Sandra Elizabeth Botté

Latest approaches on green chemistry preconcentration methods for trace metal determination in seawater – A review

Evaluation of trace metal levels in seawater samples is undertaken regularly by research groups all over the world, leading to a growing demand for techniques involving fewer toxic reagents, less time-consuming protocols and lower limits of detection. This review focuses on providing a brief but concise description of the latest methodologies developed to this end, outlining the advantages and disadvantages of the various protocols, chelating and dispersive agents and instruments used. Conclusions are drawn on the basis of the articles reviewed, highlighting improvements introduced in order to enhance the performance of the protocols.

Tidal time-scale variation of inorganic nutrients and organic matter in Bahía Blanca mesotidal estuary, Argentina

Land-derived materials are regulated by coastal and shelf environmental conditions before being transported to the open sea. It is of great concern to understand the processes and to establish the extent in which they modify terrestrial compound fluxes, such as nutrients, that end up in the oceans. At present, one of the topics that arouses the highest interest within environmental coastal studies is the direction and magnitude of inorganic nutrients and the exchange fluxes of organic matter between the water column and the associated tidal plains during the daily tidal cycle. These processes, together with the local hydrographic conditions, define the key role of this type of environment: its function as a nutrient and organic matter reservoir and/or as a source. A research programme directed to understand this mechanism within mesotidal estuaries was developed in the Bahía Blanca estuary, on the coast of Buenos Aires (Argentina). On a tidal time-scale basis, levels of DIN (nitrate + nitrite + ammonium), DIP, DISi, and organic matter were measured in the estuarine water column and tidal plain porewater, for two years. Results showed no significant variations during the tidal cycle, even though the temporal variation of these compounds was clearly identified. In addition, the biological production of the estuary was considered and taken into account, so as to understand the organic matter cycle within the system. Particular conditions of the environment (sediment characteristics, porewater chemical environment, hydrodynamics, anthropogenic sources, etc.) were also considered to help fully understand the results.

Above- and belowground biomass and nutrient pools of Spartina alterniflora (smooth cordgrass) in a South American salt marsh

In order to examine the role of position in the tidal range on biomass production and nutrient pools in Spartina alterniflora in an Argentinian estuary, we estimated productivity, the concentration of C, N and P in tissues and pools (concentration×biomass) of these elements in low (LM) and high (HM) zones. Aboveground biomass of S. alterniflora was higher in HM than in LM. Aboveground primary productivity was 106 and 439 g dry wt m−2 year−1 in LM and HM, respectively. Belowground biomass was similar in LM and HM. Belowground primary productivity was 526 and 744 g dry wt m−2 year−1 for LM and HM, respectively. Nutrient pools were higher in HM than in LM. Biomass and productivity values were low, which makes nutrient pools low. The lower values of the parameters analysed in LM than in HM indicate that position in the tidal range is an important factor in this system, possibly due to the effect of flooding. Moreover, this pattern is opposite to the general one observed in the northern hemisphere, meaning that studying marshes from different environments is worth doing. Because pools were higher in HM, this zone would be more important for nutrient input to the estuary.

Burrowing Crab ( Neohelice granulata ) as a Potential Bioindicator of Heavy Metals in the Bahía Blanca Estuary, Argentina

Bioindicators can be used to determine spatial and/or temporal variations of heavy metals in a certain coastal or marine environments. This study investigated the potential use of the burrowing crab Neohelice granulata from two different locations in the Bahía Blanca estuary, a moderately polluted ecosystem. Concentrations of zinc (Zn), nickel (Ni), and lead (Pb) in soft tissues of male and female crabs were measured. In addition, concentrations of the three metals in eggs were compared with concentrations in female crabs. No geographical differences were found for any of the three metals, whereas sexual and seasonal differences were obtained for Zn and Ni, with the winter season posing lower concentrations. Moreover, the three metals were detectable in eggs and were lower than concentrations in female crabs (except for Zn). Finally, the usefulness of this species as a potential bioindicator of heavy-metal pollution within this estuarine ecosystem is discussed.

Ecological processes and biogeochemical cycling in salt marshes: synthesis of studies in the Bahía Blanca estuary (Argentina)

Here we offer an integrative review of biogeochemical cycling of carbon, nitrogen, phosphorus, and several metals in salt marshes of the Bahía Blanca Estuary, located in South America, which is a region underrepresented in the literature. The dominant species, Spartina alterniflora and Sarcocornia perennis, have low net aboveground primary productivity but play substantial and contrasting roles in the biogeochemical cycling of elements. S. perennis was more efficient at metal sequestration, whereas S. alterniflora was important in the immobilization of phosphorus. Because of the differences in net aboveground primary productivity between high and low marsh, plant position should be considered to evaluate the role of S. alterniflora on biogeochemical cycles. Some elements were also in high concentrations in belowground tissues but, based on our data, we could not accurately estimate net belowground primary productivity, a key process to evaluate elemental cycling in salt marshes. In spite of uncertainties in the estimations, the slower decomposition rates in S. alterniflora would be indicative of a higher contribution to the long-term storage of nutrients and metals within the marsh. Regardless shortcomings, our work represents a valuable tool for comparisons with salt marshes worldwide.

