Mário Mil-Homens

Major factors influencing the elemental composition of surface estuarine sediments: The case of 15 estuaries in Portugal

Upper sediments (0-5 cm) were sampled in 94 sites of water bodies of the fifteen Portuguese estuaries characterized by distinct settings of climate, topography and lithology, and marked by diverse anthropogenic pressures. Confined areas recognized as highly anthropogenic impacted, as well as areas dominated by erosion or frequently dredged were not sampled. Grain size, organic carbon (Corg), Al and trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were determined. Normalisation of trace element concentrations to Al and Corg, correlations between elements and Principal Component Analysis (PCA) allowed identifying elemental associations and the relevance of grain-size, lithology and anthropogenic inputs on sediment chemical composition. Whereas grain-size is the dominant effect for the majority of the studied estuaries, the southern estuaries Mira, Arade and Guadiana are dominated by specific lithologies of their river basins, and anthropogenic effects are identified in Ave, Leça, Tagus and Sado. This study emphasizes how baseline values of trace elements in sediments may vary within and among estuarine systems.

Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal).

Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5 ng g(-1). A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments.

Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies.

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.

Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: a fingerprint of human activities.

Stable Pb isotope ratios ((206)Pb/(207)Pb, (208)Pb/(206)Pb), (210)Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200 years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of (206)Pb/(207)Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine-coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin.

Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, Portugal

The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg-1 and 18 to 210mg·kg-1, respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries.

Historical trends in Hg, Pb and Zn sedimentation in the central shelf area of Portugal

Temporal records of excess 210Pb, and the determination of major (Al and Ca) and trace elements (Zn, Cr, Ni, Pb, Cu and Hg) in two sediment box-cores, collected in the central area of the Portuguese shelf of North of the Nazare canyon (offshore from the Lis River), allow evaluation of the deposition of various chemical elements normally associated with anthropogenic activities. In order to compensate for the natural sediment variability, heavy metal contents were normalised to Al. Temporal variations of Hg, Pb and Zn (Al-normalised) show an increasing trend since the beginning of the 1920’s, recording the development of industrial activities. Enrichment factors (EF) were calculated to estimate the level of contamination in these sediments. Mercury is the element with the highest average EF values (EF = 3), followed by Pb (EF = 1.5) and Zn (EF = 1.2). The results indicate that since 1991 64% of total Hg, 44% of total Pb and 24% of total Zn are derived from anthropogenic sources. The average anthropogenic fluxes of Hg, Pb and Zn (0.008, 3, 6 μg cm-2yr-1, respectively) for the last 40 years in a ca. 400 km2 deposition area represent a total accumulation of approximately 30, 12000 and 24400 kg per year of Hg, Pb and Zn, respectively. These results indicate that despite the high-energy conditions and the generally sandy nature of the Portuguese shelf sediments, it is possible to identify significant anthropogenic enrichments in some areas of sediment accumulation. These contaminants are not necessarily related to immediate sources but may instead indicate atmospheric and or marine transport from more distant sources.

Are There Real Advantages of Induction Therapy With Basiliximab in Renal Transplantation

BACKGROUND Randomized clinical trials have supported the use of interleukin-2 receptor (IL-2R) antagonists as induction therapy in renal transplantation. This strategy has reduced the incidence of acute rejection episodes (ARE) but not improved graft survival. Our objective was to investigate the impact of induction therapy using the IL-2R antagonist basiliximab, as compared with no induction therapy, on relevant clinical outcomes-initial length of stay, incidence of ARE, long-term graft function, and graft survival. METHODS We retrospectively reviewed the medical records of patients transplanted in a tertiary care center between 1996 and 2011. We selected patients who received cyclosporine, mycophenolate mofetil, and prednisolone (n = 334) to classify as: no induction therapy (n = 131; group 1); induction therapy with basiliximab (n = 203; group 2). Estimated glomerular filtration rate (eGFR) was assessed with the 4-variable Modification of Diet in Renal Disease (MDRD) equation. RESULTS Mean follow-up was 72.7 ± 35.4 months. Patients who received basiliximab had a shorter mean hospital stay (19.2 versus 22.5 days; P = .02), lower incidence of ARE (10.8% versus 23.7%; P = .02) and better graft function post transplantation at 12 months (mean eGFR 59.4 ± 18.4 versus 54.8 ± 18.7 mL/min/1.73 m(2); P = .015) and 5 years (mean eGFR 64.1 ± 21.5 versus 55.4 ± 19.6 mL/min/1.73 m(2); P = .009). On multivariate analysis, induction therapy with basiliximab was independently associated with a lower incidence of ARE and better graft function at 1 and 5 years after transplantation. There was no difference in 5-year graft survival between the two groups (log-rank: P = .54). CONCLUSIONS Induction therapy with basiliximab was associated with a reduced incidence of ARE and better long-term graft function but no difference in 5-year graft survival.

