Tiago Osório Ferreira

Mineralogia e físico-química dos solos de mangue do rio Iriri no canal de Bertioga (Santos, SP)

The present study evaluated the influence of halomorphic, hydromorphic, and sulfate reduction conditions on sand fraction mineralogy and on the geochemistry of three mangrove soils from the Iriri River estuary. Three representative soil profiles selected from a transect had their geochemical conditions characterized and their effects on the mineralogy of the soils were described. The mineralogical analyses (XRD and EDS) and the physicochemical (Eh and pH) conditions found indicate the occurrence of pyritization in the investigated area. The mineralogical soil assembly is composed of both allochthonous (kaolinite, mica, and smectite) and autochthonous clays (mica, smectite, and pyrite). Based on the XRD and EDS data, it is speculated the possibility of glauconite formation in these soils. The halomorphic and hydromorphic conditions determine the Eh and pH values. Under such environment Fe2+ and SO are found free the soil solution with a tendency to stabilize as pyrite (FeS2), thus favorinf the pyritization process.

Phosphorus geochemistry in a Brazilian semiarid mangrove soil affected by shrimp farm effluents

Wastewater discharge from shrimp farming is one of the main causes of eutrophication in mangrove ecosystems. We investigated the phosphorus (P) geochemistry in mangrove soils affected by shrimp farming effluents by carrying out a seasonal study of two mangrove forests (a control site (CS); a site affected by shrimp farm effluents (SF)). We determined the soil pH, redox potential (Eh), total organic carbon (TOC), total phosphorus (TP), and dissolved P. We also carried out sequential extraction of the P-solid phases. In SF, the effluents affected the soil physicochemical conditions, resulting in lower Eh and higher pH, as well as lower TOC and higher TP than in CS. Organic P forms were dominant in both sites and seasons, although to a lesser extent in SF. The lower TOC in SF was related to the increased microbial activity and organic matter decomposition caused by fertilization. The higher amounts of P oxides in SF suggest that the effluents alter the dominance of iron and sulfate reduction in mangrove soils, generating more reactive Fe that is available for bonding to phosphates. Strong TP losses were recorded in both sites during the dry season, in association with increased amounts of exchangeable and dissolved P. The higher bioavailability of P during the dry season may be attributed to increased mineralization of organic matter and dissolution of Ca-P in response to more oxidizing and acidic conditions. The P loss has significant environmental implications regarding eutrophication and marine productivity.

Phosphorus in seagull colonies and the effect on the habitats. The case of yellow-legged gulls (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain)

During the period 1980-2000, the yellow-legged gull population underwent exponential growth due to an increase in the availability of anthropogenic food resources. The aim of this study was to highlight the effect of the gull colonies on the P soil cycle and the associated effects on coastal ecosystems. Samples of soil, water and faecal material were collected in a colony of yellow-legged gulls (Cíes Islands) and in a control area. Four sampling plots were installed in the study areas, and samples were collected in summer and winter in 1997 and 2011. Sample analysis included soil characterization and determination of the total P content (TP), bioavailable-P and fractionated-P forms in the soils and faecal material. The (31)P NMR technique was also used to determine organic P forms. Clear differences between the gull colony soils and the control soil were observed. The TP was 3 times higher in the gull colony soil, and the bioavailable P was 30 times higher than in the control soil. The P forms present at highest concentrations in the faecal material (P-apatite, P-residual and P-humic acid) were also present at high concentrations in the colony soil. The absence of any seasonal or annual differences in P concentration indicates that the P has remained stable in the soil over time, regardless of the changes in the gull population density. The degree of P saturation indicated that soils are saturated with P due to the low concentration of Fe/Al-hydroxides, which is consistent with a high P concentration in the run-off from the colonies. The P output from the colony soils to coastal waters may cause eutrophication of a nearby lagoon and the disappearance of a Zostera marina seagrass meadow. Similarly, the enrichment of P concentration in dune system of Muxieiro may induce irreversible changes in the plant communities.

Trace metal pyritization variability in response to mangrove soil aerobic and anaerobic oxidation processes

The degree of iron pyritization (DOP) and degree of trace metal pyritization (DTMP) were evaluated in mangrove soil profiles from an estuarine area located in Rio de Janeiro (SE Brazil). The soil pH was negatively correlated with redox potential (Eh) and positively correlated with DOP and DTMP of some elements (Mn, Cu and Pb), suggesting that pyrite oxidation generated acidity and can affect the importance of pyrite as a trace metal-binding phase, mainly in response to spatial variability in tidal flooding. Besides these aerobic oxidation effects, results from a sequential extraction analyses of reactive phases evidenced that Mn oxidized phase consumption in reaction with pyrite can be also important to determine the pyritization of trace elements. Cumulative effects of these aerobic and anaerobic oxidation processes were evidenced as factors affecting the capacity of mangrove soils to act as a sink for trace metals through pyritization processes.

