Ernesto Brugnoli

A multi-molecular marker assessment of organic pollution in shore sediments from the Río de la Plata Estuary, SW Atlantic

Organic pollution was evaluated in surface sediments along the middle portion of the Río de la Plata Estuary, SW Atlantic. A multi-molecular marker approach was performed to identify major sources of organic compounds using diagnostic indices. The relative contribution of different sources of hydrocarbons was quantified by source apportionment employing Principal Component Analysis/Multiple Linear Regression (PCA/MLR) as chemometric technique. All molecular markers indicated high chronic organic pollution in the stations of Montevideo Bay. Main sources of aliphatic and polycyclic aromatic hydrocarbons were petroleum inputs and combustion, due to oil transport and refinement, harbour activities and vehicular emissions. Major sources of linear alkylbenzenes and steroids were industrial and domestic sewage. Although, significant anthropogenic inputs, a natural footprint of terrestrial higher plants contribution was recognized. Multi-molecular marker and comprehensive assessments can improve the establishment of more precise regulation actions to reduce pollution levels.

Integrated assessment of contaminants and monitoring of an urbanized temperate harbor (Montevideo, Uruguay): a 12-year comparison

A cidade de Montevideu, com mais de 1,5 milhoes de habitantes, circunda a Baia de Montevideu, onde um dos portos mais ativos e poluidos da America do Sul esta localizado. No presente trabalho, foram avaliados esterois fecais, metais traco, compostos organoclorados e derivados de petroleo nos sedimentos superficiais do Porto de Montevideu, analisando sua distribuicao espacial no interior do porto, bem como em dois dos principais tributarios que chegam ao interior da baia. Especificamente para os sitios do porto, foi realizada uma comparacao temporal dos metais pesados e hidrocarbonetos, considerando dados preteritos de 12 anos. Foram observadas alteracoes significativas nos sitios estudados. Metais, tais como o Pb, Cr e Zn, apresentaram reducao nas suas concentracoes, enquanto os hidrocarbonetos alifaticos aumentaram seus valores em quase todas as estacoes. Foram observadas tambem diferencas entre o verao e o inverno, sugerindo mudancas no padrao de sedimentacao, nos ingressos de substâncias e/ou mudancas hidrodinâmicas na area. Os resultados podem vir auxiliar na compreensao do estado atual e para o desenvolvimento de medidas de gestao necessarias para melhorar a qualidade ambiental do porto e da baia.

Diatoms, protein and carbohydrate sediment content as proxies for coastal eutrophication in Montevideo, Rio de la Plata Estuary, Uruguay

A study on sediment surface diatom composition in relation to both protein/carbohydrate content and salinity was carried out in Montevideo Bay and the adjacent coastal zone. Samples were seasonally taken during one year along a human impact gradient, and the trophic conditions were assessed from the biochemical composition of the surface sediment organic matter. The co-occurrence of the marine-brackish (Actinocyclus curvatulus, Actinocyclus gallicus, Coscinodiscus excentricus, Coscinodiscus radiatus, Hyalodiscus subtilis, Paralia sulcata) and freshwater diatom flora (Aulacoseira granulata, Aulacoseira italica, Aulacoseira muzzanensis, Actinocyclus normanii, Amphora copulata, Cyclotella meneghiniana, Nitzschia linearis), suggests myxohaline estuarine conditions in the study area. The sampling stations located within the bay, close to several contamination sources, exhibited hypertrophic conditions as indicated by the highest levels of protein content, but also by the high relative abundances of Actinocyclus normanii and Cyclotella meneghiniana, as both diatom species are very well established cosmopolitan proxies of aquatic degradation. The levels of both protein and carbohydrate content, but also photosynthetic pigments, recorded in the adjacent coastal zone suggest meso-eutrophic conditions as contamination levels from the inner bay might become diluted off shore. Multivariate diatom species-environmental data relationships, indicate that the trophic gradient is hierarchically more important than salinity in explaining the diatom distribution. The present data imply an improvement in our ability of assessing organic contamination in the study area, since both biological and biopolymer variables were introduced for the first time as a tool for assessing the benthic health/degradation in one of the most populated regions of the Rio de la Plata.

