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Know Your Urban Soil Restoring Urban Soils: How Can Bioremediation Help? What is Soil? Soil performs a number of essential life-supporting functions: →→ Habitat for soil organisms: Sustaining biological activity, diversity, and productivity Soil is alive and (hopefully) well in our cities! Although we generally think of soil in ‘natural’ fields and forests, The skin of the Earth. Soil exists as the exterior surface layer of our planet. The first living organisms may have originated Our actions are not only a cause of urban soil degradation, but are also capable of helping to restore urban soil →→ Water supply and purification: Regulating and partitioning water and solute flow in Earth’s oceans billions of years ago, but for at least 500 million years life has been evolving on land. Soil provides the it also exists beneath and between all the cracks of our paved and built environments. Some of our city soils quality, particularly within the context of environmental movements and greening cities. We have tremendous →→ Recycling nutrients and organic wastes: Filtering, buffering, degrading, immobilizing and detoxifying substrate for all five kingdoms of life to thrive on land, to take up nutrients, to grow in place and move through the world. have been formed by naturally occurring parent materials, while the rest of have developed on human-altered or opportunities to promote the sustainability of our urban areas by focusing on the health of our soils. organic and inorganic materials transported materials. →→ A restoration technique called bioremediation has been gaining interest in recent years. Bioremediation is Soil allows for new forms of life to come into being, as they incorporate the nutrients left there by organisms of the past. It Medium for plant growth: Storing and cycling nutrients and other elements Did you know? Approximately 9% of NYC is covered by soils formed in natural materials and approximately 28% the use of natural processes involving microorganisms, plants, and fungi, or their enzymes to clean and restore supplies the space for nutrients locked in living organisms to break down, while microbes like bacteria and fungi facilitate →→ Engineering Medium: Providing support for our built environment is covered by soils formed in human-altered or human-transported materials.1 polluted sites. Remediation, whether by biological means, chemical means or a combination of both, is of the decomposition of life. In soil, nutrients are released, stored in the Earth, and made available for new forms of life to particular interest because it both addresses problems of pollution and paves the way for a more ecologically continue to emerge. Soil Formation Soil Properties sustainable future. It presents humans with an opportunity to interact with nature in a way that is proactive and Urban Soil Issues Where do we find soil in the city? promotes ecological health in sites which are most in need of attention. Soil functions to protect the Earth and keep its many processes going, almost like organs in the body. As the Earth’s Soil is constantly forming and reforming from How do we understand and describe our highly surface it protects the land like skin and as gases move through soil it breathes like lungs. Water circulates materials a number of local and regional materials and diverse and complex soils? Each soil has a range Why should we care about our city soils? Urban soil is There are numerous methods for bioremediation, and each one has strengths and limitations. Soil remediation through the soil system and like a digestive tract, soil releases nutrients and supplies energy to the organisms of our →→ Gardens processes. It can take thousands of years for a few of easily observable (and less easily observable) capable of performing all of the essential life-supporting techniques can be either in situ or ex situ. Ex situ methods involve removing soil from the site or excavating soil for planet. →→ Front and back yards inches of soil to form naturally. properties that allow us to categorize them and functions that its suburban and rural counterparts treatment while in situ methods involve direct treatment, keeping soil in place and essentially enhancing natural →→ Athletic fields identify their forms and functions. The materials provide, such as cleaning water, supporting plant growth, remediation processes. Soil may appear to be a uniform dirty mass, but it is truly dynamic and complex. It is a constantly changing mix of minerals, →→ Playgrounds in soil and the ways soil forms largely shape these and storing carbon and other greenhouse gases. But our In situ treatments have many benefits, including minimal costs and disruption to the site, and minimal human and living organisms, decaying organic matter, air and water. Soil is bursting with life and can be vastly different from one inch →→ Parks Soil Forming Factors: properties. These properties, in turn, enable the soil urban soils are often highly disturbed by human activities environmental exposure to contaminated soil. The suitability of each bioremediation technology is determined to the next. →→ Woods