Navegando por Assunto "Phosphorus"

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Acesso aberto (Open Access)
The ceramic artifacts in archaeological black earth (terra preta) from Lower Amazon Region, Brazil: chemistry and geochemical evolution
(Instituto Nacional de Pesquisas da Amazônia, 2004-09) COSTA, Marcondes Lima da; KERN, Dirse Clara; PINTO, Alice Helena Eleotério; SOUZA, Jorge Raimundo da Trindade
This paper carried out a chemical investigation of archaeological ceramic artifacts found in archaeological sites with Black Earth (ABE) in the Lower Amazon Region at Cachoeira-Porteira, State of Pará, Brazil. The ceramic artifacts, mostly of daily use, belong to Konduri culture (from 900 to 400 years BP). They are constituted of SiO2, Al2O3, Fe2O,3, Na2O and P2O5; SiO2 and Al2O3 together add up to 80 % and indicate influence of acid rocks, transformed into clay minerals basically kaolinite. The relative high contents of P2O5 (2.37 % in average) come out as (Al,Fe)-phosphate, an uncommon fact in primitive red ceramics, but found in some roman and egyptian archaeological sites. The contents of the trace elements are similar or below the Earth's crust average. This chemical composition (except P2O5) detaches saprolite material derived acid igneous rocks or sedimentary ones as the main raw material of the ceramics. The contents of K, Na and Ca represent the feldspars and rock fragments possibly introduced into saprolitic groundmass, indicated by mineralogical studies. The presence of cauixi and cariapé as well as quartz sand was confirmed by optical microscope, SEM analyses and by the high silica contents of ceramic fragments. Phosphorus was possibly incorporated into groundmass during cooking of foods, and ABE soil profile formation developed on yellow Latosols. The raw materials and its tempers (cauixi, or cariapé, feldspar, crushed rocks, old ceramic artifacts and quartz fragments) are found close to the sites and therefore and certainly came from them.
Acesso aberto (Open Access)
Distribuição e variabilidade de nutrientes em bacias hidrográficas da Amazônia: uma análise bibliométrica
(Universidade Federal do Pará, 2024-04-19) COELHO, Rosana; MARTINELLI FILHO, José Eduardo; http://lattes.cnpq.br/2080628833884538; https://orcid.org/0000-0001-8445-1332
The excessive presence of nutrients in water triggers a process known as eutrophication, which can affect its quality and lead to ecological imbalance, generating significant environmental impacts. Human activities such as agriculture, livestock farming, mining, and urbanization may be related to the increase of nutrients in the Amazon rivers. Despite the severity of this issue, studies on the increase of nutrients in the Amazon basin are still scarce in the scientific and academic community. The objective of this work was to explore databases like Scopus and Web of Science to synthesize information on nutrient concentrations (N and P) in the Amazon basin. After searching databases using selected keywords and following the three phases of article selection, 40 relevant articles were chosen for the bibliometric review of literature on the topic. The reviewed literature presented results on nitrate, nitrite, ammonium, and phosphate, with nitrate being the most frequently analyzed nutrient in 33 published works, followed by phosphate in 28 studies, ammonium in 26, and nitrite in nine. The study revealed higher average concentrations for nitrate, at 20.28 mg/l, and for phosphate, at 8.03 mg/l, indicating potential areas of interest for future eutrophication research. The mainstem of the Amazon River was the most studied area, appearing in 11 published articles, followed by the Negro, Solimões, and Orinoco rivers, each with seven studies. Data scarcity was identified in areas of the Tapajós, JiParaná, Trombetas, Araguaia, Madre de Dios, Tocantins, Madeira, and Xingu rivers, indicating a lack of information on nutrient concentrations in the sample coverage of collected data. This study provides an important review of nutrient concentrations in the Amazon rivers, emphasizing the need for further research to understand nitrogen and phosphorus concentrations, especially in the main sub-basins of the Amazon (Xingu, Madeira, Tapajós, and Tocantins, Purus), located in deforestation arc areas experiencing greater anthropogenic pressure with few or no studies presented. Understanding these nutrient patterns is essential to protect aquatic ecosystems and promote human health in the Amazon, aiming to guide conservation policies and sustainable management of water resources in the region.
Acesso aberto (Open Access)
Especiação do fósforo em rios urbanos: um estudo de caso dos rios Tucunduba e Tamandaré, Belém/Pará
(Universidade Federal do Pará, 2023-05-24) COIMBRA, Marcus Vinicius Rodrigues; MONTEIRO, Sury de Moura; http://lattes.cnpq.br/4309806566068586; https://orcid.org/0000-0001-9449-7043
Phosphorus (P) is a bioliminating macronutrient that plays an essential role in regulating ecosystem functions and primary productivity in marine and coastal environments. However, when in excessive concentrations, P assumes the role of a pollutant, negatively influencing the ecosystem and causing eutrophication. In Brazil, the problem is maximized in urban centers cut by canals, where there is an intensification of the process of changing the natural conditions of the environment. The speciation of P associated with hydrodynamic processes and the type of urbanization of the environment allows identifying the eutrophication status of these environments. Therefore, the present study seeks to promote understanding of the dynamics of P speciation in two urban rivers, the Tucunduba and Tamandaré rivers, located in the metropolitan region of Belém (Northern Brazil), with the objective of evaluating whether there is variation in P speciation. phosphorus in urban rivers at different time scales. To this end, samples of suspended particulate matter (SPM) were carried out using two different methodologies: the horizontal flow trap (portable traps) and the vertical flow trap (fixed traps). For the extraction of P, the sequential extraction method SEDEX was adopted, which allowed the extraction of five forms: P-Ex, P-Fe, P-Au, PDe and P-Org, in addition to P-Bio. In the Tucunduba river, Total-P concentrations ranged from 20.52 to 100.78 μmol.g-1, with predominance of the P-Fe fraction. In the Tamandaré River, concentrations ranged from 42.36 to 173.88 μmol.g-1 with P-Au predominance. Thus, it was possible to verify that the urban rivers Tucunduba and Tamandaré have high concentrations of P and its species. With these data, it is clear the need to deepen this type of study in these rivers and other urban rivers present in Belém, as well as the need for policies aimed at the recovery and preservation of these, in order to mitigate the problem involving phosphorus and restore the capacity ecosystems of these environments.