The legacy of past manuring practices on soil contamination in remote rural areas

This paper demonstrates that there can be a legacy of contamination on former arable land in remote rural areas as a result of past manuring practices. In the first part of the study four farms abandoned in the late 19th to mid-20th century were investigated with samples collected from residual material in domestic hearths, the midden heaps, kailyards (walled garden for vegetables), infields (intensively managed arable land) and outfields (less intensively managed land for cropping or grazing). Consistent sequences in concentration values were found for such elements as Pb, Zn, Cu and P in the order hearth>midden>kailyard>infield>outfield. Such patterns can in part be explained in terms of atmospheric deposition on peat and turf which were subsequently burnt in hearths to result in enhanced elemental concentrations. The ash then was deposited in midden heaps and subsequently on kailyards or infields. In the second part, microanalytical results from St. Kilda are discussed. Enhanced loadings of Pb and Zn were found in the old arable land. The highest levels of Zn were found in small fragments of carbonised and humified material and bone fragments; in contrast Pb tended to be more uniformly distributed. Seabird waste was extensively applied to the arable land and some of the Zn may have accumulated in the soil by this pathway. The retention of Zn in bone is likely to have been very minor given the rarity of bone fragments as evident in thin sections (0.3%); this compares with 6.8% for black carbonised particles which are likely to provide the main storage sites for Zn.

Efficiency and soil contamination during underground application of insecticides: control of leaf-cutting ants with thermal foggers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimating the Extent of Soil Contamination During a Redevelopment Excavation

From October 2014 to March 2015, I provided excavation oversight services at a property with substantial environmental concerns. The property in question is located near downtown Seattle and was formerly occupied by the Washington’s first coal gasification plant. The plant operated from 1888 to 1908 and produced coal gas for municipal use. A coal tar like substance with a characteristically high benzene concentration was a byproduct of the coal gasification process and heavily contaminated at or below the surface grade of the plant as shown in previous investigations on the property. Once the plant ceased operation in 1908 the property was left vacant until 1955 when the site was filled in and a service station was built on the property. The main goal of the excavation was not to achieve cleanup on the property, but to properly remove what contaminated soil was encountered during the redevelopment excavation. Areas of concern were identified prior to the commencement of the excavation and an estimation of the extent of contamination on the property was developed. “Hot spots” of contaminated soil associated with the fill placed after 1955 were identified as areas of concern. However, the primary contaminant plume below the property was likely sourced from the coal gasification plant, which operated at an approximate elevation of 20 feet. We planned to constrain the extents of the soil contamination below the property as the redevelopment excavation progressed. As the redevelopment excavation was advanced down to an elevation of approximately 20 feet, soil samples were collected to bound the extents of contamination in the upper portion of the site. The hot spots, known pockets of carcinogenic polycyclic aromatic hydrocarbons (cPAH) located above 20 feet elevation, were excavated as part of the redevelopment excavation. Once a hot spot was excavated, soil samples were collected from the north, south, east, west and bottom sidewalls of the hot spot excavation to check for remaining cPAH. Additionally, four underground storage tanks (USTs) associated with the service station were discovered and subsequently removed. Soil samples were also collected from the resulting UST excavation sidewalls to check for remaining petroleum hydrocarbons. Once the excavation reached its final excavation depth of 20 to 16 feet in elevation, bottom of excavation samples were collected on a 35 foot by 35 foot grid to test for concentrations of contaminants remaining onsite. Once the redevelopment excavation was complete, soils observed from borings drilled for either structural elements, geotechnical wells, or environmental wells were checked for any evidence of contamination using field screening techniques. Evidence of contamination was used to identify areas below the final excavation grade which had been impacted by the operation of the coal gasification plant. Samples collected from the excavation extents of hot spots and USTs show that it was unlikely that any contamination traveled from the post-1955 grade down to the pre-1955 grade. Additionally, the lack of benzene in the bottom of excavation samples suggests that a release from the coal gasification plant occurred below the redevelopment excavation final elevations of 20 to 16 feet. Qualitative data collected from borings for shoring elements and wells indicated that the spatial extent of the subsurface contaminant plume was different than initially estimated. Observations of spoils show that soil contamination extends further to the southwest and not as far to the east and north than originally estimated. Redefining the extent of the soil contamination beneath the property will allow further subsurface investigations to focus on collecting quantitative data in areas that still represent data gaps on the property, and passing over areas that have shown little signs of contamination. This information will help with the formation of a remediation plan should the need to clean up the site arise in the future.