Geochemical speciation and dynamic of copper in tropical semi-arid soils exposed to metal-bearing mine wastes.

The potentially hazardous effects of rock wastes disposed at open pit in three different areas (Pr: Ore processing; Wr: Waste rock and Bd: Border) of an abandoned copper mine were evaluated in this study, with emphasis on acid drainage generation, metal contamination and copper geochemical dynamics in soils. Samples of waste rock were analyzed by Energy dispersive X-ray fluorescence (XRF), scanning electron microscopy with microanalysis (SEM-EDS) and X-ray diffraction (XRD). Soil samples were analyzed to determine the total metal contents (XRF), mineralogy (XRD), pH (H2O and H2O2), organic and inorganic carbon, % of total N, S and P, particle size, and a sequential extraction procedure was used to identify the different copper fractions. As a result of the prevalence of carbonates over sulphides in the wastes, the soil pH remained close to neutral, with absence of acid mine drainage. The geochemical interaction between these mineral phases seems to be the main mechanism to release Cu(2)(+) ions. Total Cu in soils from the Pr area reached 11,180mg.kg(-1), while in Wr and Bd areas the values reached, on average, 4683 and 1086mg.kg(-1), respectively, indicating a very high level of soil contamination. In the Pr and Wr, the Cu was mainly associated with carbonates and amorphous iron oxides. In the Bd areas, the presence of vegetation has influenced the geochemical behavior of copper by increasing the dissolution of carbonates, affecting the buffer capacity of soils against sulphide oxidation, reducing the pH levels and enhancing the proportion of exchangeable and organic bound Cu. The present findings show that the use of plants or organic amendments in mine sites with high concentration of Cu carbonate-containing wastes should be viewed with caution, as the practice may enhance the mobilization of copper to the environment due to an increase in the rate of carbonates dissolution.

Edaphic factors controlling summer (rainy season) greenhouse gas emissions (CO2 and CH4) from semiarid mangrove soils (NE-Brazil)

The soil attributes controlling the CO2, and CH4 emissions were assessed in semiarid mangrove soils (NE-Brazil) under different anthropogenic activities. Soil samples were collected from different mangroves under different anthropogenic impacts, e.g., shrimp farming (Jaguaribe River); urban wastes (Cocó River) and a control site (Timonha River). The sites were characterized according to the sand content; physicochemical parameters (Eh and pH); total organic C; soil C stock (SCS) and equivalent SCS (SCSEQV); total P and N; dissolved organic C (DOC); and the degree of pyritization (DOP). The CO2 and CH4 fluxes from the soils were assessed using static closed chambers. Higher DOC and SCS and the lowest DOP promote greater CO2 emission. The CH4 flux was only observed at Jaguaribe which presented higher DOP, compared to that found in mangroves from humid tropical climates. Semiarid mangrove soils cannot be characterized as important greenhouse gas sources, compared to humid tropical mangroves.

Copper Biogeochemistry in Response to Rhizosphere Soil Processes Under Four Native Plant Species Growing Spontaneously in an Abandoned Mine Site in NE Brazil

We evaluated the biogeochemical processes occurring in the rhizosphere of different native plants growing spontaneously in a copper-contaminated soil in an abandoned mine site in NE Brazil. We also assessed the effects that these processes have on copper mobility and toxicity and discuss the potential use of the plants as pioneer species in restoration programs. For these purposes, we determined chemical (pH, macronutrients, % TOC, and % TIC) and mineralogical (XRD) properties in both rhizosphere and nonrhizosphere soils (bulk soil), and we used the sequential extraction method (SEM) to extract copper from both soils. The study findings show that the plants have greatly altered the physicochemical characteristics of the soil that is directly influenced by their roots. Different plant species appear to act through different processes, thus altering various soil components and affecting the biogeodynamic cycling of essential nutrients and copper. The changes in the physical-chemical characteristics of the rhizosphere affected copper dynamics, mainly manifested as significantly lower concentrations of potentially bioavailable copper, i.e., exchangeable and carbonate-associated copper, in this soil fraction. The concentration of copper associated with noncrystalline Fe oxides was also higher in the rhizosphere, thus enhancing the immobilization and probably minimizing the risks of copper toxicity and mobility. The biogeochemical processes observed in the rhizosphere of the species under study seem to indicate that the plants promote phytostabilization of copper in their rhizosphere zone, and they thus show desirable characteristics for use in phytoremediation programs.

