Mercury distribution in medium-size rivers and reservoirs of the Sao Paulo state (southeast Brazil).
The aim of this work was to investigate mercury (Hg) levels in six meso-scale watersheds (Upper Paranapanema, Aguapeí, Peixe, São José dos Dourados, Mogi-Guaçu, and Piracicaba) of the São Paulo state to contribute to a more comprehensive understanding of Hg contamination in Brazil. Water, sediment, bivalves, and fish samples were collected during 2001 at 11 sites. Fish were also collected in the Jurumirim and Salto Grande Reservoirs which are 39 and 52 yr old since impoundment, respectively. Results showed that Hg concentrations were low in almost all samples, except fish from Jurumirim Reservoir (total mercury [T-Hg] = 1.14 +/- 0.55 mg kg(-1) wet wt.). In spite of industrialization and high population, the results showed that there was no important source of Hg contamination in the investigated areas. The higher concentrations found in fish from Jurumirim seem to be the result of processes that favor Hg mobilization and methylation as a consequence of the impoundment of the reservoir area. The same levels were not observed in the Salto Grande Reservoir, probably because these are no longer significant due to the long time since the impoundment. To understand the dynamics of methylmercury (MeHg) production and its accumulation in fish, further studies are needed in the Jurumirim Reservoir. The results show that even at low T-Hg concentrations in sediment and water, concentrations in fish can reach values that pose concerns for consumption. This emphasizes the importance of designing an optimized biomonitoring program that can provide warning of biogeochemical conditions that promote formation of MeHg.
Tomazelli
Andréa Cristina
AC
Ciências e Letras de Ribeirão Preto, Dep. de Biologia, Av. dos Bandeirantes, 3900-CEP, 14040-901 Ribeirão Preto, SP, Brazil. andrea_tomazelli@yahoo.com.br
Martinelli
Luiz Antonio
LA
Krug
Francisco José
FJ
Santos
Dario
D
Ruffini
Iolanda
I
de Camargo
Plínio Barbosa
PB
Horvat
Milena
M
D000818:Animals; D049872:Bivalvia / Q000378:metabolism*; D001938:Brazil; D004784:Environmental Monitoring; D005399:Fishes / Q000378:metabolism*; D005506:Food Contamination; D019015:Geologic Sediments / Q000032:analysis; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D008767:Methylmercury Compounds / Q000032:analysis* / Q000378:metabolism; D045483:Rivers / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D014881:Water Supply / Q000032:analysis
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury