Rapid Prediction of Long-Term Rates of Contaminant Desorption from Soils and Sediments

2001 ◽  
Vol 35 (2) ◽  
pp. 427-433 ◽  
Author(s):  
Martin D. Johnson ◽  
Walter J. Weber
Biochar ◽  
2021 ◽  
Author(s):  
Qian Yang ◽  
Yongjie Wang ◽  
Huan Zhong

AbstractThe transformation of mercury (Hg) into the more toxic and bioaccumulative form methylmercury (MeHg) in soils and sediments can lead to the biomagnification of MeHg through the food chain, which poses ecological and health risks. In the last decade, biochar application, an in situ remediation technique, has been shown to be effective in mitigating the risks from Hg in soils and sediments. However, uncertainties associated with biochar use and its underlying mechanisms remain. Here, we summarize recent studies on the effects and advantages of biochar amendment related to Hg biogeochemistry and its bioavailability in soils and sediments and systematically analyze the progress made in understanding the underlying mechanisms responsible for reductions in Hg bioaccumulation. The existing literature indicates (1) that biochar application decreases the mobility of inorganic Hg in soils and sediments and (2) that biochar can reduce the bioavailability of MeHg and its accumulation in crops but has a complex effect on net MeHg production. In this review, two main mechanisms, a direct mechanism (e.g., Hg-biochar binding) and an indirect mechanism (e.g., biochar-impacted sulfur cycling and thus Hg-soil binding), that explain the reduction in Hg bioavailability by biochar amendment based on the interactions among biochar, soil and Hg under redox conditions are highlighted. Furthermore, the existing problems with the use of biochar to treat Hg-contaminated soils and sediments, such as the appropriate dose and the long-term effectiveness of biochar, are discussed. Further research involving laboratory tests and field applications is necessary to obtain a mechanistic understanding of the role of biochar in reducing Hg bioavailability in diverse soil types under varying redox conditions and to develop completely green and sustainable biochar-based functional materials for mitigating Hg-related health risks.


2015 ◽  
Vol 103 (3) ◽  
Author(s):  
Lindis Skipperud ◽  
Brit Salbu

AbstractTo assess the long term environmental impact of radioactive contamination of ecosystems, information on source terms including radionuclide speciation, mobility and biological uptake is of high importance. The speciation of radionuclides deposited or occurring naturally depends on source term and release scenario characteristics, transport and dispersion mechanisms and ecosystem properties. If mobile species are present, ecosystem transfer is relatively fast, whereas the ecosystem transfer is delayed if radionuclides are present as particles or incorporated in mineral lattices.This paper discusses cases showing important factors influencing the mobility of different radionuclides and metals. As examples can be given:


2015 ◽  
Vol 18 (3) ◽  
pp. 547-563 ◽  
Author(s):  
Umesh Pendharkar ◽  
K.A. Patel ◽  
Sandeep Chaudhary ◽  
A.K. Nagpal

2012 ◽  
Vol 468-471 ◽  
pp. 1850-1855 ◽  
Author(s):  
Meng De Liu ◽  
Ping Ping Fan ◽  
Liu Yan ◽  
Li Bin Du ◽  
Guang Li Hou ◽  
...  

Organic matter in soils and sediments is the key object of biogeochemistry in both terrestrial and marine ecosystems. Whether organic matter is the source or sink of carbon and nutrients can be predicted by its compositions and need continuous, long-term observations of organic matter compositions; therefore, in situ technologies are being investigated to meet the continuous, long-term observations. This study tried to explore a rapid determination of organic matter compositions by ozone chemiluminescence. After the soils or sediments were oxidized by ozone, their chemiluminescence characteristics such as luminescence maximum and time differed significantly. We hypothesized that the luminescence characteristics is controlled by the organic matter compositions. The soils and sediments were separated into extractives, acid soluble fractions (AS), and acid insoluble fractions (AIF), and then the original samples and their compositions were oxidized by ozone. Different organic matter compositions play a different role in the luminescence characteristics: extractives inhibited the luminescence maximum and luminescence time, AS increased the luminescence time and AIF increased the luminescence maximum. Results also showed that AIF can explain most variation of luminescence characteristics, suggesting that the luminescence characteristics are mainly controlled by the concentrations of AIF. Our study suggested that ozonaiton chemiluminescence have a strong potential to rapidly determine the chemistry of soils and sediments.


2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
V. Cappuyns ◽  
E. Slabbinck

Vanadium (V) is a naturally occurring trace element, but total concentrations in soils and sediments are also dependent on the parent material and might be influenced by anthropogenic activities (e.g., steel industry). Despite the fact that threshold values for V in soils and/or sediments exist in various European countries, in Belgium, V is not taken into account when the environmental quality of soils and sediments has to be evaluated, despite the existence of several (diffuse) sources for V. In the first part of the study, the occurrence of V alluvial soils in Belgium was compared with V concentrations in alluvial soils (floodplain soils) across Europe. By analysis of both the Belgian and European data, the relationship between physicochemical soil characteristics and total V concentrations was quantified and some areas polluted with V were detected. A regression equation, in which V concentrations in alluvial soils were expressed as a function of major element composition, was proposed for the Belgian and European data. Additionally, single extractions with CaCl2(0.01 mol L-1) and ammonium-EDTA (0.05 mol L-1) were used to estimate short- and long-term mobility of V in the alluvial soils.


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