Disposal of Oiled Beach Sand in C Onstalsj Á Ce Ntre for Ec Olog Y & Hy Drology
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Centre for Ec ology & Hy drology Disposal of oiled beach sand in c onstaLsJ á Ce ntre for Ec olog y & Hy drology Disposal of oiled beach sand in coastal soils R.E. Daniels,' A.F. Harrison,2 G.H. Hall,3 J.S. Garnett,2 A.P. Rowland,2 R. Scott,2 and J. Davies' ' ITE Furzebrook ITE Merlewood 3 1FE Windermere BGS Wallingford c a Final Report to Maritime and Coastguard Agency ITE is one of four Institutes which form the Centre for Ecology and Hydrology, a part of the UK Natural Environment Research Council. The mission of CEH is to advance the sciences of ecology, environmental microbiology (including virology) and hydrology. It will do this through high-quality and internationally recognised research which will lead to a better understanding and quantifi cation of the physical, chemical and biological processes relating to land and freshwater, and of living organisms within these environments. ITE is responsible for research into all aspects of the terrestrial environment and its resources, and has specialist staff based at six research stations, each with its own particular expertise and regional emphasis. This report is an official document prepared under contract between the Maritime and Coastguard Agency and the Natural Environment Research Council. Permission to use material contained within the report should be sought from both MCA and NERC. September 1999 TABLE OF CONT ENTS EXE CUTIVE SUM MARY 1. INTRODUCTI ON 5 1.1 The incidence of spills 5 1.2 The problem of disposal 5 1.3 Aims of the proj ect 5 2. NATURAL BIO REME DIATIO N 7 2.1 Hydrocar bon degradation 7 2.2 Th e distribution of hydrocarbon degr ader s in the environment 8 2.3 Biodegr adation following spills 8 2.4 The sta rting material 8 3. EXPERIM ENTAL APPROACH 11 3.1 Gener al philosophy 11 3.2 Exper imental sca les 11 3.3 Toxicity trials 12 3.4 Lysimeter experiments 12 3.5 Eskmeals field trials 13 3.6 Extensive study • 15 3.7 First Pendine deposit 16 3.8 Second Pendine deposit 17 3.9 Micr obiological techniques 19 3.10 Decomposition activity 19 3.11 Assessment of degradation 20 3.12 Assessment of leaching 20 4. FACTORS AFFECTING DEGRADATION 21 4.1 Patter n of degr adation 21 4.2 Effects of oil type and concentration 21 4.3 Effects of temper ature 23 4.4 Effects of moisture 23 4.5 Effects of sand type 27 4.6 Effects of micr obial differ ences 29 4.7 Effects of treatment 31 4.8 Inter actions 34 5. DE GRADATIO N PRODUCTS AND THEIR FATE 35 5.1 Introduction 35 5.2 Heavy metals 35 5.3 Changes in hyd rocarbon composition 36 5.4 Vertical migration 36 5.5 Leaching of miner al ions to groundwater 37 5.6 Leaching of hydrocarbons to groundwater 37 6. SITE RECOVERY 39 6.1 Na tu re conser vation value of dunes 39 6.2 Toxicity testing of plants 40 6.3 Recovery of dune sites 40 7. CONCLUSIONS 45 8. IMPLEMENTATION 47 8.1 Site consider ations 47 8.2 Site factors infl uencing degradation 47 8.3 Management factors 48 8.4 Public per ception 49 9. F UTURE RESEARCH NEEDS 51 9.1 Enh ancement of degr adation 51 9.2 Site selection 51 10 ILLUST RATIO NS 53 11. ACKNOWLEDGEMENTS 57 12. REFERENCES 59 EXE CUTIVE SUMMARY Background Experiments to study the factors identi fi ed in the literature as being important in controlling rates Disposal of oiled sand removed from beaches of decomposition were conducted in the contaminated as a result of oil spills at sea poses a laboratory and in the fi eld. Potential for maj or problem. Regulatory and environmental movement of the introduced hydrocarbons, or constraints are increasingly limiting the use of their breakdown products was measured in landfill sites to dispose of such material . In many laboratory scale experiments and in fi eld trials. remote ar eas the only acceptable disposal method Toxic effects of oil residues on plants were is the long-distance transport of the OBS to an examined in glasshouse tests and the capacity for offi cially licensed disposal sit e. site recovery was measured in fi eld trials. Towards the end of the project, issues of .A research programme to investigate the feasibility selection and management of suitable sites were and environmental acceptability of an alternative explored with representatives of local authorities, method of disposal was instigated by the Maritime statutory 'conservation agencies and the and Coastguard Agency (formerly Marine Pollution Environment Agency. Control Unit of the Coastguard Agency). Its purpose was to assess the practicality and Experimental Work environmental acceptability of using naturally occurring populations of soil micro-organisms to La boratory experiments degrade weathered oil residues incorporated into M icrobiological studies examined the stimulation sandy coastal soils. Especiall y in low grade, non- of respiration of microbial communities when sensitive areas of coastal sand dunes