Document: 17
Agenda:10
Reducing Methyl Bromide QPS Emissions
Discussion Paper by K.LGlassey 19.10.06
The aim of the Montreal Protocol is to protect the ozone layer from ozone depleting chemicals of which methyl bromide (MB) is an offender although there is still debate occurring over the role of the oceans in the production of the gas and acting as a sink. MB exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity (Anbar 1996). The climatic benefit of MB in the prevention of pest incursions that can seriously reduce carbon sequestion is not to be underestimated either.
Methyl bromide has been a highly effective fumigant used to control insects, nematodes, weed and pathogens in a huge range of commodities world wide for over 50 years. Its primary uses have been for soil fumigation, post-harvest protection, and quarantine treatments. The use of methyl bromide for quarantine and pre-shipment has been exempt from controls under the Montreal Protocol because of difficulties in identifying technological and economically feasible alternatives to the satisfaction of individual trading partners.
Reduction in the volume of MB used for soil fumigation has been the focus up until now with the developed countries were required to phase out by 1 January 2005 (largely achieved) and developing countries have until 2015 to achieve phase out. Progress in reducing consumption has been significant since 1991 consumption of 66,430 tonnes has been reduced to 24,635 tonnes in 2004 for controlled uses of which Quarantine and preshipment (QPS) is now estimated to be about half of the total use but likely to be higher due to difficulty in obtaining accurate data (TEAP 2006). Approximately 1500 tonnes of the current QPS use is for fumigating soil for reasons which are under debate
I believe that there is scope to reduce the methyl bromide emissions while retaining the use until such time as there are internationally accepted alternatives by applying a strategy to recapture, improve specifications and monitoring of both facilities and fumigations of official treatments, standardise treatment schedules and by reducing the illegal use of MB.
Recapture
One of the main reasons that soil fumigation has been the target is that it is virtually impossible to recover the gas once injected into the soil. This is in contrast to the established systems and standards in the Protocol and around the world for the recovery of other ozone depleting gases used in refrigerators etc such as CFC’s & HFC’s. QPS use has the distinct advantage over soil fumigation (as far as gas containment) in that the majority of fumigations occur in chambers, shipping containers, ships, other permanent structures or under “gas proof” covers on impervious surfaces. While there is sorption of a small quantity of MB into the commodity and varying amounts are leaked into the atmosphere depending on the gas tightness of the chamber or cover, the majority is available for recovery and destruction. This I believe should be the focus of users of the gas and custodians of the facilities that treat for QPS uses until acceptable alternatives are in place.
NPPO’s either own or approve the fumigation facilities for official treatments of both import and export commodities in their respective countries. Therefore they have the power to require recovery systems to be part of that approval; there are already many doing this mainly for safety or local environmental reasons. One of the major disadvantages is added cost but if recovery becomes standard practice it is likely to become cheaper and evens out the cost differences as far competition between products or countries. It also improves worker and environmental safety. There are now several recovery systems available and greater use would improve on this. Another distinct advantage is no registration is required compared to a new chemical or new use for an existing one. A side effect could be to make alternatives more attractive cost wise.
Recovery and destruction is the quickest way, within the control of NPPO’s, of adapting existing systems to reduce the emissions of methyl bromide into the atmosphere compared to implementing alternative treatments.
Improved specifications
Improved specifications and monitoring of both facilities and fumigations of official treatments would improve the accuracy and reliability to prevent over dosing, reduce emissions through less leakage and retreatments – both through failures at origin and retreatments on arrival at the destination due to pest detections. The Australian Fumigation Accreditation Scheme is an example of better specification and monitoring reducing the frequency of failure. The Vikane stewardship programme by Dow has improved the fumigation industry performance. ICPM could develop improved specifications for facilities, treatment operators and monitoring by NPPO’s.
Alignment of Fumigation Schedules
There are significant variations between the schedules specified by countries for the fumigation of the same product. For instance treatment specifications for softwood logs and sawn timber have not been harmonised world wide and vary between 25 /m3 for 24hrs at 12-15oC (Yu et al.) and 128g/m3 for a 24 hour exposure period at 210C (Malaysia). A suitable role for the ICPM would be to identify those schedules that would benefit most (from a reduction in MB use) from being aligned as this could be the quickest reduction in use of methyl bromide. This would involve assembly and acquisition of efficacy data in support of harmonisation of treatment specifications at an international level, for instance if 48gms (ISPM 15) is effective for the treatment of softwood logs then this could be standardized and save 63% of the volume of gas used for shipments of logs to some countries such as Malaysia and China. If MB schedules can be standardised between countries, excessive gas loadings can be avoided and fumigant use reduced. In New Zealand’s case this could save an estimated 80 tonnes per annum used in the log trade.
Illegal use
The definition of QPS is very clear (slight differences between the Protocol and IPPC definitions accepted). I believe that there are significant quantities of gas being used illegally as a general “clean up” by exporters prior to export to prevent detection of pests on arrival in the importing country (even though the country does not require methyl bromide fumigation), clean up by importers of imported products for non quarantine pests and blatant domestic use for controlling non quarantine pests. NPPO’s have some influence over the former but likely none over the latter as this responsibility is usually vested in other authorities. Some direction by the ICPM could be given to reduce the illegal use of MB and standardizing recording of QPS use for accurate reporting.
References
Anbar D, Yung YL, Chavez FP, Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity. Global Biogeochemical Cycles, Vol. 10, no. 1, pages 175–190, 1996
Yu KY, Chung YW, Lee MH, Jae JW. 1984. Study on shipboard fumigation of the imported logs. Korea J Plant Prot 23: 37-41
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