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The 87 Sr/ 86 Sr isotope ratio has been widely used as an indicator of provenance and migration of aquatic animals, and has applications in other areas such as in environmental and forensic studies. However, the modeling of the spatial distribution in the Amazon basin is still incipient, preventing large-scale applications. In this study, we present a baseline of the 87 Sr/ 86 Sr isotope ratio in surface waters of the Amazon basin to infer the provenance and migration patterns of fish. We have compiled an extensive 87 Sr/ 86 Sr database of water samples from the Amazon basin, with data obtained from scientific publications and from field surveys. Next, we developed a geostatistical model, based on spatial interpolation (IDW), to estimate the 87 Sr/ 86 Sr ratio in unsampled locations, considering the influence of geology. Surface river waters in the Amazon show a high isotopic heterogeneity, associated with the region's geology (p < 0.005). Lower isotope ratios are related to waters draining more recent structures, such as the sub-basins of the Andean region, while higher isotope ratios are related to waters draining older crystalline terrains, such as the Guiana and Brazilian Shields. We show a linear relationship between the predicted and observed values (r 2  = 0.81), demonstrating the high accuracy of the modeled data and its potential use in various other studies. The acquisition of additional 87 Sr/ 86 Sr data, along with the integration of new geospatial products, can improve estimates and accuracy in interpretations of strontium geospatial behavior in micro- and macroregions., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Has patent pending to. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

A reliable response of bioindicators to environmental variation is a cornerstone for effective bioassessment and biomonitoring. Fish and aquatic macroinvertebrates are widely used as bioindicators of different human impacts in freshwater ecosystems, but the cost-effectiveness of their usage can be improved through the use of surrogates. We investigated congruence patterns between using different taxonomic and numeric resolutions for aquatic macroinvertebrates and fish to assess community-environment relationships. We also tested whether dataset characteristics (e.g., area sampled, species pool) could explain the variation in the effectiveness of using different taxonomic and numerical resolutions. We used a Brazilian nationwide database encompassing multiple datasets with a gradient of riparian deforestation each. Our findings suggest that families and genera can effectively represent macroinvertebrate genera and fish species, respectively, when using community matrices for assessing community-environment relationships, with an acceptable loss of information. EPT (Ephemeroptera, Plecoptera, and Trichoptera) and Characiformes or Siluriformes may be used as a surrogate, in some cases, for the entire assemblages of macroinvertebrates and fish, respectively, but their use may result in higher loss of information. Presence-absence data also presented a minimal loss of information compared to abundance data, for both macroinvertebrates and fish. The variation in congruence levels among macroinvertebrate datasets was less predicted by dataset characteristics than fish. Across distinct resolutions, on average, 10 % and 19 % of the variation in community composition of macroinvertebrates and fish, respectively, was explained by broad-scale environmental variables, and the effect size was negatively affected by the dataset's sample size and spatial extent for fish. Whereas identification at species (fish) and genus (macroinvertebrates) level and quantification of all individuals still provide the best scenario, we provide evidence that coarser taxonomical resolution and presence-absence data can be used as cost-effective alternatives to facilitate biomonitoring and bioassessment of freshwaters in the Neotropical region impacted by deforestation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Understanding the patterns and mechanisms of biodiversity and its organization in space is essential for developing effective conservation strategies. Zeta diversity is an index of how taxa are shared by several sites, providing information on how ecological filters, including anthropogenic disturbances, influence biodiversity distribution. This study documents how anthropogenic disturbances at multiple spatial extents affect the spatial variation of benthic macroinvertebrate assemblages in lotic ecosystems. To test the relation between zeta diversity and anthropogenic disturbances, we used three disturbance metrics. (a) For in-stream disturbances, we used the percentage of fine sediment in the substrate (PCT&#95;FN). (b) For local/riparian disturbances, we used the Local Disturbance Index (LDI). (c) For catchment disturbances we used the Catchment Disturbance Index (CDI). Our results showed that differing anthropogenic disturbances were differently important for spatial biodiversity variation in benthic macroinvertebrate assemblages. Relatively rarer taxa were usually more susceptible to in-stream and local/riparian-scale disturbances or local environmental filters. On the other hand, relatively common taxa were usually more related to catchment-scale disturbances or landscape resistance to dispersal. These results indicate that conservation efforts to maintain headwater ecosystem biodiversity must incorporate multiple spatial extents because relatively rare and relatively common taxa appear to be affected to different degrees by different anthropogenic disturbances at different spatial extents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

The knowledge of metals concentration in upwelling areas are a concern due the higher productivity of these areas In Cabo Frio Upwelling-Downwelling System (CFUS) is high primary productivity area and has been identified as an Hg hotspot to biota in SE Brazil that has been susceptible to Hg inputs, due to growing industrialization in the region. To investigate the concentration of Hg and Se metals, as well as the trophic transfer of these metals, the present study investigated Hg and Se concentrations in 64 samples collected in net mesh of >20, >64, >150 and >300 μm, in 2012, in the region's water masses. Higher mean Hg concentrations were found in zooplankton, 0.15 ± 0.09 μg g -1 (>300 μm) and 0.18 ± 0.1 μg g -1 (>150 μm), compared to phytoplankton, 0.11 ± 0.11 μg g -1 (>64 μm) and 0.06 ± 0.07 μg g -1 (>20 μm), and the calculation of the biomagnification factor (BMF) indicated that there was a process of magnification and trophic transfer. An opposite trend was found for Se in phytoplankton: higher average Se concentrations were observed in phytoplankton, 93.0 ± 65.2 μg g -1 (>64 μm), 93.8 ± 96.4 μg g -1 (>20 μm), compared to zooplankton, 91.1 ± 67.3 μg g -1 (>300 μm), 97.3 ± 71.3 μg g -1 (>150 μm). A positive linear relationship for the Hg:Al vs P:Al ratios was identified and indicated intracellular incorporation of Hg according to plankton size. Anthropogenic Hg sources were identified in the plankton samples by comparison with the sediment background values for the CFUS. Upwelling waters probably increased the availability of Hg and Se, these elements tend to bioaccumulate 10 to 100 times more than in areas with the influence of upwelling, due to fertilization and the increase in primary production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Despite