"Leaks and dumping of used lubricating oil from vehicles and other machinery are major sources of oil in urban runoff. Other sources include ruptures of storage tanks (e.g., at petrol stations), and, in some places, the use of used lubricating oil for dust control. Removing oil from storm drainage is not technically difficult where there is storm sewerage.
Constructing storm sewerage, however, requires large capital investment, and may not be feasible in low-lying areas that experience regular flooding, such as Bangkok and Bangladesh. In some places, it may be possible to construct interceptors in strategic locations, such as natural drainage channels, without needing to invest in storm sewerage.
Providing readily available waste oil reception facilities in urban areas can greatly reduce dumping of used motor oil, especially when combined with effectively enforced prohibitions on it, as already exist in some countries. Public education and economic incentives, such as a market for used oil, reduce the reliance on enforcement.
Other measures to reduce oil in urban runoff include maintenance standards for vehicles and petroleum facilities, and discontinuing the practice of applying used oil to roads for dust control. Deposit-refund schemes for used motor oil, or surcharges on the purchase of new oil (with the proceeds used to fund disposal facilities), may have potential; but they do not appear to have been widely tried.
[Page 104]
Although point sources are of great concern in some localities, anthropogenic flows of nutrients to the marine environment are dominated by non-point sources on global and regional scales. These cannot be addressed by simple end-of-pipe technological solutions and urgently require broad-scale changes in industrial practice, and in land and energy use. While continuing improvements in BEP [Best Environmental Practice] would be welcomed, great gains could be achieved by applying existing BEP and BAT [Best Available Technology] more widely, and especially by the transferring them effectively and rapidly transfer developing countries – a measure that will require international technical and financial assistance.
The costs and benefits of measures to address nutrient runoff from agriculture have not been adequately assessed, but it is reasonable to assume that their benefits would be substantially higher than their costs. Regarding atmospheric emissions, there are three broad, mutually reinforcing policies available: improving fuel pricing to reflect the environmental costs of its use; reducing urban congestion (e.g., through better urban planning and mass transport); and promoting clean fuel and engine technologies.
The costs of the first two policies are relatively low. The global phasing-in of cleaner fuels and engine technologies which reduce – but do not eliminate – nitrogen oxide emissions from vehicles, as well as further technological improvements, has been estimated by the World Bank to cost 0.5% of global GDP by 2010.
The World Bank has also calculated that phasing in reforms to rectify price inefficiencies and problems of accountability up to 2030 would make electricity production more efficient and reduce pollution, while raising incomes and human welfare. Introducing more environmentally friendly technologies and practices would produce additional pollution reductions. The Bank argues that the resultant savings in investment (e.g., in new power plants) – not to mention the benefits of pollution reduction itself – would far exceed the costs.
The two technical approaches to reducing industrial emissions, other than from power plants, are end-of-pipe controls and improvements in the industrial process. End-of-pipe controls can be expensive, but the industrial sectors of developing countries are advancing rapidly and each new investment offers the opportunity to incorporate cost-effective pollution abatement.
The World Bank has noted that developing countries should therefore be able to reduce emissions from large industrial plants at a lower cost than industrial countries, which are more dependent on fitting end-of-pipe controls to old plants. This will require developing countries to adopt appropriate policies to induce a proper combination of waste reduction and end-of-pipe controls.
Altered patterns of fertilizer use and application, cropping, tillage, and other agricultural practices would significantly reduce nutrient contamination of coastal areas. [Scientists in a 1997 study] describe an example from a sugar cane plantation where the subterranean delivery of fertilizer in dissolved form, together with timing application to coincide with crop growth, cut nitrogen fertilizer use by a third (improving profitability) and reduced runoff of nitrogen nutrients by a factor of ten. Applying existing best practice – and continued improvements in it – would have similar benefits in other industries; the specific measures that are appropriate vary widely among industries and from place to place.
Urban runoff is another significant non-point source of nutrients to coastal waters. The measures most likely to be effective include regular street sweeping, and others that reduce the concentration of nutrients in runoff, and storm-water management to slow the flow of runoff and promote ground penetration. Given reticulated storm sewerage, it is theoretically feasible to provide tertiary treatment, but not only would the costs be unacceptably high even in developed countries, but the large variations in flow rates would create considerable technical difficulties. Re-use of stormwater, for example for municipal irrigation, might reduce nutrient inputs, but would require both storm sewerage and infrastructure for water storage and delivery.
Improved environmental practice in agriculture and other industries can greatly reduce human-induced nutrient flow into marine areas, but probably never eliminate it. Wetlands, including mangroves, play a key natural role in intercepting and immobilizing dissolved nutrients in runoff and groundwater. A global strategy to reduce eutrophication and other problems associated with excessive nutrient inputs should place a priority on protecting and rehabilitating natural wetlands. The construction of artificial wetlands can also be an effective tool. Better drainage management is associated with this: it would, for
[Page 105]
example, reduce channelization and slow the flow of run-off to the marine environment, thereby allowing more time for natural assimilation and denitrification. A complicating factor is that wetlands typically convert dissolved nutrients into particulate organic form, which is exported to other systems: management and regulatory schemes should take this net export of particulate organic nutrients into account.
It is important to note that the same control measures will often be effective in addressing nutrient mobilization, sediment mobilization, and the physical alteration of habitats, because of the strong inter-relationships among them. In particular, measures that reduce sediment mobilization. will also address nutrient inputs. Reducing the alteration of physical habitats both cuts destabilization of soils at the habitat site and preserves the function of wetlands and other habitats in immobilizing nutrient and sediment flows from upstream.
Controlling atmospheric emissions of nitrogen poses a considerable challenge. Technological fixes – such as catalytic converters and more efficient vehicle engines, end-of-pipe interception and/or treatment (e.g., stack scrubbers), and cleaner industrial technologies – can achieve significant reductions.
It is unclear that many such measures are feasible in developing countries; certainly, international cooperation will be required.
Improved practice in fertilizer use and manure storage and handling to reduce emissions from agriculture are feasible in many countries, and reasonably readily transferable to many others. It is doubtful, however, that the available measures can reduce atmospheric nitrogen inputs to the ocean to a level where they are no longer a serious concern. What are probably required are significant societal changes in transport and energy use patterns, and/or major technological breakthroughs to control vehicle and industrial emissions."
GESAMP71:103-105
GESAMP (IMO/FAO/UNESCO-IOC/WMO/WHO/IAEA/ UN/UNEP Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection). 2001. Protecting the oceans from land-based activities - Land-based sources and activities affecting the quality and uses of the marine, coastal and associated freshwater environment. Rep. Stud. GESAMP No. 71, 162 pp. ISBN 82-7701-011-7.