ADSORPTION / DESORPTION OF COPPER BY A SANDY SOIL AMENDED WITH VARIOUS RATES OF MANURE, SEWAGE SLUDGE, AND INCINERATED SEWAGE SLUDGE

Authors: Alva, Ashok; Baugh, Tami; PARAMASIVAM, S - SAVANNAH STATE UNIV; SAJWAN, K - SAVANNAH STATE UNIV

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2004
Publication Date: 5/1/2005
Citation: Alva, A.K., Baugh, T.J., Paramasivam, S., Sajwan, K.S. 2005. Adsorption / desorption of copper by a sandy soil amended with various rates of manure, sewage sludge, and incinerated sewage sludge. Journal of Environmental Science and Health. Part B, 40:687-696.

Interpretive Summary: Adsorption and subsequent desorption of copper (Cu) in soils is dependent on various soil properties. Soil amendments such as animal manure, sewage sludge (SS), and incinerated sewage sludge (ISS) are applied to the soil to improve soil physical and chemical properties. Some of the soil amendments contain high levels of plant nutrients in particular micronutrients including copper (Cu) and iron (Fe). Some of the soil amendments can also influence adsorption and/or desorption of metals, including Cu. In this study a Quincy fine sand was amended with varying rates (0 to 160 g/kg) of three soil amendments, i.e. either animal manure, SS, or ISS, and incubated for 100 days at near field capacity soil moisture content (15% weight to weight basis) in a greenhouse. The effect of the above amendments on Cu adsorption was evaluated at various concentrations of Cu in solution (0 to 400 mg/L Cu). In soil with increasing rates of animal manure or SS amendment, the adsorption of Cu increased while the desorption of Cu decreased. The total carbon (C) content in the above amendments varied from 216 to 317 mg/g as compared to 18 mg/g in the ISS. Accordingly, the effect of ISS was less marked on Cu adsorption and desorption as compared to that of either animal manure or SS. This study showed that organically rich soil amendments contributed to increased retention of Cu. Further studies are needed to understand the bioavailability as well as phytotoxicity of Cu that was retained by the soil which was amended with organic sources.

Technical Abstract: Organic amendments are sometimes applied to agricultural soils to improve the physical, chemical, and microbiological properties of the soils. The organic fractions in these soil amendments also influence metal reaction, particularly the adsorption and desorption of metals which, in turn, determine the bioavailability of the metals and hence their phytotoxicities. In this study, a Quincy fine sandy (mixed, mesic, Zeric Torripsamments) soil was treated with 0 to 160 g kg-1 rates of either manure, sewage sludge (SS), or incinerated sewage sludge (ISS) and equilibrated in a greenhouse at near field capacity moisture content for 100 days. Following the incubation period, the soil was dried and adsorption of copper (Cu) was evaluated in a batch equilibration study at either 0, 100, 200, or 400 mg L-1 Cu concentrations in a 0.01M CaCl2 solution. The desorption of adsorbed Cu was evaluated by three successive elutions in 0.01M CaCl2. Copper adsorption increased with an increase in manure rates. At the highest rate of manure addition (160 g kg-1 soil), Cu adsorption was 2-fold greater than that by the unamended soil at all rates of Cu additions. With increasing rates of Cu additions, the adsorption of Cu decreased from 99.4 to 77.6% of Cu applied to the 160 g kg-1 manure amended soil. The desorption of Cu decreased with an increase in rate of manure amendment. Effects of sewage sludge amendments on Cu adsorption were somewhat similar to those as described for manure additions. Likewise, the desorption of Cu was the least at the high rate of SS addition (160 g kg-1), although at the lower rates there was not a clear indication of the rate effects. In contrast to the above two amendments, the ISS amendment had the least effect on Cu adsorption. At the highest rate of ISS amendment, the Cu adsorption was roughly 50% of that at the similar rate of either manure or SS amendments, across all Cu rates.