being one of the most remote areas on the planet, the Antarctic continent is subject to anthropogenic influences. The presence of various groups of contaminants, including persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs), has been documented in the region over the past decades. However, a significant knowledge gap remains regarding the detection of new pollutants, such as emerging contaminants (ECs), in Antarctic coastal environments. This study analyzed the occurrence and levels of selected POPs, PAHs, ECs in surface sediments from Admiralty Bay, Antarctica Peninsula. Non-target screening was employed to identify potential novel contaminants in the region. Samples (n = 17) were extracted using an accelerated solvent extraction (ASE) system and instrumental analyses were performed using gas chromatography coupled to a triple-quadrupole mass spectrometer (GC/MS-MS). Regarding regulated contaminants, concentrations of Σ5PCBs ranged from -1 , while Σ16PAHs ranged from 2.6 to 617.4 ng g -1 . These compounds were predominant in the Martel inlet, suggesting influences of local input sources, especially for PAHs. ECs were detected in some sites of the Ezcurra and Martel inlets, especially nearby the Brazilian and Polish research stations. The UV filters homosalate (0.3 to 251.3 ng g -1 ) and octocrylene (0.7 to 93.8 ng g -1 ) were the most abundant EC, followed by TPP (0.1 to 87.4 ng g -1 ) and galaxolide (0.2 to 55.0 ng g -1 ). Applying non-target analysis, phthalates, and the fragrance OTNE (octahydro-tetramethyl-naphthalenyl-ethanone) were identified for the first time in Antarctic sediments. The data highlights the contribution of human activities in the region, possibly through wastewater effluents. This study provides data on the current levels of PAHs and POPs in the region, which are steadily decreasing over the years., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Operational demands and the natural inflow of water actively drive biweekly fluctuations in water levels in hydropower reservoirs. These daily to weekly fluctuations could have major effects on methane (CH 4 ) and carbon dioxide (CO 2 ) emissions via release of bubbles from reservoir bottom sediments (ebullition) or organic matter inputs, respectively. The impact of transient fluctuations in water levels on GHG emissions is poorly understood and particularly so in tropical run-of-the-river reservoirs. These reservoirs, characterized by high temperatures and availability of labile organic matter, are usually associated with extensive CH 4 generation within bottom sediments. The aim of this study is to determine how water level fluctuations resulting from the operation of the Belo Monte hydropower plant on the Xingu River, eastern Amazon River Basin, affect local CO 2 and CH 4 emissions. Between February and December 2022, we monitored weekly fluxes and water concentrations of CO 2 and CH 4 in a site on the margin of the Xingu reservoir. Throughout the study period, fluxes of CO 2 and CH 4 were 118 ± 137 and 3.62 ± 8.47 mmol m -2 d -1 (average ± 1SD) while concentrations were 59 ± 29.77 and 0.30 ± 0.12 μM, respectively. The fluxes and water concentrations of CO 2 were clearly correlated with the upstream discharge, and the variation observed was more closely associated with a seasonal pattern than with biweekly fluctuations in water level. However, CH 4 fluxes were significantly correlated with biweekly water level fluctuations. The variations observed in CH 4 fluxes occurred especially during the high-water season (February-April), when biweekly water level fluctuations were frequent and had higher amplitude, which increased CH 4 ebullition. Reducing water level fluctuations during the high-water season could decrease ebullitive pulses and, consequently, total flux of CH 4 (TFCH 4 ) in the reservoir margins. This study underscores the critical role of water level fluctuations in near-shore CH 4 emissions within tropical reservoirs and highlights significant temporal variability. However, additional research is necessary to understand how these findings can be applied across different spatial scales., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study identified the occurrence of Holocene chronology hiatuses in the sedimentary record of the Patos-Mirim system caused by river avulsion processes, as well as evidence of sharp anthropogenic changes in the surrounding region of the lagoon water bodies. The presence of chronology hiatuses demonstrates the importance of considering the disturbance effect of paleo-drainage processes on the paleoenvironmental resolution and expression of the sedimentary record of such coastal plains. Anthropogenic activities especially those related to agriculture and forestry have increased significantly during the great acceleration, resulting in modifications of both the landscape and the environmental conditions of the lagoon bodies. Such impacts were clearly reflected in the sedimentary record where abrupt changes in palynological trends, sedimentary DNA, isotopic and granulometric analyses were inferred. The climatic conditions combined with regressive sea level can explain the chronology hiatuses. Pollen analyses demonstrated changes in the landscape, particularly indicated by the shift from Cyperaceae to Poaceae dominance after the 1960 CE. Therefore, all proxies together demonstrate the modification in the landscape and changes in the environment, clearly influenced by anthropogenic action from unsustainable agricultural practices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The fluvial transport of dissolved inorganic carbon (DIC) is an important component of the global carbon cycle. Herein, we assessed the dynamics of DIC and the C stable isotopic composition (δ 13 C DIC ) in a watershed with diversified land use in São Paulo State (Brazil), more specifically in the Sorocaba River basin (SRB) and considered the temporal and spatial scales. For this purpose, twelve fluvial samples at each sampling point (e.g., S1, S2, S3, S4 and S5) were collected in the SRB, from June 2009 to May 2010, which represented one complete hydrological cycle that included the extremes of the rainfall and discharge regimes. In addition, the δ 13 C DIC values were also characterized in the wet and dry season at all sampling points to verify their seasonal variability. The results reflected the seasonal variation in discharges, water temperatures, and electrical conductivities. Most of the DIC was transported in the wet season at all sampling points, where the less negative δ 13 C DIC values were characterized. The natural sources of DIC are associated with atmospheric/soil CO 2 consumption. The anthropogenic impacts on both [DIC] and δ 13 C DIC are linked to untreated urban sewage that is discharged directly into the Sorocaba River, as well as to aquatic photosynthesis in the Itupararanga Reservoir. From 1970 to 2020, the modeling proposed in this study indicated that the annual flux of DIC (F river ) varied from 9.0 to 78.7 t km -2 a -1 , confirming that the El Niño Southern Oscillation (ENSO) controlled F river in the SRB, with higher and lower F river values occurring during strong El Niño (EN) and La Niña (LN) years. The average F river value was 20 t km -2 a -1 , which is higher than those obtained in natural several temperate and tropical watersheds due to the influences of urban areas on [DIC] in the SRB., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Anthropogenic marine debris and invasive species are pervasive in the ocean. However, research