Cation exchange capacity of an oxisol amended with an effluent from domestic sewage treatment

Abstract

The addition of Na-rich anthropogenic residues to tropical soils has stimulated the scientific community to study the role of sodium in both the soil solution and the exchange complex. In this study, several different methods were used to calculate the concentration of exchangeable and soluble cations and this data was then used to establish correlations between the level of these cations and both the accumulation of various elements and the dry weight of maize grown in a greenhouse under different conditions. In the closed environments of the pots, the most suitable method for calculating the effective cation exchange capacity (ECEC) was the cation exchange capacity calculated by cations removed with barium chloride solution (CEC S ). Then again, the actual cation exchange capacity (CEC A ) should be measured by using Mg adsorption to prevent ionic force from influencing electric charges. A strong positive correlation was obtained between the concentrations of Na in the 1:2 soil:water extracts and the accumulation of Na in the maize plants, indicating saline or double acid extractors are not needed when monitoring the Na concentration only. Key words: exchangeable cations, soil solution, soil with variable charge, treated sewage effluent, maize CAPACIDADE DE TROCA CATIÔNICA DE UM LATOSSOLO TRATADO COM EFLUENTE DE TRATAMENTO DE ESGOTO DOMÉSTICORESUMO: A disposição de resíduos antropogênicos ricos em sódio nos solos tropicais tem despertado o interesse da comunidade científica em estudar a participação deste elemento no complexo de troca, bem como na solução no solo. Objetivou-se neste trabalho estabelecer correlações entre as concentrações de cátions trocáveis e de cátions solúveis, obtidos por diferentes métodos, com o acúmulo de elementos e com a massa seca no milho. O experimento foi conduzido em casa de vegetação, sob diferentes condições. Para experimentos em ambiente fechado (vasos), o método mais indicado para o cálculo da capacidade de troca catiônica efetiva (CTC e ) é a capacidade de troca catiônica calculada a partir dos cátions removidos com solução de cloreto de bário. Ainda, a capacidade de troca catiônica atual deve ser medida ao pH do solo pela adsorção de Mg, para evitar a influência da força iônica nas cargas elétricas. Obteve-se alta correlação positiva entre a concentração de Na no extrato aquoso 1:2 e o acúmulo deste elemento nas plantas, indicando que quando somente o monitoramento do Na for necessário, pode-se desprezar o uso dos extratores salino ou duplo ácido. Palavras-chave: cátions trocáveis, solução no solo, solo com carga variável, efluente de esgoto tratado, milho

Soil Chemistry after Irrigation with Treated Wastewater in Semiarid Climate

“…This increase is related to the high pH of the wastewater (Stewart et al, 1990), the presence of additional HCO 3 − , and changes in N dynamics due to denitrification and/or reduction of NO 3 − , which, in turn, releases OH − (Stewart et al, 1990;Fonseca et al, 2005;Firme, 2007;Gloaguen et al, 2007). However, Speir et al (1999) affirmed that such changes are, in general, of low magnitude, with values typically lower than 1 pH unit, and therefore did not significantly affected the availability of nutrients.…”

“…The monovalency of the Na ion and its large hydration sphere further facilitate dispersion of the clay (Balks et al, 1998), which may then lead to a reduction in hydraulic conductivity (Magesan et al, 1999;Shainberg et al, 2001;Bagarello et al, 2006) and decrease permeability (Meenner et al, 2001), drainage, and soil aeration (McBride, 1989). High concentrations of Na also compete with Ca and alter the ion exchange properties of the soil (Katerji et al, 1996;Fonseca et al, 2005). Some studies regarding the Na-Ca system in soils have been conducted (So and Aylmore, 1993;Bond, 1998), but it is not clear how the Na-Ca system behaves when wastewater is used for irrigation.…”

Electrochemical attributes and availability of nutrients, toxic elements, and heavy metals in tropical soils

“…For instance, the addition of Na-rich anthropogenic residues to tropical soils has stimulated the scientific community to study the role of Na in both, the soil solution and the exchange complex. Fonseca et al (2005) evaluated methods to obtain the concentration of exchangeable and soluble cations in a greenhouse experiment with an Haplustox amended with a secondary-treated sewage effluent, collected from stabilization ponds at the wastewater treatment facility of Lins, São Paulo state, Brazil. The authors observed that, in closed environments of pots, the most suitable method for calculating the effective CEC was the cation exchange capacity calculated by removing cations with a barium chloride solution.…”

Avaliação físico-química de efluente gerado em biodigestor anaeróbio para fins de avaliação de eficiência e aplicação como fertilizante agrícola

“…[13][14][15][16][17][18] Os resíduos de esgotos gerados após tratamento são constituídos essencialmente de água com a presença de minerais e MO suspensa ou dissolvida. Entretanto, em alguns casos, a quantidade relativamente grande de nutrientes, como fosfatos, nitratos e amônio, favorece a eutrofização de corpos de água, comprometendo a qualidade das águas superficiais e limitando a disposição do efluente tratado no local.…”