Stabilizing effects on a Cd polluted coastal wetland soil using calcium polysulphide

Abstract

In this study, different dosages of calcium polysulphide (CaS x) were used as an amendment to investigate effects on the immobilizing of Cd in a wetland soil by pot experiment. In addition to chemical analysis (pH and bioavailable Cd concentration), changes in soil enzyme activities, microbial carbon utilization capacity, metabolic and community diversity were examined to assess dynamic impacts on soil environmental quality and toxicity of Cd resulting from ameliorant dosing. Soil pH increased immediately upon CaS x amendment compared to the unamended control (CK), and then declined slowly to a level lower than CK. Diethylenetriamine pentaacetic acid (DTPA) extractable Cd concentration was determined to characterize the bioavailability of Cd in the soil. The CaS x dose-dependent effect observed that with increasing CaS x dosage, the immobilizing efficiency decreased. Soil urease and catalase activity assays and Biolog EcoPlate assay indicated that early stage addition of CaS x significantly inhibited soil microbial activities. However, mid and late stage time periods showed the inhibition effects were alleviated, and the microbial activities could be recovered in 1% and 2% CaS x treatments. Moreover, with increasing incubation time, microbial community diversity and richness were significantly recovered in 1% and 2% CaS x treatments compared to the CK. No considerable changes were observed in the 5% CaS x treatment. Conclusively, the 1% CaS x amendment was an efficient and safe dosage for the stabilization of Cd contaminated wetland soil. This study contributes to the development of in situ remediation ameliorants and technologies for heavy metal polluted wetland soils.

Cadmium Immobilization in the Rhizosphere and Plant Cellular Detoxification: Role of Plant-Growth-Promoting Rhizobacteria as a Sustainable Solution

“…Calcium hydroxide stabilizers significantly diminished CaCl 2 -extractable Cd (44–75%) when compared to the control . Calcium polysulfide (CaS x ) at 1% increased soil pH when immediately applied, and diethylenetriaminepentaacetic acid (DTPA)-extractable Cd concentrations were also reduced . Calcium carbonate precipitation has been found to be effective in immobilizing toxic Cd­(II) by precipitation or co-precipitation .…”

“…61 Calcium polysulfide (CaS x ) at 1% increased soil pH when immediately applied, and diethylenetriaminepentaacetic acid (DTPA)-extractable Cd concentrations were also reduced. 62 Calcium carbonate precipitation has been found to be effective in immobilizing toxic Cd(II) by precipitation or co-precipitation. 63 Despite Ca(II)-containing minerals suitable for Cd(II) immobilization behavior; alkalinity, soil productivity, and plant nutritional uptake behavior of plants were negatively affected by Ca(II) and its byproducts in neutral to slightly alkaline agricultural soils (pH 7−7.5).…”

Physiological Diversity of Spitsbergen Soil Microbial Communities Suggests Their Potential as Plant Growth-Promoting Bacteria

“…To compare the catabolic diversity of the microbial community among different soil samples, H, R, E [ 69 ], D [ 70 ], and NUSE [ 71 ] were calculated and shown in Figure 3 . H index was calculated as H = −Σ p i (ln p i ), where p i is the ratio between the relative value of absorption (n i − c) of the substrate and the sum of the entire plate [ 72 ]. R refers to the total number of different carbon sources metabolized by the soil microbial community.…”

Effects of Biochar on the Cd Uptake by Rice and the Cd Fractions in Paddy Soil: A 3-Year Field Experiment

“…However, water regulation alone cannot completely avoid the toxicity of Cd contamination in paddy soil [5]. By adding appropriate soil additives, the content of bioavailable Cd in soil can be effectively controlled, thus reducing the absorption of Cd by plants [6,7]. Therefore, using suitable soil amendments in situ to make the content of Cd in the edible part of crops meet safety standards is a simple and feasible way to remediate contaminated farmland soil [8][9][10].…”