on the mechanisms and dynamics controlling their distribution in marine systems (e.g.; by floating debris acting as vectors for invasive species) is limited. Applying a numerical modeling approach, we demonstrate that rafting invasive corals (Tubastraea spp.) can be transported over long distances and reach important tropical receptor regions. In <180 days, buoyant debris can cover distances between 264 and 7170 km moving from the Brazilian semiarid coast to the Amazon coast and reaching eight regions in the Wider Caribbean (mainly the Eastern Caribbean and Greater Antilles). Analyzing 48 simulated scenarios (4 years × 3 depths × 4 months), we demonstrate that in ~86 % of the scenarios the particles are stranded in the Caribbean and in ~71 % they end up in the Amazon coast. Our results showed litter floating trajectories at 0-10 m water depth, transported every year to the Caribbean province. However, in August this transport is frequently blocked by the retroflection of the North Brazil Current adjacent to the Amazon River estuarine plume. Our results indicate routes for fast and long-distance transport of litter-rafting invasive species. We hypothesized a high risk of bioinvasion on important marine ecosystems (e.g., coral reefs) likely becoming increasingly threatened by these invasive species and debris. This highlights the imperative need for an ocean governance shift in prevention, control, and eradication, not only focused on local actions to prevent the spread of invasive species but also a broad international action to decrease and mitigate marine debris pollution globally., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Phase shift is characterized by an abrupt change in the structure of a community in response to a disturbance that can break its resistance, displacing it from its natural variation. This phenomenon has been recognized in several ecosystems and often points to human activities as the main cause. However, reactions of shifted communities to anthropogenic impacts have been less studied. In recent decades, heatwaves resulting from climate change have strongly affected coral reefs. Mass coral bleaching events are recognized as the main cause of coral reef phase shifts on a global scale. In 2019, an unprecedented heatwave hit the southwest Atlantic Ocean causing mass coral bleaching in non-degraded and phase-shifted reefs of Todos os Santos Bay, at an intensity never recorded in a 34-year historical series. We analyzed the effects of this event on the resistance of phase-shifted reefs, dominated by the zoantharian Palythoa cf. variabilis. Using benthic coverage data from 2003, 2007, 2011, 2017, and 2019, we analyzed three non-degraded reefs and three phase-shifted reefs. We estimated the coverage and bleaching of corals and P. cf. variabilis on each reef. There was a reduction in coral coverage in non-degraded reefs before the 2019 mass bleaching event (i.e., heatwave). However, there was no significant coral coverage variation after the event and the structure of non-degraded reef communities did not change. In phase-shifted reefs the coverage of zoantharians did not change significantly before the 2019 event, however, after the mass bleaching, there was a significant reduction in the coverage of these organisms. Here we revealed that the resistance of the shifted community was broken, and its structure was altered, indicating that reefs in this condition were more susceptible to bleaching disturbance than non-degraded reefs., Competing Interests: Declaration of competing interest None declared., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Microplastics (MPs) represent an emergent contamination marker. For this reason, we analyzed the vertical distribution of MPs in six sediment cores retrieved from the Patos-Mirim System, the world's largest coastal lagoonal system. The sediment cores span from mid Holocene to present times according to both radiocarbon and lead dating and are located close to both urban/industrial and agricultural regions. We identified a basal pre-disturbance MP-free zone in all cores and an uppermost contaminated 70-cm-zone, where a general increasing trend in MPs content resembling the human anthropization process was recorded. The predominant format of MPs was fiber, followed by fragments. The most commonly identified polymers were rayon, PVC, acrylate, polycarbonate and cellophane. Urban/industrial and agricultural activities were shown as clear sources of MPs, leading to comparable MPs concentration values in the sediment cores. Thus, MPs are collectively a reliable indicator of the Anthropocene onset, and in the Patos-Mirim System the most appropriate chronology can be assigned to the beginning of 1970s, matching the intensification of anthropogenic activities in the area., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This study characterized the chemical composition of particulate matter (PM) from light- (LDV) and heavy-duty (HDV) vehicles based on two traffic tunnel samplings carried out in the megacity of São Paulo (Brazil), which has >7 million vehicles and intense biofuel use. The samples were collected with high-volume samplers and analyzed using chemical characterization techniques (ion and gas chromatography, thermal-optical analysis, and inductively coupled plasma mass spectroscopy). Chemical source profiles (%) were calculated based on the measurements performed inside and outside the tunnels. Identifying a high abundance of Fe and Cu for traffic-related PM in the LDV-impacted tunnel was possible, linked with the emission of vehicles powered by ethanol and gasohol (gasoline and ethanol blend). We calculated diagnostic ratios (e.g., EC/Cu, Fe/Cu, pyrene/benzo[a]pyrene, pyrene/benzo[b]fluoranthene, and fluoranthene/benzo[b]fluoranthene) characteristic of fuel exhausts (diesel/biodiesel and ethanol/gasohol), allowing their use in the assessment of the temporal variation of the fuel type used in urban sites. Element diagnostic ratios (Cu/Sb and Fe/Cu) pointed to the predominance of LDVs exhaust-related copper and can differentiate LDVs exhaust from brake wear emissions. The carbonaceous fraction EC3 was suggested as an HDV emission tracer. A higher total polycyclic aromatic hydrocarbons (PAHs) fraction of traffic-related PM 2.5 was observed in the HDV-impacted tunnel, with a predominance of diesel-related pyrene and fluoranthene, as well as higher oxy-PAHs (e.g., 9,10-anthraquinone, associated with biodiesel blends) abundances. However, carcinogenic species presented higher abundances for the LDV-impacted tunnel (e.g., benzo[a]pyrene). These findings highlighted the impact of biofuels on the characteristic ratios of chemical species and pointed to possible markers for LDVs and HDVs exhausts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The role of seagrass meadows in the cycling and accumulation of rare earth elements and yttrium (REEY) is unknown. Here, we measured the concentration of REEY in the different compartments of Halodule wrightii (shoots, rhizomes, and roots) and soils in seagrass meadows near sandy beaches, mangroves, and coral reefs in the Todos os Santos Bay, Brazil. We provide data on the accumulation dynamics of REEY in seagrass compartments and demonstrate that plant compartments and soil properties determine accumulation patterns. The ∑REEY in soils were ~1.7-fold higher near coral reefs (93.0 ± 5.61 mg kg -1 ) than near mangrove sites (53.9 ± 31.5 mg kg -1 ) and were slightly higher than in sandy beaches (81.7 ± 49.1 mg kg -1 ). The ∑REEY in