Microrrelevo e a distribuição de frações granulométricas em Cambissolos de origem calcária

A Chapada do Apodi caracteriza-se como importante polo agricola no estado do Ceara. Apesar da homogeneidade de clima, relevo e material de origem, seus solos apresentam grande variabilidade de atributos, muitas vezes em pequenas escalas espaciais, indicando a necessidade de manejos distintos. O presente trabalho teve como objetivo estudar a influencia do microrrelevo na variabilidade espacial das diferentes fracoes granulometricas dos solos da Chapada do Apodi. Para isso, foi realizado levantamento planialtimetrico em uma area de 102 ha, seguido de tradagens para coleta das amostras de solo e determinacao da profundidade efetiva. As amostras foram submetidas a analise granulometrica e os dados foram tratados por meio da estatistica descritiva e da geoestatistica, utilizando-se semivariogramas e mapas de krigagem. Com base nas formas de microrelevo, o local de estudo foi compartimentado em 03 superficies distintas (concava, convexa e retilinea). Por meio dos resultados foi identificada clara influencia do microrrelevo na distribuicao das fracoes granulometricas. Maiores teores de argila e maiores profundidades de solos foram encontrados na superficie concava. Estes resultados sao indicativos de maior acao da pedogenese nos solos desta porcao do terreno em resposta a existencia de fluxos hidricos convergentes. A ocorrencia de maiores teores de areia e solos mais rasos na superficie convexa e mais elevada indica menor acao da pedogenese e maior intensidade do processo de erosao seletiva. O uso da geoestatistica contribuiu para a identificacao de areas com necessidades diferenciadas de manejo, servindo como importante ferramenta para a tomada de decisoes, especialmente relacionadas a irrigacao.

The role of bioturbation by Ucides cordatus crab in the fractionation and bioavailability of trace metals in tropical semiarid mangroves

This study evaluated the burrowing activity of U. cordatus and its effects on Fe, Cu and Zn fractionation, bioavailability and bioaccumulation in a semiarid mangrove area (Ceara state, NE-Brazil). Were analyzed the Eh; pH; grain size and pore water composition; total S and organic C, and the speciation of Fe, Cu and Zn solid-phases in two areas: a densely populated crab and a control site. The burrowing activity and seasonal variation affect the biogeochemical conditions of mangrove soils increasing metals bioavailability and bioaccumulation. The crab burrows favors the entrance of oxygen into the soil, oxidizing the pyrite and forming poorly-crystalline Fe minerals, increasing the risks of biocontamination. Furthermore, the metals content in the hepatopancreas are a good proxy for the evaluation of bioavailable metal forms and, thus, further studies must be conducted in order to evaluate the potential use of U. cordatus as a bioindicator for trace metals contamination.

Soil genesis on hypersaline tidal flats (apicum ecosystem) in a tropical semi-arid estuary (Ceará, Brazil)

Wetland soils, especially those under a semi-arid climate, are among the least studied soils in the tropics. The hypersaline tidal flats on the north-eastern Brazilian coast, locally named apicum, are coastal wetland ecosystems in the peripheral portions of semi-arid estuaries. Despite their great ecological importance, they have been highly impacted by anthropogenic activities. Morphological and analytical data of six soil profiles, representative of the different coastal compartments (mangroves, apicum and coastal tablelands) of the north-eastern Brazilian coast, were examined to better understand the pedogenesis of apicum soils. The hypersaline tidal flat soils were classified as Typic Fluvaquents and Typic Sulfaquents with the following main characteristics: predominance of sand fraction (62-77%); presence of high-activity clays (>24cmolckg -1 clay); clay fraction comprising kaolinite, illite, smectite and an interstratified smectite/illite; exchangeable complex dominated by Na + (ESP � 15%); elevated levels of salinity (electrical conductivity, EC 25-44dSm -1 ); alkaline pH values (7.5-9.5). The sandy texture and quartz-dominated composition of the hypersaline, tidal flat soils indicate a pedogenesis associated with the superficial addition of mineral material. This upbuilding process would have lowered the watertable (relatively to the ground level) and decreased the flooding frequency by the tides, favouring salinisation and solonisation processes at the hypersaline tidal flats. Furthermore, the still-existing hydromorphism would have promoted the maintenance of gleisation and sulfidisation. The presence of pyrite on the hyper-saline tidal flat soils further corroborates the formation of apicum soils from/over buried mangroves.