Insights of Pb isotopic signature into the historical evolution and sources of Pb contamination in a sediment core of the southwestern Iberian Atlantic shelf

Stable Pb isotopic ratios and concentrations of Al, Cu and Pb were measured in a 5m long sediment core (VC2B) retrieved at 96m water depth in the southwestern Iberian Atlantic shelf. Five phases during the last 9.5kyrs were identified, two of them (Roman Period and modern mining) marked by a decrease of 206Pb/207Pb ratios reflecting additional inputs of Pb derived from mining activities. The Roman Period was also characterized by high 208Pb/206Pb ratios suggesting the exploitation of the outcropping portion of the orebody intensely weathered when compared with the other formations later mined. The shift of 208Pb/206Pb ratios towards linearity took approximately 1.0kyrs, which may mirror the time of environmental recovery from the impact of Roman mining activities. The application of a mixing model allowed the quantification of the contribution associated with anthropogenic mining activities to the shelf sediments. The maximum values of Pb contamination occurred in the 20th century. This study gives direct evidence of Pb and Cu exploitation over the last 2000years. The stable Pb isotopic signatures point to legacy of mining activities that are still the prevailing metal source recorded in the southwestern Iberian Atlantic shelf sediments.

Searching Relationships between Tissue Elemental Concentrations and Geographical Distribution of Bigeye Tuna(Thunnus Obesus) from the South Atlantic Ocean

Tunas are at the top of the food chains and have high metabolism and feeding rates, leading to increased metal accumulation in their tissues. Several tools using biological, biochemical and chemical measurements have been used to identify populations, geographic distributions and migrations of fish species in different environments. Elemental composition (V, Cr, Co, Ni, Cu, Zn, As, Se, Cd and Pb) was determined in muscle and liver tissues of bigeye tuna (Thunnus obesus) caught in three areas of the south Atlantic Ocean. Concentrations in liver (V, Co, Cu, Zn, As, Cd and Pb) point to increased values in specimens captured near the South Africa and South America relatively to the open-ocean areas. The obtained results showed that tissue elemental concentrations in T. obesus from the south Atlantic areas can be used as a natural tag. Due to its role, liver seems to be the best indicator tissue.

Comparing spatial and temporal changes in metal trends (Cr, Ni, Pb and Zn) on the Portuguese shelf since the 1970s

Comparison between an archive dataset, collected during the 1970s (1974–1977), and samples taken during the PALEO1 cruise (2002) enabled evaluation of large-scale and long-term spatiotemporal changes in Al, Cr, Ni, Pb and Zn contents in bulk surface sediments in four areas of the Portuguese shelf. The so-called gradient method (GM) with normalisation to Al, a proxy for terrigenous clay content, was applied. The studied areas are distributed from north to south along the western margin, with the northernmost located off shore the Ave and Douro rivers, a central one located off shore the Lis River and a southern one located off shore the Mira River. One-way ANOVA and Kruskal-Wallis tests were used to identify differences among study areas and periods of sample collection. A comparison of metal contents in 2002 samples with the Portuguese classification scheme regulation for deposition of dredged materials in coastal areas indicates good environmental quality in terms of Cr, Ni, Pb and Zn levels. Nevertheless, the GM results suggest an increase in metal loadings relative to Al from the 1970s to the 2002 samples (except for Pb). The Algarve area on the southern shelf is characterised by having high number of sites with metal level on class 2. These high values have traditionally been explained by a substantial supply of natural metals from the Guadiana, Tinto and Odiel rivers that drain areas Iberian Pyrite Belt formations. This supply has probably been magnified by present and past mining activities. For quality evaluation of marine sediments, especially when using total metal contents, this study shows the importance of considering all possible sources of metal loading. The natural grain size and composition variability have also a crucial influence on the metal content, and the combined evaluation allows a more holistic perspective.