seagrasses varied between 35.4 ± 28.1 mg kg -1 near coral reefs to 59.2 ± 21.3 mg kg -1 near sandy beaches, respectively. The ∑REE bioaccumulation factor (BAF) was highest in seagrass roots near sandy beaches (BAF = 0.67 ± 0.48). All values of ∑REE translocation are <1, indicating inefficient translocation of REE from roots to rhizome to shoot. PAAS normalized REE was enriched in light REE (LREE) over heavy REE (HREE). The REEY accumulation in Halodule wrightii revealed a low potential of the seagrass to act as a sink for these elements. However, their bioavailability and potential uptake may change with soil properties. Our results serve as a basis for a better understanding of REE biogeochemical cycling and its fate in the marine environment. REE have experienced increased use as they are central to new technologies revealing an urgent need for further investigations of potential impacts on coastal ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Trace elements (TE) contamination in forested areas of the Itacaiúnas River Watershed (IRW), Brazilian Amazon, arouses growing interest owing to the rapid deforestation and mining activities. In this study, soils (surface, SS; bottom, BS) and stream sediments (SD) from forested/deforested areas of IRW were analyzed with the aim of (1) evaluating the major sources of TE (mainly As, Ba, Cd, Cu, Co, Cr, Hg, Mo, Mn, Ni, Pb, V, and Zn), and (2) examining the soil-sediment TE link related to land-use change and/or geologic factors. Compositional data analysis (CoDA) was used to eliminate data closure issues and the centred log-ratio (clr) transformation yielded better results in Principal Component Analysis (PCA). The TE distribution pattern was significantly different (p < 0.05) between forested and deforested areas, but in both areas the TE distribution pattern is significantly correlated between SS, BS, and SD, indicating a strong lithogenic control. PCA (clr-transformed) identified the major geochemical bedrock signature as Fe-Ti-V-Cu-Cr-Ni, which is nearly similar in soil and sediments. The more accentuated enrichment and the maximum number of anomalies of these elements were found in the Carajás Basin and are highly coincident with mineral deposits/local lithologies without clear indication of anthropogenic contamination from point sources. Besides geogenic factors, deforestation is also affecting TE distribution in the basin. In deforested areas, Mn was significantly enriched in the surface horizon. Furthermore, linear regression analysis shows stronger TE relationships between soils and sediments in deforested areas than in forested ones, reflecting higher erosion in the former. This could be the reason for the relatively higher enrichment of TE (e.g., Fe, Mn, Cu, Cr, Ni) in deforested sediments. The TE contamination using regional background values provides more accurate results than worldwide reference values. Thus, the former should be considered for a more realistic environmental risk assessment in IRW and other forest ecosystems in the Brazilian Amazon., Competing Interests: Declaration of competing interest The authors declare that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In November 2015, the collapse of the Fundão dam (Minas Gerais, Brazil) carried over 40 × 10 6 m 3 of iron ore tailings into the Doce river and caused massive environmental and socioeconomic impacts across the watershed. The downstream mudslide scavenged contaminants deposited in the riverbed, and several potentially toxic elements were further released through reduction and solubilization of Fe oxy-hydroxides under estuarine conditions. A turbidity plume was formed off the river mouth, but the detection of contaminants' dispersion in the ocean remains poorly assessed. This situation is specially concerning because Southwestern Atlantic's largest and richest reefs are located 70-250 km to the north of the Doce river mouth, and the legal dispute over the extent of monitoring, compensation and restoration measures are based either on indirect evidence from modeling or on direct evidence from remote sensing and contaminated organisms. Coral skeletons can incorporate trace elements and are considered good monitors of marine pollution, including inputs from open cut mining. Here, we studied a Montastraea cavernosa (Linnaeus 1767) coral colony collected 220 km northward to the river mouth, using X-rays for assessing growth bands and Laser Ablation Inductively Coupled Plasma Mass Spectrometry to recover trace elements incorporated in growth bands formed between 2014 and 2018. A threefold positive Fe anomaly was identified in early 2016, associated with negative anomalies in several elements. Variation in Ba and Y was coherent with the region's sedimentation dynamics, but also increased after 2016, akin to Pb, V and Zn. Coral growth rates decreased after the disaster. Besides validating M. cavernosa as a reliable archive of ocean chemistry, our results evidence wide-reaching sub-lethal coral contamination in the Abrolhos reefs, as well as different incorporation mechanisms into corals' skeletons., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The palaeolimnological conditions of Mirim Lagoon, a large coastal shallow lagoon under the influence of historical human impacts related to the development of the primary sector of the economy were reconstructed. The first significant human impact consisted of locking the estuarine system to induce the transition from brackish to freshwater conditions. During this transition, the sedimentation rate consistently increased from pre-disturbance values of 0.25 cm yr -1 to >1 cm yr -1 . A concomitant increase in nitrogen and carbon values was recorded indicating a related eutrophication process. The highest nutrient levels were achieved during the 1990s after the incorporation of cutting-edge technologies for agricultural production such as high-yielding varieties of rice resistant to climate variability and pests, and the use of inorganic fertilisers, pesticides and water supply controlled by irrigation. After 2011, the soybean production boosted and the area cultivated with this oilseed equalled the area of rice paddies, i.e., 2 × 10 5 ha. A sharp decrease in δ 13 C from -19 to -24‰ and in δ 15 N from 6 to 2‰ were observed in the sedimentary record, indicating a major shift in the composition of the organic matter after the agricultural intensification. Trace elements Cr, Cu, Ni and Zn showed a high positive correlation with Al and Fe, and enrichment factors near 1, indicating a natural and terrigenous source of these elements and also unpolluted conditions. However, the increase of As after 1990 and the positive correlation with Pb was associated with agricultural practices. All elemental ratios (K/Al, Ti/Al and V/Cr) showed constant pre-disturbance trends and a turning point ca. the 1990s. Microplastics were detected from the beginning of the 1990s and increased towards recent sediments, thus corroborating an anthropogenically impacted scenario. Therefore, the development of the primary sector of the economy exerted clear impacts on the environmental quality of the system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Bioclimatic envelope models have been extensively used to predict the vegetation dynamics in response to climate changes. However, they are prone to the uncertainties arising from General Circulation Models (GCMs), classification algorithms and predictors, with low-resolution results and little detail at the regional level. Novel research has focused on the