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Estudo do perfil de macronutrientes em espécies vegetais regadas com águas residuais tratadas
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Resumo(s)
Com o aumento das necessidades hídricas a nível mundial e da escassez de água em algumas regiões,
surge a necessidade de encontrar mecanismos para superar esta carência, nomeadamente no setor
agrícola. Uma das soluções passa pela utilização na rega de águas residuais tratadas (ART) que, devido
à sua composição rica em nutrientes essenciais ao desenvolvimento de culturas, contribui para a
diminuição da fertilização das mesmas. Contudo, devido à recuperação de águas residuais provenientes
da indústria, as ART podem estar contaminadas com metais, tornando-se prejudiciais para o
desenvolvimento de hortícolas e para a saúde pública.
Neste trabalho, estudou-se o efeito da utilização de ART tal como produzida pela ETAR e ART
suplementada com os metais Cd, Cr, Ni e Pb, nas concentrações presentes no Decreto-Lei n.º 236/98,
na germinação e no perfil de macronutrientes de cebolas e de cenouras já desenvolvidas. Tomou-se
como referência a utilização de água da torneira.
Tanto para as cebolas como para as cenouras, não se observaram diferenças significativas na taxa de
germinação e valores de biomassa e comprimento das plântulas entre sementes regadas com os
diferentes tipos de água: água da torneira, ART e ART suplementada com metais.
No estudo da absorção de macronutrientes pelas cebolas, não se observaram diferenças devido à
utilização de diferentes tipos de água. Para as cenouras, verificou-se que a rega com água da torneira
resulta na menor absorção de cloreto, nitrato, fosfato e sulfato. Nas cenouras regadas com ART
suplementada com metais tóxicos observa-se o maior teor de nutrientes. Em ambos os hortícolas não se
observaram diferenças no teor de Pb absorvido pelos vegetais regados com os diferentes tipos de água.
Globalmente, a rega de cebolas e cenouras com ART, mesmo na presença dos metais estudados,
apresenta viabilidade, podendo esta prática contribuir para o reaproveitamento das ART e, no caso das
cenouras, para a diminuição da utilização de fertilizantes.
With the increase in water demand worldwide and the scarcity in some regions, there is a need to find different mechanisms to overcome this shortage, namely in the agricultural sector. One solution involves the use of treated wastewaters (TWW) for irrigation, which, due to its composition, rich of essential nutrients for crop development, contributes to reducing the need for fertilization, However, due to wastewater from industrial sources, TWW may be contaminated with heavy metals, becoming harmful for both crop development and public health. In this study, the effect of using TWW like produced by the wastewater treatment plant and TWW supplemented with Cd, Cr, Ni, and Pb, at the concentrations specified in Decree-Law nr. 236/98, was investigated in the germination and macronutrient profile of developed onions and carrots. The use of tap water was considered as the reference. For both onions and carrots, no significant differences were observed in the germination rate and values of biomass and length of seedlings when irrigated with different types of water: tap water, TWW, and TWW supplemented with metals. In the study of macronutrient absorption by onions, no differences were observed due to the use of different types of water. For carrots, it was found that irrigation with tap water resulted in the lowest absorption of chloride, nitrate, phosphate and sulphate. Carrots irrigated with TWW supplemented with toxic metals exhibited the highest nutrient content. In both vegetables, no differences were observed in the lead content absorbed by plants irrigated with different types of water. Overall, it is possible to irrigate onions and carrots with TWW, even in the presence of the toxic metals Cd, Cr, Ni, and Pb. This practice could contribute to the reuse of TWW and, in the case of carrots, reduce the use of fertilizers.
With the increase in water demand worldwide and the scarcity in some regions, there is a need to find different mechanisms to overcome this shortage, namely in the agricultural sector. One solution involves the use of treated wastewaters (TWW) for irrigation, which, due to its composition, rich of essential nutrients for crop development, contributes to reducing the need for fertilization, However, due to wastewater from industrial sources, TWW may be contaminated with heavy metals, becoming harmful for both crop development and public health. In this study, the effect of using TWW like produced by the wastewater treatment plant and TWW supplemented with Cd, Cr, Ni, and Pb, at the concentrations specified in Decree-Law nr. 236/98, was investigated in the germination and macronutrient profile of developed onions and carrots. The use of tap water was considered as the reference. For both onions and carrots, no significant differences were observed in the germination rate and values of biomass and length of seedlings when irrigated with different types of water: tap water, TWW, and TWW supplemented with metals. In the study of macronutrient absorption by onions, no differences were observed due to the use of different types of water. For carrots, it was found that irrigation with tap water resulted in the lowest absorption of chloride, nitrate, phosphate and sulphate. Carrots irrigated with TWW supplemented with toxic metals exhibited the highest nutrient content. In both vegetables, no differences were observed in the lead content absorbed by plants irrigated with different types of water. Overall, it is possible to irrigate onions and carrots with TWW, even in the presence of the toxic metals Cd, Cr, Ni, and Pb. This practice could contribute to the reuse of TWW and, in the case of carrots, reduce the use of fertilizers.
Descrição
Tese de Mestrado, Química, 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Água residual tratada Macronutrientes Vegetais GFAAS IC Teses de mestrado - 2024