Is Rapid Adaptation to New Environments Fueled by Old Mutations? A Case Study of Copper Tolerance on Mimulus guttatus

Rapid adaptation and tolerance is a phenomenon experienced by a variety of organisms typically because of new and harsh environments. Mimulus guttatus, a plant commonly seen on the west coast of the United States, is a prime example as it has rapidly evolved to soil contamination by copper due to mining in California in the last 150 years. There have been two hypotheses posed by researchers as to the genetic basis of how organisms have evolved so quickly which I set out to study: 1) There is a low frequency of tolerant genotypes in the ancestral population otherwise known as standing variation or 2) new mutations occurred once exposed to a new environment. In the past, researchers found it difficult to distinguish between the two because they lacked the technology we have today for DNA analysis. I used four different populations of M. guttatus from varying locations in order to address which hypothesis was valid. I conducted both survival assays of these populations and DNA analysis of known tolerant and non-tolerant lines using a copper oxidase gene. I found that there was at least some degree of tolerance in all populations in the survival assays, supporting the hypothesis of standing variation. I also found patterns within DNA analysis suggesting the copper oxidase gene would be useful for further study to verify the standing variation hypothesis. The results from this experiment helps in understanding rapid evolution not just in the context of soil contamination by metals but also ties back to why an alarming number of species are not able to adapt to our constantly changing world.

Correlation of soil microbial community responses to contamination with crude oil with and without chromium and copper

Soil microcosms contaminated with crude oil with or without chromium and copper were monitored over a period of 90 days for microbial respiration, biomass, and for dehydrogenase, lipase, acid phosphatase, and arylsulfatase activities. In addition, the community structure was followed by enumerating the total heterotrophic and oil-degrading viable bacteria and by performing a denaturing gradient gel electrophoresis (DGGE) of the PCR amplified 16S rDNA. A significant difference was observed for biochemical activities and microbial community structures between the microcosms comprised of uncontaminated soil, soil contaminated with crude oil and soil contaminated with crude oil and heavy metals. The easily measured soil enzyme activities correlated well with microbial population levels, community structures and rates of respiration (CO2 production). The estimation of microbial responses to soil contamination provides a more thorough understanding of the microbial community function in contaminated soil, in situations where technical and financial resources are limited and may be useful in addressing bioremediation treatability and effectiveness. (C) 2012 Published by Elsevier Ltd.

Effect of microbial activities on the mobility of copper in stabilised contaminated soil

Stabilisation, using a wide range of binders including wastes, is most effective for heavy metal soil contamination. Bioremediation techniques, including bioaugmentation to enhance soil microbial population, are most effective for organic contaminants in the soil. For mixed contaminant scenarios a combination of these two techniques is currently being investigated. An essential issue in this combined remediation system is the effect of microbial processes on the leachability of the heavy metals. This paper considers the use of zeolite and compost as binder additives combined with bioaugmentation treatments and their effect on copper leachability in a model contaminated soil. Different leaching test conditions are considered including both NRA and TCLP batch leaching tests as well as flow-through column tests. Two flow rates are applied in the flow-through tests and the two leaching tests are compared. Recommendations are given as to the effectiveness of this combined remediation technique in the immobilisation of copper. © 2005 Taylor & Francis Group.

Yellow earthworms:Distinctive pigmentation associated with arsenic- and copper-tolerance in Lumbricus rubellus

Lumbricus rubellus Hoffmeister, inhabiting soil at the 19th century Devon Great Consols mine at Tavistock, Devon, UK, show high tolerance to Cu- and As-toxicity and frequently have a striking yellow coloration. Specimens from this site (mature and immature) and from an uncontaminated site on Lancaster University campus (mature) were photographed, and the slide images digitized and analyzed. All L. rubellus showed reddish-purple pigmentation of the body wall that declined in intensity posteriorly. The metal- and metalloid-resistant earthworms, whether mature or immature, showed yellowing in the posterior half of the body. The source of the coloration was intense yellow pigmentation of the chloragogenous tissue surrounding the alimentary canal. The yellow pigmentation is masked by reddish-purple body wall pigmentation anteriorly. Total As concentrations in tissues were determined for the anterior, middle and posterior sections of resistant and non-resistant L. rubellus. Highest concentrations were in the middle sections of the mature and immature resistant L. rubellus (36.17 ± 19.77 and 27.77 ± 9.02 mg As kg^-1, respectively). Resistant immature L. rubellus lost condition over 28 d in soil treated with 750 mg As kg^-1, possibly due to a higher metabolism, whilst there was no loss in condition for resistant mature L. rubellus in the treated soil. As far as the authors are aware, this is the first report of yellow pigmentation of this kind in earthworms. The pigmentation may provide a useful indicator of exposure/resistance to soil contamination. © 2002 Elsevier Science Ltd. All rights reserved.