improvement of these models through a combination of climate and soil predictors to enhance ecological consistency. In this framework, we aimed to apply a joint edaphoclimatic envelope to predict the current and future vegetation distribution in the semiarid region of Brazil, which encompasses several classes of vegetation in response to the significant environmental heterogeneity. We employed a variety of machine learning algorithms and GCMs under RCP 4.5 and 8.5 scenarios of Coupled Model Intercomparison Project Phase 5 (CMIP5), in 1 km resolution. The combination of climate and soil predictors resulted in higher detail at landscape-scale and better distinction of vegetations with overlapping climatic niches. In forecasts, soil predictors imposed a buffer effect on vegetation dynamics as they reduced shifts driven solely by climatic drift. Our results with the edaphoclimatic approach pointed to an expansion of the dry Caatinga vegetation, ranging from an average of 16% to 24% on RCP 4.5 and RCP8.5 scenarios, respectively. The shift in environmental suitability from forest to open and dry vegetation implies a major loss to biodiversity, as well as compromising the provision of ecosystem services important for maintaining the economy and livelihoods of the world's largest semiarid population. Predicting the most susceptible regions to future climate change is the first step in developing strategies to mitigate impacts in these areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The ubiquitous presence of microplastics in the aquatic environment has raised concern about their potential impacts on and risks to the biota. While the presence of microplastics in a marine environment has been well studied, the impact of microplastic contamination in freshwater bodies is understudied. In the present study, baseline data about contamination with microplastics in Lake Guaíba in southern Brazil are presented. The abundance, distribution, and composition of microplastics in the surface of this freshwater body were investigated, and these parameters were correlated with population density, land occupation, wind, and geohydrologic processes. The samples were collected with a manta net (60 μm mesh size). Microplastics were found in all the samples, with an average of 11.9 ± 0.6 to 61.2 ± 6.1 items m -3 , which indicates the widespread contamination of the lake with plastic particles. The most frequent microplastic morphology was the fragment type in the size range of 100 to 250 μm, and the predominant colours were white/transparent and red. Measurement uncertainty of the visual microplastic counts showed that black colour microplastics is more susceptible to be mistaken, which might lead to an underestimation and/or overestimation of the total number of microplastics. Polypropylene and polyethylene together comprised most of the polymer types (98%). Micro-Fourier transform infrared (micro-FTIR) spectroscopy analyses showed that 58% of the analysed polymers were highly oxidised, indicating long residence of this particles in the water. In addition, our data show that the distribution of microplastics is strongly influenced by the geohydrological characteristics of the lake. Therefore, this research may provide information for further investigations of microplastic distribution in Lake Guaíba and can serve as a base to improve the regulations regarding waste management to effectively reduce microplastic pollution in freshwater systems. Additionally, the measurement uncertainty showed that black microplastics are more susceptible to variations in their measurements., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

We assessed the concentrations of microplastics in sediment samples collected in seven sites from Solimões, Negro and Amazon rivers, upstream and downstream the metropolitan region of Manaus. Concentrations ranged from 417 to 8178 particles/kg of dried sediment (microplastics: 0.063-5 mm), and from 0 to 5725 particles/kg of dried sediment (microplastics: 0.063-1 mm). The highest microplastics concentrations were observed in samples from shallow water (water depth of 5-7 m) sites with lower water velocity of the Negro river surrounding Manaus, and the lowest concentration in farthest sample collected in deeper zone (water depth of 34 m) of the Amazon river around 110 km downstream Manaus. The variation of microplastics concentrations within the studied area can be related to hydraulic characteristics defining the erosive-depositional behavior of the sampling sites and their proximity to Manaus. Our results represent the first report to show the ubiquitous presence and widespread distribution of microplastics in sediments from the lower Solimões, lower Negro and upper Amazon rivers., Competing Interests: Declaration of competing interest On behalf of the authors of the manuscript entitled “Microplastics in sediments from Amazon rivers, Brazil”, I declare that we have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The contamination of coastal environments by metallurgical wastes involves multiple biogeochemical processes; accordingly, understanding metal behavior and risk evaluation of contaminated areas, such as Sepetiba Bay (Rio de Janeiro, Brazil), remains challenging. This study coupled Zn isotopic analyses with sequential extractions (BCR) to investigate the mechanisms of Zn transfer between legacy electroplating waste and the main environments in Sepetiba Bay. This metallurgical waste showed a light bulk isotopic signature (δ 66/64 Znbulk JMC  = +0.30 ± 0.01‰, 2 s, n = 3) that was not distinct from the lithogenic geochemical baseline, but was different from signature of mangrove sediment considered as anthropogenic end member (δ 66/64 Zn JMC  = +0.86 ± 0.15‰) in a previous isotopic study in this area. Zn isotopic compositions of sediment samples (ranging from +0.20 to +0.98‰) throughout the bay fit a mixing model involving multiple sources, consistent with previous studies. In the metallurgic zone, the exchangeable/carbonate fraction (ZnF1) exhibited high Zn concentrations (ZnF1 = 9840 μg g -1 ) and a heavy isotopic composition (δ 66/64 ZnF1 JMC  = +1.10 ± 0.01‰). This finding showed that, in some cases, the bulk isotopic signature of waste is not the most relevant criterion for evaluating trace metal dispersion in the environment. Indeed, based on the BCR, it was observed that part of the anthropogenic metallurgical Zn was redistributed from the exchangeable/carbonate fraction in the waste to the surrounding mangrove sediment. Then, this contaminated sediment with heavy δ 66/64 Zn values was exported to other coastal environments. In Sepetiba Bay, contaminated sediments revealed a large concentration of ZnF1 fraction (up to 400 μg g -1 ) with a heavy Zn isotopic signature. This signature also matched the Zn isotopic signature of oysters in Sepetiba Bay reported by other studies; hence, measurement of the isotopic exchangeable/carbonate fraction has important implications for tracing the transfer of anthropogenic Zn to biota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The impacts of climate change on precipitation and the growing demand for water have increased the water risks worldwide. Water scarcity is one of the main challenges of the 21st century, and the assessment of water risks is only possible from spatially distributed records of historical climate and levels of water reservoirs. One potential method to assess water supply is the reconstruction of oxygen isotopes in rainfall. We here investigated the use of tree-ring