Environmental and anthropic variabilities at Guanabara Bay (Brazil): A comparative perspective of metal depositions in different time scales during the last 5,500 yrs.

The determination of age-dated metal sediment accumulation rates in a representative South American bay is able to portray the dimension of human impacts during the colonial occupation and industrial periods. Many studies have assessed metal distribution and chronology at Guanabara Bay, in Brazil. However, understanding natural variabilities associated to paleoclimatic changes and comparing these natural variabilities to anthropogenic processes are not well established to date. Accurate geochronological control integrating ages determined by 210Pb and 14C chronologies through an exponential spline fit model allowed for a precise definition of changes associated to the holocene marine transgression, as well as the colonial period, leading to intense land use changes, and the industrial period. The reference values of the system were defined based on their concentrations and the accumulation rates of ecotoxicologically important metals. Al, Ba, Fe, Cd, Cu, Cr, Li, Ni, Mn, Pb, Si, Ti, V, and Zn distributions were determined in a Guanabara Bay core (BG-28) by the EPA 3051 method. Elemental distribution profile assessment allowed for the identification of variabilities associated to weathering processes, predominantly of lithogenic origin, mainly for Al, Ba, Fe, Li, Si, and V. Weathering processes occurred simultaneously to land use changes in the drainage basin since the colonial period, at 400 cal yr BP, and during the industrial period, mainly after the 1960s, denoted by Cd, Cr, Cu, Mn, Pb and Zn increases. The highest average metal enrichment values metals associated to industrial processes reached 5.95, with 119.1-fold higher accumulation rates than the background accumulation values observed between 4200 and 500 cal yr BP.

Environmental risk increase due to heavy metal contamination caused by a copper mining activity in Southern Brazil.

The Camaquã Copper Mines (CCM) were the main sulphide deposit in Southern Brazil and have been in operation from last century to 1996. To evaluate water contamination and environmental risk increase by heavy metals from mining operations, two points on the João Dias Creek were sampled (Station 1, background area and Station 2, contaminated area). Mining activity increased the natural weakly heavy metal fluxes by approximately 5424 kg. (approximately 60%) of the total metal flux, 1542 kg. (approximately 49%) of dissolved and 3881 kg (approximately 66%) of particulate metal flux. Total metal flux of anthropic origin was mostly due to Fe followed by Cu > Zn > Mn whereas Cd, As and Pb fluxes were negligible. The potential human health hazards and risk assessment related to daily intake of water from João Dias Creek are mostly due to Mn and should be of concern for the contaminated area. The ingestion of water from station 2 represents incremental risks of 130% and 59% respectively, considering the non-carcinogenic and the carcinogenic effects. The real increase of human health hazards may be greater than those related to the total concentrations since Mn and As dissolved concentrations were 5.5 and 2.0 higher than acceptable, respectively.

Mercury concentrations in fish from the Itacaiúnas-Parauapebas river system, Carajás region, Amazon

This paper reports on total Hg concentrations in muscle tissue from 12 fish species collected in the Itacaiúnas and Parauapebas Rivers in the Carajás region,South Pará. It is found that carnivorous species present Hg concentrations higher than herbivorous and omnivorous species. Also, large carnivorus species presented higher Hg concentrations than smaller carnivorus species. Significant positive relationship are found between fish weight and total Hg concentrations for at least two studied in detailed, the carnivorous Paulicea likeni (jaú) and Serrasalmus nattererii (piranha)

Mercury concentrations in fish from the Itacaiúnas-Parauapebas River system, Carajás region, Amazon.

This paper reports on total Hg concentrations in muscle tissue from 12 fish species collected in the Itacaiúnas and Parauapebas Rivers in the Carajás region, South Pará. It is found that carnivorous species present Hg concentrations higher than herbivorous and omnivorous species. Also, large carnivorous species presented higher Hg concentrations than smaller carnivorous species. Significant positive relationships are found between fish weight and total Hg concentrations for at least two species studied in detailed, the carnivorous Paulicea lutkeni (jaú) and Serrasalmus nattererii (piranha).

Heavy-metal pollution assessment in the coastal lagoons of Jacarepaguá, Rio de Janeiro, Brazil.

The Jacarepaguá lagoon receives the waste from 239 industries and domestic sewage. Bottom sediment analysis revealed that metal pollution is not spread over the lagoons but restricted to the discharge areas of the main metal-carrier rivers. Metal concentrations in superficial water showed the following concentrations values in ng/ml: Zn, 9.63+/-3.59; Pb, 0.61+/-0.43; Cu, 0.94+/-0.45; Mn, 12.7+/-8.0. Metal concentration in fish (average of seven different species) presented the following results, in mg/kg wet weight: Cr, 0.08+/-0.01; Cu, 0.4+/-0.15; Zn, 4.6+/-3.4; Fe, 2.4+/-1.3; Mn, 0.4+/-0.3. These results imply, considering fish consumption rate and the RfD (USEPA Reference Dose), that the local population is not exposed to undue health risks. Metal concentrations in the water may, however, increase due to their dissolution induced by pH and redox changes in the sediments.