Cd Speciation In Soil Research Articles

Effects of Sludge and pH Adjustment on Cd Speciation in Soil and Growth and Cd Accumulation in Pak Choi

The objective of this study was to assess the effects of soil pH adjustment and treatment with sludge on plant growth and cadmium (Cd) accumulation in Chinese cabbage (pak choi) grown in Cd-contaminated soils. Soil was artificially spiked to raise its final Cd concentration to 10 mg/kg, adjusted to different pH values, and then supplemented with 5% sludge: either biosolids (BS) from wastewater treatment or sludge from drinking water treatment (WTS). Pak choi seeds were sown and the seedlings potted in the treated soil, then grown in a greenhouse for 45 days. The added Cd was present mainly in the exchangeable fraction and its concentration correlated to Cd accumulation in the roots and shoots. Adjustment of pH and application of sludge affected the Cd concentration in different fractions. Addition of WTS and adjustment to pH 7.0 inhibited growth and Cd accumulation in the pak choi. Addition of BS increased the soil nutrient content and thus enhanced growth and Cd accumulation. If pak choi were the only form of vegetable intake, consumption of pak choi grown in the Cd-spiked soils used in this study would exceed the maximum acceptable intake (60 μg/day) proposed by the World Health Organization.

Research on the Bioavailability of Cd in Ilex kudingcha C. J. Tseng Soil

In Hainan ChengMai Kudingcha Plantation, soil, roots, leaves of Ilex kudingcha C. J. Tseng were obtained from 11 sampling points as “S” and analyzed for Cd and physical and chemical properties of soil, then the concentration and mobility of Cd in tea trees-soil was studied. The speciation of Cd in soil were analyzed by BCR three stage sequential extraction procedure and one-step extraction. Method characterized Bioavailability of Cd in Ilex kudingcha C. J. Tseng were established through the correlation analysis of Cd speciation in soil to Cd content in leaves and the influence of physical and chemical properties of soil to Bioavailability of Cd in soil was discussed. Results of this study showed that: The majority of Cd in soil was transferred to plant as the strong enrichment of Ilex kudingcha C. J. Tseng Trees, The Cd content distribution was: roots > leaves >>rhizosphere soil; According to the correlation analysis, （F1）、（F1+F2） and Cd-HCl extraction were used to characterize the Bioavailability of Cd in soil due to complex soil environment. The order of physical and chemical properties of soil which affected Bioavailability of Cd was: pH>Eh>organic matter>moisture>volatile phenol, that is to say, lower pH, higher Eh, organic matter, moisture, volatile phenol was in favor of reducing the Bioavailability of Cd and Cd accumulation in tea.

Soil Cadmium Mobility as a Consequence of Sewage Sludge Disposal

AbstractAnaerobically digested liquid sewage sludge was applied as a single treatment to a loamy hydromorphic drained soil, characteristic of agricultural soils in the North of France, at a rate of 11 Mg of dry solids ha−1. Total Cd concentrations of drainage waters for both amended and unamended plots were monitored at selected times to follow the mobility of Cd after sludge disposal. The drained groundwater of the plot that exhibited the highest discharge of sludge soluble organic matter (SSOM) exhibited about twice the Cd levels of the control plot during the first few weeks following sludge disposal (average of 3 and 1.5 µg L−1, respectively). Laboratory experiments were conducted to provide estimates of the relative binding strength of Cd‐soil interactions as well as Cd‐SSOM interactions. The behavior of Cd in a mixed sludge‐soil system showed that the addition of sludge soluble organic matter to the soil led to a decrease in the sorption of this cation across the pH range between 5 and 7. The laboratory studies highlighted the role of soluble organic matter in soil Cd speciation, and can be used to speculate on the perturbations induced by high levels of sludge soluble organic matter introduced into a soil.