stable isotopes in urban trees to assess spatial/temporal variation in precipitation and level of water reservoirs. We analyzed the intra-annual variation of δ 13 C and δ 18 O in the tree rings of Tipuana tipu trees from northern and southern Metropolitan Area of São Paulo (MASP), Brazil. While variation in δ 13 C indicates low leaf-level enrichments from evapotranspiration, δ 18 O variation clearly reflects precipitation extremes. Tree-ring δ 18 O was highest during the 2014 drought, associated with the lowest historical reservoir levels in the city. The δ 18 O values from the middle of the tree rings have a strong association with the mid-summer precipitation (r = -0.71), similar to the association between the volume of precipitation and its δ 18 O signature (r = -0.76). These consistent results allowed us to test the association between tree-ring δ 18 O and water-level of the main reservoirs that supply the MASP. We observed a strong association between intra-annual tree-ring δ 18 O and the water-level of reservoirs in the northern and southern MASP (r = -0.94, r = -0.90, respectively). These results point to the potential use of high-resolution tree-ring stable isotopes to put precipitation extremes, and water supply, in a historical perspective assisting public policies related to water risks and climate change. The ability to record precipitation extremes, and previously reported capacity to record air pollution, place Tipuana tipu in a prominent position as a reliable environmental monitor for urban locations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The main land use/land cover changes (LULCC) have been associated with population growth and energy policies in the São Paulo State, Brazil, since 1970. The LULCC can alter the behavior of trace elements in different environmental systems, with the riverbed sediments being the main reservoirs or sinks for trace elements, and thus become a valuable environmental archive on temporal changes. Thus, the main purpose of the study was to apply a multi-tracer analysis to estimate the historical evolution of pollution in riverbed sediment of a subtropical watershed, the lower course of the Piracicaba River, São Paulo, Brazil. 210 Pb measurements done on river sediment core samples allowed estimating a sedimentation rate of 9 mm yr -1 between 1971 and 2001. Zn was the most abundant trace element in the sediment core, followed by Cr, Cu, Ni, Pb, Sc and Cd. The total concentrations of Cd, Cr, Ni, Sc and Pb presented practically no variations in the sediment core, with a continuous excess of ca. 0.27 μg g -1  yr -1 of Cu and of ca. 0.54 μg g -1  yr -1 of Zn between 1971 and 2001. The excess of Cu and Zn was associated with labile fractions, in particular with carbonate bound to Zn and organic matter bound to Cu. The assessment of trace metal pollution indicated that most of the trace elements were of geogenic origin, except for Cu and Zn. According to the sediment quality guidelines used in Brazil, Pb showed no potential toxic effect, Cu, Cr and Zn were intermediate to Threshold Effect Level (TEL) and Probable Effect Level (PEL) and the Cd and Ni concentrations were above the PEL limits. The elemental and isotopic analysis of C and N and the C/N ratio indicated that the anthropogenic origin of POM found in the sediment core is related mainly to domestic sewage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The Pantanal is an important active sedimentary basin in central South America where highly diverse flora and fauna are sustained by seasonal floods. Intense land use in the catchment areas enhanced sediment load and destabilized avulsive river systems in the plains. A well-known avulsion in the Taquari River during the 1980-90s, called "Zé da Costa", has shifted the river mouth and drastically changed the nearby landscapes, making them difficult to map because of the hard access and the large variations in spectral and spatial attributes of raster data like Landsat images. Therefore, we developed a useful method to map and explore landscape changes in "Zé da Costa" avulsion that combines geotagged field pictures, randomly selected high-resolution orbital truths, normalized difference vegetation index, digital elevation models, linear spectral mixture models and Landsat historical imagery in pixel-based and object-oriented supervised classifications. We found that bands in green, red, and near-infrared spectra provide better mapping results with object-oriented algorithms for deriving and studying temporal dry/wet ratio dynamics. The temporal analyses of the dry/wet ratio showed that avulsions in the Taquari River have the potential to change permanently the "Zé da Costa" area into a dry landscape, making it susceptible for land use (deforestation and fire), except areas seasonally inundated by the floods of the Paraguay River. Overall, our method might be also useful for long-term studies of land use and climate change in avulsive rivers in wetlands around the world., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Levels and fluxes of Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), including n-alkanes and petroleum biomarkers (PBMs), were measured in a sedimentary core from a nominated RAMSAR (Guaratuba Bay, Brazil) subtropical estuary experiencing relatively low human impacts, to describe the evolution of anthropogenic activities over the last century. TOC contents varied from 0.80 to 1.25%. No significant correlation between hydrocarbons and TOC with grain size (predominantly sand) was observed. Concentration and flux of total AHs ranged from 65.5 to 195 μg g - 1 and 27.6 to 82.0 μg cm - 2 y - 1 , respectively, with the highest levels found in 1960-1966, when access routes to Guaratuba city were improved. Diagnostic ratios based on AH components showed an apparent change in the sources over time, with biogenic origins prevailing until 1966-1971, followed by subsequent increases in petroleum sources. Petroleum tricyclic terpanes were detected in the core (0.40 to 3.0 μg g - 1 ), suggesting the use of lubricating oil in the bay area. Hopanes were mainly attributed to biological sources. Concentration and flux of total PAHs ranged from 8.65 to 35.9 ng g - 1 and 3.64 to 15.1 ng cm - 2 y - 1 , respectively, with the highest levels found in the top core section, reflecting recently increased human activity, while a peak PAH concentration at approximately 1977-1983 can be assumed to be a delayed signal of increased human occupation as a consequence of the improvement of access roads to the area, which started in the 1960s. Alkylated were the most abundant group of PAHs throughout the core. Despite relatively low concentrations of hydrocarbon deposition over approximately 90 years, this study highlights the influence of human occupation and slight petroleum contamination in this preserved area, mainly in recent core sections., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Transportation infrastructures are directly responsible for killing billions of animals worldwide. Although the understanding about road impacts have recently increased, the impact of railroads on wildlife has received less attention. The current knowledge concerning the impacts of railroads focuses mainly on large mammals although amphibians might be affected. Our study aims to unravel temporal and spatial patterns of Rhinella toad fatalities on a Brazilian Amazonian railroad, to comprehend how toads are killed and to estimate the magnitude of toad fatalities. Data collection was carried out on foot on an 