Why Soil Monitoring?
Plants and animals throughout the Galapagos get part of their nutrition from the soil. Soil pollution therefore can harm the ecosystem at all levels. Soil pollutants can be classified into two types, macropollutants, which are introduced into the soil in abundant amounts, and micropollutants, which are introduced in small quantities (Mirsal, 2004). Nitrogen fertilizers, for example, belong to the macropollutants, and they are considered a serious environmental problem. These fertilizers seep into groundwater, which enhance eutrophication. The micropollutants include heavy metals, a term applied for the group of metals and metalloids with an atomic density greater than 6 g/cm3. Examples include copper, iron, and zinc, which are essential for plant metabolism and are required by animals.
Of city sources contributing to soil pollution, waste and sewage sludge disposal play a central role. Municipal waste disposal by landfills and incineration may lead to unusually high concentrations of heavy metals in the soil such as cadmium, cobalt, chromium, copper, lead, nickel, mercury, tin, and zinc, either directly or by ash from incinerating plants, such as the one on San Cristóbal (Mirsal, 2004).
We propose that most soil sampling will take place in agricultural regions, around particularly endangered species, close to waste treatment facilities, and near or in retired landfill sites.
How and What?
An integrated soil monitoring plan is comprised of site characterization, methodology development and data collection, interpretation, and reporting. Geomorphic characteristics of many of the proposed collection sites need to be obtained before monitoring can be done. Already existent maps of the sampling areas need to be gathered, including base maps detailing the morphology of the site and runoff conditions, geology and soil maps characterizing soil and rock types which can prove useful in determining the potential for flow of pollutants near the site, and hydrologic maps showing the direction of groundwater flow. If the current information is incomplete, then new maps must be developed.
After site characterization, sampling areas will be mostly randomly selected within the sites. About half a dozen soil samples should be taken per effort in the landfill and incineration plant areas. Field sampling should be done at least once per month in these areas. Agricultural soil sampling can be done once every two weeks within every agricultural region run by a particular farmer. Soil collection in areas around specific endangered species will vary.
Samples at all sites can be taken at depths of less than one meter (UN/ECE ICP Forest, 1994). Simple soil augers can be employed for this purpose if the soil is loamy. For more stony soils, light power augers should suffice. In the sample sites, the heavy metal concentrations mentioned above will be measured, along with microbes (Keller and Desaules, 2002). A discussion of microbes follows below.
Of particular interest to our design is the capacity of the larger monitoring system to provide a real-time feedback loop capable of assessing the relative success of changes in the environment due to changes in village structure or land use as proposed through the biopreserve committee.
As part of this process, farmers will need to learn how to draw samples from their fields to run soil content analysis for comparison over time. By asking them to monitor and record microbial activity, pesticide levels, and mineral content, they will be given a very real connection to the workings of a lab. This in turn will foster a sense that they are active members of the educated and important research community while also providing invaluable information about the land on which their crops are being produced. As the farmers will already be in their fields, asking them to draw and record samples will not add any excess pressure to the spaces in which they work. To ensure accuracy while these individuals learn to take these samples, we suggest that there be instructors collecting and analyzing samples from the same sites as the farmers until results correlate consistently. For the purpose of this proposal, and as is fully articulated in the proposal on soil monitoring, sources of particular interest include all spring heads that originate in a farmer’s field and all points where freshwater crosses the boundary between farm and park lands. Of course standard soil samples taken within the boundary of each field would also be necessary for use in agricultural planning. Where the farmers do a good job working their fields, these samples will provide them with a form of hard evidence that will do much to inspire their further interest.
Biological diversity along with the health of soil are key components of overall ecological resilience. Galapagos microbes possess the potential to provide a wealth of information about the ecological foundation of the islands. They also provide a relatively non-invasive way to understand the human impact on the ecosystem and its capacity to respond to external challenges. If the flora of the islands is healthy, the fauna will also be healthy. For this first link in the chain to be true, certain soil microbes must be present and abundant. When this is true, biota tends to fight off disease more readily and are significantly less hospitable to infestation by pests, particularly those that are introduced on the islands. As a result, establishing a baseline to understand what type of soil ecology best suits endangered endemic species is a key factor in helping to ensure both its survival and restoration.
