Contaminated soil with WSU compost
The recent times have experienced an increase in adoption of agricultural practices largely centered in urban areas. Urban agriculture is characteristic of gardens close to community habitations which supply the larger community with the necessary supply of most food crops. Despite having common advantages like nutritional improvement, improvement of the existing soil areas and enhancing the way people look at their health and ecosystem, the use of urban soils have largely increased the rate at which elements concentrate in the soils. These concentrations can be traced to mining activities and related industrial activities that use heavy base metals, emission of crude oil gases and paints in general.
Another angle to the topic of soil contamination relates to the mining and excavation of grounds with the desire to extra metal ores. These processes produce large amounts of waste materials that have deposits of metals like Pb, Cu and Zn which are notorious in degrading the environment. The resulting effect of Pb and other heavy metal contaminations is the disruption of the microorganisms that enhance the soil aeration, fertility and other biogeochemical process of N and C.
A major contributor to contamination in the urban setup is Lead. This is a common element traced in most urban soils due to the use of fertilizers based on lead, extensive mining processes related to extraction of Lead metal ores. According to Aschengrau et al (1994) the effects of high lead concentrations in soil includes increased concentrations in the blood stream of the children inhabiting these specific regions. The modes of contact involving Lead include direct eating of soil that is largely contaminated with Lead. Another common method is inhalation of dust particles from contaminated soil that happens in areas experiencing winds (Mielke 1994). Research done by Chaney and Ryan, 1994 consider ingestion of Lead contamination through food as a minor risk as compared to the continued exposure to contaminated soil particles. This means that the more farmers in soil contaminated regions spend in their farms, the more the effect of the Lead exposure they get.
Review of existing solutions
Numerous solutions have found place in literature and research with the aim of lowering or dealing away with the effect of Pb contamination in soil. Top on the list is the use biosolids compost that has bee shown to largely reduce the bioaccessibility of lead in soils by making use of both vivo and vitro measures. Farfel et al (2005) note that Pb is considerably diluted when WSU compost is added to Pb contaminated soil. Another solution to contamination involves the use of metal oxides in the process of complexation (Martinez and McBride 2001).
There exists a large challenge to the large scale adoption of most Fe based composts because of their availability and the costs involved are somewhat expensive. Most compost also takes a long time to prepare with a large spectrum of ingredients that are not readily available in most regions.
This project proposes the use of WSU compost as the most amicable solution for the problem of Pb contamination. WSU compost is not only laboratory tested to ascertain its excellence on handling the Pb concentration issue in soils. WSU compost is organic, rich, and has a high ratio of Carbon to Nitorgen with a very low concentration of herbicides that are considered to be persistent and harmful to plants. The WSU compost is less costly as compared to the other high Fe based composts. The reason for this low cost is the use of most readily available ingredients in its preparation. These include food waste, greenhouse soil coal ash and animal manure and bedding. This together with the NPK and other Ammonium based components form a large reduction in Pb bio accessibility. A case in point concerning the chemical composition of WSU compost is NO2-N, NH4-N and NO3-N that easily blend with Pb in a precipitation reaction to form both soluble salts and an insoluble salt based on Pb. the liability of contaminated soils mixed with WSU composts is enhanced through improvement of the soluble percent achieved through the process of precipitation.
In order to achieve these experimental results, this project will use soil samples that are differentially contaminated. Three soil samples will be used for a period of a month. All samples will have an equal addition of WSU compost. The samples will be irrigated throughout the period of experiment to enhance the precipitation process.
At the end of the period, the content of soluble salts, Pb based salts and other soil elements will be measured in a laboratory setup.
With a large access to this WSU compost, most farmers will have less exposure to Pb contamination because of the considerably less time involved in the soluble salt and precipitation of Pb based salts without necessarily affecting the health of the crops. The risk involved with eating foods that are contaminated will also be reduced to very negligible levels.
Aschengrau, A., A. Belser, D. Bellinger, D. Copenhafer, and M. Weitzman. 1994. Th e impact of soil lead abatement on urban children’s blood lead levels: Phase II results from the Boston lead-in-soil demonstration project. Environ. Res. 67(2):125–148. doi:10.1006/enrs.1994.1069.
Farfel, M.R., A.O. Orlova, R.L. Chaney, P.S.J. Lees, C. Rohde, and P.J. Ashley. 2005. Biosolids compost amendment for reducing soil lead hazards: A pilot study of Orgo amendment and grass seeding in urban yards. Sci. Total Environ. 340:81–95. doi:10.1016/j.scitotenv.2004.08.018
Martinez, C.E., and M. McBride. 2001. Cd, Cu, Pb, and Zn coprecipitates in Fe oxide formed at diﬀ erent pH: Aging eﬀ ects on metal solubility and extractability by citrate. Environ. Toxicol. Chem. 20:122–126. doi:10.1002/etc.5620200112
Mielke, H.W., D. Dugas, P.W. Mielke, K.S. Smith, and C.R. Gonzales. 1997. Associations between soil lead and childhood blood lead in urban New Orleans and rural Lafourche Parish of Louisiana. Environ. Health Perspect. 105(9):950–954. doi:10.1289/ehp.97105950