871-km stretch of the Estrada de Ferro Carajás from 2013 to 2017. We identified different potential causes for fatalities: being run over, desiccated or with barotrauma signs. We estimated a surprisingly high carcass persistence probability of about 38 days. After correcting for the bias from carcass detection and removal, we estimated that approximately 10,000 toads are killed per year (≈ 11 fatalities/km/year). A GLM model showed that toads were more likely to be killed in the dry to wet transition. We identified critical zones of fatalities and prioritized them according to their intensity. The highly critical segments encompass >10% of all fatalities although they cover only 1.5% of the railroad. Our study is the first one to address carcass detection and persistence on railroads and to unravel patterns of fatalities of an amphibian species in a tropical climate. A better understanding of the patterns of animal fatality on railroads is of fundamental importance to manage and mitigate this impact., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Large dams built for hydroelectric power generation alter the hydrology of rivers, attenuating the flood pulse downstream of the dam and impacting riparian and floodplain ecosystems. The present work mapped black-water floodplain forests (igapó) downstream of the Balbina Reservoir, which was created between 1983 and 1987 by damming the Uatumã River in the Central Amazon basin. We apply remote sensing methods to detect tree mortality resulting from hydrological changes, based on analysis of 56 ALOS/PALSAR synthetic aperture radar images acquired at different flood levels between 2006 and 2011. Our application of object-based image analysis (OBIA) methods and the random forests supervised classification algorithm yielded an overall accuracy of 87.2%. A total of 9800 km 2 of igapó forests were mapped along the entire river downstream of the dam, but forest mortality was only observed below the first 49 km downstream, after the Morena rapids, along an 80-km river stretch. In total, 12% of the floodplain forest died within this stretch. We also detected that 29% of the remaining living igapó forest may be presently undergoing mortality. Furthermore, this large loss does not include the entirety of lost igapó forests downstream of the dam; areas which are now above current maximum flooding heights are no longer floodable and do not show on our mapping but will likely transition over time to upland forest species composition and dynamics, also characteristic of igapó loss. Our results show that floodplain forests are extremely sensitive to long-term downstream hydrological changes and disturbances resulting from the disruption of the natural flood pulse. Brazilian hydropower regulations should require that Amazon dam operations ensure the simulation of the natural flood-pulse, despite losses in energy production, to preserve the integrity of floodplain forest ecosystems and to mitigate impacts for the riverine populations., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Augmented production and transport of fine sediments resulting from increased human activities are major threats to freshwater ecosystems, including reservoirs and their ecosystem services. To support large scale assessment of the likelihood of soil erosion and reservoir sedimentation, we developed and validated an environmental fragility index (EFI) for the Brazilian neotropical savannah. The EFI was derived from measured geoclimatic controls on sediment production (rainfall, variation of elevation and slope, geology) and anthropogenic pressures (natural cover, road density, distance from roads and urban centers) in 111 catchments upstream of four large hydroelectric reservoirs. We evaluated the effectiveness of the EFI by regressing it against a relative bed stability index (LRBS) that assesses the degree to which stream sites draining into the reservoirs are affected by excess fine sediments. We developed the EFI on 111 of these sites and validated our model on the remaining 37 independent sites. We also compared the effectiveness of the EFI in predicting LRBS with that of a multiple linear regression model (via best-subset procedure) using 7 independent variables. The EFI was significantly correlated with the LRBS, with regression R 2 values of 0.32 and 0.40, respectively, in development and validation sites. Although the EFI and multiple regression explained similar amounts of variability (R 2  = 0.32 vs 0.36), the EFI had a higher F-ratio (51.6 vs 8.5) and better AICc value (333 vs 338). Because the sites were randomly selected and well-distributed across geoclimatic controlling factors, we were able to calculate spatially-explicit EFI values for all hydrologic units within the study area (~38,500 km 2 ). This model-based inference showed that over 65% of those units had high or extreme fragility. This methodology has great potential for application in the management, recovery, and preservation of hydroelectric reservoirs and streams in tropical river basins., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The Pantanal is a large wetland mainly located in Brazil, whose natural resources are important for local, regional and global economies. Many human activities in the region rely on Pantanal's ecosystem services including cattle breeding for beef production, professional and touristic fishing, and contemplative tourism. The conservation of natural resources and ecosystems services provided by the Pantanal wetland must consider strategies for water security. We explored precipitation data from 1926 to 2016 provided by a regional network of rain gauge stations managed by the Brazilian Government. A timeseries obtained by dividing the monthly accumulated-rainfall by the number of rainy days indicated a positive trend of the mean rate of rainy days (mm/day) for the studied period in all seasons. We assessed the linkage of Pantanal's rainfall patterns with large-scale climate data in South America provided by NOAA/ESRL from 1949 to 2016. Analysis of spatiotemporal correlation maps indicated that, in agreement with previous studies, the Amazon biome plays a significant role in controlling summer rainfall in the Pantanal. Based on these spatiotemporal maps, a multi-linear regression model was built to predict the mean rate of summer rainy days in Pantanal by 2100, relative to the 1961-1990 mean reference. We found that the deforestation of the Amazon rainforest has profound implications for water security and the conservation of Pantanal's ecosystem services., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The sources and depositional history of OCPs (organochlorine pesticides), PCBs (polychlorinated biphenyls) and PAHs (polycyclic aromatic hydrocarbons) over the last 100years were determined in two sediment cores collected in the Amazon region. It was possible to distinguish two depositional periods along the cores. The first period occurred before extensive anthropogenic effects were registered in the sediments. During this time interval, the concentrations of all OCPs and PCBs were below the detection limits (DL), and the PAH concentrations were low and essentially constant (58.19-124.28ngg -1 ). The second period starts in the mid-1960s and reflects the increased human influence in the area. The concentrations of OCPs, PCBs, and PAHs increased towards the top of the cores, varying between

-1 ,