and dune challenged with introduced hydrocarbons andt pastures. If the method proved successful it would the ability of cultured organisms to break facilitate disposal of oil ed beach sand (OBS) in aromatic ring structures. remote areas where disposal is dif fi cult and expensive. Small-scale experiments were used to examine the responses of plants found in coastal dunes and The work was carried out by a consortium led by dune pastures to the presence of different The Institute of Terrestrial Ecology and began in concentrations of weathered and unweathered oil 1994 residues. M ain conclusions A lysimeter facility (consisting of 30 tubes 2 m deep x 27.5cm diameter) at ITE Merlewood was used to examine the infl uence of a number of • M icrobial action can rapidly reduce the factors on the rate of hydrocarbon degradation concentration of hydrocarbons in oiled sand. and the composition of drainage water in Under favourable conditions, the oriemal replicated experiments. hydrocarbon content can be more than hal ved in less than a year. Field Trials A fi eld trial at Eskmeals, Cumbria was used to • The process has produced no adverse compare degradation rates in replicated plots environmental effects. There was no movement containing buried and landfarmed OBS. of hydrocarbons to groundwater, and plant and Measurements were also made of air and soil animal communities were not affected by the temperatures, and rainfall and water table presence of weathered oil residues in the soil. fl uctuations. Groundwater samples taken from beneath the plots were analysed to determine M ethodology whether hydrocarbons were present. An initial feasibility study showed that the problem of OBS disposal in coastal areas required an A larger scale monitoring trial, following oil ecological rather than a technical approach. residue decomposition, was conducted at Observations were made in the laboratory and in Pendine, where OBS prepared from a stranding of the fi eld to obtain information on the processes tar balls was placed in a dune hollow. The deposit involved in microbial degradation of petroleum was characterised by uneven distribution of hydrocarbons and their ecological consequences. highly weathered oil residues. This site was also used to examine the progress of plant colonisation practical terms to increase the efficiency of natural and sand stabilisation within the dune area. breakdown. However, if the rate limiting factor is related to physical or chemical properties of the A second experiment at Pendine was designed to sand containing the oil residues some form of measure the decomposition of a homogeneous OBS treatment may be possible which is capable of prepared with a high concentration of fuel oil to enhancing the rate and completeness of detect any movement of hydrocarbons from the breakdown. For example, the addition of nutrients deposit to groundwater. may increase the rate of decay but investigations into such additions were outside the scope of this Geographical Variation project. Because areas of the coast differ in climatic conditions and in the type of sand found, an Eff ect of oil concentration extensive trial was carried out, in which small bags Extensive weathering of oil residues reduced the of OBS were buried at fi fteen sites around the British initial decomposition rate, indicating that the most coast from Shetland to Devon. These bags were volatile or soluble components were those which recovered at intervals and analysed for remaining are likely to be most readily metabolised by micro- hydrocarbon content. A collateral trial at a single organisms. Increasing concentration of site (Eskmeals) contained bags of OBS made from hydrocarbons in OBS, up to about 7.5% increased sands collected at all fiftee n sites. the rate of decomposition, but above this concentration there was rapid decrease in Results and observations degradation rate . This suggests there is an optimum starting concentration (between 5% and Main f indings 7.5%), for OBS to obtain maximum breakdown of Trials at all scales showed that micro-organisms hydrocarbons. (principally bacteria) with a capacity for hydrocarbon degradation were present in coastal Eff ect of Temperature sandy soils and that these populations responded Temperature had a clear infl uence on degradation rapidly to the presence of oil residues. In all cases, a rate, as demonstrated in laboratory and lysimeter rapid build-up of the microbial hydrocarbon experiments, where temperature could be degrader populations was accompanied by controlled or measured continuously. Seasonal enhanced soil respiration and a reduction in the temperature dependence is more likely to be concentration of hydrocarbons present in the soil. important than diurnal in terms of site management, and timing of disposal may be Pattern of Decay important in establishing the precise nature of the A common pattern of degradation was found, with decay curve.