Essential and non-essential heavy metals in skin and muscle tissues of franciscana dolphins (Pontoporia blainvillei) from the southern Argentina coast

Franciscana dolphin, Pontoporia blainvillei, is a small and ‘vulnerable’ cetacean, which exhibits coastal marine habits according to the IUCN (2008). The aim of this work was to determine the presence of essential (Zn and Cu) and non-essential (Cd, Pb, Cr and Ni) heavy metals in skin (n=33) and muscle (n=36) tissues of franciscana dolphins from southern Buenos Aires, establishing the influence of biological parameters on the accumulation of these pollutants. Histological standardised methods were used to determine both age and sexual maturity of the dolphins. Heavy metal concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Zn was 8-fold higher than Ni in the skin. Zn was significantly affected by the age of the specimens and might be influenced by the state of body condition. Ni showed a behaviour pattern similar to that of non-essential heavy metals. The relationship between Ni and Zn concentration determined in skin and muscle might provide a tool for studying the general condition of endangered marine mammal species such as franciscana dolphins.

Exceptionally high Cd levels and other trace elements in eggshells of American oystercatcher (Haematopus palliatus) from the Bahía Blanca Estuary, Argentina.

Concentrations of six trace metals were determined in the eggshells of American oystercatchers (Haematopus palliatus) from the Bahía Blanca estuary, Argentina. All metals measured in selected samples presented concentrations above the detection limit. Means found for Cu, Pb, Cr, Zn and Ni were as follow: 2.02±0.52, 7.23±2.33, 0.78±0.03, 2.22±1.13 and 6.05±0.89mg/kg dw. The mean concentrations of Cd found were surprisingly high: 13.28±3.38mg/kg dw. Previous studies made on prey items of the American oystercatchers showed low to medium concentrations of the six trace metals. This may indicate a possible transfer of the metals that are available in the environment through food chains. Our study indicates that American oystercatchers sequester heavy metals in their eggshells. Therefore the eggshells may be useful as biomonitors for trace metal contamination in the Bahía Blanca estuary.

Occurrence and spatial distribution of metals in intertidal sediments of a temperate estuarine system (Bahía Blanca, Argentina)

Abstract Intertidal sediments of the inner and middle zone from the Bahía Blanca estuary were sampled for geochemical and environmental assessment of metals (Cd, Cu, Pb, Zn, Mn, Ni, Cr and Fe). Results indicate that both the organic matter content and the sediment grain size plays an important role in controlling the differential concentrations of the metals found in sediments from both zones. For most of the elements (except Mn), sediment metal concentrations were greater in the middle zone, although the concentrations did not exceed the maximums for quality of marine sediments. In this sense, anthropogenic impact (i.e., sewage drain) appears to be a key factor in the distribution of metals within the estuarine system. Comparing the levels obtained with quality levels (LEL and SEL), except Cu that showed levels slightly above the LEL, the rest of the concentrations of metals were lower to those levels. The low metal concentrations obtained within this highly impacted estuarine system suggest that the great volume of water that flooding the extensive flats in each tidal cycle has much importance. Although the potential risks of metals to the estuarine environment were low, taking into account the toxicity of some of these metals, continuity of monitoring is highly recommended.

Distribution and behavior of zinc in estuarine environments: an overview on Bahía Blanca estuary (Argentina)

Zinc concentrations and distribution have been fully studied within Bahía Blanca estuary, an area which is strongly influenced by urban and industrial stress. Not only metal dissolved in estuarine water were measured but also measured were sediments and suspended particulate matter (SPM), as well as associated with estuarine organisms. In all cases, internationally standardized protocols were applied to metal measurements, including analytical quality check test through analysis of certified reference materials. Total metal contents from surface sediments and SPM were compared with those from a historical database of the area, as well as with values representing the natural geochemical baseline within the system. Results showed that heavy metal pollution is mainly localized in the areas close to both industrial effluents discharge system and urban sewage outfall discharge. Data from sequential extractions indicate that metals from anthropogenic sources are potentially more mobile than those inherited from geological parent material. The influences of other potential sources of metals (i.e., streams, runoff) were also considered. SPM was clearly identified as the main carrier of the studied heavy metals within the system, and its significance to metals input into sediments and/or biota was verified. Zinc has been accumulated within the different biological species from Bahía Blanca estuary, and their kinetics of accumulation have also been considered. Finally, the combination of the obtained results allowed suggesting the maintenance of a surveillance program to assess the environmental quality of this environment.

Metals in tidal flats colonized by microbial mats within a South-American estuary (Argentina)

In this study, we measured the concentrations of metals (Cd, Cu, Pb, Ni, Cr, Zn, Hg, Mn, and Fe) and assessed the characteristics of tidal flats (grain size and organic matter content) in sediments and their overlying microbial mats fractions to evaluate the anthropogenic impact within the Bahía Blanca Estuary (BBE). Puerto Rosales (PR) and Almirante Brown (AB), located in the middle and inner zone of the estuary, respectively, were used as sampling sites. Sediments were composed mainly of silt–clay in AB, whereas first fine-grained particles were coarser in depth in PR. Regarding the concentration of metals in both fractions, we found differences between sites: There were higher concentrations of overall metals in AB relative to PR. In addition, higher concentrations of Cu were recorded in the first centimeters of AB tidal flats, whereas higher concentration of Cd were recorded in microbial mats of PR. Considering that the grain size was similar between sites, these results are consistent with the high concentration of organic matter found in AB, probably because this site is close to a former municipal dump and sewage discharges. Also, the higher Cd content found in PR site would highlight both the influence of untreated urban discharges and port anthropogenic activities. In conclusion, this study allowed identifying high values of some metals in the presence of microbial mats in the BBE, thus suggesting a possible interaction between both, at least for metals like Cu or Cd.