Especiaci??n de zinc en sedimentos marinos del fiordo Ays??n

Abstract

Zinc speciation in marine shallow sediments from Aysen fjord was analyzed using a differential attack. This treatment was used in order to identify the dominance of the different Zn species. Samples were collected in two stations, one of them in the fjord mouth, and the other in the fjord head, november 2001. The Zn total results were: 168.0 ?? 15 ??g-g -1 at the fjord head (corresponding to enriched sediments) and, 83.6 ?? 6 ??g.g -1 at the fjord mouth (concentration close to base line value in this area). These results were consistent with the Zn total concentration from the samples obtained in 1995, in stations placed at the same geographic location. The study of speciation of Zn showed that at Stn. 82-a the metals, in order of abundance, were associated with the residual fraction > oxyhydroxides > interchangeables > organic matter > carbonates. In contrast, at Stn. 78-a, in order of abundance the residual fraction > oxyhydroxides 3 interchangeables > carbonates > carbonates > organic material. The resultant relationship among the species of the interchangeable sites were: carbonates : oxyhydroxides : organic material : residuals = 2.7 : 0.44 : 11.2 : 7.5 : 1.4. The percentages of all the species were interchangeable: carbonates : oxyhydroxides : organic material : residuals = 1.37 : 0.21 : 5.73 : 3.9 : 0.71. These results showed that the absolute values for concentrations were independent of percentages of the species. The relationship between, concentration in the sediments showed that Puerto Chacabuco (shipment site of concentrate minerals), had twice the Zn concentrations shown by samples from the mouth of Ays??n Fjord.