Can anybody provide some possible methods to dispose heavy metal contaminated soil, specifically Cd contaminated soil for Cocoa Cultivation? superficial soil layers (30cm) large land extensions
Not micorremediacion with filamentous fungi or phytoremediation are a very delayed solution and does not improve the problem besides it has no applicability in the large land extensions neither industry of the cacao growers, i need cost benefit relation, Innovative ideas please.
You may go through the report entitled " Heavy metal pollution of soil and a new approach to its remediation: Research Experiences in Japan" by Tomoyuki Makino.. I think it may help you for planning.
Link: www.agnet.org/library.php?func=view&Id=201108094756
This depends on the particle size distribution of the pollutant but if the cadmium is primarily adsorbed onto the smaller perticle size fraction then it may be possible to use a soil washing technique. There is lots of information about this in the literature.
Why is the soil contaminated? If you move the Cd on it will probably create a problem elsewhere. You need to think about secure containment.
There has been a buzz some years ago about using sunflowers to extract heavy metals from contaminated soils. It may a viable way to extract them - further processing may allow recovery of said heavy metals.
Dear Paul, The contamination with cd in this site is of geogenic origin. not anthropogenic.
I used biomass of filamentous fungi isolated from the same soil (Aspergillus sp, Penicillium sp., sporotrichum sp) in greenhouse as an experiment, with good results, but I think it would be very costly and not viable or advisable to spread so much biomass in the soil, it can be counterproductive.
It is a creole cocoa-producing town, exists between 10ppm and 30ppm in soils and is of geogenic origin, in the last years the producers have been harmed by the different standards to commercialize the cocoa bean because the beans contain traces of cadmium between 0.5-1ppm and Currently allowed by World Health Organization are 0.1ppm
I'm not really sure of soil washing technique, due to water pollution, additionally this can alter soil homeostasis and contribute to spread of pathogenic microorganisms.
There seems to be confusion about the term "soil washing". This is an ex situ technique which requires excavation of the soil and separation of the fine from the course fraction (which often contains the sorbed pollutant). The polluted fraction is then dealt with or disposed of. The clean material would then need additions of compost to make it suitable for plant growth. This is not the same as "soil flushing" which indeed can result in pollution of groundwater. But a properly controlled soil washing plant should not result in water pollution. Much of the cost of soil washing technology is in the treatment of wash waters to allow it to be recycled for further washing. However, it will not be cheap and you would have to remove the plants to do it. If you a looking for a cheaper solution or an in situ one which does not need you to remove the plants then you need to think about reducing the uptake. I would start with simply modifying the pH with lime if there is any lattitude between the current pH and the maximum pH tollerated by the plants. However this is not straightforward and may do more harm than good so pilot trials will be needed.
https://www.researchgate.net/publication/299495415_Analysis_of_Zn_Cd_As_Cu_Pb_and_Fe_in_snails_as_bioindicators_and_soil_samples_near_traffic_road_by_ICP-OES?ev=prf_high
Article Analysis of Zn, Cd, As, Cu, Pb, and Fe in snails as bioindic...
There are some plants that are capable of phytoremediating the soil, such as spear grass,(Imperata cylindrica), if planted on such soil, it may take the heavy metals away gradually and gradually
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