From 1980 to the mid-1990s my main focus was on various aspects of radioactive waste disposal to the ocean. This included a large international project on low-level radioactive disposal on the ocean floor, with a particular focus on the NE Atlantic dumpsite. In addition, a significant effort was applied to investigating the fate of radionuclides discharged from the Sellafield nuclear fuel reprocessing site into the Irish Sea. In both cases use was made of natural and artificial tracers to quantify sediment processes in the seabed and sediment-water column exchanges. A particular interest was the use of radio-tracers to quantify the nature and rate of sediment mixing by burrowing organisms (bioturbation), and investigate the behaviour of poorly understood organisms such as Maxmulleria lankesteri, an Echiuran. Artificial radionuclides released from European reprocessing facilities provided excellent tracers of long-range surface ocean circulation, including the dynamics of coastal and shelf currents, biologically mediated vertical transport in the water column and longer-term deep water dynamics.
In the early 1990s the international community became aware of the practises of the former USSR in dumping substantial quantities of radioactive waste, including high-level material, in the Kara Sea and eastern Barents Sea. I became involved in the assessment of the consequences as part of the international effort, coordinated by the IAEA. In part, this was because of the need to account for the presence of radiocaesium in the area transported from the Sellafield site.
I led a research group for several years looking at several aspects of radioecology, including: biological uptake of radionuclides at a whole organism, organ and cellular level; the effects of radiation on reproductive success in fish; and, biogeochemical processes in the seabed and their impact on radionuclide behaviour
The experience gained in these formative years remains relevant today, for instance in the case of accidental loses (e.g. Komsomelets submarine), accidental discharges (e.g. Fukushima) and of assessments in connection with planned new nuclear build. Within the UK there remains a legacy of environmental contamination from past practises. This includes the relatively recent discovery of radioactive particles in the eastern Irish Sea, triggering renewed research interest and risk assessment.
I have worked with colleagues on many aspects of environmental contamination due to heavy metals, tributyl tin (TBT) and persistent bioaccumulating and toxic compounds (PBTs). This included defining appropriate 'background levels' for heavy metals, in relation to dumping dredged harbour sediments, and advising on a programme to 'cap' highly contaminated sediments offshore, dredged from a historically heavily industrialised and pollution estuary.
TBT was used extensively as an effective anti-fouling treatment on ships' hulls. Unfortunately it caused significant imposex changes in some species of invertebrates. I helped to develop a Bayesian Belief Network model which allowed the potential effects of TBT to be assessed under a series of socio-economic scenarios. It was then used to predict the recovery period once the TBT ban had been introduced. This demonstrated the utility of the BBN approach in allowing an ecological response to be linked directly with social and economic drivers, and potential management mitigation measures.
Excess inputs of nutrients into estuarine and coastal waters cause a variety of undesirable effects, such as alga blooms and oxygen depletion. This has been a recurring interest, evolving from helping to set up a major study of nutrient inputs from the rivers of eastern England in to North Sea, to collaborating with groups combining field observations with sophisticated models on nutrient cycling in coastal waters.
Project management experience has included several multidisciplinary studies of seabed and water dynamics and sediment-water exchanges in the North Sea and Irish Sea. Both regions are extensively fished using heavy bottom gears, leading to disturbance of the seabed. The degree of disturbance, the extent and timing of recovery, and a comparison with disturbance due to natural processes (bioturbation, current-wave interactions) has been a key research topic. This led to involvement in the development of in-situ autonomous sampling systems. An early incarnation in the 1980s (the 'flying bedstead') allowed 24 hour sampling of bottom waters for Th-234, combined with suspended solids and near-bottom currents. These systems rapidly grew in sophistication, culminating, for me, in the COBO sediment disturber.
In recent years the ecosystem-based approach has moved centre stage, and illustrated the need to consider a coupled socio-ecological systems approach (e.g. EU-FP6 ELME and FP7 Knowseas projects). This provides a mean of addressing the cumulative effects of multiple stressors, the sometimes conflicting interests of end users and the complexity of developing effective and acceptable measures.It has proved essential to work with a whole range of natural scientists and experts from a variety of other disciplines including, social and political scientists and economists. This has been challenging but very satisfying.
Marine litter has been recognised as a potential problem for many decades, and reports appeared in the early 1970s of the presence and potential effects of micro plastic particles in the ocean. However, the issue has risen in profile in the past decade in national, regional and international fora. UNEP, IMO, UNESCO-IOC, Regional Seas Organisations, the EU and national authorities have all launched programmes to assess the extent of the problem and propose possible management measures. My personal experience has included involvement in a large European programme (Marlisco), a framework ageeement with the European Commission, and several international initiatives. GESAMP has contributed with a global assessment of Sources, fate and effects of microplastics is the marine environment, which I am fortunate to lead. I also contributed to the Transboundary Water Assessment Programme (Global Environment Facility), as well as undertaking two consultancies for UNEP on marine litter and taking part in various workshops and initiatives organised by Regional Seas and International organisations.