Retardamento e dispersão hidrodinâmica de cobre, potássio e cloreto em solos residuais do subgrupo Itararé no Estado de São Paulo

Abstract

Resumo: Contaminantes inorgânicos como Cu 2+, K + e Cl -são comuns em resíduos urbanos, industriais e/ou rurais, de forma que o entendimento do comportamento desses íons no solo é importante na gestão de áreas contaminadas. Neste estudo, foram determinados o coeficiente de dispersão hidrodinâmica (Dh) e o fator de retardamento (Rd) dessas espécies químicas em solos residuais arenosos e argilosos do Subgrupo Itararé, coletados nos municípios de Mogi Mirim e Capivari, região leste do estado de São Paulo. Experimentos de laboratório foram feitos com percolação de soluções aquosas de cloretos de potássio e de cobre, em diferentes concentrações, em colunas de solo saturado e regime de fluxo permanente. Curvas de Chegada (BTC) foram geradas a partir dos ensaios, obtendo-se os parâmetros de transporte a partir de ajuste numérico com o programa STANMOD. A análise de mudanças mineralógicas e de precipitados nas colunas de solos foi efetuada por meio de microscopia eletrônica de varredura. O fator de retardamento para os cátions analisados variou entre 9 e 3,9 no solo arenoso e entre 5,7 e 3,5 no solo argiloso; o cloreto apresentou Rd entre 2,9 e 2,4 no solo arenoso e entre 4,6 e 2,5 no solo argiloso. O coeficiente de dispersão hidrodinâmica apresentou pouca variação entre os solos arenoso e argiloso, com valores entre 0,31 cm ), through saturated soil columns at steady-state flux. Breakthrough curves (BTC) were constructed and transport parameters were calculated by fitting theoretical curve to the experimental data using the STANMOD software. Mineralogical alterations and precipitates were examined in soil samples using scanning electronic microscope. The calculated Rd for cations ranged from 9 to 3.9 in sandy soil and from 5.7 to 3.5 in clay-rich soil. For chloride it varied from 4.6 to 2.4. Hydrodynamic dispersion coefficients showed values ranging from 0.02 cm 2 /min to 0.31 cm 2 /min for cations and from 0.01 cm 2 /min e 0.11 cm 2 /min for chloride. The column tests showed that ionic retention was highly influenced by pore volume on soil, and by flux velocity. Mineralogical analysis of the percolated soil samples did not indicate dissolution and precipitation of minerals.

Geoquímica de Terrenos Urbanos Modificados pela Humanidade e Serviços Ecossistêmicos (SE): o Caso de Santa Maria (RS, Brasil)

“…According to Brady and Weill (2015), the pH change of soils alters its flocculation capacity, which in turn influences in the formation and stabilization of aggregates and structures, important physical aspects of the water and gas dynamics from soil. The type of soil structure is fundamental for certain ESs since good structures facilitate the hydraulic and gas conductivity (BASSO and KIANG, 2017). Environments with high values of potential acidity tend to have the modified buffering power, which also affects the formation of aggregates.…”

Field Description and Identification of Diagnostic Qualifiers for Urban Soils in Brazil

“…Annotation of this characteristic is important for the interpretation of soil functions. In a broad sense, sandy or loamy soils increase the propensity of the area to contamination, since they commonly facilitate hydraulic conductivity and contaminant percolation (Basso and Kiang, 2017) that can reach recharge points of aquifers. The same happens when sandstone saprolite layers are exposed by cutting because they compose part of the local aquifer.…”

Reliability analysis as a support tool for projects focusing on non-potable uses of treated wastewater in steel industries

“…Predicting the percolating liquid behavior becomes an important tool since the contaminants present in the solution can be absorbed by plants in the soil and/or precipitates. Moreover, they may also leach into deeper soil layers, even generating environmental impacts and contamination risks (Basso and Kiang, 2017). This knowledge is especially relevant for sandy soils since these, in general, have low concentrations of organic matter and clay minerals that have greater ion exchange capacity than silts and sands.…”