Distribution and availability of copper, iron, manganese and zinc in the archaeological black earth profile from the Amazon region

Os solos de terra preta arqueológica são ricos em matéria orgânica, contêm fragmentos cerâmicos e artefatos líticos e apresentam nutrientes em concentrações mais elevadas do que outros tipos de solos. Com o intuito de contribuir com informações sobre concentrações de micronutrientes disponíveis em solos de terra preta, foram avaliadas através de extrações químicas sequenciais, a distribuição e disponibilidade de Cu, Fe, Mn e Zn em um perfil de terra preta arqueológica no município de Juruti, estado do Pará. As maiores concentrações de Cu, Fe, Mn e Zn no perfil são encontradas na fração residual. Este estudo mostrou que ferro, manganês e zinco são preferencialmente disponíveis a partir das frações, associados aos óxidos de Fe-Mn, variando de 1265,39 a 1818,12 mg kg^-1, 0,83 a 48,51 mg kg^-1 e 1,92 a 12,05 mg kg^-1, respectivamente, e o cobre a partir da matéria orgânica, variando de 0,13 a 0,45 mg kg^-1.

Cytogenetic damage related to low levels of methyl mercury contamination in the Brazilian Amazon

The mercury rejected in the water system, from mining operations and lixiviation of soils after deforestation, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin. The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within a population living on the banks of the Tapajós River with respect to methylmercury (MeHg) contamination, using hair mercury as a biological indicator of exposure. Our investigation shows a clear relation between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50 micrograms/gram, the level at which initial clinical signs and symptoms of mercury poisoning occur. The first apparent biological effect with increasing MeHg hair level was the impairment of lymphocyte proliferation measured as mitotic index (MI). The relation between mercury concentration in hair and MI suggests that this parameter, an indicator of changes in lymphocytes and their ability to respond to culture conditions, may be an early marker of cytotoxicity and genotoxicity in humans and should be taken into account in the preliminary evaluation of the risks to populations exposed in vivo. This is the first report showing clear cytotoxic effects of long-term exposure to MeHg. Although the results strongly suggest that, under the conditions examined here, MeHg is both a spindle poison and a clastogen, the biological significance of these observations are as yet unknown. A long-term follow-up of these subjects should be undertaken.

Seasonal variability of a conditional stability constant and the characterization of sedimentary humic substances from typical agricultural and urban areas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estratégias de propagação de barueiro (Dipteryx alata Vog.) e jatobazeiro do cerrado (Hymenaea stigonocarpa MART)

Pós-graduação em Agronomia - FEIS

The cone loading test to estimate deformability moduli of a tropical soil

The Cone Loading Test (CLT) consists of the execution of a load test on the piezocone probe in conjunction with the CPT test. The CLT yields the modulus ECLT, a parameter that can be used in the estimative of foundation settlement. It is also presented here the interpretation and the process to determine ECLT values from the stress-displacement curves obtained from cone loading tests. Several CLT tests were conducted at the experimental research site of São Paulo State University, Bauru-SP-Brazil. The geotechnical profile at the studied site is a brown to bright red slightly clayey fine sand, a tropical soil common to this region which is lateritic, unsaturated and collapsible. The results of CLT tests satisfactorily represent the behavior of the investigated soil. The penetrometric modulus ECLT for each depth was calculated considering the elastic behavior in the initial linear segment of the soil stress-strain curve. The ECLT moduli obtained for the various tests were compared to moduli obtained from PMT and DMT test results performed at same studied site. The shear modulus degradation curves obtained from the CLT tests are also presented. The comparison to PMT and DMT results indicates the CLT test is a viable complementary test to the CPT in the quest for better understanding stress-strain behavior of soils. Further, the CLT test provides a graphic visualization of the degradation of the shear modulus with increasing levels of strain. As a hybrid geotechnical test, CPT+CLT can be valuable in the investigation of non-conventional collapsible soils, whose literature lack reference parameters for the prediction of settlement in the design of foundations.

Go/N ratio in tropical soils from Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Emissão de gases de efeito estufa e estoque de carbono no solo em função do manejo e correção de acidez

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of Botanical Composition, Soil Carbon Content, and Root Distribution of Subirrigated Meadows in The Nebraska Sandhills

Characterizing vegetation composition, carbon/nitrogen (C/N) content of soils, and root-mass distribution is critical to understanding carbon sequestration potential of subirrigated meadows in the Nebraska Sandhills. Five subirrigated meadows dominated by cool-season (C3) graminoids and five meadows dominated by warm-season (C4) grasses were selected throughout the Nebraska Sandhills. Vegetation, soil carbon and nitrogen, and root-mass density distribution were sampled in each meadow. Meadows dominated by C3 vegetation had 12% greater (P < 0.1) yields than meadows dominated by C4 vegetation. Total root-mass density was 30% greater (P < 0.1) in C4-dominated meadows than C3-dominated meadows. Total carbon and nitrogen content was 65% and 53% greater (P < 0.1), respectively, in the A horizon of C3-dominated meadows, but was 43% and 52% greater (P < 0.1), respectively, in the C horizon of C4-dominated meadows. Although meadows dominated by C3 vegetation had more carbon in the soil profile, much of the carbon in C3-dominated meadows appeared to be recalcitrant C4 carbon from historic vegetation.

