Effect of Long-Term Use of Sewage Sludge and Lime on the Gross Content and Concentration of Mobile Forms of Heavy Metals in Sandy Loam Sod-Podzolic Soil

Abstract

The long-term dynamics of the gross content and concentration of mobile forms of heavy metals (TM) in the soil of a microfield experiment laid in 1984 on sod-podzolic gleevate sandy loam soil on moraine loam (Vladimir region) is considered. Various large doses of municipal sewage sludge (MSS) and lime (dolomite flour) were introduced as meliorants. Despite the duration of the field experiment, sampling to compare the variants of the experiment on the content of TM in the soil turned out to be insufficiently systematic. Therefore, comparisons were made only on the basis of 3-4 years, and with insufficient comparability of analytical data. As a result, if in some years a significant dependence of the TM content in the soil on the doses of meliorants was obtained, then in the long-term plan, basically we can only talk about trends. From the point of view of contamination of the arable soil layer, it was found that the gross content of Cd, Zn, As was greater than the standard of approximate permissible concentration (APC) in all variants of the experiment (including control); the same is shown for Cu in all variants except control, and for Ni at maximum doses of MSS. Soil contamination in the control appears to be associated with lateral transport. Most of the total Cd and Cu content was extracted with mononormal acids. The content of mobile copper (AAB pH 4.8) (compared with acidsoluble) reacted poorly to the introduction of ameliorants.