-1 and 331 to 2341ngg -1 , respectively. In general, OCP results showed trends corresponding to the production, usage and prohibition periods of POPs in Brazil. Compounds related to wood treatment, such HCHs and chlordanes, were predominant among the OCPs, which may be associated with many sawmills located in this region. The increase in PAH concentration after the 1960s is mainly due to forest fires, caused by the implementation of large-scale cattle ranches, which burned forests to create pastures. The background PAH concentrations before the 1960s are probably related to natural diagenetic processes., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The two-dimensional fractal dimension (D f ) of large aggregates of kaolin (>540μm) during the shear flocculation process for kaolin solution was investigated using non-intrusive in situ image-based acquisition system. Separate experiments were also carried out for three different sized sub-ranges of large aggregates (0.540-1.125mm; 1.125-1.750mm; 1.750-2.375mm). Digital images were taken at a frequency of 10Hz for 10s for each different pairs of gradients of velocity (G f ) of 20 and 60s -1 and flocculation times of 2; 3; 4; 5; 10; 20; 30; 60; 120 and 180min. For the same conditions, particle size distribution (PSD) was also determined. Under the investigated conditions, the lowest G f produced the greatest D f (1.69) at a flocculation time of 30min for the whole range of aggregates. Also, the evolution of the longest length of aggregate (l) and D f with time, showed that the dynamic steady-state was reached at different times for each shear rate and l ranges. However, D f varied for each size sub-range (ca. 1.1 to 1.8). Finally, the behavior of the aggregate structure may be understood by the predominance of different aggregation mechanisms such as cluster-cluster for G f of 60s -1 and particle-cluster for G f of 20s -1 ., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The iron isotope composition was used to investigate dissimilatory iron reduction (DIR) processes in an iron-rich waterlogged paddy soil, the iron uptake strategies of plants and its translocation in the different parts of the rice plant along its growth. Fe concentration and isotope composition (δ 56 Fe) in irrigation water, precipitates from irrigation water, soil, pore water solution at different depths under the surface water, iron plaque on rice roots, rice roots, stems, leaves and grains were measured. Over the 8.5-10cm of the vertical profiles investigated, the iron pore water concentration (0.01 to 24.3mg·l -1 ) and δ 56 Fe (-0.80 to -3.40‰) varied over a large range. The significant linear co-variation between Ln[Fe] and δ 56 Fe suggests an apparent Rayleigh-type behavior of the DIR processes. An average net fractionation factor between the pore water and the soil substrate of Δ 56 Fe≈-1.15‰ was obtained, taking the average of all the δ 56 Fe values weighted by the amount of Fe for each sample. These results provide a robust field study confirmation of the conceptual model of Crosby et al. (2005, 2007) for interpreting the iron isotope fractionation observed during DIR, established from a series of laboratories experiments. In addition, the strong enrichment of heavy Fe isotope measured in the root relative to the soil solution suggest that the iron uptake by roots is more likely supplied by iron from plaque and not from the plant-available iron in the pore water. Opposite to what was previously observed for plants following strategy II for iron uptake from soils, an iron isotope fractionation factor of -0.9‰ was found from the roots to the rice grains, pointing to isotope fractionation during rice plant growth. All these features highlight the insights iron isotope composition provides into the biogeochemical Fe cycling in the soil-water-rice plant systems studied in nature., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Implying large residence times and complex water origins deep coastal aquifers are of particular interest as they are remarkable markers of climate, water use and land use changes. Over the last decades, the Metropolitan Region of Recife (Brazil) went through extensive environmental changes increasing the pressure on water resources and giving rise to numerous environmental consequences on the coastal groundwater systems. We analysed the groundwater of the deep aquifers Cabo and Beberibe that are increasingly exploited. The processes potentially affecting groundwater residence times and flow paths have been studied using a multi-tracer approach (CFCs, SF6, noble gases, 14C, 2H and 18O). The main findings of these investigations show that: (1) Groundwaters of the Cabo and Beberibe aquifers have long residence times and were recharged about 20,000years ago. (2) Within these old groundwaters we can find palaeo-climate evidences from the last glacial period at the tropics with lower temperatures and dryer conditions than the present climate. (3) Recently, the natural slow dynamic of these groundwater systems was significantly affected by mixing processes with contaminated modern groundwater coming from the shallow unconfined Boa Viagem aquifer. (4) The large exploitation of these aquifers leads to a modification of the flow directions and causes the intrusion through palaeo-channels of saline water probably coming from the Capibaribe River and from the last transgression episodes. These observations indicate that the current exploitation of the Cabo and Beberibe aquifers is unsustainable regarding the long renewal times of these groundwater systems as well as their ongoing contamination and salinisation. The groundwater cycle being much slower than the human development rhythm, it is essential to integrate the magnitude and rapidity of anthropogenic impacts on this extremely slow cycle to the water management concepts., (Copyright © 2016. Published by Elsevier B.V.)

Pb concentration and Pb isotopic composition are known to represent powerful tools to investigate the history of Pb pollution in water and sediments. In this paper, we present and discuss the results of a detailed study of sediments deposited in the Paranoá Lake, a 44-year-old artificial reservoir in Brasília, central Brazil. Pb concentration and isotopic composition of the sediments were obtained by ID-TIMS, on three different sample fractions: leachate, residue, and bulk sample. The leachate phase has proven to be most efficient to distinguish between anthropogenic and natural Pb inputs. In the Paranoá lake, important sources of contamination were recognized, producing higher Pb concentrations (max. 37.68 ppm) and significant variations in Pb isotopic composition, relative to the regional geogenic background. Contamination of the sediments due to anthropogenic activity produced less radiogenic Pb isotopic compositions (206Pb/207Pb=1.15-1.17), compared with the regional natural composition (206Pb/207Pb=1.19-1.25). 210Pb analyses along one bore hole which sampled the entire sediment section indicated a sedimentation rate of 8.2+/-1.8 mm/year. The combined use of the 210Pb ages and Pb isotopic compositions of these samples revealed three distinct periods in the lake history: (1) the period of the time formation of the lake in 1959 until ca. 1970 was characterized by the deposition of sediments displaying more radiogenic Pb isotopic signature, (2) the time interval from the start of the process of eutrophication at 1970, until 1995, was characterized by the deposition of sediments having less radiogenic average compositions, and (3) from 1995 until the present represents a period of recovery of water quality, after two sewage treatment stations started to operate.