The sustainability of ethanol production from sugarcane

The rapid expansion of ethanol production from sugarcane in Brazil has raised a number of questions regarding its negative consequences and sustainability. Positive impacts are the elimination of lead compounds from gasoline and the reduction of noxious emissions. There is also the reduction of CO2 emissions, since sugarcane ethanol requires only a small amount of fossil fuels for its production, being thus a renewable fuel. These positive impacts are particularly noticeable in the air quality improvement of metropolitan areas but also in rural areas where mechanized harvesting of green cane is being introduced, eliminating the burning of sugarcane. Negative impacts such as future large-scale ethanol production from sugarcane might lead to the destruction or damage of high-biodiversity areas, deforestation, degradation or damaging of soils through the use of chemicals and soil decarbonization, water resources contamination or depletion, competition between food and fuel production decreasing food security and a worsening of labor conditions on the fields. These questions are discussed here, with the purpose of clarifying the sustainability aspects of ethanol production from sugarcane mainly in Sao Paulo State, where more than 60% of Brazil`s sugarcane plantations are located and are responsible for 62% of ethanol production. (c) 2008 Elsevier Ltd. All rights reserved.

Biogenic calcium phosphate transformation in soils over millennial time scales

Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600-1,000 years, beta-tricalcium phosphate increased to 16% of total P after 900-1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58-65%) across the time scale studied. Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.

Soil profile, relief features and their relation to structure and distribution of Brazilian Atlantic rain forest trees

In tropical forests, the environmental heterogeneity can provide niche partitioning at local scales and determine the diversity and plant species distribution. Thus, this study aimed to investigate the variations of tree species structure and distribution in response to relief and soil profile features in a portion of the largest remnant of Brazilian Atlantic rain forest. All trees >= 5 cm diameter at breast height were recorded in two 0.99 ha plots. Topographic survey and a soil characterization were accomplished in both plots. Topsoil samples (0-20 cm) were taken from 88 quadrats and analyzed for chemical and particle size properties. Differences for both diversity and tree density were identified among three kinds of soils. A canonical correspondence analysis (CCA) indicated that the specific abundance varied among the three kinds of soils mapped: a shallow Udept - Orthent / Aquent gradient, probably due to differences in soil drainage. Nutrient content was less likely to affect tree species composition and distribution than relief, pH, Al3+, and soil texture. Some species were randomly distributed and did not show restriction to relief and soil properties. However, preferences in niche occupation detected in this study, derived from the catenary environments found, rise up as an important explanation for the high tree species diversity in tropical forests.

Sensitivity of Eisenia andrei (Annelida, Oligochaeta) to a commercial formulation of abamectin in avoidance tests with artificial substrate and natural soil under tropical conditions

Obtaining ecotoxicological data on pesticides in tropical regions is imperative for performing more realistic risk analysis, and avoidance tests have been proposed as a useful, fast and cost-effective tool. Therefore, the present study aimed to evaluate the avoidance behavior of Eisenia andrei to a formulated product, Vertimec(A (R)) 18 EC (a.i abamectin), in tests performed on a reference tropical artificial soil (TAS), to derive ecotoxicological data on tropical conditions, and a natural soil (NS), simulating crop field conditions. In TAS tests an adaptation of the substrate recommended by OECD and ISO protocols was used, with residues of coconut fiber as a source of organic matter. Concentrations of the pesticide on TAS test ranged from 0 to 7 mg abamectin/kg (dry weight-d.w.). In NS tests, earthworms were exposed to samples of soils sprayed in situ with: 0.9 L of Vertimec(A (R)) 18 EC/ha (RD); twice as much this dosage (2RD); and distilled water (Control), respectively, and to 2RD: control dilutions (12.5, 25, 50, 75%). All tests were performed under 25 +/- A 2A degrees C, to simulate tropical conditions, and a 12hL:12hD photoperiod. The organisms avoided contaminated TAS for an EC50,48h = 3.918 mg/kg soil d.w., LOEC = 1.75 mg/kg soil d.w. and NOEC = 0.85 mg/kg soil d.w. No significant avoidance response occurred for any NS test. Abamectin concentrations in NS were rather lower than EC50, 48h and LOEC determined in TAS tests. The results obtained contribute to overcome a lack of ecotoxicological data on pesticides under tropical conditions, but more tests with different soil invertebrates are needed to improve pesticides risk analysis.