Diatom assemblages from surface sediments of the Río de la Plata estuary, Uruguay

ABSTRACT The Río de la Plata estuary (RdlP) exhibits environmental gradients associated with the freshwater input and oceanic water intrusion. The aim of this study was to assess diatom species distribution in surface sediment samples related to such environmental gradients. The internal section of RdlP was dominated by Aulacoseira spp., Eunotia spp., Staurosirella martyi, Actinocyclus normanii and Thalassiosira baltica, indicatives of low salinity levels and high trophic conditions, associated with the riverine and estuarine regimes. The external section was dominated by Coscinodiscus radiatus, Thalassiosira spp., Paralia sulcata, Cyclotella striata, among other marine taxa, indicatives of high salinity and low trophic conditions, associated with the influence of the Southwestern Atlantic Ocean. Furthermore, the intermediate section presents a mixture of both diatom groups representing mixing conditions. The observed diatom species groups capture fairly well the RdlP environmental variability and can be reliably used for paleoenvironmental studies in this and other similar estuarine systems.

Anthropogenic and natural variability in the composition of sedimentary organic matter of the urbanised coastal zone of Montevideo (Río de la Plata)

This study is aimed to identify the different sources of sedimentary organic matter (SOM) within Montevideo coastal zone (MCZ). To this end δ13C, δ15N and C/N ratio were analysed in surface sediments and a sediment core. Sediment core analysis showed that until ~1950CE SOM was mainly marine, observing a shift towards lower δ13C in recent sediments, evidencing an estuarine composition. This trend was associated to the climatic variability, which exerted a major influence on the SOM composition, leading to an increased input of terrigenous material and associated anthropogenic contaminants. Surface sediments collected during different El Niño South Oscillation (ENSO) phases did not show inter-annual variability in SOM composition, which was mainly marine in both eastern and western region of MCZ and estuarine in Montevideo Bay. This spatial pattern provides new insights on the dynamics and factors affecting organic matter sources available for primary consumers along the study region.

Aplicación de isótopos estables como indicadores de flujos de energía en ambientes costeros de Uruguay

El analisis de isotopos estables en sedimentos, vegetales y animales representa una herramienta de importancia para estudios ecologicos, reconstrucciones paleoclimaticas y paleoambientales. Con base en la diferenciacion isotopica entre productores primarios, esta tecnica ha tenido un gran impacto en la identificacion de flujos de energia entre ecosistemas terrestres y acuaticos adyacentes y en la estructura trofica. Se sintetizan aqui la nomenclatura y los principios basicos para la aplicacion de isotopos estables en estudios de ambientes acuaticos. Ademas, se muestra su utilidad describiendo tres ejemplos recientes en ambientes costeros de Uruguay con diferentes objetivos: 1) evaluar el origen de la materia organica en sedimentos del Rio de la Plata, 2) determinar la importancia trofica de una especie de diatomea en playas arenosas de Uruguay, y 3) evaluar la influencia de la materia organica antropogenica en la Bahia de Montevideo. La composicion isotopica de las fuentes de materia organica permitio inferir los mecanismos involucrados en la transferencia de materia organica en los ecosistemas costeros. En esta revision se subrayan las ventajas de este marcador isotopico de carbono que permite discriminar fuentes de materia organica. Asimismo, la combinacion con otros analisis complementarios como la espectrofluorometria o los biopolimeros resulta importante en investigaciones de funcionamiento ecosistemico.

Copper, zinc, mercury and arsenic content in Micropogonias furnieri and Mugil platanus of the Montevideo coastal zone, Río de la Plata

Foram estudadas as concentracoes de metais (Cu, Zn, Hg) e metaloides (As) em exemplares de Micropogonias furnieri e Mugil platanus coletados em tres locais ao longo da costa de Montevideu (Uruguai) durante o inverno de 2010 e as primaveras de 2010 e 2011. Comparados com estudos previos realizados nessas areas, ambas as especies apresentaram concentracoes maiores (para Cu), similares (para Zn) ou menores (para Hg). Os valores mais elevados de Hg foram encontrados em M. furnieri da baia de Montevideu. Nao houve variacao espacial na concentracao dos elementos Cu, Zn, and As, provavelmente devido a alta mobilidade de ambas as especies. No entanto, a concentracao de Cu no figado de M. furnieri foi maior nos peixes da area Oeste. Cu, Zn e As foram encontrados em M. platanus em valores mais elevados do que no figado de M. furnieri. A relacao funcional entre os niveis de Zn e Hg no musculo e o comprimento dos peixes em M. furnieri indica bioacumulacao para estes metais. De acordo com os resultados, M. furnieri pode ser utilizado como bioindicador temporal para Hg, mas nao como bioindicador espacial. Os niveis de Hg registrados estiveram abaixo do nivel maximo de seguranca com base nos valores do padrao internacional para o consumo humano.