Retention of copper, cadmium and zinc in soil and its textural fractions influenced by long‐term field management

Abstract

The present study investigated the impact of long-term soil management on the metal retention capacity of soil. We examined the sorption behaviour of Cu, Cd and Zn in soils and in the various particle-size fractions of these soils, which had been amended with farmyard manure, mineral fertilizers or were fallow for 38 years in a long-term field experiment. The soils investigated contained different amounts and origins of organic matter and differed in soil pH, but the mineral phase showed less response to the different soil managements. Batch adsorption and desorption experiments as well as a sequential fractionation schema, which defines seven geochemical fractions, were used to investigate the retention properties of soil. Sequential extraction was conducted with original as well as with metal-spiked soils. Results showed that amounts of Cu, Cd and Zn retained differed by a factor of more than 3 among the treatments in the longterm field experiment, when a massive concentration of metal was added to soil. An increased sorption on smaller particle size fractions occurred (clay ) silt > fine sand ! coarse sand) due to the larger surface area as well as the greater carbon content in the smaller fractions. Soil sorption behaviour in another long-term field experiment was estimated based on the present particle-sorption data. Differences in the sorption behaviour were related to differences in soil mineralogy and amounts of Fe-and Mn-oxides. Fractionation of the original and the metal-spiked soil underlined the contribution of organic matter to sorption capacity (sequence: Cu ) Cd > Zn). Different organic matter contents and a different soil pH considerably changed the amounts of metals in the defined geochemical fractions. Freshly added Cu, Cd and Zn ions were found mainly in more mobile fractions. In contrast, metals in non-spiked soils appeared in lessmobile fractions reflecting their long-term sorption behaviour.

Dynamics of plant metal uptake and metal changes in whole soil and soil particle fractions during repeated phytoextraction

“…This demonstrates the successful phytoremediation of the metal-contaminated soil by the hyperaccumulator, but for successful phytoextraction of soils highly polluted with Zn it may be necessary to apply other remediation methods together with phytoextraction. Because of their much higher soil cation exchange capacities (CEC) and organic matter contents and the presence of Fe-Mn-Al oxides (Table 2), the finer soil particles adsorbed more Cd and Zn than did the coarse particles (Table 4) and this is consistent with previous studies (Lair et al 2007;Tang et al 2009). Different metal contents and affinities for metals in soil particle fractions would result in different metal availability to the plants (Madrid et al 2008).…”

“…Numerous studies have shown that the fine particle fractions have higher metal concentrations than coarse fractions (e.g. Lair et al 2007;Tang et al 2009), and metals in the clay fraction of urban soils have higher bioavailability than those in other fractions or whole soil (Madrid et al 2008), but fine clay-size fractions also make Cd less bioavailable when Cd enters the soil (Onyatta and Huang 2006). Most studies have focused on static metal distribution and have evaluated bioavailability using chemical agents.…”

Fractionation and mobility of cadmium and zinc in urban vegetable gardens of Kano, Northern Nigeria

“…This fractionation method was developed for aerated soils with very low carbonate concentrations (Lair et al 2007) which are similar to the soils of this study. The method partitions heavy metals into seven operationally defined fractions as follows:…”

The heavy metal availability in long-term polluted soils as affected by EDTA and alfalfa meal treatments

“…In the present study, EDTA was very efficient in releasing heavy metals from the experimental soils CM-A and CM-G, and significantly increased the concentrations of the available metal fractions during the experiment. Despite to higher total heavy metal concentrations, the extractability of readily available metal fractions in the soil CM-G with higher organic carbon content was lower after EDTA treatment possibly due to existence of organo-mineral complexes (Lair et al 2007) and metal-enriched organic particles (Kao et al 2006).…”