1) Spanish Case Study - reduction in contamination through amendment additions and afforestation
The researchers tested and monitored the efectiveness and duration of amendments to reduce contamination in the Guadiamar corridor. They also monitored the effects of trees on soil contamination and carbon sequestration.
|Reduction of contamination by amendment addition|
|Afforestation of contaminated land|
The main target was to increase pH and thereby reduce the availability of cationic trace elements.
The addition of amendments increased pH and their effects lasted with time. Sugar beet lime increased pH by 111%, while biosolid compost increment was 43%.
The available concentration of trace elements showed a strong decrease in the amended plots. In particular, sugar beet lime reduced Cd, Cu and Zn availability by 99%.
The soil pH under trees ranged from 2.6 up to 6.1 and was negatively and exponentially related with availability of trace elements (see example of Cd in the figure below).
- Ceratonia, Fraxinus, and Populus were the tree species most effective at reducing trace elements availability in the soil underneath them.
Enrichment of soil organic carbon was a second target of remediation measures.
- The initial values of soil carbon were very low, around 1%. The addition of biosolid compost doubled soil carbon.
- Soils underneath trees were richer in organic carbon than those in the treeless sites. The highest values were for Ceratonia and Fraxinus.
Madejón, Paula, María T. Domínguez, Engracia Madejón, Francisco Cabrera, Teodoro Marañón, and José M. Murillo. Soil-plant relationships and contamination by trace elements: A review of twenty years of experimentation and monitoring after the Aznalcóllar (SW Spain) mine accident. Science of The Total Environment 625 (2018): 50-63. doi.org/10.1016/j.scitotenv.2017.12.277doi.org/10.1016/j.scitotenv.2017.12.277
M.T. Domínguez,J.M. Alegre, P. Madejón, E. Madejón, P. Burgos, F. Cabrera, T. Marañón, J.M. Murillo (2016) River banks and channels as hotspots of soil pollution after large-scale remediation of a river basin Geoderma Vol 261, 1 January 2016, Pages 133–140 DOI:10.1016/j.geoderma.2015.07.008
María T. Domínguez, , Ignacio M. Pérez-Ramos, José M. Murillo, Teodoro Marañón Facilitating the afforestation of Mediterranean polluted soils by nurse shrubs.Journal of Environmental Management Vol Volume 161, 15 September 2015, Pages 276–286 doi:10.1016/j.jenvman.2015.07.009
María Anaya-Romero,Sameh Kotb Abd-Elmabod, Miriam Muñoz-Rojas, Gianni Castellano, Carlos Juan Ceacero, Susana Alvarez, Miguel Méndez, Diego De la Rosa (2015) Evaluating Soil Threats Under Climate Change Scenarios in the Andalusia Region, Southern Spain. Published in: Land Degradation & Development Volume 26, Issue 5 July 2015 Pages 441–449 http://onlinelibrary.wiley.com/doi/10.1002/ldr.2363/full
2) Romanian Case Study - immobilization of heavy metals using soil amendements
The researchers tested the effectiveness of different soil amendements to reduce the heavy metals mobility in soil and the uptake by plants.
|Factory site, Copsca Mica|
The main results from the experimental field were:
- The highest increase in pH values was for soil treated with Na-bentonite (7.16) compared with the control (5.18).
- In both experimental years, concentrations of available cadmium, lead and zinc decreased significantly with the application of amendments, and they followed the order (highest to lowest): control > natural zeolite > manure > Na-bentonite > dolomite.
- Compared with the control all treatments had statistically significant effects on metals accumulation in biomass but the highest decrease of metal content in the plant was after dolomite application.