Effects of hydrocarbon contamination on soil microbial community and enzyme activity

Acknowledgment I would like to gratefully acknowledge the government of Saudi Arabia for the scholarship and financial support.

Background levels of urban land contamination

The research work reported in this thesis is concerned with the development and application of an urban scale sampling methodology for measuring and assessing background levels of heavy metal soil contamination in large and varied urban areas. The policy context of the work is broadly the environmental health problems posed by contaminated land and their implications for urban development planning. Within this wider policy context, the emphasis in the research has been placed on issues, related to the determination and application of 'guidelines' for assessing the significance of contaminated land for environmental planning. In concentrating on background levels of land contamination, the research responds to the need for additional techniques which address both the problems of measuring soil contamination at the urban scale and which are also capable of providing detailed information for use in the assessment of contaminated sites. Therefore, a key component of the work has been the development of a land-use based sampling framework for generating spatially comprehensive data on heavy metals in soil. The utility of the information output of the sampling method is demonstrated in two alternative ways. Firstly, it has been used to map the existing pattern of typical levels of heavy metals in urban soils. Secondly, it can be used to generate both generalised data in the form of 'reference levels' from which the overall significance of .background contamination may be assessed and detailed data, termed 'normal limit levels' for use in the assessment of site specific investigation data. The fieldwork was conducted in the West Midlands Metropolitan County and surface soil has been sampled and analysed for a measure of plant-available' and 'total' lead cadmium, copper and zinc. The research contrasts with much of the previous work on contaminated land which has generally concentrated on either the detailed investigation of individual sites suspected of being contaminated or the appraisal of land contamination resulting from specific point sources.

Application of chemometrics to analysis of soil pollutants

This overview focuses on the application of chemometrics techniques for the investigation of soils contaminated by polycyclic aromatic hydrocarbons (PAHs) and metals because these two important and very diverse groups of pollutants are ubiquitous in soils. The salient features of various studies carried out in the micro- and recreational environments of humans, are highlighted in the context of the various multivariate statistical techniques available across discipline boundaries that have been effectively used in soil studies. Particular attention is paid to techniques employed in the geosciences that may be effectively utilized for environmental soil studies; classical multivariate approaches that may be used in isolation or as complementary methods to these are also discussed. Chemometrics techniques widely applied in atmospheric studies for identifying sources of pollutants or for determining the importance of contaminant source contributions to a particular site, have seen little use in soil studies, but may be effectively employed in such investigations. Suitable programs are also available for suggesting mitigating measures in cases of soil contamination, and these are also considered. Specific techniques reviewed include pattern recognition techniques such as Principal Components Analysis (PCA), Fuzzy Clustering (FC) and Cluster Analysis (CA); geostatistical tools include variograms, Geographical Information Systems (GIS), contour mapping and kriging; source identification and contribution estimation methods reviewed include Positive Matrix Factorisation (PMF), and Principal Component Analysis on Absolute Principal Component Scores (PCA/APCS). Mitigating measures to limit or eliminate pollutant sources may be suggested through the use of ranking analysis and multi criteria decision making methods (MCDM). These methods are mainly represented in this review by studies employing the Preference Ranking Organisation Method for Enrichment Evaluation (PROMETHEE) and its associated graphic output, Geometrical Analysis for Interactive Aid (GAIA).

Optimal adaptive sequential spatial sampling of soil using pair-copulas

A spatial sampling design that uses pair-copulas is presented that aims to reduce prediction uncertainty by selecting additional sampling locations based on both the spatial configuration of existing locations and the values of the observations at those locations. The novelty of the approach arises in the use of pair-copulas to estimate uncertainty at unsampled locations. Spatial pair-copulas are able to more accurately capture spatial dependence compared to other types of spatial copula models. Additionally, unlike traditional kriging variance, uncertainty estimates from the pair-copula account for influence from measurement values and not just the configuration of observations. This feature is beneficial, for example, for more accurate identification of soil contamination zones where high contamination measurements are located near measurements of varying contamination. The proposed design methodology is applied to a soil contamination example from the Swiss Jura region. A partial redesign of the original sampling configuration demonstrates the potential of the proposed methodology.

