Abstract:
Soil provides multiple essential functions, such as provision of food and raw
materials, a platform for urban development and human wellbeing and as a
filtering and transforming medium. Many unregulated contaminants, often termed
emerging contaminants, are globally released on soil creating potential risks,
especially when undetected leading to significant impact on environmental
receptors. The UK ministry of Defence plays an important role in soil protection
as the biggest holder of Sites of Special Scientific Interest (SSSI) in the UK as
well as being an active polluter in these protected areas through essential training
activities. Therefore, there is a need to improve methods for early identification of
emerging contamination to avoid long term environmental impacts and costly
remediation. The research undertaken for this thesis has contributed to the
development of a soil analytical framework to facilitate early identification of the
deleterious effects of emerging contaminants and chemicals of military concern
on soil. During this research two different scenarios were considered, firstly, when
there is a significant body of ecotoxicological data available for a specific
contaminant in the literature and secondly, when ecotoxicological data is not
available.
A scale based on potential hazards was created for the first scenario, which aims
to classify chemicals into three categories - low, medium, and high environmental
hazards. This scale serves as an inexpensive method to identify the risk of soil
degradation. Results from this research showed that for the contaminants of
interest (e.g. 1,3,5-trinitro-1,3,5-triazine - RDX, 2,4,6-Trinitrotoluene - TNT,
Perfluorooctanoic Acid - PFOA, Perfluorooctane Sulfonate - PFOS and
Cypermethrin) the low-level hazard values were lower than expected. These
values were expected to correspond to existing Soil Screening Values (SSVs)
and Ecological Soil Screening Levels (Eco-SSL), meaning that the contaminants
are likely to have a negative impact on the soil at lower concentrations.
For the second case, when data is not available experiments need to be
undertaken to generate primary data. Insensitive High Explosives (IHE)
compositions were identified as lacking data and explosive residues were collected and soil mesocosms were carried out to define the long-term
consequences on soil. Field experiments were used to quantify IHE residue
deposition concentrations from a standard 155 mm artillery shell, which was then
used to estimate potential contamination after 100 detonations. These values
were used to estimate low, medium and high contaminant concentration for soil
mesocosm studies to quantify the impact on soil using indicators identified
through literature review. A standardised procedure was developed based on
this, which quantifies the consequences of explosives on soil. This procedure
revealed that soils that are already degraded are more susceptible to the impact
of explosives, which primarily affects the chemical and biological properties of the
soil. .
Specifically, this work has shown that the frequent use of IHE filled munitions on
training ranges will have an effect on the quality of the soil even when low
quantities of energetic residue are deposited. Results for this thesis represent a
first step towards a more comprehensive soil analytical framework development
providing early identification tools for soil protection.