micronutrients and Trace Elements in the Oceans (LABNUT-IOUSP), Institute of Oceanography, University of São Paulo, Praça do Oceanográfico, 191, São Paulo, SP CEP 05508-120, Brazil. Electronic address: edsbraga@usp.br.
Elisabete S
ES
Braga
D001938:Brazil; D002133:Calcium Sulfate; D004784:Environmental Monitoring; D063366:Estuaries; D019015:Geologic Sediments / Q000737:chemistry; D010100:Oxygen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis*; D012621:Seasons; D012722:Sewage / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D012722:Sewage; D014874:Water Pollutants, Chemical; C077769:phosphogypsum; D010758:Phosphorus; D010100:Oxygen; D002133:Calcium Sulfate
Estuaries; Eutrophication; Geochemistry; Phosphogypsum; Phosphorus; Sediments