Functional diversity of bacterial genes associated with aromatic hydrocarbon degradation in anthropogenic dark earth of Amazonia

The objective of this work was to evaluate the catabolic gene diversity for the bacterial degradation of aromatic hydrocarbons in anthropogenic dark earth of Amazonia (ADE) and their biochar (BC). Functional diversity analyses in ADE soils can provide information on how adaptive microorganisms may influence the fertility of soils and what is their involvement in biogeochemical cycles. For this, clone libraries containing the gene encoding for the alpha subunit of aromatic ring-hydroxylating dioxygenases (alpha-A RH D bacterial gene) were constructed, totaling 800 clones. These libraries were prepared from samples of an ADE soil under two different land uses, located at the Caldeirao Experimental Station secondary forest (SF) and agriculture (AG)-, and the biochar (SF_BC and AG_BC, respectively). Heterogeneity estimates indicated greater diversity in BC libraries; and Venn diagrams showed more unique operational protein clusters (OPC) in the SF_BC library than the ADE soil, which indicates that specific metabolic processes may occur in biochar. Phylogenetic analysis showed unidentified dioxygenases in ADE soils. Libraries containing functional gene encoding for the alpha subunit of the aromatic ring-hydroxylating dioxygenases (ARHD) gene from biochar show higher diversity indices than those of ADE under secondary forest and agriculture.

Land Use, Freshwater Flows and Ecosystem Services in an Era of Global Change

The purpose of this thesis is to analyse interactions between freshwater flows, terrestrial ecosystems and human well-being. Freshwater management and policy has mainly focused on the liquid water part (surface and ground water run off) of the hydrological cycle including aquatic ecosystems. Although of great significance, this thesis shows that such a focus will not be sufficient for coping with freshwater related social-ecological vulnerability. The thesis illustrates that the terrestrial component of the hydrological cycle, reflected in vapour flows (or evapotranspiration), serves multiple functions in the human life-support system. A broader understanding of the interactions between terrestrial systems and freshwater flows is particularly important in light of present widespread land cover change in terrestrial ecosystems. The water vapour flows from continental ecosystems were quantified at a global scale in Paper I of the thesis. It was estimated that in order to sustain the majority of global terrestrial ecosystem services on which humanity depends, an annual water vapour flow of 63 000 km3/yr is needed, including 6800 km3/yr for crop production. In comparison, the annual human withdrawal of liquid water amounts to roughly 4000 km3/yr. A potential conflict between freshwater for future food production and for terrestrial ecosystem services was identified. Human redistribution of water vapour flows as a consequence of long-term land cover change was addressed at both continental (Australia) (Paper II) and global scales (Paper III). It was estimated that the annual vapour flow had decreased by 10% in Australia during the last 200 years. This is due to a decrease in woody vegetation for agricultural production. The reduction in vapour flows has caused severe problems with salinity of soils and rivers. The human-induced alteration of vapour flows was estimated at more than 15 times the volume of human-induced change in liquid water (Paper II).

Centrifuge Modeling of Sandy Slopes

Slope failure occurs in many areas throughout the world and it becomes an important problem when it interferes with human activity, in which disasters provoke loss of life and property damage. In this research we investigate the slope failure through the centrifuge modeling, where a reduced-scale model, N times smaller than the full-scale (prototype), is used whereas the acceleration is increased by N times (compared with the gravity acceleration) to preserve the stress and the strain behavior. The aims of this research “Centrifuge modeling of sandy slopes” are in extreme synthesis: 1) test the reliability of the centrifuge modeling as a tool to investigate the behavior of a sandy slope failure; 2) understand how the failure mechanism is affected by changing the slope angle and obtain useful information for the design. In order to achieve this scope we arranged the work as follows: Chapter one: centrifuge modeling of slope failure. In this chapter we provide a general view about the context in which we are working on. Basically we explain what is a slope failure, how it happens and which are the tools available to investigate this phenomenon. Afterwards we introduce the technology used to study this topic, that is the geotechnical centrifuge. Chapter two: testing apparatus. In the first section of this chapter we describe all the procedures and facilities used to perform a test in the centrifuge. Then we explain the characteristics of the soil (Nevada sand), like the dry unit weight, water content, relative density, and its strength parameters (c,φ), which have been calculated in laboratory through the triaxial test. Chapter three: centrifuge tests. In this part of the document are presented all the results from the tests done in centrifuge. When we talk about results we refer to the acceleration at failure for each model tested and its failure surface. In our case study we tested models with the same soil and geometric characteristics but different angles. The angles tested in this research were: 60°, 75° and 90°. Chapter four: slope stability analysis. We introduce the features and the concept of the software: ReSSA (2.0). This software allows us to calculate the theoretical failure surfaces of the prototypes. Then we show in this section the comparisons between the experimental failure surfaces of the prototype, traced in the laboratory, and the one calculated by the software. Chapter five: conclusion. The conclusion of the research presents the results obtained in relation to the two main aims, mentioned above.