Within a historical context, monitoring and cataloguing microbes in the Galapagos also provide an opportunity to further expand upon the island’s contribution to evolutionary thought. As a nearly un-studied source of information about soil biology in newly formed land masses, microbes provide an opportunity to expand the ideas and experimental basis for endosymbiosis (symbiogenesis).
Most soil sampling will take place in agricultural regions, around particularly sensitive species, close to waste treatment facilities, and near or in retired landfill sites. Of theses, agricultural zones and areas around threatened species present the most immediate opportunity to benefit from the information about soil microbiology. Information gained in the agricultural zones can be used to determine the effects of pesticides on soil biota, the subsequent effect of shifting to organic and biodynamic processes, and the impact of both these on the initial soil composition of the humid regions in the Galapagos. Similarly, information gained from the soil around threatened species can be used both as a control to eliminate potential factors contributing to their decline and as a way to inform restoration practices in the highlands as agricultural land is returned to its initial ecological standing.
Due to financial and technical constraints, the optimal means of qualifying soil health by establishing a baseline case for microbial activity are the magnetic bead cell separation techniques (Edwards, 2004). In magnetic-particle based separations, haptens designed to recognize a specific cell wall are set onto these magnetic particles and then exposed to extremely small quantities of a soil sample (Edwards, 2004). Once the hapten bonds with the cell, a magnetic field is generated in the space containing the sample and the particular microbe being studied is removed. From this point, information can either be gathered about the structure of the individual microbes or entire communities (Robertson, Coleman, Bledsoe, & Sollins, 1999). Other more expensive and technically intensive methods used to monitor microbial communities exist, ranging from cytometric cell sorting, optical trapping, micro-manipulation, dielectrophores, ultrasound sedimentation, sedimentation field-flow fractionation, and elutriation (Edwards, 1999).
Microbes and Regeneration
To restore some land currently under agricultural cultivation to its primordial state, understanding soil biology becomes a key question. As mentioned above, each species prefers a specific growing environment. Thus, where land is set to be restored, an understanding of initial growing conditions becomes essential to remediating impact and returning the local ecology to its original state.
Monitoring microbes and heavy metal levels in soils, particularly in the agricultural regions, provides a low cost, high return method of assessing ecological health and the relative success of changes due to shifts in land use. Using facilities and current social patterns, soil pollution management and understanding provides a means of strengthening both community and economy.
- Bloem, J., D. van Mullem, & P. Bolhuis (1995). Fully automatic determination of soil bacterium numbers, cell volumes, and frequencies of dividing cells by confocal laser scanning microscopy and image analysis. Applied and Environmental Microbiology, 61, 926-936.
- Edwards, Clive (ed.) (1999). Environmental Monitoring of Bacteria. Humana Press: Totowa, NJ.
- Edwards, Clive (2004). Methods in Biotechnology, vol. 12. Humana Press: Totowa, NJ.
- Keller, A, Desaules, A. (2002) The Swiss Soil Monitoring Network: Regular Measurements of Heavy Metals in Soil and Field Balances. Retrieved November 30, 2004, from http://www.ktbl.de/english/projects/aromis/keller.pdf.
- Mirsal, I. A. (2004). Soil Pollution: Origin, Monitoring, and Remediation. New York: Springer.
- Robertson, P., Coleman, D., Bledsoe, C., & P. Sollins (1999). Standard Soil Methods for Long-Term Ecological Research. New York: LTER.
- UN/ECE ICP-Forest (1994). UN/ECE International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests. Manual of Methods and Criteria for Harmonizing Sample Assessment, Monitoring and Analysis of the Effects of Air Pollution on Forests. Third edition.
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