Concentrations of PAH and PCB in London

The British Geological Survey recently published an open access study on the distribution and abundance of organic pollutants in London soils1 . The study reflects an opportunity to characterise soil contamination at different geographical scales to support site specific risk-based land management (RBLM). The policy backdrop for this study is the coalition Government’s announcement and implementation of the Environment Theme Red Tape Challenge2 . Effective changes arising from the initiative may end up being quite far reaching, with the potential archiving of many useful guidance documents

From Tahrir to Independence Square: The Evolution of Digitally Mediated Protest Movements 2009 – 2013

The surge in mass protest movements against authoritarian regimes around the world is raising questions about the reasons, motives and timing of such risky political activity. The hailing of social media as an enabler for contentious political action raises questions regarding the political impact of these new technologies, and how they may play a role in fomenting mass protests. A process-tracing analysis of four major protest movements will serve to examine the structural qualities of social media, and whether their particular use by activists and disgruntled publics is helping to spur mass disobedience and protest activity. The movements in Egypt in 2011, Iran in 2009, Turkey in 2013 and Ukraine in 2013 will serve to infer a broadly generalizable theory about social media’s role in contentious political activity and mass movements

Agent based modelling : initial assessment for use on soil bioaccessibility

This report describes the testing of Agent Based Modelling implementations in three different software packages: Repast-simphony, NetLogo and Insight-maker. These software have been evaluated against their capability to simulate the exposure of people as agents moving across Arsenic contaminated soils. Two of the three tested software (Repast-simphony and NetLogo) are recommended for assessment on more complex problems. An outline work plan is presented for future work

Rise and fall of mercury (Hg) pollution in sediment cores of the Thames Estuary, London, UK

Fifty six sediment cores were collected along a 100 km longitudinal transect of the Thames estuary. Total Hg ranged from 0.01 to 12.07 mg/kg, with a mean of 2.10 mg/kg (n=351). Concentrations of the toxic metal decreased downstream from London to the outer estuary and were positively correlated to total organic carbon (TOC) content. Many Hg profiles showed a clear rise, peak and fall, reflecting changing anthropogenic input through time. Surface concentrations averaged 1.27 mg/kg, confirming the effectiveness of recent environmental legislation and improved river management. Sediments at >40 cm depth from London reaches of the river (Waterloo Bridge, Cuckolds Point (Rotherhithe), Butlers Wharf (Tower Bridge), Millwall, Deptford and Millennium Dome) were highly contaminated, with levels of Hg of >7 mg/kg. The outer Thames had lower Hg, with the exception of Rainham, Crossness and Cliffe. Benchmarking against UK guidelines for the disposal of dredged material revealed that 88 samples from 21 sites exceeded the 3 mg/kg criteria (unsuitable for disposal at sea); 173 fell between 0.3 and 3 mg/kg (further assessment required); and 90 were of no concern. Using Hg as a generic pollution marker, the tidal Thames is one of the world's most contaminated river–estuarine sediment systems

Validation of a gravimetric PM2.5 impactor using particle sizing techniques

Particulate matter sampling was conducted at Ballidon Quarry, Ballidon, Derbyshire. The quarry is owned and managed by Tarmac Trading Ltd. (Tarmac). The monitoring station deployed comprised two DS500X gravimetric samplers fitted with PM2.5 impactors, that were placed side by side in the primary crusher shed during February 2016. Monitoring was conducted over three, seven day periods. Particulate matter from six filters and oversize particulate matter collected from the impactor plates were analysed by BGS on behalf of DustScan using Scanning Transmission Electron Microscopy and Laser Diffraction granulometry. The results of the work show that the DS500X fitted with a PM2.5 size selective impactor is capable of separating particles with a projected area diameter of ≤ 2.5 μm from ambient air, retaining themon filter media for subsequent quantification. The overall median particle size recorded on the filters was 0.46 μm, the mean was 0.74 μm and the 95th percentile was 2.15 μm (n = 6343). A number of observations were made during this study and included in the full report which should be considered when interpreting the results

Infrared spectroscopy and chemometric modelling of organic carbon measured by Rock-Eval pyrolysis of UK shale rock

