Impact of anthropogenic activity on the Hg concentrations in the Piracicaba river basin (São Paulo State, Brazil)

Abstract

A sampling and analysis program has been completed between 1995 and 1998 in order to determine mercury concentrations in water, sediments, soils and fish in the Piracicaba river basin, one of the most populated and industrialized regions in Brazil. In sediment, the average Hg concentrations varied between 33 ± 17 ng g −1 and 106 ± 78 ng g −1 , in samples collected during the rainy and dry season, respectively. The same averages were also found for soil samples (35 ± 14 and 109 ± 61 ng g −1 ). In water, the total Hg concentration varied between <1.1 and 24.0 ng L −1 . In piscivore fish, up to 943 µg Hg kg −1 was found. Our results show that all compartments undergo Hg contamination, in view of the levels found in pristine environments. Water contamination seems to be due mainly to diffuse processes of soil erosion and suspension of river bed sediment during the rainy season. Also untreated wastewaters generated by industrial activities and from domestic sewage appear to be potential non-point sources in the most industrialized and populated part of the basin. On the other hand, atmospheric transport of mercury originating from the Campinas Metropolitan Region could be another source of mercury contamination, especially in the basin headwaters.

Evaluation of metals in water and sediments of micro-basins in the city of Americana, São Paulo state, Brazil

“…Among these researches, the diagnostic work on water quality in micro-basins developed by Medeiros et al [3], in the city of Americana, Daniel et al [4] and Fostier et al [5], in the Piracicaba river basin, and Moreira and Fazza [6], in the county of Limeira, near Americana city, stand out. These works showed a scenario of significant degradation of water quality, basically by discarding of domestic sewage and industrial effluent without any treatment.…”

Mercury concentration in the freshwater bonefish Cyphocharax gilbert (Curimatidae) and its parasite the crustacean Riggia paranensis (Cymothoidae)

“…The analyses of fish muscle have allowed the assessment of how humans have been exposed to mercury and the evaluation of detrimental effects on animals at higher trophic levels, especially in gold mining areas (Uryu et al, 2001). The mercury concentrations reported in the edible part of the fish collected from several Brazilian freshwater environments varies from 20 ng.g -1 to 700 ng.g -1 in non-piscivorous species and from 60 ng.g -1 to 1,000 ng.g -1 in piscivorous ones (Lacerda et al, 1994;Malm et al, 1995;Lacerda, 1997;Bidone et al, 1997aBidone et al, , 1997bLebel et al, 1997;Moraes et al, 1997;Castilhos et al, 1998;Brabo et al, 1999;De Souza et al, 2000;Lechler et al, 2000;Lima et al, 2000;Leady & Gottgens, 2001;Uryu et al, 2001;Da Silva et al, 2005;Farias et al, 2005;Fostier et al, 2005). The levels of mercury in the edible part of C. gilbert, a nonpiscivorous fish, were close to the lowest values reported for Brazilian fish, suggesting that there is currently a low impact of mercury in the middle Itabapoana River food chains.…”

Dissolved Heavy Metal Determination and Ecotoxicological Assessment: A Case Study of the Corumbataí River (São Paulo, Brazil)

“…In the case of the Corumbataí River, for example, many substances such as heavy metals have been detected in the water, sediments, and fish (19,20). Beside heavy metals, several classes of herbicides have been reported (21).…”

“…Many studies of the rivers of São Paulo have been developed to identify and quantify metals in different matrices. For example, Fostier et al (20) observed that Hg contaminated all compartments (water, sediment, soil, and fish) in the Piracicaba River Basin. In the same basin França et al (37) found more than 30 elements in suspended sediments, including those of great environmental importance such as Se, Sb, Cr, Mo, Zn, and Hg.…”