Effect of Dissolved Organic Matter from Sludge and Sludge Compost on Soil Copper Sorption

Abstract

Interaction of Cu with dissolved organic matter (DOM) is an important physicochemical process affecting Cu mobility in soils. The aim of this study was to investigate the effects of DOM from anaerobically digested dewatered sludge and sludge compost on the sorption of Cu on an acidic sandy loam and a calcareous clay loam. In the presence of DOM, Cu sorption capacity decreased markedly for both soils, especially for the calcareous soil. The Cu sorption isotherms could be well described by the Freundlich equation (r2 = 0.99), and the binding intensity parameter of soils in the presence of sludge DOM was lower than compost DOM. An increase in DOM concentration significantly reduced the sorption of Cu by both soils. Within the Cu and DOM concentration range studied, the decrease in Cu sorption caused by sludge DOM was consistently greater than that of compost DOM. This might be attributed to the greater amount of hydrophobic fraction of DOM in the compost. Moreover, the reduction of Cu sorption caused by DOM was more obvious in the soil with higher pH. In addition, the sorption of Cu increased with an increase in pH for both soils without the addition of DOM, while Cu sorption in the presence of DOM was unexpectedly decreased with an increase in pH at a pH >6.8. This implied that DOM produced by sludge or other C-enriched organic wastes heavily applied on calcareous soils might facilitate the leaching loss of Cu because of the formation of soluble DOM-metal complexes.

Effects of three different biochars on aggregate stability, organic carbon mobility and micronutrient bioavailability

“…Dissolved organic carbon is the most mobile fraction of organic ligands that exist in soils and may assist in the transfer of metals through soil as organic complexes (Cao et al, 2003); greater concentrations of aromatic and phenolic compounds will produce soluble metal-organic complexes (Tapia et al, 2010;Vaca-Paulín et al, 2006). Copper mobility has been shown to increase with increasing DOC concentration and pH (Temminghof et al, 1997;Strobel et al, 2001), whilst Zhou and Wong (2001) reported that application of soluble organic carbon from sewage sludge reduced Cu sorption in soil due to development of soluble complexes, with the effect being greater at higher pH. There were no significant differences in pore water Zn and Mn concentrations compared to controls (Figs S4 and S5).…”

Citric acid and ethylene diamine tetra-acetic acid as effective washing agents to treat sewage sludge for agricultural reuse

“…When CA causes the sludge to form crumbs and clay, i.e., changing the sludge structure, organic matter is increased accordingly. In regards to EDTA, the decrease of organic matter can be mainly attributed to leaching (Zhou and Wong, 2001). …”

Phytoextraction of lead by Helianthus annuus: effect of mobilising agent application time

“…It was reported that dissolved organic matter from cattle-manure slurry and sludge and sludge compost increases the solubility of cadmium, copper and zinc soil (Del Castilho et al 1993, Zhou andWong 2001). The results showed that soil available Pb was higher in SME treatments at T3 and T4.Therefore the positive effects of SME on Pb uptake by Helianthus annuus is the result of plant growth improvement and soil Pb solubilization.…”