EGU General Assembly 2020
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the Creative Commons Attribution 4.0 License.

The impacts of urbanisation on urban soil carbon – a study from Manchester, UK

Roisin ORiordan1, Jess Davies1, Carly Stevens1, John Quinton1, and Christopher Boyko2
Roisin ORiordan et al.
  • 1Lancaster Environment Centre, Lancaster University, UK (
  • 2Imagination Lancaster, Lancaster University, UK

The study of anthropogenic soils is a growing area of interest, and as cities continue to expand, urban soils are heavily influenced by human activities. Urbanisation exhibits a wide range of impacts on soil, from buried horizons, compaction, sealing with impervious surfaces, additions of anthropogenic material to being largely man-made soils, or technosols. The properties of urban soil are further complicated by the addition of fertilisers, management strategies in greenspaces and the treatments of soil, including topsoil removal, during construction projects. Therefore, the properties and functions of anthropogenic soils differ notably to that of natural soils, and as such, there is a need to understand the dynamics of soil carbon in urban areas.

Research on urban soil carbon has been relatively limited, however there is recent growth in this area due to its importance, firstly, as a carbon store contributing to climate regulation, and secondly, in relation to the potential of urban soil to support numerous ecosystem services. Urban soils are highly heterogeneous and anthropogenic carbon additions can come from many current or historical sources, such as charcoal used in old roads, coal ash from power stations, carbon from car tyres, as well as inorganic carbonates in limestone road foundations. Understanding the current stores of carbon, as well as how stable it is, is important to understand likely carbon dynamics and storage potential.

This work presents a field study across Manchester (UK) where soil carbon data has been collected from soils across urban parks, greenspaces and from under sealed surfaces (roads and pavements). It provides carbon data for a variety of urban contexts and with high spatial variability. We will build on previous work from this field study by presenting i) a typology of urban soils according to anthropogenic content, ii) data for physical size fractionation to understand soil physical properties and texture, and iii) the carbon content of the size fractions to provide a proxy for understanding how labile or stable the carbon is. This will allow us to understand the impacts of soil sealing on the carbon content and build a picture of soil carbon stability across a range of urban situations.

This research will contribute to the much-needed understanding on how soil carbon behaves in urban areas, and the implications of this for carbon storage in both sealed and urban greenspace soils. 

How to cite: ORiordan, R., Davies, J., Stevens, C., Quinton, J., and Boyko, C.: The impacts of urbanisation on urban soil carbon – a study from Manchester, UK, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11818,, 2020


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  • CC1: Comment on EGU2020-11818, Julia Hargreaves, 04 May 2020

    Nice presentation!  There seems to be large variation in the sealed anthropogenic cases. What kinds of locations do these come from, especially compared to the undisturbed anthropogenic?


    • AC1: Reply to CC1, Roisin O'Riordan, 04 May 2020

      Thanks Julia!  The sealed samples (both anthropogenic and undisturbed) came mostly from roadworks and some construction sites all across the city.  They were usually from holes being dug in roads or pavements to fix utility pipes. I think whether they were anthropogenic or undisturbed was dependent upon how many times the holes had been re-dug, and how much the soil was disturbed by the activites. 

      • CC2: Reply to AC1, Julia Hargreaves, 04 May 2020

        Ok thanks. Interesting. So there could be a big range of histories for those anthropogenic sealed ones.

        • AC2: Reply to CC2, Roisin O'Riordan, 05 May 2020

          Yes, definitely. Especially as Manchester has a long history and is a post-industrial city, there has been a lot of redevelopment, and lots different materials get used as fill in urban soils which contributes to the complexity! 

  • CC3: Comment on EGU2020-11818, Tom Sizmur, 04 May 2020

    Hi Roisin,

    Fab presentation.

    Did you collect the urban greenspace soil samples from an equivalent depth to the sealed soils? In grassland/arable/woodland soils we see proportionally more SOC that is mineral associated with depth (and less that is POM).


    • AC3: Reply to CC3, Roisin O'Riordan, 05 May 2020

      Hi Tom, 


      The greenspace samples are from 0-10cm, but the sealed samples are from the first available soil underneath the road construction, which tended to be 70-80cm deep. Typically the topsoil is removed prior to road constuction so what we were reaching was a subsoil, often clay rich. It would have been great to have equivalent depth samples from the greenspaces but we weren't able to in this study. 

      Good point on the increase in mineral-SOC with depth, I'm sure that will play a part in what are seeing in our results - thank you for highlighting it.  Do you also work on urban soils? 


  • CC4: Comment on EGU2020-11818, Tom Sizmur, 05 May 2020

    Thanks Roisin,

    I think that SOM dynamics in subsoils may be quite different to topsoils (in urban or rural environments). I guess it is difficult to know exactly how much topsoil has been stripped off before the soil is sealed so it is difficult to make a direct comparison. 

    I don't work directly in urban soil as you do (i.e. certainly never looked at sealed soils). Most of my work is in arable soils, but I don't tend to discriminate. We know so little about what is happening underneath tarmac and concrete that I think that this stuff is definatley novel and exciting.


    • AC4: Reply to CC4, Roisin O'Riordan, 05 May 2020

      Yes, it is difficult to make a comparison, but as the topsoil has been removed (probably many years ago) we are looking at what soil is there now. But yes, likely SOC dynamics will be very different. 

      I've seen you're an author on another SOC stability presentation - chemical and physical stability of SOC in 1m depth in the UK - looks a very interesting piece of work, I will learn something from it! 

      • CC5: Reply to AC4, Tom Sizmur, 05 May 2020

        Yes - this is where we see that there is proportionally more mineral associated SOC at depth