Experimental and modeling study on Cr(VI) transfer from soil into surface runoff

Abstract

With the development of modern agriculture, large amount of fertilizer and pesticide outflow from farming land causes great waste and serious pollution to surface water and groundwater, and threatens ecological environment and even human life. In this paper, laboratory experiments are conducted to simulate adsorbed Cr(VI) transfer from soil into runoff. A two-layer in-mixing analytical model is applied to analyze laboratory experimental results. A data assimilation (DA) method via the ensemble Kalman filter (EnKF) is used to update parameters and improve modeling results. In comparison with the experimental data, DA updated modeling results are much better than those without the updating. To make predictions better, the inflation method with a constant inflation factor via DA method was used to compensate the fast decrease of ensemble spread partially related to filter inbreeding. Based on the used rainfall and relevant physical principles, the updated value of the incomplete mixing coefficient c is about 14.0 times of the value of the incomplete mixing coefficient a in experiment 1 and about 7.4 times in experiment 2, while the difference between the flow rate of runoff and infiltration is not so large even after reaching stable infiltration condition. The results indicate the loss of Cr(VI) in soil solute is mainly due to infiltration, rather than surface runoff. With the increase of mixing layer depth, soil adsorption capacity will increase and the loss of soil solute will decrease. The study results provide information for reducing and even preventing the agricultural nonpoint source pollution.

Assessing Chromium Contamination in Red Soil: Monitoring the Migration of Fractions and the Change of Related Microorganisms

“…Moreover, previous experiment and modeling research was concerned with the transfer of Cr (VI) from soil into surface runoff [34,35]. In this study, we calculated relative mobility of Cr fractions: r represented the relative mobility of Cr fractions (mg/kg•d•m), c1 was the concentration of the initial Cr fractions (mg/kg), c2 was the concentration of Cr fractions after migration with the time variation (mg/kg), t was the time of Cr fractions migration (d), and l was the soil depth (m).…”

Determination of Contaminant Transport Parameters for a Local Aquifer by Numerical Modeling of Two Plumes: Trichloroethylene and Hexavalent Chromium

“…In many investigations, dispersivity is estimated through adjustments until the modeled concentrations best approximate observed concentrations [2][3][4][5][6][7][8][9][10][11][12]. An alternative approach to estimating dispersivity is through field and laboratory experiments conducted at different spatial scales [12][13][14][15][16][17][18][19][20][21][22]. However, field tracer tests are often time-consuming and very expensive.…”

Insight into functional microorganisms in wet–dry conversion to alleviate the toxicity of chromium fractions in red soil

“…Unregulated Cr slag dumping and overuse of chemical fertilizers have resulted in the accumulation of Cr in red soil ( Chen et al, 2010 ). Many groups have studied the spatial toxicity variability of Cr fractions under rainfall conditions ( Aceves et al, 2009 ; Tan et al, 2015 ). However, there have been few studies of the migration and occurrence of Cr fractions in red soils in South China under dry and wet conditions ( Han et al, 2001 ; Xu et al, 2013 ), which is essential for accurate environmental toxicity assessments and efficient remediation of soil pollution.…”