scholarly journals Adsorption and Desorption of Cd by Soil Amendment: Mechanisms and Environmental Implications in Field-Soil Remediation

2018 ◽  
Vol 10 (7) ◽  
pp. 2337 ◽  
Author(s):  
Shanshan Li ◽  
Meng Wang ◽  
Zhongqiu Zhao ◽  
Changbao Ma ◽  
Shibao Chen
Keyword(s):  
Contaminated Soils ◽  
Maximum Adsorption Capacity ◽  
Field Soil ◽  
In Situ Immobilization ◽  
Environmental Implications ◽  
Surface Precipitation ◽  
Before And After ◽  
Significant Public Health ◽  
Main Components

In China, 1/5 of the total farmland area is Cd-enriched; the wide occurrence of Cd-contaminated soil in China has already posed significant public health risk and deserves immediate action. In situ immobilization has been regarded as one of the most promising agricultural extension-technologies for remediating low-to-medium levels of heavy metal contaminated land in China. Although extensive research has been conducted to examine the effectiveness of different amendments on remediation of Cd-contaminated soils, the influence of changed soil properties on secondary release of Cd from Cd-amendment to soil is rarely known. The objective of this study was to evaluate the effectiveness of four soil amendments (denoted as Ad1, Ad2, Ad3 and Ad4, their main components being clay mineral, base mineral, humus and biochar, respectively) on reducing Cd availability and increasing Cd stability in soil. The maximum adsorption capacity of test amendments on Cd ranged from 7.47 to 17.67 mg g−1. The characterizations of test amendments before and after Cd loading provided the evidence that surface precipitation and ion exchange were the main reasons for Ad1 and Ad2 to adsorb Cd, and complexation was for Ad3 and Ad4. In addition, there was significant increase in the desorption percentages of Cd from amendments as pH decreased (from 7 to 1) or ion strength increased (from 0 to 0.2 M). Comparatively, Ad3 and Ad4 could be more effective for in situ immobilization of Cd in contaminated soils, due to their high adsorption capacities (12.82 and 17.67 mg g−1, respectively) and low desorption percentages (4.46–6.23%) at pH from 5 to 7 and ion strengths from 0.01 to 0.1 mol L−1. The results obtained in this study could provide a guideline for in-situ remediation of Cd polluted field-soil in China.

In Situ Immobilization of Heavy Metal-Contaminated Soils

Soil Science ◽  
1992 ◽  
Vol 154 (4) ◽  
pp. 338
Author(s):  
G. Czupyrna ◽  
R. D. Levy ◽  
A. I. MacLean ◽  
H. Gold
Keyword(s):  
Heavy Metal ◽  
Contaminated Soils ◽  
In Situ Immobilization

In situ immobilization of metals in contaminated or naturally metal-rich soils

2001 ◽  
Vol 9 (2) ◽  
pp. 81-97 ◽  
Author(s):  
B R Singh ◽  
L Oste
Keyword(s):  
Organic Matter ◽  
Contaminated Soils ◽  
Plant Uptake ◽  
Binding Capacity ◽  
Peat Soil ◽  
Cadmium Concentration ◽  
In Situ Immobilization ◽  
Soil Matrix ◽  
Alum Shale

The chemical behaviour of metals is primarily governed by their retention and release reactions of solute with the soil matrix. Liming increased the soil pH, resulting in increased adsorption of Zn, Cu, and Cd in soils, which in consequence decreased the concentration of easily soluble Cd fraction in the soils and the uptake of this metal by wheat (Triticum aestivum) and carrots (Daucus carota). Metal adsorption also depended on the presence of clay and organic matter, and thus the soils having highest amounts of clay (e.g., alum shale) and (or) organic matter (e.g., peat soil) showed the highest adsorption for these metals. Among the materials (Fe and Mn oxides and aluminosilicates) having high binding capacity for metals, the immobilizing capacity of birnessite (MnO2) was higher than that of other materials. Addition of synthetic zeolites significantly reduced the metal uptake by plants. Application of zeolite to a soil resulted in increased dissolved organic carbon (DOC) concentration in the leachate, which in consequence increased the leaching of Cd and Zn. Addition of beringite (an aluminosilicate) to a Zn-contaminated soil resulted in increased shoot length and leaf area of bean (Phaseolus vulgaris) and a significant reduction in Zn concentration in leaves (from 350 to 146 mg kg-1). Cadmium concentration in ryegrass and the concentrations of diethylenetriaminepentaacetic acid (DTPA)- extractable Cd, Cu, Ni, and Zn in the soil decreased significantly (P < 0.05) with increasing amounts of organic matter (peat soil and cow manure) added to soils. These effects were assumed to be related to immobilization of metals due to formation of insoluble metal--organic complexes and increased cation exchange capacity (CEC). An overview of the results showed that the products tested (lime, Fe/Mn-containing compounds, aluminosilicates, and organic matter products) can reduce the solubility and the plant uptake of metals but their immobilizing capacity is limited (sometimes through their side effects). Key words: aluminosilicates, contaminated soils, in situ immobilization, leaching, metal oxides, organic matter, plant uptake.

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

scholarly journals Cell-free protein synthesis and in situ immobilization of deGFP-MatB in polymer microgels for malonate-to-malonyl CoA conversion

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40588-40596
Author(s):  
Tony Köhler ◽  
Thomas Heida ◽  
Sandra Hoefgen ◽  
Niclas Weigel ◽  
Vito Valiante ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Genetic Information ◽  
In Situ Immobilization ◽  
Bottom Up ◽  
Free Protein ◽  
Malonyl Coa ◽  
Cell Free Protein Synthesis

We describe a bottom-up approach towards functional enzymes utilizing microgels as carriers for genetic information that enable cell-free protein synthesis, in situ immobilization, and utilization of functional deGFP-MatB.

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