to perform its invaluable life-supporting functions. and land use. by several factors, which may include site conditions, indigenous populations of microorganisms, and the types, →→ Tree pits Only half of soil is solid material. Healthy soils contain about 50% solid matter (45% mineral, 5% organic matter) and Parent Materials: Rocks, minerals, decaying Identifying soil properties allows us to determine quantities and potential toxicities of specific pollutants in the soil. Here, we will offer brief summaries of various organic matter soil quality. While it may take hundreds or thousands of years for →→ Traffic islands bioremediation techniques which can be performed in situ.3 about 50% pore space (with changing levels of air and water content). fertile topsoil to form naturally, it can be eroded away →→ School yards Climate: Sunlight, temperature, rain, wind Helps us understand soil mineral and almost instantly. Building on top of soils and walking →→ Rooftops Contained within just a few feet of this fragile surface, rocks, air, and water all meet and mix to support life on earth. Color: Organisms: Bacteria, archaea, fungi, nematodes, organic matter content or driving over them can cause soils to compact, which →→ Vacant lots Bioremediation Methods Bioremediation terms to know protozoa, insects, worms, mammals also limits their functions. We are constantly mixing or →→ Planting pots Texture: Indicates the percentage of sand, silt, removing our city soils, cutting into them, or filling them →→ Air particulates (e.g. dust) Compost & Compost Tea Topography: Steep slopes, shallow valleys and clay in soil, which impacts pore space and the with new materials, waste products, or construction →→ Beneath buildings and roads The application of compost and compost tea to soil can help Biodegradation: Breakdown of materials by Time: Years to millennia ability of air and water to move through soil debris. These actions make urban soils different from remediate sites polluted with certain types of contaminants bacteria, fungi, or other biological means. Soil Biology through bioaugmentation of soil to increase its capacity to Structure: Pertains to how mineral and organic soils in non-urban areas in some important ways: *Humans are also being recognized as a sixth soil →→ Display greater variability biodegrade contaminants. Compost is a mixture of living Biostimulation: Modification of the environment matter come together to form stable aggregates, What about Phytoremediation? Billions of organisms and thousands of different species can be found in a handful of healthy soil. The presence of these forming factor. Our actions can significantly affect →→ May have little or no organic matter soil organisms and decomposing organic matter which to stimulate existing bacteria capable of which also determines how well air, water and organisms is what sets soil apart from the nonliving rocks, minerals, and dust around us. It is the activities of these creatures what is added to soil, what is lost from soil, and →→ Have altered soil temperatures Some plants may potentially remove or break down can be made at home with substances like leaves, grass bioremediation. This can be done by addition of roots can move through soil →→ Are likely to contain human artifacts that enable soil to perform its vital functions, and each organism provides its own essential role in soil ecosystems. reactions within soil on very short time scales and certain chemical and biological contaminants in clippings, wood shavings and paper, among others. Compost phosphorus, nitrogen, oxygen, or carbon. →→ Have high probabilities of compaction An incredible diversity of organisms make up the soil food web. They range in size from the tiniest one-celled bacteria, with extremely large volumes. Human materials soil through a process known as phytoremediation. tea is essentially liquid fertilizer that is rich in beneficial Consistency: Refers to the stability of the soil →→ Display more contamination Bioaugmentation: Adding cultured algae, fungi, archaea and protozoa, to the more complex nematodes and micro-arthropods, to the visible earthworms, can also be the source of soil parent materials both However, this method of urban soil treatment microbes. The tea helps build soil structure by supplying structure microorganisms to assist in the breakdown of insects, small vertebrates, and plants. intentionally and unconsciously. While overall quality is an important concern for is not recommended for heavy metals such as vital nutrients, microorganisms and organic matter to pH: A ‘master variable’ that tells us how acidic contaminants. As these organisms eat, grow, and move through the soil, they make it possible to have clean water, clean air, healthy urban soils, an evaluation of soil quality wouldn’t be lead. Lead does not readily enter plants when soil. It can also increase soil porosity and water retention, or basic a soil is, and regulates organism activity, complete without assessing soil contamination.2 The the soil’s pH level is neutral or near neutral (pH of encourage biodiversity, and prevent plant diseases.

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