Shale rock core from the Bowland Shale Formation, UK was analysed in the laboratory using Rock-Eval(6) pyrolysis and Fourier Transform Infrared Spectroscopy (FTIR). These methods are used to characterise the organic constituents of soil and rock. This research is a proof-of-concept study to investigate whether regression models developed using FTIR and Rock-Eval data for the same length of core can be used to estimate selected Rock-Eval parameters. The accuracy of the regression models was assessed using statistical methods, the results of which were used to choose preferred models for each Rock-Eval parameter. Models produced were shown to have an acceptable level of uncertainty for Total Organic Carbon, S1, S2 and S3 outputs which led us to conclude these are potentially suitable for estimating unknown down-core Rock-Eval parameter values. Conversely, the Tmax model had a higher variability in the cross-validation data above the acceptable level of uncertainty which could lead to erroneous estimates. Down-core interpolations of selected Rock-Eval parameters could be practically achieved by modelling FTIR data by maintaining standard sample frequencies for Rock-Eval while supplementing with higher frequencies for FTIR and chemometric analysis

A typology of different development and testing options for symbolic regression modelling of measured and calculated datasets

AbstractData-driven modelling is used to develop two alternative types of predictive environmental model: a simulator, a model of a real-world process developed from either a conceptual understanding of physical relations and/or using measured records, and an emulator, an imitator of some other model developed on predicted outputs calculated by that source model. A simple four-way typology called Emulation Simulation Typology (EST) is proposed that distinguishes between (i) model type and (ii) different uses of model development period and model test period datasets. To address the question of to what extent simulator and emulator solutions might be considered interchangeable i.e. provide similar levels of output accuracy when tested on data different from that used in their development, a pair of counterpart pan evaporation models was created using symbolic regression. Each model type delivered similar levels of predictive skill to that other of published solutions. Input–output sensitivity analysis of the two different model types likewise confirmed two very similar underlying response functions. This study demonstrates that the type and quality of data on which a model is tested, has a greater influence on model accuracy assessment, than the type and quality of data on which a model is developed, providing that the development record is sufficiently representative of the conceptual underpinnings of the system being examined. Thus, previously reported substantial disparities occurring in goodness-of-fit statistics for pan evaporation models are most likely explained by the use of either measured or calculated data to test particular models, where lower scores do not necessarily represent major deficiencies in the solution itself

A review of the current state of the art of physiologically-based tests for measuring human dermal in vitro bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil

Polycyclic Aromatic Hydrocarbons are classed as Persistent Organic Pollutants, a large group of compounds that share similar characteristics. They are lipophilic, resistant to degradation in the environment and harmful to human and environmental health. Soil has been identified as the primary reservoir for Polycyclic Aromatic Hydrocarbons in the United Kingdom. This study reviews the literature associated with, or is relevant to, the measurement and modelling of dermal absorption of Polycyclic Aromatic Hydrocarbons from soils. The literature illustrates the use of in vivo, in vitro and in silico methods from a wide variety of scientific disciplines including occupational and environmental exposure, medical, pharmaceutical and cosmetic research and associated mathematical modelling. The review identifies a number of practical shortcomings which must be addressed if dermal bioavailability tests are to be applied to laboratory analysis of contaminated soils for human health risk assessment

Increasing recovery opportunities of metal(loid)s from municipal solid waste via landfill leachate recirculation

The recovery of 12 critical raw materials (CRM) from municipal solid wastes (MSW) via leachate recirculation was evaluated using a 4 L semi-pilot scale column percolation. The results showed that the recovery of the metal(loid)s was mainly influenced by order of importance: pH > organic content > type of metal(loid)s > age of the waste > redox potential. Among the CRM, Cd and Ni were the most mobile elements, while As and Cr were the least mobile. A comparison of leachate from the leachate recirculated columns before and after the initiation of recirculation indicates an increase in the concentrations of certain CRM and metalloids. The first recirculation cycle supported achieving 100 % recovery. CRM and metalloids in leachate can be recovered; however, the concentrations of CRM and metalloids are usually below 1 mg/L. In this regard, leachate recirculation may enhance the increasing concentration of CRM in landfill leachate. For example, after first recirculation cycle, Ni concentration increased from 0.05 mg/L to 0.11 mg/L. The results obtained from this study can develop further methodologies for the potential recovery of CRM and help foster further research into overcoming limitations for recovering CRM in landfill leachate