Assessment of phytostabilization of Pb/Zn mine soils with organic amendments and a native metallicolous ecotype of Festuca Rubra l.: implications for amendment selection and recovery of soil health

La contaminación del suelo es una de las principales amenazas para los ecosistemas y la salud humana. Actualmente, desde un punto de vista tanto económico como ambiental, la fitoestabilización es la mejor tecnología para remediar suelos contaminados con elevadas concentraciones de metales como son los suelos mineros. La fitoestabilización asistida consiste en el empleo de plantas y enmiendas orgánicas y/o inorgánicas con el fin de reducir la movilidad y la biodisponibilidad de los contaminantes y recuperar la salud de suelo. En este trabajo se han realizado ensayos en microcosmos y en campo centrándonos en la salud del suelo minero contaminado con Pb y Zn durante un proceso de fitoestabilización empleando enmiendas orgánicas (purines vacunos, gallinaza, estiércol de oveja y lodos de papelera mezclados con gallinaza) y/o la especie metalífera Festuca rubra con el objetivo de (i) estudiar las interacciones suelo-enmienda responsables de los cambios inducidos por el proceso de quimioestabilización en las propiedades físicoquímicas y biológicas del suelo, (ii) evaluar la efectividad del proceso de fitoestabilización sobre suelos vegetados y de la revegetación sobre suelos desnudos (iii) valorar la idoneidad de distintos indicadores químicos y biológicos (parámetros microbianos y de la vegetación) para monitorizar la efectividad de la fitoestabilización asistida en términos de reducción de la biodisponibilidad de metales en el suelo, mejora de la vegetación y de la recuperación de la salud del suelo. La aplicación de enmiendas al suelo minero supone una entrada de materia orgánica y nutrientes que conduce a una disminución de la biodisponibilidad de metales, facilitando la colonización de las plantas y el crecimiento de la vegetación nativa, además de estimular la actividad microbiana del suelo. El pH del suelo es un factor crítico que condiciona la movilidad de los metales y la toxicidad del suelo. Las poblaciones microbianas de las enmiendas no modificaron la diversidad funcional de las comunidades microbianas nativas de la mina. Los purines vacunos y los lodos de papelera mezclados con gallinaza son los tratamientos más efectivos en el proceso de fitoestabilización asistida bajo condiciones de campo. La gallinaza fue el tratamiento que más estimuló el crecimiento de la vegetación nativa y la colonización en los suelos desnudos. El bioensayo de elongación radical de lechuga es un test sensible, sencillo y barato para evaluar la biodisponibilidad de metal y la ecotoxicidad del suelo. Los tocoferoles son biomarcadores de exposición a metales con potencial para su implementación en bioensayos de toxicidad. Este trabajo permite concluir que la población metalífera de F. rubra, combinada con enmiendas orgánicas, es una excelente candidata para los proyectos de fitoestabilización asistida. Además, la monitorización simultánea de los parámetros fisicoquímicos y microbiológicos del suelo y de su ecotoxicidad permite una evaluación adecuada de la salud del suelo, así como la selección de enmiendas apropiadas para el desarrollo de un proceso fitoestabilizador.

Polycyclic aromatic hydrocarbon (PAH) dispersion and deposition to vegetation and soil following a large scale chemical fire

Polycyclic aromatic hydrocarbons (PAHs) were determined in soil and vegetation following a large scale chemical fire involving 10,000 ton of polypropylene. In comparison with sites outside the plume from the fire, PAH concentrations were elevated in grass shoots (by up to 70-fold) and in soil (by up to 370-fold). The pattern of PAH dispersion under the plume was dependent on the physical-chemical properties of individual PAHs. The lighter, least hydrophobic PAHs were dispersed into the environment at greater distances than heavier, more hydrophobic PAHs. At the most distant sampling point (4.5 km) under the plume, the low molecular weight PAHs were still considerably elevated in vegetation samples compared to control sites. Dispersion appeared to be regulated by the compounds partitioning between the vapour and particulate phase, with dry particulate deposition occurring closer to the fire source than gaseous deposition. For all PAHs, the fire resulted in greater contamination of soils compared to grasses, with the relative ratio of plant/soil contamination decreasing as hydrophobicity increased.

Antimony bioavailability in mine soils

Five British former mining and smelting sites were investigated and found to have levels of total Sb of up to 700 mg kg(-1), indicating high levels of contamination which could be potentially harmful. However, this level of Sb was found to be biologically unavailable over a wide range of pH values, indicating that Sb is relatively unreactive and immobile in the surface layers of the soil, remaining where it is deposited rather than leaching into lower horizons and contaminating ground water. Sb, sparingly soluble in water, was unavailable to the bacterial biosensors tested. The bioluminescence responses were correlated to levels of co-contaminants such as arsenic and copper, rather than to Sb concentrations. This suggests that soil contamination by Sb due to mining and smelting operations is not a severe risk to the environment or human health provided that it is present as immobile species and contaminated sites are not used for purposes which increase the threat of exposure to identified receptors. Co-contaminants such as arsenic and copper are more bioavailable and may therefore be seen as a more significant risk.