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Aim:To verify the vertical distribution of phosphorus in the water and to identify the predominant forms of P in the water column for understand the phosphorus dynamics in tropical semiarid reservoirs during a prolonged drought period. Methods: Two reservoirs from the semiarid region of Rio Grande do Norte were analysed during the period from

Aim To determine the internal P loading potential of semiarid tropical reservoir sediment while verifying the driving factors that affect P release rates. Methods An experiment was performed with water and sediment from the reservoir Boqueirão de Parelhas in Brazil. The effects of three variables on P release were studied: air temperature (region average of 28 °C and 32 °C, simulating an increase of 4 °C), pH (region average of pH 8, more acidic pH 6 and more alkaline pH 10) and oxygen (presence and absence). In addition, P fractionation analysis was performed on the P forms in the sediment. Results It was found that the minimum P release was in an oxic treatment at pH 6 and temperature 28 °C (0.22 mg m-2 d-1 ± 0.13) and the maximum P release in an anoxic treatment at pH 10 and temperature 32 °C (2.1 mg m-2 d-1 ± 0.15). The total P in the sediment was 597 mg kg-1, and the major P form in the sediment was NaOH-rP, the P bound to aluminum, corresponding to 42% of the total P. Conclusion These results allow us to confirm that the sediment of the Boqueirão reservoir is susceptible to the release of P bound to aluminum due to the prevalence of this form in its sediments concomitant with the high temperatures and alkaline pH of the water. This scenario can be aggravated by climate change.

The aim of this study was to evaluate some parameters of water quality of semiarid reservoirs under different uses and occupation of the catchment’s soil. For this, the reservoirs Acauã and Boqueirão, belonging to the Paraíba do Norte river watershed and Middle and Upper course sub catchments, respectively, were studied. For this, water samples were collected in August, September and October 2016. From these samples, total and dissolved phosphorus, nitrate, nitrite, ammonia, chlorophyll, dissolved and suspended solids were analyzed. In addition, images of the Landsat 8 satellite were acquired for the calculation of the Normalized Difference Vegetation Index (NDVI), and for the supervised classification of the use and occupation of the sub catchments. Thus, it was observed that, in general, the Acauã reservoir presented values of phosphorus and nitrogen and solids larger than the Boqueirão reservoir, due to the greater urban area, even though it had a smaller total area of the basin. Both reservoirs presented low vegetation rates and high areas of sparse vegetation and exposed soil, increasing the propensity to soil erosion and the transport of nutrients from the basin to the reservoirs, making water quality worse or impossible.

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Por suas atraentes propriedades, os extratos vegetais da região amazônica tornaram-se matérias-primas fundamentais para a fabricação de produtos cosméticos no mercado mundial, neste contexto incluem-se os extratos de andiroba e mulateiro que possuem excelentes propriedades benéficas à pele. Na criação e desenvolvimento de novos produtos, o planejamento fatorial apresenta-se como uma ferramenta científica eficiente a ser empregada. Desta forma, o objetivo deste trabalho consistiu em realizar o desenvolvimento de um sabonete líquido combinando os extratos vegetais de mulateiro e andiroba, uma vez que não se tem conhecimento de qualquer produto que combine as ações de ambos, com o auxílio de planejamento experimental estatístico. Com esta ferramenta estatística foi possível avaliar a influência dos principais componentes da formulação (lauril, amida, anfótero, extrato vegetal e essência) nas propriedades físico-químicas do produto. Após o desenvolvimento experimental, verificou-se que a proposta de criação de um sabonete líquido com a utilização dos dois extratos é viável, pois não observou-se desiquilíbrio físico-químico promovido pela combinação nas formulações desenvolvidas. Por sua vez, a análise do planejamento fatorial demonstra que o lauril (lauril éter sulfato de sódio) influenciou as seguintes propriedades: pH, condutividade elétrica, viscosidade, densidade e resíduo seco. A amida (dietanolamina de ácido graxo de coco), por sua vez, influencia o pH, viscosidade e resíduo seco. O componente anfótero (anfótero bezaínico) influenciou as respostas para viscosidade, densidade e resíduo seco. Por fim, a essência foi significativa apenas para a resposta de resíduo seco, enquanto o extrato vegetal nas formulações não apresentou significância estatística nas respostas obtidas.

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