Distribution of particulate trace metal in the southern part of the Patos Lagoon estuary

Abstract

The analysis of suspended particles probably provides the best basis for assessing metal contamination of aquatic environments. However, such assessments cannot be made unless sufficient knowledge of natural contributions to observed concentrations is available. As different coastal areas are influenced by different natural inputs from their watersheds, assessments of natural versus anthropogenic contributions to metal concentrations must be made on a regional or site-specific basis. The purpose of this research was to assess whether anthropogenic inputs of heavy metals into the surrounding waters of Rio Grande City were large enough to significantly affect concentrations in the southern part of the Patos Lagoon Estuary. Particulate samples were collected during 15 monthly cruises at seven fixed stations from May 1990 to June 1991 and analyzed under different seasonal and hydrological conditions. Results show that the local inputs from urban, industrial and harbor activities in the city of Rio Grande have produced enrichments of copper, lead and zinc (but not iron) in suspended sediments in the three areas studied. The different behavior presented by these three areas are mainly due to hydrodynamic conditions and to distance from the harbor activities. Meteorological conditions which favor resuspension of bottom sediment, resulting in high total suspended matter concentrations, mask anthropogenic inputs.

Labile copper and zinc fractions under different salinity conditions in a shipyard area in the patos lagoon estuary, south of Brazil

“…11 Studies undertaken in the Patos Lagoon estuary in southern Brazil have measured the total trace metal concentrations in water and SPM in the estuary channel. [21][22][23] These studies indicated low levels of metals in accordance with the national recommendations issued by CONAMA 357 (2005). 24 However, the labile fraction of trace metals in the water column is not well known.…”

“…In total, 6 deployments were carried out, two in each seasonal period. Following a conceptual model of the distribution and behavior of dissolved metals vs. salinity in the Patos Lagoon estuary, the range of salinity was classified as low (0-6), intermediate (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) or high (above 25). 22 In each deployment period, four devices were attached to a rope fixed on a pier at 0.5 m depth about 10 m from the margin area of the estuary.…”

In situ measurement of trace metals in estuarine waters of Patos Lagoon using diffusive gradients in thin films (DGT)

“…These main sources are responsible for the presence of high level of nutrients and metals in waters in the vicinity of the city. 19,24 Additional contamination comes from three ports located near the city, one of which is the most important port of Brazil, in terms of the number of containers shipped. Wallner-Kersanach et al 335 Vol.…”

“…These main sources are responsible for the presence of high level of nutrients and metals in waters in the vicinity of the city. 19,24 Additional contamination comes from three ports located near the city, one of which is the most important port of Brazil, in terms of the number of containers shipped. In both experimental sites, DGT devices were deployed back to back attached to a length of 4 mm polypropylene rope at a depth of about 0.5 m. Triplicate DGT devices were collected after 2, 6 and 10 days of deployment period.…”

“…However, DGT devices have been shown to be more sensitive than mussels (Mytilus edulis) in detecting differences in metal concentrations between sites, indicating an advantage of DGT in studying the geographic distribution of contamination. 18 Previous studies have identified some inputs of trace metals to the Patos Lagoon estuary 17,19 from untreated urban and industrial waste water discharges present around the city of Rio Grande. The increase of the industrialization in the estuary area, together with the dynamic nature of the environment, makes it necessary to evaluate trace metals contaminations in some areas around the city.…”